8-K/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K/A

AMENDMENT NO. 1

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF

THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported) July 30, 2004

MARKWEST HYDROCARBON, INC.

(Exact name of registrant as specified in its charter)

Delaware	01-14841	84-1352233
(State or other jurisdiction of incorporation or organization)	(Commission File Number)	(I.R.S. Employer Identification Number)
155 Inverness Drive West, Suite 200, Englewood, CO 80112-5000
	(Address of principal executive offices)
Registrant’s telephone number, including area code: 303-290-8700

Not Applicable.

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

oWritten Communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

oSoliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

oPre-Commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

oPre-Commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 2.01.   ACQUISITION OR DISPOSITION OF ASSETS

On July 30, 2004, pursuant to the terms and conditions of the Asset Purchase and Sale Agreement (the “Agreement”) dated as of July 1, 2004, MarkWest Energy Partners, L.P. (the “Partnership”), a consolidated subsidiary of MarkWest Hydrocarbon, Inc. (“MarkWest Hydrocarbon”), completed the acquisition of American Central Eastern Texas Gas Company, Limited Partnership’s (“American Central Eastern Texas” or the “Seller”) Carthage gathering system and gas processing assets located in East Texas for approximately $240 million, including direct transaction costs and subject to certain post-closing adjustments.  The purchase price was determined through arm’s-length negotiations between the Partnership and American Central Eastern Texas.

The assets include the Carthage gathering system located in the East Texas county of Panola.  Substantially all of the Carthage gathering system has been constructed in the last 10 years and offers both low- and high-pressure service to producers in the Carthage Field, gathering gas from the Cotton Valley, Pettit and Travis Peak formations.  The acquired assets include 185 miles of existing natural gas gathering system pipelines connected to 1,730 wells with approximately 78 miles of additional pipeline under construction.  The natural gas gathering system includes 14 centralized compressor stations with a throughput capacity of 350 MMcf/d.  Average throughput volume for August 2004 was 245 MMcf/d.

The purchase price of approximately $240 million was financed through borrowings under the Partnership line of credit and a private placement of approximately 1.3 million of our common units, at $34.50 per unit, which netted us approximately $45.1 million after transaction costs and the general partner contribution.  The Partnership credit facility, which is administered by Royal Bank of Canada, was amended and restated concurrently with the closing of the acquisition to increase availability under the revolving credit facility from $140.0 million to $265.0 million and to add a term loan facility of $50.0 million, for an aggregate borrowing of $315.0 million.  Upon completion of the American Central Eastern Texas acquisition, outstanding borrowings under the Partnership’s new credit facility was $287.0 million.  All of the Partnership’s assets are pledged to the new credit facility lenders to secure the repayment of the outstanding borrowings under the credit facility.

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ITEM 9.01.  FINANCIAL STATEMENTS AND EXHIBITS

(a)  Financial Statements of Businesses Acquired.

Following are the audited financial statements of American Central Eastern Texas Gas Company, Limited Partnership for the three years in the period ended December 31, 2003.

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Report of Independent Registered Public Accounting Firm

Management Committee

American Central Eastern Texas Gas

Company, Limited Partnership

Tulsa, Oklahoma

We have audited the accompanying consolidated balance sheets of AMERICAN CENTRAL EASTERN TEXAS GAS COMPANY, LIMITED PARTNERSHIP as of December 31, 2003 and 2002, and the related consolidated statements of income, changes in partners’ equity, and cash flows for each of the three years in the period ended December 31, 2003.  These financial statements are the responsibility of the Partnership’s management.  Our responsibility is to express an opinion on these financial statements based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States).  Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement.  An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements.  An audit also includes assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation.  We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in all material respects, the financial position of AMERICAN CENTRAL EASTERN TEXAS GAS COMPANY, LIMITED PARTNERSHIP as of December 31, 2003 and 2002, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2003, in conformity with accounting principles generally accepted in the United States of America.

	/s/ BKD, LLP
Tulsa, Oklahoma
March 2, 2004

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American Central Eastern Texas Gas Company, Limited Partnership

Consolidated Balance Sheets

December 31, 2003 and 2002

	2003		2002
Assets
Current Assets
Cash	$	2,113,833	$	1,310,753
Accounts receivable - trade	6,918,027		5,480,104
Other current assets	168,108		171,042
Total current assets	9,199,968		6,961,899
Property and Equipment, At Cost
Gas systems	61,998,149		55,543,778
Furniture and fixtures	348,235		399,672
Construction in progress	770,784		5,067,970
	63,117,168		61,011,420
Less accumulated depreciation	12,230,534		9,347,780
	50,886,634		51,663,640
Other Assets	500,000		—
	$	60,586,602	$	58,625,539
Liabilities and Partners’ Equity
Current Liabilities
Accounts payable and accrued expenses	$	7,193,830	$	4,486,154
Accounts payable to general partner	593,891		364,420
Total current liabilities	7,787,721		4,850,574
Long-term Debt	827,950		—
Partners’ Equity	51,970,931		53,774,965
	$	60,586,602	$	58,625,539

The accompanying notes are an integral part of these financial statements.

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American Central Eastern Texas Gas Company, Limited Partnership

Consolidated Statements of Income

Years Ended December 31, 2003, 2002 and 2001

	2003			2002			2001
Revenues
Gas sales and gathering	$	16,737,939		$	15,914,855		$	14,099,247
Plant liquid sales	16,550,249			11,683,003			15,046,023
	33,288,188			27,597,858			29,145,270
Cost of Gas and Liquid Sales	12,357,605			7,898,335			12,720,379
Gross Profit	20,930,583			19,699,523			16,424,891
Operating Expenses
Cost of field operations	5,094,803			4,792,299			4,861,392
Depreciation	2,942,155			2,746,615			2,166,359
General and administrative	121,371			1,217,576			895,466
Management fee to general partner, net of amount capitalized	1,816,296			1,816,296			1,861,176
	9,974,625			10,572,786			9,784,393
Income from Operations	10,955,958			9,126,737			6,640,498
Other Income (Expense)
Interest income	11,667			12,836			189,773
Interest income from general partner	—			76,293			679,497
Litigation settlement	—			344,632			8,600,000
Legal expenses related to litigation settlement	—			—			(2,150,000		)
Net revenue interest payable	—			—			(1,500,000		)
Loss on sale of asset	(227,117		)	—			—
Other expense	(44,542		)	(140,146		)	—
	(259,992		)	293,615			5,819,270
Net Income	$	10,695,966		$	9,420,352		$	12,459,768
Net Income Per Partnership Unit	$	9,867		$	8,690		$	12,460

The accompanying notes are an integral part of these financial statements.

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American Central Eastern Texas Gas Company, Limited Partnership

Consolidated Statements of Changes in Partners’ Equity

Years Ended December 31, 2003, 2002 and 2001

Partners’ Equity, December 31, 2000	$	46,684,796
Conversion of net revenue interest payable to additional partnership units	18,900,000
Net income	12,459,768
Distributions to partners	(20,706,601		)
Partners’ Equity, December 31, 2001	57,337,963
Net income	9,420,352
Distributions to partners	(12,983,350		)
Partners’ Equity, December 31, 2002	53,774,965
Net income	10,695,966
Distributions to partners	(12,500,000		)
Partners’ Equity, December 31, 2003	$	51,970,931

The accompanying notes are an integral part of these financial statements.

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American Central Eastern Texas Gas Company, Limited Partnership

Consolidated Statements of Cash Flows

Years Ended December 31, 2003, 2002 and 2001

	2003			2002			2001
Operating Activities
Net income	$	10,695,966		$	9,420,352		$	12,459,768
Items not requiring cash
Depreciation	2,942,155			2,746,615			2,166,359
Loss on asset exchange	227,117			—			—
Changes in
Accounts and accrued interest receivable – trade and related parties	(1,437,923		)	(1,058,642		)	3,544,955
Other assets	(523,068		)	180,584			145,863
Accounts payable and accrued expenses – trade and related parties	3,402,085			1,940,921			(4,166,566		)
Net revenue interest payable	—			—			1,500,000
Net cash provided by operating activities	15,306,332			13,229,830			15,650,379
Investing Activities
Principal payment received on note receivable	—			6,158,349			8,583,231
Purchase of property and equipment	(3,117,124		)	(5,427,213		)	(11,912,515		)
Net change in short-term certificates of deposit	—			—			1,597,878
Proceeds from sale of assets	285,920			—			—
Net cash provided by (used in) investing activities	(2,831,204		)	731,136			(1,731,406		)
Financing Activities
Proceeds from long-term debt	2,015,000			—			—
Principal payments on long-term debt	(1,187,048		)	—			—
Distributions to partners	(12,500,000		)	(12,983,350		)	(20,706,601		)
Net cash used in financing activities	(11,672,048		)	(12,983,350		)	(20,706,601		)
Increase (Decrease) in Cash and Cash Equivalents	803,080			977,616			(6,787,628		)
Cash and Cash Equivalents, Beginning of Year	1,310,753			333,137			7,120,765
Cash and Cash Equivalents, End of Year	$	2,113,833		$	1,310,753		$	333,137
Supplemental Cash Flows Information
Purchases of property and equipment in accounts payable	$	64,933		$	529,872		$	294,159
Conversion of net revenue interest payable to limited partnership units	$	—		$	—		$	18,900,000

The accompanying notes are an integral part of these financial statements.

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American Central Eastern Texas Gas Company, Limited Partnership

Notes to Consolidated Financial Statements

December 31, 2003, 2002 and 2001

Note 1:  Nature of Operations and Summary of Significant Accounting Policies

Nature of Operations

American Central Eastern Texas Gas Company, Limited Partnership’s (the “Partnership”) revenues are predominantly earned from gathering and processing natural gas and processing natural gas and marketing (selling) extracted liquefied petroleum products. The Partnership’s operations are located in eastern Texas. The Partnership extends unsecured credit to its customers, which are primarily comprised of several publicly traded national and international oil, gas and energy companies.

The Partnership was formed under a partnership agreement effective December 1, 1997, between American Central Gas Technologies, Inc. (ACGT, formerly American Central Gas Companies, Inc.), MCNIC East Texas Pipeline and Processing Company (MCNIC), ACGC Holdings, Inc. (ACGC Holdings), and MCNIC East Texas Gathering Company Holdings, Inc. (MTGC).  In exchange for a contribution of primarily property and equipment, ACGT and ACGC Holdings received 600 partnership units.  MCNIC and MTGC made a cash contribution in exchange for 400 partnership units.  In December 2001, MTGC was issued an additional 84 partnership units as payment of the Partnership’s net revenue interest payable obligation to MTGC, increasing MCNIC and MTGC partnership units to 484.  The agreement further stipulates that there are to be two general partners and two limited partners.  ACGT and MCNIC are the general partners, each owning one ownership unit.  ACGT is the managing general partner.  At December 31, 2003 and 2002, ACGC Holdings and MTGC are the limited partners owning 599 and 483 partnership units, respectively.  The term for the existence of the partnership is through December 31, 2038, or until earlier termination in accordance with certain provisions of the partnership agreement.

The partnership agreement between ACGT, MCNIC, ACGC Holdings and MTGC (the Partners) provides for special allocations of the Partnership’s net income or loss and the payment of cash distributions, which differ from each partner’s percentage ownership of the Partnership.  In addition, ACGT, as managing general partner, may require that additional capital be contributed by the Partners under certain conditions.

In January 2004, ACGT purchased both MCNIC’s and MTGC’s interest in the Partnership and, as a result, owns 100% of the Partnership (See Note 8).

Principles of Consolidation

The consolidated financial statements include the accounts of the Partnership and its wholly owned subsidiary, American Central Gas Gathering Company, LLC.  All significant inter-company accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

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Cash Equivalents

The Partnership considers all liquid investments with original maturities of three months or less to be cash equivalents.  At December 31, 2003 and 2002, the Partnership had no cash equivalents.  At December 31, 2001, cash equivalents consisted primarily of money market accounts with brokers and certificates of deposit.

Accounts Receivable

Accounts receivable are stated at the amount billed to customers plus any accrued and unpaid interest. The Partnership provides an allowance for doubtful accounts, which is based upon a review of outstanding receivables, historical collection information, and existing economic conditions. Accounts receivable are ordinarily due 30 days after the issuance of the invoice.  Accounts that are unpaid after the due date bear interest at 1% per month.  Accounts past due more than 120 days are considered delinquent. Interest continues to accrue on delinquent accounts until the account is past due more than one year, at which time interest accrual ceases and does not resume until the account is no longer classified as delinquent. Delinquent receivables are written off based on individual credit evaluation and specific circumstances of the customer.

Property and Equipment

The Partnership provides for depreciation using the straight-line method over the estimated useful lives of the assets, which are as follows:

	Years
Gas systems	20
Furniture and fixtures	5

Fair Value of Financial Instruments

The carrying amount of the Partnership’s financial instruments is a reasonable estimate of fair value.

Income Taxes

The Partnership is not directly subject to income taxes under the provisions of the Internal Revenue Code and applicable state laws.  Therefore, taxable income or loss is reported to the individual partners for inclusion in their respective tax returns and no provision for federal and state income taxes has been included in the accompanying financial statements.

Revenue Recognition

The Partnership recognizes revenues based upon contractual terms and the related volumes delivered through the month and year-end.

Other Assets

Other assets consist of loan fees paid to establish a new credit facility and will be amortized over the life of the new facility (See Note 2).

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Note 2:  Long-Term Debt

Long-term debt consists of an unsecured note payable to a bank for $827,950 due March 2008.  The note is payable $37,399 monthly, including interest at 4.25%.  This debt was paid off with a new credit facility in January 2004.

In January 2004, the Partnership entered into a new credit facility with an initial draw of $46,700,000 (see Note 9).  Interest only payments will be made monthly until the due date of the note when the principal balance will be paid in full.  The note is secured by substantially all assets of the Partnership and guaranteed by ACGT.  The note is due January 2007 and, as a result, all long-term debt at December 31, 2003, is classified as long-term with no current maturities.

Note 3:  Operating Leases

Noncancellable operating leases for equipment, automobiles and land expire in various years through 2008.  Rent expense for the noncancellable leases and other operating leases in 2003, 2002 and 2001 was $1,014,585, $1,244,048, and $1,408,128, respectively.

Future minimum lease payments on the noncancellable operating leases at December 31, 2003, were:

2004	$	883,636
2005	628,852
2006	47,093
2007	20,750
2008	2,750
	$	1,583,081

Note 4:  Related Party Transactions

The Partnership enters into various transactions with ACGT and certain affiliated companies.  The Partnership pays a management fee to ACGT for services rendered as the managing general partner of the Partnership. The Partnership paid ACGT management fees of approximately $2,017,000 for both 2003 and 2002, and approximately $2,062,000 during 2001.  Management fees of approximately $201,000 were capitalized in property and equipment for each of the three years.  No management fees were payable to ACGT at December 31, 2003 or 2001.  Included in accounts payable at December 31, 2002, was $336,151 payable to ACGT for management fees.  Under the terms of the management agreement, amounts paid relating to management fees may be adjusted on a quarterly basis, and the Partnership will continue to pay the management fees for the life of the Partnership.  Additionally, the Partnership reimburses ACGT for all direct operating expenses incurred by ACGT on behalf of the Partnership, of which $593,891, $28,269 and $364,242 was payable at December 31, 2003, 2002, and 2001, respectively.

Note 5:  Litigation Settlement

In March 2001, the Partnership entered into a settlement and release agreement with two of the three defendant parties to release them from all claims and litigation arising from the monopolizing of a trade area.  As a result of this agreement, the Partnership received $8,600,000.  The Partnership has an agreement with the law firm that represented them in the litigation requiring a 25% retainer of proceeds

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from the settlement.  In March 2001, the Partnership paid the 25% or $2,150,000 to the law firm for this retainer.  The Partnership engaged in settlement discussions with the third defendant of the monopoly finding, and the initial arbitrator’s ruling was appealed.  In January 2004, the United Sates Court of Appeals affirmed the arbitrator’s ruling.

During 2002, the Partnership received $344,632 in additional awards relating to a binding arbitration agreement that was reached in August 2000 between the Partnership and a natural gas processor.

Note 6:  Earnings Per Partnership Unit

Earnings per partnership unit is computed based on the weighted average number of units outstanding during each year.  Earnings per unit is computed as follows:

	2003		2002		2001
Net income	$	10,695,966	$	9,420,352	$	12,459,768
Average partnership units outstanding	1,084		1,084		1,000
Earnings per partnership unit	$	9,867	$	8,690	$	12,460

Note 7:  Significant Estimates and Concentrations

Accounting principles generally accepted in the United States of America require disclosure of certain significant estimates and current vulnerabilities due to certain concentrations. Those matters include the following:

General Litigation

The Partnership is subject to claims and lawsuits that arise primarily in the ordinary course of business.  It is the opinion of management that the disposition or ultimate resolution of such claims and lawsuits will not have material adverse effect on the consolidated financial position of the Partnership.

Major Customers

For the year ended December 31, 2003, three of the Partnership’s customers individually comprised approximately 50%, 14%, and 16%, respectively, of gross revenues.  Three customers individually comprised approximately 42%, 19%, and 16%, respectively, of the Partnership’s gross revenues for the year ended December 31, 2002.  Two customers individually comprised approximately 70% and 11%, respectively, of the Partnership’s gross revenues for the year ended December 31, 2001.  At December 31, 2003, one customer comprised approximately 52% of total accounts receivable.  At December 31, 2002, one customer comprised approximately 45% of total accounts receivable.  At December 31, 2001, two customers individually comprised approximately 33% and 20%, respectively, of total accounts receivable.

Cash Deposits

The Partnership maintains its cash in bank deposit accounts which, at times, may exceed federally insured limits. The Partnership has not experienced any losses in such accounts. The Partnership believes it is not exposed to any significant credit risk on cash and cash equivalents.

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Note 8:  Net Revenue Interest Payable

MCNIC and MTGC had a net revenue interest (NRI) in the gross revenues of the Partnership as a result of special provisions included in the partnership agreement.  Under the terms set forth in the agreement, the NRI was allocated to MCNIC and MTGC.  The NRI allocation period was defined as the time from December 1, 1997 through December 31, 2001.  Allocated amounts are specifically defined in the partnership agreement, and these amounts were accruing monthly as a liability of the Partnership.  In December 2001, the managing general partner (ACGT), as provided for in the partnership, elected to pay off the NRI liability by issuing additional units of ownership in the Partnership which resulted in MTGC receiving an additional 84 partnership units.

Note 9:  Subsequent Event

In January 2004, the Partnership entered into a credit facility for $75,000,000.  The initial borrowing base was $50,000,000 and $46,700,000 was the initial draw on the new facility.  The purpose of the borrowing was to purchase all the Partnership interests of MCNIC and MTGC and pay off existing debt of the Partnership and ACGT (See Notes 1 and 2).

Interest rates vary depending on a pricing grid that changes based on a ratio of debt-to-defined earnings and LIBOR.  The initial rate was 4.125%.

A summary of the initial borrowing and use of proceeds is:

Initial borrowing	$	46,700,000
Purchase MCNIC and MTGC partnership interests	$	26,416,515
Distribution to ACGT to pay off existing debt of ACGT	18,721,442
Pay off existing debt of the Partnership	794,350
Fees associated with the credit arrangement	757,740
	$	46,690,047

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Report of Independent Registered Public Accounting Firm

Management Committee

American Central Eastern Texas

Gas Company, Limited Partnership

Tulsa, Oklahoma

We have reviewed the accompanying consolidated balance sheet of AMERICAN CENTRAL EASTERN TEXAS GAS COMPANY, LIMITED PARTNERSHIP (the Partnership) as of June 30, 2004, and the related consolidated statements of income and cash flows for the six-month periods ended June 30, 2004 and 2003, and changes in partners’ equity for the six-month period ended June 30, 2004.  These interim financial statements are the responsibility of the Partnership’s management.

We conducted our reviews in accordance with the standards of the Public Company Accounting Oversight Board (United States).  A review of interim financial information consists principally of applying analytical procedures to financial data and making inquiries of persons responsible for financial and accounting matters.  It is substantially less in scope than an audit conducted in accordance with the standards of the Public Company Accounting Oversight Board, the objective of which is the expression of an opinion regarding the financial statements taken as a whole.  Accordingly, we do not express such an opinion.

Based on our reviews, we are not aware of any material modifications that should be made to the consolidated financial statements referred to above for them to be in conformity with accounting principles generally accepted in the United States of America.

	/s/ BKD, LLP
Tulsa, Oklahoma
July 23, 2004

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American Central Eastern Texas Gas Company,

Limited Partnership

Consolidated Balance Sheet

June 30, 2004

	(Unaudited) June 30, 2004
Assets
Current Assets
Cash	$	9,054,889
Accounts receivable - trade	6,312,710
Other current assets	91,451
Total current assets	15,459,050
Property and Equipment, at Cost
Gas systems	61,934,136
Furniture and fixtures	348,235
Construction in progress	9,374,506
	71,656,877
Less accumulated depreciation	13,542,487
	58,114,390
Other Assets	416,667
	$	73,990,107
Liabilities and Partners’ Equity
Current Liabilities
Accounts payable and accrued expenses	$	5,403,329
Accounts payable to general partner	363,437
Total current liabilities	5,766,766
Long-term Debt	55,000,000
Partners’ Equity	13,223,341
	$	73,990,107

See Notes to Condensed Financial Statements

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American Central Eastern Texas Gas Company,

Limited Partnership

Consolidated Statements of Income

Six Months Ended June 30, 2004 and 2003

	(Unaudited) June 30, 2004			(Unaudited) June 30, 2003
Revenues
Gas sales and gathering	$	13,832,255		$	8,009,056
Plant liquid sales	3,273,358			9,185,476
	17,105,613			17,194,532
Cost of Gas and Liquid Sales	2,431,944			6,969,436
Gross Profit	14,673,669			10,225,096
Operating Expenses
Cost of field operations	3,143,167			2,460,555
Depreciation and amortization	1,657,313			1,404,719
General and administrative	252,659			107,316
Management fee to general partner, net of amount capitalized	1,468,287			908,148
	6,521,427			4,880,738
Income from Operations	8,152,242			5,344,358
Other Income (Expense)
Interest expense	(925,069		)	(19,754		)
Loss on sale of assets	(136,806		)	(15,517		)
	(1,061,875		)	(35,271		)
Net Income	$	7,090,367		$	5,309,087
Net Income Per Partnership Unit	$	6,541		$	4,898

See Notes to Condensed Financial Statement

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American Central Eastern Texas Gas Company,
Limited Partnership

Consolidated Statement of Changes in Partners’ Equity

Six Months Ended June 30, 2004

Partners’ Equity, December 31, 2003	$	51,970,931
Net income	7,090,367
Distributions to partners	(19,421,442		)
Purchase MCNIC and MTGC partnership interest	(26,416,515		)
Partners’ Equity, June 30, 2004 (Unaudited)	$	13,223,341

See Notes to Condensed Consolidated Financial Statements

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American Central Eastern Texas Gas Company,
Limited Partnership

Consolidated Statements of Cash Flows

Six Months Ended June 30, 2004 and 2003

	(Unaudited)			(Unaudited)
	June 30, 2004			June 30, 2003
Operating Activities
Net income	$	7,090,367		$	5,309,087
Items not requiring cash
Depreciation and amortization	1,657,313			1,404,719
Loss on sale of assets	136,806			15,517
Changes in
Accounts receivable, net	605,317			200,449
Other current assets	76,657			15,525
Accounts payable and accrued expenses	(2,826,327		)	775,553
Net cash provided by operating activities	6,740,133			7,720,850
Investing Activities
Proceeds from the sale of assets	549,943			35,918
Purchase of property and equipment	(8,683,113		)	(2,485,313		)
Net cash used in investing activities	(8,133,170		)	(2,449,395		)
Financing Activities
Proceeds from long-term debt	55,000,000			2,015,000
Principal payments on long-term debt	(827,950		)	(90,979		)
Distributions to partners	(19,421,442		)	(6,400,000		)
Purchase MCNIC and MTGC partnership interest	(26,416,515		)	—
Net cash provided by (used in) financing activities	8,334,093			(4,475,979		)
Increase in Cash	6,941,056			795,476
Cash, Beginning of Period	2,113,833			1,310,753
Cash, End of Period	$	9,054,889		$	2,106,229
Supplemental Cash Flows Information
Purchases of property and equipment in accounts payable	$	870,306		$	71,101

See Notes to Condensed Consolidated Financial Statements

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American Central Eastern Texas Gas Company, Limited Partnership

Notes to Consolidated Financial Statements

Six Months Ended June 30, 2004 and 2003

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements reflect all adjustments that are, in the opinion of the Partnership’s management, necessary to fairly present the financial position, results of operations and cash flows of the Partnership.  Those adjustments consist only of normal recurring adjustments.

Certain information and note disclosures normally included in the Partnership’s annual financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted.  These financial statements should be read in conjunction with the financial statements and notes thereto included in the Partnership’s annual financial statements.

The consolidated financial statements include the accounts of the Partnership and its wholly owned subsidiary, American Central Gas Gathering Company, LLC.  All significant intercompany accounts and transactions have been eliminated in consolidation.

Results of Operations

The results of operations for the interim period are not necessarily indicative of the results to be expected for the full year.

Earnings Per Partnership Unit

Earnings per partnership unit is computed based on the weighted average number of units outstanding during each year.  Earnings per unit is computed as follows:

	Unaudited		Unaudited
	June 30, 2004		June 30, 2003
Net income	$	7,090,367	$	5,309,087
Average partnership units outstanding	1,084		1,084
Earnings per partnership unit	$	6,541	$	4,898

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Item 9.01 Financial Statements and Exhibits.

(b)Pro Forma Financial Information.

The following are the unaudited pro forma financial statements as of June 30, 2004, for the six months ended June 30, 2004 and for the year ended December 31, 2003.

The unaudited pro forma consolidated balance sheet as of June 30, 2004 reflects the following transactions as if such transactions occurred as of June 30, 2004:

•the American Central Eastern Texas Gas Company, Limited Partnership acquisition (“American Central Eastern Texas acquisition”), which closed July 30, 2004, for consideration of $239.6 million, plus $0.4 million in estimated transaction costs,

•borrowings of $200.8 million under the Partnership’s new credit facility to partially finance the American Central Eastern Texas acquisition, and

•the Partnership’s private placement of 1,304,438 common units and a capital contribution from us, as general partner, to maintain our 2% general partner interest, the net proceeds from which were used to partially finance the American Central Eastern Texas acquisition.

The unaudited pro froma consolidated statements of operations for the six months ended June 30, 2004, and the year ended December 31, 2003, reflects the following transactions as if such transactions occurred as of January 1, 2003:

•the American Central Eastern Texas acquisition, which closed July 30, 2004, for consideration of $239.6 million, plus $0.4 million in estimated transaction costs,

•borrowings of $200.8 million under our new credit facility to partially finance the American Central Eastern Texas acquisition,

•the Partnership’s private placement of 1,304,438 common units and a capital contribution from us, as general partner, to maintain our 2% general partner interest, the net proceeds from which were used to partially finance the American Central Eastern Texas acquisition,

•the American Central Western Oklahoma Gas Company, L.L.C. acquisition (“American Central Western Oklahoma acquisition”), which closed December 1, 2003, for consideration of $37.9 million, plus $0.1 million in transaction costs,

•the Michigan Crude Pipeline System acquisition (“Michigan Crude Pipeline acquisition”), which closed December 18, 2003, for consideration of $21.2 million, plus $0.1 million in transaction costs,

•borrowings of $59.3 million under the Partnership’s credit facility to finance the American Central Western Oklahoma and Michigan Crude Pipeline acquisitions,

•the Partnership’s public offering of 1,172,944 common units on January 13, 2004 at a public offering price of $39.90 per common unit and a capital contribution from us, as general partner, to maintain our 2% general partner interest, the net proceeds from which were used to repay indebtedness incurred in connection with the American Central Western Oklahoma and Michigan Crude Pipeline acquisitions,

•the payment of underwriting fees and commission, and other fees and expenses associated with the January 2004 offering, of approximately $3.8 million,

20

•the Pinnacle acquisition, which closed March 28, 2003, for consideration of $39.5 million, plus $0.4 million in transaction costs, and

•the Partnership’s private placement in June 2003 of 375,000 common units and a capital contribution from us, as general partner, to maintain our 2% general partner interest, the net proceeds from which were used to repay indebtedness incurred in connection with the Pinnacle acquisition.

Adjustments for these transactions are presented in the notes to the unaudited pro forma financial statements. The unaudited pro forma financial statements and accompanying notes should be read in conjunction with the historical financial statements included in MarkWest Hydrocarbon’s previous filings with the Securities and Exchange Commission and the audited American Central Eastern Texas Gas Company, Limited Partnership financial statements included herein.

Information under the headings “Pinnacle” in the pro forma financial statement presentation are the results of operations of PNG Corporation and its subsidiaries which we refer to collectively as PNG.  Although Pinnacle represents most of PNG’s assets, liabilities and operations, we excluded from our acquisition certain liabilities and assets, and accordingly, we have made pro forma adjustments to the historical financial statements for PNG to exclude the impact of those liabilities and assets we did not acquire.  Most significantly, we did not assume any pre-merger tax liabilities or any liabilities associated with an existing lawsuit against PNG.  In addition, we did not acquire the property and contract rights associated with the Hobbs, New Mexico lateral pipeline, although we were providing certain operating services to the Hobbs pipeline operation.  Finally, the financial information presented under the heading “Pinnacle” in these unaudited proforma statements of operations represents PNG’s results of operations for the first three months of 2003.  The results of operations for Pinnacle for the period from March 28, 2003, the date we completed the Pinnacle acquisition, through June 30, 2004, are included in our historical results of operations.  We have made pro forma adjustments to eliminate the four days of results, March 28, 2003 through March 31, 2003, that are included in PNG’s historical results.

Similarly, the information presented under the headings “Eastern Texas”, “Western Oklahoma” and “Michigan Crude Pipeline” represent the results of operations of American Central Eastern Texas Gas Company, L.P., American Central Western Oklahoma Gas Company, L.L.C. and the Michigan Crude Oil Pipeline System, respectively, for the year ended December 31, 2003.  In these cases there were no material items other than working capital that we excluded from these acquisitions and, accordingly, we have not further adjusted the historical results of operations for Eastern Texas, Western Oklahoma or the Michigan Crude Oil Pipeline.  The results of operations for Western Oklahoma and Michigan Crude Oil Pipeline for the period from December 1, 2003 and December 18, 2003, the dates we completed the American Central Western Oklahoma acquisition and the Michigan Crude Pipeline acquisition, respectively, through June 30, 2004, are included in our historical results of operations.

In addition, while our historical consolidated balance sheet reflects our $12.2 million Lubbock pipeline acquisition in September 2003, our pro forma statements of operations present the effect of this acquisition since the date of acquisition. Similarly, our historical consolidated balance sheet also reflects our $2.3 million Hobbs Lateral acquisition in April 2004, while our pro forma statements of operations present the effect of this acquisition since the date of acquisition.  These acquisitions did not meet the applicable materiality thresholds that would require inclusion in these unaudited pro forma statements of operations.

The pro forma balance sheet and the pro forma statements of operations were derived by adjusting the historical financial statements of MarkWest Hydrocarbon, Inc.  The adjustments are based on currently available information and, therefore, the actual adjustments may differ from the pro forma adjustments.  However, management believes that the adjustments provide a reasonable basis for presenting the significant effects of the transactions described above.  The unaudited pro forma financial statements do not purport to present our financial position or results of operations had the acquisitions or the other transactions actually been completed as of the dates indicated.  Moreover, the statements do not project our financial position or results of operations for any future date or period.

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MARKWEST HYDROCARBON, INC.

UNAUDITED PRO FORMA CONSOLIDATED BALANCE SHEET

June 30, 2004

(in thousands)

	MarkWest Hydrocarbon, Inc.			Eastern Texas		Pro Forma Adjustments			Pro Forma
ASSETS
Current assets:
Cash and cash equivalents	$	33,777		$	9,055	$	(9,055	)(A)	$	30,226
						(45,057		)(B)
						(3,551		)(C)
						45,003		(E)
						(864		)(E)
						918		(E)
Restricted cash	2,500			—					2,500
Marketable securities	13,809			—					13,809
Receivables, net	28,300			6,313		(6,313		)(A)	30,401
						2,101		(B)
Inventories	9,112			—					9,112
Prepaid replacement natural gas	264			—					264
Deferred income taxes	178			—		385		(F)	563
Other assets	415			91		(91		)(A)	415
Total current assets	88,355			15,459		(16,524		)	87,290
Property, plant and equipment, net	189,900			58,114		18,519		(B)	266,533
Customer contracts, net	—			—		163,343		(B)	163,343
Deferred financing costs, net	3,178			—		7,188		(C)	9,470
						(896		)(D)
Investment in and advances to equity investee	232			—					232
Notes receivable from officers	207			—					207
Other assets	42			417		(417		)(A)	42
Total assets	$	281,914		$	73,990	$	171,213		$	527,117
LIABILITIES AND CAPITAL
Current liabilities:
Accounts payable	$	31,237		$	5,403	$	(5,403	)(A)	$	31,237
Payables to affiliate	—			364		(364		)(A)	—
Accrued liabilities	16,863			—					16,863
Risk management liabilities	748			—					748
Current portion of long-term debt	86,200			—		197,020		(B)	287,000
						3,780		(C)
Total current liabilities	135,048			5,767		195,033			335,848
Deferred income taxes	5,105			—					5,105
Long-term debt	—			55,000		(55,000		)(A)	—
Risk management liability	397			—					397
Other liabilities	501			—					501
Non-controlling interest in consolidated subsidiary	94,140			—		(143		)(C)	138,543
						(896		)(D)
						45,003		(E)
						(864		)(E)
						918		(E)
						385		(F)
Commitments and contingencies
Stockholders’ equity
Preferred stock	—			—					—
Common stock/partner’s equity	98			13,223		(13,223		)(A)	98
Additional paid-in capital	52,259			—					52,259
Retained earnings	(3,782		)	—					(3,782		)
Accumulated other comprehensive loss net of tax	(1,395		)	—					(1,395		)
Treasury stock	(457		)	—					(457		)
Total stockholders’ equity	46,723			13,223		(13,223		)	46,723
Total liabilities and stockholders’ equity	$	281,914		$	73,990	$	171,213		$	527,117

The accompanying notes are an integral part of these unaudited pro forma consolidated financial statements.

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MARKWEST HYDROCARBON, INC.

UNAUDITED PRO FORMA STATEMENT OF OPERATIONS

Six Months Ended June 30, 2004

(in thousands, except per unit data)

	MarkWest Hydrocarbon, Inc.			Eastern Texas			Pro Forma Adjustments			Pro Forma
Revenue	$	181,484		$	17,105		$	—		$	198,589
Operating expenses:
Purchased product costs	150,587			2,432						153,019
Facility expenses	11,866			3,143						15,009
Selling, general and administrative	8,746			253						8,999
Depreciation and amortization	7,410			1,657			4,041		(G)	13,108
Management fee to general partner, net of amount capitalized	—			1,468						1,468
Total operating expenses	178,609			8,953			4,041			191,603
Income (loss) from operations	2,875			8,152			(4,041		)	6,986
Other income (expense):
Interest expense, net	(2,450		)	(925		)	(3,115		)(H)	(6,490		)
Non-controlling interest in net income of consolidated subsidiary	(4,242		)	—						(4,242		)
Other income (expense)	32			(137		)				(105		)
Total other expense	(6,660		)	(1,062		)	(3,115		)	(10,837		)
Income (loss) before income taxes	(3,785		)	7,090			(7,156		)	(3,851		)
Provision (benefit) for income taxes	(1,372		)	—			(24		)(F)	(1,396		)
Net income (loss)	$	(2,413	)	$	7,090		$	(7,132	)	$	(2,455	)
Net loss per share:
Basic	$	(0.25	)							$	(0.25	)
Diluted	$	(0.25	)							$	(0.25	)
Weighted average number of outstanding shares of common stock:
Basic	9,662									9,662
Diluted	9,662									9,662

The accompanying notes are an integral part of these unaudited proforma consolidated financial statements.

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MARKWEST HYDROCARBON, INC.

UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF OPERATIONS

Year Ended December 31, 2003

(in thousands, except per unit data)

	MarkWest Hydrocarbon, Inc.			Pinnacle			Western Oklahoma		Michigan Crude Pipeline		Eastern Texas			Pro Forma Adjustments			Offering Adjustments			Pro Forma As Adjusted
Revenues	$	207,651		$	18,614		$	37,016	$	4,229	$	33,288		$	(51	)(I)	$	—		$	299,920
														(827		)(J)
Operating expenses:
Purchased product costs	187,544			15,305			30,203		—		12,358			(680		)(J)				244,730
Facility expenses	19,977			885			2,677		1,790		5,095			(9		)(I)				30,376
														(39		)(J)
Selling, general and administrative expenses	14,465			336			135		937		122			(12		)(J)				15,983
Depreciation and amortization	8,333			1,031			2,154		599		2,942			8,454		(G)				23,636
														(52		)(I)
														(46		)(J)
														221		(K)
Management fee	—			—			1,713		—		1,816									3,529
Impairment	1,148			—			—		—		—									1,148
Total operating expenses	231,467			17,557			36,882		3,326		22,333			7,837			—			319,402
Income (loss) from operations	(23,816		)	1,057			134		903		10,955			(8,715		)	—			(19,482		)
Other income (expense):
Interest income (expense), net	(6,345		)	(269		)	10		—		12			(15,073		)(H)	409		(M)	(23,332		)
														(3,786		)(L)	1,710		(N)
Gain on sale of non-operating assets to related parties	382			—			—		—		—									382
Gain on sale of non-operating assets to related parties	(3,236		)	—			—		—		—									(3,236		)
Other income (expense)	(92		)	18			—		—		(272		)							(346		)
Total other income (expense)	(9,291		)	(251		)	10		—		(260		)	(18,859		)	2,119			(26,532		)
Income (loss) before income taxes	(33,107		)	806			144		903		10,695			(27,574		)	2,119			(46,014		)
Provision (benefit) for income taxes	(12,209		)	294			—		—		—			(5,858		)(F)	784		(F)	(16,989		)
Net income (loss)	$	(20,898	)	$	512		$	144	$	903	$	10,695		$	(21,716	)	$	1,335		$	(29,025	)
Net loss per share:
Basic	$	(2.23	)																	$	(3.09	)
Diluted	$	(2.23	)																	$	(3.09	)
Weighted average number of outstanding shares of common stock:
Basic	9,389																			9,389
Diluted	9,389																			9,389

The accompanying notes are an integral part of these unaudited pro forma consolidated financial statements.

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MARKWEST HYDROCARBON, INC.

NOTES TO UNAUDITED PRO FORMA FINANCIAL STATEMENTS

Pro Forma Adjustments

Unaudited Pro Forma Balance Sheet:

(A)Reflects the elimination of the American Central Eastern Texas assets, liabilities and equity that we did not acquire.

(B)Reflects the acquisition and the related financing (cash consideration and estimated direct acquisition costs were financed by borrowings under our credit facility and from proceeds from a private equity placement) of the American Central Eastern Texas assets.  The consideration paid, the purchase price allocation and funding source for the acquisition were as follows (in thousands):

Acquisition costs:
Cash consideration	$	239,580
Direct acquisition costs	396
Total	$	239,976
Allocation of acquisition costs(1):
Identifiable intangible assets	$	163,343
Property, plant and equipment	76,633
Net assets purchased	$	239,976
Funding sources:
Borrowings under the credit facility	$	197,020
Proceeds from private equity placement and general partner contribution, net (See note E)	45,057
Receivable from seller (2)	(2,101		)
Total	$	239,976

(1)This acquisition was accounted for as a purchase in accordance with Statement of Financial Accounting Standards No. 141, Business Combinations.  The purchase price allocation is based on the fair values of the assets acquired, including the fair values of identifiable intangibles as of July 30, 2004, the date that the acquisition was consummated.  The pro forma allocation of the purchase price is preliminary and subject to audit.

(2)Under the Asset Purchase and Sale Agreement, the Partnership, as the buyer, is entitled to operating income and expenses related to the first day of the month of closing through the closing date.  As the acquisition closed on July 30, 2004, the operating activity related to July 2004 is an adjustment to the purchase price and recorded as a receivable from the Seller.

(C)Reflects the payment of $7.2 million capitalized as deferred financing costs and approximately $0.2 million recorded as interest expense related to the Partnership’s debt refinancing for the American Central Eastern Texas acquisition ($3.6 million paid out of existing cash and $3.8 million borrowed under the Partnership’s credit facility).

(D)Relates to unamortized deferred financing costs written off to interest expense as a result of the debt refinancing for the American Central Eastern Texas acquisition.

(E)Reflects the gross proceeds of $45.0 million from the issuance and sale of 1,304,438 common units at a private placement price of $34.50 per common unit, net of estimated offering expenses of $0.9 million, and the contribution of $0.9 million from us, as general partner, in order to maintain our 2% general partner interest.

25

Unaudited Pro Forma Statement of Operations:

(F)The income tax provision (benefit) generated from the aggregate effects of the American Central Eastern Texas results of operations and the associated pro forma adjustments.

(G)Reflects the pro forma adjustment to American Central Eastern Texas depreciation expense, as follows:

	Six Months Ended June 30, 2004			Year Ended December 31, 2003
	(in thousands)
Eliminate historical depreciation expense	$	(1,657	)	$	(2,942	)
Pro forma depreciation expense(1)	5,698			11,396
Pro forma adjustment to depreciation expense	$	4,041		$	8,454

(1)Pro forma depreciation is based on the lesser of the term of the associated long-term contract or estimated reserves supporting our asset or the asset’s useful life, which is twenty years for property and equipment.

(H)The pro forma adjustment to American Central Eastern Texas interest expense for the periods presented is calculated as follows:

	Six Months Ended June 30, 2004			Year Ended December 31, 2003
	(in thousands)
Eliminate Eastern Texas interest expense	$	925		$	12
Partnership new bank debt ($200.8 million in additional principal) at assumed rates of 3.22% and 4.09%, respectively(1)(2)	(3,198		)	(8,122		)
Amortization of deferred financing costs	(842		)	(6,820		)
Debt refinancing interest expense	—			(143		)
Pro forma increase to interest expense from the acquisition	$	(3,115	)	$	(15,073	)

(1)The Partnership incurred bank debt of $200.8 million in connection with the Eastern Texas acquisition.  The assumed rates of 3.22% and 4.09% for the periods ended June 30, 2004 and December 31, 2003, respectively, reflect the weighted average interest rates for those periods.

(2)The effects of fluctuations of 0.125% and 0.25% in annual interest rates under the Partnership’s credit facility on pro forma interest expense would have been approximately $178,000 and $356,000, respectively, for the six months ended June 30, 2004.  The effects of fluctuations of 0.125% and 0.25% in annual interest rates under the Partnership’s credit facility on pro forma interest expense would have been approximately $406,000 and $812,000, respectively, for the twelve months ended December 31, 2003.

(I)This entry eliminates the operating results of the Hobbs, New Mexico lateral pipeline that was not acquired as part of the Pinnacle acquisition.

(J)MarkWest Energy Partners acquired Pinnacle on March 28, 2003.  This entry eliminates the four days of Pinnacle results (March 28 through March 31, 2003) included in MarkWest Energy Partners’ results for the twelve months ended December 31, 2003.

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(K)Reflects the pro forma adjustment to Western Oklahoma and Michigan Crude Pipeline depreciation expense for the year ended December 31, 2003, as follows:

	Western Oklahoma			Michigan Crude Pipeline			Total
				(in thousands)
Eliminate historical depreciation expense	$	(2,154	)	$	(599	)	$	(2,753	)
Pro forma depreciation expense(1)	1,900			1,074			2,974
Pro forma adjustment to depreciation expense	$	(254	)	$	475		$	221

(1)Pro forma depreciation is based on the lesser of the term of the associated long-term contract or estimated reserves supporting our asset or the asset’s useful life, which is twenty years for property and equipment.

(L)Reflects pro forma adjustment to interest expense for the 2003 acquisitions as calculated below (in thousands):

	Year Ended December 31, 2003
Eliminate Pinnacle interest expense	$	269
Partnership bank debt ($99.2 million in additional principal) at assumed rate of 4.09%(1)	(4,055		)
Pro forma increase to interest expense from the acquisition	$	(3,786	)

(1)The Partnership incurred bank debt of $39.5 million in connection with the Pinnacle acquisition, $37.9 million in connection with the American Central Western Oklahoma acquisition and $21.2 million in connection with the Michigan Crude Pipeline acquisition, plus $0.6 million to pay aggregate transaction costs related to these three acquisitions.  The assumed rate of 4.09% for the period ended December 31, 2003, reflects the weighted average interest rate for that period.

(M)The pro forma adjustment to interest expense from the June 2003 offering to pay off debt issued for the Pinnacle acquisition is calculated as follows (in thousands):

	Year Ended December 31, 2003
Partnership bank debt ($10.0 million in reduced principal) at assumed rate of 4.09%(1)	$	409
Pro forma decrease to interest expense	$	409

(1)The effects of fluctuations of 0.125% and 0.25% in annual interest rates under the Partnership’s credit facility on pro forma interest expense would have been approximately $13,000 and $25,000, respectively, for the twelve months ended December 31, 2003.  The assumed rate of 4.09% for the period ended December 31, 2003, reflects the weighted average interest rate for that period.

27

(N)The pro forma adjustment to interest expense from the January 2004 offering to pay off debt issued for the American Central Western Oklahoma and Michigan Crude Pipeline acquisitions is calculated as follows (in thousands):

	Year Ended December 31, 2003
Partnership bank debt ($41.8 million in reduced principal) at assumed rate of 4.09%(1)	$	1,710
Pro forma decrease to interest expense	$	1,710

(1)The effects of fluctuations of 0.125% and 0.25% in annual interest rates under the Partnership’s credit facility on pro forma interest expense would have been approximately $52,000 and $105,000, respectively, for the twelve months ended December 31, 2003.  The assumed rate of 4.09% for the period ended December 31, 2003, reflects the weighted average interest rate for that period.

Subsequent Event:

In July 2004, the Partnership sold 1,304,438 common units through a private placement, reducing MarkWest Hydrocarbon’s ownership interest in the Partnership from 35% to 29%.  As a result, MarkWest Hydrocarbon has determined that consolidation of the Partnership is no longer appropriate.  However, as the event that triggered the deconsolidation happened in July 2004, the unaudited pro forma financial statements as of June 30, 2004, for the six months ended June 30, 2004 and for the year ended December 31, 2003 reflect the consolidation of the Partnership.  Henceforth, the investment in the Partnership will be accounted for using the equity method.

28

(c)  Exhibits.

Exhibit No.	Description of Exhibit
2.1	Asset Purchase and Sale Agreement and Addendum, thereto, dated as of July 1, 2004 by and between American Central Eastern Texas Gas Company Limited Partnership, ACGC Gathering Company, L.L.C. and MarkWest Energy East Texas Gas Company L.P.
4.1	Unit Purchase Agreement dated as of July 29, 2004 among MarkWest Energy Partners, L.P., and MarkWest Energy GP, L.L.C. and each of Kayne Anderson Energy Fund II, L.P., Kayne Anderson Capital Income Partners, L.P., Kayne Anderson MLP Fund, L.P., Kayne Anderson Capital Income Fund, LTD., Kayne Anderson Income Partners, L.P., HFR RV Performance Master Trust, Tortoise Energy Infrastructure Corporation and Energy Income and Growth Fund, as Purchasers.
4.2	The Registration Rights Agreement dated as of July 29, 2004 among MarkWest Energy Partners, L.P., and MarkWest Energy GP, L.L.C. and each of Kayne Anderson Energy Fund II, L.P., Kayne Anderson Capital Income Partners, L.P., Kayne Anderson MLP Fund, L.P., Kayne Anderson Capital Income Fund, LTD., Kayne Anderson Income Partners, L.P., HFR RV Performance Master Trust, Tortoise Energy Infrastructure Corporation and Energy Income and Growth Fund, as Purchasers.
23.1	Consent of BKD, LLP.
99.1	Second Amended and Restated Credit Agreement dated as of July 30, 2004 among MarkWest Energy Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P., as Guarantor, Royal Bank of Canada, as Administrative Agent, Fortis Capital Corp., as Syndication Agent, Bank One, NA, as Documentation Agent and Societe Generale, as Documentation Agent to the $315,000,000 Senior Credit Facility.
99.2	First Amendment to the Second Amended and Restated Credit Agreement dated as of August 20, 2004, among MarkWest Energy Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P., as Guarantor, Royal Bank of Canada, as Administrative Agent, Fortis Capital Corp., as Syndication Agent, Bank One, NA, as Documentation Agent and Societe Generale, as Documentation Agent.

29

SIGNATURE

Pursuant to the requirements of the Securities and Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.

	MARKWEST HYDROCARBON, INC.
	(Registrant)
Date:  October 12, 2004	By:	/s/ JAMES G. IVEY
		James G. Ivey
		Chief Financial Officer

30

EXHIBIT INDEX

Exhibit No.	Description of Exhibit
2.1	Asset Purchase and Sale Agreement and Addendum, thereto, dated as of July 1, 2004 by and between American Central Eastern Texas Gas Company Limited Partnership, ACGC Gathering Company, L.L.C. and MarkWest Energy East Texas Gas Company L.P.
4.1	Unit Purchase Agreement dated as of July 29, 2004 among MarkWest Energy Partners, L.P., and MarkWest Energy GP, L.L.C. and each of Kayne Anderson Energy Fund II, L.P., Kayne Anderson Capital Income Partners, L.P., Kayne Anderson MLP Fund, L.P., Kayne Anderson Capital Income Fund, LTD., Kayne Anderson Income Partners, L.P., HFR RV Performance Master Trust, Tortoise Energy Infrastructure Corporation and Energy Income and Growth Fund, as Purchasers.
4.2	The Registration Rights Agreement dated as of July 29, 2004 among MarkWest Energy Partners, L.P., and MarkWest Energy GP, L.L.C. and each of Kayne Anderson Energy Fund II, L.P., Kayne Anderson Capital Income Partners, L.P., Kayne Anderson MLP Fund, L.P., Kayne Anderson Capital Income Fund, LTD., Kayne Anderson Income Partners, L.P., HFR RV Performance Master Trust, Tortoise Energy Infrastructure Corporation and Energy Income and Growth Fund, as Purchasers.
23.1	Consent of BKD, LLP.
99.1	Second Amended and Restated Credit Agreement dated as of July 30, 2004 among MarkWest Energy Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P., as Guarantor, Royal Bank of Canada, as Administrative Agent, Fortis Capital Corp., as Syndication Agent, Bank One, NA, as Documentation Agent and Societe Generale, as Documentation Agent to the $315,000,000 Senior Credit Facility.
99.2	First Amendment to the Second Amended and Restated Credit Agreement dated as of August 20, 2004, among MarkWest Energy Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P., as Guarantor, Royal Bank of Canada, as Administrative Agent, Fortis Capital Corp., as Syndication Agent, Bank One, NA, as Documentation Agent and Societe Generale, as Documentation Agent.

31

EX-2.1

Exhibit 2.1

ASSET PURCHASE AND SALE AGREEMENT

THIS ASSET PURCHASE AND SALE AGREEMENT (“Agreement”), dated as of the 1st day of July, 2004, is executed by and entered into by and between AMERICAN CENTRAL EASTERN TEXAS GAS COMPANY LIMITED PARTNERSHIP, an Oklahoma limited partnership and ACGC GATHERING COMPANY, L.L.C., an Oklahoma limited liability company (collectively the “Sellers”), and MARKWEST ENERGY EAST TEXAS GAS COMPANY L.P. a Delaware limited partnership (the “Buyer”).

In consideration of the mutual promises contained herein, the benefits to be derived by each party hereunder and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

1.1Definitions.  As used in this Agreement, the following terms have the indicated meanings:

a.The term “ACGT” shall mean American Central Gas Technologies, Inc., a Delaware corporation.

b.The term “ACGC Gathering” shall mean ACGC Gathering Company, L.L.C., an Oklahoma limited liability company.

c.The term “Agreement” shall mean this Asset Purchase and Sale Agreement together with the exhibits hereto.

d.The term “American Central Eastern Texas” shall mean American Central Eastern Texas Gas Company Limited Partnership, an Oklahoma limited partnership.

e.The term “Assessment Period” as provided by Section 6.1 shall mean a time period, which shall end on July 20, 2004.

f.The term “Buyer” shall mean MarkWest Energy East Texas Gas Company L.P., a Delaware Limited Partnership.

g.The term “Buyer Indemnitor” shall mean Buyer, its successors and assigns for the purposes set forth in Section 6.8.

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h.The term “Capital Expenditure Contracts” means the Chevron Contract, the EPC Contract, the NGPL Contracts and the Total E&P Contract.

i.The term “Chevron Contract” shall mean the Gas Gathering and Processing Agreement dated February 13, 2004, as amended on May 20, 2004, between Chevron Texaco Exploration and Production Company, a division of Chevron USA, Inc. and Sellers referred to in Section 2.6.

j.The term “Closing” is defined in Section 7.4.

k.The term “Closing Amount” is defined in Section 3.3.

l.The term “Closing Date” shall mean on or before August 30, 2004.

m.The term “Compressor Stations” shall mean the compressor stations and related buildings, improvements and facilities described on Exhibit E.

n.The term “Contracts” mean the gas purchase agreements, gas and liquids sales agreements, gathering and processing agreements, and other contracts and agreements relating to the System that are identified on Exhibit I.

o.The term “Crawfish Plant” shall mean the natural gas processing plant referred to in Section 2.5.

p.The term “Devon Gas Imbalances” shall mean any gas purchase and sale imbalances relating to Devon Energy Corp. as defined in Section 3.6.

q.The term “Devon Negative Balance Payment Amount” is defined in Section 3.6.

r.The term “Devon Positive Balance Payment Amount” is defined in Section 3.6.

s.The term “Earnest Money Deposit” is defined in Section 3.1(a).

t.The term “Easements” shall mean all easements, rights-of-way, surface use agreements, servitudes, licenses and other similar rights for the use of the surface or subsurface estate in connection with the System including, without limitation, those described on Exhibit C.

u.The term “Effective Time” means, at 12:01 a.m. Central Standard Time, on the first day of the month in which Closing occurs.

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v.The term “Environmental Assessment” is defined in Section 6.1.

w.The terms “Environmental Claim” and “Claims” shall mean all liability, costs (including without limitation any attorney fees and costs), expenses, claims, demands, fines, penalties, causes of action or other obligations under Environmental Laws.

x.The term “Environmental Defect Notice Date” is defined in Section 6.6(b).

y.The term “Environmental Laws” shall mean any and all laws, statutes, regulations, rules, or orders, of any state or federal governmental agency pertaining to the environment whose purpose is to protect the environment or wildlife and that are in effect in any and all jurisdictions in which the Properties are located, including, without limitation, the Clean Air Act, as amended, the Federal Water Pollution Control Act, as amended, the Rivers and Harbors Act of 1899, as amended, the Safe Drinking Water Act, as amended, the Comprehensive Environmental Response, Compensation and Liability Act, as amended, the Superfund Amendments and Reauthorization Act of 1986, as amended, the Resource Conservation and Recovery Act, as amended, the Hazardous and Solid Waste Amendments Act of 1984, as amended, the Toxic Substances Control Act, as amended, the Hazardous Materials Transportation Act, as amended, and the Oil Pollution Act of 1990, as amended and any analogous state or local laws, regulations, rules, orders or ordinances.

z.The term “Environmental Remediation Costs” is defined in Section 6.7.

aa.The term “EPC Contract” shall mean the Design and Construction Agreement dated March 2, 2004, between Sellers and Engineering, Procurement and Construction, Inc. referred to in Section 2.5.

bb.The term “Equipment Lease” is defined in Section 2.4.

cc.The term “Escrow Agent” shall mean Bank of Oklahoma, N.A.

dd.The term “Escrow Agreement” shall mean the agreement referred to in Section 3.1 in the form attached hereto as Exhibit K.

ee.The term “Gathering Lines” shall mean all natural gas and condensate gathering pipelines, residue gas pipelines and other gas and condensate pipelines, pigging and handling facilities comprising the System, including, without limitation, those described on Exhibit D.

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ff.The term “HSR Act” means the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules and regulations promulgated thereunder.

gg.The term “Liabilities” means all liability, costs (including without limitation any attorney fees and costs), expenses, claims, demands, fines, penalties, causes of action or other obligations other than those arising under Environmental Laws.

hh.“Material Adverse Environmental Conditions” for the purposes provided under Section 6.6(a) shall mean conditions which are required to be remediated under current applicable Environmental Laws and which, in the aggregate, would cost in excess of Five Million Dollars ($5,000,000.00) to remedy.

ii.The term “NGPL Contracts” shall mean the Agreement Regarding Facilities Necessary for Natural Gas Pipeline Company of America to Receive Gas from American Central Gas Technologies, Inc. in Panola County, Texas, and an Operational Gas Balancing Agreement with Natural Gas Pipeline Company of America referred to Section 2.7.

jj.The term “Owned Real Estate” shall mean the lands and surface estates described on Exhibit A.

kk.The term “Parts Inventory” shall mean all spare parts, pipe, valves and other similar items of inventory located on or about the Gathering Lines, the Compressor Stations and the Processing Facilities and intended for use in connection with the System.

ll.The term “Permits” shall mean all permits, franchises, licenses, concessions and other rights granted by any governmental authorities for the ownership, use or operation of the System, including, without limitation, those identified on Exhibit H.

mm.The term “Preliminary Settlement Statement” shall mean a statement prepared by Sellers which shall set forth the Closing Amount showing each adjustment and the calculation of such adjustments used to determine the Closing Amount.

nn.The term “Processing Facilities” shall mean the processing facilities described on Exhibit F.

oo.The term “Properties” shall mean all of the Sellers’ rights, titles, interests and benefits in and to the assets described in Section 2.1 (“Panola Gas System”) located in the County of Panola in the State of Texas.

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pp.The term “Purchase Price” as used in this Agreement is defined in Section 3.1.

qq.The term “Real Property Leases” shall mean the real property leases and leasehold interests described on Exhibit B.

rr.The term “Records” is defined in Section 2.1(m).

ss.The term “Seller Indemnitee” shall mean Sellers, their officers, directors, employees, contractors, representatives, and successors for the purposes set forth in Section 6.9.

tt.The term “Sellers” shall mean American Central Eastern Texas Gas Company Limited Partnership, an Oklahoma limited partnership and ACGC Gathering Company, L.L.C., an Oklahoma limited liability company.

uu.The term “Sellers’ Balancing Settlement Statement” is defined in Section 3.6.

vv.The term “System” shall mean the Panola Gas System located in Panola County, Texas, consisting of the Properties.

ww.The term “Total E&P Contract” is defined in Section 2.8.

ARTICLE II

PURCHASE AND SALE OF THE PROPERTIES

2.1Purchase and Sale of the Properties.  Subject to the terms and conditions of this Agreement, the Sellers shall sell, assign, transfer and convey to Buyer, and Buyer shall purchase and pay for, all of the Sellers’ rights, titles, interests and benefits in and to the following described assets (hereinafter collectively referred to as the “Properties”) including Sellers’ natural gas and condensate gathering and processing facilities located in the County of Panola in the State of Texas as hereinafter described (the “System”):

a.Lands.  The lands and other surface estates described on Exhibit A hereto together with all other surface estates owned by Sellers that are used in the operation of the System (the “Owned Real Estate”);

b.Real Property Leases.  The real property leases and leasehold interests described on Exhibit B hereto together with all other of Sellers’ leasehold interests used in the operation of the System (the “Real Property Leases”);

c.Easements.  All easements, rights-of-way, surface use agreements, servitudes, licenses and other similar rights for the use of the surface or

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subsurface estate in connection with the System including, without limitation, those described on Exhibit C hereto (the “Easements”);

d.Gathering Lines.  All natural gas and condensate gathering pipelines, residue gas pipelines and other gas pipelines, pigging and handling facilities, comprising the System, including, without limitation the equipment that is part of the gathering lines all as described on Exhibit D hereto and as shown on Exhibit DD (the “Gathering Lines”);

e.Compressor Stations.  The compressor stations and related buildings, improvements, facilities and equipment described on Exhibit E hereto and as shown on Exhibit DD (the “Compressor Stations”);

f.Processing Facilities.  The processing facilities described on Exhibit F hereto, including all components of the Crawfish Plant, with all improvements, additions, equipment and ancillary parts thereof as of the Closing Date, whether described on Exhibit F or not (the “Processing Facilities”):

g.Personal Property.  All personal property as described on Exhibit G hereto.

h.Parts Inventory.  All spare parts, pipe, valves and other similar items of inventory located on or about the Gathering Lines, the Compressor Stations and the Processing Facilities and intended for use in connection with the System (the “Parts Inventory”);

i.Permits.  To the extent assignable, all permits, franchises, licenses, concessions and other rights granted by any governmental authorities for the ownership, use or operation of the System, including, without limitation, those identified on Exhibit H hereto (the “Permits”);

j.Contracts.  The gas purchase agreements, gas and liquids sales agreements, gathering and processing agreements, and other contracts and agreements relating to the System including without limitation those identified on Exhibit I hereto (the “Contracts”);

k.Hydrocarbons.  All natural gas, condensate and other hydrocarbons owned by the Sellers and located in the Gathering Lines, the Processing Facilities, the Equipment or elsewhere in the System as of the Closing Date;

l.Warranties.  To the extent assignable, all warranties, representations and guarantees made by suppliers, manufacturers, and contractors held by the Sellers and relating to the Gathering Lines, the Equipment or the Processing Facilities; and

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m.Books and Records.  All books, files, records, correspondence, studies, surveys, reports and other data in the actual possession or control of Sellers relating to the operation of the System, including, without limitation, all title records, customer lists, supplier lists, sales materials, promotional materials, operational records, technical records, production and processing records, division order and lease right-of-way files, accounting files and contract files (the “Records”) with Sellers retaining the right to maintain or obtain from Buyer copies of the Records for a period of seven (7) years.

2.2Excluded Assets.

a.The Properties shall not include, and the Sellers specifically retain unto themselves, all refunds, insurance, bonds, cash and deposits of Sellers maintained in connection with the System and the other assets and properties of the Sellers not associated with the System as specifically set forth on Exhibit AA.

b.Additionally, Sellers shall retain all accounts receivable attributable to the sale, transportation and processing of natural gas and natural gas condensate and shall be responsible for paying accounts payable with respect to the System during periods prior to the Effective Time.  In the event Buyer is paid for such amounts as are properly due Sellers, Buyer shall immediately remit such payments to Sellers.  If Buyer pays any accounts payable with respect to the System for periods prior to the Effective Time, Sellers shall immediately reimburse Buyer for such amounts.  Buyer shall be entitled to all proceeds from the sale, transportation and processing of natural gas and natural gas condensate for periods following the Effective Time.  In the event Sellers are paid for such amounts as are properly due Buyer, Sellers shall immediately remit such payment to Buyer.

2.3Assumption of Liabilities and Obligations in Connection with Real Property Leases, Easements, Permits and Contracts.   Subject to the terms and conditions of this Agreement, upon Closing, Buyer shall assume, perform, observe and fulfill the duties, liabilities and obligations of Sellers under the Real Property Leases, Easements, Permits and Contracts to the extent arising after the Effective Time, and excluding in each case to the extent that such terms, provisions, conditions, liabilities or obligations (i) were required to have been performed under the terms of such Real Property Leases, Easements, Permits and Contracts prior to the Closing Date, (ii) arise out of breaches or violations of or other delinquencies under such Real Property Leases, Easements, Permits and Contracts prior to the Closing Date, or (iii) relate to obligations incurred under the terms of such Real Property Leases, Easements, Permits and Contracts prior to the Closing Date.

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2.4Assumption of Equipment Leases.  Upon Closing, Buyer shall assume, perform, observe and fulfill the duties, liabilities and obligations of Sellers under the Equipment Leases described on Exhibit J, including the payment obligations incurred from and after the Effective Time thereunder but excluding any payment or other obligations due under or related to the Equipment Leases prior to the Effective Time.

2.5Assignment and Assumption of EPC Contract.  American Central Eastern Texas has contracted with Engineering, Procurement and Construction, Inc., pursuant to a Design and Construction Agreement dated March 2, 2004 (the “EPC Contract”) to redesign, refurbish and skid mount a natural gas processing plant previously known as the Shell Oil Company Crawfish Plant (the “Crawfish Plant”).  The Crawfish Plant is intended to be utilized as part of the System and is described on Exhibit F as part of the Processing Facilities.  At Closing, Buyer shall assume all of American Central Eastern Texas’ rights, responsibilities, liabilities and obligations under the EPC Contract all to the extent arising on or after the Effective Time, and American Central Eastern Texas shall assign to Buyer all its rights under the EPC Contract and the Crawfish Plant as part of the Processing Facilities.

2.6Assignment and Assumption of ChevronTexaco Contract.  American Central Eastern Texas has entered into a Gas Gathering and Processing Agreement dated February 13, 2004, as amended on May 20, 2004, (the “Chevron Contract”) with ChevronTexaco Exploration & Production Company, a division of Chevron U.S.A., Inc., for the construction of gathering and processing facilities and the gathering and processing of natural gas.  Such facilities are intended to be utilized as part of the System and are described, in part, on Exhibits D, E, F, H and I.  At Closing, Buyer shall assume the rights, responsibilities, liabilities and obligations under the Chevron Contract to the extent arising on or after the Effective Time, and American Central Eastern Texas shall assign to Buyer all its rights under the Chevron Contract.ACGT is owner of all of the partnership and Member interests of Sellers and has guaranteed the performance of American Central Eastern Texas under the Chevron Contract under Guaranty Agreement dated May 20, 2004.  MarkWest Energy Partners, L.P., of which Buyer is a wholly owned subsidiary, shall assume the obligations of ACGT under such Guaranty Agreement and, to evidence the same, Buyer shall deliver to Seller at Closing the Guaranty Assumption Agreement in the form of Exhibit CC hereto executed by MarkWest Energy Partners, L.P.  From and after Closing, Buyer shall indemnify ACGT from and against any claim, demand, expense, liability or damages, including attorneys’ fees and costs of defense, made or arising under such Guaranty to the extent relating to any obligation arising on or after the Effective Time.

2.7Assignment and Assumption of NGPL Contracts.  American Central Eastern Texas has entered into an Agreement Regarding Facilities Necessary for Natural Gas Pipeline Company of America to Receive Gas from American Central Gas Technologies, Inc. in Panola County, Texas and an Operational Gas Balancing Agreement with Natural Gas Pipeline Company of America (the “NGPL

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Contracts”).  At Closing, Buyer shall assume the rights, responsibilities, liabilities and obligations of American Central Eastern Texas under such contracts to the extent arising on or after the Effective Time, and Sellers shall assign to Buyer all its rights thereunder.

2.8Assignment and Assumption of Total E&P Contract.  American Central Eastern Texas has entered into a Gas Gathering and Processing Agreement dated June 4, 2004, with Total E&P USA, Inc. (the “Total E&P Contract”) for the construction of gathering and processing facilities and the gathering and processing of natural gas.  At Closing, Buyer shall assume the rights, responsibilities, liabilities and obligations under the Total E&P Contract to the extent arising on or after the Effective Time, and American Central Eastern Texas shall assign all its rights under the Total E&P Contract.

ARTICLE III

PURCHASE PRICE

3.1Purchase Price.  The purchase price payable by Buyer for the Properties shall be Two Hundred Forty Million Four Hundred Thousand Dollars ($240,400,000.00) (the “Purchase Price”) in immediately available funds, subject to adjustment as provided in this Article III, to be paid as follows:

a.Earnest Money Deposit.  At the time of the execution and delivery of this Agreement by the parties, Buyer shall deposit the sum of Ten Million Dollars ($10,000,000) in immediately available funds (the “Earnest Money Deposit”) with Bank of Oklahoma, N.A. as Escrow Agent to be held by Escrow Agent pursuant to the terms of the Escrow Agreement attached hereto as Exhibit K which the parties shall execute at the time of the execution of this Agreement to be held and applied against the Purchase Price at Closing (as hereinafter defined) or otherwise disposed of pursuant to the terms of this Agreement.

b.Payment of Remaining Balance of Purchase Price.  At Closing, which will occur no later than August 30, 2004, Buyer shall pay to Sellers the balance of the Purchase Price as provided in Section 3.3.

3.2Adjustments to Purchase Price.  The Purchase Price shall be subject to adjustment as follows:

a.Operating Revenues and Expenses.  Sellers shall be entitled to all operating revenues attributable to the operation of the Property and shall be responsible for all operating expenses and related accounts payable arising in the ordinary course of business attributable to the Properties, in each case to the extent they relate to the time prior to the Effective Time.  Buyer shall be entitled to all operating revenues and shall be responsible for the payment of all operating expenses and related accounts payable

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arising in the ordinary course of business attributable to the Properties, in each case to the extent they relate to time after the Effective Time.  The actual amounts or values associated with the above shall be accounted for to the extent known in the Preliminary Settlement Statement with the final reconciliation contained in the Final Accounting Settlement.

b.Taxes.  All taxes and assessments, including without limitation, excise taxes, ad valorem taxes and any other federal, state or local taxes or assessments attributable to the ownership or operation of the Properties prior to the Effective Time shall remain Seller’s responsibility, and all deductions, credits and refunds pertaining to the aforementioned taxes and assessments, no matter when received, shall belong to Seller.  All taxes and assessments, including without limitation, excise taxes, ad valorem taxes and any other federal, state, local or tribal taxes and assessments attributable to the ownership or operation of the Properties after the Effective Time (excluding franchise and income taxes of the Seller from the Effective Time through the Closing) shall be Buyer’s responsibility, and all deductions, credits and refunds pertaining to the aforementioned taxes and assessments, no matter when received, shall belong to Buyer.  The actual amounts or values associated with the above, if any, shall be accounted for to the extent known in the Preliminary Settlement Statement and finally reconciled in the Final Accounting Settlement.  Ad valorem taxes, real property and personal property taxes which have not been assessed and paid for calendar year 2004 shall be estimated based on the prior year assessment, prorated through the Effective Time and reflected in Preliminary Settlement Statement as a reduction in the Purchase Price.

c.Capital Expenditure Contracts.   At Closing, there shall be an adjustment to the Purchase Price based on all amounts actually paid by Sellers under the Capital Expenditure Contracts (as defined in Section 4.1(j) as of Closing (“Actual Amounts Paid”).  If the Actual Amounts Paid are less than $11,000,000, then the Purchase Price shall be reduced by an amount equal to the difference between $11,000,000 and the Actual Amounts Paid.  If the Actual Amounts Paid are more than $11,000,000, then the Purchase Price shall be increased by the difference between the Actual Amounts Paid and $11,000,000.

d.Obligations and Credits.  All prepaid utility charges, taxes, rentals and any other prepaids applicable to periods of time after the Effective Time, if any, and attributable to the Properties shall be reimbursed to Seller by Buyer; and accrued payables applicable to periods of time prior to the Effective Time, if any, and attributable to the Properties shall be the responsibility of Seller.  The actual amounts or values associated with the above shall be accounted for in the Preliminary Settlement Statement or Final Accounting Settlement.

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e.Final Accounting Settlement.  As soon as reasonably practicable, but in no event later than ninety (90) Days after Closing, Seller shall deliver to Buyer a post-closing statement setting forth a detailed final calculation of all post-closing adjustments applicable to the periods before and after the Effective Time (“Final Accounting Settlement”).  As soon as reasonably practicable, but in no event later than thirty (30) Days after Buyer receives the post-closing statement, Buyer shall deliver to Seller a written report containing any changes Buyer proposes to be made to such statement.  If Buyer fails to deliver a report to Seller containing changes Buyer proposes to be made to the post-closing statement, the post-closing statement delivered by Seller shall be deemed to be true and correct and binding on and non-appealable by the parties.  As soon as reasonably practicable, but in no event later than fifteen (15) Days after Seller receives Buyer’s proposed changes to the post-closing statement, the parties shall meet and undertake to agree on the final post-closing adjustments.  If the parties fail to agree on the final post-closing adjustments within such fifteen (15) Day period, the disputed items shall be resolved by submitting the same to a firm of independent nationally recognized accountants mutually acceptable to the parties (the “Accounting Referee”).  The Accounting Referee shall resolve the dispute(s) regarding the Final Accounting Settlement within thirty (30) Days after having the relevant materials submitted for review.  The decision of the Accounting Referee shall be binding and non-appealable by the parties.  The fees and expenses associated with the Accounting Referee shall be borne equally by Buyer and Seller.  The date upon which all amounts associated with the Final Accounting Settlement are agreed to by the parties, whether by decision of the Accounting Referee or otherwise, shall be herein called the “Final Settlement Date.”  Any amounts owed by either party to the other as a result of such final post-closing adjustments shall be paid within five (5) Business Days after the Final Settlement Date.

e.Post-Final Accounting Settlement.  Any revenues received or costs and expenses paid by Buyer after the Final Accounting Settlement which are attributable to the ownership or operation of the Properties prior to the Effective Time shall be billed or reimbursed to Seller, as appropriate.  Any revenues received or costs and expenses paid by Seller after the Final Accounting Settlement which are attributable to the ownership or operation of the Properties after the Effective Time shall be reimbursed or billed to Buyer, as appropriate.

3.3Determination and Payment of Closing Amount.  Not less than five (5) business days prior to Closing, Sellers shall prepare and deliver to Buyer a closing statement reflecting the “Closing Amount” which shall be the Purchase Price (less the Earnest Money Deposit) adjusted as provided in Section 3.2, using for such adjustments the best information (including estimated data) available (“Preliminary Settlement Statement”).  At the Closing, Buyer shall pay to Sellers the Closing Amount in immediately available funds by wire transfer to an account or accounts designated in writing by Sellers and Buyer shall provide

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such instructions to the Escrow Agent to cause the Earnest Money Deposit to be paid to Sellers.

3.4Sellers’ Liability for Taxes and Entitlement to Pre-Effective Date Gas.

a.Sellers shall be responsible for and pay all unpaid ad valorem, property, production, severance and similar taxes and assessments based upon or measured by the ownership of property or the production of hydrocarbons or the receipt of proceeds therefrom accruing to the Properties prior to the Effective Time.

b.Sellers shall be entitled to payment for all natural gas, natural gas condensate and other hydrocarbons transported by and produced by the System prior to the Effective Time.

3.5Allocation to Equipment and Parts Inventory.  The portion of the Purchase Price which the parties agree should reasonably be allocable to the Equipment and Parts Inventory not a part of the real estate interests sold hereunder is Sixty Six Thousand Three Hundred Twenty Eight Dollars ($66,328.00).

3.6Pre-Closing Determination and Payment for Gas Imbalances.

a.The parties acknowledge that as of the Effective Time, the System may be subject to gas imbalances relating to (i) producers/shippers on the System; and (ii) deliveries of gas to the Duke Energy Field Services East Texas Gas System.  Seller shall be required to settle all such imbalances as of the Effective Time.

b.The System may also be subject to gas imbalances with Devon Energy Corp. under a contract dated January 9, 1998 (the “Devon Gas Imbalances”).  In the event the Devon Gas Imbalances are positive as of the Effective Time (meaning the System is owed Deliveries of gas from Devon Energy Corp. without having to make payment for such deliveries), Buyer shall pay Sellers for such positive balance based upon a valuation using the NGPL Texok Index for the month immediately preceding the Effective Time (the “Devon Positive Balance Payment Amount”).  Buyer shall be entitled to sellers’ positive balance with Devon Energy Corp. upon payment therefore as provided in this Section 3.6.  In the event the Devon Gas Imbalances with respect to the System are negative as of the Effective Time (meaning the System owes deliveries of gas to Devon Energy Corp.), Sellers shall pay Buyer for such negative balances based upon a valuation using the NGPL Texok Index for the month immediately preceding the Effective Time (the “Devon Negative Balance Payment Amount”).  Upon such payment by Sellers, Buyer shall satisfy any obligation to Devon Energy Corp. for such negative balances.  Sellers will endeavor to eliminate or minimize all Devon Gas Imbalances by the Effective Time; provided, in any event the amount of the Devon Gas Imbalances as of the Effective Time will not exceed 100,000 MMBtu.

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c.As soon as practicable after the Closing, but not later than 60 days after the Closing, Sellers shall prepare and deliver to Buyer, in accordance with this Agreement and generally accepted accounting principles, a statement (“Sellers’ Balancing Settlement Statement”) setting forth its calculation of the Devon Positive Balance Payment Amount or Devon Negative Balance Payment Amount.  As soon as practicable after receipt of Sellers’ Balancing Settlement Statement, and no later than 90 days after the Closing, Buyer shall deliver to Sellers a written report containing any changes that Buyer proposes to be made to Sellers’ Balancing Settlement Statement.  Sellers and Buyer shall undertake to agree with respect to the proper amounts due for the Devon Gas Imbalances not later than 15 days after the receipt by Sellers of Buyer’s proposed changes referred to in the preceding sentence.

d.If Buyer and Sellers are unable to agree upon the proper amount due for the Devon Gas Imbalances within the time periods set forth above, the matter shall be resolved in accordance with the procedures for resolving the Final Accounting Settlement in Section 3.2(d).

ARTICLE IV

REPRESENTATIONS AND WARRANTIES OF SELLERS

Sellers represent and warrant to Buyer as follows:

4.1Sellers’ Representations and Warranties.

a.Seller, American Central Eastern Texas Gas Company Limited Partnership is a limited partnership duly organized, validly existing and in good standing under the laws of the State of Oklahoma and is duly qualified to carry on its business in Texas.  Seller, ACGC Gathering Company, L.L.C. is a limited liability company duly organized, validly existing and in good standing under the laws of the State of Oklahoma and is duly qualified to carry on its business in Texas.

b.Sellers have the power and authority to execute and deliver this Agreement and each agreement and instrument to be delivered by Sellers pursuant hereto, and to carry out its obligations hereunder.  The execution, delivery and performance of this Agreement and each agreement and instrument to be delivered pursuant hereto by Sellers, and the consummation of the transactions provided for hereby have been duly authorized and approved by all requisite action of Sellers and no other act or proceeding on the part of Sellers or its General Partner or other partners is necessary to authorize the execution, delivery or performance of this Agreement and this Agreement is a legal, valid, binding and enforceable obligation of Sellers, except as may be limited by bankruptcy or other laws of such general application affecting creditors’ rights generally.

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c.No consent, approval, or notices of or to any other person is required with respect to Sellers in connection with the execution, delivery or enforceability of this Agreement or the consummation of the transactions provided for hereby other than (i) those for which any adverse consequences arising out of the failure to obtain such consent or to make such filing are immaterial, individually and in the aggregate, to the Properties, (ii) consents already obtained by Sellers; and (iii) consents not yet obtained by Sellers which are set forth on Exhibit L.

d.Sellers have not incurred any obligation or liability, contingent or otherwise, for brokers’ or finders’ fees in connection with the transactions contemplated by this Agreement for which Buyer shall have any responsibility or liability.  Sellers agree to pay and to indemnify fully, hold harmless and defend Buyer from and against, and pay, any claims by any person alleging a right to a broker’s or finder’s fee based upon any actions of Sellers in connection with these transactions.

e.This Agreement and the execution and delivery hereof by Sellers do not, and the fulfillment and compliance with the terms and conditions hereof and the consummation of the transactions contemplated hereby will not:

i.Conflict with any of the terms, conditions or provisions of (i) the Limited Partnership Agreement of American Central Eastern Texas; or (ii) the Articles of Organization or Operating Agreement of ACGC Gathering;

ii.Violate any provisions of or, except with respect to the HSR Act and any consents, authorizations or approvals of governmental authorities as are customarily generated and received in the ordinary course of business at post-closing dates, require any consent, authorization or approval of any governmental authority under, any statute, law, rule, regulation, ordinance, court order or judgment applicable to or binding upon Sellers;

iii.Conflict with, result in a breach of, constitute a default under, accelerate or permit the acceleration of the performance required by, or require any consent, authorization or approval under any mortgage, indenture, loan, credit agreement or other agreement or instrument evidencing indebtedness for borrowed money to which Sellers are a party or by which Sellers are bound or to which any of the Properties owned by them are subject, except any such consent as has been obtained prior to the date hereof; or

iv.Result in the creation or imposition of any lien, charge or other encumbrance upon the Properties.

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f.Sellers are not in default under any of the Contracts or any other agreement, contract, lease, license or other instrument to which Sellers are a party or by which Sellers are bound or to which any of the Properties are subject.

g.The Properties have been and are being operated through the Closing Date in compliance with all statutes, laws, rules, regulations or orders of any governmental authorities applicable to or binding upon Sellers or the Properties, including, without limitation, all Environmental Laws.  In the event of a breach of this warranty with respect to claims under Environmental Laws, the provisions of Sections 6.6 and 6.7 hereof shall be applicable.

h.The Permits described on Exhibit H constitute all of the material Permits required or necessary for the Sellers to own and operate the Properties and to operate the System, in the places and in the manner currently owned or operated and each such Permit is in full force and effect, (ii) Sellers have not received written notification concerning, and there are no material violations that are in existence with respect to such Permits and (iii) no proceeding is pending, or to Sellers’ Knowledge, threatened with respect to the revocation, limitation or otherwise relating to any of such Permits.  The System, as currently operated by Sellers, does not require certificate authority from the Federal Energy Regulatory Commission.  All necessary reports required by any governmental authority with respect to the Properties have been, and through the Closing Date will be, timely, properly and accurately made in all material respects.  In the event of a breach of this warranty the provisions of Section 6.5(b) hereof shall be applicable.

i.At the Closing, Sellers will convey title to the Properties free and clear of any and all liens, claims or encumbrances of persons claiming by, through or under Sellers, but not otherwise and will warrant and defend title to the Properties against all persons claiming by, through or under Sellers, but not otherwise. All or a portion of the Properties are subject to the mortgages described below:

Deed of Trust, Fixture Filing, Assignment, Security Agreement and Financing Statement from American Central Eastern Texas Gas Company, Limited Partnership, to Robert R. Wetteroff, as Trustee For The Benefit of Wachovia Bank, National Association as Administrative Agent and others dated January 13, 2004, recorded on January 20, 2004 in Vol. 1208, Page 658, Panola County Texas; and

Deed of Trust Fixture Filing, Assignment, Security Agreement and Financing Statement From ACGC Gathering Company, L.L.C. dated January 13, 2004, recorded on

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January 20, 2004, in Vol. 1209, Page 1, Panola County, Texas.

Sellers shall obtain a full release of such mortgages, together with all other mortgages and liens affecting any portions of the System and the Properties and deliver the same to Buyer at or prior to Closing.

j.With respect to the Real Property Leases, Easements and Contracts, in all material respects: (i) to the knowledge of Sellers all of such Real Property Leases, Easements and Contracts are in full force and effect and are the valid and legally binding obligations of the parties thereto; (ii) Sellers are not in breach or default with respect to any material obligations pursuant to any of the Real Property Leases, Easements or Contracts; (iii) all material payments required to be made by Sellers thereunder prior to Closing Date have been made by Sellers or will be made by Sellers prior to the Closing Date; (iv) to the knowledge of Sellers, no other party to any of the Real Property Leases, Easements or Contracts (or any successor in interest thereto) is in breach or default with respect to any of its material obligations thereunder; and (v) neither Sellers nor, to the knowledge of Sellers, any other party to any of the Real Property Leases, Easements or Contracts has given or threatened to give notice of any action to terminate, cancel, rescind or procure a judicial reformation of any of the Contracts or any provision thereof.  Without limiting the foregoing, with respect to the EPC Contract, the ChevronTexaco Contract, the NGPL Contracts and the Total E&P Contract (“Capital Expenditure Contracts”), (x) to the knowledge of Sellers the counterparties to each of the foregoing have fully complied with the terms and conditions thereof, (y) no persons are claiming, or have the right to claim, any materialmen’s, supplier’s or laborer’s liens in connection therewith. Exhibit Z, attached hereto is a comprehensive description of all amounts expended to date under the Capital Expenditure Contracts, including specification as to whom amounts were paid, under which contract, for what the amounts were paid and whether the work, facilities or services for which payment was made was completed as required under the applicable Capital Expenditure Contract; and, a specification of amounts left to be paid, and for what such amounts will be paid through completion of any required construction under the Capital Expenditure Contracts.

k.No person, firm or entity holds any preferential or pre-emptive purchase right to purchase all or any portion of the Properties.

l.All costs incurred by Sellers in the ownership and operation of the Properties have been timely and properly paid.

m.Except for consents already obtained and those not yet obtained as set forth on Exhibit L (herein, the “Required Consents”), Sellers do not require the consent or approval of any third party or governmental body to transfer, sell or assign the Properties to Buyer.

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n.No action, suit, proceeding or claim is pending or to Sellers’ knowledge threatened against Sellers relating to the Properties or to Sellers’ ownership or operation of the Properties or seeking to restrain or prohibit this Agreement or the transactions contemplated hereby, or to obtain damages, a discovery order or other relief in connection with this Agreement or the transactions contemplated hereby.

o.Sellers have not received any written notice of infringement, misappropriation or conflict with respect to any intellectual property included within the Properties.  The operation of the Properties has not infringed, misappropriated or otherwise conflicted with any patents, patent applications, patent rights, trademarks, trademark applications, service marks, service mark applications, copyrights, trade names, unregistered copyrights, or trade secrets of any other person, firm or entity Environmental Matters.

p.Neither Sellers nor any other person under the direction of Sellers has caused or allowed the accumulation, generation, use, treatment, storage, or disposal of hazardous substances in connection with or on the Properties, including offsite disposals, except in accordance with applicable Environmental Laws.  In the event of a breach of this warranty the provisions of Sections 6.6 and 6.7 hereof shall be applicable.

q.There are no, and there has been no release of any, hazardous substances at, on, or underlying any of the Properties and all such releases that are required to be reported (i) under Environmental Law have been reported to the appropriate governmental authority or otherwise are in compliance with applicable Environmental Laws.  In the event of a breach of this warranty the provisions of Sections 6.6 and 6.7 hereof shall be applicable.

r.Since January 1, 1999, Sellers have not received written inquiry or notice of any actual or threatened Claim or of any civil, criminal or administrative proceeding related to or arising under any Environmental Law relating to the Properties;

s.Sellers are not required to operate of the System and/or Properties under any compliance order, a decree or agreement, any consent decree or order, or corrective action decree or order issued by or entered into with any governmental authority under any Environmental Law or any Law regarding health or safety in the work place.

t.To Seller’s Knowledge, each Seller is operating and has operated the Systems and Assets in compliance with all applicable Environmental Laws.  In the event of a breach of this warranty the provisions of Sections 6.6 and 6.7 hereof shall be applicable.

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u.Sellers have all real property rights necessary to operate the System and to own and use the Properties in their present locations, and all portions of the System are located upon lands on which Sellers have valid and subsisting Owned Real Estate, Real Property Leases or Easements.  No event has occurred that with notice or lapse of time would constitute a breach or default that would permit termination, modification, or acceleration, under any Real Property Lease or Easement.  In the event of a breach of this warranty as it pertains to Easements and Permits the provisions of Section 6.5(b) hereof shall be applicable.

v.In the data, records and materials delivered to Buyer in connection with this Agreement and the transactions contemplated herein, there is no untrue statement of a material fact or omission to state a material fact necessary to make the information contained in the data, records and materials delivered to Buyer hereunder not misleading.

w.Except as otherwise specifically provided herein, Sellers make no representations, express or implied, with respect to the condition of the Properties.  No implied warranties of merchantability or fitness for purpose are made by Sellers and Buyer specifically disclaims the same.

x.The foregoing representations and warranties of Sellers shall expressly survive Closing and not be deemed to have merged into any of the assignments or other conveyances at Closing.

ARTICLE V

REPRESENTATIONS AND WARRANTIES OF BUYER

Buyer represents and warrants to Sellers as follows:

5.1Buyer’s Representations and Warranties.

a.Buyer represents and warrants to Sellers that Buyer is acquiring the properties for its own benefit and account and not with the intent of distributing fractional undivided interests thereof such as would be subject to regulation by federal or state securities laws.

b.Buyer represents that by reason of Buyer’s knowledge and experience in the evaluation, acquisition, and operation of similar properties, Buyer has evaluated the merits and risks of purchasing the Properties and has formed an opinion based solely upon Buyer’s knowledge and experience and upon the express representations and warranties of Sellers contained in this Agreement and not upon any other representations or warranties by Sellers with respect to the Properties or as to the accuracy or completeness of any data, information, or materials heretofore or hereafter furnished to Buyer in connection with the Properties, and any reliance on or use of the same has been and will be at Buyer’s sole risk.

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c.Buyer represents that Buyer has made or will make during the “Assessment Period” all investigation necessary to determine the environmental condition of the Properties.

d.Buyer is a limited partnership duly organized, validly existing and in good standing under the laws of the State of Delaware, and is duly qualified to conduct business in Texas.

e.Buyer has the power and authority to execute and deliver this Agreement and each agreement and instrument to be delivered by Buyer pursuant hereto, and to carry out its obligations hereunder.  The execution, delivery and performance of this Agreement and each agreement and instrument to be delivered pursuant hereto by Buyer and the consummation of the transactions provided for hereby have been duly authorized and approved by all requisite action of Buyer and no other act or proceeding on the part of Buyer or its affiliates or partners is necessary to authorize the execution, delivery or performance of this Agreement, and this Agreement is a legal, valid, binding and enforceable obligation of Buyer, except as may be limited by bankruptcy or other laws of such general application affecting creditor’s rights generally.

f.Except for filings required under the HSR Act, no consent or filing is required with respect to Buyer in connection with the execution, delivery or enforceability of this Agreement or the consummation of the transactions provided for hereby, other than those for which any adverse consequences arising out of the failure to obtain such consent are immaterial, individually and in the aggregate, to the purchase and sale of the Properties.

g.The execution and delivery of this Agreement and the consummation of the transactions provided for hereby does not violate any other agreement, contract, or instrument to which Buyer is subject or is a party.

h.No action, suit, proceeding or claim is pending or to Buyer’s knowledge threatened against Buyer seeking to restrain or prohibit this Agreement or the transactions contemplated hereby, or to obtain damages, a discovery order or other relief in connection with this Agreement or the transactions contemplated hereby.

i.Buyer has not incurred any obligation or liability, contingent or otherwise, for brokers’ or finders’ fees in connection with the transactions contemplated by this Agreement for which Sellers shall have any responsibility or liability.  Buyer agrees to pay and to indemnify fully, hold harmless and defend Sellers from and against, and pay, any claims by any person alleging a right to a broker’s or finder’s fee based upon any actions of Buyer in connection with these transactions.

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ARTICLE VI

BUYER’S ASSESSMENT OF PROPERTIES

6.1Assessment.  Buyer shall have a time period (“Assessment Period”) which shall end on July 20, 2004, to conduct or have conducted, at its own risk and expense, an environmental assessment of the real property on which the Properties are located consisting of (i) a surface inspection of the Properties, (ii) an inspection of Sellers’ historical files for information, if any, to the best of Sellers’ knowledge, covering any spills or disposal of crude oil, petroleum, petroleum products and condensate or hazardous substances that would be a violation of Environmental Laws relating to the Properties (herein collectively called the “Environmental Assessment”).

6.2Right of Entry.  Buyer agrees that the provisions of this Section shall apply to any and all access to the Properties or other property of Sellers in connection with this Agreement, whether such access occurred before or will occur after the execution of this Agreement.  Sellers will, to the extent they have the legal right to do so, provide Buyer (or its contractor) with reasonable access to the Properties to conduct the Environmental Assessment.  Buyer and/or its contractor shall comply with prudent safety and industrial hygiene procedures and shall review such procedures with Sellers prior to commencement of the Environmental Assessment.  Buyer shall comply with Sellers’ established safety related rules and regulations including those provided by Sellers’ safety manuals which will be provided to Buyer upon request.  Buyer shall submit schedules to Seller which show when Buyer plans to enter the Properties or other Seller property. Said schedules shall be in sufficient detail to allow Sellers to determine in advance the approximate number of employees, contractors, subcontractors and equipment that Buyer will have on the sites where the Properties are located at any time, and shall be provided to Sellers sufficiently in advance of the date or dates of entry to enable Sellers to arrange to have an inspector(s) present at the site(s).  Buyer shall not enter the real property on which the Properties are located without the presence of an employee or contractor of Sellers.  It is understood that there are risks associated with entry onto the Properties, and Buyer assumes responsibility for the safety of personnel and property of both Buyer and Buyer’s contractors.  Buyer agrees to inspect the Properties for safety purposes prior to such entry and to exercise precautions and conduct all actions in a way that will, in so far as reasonably possible, assure the safety of persons and property.

6.3Confidentiality.  Prior to Closing, Buyer shall maintain in confidence and not disclose to third parties or its employees, who are not involved in evaluating this asset acquisition, any Seller information obtained in the review of title or any other information obtained from Sellers, and shall not use such Seller information in any manner that is adverse or detrimental to the interests of Sellers.

6.4Records.  Buyer shall not destroy or otherwise dispose of any records, files and other data acquired hereunder until a date no earlier than December 31, 2010.  Until such date, Buyer shall make such records, files and other data available to

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Sellers or their authorized representatives for any business, legal or technical need in a manner, which does not unreasonably interfere with Buyer’s business operations.  Additionally, Sellers shall have the right to retain copies of any records, files or other data transferred to Buyer hereunder.

6.5Review of Title.

a.Buyer has conducted a review of the Owned Real Estate, Real Property Leases, Easements and Permits including licenses, to determine whether Sellers have good title thereunder and whether any consents or approvals are required for their assignment.  At Buyer’s request, Sellers will provide Buyer with continuing access to Sellers’ right-of-way files covering the Owned Real Estate, Real Property Leases and Easements.  If consents or approvals are required for assignment of any part of the Owned Real Estate, Real Property Leases, or Easements, Sellers shall, prior to Closing, obtain such consents and/or approvals, provided that (i) Buyer shall cooperate in obtaining any such consents and or approvals, at no expense to Buyer, and (ii) Buyer shall execute any reasonable documentation requested by the parties whose consent or approval may be required.

b.Sellers have disclosed on Exhibit M hereto any defects, deficiencies or exceptions in the Easements and Permits of which it is aware (“Exhibit M Defects”).  In the event Buyer becomes aware of any additional defects or deficiencies in the Easements and Permits not disclosed on Exhibit M, Buyer shall notify Sellers of such defects or deficiencies in writing within 120 days after Closing (“Additional Defects”).  Thereafter, Sellers shall cure and eliminate the Exhibit M Defects listed on Exhibit M under the heading of Right of Way Gaps Currently Being Handled and the Additional Defects within one (1) year after Closing.   It is provided, however, that Sellers shall have no obligation to cure and eliminate any Exhibit M Defects that is not listed under the heading of Right of Way Gaps Currently Being Handled.  In the event Sellers are unable to cure and eliminate any defects or deficiencies, Sellers shall, as Buyer’s sole remedy, (i) indemnify Buyer against any Liabilities arising as a result of such defects or deficiencies of which Buyer has given Sellers timely notice as provided in this Section 6.5(b), (ii) pay Buyer its reasonable cost of re-routing the System around the deficient or defective right(s)-of-way or Permit, including, without limitation, all costs incurred for rights-of-way and easements.

c.Sellers have disclosed on Exhibit L hereto the Easements for which consents are required to assign the same, but for which consents to assign have not yet been obtained.  Sellers shall have one (1) year following Closing to obtain such consents.  As to any Easements requiring consent to assign to Buyer for which Seller has not obtained such consents by Closing, such Easements will not be transferred or assigned to Buyer at Closing.  During that one-year period, or until Seller has

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obtained the required consents, Seller shall (A) retain such Easements for the benefit of Buyer, (B) provide gathering services in the pipelines located on such Easements for buyer to the same extent that would have been available to Buyer had the assignment of the Easements been made, and (C) engage Buyer as Seller’s subcontractor to operate, maintain, repair, use and replace such pipelines.  Upon obtaining the required consents, Seller shall assign such Easements to Buyer in same form as set forth on Exhibit “P”, attached hereto.  In the event Sellers are unable to obtain such consents within such period, Sellers shall, as Buyer’s sole remedy (i) indemnify Buyer against any liabilities arising from the failure to obtain such consents, and (ii) pay Buyer is reasonable cost of re-routing the System around the property covered by the Easements for which consents to assign have not been obtained, including, without limitation, all costs incurred for rights-of-way and easements.  During the period, if any, that buyer is acting as Seller’s subcontractor with respect to any pipelines under this Section 6.5 (c).  Buyer shall indemnify and hold Seller harmless from and against any Liabilities or Environmental Claims arising from Buyer’s operation, maintenance, repair, use or replacements of such pipelines during that period.

6.6Right to Terminate.

a.Except as hereinafter provided, Buyer shall have the right to terminate this Agreement only in the event that the Properties are subject to Material Adverse Environmental Conditions as defined above.

b.To terminate this Agreement pursuant to this Section 6.6, Buyer shall provide written notice to Sellers and the Escrow Agent on or before July 20, 2004, at 3:00 p.m. Central Standard Time (the “Environmental Defect Notice Date”).  To be effective, any such notice shall specifically identify and describe the basis for such termination, and shall include substantial evidence thereof, including a copy of the environmental assessment report or reports.

c.Notwithstanding the delivery of such a notice of termination by Buyer to Sellers, this Agreement shall not be terminated if by July 30, 2004 (1) Sellers remedy or agree to remedy such Material Adverse Environmental Conditions; or (2) Sellers and Buyer mutually agree on an adjustment to the Purchase Price, which adjustment shall reflect Buyer’s cost to remedy such condition.

d.If Sellers agree to remedy specific Material Adverse Environmental Condition(s), then all negotiations and contacts with state, federal and local agencies for approval and review of such remedial action shall be made by Sellers, and Buyer shall make no independent contacts with any of the agencies relative to such remediation.

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e.If the Agreement is terminated pursuant to the right specified in this Section, the Earnest Money Deposit shall be returned to Buyer.

6.7Post-Closing Environmental Claims.

a.Sellers and Buyer shall bear the cost of claims under Environmental Laws arising from incidents with respect to the Properties which occur prior to the Closing Date as follows:

i.Sellers shall release Buyer from and shall fully protect, indemnify and defend Buyer, its affiliates, and each of their officers, agents and employees and hold them harmless from and against any and all Liabilities relating to, arising out of, or connected, directly or indirectly, with respect to any Claims under Environmental Laws with respect to which (i) Buyer has given written notice to Sellers within 2 years following the Closing Date, and (ii) any Claims relating to Environmental Conditions that Sellers agreed to remediate under the provisions of Section 6.6, all to the extent that such Claims under (i) (ii) relate to, grow out of, or are connected with acts or omissions, or conditions occurring or existing before Closing.  Further Sellers shall reimburse Buyer for reasonable costs incurred by Buyer with respect to claims of which Buyer provided written notice to Sellers within two (2) years after the Closing Date for Claims under Environmental Laws for conditions existing on or before Closing that a governmental agency mandates remediation under a law or regulation which was applicable as of the Closing Date, including all costs of remediation, and all fines, penalties and assessments, and property damage claims from third parties on whose land such remediation takes place (collectively “Environmental Remediation Costs”), provided Buyer also bears a portion of such costs according to the following schedule:

i.Buyer shall pay 100% of the first $500,000 of Environmental Remediation Costs.

ii.Of the next $1,000,000.00 in Environmental Remediation Costs, Buyer and Sellers shall each pay 50%.

iii.Sellers shall be responsible for all Environmental Remediation Costs in excess of $1,500,000.

Any costs incurred by Buyer for any claims that Buyer did not give specific written notice describing the claim within two (2) years after Closing shall not be paid or reimbursed by Sellers.

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6.8Buyer’s Release and Indemnification for Post-Closing Environmental Claims.

a.Buyer, its successors and assigns (herein collectively “Buyer Indemnitor”) shall release, indemnify, defend and hold harmless Sellers, and their officers, directors, employees, contractors, representatives, and successors (collectively “Seller Indemnitee”) from all claims asserted against Seller Indemnitee by any governmental agency, person or entity arising from or related to Buyer Indemnitor’s ownership, operation, use, repair, removal, separation or control of the Properties from and after Closing, except to the extent related to any acts or omissions, or conditions first occurring or existing before Closing.

b.If any action, suit, proceeding or claim is commenced, or if any claim, demand or assessment is asserted, by a third party in respect of which Sellers are entitled to be indemnified under this Section, Sellers shall notify Buyer thereof and Buyer shall defend against the action, suit, proceeding or claim and fully indemnify Sellers thereforth.

6.9Sellers’ Release and Indemnification for Pre-Closing Liabilities.

a.Sellers shall release Buyer from and shall fully protect, indemnify and defend Buyer, its affiliates, and each of their officers, agents and employees and hold them harmless from and against any and all Liabilities relating to, arising out of, or connected, directly or indirectly, with the ownership or operation of the Properties, or any part thereof, pertaining to the period of time prior to the Closing Date; including without limitation, Liabilities relating to (i) injury or death of any person or persons whomsoever, (ii) damages to or loss of any property or resources, (iii) common law causes of action such as negligence, gross negligence, strict liability, nuisance or trespass, (iv) fault imposed by statute, rule, regulation or otherwise, (v) violation of the terms of any agreements or contracts, or (vi) acts or omissions, or conditions or circumstances occurring or existing prior to the Closing Date, except, however, the provisions of Section 6.7 hereof shall be applicable with respect to claims under Environmental Laws.

ARTICLE VII

COVENANTS, CLOSING CONDITIONS AND CLOSING

7.1Covenants of Sellers.  From the date hereof until the Closing, Sellers (i) will operate the Properties in the ordinary course and in compliance with all applicable laws, (ii) except for commitments existing under the Capital Expenditure Contracts, will not, without the prior written consent of Buyer, which consent shall not be unreasonably withheld, commit to any operation reasonably anticipated by Sellers to require future capital expenditures by the owner of the Properties in excess of $150,000, or make any capital expenditures in excess of $150,000 (iii) terminate or materially amend any of the Contracts, Real Property Leases or Easements, or execute or enter into any new material agreements affecting the Properties, (iv) will maintain generally insurance coverage on the

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Properties presently furnished by nonaffiliated third parties in the amounts and of the types presently in force, (v) will use commercially reasonable efforts to maintain in full force and effect all Real Property Leases and Easements, (v) will maintain and comply with all Permits, (vii) will not transfer, sell, hypothecate, encumber or otherwise dispose of any of the Properties, (viii) from and after the date of this Agreement until Closing, Seller shall diligently pursue all projects set forth in the Capital Expenditure Contracts in accordance with the terms thereof.  The provisions hereof shall not effect or apply to the capital expenditures of Sellers under the contracts described in Sections 2.5, 2.6, 2.7, and 2.8 above.

a.Financial Statements.  Sellers acknowledge that, in order for Buyer to comply with its reporting obligations under the Securities Exchange Act of 1934, as amended (the Exchange Act) and Regulations S-X promulgated by the Securities and Exchange Commission (SEC), Buyer will be required to file with SEC on a Current Report on Form 8-K historical financial statements for the business represented by the Properties audited in accordance with generally accepted auditing principles in the United States, together with an audit opinion thereon by BKD, Sellers independent public accountants, and a consent of such accountants to the filing thereof by Buyer with the SEC (collectively, the Audited Financial Statements and Opinion).  Each of the Sellers agrees to use its commercially reasonable efforts to provide whatever other assistance is necessary (including, but not limited to, seeking the assistance and consent of its independent public accountants) to enable Buyer to file the Audited Financial Statements and Opinion within 75 days of the Closing Date.  Buyer shall pay for any services provided by the accountants pursuant to this provision.

7.2Governmental Filings.

a.Buyer and Sellers shall, as promptly as practicable and in any event no later than July 15, 2004, file under the HSR Act with the Federal Trade Commission and the Department of Justice, as applicable, the notification and report form required for the transaction contemplated herein.  Each party will as promptly as practicable furnish all supplemental information which may be reasonably requested in connection therewith, including all information subject to secondary requests.  Each party shall request expedited treatment of such filing.  Buyer shall be obligated to use its best efforts and do all things reasonably required to obtain HSR approval.  If failure by either party to obtain timely authorization from the Federal Trade Commission or the Department of Justice results in the inability of the parties to close on the Closing Date, the time for Closing shall automatically be extended until such date as Closing can occur in compliance with the HSR Act, but in no event will the Closing Date be extended past August 30, 2004, unless further extension is mutually agreed upon by the parties.  Buyer shall pay any filing fees in connection with the filings and proceedings required by the HSR Act.  Sellers and

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Buyer shall pay their own attorney fees incurred in connection with the filings and proceedings required by the HSR Act.

b.In addition to filings under the HSR Act provided above, Sellers shall timely make all required governmental filings and will cooperate with Buyer in all respects in connection with required governmental filings.  Sellers shall cooperate with Buyer in connection with any requests for information to obtain any necessary approvals (or to allow the applicable time periods to expire).

c.The Parties shall each deliver to the other drafts of any governmental filings and all other materials to be submitted in connection therewith sufficiently in advance of any such submission so that the other may review and comment upon such filings and other materials.

7.3Closing Conditions.

a.Conditions of Sellers to Closing. The obligations of Sellers to consummate the transactions contemplated by this Agreement are subject, at the option of Sellers, to the satisfaction on or prior to the Closing of each of the following conditions:

i.Representations.  The representations and warranties of Buyer set forth in Article 5 shall be true and correct in all material respects as of the Closing Date as though made on and as of the Closing Date;

ii.Performance.  Buyer shall have performed and observed, in all material respects, all covenants and agreements to be performed or observed by it under this Agreement prior to or on the Closing Date;

iii.Pending Litigation.  No suit, action or other proceeding by a third party (including any governmental body) seeking to restrain, enjoin or otherwise prohibit the consummation of the transactions contemplated by this Agreement shall be pending before any governmental body;

iv.HSR.  The applicable time period under the HSR Act notification has expired.

b.Conditions of Buyer to Closing. The obligations of Buyer to consummate the transactions contemplated by this Agreement are subject, at the option of Buyer, to the satisfaction on or prior to the Closing of each of the following conditions:

i.Representations.  The representations and warranties of Sellers set forth in Article 4 shall be materially true and correct as of the date of this Agreement and as of the Closing Date as though made on and as of the Closing Date; Except, however, the existence of a

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violation of Environmental Laws with respect to the System shall not excuse Buyer from its obligation to close as such condition is specifically provided for pursuant to the provisions of Section 6.6.

ii.Performance.  Sellers shall have performed and observed, in all material respects, all covenants and agreements to be performed or observed by it under this Agreement prior to or on the Closing Date.

iii.Pending Litigation.  No suit, action or other proceeding by a third party (including any governmental body) seeking to restrain, enjoin or otherwise prohibit the consummation of the transactions contemplated by this Agreement shall be pending before any governmental body.

iv.HSR.   The applicable time period under the HSR Act notification has expired.

7.4Closing.

a.The “Closing” (hereby defined) of this sale shall occur on or before August 30, 2004, at the offices of Sellers at 6655 South Lewis, Suite 222, Tulsa, Oklahoma 74136, unless the parties mutually agree to another location.  Time shall be of the essence to this Agreement.

b.At the Closing, Sellers and Buyer shall execute and/or deliver one or more of each of the following documents:

i.Certified Resolutions of Buyer and Sellers authorizing all aspects of transactions contemplated herein; and

ii.Any other documents, instruments, and/or certificates reasonably requested by Sellers or Buyer or otherwise contemplated by this Agreement;

iii.A certificate of non-foreign status provided to Buyer by Sellers;

iv.Incumbency certificates for all signatory officers of Buyer and Sellers.

v.Transitions and Services Agreement attached hereto as Exhibit BB.

c.At Closing, Sellers shall execute and deliver:

i.A Special Warranty Deed covering the Owned Real Estate in the form attached hereto as Exhibit N;

ii.An Assignment of the Real Property Leases in the form attached hereto as Exhibit O;

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iii.An Assignment of the Easements in the form attached hereto as Exhibit P;

iv.An Assignment of the Gathering Lines in the form attached hereto as Exhibit Q;

v.A Bill of Sale covering the Compressor Stations, the Processing Facilities, the Equipment and the Parts Inventory in the form attached hereto as Exhibit R;

vi.An Assignment of the Permits to the extent assignable in the form attached hereto as Exhibit S;

vii.An Assignment of the Contracts in the form attached hereto as Exhibit T;

d.At Closing, Sellers and Buyer shall execute the following Assignment and Assumption Agreements:

i.An Assignment and Assumption of Lessee’s Rights and Obligations under Equipment Lease in the form attached hereto as Exhibit U for each of the Equipment Leases; and

ii.An Assignment and Assumption of Sellers’ rights and obligations under the EPC Contract in the form attached hereto as Exhibit V; and

iii.An Assignment and Assumption of Sellers’ rights and obligations under the ChevronTexaco Contract, in the form attached hereto as Exhibit W.

iv.An Assignment and Assumption of Sellers’ rights and obligations under the NGPL contracts in the form attached hereto as Exhibit X.

v.An Assignment and Assumption of Sellers’ rights and obligations under the Total E&P Contract in the form attached hereto as Exhibit Y.

e.The above listed closing documents shall be executed at Closing and made effective as of the Effective Time, unless Sellers and Buyer mutually agree to the contrary.  The Escrow Agent shall deliver the Earnest Money to Sellers, and Buyer shall deliver the balance of the Purchase Price to Sellers’ account by wire transfer of immediately available funds at Closing, without discount or deduction other than as expressly set forth in this

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Agreement and shown on a closing statement executed by both Buyer and Sellers.

ARTICLE VIII

POST-CLOSING RESPONSIBILITIES

8.1Consents.  Certain of the Contracts provide, by their terms, that the assignment thereof by Sellers requires the consent of other parties to the Contracts.  Sellers shall be obligated to obtain such consents which shall be furnished to Buyer upon their receipt, which may be after Closing.  Receipt of such consents shall not be a condition to Buyer’s obligation to perform its obligations at Closing, but Sellers shall provide such consents within 180 days after Closing.  Sellers shall facilitate the continuity and performance of any of the Contracts for which consents have not been procured prior to Closing until such consents are obtained.  In performance of such obligation, Sellers shall assure that Buyer receives the benefits of such Contracts which Buyer would have received if the consent had been obtained, including any natural gas sold thereunder, and Buyer shall fully perform Sellers’ obligations under such Contracts.  In the event Sellers receive funds attributable to periods after the Effective Time to which Buyer would be entitled as a result of such consents not being procured (or otherwise), Sellers shall immediately transmit or pay the same to Buyer.  Sellers shall be responsible for and shall indemnify and hold Buyer harmless from any and all claims and Liabilities asserted by any counterparty to a Contract relating to the Closing of the transactions hereunder without such consents.

8.2Permits.  It shall be Buyer’s responsibility to obtain the issuance or transfer of all Federal, state or municipal licenses, registrations and other operational permits and authority; provided however, that Sellers shall reasonably cooperate with Buyer’s reasonable efforts to obtain the transfer of such permits.

8.3Sales and Other Taxes.  As may be required by relevant taxing agencies, Sellers shall collect and Buyer shall pay on the date of Closing all applicable state and local sales tax, use tax, gross receipts tax, business license tax and other taxes arising as a result of the transactions hereunder, except taxes imposed by reason of income to Sellers.  Any state or local tax specified above, inclusive of any penalty and interest, assessed at a future date against Sellers with respect to the transaction covered herein shall be paid by Buyer or, if paid by Sellers, Buyer shall promptly reimburse Sellers therefor.  Any filing fees, recording fees or other charges of governmental agencies or departments to file or record the deeds, assignments and other documents delivered at Closing, which may be due, shall be paid by Buyer.

8.4Transfer of System By Buyer.  In the event Buyer sells, assigns or transfers all or a substantial part of the System, Buyer shall cause its transferee to assume with Buyer Buyer’s liability for any obligations of Buyer to Sellers under this Agreement.  Such assumption shall not affect Buyer’s continuing responsibility for such obligations.

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ARTICLE IX

MISCELLANEOUS

9.1Post-Closing Operation by Sellers.  Buyer may hire the field employees of Sellers engaged in the operation of the System after the Closing, and Sellers consent thereto.

9.2Default.  If Buyer defaults on or prior to Closing in a material way on Buyer’s obligations, including but not limited to Buyer’s absence at the designated time and place for Closing, Sellers shall be entitled, as their sole and exclusive remedy, to be paid and retain the Earnest Money Deposit as liquidated damages.  Further, Sellers shall be free immediately to sell the Properties to any third party without any restriction under or by reason of this Agreement.  If Sellers default on or prior to Closing in a material way on Sellers’ obligations, including but not limited to Sellers’ absence at the designated time and place for Closing, Buyer may specifically enforce Sellers’ obligation to close or, at its option, may terminate this Agreement and receive a refund of the Earnest Money Deposit, in addition to all of its other rights or remedies at law or in equity.  In the event that Closing fails to occur due to a failure of Section 7.3(b)(iii), or due to the failure to receive HSR approval after Buyer’s performance of its obligations under Section 7.2 hereof, Buyer shall be entitled to a refund of the Earnest Money Deposit.

9.3Notices.  All notices, requests, demands, instructions and other communications required or permitted to be given hereunder shall be in writing and shall be delivered personally, mailed by registered mail, postage prepaid or sent by facsimile, as follows:

IF TO SELLERS, ADDRESSED TO:

American Central Eastern Texas Gas Company, Limited Partnership

ACGC Gathering Company, L.L.C.

ATTN: Anthony Michog, Executive Vice President

6655 South Lewis, Suite 222

Tulsa, Oklahoma 74136

Facsimile No.: 918-493-8660

IF TO BUYER, ADDRESSED TO:

MarkWest Energy East Texas Gas Company L.P.

155 Inverness Drive West, Suite 200

Englewood, Colorado 80112

Attention: Randy S. Nickerson

Facsimile No.: (303) 290-8769

or to such other place as either party may designate as to itself by written notice to the other.  All notices will be deemed given on the date of receipt at the appropriate address.

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9.4Governing Law.  The provisions of this Agreement and the documents delivered pursuant hereto shall be governed by and construed in accordance with the laws of the State of Texas without regard to its conflicts of laws provisions which if applied might require the application of the laws of another jurisdiction.

9.5Assignment.  This Agreement shall be binding upon and shall inure to the benefit of the parties hereto and their respective permitted successors and assigns.  This Agreement may not be assigned, in whole or in part, without the prior written consent of the other party hereto, and any such assignment that is made without such consent shall be void and of no force and effect.

9.6Entire Agreement; Amendments.  This Agreement, including the attached Exhibits, constitutes the entire agreement between the parties hereto with respect to the subject matter hereof, superseding any and all prior negotiations, discussions, agreements and understandings, whether oral or written, relating to such subject matter.  Exhibits “A” through “DD”, as more specifically described herein or in the attached “Schedule of Exhibits”, are incorporated herein for all purposes.  This Agreement may not be amended, and no rights hereunder may be waived except by a written document signed by the party to be charged with such amendment or waiver.

9.7Publicity.  All notices to third parties and other publicity concerning the transactions contemplated by this Agreement shall be jointly planned and coordinated by and between Buyer and Sellers.  No party shall act unilaterally in this regard without the prior written approval of the other, unless required by law.

9.8No Third Party Beneficiary.  It is expressly understood that the provisions of this Agreement do not impart enforceable rights in anyone who is not a Party or a successor or assign of a party hereto.

9.9Joint Efforts.  This Agreement was prepared with each of the Parties having access to their own legal counsel.  Accordingly, the Parties stipulate and agree that this Agreement shall be deemed and considered for all purposes as prepared through the joint efforts of the Parties and shall not be construed against one Party or the other as a result of the preparation, submittal or other event of negotiation or drafting.

9.10Headings.  The division of this Agreement into articles, sections, and subsections and the insertion of headings and table of contents, if any, are for convenience only and shall not be used in or affect the construction or interpretation of this Agreement.

9.11Severability.  If any term or provision or portions thereof is deemed invalid or unenforceable pursuant to a final determination of any court of competent jurisdiction or as a result of future laws, such determination or action shall be construed so as not to affect the validity or effect of any other portion or portions of this Agreement.  Furthermore, it is the intent and agreement of the Parties that

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this Agreement shall be deemed amended by modifying such term or provision to the extent necessary to render it valid and enforceable while preserving the original intent of the affected term or provision or if that is not possible, by substituting therefor another provision that is valid and enforceable and achieves the same objective.

9.12Further Assurances and Documents.  Each Party shall promptly take such further actions, including the execution of further documents, as shall be reasonably required in order to carry out the intent and purposes of this Agreement or to protect the rights and remedies hereby created or intended to be created in favor of one or both Parties.

9.13Risk of Loss.  Until Closing, risk of loss to the Properties shall be on Sellers.  In the event of a casualty loss with respect to the Properties prior to Closing involving damages in excess of $100,000.00, Buyer may terminate this Agreement and be repaid the Earnest Money Deposit unless Sellers pay the cost of repair of such damage.

9.14Litigation.  In the event of legal proceedings to interpret or enforce the provisions hereof, the prevailing party shall be entitled to recover from the other party its reasonable attorneys’ fees and costs of the action.

9.15Multiple Counterparts.  This Agreement may be executed in a number of identical counterparts and by facsimile signatures.  If so executed, each of such counterparts and facsimile signatures is to be deemed an original for all purposes, and all such counterparts shall, collectively, constitute one (1) agreement.

Executed on behalf of the parties hereto on the dates set forth below the respective signature lines but effective as of the date first set forth herein above.

BUYER:
	MARKWEST ENERGY EAST TEXAS GAS COMPANY L.P.
	By:	/s/ MarkWest Energy East Texas Gas Company, L.P.
	Title:   MarkWest Energy East Texas Gas Company, L.P.
	Date:
SELLERS:	AMERICAN CENTRAL EASTERN TEXAS
	GAS COMPANY LIMITED PARTNERSHIP
	By:  AMERICAN CENTRAL GAS
	TECHNOLOGIES, INC., General Partner

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	By:	/s/ American Central Eastern Texas Gas Company Limited Partnership
	Title: American Central Eastern Texas Gas Company Limited Partnership
	Date:
			ACGC GATHERING COMPANY, L.L.C.
			By:  AMERICAN CENTRAL GAS
			TECHNOLOGIES, INC., Manager
			By:	/s/ ACGC Gathering Company, L.L.C.
			Title: ACGC Gathering Company, L.L.C.
			Date:
JHF.AMERICAN CENTRAL EASTERN TEXAS.PSA.061004

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Schedule of Exhibits (1)

Exhibit “A”	Lands and Surface Estates
Exhibit “B”	Real Property Leases and Leasehold Interests
Exhibit “C”	Easements
Exhibit “D”	Gathering Lines
Exhibit “E”	Compressor Stations
Exhibit “F”	Processing Facilities
Exhibit “G”	Personal Property
Exhibit “H”	Permits
Exhibit “I”	Contracts
Exhibit “J”	Equipment Leases
Exhibit “K”	Escrow Agreement
Exhibit “L”	Contract Assignment Consents Needed
Exhibit “M”	Exceptions, Defects or Deficiencies in Easements to be Accepted by Buyer
Exhibit “N”	Special Warranty Deed covering Owned Real Estate
Exhibit “O”	An Assignment of the Real Property Leases
Exhibit “P”	An Assignment of the Easements and Rights-of-Way
Exhibit “Q”	An Assignment of the Gathering Lines
Exhibit “R”	A Bill of Sale covering the Compressor Stations, the Processing Facilities and the Parts Inventory
Exhibit “S”	An Assignment of Permits
Exhibit “T”	An Assignment of the Contracts
Exhibit “U”	Assignment and Assumption of Rights under Equipment Lease
Exhibit “V”	Assignment and Assumption of Rights under EPC Contract
Exhibit “W”	Assignment and Assumption of Rights under ChevronTexaco Contract

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Exhibit “X”	An Assignment and Assumption of Sellers’ Rights and
	Obligations Under the NGPL Contracts
Exhibit “Y”	An Assignment & Assumption of Total E & P Contract
Exhibit “Z”	Capital Expenditures
Exhibit “AA”	Excluded Assets
Exhibit “BB”	Transition Services Agreement
Exhibit “CC”	Guaranty Assumption Agreement
Exhibit “DD”	Panola System Map

(1) Exhibits to the Asset Purchase and Sale Agreement have been ommitted.

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ADDENDUM TO

ASSET PURCHASE AND SALE AGREEMENT

AMERICAN CENTRAL EASTERN TEXAS GAS COMPANY LIMITED PARTNERSHIP (“Seller”) and MARKWEST ENERGY EAST TEXAS GAS COMPANY L.P. (“Buyer”) are parties to that certain Asset Purchase and Sale Agreement dated July 1, 2004, relating to the Panola Gas System in Panola County, Texas (the “Purchase Agreement”).  The parties wish to modify the terms of the Purchase Agreement as provided herein.

NOW, THEREFORE, the Purchase Agreement is hereby amended as follows:

1.Section 2.8 of the Purchase Agreement provides that Seller will assign and Buyer will assume certain obligations under the NGPL Contracts as defined by the Purchase Agreement.  Buyer has determined to enter into a new agreement with Natural Gas Pipeline Company of America (“NGPL”) to replace the Operational Gas Balancing Agreement and, therefore, the existing Operational Gas Balancing Agreement between NGPL and Seller will not be assigned to Buyer at Closing under the Purchase Agreement.

2.Section 3.2(a), Operating Revenues and Expenses, of the Purchase Agreement shall be replaced in its entirety by the following:

“a.All revenues attributable to the operation of the Properties prior to the Effective Time shall be owned by and for the account of Seller.  Seller shall be entitled to all operating revenues and shall be responsible for all operating expenses and related accounts payable arising in the ordinary course of business attributable to the Properties, in each case to the extent they relate to the time prior to the Effective Time.  Buyer shall be entitled to all operating revenues and shall be responsible for the payment of all operating expenses and related accounts payable arising in the ordinary course of business attributable to the Properties, in each case to the extent they relate to time after the Effective Time.  The actual amounts or values associated with the above shall be accounted for to the extent known in the Preliminary Settlement Statement with the final reconciliation contained in the Final Accounting Settlement.  Buyer shall not be obligated to pay or reimburse Seller for the services to be provided under the Transition Services Agreement to be executed by the parties at Closing, except as provided by that agreement.”

3.Buyer’s lender has requested that the Deed of Trust instruments described in Section 4.1(i) of the Purchase Agreement not be released at Closing.  The Buyer and Seller acknowledge that the Deed of Trust instruments described in 4.1(i) of the Purchase Agreement shall not be released at Closing, but that Seller shall, at Closing, pay to Wachovia Bank, National Association, as

36

Administrative Agent, all amounts due at Closing under such Deed of Trust instruments.

This Addendum to Asset Purchase and Sale Agreement is executed the            day of July, 2004.

MARKWEST ENERGY EAST TEXAS		AMERICAN CENTRAL EASTERN
GAS COMPANY L.P.		GAS COMPANY LIMITED PARTNERSHIP
By: MARKWEST TEXAS GP, LLC					By:	AMERICAN CENTRAL GAS
General Partner						TECHNOLOGIES, INC.,
						General Partner
By:	/s/ MarkWest Energy East Texas Gas Company L.P.
President		By:	/s/ American Central Eastern Gas Company Limited Partnership
		President
				ACGC GATHERING COMPANY, L.L.C.
					By:	AMERICAN CENTRAL
						EASTERN TEXAS GAS
						COMPANY LIMITED
						PARTNERSHIP, Manager
					By:	AMERICAN CENTRAL GAS
						TECHNOLOGIES, INC.,
						General Partner
					By:	/s/ ACGC Gathering Company, L.L.C.
		President
JHF.AMERICAN CENTRAL MARKWEST.ADDENDUM TO APSA

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EX-4.1

Exhibit 4.1

Execution Copy

UNIT PURCHASE AGREEMENT

by and among

MARKWEST ENERGY PARTNERS, L.P.,

MARKWEST ENERGY GP, L.L.C.

KAYNE ANDERSON ENERGY FUND II, L.P.,

KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P.,

KAYNE ANDERSON MLP FUND, L.P.,

KAYNE ANDERSON CAPITAL INCOME FUND, LTD.,

KAYNE ANDERSON INCOME PARTNERS, L.P.,

HFR RV PERFORMANCE MASTER TRUST,

TORTOISE ENERGY INFRASTRUCTURE CORPORATION

AND

ENERGY INCOME AND GROWTH FUND

UNIT PURCHASE AGREEMENT

UNIT PURCHASE AGREEMENT, dated as of July 29, 2004 (this “Agreement”), by and among MARKWEST ENERGY PARTNERS, L.P. (“MarkWest”) and MARKWEST ENERGY GP, L.L.C. (“MarkWest GP”) (solely for purposes of Sections 3.15 and 5.13) and each of KAYNE ANDERSON ENERGY FUND II, L.P. (“KAEF”), KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P. (“KACIP”), KAYNE ANDERSON MLP FUND, L.P. (“KAMLP”), KAYNE ANDERSON CAPITAL INCOME FUND, LTD. (“KACIF”), KAYNE ANDERSON INCOME PARTNERS, L.P. (“KAIP”), HFR RV PERFORMANCE MASTER TRUST (“HFR”) (collectively, “Kayne Anderson”),TORTOISE ENERGY INFRASTRUCTURE CORPORATION (“Tortoise”) and ENERGY INCOME AND GROWTH FUND (“Energy Income”) (each of KAEF, KACIP, KAMLP, KACIF, KAIP, HFR, Tortoise and Energy Income a “Purchaser” and collectively, the “Purchasers”).

In consideration of the mutual covenants and agreements set forth herein and for good and valuable consideration, the receipt of which is hereby acknowledged, the parties hereby agree as follows:

ARTICLE I.
DEFINITIONS

Section 1.01           Definitions.  As used in this Agreement, and unless the context requires a different meaning, the following terms have the meanings indicated:

“ACGC” means ACGC Gathering Company, L.L.C., an Oklahoma limited liability company.

“Action” against a Person means any lawsuit, action, proceeding, investigation or complaint before any Governmental Authority, mediator or arbitrator.

“Affiliate” means, with respect to a specified Person, any other Person, directly or indirectly controlling, controlled by or under direct or indirect common control with such specified Person.  For purposes of this definition, “control” (including, with correlative meanings, “controlling”, “controlled by”, and “under common control with”) means the power to direct or cause the direction of the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise.

“American Central” means American Central Eastern Texas Gas Company Limited Partnership, an Oklahoma limited partnership.

“American Central Acquisition” means MarkWest’s proposed acquisition of the east Texas Carthage gathering system and gas processing assets pursuant to the American Central PSA.

“American Central Closing” means the closing of the American Central Acquisition.

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“American Central PSA” means that certain Asset Purchase and Sale Agreement dated as of July 1, 2004, between MarkWest Energy East Texas Gas Company L.P., a Delaware limited partnership and indirect wholly owned subsidiary of MarkWest, as buyer, and American Central and ACGC, as sellers.

“Basic Documents” means, collectively, this Agreement, the Registration Rights Agreement, and any and all other agreements or instruments executed and delivered to the Purchasers by MarkWest or any Subsidiary of MarkWest hereunder or thereunder.

“Business Day” means any day other than a Saturday, Sunday, or a legal holiday for commercial banks in Wilmington, Delaware.

“Closing” shall have the meaning specified in Section 2.03.

“Closing Date” shall have the meaning specified in Section 2.03.

“Commission” means the United States Securities and Exchange Commission.

“Commitment” means, with respect to a particular Purchaser, the commitment of such Purchaser until the Termination Date to purchase such Purchaser’s Purchased Units on the terms and subject to the conditions set forth in this Agreement.

“Commitment Date” means the date of this Agreement.

“Common Unit Price” shall have the meaning specified in Section 2.06(b).

“Common Units” means the common units of MarkWest.

“Confidential Information” means all oral or written information, documents, records and data that MarkWest or its Representatives furnishes or otherwise discloses to a Purchaser or any of its Representatives, including any information relating to either American Central or ACGC, together with all copies, extracts, analyses, compilations, studies, memoranda, notes or other documents, records or data (in whatever form maintained, whether documentary, computer or other electronic storage or otherwise) prepared by any Person that contain or otherwise reflect or are generated from such information, documents, records, or data.  The term “Confidential Information” does not include any information that (a) at the time of disclosure or thereafter is generally available to the public (other than as a result of a disclosure by such Purchaser or its Representatives), (b) is developed by such Purchaser or any of its Representatives, independent of, and without reliance in whole or in part on, any Confidential Information or any knowledge of Confidential Information, (c) becomes available to such Purchaser or its Representatives on a non-confidential basis from a source other than MarkWest or its Representatives who, insofar as is known to the recipient after reasonable inquiry, is not prohibited from transmitting the information to the recipient by a contractual, legal, fiduciary or other obligation to MarkWest or (d) was available to such Purchaser or its Representatives on a non-confidential basis prior to its disclosure to such Purchaser or its Representatives by MarkWest or its Representatives.

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“Exchange Act” means the Securities Exchange Act of 1934, as amended from time to time, and the rules and regulations of the Commission promulgated thereunder.

“Form 8-A” shall have the meaning set forth in Section 3.02(a).

“GAAP” means generally accepted accounting principles in the United States of America in effect from time to time.

“Governmental Authority” means, with respect to a particular Person, the country, state, county, city and political subdivisions in which such Person or such Person’s Property is located or which exercises valid jurisdiction over any such Person or such Person’s Property, and any court, agency, department, commission, board, bureau or instrumentality of any of them and any monetary authority which exercises valid jurisdiction over any such Person or such Person’s Property.  Unless otherwise specified, all references to Governmental Authority herein with respect to MarkWest means a Governmental Authority having jurisdiction over MarkWest, its Subsidiaries or any of their respective Properties.

“Indemnified Party” shall have the meaning specified in Section 5.02(c).

“Indemnifying Party” shall have the meaning specified in Section 5.02(c).

“Knowledge” means the actual knowledge of the individuals listed on Schedule 2.01 hereto.

“Law” means any federal, state, local or foreign order, writ, injunction, judgment, settlement, award, decree, statute, law, rule or regulation.

“Lien” means any interest in Property securing an obligation owed to, or a claim by, a Person other than the owner of the Property, whether such interest is based on the common law, statute or contract, and whether such obligation or claim is fixed or contingent, and including but not limited to the lien or security interest arising from a mortgage, encumbrance, pledge, security agreement, conditional sale or trust receipt or a lease, consignment or bailment for security purposes. For the purpose of this Agreement, a Person shall be deemed to be the owner of any Property which it has acquired or holds subject to a conditional sale agreement, or leases under a financing lease or other arrangement pursuant to which title to the Property has been retained by or vested in some other Person in a transaction intended to create a financing.

“MarkWest” has the meaning set forth in the introductory paragraph.

“MarkWest Financial Statements” means the financial statement or statements described or referred to in Section 3.03.

“MarkWest GP” has the meaning set forth in the introductory paragraph.

“MarkWest Material Adverse Effect” means any material and adverse effect on (a) the assets, liabilities, financial condition, business, operations or affairs of MarkWest

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and its Subsidiaries taken as a whole measured against those assets, liabilities, financial condition, business, operations or affairs reflected in the MarkWest SEC Documents filed with the Commission prior to the Commitment Date or from the facts represented or warranted in any Basic Document, or (b) the ability of MarkWest to consummate the American Central Acquisition or any of the transactions contemplated under the Basic Documents.

“MarkWest Related Parties” shall have the meaning specified in Section 5.02(b).

“MarkWest SEC Documents” shall have the meaning specified in Section 3.03.

“Partnership Agreement” means the Amended and Restated Agreement of Limited Partnership of MarkWest, dated as of May 24, 2002.

“Partnership Securities” means any class or series of equity interest in MarkWest (but excluding any options, rights, warrants and appreciation rights relating to an equity interest in MarkWest), including without limitation Common Units, Subordinated Units and Incentive Distribution Rights (as defined in the Partnership Agreement).

“Permits” means, with respect to MarkWest or any of its Subsidiaries, any licenses, permits, variances, consents, authorizations, waivers, grants, franchises, concessions, exemptions, orders, registrations and approvals of Governmental Authorities or other Persons necessary for the ownership, leasing, operation, occupancy and use of its Properties and the conduct of its businesses as currently conducted.

“Person” means any individual, corporation, company, voluntary association, partnership, joint venture, trust, limited liability company, unincorporated organization or government or any agency, instrumentality or political subdivision thereof, or any other form of entity.

“Prior Registration Rights Agreements” means the (i) Registration Rights Agreement dated November 20, 2002 by and between MarkWest and Tortoise MWEP, L.P. and (ii) Registration Rights Agreement dated June 13, 2003 by and among MarkWest and each party listed on Schedule A thereto (Tortoise MWEP, L.P. and each such party are collectively referred to herein as “Prior Rights Holders”).

“Property” means any interest in any kind of property or asset, whether real, personal or mixed, or tangible or intangible.

“Purchase Price” means, with respect to a particular Purchaser, the monetary commitment amount set forth opposite such Purchaser’s name under the column entitled “Total Purchase Price” on Schedule 2.02 hereto.

“Purchased Units” means, with respect to a particular Purchaser, the number of Common Units equal to the quotient determined by dividing (a) the monetary commitment amount set forth opposite such Purchaser’s name under the column entitled “Total Purchase Price” set forth on Schedule 2.02 hereto by (b) the Common Unit Price.

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“Purchaser” has the meaning set forth in the introductory paragraph.

“Purchaser Material Adverse Effect” means, with respect to a particular Purchaser, any material and adverse effect on (a) the assets, liabilities, financial condition, business, operations or affairs of such Purchaser, (b) the ability of such Purchaser to carry out its business as of the date hereof or to meet its obligations under the Basic Documents on a timely basis or (c) the ability of such Purchaser to consummate the transactions under any Basic Document.

“Purchaser Related Parties” shall have the meaning specified in Section 5.02(a).

“RBC” shall mean Royal Bank of Canada.

“Registration Rights Agreement” means the Registration Rights Agreement, to be entered into at the Closing, between MarkWest and the Purchasers in the form attached hereto as Exhibit A hereto.

“Representatives” of any Person means the officers, directors, employees, agents, counsel, investment bankers and other representatives of such Person.

“Securities Act” means the Securities Act of 1933, as amended from time to time, and the rules and regulations of the Commission promulgated thereunder.

“Subordinated Units” means the subordinated units of MarkWest.

“Subsidiary” means, as to any Person, any corporation or other entity of which: (i) such Person or a Subsidiary of such Person is a general partner or manager; or (ii) at least a majority of the outstanding equity interest having by the terms thereof ordinary voting power to elect a majority of the board of directors or similar governing body of such corporation or other entity (irrespective of whether or not at the time any equity interest of any other class or classes of such corporation or other entity shall have or might have voting power by reason of the happening of any contingency) is at the time directly or indirectly owned or controlled by such Person or one or more of its Subsidiaries.

“Termination Date” has the meaning set forth in Section 5.11(a).

Section 1.02           Accounting Procedures and Interpretation.  Unless otherwise specified herein, all accounting terms used herein shall be interpreted, all determinations with respect to accounting matters hereunder shall be made, and all Financial Statements and certificates and reports as to financial matters required to be furnished to the Purchasers hereunder shall be prepared, in accordance with GAAP applied on a consistent basis during the periods involved (except, in the case of unaudited statements, as permitted by Form 10-Q promulgated by the Commission) and in compliance as to form in all material respects with applicable accounting requirements and with the published rules and regulations of the Commission with respect thereto.

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ARTICLE II.
AGREEMENT TO SELL AND PURCHASE

Section 2.01           Authorization of Sale of Common Units.  MarkWest has authorized the issuance and sale to each of the Purchasers such Purchaser’s Purchased Units.

Section 2.02           Sale and Purchase.  Substantially contemporaneous with the consummation of the American Central Acquisition and subject to the terms and conditions hereof, at the Closing (as defined in Section 2.03) MarkWest hereby agrees to issue and sell to each Purchaser, and each Purchaser hereby agrees to purchase from MarkWest, such Purchaser’s Purchased Units, and each Purchaser agrees to pay MarkWest such Purchaser’s Purchase Price. The obligation of each Purchaser hereunder is several and not joint and is independent of the obligation of each other Purchaser, and the failure of, or MarkWest’s waiver of, performance by any Purchaser does not excuse performance by any other Purchaser or MarkWest.  In the event the American Central Acquisition is not consummated, (a) MarkWest shall be relieved of its obligation to issue and sell to each Purchaser such Purchaser’s Purchased Units and (b) each Purchaser shall be relieved of its obligation to purchase from MarkWest such Purchaser’s Purchased Units.

Section 2.03           Closing.  Subject to the terms and conditions hereof, the consummation of the purchase and sale of the Purchased Units hereunder (the “Closing”) shall take place substantially contemporaneous with the American Central Closing, but on or prior to the Termination Date, provided that MarkWest shall have given each Purchaser ten (10) Business Days (or such shorter period as shall be agreeable to all parties hereto) prior written notice of such designated closing date (such date, the “Closing Date”) at the offices of Vinson & Elkins, L.L.P., 1001 Fannin, Suite 2300, Houston, Texas 77002.

Section 2.04           Conditions to the Closing.

(a)           Mutual Conditions.  The respective obligation of each party to consummate the purchase and issuance and sale of the Purchased Units shall be subject to the satisfaction on or prior to the Closing Date of each of the following conditions (any or all of which may be waived by a particular party on behalf of itself in writing, in whole or in part, to the extent permitted by applicable Law):

(i)         no statute, rule, order, decree or regulation shall have been enacted or promulgated, and no action shall have been taken, by or before any Governmental Authority of competent jurisdiction which temporarily, preliminarily or permanently restrains, precludes, enjoins or otherwise prohibits the consummation of the transactions contemplated hereby or makes the transactions contemplated hereby illegal;

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(ii)        there shall not be pending any suit, action or proceeding by or before any Governmental Authority seeking to restrain, preclude, enjoin or prohibit the transactions contemplated by this Agreement;

(iii)       Substantially contemporaneous with the Closing, MarkWest shall consummate the American Central Acquisition;

(iv)       MarkWest and the Prior Rights Holders shall have delivered amendments to the Prior Registration Rights Agreements; and

(v)        The Common Units comprising the Purchased Units have, subject to issuance, been approved for listing on the American Stock Exchange.

(b)           Each Purchaser’s Conditions.  The respective obligation of each Purchaser to consummate the purchase of its Purchased Units shall be subject to the satisfaction on or prior to the Closing Date of each of the following conditions (any or all of which may be waived by a particular Purchaser, on behalf of itself in writing, in whole or in part, to the extent permitted by applicable Law):

(i)         (A) The representations and warranties of MarkWest contained in this Agreement shall be true and correct in all material respects (except that the representations and warranties of MarkWest contained in Sections 3.03 and 3.04 shall be true and correct in all respects) both when made and at and as of the Closing Date, as if made at and as of such time (except to the extent expressly made as of an earlier date, in which case as of such date), and (B) MarkWest shall have performed in all material respects all of its agreements and covenants to be performed prior to the Closing, and such Purchaser shall have received a certificate signed on behalf of MarkWest to such effect;

(ii)        MarkWest shall have paid the Commitment Fee required by Section 2.06(a) hereof; and

(iii)       MarkWest shall have entered into definitive loan documentation with RBC with terms substantially as contemplated by the commitment letter that was provided to the Purchasers on or prior to the Commitment Date, and all conditions precedent to the funding under such loan documentation shall have been satisfied, except for the issuance and sale of the Purchased Units as contemplated hereby, and the loan contemplated thereby shall fund substantially contemporaneously with the Closing.

(c)           MarkWest’s Conditions.  The obligation of MarkWest to consummate the sale of each of the Purchaser’s Purchased Units to each of the Purchasers shall be subject to the satisfaction on or prior to the Closing Date of the condition (which

8

may be waived by MarkWest in writing, in whole or in part, to the extent permitted by applicable Law) that the representations and warranties of such Purchaser contained in this Agreement shall be true and correct in all material respects both when made and at and as of the Closing Date, as if made at and as of such time (except to the extent expressly made as of an earlier date, in which case as of such date), and MarkWest shall have received a certificate from each of the Purchasers signed on behalf of such Purchaser to such effect.

Section 2.05           Deliveries.

(a)           At the Closing, subject to the terms and conditions hereof, MarkWest will deliver, or cause to be delivered, to each Purchaser:

(i)         The Purchased Units to be purchased by such Purchaser by delivery of certificates evidencing such Purchased Units at the Closing meeting the requirements of the Partnership Agreement, all free and clear of any Liens, encumbrances or interests of any other Person, and (subject to the terms and conditions hereof) Purchaser will make payment to MarkWest of such Purchaser’s Purchase Price by wire transfer of immediately available funds to an account designated by MarkWest in writing at least ten (10) Business Days (or such shorter period as shall be agreeable to all parties hereto) prior to the Closing;

(ii)        A certificate of the Secretary of State of the State of Delaware, dated a recent date, that MarkWest is in good standing;

(iii)       An opinion addressed to the Purchasers from Vinson & Elkins L.L.P. (or other legal counsel to MarkWest reasonably acceptable to the Purchasers), dated as of the Closing, in the form and substance attached hereto as Exhibit C; and

(iv)       The Registration Rights Agreement, which shall have been duly executed by MarkWest.

(b)           At the Closing, subject to the terms and conditions hereof, each Purchaser will deliver, or cause to be delivered to MarkWest, the Registration Rights Agreement, which shall have been duly executed by each such Purchaser.

Section 2.06           Consideration.

(a)           In exchange for each Purchaser’s Commitment to purchase its Purchased Units, MarkWest has, contemporaneously herewith, paid to each Purchaser a commitment fee in cash of one and one-half percent (1.5%) of such Purchaser’s Purchase Price (the “Commitment Fee”) and as set forth on Schedule 2.02 hereto opposite such Purchaser’s name under the column entitled “Commitment Fee.”  The Commitment Fee represents consideration for each Purchaser’s Commitment, irrespective of whether the Closing actually occurs.

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(b)           The amount per Common Units each Purchaser will pay to MarkWest to purchase the Common Units comprising the Purchased Units (the “Common Unit Price”) shall be the lesser of (i) $34.50 per Common Unit, an amount which represents ninety-one-point-five (91.5%) of the average closing price of the Common Units as reported by the Bloomberg Professional Financial Reporting Service for the twenty (20) trading days immediately ending and including July 12, 2004 less $0.50 and (ii) an amount per Common Unit equal to the closing price of the Common Units as reported by the Bloomberg Professional Financial Reporting Service for the trading day immediately prior to the Closing Date.

Section 2.07           Independent Nature of Purchasers’ Obligations and Rights.  The obligations of each Purchaser under any Basic Document are several and not joint with the obligations of any other Purchaser, and no Purchaser shall be responsible in any way for the performance of the obligations of any other Purchaser under any Basic Document.  Nothing contained herein or in any Basic Document, and no action taken by any Purchaser pursuant thereto, shall be deemed to constitute the Purchasers as a partnership, an association, a joint venture or any other kind of entity, or create a presumption that the Purchasers are in any way acting in concert or as a group with respect to such obligations or the transactions contemplated by the Basic Document.  Each Purchaser shall be entitled to independently protect and enforce its rights, including without limitation, the rights arising out of this agreement or out of the other Basic Documents, and it shall not be necessary for any other Purchaser to be joined as an additional party in any proceeding for such purpose.  Each Purchaser has been represented by its own separate legal counsel in their review and negotiation of the Basic Documents.  MarkWest has elected to provide all Purchasers with the same material terms and Basic Documents for the convenience of MarkWest and not because it was required or requested to do so by the Purchasers.

ARTICLE III.
REPRESENTATIONS AND WARRANTIES RELATED TO MARKWEST

MarkWest represents and warrants to each Purchaser as follows:

Section 3.01           Corporate Existence.  MarkWest:  (a) is a limited partnership duly organized, legally existing and in good standing under the laws of the State of Delaware; and (b) has all requisite power and authority, and has all governmental licenses, authorizations, consents and approvals necessary, to own, lease, use and operate its Properties and carry on its business as its business is now being conducted, except where the failure to obtain such licenses, authorizations, consents and approvals would not be reasonably likely to have a MarkWest Material Adverse Effect.  Each of MarkWest’s Subsidiaries that is a corporation is a corporation duly incorporated, validly existing and in good standing under the laws of the State or other jurisdiction of its incorporation and has all requisite power and authority, and has all governmental licenses, authorizations, consents and approvals necessary, to own, lease, use or operate its respective Properties and carry on its business as now being conducted, except where the failure to obtain such licenses, authorizations, consents and approvals would not be reasonably likely to have a MarkWest Material Adverse Effect.  Each Subsidiary of

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MarkWest that is not a corporation has been duly formed, is validly existing and in good standing under the laws of the State or other jurisdiction of its formation and has all requisite power and authority, and has all governmental licenses, authorizations, consents and approvals necessary, to own, lease, use or operate its respective Properties and carry on its business as now being conducted, except where the failure to obtain such licenses, authorizations, consents and approvals would not be reasonably likely to have a MarkWest Material Adverse Effect.  None of MarkWest or any of its Subsidiaries are in default in the performance, observance or fulfillment of any provision of, in the case of MarkWest, the Partnership Agreement or its Certificate of Limited Partnership or, in the case of any Subsidiary of MarkWest, its respective certificate of incorporation, bylaws or other similar organizational documents.  Each of MarkWest and its Subsidiaries is duly qualified or licensed and in good standing as a foreign corporation, and is authorized to do business, in each jurisdiction in which the ownership or leasing of its respective Properties or the character of its respective operations makes such qualification necessary, except where the failure to obtain such qualification, license, authorization or good standing would not be reasonably likely to have a MarkWest Material Adverse Effect.

Section 3.02           Capitalization and Valid Issuance of Purchased Units.

(a)           As of the Commitment Date, the issued and outstanding limited partner interests of MarkWest consist of 3,997,502 Common Units and 3,000,000 Subordinated Units.  The only issued and outstanding general partner interests of MarkWest are the interests of the General Partner described in the Partnership Agreement.All outstanding Common Units and Subordinated Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Partnership’s Registration Statement on Form 8-A (File No. 001-31239) (the “Form 8-A”)).

(b)           Other than MarkWest’s Long-Term Investment Plan and MarkWest’s other equity compensation plans, as described in MarkWest’s Annual Report on Form 10-K, as amended, prior to the Commitment Date, for the period ended December 31, 2003, MarkWest has no equity compensation plans that contemplate the issuance of Common Units (or securities convertible into or exchangeable for Common Units).  No indebtedness having the right to vote (or convertible into or exchangeable for securities having the right to vote) on any matters on which MarkWest unitholders may vote are issued or outstanding.  Except as set forth in the first sentence of this Section 3.02(b) or as are contained in the Partnership Agreement, there are no outstanding or authorized (i) options, warrants, preemptive rights, subscriptions, calls, or other rights, convertible securities, agreements, claims or commitments of any character obligating MarkWest or any of its Subsidiaries to issue, transfer or sell any partnership interests or other equity interest in, MarkWest or any of its Subsidiaries or securities convertible into or exchangeable for such partnership interests or equity interests, (ii) obligations of

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MarkWest or any of its Subsidiaries to repurchase, redeem or otherwise acquire any partnership interests or equity interests of MarkWest or any of its Subsidiaries or any such securities or agreements listed in clause (i) of this sentence or (iii) voting trusts or similar agreements to which MarkWest or any of its Subsidiaries is a party with respect to the voting of the equity interests of MarkWest or any of its Subsidiaries.  At the Closing, except as described in this Section 3.02(b), there will not be any outstanding subscriptions, options, warrants, calls, preemptive rights, subscriptions, or other rights, convertible or exchangeable securities, agreements, claims or commitments of any character by which MarkWest or any of its Subsidiaries will be bound calling for the purchase or issuance of any partnership interests of MarkWest or any equity interest of any of its Subsidiaries or securities convertible into or exchangeable for such partnership or equity interests or any other such securities or agreements

(c)           (i) All of the issued and outstanding equity interests of each of MarkWest’s Subsidiaries are owned, directly or indirectly, by MarkWest free and clear of any Liens (except for such restrictions as may exist under applicable Law and except for such Liens as may be imposed under MarkWest’s or MarkWest’s Subsidiaries’ credit facilities), and all such ownership interests have been duly authorized, validly issued and are fully paid (to the extent required in the organizational documents of MarkWest’s Subsidiaries, as applicable) and non-assessable (except as nonassessability may be affected by Section 6.07 of the Texas Revised Uniform Limited Partnership Act, Section 18-607 of the Delaware Limited Liability Company Act, Section 17-607 of the Delaware Revised Uniform Limited Partnership Act, Section 450.4307 of the Michigan Limited Liability Company Act, Section 2030 of the Oklahoma Limited Liability Company Act or the organizational documents of MarkWest’s Subsidiaries, as applicable) and free of preemptive rights, with no personal liability attaching to the ownership thereof, and (ii) as of the Commitment Date, neither MarkWest nor any of its Subsidiaries owns any shares of capital stock or other securities of, or interest in, any other Person, or is obligated to make any capital contribution to or other investment in any other Person.  The material Subsidiaries of MarkWest are set forth on Schedule 2.03 hereto.

(d)           The Common Units being purchased by the Purchasers hereunder and the limited partner interests represented thereby, will be duly authorized by the Partnership Agreement (as amended as contemplated by this Agreement) prior to the Closing and, when issued and delivered to the Purchasers against payment therefor in accordance with the terms of this Agreement, will be validly issued, fully paid (to the extent required by the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described under the caption “The Partnership Agreement—Limited Liability” in MarkWest’s registration statement on Form S-1 (No. 333-81780) which is incorporated by reference into the Form 8-A) and will be free of any and all Liens and restrictions on transfer, other than restrictions on transfer under the Partnership Agreement and under applicable state and federal securities laws and other than such Liens as are created by the Purchaser.

(e)           The Common Units are listed on the American Stock Exchange.

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(f)            Correct and complete copies of the Partnership Agreement and MarkWest’s certificate of limited partnership are attached hereto as Exhibit B.

Section 3.03           MarkWest SEC Documents.  Except for the Current Report on Form 8-K/A filed on August 26, 2003, MarkWest has timely filed with the Commission all forms, registration statements, reports, schedules and statements required to be filed by it under the Exchange Act or the Securities Act (all such documents, collectively “MarkWest SEC Documents”).  The MarkWest SEC Documents, including, without limitation, any audited or unaudited financial statements and any notes thereto or schedules included therein (the “MarkWest Financial Statements”), at the time filed (in the case of registration statements, solely on the dates of effectiveness) (except to the extent corrected by a subsequently filed MarkWest SEC Document filed prior to the Commitment Date) (a) did not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading, (b) complied in all material respects with the applicable requirements of the Exchange Act and the Securities Act, as the case may be, (c) complied as to form in all material respects with applicable accounting requirements and with the published rules and regulations of the Commission with respect thereto, (d) were prepared in accordance with GAAP applied on a consistent basis during the periods involved (except as may be indicated in the notes thereto or, in the case of unaudited statements, as permitted by Form 10-Q of the Commission), and (e) fairly present (subject in the case of unaudited statements to normal, recurring and year-end audit adjustments) in all material respects the consolidated financial position and status of the business of MarkWest as of the dates thereof and the consolidated results of its operations and cash flows for the periods then ended.  PricewaterhouseCoopers LLP, MarkWest’s former public accounting firm, is an independent public accounting firm with respect to MarkWest and did not resign and was not dismissed as independent public accountants of MarkWest as a result of or in connection with any disagreement with MarkWest on a matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure.  KPMG LLP, MarkWest’s current public accounting firm, is an independent public accounting firm with respect to MarkWest and has not resigned or been dismissed as independent public accountants of MarkWest as a result of or in connection with any disagreement with MarkWest on a matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure.  To MarkWest’s Knowledge, the information (considering all information in the aggregate and excluding all forecasts, projections and forward looking information) provided by MarkWest to the Purchasers regarding the American Central Acquisition was true and correct in all material respects and did not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading.  Based on advice from the staff of the Commission and related information, MarkWest believes that it is currently eligible to use a registration statement on Form S-3 for the registration of securities under the Securities Act.

Section 3.04           No Material Adverse Change.  Except as set forth in or contemplated by the MarkWest SEC Documents filed with the Commission on or prior to

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the Commitment Date and except for the earnest money deposit paid to the sellers as contemplated by the American Central PSA and all other matters related to the proposed American Central Acquisition which have been discussed with each of the Purchasers, since December 31, 2003, MarkWest and its Subsidiaries have conducted their respective businesses in the ordinary course, consistent with past practice, and there has been no (a) change, event, occurrence, effect, fact, circumstance or condition that has had or would be reasonably likely to have a MarkWest Material Adverse Effect, other than those occurring as a result of general economic or financial conditions or other developments that are not unique to MarkWest and its Subsidiaries but also affect other Persons who participate or are engaged in the lines of business of which MarkWest and its Subsidiaries participate or are engaged, except, in each case, to the extent such change, event, occurrence, effect, fact, circumstance or condition affects MarkWest to a significantly greater extent than other similarly situated companies generally, (b) acquisition or disposition of any material asset by MarkWest or any of its Subsidiaries or any contract or arrangement therefor, otherwise than for fair value in the ordinary course of business or as disclosed in the MarkWest SEC Documents filed with the Commission on or prior to the Commitment Date, or (c) material change in MarkWest’s accounting principles, practices or methods.  Except as set forth in or contemplated by the MarkWest SEC Documents filed with the Commission on or prior to the Commitment Date and except for the earnest money deposit paid to the sellers as contemplated by the American Central PSA and the proposed credit arrangements substantially as contemplated by the commitment letter referenced in Section 2.04(b)(iv), MarkWest has neither issued Partnership Securities (other than under its Long-Term Investment Plan and its other equity compensation plans, each as described in the MarkWest SEC Documents filed with the Commission on or prior to the Commitment Date) nor incurred material indebtedness since March 31, 2004.

Section 3.05           Litigation.  Except as set forth in the MarkWest SEC Documents filed with the Commission on or prior to the Commitment Date, there is no Action pending or, to the knowledge of MarkWest, contemplated or threatened against or affecting MarkWest, any of its Subsidiaries or any of their respective officers, directors, properties or assets, which (individually or in the aggregate) (a) questions the validity of this Agreement or the Registration Rights Agreement or the right of MarkWest to enter into this Agreement or the Registration Rights Agreement or to consummate the transactions contemplated hereby and thereby or (b) would be reasonably likely to result in a MarkWest Material Adverse Effect.

Section 3.06           No Breach.  The execution, delivery and performance by MarkWest of this Agreement, the Registration Rights Agreement, the American Central PSA and all other agreements and instruments to be executed and delivered by MarkWest pursuant hereto or thereto or in connection with the transactions contemplated by this Agreement, the Registration Rights Agreement, the American Central PSA or any such other agreements and instruments, and compliance by MarkWest with the terms and provisions hereof and thereof and the issuance and sale by MarkWest of the Purchased Units, do not and will not (a) violate any provision of any Law or Permit having applicability to MarkWest or any of its Subsidiaries or any of their respective Properties, (b) conflict with or result in a violation of any provision of the Certificate of Limited

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Partnership or other organizational documents of MarkWest, or the Partnership Agreement, or any organizational documents of any of MarkWest’s Subsidiaries, (c) require any consent, approval or notice under or result in a violation or breach of or constitute (with or without due notice or lapse of time or both) a default (or give rise to any right of termination, cancellation or acceleration) under any contract, agreement, instrument, obligation, note, bond, mortgage, license, loan or credit agreement to which MarkWest or any of its Subsidiaries is a party or by which MarkWest or any of its Subsidiaries or any of their respective Properties may be bound, or (d) result in or require the creation or imposition of any Lien upon or with respect to any of the Properties now owned or hereafter acquired by MarkWest or any of its Subsidiaries; with the exception of the conflicts stated in clause (b) of this Section 3.06, except where such conflict, violation, default, breach, termination, cancellation, failure to receive consent or approval, or acceleration with respect to the foregoing provisions of this Section 3.06 would not be, individually or in the aggregate, reasonably likely to have a MarkWest Material Adverse Effect.

Section 3.07           Authority.  MarkWest has all necessary power and authority to execute, deliver and perform its obligations under the Basic Documents and the American Central PSA; and the execution, delivery and performance by MarkWest of the Basic Documents and the American Central PSA have been duly authorized by all necessary action on its part; and the Basic Documents and the American Central PSA constitute the legal, valid and binding obligations of MarkWest, enforceable in accordance with their terms, except as such enforceability may be limited by bankruptcy, insolvency, fraudulent transfer and similar laws affecting creditors’ rights generally or by general principles of equity. No approval from the holders of the Common Units is required in connection with MarkWest’s issuance and sale of the Purchased Units to the Purchasers.

Section 3.08           Approvals.  Except for the approvals required by the Commission in connection with MarkWest’s obligations under the Registration Rights Agreement, no authorization, consent, approval, waiver, license, qualification or written exemption from, nor any filing, declaration, qualification or registration with, any Governmental Authority or any other Person is required in connection with the execution, delivery or performance by MarkWest of any of the Basic Documents and the American Central PSA, except where the failure to receive such authorization, consent, approval, waiver, license, qualification or written exemption from, or to make such filing, declaration, qualification or registration would not, individually or in the aggregate, be reasonably likely to have a MarkWest Material Adverse Effect.

Section 3.09           MLP Status.  MarkWest has, for each taxable year beginning after December 31, 2002, during which MarkWest was in existence, met the gross income requirements of Section 7704(c)(2) of the Internal Revenue Code of 1986, as amended.

Section 3.10           Offering.  Assuming the accuracy of the representations and warranties of the Purchasers contained in this Agreement, the sale and issuance of the Purchased Units to each of the Purchasers pursuant to this Agreement is exempt from the

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registration requirements of the Securities Act, and neither MarkWest nor any authorized agent acting on its behalf has taken or will take any action hereafter that would cause the loss of such exemptions.

Section 3.11           Investment Company Status.  MarkWest is not an “investment company” within the meaning of the Investment Company Act of 1940, as amended.

Section 3.12           Certain Fees.  Except for the Commitment Fees to be payable to each of the Purchasers pursuant to Section 2.06(a) and the expense reimbursement contemplated by Section 5.12, no fees or commissions will be payable by MarkWest to brokers, finders, or investment bankers with respect to the sale of any of the Purchased Units or the consummation of the transaction contemplated by this Agreement.  MarkWest agrees that it will indemnify and hold harmless each of the Purchasers from and against any and all claims, demands, or liabilities for broker’s, finder’s, placement, or other similar fees or commissions incurred by MarkWest or alleged to have been incurred by MarkWest in connection with the sale of each Purchaser’s Purchased Units or the consummation of the transactions contemplated by this Agreement.

Section 3.13           No Side Agreements.  There are no other agreements by, among or between MarkWest or its Affiliates, on the one hand, and any of the Purchasers or their Affiliates, on the other hand, with respect to the transactions contemplated hereby nor promises or inducements for future transactions between or among any of such parties. 

Section 3.14           Material Agreements.  MarkWest has provided the Purchasers with correct and complete copies of all material agreements (as defined in Section 601(b)(10) of Regulation S-K promulgated by the Commission), including amendments to or other modifications of pre-existing material agreements, entered into by MarkWest since March 31, 2004.

Section 3.15           Accretive Acquisition.  MarkWest GP has determined, in good faith, that the American Central Acquisition is an “Acquisition” (as defined in the Partnership Agreement) that satisfies the requirements of Section 5.7(b) of the Partnership Agreement and thus allows the issuance of the Purchased Units without the prior approval of the MarkWest unitholders.

ARTICLE IV.
REPRESENTATIONS AND WARRANTIES OF EACH PURCHASER

Each Purchaser, severally and not jointly, represents and warrants to MarkWest with respect to itself:

Section 4.01           Investment.  The Purchased Units are being acquired for its own account, not as a nominee or agent, and with no intention of distributing the Purchased Units or any part thereof, and that such Purchaser has no present intention of selling or granting any participation in or otherwise distributing the same in any transaction in violation of the securities laws of the United States of America or any

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State, without prejudice, however, to such Purchaser’s right at all times to sell or otherwise dispose of all or any part of the Purchased Units under a registration statement under the Securities Act and applicable state securities laws or under an exemption from such registration available thereunder (including, without limitation, if available, Rule 144 promulgated thereunder). If such Purchaser should in the future decide to dispose of any of the Purchased Units, such Purchaser understands and agrees (a) that it may do so only (i) in compliance with the Securities Act and applicable state securities law, as then in effect, or (ii) in the manner contemplated by any registration statement pursuant to which such securities are being offered, and (b) that stop-transfer instructions to that effect will be in effect with respect to such securities.

Section 4.02           Nature of Purchaser.  Such Purchaser represents and warrants to, and covenants and agrees with, MarkWest that, (a) it is an “accredited investor” within the meaning of Rule 501 of Regulation D promulgated by the Securities and Exchange Commission pursuant to the Securities Act and (b) by reason of its business and financial experience it has such knowledge, sophistication and experience in making similar investments and in business and financial matters generally so as to be capable of evaluating the merits and risks of the prospective investment in the Purchased Units, is able to bear the economic risk of such investment and, at the present time, would be able to afford a complete loss of such investment.

Section 4.03           Receipt of Information; Authorization.  Such Purchaser acknowledges that it has (a) had access to MarkWest’s periodic filings with the Commission, including MarkWest’s Annual Report on Form 10-K, as amended, by the Form 10-K/A filed with the Commission on April 6, 2004, for the year ended December 31, 2003, MarkWest’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2004 and all Current Reports on Form 8-K filed with the Commission by MarkWest since January 1, 2004, (b) had access to information regarding the proposed American Central Acquisition and its potential effect on MarkWest’s operations and financial results and the risks related thereto and (c) been provided a reasonable opportunity to ask questions of and receive answers from Representatives of MarkWest regarding such matters.

Section 4.04           Corporate Existence.  Such Purchaser, if an entity: (a) is duly incorporated or formed, legally existing and in good standing under the laws of its respective jurisdiction of incorporation or formation; and (b) has all requisite power and authority, and has all governmental licenses, authorizations, consents and approvals necessary, to own, lease, use and operate its Properties and carry on its business as its business is now being conducted, except where the failure to obtain such licenses, authorizations, consents and approvals would not have or would not reasonably be expected to have a Purchaser Material Adverse Effect. Each such Purchaser is not in default in the performance, observance or fulfillment of any provision of its organizational documents, except where such default would not have or would not be reasonably likely to have a Purchaser Material Adverse Effect.

Section 4.05           No Breach.  The execution, delivery and performance by such Purchaser of this Agreement, the Registration Rights Agreement and all other agreements and instruments to be executed and delivered by such Purchaser pursuant

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hereto or thereto or in connection with the transactions contemplated by this Agreement, the Registration Rights Agreement or any such other agreements and instruments, and compliance by such Purchaser with the terms and provisions hereof and thereof, and the purchase of such Purchaser’s Purchased Units by such Purchaser do not and will not (a) violate any provision of any Law or permit having applicability to such Purchaser or any of its Properties, (b) conflict with or result in a violation of any provision of the organizational documents of such Purchaser, (c) require any consent, approval or notice under or result in a violation or breach of or constitute (with or without due notice or lapse of time or both) a default (or give rise to any right of termination, cancellation or acceleration) under any contract, agreement, instrument, obligation, note, bond, mortgage, license, loan or credit agreement to which such Purchaser is a party or by which such Purchaser or any of its Properties may be bound, or (d) result in or require the creation or imposition of any Lien upon or with respect to any of the Properties now owned or hereafter acquired by such Purchaser; with the exception of the conflicts stated in clause (b) of this Section 4.05, except where such conflict, violation, default, breach, termination, cancellation, failure to receive consent or approval, or acceleration with respect to the foregoing provisions of this Section 4.05 would not, individually or in the aggregate, be reasonably likely to have a Purchaser Material Adverse Effect.

Section 4.06           Restricted Securities.  Such Purchaser understands that the Purchased Units it is purchasing are characterized as “restricted securities” under the federal securities laws inasmuch as they are being acquired from MarkWest in a transaction not involving a public offering and that under such laws and applicable regulations such securities may be resold without registration under the Securities Act only in certain limited circumstances. In this connection, Purchaser represents that it is knowledgeable with respect to Rule 144 of the Commission promulgated under the Securities Act.

Section 4.07           Certain Fees.  Other than the fees payable by Tortoise to Lehman Brothers Inc. and the fees payable by Energy Income to A.G. Edwards & Sons, Inc., no fees or commissions will be payable by such Purchaser to brokers, finders, or investment bankers with respect to the purchase of any of the Purchased Units or the consummation of the transaction contemplated by this Agreement.  Such Purchaser agrees that it will indemnify and hold harmless MarkWest from and against any and all claims, demands, or liabilities for broker’s, finder’s, placement, or other similar fees or commissions incurred by such Purchaser or alleged to have been incurred by such Purchaser in connection with the purchase of such Purchaser’s Purchased Units or the consummation of the transactions contemplated by this Agreement.

Section 4.08           Legend.  It is understood that the certificates evidencing the Purchased Units may bear the following legend:  “These securities have not been registered under the Securities Act of 1933, as amended.  They may not be sold, offered for sale, pledged or hypothecated in the absence of a registration statement in effect with respect to the securities under such Act or an opinion of counsel satisfactory to the Company that such registration is not required or unless sold pursuant to Rule 144 of such Act.”

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Section 4.09           No Side Agreements.  There are no other agreements by, among or between such Purchaser and any of its Affiliates, on the one hand, and any of the other Purchasers or their Affiliates, on the other hand, with respect to the transactions contemplated hereby nor promises or inducements for future transactions between or among any of such parties.

ARTICLE V.
MISCELLANEOUS

Section 5.01           Interpretation and Survival of Provisions.  Article, Section, Schedule, and Exhibit references are to this Agreement, unless otherwise specified.  All references to instruments, documents, contracts, and agreements are references to such instruments, documents, contracts, and agreements as the same may be amended, supplemented, and otherwise modified from time to time, unless otherwise specified.  All references to a party in this Agreement shall include such party’s successors and permitted assigns.  The word “including” shall mean “including but not limited to.”  The terms “will” and “shall” shall be interpreted to have the same meaning.  Words in the singular form will be construed to include the plural and vice versa, unless the context otherwise requires.  The section headings contained in this Agreement are inserted for convenience only and will not affect in any way the meaning or interpretation of this Agreement.  Whenever MarkWest has an obligation under the Basic Documents, the expense of complying with that obligation shall be an expense of MarkWest unless otherwise specified. Whenever any determination, consent, or approval is to be made or given by a Purchaser, such action shall be in such Purchaser’s sole discretion unless otherwise specified in this Agreement.  If any provision in the Basic Documents is held to be illegal, invalid, not binding, or unenforceable, such provision shall be fully severable and the Basic Documents shall be construed and enforced as if such illegal, invalid, not binding, or unenforceable provision had never comprised a part of the Basic Documents, and the remaining provisions shall remain in full force and effect.  The Basic Documents have been reviewed and negotiated by sophisticated parties with access to legal counsel and shall not be construed against the drafter.  The representations and warranties set forth in Sections 3.01, 3.02, 3.06, 3.07, 3.08, 3.12, 3.13, 4.01, 4.02, 4.03, 4.04, 4.05, 4.06, 4.07 and 4.09 hereunder shall survive the execution and delivery of this Agreement indefinitely, and the other representations and warranties set forth herein shall survive for a period of twelve (12) months following the Closing Date regardless of any investigation made by or on behalf of MarkWest or each of the Purchasers.  The covenants made in this Agreement or any other Basic Document shall survive the Closing of the transactions described herein and remain operative and in full force and effect regardless of acceptance of any of the Purchased Units and payment therefor and repayment or repurchase thereof.  All indemnification obligations of MarkWest and the provisions of Section 5.02 shall remain operative and in full force and effect unless such obligations are expressly terminated in a writing referencing that individual Section, regardless of any purported general termination of this Agreement.

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Section 5.02           Indemnification, Costs and Expenses.

(a)           Indemnification by MarkWest.  MarkWest agrees to indemnify each Purchaser and its officers, directors, employees and agents (collectively, the “Purchaser Related Parties”) from, and hold each of them harmless against any and all actions, suits, proceedings (including any investigations, litigation or inquiries), demands, and causes of action, and, in connection therewith, and promptly upon demand, pay or reimburse each of them for all reasonable costs, losses, liabilities, damages, or expenses of any kind or nature whatsoever, including, without limitation, the reasonable fees and disbursements of counsel and all other reasonable expenses incurred in connection with investigating, defending or preparing to defend any such matter that may be incurred by them or asserted against or involve any of them as a result of, arising out of, or in any way related to (i) any actual or proposed use by MarkWest of the proceeds of any sale of the Purchased Units or (ii) the breach of any of the representations, warranties or covenants of MarkWest contained herein, provided such claim for indemnification relating to a breach of a representation or warranty is made prior to the expiration of such representation or warranty.

(b)           Indemnification by Purchasers.  Each Purchaser agrees, severally and not jointly, to indemnify MarkWest, MarkWest GP and their officers, directors, employees and agents (collectively, the “MarkWest Related Parties”) from, and hold each of them harmless against any and all actions, suits, proceedings (including any investigations, litigation, or inquiries), demands, and causes of action, and, in connection therewith, and promptly upon demand, pay or reimburse each of them for all reasonable costs, losses, liabilities, damages, or expenses of any kind or nature whatsoever, including, without limitation, the reasonable fees and disbursements of counsel and all other reasonable expenses incurred in connection with investigating, defending or preparing to defend any such matter that may be incurred by them or asserted against or involve any of them as a result of, arising out of, or in any way related to the breach of any of the representations, warranties or covenants of such Purchaser contained herein, provided such claim for indemnification relating to a breach of the representations and warranties is made prior to the expiration of such representations and warranties.

(c)           Indemnification Procedure.  Promptly after any MarkWest Related Party or Purchaser Related Party (hereinafter, the “Indemnified Party”) has received notice of any indemnifiable claim hereunder, or the commencement of any action or proceeding by a third person, which the Indemnified Party believes in good faith is an indemnifiable claim under this Agreement, the Indemnified Party shall give the indemnitor hereunder (the “Indemnifying Party”) written notice of such claim or the commencement of such action or proceeding, but failure to so notify the Indemnifying Party will not relieve the Indemnifying Party from any liability it may have to such Indemnified Party hereunder except to the extent that the Indemnifying Party is materially prejudiced by such failure. Such notice shall state the nature and the basis of such claim to the extent then known.  The Indemnifying Party shall have the right to defend and settle, at its own expense and by its own counsel, any such matter as long as the Indemnifying Party pursues the same diligently and in good faith. If the Indemnifying Party undertakes to defend or settle, it shall promptly notify the Indemnified Party of its

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intention to do so, and the Indemnified Party shall cooperate with the Indemnifying Party and its counsel in all commercially reasonable respects in the defense thereof and the settlement thereof. Such cooperation shall include, but shall not be limited to, furnishing the Indemnifying Party with any books, records and other information reasonably requested by the Indemnifying Party and in the Indemnified Party’s possession or control.  Such cooperation of the Indemnified Party shall be at the cost of the Indemnifying Party.  After the Indemnifying Party has notified the Indemnified Party of its intention to undertake to defend or settle any such asserted liability, and for so long as the Indemnifying Party diligently pursues such defense, the Indemnifying Party shall not be liable for any additional legal expenses incurred by the Indemnified Party in connection with any defense or settlement of such asserted liability; provided, however, that the Indemnified Party shall be entitled (i) at its expense, to participate in the defense of such asserted liability and the negotiations of the settlement thereof and (ii) if (A) the Indemnifying Party has failed to assume the defense and employ counsel or (B) if the defendants in any such action include both the Indemnified Party and the Indemnifying Party and counsel to the Indemnified Party shall have concluded that there may be reasonable defenses available to the Indemnified Party that are different from or in addition to those available to the Indemnifying Party or if the interests of the Indemnified Party reasonably may be deemed to conflict with the interests of the Indemnifying Party, then the Indemnified Party shall have the right to select a separate counsel and to assume such legal defense and otherwise to participate in the defense of such action, with the expenses and fees of such separate counsel and other expenses related to such participation to be reimbursed by the Indemnifying Party as incurred.  Notwithstanding any other provision of this Agreement, the Indemnifying Party shall not settle any indemnified claim without the consent of the Indemnified Party, unless the settlement thereof imposes no liability or obligation on, and includes a complete release from liability of, the Indemnified Party.

Section 5.03           No Waiver; Modifications in Writing.

(a)           Delay.  No failure or delay on the part of any party in exercising any right, power, or remedy hereunder shall operate as a waiver thereof, nor shall any single or partial exercise of any such right, power, or remedy preclude any other or further exercise thereof or the exercise of any right, power, or remedy. The remedies provided for herein are cumulative and are not exclusive of any remedies that may be available to a party at law or in equity or otherwise.

(b)           Specific Waiver.  Except as otherwise provided herein, no amendment, waiver, consent, modification, or termination of any provision of this Agreement or any other Basic Document shall be effective unless signed by each of the parties hereto or thereto affected by such amendment, waiver, consent, modification, or termination.  Any amendment, supplement or modification of or to any provision of this Agreement or any other Basic Document, any waiver of any provision of this Agreement or any other Basic Document, and any consent to any departure by MarkWest from the terms of any provision of this Agreement or any other Basic Document shall be effective only in the specific instance and for the specific purpose for which made or given. Except where notice is specifically required by this Agreement, no notice to or demand on

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MarkWest in any case shall entitle MarkWest to any other or further notice or demand in similar or other circumstances.

Section 5.04           Binding Effect; Assignment.

(a)           Binding Effect.  This Agreement shall be binding upon MarkWest, each Purchaser, and their respective successors and permitted assigns. Except as expressly provided in this Agreement, this Agreement shall not be construed so as to confer any right or benefit upon any Person other than the parties to this Agreement, and their respective successors and permitted assigns.

(b)           Assignment of Purchased Units.  All or any portion a Purchaser’s Purchased Units purchased pursuant to this Agreement may be sold, assigned or pledged by such Purchaser, subject to compliance with applicable securities laws.

(c)           Assignment of Rights.  All or any portion of the rights and obligations of each Purchaser under this Agreement may not be transferred by such Purchaser without the written consent of MarkWest, unless such transfer is to an Affiliate of the Purchaser in which case written consent shall not be unreasonably withheld.

Section 5.05           Confidentiality.  Notwithstanding anything herein to the contrary, each Purchaser has executed a confidentiality agreement in favor of MarkWest and shall continue to remain bound by such confidentiality agreement.  Disclosure of Confidential Information will not be deemed to be a breach of this Section 5.05 if such disclosure is made with the consent of MarkWest or pursuant to a subpoena or order issued by a court of competent jurisdiction or by a judicial or administrative or legislative body or committee; provided, however, that upon receipt by a Purchaser of any subpoena or order covering Confidential Information of MarkWest, such Purchaser will promptly notify MarkWest of such subpoena or order.

Section 5.06           Communications.  All notices and demands provided for hereunder shall be in writing and shall be given by registered or certified mail, return receipt requested, telecopy, air courier guaranteeing overnight delivery or personal delivery to the following addresses:

(a)           If to Kayne Anderson:

1800 Avenue of the Stars, 2nd Floor

Los Angeles, California 90067

Attention: David Shladovsky, General Counsel

Facsimile: (310) 284-6444

and to:

1100 Louisiana St # 4550

Houston, TX 77002

Attention: Chuck Yates

Facsimile: (713) 655-7355

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with a copy (which shall not constitute notice) to:

Akin Gump Strauss Hauer & Feld LLP

1100 Louisiana Street, 44^th Floor

Houston, TX 77002

Attention: J. Vincent Kendrick

Facsimile: (713) 236-0822

(b)           If to Tortoise:

Tortoise Energy Infrastructure Corporation

10801 Mastin Blvd, Suite 222

Overland Park, KS 66210

Attention: David Schulte

Facsimile: (913) 345 2763

with a copy (which shall not constitute notice) to:

Blackwell Sanders Peper Martin, LLP

2300 Main Street, Suite 1000

Kansas City, MO 64108

Attention: Steven F. Carman

Facsimile: (816) 983-8080

(c)           If to Energy Income:

Fiduciary Asset Management

8112 Maryland, Suite 400

St. Louis, Missouri 63105

Attention: James J. Cunnane, Jr.

Facsimile: (314) 863-4360

with a copy (which shall not constitute notice) to:

Jenner & Block LLP

1 IBM Plaza

Chicago, Illinois 60611

Attention: Michael T. Wolf

Facsimile: (312) 840-7306

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(d)           If to MarkWest:

MarkWest Energy Partners, L.P.

155 Inverness Drive West, Suite 200

Englewood, CO 80112

Attention: Andrew L. Schroeder

Facsimile: (303) 290-8769

with a copy (which shall not constitute notice) to:

Vinson & Elkins L.L.P.

2300 First City Tower

1001 Fannin Street

Houston, Texas 77002

Attention: David P. Oelman, Esq.

Facsimile: (713) 615-5861

or to such other address as MarkWest or such Purchaser may designate in writing. All notices and communications shall be deemed to have been duly given at the time delivered by hand, if personally delivered; upon actual receipt if sent by certified mail, return receipt requested, or regular mail, if mailed; when receipt acknowledged, if sent via facsimile; and upon actual receipt when delivered to an air courier guaranteeing overnight delivery.

Section 5.07           Removal of Legend.  Any Purchaser may request MarkWest to remove the legend described in Section 4.08 from the certificates evidencing the Purchased Units by submitting to MarkWest such certificates, together with an opinion of counsel to the effect that such legend is no longer required under the Securities Act or applicable state laws, as the case may be.

Section 5.08           Entire Agreement.  This Agreement, the other Basic Documents and the other agreements and documents referred to herein are intended by the parties as a final expression of their agreement and intended to be a complete and exclusive statement of the agreement and understanding of the parties hereto in respect of the subject matter contained herein and therein. There are no restrictions, promises, warranties or undertakings, other than those set forth or referred to herein or therein with respect to the rights granted by MarkWest or any of its Affiliates or each of the Purchasers or any of their Affiliates set forth herein or therein.  This Agreement, the other Basic Documents and the other agreements and documents referred to herein supersede all prior agreements and understandings between the parties with respect to such subject matter.

Section 5.09           Governing Law.  This Agreement will be construed in accordance with and governed by the laws of the State of Delaware without regard to principles of conflicts of laws.

Section 5.10           Execution in Counterparts.  This Agreement may be executed in any number of counterparts and by different parties hereto in separate

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counterparts, each of which counterparts, when so executed and delivered, shall be deemed to be an original and all of which counterparts, taken together, shall constitute but one and the same Agreement.

Section 5.11           Termination.

(a)           Notwithstanding anything herein to the contrary, this Agreement shall automatically terminate if the Closing shall not have occurred on or before October 31, 2004, unless the term hereof is extended by agreement of the parties hereto (such date or any extension of such date, the “Termination Date”).

(b)           In the event of the termination of this Agreement as provided in Section 5.11(a), this Agreement shall forthwith become null and void.  In the event of such termination, there shall be no liability on the part of any party hereto, except as set forth in Section 5.02 of this Agreement and except with respect to the requirement to comply with any confidentiality agreement in favor of MarkWest; provided that nothing herein shall relieve any party from any liability or obligation with respect to any willful breach of this Agreement.

Section 5.12           Expenses.  MarkWest hereby covenants and agrees to reimburse Kayne Anderson, Tortoise and Energy Income for reasonable and documented costs and expenses incurred in connection with the negotiation, execution, delivery and performance of the Basic Documents and the transactions contemplated hereby and thereby (including, without limitation, reasonable legal, consulting and due diligence fees and expenses), provided that such expenses do not exceed $35,000 with respect to each of Kayne Anderson and Tortoise and $15,000 with respect to Energy Income and that any request for such expense reimbursement by Kayne Anderson, Tortoise or Energy Income be accompanied by a detailed invoice for such amount.  If any action at law or equity is necessary to enforce or interpret the terms of the Basic Documents, the prevailing party shall be entitled to reasonable attorney’s fees, costs and necessary disbursements in addition to any other relief to which such party may be entitled.

Section 5.13           Other Matters.  In the event MarkWest enters into any material amendment of, or waives any material condition to closing under the American Central PSA, no Purchaser shall be obligated to fulfill its Commitment.  Other than the obligation of MarkWest GP to make contributions to MarkWest as required by Section 5.2 of the Partnership Agreement, MarkWest GP hereby waives (for itself and on behalf of its Affiliates) its preemptive rights provided under Section 5.9 of the Partnership Agreement with respect to the issuances of Partnership Securities pursuant to this Agreement.

[The remainder of this page is intentionally left blank.]

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IN WITNESS WHEREOF, the parties hereto execute this Agreement, effective as of the date first above written.

MARKWEST ENERGY PARTNERS, LP.
By:	MarkWest Energy GP, L.L.C.,
	its general partner
By:	/s/ MarkWest Energy Partners, L.P.
Name:	MarkWest Energy Partners, L.P.
Title:
MARKWEST ENERGY GP, L.L.C. (solely for the purpose of Sections 3.15 and 5.13)
By:	/s/ MarkWest Energy GP, L.L.C.
Name:	MarkWest Energy GP, L.L.C.
Title:
KAYNE ANDERSON ENERGY FUND II, L.P.
By:	KAEFTX, L.P., its general partner
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Energy Fund II, L.P.
Name:	Kayne Anderson Energy Fund II, L.P.
Title:

KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Capital Income Partners (QP), L.P.
Name:	Kayne Anderson Capital Income Partners (QP), L.P.
Title:
KAYNE ANDERSON MLP FUND, L.P.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson MLP Fund, L.P.
Name:	Kayne Anderson MLP Fund, L.P.
Title:
KAYNE ANDERSON CAPITAL INCOME FUND, LTD.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Capital Income Fund, LTD.
Name:	Kayne Anderson Capital Income Fund, LTD.
Title:

KAYNE ANDERSON INCOME PARTNERS, L.P.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Income Partners, L.P.
Name:	Kayne Anderson Income Partners, L.P.
Title:
TORTOISE ENERGY INFRASTRUCTURE CORPORATION
By:	/s/ David J. Schulte
Name:	David J. Schulte
Title:	President
ENERGY INCOME AND GROWTH FUND
By:	/s/ Roger Testin
Name:	Roger Testin
Title:	Vice President

HFR RV PERFORMANCE MASTER TRUST
By:	HFR RV Performance Master Trust	, its trustee
By:	/s/ HFR RV Performance Master Trust
Name:	HFR RV Performance Master Trust
Title:

Exhibit A – Form of Registration Rights Agreement

See Attached

Exhibit B – Partnership Agreement and Certificate of Limited Partnership

See Attached

Exhibit C – Form of Opinion of MarkWest Counsel

See Attached

Schedule 2.01

Frank M. Semple

James G. Ivey

John C. Mollenkopf

Randy S. Nickerson

Andrew L. Schroeder

Schedule 2.02

Purchaser	Units Purchased	Total Purchase Price		Commitment Fee
Kayne Anderson Energy Fund II, L.P.	465,000	$	16,042,500	$	240,000
Kayne Anderson Capital Income Partners (QP), L.P.	17,000	$	586,500	$	9,000
Kayne Anderson MLP Fund, L.P.	72,000	$	2,484,000	$	37,500
Kayne Anderson Capital Income Fund, Ltd.	14,000	$	483,000	$	7,500
Kayne Anderson Income Partners, L.P.	6,000	$	207,000	$	3,000
HFR RV Performance Master Trust	5,800	$	200,100	$	3,000
Tortoise Energy Infrastructure Corporation	579,710	$	19,999,995	$	300,000
Energy Income and Growth Fund	144,928	$	5,000,016	$	75,000
Total	1,304,438	$	45,003,111	$	675,000

Schedule 2.03

MarkWest Texas GP, L.L.C.

MarkWest Energy Operating Company, L.L.C.

MarkWest Energy Appalachia, L.L.C.

Basin Pipeline, L.L.C.

MarkWest Michigan Pipeline Company, L.L.C.

MarkWest Western Oklahoma Gas Company, L.L.C.

EX-4.2

Exhibit 4.2

Execution Copy

REGISTRATION RIGHTS AGREEMENT

by and among

MARKWEST ENERGY PARTNERS, L.P.,

KAYNE ANDERSON ENERGY FUND II, L.P.,

KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P.,

KAYNE ANDERSON MLP FUND, L.P.,

KAYNE ANDERSON CAPITAL INCOME FUND, LTD.,

KAYNE ANDERSON INCOME PARTNERS, L.P.,

HFR RV PERFORMANCE MASTER TRUST,

TORTOISE ENERGY INFRASTRUCTURE CORPORATION

AND

ENERGY INCOME AND GROWTH FUND

REGISTRATION RIGHTS AGREEMENT

THIS REGISTRATION RIGHTS AGREEMENT (this “Agreement”) is made and entered into as of July     , 2004, by and among MARKWEST ENERGY PARTNERS, L.P. (“MarkWest”) and each of KAYNE ANDERSON ENERGY FUND II, L.P. (“KAEF”), KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P. (“KACIP”), KAYNE ANDERSON MLP FUND, L.P. (“KAMLP”), KAYNE ANDERSON CAPITAL INCOME FUND, LTD. (“KACIF”), KAYNE ANDERSON INCOME PARTNERS, L.P. (“KAIP”), HFR RV PERFORMANCE MASTER TRUST (“HFR”) (collectively, “Kayne Anderson”),TORTOISE ENERGY INFRASTRUCTURE CORPORATION (“Tortoise”) and ENERGY INCOME AND GROWTH FUND (“Energy Income”) (each of KAEF, KACIP, KAMLP, KACIF, KAIP, HFR, Tortoise and Energy Income a “Purchaser” and collectively, the “Purchasers”).  Capitalized terms used herein without definition shall have the meanings given to them in the Purchase Agreement.

This Agreement is made in connection with the Closing of the issuance and sale of the Purchased Units pursuant to the Unit Purchase Agreement, dated as of July 29, 2004, by and among MarkWest and the Purchasers (the “Purchase Agreement”).  MarkWest has agreed to provide the registration and other rights set forth in this Agreement for the benefit of the Purchasers pursuant to Section 2.05(d) of the Purchase Agreement. In consideration of the mutual covenants and agreements set forth herein and for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged by each party hereto, the parties hereby agree as follows:

ARTICLE I.

DEFINITIONS

Section 1.01           Definitions.  The terms set forth below are used herein as so defined:

“Affiliate” means, with respect to a specified Person, any other Person, directly or indirectly controlling, controlled by or under direct or indirect common control with such specified Person.  For purposes of this definition, “control” (including, with correlative meanings, “controlling”, “controlled by”, and “under common control with”) means the power to direct or cause the direction of the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise.

“Business Day” means any day other than a Saturday, Sunday, or a legal holiday for commercial banks in Wilmington, Delaware.

“Closing” shall have the meaning set forth in the Purchase Agreement.

“Commission” means the United States Securities and Exchange Commission.

“Common Units” means the common units of MarkWest.

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“Effectiveness Period” has the meaning specified therefor in Section 2.01(a) of this Agreement.

“Exchange Act” shall mean the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Commission promulgated thereunder.

“Holder” means the record holder of any Registrable Securities.

“Included Registrable Securities” has the meaning specified therefor in Section 2.02(a) of this Agreement.

“Losses” has the meaning specified therefor in Section 2.08(a) of this Agreement.

“Managing Underwriter” means, with respect to any Underwritten Offering, the book running lead manager of such Underwritten Offering.

“MarkWest Hydrocarbon” means MarkWest Hydrocarbon, Inc., a Delaware corporation.

“Person” means any individual, corporation, company, voluntary association, partnership, joint venture, trust, limited liability company, unincorporated organization, government or any agency, instrumentality or political subdivision thereof, or any other form of entity.

“Piggyback Registration” has the meaning specified therefor in Section 2.02(a) of this Agreement.

“Prior Holders” means Tortoise MWEP, L.P., a Kansas limited partnership, and each investor a party to the Registration Rights Agreement dated June 13, 2003 by and among MarkWest and each party listed on Schedule A thereto.

“Purchase Agreement” has the meaning specified therefor in the introductory paragraph of this Agreement.

“Purchased Units”  shall have the meaning set forth in the Purchase Agreement.

“Purchasers” has the meaning specified therefor in the introductory paragraph of this Agreement.

“Registrable Securities” means the Common Units comprising the Purchased Units until such time as such securities cease to be Registrable Securities pursuant to Section 1.02 hereof.

“Registration Expenses” has the meaning specified therefor in Section 2.07(a) of this Agreement.

“Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations of the Commission promulgated thereunder.

“Selling Expenses” has the meaning specified therefor in Section 2.07(a) of this Agreement.

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“Selling Holder” means a Holder who is selling Registrable Securities pursuant to a registration statement.

“Shelf Registration” has the meaning specified therefor in Section 2.01(a) of this Agreement.

“Shelf Registration Statement” has the meaning specified therefor in Section 2.01(a) of this Agreement.

“Underwritten Offering” means an offering (including an offering pursuant to a Shelf Registration Statement) in which Common Units are sold to an underwriter on a firm commitment basis for reoffering to the public or an offering that is a “bought deal” with one or more investment banks.

Section 1.02           Registrable Securities.  Any Registrable Security will cease to be a Registrable Security when (a) a registration statement covering such Registrable Security has been declared effective by the Commission and such Registrable Security has been sold or disposed of pursuant to such effective registration statement; (b) such Registrable Security has been disposed of pursuant to any section of Rule 144 (or any similar provision then in force under the Securities Act); or (c) such Registrable Security is held by MarkWest or one of its subsidiaries.  Except for the rights and obligations under Section 2.08 herein, all rights and obligations of each Purchaser under this Agreement, and all rights and obligations of MarkWest under this Agreement with respect to such Purchaser, shall terminate when such Purchaser is no longer a Holder

ARTICLE II.

REGISTRATION RIGHTS

Section 2.01           Shelf Registration.

(a) Shelf Registration.  As soon as practicable following the Closing of the purchase of the Purchased Units pursuant to the terms of the Purchase Agreement, but in any event within 120 days of the Closing, MarkWest shall prepare and file a registration statement under the Securities Act to permit the public resale of the Registrable Securities from time to time as permitted by Rule 415 of the Securities Act (the “Shelf Registration Statement”).  MarkWest shall use its commercially reasonable efforts to cause the Shelf Registration Statement to become effective no later than 180 days after the date of the Closing (the “Shelf Registration”).  A Shelf Registration Statement filed pursuant to this Section 2.01(a) shall be on such appropriate registration form of the Commission as shall be selected by MarkWest; provided, however, that if a prospectus supplement will be used in connection with the marketing of an Underwritten Offering from the Shelf Registration Statement and the Managing Underwriter at any time shall notify MarkWest in writing that, in the sole judgment of such Managing Underwriter, inclusion of detailed information to be used in such prospectus supplement is of material importance to the success of the Underwritten Offering of such Registrable Securities, MarkWest shall use its commercially reasonable efforts to include such information in the prospectus.  MarkWest will cause the Shelf Registration Statement filed

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pursuant to this Section 2.01(a) to be continuously effective, supplemented and amended to the extent necessary to assure that it is available for resale of all Registrable Securities by the Holders and that it conforms in all material respects with the requirements of the Securities Act during the entire period beginning on the date the Shelf Registration Statement first is declared effective under the Securities Act and ending on the earlier to occur of (i) the date all Registrable Securities covered by the Shelf Registration Statement have been distributed in the manner set forth and as contemplated in the Shelf Registration Statement and (ii) the date on which the Registrable Securities cease to be Registrable Securities hereunder in accordance with Section 1.02 (the “Effectiveness Period”).  The Shelf Registration Statement when declared effective (including the documents incorporated therein by reference) will comply as to form with all applicable requirements of the Securities Act and the Exchange Act and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading. 

(b) Delay Rights.  Notwithstanding anything to the contrary contained herein, MarkWest may, upon written notice to any Selling Holder whose Registrable Securities are included in the Shelf Registration Statement, suspend such Selling Holder’s use of any prospectus which is a part of the Shelf Registration Statement (in which event the Selling Holder shall discontinue sales of the Registrable Securities pursuant to the Shelf Registration Statement), for a period not to exceed an aggregate of 60 days in any 180-day period and not to exceed an aggregate of 90 days in any 365-day period, if (i) MarkWest is pursuing a material acquisition, merger, reorganization, disposition or other similar transaction and MarkWest determines in good faith that MarkWest’s ability to pursue or consummate such a transaction would be materially adversely affected by any required disclosure of such transaction in the Shelf Registration Statement or (ii) MarkWest has experienced some other material non-public event the disclosure of which at such time, in the good faith judgment of MarkWest, would materially adversely affect MarkWest.  Upon disclosure of such information or the termination of the condition described above, MarkWest shall provide prompt notice to the Selling Holders whose Registrable Securities are included in the Shelf Registration Statement, and shall promptly terminate any suspension of sales it has put into effect and shall take such other actions to permit registered sales of Registrable Securities as contemplated in this Agreement.

Section 2.02           Piggyback Registration.

(a) Participation.  If MarkWest, MarkWest Hydrocarbon or any subsidiary of MarkWest Hydrocarbon at any time proposes to (i) file a prospectus supplement to an effective shelf registration statement with respect to an Underwritten Offering of Common Units for its own account or (ii) register any Common Units for its own account for sale to the public in an Underwritten Offering other than, in the case of clause (ii), (a) a registration relating solely to employee benefit plans, (b) a registration relating solely to a Rule 145 transaction, or (c) a registration on any registration form which does not permit secondary sales or does not include substantially the same information as would be required to be included in a registration statement covering the sale of Registrable Securities, then, as soon as practicable following the engagement of counsel by MarkWest to prepare the documents to be used in connection with an Underwritten Offering, MarkWest shall give notice of such proposed Underwritten Offering to the Holders and such notice shall offer the Holders the opportunity to include in such Underwritten Offering such number of Registrable Securities as each such Holder may request in writing (a “Piggyback

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Registration”); provided, however, that MarkWest shall not be required to offer such opportunity to Holders to the extent MarkWest has been advised in writing by the Managing Underwriter that the inclusion of Registrable Securities for sale for the benefit of the Holders will have an adverse effect on the price, timing or distribution of the Common Units.  Each Holder of Registrable Securities acknowledges for purposes of clause (ii) that its Registrable Securities are not covered by MarkWest’s existing registration statement on Form S-3 (File No. 333-116680) and MarkWest shall have no obligation to include such Registrable Securities in such registration statement, by post-effective amendment or otherwise; provided, however, that if a registration statement covering the Registrable Securities is effective and a prospectus supplement relating to the Form S-3 (File No. 333-116680) described above has been proposed with respect to an Underwritten Offering, the Holders shall be entitled to notice and the opportunity to include in such Underwritten Offering, pursuant to the registration statement covering the Registrable Securities, such number of Registrable Securities as each such Holder may request in writing, subject to the other terms and conditions of this Section 2.02(a).  Subject to Section 2.02(b), MarkWest shall include in such Underwritten Offering all such Registrable Securities (“Included Registrable Securities”) with respect to which MarkWest has received requests within one Business Day after MarkWest’s notice has been delivered in accordance with Section 3.01.  If no request for inclusion from a Holder is received within the specified time, such Holder shall have no further right to participate in such Piggyback Registration.  If, at any time after giving written notice of its intention to undertake an Underwritten Offering and prior to the closing of such Underwritten Offering, MarkWest shall determine for any reason not to undertake or to delay such Underwritten Offering, MarkWest may, at its election, give written notice of such determination to the Selling Holders and, (i) in the case of a determination not to undertake such Underwritten Offering, shall be relieved of its obligation to sell any Included Registrable Securities in connection with such terminated Underwritten Offering, and (ii) in the case of a determination to delay such Underwritten Offering, shall be permitted to delay offering any Included Registrable Securities for the same period as the delay in the Underwritten Offering. Any Selling Holder shall have the right to withdraw such Selling Holder’s request for inclusion of such Selling Holder’s Registrable Securities in such offering by giving written notice to MarkWest of such withdrawal up to and including the time of pricing of such offering.

(b)           Priority of Piggyback Registration.   If the Managing Underwriter or Underwriters of any proposed Underwritten Offering of Common Units included in a Piggyback Registration advises MarkWest in writing that the total amount of Common Units which the Selling Holders and any other Persons intend to include in such offering exceeds the number which can be sold in such offering without being likely to have an adverse effect on the price, timing or distribution of the Common Units offered or the market for the Common Units, then the Common Units to be included in such Underwritten Offering shall include the number of Registrable Securities that such Managing Underwriter or Underwriters advises MarkWest can be sold without having such adverse effect, with such number to be allocated pro rata among the Selling Holders and Prior Holders who have requested participation in the Piggyback Registration (based, for each such Selling Holder or Prior Holder, as applicable, on the percentage derived by dividing (A) the number of Registrable Securities proposed to be sold by such Selling Holder or Prior Holder in such offering; by (B) the aggregate number of Common Units proposed to be sold by the Selling Holders and Prior Holders participating in the Piggyback Registration to be included in such offering).

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(c)           Termination of Piggyback Registration Rights.  The Piggyback Registration rights granted pursuant to this Section 2.02 shall be unlimited in number and shall terminate the later of (i) two years following the Closing Date under the Purchase Agreement and (ii) the date on which all Registrable Securities cease to be Registrable Securities hereunder in accordance with Section 1.02.

Section 2.03           Underwritten Offering.

(a) Shelf Registration.  In the event that one or more Selling Holders elect to dispose of Registrable Securities under the Shelf Registration Statement pursuant to an Underwritten Offering and such Selling Holders reasonably anticipate gross proceeds from such Underwritten Offering of at least $10 million, MarkWest shall enter into an underwriting agreement in customary form with the Managing Underwriter or Underwriters, which shall include, among other provisions, indemnities to the effect and to the extent provided in Section 2.08, and shall take all such other reasonable actions as are requested by the Managing Underwriter in order to expedite or facilitate the registration and disposition of the Registered Securities; provided, however, that MarkWest shall be required to cause appropriate officers of MarkWest or its Affiliates to participate in a “road show” or similar marketing effort being conducted by such underwriter with respect to such Underwritten Offering only if the Selling Holders reasonably anticipate gross proceeds from such Underwritten Offering of at least $20 million.

(b) General Procedures.  In connection with any Underwritten Offering under this Agreement (except for Underwritten Offerings pursuant to Section 2.03(a)), MarkWest shall be entitled to select the Managing Underwriter or Underwriters, each of which must be a nationally-recognized firm.  In the case of an Underwritten Offering pursuant to Section 2.03(a) hereof, the Selling Holders in such Underwritten Offering shall be entitled to select the Managing Underwriter or Underwriters, each of which must be a nationally recognized firm.  In connection with an Underwritten Offering under Section 2.01 or 2.02 hereof, each Selling Holder and MarkWest shall be obligated to enter into an underwriting agreement which contains such representations, covenants, indemnities and other rights and obligations as are customary in underwriting agreements for firm commitment offerings of securities.  No Selling Holder may participate in such Underwritten Offering unless such Selling Holder agrees to sell its Registrable Securities on the basis provided in such underwriting agreement and completes and executes all questionnaires, powers of attorney, indemnities and other documents reasonably required under the terms of such underwriting agreement.  Each Selling Holder may, at its option, require that any or all of the representations and warranties by, and the other agreements on the part of, MarkWest to and for the benefit of such underwriters also be made to and for such Selling Holder’s benefit and that any or all of the conditions precedent to the obligations of such underwriters under such underwriting agreement also be conditions precedent to its obligations. No Selling Holder shall be required to make any representations or warranties to or agreements with MarkWest or the underwriters other than representations, warranties or agreements regarding such Selling Holder and its ownership of the securities being registered on its behalf and its intended method of distribution and any other representation required by law.  If any Selling Holder disapproves of the terms of an underwriting, such Selling Holder may elect to withdraw therefrom by notice to MarkWest and the Managing Underwriter; provided, however, that such withdrawal must be made prior to the time in the final sentence of Section 2.02(a)

6

hereof to be effective.  No such withdrawal or abandonment shall affect MarkWest’s obligation to pay Registration Expenses.

Section 2.04           Registration Procedures.  In connection with its obligations contained in Sections 2.01, 2.02 and 2.03, MarkWest will, as expeditiously as possible:

(a)           prepare and file with the Commission such amendments and supplements to the Shelf Registration Statement and the prospectus used in connection therewith as may be necessary to keep the Shelf Registration Statement effective for the Effectiveness Period and as may be necessary to comply with the provisions of the Securities Act with respect to the disposition of all securities covered by the Shelf Registration Statement;

(b)           furnish to each Selling Holder (i) as far in advance as reasonably practicable before filing the Shelf Registration Statement or any other registration statement contemplated by this Agreement or any supplement or amendment thereto, upon request, copies of reasonably complete drafts of all such documents proposed to be filed (including exhibits and each document incorporated by reference therein to the extent then required by the rules and regulations of the Commission), and provide each such Selling Holder the opportunity to object to any information pertaining to such Selling Holder and its plan of distribution that is contained therein and make the corrections reasonably requested by such Selling Holder with respect to such information prior to filing the Shelf Registration Statement or such other registration statement or supplement or amendment thereto, and (ii) such number of copies of the Shelf Registration Statement or such other registration statement and the prospectus included therein and any supplements and amendments thereto as such Persons may reasonably request in order to facilitate the public sale or other disposition of the Registrable Securities covered by such Shelf Registration Statement or other registration statement;

(c)           if applicable, use its commercially reasonable efforts to register or qualify the Registrable Securities covered by the Shelf Registration Statement or any other registration statement contemplated by this Agreement under the securities or blue sky laws of such jurisdictions as the Selling Holders or, in the case of an Underwritten Offering, the Managing Underwriter, shall reasonably request, provided that MarkWest will not be required to qualify generally to transact business in any jurisdiction where it is not then required to so qualify or to take any action which would subject it to general service of process in any such jurisdiction where it is not then so subject;

(d)           promptly notify each Selling Holder and each underwriter, at any time when a prospectus relating thereto is required to be delivered under the Securities Act, of (i) the filing of the Shelf Registration Statement or any other registration statement contemplated by this Agreement or any prospectus or prospectus supplement to be used in connection therewith, or any amendment or supplement thereto, and, with respect to such Shelf Registration Statement or any other registration statement or any post-effective amendment thereto, when the same has become effective; and (ii) any written comments from the Commission with respect to any filing referred to in clause (i) and any written request by the Commission for amendments or supplements to the Shelf Registration Statement or any other registration statement or any prospectus or prospectus supplement thereto;

7

(e)           immediately notify each Selling Holder and each underwriter, at any time when a prospectus relating thereto is required to be delivered under the Securities Act, of (i) the happening of any event as a result of which the prospectus or prospectus supplement contained in the Shelf Registration Statement or any other registration statement contemplated by this Agreement, as then in effect, includes an untrue statement of a material fact or omits to state any material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing; (ii) the issuance or threat of issuance by the Commission of any stop order suspending the effectiveness of the Shelf Registration Statement or any other registration statement contemplated by this Agreement, or the initiation of any proceedings for that purpose; or (iii) the receipt by MarkWest of any notification with respect to the suspension of the qualification of any Registrable Securities for sale under the applicable securities or blue sky laws of any jurisdiction.  Following the provision of such notice, MarkWest agrees to as promptly as practicable amend or supplement the prospectus or prospectus supplement or take other appropriate action so that the prospectus or prospectus supplement does not include an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing and to take such other action as is necessary to remove a stop order, suspension, threat thereof or proceedings related thereto;

(f)            furnish to each Selling Holder copies of any and all transmittal letters or other correspondence with the Commission or any other governmental agency or self-regulatory body or other body having jurisdiction (including any domestic or foreign securities exchange) relating to such offering of Registrable Securities;

(g)           in the case of an Underwritten Offering, furnish upon request, (i) an opinion of counsel for MarkWest, dated the effective date of the applicable registration statement or the date of any amendment or supplement thereto, and a letter of like kind dated the date of the closing under the underwriting agreement, and (ii) a “cold comfort” letter, dated the effective date of the applicable registration statement or the date of any amendment or supplement thereto and a letter of like kind dated the date of the closing under the underwriting agreement, in each case, signed by the independent public accountants who have certified MarkWest’s financial statements included or incorporated by reference into the applicable registration statement, and each of the opinion and the “cold comfort” letter shall be in customary form and covering substantially the same matters with respect to such registration statement (and the prospectus and any prospectus supplement included therein) and as are customarily covered in opinions of issuer’s counsel and in accountants’ letters delivered to the underwriters in Underwritten Offerings of securities, such other matters as such underwriters may reasonably request;

(h)           otherwise use its commercially reasonable efforts to comply with all applicable rules and regulations of the Commission, and make available to its security holders, as soon as reasonably practicable, an earnings statement covering the period of at least 12 months, but not more than 18 months, beginning with the first full calendar month after the effective date of such registration statement, which earnings statement shall satisfy the provisions of Section 11(a) of the Securities Act and Rule 158 promulgated thereunder;

(i)            make available to the appropriate representatives of the Managing Underwriter and Selling Holders access to such information and MarkWest personnel as is

8

reasonable and customary to enable such parties to establish a due diligence defense under the Securities Act; provided that MarkWest need not disclose any information to any such representative unless and until such representative has entered into a confidentiality agreement with MarkWest;

(j)            cause all such Registrable Securities registered pursuant to this Agreement to be listed on each securities exchange or nationally recognized quotation system on which similar securities issued by MarkWest are then listed;

(k)           use its commercially reasonable efforts to cause the Registrable Securities to be registered with or approved by such other governmental agencies or authorities as may be necessary by virtue of the business and operations of MarkWest to enable the Selling Holders to consummate the disposition of such Registrable Securities;

(l)            provide a transfer agent and registrar for all Registrable Securities covered by such registration statement not later than the effective date of such registration statement; and

(m)          enter into customary agreements and take such other actions as are reasonably requested by the Selling Holders or the underwriters, if any, in order to expedite or facilitate the disposition of such Registrable Securities.

Each Selling Holder, upon receipt of notice from MarkWest of the happening of any event of the kind described in subsection (e) of this Section 2.04, shall forthwith discontinue disposition of the Registrable Securities until such Selling Holder’s receipt of the copies of the supplemented or amended prospectus contemplated by subsection (e) of this Section 2.04 or until it is advised in writing by MarkWest that the use of the prospectus may be resumed, and has received copies of any additional or supplemental filings incorporated by reference in the prospectus, and, if so directed by MarkWest, such Selling Holder will, or will request the managing underwriter or underwriters, if any, to deliver to MarkWest (at MarkWest’s expense) all copies in their possession or control, other than permanent file copies then in such Selling Holder’s possession, of the prospectus covering such Registrable Securities current at the time of receipt of such notice.

Section 2.05           Cooperation by Holders.  MarkWest shall have no obligation to include in the Shelf Registration Statement units of a Holder or in a Piggyback Registration units of a Selling Holder who has failed to timely furnish such information which, in the opinion of counsel to MarkWest, is reasonably required in order for the registration statement or prospectus supplement, as applicable, to comply with the Securities Act.

Section 2.06           Restrictions on Public Sale by Holders of Registrable Securities.  Each Holder of Registrable Securities who is included in the Shelf Registration Statement agrees not to effect any public sale or distribution of the Registrable Securities during the 90 calendar day period beginning on the date of a prospectus supplement filed with the Commission with respect to the pricing of an Underwritten Offering, provided that the duration of the foregoing restrictions shall be no longer than the duration of the shortest restriction generally imposed by the underwriters on the officers or directors or any other unitholder of MarkWest on whom a restriction is imposed; provided, however, that the restrictions under this Section 2.06 shall not

9

apply to any Holder if such Holder, along with its Affiliates, beneficially owns (in the aggregate) less than 5% of the outstanding Common Units.

Section 2.07           Expenses.

(a)           Certain Definitions.  “Registration Expenses” means all expenses incident to MarkWest’s performance under or compliance with this Agreement to effect the registration of Registrable Securities in a Shelf Registration or a Piggyback Registration, or otherwise pursuant to Section 2.03, and the disposition of such securities, including, without limitation, all registration, filing, securities exchange listing and American Stock Exchange fees, all registration, filing, qualification and other fees and expenses of complying with securities or blue sky laws, fees of the National Association of Securities Dealers, Inc., transfer taxes and fees of transfer agents and registrars, all word processing, duplicating and printing expenses, the fees and disbursements of counsel and independent public accountants for MarkWest, including the expenses of any special audits or “cold comfort” letters required by or incident to such performance and compliance.  Except as otherwise provided in Section 2.08 hereof, MarkWest shall not be responsible for legal fees incurred by Holders in connection with the exercise of such Holders’ rights hereunder.  In addition, MarkWest shall not be responsible for any “Selling Expenses,” which means all underwriting fees, discounts and selling commissions allocable to the sale of the Registrable Securities.

(b)           Expenses.  MarkWest will pay all Registration Expenses in connection with the Shelf Registration Statement filed pursuant to Section 2.01(a) of this Agreement, and MarkWest will pay all Registration Expenses in connection with a Piggyback Registration, whether or not the applicable registration statement becomes effective or any sale is made pursuant to the Shelf Registration Statement or Piggyback Registration. Each Selling Holder shall pay all Selling Expenses in connection with any sale of its Registrable Securities hereunder.

Section 2.08           Indemnification.

(a)           By MarkWest.  In the event of a registration of any Registrable Securities under the Securities Act pursuant to this Agreement, MarkWest will indemnify and hold harmless each Selling Holder thereunder, its Affiliates and their respective directors and officers, and each underwriter, pursuant to the applicable underwriting agreement with such underwriter, of Registrable Securities thereunder and each Person, if any, who controls such Selling Holder or underwriter within the meaning of the Securities Act and the Exchange Act (collectively, the “Selling Holder Indemnified Persons”), against any losses, claims, damages, expenses or liabilities (including reasonable attorneys’ fees and expenses) (collectively, “Losses”), joint or several, to which such Selling Holder Indemnified Person may become subject under the Securities Act, the Exchange Act or otherwise, insofar as such Losses (or actions or proceedings, whether commenced or threatened, in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in the Shelf Registration Statement or any other registration statement contemplated by this Agreement, any preliminary prospectus or final prospectus contained therein, or any amendment or supplement thereof, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein (in the case of a prospectus, in light of the circumstances under which they were made) not misleading, and will

10

reimburse each such Selling Holder Indemnified Person for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such Loss or actions or proceedings; provided, however, that MarkWest will not be liable in any such case if and to the extent that any such Loss arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission so made in conformity with information furnished by such Selling Holder Indemnified Person in writing specifically for use in the Shelf Registration Statement or such other registration statement, or prospectus supplement, as applicable. Such indemnity shall remain in full force and effect regardless of any investigation made by or on behalf of such Selling Holder Indemnified Person, and shall survive the transfer of such securities by such Selling Holder.

(b)           By Each Selling Holder.  Each Selling Holder agrees severally and not jointly to indemnify and hold harmless MarkWest, its Affiliates and their respective directors and officers, and each Person, if any, who controls MarkWest within the meaning of the Securities Act or of the Exchange Act to the same extent as the foregoing indemnity from MarkWest to the Selling Holders, but only with respect to information regarding such Selling Holder furnished in writing by or on behalf of such Selling Holder expressly for inclusion in the Shelf Registration Statement or prospectus supplement relating to the Registrable Securities, or any amendment or supplement thereto; provided, however, that the liability of each Selling Holder shall not be greater in amount than the dollar amount of the proceeds (net of any Selling Expenses) received by such Selling Holder from the sale of the Registrable Securities giving rise to such indemnification.

(c)           Notice.  Promptly after receipt by an indemnified party hereunder of notice of the commencement of any action, such indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party hereunder, notify the indemnifying party in writing thereof, but the omission so to notify the indemnifying party shall not relieve it from any liability which it may have to any indemnified party other than under this Section 2.08.  In any action brought against any indemnified party, it shall notify the indemnifying party of the commencement thereof.  The indemnifying party shall be entitled to participate in and, to the extent it shall wish, to assume and undertake the defense thereof with counsel reasonably satisfactory to such indemnified party and, after notice from the indemnifying party to such indemnified party of its election so to assume and undertake the defense thereof, the indemnifying party shall not be liable to such indemnified party under this Section 2.08 for any legal expenses subsequently incurred by such indemnified party in connection with the defense thereof other than reasonable costs of investigation and of liaison with counsel so selected; provided, however, that, (i) if the indemnifying party has failed to assume the defense and employ counsel or (ii) if the defendants in any such action include both the indemnified party and the indemnifying party and counsel to the indemnified party shall have concluded that there may be reasonable defenses available to the indemnified party that are different from or additional to those available to the indemnifying party, or if the interests of the indemnified party reasonably may be deemed to conflict with the interests of the indemnifying party, then the indemnified party shall have the right to select a separate counsel and to assume such legal defense and otherwise to participate in the defense of such action, with the reasonable expenses and fees of such separate counsel and other reasonable expenses related to such participation to be reimbursed by the indemnifying party as incurred.  Notwithstanding any other provision of this Agreement, no indemnified party shall settle any action brought against it with respect to

11

which it is entitled to indemnification hereunder without the consent of the indemnifying party, unless the settlement thereof imposes no liability or obligation on, and includes a complete and unconditional release from all liability of, the indemnifying party.

(d)           Contribution.  If the indemnification provided for in this Section 2.08 is held by a court or government agency of competent jurisdiction to be unavailable to MarkWest or any Selling Holder or is insufficient to hold them harmless in respect of any Losses, then each such indemnifying party, in lieu of indemnifying such indemnified party, shall contribute to the amount paid or payable by such indemnified party as a result of such Losses as between MarkWest on the one hand and such Selling Holder on the other, in such proportion as is appropriate to reflect the relative fault of MarkWest on the one hand and of such Selling Holder on the other in connection with the statements or omissions which resulted in such Losses, as well as any other relevant equitable considerations; provided, however, that in no event shall such Selling Holder be required to contribute an aggregate amount in excess of the dollar amount of proceeds (net of Selling Expenses) received by such Selling Holder from the sale of Registrable Securities giving rise to such indemnification.  The relative fault of MarkWest on the one hand and each Selling Holder on the other shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact has been made by, or relates to, information supplied by such party, and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.  The parties hereto agree that it would not be just and equitable if contributions pursuant to this paragraph were to be determined by pro rata allocation or by any other method of allocation which does not take account of the equitable considerations referred to in the first sentence of this paragraph.  The amount paid by an indemnified party as a result of the Losses referred to in the first sentence of this paragraph shall be deemed to include any legal and other expenses reasonably incurred by such indemnified party in connection with investigating or defending any Loss which is the subject of this paragraph. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any Person who is not guilty of such fraudulent misrepresentation.

(e)           Other Indemnification.  The provisions of this Section 2.08 shall be in addition to any other rights to indemnification or contribution which an indemnified party may have pursuant to law, equity, contract or otherwise.

Section 2.09           Rule 144 Reporting.  With a view to making available the benefits of certain rules and regulations of the Commission that may permit the sale of the Registrable Securities to the public without registration, MarkWest agrees to use its commercially reasonable efforts to:

(a)           Make and keep public information regarding MarkWest available, as those terms are understood and defined in Rule 144 of the Securities Act, at all times from and after the date hereof;

(b)           File with the Commission in a timely manner all reports and other documents required of MarkWest under the Securities Act and the Exchange Act at all times from and after the date hereof; and

12

(c)           So long as a Holder owns any Registrable Securities, furnish to such Holder forthwith upon request a copy of the most recent annual or quarterly report of MarkWest, and such other reports and documents so filed as such Holder may reasonably request in availing itself of any rule or regulation of the Commission allowing such Holder to sell any such securities without registration.

Section 2.10           Transfer or Assignment of Registration Rights.  The rights to cause MarkWest to register Registrable Securities granted to the Purchasers by MarkWest under this Article II may be transferred or assigned by the Purchasers to one or more transferee(s) or assignee(s) of such Registrable Securities, provided that (a) unless such transferee is an Affiliate of the transferring Purchaser, each such transferee or assignee holds Registrable Securities representing at least 15% of the total number of Purchased Units sold pursuant to the terms of the Purchase Agreement, (b) MarkWest is given written notice prior to any said transfer or assignment, stating the name and address of each such transferee and identifying the securities with respect to which such registration rights are being transferred or assigned, and (c) each such transferee assumes in writing responsibility for its portion of the obligations of the Purchasers under this Agreement.

ARTICLE III.

MISCELLANEOUS

Section 3.01           Communications.  All notices and other communications provided for or permitted hereunder shall be made in writing by facsimile, courier service or personal delivery:

(a)           if to the Purchasers, at the most current addresses given by the Purchasers to MarkWest in accordance with the provisions of this Section 3.01, which addresses initially are, with respect to the Purchasers, the addresses set forth in the Purchase Agreement,

(b)           if to a transferee of the Purchaser, to such Holder at the address provided pursuant to Section 2.10 above, and

(c)           if to MarkWest, at 155 Inverness Drive West, Suite 200, Englewood, CO  80112, notice of which is given in accordance with the provisions of this Section 3.01.

All such notices and communications shall be deemed to have been received at the time delivered by hand, if personally delivered; when receipt acknowledged, if sent via facsimile or sent via Internet electronic mail; and when actually received, if sent by any other means.

Section 3.02           Successor and Assigns.  This Agreement shall inure to the benefit of and be binding upon the successors and assigns of each of the parties, including subsequent Holders of Registrable Securities to the extent permitted herein.

Section 3.03           Assignment of Rights.  All or any portion of the rights and obligations of the Purchasers under this Agreement may be transferred or assigned by the Purchasers in accordance with Section 2.10 hereof.

Section 3.04           Recapitalization, Exchanges, etc. Affecting the Common Units.  The provisions of this Agreement shall apply to the full extent set forth herein with respect to any and

13

all units of MarkWest or any successor or assign of MarkWest (whether by merger, consolidation, sale of assets or otherwise) which may be issued in respect of, in exchange for or in substitution of, the Registrable Securities, and shall be appropriately adjusted for combinations, recapitalizations and the like occurring after the date of this Agreement.

Section 3.05           Specific Performance.  Damages in the event of breach of this Agreement by a party hereto may be difficult, if not impossible, to ascertain, and it is therefore agreed that each such Person, in addition to and without limiting any other remedy or right it may have, will have the right to an injunction or other equitable relief in any court of competent jurisdiction, enjoining any such breach, and enforcing specifically the terms and provisions hereof, and each of the parties hereto hereby waives any and all defenses it may have on the ground of lack of jurisdiction or competence of the court to grant such an injunction or other equitable relief.  The existence of this right will not preclude any such Person from pursuing any other rights and remedies at law or in equity which such Person may have.

Section 3.06           Counterparts.  This Agreement may be executed in any number of counterparts and by different parties hereto in separate counterparts, each of which counterparts, when so executed and delivered, shall be deemed to be an original and all of which counterparts, taken together, shall constitute but one and the same Agreement.

Section 3.07           Headings.  The headings in this Agreement are for convenience of reference only and shall not limit or otherwise affect the meaning hereof.

Section 3.08           Governing Law.  The laws of the State of Delaware shall govern this Agreement without regard to principles of conflict of laws.

Section 3.09           Severability of Provisions.  Any provision of this Agreement which is prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions hereof or affecting or impairing the validity or enforceability of such provision in any other jurisdiction.

Section 3.10           Entire Agreement.  This Agreement is intended by the parties as a final expression of their agreement and intended to be a complete and exclusive statement of the agreement and understanding of the parties hereto in respect of the subject matter contained herein.  There are no restrictions, promises, warranties or undertakings, other than those set forth or referred to herein with respect to the rights granted by MarkWest set forth herein.  This Agreement supersedes all prior agreements and understandings between the parties with respect to such subject matter.

Section 3.11           Amendment.  This Agreement may be amended only by means of a written amendment signed by MarkWest and the Holders of a majority of the then outstanding Registrable Securities; provided, however, that no such amendment shall materially and adversely affect the rights of any Holder hereunder without the consent of such Holder.

Section 3.12           No Presumption.In the event any claim is made by a party relating to any conflict, omission, or ambiguity in this Agreement, no presumption or burden of proof or

14

persuasion shall be implied by virtue of the fact that this Agreement was prepared by or at the request of a particular party or its counsel.

[The remainder of this page is intentionally left blank.]

15

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first written above.

MARKWEST ENERGY PARTNERS, LP.
By:	MarkWest Energy GP, L.L.C.,
	its general partner
By:	/s/ MarkWest Energy Partners, L.P.
Name:	MarkWest Energy Partners, L.P.
Title:
KAYNE ANDERSON ENERGY FUND II, L.P.
By:	KAEFTX, L.P., its general partner
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Energy Fund II, L.P.
Name:	Kayne Anderson Energy Fund II, L.P.
Title:
KAYNE ANDERSON CAPITAL INCOME PARTNERS (QP), L.P.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Capital Income Partners (QP), L.P.
Name:	Kayne Anderson Capital Income Partners (QP), L.P.
Title:

KAYNE ANDERSON MLP FUND, L.P.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson MLP Fund, L.P.
Name:	Kayne Anderson MLP Fund, L.P.
Title:
KAYNE ANDERSON CAPITAL INCOME FUND, LTD.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Capital Income Fund, LTD.
Name:	Kayne Anderson Capital Income Fund, LTD.
Title:
KAYNE ANDERSON INCOME PARTNERS, L.P.
By:	Kayne Anderson Capital Advisors, L.P., its general partner
By:	Kayne Anderson Investment Management, Inc., its general partner
By:	/s/ Kayne Anderson Income Partners, L.P.
Name:	Kayne Anderson Income Partners, L.P.
Title:

TORTOISE ENERGY INFRASTRUCTURE CORPORATION
By:	/s/ David J. Schulte
Name:	David J. Schulte
Title:	President
ENERGY INCOME AND GROWTH FUND
By:	/s/ Energy Income and Growth Fund
Name:	Energy Income and Growth Fund
Title:

HFR RV PERFORMANCE MASTER TRUST
By:	HFR RV Performance Master Trust	, its trustee
By:	/s/ HFR RV Performance Master Trust
Name:	HFR RV Performance Master Trust
Title:

EX-23.1

Exhibit 23.1

Report of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the registration statement of MarkWest Hydrocarbon, Inc., on Form S-8 (File No. 333-37642) of our report dated March 2, 2004, on our audits of the consolidated financial statements of American Central Eastern Texas Gas Company, Limited Partnership as of December 31, 2003 and 2002 and for the years ended December 31, 2003, 2002, and 2001, which report is included in the Current Report on Form 8-K/A.

/s/ BKD, LLP

Tulsa, Oklahoma

October 12, 2004

EX-99.1

Exhibit 99.1

SECOND AMENDED AND RESTATED

CREDIT AGREEMENT

Originally dated as of May 20, 2002 and amended by First Amendment
dated as of March 28, 2003

and

Amended and Restated in its entirety as of December 1, 2003

and

amended by First Amendment dated as of January 16, 2004

and

as amended and restated as of July 30, 2004

among

MARKWEST ENERGY OPERATING COMPANY, L.L.C.,

as the Borrower,

MARKWEST ENERGY PARTNERS, L.P.,

as a Guarantor

ROYAL BANK OF CANADA,

as Administrative Agent

FORTIS CAPITAL CORP.,

as Syndication Agent

BANK ONE, NA,

as Documentation Agent

SOCIETE GENERALE,

as Documentation Agent

and

The Lenders Party Hereto

$315,000,000

SENIOR CREDIT FACILITY

RBC CAPITAL MARKETS

As Lead Arranger and Sole Bookrunner

Dated as of July 30, 2004

TABLE OF CONTENTS

ARTICLE I.		DEFINITIONS AND ACOUNTING TERMS
	1.01	Defined Terms
	1.02	Other Interpretive Provisions
	1.03	Accounting Terms
	1.04	Rounding
	1.05	References to Agreements and Laws
ARTICLE II.		THE COMMITMENTS AND BORROWINGS
	2.01	Revolver Loans
	2.02	Term Loans
	2.03	Borrowings, Conversions and Continuations of Loans
	2.04	Prepayments
	2.05	Reduction or Termination of Commitments
	2.06	Repayment of Loans
	2.07	Interest
	2.08	Fees
	2.09	Computation of Interest and Fees
	2.10	Evidence of Debt
	2.11	Payments Generally
	2.12	Sharing of Payments
	2.13	Priority of Hedging Obligations and Banking Service Obligations
	2.14	Letters of Credit
ARTICLE III		TAXES, YIELD PROTECTION AND ILLEGALITY
	3.01	Taxes
	3.02	Illegality
	3.03	Inability to Determine Rates
	3.04	Increased Cost and Reduced Return; Capital Adequacy; Reserves on Eurodollar Rate Loans
	3.05	Funding Losses
	3.06	Matters Applicable to all Requests for Compensation
	3.07	Survival
ARTICLE IV.		TAXES, YIELD PROTECTION AND ILLEGALITY
	4.01	Conditions Precedent to Amendment and Restatement of Agreement
	4.02	Conditions to all Loans and L/C Credit Extension
ARTICLE V		REPRESENTATIONS AND WARRANTIES.
	5.01	Existence; Qualification and Power; Compliance with Laws
	5.02	Authorization; No Contravention
	5.03	Governmental Authorization

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	5.04	Binding Effect
	5.05	Financial Statements; No Material Adverse Effect
	5.06	Litigation
	5.07	No Default
	5.08	Ownership of Property; Liens
	5.09	Environmental Compliance
	5.10	Insurance
	5.11	Taxes
	5.12	ERISA Compliance
	5.13	Subsidiaries and other Investments
	5.14	Margin Regulations; Investment Company Act;  Public Utility Holding Company Act; Use of Proceeds
	5.15	Disclosure
	5.16	Labor Matters
	5.17	Compliance with Laws
	5.18	Third Party Approvals
	5.19	Solvency
	5.20	Collateral
ARTICLE VI.		AFFIRMATIVE COVENANTS
	6.01	Financial Statements
	6.02	Certificates; Other Information
	6.03	Notices
	6.04	Payment of Obligations
	6.05	Preservation of Existence, Etc.
	6.06	Maintenance of Assets and Business
	6.07	Maintenance of Insurance
	6.08	Compliance with Laws and Contractual Obligations
	6.09	Books and Records
	6.10	Inspection Rights
	6.11	Compliance with ERISA
	6.12	Use of Proceeds
	6.13	Material Agreements
	6.14	Clean Down Period
	6.15	Guaranties
	6.16	Further Assurances; Additional Collateral
ARTICLE VII		NEGATIVE COVENANTS.
	7.01	Liens
	7.02	Investments
	7.03	Hedging Agreements
	7.04	Indebtedness
	7.05	Lease Obligations
	7.06	Fundamental Changes

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	7.07	Dispositions
	7.08	Restricted Payments; Distributions and Redemptions
	7.09	ERISA
	7.10	Nature of Business; Capital Expenditures; Risk Management
	7.11	Transactions with Affiliates
	7.12	Burdensome Agreements
	7.13	Use of Proceeds
	7.14	Material Agreements
	7.15	Financial Covenants
	7.16	Counterparty Consents
	7.17	Subordinated Indebtedness
ARTICLE VIII.		EVENTS OF DEFAULT AND REMEDIES
	8.01	Events of Default
	8.02	Remedies Upon Event of Default
ARTICLE IX.		ADMINISTRATIVE AGENT
	9.01	Appointment and Authorization of Agents; Lender Hedging Agreements
	9.02	Delegation of Duties
	9.03	Default; Collateral
	9.04	Liability of Agents
	9.05	Reliance by Administrative Agent
	9.06	Notice of Default
	9.07	Credit Decision; Disclosure of Information by Administrative Agent
	9.08	Indemnification of Agents
	9.09	Administrative Agent in its Individual Capacity
	9.10	Successor Administrative Agent
	9.11	Syndication Agent; Other Agents; Arranger
ARTICLE X		MISCELLANEOUS.
	10.01	Amendments, Release of Collateral, Etc
	10.02	Notices and Other Communications; Facsimile Copies
	10.03	No Waiver; Cumulative Remedies
	10.04	Attorney Costs; Expenses and Taxes
	10.05	Indemnification
	10.06	Payments Set Aside
	10.07	Successors and Assigns
	10.08	Confidentiality
	10.09	Set-off
	10.10	Interest Rate Limitation
	10.11	Counterparts
	10.12	Integration
	10.13	Survival of Representations and Warranties
	10.14	Severability
	10.15	Foreign Lenders

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10.16	Governing Law
10.17	Waiver of Right to Trial by Jury, Etc
10.18	Security Interest In Amended and Restated MarkWest Parent Deposit Pledge Agreement
10.19	No General Partner’s Liability
10.20	Termination of Commitments Under First Amended and Restated Credit Agreement
10.21	No Novations, Etc
10.22	ENTIRE AGREEMENT

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SCHEDULES
2.01	Commitments
5.13	Subsidiaries and other Equity Investments
7.01	Existing Liens
7.04	Indebtedness Assumed in ACET Acquisition
7.05	Operating Leases
7.12	Agreements Restricting Liens on Leasehold Interests
10.02	Addresses for Notices to Borrower, Guarantors and Administrative Agent

EXHIBITS

Exhibit:	Form of:
A-1	Borrowing Notice
A-2	Conversion/Continuation Notice
B-1	Revolver Note
B-2	Term Note
C	Compliance Certificate pursuant to Section 6.02(a)
D	Assignment and Assumption
E-1	Amended and Restated MLP Guaranty
E-2	Amended and Restated Subsidiary Guaranty
E-3	Subsidiary Guaranty
F-1	Legal Opinion of Hogan & Hartson L.L.P.
G	Subsidiary Pledge and Security Agreement

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SECOND AMENDED AND RESTATED CREDIT AGREEMENT

Originally dated as of May 20, 2002 and amended by First Amendment

dated as of March 28, 2003

and

Amended and Restated in its entirety as of December 1, 2003

and

amended by First Amendment dated as of January 16, 2004

and

as amended and restated as of July 30, 2004

THIS SECOND AMENDED AND RESTATED CREDIT AGREEMENT (“Agreement”) is entered into as of July 30, 2004, among MARKWEST ENERGY OPERATING COMPANY, L.L.C., a Delaware limited liability company (the “Borrower”), MARKWEST ENERGY PARTNERS, L.P., a Delaware limited partnership (the “MLP”), each lender from time to time party hereto (collectively, the “Lenders” and individually, “Lender”), ROYAL BANK OF CANADA, as Administrative Agent.

PRELIMINARY STATEMENTS

(1)The Borrower, the MLP, Bank of America, N.A., individually and as initial administrative agent (“Bank of America”), Fortis Capital Corp. (“Fortis”), Wells Fargo Bank, N.A. (“Wells Fargo”), U.S. Bank National Association (“US Bank”), Bank of Oklahoma, N.A. (“Bank of Oklahoma”) and Royal Bank of Canada (“Royal Bank”; Bank of America, Fortis, Wells Fargo, US Bank, Bank of Oklahoma and Royal Bank collectively called the “Original Lenders”) entered into a Credit Agreement originally dated May 20, 2002 providing for an aggregate credit facility of $60,000,000, as amended by a First Amendment to Credit Agreement among the Borrower, the MLP and the Original Lenders (with Royal Bank succeeding Bank of America as administrative agent) dated March 28, 2003, pursuant to which First Amendment the aggregate credit facility was increased to $75,000,000 (as amended, the “Original Credit Agreement”).

(2)Pursuant to the provisions of Section 10.07 of the Original Credit Agreement and Assignment and Assumption Agreements each dated December 1, 2003, each of Bank of America, Fortis, Wells Fargo, US Bank and Bank of Oklahoma assigned all of their rights and obligations under the Original Credit Agreement (including all of their respective commitments and loans and participations in letters of credit thereunder and all liens and security interests granted as security for indebtedness under the Original Credit Agreement) to Royal Bank and Royal Bank, as administrative agent under the Original Credit Agreement, accepted and recorded such assignments and the Borrower also consented to such assignments.

(3)The Original Credit Agreement was amended and restated in its entirety by an Amended and Restated Credit Agreement dated December 1, 2003 among Borrower, the MLP, Royal Bank, as administrative agent, Bank One, NA (“Bank One”), as documentation agent, and

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Fortis, as syndication agent, providing for an aggregate credit facility of $140,000,000 (as amended, the “First Amended and Restated Credit Agreement”).

(4)Pursuant to the provisions of Section 10.7 of the Amended and Restated Credit Agreement and a Master Assignment and Assumption dated January 15, 2004 among Royal Bank, Bank One and Fortis, as assignors, and Bank of Oklahoma, Comerica Bank (“Comerica”), Guaranty Bank, FSB (“Guaranty”), U.S. Bank, National Association (“US Bank”) and Wells Fargo, as assignees, each of Royal Bank, Bank One and Fortis assigned a portion of their respective rights and obligations under the First Amended and Restated Credit Agreement (including a portion of their respective commitments and loans and participations in letters of credit thereunder and a proportionate undivided interest in the liens and security interests granted as security for indebtedness under the First Amended and Restated Credit Agreement) to Bank of Oklahoma, Comerica Guaranty, and Wells Fargo and the First Amended and Restated Credit Agreement was amended by a First Amendment dated January 16, 2004.

(5)Pursuant to the provisions of Section 10.07 of the First Amended and Restated Credit Agreement and Assignment and Assumption Agreements each dated of even date herewith, each of Bank of Oklahoma, Comerica, Guaranty,  and Wells Fargo assigned all of their rights and obligations under the First Amended and Restated Credit Agreement (including all of their respective commitments and loans and participations in letters of credit thereunder and all liens and security interests granted as security for indebtedness under the First Amended and Restated Credit Agreement) to Royal Bank, as administrative agent under the First Amended and Restated Credit Agreement (and Royal Bank, as administrative Agent under the First Amended and Restated Credit Agreement, hereby waives the $3,500 processing and recordation fee for each assignment) and Royal Bank, as administrative agent under the First Amended and Restated Credit Agreement, accepted and recorded such assignments and the Borrower also consented to such assignments.

(6)Concurrently with such assignment to Royal Bank, Royal Bank has assigned to Societe Generale a 16% interest in the commitments and loans and letters of credit outstanding under the First Amended and Restated Credit Agreement and the interest in such commitments and loans and letters of credit have been increased to 22% for Fortis, 22% for Bank One and 11% for US Bank (with Royal Bank’s interest therein being 29%) and contemporaneously with such assignments to Fortis, US Bank, Bank One and Societe Generale, the Borrower, the MLP and Royal Bank, Fortis, US Bank, Bank One and Societe Generale have agreed to amend and restate in its entirety the First Amended and Restated Credit Agreement on the terms and conditions set forth herein, to renew and rearrange the indebtedness outstanding under the First Amended and Restated Credit Agreement (but not to repay or pay off such indebtedness) and to increase the Aggregate Commitments to THREE HUNDRED FIFTEEN MILLION DOLLARS ($315,000,000.00).

NOW, THEREFORE, in consideration of the mutual covenants and agreements herein contained, the parties hereto hereby agree that the First Amended and Restated Credit Agreement is amended and restated in its entirety to read as follows:

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ARTICLE I.
DEFINITIONS AND ACCOUNTING TERMS

1.01Defined Terms.

As used in this Agreement, the terms defined in the introductory paragraph hereof and in the preliminary statements hereto shall have the meanings therein indicated and the following terms shall have the meanings set forth below:

ACET Acquisition means the acquisition by MW Energy of a natural gas pipeline, gathering systems, processing facilities and related assets located in the State of Texas from American Central Eastern Texas Gas Company Limited Partnership, an Oklahoma limited partnership, and ACGC Gathering Company, L.L.C., an Oklahoma limited liability company, as sellers pursuant to the ACET PSA.

ACET Assumed Guaranty means the guaranty assumed by the MLP pursuant to the Guaranty Assumption Agreement attached as Exhibit CC to the ACET PSA of the guaranty originally given by American Central Gas Technologies, Inc., parent of American Central Eastern Texas Gas Company Limited Partnership and ACGC Gathering Company, L.L.C., to Chevron Texaco Exploration and Production Company, a division of Chevron USA, Inc. under a Guaranty dated May 20, 2004.

ACET Construction Agreement means the Design and Construction Agreement dated March 2, 2004 among American Central Eastern Texas Gas Company Limited Partnership, and ACGC Gathering Company, L.L.C. and Engineering Procurement and Construction, Inc., relating to the redesign, refurbishment and skid mounting of a natural gas processing plant previously known as the Shell Oil Company Crawfish Plant.

ACET Gas Gathering Agreements means collectively the gas gathering agreements listed on Exhibit “I” to the ACET PSA.

ACET Gas Processing Agreements means collectively (i) the Gas Gathering and Processing Agreement dated February 13, 2004, as amended on May 20, 2004 between Chevron Texaco Exploration and Production Company, a division of Chevron USA, Inc. and  American Central Eastern Texas Gas Company Limited Partnership, and ACGC Gathering Company, L.L.C., (ii) Gas Gathering and Processing Agreement dated June 4, 2004 between American Central Eastern Texas Gas Company Limited Partnership and Total E&P USA, Inc.; and (iii) all of the other gas processing agreements listed on Exhibit “I” to the ACET PSA.

ACET/NGPL Contracts means collectively (i) Agreement Regarding Facilities Necessary for Natural Gas Pipeline Company of America to Receive Gas from American Central Gas Technologies, Inc. in Panola County, Texas and (ii) Operational Gas Balancing Agreement with Natural Gas Pipeline Company of America.

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ACET PSA means the Asset Purchase and Sale Agreement dated July 1, 2004, among MW Energy, as purchaser, American Central Eastern Texas Gas Company Limited Partnership, and ACGC Gathering Company, L.L.C., as sellers, together with all schedules, exhibits and annexes thereto.

Acquisition means any transaction or series of related transactions for the purpose of, or resulting in, directly or indirectly, (a) the acquisition by a Company of all or substantially all of the assets located in the United States of a Person or of any business or division of a Person; (b) the acquisition by a Company of more than 50% of any class of Voting Stock (or similar ownership interests) of any Domestic Person; or (c) a merger, consolidation, amalgamation, or other combination by a Company with another Person if a Company is the surviving entity, provided that, (i) in any merger involving the Borrower, the Borrower must be the surviving entity; and (ii) in any merger involving a Wholly-Owned Subsidiary and another Subsidiary, a Wholly-Owned Subsidiary shall be the survivor.

Administrative Agent means Royal Bank of Canada in its capacity as administrative agent under any of the Loan Documents, or any successor administrative agent.

Administrative Agent’s Office means the Administrative Agent’s address and, as appropriate, account as set forth on Schedule 10.02, or such other address or account as the Administrative Agent may from time to time notify to the Borrower and the Lenders.

Administrative Details Form means the Administrative Details Reply Form furnished by a  Lender to the Administrative Agent in connection with this Agreement.

Affiliate means, as to any Person, any other Person directly or indirectly controlling, controlled by, or under direct or indirect common control with, such Person.  A Person shall be deemed to be controlled by any other Person if such other Person possesses, directly or indirectly, power (a) to vote 10% or more of the securities (on a fully diluted basis) having ordinary voting power for the election of directors, managing members, or managing general partners; or (b) to direct or cause the direction of the management and policies of such Person whether by contract or otherwise.

Agent/Arranger Fee Letter has the meaning specified in Section 2.08(b).

Agents means collectively the Administrative Agent and the Syndication Agent and Agent individually means either of them.

Agent-Related Persons means the Administrative Agent (including any successor administrative agent), the Syndication Agent (including any successor syndication agent) and their respective Affiliates (including the officers, directors, employees, agents and attorneys-in-fact of such Person).

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Aggregate Commitments means the sum of (i) the Aggregate Revolver Commitments and (ii) the Aggregate Term Loan Commitments, and as of the Restatement Date the Aggregate Commitments are $315,000,000.

Agreement means this Second Amended and Restated Credit Agreement.

Amended and Restated MLP Guaranty means the Amended and Restated MLP Guaranty  made by the MLP as of the Restatement Date in favor of the Administrative Agent on behalf of the Lenders, substantially in the form of Exhibit E-1, as it may be amended from time to time.

Amended and Restated Subsidiary Guaranty means the Amended and Restated Subsidiary Guaranty  made by each  Subsidiary Guarantor as of the Restatement Date in favor of the Administrative Agent on behalf of the Lenders, substantially in the form of Exhibit E-2, as it may be amended from time to time.

Applicable Rate means the following percentages per annum set forth in the table below, on any date of determination, with respect to the Type of Credit Extension or commitment fee that corresponds to the Leverage Ratio at such date of determination, as calculated based on the quarterly Compliance Certificate most recently delivered pursuant to Section 6.02(a):

Applicable Rate

Pricing Level	Leverage Ratio	Commit- ment Fee (bps)	Letter of Credit and Revolver Eurodollar Rate + (bps)	Term Loan Eurodollar Rate for + (bps)	Revolver Base Rate + (bps)	Term Loan Base Rate + (bps)
1	Less than 5.00:1.00	50.0	350.0	400.0	250.0	300.0
2	Greater than or equal to 5.00:1.00 but less than 6.00:1.00	50.0	400.0	450.0	300.0	350.0
3	Greater than or equal to 6.00:1.00	50.0	450.0	500.0	350.0	400.0

Any increase or decrease in the Applicable Rate resulting from a change in the Leverage Ratio shall become effective as of the first day of the fiscal quarter of the Borrower immediately following the date of a Compliance Certificate delivered pursuant to Section 6.02; provided, however, that if no Compliance Certificate is delivered during a fiscal quarter when due in

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accordance with such Section, the Pricing Level 3 shall apply as of the first day of such following fiscal quarter; provided further within a reasonable period after the MLP Offering the Borrower may submit an interim Compliance Certificate and the Applicable Rate for the next Fiscal Quarter following delivery of such interim Compliance Certificate shall be based upon the Leverage Ratio reflected in such interim Compliance Certificate.  The Applicable Rate in effect from the Restatement Date through September 30, 2004 shall be based upon Pricing Level 2.

Approved Fund means any Fund that is administered or managed by a Lender, an Affiliate of a Lender, or an entity or an Affiliate of an entity that administers or manages a Lender.

Arranger means RBC Capital Markets in its capacity as lead arranger and sole bookrunner.

Assignment and Assumption means an Assignment and Assumption substantially in the form of Exhibit D.

Attorney Costs means and includes the reasonable fees and disbursements of any law firm or other external counsel and the allocated cost of internal legal services and all disbursements of internal counsel.

Attributable Indebtedness means, on any date, (a) in respect of any Capital Lease of any Person, the capitalized amount thereof that would appear on a balance sheet of such Person prepared as of such date in accordance with GAAP, and (b) in respect of any Synthetic Lease Obligation, the capitalized amount of the remaining lease payments under the relevant lease that would appear on a balance sheet of such Person prepared as of such date in accordance with GAAP if such lease were accounted for as a capital lease.

Authorizations means all filings, recordings, and registrations with, and all validations or exemptions, approvals, orders, authorizations, consents, franchises, licenses, certificates, and permits from, any Governmental Authority.

Bank Guaranties means guaranties or other agreements or instruments serving a similar function issued by a bank or other financial institution.

Banking Services means each and any of the following bank services provided to any Loan Party by any Lender or Affiliate of a Lender: (i) commercial credit cards, (ii) stored value cards, and (iii) treasury management services (including, without limitation, controlled disbursement, automated clearinghouse transactions, return items, overdrafts and interstate depository network services).

Banking Service Obligations means any and all obligations of the Loan Parties, whether absolute or contingent and howsoever created, arising, evidenced or acquired (including all renewals, extensions and modifications thereof and substitutions therefor) in connection with Banking Services.

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Base Rate means for any day a fluctuating rate per annum equal to the higher of (a) the Federal Funds Rate plus ½ of 1% and (b) the rate of interest in effect for such day as publicly announced from time to time by the Administrative Agent as its “prime rate.” Such rate is a rate set by the Administrative Agent based upon various factors including the Administrative Agent’s costs and desired return, general economic conditions and other factors, and is used as a reference point for pricing some loans, which may be priced at, above, or below such announced rate.  Any change in such rate announced by the Administrative Agent shall take effect at the opening of business on the day specified in the public announcement of such change.

Base Rate Loan means a Loan that bears interest based on the Base Rate.

Blackhawk Pipeline means that certain natural gas pipeline in Hutchinson County, Texas, approximately five (5) miles in length, connected and transporting gas to the electrical generation plant owned by Borger Energy Associates, LP, known as Blackhawk Station, from the El Paso Pipeline northeast of Borger, Texas.

Board means the Board of Governors of the Federal Reserve System of the United States cf America.

Borrower Affiliate means the Borrower, the General Partner, the MLP, and each of their respective Subsidiaries.

Borrowing means a borrowing consisting of simultaneous Loans of the same Type and having the same Interest Period made by each of the Lenders pursuant to Section 2.01 or Section 2.02.

Borrowing Notice means a notice of (a) a Borrowing, (b) a conversion of Loans from one Type to the other, or (c) a continuation of Loans as the same Type, pursuant to Section 2.03(a), which, if in writing, shall be substantially in the form of Exhibit A-1 or A-2, as applicable.

Business Day means any day other than a Saturday, Sunday, or other day on which commercial banks are authorized to close under the Laws of New York, or are in fact closed and, if such day relates to any Eurodollar Rate Loan, means any such day on which dealings in Dollar deposits are conducted by and between banks in the applicable offshore Dollar interbank market.

Capital Expenditure by a Person means an expenditure (determined in accordance with GAAP) for any fixed asset owned by such Person for use in the operations of such Person having a useful life of more than one year, or any improvements or additions thereto.

Capital Lease means any capital lease or sublease which should be capitalized on a balance sheet in accordance with GAAP.

Cash Collateralize means to pledge and deposit with or deliver to the Administrative Agent, for the benefit of the L/C Issuer and the Lenders, as collateral for the L/C Obligations, cash and deposit account balances pursuant to documentation in form and substance satisfactory

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to the Administrative Agent and the L/C Issuer (which documents hereby are consented to by the Lenders).

Cash Equivalents means:

(a)United States Dollars;

(b)direct general obligations, or obligations of, or obligations fully and unconditionally guaranteed as to the timely payment of principal and interest by, the United States or any agency or instrumentality thereof having remaining maturities of not more than thirteen (13) months, but excluding any such securities whose terms do not provide for payment of a fixed dollar amount upon maturity or call for redemptions;

(c)certificates of deposit and eurodollar- time deposits with maturities of thirteen (13) months or less, bankers acceptances with maturities not exceeding one hundred eighty (180) days, overnight bank deposits and other similar short term instruments, in each case with any domestic commercial bank having capital and surplus in excess of $250,000,000 and having a rating of at least “A2” by Moody’s and at least “A” by S&P;

(d)repurchase obligations with a term of not more than thirteen (13) months for underlying securities of the types described in (b) and (c) above entered into with any financial institution meeting the qualifications in (c) above;

(e)commercial paper (having original maturities of not more than two hundred seventy (270) days) of any Person rated “P-1” or better by Moody’s or “A-1” or the equivalent by S&P; and

(f)money market mutual or similar funds having assets in excess of $100,000,000, at least 95% of the assets of which are comprised of assets specified in clause (a) through (e) above.

Change of Control means (a) MarkWest Parent shall fail to own, directly or indirectly, or fail to have voting control over, at least 51 % of the equity interest of the General Partner, (b) any Person, entity or group (other than MarkWest Parent) acquires beneficial ownership (within the meaning of Rule 13d-3 of the Securities and Exchange Commission under the Securities Exchange Act of 1934) of 66 2/3% or more of the equity interests in the MLP, (c) the MLP shall fail to own, directly or indirectly, 100% of the equity interests in the Borrower, or (e) a Parent Change of Control shall occur.

Change in Law means (a) the adoption of any law, rule or regulation after the date of this Agreement, (b) any change in any law, rule or regulation or in the interpretation or application thereof by any Governmental Authority after the date of this Agreement or (c) compliance by any Lender or the L/C Issuer (or, for purposes of Section 3.04(b), by any lending office of such Lender or by such Lender’s or the L/C Issuer’s holding company, if any) with any request,

8

guideline or directive (whether or not having the force of law) of any Governmental Authority made or issued after the date of this Agreement.

Clean Down Period has the meaning set forth in Section 6.14.

Closing Date means May 20, 2002, the date upon which the Original Credit Agreement was executed by the Borrower, the MLP, the Original Lenders and the initial administrative agent.

Code means the Internal Revenue Code of 1986.

Collateral means all property and interests in property and proceeds thereof now owned or hereafter acquired by the MLP, the Borrower, and their respective Subsidiaries in or upon which a Lien now or hereafter exists in favor of the Lenders, or the Administrative Agent on behalf of the Lenders, including, but not limited to substantially all of the assets (including stock and other equity interests) of the MLP, the Borrower, and their respective Subsidiaries, whether under this Agreement, the Collateral Documents, or under any other document executed by any Borrower Affiliate and delivered to the Administrative Agent or the Lenders.

Collateral Documents means (a) each guaranty, pledge agreement, security agreement, mortgage, assignment, and all other security agreements, deeds of trust, mortgages, chattel mortgages, assignments, pledges, guaranties, financing statements, continuation statements, extension agreements and other similar agreements or instruments executed by the Borrower, the MLP, any Guarantor, or any of their respective Subsidiaries for the benefit of the Lenders now or hereafter delivered to the Lenders or the Administrative Agent pursuant to or in connection with the transactions contemplated hereby, and all financing statements (or comparable documents now or hereafter filed in accordance with the Uniform Commercial Code or comparable law) against the Borrower, the MLP, any Guarantor, or any of their respective Subsidiaries as debtor in favor of the Lenders or the Administrative Agent for the benefit of the Lenders as secured party to secure or guarantee the payment of any part of the Obligations or the performance of any other duties and obligations of Borrower under the Loan.  Documents, whenever made or delivered, and (b) any amendments, supplements, modifications, renewals, replacements, consolidations, substitutions, restatements, and extensions of any of the foregoing.

Commitmentmeans, as to each Lender, its obligation to make Loans to the Borrower pursuant to Sections 2.01 and 2.02 and  to purchase participations in L/C Obligations pursuant to Section 2.14, in an aggregate principal amount at any one time outstanding not to exceed the amount stated beside such Lender’s name on the most-recently amended Schedule 2.01 to this Agreement (which amount is subject to increase, reduction, or cancellation in accordance with the Loan Documents)(collectively, the Commitments of all the Lenders herein the “Aggregate Commitments”).

Company and Companies means, on any date of determination thereof, the MLP, the Borrower and each of their respective Subsidiaries.

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Compensation Period has the meaning set forth in Section 2.11(e)(ii).

Compliance Certificate means a certificate substantially in the form of Exhibit C.

Consolidated EBITDA means, for any period, for the MLP and its Subsidiaries on a consolidated basis, an amount equal to the sum of (a) Consolidated Net Income, (b) Consolidated Interest Charges, (c) the amount of taxes, based on or measured by income, used or included in the determination of such Consolidated Net Income, (d) the amount of depreciation, depletion, and amortization expense deducted in determining such Consolidated Net Income, and (e) other non-cash charges and expenses, including, without limitation, non-cash charges and expenses relating to Swap Contracts or resulting from accounting convention changes, of the MLP and its Subsidiaries on a consolidated basis, all determined in accordance with GAAP.

Consolidated Funded Debt means, as of any date of determination, for the MLP and its Subsidiaries on a consolidated basis, the sum of (a) the outstanding principal amount of all obligations and liabilities, whether current or long-term, for  borrowed money (including Obligations hereunder), (b) all reimbursement obligations relating to letters of credit, (c) Capital Leases, (d) Synthetic Lease Obligations, and (e) without duplication, all Guaranty Obligations with respect to Indebtedness of the type specified in subsections (a) through (d) above.

Consolidated Interest Charges means, for any period, for the MLP and its Subsidiaries on a consolidated basis, the sum of (a) all interest, premium payments, fees, charges and related expenses of the MLP and its Subsidiaries in connection with Indebtedness (including capitalized interest), in each case to the extent treated as interest in accordance with GAAP, and (b) the portion of rent expense of the MLP and its Subsidiaries with respect to such period under Capital Leases that is treated as interest in accordance with GAAP.

Consolidated Net Income means, for any period, for the MLP and its Subsidiaries on a consolidated basis, the net income or net loss of the MLP and its Subsidiaries from continuing operations, provided that there shall be excluded from such net income (to the extent otherwise included therein): (a) the income (or loss) of any entity other than a Subsidiary in which the MLP or any Subsidiary has an ownership interest, except to the extent that any such income has been actually received by the MLP or such Subsidiary in the form of cash dividends or similar cash distributions; (b) net extraordinary gains and losses (other than, in the case of losses, losses resulting from charges against net income to establish or increase reserves for potential environmental liabilities and reserves for exposure under rate cases), (c) any gains or losses attributable to non-cash write-ups or write-downs of assets, (d) proceeds of any insurance on property, plant or equipment other than business interruption insurance, (e) any gain or loss, net of taxes, on the sale, retirement or other disposition of assets (including the capital stock or other equity ownership of any other Person, but excluding the sale of inventories in the ordinary course of business), and (f) the cumulative effect of a change in accounting principles.

Contractual Obligation means, as to any Person, any provision of any security issued by such Person or of any agreement, instrument or other undertaking to which such Person is a party or by which it or any of its property is bound.

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Counterparty Consent means a consent from a counterparty to a pipeline transportation agreement consenting to the Liens granted by the Collateral Documents and containing such other terms as are satisfactory to the Administrative Agent.

Credit Extension means each of the following: (a) a Borrowing and (b) an L/C Credit Extension.

Debtor Relief Laws means the Bankruptcy Code of the United States of America, and all other liquidation, conservatorship, bankruptcy, assignment for the benefit of creditors, moratorium, rearrangement, receivership, insolvency, reorganization, or similar debtor relief Laws of the United States of America or other applicable jurisdictions from time to time in effect and affecting the rights of creditors generally.

Default means any event that, with the giving of any notice, the passage of time, or both, would be an Event of Default.

Default Rate means an interest rate equal to (a) the Base Rate plus (b) the Applicable Rate, if any, applicable to Base Rate Loans plus (c) 2% per annum; provided, however, that with respect to a Eurodollar Rate Loan, the Default Rate shall be an interest rate equal to the interest rate (including any Applicable Rate) otherwise applicable to such Loan plus 2% per annum, in each case to the fullest extent permitted by applicable Laws.

Disposition or Dispose means the sale, transfer, license or other disposition (including any sale and leaseback transaction) of any property (including stock, partnership and other equity interests) by any Person of property owned by such Person, including any sale, assignment, transfer or other disposal, with or without recourse, of any notes or accounts receivable or any rights and claims associated therewith.

Distribution Loan means a Loan which is made in whole or in part for the purpose of (i) paying a Quarterly Distribution, or (ii) reimbursing the purchase price of partnership units purchased under the MLP’s long-term incentive plan, or (iii) reimbursing the purchase or redemption price of equity interests in the Borrower or any Guarantor purchased or redeemed from their employees in accordance with Section 7.08(b)(iii).

Dollar and $ means lawful money of the United States of America.

Domestic Person means any corporation, general partnership, limited partnership, or limited liability company that is organized under the laws of the United States of America or any state thereof or the District of Columbia.

Eligible Assignee means (a) a Lender, (b) an Affiliate of a Lender, (c) an Approved Fund, (d) any institutional investor and (e) any other Person (other than a natural Person) approved by the Administrative Agent and, unless an Event of Default has occurred and is continuing or in connection with the settlement of a credit derivative transaction, the Borrower (each such approval not to be unreasonably withheld, conditioned or delayed); provided that

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notwithstanding the foregoing, “Eligible Assignee” shall not include the Borrower, the MLP, any MarkWest Party, or any of their respective Affiliates or Subsidiaries.

Environmental Law means any applicable Law that relates to (a) the condition or protection of air, groundwater, surface water, soil, or other environmental media, (b) the environment, including natural resources or any activity which affects the environment, (c) the regulation of any pollutants, contaminants, wastes, substances, and Hazardous Substances, including, without limitation, the Comprehensive Environmental Response, Compensation, and Liability Act (42 U.S.C. §9601 et seq.) (“CERCLA”), the Clean Air Act (42 U.S.C. § 7401 et seq.), the Federal Water Pollution Control Act, as amended by the Clean Water Act (33 U.S.C. § 1251 et seq.), the Federal Insecticide, Fungicide, and Rodenticide Act (7 U.S.C. § 136 et seq.), the Emergency Planning and Community Right to Know Act of 1986 (42 U.S.C. § 1100 1 et seq.), the Hazardous Materials Transportation Act (49 U.S.C. § 1801 et seq.), the National Environmental Policy Act of 1969 (42 U.S.C. § 4321 et seq.), the Oil Pollution Act (33 U.S.C. § 2701 et seq.), the Resource Conservation and Recovery Act (42 U.S.C. § 6901 et seq.), the Rivers and Harbors Act (33 U.S.C. §401 et seq.), the Safe Drinking Water Act (42 U.S.C. § 201 and § 300f et seq.), the Solid Waste Disposal Act, as amended by the Resource Conservation and Recovery Act of 1976 and the Hazardous and Solid Waste Amendments of 1984 (42 U.S.C. § 6901 et seq.), the Toxic Substances Control Act (15 U.S.C. § 2601 et seq.), and analogous state and local Laws, as any of the foregoing may have been and may be amended or supplemented from time to time, and any analogous enacted or adopted Law, or (d) the Release or threatened Release of Hazardous Substances.

Equitable Leases means the Lease Agreement executed by Equitable Production Company as lessor and MarkWest Energy Appalachia, L.L.C. as lessee, and the Equipment Lease Agreement and Pipeline Lease Agreement for Maytown to Institute Pipeline dated May 28, 1999, executed by Equitable Production Company as lessor and MarkWest Energy Appalachia, L.L.C. as lessee.

ERISA means the Employee Retirement Income Security Act of 1974 and any regulations issued pursuant thereto.

ERISA Affiliate means any trade or business (whether or not incorporated) under common control with the Borrower within the meaning of Section 414(b) or (c) of the Code (and Sections 414(m) and (o) of the Code for purposes of provisions of this Agreement relating to obligations imposed under Section 412 of the Code).

ERISA Event means (a) a Reportable Event with respect to a Pension Plan; (b) a withdrawal by the Borrower or any ERISA Affiliate from a Pension Plan subject to Section 4063 of ERISA during a plan year in which it was a substantial employer (as defined in Section 4001(a)(2) of ERISA) or a cessation of operations that is treated as such a withdrawal under Section 4062(e) of ERISA; (c) a complete or partial withdrawal by the Borrower or any ERISA Affiliate from a Multiemployer Plan or notification that a Multiemployer Plan is in reorganization; (d) the filing of a notice of intent to terminate, the treatment of a Plan amendment as a termination under Sections 4041 or 4041A of ERISA, or the commencement of proceedings

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by the PBGC to terminate a Pension Plan or Multiemployer Plan; (e) an event or condition which might reasonably be expected to constitute grounds under Section 4042 of ERISA for the termination of, or the appointment of a trustee to administer, any Pension Plan or Multiemployer Plan; or (f) the imposition of any liability under Title IV of ERISA, other than PBGC premiums due but not delinquent under Section 4007 of ERISA, upon the Borrower or any ERISA Affiliate.

Eurodollar Rate means for any Interest Period with respect to any Eurodollar Rate Loan:

(a)the rate per annum equal to the rate determined by the Administrative Agent to be the offered rate that appears on the page of the LIBOR I screen (or any successor thereto) that displays an average British Bankers Association Interest Settlement Rate for deposits in Dollars (for delivery on the first day of such Interest Period) with a term equivalent to such Interest Period, determined as of approximately 11:00 a.m. (London time) two Business Days prior to the first day of such Interest Period, or

(b)if the rate referenced in the preceding subsection (a) does not appear on such page or service or such page or service shall cease to be available, the rate per annum equal to the rate determined by the Administrative Agent to be the offered rate on such other page or other service that displays an average British Bankers Association Interest Settlement Rate for deposits in Dollars (for delivery on the first day of such Interest Period) with a term equivalent to such Interest Period, determined as of approximately 11:00 a.m. (London time) two Business Days prior to the first day of such Interest Period, or

(c)if the rates referenced in the preceding subsections (a) and (b) are not available, the rate per annum determined by the Administrative Agent as the rate of interest (rounded upward to the next 1/100th of 1%) at which deposits in Dollars for delivery on the first day of such Interest Period in same day funds in the approximate amount of the Eurodollar Rate Loan being made, continued or converted by the Administrative Agent and with a term equivalent to such interest Period would be offered by the Administrative Agent’s London Branch to major banks in the offshore Dollar market at their request at approximately 11:00 a.m. (London time) two Business Days prior to the first day of such Interest Period.

Eurodollar Rate Loan means a Loan that bears interest at a rate based on the Eurodollar Rate.

Event of Default means any of the events or circumstances specified in Article VIII.

Evergreen Letter of Credit has the meaning specified in Section 2.14(b)(iii).

Federal Funds Rate means, for any day, the rate per annum (rounded upwards to the nearest 1/100 of 1%) equal to the weighted average of the rates on overnight Federal funds

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transactions with members of the Federal Reserve System arranged by Federal funds brokers on such day, as published by the Federal Reserve Bank on the Business Day next succeeding such day; provided that (a) if such day is not a Business Day, the Federal Funds Rate for such day shall be such rate on such transactions on the next preceding Business Day as so published on the next succeeding Business Day, and (b) if no such rate is so published on such next succeeding Business Day, the Federal Funds Rate for such day shall be the average rate charged to the Administrative Agent on such day on such transactions as determined by the Administrative Agent.

Foreign Lender has the meaning specified in Section 10.15.

Fractionation, Storage and Loading Agreement (Siloam) means the Fractionation, Storage and Loading Agreement (Siloam) agreement between MarkWest Energy Appalachia, L.L.C. and MarkWest Parent dated as of the Conditions Effective Date.

Fund means any Person (other than a natural person) that is (or will be) engaged in making, purchasing, holding or otherwise investing in commercial loans and similar extensions of credit in the ordinary course of its business.

GAAP means generally accepted accounting principles set forth in the opinions and pronouncements of the Accounting Principles Board and the American Institute of Certified Public Accountants and statements and pronouncements of the Financial Accounting Standards Board or such other principles as may be approved by a significant segment of the accounting profession, that are applicable to the circumstances as of the date of determination, consistently applied.  If at any time any change in GAAP would affect the computation of any financial ratio or requirement set forth in any Loan Document, and either the Borrower or the Required Lenders shall so request, the Administrative Agent, the Lenders and the Borrower shall negotiate in good faith to amend such ratio or requirement to preserve the original intent thereof in light of such change in GAAP (subject to the approval of the Required Lenders); provided that, until so amended, (a) such ratio or requirement shall continue to be computed in accordance with GAAP prior to such change therein and (b) the Borrower shall provide to the Administrative Agent and the Lenders financial statements and other documents required under this Agreement or as reasonably requested hereunder setting forth a reconciliation between calculations of such ratio or requirement made before and after giving effect to such change in GAAP.

Gas Processing Agreement (Kenova, Boldman and Cobb Plants) means the Gas Processing Agreement (Kenova, Boldman and Cobb Plants) between MarkWest Energy Appalachia, L.L.C. and MarkWest Parent dated as of the Conditions Effective Date.

General Partner means MarkWest Energy GP, L.L.C., the general partner of the MLP.

Governmental Authority means any nation or government, any state or other political subdivision thereof, any agency, authority, instrumentality, regulatory body, court, administrative tribunal, central bank or other legal entity exercising executive, legislative, judicial, taxing, regulatory or administrative powers or functions of or pertaining to government.

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Guarantors means any Person, including the MLP and every present and future Subsidiary of Borrower and the MLP, which undertakes to be liable for all or any part of the Obligations by execution of a Guaranty, or otherwise.

Guaranty means a Guaranty now or hereafter made by any Guarantor in favor of the Administrative Agent on behalf of the Lenders, including the Amended and Restated MLP Guaranty substantially in the form of Exhibit E-1, and the Amended and Restated Subsidiary Guaranty substantially in the form of Exhibit E-2.

Guaranty Obligation means, as to any Person, (a) any obligation, contingent or otherwise, of such Person guaranteeing or having the economic effect of guaranteeing any Indebtedness or other payment obligation of another Person (the “primary obligor”) in any manner, whether directly or indirectly, and including any obligation of such Person, direct or indirect, (i) to purchase or pay (or advance or supply funds for the purchase or payment of) such Indebtedness or other payment obligation, (ii) to purchase or lease property, securities or services for the purpose of assuring the obligee in respect of such Indebtedness or other payment obligation of the payment of such Indebtedness or other payment obligation, (iii) to maintain working capital, equity capital or any other financial statement condition or liquidity of the primary obligor so as to enable the primary obligor to pay such Indebtedness or other payment obligation, or (iv) entered into for the purpose of assuring in any other manner the obligees in respect of such Indebtedness or other payment obligation of the payment thereof or to protect such obligees against loss in respect thereof (in whole or in part), or (b) any Lien on any assets of such Person securing any Indebtedness or other payment obligation of any other Person, whether or not such Indebtedness or other payment obligation is assumed by such Person; provided, however, that the term “Guaranty Obligation” shall not include endorsements of instruments for deposit or collection in the ordinary course of business.  The amount of any Guaranty Obligation shall be deemed to be the lesser of (a) an amount equal to the stated or determinable outstanding amount of the related primary obligation and (b) the maximum amount for which such guaranteeing Person may be liable pursuant to the terms of the instrument embodying such Guaranty Obligation, unless the outstanding amount of such primary obligation and the maximum amount for which such guaranteeing Person may be liable are not stated or determinable, in which case the amount of such Guaranty Obligation shall be the maximum reasonably anticipated liability in respect thereof as determined by the guaranteeing Person in good faith.

Hazardous Substance means any substance that poses a threat to, or is regulated to protect, human health, safety, public welfare, or the environment, including without limitation: (a) any “hazardous substance,” pollutant” or “contaminant,” and any “petroleum” or “natural gas liquids” as those terms are defined or used under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act of 1980, as amended ( 42 U.S.C. §§ 9601 et seq.) (“CERCLA”), (b) “solid waste” as defined by the federal Solid Waste Disposal Act (42 U. S.C. § § 6901 et seq.), (c) asbestos or a material containing asbestos, (d) any material that contains lead or lead-based paint, (e) any item or equipment that contains or is contaminated by polychlorinated biphenyls, (f) any radioactive material, (g) urea formaldehyde, (h) putrescible materials, (i) infectious materials, (j) toxic microorganisms, including mold, or (k) any substance

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the presence or Release of which requires reporting, investigation or remediation under any Environmental Law.

Hobbs Pipeline means that certain natural gas pipeline in Lea County, New Mexico, owned by MW New Mexico connected and transporting gas to Southwestern Public Service Company’s Cunningham Station, in Section 28, T18S, R36E, NMPM, and Maddox Station in Section 25, T18S, R36E, NMPM, Lea County, New Mexico.

Honor Date has the meaning set forth in Section 2.14(c)(i).

Indebtedness means, as to any Person at a particular time, all of the following:

(a)all obligations of such Person for borrowed money and all obligations of such Person evidenced by bonds, debentures, notes, loan agreements or other similar instruments;

(b)the face amount of all letters of credit (including standby and commercial), banker’s acceptances, Bank Guaranties, surety bonds, and similar instruments issued for the account of such Person, and, without duplication, all drafts drawn and unpaid thereunder;

(c)net obligations under any Swap Contract in an amount equal to (i) if such Swap Contract has been closed out, the termination value thereof, or (ii) if such Swap Contract has not been closed out, the mark-to-market value thereof determined on the basis of readily available quotations provided by any recognized dealer in such Swap Contract;

(d)whether or not so included as liabilities in accordance with GAAP, all obligations of such Person to pay the deferred purchase price of property or services, other than trade accounts payable in the ordinary course of business not overdue by more than 60 days, and indebtedness (excluding prepaid interest thereon) secured by a Lien on property owned or being purchased by such Person (including indebtedness arising under conditional sales or other title retention agreements), whether or not such indebtedness shall have been assumed by such Person or is limited in recourse;

(e)Capital Leases and Synthetic Lease Obligations; and

(f)all Guaranty Obligations of such Person in respect of any of the foregoing.

For all purposes hereof, the Indebtedness of any Person shall include the Indebtedness of any partnership or joint venture in which such Person is a general partner, unless such Indebtedness is expressly made non-recourse to such Person except for customary exceptions acceptable to the Required Lenders.  The amount of any Capital Lease or Synthetic Lease as of any date shall be deemed to be the amount of Attributable Indebtedness in respect thereof as of such date.  In addition, the determination of Indebtedness of the MLP, the Borrower and/or their

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Subsidiaries shall be made on a consolidated basis without taking into account any Indebtedness owed by any such Person to any other such Person.

Indemnified Liabilities has the meaning set forth in Section 10. 05.

Indemnitees has the meaning set forth in Section 10.05.

Insurance Deposit Account has the meaning set forth in Section 6.07(b).

Interest Coverage Ratio means, as of any date of determination, the ratio of (a) Consolidated EBITDA for the period of the four prior fiscal quarters ending on such date to (b) the sum of (i) Consolidated Interest Charges during such period and (ii) imputed interest charges on Synthetic Leases, of the MLP and its Subsidiaries during such period.

Interest Payment Date means, (a) as to any Loan other than a Base Rate Loan, the last day of each Interest Period applicable to such Loan; provided, however, that if any Interest Period for a Eurodollar Rate Loan exceeds three months, the respective dates that fall every three months after the beginning of such Interest Period shall also be Interest Payment Dates; and (b) as to any Base Rate Loan, the last Business Day of each March, June, September and December and, in the case of Revolver Loans, the Revolver Maturity Date and, in the case of Term Loans, the Term Loan Maturity Date.

Interest Period means, as to each Eurodollar Rate Loan, the period commencing on the date such Eurodollar Rate Loan is disbursed or converted to or continued as a Eurodollar Rate Loan and ending on the date one, two, three or six months thereafter, as selected by the Borrower in its Borrowing Notice; provided that:

(i)any Interest Period that would otherwise end on a day that is not a Business Day shall be extended to the next succeeding Business Day unless, in the case of a Eurodollar Rate Loan, such Business Day falls in another calendar month, in which case such Interest Period shall end on the next preceding Business Day;

(ii)any Interest Period pertaining to a Eurodollar Rate Loan that begins on the last Business Day of a calendar month (or on a day for which there is no numerically corresponding day in the calendar month at the end of such Interest Period) shall end on the last Business Day of the calendar month at the end of such Interest Period; and

(iii)no Interest Period shall extend beyond,  in the case of Revolver Loans, the Revolver Maturity Date and, in the case of Term Loans, the Term Loan Maturity Date.

Investment means, as to any Person, any acquisition or investment by such Person, whether by means of (a) the purchase or other acquisition of capital stock or other securities of another Person, (b) a loan, advance or capital contribution to, guaranty of debt of, or purchase or other acquisition of any other debt or equity participation or interest in, another Person, including any partnership or joint venture interest in such other Person, or (c) the purchase or other

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acquisition (in one transaction or a series of transactions) of assets of another Person that constitute a business unit. For purposes of covenant compliance, the amount of any Investment shall be the amount actually invested, without adjustment for subsequent increases or decreases in the value of such Investment, less all returns of principal or equity thereon, and shall, if made by the transfer or exchange of property other than cash be deemed to have been made in an amount equal to the fair market value of such property.

IRS means the United States Internal Revenue Service.

ISDA means the International Swaps and Derivatives Association, Inc.

Lake Whitney Pipeline means that certain natural gas pipeline lateral in Johnson, Hill and Bosque Counties, Texas, approximately 33 miles in length, connected and delivering gas to SEI Texas, LP’s electrical generation facility located in Bosque County, Texas.

Laws means, collectively, all applicable international, foreign, federal, state and local statutes, treaties, rules, regulations, ordinances, codes and administrative or judicial precedents or authorities, including the interpretation or administration thereof by any Governmental Authority charged with the enforcement, interpretation or administration thereof, and all applicable administrative orders, licenses, authorizations and permits of, any Governmental Authority.

L/C Advance means, with respect to each Lender, such Lender’s participation in any L/C Borrowing in accordance with its Pro Rata Share.

L/C Borrowing means an extension of credit resulting from a drawing under any Letter of Credit which has not been reimbursed on the date when made or refinanced as a Borrowing.

L/C Credit Extension means, with respect to any Letter of Credit, the issuance thereof or extension of the expiry date thereof, or the renewal or increase of the amount thereof.

L/C Issuer means Royal Bank of Canada in its capacity as issuer of Letters of Credit hereunder, or any successor issuer of Letters of Credit hereunder.

L/C Obligations means, as at any date of determination, the aggregate undrawn face amount of all outstanding Letters of Credit plus the aggregate of all Unreimbursed Amounts, including all L/C Borrowings.

Lender has the meaning specified in the introductory paragraph hereto and, as the context requires, includes the L/C Issuer.

Lender Hedging Agreement means a Swap Contract between a Company and a Lender or an Affiliate of a Lender.

Lending Office means, as to any Lender, the office or offices of such Lender set forth on its Administrative Details Form, or such other office or offices as a Lender may from time to time notify the Borrower and the Administrative Agent.

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Letter of Credit means any standby or commercial letter of credit issued hereunder.

Letter of Credit Application means an application and agreement for the issuance or amendment of a letter of credit in the form from time to time in use by the L/C Issuer.

Letter of Credit Expiration Date means the day that is five days prior to the Revolver Maturity Date (or, if such day is not a Business Day, the next preceding Business Day).

Letter of Credit Sublimit means an amount equal to the lesser of the Aggregate Revolver Commitments and $10,000,000.

Leverage Ratio means, for the MLP and its Subsidiaries on a consolidated basis, the ratio of (a) Consolidated Funded Debt as of the determination date to (b) Consolidated EBITDA for the period of the four fiscal quarters ending on such date, or if such date is not the last day of a fiscal quarter, ending on the last day of the fiscal quarter most recently ended.

Lien means any mortgage, pledge, hypothecation, assignment, deposit arrangement, encumbrance, lien (statutory or other), charge, or preference, priority or other security interest or preferential arrangement of any kind or nature whatsoever to secure or provide for payment of any obligation of any Person (including any conditional sale or other title retention agreement, any financing lease having substantially the same economic effect as any of the foregoing, and the filing of any financing statement under the Uniform Commercial Code or comparable Laws of any jurisdiction), including the interest of a purchaser of accounts receivable.

Limited Liability Company Agreement (Borrower) means the Amended and Restated Limited Liability Company Agreement of the Borrower.

Loan means an extension of credit by a Lender to the Borrower pursuant to Section 2.01 or Section 2.02.

Loan Documents means this Agreement, each Note, each of the Collateral Documents, the Agent/Arranger Fee Letter, each Borrowing Notice, each Compliance Certificate, the Guaranties, any Subordination Agreement, each Letter of Credit Application, and each other agreement, document or instrument delivered by the Borrower or any of its Subsidiaries from time to time in connection with this Agreement and the Notes.

Loan Party means each of the Borrower, each Guarantor, and each other entity that is an Affiliate of the Borrower that executes one or more Loan Documents.

MarkWest Parent means MarkWest Hydrocarbon, Inc., a Delaware corporation.

MarkWest Party means MarkWest Parent or any Subsidiary of MarkWest Parent, other than the General Partner, the MLP, the Borrower and its Subsidiaries.

Material Adverse Effect means (a) a material adverse change in, or a material adverse effect upon, the operations, business, properties or condition (financial or otherwise) or prospects

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of the Borrower and its Subsidiaries taken as a whole or the MLP and its Subsidiaries taken as a whole; (b) a material impairment of the ability of the Borrower, or any other Loan Party to perform their obligations under the Loan Documents to which it is a party; or (c) a material adverse effect upon the legality, validity, binding effect or enforceability against the Borrower or any other Loan Party of any Loan Documents.

Material Agreements means the following, which shall be satisfactory to the Administrative Agent and the Required Lenders: (a) the Omnibus Agreement, (b) the Gas Processing Agreement (Kenova, Boldman and Cobb Plants), the Pipeline Liquids Transportation Agreement, the Fractionation, Storage and Loading Agreement (Siloam), and the Natural Gas Liquids Purchase Agreement (Maytown), (c) Gas Processing Agreement (Maytown) dated May 28, 1989 between Equitable Production Company and Borrower as assignee of MarkWest Parent, (d) the ACET PSA, (e) the ACET Gas Processing Agreements, (f) the ACET Gas Gathering Agreements, (g) the ACET Assumed Guaranty, (h) the ACET Construction Agreement, (i) the ACET/NGPL Contracts and (j) any other contract material to the business of the MLP or the Borrower to which the Borrower or any Borrower Affiliate is a party.  “Material Agreement” means each of such Material Agreements.

Maximum Amount and Maximum Rate respectively mean, for each Lender, the maximum non-usurious amount and the maximum non-usurious rate of interest which, under applicable Law, such Lender is permitted to contract for, charge, take, reserve, or receive on the Obligations.

Midstream Businesses means gathering, transportation, fractionation, processing, marketing, and storage of natural gas, crude oil, natural gas liquids and other liquid and gaseous hydrocarbons and businesses closely related to the foregoing.

MLP Offering means after the Restatement Date, a private placement or a public sale of common or preferred units in the MLP (or any other sale to the public of partnership interests or other equity interests in the MLP including from debt convertible into equity in the MLP).

Mortgaged Properties means collectively all the Mortgaged Property as defined in the Mortgages and Mortgaged Property individual means any one of such Mortgaged Properties.

Mortgages means the mortgages, deeds of trust, or similar instruments executed by any of the Loan Parties in favor of Administrative Agent, for the benefit of the Lenders, and all supplements, assignments, amendments, and restatements thereto (or any agreement in substitution therefore, and “Mortgage” means each of such Mortgages).

Multiemployer Plan means any employee benefit plan of the type described in Section 4001(a)(3) of ERISA, to which the Borrower or any ERISA Affiliate makes or is obligated to make contributions, or during the preceding three calendar years, has made or been obligated to make contributions.

MW Blackhawk means MarkWest Blackhawk L.P., a Texas limited partnership.

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MW Energy means MarkWest Energy East Texas Gas Company, L.P., a Delaware limited partnership.

MW New Mexico means MarkWest New Mexico L.P., a Texas limited partnership,

MW Pinnacle means MarkWest Pinnacle L.P., a Texas limited partnership.

MW PNG means MarkWest PNG Utility L.P., a Texas limited partnership.

MW Texas PNG means MarkWest Texas PNG Utility L.P., a Texas limited partnership.

Natural Gas Liquids Purchase Agreement (Maytown) means the Natural Gas Liquids Purchase Agreement (Maytown) between MarkWest Energy Appalachia, L.L.C. and MarkWest Parent dated as of the Conditions Effective Date.

Net Cash Proceeds means  (a) with respect to any Disposition, cash (including any cash received by way of deferred payment as and when received) received by the MLP, the Borrower or any of its Subsidiaries in connection with and as consideration therefor, on or after the date of consummation of such transaction, after (i) deduction of Taxes payable in connection with or as a result of such transaction, and (ii) payment of all usual and customary brokerage commissions and all other reasonable fees and expenses related to such transaction (including, without limitation, reasonable attorneys’ fees and closing costs incurred in connection with such transaction), (b) with respect to any Refinancing Indebtedness, proceeds of such Refinancing Indebtedness after payment of all reasonable closing costs and transaction costs, (c) with respect to any MLP Offering, proceeds of such MLP Offering after payment of all reasonable closing costs and transaction costs.

Nonrenewal Notice Date has the meaning specified in Section 2.14(b)(iii).

Notes means collectively the Revolver Notes and the  Term Notes and “Note” means any one of such promissory notes issued hereunder.

Obligations means all advances to, and debts, liabilities, obligations, covenants and duties of, any Loan Party arising under any Loan Document, whether direct or indirect (including those acquired by assumption), absolute or contingent, due or to become due, now existing or hereafter arising and including interest that accrues after the commencement by or against any Loan Party of any proceeding under any Debtor Relief Laws naming such Person as the debtor in such proceeding. In addition, all references to the “Obligations” in the Collateral Documents and in Sections 2.13 and 10.09 of this Agreement shall, in addition to the foregoing, also include all present and future indebtedness, liabilities, and obligations (and all renewals and extensions thereof or any part thereof now or hereafter owed to any Lender or any Affiliate of a Lender arising pursuant to any Lender Hedging Agreement and all Bank Service Obligations.

Obligor means the Borrower or any other Person (other than the Administrative Agent, Syndication Agent or any Lender) obligated under any Loan Document.

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Omnibus Agreement means the Omnibus Agreement dated as of May 24, 2002, among the MLP, the Borrower, and MarkWest Parent.

Organization Documents means, (a) with respect to any corporation, the certificate or articles of incorporation and the bylaws; (b) with respect to any limited liability company, the certificate of formation and operating agreement; and (c) with respect to any partnership, joint venture, trust or other form of business entity, the partnership, joint venture or other applicable agreement of formation and any agreement, instrument, filing or notice with respect thereto filed in connection with its formation with the secretary of state or other department in the state of its formation, in each case as amended from time to time.

Other Taxes has the meaning specified in Section 3. 01(b).

Outstanding Amount on any date (i) with respect to Loans, means the aggregate principal amount thereof after giving effect to any Borrowings and prepayments or repayments occurring on such date, (ii) with respect to any L/C Obligations, the amount of such L/C Obligations on such date after giving effect to any L/C Credit Extension occurring on such date and any other changes in the aggregate amount of the L/C Obligations as of such date, including as a result of any reimbursements of outstanding unpaid drawings under any Letters of Credit or any reductions in the maximum amount available for drawing under Letters of Credit taking effect on such date, and (iii) for purposes of Section 2.11(d) with respect to Obligations under a Lender Hedging Agreement, means the amount then due and payable under such Lender Hedging Agreement.

Parent Change of Control means the acquisition by any Person, or two or more Persons acting in concert (other than John Fox and members of his family), of beneficial ownership (within the meaning of Rule 13d-3 of the Securities and Exchange Commission under the Securities Exchange Act of 1934) of 30% or more of the outstanding shares of voting stock of MarkWest Parent.

Participant has the meaning specified in Section 10.07(d).

Partnership Agreement (MLP) means the First Amended and Restated Agreement of Limited Partnership of the MLP.

PBGC means the Pension Benefit Guaranty Corporation.

Pension Plan means any “employee pension benefit plan” (as such term is defined in Section 3(2)(A) of ERISA), other than a Multiemployer Plan, that is subject to Title IV of ERISA and is sponsored or maintained by the Borrower or any ERISA Affiliate or to which the Borrower or any ERISA Affiliate contributes or has an obligation to contribute, or in the case of a multiple employer plan (as described in Section 4064(a) of ERISA) has made contributions at any time during the immediately preceding five plan years.

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Permitted Acquisition means the ACET Acquisition and any other Acquisition by the Borrower or a Subsidiary of the Borrower resulting in ownership of assets inside the United States, or of equity interests in a Domestic Person; provided, however, the purchase price for any Acquisition shall not, when aggregated with all other Permitted Acquisitions (excluding the ACET Acquisition) exceed $10,000,000; and provided, further that the following requirements have been satisfied:

(i)If such Acquisition results in the Borrower’s ownership of a Subsidiary, the Borrower shall have complied with the requirements of Sections 6.15 and 6.16 as of the date of such Acquisition;

(ii)With respect to Acquisitions involving acquisitions of an equity interest, such Acquisition shall have been approved or consented to by the board of directors or similar governing entity of the Person being acquired; and

(iii)As of the closing of such Acquisition no Default or Event of Default shall exist or occur as a result of, and after giving effect to, such Acquisition.

Permitted Liens means Liens permitted under Section 7.01 as described in such Section.

Person means any individual, trustee, corporation, general partnership, limited partnership, limited liability company, joint stock company, trust, unincorporated organization, bank, business association, firm, joint venture or Governmental Authority.

Pipeline Liquids Transportation Agreement means the Pipeline Liquids Transportation Agreement between MarkWest Energy Appalachia, L.L.C. and MarkWest Parent dated as of the Conditions Effective Date.

Plan means any “employee benefit plan” (as such term is defined in Section 3(3) of ERISA) established by the Borrower or any ERISA Affiliate.

Pro Rata Share means, at any date of determination, for any Lender, the percentage (carried out to the ninth decimal place) that its Aggregate Commitment bears to the Aggregate Commitments.

Purchase Price means, with respect to any Acquisition, all direct, indirect, and deferred cash and non-cash payments made to or for the benefit of the Person being acquired (or whose assets are being acquired), its shareholders, officers, directors, employees, or Affiliates in connection with such Acquisition, including, without limitation, the amount of any Indebtedness being assumed in connection with such Acquisition and (subject to the limitations on Indebtedness hereunder) seller financing, payments under non-competition or consulting agreements entered into in connection with such Acquisition and similar agreements, all non-cash consideration and the value of any stock, options, or warrants or other rights to acquire stock issued as part of the consideration in such transaction.

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Quarterly Distributions means with respect to the Borrower, the distributions by the Borrower of Available Cash (as defined in the Limited Liability Company Agreement (Borrower)) or with respect to MLP, the distributions by the MLP of Available Cash (as defined in the Partnership Agreement (MLP)).

Refinancing Indebtedness means any Indebtedness of any Company including, without limitation, Subordinated Indebtedness, incurred to refinance all or any portion of the Loans.

Register has the meaning set forth in Section 10.07(c).

Related Parties means, with respect to any specified Person, such Person’s Affiliates and the respective directors, officers, employees, agents and advisors of such Person and such Person’s Affiliate.

Release means any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, disposal, deposit, dispersal, migrating, or other movement into the air, ground, or surface water, or soil.

Reportable Event means any of the events set forth in Section 4043(c) of ERISA, other than events for which the 30 day notice period has been waived.

Request for Credit Extension means (a) with respect to a Borrowing, conversion or continuation of Loans, a Borrowing Notice, and (b) with respect to an L/C Extension, a Letter of Credit Application.

Required Lenders means (a) on any date of determination on and after the Restatement Date and prior to the date of the initial Borrowing under this Agreement, those Lenders holding more than 66 2/3% of the Aggregate Commitments, (b) on any date of determination on and after the date of the initial Borrowing under this Agreement and prior to the Revolver Maturity Date, those Lenders holding more than 66 2/3% of the Outstanding Amount of Loans.

Responsible Officer means the president, chief executive officer, executive vice president, senior vice president, vice president, chief financial officer, controller, treasurer or assistant treasurer of a Person.  Any document delivered hereunder that is signed by a Responsible Officer of a Loan Party shall be conclusively presumed to have been authorized by all necessary corporate, partnership, limited liability company, and/or other action on the part of such Loan Party and such Responsible Officer shall be conclusively presumed to have acted on behalf of such Loan Party.

Restatement Conditions Effective Date means the first date all the conditions precedent in Section 4.01 and Section 4.02 are satisfied or waived (or, in the case of Sections 4.01(g) and (h), waived by the Person entitled to receive the applicable payment).

Restatement Date means the date upon which this Agreement has been executed by the Borrower, the MLP, the Lenders and the Administrative Agent.

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Restricted Payment by a Person means any dividend or other distribution (whether in cash, securities or other property) with respect to any equity interest in such Person, or any payment (whether in cash, securities or other property), including any sinking fund or similar deposit on account of the purchase, redemption, retirement, acquisition, cancellation or termination of any such equity interest or of any option, warrant or other right to acquire any such equity interest.

Revolver Commitment means, as to each Lender, its obligation to make Loans to the Borrower pursuant to Section 2.01 and  to purchase participations in L/C Obligations pursuant to Section 2.14, in an aggregate principal amount at any one time outstanding not to exceed the amount stated beside such Lender’s name on the most-recently amended Schedule 2.01 to this Agreement (which amount is subject to increase, reduction, or cancellation in accordance with the Loan Documents) and collectively for all Lenders an amount (subject to reduction or cancellation as herein provided) equal to $265,000,000 (collectively, the Revolver Commitments of all the Lenders herein the “Aggregate Revolver Commitments”).

Revolver Facility means the credit facility as described in and subject to the limitations set forth in Section 2.01.

Revolver Loan has the meaning set forth in Section 2.01.

Revolver Maturity Date means (a) May 31, 2005, or (b) such earlier effective date of any other termination, cancellation, or acceleration of all Aggregate Revolver Commitments under this Agreement.

Revolver Note means a promissory note of Borrower in substantially the form of Exhibit B-1, evidencing the obligation of Borrower to repay the Revolver Loans and all renewals and extensions of all or any part thereof.

Revolver Principal Debt means, on any date of determination, the aggregate unpaid principal balance of all Loans under the Revolver Facility.

Rights means rights, remedies, powers, privileges, and benefits.

Rio Nogales Pipelines means those two natural gas pipeline laterals in Guadalupe and Caldwell Counties, Texas, one approximately twenty-two (22) miles in length and the other approximately seven (7) miles in length, connected and transporting gas to Rio Nogales Power Project, LP’s electrical generation facility located in or near the city of Seguin, Guadalupe County, Texas.

Security Agreements means, collectively, the security agreements, or similar instruments, executed by any of the Loan Parties in favor of the Administrative Agent for the benefit of the Lenders, and all supplements, assignments, amendments, and restatements thereto (or any agreement in substitution therefore), and “Security Agreement” means each of such Security Agreements.

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Subsidiary of a Person means a corporation, partnership, joint venture, limited liability company or other business entity of which a majority of the shares of securities or other interests having ordinary voting power for the election of directors or other governing body (other than securities or interests having such power only by reason of the happening of a contingency) are at the time beneficially owned, or the management of which is otherwise controlled, directly, or indirectly through one or more intermediaries, or both, by such Person.  Unless otherwise specified, all references herein to a “Subsidiary” or to “Subsidiaries” shall refer to a Subsidiary or Subsidiaries of the Borrower.

Subordinated Indebtedness has the meaning set forth in Section 7.04(c).

Subordination Agreement has the meaning set forth in Section 7.04(c).

Swap Contract means (a) any and all rate swap transactions, basis swaps, credit derivative transactions, forward rate transactions, commodity swaps, commodity options, forward commodity contracts, equity or equity index swaps or options, bond or bond price or bond index swaps or options or forward bond or forward bond price or forward bond index transactions, interest rate options, forward foreign exchange transactions, cap transactions, floor transactions, collar transactions, currency swap transactions, cross-currency rate swap transactions, currency options, spot contracts, or any other similar transactions or any combination of any of the foregoing (including any options to enter into any of the foregoing), whether or not any such transaction is governed by or subject to any master agreement, and (b) any and all transactions of any kind, and the related confirmations, which are subject to the terms and conditions of, or governed by, any form of master agreement published by the International Swaps and Derivatives Association, Inc., any International Foreign Exchange Master Agreement, or any other master agreement (any such master agreement, together with any related schedules, a “Master Agreement”), including any such obligations or liabilities under any Master Agreement.

Swap Termination Value means, in respect of any one or more Swap Contracts, after taking into account the effect of any legally enforceable netting agreement relating to such Swap Contracts, (a) for any date on or after the date such Swap Contracts have been closed out and termination value(s) determined in accordance therewith, such termination value(s), and (b) for any date prior to the date referenced in clause (a) the amount(s) determined as the mark-to-market value(s) for such Swap Contracts, as determined based upon one or more mid-market or other readily available quotations provided by any recognized dealer in such Swap Contracts (which may include any Lender).

Syndication Agent means Fortis Capital Corp. in its capacity as syndication agent under this Agreement, or any successor syndication agent.

Synthetic Lease Obligation means the monetary obligation of a Person under (a) a so-called synthetic or tax retention lease, or (b) an agreement for the use or possession of property creating obligations that do not appear on the balance sheet of such Person but which are depreciated for tax purposes by such Person.  The amount of any Synthetic Lease Obligation

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as of any date shall be deemed to be the amount of Attributable Indebtedness in respect thereof as of such date.

Taxes has the meaning set forth in Section 3.01.

Term Loan Commitment means, as to each Lender, its obligation to make Loans to the Borrower pursuant to Section 2.02 in an aggregate principal amount at any one time outstanding not to exceed the amount stated beside such Lender’s name on the most-recently amended Schedule 2.01 to this Agreement (which amount is subject to increase, reduction, or cancellation in accordance with the Loan Documents) and collectively for all Lenders an amount (subject to reduction or cancellation as herein provided) equal to $50,000,000 (collectively, the  Term Loan Commitments of all the Lenders herein the “Aggregate  Term Loan Commitments”).

Term Loan Facility means the credit facility as described in and subject to the limitations set forth in Section 2.02.

Term Loan Maturity Date means (a) December 31, 2004, or (b) such earlier effective date of any other termination, cancellation, or acceleration of all Aggregate Term Loan Commitments under this Agreement.

Term Loan Principal Debt means, on any date of determination, the aggregate unpaid principal balance of all Loans under the  Term Loan Facility.

Term Loans means an extension of credit by a Lender to the Borrower pursuant to Section 2.02.

Term Note means a promissory note of the Borrower in substantially the form of Exhibit B-2, evidencing the obligation of Borrower to repay the  Term Loans and all renewals and extensions of all or any part thereof

Type means, with respect to a Loan, its character as a Base Rate Loan or a Eurodollar Rate Loan.

Unfunded Pension Liability means the excess of a Pension Plan’s benefit liabilities under Section 4001(a)(16) of ERISA, over the current value of that Pension Plan’s assets, determined in accordance with the assumptions used for funding the Pension Plan pursuant to Section 412 of the Code for the applicable plan year.

Unreimbursed Amount has the meaning set forth in Section 2.14(c)(i).

Voting Stock means the capital stock (or equivalent thereof) of any class or kind, of a Person, the holders of which are entitled to vote for the election of directors, managers, or other voting members of the governing body of such Person.

Wholly-Owned when used in connection with a Person means any Subsidiary of such Person of which all of the issued and outstanding equity interests (except shares required as

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directors’ qualifying shares) shall be owned by such Person or one or more of its Wholly-Owned Subsidiaries.

1.02Other Interpretive Provisions.

(a)The meanings of defined terms are equally applicable to the singular and plural forms of the defined terms.

(b)(i)The words “herein” and “hereunder” and words of similar import when used in any Loan Document shall refer to such Loan Document as a whole and not to any particular provision thereof.

(ii)Unless otherwise specified herein, Article, Section, Exhibit and Schedule references are to this Agreement.

(iii)The term “including” is by way of example and not limitation.

(iv)The term “documents” includes any and all instruments, documents, agreements, certificates, notices, reports, financial statements and other writings, however evidenced.

(c)In the computation of periods of time from a specified date to a later specified date, the word “from” means “from and including;” the words “to” and “until” each mean “to but excluding;” and the word “through” means “to and including.”

(d)Section headings herein and the other Loan Documents are included for convenience of reference only and shall not affect the interpretation of this Agreement or any other Loan Document.

1.03Accounting Terms.

All accounting terms not specifically or completely defined herein shall be construed in conformity with, and all financial data required to be submitted pursuant to this Agreement shall be prepared in conformity with, GAAP applied on a consistent basis, as in effect from time to time, applied in a manner consistent with that used in preparing the audited financial statements, except as otherwise specifically prescribed herein.

1.04Rounding.  Any financial ratios required to be maintained by the Borrower pursuant to this Agreement shall be calculated by dividing the appropriate component by the other component, carrying the result to one place more than the number of places by which such ratio is expressed herein and rounding the result up or down to the nearest number (with a rounding-up if there is no nearest number).

1.05References to Agreements and Laws.  Unless otherwise expressly provided herein, (a) references to agreements (including the Loan Documents) and other contractual instruments shall be deemed to include all subsequent amendments, restatements, extensions,

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supplements and other modifications thereto, but only to the extent that such amendments, restatements, extensions, supplements and other modifications are not prohibited by any Loan Document; and (b) references to any Law shall include all statutory and regulatory provisions consolidating, amending, replacing, supplementing or interpreting such Law.

ARTICLE II.
THE COMMITMENTS AND BORROWINGS

2.01Revolver Loans.  Subject to and in reliance upon the terms, conditions, representations, and warranties in the Loan Documents, each Lender severally, but not jointly, agrees to make revolving loans (each such Loan a “Revolver Loan”) to Borrower from time to time on any Business Day during the period from the Restatement Conditions Effective Date to the Revolver Maturity Date, in an aggregate amount not to exceed at any time outstanding the amount of such Lender’s Pro Rata Share of one or more Borrowings not to exceed, when aggregated with the Outstanding Amount of the L/C Obligations, such Lender’s Revolver Commitment; provided, however funding of Revolver Loans to finance the ACET Acquisition is limited to the amount described in Section 6.12(b).   Such Borrowings may be repaid and reborrowed from time to time in accordance with the terms and provisions of the Loan Documents; provided that, each such Borrowing must occur on a Business Day and no later than the Business Day immediately preceding the Revolver Maturity Date.

2.02Term Loans.  Subject to and in reliance upon the terms, conditions, representations, and warranties in the Loan Documents, each Lender severally, but not jointly, agrees to make  Term Loans to Borrower in a single disbursement on the Restatement Conditions Effective Date (but in no event or under any circumstances later than August 31, 2004) in aggregate amount not to exceed at any time outstanding the amount of such Lender’s Pro Rata Share of the  Term Loan Commitment.  If all or a portion of the  Term Loan Principal Debt is paid or prepaid, then the amount so paid or prepaid may not be reborrowed. Any portion of the Term Loan Commitment that remains undisbursed after the initial disbursement under the  Term Loan Facility shall be reduced to zero and cancelled on the date of such initial disbursement.

2.03Borrowings, Conversions and Continuations of Loans.

(a)Each Borrowing, each conversion of Loans from one Type to the other, and each continuation of Loans as the same Type shall be made upon the Borrower’s irrevocable notice to the Administrative Agent, which may be given by telephone.  Each such notice must be received by the Administrative Agent not later than 11:00 a.m., New York time, (i) three Business Days prior to the requested date of any Borrowing of, conversion to or continuation of Eurodollar Rate Loans, and (ii) one Business Day prior to the conversion of Eurodollar Rate Loans to Base Rate Loans, or the requested date of any Borrowing of Base Rate Loans.  Each such telephonic notice must be confirmed promptly by delivery to the Administrative Agent of a written Borrowing Notice, appropriately completed and signed by an authorized officer of the Borrower.  Each Borrowing of, conversion to or continuation of Eurodollar Rate Loans shall be in a principal amount of $500,000 or a whole multiple of $500,000 in excess thereof.  Each Borrowing of or conversion to Base Rate Loans shall be in a principal amount of $500,000 or a whole multiple of

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$100,000 in excess thereof.  Each Borrowing Notice (whether telephonic or written) shall specify (i) whether the Borrowing, conversion or continuation (as applicable) is under the Revolver Facility or the  Term Loan Facility, (ii)whether the Borrower is requesting a Borrowing, a conversion of Loans from one Type to the other, or a continuation of Loans as the same Type, (iii) the requested date of the Borrowing, conversion or continuation, as the case may be (which shall be a Business Day), (iv) the principal amount of Loans to be borrowed, converted or continued, (v) the Type of Loans to be borrowed or to which existing Loans are to be converted, and (vi) if applicable, the duration of the Interest Period with respect thereto.  If the Borrower fails to specify a Type of Loan in a Borrowing Notice or if the Borrower fails to give a timely notice requesting a conversion or continuation, then the applicable Loans shall be made or continued as, or converted to, Base Rate Loans.  Any such automatic conversion to Base Rate Loans shall be effective as of the last day of the Interest Period then in effect with respect to the applicable Eurodollar Rate Loans.  If the Borrower requests a Borrowing of, conversion to, or continuation of Eurodollar Rate Loans in any such Borrowing Notice, but fails to specify an Interest Period, it will be deemed to have specified an Interest Period of one month.

(b)Following receipt of a Borrowing Notice, the Administrative Agent shall promptly notify each Lender of its Pro Rata Share of the applicable Loans, and if no timely notice of a conversion or continuation is provided by the Borrower, the Administrative Agent shall notify each Lender of the details of any automatic conversion to Base Rate Loans described in the preceding subsection.  In the case of a Borrowing, each Lender shall make the amount of its Loan available to the Administrative Agent in immediately available funds at the Administrative Agent’s Office not later than 11:00 a.m., New York time, on the Business Day specified in the applicable Borrowing Notice.  Upon satisfaction of the applicable conditions set forth in Section 4.01 and Section 4.02, the Administrative Agent shall make all funds so received available to the Borrower in like funds as received by the Administrative Agent either by (i) crediting the account of the Borrower on the books of the Administrative Agent with the amount of such funds or (ii) wire transfer of such funds, in each case in accordance with instructions provided to the Administrative Agent by the Borrower; provided, however, that if, on the date of the Borrowing there are L/C Borrowings outstanding, then the proceeds of such Borrowing shall be applied, first, to the payment in full of any such L/C Borrowings, and second, to the Borrower as provided above.

(c)Except as otherwise provided herein, a Eurodollar Rate Loan may be continued or converted only on the last day of the Interest Period for such Eurodollar Rate Loan.  During the existence of a Default or Event of Default, no Loans may be requested as, converted to or continued as Eurodollar Rate Loans without the consent of the Required Lenders, and the Required Lenders may demand that any or all of the then outstanding Eurodollar Rate Loans be converted immediately to Base Rate Loans.

(d)The Administrative Agent shall promptly notify the Borrower and the Lenders of the interest rate applicable to any Eurodollar Rate Loan upon determination of such interest rate.  The determination of the Eurodollar Rate by the Administrative Agent shall be conclusive in the absence of manifest error.

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(e)After giving effect to all Borrowings, all conversions of Loans from one Type to the other, and all continuations of Loans as the same Type, there shall not be more than six (6) Interest Periods in effect at any given time with respect to Loans.

2.04Prepayments.

(a)Optional Prepayments.  The Borrower may, upon notice to the Administrative Agent, at any time or from time to time voluntarily prepay in whole or in part Loans outstanding under the Revolver Facility and/or the  Term Loan Principal Debt without premium or penalty; provided that (i) such notice must be received by the Administrative Agent not later than 11:00 a.m., New York time, (A) three Business Days prior to any date of prepayment of Eurodollar Rate Loans, and (B) the date of prepayment of Base Rate Loans; (ii) any prepayment of Eurodollar Rate Loans shall be in a principal amount of $500,000 or a whole multiple of $500,000 in excess thereof; and (iii) any prepayment of Base Rate Loans shall be in a principal amount of $500,000 or a whole multiple of $100,000 in excess thereof.  Each such notice shall specify the date and amount of such prepayment and the Type(s) of Loans to be prepaid.  The Administrative Agent will promptly notify each Lender of its receipt of each such notice, and of such Lender’s Pro Rata Share of such prepayment.  If such notice is given by the Borrower, the Borrower shall make such prepayment and the payment amount specified in such notice shall be due and payable on the date specified therein.  Any prepayment of a Eurodollar Rate Loan shall be accompanied by all accrued interest thereon, together with any additional amounts required pursuant to Section 3.05.  Each such prepayment shall be applied to the Loans of the Lenders in accordance with their respective Pro Rata Shares.

Unless a Default or Event of Default has occurred and is continuing or would arise as a result thereof, any payment or prepayment of the Revolver Loans may be reborrowed by Borrower, subject to the terms and conditions hereof; but in no event following a payment or prepayment of  Term Loans may any amount so paid or prepaid be reborrowed.

(b)Mandatory Prepayments from Net Cash Proceeds.

(i)If any Net Cash Proceeds are received by a Company from any Disposition (including any deferred purchase price therefor and including sales of stock or other equity interests of Subsidiaries but excluding any Disposition permitted by Section 7.07(a) or (b)), the Aggregate Commitments shall be permanently reduced, and the Loans shall be prepaid, immediately upon receipt of such Net Cash Proceeds, in an amount equal to the amount of Net Cash Proceeds received from such Disposition.

(ii)If any Net Cash Proceeds are received by the MLP from an MLP Offering, the Loans shall be prepaid by the Borrower immediately after receipt of such Net Cash Proceeds by the MLP, in an amount equal to the amount of Net Cash Proceeds received by the MLP from such MLP Offering.

(iii)If any Net Cash Proceeds are received from the issuance or incurrence of Refinancing Indebtedness by a Company, the Aggregate Commitments shall be

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permanently reduced, and the Loans shall be prepaid, immediately upon receipt of such Net Cash Proceeds, in an amount equal to the amount of Net Cash Proceeds received from such Refinancing Indebtedness.

(iv)The prepayments and commitment reductions provided for in this Section 2.04(b) shall be applied as follows, unless a Default or Event of Default has occurred and is continuing or would arise as a result thereof (whereupon the provisions of Section 2.11(d) shall apply): (A) first, to repay any outstanding fees, costs of expenses owing to Administrative Agent or any Lender, including Attorney Costs, (B) second, as a payment of all Unreimbursed Amounts then outstanding, until paid in full, (C), third, as a repayment of the Term Loan Principal Debt, until paid in full, with a corresponding reduction in the Aggregate Term Loan Commitments and (D) fourth, as a repayment of the Revolver Principal Debt, until paid in full, with a corresponding reduction in the Aggregate Revolver Commitments, or if a Default or Event of Default exists, as specified by the Agents or the Required Banks.

(c)Mandatory Payments/Reductions.  If for any reason the Outstanding Amount of all Loans and L/C Obligations at any time exceeds the Aggregate Commitments then in effect, the Borrower shall immediately prepay Loans and/or Cash Collateralize the L/C Obligations in an aggregate amount equal to such excess.

(d)Prepayments: Interest/Consequential Loss.  All prepayments under this Section 2.04 shall be made together with accrued interest to the date of such prepayment on the principal amount prepaid and any amounts due under Section 3.05.

2.05Reduction or Termination of Commitments.  (a) The Borrower may, upon notice to the Administrative Agent, terminate the Aggregate Commitments or (prior to funding the Term Loan) permanently reduce the Term Loan Commitment or permanently reduce the Revolver Commitment to an amount not less than the sum of the Outstanding Amount of the then existing (i) Revolver Principal Debt and (ii) L/C Obligations; provided that (i) any such notice shall be received by the Administrative Agent not later than 11:00 a.m., five Business Days prior to the date of termination or reduction, and (ii) any such partial reduction shall be in an aggregate amount of $3,000,000 or any whole multiple of $500,000 in excess thereof.   The Administrative Agent shall promptly notify the Lenders of any such notice of reduction or termination.  Once reduced in accordance with this Section, the Revolver Commitment or  Term Loan Commitment, as the case may be,  may not be increased.  Any reduction of the Revolver Commitment shall be applied to the Revolver Commitment of each Lender according to its Pro Rata Share, and any reduction of the  Term Loan Commitment shall be applied to the  Term Loan Commitment of each Lender according to its Pro Rata Share.  All commitment fees on the portion of the Aggregate Revolver Commitment so terminated which have accrued to the effective date of any termination of the Aggregate Revolver Commitments shall at Administrative Agent’s option either be paid on the effective date of such termination or on the date when such commitment fee would otherwise be due.

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(b)The Aggregate Revolver Commitments shall be automatically reduced, dollar for dollar, by any downward purchase price adjustment received by or for the benefit of MW Energy in connection with the ACET Acquisition pursuant to Section 3.1 of the ACET PSA (excluding purchase price adjustments pursuant to Section 3.2 of the ACET PSA) and Borrower agrees to notify Administrative Agent of any such adjustment to the ACET Acquisition purchase price promptly and in any event prior to funding the initial Loan under this Agreement.

2.06Repayment of Loans.  (a)  The Borrower shall repay to the Lenders on the Revolver Maturity Date the aggregate Revolver Principal Debt outstanding on such date.

(b)The Borrower shall repay to the Lenders on the  Term Loan Maturity Date the aggregate  Term Loan Principal Debt outstanding on such date.

2.07Interest.   (a)  Subject to the provisions of subsection (b) below, (i) each Eurodollar Rate Loan shall bear interest on the outstanding principal amount thereof for each Interest Period at a rate per annum equal to the Eurodollar Rate for such Interest Period plus the Applicable Rate and (ii) each Base Rate Loan shall bear interest on the outstanding principal amount thereof from the applicable borrowing date at a rate per annum equal to the Base Rate plus the Applicable Rate.

(b)While any Event of Default exists or after acceleration (i) the Borrower shall pay interest on the principal amount of all outstanding Obligations at a fluctuating interest rate per annum at all times equal to the Default Rate to the fullest extent permitted by applicable Law, and (ii) accrued and unpaid interest on past due amounts (including interest on past due interest) shall be due and payable upon demand.

(c)Interest on each Loan shall be due and payable in arrears on each Interest Payment Date applicable thereto and at such other times as may be specified herein.  Interest hereunder shall be due and payable in accordance with the terms hereof before and after judgment, and before and after the commencement of any proceeding under any Debtor Relief Law.

(d)If the designated rate applicable to any Borrowing exceeds the Maximum Rate, the rate of interest on such Borrowing shall be limited to the Maximum Rate, but any subsequent reductions in such designated rate shall not reduce the rate of interest thereon below the Maximum Rate until the total amount of interest accrued thereon equals the amount of interest which would have accrued thereon if such designated rate had at all times been in effect.  In the event that at maturity (stated or by acceleration), or at final payment of the Outstanding Amount of any Loans or L/C Obligations, the total amount of interest paid or accrued is less than the amount of interest which would have accrued if such designated rates had at all times been in effect, then, at such time and to the extent permitted by Law, the Borrower shall pay an amount equal to the difference between (a) the lesser of the amount of interest which would have accrued if such designated rates had at all times been in effect and the amount of interest which would have accrued if the Maximum Rate had at all times been in effect, and (b) the amount of interest actually paid or accrued on such Outstanding Amount.

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2.08Fees.   (a)  Commitment Fee.  The Borrower shall pay to the Administrative Agent for the account of each Lender in accordance with its Pro Rata Share, a commitment fee equal to the Applicable Rate times the actual daily amount by which the Aggregate Revolver Commitments (subject to reduction pursuant to Section 2.05(b)) exceed the sum of (i) the Outstanding Amount of Revolver Loans plus (ii) the Outstanding Amount of L/C Obligations.  The commitment fee shall accrue at all times from the Restatement Date until the Revolver Maturity Date and shall be due and payable quarterly in arrears on the last Business Day of each March, June, September and December, commencing with the first such date to occur after the Restatement Date, and on the Revolver Maturity Date.  The commitment fee shall be calculated quarterly in arrears.  The commitment fee shall accrue at all times, including at any time during which one or more of the conditions in Article IV is not met.

(b)Arranger’s and Administrative Agent’s Fees.   On the Restatement Date, the Borrower shall pay certain fees to the Arranger and Administrative Agent to be shared between them and the Borrower shall pay certain fees to the Administrative Agent for the Administrative Agent’s own account as an administrative agency fee, in the amounts and at the times specified in the letter agreement dated July 15, 2004 (the “Agent/Arranger Fee Letter”), between the Borrower, the Arranger and the Administrative Agent.  Such fees shall be fully earned when paid and shall be nonrefundable for any reason whatsoever.  Additionally, Borrower shall pay to the Administrative Agent for the Administrative Agent’s own account the fees in the amounts and on the dates specified in the Agent/Arranger Fee Letter.

2.09Computation of Interest and Fees.  Computation of interest on Base Rate Loans shall be calculated on the basis of a year of 365 or 366 days, as the case may be, and the actual number of days elapsed.  Computation of all other types of interest and all fees shall be calculated on the basis of a year of 360 days and the actual number of days elapsed, which results in a higher yield to the payee thereof than a method based on a year of 365 or 366 days.  Interest shall accrue on each Loan for the day on which the Loan is made, and shall not accrue on a Loan, or any portion thereof, for the day on which the Loan or such portion is paid; provided that any Loan that is repaid on the same day on which it is made shall bear interest for one day.

2.10Evidence of Debt.   (a)  The Loans made by each Lender shall be evidenced by one or more accounts or records maintained by such Lender and by the Administrative Agent in the ordinary course of business.  The accounts or records maintained by the Administrative Agent and each Lender shall be conclusive absent manifest error of the amount of the Loans made by the Lenders to the Borrower and the interest and payments thereon.  Any failure so to record or any error in doing so shall not, however, limit or otherwise affect the obligation of the Borrower hereunder to pay any amount owing with respect to the Loans or the L/C Obligations.  In the event of any conflict between the accounts and records maintained by any Lender and the accounts and records of the Administrative Agent in respect of such matters, the accounts and records of such Lender shall control.  Upon the request of any Lender made through the Administrative Agent, such Lender’s Loans may be evidenced by one or more Notes.  Each Lender may attach schedules to its Note(s) and endorse thereon the date, Type (if applicable), amount and maturity of the applicable Loans and payments with respect thereto.

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(b)In addition to the accounts and records referred to in subsection (a), each Lender and the Administrative Agent shall maintain in accordance with its usual practice accounts or records evidencing the purchases and sales by such Lender of participations in Letters of Credit.  In the event of any conflict between the accounts and records maintained by the Administrative Agent and the accounts and records of any Lender in respect of such matters, the accounts and records of the Administrative Agent shall control.

2.11Payments Generally.  (a) All payments to be made by the Borrower shall be made without condition or deduction for any counterclaim, defense, recoupment or setoff.  Except as otherwise expressly provided herein, all payments by the Borrower hereunder shall be made to the Administrative Agent, for the account of the respective Lenders to which such payment is owed, at the Administrative Agent’s Office in Dollars and in immediately available funds not later than 11:00 a.m., New York time, on the date specified herein.  The Administrative Agent will promptly distribute to each Lender its Pro Rata Share (or other applicable share as provided herein) of such payment in like funds as received by wire transfer to such Lender’s Lending Office.  All payments received by the Administrative Agent after 11:00 a.m., New York time, shall be deemed received on the next succeeding Business Day and any applicable interest or fee shall continue to accrue.

(b)Subject to the definition of “Interest Period,” if any payment to be made by the Borrower shall come due on a day other than a Business Day, payment shall be made on the next following Business Day, and such extension of time shall be reflected in computing interest or fees, as the case may be.

(c)If no Default or Event of Default exists and if no order of application is otherwise specified in the Loan Documents, payments and prepayments of the Obligations shall be applied first to fees, second to accrued interest then due and payable on the Outstanding Amount of Loans and L/C Obligations, and then to the remaining Obligations in the order and manner as Borrower may direct.

(d)If at any time insufficient funds are received by and available to the Administrative Agent to pay fully the Obligations, or if a Default or Event of Default exists, any payment or prepayment shall be applied in the following order: (i) to the payment of enforcement expenses incurred by the Administrative Agent, including Attorney Costs; (ii) to the ratable payment of all other fees, expenses, and indemnities for which the Administrative Agent or Lenders have not been paid or reimbursed in accordance with the Loan Documents (as used in this Section 2.11(d)(ii), a “ratable payment” for any Lender or the Administrative Agent shall be, on any date of determination, that proportion which the portion of the total fees, expenses, and indemnities owed to such Lender or the Administrative Agent bears to the total aggregate fees and indemnities owed to all Lenders and the Administrative Agent on such date of determination); (iii) to the ratable payment of accrued and unpaid interest on the Outstanding Amount of Loans and the Outstanding Amount of Obligations under Lender Hedging Agreements (it being understood that for purposes of this clause (iii) the Outstanding Amount of Obligations under Lender Hedging Agreements refers only to payments owing pursuant to Section 2(a) of the 2002 Master Agreement  form promulgated by the ISDA (or equivalent type

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payment obligation if some other form of Swap Contract is in effect)(as used in this Section 2.11(d)(iii), “ratable payment” means, for any Lender (or Lender Affiliate, in the case of Lender Hedging Agreements), on any date of determination, that proportion which the accrued and unpaid interest on the Outstanding Amount of Loans and the Outstanding Amount of Obligations under Lender Hedging Agreements owed to such Lender (or Lender Affiliate, in the case of Lender Hedging Agreements) bears to the total accrued and unpaid interest on the Outstanding Amount of Loans and the Outstanding Amount of Obligations under Lender Hedging Agreements owed to all Lenders (and Affiliates, in the case of Lender Hedging Agreements)); (iv) to the ratable payment of the Outstanding Amount of Loans and the Outstanding Amount of Obligations under Lender Hedging Agreements (it being understood that for purposes of this clause (iv) the Outstanding Amount of Obligations under Lender Hedging Agreements refers to payments owing in connection with an Early Termination Payment as defined in the 2002 Master Agreement form promulgated by the ISDA (or equivalent type payment obligation if some other form of Swap Contract is in effect)(as used in this Section 2.11(d)(iv), “ratable payment” means for any Lender (or Lender Affiliate, in the case of Lender Hedging Agreements), on any date of determination, that proportion which the Outstanding Amount of Loans and the Outstanding Amount of Obligations under Lender Hedging Agreements owed to such Lender (or Lender Affiliate, in the case of Lender Hedging Agreements) bears to the Outstanding Amount of Loans owed to all Lenders)(and Affiliates, in the case of Lender Hedging Agreements)); (v) to Cash Collateralize the Letters of Credit; and (vi) to the payment of the remaining Obligations, if any, in the order and manner the Required Lenders deem appropriate.

(e)Unless the Borrower or any Lender has notified the Administrative Agent prior to the date any payment is required to be made by it to the Administrative Agent hereunder, that the Borrower or such Lender, as the case may be, will not make such payment, the Administrative Agent may assume that the Borrower or such Lender, as the case may be, has timely made such payment and may (but shall not be so required to), in reliance thereon, make available a corresponding amount to the Person entitled thereto.  If and to the extent that such payment was not in fact made to the Administrative Agent in immediately available funds, then:

(i)if the Borrower failed to make such payment, each Lender shall forthwith on demand repay to the Administrative Agent the portion of such assumed payment that was made available to such Lender in immediately available funds, together with interest thereon in respect of each day from and including the date such amount was made available by the Administrative Agent to such Lender to the date such amount is repaid to the Administrative Agent in immediately available funds, at the Federal Funds Rate from time to time in effect; and

(ii) if any Lender failed to make such payment, such Lender shall forthwith on demand pay to the Administrative Agent the amount thereof in immediately available funds, together with interest thereon for the period from the date such amount was made available by the Administrative Agent to the Borrower to the date such amount is recovered by the Administrative Agent (the “Compensation Period”) at a rate per annum equal to the Federal Funds Rate from time to time in effect.  If such Lender pays such amount to the Administrative Agent, then such amount shall constitute such Lender’s

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Loan, included in the applicable Borrowing.  If such Lender does not pay such amount forthwith upon the Administrative Agent’s demand therefor, the Administrative Agent may make a demand therefor upon the Borrower, and the Borrower shall pay such amount to the Administrative Agent, together with interest thereon for the Compensation Period at a rate per annum equal to the rate of interest applicable to the applicable Borrowing.  Nothing herein shall be deemed to relieve any Lender from its obligation to fulfill its Commitment or to prejudice any rights which the Administrative Agent or the Borrower may have against any Lender as a result of any default by such Lender hereunder.

A notice of the Administrative Agent to any Lender with respect to any amount owing under this subsection (e) shall be conclusive, absent manifest error.

(f)If any Lender makes available to the Administrative Agent funds for any Loan to be made by such Lender as provided in the foregoing provisions of this Article II, and the conditions to the applicable Borrowing set forth in Article IV are not satisfied or waived in accordance with the terms hereof, the Administrative Agent shall return such funds (in like funds as received from such Lender) to such Lender, without interest.

(g)The obligations of the Lenders hereunder to make Loans are several and not joint.  The failure of any Lender to make any Loan on any date required hereunder shall not relieve any other Lender of its corresponding obligation to do so on such date, and no Lender shall be responsible for the failure of any other Lender to so make its Loan or purchase its participation.

(h)Nothing herein shall be deemed to obligate any Lender to obtain the funds for any Loan in any particular place or manner or to constitute a representation by any Lender that it has obtained or will obtain the funds for any Loan in any particular place or manner.

2.12Sharing of Payments.  If, other than as expressly provided elsewhere herein, any Lender shall obtain on account of the Loans made by it, or the participations in the L/C Obligations, any payment (whether voluntary, involuntary, through the exercise of any right of set-off, or otherwise) in excess of its ratable share (or other share contemplated hereunder) thereof, such Lender shall immediately (a) notify the Administrative Agent, of such fact, and (b) purchase from the other Lenders such participations in the Loans made by them, and/or such subparticipations in the participations in L/C Obligations held by them, as shall be necessary to cause such purchasing Lender to share the excess payment in respect of such Loan or such participations, as the case may be, pro rata with each of them; provided, however, that if all or any portion of such excess payment is thereafter recovered from the purchasing Lender, such purchase shall to that extent be rescinded and each other Lender shall repay to the purchasing Lender the purchase price paid therefor, together with an amount equal to such paying Lender’s ratable share (according to the proportion of (i) the amount of such paying Lender’s required repayment to (ii) the total amount so recovered from the purchasing Lender) of any interest or other amount paid or payable by the purchasing Lender in respect of the total amount so recovered.  The Borrower agrees that any Lender so purchasing a participation from another Lender may, to the fullest extent permitted by law, exercise all its rights of payment (including

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the right of set-off, but subject to Section 10.09) with respect to such participation as fully as if such Lender were the direct creditor of the Borrower in the amount of such participation.  The Administrative Agent will keep records (which shall be conclusive and binding in the absence of manifest error) of participations purchased under this Section and will in each case notify the Lenders following any such purchases or repayments.  Each Lender that purchases a participation pursuant to this Section shall from and after such purchase have the right to give all notices, requests, demands, directions and other communications under this Agreement with respect to the portion of the Obligations purchased to the same extent as though the purchasing Lender were the original owner of the Obligations purchased.

2.13Priority of Hedging Obligations and Banking Service Obligations.  Any amounts received in satisfaction of any Obligations arising under the Loan Documents, including, without limitation, Obligations under this Agreement, Obligations under any Lender Hedging Agreement and Obligations in connection with any Banking Services, shall rank pari passu in right of payment and shall be used to repay such Obligations on a pro rata basis, unless specified otherwise in Section 2.11(d).

2.14Letters of Credit.   (a)  The Letter of Credit Commitment.

(i)Subject to the terms and conditions set forth herein, (A) the L/C Issuer agrees, in reliance upon the agreements of the other Lenders set forth in this Section 2.14, (1) from time to time on any Business Day during the period from the Restatement Date until the Letter of Credit Expiration Date, to issue Letters of Credit for the account of the Borrower or its Subsidiaries, and to amend or renew Letters of Credit previously issued by it, in accordance with subsection (b) below, and (2) to honor drafts under the Letters of Credit; and (B) the Lenders severally agree to participate in Letters of Credit issued for the account of the Borrower and its Subsidiaries; provided that the L/C Issuer shall not be obligated to make any L/C Credit Extension with respect to any Letter of Credit, and no Lender shall be obligated to participate in any Letter of Credit, if as of the date of such L/C Credit Extension, (x) the Outstanding Amount of all L/C Obligations and all Revolver Loans would exceed the Aggregate Revolver Commitments, (y) the aggregate Outstanding Amount of the Revolver Loans of any Lender, plus such Lender’s Pro Rata Share of the Outstanding Amount of all L/C Obligations would exceed such Lender’s Revolver Commitment, or (z) the Outstanding Amount of the L/C Obligations would exceed the Letter of Credit Sublimit.  Within the foregoing limits, and subject to the terms and conditions hereof, the Borrower’s ability to obtain Letters of Credit shall be fully revolving, and accordingly the Borrower may, during the foregoing period, obtain Letters of Credit to replace Letters of Credit that have expired or that have been drawn upon and reimbursed.

(ii)The L/C Issuer shall be under no obligation to issue any Letter of Credit if:

(A)any order, judgment or decree of any Governmental Authority or arbitrator shall by its terms purport to enjoin or restrain the L/C Issuer from issuing such Letter of Credit, or any Law applicable to the L/C Issuer or any

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request or directive (whether or not having the force of law) from any Governmental Authority with jurisdiction over the L/C Issuer shall prohibit, or request that the L/C Issuer refrain from, the issuance of letters of credit generally or such Letter of Credit in particular or shall impose upon the L/C Issuer with respect to such Letter of Credit any restriction, reserve or capital requirement (for which the L/C Issuer is not otherwise compensated hereunder) not in effect on the Closing Date, or shall impose upon the L/C Issuer any unreimbursed loss, cost or expense which was not applicable on the Closing Date and which the L/C Issuer in good faith deems material to it;

(B)subject to Section 2.14(b)(iii), the expiry date of such requested Letter of Credit would occur more than twelve months after the date of issuance or last renewal, unless the Required Lenders have approved such expiry date;

(C)the expiry date of such requested Letter of Credit would occur after the Letter of Credit Expiration Date, unless all the Lenders have approved such expiry date;

(D)the issuance of such Letter of Credit would violate one or more policies of the L/C Issuer generally applicable to all borrowers; or

(E)such Letter of Credit is in a face amount less than $100,000, or is to be used for a purpose other than as described in Section 6.12 or is denominated in a currency other than Dollars.

(iii)The L/C Issuer shall be under no obligation to amend any Letter of Credit if (A) the L/C Issuer would have no obligation at such time to issue such Letter of Credit in its amended form under the terms hereof, or (B) the beneficiary of such Letter of Credit does not accept the proposed amendment to such Letter of Credit.

(b)Procedures for Issuance and Amendment of Letters of Credit; Evergreen Letters of Credit.

(i)Each Letter of Credit shall be issued or amended, as the case may be, upon the request of the Borrower delivered to the L/C Issuer (with a copy to the Administrative Agent) in the form of a Letter of Credit Application, appropriately completed and signed by a Responsible Officer of the Borrower.  Such Letter of Credit Application must be received by the L/C Issuer and the Administrative Agent not later than 11:00 a.m., New York time, at least two Business Days (or such later date and time as the L/C Issuer may agree in a particular instance in its sole discretion) prior to the proposed issuance date or date of amendment, as the case may be.  In the case of a request for an initial issuance of a Letter of Credit, such Letter of Credit Application shall specify in form and detail satisfactory to the L/C Issuer: (A) the proposed issuance date of the requested Letter of Credit (which shall be a Business Day); (B) the amount thereof; (C) the expiry date thereof; (D) the name and address of the beneficiary thereof; (E) the documents to be

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presented by such beneficiary in case of any drawing thereunder; (F) the full text of any certificate to be presented by such beneficiary in case of any drawing thereunder; and (G) such other matters as the L/C Issuer may require.  In the case of a request for an amendment of any outstanding Letter of Credit, such Letter of Credit Application shall specify in form and detail satisfactory to the L/C Issuer (A) the Letter of Credit to be amended; (B) the proposed date of amendment thereof (which shall be a Business Day); (C) the nature of the proposed amendment; and (D) such other matters as the L/C Issuer may require.

(ii)Promptly after receipt of any Letter of Credit Application, the L/C Issuer will confirm with the Administrative Agent (by telephone or in writing) that the Administrative Agent has received a copy of such Letter of Credit Application from the Borrower and, if not, the L/C Issuer will provide the Administrative Agent with a copy thereof.  Upon receipt by the L/C Issuer of confirmation from the Administrative Agent that the requested issuance or amendment is permitted in accordance with the terms hereof, then, subject to the terms and conditions hereof, the L/C Issuer shall, on the requested date, issue a Letter of Credit for the account of the Borrower or enter into the applicable amendment, as the case may be, in each case in accordance with the L/C Issuer’s usual and customary business practices.  Immediately upon the issuance of each Letter of Credit, each Lender shall be deemed to, and hereby irrevocably and unconditionally agrees to, purchase from the L/C Issuer a participation in such Letter of Credit in an amount equal to the product of such Lender’s Pro Rata Share times the amount of such Letter of Credit.

(iii)If the Borrower so requests in any applicable Letter of Credit Application, the L/C Issuer may, in it sole and absolute discretion, agree to issue a Letter of Credit that has automatic renewal provisions (each, an “Evergreen Letter of Credit”); provided that any such Evergreen Letter of Credit must permit the L/C Issuer to prevent any such renewal at least once in each twelve-month period (commencing with the date of issuance of such Letter of Credit) by giving prior notice to the beneficiary thereof not later than a day (the “Nonrenewal Notice Date”) in each such twelve-month period to be agreed upon at the time such Letter of Credit is issued.  Unless otherwise directed by the L/C Issuer, the Borrower shall not be required to make a specific request to the L/C Issuer for any such renewal.  Once an Evergreen Letter of Credit has been issued, the Lenders shall be deemed to have authorized (but may not require) the L/C Issuer to permit the renewal of such Letter of Credit at any time to a date not later than the Letter of Credit Expiration Date; provided, however, that the L/C Issuer shall not permit any such renewal if it has received notice on or before the Business Day immediately preceding the Nonrenewal Notice Date (1) from the Administrative Agent that the Required Lenders have elected not to permit such renewal or (2) from any Lender stating that one or more of the applicable conditions specified in Section 4.02 is not then satisfied and directing the L/C Issuer not to permit such renewal.  Notwithstanding anything to the contrary contained herein, the L/C Issuer shall have no obligation to permit the renewal of any Evergreen Letter of Credit at any time.

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(iv)Promptly after its delivery of any Letter of Credit or any amendment to a Letter of Credit to an advising bank with respect thereto or to the beneficiary thereof, the L/C Issuer will also deliver to the Borrower and the Administrative Agent a true and complete copy of such Letter of Credit or amendment.

(c)Drawings and Reimbursements; Funding of Participations.

(i)Upon any drawing under any Letter of Credit, the L/C Issuer shall notify the Borrower and the Administrative Agent thereof.   Not later than 11:00 a.m., New York time, on the date of any payment by the L/C Issuer under a Letter of Credit (each such date, an “Honor Date”), the Borrower shall reimburse the L/C Issuer through the Administrative Agent in an amount equal to the amount of such drawing.  If the Borrower fails to so reimburse the L/C Issuer by such time, the Administrative Agent shall promptly notify each Lender of the Honor Date, the amount of the unreimbursed drawing (the “Unreimbursed Amount”), and such Lender’s Pro Rata Share thereof.  In such event, the Borrower shall be deemed to have requested a Borrowing of Base Rate Revolver Loans to be disbursed on the Honor Date in an amount equal to the Unreimbursed Amount, without regard to the minimum and multiples specified in Section 2.03 for the principal amount of Base Rate Revolver Loans, but subject to the amount of the unutilized portion of the Aggregate Commitments and the conditions set forth in Section 4.02 (other than the delivery of a Borrowing Notice).  Any notice given by the L/C Issuer or the Administrative Agent pursuant to this Section 2.14(c) (i) may be given by telephone if immediately confirmed in writing; provided that the lack of such an immediate confirmation shall not affect the conclusiveness or binding effect of such notice.

(ii)Each Lender (including the Lender acting as L/C Issuer) shall upon any notice pursuant to Section 2.14(c)(i) make funds available to the Administrative Agent for the account of the L/C Issuer at the Administrative Agent’s Office in an amount equal to its Pro Rata Share of the Unreimbursed Amount not later than 11:00 a.m., New York time, on the Business Day specified in such notice by the Administrative Agent, whereupon, subject to the provisions of Section 2.14(c)(iii), each Lender that so makes funds available shall be deemed to have made a Base Rate Revolver Loan to the Borrower in such amount.  The Administrative Agent shall remit the funds so received to the L/C Issuer.

(iii)With respect to any Unreimbursed Amount that is not fully refinanced by a Borrowing of Base Rate Revolver Loans because the conditions set forth in Section 4.02 cannot be satisfied or for any other reason, the Borrower shall be deemed to have incurred from the L/C Issuer an L/C Borrowing in the amount of the Unreimbursed Amount that is not so refinanced, which L/C Borrowing shall be due and payable on demand (together with interest) and shall bear interest at the Default Rate.  In such event, each Lender’s payment to the Administrative Agent for the account of the L/C Issuer pursuant to Section 2.14(c) (ii) shall be deemed payment in respect of its participation in

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such L/C Borrowing and shall constitute an L/C Advance from such Lender in satisfaction of its participation obligation under this Section 2.14.

(iv)Until each Lender funds its Revolver Loan or L/C Advance pursuant to this Section 2.14(c) to reimburse the L/C Issuer for any amount drawn under any Letter of Credit, interest in respect of such Lender’s Pro Rata Share of such amount shall be solely for the account of the L/C Issuer.

(v)Each Lender’s obligation to make Revolver Loans or L/C Advances to reimburse the L/C Issuer for amounts drawn under Letters of Credit, as contemplated by this Section 2.14(c), shall be absolute and unconditional and shall not be affected by any circumstance, including (A) any set-off, counterclaim, recoupment, defense or other right which such Lender may have against the L/C Issuer, the Borrower or any other Person for any reason whatsoever; (B) the occurrence or continuance of a Default or Event of Default, or (C) any other occurrence, event or condition, whether or not similar to any of the foregoing.  Any such reimbursement shall not relieve or otherwise impair the obligation of the Borrower to reimburse the L/C Issuer for the amount of any payment made by the L/C Issuer under any Letter of Credit, together with interest as provided herein.

(vi)If any Lender fails to make available to the Administrative Agent for the account of the L/C Issuer any amount required to be paid by such Lender pursuant to the foregoing provisions of this Section 2.14(c) by the time specified in Section 2.14(c)(ii), the L/C Issuer shall be entitled to recover from such Lender (acting through the Administrative Agent), on demand, such amount with interest thereon for the period from the date such payment is required to the date on which such payment is immediately available to the L/C Issuer at a rate per annum equal to the Federal Funds Rate from time to time in effect.  A certificate of the L/C Issuer submitted to any Lender (through the Administrative Agent) with respect to any amounts owing under this clause (vi) shall be conclusive absent manifest error.

(d)Repayment of Participations.

(i)At any time after the L/C Issuer has made a payment under any Letter of Credit and has received from any Lender such Lender’s L/C Advance in respect of such payment in accordance with Section 2.14(c), if the Administrative Agent receives for the account of the L/C Issuer any payment related to such Letter of Credit (whether directly from the Borrower or otherwise, including proceeds of cash Collateral applied thereto by the Administrative Agent), or any payment of interest thereon, the Administrative Agent will distribute to such Lender its Pro Rata Share thereof in the same funds as those received by the Administrative Agent.

(ii)If any payment received by the Administrative Agent for the account of the L/C Issuer pursuant to Section 2.14(c)(i) is required to be returned, each Lender shall pay to the Administrative Agent for the account of the L/C Issuer its Pro Rata Share

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thereof on demand of the Administrative Agent, plus interest thereon from the date of such demand to the date such amount is returned by such Lender, at a rate per annum equal to the Federal Funds Rate from time to time in effect.

(e)Obligations Absolute.  The obligation of the Borrower to reimburse the L/C Issuer for each drawing under each Letter of Credit, and to repay each L/C Borrowing and each drawing under a Letter of Credit that is refinanced by a Borrowing of Revolver Loans, shall be absolute, unconditional and irrevocable, and shall be paid strictly in accordance with the terms of this Agreement under all circumstances, including the following:

(i)any lack of validity or enforceability of such Letter of Credit, this Agreement, or any other agreement or instrument relating thereto;

(ii)the existence of any claim, counterclaim, set-off, defense or other right that the Borrower may have at any time against any beneficiary or any transferee of such Letter of Credit (or any Person for whom any such beneficiary or any such transferee may be acting), the L/C Issuer or any other Person, whether in connection with this Agreement, the transactions contemplated hereby or by such Letter of Credit or any agreement or instrument relating thereto, or any unrelated transaction;

(iii)any draft, demand, certificate or other document presented under such Letter of Credit proving to be forged, fraudulent, invalid or insufficient in any respect or any statement therein being untrue or inaccurate in any respect; or any loss or delay in the transmission or otherwise of any document required in order to make a drawing under such Letter of Credit;

(iv)any payment by the L/C Issuer under such Letter of Credit against presentation of a draft or certificate that does not strictly comply with the terms of such Letter of Credit; or any payment made by the L/C Issuer under such Letter of Credit to any Person purporting to be a trustee in bankruptcy, debtor-in-possession, assignee for the benefit of creditors, liquidator, receiver or other representative of or successor to any beneficiary or any transferee of such Letter of Credit, including any arising in connection with any proceeding under any Debtor Relief Law; or

(v)any other circumstance or happening whatsoever, whether or not similar to any of the foregoing, that might otherwise constitute a defense available to, or a discharge of, the Borrower.

The Borrower shall promptly examine a copy of each Letter of Credit and each amendment thereto that is delivered to it and, in the event of any claim of noncompliance with the Borrower’s instructions or other irregularity, the Borrower will immediately notify the L/C Issuer.  The Borrower shall be conclusively deemed to have waived any such claim against the L/C Issuer and its correspondents unless such notice is given as aforesaid.

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(f)            Role of L/C Issuer.  Each Lender and the Borrower agree that, in paying any drawing under a Letter of Credit, the L/C Issuer shall not have any responsibility to obtain any document (other than any sight draft, certificates and documents expressly required by the Letter of Credit) or to ascertain or inquire as to the validity or accuracy of any such document or the authority of the Person executing or delivering any such document.  No Agent-Related Person nor any of the respective correspondents, participants or assignees of the L/C Issuer shall be liable to any Lender for (i) any action taken or omitted in connection herewith at the request or with the approval of the Lenders or the Required Lenders, as applicable, (ii) any action taken or omitted in the absence of gross negligence or willful misconduct; or (iii) the due execution, effectiveness, validity or enforceability of any document or instrument related to any Letter of Credit or Letter of Credit Application.  The Borrower hereby assumes all risks of the acts or omissions of any beneficiary or transferee with respect to its use of any Letter of Credit; provided, however, that this assumption is not intended to, and shall not, preclude the Borrower’s pursuing such rights and remedies as it may have against the beneficiary or transferee at law or under any other agreement.  No Agent-Related Person, nor any of the respective correspondents, participants or assignees of the L/C Issuer, shall be liable or responsible for any of the matters described in clauses (i) through (v) of Section 2.14(e); provided, however, that anything in such clauses to the contrary notwithstanding, the Borrower may have a claim against the L/C Issuer, and the L/C Issuer may be liable to the Borrower, to the extent, but only to the extent, of any direct, as opposed to consequential or exemplary, damages suffered by the Borrower which the Borrower proves were caused by the L/C Issuer’s willful misconduct or gross negligence or the L/C Issuer’s willful failure to pay under any Letter of Credit after the presentation to it by the beneficiary of a sight draft and certificate(s) strictly complying with the terms and conditions of a Letter of Credit.  In furtherance and not in limitation of the foregoing, the L/C Issuer may accept documents that appear on their face to be in order, without responsibility for further investigation, regardless of any notice or information to the contrary, and the L/C Issuer shall not be responsible for the validity or sufficiency of any instrument transferring or assigning or purporting to transfer or assign a Letter of Credit or the rights or benefits thereunder or proceeds thereof, in whole or in part, which may prove to be invalid or ineffective for any reason.

(g)           Cash Collateral.  Upon the request of the Administrative Agent, (i) if the L/C Issuer has honored any full or partial drawing request under any Letter of Credit and such drawing has resulted in an L/C Borrowing, or (ii) if, as of the Letter of Credit Expiration Date, any Letter of Credit may for any reason remain outstanding and partially or wholly undrawn, the Borrower shall immediately Cash Collateralize the then Outstanding Amount of all L/C Obligations (in an amount equal to such Outstanding Amount).  The Borrower hereby grants the Administrative Agent, for the benefit of the L/C Issuer and the Lenders, a Lien on all such cash and deposit accounts at any Lender.

(h)           Applicability of ISP98.  Unless otherwise expressly agreed by the L/C Issuer and the Borrower when a Letter of Credit is issued (including any such agreement applicable to an Existing Letter of Credit), the rules of the “International Standby Practices 1998” published by the Institute of International Banking Law & Practice (or such later version thereof as may be in effect at the time of issuance) shall apply to each Letter of Credit.

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(i)            Letter of Credit Fees.  The Borrower shall pay to the Administrative Agent for the account of each Lender in accordance with its Pro Rata Share a Letter of Credit fee for each Letter of Credit issued equal to the Applicable Rate times the actual daily undrawn amount under each Letter of Credit.  Such fee for each Letter of Credit shall be due and payable on the last Business Day of each March, June, September and December, commencing with the first such date to occur after the issuance of such Letter of Credit, and on the Letter of Credit Expiration Date.  If there is any change in the Applicable Rate during any quarter, the actual daily undrawn amount of each Letter of Credit shall be computed and multiplied by the Applicable Rate separately for each period during such quarter that such Applicable Rate was in effect.

(j)            Fronting Fee and Documentary and Processing Charges Payable to L/C Issuer.  The Borrower shall pay directly to the L/C Issuer for its own account a fronting fee in an amount with respect to each Letter of Credit issued equal to the greater of (i) $500 or (ii) 1/4 of 1% calculated on the face amount thereof.  In addition, the Borrower shall pay directly to the L/C Issuer for its own account the customary issuance, presentation, amendment and other processing fees, and other standard costs and charges, of the L/C Issuer relating to letters of credit as from time to time in effect.  Such fees and charges are due and payable on demand and are nonrefundable.

(k)           Conflict with Letter of Credit Application.  In the event of any conflict between the terms hereof and the terms of any Letter of Credit Application, the terms hereof shall control.

ARTICLE III.

TAXES, YIELD PROTECTION AND ILLEGALITY

3.01        Taxes.

(a)           Any and all payments by the Borrower to or for the account of the Administrative Agent or any Lender under any Loan Document shall be made free and clear of and without deduction for any and all present or future taxes, duties, levies, imposts, deductions, assessments, fees, withholdings or similar charges, and all liabilities with respect thereto; excluding, in the case of the Administrative Agent and each Lender, taxes imposed on or measured by its net income, and franchise taxes imposed on it (in lieu of net income taxes), by the jurisdiction (or any political subdivision thereof) under the Laws of which the Administrative Agent or such Lender, as the case may be, is organized or maintains its Lending Office (all such non-excluded taxes, duties, levies, imposts, deductions, assessments, fees, withholdings or similar charges, and liabilities being hereinafter referred to as “Taxes”).  If the Borrower shall be required by any Laws to deduct any Taxes from or in respect of any sum payable under any Loan Document to the Administrative Agent or any Lender, (i) the sum payable shall be increased as necessary so that after making all required deductions (including deductions applicable to additional sums payable under this Section), each of the Administrative Agent and such Lender receives an amount equal to the sum it would have received had no such deductions been made, (ii) the Borrower shall make such deductions, (iii) the Borrower shall pay the full amount deducted to the relevant taxation authority or other authority in accordance with applicable Laws, and (iv) within 30 days after the date of such payment, the Borrower shall furnish to the Administrative

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Agent (which shall forward the same to such Lender) the original or a certified copy of a receipt evidencing payment thereof.

(b)           In addition, the Borrower agrees to pay any and all present or future stamp, court or documentary taxes and any other excise or property taxes or charges or similar levies which arise from any payment made under any Loan Document or from the execution, delivery, performance, enforcement or registration of, or otherwise with respect to, any Loan Document (hereinafter referred to as “Other Taxes”).

(c)           If the Borrower shall be required to deduct or pay any Taxes or Other Taxes from or in respect of any sum payable under any Loan Document to the Administrative Agent or any Lender, the Borrower shall also pay to the Administrative Agent (for the account of such Lender) or to such Lender, at the time interest is paid, such additional amount that such Lender specifies as necessary to preserve the after-tax yield (after factoring in all taxes, including taxes imposed on or measured by net income) such Lender would have received if such Taxes or Other Taxes had not been imposed.

(d)           The Borrower agrees to indemnify the Administrative Agent and each Lender for (i) the full amount of Taxes and Other Taxes (including any Taxes or Other Taxes imposed or asserted by any jurisdiction on amounts payable under this Section) paid by the Administrative Agent and such Lender, (ii) amounts payable under Section 3.01(c) and (iii) any liability (including penalties, interest and expenses) arising therefrom or with respect thereto.  Payment under this subsection (d) shall be made within 30 days after the date the Lender or the Administrative Agent makes a demand therefor.

3.02        Illegality.  If any Lender determines that any Law has made it unlawful, or that any Governmental Authority has asserted that it is unlawful, for any Lender or its applicable Lending Office to make, maintain or fund Eurodollar Rate Loans, or materially restricts the authority of such Lender to purchase or sell, or to take deposits of, Dollars in the applicable offshore Dollar market, or to determine or charge interest rates based upon the Eurodollar Rate, then, on notice thereof by such Lender to the Borrower through the Administrative Agent, any obligation of such Lender to make or continue Eurodollar Rate Loans or to convert Base Rate Loans to Eurodollar Rate Loans shall be suspended until such Lender notifies the Administrative Agent and the Borrower that the circumstances giving rise to such determination no longer exist.  Upon receipt of such notice, the Borrower shall, upon demand from such Lender (with a copy to the Administrative Agent), prepay or, if applicable, convert all Eurodollar Rate Loans of such Lender to Base Rate Loans, either on the last day of the Interest Period thereof, if such Lender may lawfully continue to maintain such Eurodollar Rate Loans to such day, or immediately, if such Lender may not lawfully continue to maintain such Eurodollar Rate Loans.  Upon any such prepayment or conversion, the Borrower shall also pay interest on the amount so prepaid or converted.  Each Lender agrees to designate a different Lending Office if such designation will avoid the need for such notice and will not, in the reasonable judgment of such Lender, otherwise be materially disadvantageous to such Lender.

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3.03        Inability to Determine Rates.  If the Administrative Agent determines in connection with any request for a Eurodollar Rate Loan or a conversion to or continuation thereof that (a) Dollar deposits are not being offered to banks in the applicable offshore Dollar market for the applicable amount and Interest Period of such Eurodollar Rate Loan, or adequate and reasonable means do not exist for determining the Eurodollar Rate for such Eurodollar Rate Loan, or (b) if the Required Lenders determine and notify the Administrative Agent that the Eurodollar Rate for such Eurodollar Rate Loan does not adequately and fairly reflect the cost to the Lenders of funding such Eurodollar Rate Loan, then the Administrative Agent will promptly notify the Borrower and all Lenders.  Thereafter, the obligation of the Lenders to make or maintain Eurodollar Rate Loans shall be suspended until the Administrative Agent revokes such notice.  Upon receipt of such notice, the Borrower may revoke any pending request for a Borrowing, conversion or continuation of Eurodollar Rate Loans or, failing that, will be deemed to have converted such request into a request for a Borrowing of Base Rate Loans in the amount specified therein.

3.04        Increased Cost and Reduced Return; Capital Adequacy; Reserves on Eurodollar Rate Loans.

(a)           If any Lender determines that as a result of a Change in Law, or such Lender’s compliance therewith, there shall be any increase in the cost to such Lender of agreeing to make or making, funding or maintaining Eurodollar Rate Loans, or a reduction in the amount received or receivable by such Lender in connection with any of the foregoing (excluding for purposes of this subsection (a) any such increased costs or reduction in amount resulting from (i) Taxes or Other Taxes (as to which Section 3.01 shall govern), (ii) changes in the basis of taxation of overall net income or overall gross income by the United States or any foreign jurisdiction or any political subdivision of either thereof under the Laws of which such Lender is organized or has its Lending Office, and (iii) reserve requirements contemplated by Section 3.04(c) utilized, as to Eurodollar Rate Loans, in the determination of the Eurodollar Rate), then from time to time upon demand of such Lender (with a copy of such demand to the Administrative Agent), the Borrower shall pay to such Lender such additional amounts as will compensate such Lender for such increased cost or reduction.

(b)           If any Lender determines a Change in Law has the effect of reducing the rate of return on the capital of such Lender or any corporation controlling such Lender as a consequence of such Lender’s obligations hereunder (taking into consideration its policies with respect to capital adequacy and such Lender’s desired return on capital, then from time to time upon demand of such Lender (with a copy of such demand to the Administrative Agent), the Borrower shall pay to such Lender such additional amounts as will compensate such Lender for such reduction.

(c)           The Borrower shall pay to each Lender, as long as such Lender shall be required under regulations of the Board to maintain reserves with respect to liabilities or assets consisting of or including Eurocurrency funds or deposits (currently known as “Eurocurrency liabilities”), additional costs on the unpaid principal amount of each Eurodollar Rate Loan equal to the actual costs of such reserves allocated to such Loan by such Lender (as determined by such Lender in

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good faith, which determination shall be conclusive), which shall be due and payable on each date on which interest is payable on such Loan; provided the Borrower shall have received at least 15 days’ prior notice (with a copy to the Administrative Agent) of such additional interest from such Lender.  If a Lender fails to give notice 15 days prior to the relevant Interest Payment Date, such additional interest shall be due and payable 15 days from receipt of such notice.

3.05        Funding Losses.  Upon demand of any Lender (with a copy to the Administrative Agent) from time to time, the Borrower shall promptly compensate such Lender for and hold such Lender harmless from any loss, cost or expense incurred by it as a result of:

(a)           any continuation, conversion, payment or prepayment of any Loan other than a Base Rate Loan on a day other than the last day of the Interest Period for such Loan (whether voluntary, mandatory, automatic, by reason of acceleration, or otherwise); or

(b)           any failure by the Borrower (for a reason other than the failure of such Lender to make a Loan) to prepay, borrow, continue or convert any Loan other than a Base Rate Loan on the date or in the amount notified by the Borrower; including any loss of anticipated profits and any loss or expense arising from the liquidation or reemployment of funds obtained by it to maintain such Loan or from fees payable to terminate the deposits from which such funds were obtained.  The Borrower shall also pay any customary administrative fees charged by such Lender in connection with the foregoing.

For purposes of calculating amounts payable by the Borrower to the Lenders under this Section 3.05, each Lender shall be deemed to have funded each Eurodollar Rate Loan made by it at the Eurodollar Rate for such Loan by a matching deposit or other borrowing in the applicable offshore Dollar interbank market for a comparable amount and for a comparable period, whether or not such Eurodollar Rate Loan was in fact so funded.

3.06        Matters Applicable to all Requests for Compensation.  A certificate of the Administrative Agent or any Lender claiming compensation under this Article III and setting forth the additional amount or amounts to be paid to it hereunder shall be conclusive in the absence of manifest error.  In determining such amount, the Administrative Agent or such Lender may use any reasonable averaging and attribution methods.

3.07        Survival.  All of the Borrower’s obligations under this Article III shall survive termination of the Aggregate Commitments and payment in full of all the other Obligations.

ARTICLE IV.
CONDITIONS PRECEDENT TO AMENDMENT
AND RESTATEMENT OF AGREEMENT

4.01        Conditions Precedent to Amendment and Restatement of Agreement.  The amendment and restatement of this Agreement on the Restatement Conditions Effective Date is subject to, and will take effect upon, satisfaction of the following conditions precedent on or prior to such date:

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(a)           Satisfactory completion of due diligence by the Arranger, including without limitation, receipt and review, with results satisfactory to the Arranger, of information regarding material contracts, property ownership, organizational structure, litigation, tax, accounting, insurance and environmental matters (including Phase I and, if any, Phase II environmental studies related to the ACET Acquisition) currently in the Borrower’s possession and relating to the ACET Acquisition.

(b)           The Administrative Agent’s receipt, in form and substance reasonably satisfactory to the Administrative Agent, and reasonably satisfactory review of a reserve report prepared by Cawley Gillespie & Associates, Inc. of natural gas reserves in connection with the ACET Acquisition.

(c)           The Administrative Agent’s receipt, in form and substance reasonably satisfactory to the Administrative Agent, and reasonably satisfactory review of an evaluation and financial analysis prepared by Barnes & Click, Inc. in connection with the ACET Acquisition.

(d)           Satisfactory evidence that a private placement of MLP common or preferred units generating gross sale proceeds of no less than $45,000,000 has been completed on terms and conditions satisfactory to the Agent in all respects and the MLP has contributed the net sale proceeds from such MLP private placement to be applied toward the purchase price of the ACET Acquisition.

(e)           Satisfactory evidence that the ACET Acquisition has been (or contemporaneously with the funding of the Revolver Loans and Term Loans on the Restatement Conditions Effective Date will be) consummated for a purchase price not to exceed $240,400,000 (excluding acquired working capital and fees/expenses associated therewith and any adjustments to the purchase price pursuant to Section 3.2 of the ACET PSA) and on terms and conditions and pursuant to documentation satisfactory to the Administrative Agent in all respects.

(f)            The Administrative Agent’s receipt of the following, each of which shall be originals or facsimiles (followed promptly by originals) and unless otherwise specified, each properly executed by an authorized officer of the signing Loan Party or other Person party thereto, each dated the Restatement Date (or, in the case of certificates of governmental officials, a recent date before the Restatement Date), and each in form and substance satisfactory to the Administrative Agent and its legal counsel:

(i)            executed counterparts of an Assignment and Assumption from each of Bank of Oklahoma, Bank One, Comerica, Guaranty Bank, [Fortis], [US Bank] and Wells Fargo, as lenders under the First Amended and Restated Credit Agreement, assigning all of their rights and obligations under the First Amended and Restated Credit Agreement (including all of their respective commitments and loans and participations in letters of credit thereunder and all liens and security interests granted as security for indebtedness under the First Amended and Restated Credit Agreement) to Administrative Agent and Administrative Agent shall have accepted and recorded such assignments and the Borrower shall also have consented to such assignments;

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(ii)           executed counterparts of this Agreement, the Amended and Restated Subsidiary Guaranty, the Amended and Restated MLP Guaranty, the Mortgage from MW Energy covering the assets acquired by MW Energy in connection with the ACET Acquisition, amendments and/or supplements to any or all existing Mortgages from any Loan Party covering Mortgaged Properties if deemed advisable by Administrative Agent or its counsel, an amendment to the pledge agreement from Borrower pledging 100% of the equity in MW Energy, the Amended and Restated MarkWest Parent Deposit Pledge Agreement, and all other Collateral Documents, as amended and restated as deemed advisable by the Administrative Agent or its counsel, each dated as of the Restatement Date;

(iii)          Notes executed by the Borrower in favor of each Lender requesting such Notes, each Revolver Note in a principal amount equal to such Lender’s Revolver Commitment, each Term Note in a principal amount equal to such Lender’s Term Loan Commitment, and each Note dated as of the Restatement Date;

(iv)          such certificates of resolutions or other action, incumbency certificates and/or other certificates of officers of each Loan Party as the Administrative Agent may require to establish the identities of and verify the authority and capacity of each officer thereof authorized to act in connection with this Agreement and the other Loan Documents to which such Loan Party is a party;

(v)           such evidence as the Administrative Agent may reasonably require to verify that each Loan Party is duly organized or formed, validly existing, and in good standing in the jurisdiction of its organization;

(vi)          a certificate signed by a Responsible Officer of the Borrower certifying (A) that the representations and warranties contained in Article V are true and correct in all respects on and as of the Restatement Date, (B) that no Default or Event of Default had occurred and was continuing under the First Amended and Restated Credit Agreement as of the Restatement Date and no Default or Event of Default has occurred and is continuing under this Agreement as of the Restatement Date or will exist immediately after funding the Revolver Loan and Term Loan to finance the ACET Acquisition, (C) since March 31, 2004 there has occurred no material adverse change in (x) the business, assets, liabilities (actual or contingent), operations, or condition (financial or otherwise) or prospects of the Borrower and Guarantors, taken as a whole, or (y) any of the businesses, assets or liabilities acquired or assumed or being acquired or assumed by the Borrower or any of its Subsidiaries, (D) that as of the Restatement Date there are no material environmental or material legal issues affecting any Loan Party or any of the Collateral, (E) all necessary governmental and third party approvals necessary or required for any Loan Party to enter into this Agreement or any of the Loan Documents has been obtained, (F) there is no litigation, investigation or proceeding known to and affecting the Borrower or any Borrower Affiliate for which the Borrower is required to give notice pursuant to Section 6.03(c) (or, if there is any such litigation, investigation or proceeding, then a notice containing the information required by Section 6.03(c)

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shall be given concurrently with the delivery of the certificate given pursuant to this clause (vi)), (G) all material governmental approvals necessary or required in connection with the ACET Acquisition, including under the Hart Scott Rodino Act have been obtained, and (H) no action, suit, investigation or proceeding is pending or threatened in any court or before any arbitrator or governmental authority by or against the Borrower, any Guarantor, the General Partner, or any of their respective properties, that (x) contests or seeks to adversely affect the ACET Acquisition, or (y) could reasonably be expected to materially and adversely affect the Borrower or any Guarantor, taken as a whole, or (z) seeks to affect or pertains to any transaction contemplated hereby or the ability of the Borrower or any Guarantor to perform its obligations under the Loan Documents;

(vii)         a certificate of a Responsible Officer (a) of the Borrower demonstrating compliance with all financial covenants on a pro forma basis for the quarter ended June 30, 2004, (b) of the Borrower as to the satisfaction of all conditions specified in this Section 4.01 and Section 4.02, and (c) providing copies of the following (A) pro forma financial statements of the MLP on a consolidated basis after giving effect to the ACET Acquisition for the period ended June 30, 2004 and reflecting EBITDA of not less than $46,000,000 on a trailing 12-month basis, (B) a five-year financial forecast for the MLP on a consolidated basis pro forma after giving effect to the ACET Acquisition, and (C) such other financial information as the Administrative Agent may reasonably request;

(viii)        a certificate of a Responsible Officer of the Borrower certifying that neither the Borrower and its Subsidiaries on a consolidated basis nor the MLP and its Subsidiaries on a consolidated basis are “insolvent” as such term is used and defined in (i) the United States Bankruptcy Code or (ii) the Texas Uniform Fraudulent Transfer Act, Tex. Bus. & Com. Code Ann. §24.003.

(ix)           an opinion from Hogan & Hartson, L.L.P., counsel to each Loan Party and the General Partner, in form and substance satisfactory to the Administrative Agent and its counsel;

(x)            a letter from National Rgistered Agents, Inc., to accept service of process in the State of Texas on behalf of MW Energy;

(xi)           an assignment of note and liens from Wachovia Bank, N.A., as agent for lenders to American Central Eastern Texas Gas Company Limited Partnership, assigning the Indebtedness owing by American Central Eastern Texas Gas Company Limited Partnership to such lenders secured by a Lien on the assets to be acquired by MW Energy pursuant to the ACET PSA in consideration for payment of such Indebtedness;

(xii)          a payoff letter signed by Borrower, American Central Eastern Texas Gas Company Limited Partnership and Wachovia Bank, N.A., as agent, pursuant to which American Central Eastern Texas Gas Company Limited Partnership shall direct Borrower and Borrower shall direct Administrative Agent to directly fund to Wachovia Bank, N.A.

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the portion of the purchase price for the ACET Acquisition required to repay the Indebtedness owing by American Central Eastern Texas Gas Company Limited Partnership to Wachovia Bank, N.A. and its other lenders secured by a Lien on the assets to be acquired by MW Energy pursuant to the ACET PSA; and

(xiii)         such other assurances, certificates, documents, consents or opinions as the Administrative Agent reasonably may require.

(g)           Any fees due and payable at the Restatement Date shall have been paid including, without limitation, payment of fees and expenses pursuant to the Agent/Arranger Fee Letter.

(h)           The Borrower shall have paid Attorney Costs of the Administrative Agent to the extent invoiced prior to, or on, the Restatement Date.

(i)            Documents, executed by each Company that has assets or conducts business, in appropriate form for recording, where necessary, together with:

(i)            such Lien searches as the Administrative Agent shall have reasonably requested, and such termination statements or other documents as may be necessary to confirm that the Collateral is subject to no other Liens (other than Permitted Liens) in favor of any Persons;

(ii)           funds sufficient to pay any filing or recording tax or fee in connection with any and all UCC-1 financing statements or UCC-3 amendment financing statements, or fees associated with the filing of the Mortgages or amendments or supplements to Mortgages;

(iii)          evidence that the Administrative Agent has been named as loss payee under all policies of casualty insurance pertaining to the Collateral;

(iv)          such consents, estoppels, subordination agreements and other documents and instruments executed by landlords and other Persons party to material contracts relating to any Collateral as to which the Administrative Agent shall be granted a Lien for the benefit of the Lenders, as requested by the Administrative Agent or any Lender;

(v)           certificates evidencing all of the issued and outstanding shares of capital stock, partnership interests, or membership interests pledged pursuant thereto, which certificates shall in each case be accompanied by undated stock powers duly executed in blank, or, if any securities pledged pursuant thereto are uncertificated securities, confirmation and evidence satisfactory to the Administrative Agent that the security interest in such uncertificated securities has been transferred to and perfected by the Administrative Agent for the benefit of the Lenders in accordance with the Uniform Commercial Code; and

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(vi)          evidence that all other actions necessary or, in the opinion of the Administrative Agent or the Lenders, desirable to perfect and protect the first priority Lien created by the Collateral Documents (except to the extent otherwise permitted hereunder), and to enhance the Administrative Agent’s ability to preserve and protect its interests in and access to the Collateral, have been taken.

(j)            The Administrative Agent’s receipt (with sufficient copies for all Lenders) of the certificate of formation of the Borrower, together with all amendments, certified by an appropriate governmental officer in its jurisdiction of organization, as well as any other information required by Section 326 of the USA Patriot Act or necessary for the Administrative Agent or any Lender to verify the identity of Borrower as required by Section 326 of the USA Patriot Act.

(k)           The Administrative Agent’s receipt of executed copies of (together with all exhibits, schedules and annexes thereto) (i) the ACET PSA, (ii) the ACET Gas Processing Agreements, (iii) the ACET Gas Gathering Agreements, (iv) the ACET Assumed Guaranty, (v) the ACET Construction Agreement, (vi) the ACET/NGPL Contracts and (i) any other documents, instruments or certificates relating to the ACET Acquisition; provided, however, if the foregoing are held in escrow and cannot be delivered prior to the initial funding on or after the Restatement Conditions Effective Date, the foregoing may be delivered within ten (10) days after their release from escrow and delivery to Borrower.

The Administrative Agent shall notify the Borrower and the Lenders of the Restatement Conditions Effective Date, and such notice shall be conclusive and binding.

4.02        Conditions to all Loans and L/C Credit Extension.  The obligation of each Lender to honor any Borrowing Notice and the obligation of the L/C Issuer to issue any Letter of Credit is subject to the following conditions precedent:

(a)           The representations and warranties of the Loan Parties contained in Article V, or which are contained in any document furnished at any time under or in connection herewith, including, but not limited to the Collateral Documents, shall be true and correct in all material respects on and as of the date of such Loan is made, continued or converted, as applicable, or such Letter of Credit is issued except to the extent that such representations and warranties specifically refer to an earlier date, in which case they shall be true and correct as of such earlier date.

(b)           No Default or Event of Default shall exist or would result from such proposed Loan, continuation or conversion, or L/C Credit Extension.

(c)           The Administrative Agent and, if applicable, the L/C Issuer, shall have received a Request for Credit Extension and, if applicable, a Letter of Credit Application in accordance with the requirements hereof.

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(d)           The Administrative Agent shall have received, in form and substance reasonably satisfactory to it, such other assurances, certificates, documents or consents related to the foregoing as the Administrative Agent or the Required Lenders reasonably may require.

Each Request for Credit Extension submitted by the Borrower shall be deemed to be a representation and warranty that the conditions specified in Sections 4.02(a) and (b) have been satisfied on and as of the date of the applicable Credit Extension.

ARTICLE V.

REPRESENTATIONS AND WARRANTIES

Each of the Borrower and each of the MLP and each Subsidiary Guarantor by its execution of the Amended and Restated MLP Guaranty and Amended and Restated Subsidiary Guaranty, respectively, represents and warrants to the Administrative Agent and the Lenders that:

5.01        Existence; Qualification and Power; Compliance with Laws.  As of the Restatement Date, the Borrower is a direct wholly-owned subsidiary of the MLP and MarkWest Parent owns at least 51% of the General Partner.  MarkWest Parent, the General Partner and each Loan Party (a) is a corporation, partnership or limited liability company duly organized or formed, validly existing and in good standing under the Laws of the jurisdiction of its incorporation or organization, (b) has all requisite power and authority and all governmental licenses, authorizations, consents and approvals to own its assets, carry on its business and to execute, deliver, and perform its obligations under the Loan Documents to which it is a party, (c) is duly qualified and is licensed and in good standing under the Laws of each jurisdiction where its ownership, lease or operation of properties or the conduct of its business requires such qualification or license, and (d) is in compliance with all Laws, except in each case referred to in clause (c) or this clause (d), to the extent that failure to do so could not reasonably be expected to have a Material Adverse Effect.

5.02        Authorization; No Contravention.  The execution, delivery and performance by each Loan Party of each Loan Document to which such Person is party, have been duly authorized by all necessary corporate or other organizational action, and do not and will not: (a) contravene the terms of any of such Person’s Organization Documents; (b) conflict with or result in any breach or contravention of, or the creation of any Lien under, any material Contractual Obligation to which such Person is a party or any order, injunction, writ or decree of any Governmental Authority to which such Person or its property is subject; or (c) violate any Law.

5.03        Governmental Authorization.  No approval, consent, exemption, authorization, or other action by, or notice to, or filing with, any Governmental Authority, except for the filings of mortgages and lien notices in connection with the granting of security interests pursuant to the Collateral Documents, is necessary or required in connection with the execution, delivery or performance by, or enforcement against, any Loan Party of this Agreement or any other Loan Document.

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5.04        Binding Effect.  This Agreement has been, and each other Loan Document, when delivered hereunder, will have been duly executed and delivered by each Loan Party that is party thereto.  This Agreement constitutes, and each other Loan Document when so delivered will constitute, a legal, valid and binding obligation of such Loan Party, enforceable against each Loan Party that is party thereto in accordance with its terms.

5.05        Financial Statements; No Material Adverse Effect.

(a)           The audited financial statements delivered to the Lenders were prepared in accordance with GAAP consistently applied throughout the period covered thereby, except as otherwise expressly noted therein.  Such financial statements: (i) fairly present the financial condition of the entities therein named and their respective Subsidiaries as of the date thereof and their results of operations for the period covered thereby in accordance in all material respects with GAAP consistently applied throughout the period covered thereby, except as otherwise expressly noted therein; and (ii) show all material indebtedness and other liabilities, direct or contingent, of the entities therein named and their Subsidiaries as of the date thereof, including liabilities for taxes, material commitments and Indebtedness in accordance with GAAP consistently applied throughout the period covered thereby.

(b)           Since March 31, 2004, there has been no event or circumstance that has or could reasonably be expected to have a Material Adverse Effect.

5.06        Litigation.  There are no actions, suits, proceedings, claims or disputes pending or, to the knowledge of the MLP or the Borrower threatened or contemplated in writing, at law, in equity, in arbitration or before any Governmental Authority, by or against the Borrower or any Borrower Affiliate or against any of their properties or revenues which (a) seek to affect or pertain to this Agreement or any other Loan Document, the borrowing of Loans, the use of the proceeds thereof, or the issuance of Letters of Credit hereunder, or (b) if determined adversely, could reasonably be expected to have a Material Adverse Effect.

5.07        No Default.  Neither the Borrower nor any Borrower Affiliate is in default under or with respect to any Contractual Obligation which could be reasonably expected to have a Material Adverse Effect.  No Default or Event of Default has occurred and is continuing or would result from the consummation of the transactions contemplated by this Agreement or any other Loan Document.  There is no default under any Material Agreement.

5.08        Ownership of Property; Liens.  From and after the Restatement Date, (a) each Loan Party and its Subsidiaries have good title to, or valid leasehold interests in, all its real and personal property necessary or used in the ordinary conduct of its business, except for such defects in title as would not, individually or in the aggregate, have a Material Adverse Effect, and (b) the property of the MLP, the Borrower and their respective Subsidiaries is subject to no Liens, other than Permitted Liens.

5.09        Environmental Compliance.  The MLP and the Borrower have reasonably concluded that (a) there are no claims alleging potential liability under or responsibility for

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violation of any Environmental Law except any such claims that could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect, (b) there is no environmental condition or circumstance, such as the presence or Release of any Hazardous Substance, on any property owned, operated or used the Borrower or any Borrower Affiliate that could reasonably be expected to have a Material Adverse Effect, and (c) there is no violation of or by the Borrower or any Borrower Affiliate of any Environmental Law, except for such violations as could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect.

5.10        Insurance.  The properties of the Borrower and the Borrower Affiliates are insured with financially sound and reputable insurance companies not Affiliates of the Borrower, in such amounts, with such deductibles and covering such risks as are customarily carried by companies engaged in similar businesses and owning similar properties in localities where the Borrower or the Borrower Affiliates operate.

5.11        Taxes.  The Borrower and the Borrower Affiliates have filed all federal, state and other material tax returns and reports required to be filed, and have paid all federal, state and other material taxes, assessments, fees and other governmental charges levied or imposed upon them or their properties, income or assets otherwise due and payable, except those which are being contested in good faith by appropriate proceedings and for which adequate reserves have been provided in accordance with GAAP.  There is no proposed tax assessment against any Borrower Affiliate or any of their respective Subsidiaries that would, if made, have a Material Adverse Effect.

5.12        ERISA Compliance.  The representations and warranties set forth in this Section 5.12 shall apply only if the Borrower or an ERISA Affiliate establishes a Plan.

(a)           Each Plan is in compliance in all material respects with the applicable provisions of ERISA, the Code and other federal or state Laws except to the extent that noncompliance could not reasonably be expected to have a Material Adverse Effect.  Each Plan that is intended to qualify under Section 401(a) of the Code has received a favorable determination letter from the IRS or an application for such a letter is currently being processed by the IRS with respect thereto and, to the best knowledge of the MLP and the Borrower, nothing has occurred which would prevent, or cause the loss of, such qualification, except to the extent that nonqualification could not reasonably be expected to have a Material Adverse Effect.  The Borrower and each ERISA Affiliate have made all required contributions to each Plan subject to Section 412 of the Code, and no application for a funding waiver or an extension of any amortization period pursuant to Section 412 of the Code has been made with respect to any Plan, except to the extent that nonpayment could not reasonably be expected to have a Material Adverse Effect.

(b)           There are no pending or, to the best knowledge of the MLP or the Borrower, threatened claims, actions or lawsuits, or action by any Governmental Authority, with respect to any Plan that could reasonably be expected to have a Material Adverse Effect.  Neither the MLP nor the Borrower nor any ERISA Affiliate has engaged in or knowingly permitted to occur and, to the Borrower’s and the MLP’s knowledge, no other party has engaged in or permitted to occur

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any prohibited transaction or violation of the fiduciary responsibility rules with respect to any Plan that has resulted or could reasonably be expected to result in a Material Adverse Effect.

(c)           (i)            No ERISA Event has occurred or is reasonably expected to occur that could reasonably be expected to have a Material Adverse Effect; (ii) no Pension Plan has any Unfunded Pension Liability that (when aggregated with any other Unfunded Pension Liability) has resulted or could reasonably be expected to result in a Material Adverse Effect; and (iii) neither the Borrower nor any ERISA Affiliate has engaged in a transaction that could be subject to Sections 4069 or 4212(c) of ERISA that could reasonably be expected to have a Material Adverse Effect.

5.13        Subsidiaries and other Investments.  As of the Restatement Date the Borrower will have no Subsidiaries other than those specifically disclosed in Schedule 5.13, and will have no equity investment in any other corporation or other entity other than those specifically disclosed in Schedule 5.13.  From and after the Restatement Date, the MLP has no Subsidiaries other than the Borrower and the Borrower’s Subsidiaries.

5.14        Margin Regulations; Investment Company Act; Public Utility Holding Company Act; Use of Proceeds.

(a)           Neither the Borrower nor any Borrower Affiliate is engaged nor will it engage, principally or as one of its important activities, in the business of purchasing or carrying margin stock (within the meaning of Regulation U issued by the Board), or extending credit for the purpose of purchasing or carrying margin stock.  Margin Stock constitutes less than 25% of those assets of each Loan Party which are subject to any limitation on a sale, pledge, or other restrictions hereunder.

(b)           Neither the Borrower nor any Borrower Affiliate, no Person controlling the Borrower or any Borrower Affiliate, or any Subsidiary thereof (i) is a “holding company,” or a “subsidiary company” of a “holding company,” or an “affiliate” of a “holding company”or of a “subsidiary company” of a “holding company,” within the meaning of the Public Utility Holding Company Act of 1935, or (ii) is or is required to be registered as an “investment company” under the Investment Company Act of 1940.

(c)           The Borrower will use all proceeds of Credit Extension in the manner set forth in Section 6.12.

5.15        Disclosure.  All material factual information hereto furnished by or on behalf of the Borrower in writing to the Administrative Agent or any Lender for purposes of or in connection with this Agreement, the ACET Acquisition or any transaction contemplated hereby, as modified or supplemented by other information so furnished, is true and accurate in all material respects, and such information is not, or shall not be, as the case may be, incomplete by omitting to state any material fact necessary to make such information not misleading.  All estimates and projections delivered to the Administrative Agent or any Lender were based upon information that was available at the time such estimates or projections were prepared and

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believed to be correct and upon assumptions believed to be reasonable; however, the Borrower does not warrant that such estimates and projections will ultimately prove to have been accurate.

5.16        Labor Matters.  To the Borrower’s and the MLP’s knowledge, there are no actual or threatened strikes, labor disputes, slowdowns, walkouts, or other concerted interruptions of operations that could reasonably be expected to have a Material Adverse Effect.

5.17        Compliance with Laws.  Neither the Borrower nor any Borrower Affiliate is in violation of any Laws, other than such violations which could not, individually or collectively, reasonably be expected to have a Material Adverse Effect.  Neither the Borrower nor any Borrower Affiliate has received notice alleging any noncompliance with any Laws, except for such noncompliance which no longer exists, or which non-compliance could not reasonably be expected to have a Material Adverse Effect.

5.18        Third Party Approvals.  No approval, consent, exemption, authorization, or other action by, or notice to, or filing with, any party that is not a party to this Agreement is necessary or required in connection with the execution, delivery or performance by, or enforcement against, any Loan Party of this Agreement or any other Loan Document except where obtained or where the failure to receive such approval, consent, exemption, authorization, or the failure to do such other action by, or provide such notice could not reasonably be expected to have a Material Adverse Effect; and provided, however, that the transfer of rights in certain Collateral consisting of rights under contracts to a foreclosure purchaser may, in some instances, require the consent of third parties who have rights in such Collateral

5.19        Solvency.  Neither the Borrower and its Subsidiaries on a consolidated basis nor the MLP and its Subsidiaries on a consolidated basis are “insolvent” as such term is used and defined in (i) the United States Bankruptcy Code or (ii) the Texas Uniform Fraudulent Transfer Act, Tex. Bus. & Com. Code Ann. §24.003.

5.20        Collateral.  (a) The provisions of each of the Collateral Documents are effective to create in favor of the Administrative Agent for the benefit of the Lenders, a legal valid and enforceable first priority security interest in all right, title and interest of each Company in the Collateral described therein, except as otherwise permitted hereunder; and financing statements have been filed in the offices in all of the jurisdictions listed in the schedule to all Security Agreements and Mortgages.

(b)           All representations and warranties of each Loan Party thereto contained in the Collateral Documents are true and correct in all material respects.

(c)           None of the terms or provisions of any indenture, mortgage, deed of trust, agreement or other instrument to which the Borrower or any Borrower Affiliate is a party or by which the Borrower or any Borrower Affiliate or the property of the Borrower or any Borrower Affiliate is bound prohibit the filing or recordation of any of the Loan Documents or any other action which is necessary or appropriate in connection with the perfection of the Liens on material assets evidenced and created by any of the Loan Documents.

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ARTICLE VI.

AFFIRMATIVE COVENANTS

So long as any Lender shall have any Commitment hereunder, or any Loan or other Obligation shall remain unpaid or unsatisfied, or any Letter of Credit shall remain outstanding, each of the Borrower and the MLP shall, and shall cause each of their Subsidiaries to:

6.01        Financial Statements.  Deliver to the Administrative Agent and each Lender, in form and detail reasonably satisfactory to the Administrative Agent and the Required Lenders:

(a)           as soon as available, but in any event within 90 days after the end of each fiscal year of the MLP, consolidated balance sheets of the MLP and its Subsidiaries as at the end of such fiscal year, and the related statements of income and cash flows for such fiscal year, setting forth in each case in comparative form the figures for the previous fiscal year of the MLP, if any, all in reasonable detail, audited and accompanied by a report and opinion of PriceWaterhouseCoopers LLP or other independent certified public accountant of nationally recognized standing reasonably acceptable to the Required Lenders, which report and opinion shall be prepared in accordance with GAAP and shall not be subject to any qualifications or exceptions as to the scope of the audit nor to any qualifications and exceptions not reasonably acceptable to the Required Lenders;

(b)           as soon as available, but in any event within 45 days after the end of each of the first three fiscal quarters of each fiscal year of the MLP, an unaudited consolidated balance sheet of the MLP and its Subsidiaries as at the end of such fiscal quarter, and the related statements of income and cash flows for such fiscal quarter and for the portion of the MLP’s fiscal year then ended, setting forth in each case in comparative form the figures for the corresponding fiscal quarter of the previous fiscal year of the MLP and the corresponding portion of the previous fiscal year of the MLP, all in reasonable detail and certified by a Responsible Officer of the Borrower, as applicable, as fairly presenting the financial condition, results of operations and cash flows of the MLP and its Subsidiaries in accordance with GAAP, subject only to normal year-end audit adjustments and the absence of footnotes;

(c)           within 45 days after the end of each Fiscal Year, Borrower shall deliver a one year projection/budget for the MLP for the year following such Fiscal Year.

6.02        Certificates; Other Information.  Deliver to the Administrative Agent and each Lender, in form and detail satisfactory to the Administrative Agent and the Required Lenders:

(a)           concurrently with the delivery of the financial statements referred to in Sections 6.01(a) and (b), a duly completed Compliance Certificate in form of Exhibit C signed by a Responsible Officer of the Borrower and a Responsible Officer of the MLP;

(b)           promptly after the same are available, copies of each annual report, proxy or financial statement or other report or written communication sent to the equity owners of the MLP, and copies of all annual, regular, periodic and special reports and registration statements

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which the MLP may file or be required to file with the Securities and Exchange Commission under Section 13 or 15(d) of the Securities Exchange Act of 1934, and not otherwise required to be delivered to the Administrative Agent pursuant hereto;

(c)           promptly after execution thereof, copies of Material Agreements and any material amendment thereto; and

(d)           promptly, such additional information regarding the business, financial or corporate affairs of any Loan Party as the Administrative Agent, at the request of any Lender, may from time to time reasonably request, which information may include copies of any detailed audit reports, if any, management letters or recommendations submitted to the board of directors (or the audit committee of the board of directors) of the Borrower by independent accountants in connection with the accounts or books of the Borrower or any Subsidiary, or any audit of any of them.

6.03        Notices.  Promptly notify the Administrative Agent and each Lender:

(a)           of the occurrence of any Default or Event of Default, as soon as possible but in any event within ten (10) days after the occurrence thereof;

(b)           of any matter that has resulted or could reasonably be expected to result in a Material Adverse Effect, including any of the following events if such has resulted or could reasonably be expected to result in a Material Adverse Effect: (i) breach or non-performance of, or any default under, a Contractual Obligation of any Loan Party; (ii) any litigation, investigation by or required by a Governmental Authority, proceeding or suspension of licenses or permits between any Loan Party and any Governmental Authority; (iii) any dispute, litigation, investigation or proceeding involving any Loan Party related to any Environmental Law;

(c)           of any litigation, investigation or proceeding known to and affecting the Borrower or any Borrower Affiliate in which (i) the amount involved exceeds (individually or collectively) $3,500,000, or (ii) injunctive relief or other relief is sought, which could be reasonably expected to have a Material Adverse Effect; and

(d)           of any material change in accounting policies or financial reporting practices by the Borrower or the MLP.

Each notice pursuant to this Section shall be accompanied by a statement of a Responsible Officer of the Borrower setting forth details of the occurrence referred to therein and stating what action the Borrower has taken and proposes to take with respect thereto.  Each notice pursuant to Section 6.03(a) shall describe with particularity any and all provisions of this Agreement or other Loan Document that have been breached.

6.04        Payment of Obligations.  Pay and discharge as the same shall become due and payable, all its obligations and liabilities, including (a) the Obligations, (b) all tax liabilities, assessments and governmental charges or levies upon it or its properties or assets and (c) all

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lawful claims which, if unpaid, would by law become a Lien upon its property; except, in the case of clause (b) or (c), where (x) the validity thereof are being contested in good faith by appropriate proceedings and (y) adequate reserves in accordance with GAAP are being maintained by the appropriate Loan Party.

6.05        Preservation of Existence, Etc. (a) Preserve, renew and maintain in full force and effect its legal existence and good standing under the Laws of the jurisdiction of its organization, except in a transaction permitted by Sections 7.06 and 7.07, (b) take all reasonable action to maintain all rights, privileges, permits, licenses and franchises material to the conduct of its business, except in a transaction permitted by Sections 7.06 and 7.07.

6.06        Maintenance of Assets and Business.  (a) Maintain all material properties, equipment, licenses, permits, and franchises necessary for its normal business; (b) keep all of its assets which are useful in and necessary to its business in good working order and condition (ordinary wear and tear excepted) and make all necessary repairs thereto and replacements thereof; (c) do all things necessary to obtain, renew, extend, and continue in effect all Authorizations which may at any time and from time to time be necessary for the operation of its business in compliance with applicable Law, except where the failure to so maintain, renew, extend, or continue in effect could not reasonably be expected to have a Material Adverse Effect; (d) preserve or renew all of its registered patents, trademarks, trade names and service marks, the non-preservation of which could reasonably be expected to have a Material Adverse Effect; and (e) use the standard of care typical in the industry in the operation and maintenance of its facilities.

6.07        Maintenance of Insurance.  (a) Maintain with responsible insurance companies insurance with respect to its properties and business (including business interruption insurance) against such casualties and contingencies and of such types and in such amounts as is customary in the case of similar businesses and which is satisfactory to the Administrative Agent and the Required Lenders and will (i) furnish to the Administrative Agent on each anniversary of the Restatement Date a certificate or certificates of insurance from the applicable insurance company evidencing the existence of insurance required to be maintained by this Agreement and the other Loan Documents and evidencing that Administrative Agent is listed as sole loss payee on property insurance (except as to properties owned by MarkWest Parent or a Subsidiary of MarkWest Parent (other than the MLP and its Subsidiaries) and the Administrative Agent and Lenders are additional insureds on liability insurance, and (ii) upon request of the Administrative Agent, furnish to each Lender at reasonable intervals a certificate of an Authorized Officer of the Borrower setting forth the nature and extent of all insurance maintained in accordance with this Section.

(b)           (i) Except as the Administrative Agent may otherwise consent to in writing, Borrower will, and will cause each of its Subsidiaries to, forthwith upon receipt, transmit and deliver to the Administrative Agent, in the form received, all cash, checks, drafts, chattel paper and other instruments or writings for the payment of money (properly endorsed, where required, so that such items may be collected by the Administrative Agent) which may be received by the Borrower at any time in full or partial payment of amounts due under any insurance policy.

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Except as the Administrative Agent may otherwise consent in writing, any such items which may be received by the Borrower will not be commingled with any other of its funds or property, but will be held separate and apart from its own funds or property and upon express trust for the Administrative Agent until delivery is made to the Administrative Agent.  Borrower will comply with the terms and conditions of any consent given by the Administrative Agent pursuant to the provisions of this paragraph.

All items or amounts in excess of $250,000 which are delivered by the Borrower or by any insurance company to the Administrative Agent on account of partial or full payment of amounts due under any insurance policy shall be deposited to the credit of a deposit account (herein called the “Insurance Deposit Account”) of the Borrower with the Administrative Agent, as security for payment of the Obligations.  Borrower shall have no right to withdraw any funds deposited in the Insurance Deposit Account.  Administrative Agent will apply all or any of the then balance in the Insurance Deposit Account toward payment of the Obligations, in such order of application as the Administrative Agent may determine.  Administrative Agent may, from time to time, in its reasonable discretion and with the consent of the Required Lenders, release all or any of such balance representing collected funds to the Borrower.  Administrative Agent is authorized to endorse, in the name of the Borrower, any item, howsoever received by the Administrative Agent, representing any payment under any insurance policy.

(ii)           The Borrower hereby grants to the Administrative Agent, for the benefit of the Lenders, a lien on and security interest in and to such account and all monies, cash, checks, drafts, certificates of deposit, instruments, investment property, and other items ever received by Administrative Agent for deposit therein and held therein, as security for the Obligations.  The rights granted by this Section 6.07 shall be in addition to the rights of the Administrative Agent under any statutory banker’s Lien or the common law right of setoff.

6.08        Compliance with Laws and Contractual Obligations.  (a) Comply in all material respects with the requirements of all Laws (including Environmental Laws) applicable to it or to its business or property, except in such instances in which (i) such requirement of Law is being contested in good faith or a bona fide dispute exists with respect thereto, or (ii) the failure to comply therewith could not be reasonably expected to have a Material Adverse Effect; and (b) comply with all Contractual Obligations, except the failure to comply therewith could not be reasonably expected to have a Material Adverse Effect.

6.09        Books and Records.  Maintain (a) proper books of record and account, in which full, true and correct entries in conformity with GAAP consistently applied shall be made of all financial transactions and matters involving its assets and business, and (b) maintain such books of record and account in material conformity with all applicable requirements of any Governmental Authority having regulatory jurisdiction over it.

6.10        Inspection Rights.  Permit representatives and independent contractors of the Administrative Agent and each Lender to visit and inspect any of its properties, to examine its corporate, financial and operating records, and make copies thereof or abstracts therefrom, and to discuss its affairs, finances and accounts with its directors, officers, and independent public

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accountants, at such reasonable times during normal business hours and as often as may be reasonably desired, upon reasonable advance notice to the Borrower; provided, however, that when an Event of Default exists the Administrative Agent or any Lender (or any of their respective representatives or independent contractors) may do any of the foregoing at the expense of the Borrower at any time during normal business hours and without advance notice.  Additionally, Administrative Agent may, at the request of the Required Lenders, conduct or cause to be conducted a commercial field examination of the Borrower’s and its Subsidiaries’ financial and accounting records and Borrower shall pay the cost of such commercial field examination if such field examination occurs after the occurrence and during the continuation of an Event of Default.

6.11        Compliance with ERISA.  With respect to each Plan maintained by a Company, do each of the following: (a) maintain each Plan in compliance in all material respects with the applicable provisions of ERISA, the Code and other federal or state Laws, (b) cause each Plan which is qualified under Section 401(a) of the Code to maintain such qualification; and (c) make all required contributions to any Plan subject to Section 412 of the Code, except to the extent that noncompliance, with respect to each event listed above, could not be reasonably expected to have a Material Adverse Effect

6.12        Use of Proceeds.  Use proceeds of:

(a)           the Term Loan Facility to (i) refinance the Borrower’s Indebtedness outstanding under the First Amended and Restated Credit Agreement and (ii) finance the ACET Acquisition (but no portion of any Term Loan may be used to finance acquired working capital in connection with the ACET Acquisition);

(b)           the Revolver Facility to (i) refinance the Borrower’s Indebtedness outstanding under the First Amended and Restated Credit Agreement, (ii) finance the ACET Acquisition provided that on the day immediately following the ACET Acquisition Borrower must have a minimum of $25,000,000 in Revolver Loan availability (inclusive of any L/C Obligations unrelated to the ACET Acquisition)), (iii) finance working capital requirements and other general corporate purposes of the Borrower and its Subsidiaries, (iv) finance Permitted Acquisitions (other than the ACET Acquisition) and Capital Expenditures by the Borrower and its Subsidiaries of Persons or assets subject to compliance with this Agreement, including Sections 7.02 and 7.10, (v) fund Quarterly Distributions to the extent permitted by Sections 7.08(b) and (c) in an amount not to exceed during any twelve consecutive month period the product obtained by multiplying the total number of MLP common and subordinated units outstanding by $0.50, and (vi) pay fees, costs and expenses owed pursuant to this Agreement.

6.13        Material Agreements.  Enforce the obligations of MarkWest contained in the indemnification provisions of the Omnibus Agreement, and enforce all other obligations of the MarkWest Parties contained in the Material Agreements to the same extent as they would enforce similar obligations of unrelated third parties.

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6.14        Clean Down Period.  Prior to the Revolver Maturity Date, there shall be a period of fifteen (15) consecutive days (the “Clean Down Period”) during which (a) there are no Distribution Loans outstanding, and (b) no Distribution Loans will be made.

6.15        Guaranties.  As an inducement to the Administrative Agent and Lenders to enter into this Agreement, the MLP and each Subsidiary that executed a Guaranty pursuant to the Original Credit Agreement or the First Amended and Restated Credit Agreement shall execute an amended and restated Guaranty in connection with this Agreement, in the substantially in the form and upon the terms of Exhibit E-1 and Exhibit E-2, respectively.  In addition, at the time of the formation or acquisition of any Subsidiary of the Borrower or MLP, cause such Subsidiary to execute and deliver to the Administrative Agent (a) a Guaranty substantially in the form and upon the terms of Exhibit E-2, providing for the guaranty of payment and performance of the Obligations, (b) Collateral Documents in form and substance satisfactory to the Administrative Agent creating liens and security interests in all assets and properties of such Subsidiary and in the equity interests in such Subsidiary, and (c) certified copies of such Subsidiary’s Organization Documents and opinions of counsel with respect to such Subsidiary and such Guaranty, and (d) such other documents and instruments as may be required with respect to such Subsidiary pursuant to Section 6.16.

6.16        Further Assurances; Additional Collateral.  (a) The Borrower and the MLP shall cause the MLP and each Subsidiary of the Borrower or the MLP to take such actions and to execute and deliver such documents and instruments as the Administrative Agent shall require to ensure that the Administrative Agent on behalf of the Lenders shall, at all times, have received currently effective duly executed Loan Documents granting Liens and security interests in substantially all of the assets of the MLP and each Subsidiary of the Borrower and the MLP, including all capital stock, partnership, joint venture, membership interests, or other equity interests; provided, however that (i) MarkWest Energy Appalachia, L.L.C.  shall not be required to grant a Lien on its interests in the Equitable Leases, and (ii) unless otherwise requested by the Administrative Agent acting upon the direction of the Required Lenders, neither MW Pinnacle, MW PNG, MW Texas PNG nor MW Blackhawk shall be required to grant a Lien on any of their assets, other than assets constituting part of or related to the lateral pipeline transmission systems located in Texas, and the Appleby and Brahaney gas gathering, compressor and processing pipeline systems, as applicable.

(b)           In connection with the actions required pursuant to the foregoing subsection (a), the Borrower and the MLP shall cause the MLP and each Subsidiary of the Borrower and the MLP to execute and deliver such stock certificates, blank stock powers, evidence of corporate authorization, opinions of counsel, current valuations, evidence of title, title opinions, title insurance and other documents, and shall use commercially reasonable efforts to obtain landlord and mortgagee waivers and third party consents, as shall be requested by the Administrative Agent, in each case in form and substance satisfactory to the Administrative Agent.

(c)           The Liens required by this Section 6.16 shall be first priority perfected Liens in favor of the Administrative Agent for the benefit of the Lenders, subject to no other Liens except Permitted Liens of the type described in Section 7.01 (other than Section 7.01(h)).  If the

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Administrative Agent shall determine that, as of any date, the Borrower or the MLP shall have failed to comply with this Section 6.16, the Administrative Agent may (and at the direction of the Required Lenders, shall) notify the Borrower in writing of such failure and, within 30 days from and after receipt of such written notice by the Borrower, the Borrower shall execute and deliver to the Administrative Agent supplemental or additional Loan Documents, in form and substance satisfactory to the Administrative Agent and its counsel, securing payment of the Notes and the other Obligations and covering additional assets and properties not then encumbered by any Loan Documents (together with such other information, as may be requested by the Administrative Agent, each of which shall be in form and substance reasonably satisfactory to the Administrative Agent) such that the Administrative Agent shall have received currently effective duly executed and perfected Collateral Documents encumbering substantially all of the assets of the MLP, Borrower and their respective Subsidiaries as required by Section 6.16(a).

ARTICLE VII.

NEGATIVE COVENANTS

So long as any Lender shall have any Commitment hereunder, or any Loan or other Obligations shall remain unpaid or unsatisfied, or any Letter of Credit shall remain outstanding, each of the MLP and the Borrower agree that they shall not, nor shall they permit any of their respective Subsidiaries to, directly or indirectly:

7.01        Liens.  Create, incur, assume or suffer to exist, any Lien upon any of its property, assets or revenues, whether now owned or hereafter acquired, other than the following:

(a)           Liens pursuant to any Loan Document;

(b)           Liens existing on the Restatement Conditions Effective Date and listed on Schedule 7.01 to this Agreement and any renewals or extensions thereof; provided that the property covered thereby is not increased, the amount of the Indebtedness secured thereby is not increased, and any renewal or extension of the obligations secured or benefitted thereby is permitted under this Agreement;

(c)           Liens for taxes not yet due or which are being contested in good faith and by appropriate proceedings, if adequate reserves with respect thereto are maintained on the books of the applicable Person in accordance with GAAP;

(d)           carriers’, warehousemen’s, mechanics’, materialmen’s, repairmen’s or other like Liens arising in the ordinary course of business which are not overdue for a period of more than 30 days or which are being contested in good faith and by appropriate proceedings, if adequate reserves with respect thereto are maintained on the books of the applicable Person;

(e)           pledges or deposits in the ordinary course of business in connection with workers’ compensation, unemployment insurance and other social security legislation, other than any Lien imposed by ERISA;

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(f)            deposits to secure the performance of bids, trade contracts (other than for borrowed money), leases, statutory obligations, surety and appeal bonds, performance bonds and other obligations of a like nature, in each case incurred in the ordinary course of business;

(g)           easements, rights-of-way, restrictions and other encumbrances affecting real property which do not, taken as a whole, materially detract from the value of the Mortgaged Properties subject thereto or materially interfere with the ordinary conduct of the business of the applicable Person;

(h)           judgment Liens not giving rise to an Event of Default;

(i)            any Lien existing (A)on any asset acquired by MW Energy pursuant to the ACET Acquisition, such Liens, to the knowledge of Borrower, are listed on Schedule 7.01 to this Agreement and (B) on any asset (other than stock of a Subsidiary) prior to acquisition thereof by the Borrower or a Subsidiary, and not created in contemplation of such acquisition; provided that (i) no such Lien shall be extended to cover property other than the asset being acquired, (ii) such Lien was not created in contemplation of or in connection with such acquisition, (iii) the Indebtedness thereby secured is permitted by Section 7.04(e) or 7.04(h);

(j)            Liens securing Capitalized Lease obligations; provided that the Indebtedness in respect of such Capitalized Lease is permitted under Section 7.04(e);

(k)           Purchase money Liens upon or in any property acquired by Borrower or any of its Subsidiaries to secure the deferred portion of the purchase price of such property or to secure Indebtedness incurred to finance the acquisition of such property; provided that (i) no such Lien shall be extended to cover property other than the property being acquired, and (ii) the Indebtedness thereby secured is permitted by Section 7.04(e);

(l)            Liens reserved in or exercisable under any lease or sublease to which the Borrower or a Subsidiary is a lessee which secure the payment of rent or compliance with the terms of such lease or sublease; provided, that the rent under such lease or sublease is not then overdue and the Borrower or Subsidiary is in material compliance with the terms and conditions thereof;

(m)          any interest or title of a lessor under any lease entered into by the Borrower or any Subsidiary in the ordinary course of its business and covering only the assets so leased; and

(n)           Liens incurred in the ordinary course of business in connection with margin requirements under Lender Hedging Agreements not to exceed in the aggregate $3,000,000 at any time outstanding.

7.02        Investments.  Make or own any Investments, except:

(a)           Investments existing on the Restatement Date and listed in Section (b) of Schedule 5.13;

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(b)           Cash Equivalents;

(c)           Investments constituting Indebtedness permitted under Section 7.04(b);

(d)           Investments by the MLP in the Borrower;

(e)           Investments by the Borrower and its Subsidiaries in any Subsidiary of the Borrower that, prior to such Investment, is a Guarantor;

(f)            Acquisition of assets by the Borrower prior to the Restatement Date;

(g)           trade accounts receivable which are for goods furnished or services rendered in the ordinary course of business; and

(h)           Permitted Acquisitions by the Borrower or its Subsidiaries.

7.03        Hedging Agreements.  Enter into any Swap Contracts other than in the ordinary course of business for the purpose of protecting against fluctuations in interest rates, commodity prices, or foreign exchange rates and not for purposes of speculation; provided that the Swap Contract shall not contain any provision exonerating the non-defaulting party from its obligation to make payments on outstanding transactions to the defaulting party.

7.04        Indebtedness.

Create, incur, or assume any Indebtedness except:

(a)           Indebtedness incurred pursuant to the Loan Documents;

(b)           Indebtedness owed by a Subsidiary to the Borrower or to a Wholly-Owned Subsidiary or by the Borrower to a Wholly-Owned Subsidiary of the Borrower; provided, that, in each such case such Indebtedness is evidenced by a promissory note which has been pledged to secure the Obligations and is in the possession of the Administrative Agent;

(c)           Other Indebtedness of the Borrower and the MLP (“Subordinated Indebtedness”) subordinated to the Obligations pursuant to a subordination agreement in form and substance satisfactory to the Administrative Agent in its sole discretion (a “Subordination Agreement”), provided that such Subordinated Indebtedness shall bear a market rate of interest and shall not require any payment of principal earlier than June 30, 2005;

(d)           Obligations (contingent or otherwise) of the Borrower, the MLP or any Subsidiary (other than MW Texas PNG, MW PNG, and MW Blackhawk) existing or arising under any Swap Contract to the extent permitted by Section 7.03;

(e)           Indebtedness of the MLP, the Borrower and their respective Subsidiaries (other than MW Texas PNG, MW PNG, and MW Blackhawk) in respect of purchase money obligations for fixed or capital assets within the limitations set forth in Section 7.01(k); provided,

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however, that the aggregate amount of such Indebtedness at any one time outstanding shall not exceed $7,500,000;

(f)            Other Indebtedness of the MLP, the Borrower and their respective Subsidiaries (other than MW Texas PNG, MW PNG and MW Blackhawk) not to exceed $7,500,000 in the aggregate principal amount outstanding at any time;

(g)Indebtedness assumed by the MLP pursuant to the ACET Assumed Guaranty;

(h)           Indebtedness assumed by MW Energy pursuant to the ACET PSA, which Indebtedness is listed on Schedule 7.04 to this Agreement not to exceed $2,000,000; and

(i)Refinancing Indebtedness;

Provided, that if any Indebtedness is incurred pursuant to this Section 7.04, both before and after such Indebtedness is created, incurred or assumed, no Default or Event of Default shall exist.

7.05        Lease Obligations.  Create or suffer to exist any obligations for the payment of rent for any property under lease or agreement to lease, except for operating leases (other than those constituting Synthetic Lease Obligations) entered into or assumed by the Borrower or any Subsidiary in the ordinary course of business prior to the Restatement Conditions Effective Date and those leases assumed in connection with the ACET Acquisition to the listed on Schedule 7.05 to this Agreement or after the date of this Agreement entered into or assumed in connection with any Permitted Acquisition; provided that, such operating leases will not require the payment of an aggregate amount of payments in excess of (excluding escalations resulting from a rise in the consumer price or similar index) $7,500,000 during the full remaining term of such Leases, exclusive of expenses for maintenance, repairs, insurance taxes, assessments and similar changes.

7.06        Fundamental Changes.  Merge or consolidate with or into, or convey, transfer, lease or otherwise Dispose of (whether in one transaction or in a series of transactions) all or substantially all of its assets (whether now owned or hereafter acquired) to or in favor of any Person; except that, so long as no Default or Event of Default exists or would result therefrom:

(a)           any Person may merge into the Borrower; provided that the Borrower is the surviving entity;

(b)           any Subsidiary may merge with (i) the Borrower; provided that the Borrower shall be the continuing or surviving Person, or (ii) any one or more Subsidiaries; provided that when any Wholly-Owned Subsidiary is merging with another Subsidiary, a Wholly-Owned Subsidiary shall be the continuing or surviving Person;

(c)           any Subsidiary may sell all or substantially all of its assets (upon voluntary liquidation or otherwise), to the Borrower or to another Subsidiary; provided that if the seller in

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such a transaction is a Wholly-Owned Subsidiary, then the purchaser must also be a Wholly-Owned Subsidiary; and

(d)           any Person (other than the Borrower or a Subsidiary of the Borrower) may merge into any Subsidiary; provided that such Subsidiary is the surviving entity.

7.07        Dispositions.

Make any Disposition or enter into any agreement to make any Disposition, except:

(a)           Dispositions by the Borrower or its Subsidiaries of inventory in the ordinary course of business;

(b)           Dispositions of property by any Subsidiary to the Borrower, or by any Subsidiary or by the Borrower, to a Wholly-Owned Subsidiary that is a Guarantor; or

(c)           other Dispositions for fair market value; provided no Default or Event of Default then exists or arises as a result thereof; and provided that if the Disposition is for cash and a prepayment is required by Section 2.04(b)(i), the Borrower shall make such prepayment in accordance with such Section.

7.08        Restricted Payments; Distributions and Redemptions.  Declare or make, directly or indirectly, any Restricted Payment, or incur any obligation (contingent or otherwise) to do so, except that:

(a)           each Subsidiary may make Restricted Payments to the Borrower and to Wholly-Owned Subsidiaries of the Borrower;

(b)           the Borrower (i) may declare and make Quarterly Distributions of Available Cash (as defined in the Limited Liability Company Agreement (Borrower)), (ii) may purchase MLP units under the MLP’s Long-Term Incentive Plan in accordance with, and as defined in, the Limited Liability Company Agreement (Borrower) and the Partnership Agreement (MLP), and (iii) any Guarantor may make redemptions of, or purchase equity interest in, the Borrower or any Guarantor from employees of the Borrower or such Guarantor; provided, that at the time each Quarterly Distribution is made or any purchase or redemption is made no Default or Event of Default exists or would result therefrom; provided further that the aggregate amount expended in any consecutive 12-month period for purchases or redemptions pursuant to clause (iii) above shall not exceed $500,000; and

(c)           the MLP may (i) declare and make Quarterly Distributions of Available Cash (as defined in the Partnership Agreement (MLP)) to the extent such Quarterly Distributions in any fiscal quarter do not exceed, in the aggregate, Available Cash as defined in the Partnership Agreement (MLP) for the immediately preceding fiscal quarter and are made in accordance with the Partnership Agreement (MLP) and (ii) purchase MLP units under the MLP’s Long-Term Incentive Plan in accordance with, and as defined in, the Partnership Agreement (MLP);

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provided, that at the time each such Quarterly Distribution or purchase is made no Default or Event of Default exists or would result therefrom.

7.09        ERISA.  At any time engage in a transaction which could be subject to Section 4069 or 4212(c) of ERISA, or permit any Plan maintained by a Company to: (a) engage in any non-exempt “prohibited transaction” (as defined in Section 4975 of the Code); (b) fail to comply with ERISA or any other applicable Laws; or (c) incur any material “accumulated funding deficiency” (as defined in Section 302 of ERISA), which, with respect to each event listed above, could be reasonably expected to have a Material Adverse Effect.

7.10        Nature of Business; Capital Expenditures; Risk Management.  Engage in any line of business other than the Midstream Business, or make any Capital Expenditures or Permitted Acquisitions permitted by Section 7.02 except in connection with the Midstream Business.  In addition to the foregoing, (a) the MLP may not engage in any business other than the ownership of the Borrower and the operation of the MLP, (b) MW Texas PNG may not engage in any business other than the ownership and operation of the Rio Nogales Pipelines, (c) MW New Mexico may not engage in any business other than the ownership and operation of the Hobbs Pipeline, (d) MW Blackhawk may not engage in any business other than the ownership and operation of the Blackhawk Pipeline, and (e) MW PNG may not engage in any business other than the ownership and operation of the Lake Whitney Pipeline.  Without the written approval of the Administrative Agent, materially change its risk management policy.

7.11        Transactions with Affiliates.  Sell, lease or otherwise transfer any property or assets to, or purchase, lease or otherwise acquire any property or assets from, or otherwise engage in any other transactions with, any of its Affiliates, except (i) transactions between or among the Borrower and its Wholly-Owned Subsidiaries not involving any other Affiliate, and (ii) any Restricted Payment permitted by Section 7.08, and (iii) in the ordinary course of business at prices and on terms and conditions not less favorable to the MLP, the Borrower or such Subsidiary, as applicable, than could be obtained on an arm’s length basis from unrelated third parties.

7.12        Burdensome Agreements.  Enter into any Contractual Obligation that limits the ability of any Subsidiary to make Restricted Payments to the Borrower or to otherwise transfer property to the Borrower.  Notwithstanding the foregoing, (i) documents governing a Capitalized Lease or a purchase money Lien permitted by Sections 7.01(j) and (k) may prohibit other Liens on the asset encumbered by such Lien, and (ii) the Lenders acknowledge that the real estate leases described on Schedule 7.12 restrict or prohibit Liens on the Borrower’s or its Subsidiary’s leasehold interest.

7.13        Use of Proceeds.  Use the proceeds of any Loan for purposes other than those permitted by Section 6.12, or use the proceeds of any Loan, whether directly or indirectly, and whether immediately, incidentally or ultimately, to purchase or carry margin stock (within the meaning of Regulation U of the Board) or to extend credit to others for the purpose of purchasing or carrying margin stock or to refund indebtedness originally incurred for such purpose.

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7.14        Material Agreements.  Permit (a) any amendment to any Borrower Operating Agreement or any Material Agreement, if such amendment could reasonably be expected to (y) have a Material Adverse Effect on the ability of the Borrower or any Guarantor to perform its obligations under the Loan Documents to which it is a party or (z) otherwise materially adversely affect the Lenders, or (b) any assignment of any Material Agreement if such assignment could reasonably be expected to materially adversely affect the Lenders or have a Material Adverse Effect on the ability of the Borrower or any other Loan Party to perform its obligations under the Loan Documents to which it is a party.

7.15        Financial Covenants.

(a)           Interest Coverage Ratio.  Permit the Interest Coverage Ratio at any time prior to December 31, 2004 to be less than the ratio of 2.0 to 1.0 or on or after December 31, 2004 to be less than the ratio of 3.0 to 1.0.

(b)           Leverage Ratio.  Permit the Leverage Ratio at any time prior to December 31, 2004 to be greater than the ratio of 6.75 to 1.0 or on or after December 31, 2004 to be greater than the ratio of 5.5 to 1.0.

(c)           Minimum Net Worth.  Permit the net worth of the Borrower to be less than the sum of (i) $125,000,000 and (ii) 50% of the net proceeds of all equity issued subsequent to the Restatement Date.

(d)           Adjustments for Permitted Acquisitions.  For purposes of determining compliance with Sections 7.15(a) and (b):

(i)            Consolidated EBITDA shall be calculated after giving effect, on a pro forma basis for the four consecutive fiscal quarters most recently completed, to any Permitted Acquisition occurring during such period, as if such Permitted Acquisition occurred on the first day of such period.

(ii)           If, in connection with a Permitted Acquisition, any Indebtedness is incurred or assumed by a Company, then Consolidated Interest Charges shall be calculated, on a pro forma basis (in a manner acceptable to the Required Lenders) for the four quarters most recently completed, as if such Indebtedness had been incurred on the first day of such period.

7.16        Counterparty Consents.  In the event that the Borrower delivers to the Administrative Agent a Counterparty Consent with respect to the Blackhawk Pipeline, Lake Whitney Pipeline or Rio Nogales Pipeline, the Borrower may, at the time of such delivery of the Counterparty Consent, request that the parentheticals set forth in Sections 7.04(d), 7.04(e), and 7.04(e), and the restrictions set forth in Section 7.10, no longer apply to the Subsidiary that owns such pipeline.  Upon receipt of such Counterparty Consent and such request, the Administrative Agent shall issue a notice to the Borrower and the Lenders declaring that from and after the

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issuance of such notice, the parenthetical set forth in Sections 7.04(d), 7.04(e), and 7.04(f), and restrictions set forth in Section 7.10, no longer apply to such Subsidiary.

7.17        Subordinated Indebtedness.  Neither the Borrower nor the MLP will amend documents governing Subordinated Indebtedness unless approved in writing by the Required Lenders (other than ministerial amendments and amendments to extend the time or times for payment).  The Borrower shall not make any payments of interest or any other amounts in respect of the Subordinated Indebtedness if a Default shall have occurred and be continuing or would result from such payment.  The Borrower will not repay any principal, interest or other indebtedness in respect of the Subordinated Indebtedness, or make any redemption or acquisition for value or defeasance, refinancing or exchange thereof or therefore, or make any payments in contravention of the applicable Subordination Agreement.

ARTICLE VIII.

EVENTS OF DEFAULT AND REMEDIES

8.01        Events of Default.  Any of the following shall constitute an Event of Default:

(a)           Non-Payment .  The Borrower fails to pay (i) any amount due under the Agent/Arranger Fee Letter when and as required to be paid therein, (ii) when and as required to be paid herein, any amount of principal of any Loan or any L/C Obligation or (iii) within three Business Days after the same becomes due, any interest on any Loan, any L/C Obligation, any commitment or other fee due hereunder (other than a fee specified in the Agent/Arranger Fee Letter), or any other amount payable hereunder or under any other Loan Document; or

(b)           Specific Covenants.  The Borrower fails to perform or observe any term, covenant or agreement contained in any of Section 6.03(a), 6.05 (with respect to the Borrower’s existence), 6.12, 6.15, 6.16, or Article VII; or

(c)           Other Defaults.  Any Loan Party fails to perform or observe any other covenant or agreement (not specified in subsection (a) or (b) above) contained in any Loan Document on its part to be performed or observed and such failure continues for 15 days after the earlier of (i) the date notice has been given to the Borrower by the Administrative Agent or a Lender or (ii) the date a Responsible Officer knew or reasonably should have known of such Default; or

(d)           Representations and Warranties.  Any representation or warranty made or deemed made by the Borrower or any other Loan Party herein, in any other Loan Document, or in any document delivered in connection herewith or therewith proves to have been incorrect in any material respect when made or deemed made; or

(e)           Cross-Default.  (i) The Borrower or any Borrower Affiliate (A) fails to make any payment when due (whether by scheduled maturity, required prepayment, acceleration, demand, or otherwise) in respect of any Indebtedness or Guaranty Obligation (other than Indebtedness under Swap Contracts) having an aggregate principal amount (or, in the case of a Capitalized Lease or a Synthetic Lease Obligation, Attributable Indebtedness) (including undrawn or

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available amounts and including amounts owing to all creditors under any combined or syndicated credit arrangement) of more than (individually or collectively) $10,000,000, or (B) fails to observe or perform any other agreement or condition relating to any such Indebtedness or Guaranty Obligation or contained in any instrument or agreement evidencing, securing or relating thereto, or any other event occurs, the effect of which default or other event is to cause, or to permit the holder or holders of such Indebtedness, the lessor under such Synthetic Lease Obligation or the beneficiary or beneficiaries of such Guaranty Obligation (or a trustee or agent on behalf of such holder or holders or beneficiary or beneficiaries) to cause, with the giving of notice if required, such Indebtedness to be demanded or to become due or to be repurchased or redeemed (automatically or otherwise) prior to its stated maturity, or such Guaranty Obligation to become payable or cash collateral in respect thereof to be demanded; or (ii) (A) there occurs under any Swap Contract an Early Termination Date (as defined in such Swap Contract) resulting from any event of default under such Swap Contract as to which the Borrower or any Borrower Affiliate is the Defaulting Party (as defined in such Swap Contract) and the Swap Termination Value owed by the Borrower or any Borrower Affiliate as a result thereof is greater than (individually or collectively) $10,000,000, or (B) there occurs under any Swap Contract an Early Termination Date (as defined in such Swap Contract) resulting from any Termination Event (as so defined) under such Swap Contract as to which the Borrower or any Borrower Affiliate is an Affected Party (as so defined) and the Early Termination Amount owed by the Borrower and Borrower Affiliate as a result thereof is greater than (individually or collectively) $10,000,000 and such amount is not paid when due under such Swap Contract; or

(f)            Insolvency Proceedings, Etc.  (i) The Borrower or any Borrower Affiliate institutes or consents to the institution of any proceeding under any Debtor Relief Law, or makes an assignment for the benefit of creditors; or applies for or consents to the appointment of any receiver, trustee, custodian, conservator, liquidator, rehabilitator or similar officer for it or for all or any material part of its property or takes any action to effect any of the foregoing; or (ii) any receiver, trustee, custodian, conservator, liquidator, rehabilitator or similar officer is appointed without the application or consent of such Person and the appointment continues undischarged or unstayed for 60 calendar days; or (iii) any proceeding under any Debtor Relief Law relating to any such Person or to all or any part of its property is instituted without the consent of such Person and continues undismissed or unstayed for 60 calendar days, or an order for relief is entered in any such proceeding; or

(g)           Inability to Pay Debts; Attachment.  (i) The Borrower or any Borrower Affiliate becomes unable or admits in writing its inability or fails generally to pay its debts as they become due, or (ii) any writ or warrant of attachment or execution or similar process is issued or levied against property which is a material part of the property of the Borrower and its Subsidiaries taken as a whole, and is not released, vacated or fully bonded within 45 days after its issue or levy; or

(h)           Judgments.  There is entered against the Borrower or any Borrower Affiliate (i) a final judgment or order for the payment of money in an aggregate amount exceeding (individually or collectively) $10,000,000 (to the extent not covered by third-party insurance as to which the insurer does not dispute coverage), or (ii) any non-monetary final judgment that has

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or could reasonably be expected to have a Material Adverse Effect and, in either case, (A) enforcement proceedings are commenced by any creditor upon such judgment or order, or (B) there is a period of 30 consecutive days during which a stay of enforcement of such judgment, by reason of a pending appeal or otherwise, is not in effect; or

(i)            ERISA.  (i) If the Borrower, any Borrower Affiliate or any of their ERISA Affiliates maintains any Pension Plan or any Multiemployer Plan, an ERISA Event occurs with respect to a Pension Plan or Multiemployer Plan which has resulted or could reasonably be expected to result in liability of the Borrower or any Borrower Affiliate under Title IV of ERISA to the Pension Plan, Multiemployer Plan or the PBGC in an aggregate amount in excess of $3,500,000, or (ii) if there is any Multiemployer Plan, the Borrower, any Borrower Affiliate or any ERISA Affiliate thereof fails to pay when due, after the expiration of any applicable grace period, any installment payment with respect to its withdrawal liability under Section 4201 of ERISA under a Multiemployer Plan in an aggregate amount in excess of $3,500,000; or

(j)            Invalidity of Loan Documents.  Any Loan Document, at any time after its execution and delivery and for any reason other than the agreement of all the Lenders or termination of all Commitments and satisfaction in full of all the Obligations, ceases to be in full force and effect, or is declared by a court of competent jurisdiction to be null and void, invalid or unenforceable in any material respect; or any Loan Party denies that it has any or further liability or obligation under any Loan Document, or purports to revoke, terminate or rescind any Loan Document; or

(k)           Change of Control.  There occurs any Change of Control; or

(l)            Dissolution.  The Borrower or any Borrower Affiliate shall dissolve, liquidate, or otherwise terminate its existence, except as permitted in Section 7.06; or

(m)          Material Agreements.  (i) Termination of any Material Agreement, or any material provision of any of the foregoing if such termination could reasonably be expected to have a Material Adverse Effect and such agreement or provision is not replaced (prior to such cessation) in a manner satisfactory to the Administrative Agent; (ii) default by any Person in the performance or observance of any material term of any Material Agreement which is not cured within the applicable cure period specified in such Material Agreement, if such default could reasonably be expected to have a Material Adverse Effect; or (iii) any event or condition occurs or exists which in the opinion of the Administrative Agent is reasonably likely to (x) have a material adverse effect on the ability of a MarkWest Party to perform its obligations under a Material Agreement and (y) result in a Material Adverse Effect hereunder; or

(n)           Collateral; Impairment of Security, etc.  (i) Any provision of any Loan Document shall for any reason cease to be valid and binding on or enforceable against a Loan Party or any Loan Party shall so state in writing or bring an action to limit its obligations or liabilities thereunder; or (ii) any Collateral Document shall for any reason (other than pursuant to the terms thereof) cease to create a valid security interest in the Collateral purported to be covered thereby

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or such security interest shall for any reason cease to be a perfected and first priority security interest subject to Permitted Liens.

8.02        Remedies Upon Event of Default.  If any Event of Default occurs, the Administrative Agent shall, at the request of, or may, with the consent of, the Required Lenders:

(a)           declare the Commitment of each Lender to make Loans and any obligation of the L/C Issuer to make L/C Credit Extensions to be terminated, whereupon such Commitments and obligations shall be terminated;

(b)           declare the unpaid principal amount of all outstanding Loans, all interest accrued and unpaid thereon, and all other amounts owing or payable hereunder or under any other Loan Document to be immediately due and payable, without presentment, demand, protest, notice of intent to accelerate, notice of acceleration or other notice of any kind, all of which are hereby expressly waived by the Borrower;

(c)           declare that an amount equal to the then Outstanding Amount of all L/C Obligations be immediately due and payable by the Borrower, without presentment, demand, protest, notice of intent to accelerate, notice of acceleration or other notice of any kind, all of which are hereby expressly waived by the Borrower, and require that the Borrower deliver such payments to the Administrative Agent to Cash Collateralize the L/C Obligations (in an amount equal to the then Outstanding Amount thereof); and

(d)           exercise on behalf of itself and the Lenders all rights and remedies available to it and the Lenders under the Loan Documents or applicable Law;

provided, however, that upon the occurrence of any event specified in subsection (f) of Section 8.01, the obligation of each Lender to make Loans and any obligation of the L/C Issuer to make L/C Credit Extensions shall automatically terminate, the unpaid principal amount of all outstanding Loans and all interest and other amounts as aforesaid shall automatically become due and payable, and an amount equal to the then Outstanding Amount of all L/C Obligations shall be deemed to be forthwith due and owing by the Borrower to the L/C Issuer and the Lenders as of the date of such occurrence and the Borrower’s obligation to pay such amounts shall be absolute and unconditional, without regard to whether any beneficiary of any such Letter of Credit has attempted to draw down all or a portion of such amount under the terms of a Letter of Credit and, to the fullest extent permitted by applicable Law, shall not be subject to any defense or be affected by a right of set-off, counterclaim or recoupment which the Borrower may now or hereafter have against any such beneficiary, the L/C Issuer, the Administrative Agent, the Lenders or any other Person for any reason whatsoever.  Such payments shall be delivered to and held by the Administrative Agent as cash collateral securing the L/C Obligations.

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ARTICLE IX.

ADMINISTRATIVE AGENT

9.01        Appointment and Authorization of Agents; Lender Hedging Agreements.  (a) Each Lender hereby irrevocably (subject to Section 9.10) appoints, designates and authorizes the Administrative Agent to take such action on its behalf under the provisions of this Agreement and each other Loan Document and to exercise such powers and perform such duties as are expressly delegated to it by the terms of this Agreement or any other Loan Document, together with such powers as are reasonably incidental thereto.  Notwithstanding any provision to the contrary contained elsewhere herein or in any other Loan Document, the Administrative Agent shall not have any duties or responsibilities, except those expressly set forth herein, nor shall the Administrative Agent have or be deemed to have any fiduciary relationship with any Lender or participant, and no implied covenants, functions, responsibilities, duties, obligations or liabilities shall be read into this Agreement or any other Loan Document or otherwise exist against the Administrative Agent.  Without limiting the generality of the foregoing sentence, the use of the term “agent” herein and in the other Loan Documents with reference to the Administrative Agent or Syndication Agent is not intended to connote any fiduciary or other implied (or express) obligations arising under agency doctrine of any applicable Law.  Instead, such term is used merely as a matter of market custom, and is intended to create or reflect only an administrative relationship between independent contracting parties.

(b)           The L/C Issuer shall act on behalf of the Lenders with respect to any Letters of Credit issued by it and the documents associated therewith until such time (and except for so long) as the Administrative Agent may agree at the request of the Required Lenders to act for the L/C Issuer with respect thereto; provided, however, that the L/C Issuer shall have all of the benefits and immunities (i) provided to the Administrative Agent in this Article IX with respect to any acts taken or omissions suffered by the L/C Issuer in connection with Letters of Credit issued by it or proposed to be issued by it and the application and agreements for letters of credit pertaining to the Letters of Credit as fully as if the term “Administrative Agent” as used in this Article IX included the L/C Issuer with respect to such acts or omissions, and (ii) as additionally provided herein with respect to the L/C Issuer.

(c)           To the extent any Lender or any Affiliate of a Lender is a party to a Lender Hedging Agreement and accepts the benefits of the Liens in the Collateral arising pursuant to the Collateral Documents, such Lender (for itself and on behalf of any such Affiliates) shall be deemed (i) to appoint the Administrative Agent, as its nominee and agent, to act for and on behalf of such Lender or Affiliate thereof in connection with the Collateral Documents and (ii) to be bound by the terms of this Article IX.

9.02        Delegation of Duties.  The Agents may execute any of its duties under this Agreement or any other Loan Document by or through agents, employees or attorneys-in-fact and shall be entitled to advice of counsel and other consultants or experts concerning all matters pertaining to such duties.  Administrative Agent shall not be responsible for the negligence or misconduct of any agent or attorney-in-fact that it selects in the absence of gross negligence or willful misconduct.

9.03        Default; Collateral.  (a) Upon the occurrence and continuance of a Default or Event of Default, the Lenders agree to promptly confer in order that Required Lenders or the

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Lenders, as the case may be, may agree upon a course of action for the enforcement of the rights of the Lenders; and the Administrative Agent shall be entitled to refrain from taking any action (without incurring any liability to any Person for so refraining) unless and until the Administrative Agent shall have received instructions from Required Lenders.  All rights of action under the Loan Documents and all right to the Collateral, if any, hereunder may be enforced by the Administrative Agent and any suit or proceeding instituted by the Administrative Agent in furtherance of such enforcement shall be brought in its name as the Administrative Agent without the necessity of joining as plaintiffs or defendants any other Lender, and the recovery of any judgment shall be for the benefit of the Lenders (and, with respect to Lender Hedging Agreements, Affiliates, if applicable) subject to the expenses of the Administrative Agent.  In actions with respect to any property of the Borrower or any other Obligor, the Administrative Agent is acting for the ratable benefit of each Lender (and, with respect to Lender Hedging Agreement, Affiliates, if applicable).  Any and all agreements to subordinate (whether made heretofore or hereafter) other indebtedness or obligations of Borrower to the Obligations shall be construed as being for the ratable benefit of each Lender (and, with respect to Lender Hedging Agreement, Affiliates, if applicable).

(b)           Each Lender authorizes and directs the Administrative Agent to enter into the Collateral Documents on behalf of and for the benefit of the Lenders (and, with respect to Lender Hedging Agreements, Affiliates, if applicable)(or if previously entered into, hereby ratifies the Administrative Agent’s previously entering into such agreements and Collateral Documents).

(c)           Except to the extent unanimity (or other percentage set forth in Section 10.1) is required hereunder, each Lender agrees that any action taken by the Required Lenders in accordance with the provisions of the Loan Documents, and the exercise by the Required Lenders of the power set forth herein or therein, together with such other powers as are reasonably incidental thereto, shall be authorized and binding upon all of the Lenders.

(d)           The Administrative Agent is hereby authorized on behalf of the Lenders, without the necessity of any notice to or further consent from any Lender, from time to time to take any action with respect to any Collateral or Collateral Documents which may be necessary to perfect and maintain perfected the Liens upon the Collateral granted pursuant to the Collateral Documents.

(e)           The Administrative Agent shall have no obligation whatsoever to any Lender or to any other Person to assure that the Collateral exists or is owned by any Obligor or is cared for, protected, or insured or has been encumbered or that the Liens granted to the Administrative Agent herein or pursuant thereto have been properly or sufficiently or lawfully created, perfected, protected, or enforced, or are entitled to any particular priority, or to exercise at all or in any particular manner or under any duty of care, disclosure, or fidelity, or to continue exercising, any of the Rights granted or available to the Administrative Agent in this Section 9.03 or in any of the Collateral Documents; it being understood and agreed that in respect of the Collateral, or any act, omission, or event related thereto, the Administrative Agent may act in any manner it may deem appropriate, in its sole discretion, given the Administrative Agent’s own interest in the Collateral as one of the Lenders and that the Administrative Agent shall have no

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duty or liability whatsoever to any Lender, other than to act without gross negligence or willful misconduct.

(f)            The Lenders hereby irrevocably authorize the Administrative Agent, at its option and in its discretion, to release any Lien granted to or held by the Administrative Agent upon any Collateral: (i) constituting property in which no Obligor owned an interest at the time the Lien was granted or at any time thereafter; (ii) constituting property leased to an Obligor under a lease which has expired or been terminated in a transaction permitted under the Loan Document or is about to expire and which has not been, and is not intended by such Obligor to be, renewed; and (iii) consisting of an instrument evidencing Indebtedness pledged to the Administrative Agent (for the benefit of the Lenders), if the Indebtedness evidenced thereby has been paid in full.  In addition, the Lenders irrevocably authorize the Administrative Agent to release Liens upon Collateral as contemplated in Section 10.01(c) or (d), or if approved, authorized, or ratified in writing by the requisite Lenders.  Upon request by the Administrative Agent at any time, the Lenders will confirm in writing the Administrative Agent’s authority to release particular types or items of Collateral pursuant to this Section 9.03.

(g)           In furtherance of the authorizations set forth in this Section 9.03, each Lender hereby irrevocably appoints the Administrative Agent its attorney-in-fact, with full power of substitution, for and on behalf of and in the name of each such Lender (i) to enter into Collateral Documents (including, without limitation, any appointments of substitute trustees under any Collateral Documents), (ii) to take action with respect to the Collateral and Collateral Documents to perfect, maintain, and preserve Lenders’ Liens, and (iii) to execute instruments of release or to take other action necessary to release Liens upon any Collateral to the extent authorized in paragraph (f) hereof.  This power of attorney shall be liberally, not restrictively, construed so as to give the greatest latitude to the Administrative Agent’s power, as attorney, relative to the Collateral matters described in this Section 9.03.  The powers and authorities herein conferred on the Administrative Agent may be exercised by the Administrative Agent through any Person who, at the time of the execution of a particular instrument, is an officer of the Administrative Agent (or any Person acting on behalf of the Administrative Agent pursuant to a valid power of attorney).  The power of attorney conferred by this Section 9.03(g) to the Administrative Agent is granted for valuable consideration and is coupled with an interest and is irrevocable so long as the Obligations, or any part thereof, shall remain unpaid or the Lenders are obligated to make any Borrowings under the Loan Documents.

9.04        Liability of Agents.  No Agent-Related Person shall (a) be liable for any action taken or omitted to be taken by any of them under or in connection with this Agreement or any other Loan Document or the transactions contemplated hereby (except for its own gross negligence or willful misconduct in connection with its duties expressly set forth herein), or (b) be responsible in any manner to any Lender or participant for any recital, statement, representation or warranty made by any Loan Party or any officer thereof, contained herein or in any other Loan Document, or in any certificate, report, statement or other document referred to or provided for in, or received by Administrative Agent under or in connection with, this Agreement or any other Loan Document, or the validity, effectiveness, genuineness, enforceability or sufficiency of this Agreement or any other Loan Document, or for the creation,

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perfection or priority of any Liens purported to be created by any of the Loan Documents, or the validity, genuineness, enforceability, existence, value or sufficiency of any collateral security, or to make any inquiry respecting the performance by the Borrower of its obligations hereunder or under any other Loan Document, or for any failure of any Loan Party or any other party to any Loan Document to perform its obligations hereunder or thereunder.  No Agent-Related Person shall be under any obligation to any Lender or participant to ascertain or to inquire as to the observance or performance of any of the agreements contained in, or conditions of, this Agreement or any other Loan Document, or to inspect the properties, books or records of any Loan Party or any Affiliate thereof.

9.05        Reliance by Administrative Agent.  (a) The Administrative Agent shall be entitled to rely, and shall be fully protected in relying, upon any writing, communication, signature, resolution, representation, notice, consent, certificate, affidavit, letter, telegram, facsimile, telex or telephone message, statement or other document or conversation believed by it to be genuine and correct and to have been signed, sent or made by the proper Person or Persons, and upon advice and statements of legal counsel (including counsel to any Loan Party), independent accountants and other experts selected by the Administrative Agent.  The Administrative Agent shall be fully justified in failing or refusing to take any action under any Loan Document unless it shall first receive such advice or concurrence of the Required Lenders as it deems appropriate and, if it so requests, it shall first be indemnified to its satisfaction by the Lenders against any and all liability and expense which may be incurred by it by reason of taking or continuing to take any such action.  The Administrative Agent shall in all cases be fully protected in acting, or in refraining from acting, under this Agreement or any other Loan Document in accordance with a request or consent of the Required Lenders or all the Lenders, if required hereunder, and such request and any action taken or failure to act pursuant thereto shall be binding upon all the Lenders and participants.  Where this Agreement expressly permits or prohibits an action unless the Required Lenders otherwise determine, the Administrative Agent shall, and in all other instances, the Administrative Agent may, but shall not be required to, initiate any solicitation for the consent or a vote of the Lenders.

(b)           For purposes of determining compliance with the conditions specified in Section 4.01, each Lender that has funded its Pro Rata Share of the Borrowing(s) on the Restatement Conditions Effective Date (or, if there is no Borrowing made on such date, each Lender other than Lenders who gave written objection to the Administrative Agent prior to such date) shall be deemed to have consented to, approved or accepted or to be satisfied with, each document or other matter either sent by the Administrative Agent to such Lender for consent, approval, acceptance or satisfaction, or required hereunder to be consented to or approved by or acceptable or satisfactory to a Lender.

9.06        Notice of Default.  The Administrative Agent shall not be deemed to have knowledge or notice of the occurrence of any Default or Event of Default, except with respect to defaults in the payment of principal, interest and fees required to be paid to the Administrative Agent for the account of the Lenders, unless the Administrative Agent shall have received written notice from a Lender or the Borrower referring to this Agreement, describing such Default or Event of Default and stating that such notice is a “notice of default.” The

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Administrative Agent will notify the Lenders of its receipt of any such notice.  The Administrative Agent shall take such action with respect to such Default or Event of Default as may be directed by the Required Lenders in accordance with Article VIII; provided, however, that unless and until the Administrative Agent has received any such direction, the Administrative Agent may (but shall not be obligated to) take such action, or refrain from taking such action, with respect to such Default or Event of Default as it shall deem advisable or in the best interest of the Lenders.

9.07        Credit Decision; Disclosure of Information by Administrative Agent.  Each Lender acknowledges that no Agent-Related Person has made any representation or warranty to it, and that no act by the Administrative Agent hereinafter taken, including any consent to and acceptance of any assignment or review of the affairs of any Loan Party or any Affiliate thereof, shall be deemed to constitute any representation or warranty by any Agent-Related Person to any Lender as to any matter, including whether Agent-Related Persons have disclosed material information in their possession.  Each Lender represents to the Administrative Agent that it has, independently and without reliance upon any Agent-Related Person and based on such documents and information as it has deemed appropriate, made its own appraisal of and investigation into the business, prospects, operations, property, financial and other condition and creditworthiness of the Loan Parties and their respective Subsidiaries, and all applicable bank or other regulatory Laws relating to the transactions contemplated hereby, and made its own decision to enter into this Agreement and to extend credit to the Borrower hereunder.  Each Lender also represents that it will, independently and without reliance upon any Agent-Related Person and based on such documents and information as it shall deem appropriate at the time, continue to make its own credit analysis, appraisals and decisions in taking or not taking action under this Agreement and the other Loan Documents, and to make such investigations as it deems necessary to inform itself as to the business, prospects, operations, property, financial and other condition and creditworthiness of the Borrower and the other Loan Parties.  Except for notices, reports and other documents expressly required to be furnished to the Lenders by the Administrative Agent herein, the Administrative Agent shall not have any duty or responsibility to provide any Lender with any credit or other information concerning the business, prospects, operations, property, financial and other condition or creditworthiness of any of the Loan Parties or any of their respective Affiliates which may come into the possession of any Agent Related Person.

9.08        Indemnification of Agents.  Whether or not the transactions contemplated hereby are consummated, the Lenders shall indemnify upon demand each Agent-Related Person (to the extent not reimbursed by or on behalf of any Loan Party and without limiting the obligation of any Loan Party to do so), pro rata, and hold harmless each Agent-Related Person from and against any and all Indemnified Liabilities incurred by it; provided, however, that no Lender shall be liable for the payment to any Agent-Related Person of any portion of such Indemnified Liabilities resulting from such Person’s gross negligence or willful misconduct; provided, however, that no action taken in accordance with the directions of the Required Lenders shall be deemed to constitute gross negligence or willful misconduct for purposes of this Section.  Without limitation of the foregoing, each Lender shall reimburse the Administrative

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Agent upon demand for its ratable share of any costs or out-of-pocket expenses (including Attorney Costs) incurred by the Administrative Agent in connection with the preparation, execution, delivery, administration, modification, amendment or enforcement (whether through negotiations, legal proceedings or otherwise) of, or legal advice in respect of rights or responsibilities under, this Agreement, any other Loan Document, or any document contemplated by or referred to herein, to the extent that the Administrative Agent is not reimbursed for such expenses by or on behalf of the Borrower.  The undertaking in this Section shall survive termination of the Commitments, the payment of all Obligations hereunder and the resignation or replacement of the Administrative Agent.

9.09        Administrative Agent in its Individual Capacity.  Royal Bank of Canada and its Affiliates may make loans to, accept deposits from, acquire equity interests in and generally engage in any kind of banking, trust, financial advisory, underwriting or other business with each of the Loan Parties and their respective Affiliates as though Royal Bank of Canada were not the Administrative Agent or the L/C Issuer hereunder and without notice to or consent of the Lenders.  The Lenders acknowledge that, pursuant to such activities, Royal Bank of Canada or its Affiliates may receive information regarding any Loan Party or its Affiliates (including information that may be subject to confidentiality obligations in favor of such Loan Party or such Affiliate) and acknowledge that the Administrative Agent shall be under no obligation to provide such information to them.  With respect to its Loans, Royal Bank of Canada shall have the same rights and powers under this Agreement as any other Lender and may exercise such rights and powers as though it were not the Administrative Agent or the L/C Issuer, and the terms “Lender” and “Lenders” include Royal Bank of Canada in its individual capacity.

9.10        Successor Administrative Agent.  The Administrative Agent may resign as Administrative Agent upon 30 days’ notice to the Lenders with a copy of such notice to the Borrower.  If the Administrative Agent resigns under this Agreement, the Required Lenders shall appoint from among the Lenders a successor administrative agent for the Lenders which successor administrative agent shall be consented to by the Borrower at all times other than during the existence of an Event of Default (which consent of the Borrower shall not be unreasonably withheld or delayed).  If no successor administrative agent is appointed prior to the effective date of the resignation of the Administrative Agent, the Administrative Agent may appoint, after consulting with the Lenders and the Borrower, a successor administrative agent from among the Lenders.  Upon the acceptance of its appointment as successor administrative agent hereunder, such successor administrative agent shall succeed to all the rights, powers and duties of the retiring Administrative Agent and the term “Administrative Agent” shall mean such successor administrative agent and the retiring Administrative Agent’s appointment, powers and duties as Administrative Agent shall be terminated.  After any retiring Administrative Agent’s resignation hereunder as Administrative Agent, the provisions of this Article IX and Sections 10.03 and 10.13 shall inure to its benefit as to any actions taken or omitted to be taken by it while it was Administrative Agent under this Agreement.  If no successor administrative agent has accepted appointment as Administrative Agent by the date which is 30 days following a retiring Administrative Agent’s notice of resignation, the retiring Administrative Agent’s resignation shall nevertheless thereupon become effective and the Lenders shall perform all of the duties of the

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Administrative Agent hereunder until such time, if any, as the Required Lenders appoint a successor agent as provided for above.

9.11        Syndication Agent; Other Agents; Arranger.  None of the Lenders or other Persons identified on the facing page or signature pages of this Agreement as a “syndication agent,” as a “co-documentation agent,” any other type of agent (other than the Administrative Agent and the Syndication Agent), “arranger,” or “bookrunner” shall have any right, power, obligation, liability, responsibility or duty under this Agreement other than those applicable to all Lenders as such.  Without limiting the foregoing, none of the Lenders so identified shall have or be deemed to have any fiduciary relationship with any Lender.  Each Lender acknowledges that it has not relied, and will not rely, on any of the Lenders so identified in deciding to enter into this Agreement or in taking or not taking action hereunder.

ARTICLE X.

MISCELLANEOUS

10.01      Amendments, Release of Collateral, Etc.  (a) No amendment or waiver of any provision of this Agreement or any other Loan Document, and no consent to any departure by the Borrower or any other Loan Party therefrom, shall be effective unless in writing signed by the Required Lenders and the Borrower or the applicable Loan Party, as the case may be, and acknowledged by the Administrative Agent, and each such waiver or consent shall be effective only in the specific instance and for the specific purpose for which given; provided, however, that no such amendment, waiver or consent shall, unless in writing and signed by each of the Lenders directly affected thereby and by the Borrower, and acknowledged by the Administrative Agent, do any of the following:

(i)            extend or increase the Commitment of any Lender (or reinstate any Commitment terminated pursuant to Section 8.02);

(ii)           postpone or delay any date fixed by this Agreement or any other Loan Document for any payment or mandatory prepayment of principal, interest, fees or other amounts due to the Lenders (or any of them) hereunder or under any other Loan Document;

(iii)          reduce the principal of, or the rate of interest specified herein on, any Loan or L/C Borrowing or (subject to clause (ii) of the proviso below) any fees or other amounts payable hereunder or under any other Loan Document; provided, however, that only the consent of the Required Lenders shall be necessary to amend the definition of “Default Rate” or to waive any obligation of the Borrower to pay interest at the Default Rate;

(iv)          change the percentage of the Aggregate Commitments or of the aggregate unpaid principal amount of the Loans and L/C Obligations which is required for the Lenders or any of them to take any action hereunder;

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(v)           change the Pro Rata Share of any Lender;

(vi)          release a material amount of Collateral or release any Guarantor from a Guaranty (except in connection with a Disposition permitted under Section 7.07 or as otherwise permitted under this Section 10.01); or

(vii)         amend this Section, or Section 2.12, or any provision herein providing for unanimous consent or other action by all the Lenders;

and, provided further: (i) no amendment, waiver or consent shall, unless in writing and signed by the L/C Issuer in addition to the Required Lenders or all the Lenders, as the case may be, affect the rights or duties of the L/C Issuer under this Agreement or any Letter of Credit Application relating to any Letter of Credit issued or to be issued by it; (ii) no amendment, waiver or consent shall, unless in writing and signed by the Administrative Agent in addition to the Required Lenders or all the Lenders, as the case may be, affect the rights or duties of the Administrative Agent under this Agreement or any other Loan Document; and (iii) the Agent/Arranger Fee Letter may be amended, or rights or privileges thereunder waived, in a writing executed only by the parties thereto.  Notwithstanding anything to the contrary herein, any Lender that has failed to fund any portion of the Loans or participation in L/C Obligations required to be funded by it hereunder shall not have any right to approve or disapprove any amendment, waiver or consent hereunder, except that the Pro Rata Share of such Lender may not be increased without the consent of such Lender.

(b)           Any amendment to any Loan Document which purports to (i) decrease the amount of any mandatory prepayment or commitment reduction required by Section 2.04 or (ii) change this Section 10.01(b), must be by an instrument in writing executed by Borrower, the Administrative Agent, and the Required Lenders.

(c)           Upon any sale, transfer, or disposition of Collateral which is permitted pursuant to the Loan Documents, and upon ten (10) Business Days’ prior written request by the Borrower (which request must be accompanied by (i) true and correct copies of all material documents of transfer or disposition, including any contract of sale, (ii) a preliminary closing statement and instructions to the title company, if any, (iii) all requested release instruments in form and substance satisfactory to the Administrative Agent and (iv) if required, written consent of the requisite Lenders), the Administrative Agent shall (and is hereby irrevocably authorized by the Lenders to) execute such documents as may be necessary to evidence the release of Liens granted to the Administrative Agent for the benefit of the Lenders pursuant hereto in such Collateral.  The Administrative Agent shall not be required to execute any release instruments on terms which, in the Administrative Agent’s opinion, would expose the Administrative Agent to liability or create any obligation or entail any consequence other than the release of Liens without recourse or warranty.  No such release shall impair the Administrative Agent’s Lien on the proceeds of sale of such Collateral.

(d)           If all outstanding Loans and other Obligations have been indefeasibly paid in full and the Commitments have terminated or have been reduced to zero, and, subject to Section 10.01(e)

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all Lender Hedging Agreement have terminated, the Administrative Agent agrees to, and the Lenders hereby instruct the Administrative Agent to, at the Borrower’s expense, execute and authorize such releases of the Collateral Documents as the Borrower shall reasonably request and this Agreement shall be deemed terminated except that such termination shall not relieve the Borrower of any obligation to make any payments to the Administrative Agent or any Lender required by any Loan Document to the extent accruing, or relating to an event occurring, prior to such termination.

(e)           Notwithstanding any provision herein to the contrary, if the Commitments have been terminated, and the only outstanding Obligations are amounts owed pursuant to one or more Lender Hedging Agreements, the Administrative Agent will, and is hereby authorized to, (A) release the Liens created under the Loan Documents and (B) release all Guaranties of the Borrower; provided, that contemporaneously with such release, (i) the Borrower (and, if applicable, the Subsidiary that is a party to such Lender Hedging Agreements) (A) executes a margin agreement in form and substance acceptable to such Lender(s) (or its Affiliates) that are parties to such Lender Hedging Agreements (the “Lender Counterparties”) and (B), if required, provides collateral in the form of cash or a letter of credit having an aggregate value acceptable to such Lender Counterparties, and (ii) if such Lender Hedging Agreement is executed by a Subsidiary of the Borrower and the Borrower and the MLP are not parties thereto, the Borrower and the MLP execute a guaranty covering such Subsidiary’s obligations thereunder, such guaranty to be in form and substance satisfactory to the Lender Counterparties.  Any release under this Section 10.01(e) must be in writing and signed by the Administrative Agent.

10.02      Notices and Other Communications; Facsimile Copies.

(a)           General.  Unless otherwise expressly provided herein, all notices and other communications provided for hereunder and under the other Loan Documents shall be in writing (including by facsimile transmission) and mailed, faxed or delivered, to the address, facsimile number or (subject to subsection (c) below) electronic mail address specified for notices on Schedule 10.02 (for the Borrower, any Guarantor and the Administrative Agent) or on the Administrative Details Form (for the other Lenders); or, in the case of the Borrower, the Guarantors, the Administrative Agent, or the L/C Issuer, to such other address as shall be designated by such party in a notice to the other parties, and in the case of any other party, to such other address as shall be designated by such party in a notice to the Borrower, the Administrative Agent and the L/C Issuer.  All such notices and other communications shall be deemed to be given or made upon the earlier to occur of (i) actual receipt by the intended recipient and (ii) (A) if delivered by hand or by courier, when signed for by the intended recipient; (B) if delivered by mail, four Business Days after deposit in the mails, postage prepaid; (C) if delivered by facsimile, when sent and receipt has been confirmed by telephone; and (D) if delivered by electronic mail (which form of delivery is subject to the provisions of subsection (c) below), when delivered; provided, however, that notices and other communications to the Administrative Agent or the L/C Issuer pursuant to Article II shall not be effective until actually received by such Person.  Any notice or other communication permitted to be given, made or confirmed by telephone hereunder shall be given, made or confirmed by means of a telephone call to the intended recipient at the number specified in accordance with this Section, it being

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understood and agreed that a voicemail message shall in no event be effective as a notice, communication or confirmation hereunder.

(b)           Effectiveness of Facsimile Documents and Signatures.  Loan Documents may be transmitted and/or signed by facsimile.  The effectiveness of any such documents and signatures shall, subject to applicable Law, have the same force and effect as manually-signed originals and shall be binding on all Loan Parties, the Administrative Agent and the Lenders.  The Administrative Agent may also require that any such documents and signatures be confirmed by a manually-signed original thereof; provided, however, that the failure to request or deliver the same shall not limit the effectiveness of any facsimile document or signature.

(c)           Limited Use of Electronic Mail.  Electronic mail and internet and intranet websites may be used only to distribute routine communications, such as financial statements and other information, and to distribute Loan Documents for execution by the parties thereto, and shall not be recognized hereunder for any other purpose.

(d)           Reliance by Administrative Agent and Lenders.  The Administrative Agent and the Lenders shall be entitled to rely and act upon any notices (including telephonic Borrowing Notices) purportedly given by or on behalf of the Borrower even if (i) such notices were not made in a manner specified herein, were incomplete or were not preceded or followed by any other form of notice specified herein, or (ii) the terms thereof, as understood by the recipient, varied from any confirmation thereof.  The Borrower shall indemnify each Agent-Related Person and each Lender from all losses, costs, expenses and liabilities resulting from the reliance by such Person on each notice purportedly given by or on behalf of the Borrower.  All telephonic notices to and other communications with the Administrative Agent may be recorded by the Administrative Agent, and each of the parties hereto hereby consents to such recording.

10.03      No Waiver; Cumulative Remedies.  No failure by any Lender or the Administrative Agent to exercise, and no delay by any such Person in exercising, any right, remedy, power or privilege hereunder shall operate as a waiver thereof; nor shall any single or partial exercise of any right, remedy, power or privilege hereunder preclude any other or further exercise thereof or the exercise of any other right, remedy, power or privilege.  The rights, remedies, powers and privileges herein or therein provided are cumulative and not exclusive of any rights, remedies, powers and privileges provided by law.

10.04      Attorney Costs; Expenses and Taxes.  The Borrower agrees (a) to pay or reimburse the Administrative Agent for all reasonable costs and expenses incurred in connection with the development, preparation, negotiation, syndication, administration and execution of this Agreement and the other Loan Documents, including the filing, recording, refiling or rerecording of any Mortgage, any pledge agreement and any Security Agreement and/or any Uniform Commercial Code financing statements relating thereto and all amendments, supplements and modifications to any thereof and any and all other documents or instruments of further assurance required to be filed or recorded or refiled or rerecorded by the terms hereof or of any mortgage, any pledge agreement or any security agreement, and any amendment, waiver, consent or other modification of the provisions hereof and thereof (whether or not the transactions contemplated

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hereby or thereby are consummated), and the consummation and administration of the transactions contemplated hereby and thereby, including all Attorney Costs, and (b) to pay or reimburse the Administrative Agent and each Lender for all costs and expenses incurred in connection with the enforcement, attempted enforcement, or preservation of any rights or remedies under this Agreement or the other Loan Documents (including all such costs and expenses incurred during any workout or restructuring in respect of the Obligations and during any legal proceeding, including any proceeding under any Debtor Relief Law), including all Attorney Costs.  The foregoing costs and expenses shall include all search, filing, recording, title insurance and appraisal charges and fees and taxes related thereto, and other out-of-pocket expenses incurred by the Administrative Agent and the cost of independent public accountants and other outside experts retained by the Administrative Agent or any Lender.  The agreements in this Section shall survive the termination of the Commitments and repayment of all the other Obligations.

10.05      Indemnification.  Whether or not the transactions contemplated hereby are consummated, each of the Borrower, the MLP and each other Guarantor (by execution of a Guaranty), jointly and severally, agrees to indemnify, save and hold harmless each Agent-Related Person, the Administrative Agent, the Syndication Agent, the Arranger, each Lender, the L/C Issuer and their respective Affiliates, directors, officers, employees, counsel, agents and attorneys-in-fact (collectively the “Indemnitees”) from and against: (a) any and all claims, demands, actions or causes of action that are asserted against any Indemnitee by any Person (other than the Administrative Agent or any Lender) relating directly or indirectly to a claim, demand, action or cause of action that such Person asserts or may assert against any Loan Party, any Affiliate of any Loan Party or any of their respective officers or directors, arising out of or relating to, the Loan Documents, the Commitments, the use or contemplated use of the proceeds of any Loans, or the relationship of any Loan Party, the Administrative Agent, the Syndication Agent, the Lenders and the L/C Issuer under this Agreement or any other Loan Document; (b) any and all claims, demands, actions or causes of action that may at any time (including at any time following repayment of the Obligations and the resignation of the Administrative Agent or the replacement of any Lender) be asserted or imposed against any Indemnitee, arising out of or relating to, the Loan Documents, the Commitments, the use or contemplated use of the proceeds of any Loans, or the relationship of any Loan Party, the Administrative Agent, the Syndication Agent, the Lenders and the L/C Issuer under this Agreement or any other Loan Document; (c) without limiting the foregoing, any and all claims, demands, actions or causes of action, judgments and orders, penalties and fines that are asserted or imposed against any Indemnitee, (i) under the application of any Environmental Law applicable to the Borrower or any of its Subsidiaries or any of their properties or assets, including the treatment or disposal of Hazardous Substances on any of their properties or assets, (ii) as a result of the breach or non-compliance by the Borrower or any Subsidiary with any Environmental Law applicable to the Borrower or any Subsidiary, (iii) due to past ownership by the Borrower or any Subsidiary of any of their properties or assets or past activity on any of their properties or assets which, though lawful and fully permissible at the time, could result in present liability, (iv) due to the presence, use, storage, treatment or disposal of Hazardous Substances on or under, or the escape, seepage, leakage, spillage, discharge, emission or Release from, any of

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the properties owned or operated by the Borrower or any Subsidiary (including any liability asserted or arising under any Environmental Law), regardless of whether caused by, or within the control of, the Borrower or such Subsidiary, or (v) due to any other environmental, health or safety condition in connection with the Loan Documents; (d) any administrative or investigative proceeding by any Governmental Authority arising out of or related to a claim, demand, action or cause of action described in subsection (a), (b) or (c) above; and (e) any and all liabilities (including liabilities under indemnities), losses, costs, damages or expenses (including Attorney Costs and settlement costs) that any Indemnitee suffers or incurs as a result of the assertion of any foregoing claim, demand, action, cause of action or proceeding, or as a result of the preparation of any defense in connection with any foregoing claim, demand, action, cause of action or proceeding, in all cases, WHETHER OR NOT ARISING OUT OF THE STRICT LIABILITY OR NEGLIGENCE OF AN INDEMNITEE, and whether or not an Indemnitee is a party to such claim, demand, action, cause of action or proceeding (all the foregoing, collectively, the “Indemnified Liabilities”); provided that no Indemnitee shall be entitled to indemnification for any claim to the extent caused by its own gross negligence or willful misconduct.  The agreements in this Section shall survive and continue for the benefit of the Indemnitees at all times after the Borrower’s acceptance of the Lenders’ Commitments under this Agreement, whether or not the Restatement Conditions Effective Date shall occur and shall survive the termination of the Commitments and repayment of all the other Obligations.

10.06      Payments Set Aside.  To the extent that the Borrower makes a payment to the Administrative Agent or any Lender, or the Administrative Agent or any Lender exercises its right of setoff, and such payment or the proceeds of such set-off or any part thereof is subsequently invalidated, declared to be fraudulent or preferential, set aside or required (including pursuant to any settlement entered into by the Administrative Agent or such Lender in its discretion) to be repaid to a trustee, receiver or any other party, in connection with any proceeding under any Debtor Relief Law or otherwise, then (a) to the extent of such recovery, the obligation or part thereof originally intended to be satisfied shall be revived and continued in full force and effect as if such payment had not been made or such setoff had not occurred, and (b) each Lender severally agrees to pay to the Administrative Agent upon demand its applicable share of any amount so recovered from or repaid by the Administrative Agent, plus interest thereon from the date of such demand to the date such payment is made at a rate per annum equal to the Federal Funds Rate from time to time in effect.

10.07      Successors and Assigns.

(a)           The provisions of this Agreement shall be binding upon and inure to the benefit of the parties hereto and their respective successors and assigns permitted hereby, except that neither the Borrower nor the MLP may assign or otherwise transfer any of its rights or obligations hereunder without the prior written consent of each Lender and no Lender may assign or otherwise transfer any of its rights or obligations hereunder except (i) to an Eligible Assignee in accordance with the provisions of paragraph (b) of this Section, (ii) by way of participation in accordance with the provisions of paragraph (d) of this Section or (iii) by way of pledge or assignment of a security interest subject to the restrictions of paragraph (f) of this Section (and any other attempted assignment or transfer by any party hereto shall be null and

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void).  Nothing in this Agreement, expressed or implied, shall be construed to confer upon any Person (other than the parties hereto, their respective successors and assigns permitted hereby, Participants to the extent provided in paragraph (d) of this Section and, to the extent expressly contemplated hereby, the Related Parties of each of the Administrative Agent and the Lenders) any legal or equitable right, remedy or claim under or by reason of this Agreement.

(b)           Any Lender may at any time assign to one or more Eligible Assignees all or a portion of its rights and obligations under this Agreement (including all or a portion of its Commitment and the Loans (including for purposes of this subsection (b), participations in L/C Obligations) at the time owing to it); provided that: (i) except in the case of an assignment of the entire remaining amount of the assigning Lender’s Commitment and the Loans at the time owing to it or in the case of an assignment to a Lender or an Affiliate of a Lender or an Approved Fund with respect to a Lender, the aggregate amount of the Commitment (which for this purpose includes Loans outstanding thereunder) or, if the applicable Commitment is not then in effect, the outstanding principal balance of the Loan of the assigning Lender subject to each such assignment (determined as of the date the Assignment and Assumption with respect to such assignment is delivered to the Administrative Agent or, if “Trade Date” is specified in the Assignment and Assumption, as of the Trade Date) shall not be less than $1,000,000, unless each of the Administrative Agent and, so long as no Default has occurred and is continuing, the Borrower otherwise consent (each such consent not to be unreasonably withheld, conditioned or delayed); (ii) each partial assignment shall be made as an assignment of a proportionate part of all the assigning Lender’s rights and obligations under this Agreement with respect to the Loan or the Commitment assigned; (iii) the parties to each assignment shall execute and deliver to the Administrative Agent an Assignment and Assumption, together with a processing and recordation fee of $3,500, and the Eligible Assignee, if it shall not be a Lender, shall deliver to the Administrative Agent an Administrative Details Form; and (iv) any such assignment may be, but is not required to be, of an equal percentage of such Lender’s Revolving Commitment (and Revolving Loans) and Term Loan Commitment (and Term Loans).  Subject to acceptance and recording thereof by the Administrative Agent pursuant to paragraph (c) of this Section, from and after the effective date specified in each Assignment and Assumption, the Eligible Assignee thereunder shall be a party to this Agreement and, to the extent of the interest assigned by such Assignment and Assumption, have the rights and obligations of a Lender under this Agreement, and the assigning Lender thereunder shall, to the extent of the interest assigned by such Assignment and Assumption, be released from its obligations under this Agreement (and, in the case of an Assignment and Assumption covering all of the assigning Lender’s rights and obligations under this Agreement, such Lender shall cease to be a party hereto) but shall continue to be entitled to the benefits of Sections 3.07, 10.04 and 10.05 with respect to facts and circumstances occurring prior to the effective date of such assignment.  Any assignment or transfer by a Lender of rights or obligations under this Agreement that does not comply with this paragraph shall be treated for purposes of this Agreement as a sale by such Lender of a participation in such rights and obligations in accordance with paragraph (d) of this Section.  Upon the occurrence and during the continuance of an Event of Default all restrictions on assignment by any Lender shall cease, including all restrictive clauses driven by withholding tax considerations.

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(c)           The Administrative Agent, acting solely for this purpose as an agent of the Borrower, shall maintain at one of its offices a copy of each Assignment and Assumption delivered to it and a register for the recordation of the names and addresses of the Lenders, and the Commitments of, and principal amounts of the Loans and L/C Obligations owing to, each Lender pursuant to the terms hereof from time to time (the “Register”).  The entries in the Register shall be conclusive absent manifest error, and the Borrower, the Administrative Agent and the Lenders may treat each Person whose name is recorded in the Register pursuant to the terms hereof as a Lender hereunder for all purposes of this Agreement, notwithstanding notice to the contrary.  The Register shall be available for inspection by the Borrower and any Lender, at any reasonable time and from time to time upon reasonable prior notice.

(d)           Any Lender may at any time, without the consent of, or notice to, the Borrower or the Administrative Agent, sell participations to any Person (other than a natural person or the Borrower or any of the Borrower’s Affiliates or Subsidiaries) (each, a “Participant”) in all or a portion of such Lender’s rights and/or obligations under this Agreement (including all or a portion of its Commitment and/or the Loans (including such Lender’s participation in L/C Obligations) owing to it); provided that (i) such Lender’s obligations under this Agreement shall remain unchanged, (ii) such Lender shall remain solely responsible to the other parties hereto for the performance of such obligations and (iii) the Borrower, the Administrative Agent and the other Lenders shall continue to deal solely and directly with such Lender in connection with such Lender’s rights and obligations under this Agreement.  Any agreement or instrument pursuant to which a Lender sells such a participation shall provide that such Lender shall retain the sole right to enforce this Agreement and to approve any amendment, modification or waiver of any provision of this Agreement; provided that such agreement or instrument may provide that such Lender will not, without the consent of the Participant, agree to any amendment, modification or waiver that would (i) postpone any date upon which any payment of money is scheduled to be paid to such Participant, (ii) reduce the principal, interest, fees or other amounts payable to such Participant, or (iii) release the MLP from its Guaranty.  Subject to subsection (e) of this Section, the Borrower agrees that each Participant shall be entitled to the benefits of Sections 3.01, 3.04 and 3.05 to the same extent as if it were a Lender and had acquired its interest by assignment pursuant to subsection (b) of this Section.  To the extent permitted by law, each Participant also shall be entitled to the benefits of Section 10.09 as though it were a Lender, provided such Participant agrees to be subject to Section 2.12 as though it were a Lender.

(e)           A Participant shall not be entitled to receive any greater payment under Section 3.01 or 3.04 than the applicable Lender would have been entitled to receive with respect to the participation sold to such Participant, unless the sale of the participation to such Participant is made with the Borrower’s prior written consent.  A Participant that would be a Foreign Lender if it were a Lender shall not be entitled to the benefits of Section 3.01 unless the Borrower is notified of the participation sold to such Participant and such Participant agrees, for the benefit of the Borrower, to comply with Section 10.15 as though it were a Lender.

(f)            Any Lender may at any time pledge or assign a security interest in all or any portion of its rights under this Agreement (including under its Notes, if any) to secure obligations of such Lender, including any pledge or assignment to secure obligations to a Federal Reserve

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Bank; provided that no such pledge or assignment shall release a Lender from any of its obligations hereunder or substitute any such pledgee or assignee for such Lender as a party hereto.

(g)           If the consent of the Borrower to an assignment or to an Eligible Assignee is required hereunder (including a consent to an assignment which does not meet the minimum assignment threshold specified in clause (i) of the proviso to the first sentence of Section 10.07(b)), the Borrower shall be deemed to have given its consent five Business Days after the date notice thereof has been delivered by the assigning Lender (through the Administrative Agent) unless such consent is expressly refused by the Borrower prior to such fifth Business Day.

(h)           Notwithstanding anything to the contrary contained herein, if at any time Royal Bank of Canada assigns all of its Commitment and Loans pursuant to subsection (b) above, Royal Bank of Canada may, (i) upon 30 days’ notice to the Borrower and the Lenders, resign as L/C Issuer.  In the event of any such resignation as L/C Issuer, the Borrower shall be entitled to appoint from among the Lenders a successor L/C Issuer hereunder; provided, however, that no failure by the Borrower to appoint any such successor shall affect the resignation of Royal Bank of Canada as L/C Issuer.  Royal Bank of Canada shall retain all the rights and obligations of the L/C Issuer hereunder with respect to all Letters of Credit outstanding as of the effective date of its resignation as L/C Issuer and all L/C Obligations with respect thereto (including the right to require the Lenders to make Base Rate Loans or fund participations in Unreimbursed Amounts pursuant to Section 2.14(c)).

10.08      Confidentiality.  Each Lender agrees that it will not disclose without the prior consent of the Borrower (other than to directors, officers, employees, auditors, accountants, counsel or other professional advisors of the Administrative Agent or any Lender) any information with respect to the Borrower or its Subsidiaries, which is furnished pursuant to this Agreement and which (i) the Borrower in good faith considers to be confidential and (ii) is either clearly marked confidential or is designated by the Borrower to the Administrative Agent or the Lenders in writing as confidential; provided that any Lender may disclose any such information (a) as has become generally available to the public, (b) as may be required or appropriate in any report, statement or testimony submitted to or required by any municipal, state or federal regulatory body having or claiming to have jurisdiction over such Lender or submitted to or required by the Board or the Federal Deposit Insurance Corporation or similar organizations (whether in the United States of America or elsewhere) or their successors, (c) as may be required or appropriate in response to any summons or subpoena in connection with any litigation, (d) in order to comply with any law, order, regulation or ruling applicable to such Lender, (e) to any Eligible Assignee of or Participant in, or any prospective Eligible Assignee of or Participant in, any of its rights or obligations under this Agreement; provided that such Eligible Assignee or Participant or prospective Eligible Assignee or Participant executes an agreement containing provisions substantially similar to those contained in this Section 10.08, (f) in connection with the exercise of any remedy by such Lender following an Event of Default pertaining to the Loan Documents, (g) in connection with any litigation involving such Lender pertaining to the Loan Documents, (h) to any Lender or the Administrative Agent, or (i) to any

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Affiliate of any Lender (it being understood that the Persons to whom such disclosure is made will be informed of the confidential nature of such information and obligated to keep such information confidential); provided further, that notwithstanding anything in this Agreement to the contrary, the Borrower, the Administrative Agent, the Syndication Agent, the L/C Bank, each Lender and each Related Party may disclose to any and all Persons, without limitation of any kind, the tax treatment and tax structure of the transactions contemplated hereby and all materials of any kind (including opinions or other tax analysis) that are provided to it relating to such tax treatment and tax structure; and nothing in the foregoing authorization shall apply to any disclosure that would constitute a violation of applicable federal or state securities laws.

10.09      Set-off.  In addition to any rights and remedies of the Lenders provided by law, upon the occurrence and during the continuance of any Event of Default, each Lender is authorized at any time and from time to time, without prior notice to the MLP, the Borrower or any other Loan Party, any such notice being waived by the MLP, the Borrower (on its own behalf and on behalf of each Loan Party) to the fullest extent permitted by law, to set off and apply any and all deposits (general or special, time or demand, provisional or final) at any time held by, and other indebtedness at any time owing by, such Lender to or for the credit or the account of the respective Loan Parties against any and all Obligations owing to the Administrative Agent and the Lenders, now or hereafter existing, irrespective of whether or not the Administrative Agent or such Lender shall have made demand under this Agreement or any other Loan Document and although such Obligations may be contingent or unmatured.  Included within the scope of the foregoing is the right of set-off granted by the MLP and Borrower to that certain $2,500,000 pledged cash deposit made by the MLP in favor of Borrower and held by the Administrative Agent to secure certain obligations owing by the MLP to the Borrower under one or more Master Agreements; provided however no such set-off by the Administrative Agent may be made unless (i) the MLP is in default of its payment obligation to the Borrower under the relevant Master Agreement(s) (as determined by the Administrative Agent in its reasonable judgment) and (ii) an Event of Default exists hereunder.  Each Lender agrees promptly to notify the Borrower and the Administrative Agent after any such set-off and application made by such Lender; provided, however, that the failure to give such notice shall not affect the validity of such set-off and application.

10.10      Interest Rate Limitation.  Regardless of any provision contained in any Loan Document, neither the Administrative Agent nor any Lender shall ever be entitled to contract for, charge, take, reserve, receive, or apply, as interest on all or any part of the Obligations, any amount in excess of the Maximum Rate, and, if any Lender ever does so, then such excess shall be deemed a partial prepayment of principal and treated hereunder as such and any remaining excess shall be refunded to the Borrower.  In determining if the interest paid or payable exceeds the Maximum Rate, the Borrower and the Lenders shall, to the maximum extent permitted under applicable Law, (a) treat all Borrowings as but a single extension of credit (and the Lenders and the Borrower agree that such is the case and that provision herein for multiple Borrowings is for convenience only), (b) characterize any nonprincipal payment as an expense, fee, or premium rather than as interest, (c) exclude voluntary prepayments and the effects thereof, and (d) amortize, prorate, allocate, and spread the total amount of interest throughout the entire

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contemplated term of the Obligations.  However, if the Obligations are paid and performed in full prior to the end of the full contemplated term thereof, and if the interest received for the actual period of existence thereof exceeds the Maximum Amount, the Lenders shall refund such excess, and, in such event, the Lenders shall not, to the extent permitted by Law, be subject to any penalties provided by any Laws for contracting for, charging, taking, reserving or receiving interest in excess of the Maximum Amount.  To the extent the Laws of the State of Texas are applicable for purposes of determining the “Maximum Rate” or the “Maximum Amount,” then those terms mean the “weekly ceiling” from time to time in effect under Texas Finance Code § 303.001, as limited by Texas Finance Code § 303.009.  The Borrower agrees that Chapter 346 of the Texas Finance Code, as amended (which regulates certain revolving credit loan accounts and revolving tri-party accounts), does not apply to the Obligations.

10.11      Counterparts.  This Agreement may be executed in one or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument.

10.12      Integration.  This Agreement, together with the other Loan Documents, comprises the complete and integrated agreement of the parties on the subject matter hereof and thereof and supersedes all prior agreements, written or oral, on such subject matter.  In the event of any conflict between the provisions of this Agreement and those of any other Loan Document, the provisions of this Agreement shall control; provided that the inclusion of supplemental rights or remedies in favor of the Administrative Agent or the Lenders in any other Loan Document shall not be deemed a conflict with this Agreement.  Each Loan Document was drafted with the joint participation of the respective parties thereto and shall be construed neither against nor in favor of any party, but rather in accordance with the fair meaning thereof.

10.13      Survival of Representations and Warranties.  All representations and warranties made hereunder and in any other Loan Document or other document delivered pursuant hereto or thereto or in connection herewith or therewith shall survive the execution and delivery hereof and thereof.  Such representations and warranties have been or will be relied upon by the Administrative Agent and each Lender, regardless of any investigation made by the Administrative Agent or any Lender or on their behalf and notwithstanding that the Administrative Agent or any Lender may have had notice or knowledge of any Default or Event of Default at the time of any Borrowing, and shall continue in full force and effect as long as any Loan or any other Obligation shall remain unpaid or unsatisfied.

10.14      Severability.  Any provision of this Agreement and the other Loan Documents to which the Borrower is a party that is prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions thereof, and any such prohibition or unenforceability in any jurisdiction shall not invalidate or render unenforceable such provision in any other jurisdiction.

10.15      Foreign Lenders.  Each Lender that is a “foreign corporation, partnership or trust” within the meaning of the Code (a “Foreign Lender”) shall deliver to the Administrative

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Agent, prior to receipt of any payment subject to withholding under the Code (or after accepting an assignment of an interest herein), two duly signed completed copies of either IRS Form W-8BEN or any successor thereto (relating to such Person and entitling it to an exemption from, or reduction of, withholding tax on all payments to be made to such Person by the Borrower pursuant to this Agreement) or IRS Form W-8ECI or any successor thereto (relating to all payments to be made to such Person by the Borrower pursuant to this Agreement) or such other evidence satisfactory to the Borrower and the Administrative Agent that such Person is entitled to an exemption from, or reduction of, U.S. withholding tax.  Thereafter and from time to time, each such Person shall (a) promptly submit to the Administrative Agent such additional duly completed and signed copies of one of such forms (or such successor forms as shall be adopted from time to time by the relevant United States taxing authorities) as may then be available under then current United States laws and regulations to avoid, or such evidence as is satisfactory to the Borrower and the Administrative Agent of any available exemption from or reduction of, United States withholding taxes in respect of all payments to be made to such Person by the Borrower pursuant to this Agreement, (b) promptly notify the Administrative Agent of any change in circumstances which would modify or render invalid any claimed exemption or reduction, and (c) take such steps as shall not be materially disadvantageous to it, in the reasonable judgment of such Lender, and as may be reasonably necessary (including the re-designation of its Lending Office) to avoid any requirement of applicable Laws that the Borrower make any deduction or withholding for taxes from amounts payable to such Person.  If such Person fails to deliver the above forms or other documentation, then the Administrative Agent may withhold from any interest payment to such Person an amount equivalent to the applicable withholding tax imposed by Sections 1441 and 1442 of the Code, without reduction.  If any Governmental Authority asserts that the Administrative Agent did not properly withhold any tax or other amount from payments made in respect of such Person, such Person shall indemnify the Administrative Agent therefor, including all penalties and interest, any taxes imposed by any jurisdiction on the amounts payable to the Agent under this Section, and costs and expenses (including Attorney Costs) of the Administrative Agent.  The obligation of the Lenders under this Section shall survive the payment of all Obligations and the resignation or replacement of the Administrative Agent.

10.16      Governing Law.

(a)           THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAW OF THE STATE OF TEXAS APPLICABLE TO AGREEMENTS MADE AND TO BE PERFORMED ENTIRELY WITHIN SUCH STATE; PROVIDED THAT THE ADMINISTRATIVE AGENT AND EACH LENDER SHALL RETAIN ALL RIGHTS ARISING UNDER UNITED STATES FEDERAL LAW.

(b)           EACH COMPANY AND OTHER PARTY HERETO, AND EACH GUARANTOR, BY EXECUTION OF A GUARANTY, AGREES AS TO THIS SECTION 10.16(b). ANY LEGAL ACTION OR PROCEEDING WITH RESPECT TO THIS AGREEMENT OR ANY OTHER LOAN DOCUMENT MAY BE BROUGHT IN THE COURTS OF THE STATE OF TEXAS SITTING IN HARRIS COUNTY OR OF THE UNITED STATES FOR THE SOUTHERN DISTRICT OF SUCH STATE, AND BY

93

EXECUTION AND DELIVERY OF THIS AGREEMENT, THE BORROWER, THE ADMINISTRATIVE AGENT AND EACH LENDER CONSENTS, AND BY EXECUTION OF A GUARANTY, EACH GUARANTOR CONSENTS, FOR ITSELF AND IN RESPECT OF ITS PROPERTY, TO THE NON-EXCLUSIVE JURISDICTION OF THOSE COURTS.  THE BORROWER, EACH GUARANTOR, THE ADMINISTRATIVE AGENT AND EACH LENDER (1) IRREVOCABLY WAIVES ANY OBJECTION, INCLUDING ANY OBJECTION TO THE LAYING OF VENUE OR BASED ON THE GROUNDS OF FORUM NON CONVENIENS, WHICH IT MAY NOW OR HEREAFTER HAVE TO THE BRINGING OF ANY ACTION OR PROCEEDING IN SUCH JURISDICTION IN RESPECT OF ANY LOAN DOCUMENT OR OTHER DOCUMENT RELATED THERETO, AND (2) IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS OUT OF ANY OF THE AFOREMENTIONED COURTS IN ANY SUCH ACTION OR PROCEEDING BY THE MAILING OF COPIES THEREOF BY CERTIFIED MAIL, RETURN RECEIPT REQUESTED, POSTAGE PREPAID, AT ITS ADDRESS FOR NOTICES DESIGNATED HEREIN.  THE BORROWER, EACH GUARANTOR, THE ADMINISTRATIVE AGENT AND EACH LENDER WAIVES PERSONAL SERVICE OF ANY SUMMONS, COMPLAINT OR OTHER PROCESS, WHICH MAY BE MADE BY ANY OTHER MEANS PERMITTED BY THE LAW OF SUCH STATE.  THE BORROWER AND EACH GUARANTOR, BY ITS EXECUTION OF A GUARANTY, HEREBY IRREVOCABLY APPOINTS CT CORPORATION SYSTEM, WITH AN ADDRESS AT 350 N. ST. PAUL STREET, DALLAS, TEXAS 75201 (THE “TEXAS PROCESS AGENT”) AS PROCESS AGENT IN ITS NAME, PLACE AND STEAD TO RECEIVE AND FORWARD SERVICE OF ANY AND ALL WRITS, SUMMONSES AND OTHER LEGAL PROCESS IN ANY SUIT, ACTION OR PROCEEDING BROUGHT IN THE STATE OF TEXAS, AGREES THAT SUCH SERVICE IN ANY SUCH SUIT, ACTION OR PROCEEDING MAY BE MADE UPON THE TEXAS PROCESS AGENT, AND AGREES TO TAKE ALL SUCH ACTION AS MAY BE NECESSARY TO CONTINUE SAID APPOINTMENT IN FULL FORCE AND EFFECT.

10.17      Waiver of Right to Trial by Jury, Etc.  EACH PARTY TO THIS AGREEMENT AND EACH GUARANTOR, BY EXECUTION OF A GUARANTY, HEREBY (a) EXPRESSLY AND IRREVOCABLY WAIVES ANY RIGHT TO TRIAL BY JURY OF ANY CLAIM, DEMAND, ACTION OR CAUSE OF ACTION ARISING UNDER ANY LOAN DOCUMENT OR IN ANY WAY CONNECTED WITH OR RELATED OR INCIDENTAL TO THE DEALINGS OF THE PARTIES TO THE LOAN DOCUMENTS OR ANY OF THEM WITH RESPECT TO ANY LOAN DOCUMENT, OR THE TRANSACTIONS RELATED THERETO, IN EACH CASE WHETHER NOW EXISTING OR HEREAFTER ARISING, AND WHETHER FOUNDED IN CONTRACT OR TORT OR OTHERWISE; AND EACH PARTY HEREBY AGREES AND CONSENTS THAT ANY SUCH CLAIM, DEMAND, ACTION OR CAUSE OF ACTION SHALL BE DECIDED BY COURT TRIAL WITHOUT A JURY, AND THAT ANY PARTY TO THIS AGREEMENT MAY FILE AN ORIGINAL COUNTERPART OR A COPY OF THIS SECTION WITH ANY COURT AS WRITTEN EVIDENCE OF THE CONSENT OF THE COMPANIES TO THE WAIVER OF THEIR RIGHT TO TRIAL BY JURY; AND (b) EXPRESSLY AND IRREVOCABLY WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO

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CLAIM OR RECOVER IN ANY SUCH ACTION ANY SPECIAL, EXEMPLARY, PUNITIVE OR CONSEQUENTIAL DAMAGES, OR DAMAGES OTHER THAN, OR IN ADDITION TO, ACTUAL DAMAGES; PROVIDED THAT THE WAIVER CONTAINED IN THIS SECTION 10.17(b) SHALL NOT APPLY TO THE EXTENT THAT THE PARTY AGAINST WHOM DAMAGES ARE SOUGHT HAS ENGAGED IN GROSS NEGLIGENCE OR WILLFUL MISCONDUCT.

10.18      Security Interest In Amended and Restated MarkWest Parent Deposit Pledge Agreement.  The Borrower hereby grants to the Administrative Agent, for the benefit of the Lenders, a lien on and security interest in and to the Borrower’s rights, titles and interest in and to the Amended and Restated MarkWest Parent Deposit Pledge Agreement and in the Cash (as therein defined), the Demand Account (as therein defined) and the Collateral (as therein defined) as security for the Obligations.  The rights granted by this Section 10.18 shall be in addition to the rights of the Administrative Agent under any statutory banker’s Lien or the common law right of set-off.

10.19      No General Partner’s Liability.  The Administrative Agent and the Lenders agree for themselves and their respective successors and assigns, including any subsequent holder of any Note, that no claim under this Agreement, under the Guaranty executed on behalf of the MLP, or under any other Loan Document shall be made against the General Partner, and that no judgment, order or execution entered in any suit, action or proceeding, whether legal or equitable, hereunder, on such Guaranty, or on any other Loan Document shall be obtained or enforced, against the General Partner or its assets for the purpose of obtaining satisfaction and payment of amounts owed under this Agreement, such Guaranty or any other Loan Document.  Nothing in this Section 10.19, however, shall be construed so as to prevent the Administrative Agent, any Lender or any other holder of any Note from commencing any action, suit or proceeding with respect to or causing legal papers to be served upon the General Partner for the sole purpose of obtaining jurisdiction over the MLP.

10.20      Termination of Commitments Under First Amended and Restated Credit Agreement.  As of the Restatement Date, the Commitments under the First Amended and Restated Credit Agreement are terminated and the Administrative Agent and the Lenders hereby waive any right to receive prior notice of such termination.  Each Lender agrees upon the Restatement Date to return to Borrower with reasonable promptness all “Notes” as defined under the First Amended and Restated Credit Agreement which were delivered by the Borrower in exchange for new Notes to be issued pursuant to this Agreement.

10.21      No Novations, Etc.  To the extent of the aggregate commitments outstanding under the First Amended and Restated Credit Agreement ($140,000,000), nothing contained herein shall be deemed a novation of or a repayment or new advance of any obligation of the Borrower hereunder.  Only to the extent of an increase in the Aggregate Commitments over that amount shall there be deemed to be a new advance by the Lenders to the Borrower under this Agreement.  The Indebtedness owing under the First Amended and Restated Credit Agreement is renewed, rearranged, extended and carried forward by this Agreement and all of the liens and security interests securing the “Obligations” as defined in the First Amended and Restated Credit

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Agreement are carried forward and secure, without interruption or loss or priority, the Obligations under this Agreement.  So too, the Indebtedness owing under the Original Credit Agreement was renewed, rearranged, extended and carried forward by the First Amended and Restated Credit Agreement and all of the liens and security interests securing the “Obligations” as defined in the Original Credit Agreement were carried forward and secured, without interruption or loss of priority, the Obligations under the First Amended and Restated Credit Agreement.

10.22      ENTIRE AGREEMENT.  THIS AGREEMENT AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

[REMAINDER OF PAGE INTENTIONALLY BLANK;

SIGNATURES BEGIN ON NEXT PAGE]

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IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed as of the date first above written.

MARKWEST ENERGY OPERATING COMPANY, L.L.C.,
a Delaware limited liability company, as Borrower
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	Its General Partner
	By:	/s/ James G. Ivey
	James G. Ivey
	Senior Vice President
	and Chief Financial Officer
MARKWEST ENERGY PARTNERS, L.P.,
a Delaware limited partnership, as a Guarantor
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:	/s/ James G. Ivey
	James G. Ivey
	Senior Vice President
	and Chief Financial Officer

1

ROYAL BANK OF CANADA,
as Administrative Agent
By:	/s/ Gail Watkin
Gail Watkin
Manager, Agency
ROYAL BANK OF CANADA, as Lender
and L/C Issuer
By:	/s/ Jason York
Jason York
Authorized Signatory

2

FORTIS CAPITAL CORP.,
as Syndication Agent
By:	/s/ Darrell W. Holley
By:	/s/ Casey Lowary
FORTIS CAPITAL CORP.,
as Lender
By:	/s/ Darrell W. Holley
By:	/s/ Casey Lowary

3

U. S. BANK, NATIONAL ASSOCIATION
as Manager and Lender
By:	/s/ Monte E. Deckerd
Monte E. Deckerd
Vice President

4

BANK ONE, N.A.
as Documentation Agent and Lender
By:	/s/ Jane Bek Keil
Jane Bek Keil
Director

5

SOCIETE GENERALE,
as Documentation Agent and Lender
By:	/s/ Francis Sacr

6

SCHEDULE 2.01

COMMITMENTS

Lender	Revolver Commitments		Term Loan Commitments		Aggregate Lender Commitments
Royal Bank of Canada	$	75,714,285.71	$	14,285,714.29	$	90,000,000.00
Fortis	$	58,888,888,89	$	11,111,111,11	$	70,000,000.00
Bank One	$	58,888,888,89	$	11,111,111,11	$	70,000,000.00
Societe Generale	$	42,063,492.06	$	7,936,507.94	$	50,000,000.00
US Bank	$	29,444,444.44	$	5,555,555.56	$	35,000,000.00
Total:	$	265,000,000.00	$	50,000,000	$	315,000,000

SCHEDULE 5.13

SUBSIDIARIES

AND OTHER EQUITY INVESTMENTS

(a)           Subsidiaries as of the Restatement Date:

Name	Jurisdiction of Organization	Ownership
MarkWest Energy Appalachia, L.L.C.	Delaware	100% owned by the Borrower
Basin Pipeline L.L.C.	Michigan	100% owned by the Borrower
West Shore Processing Company, L.L.C.	Michigan	100% owned by the Borrower
MarkWest Texas GP, L.L.C.	Texas	100% owned by the Borrower
MW Texas Limited, L.L.C.	Texas	100% owned by the Borrower
MarkWest Michigan Pipeline Company, L.L.C.	Michigan	100% owned by the Borrower
MarkWest Western Oklahoma Gas Company, L.L.C.	Oklahoma	100% owned by the Borrower
MarkWest Power Tex, L.P.	Texas	100% owned by MW GP and MW Limited
MarkWest Pinnacle, L.P.	Texas	100% owned by MW GP and MW Limited
MarkWest PNG Utility, L.P.	Texas	100% owned by MW GP and MW Limited
MarkWest Texas PNG Utility, L.P.	Texas	100% owned by MW GP and MW Limited
MarkWest Blackhawk, L.P.	Texas	100% owned by MW GP and MW Limited
MarkWest New Mexico, L.P.	Texas	100% owned by MW GP and MW Limited

1

MarkWest Energy East Texas Gas Company, L.P. Delaware 100% owned by MW GP and MW Limited

(b)           Other Equity Investments as of the Restatement Date

None

2

SCHEDULE 7.01

EXISTING LIENS

Debtor	Creditor	Asset Secured	Filing Jurisdiction
MarkWest Energy Appalachia, L.L.C.,	U.S. Bancorp Leasing & Financial	Compressors at Kenova	Colorado SOS
MarkWest Energy Appalachia, L.L.C.	Fleet Capital Corp.	Gas Compressor at Kenova	Colorado SOS, W.Va SOS

LIST LIENS ON ASSETS ACQUIRED IN ACET ACQUISITION

SCHEDULE 7.04

LIST INDEBTEDNESS ASSUMED IN ACET ACQUISITION

1.             Obligations assumed in connection with Assignment and Assumption of Rights under Equipment Lease

2.             Obligations assumed in connection with Assignment and Assumption of Rights under EPC Contract

3.             Obligations assumed in connection with Assignment and Assumption of Rights under Chevron Texaco Contract

4.             Obligations assumed in connection with Assignment and Assumption of Rights under the NGPL Contracts

5.             Obligations assumed in connection with Assignment and Assumption of Rights under Total E&P Contract

6.             Obligations assumed in connection with Guaranty Assumption Agreement

SCHEDULE 7.05

OPERATING LEASES

RELATED TO ACET ACQUISITION

Annual Leases - Paid Annually

1.Amended Surface Site Easement from Bert A. McJimsey, Jr. and Barbara Ellen Paxton to SFI Interim, Inc.  Being 3.503 acres of land situated in the Edwin Smith Survey, Abstract 651, Panola County, Texas, and being a part of that certain called 320 acres of land described in a deed from E. J. Downing et ux to Z. L. Daniels, dated November 7, 1905, and recorded in Volume 15, Page 464 of the Deed Records of Panola County, Texas; and recorded in Volume 951, Page 780, Panola County, Texas.  Surface Site Easement from Bert A. McJimsey, Jr. and Barbara Ellen Paxton to SFI Interim, Inc. Being 0.918 acres of land situated in the Edwin Smith Survey, Abstract 651, Panola County, Texas, and being a part of that certain called 320 acres of land described in a deed from E. J. Downing et ux to Z. L. Daniels, dated November 7, 1905, and recorded in Volume 15, Page 464 of the Deed Records of Panola County, Texas; and recorded in Volume 927, Page 615, Panola County, Texas.  Amendment to Surface Site Easement Agreement to provide for the full annual rental payment to be paid solely to Barbara Ellen Paxton, dated February 17, 2003 and recorded in Volume 1176, Page 811, Panola County, Texas.  (File 750 - Gary Compressor Station)

2.Surface Site Lease Agreement between S. L. Holmes and American Central Gas Companies, Inc. Being a right of way over and across that certain called 63.006 acres of land situated in the Cornelius Crenshaw Survey, Abstract 131, Panola County, Texas, said 63.006 acre tract being described as the fourth tract in a partition deed to S. L. Holmes, and recorded in Volume 972, Page 1, of the Deed Records of Panola County, Texas; and recorded in Volume 1002, Page 586.

Surface Site Easement Agreement between S. L. Holmes and American Central Eastern Texas Gas Company, L.P. Being a 0.342 acre station site as situated in the Cornelius Crenshaw Survey, Abstract 103, Panola County, Texas and being a part of called 63.006 acre tract described in a deed to J.L. Holmes as recorded in Volume 792, Page 1, of the official deed records of Panola County, Texas.  Recorded in Volume 1076, Page 424, Panola County, Texas.  (File 1010 - Exxon Dehy Station)

3.Surface Site Easement Agreement from R. K. Bounds and Juanita Bounds to American Central Gas Companies, Inc.  Being 3.35 acres of land situated in the W. C. Gray Survey, Abstract 245, Panola County, Texas, and being out of that certain called 19.54 acre tract, described as Lot 2 in a deed to R. K. Bounds dated January 11, 1966 and recorded in Volume 494, Page 143 of the Deed Records of Panola County, Texas; and recorded in Volume 1002, Page 592, Panola County, Texas.  (File 1090 and File 2688 - Rich Gas Hub Inlet- Measurement & Separation Facilities)

4.Surface Site Lease Agreement from Dorothy Ann Griffith and Kenneth Griffith to American Central Gas Companies, Inc.  Being 5.00 acres of land situated in the Mary Strickland Survey, Abstract 597, Panola County, Texas, and being out of that certain called 49.551 acre tract, described as Tract No. 8 in a partition deed to Dorothy Ann Griffith,

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dated July 12, 1974 and recorded in Volume 575, Page 607 of the Deed Records of Panola County, Texas; and recorded in Volume 1004, Page 493, Panola County, Texas.  (File 2180 - Lake Murvaul Compressor Station)

5.Surface Site Lease Agreement from Ora Lee Davis to American Central Gas Companies, Inc.  Being a 2.378 acre site located in the John M. Bradley Survey, Abstract 49, of Panola County, Texas; and recorded in Volume 1028, Page 665, Panola County, Texas.  (File 2214 - Pinewood Compressor Station)

6.Surface Site Easement from Brian & Jennifer Monroe to ACGC Gathering Company, L.L.C. Being a proposed 0.336 acre station site over, under and across a called 8.344 acre tract, described as the First Tract in a deed form Harold Monroe, et ux to Brian K. Monroe, et ux as recorded in Volume 962, Page 660, said tract being situated in the Wm. Scantleberry Survey, Abstract 598, Panola County, Texas; and recorded in Volume 1050, Page 822, Panola County, Texas.  (File 2656 - Roberts Dehy Site)

Term Leases - Paid in Advance

7.Surface Site Lease Agreement from Ronnie Griffith and Betty Griffith to American Central Gas Companies, Inc. Being 50’ x 50’ site located in the 176.150 acres in the E. Morris Survey, Abstract 432, described in Volume 596, Page 152 of the Deed Records of Panola County, Texas; and recorded in Volume 1010, Page 115, Panola County, Texas.  (File 2190 - Lake Murvaul Pig Trap -15-year lease)

8.Damage Release by Great Eastern Timber Company, L.L.C. for the construction of the Mill Creek Compressor Station by American Central Eastern Texas Gas Company, L.P. Being a ..405 acre station site, said site being situated in a called 946.383 acre tract as described in a deed from John Hancock Mutual Life Insurance Company to Getco Texas Limited Partnership as recorded in Volume 1084, Page 757 of the official deed records of Panola County, Texas.  Recorded in Volume 1146, Page 666, Panola County, Texas.  (File 3218 - Mill Creek Compressor Station - -10-yr lease)

9.Memorandum of Agreement to provide notice of Surface Site Lease from W.C. & Betty Prior to American Central Eastern Texas Gas Company, L.P.  Being a 0.946 acre surface site as situated in a called 54.46 acre tract, being described as the 2nd tract in a deed from Cicero smith to Wade Prior as recorded in Volume 15, Page 588 and being situated in the Willis Vaughn Survey, Abstract 694, Panola County, Texas; and recorded in Volume 1110, Page 337, Panola County, Texas.  (File 3269 - Prior Compressor Station -10-year lease)

10.Memorandum of Agreement to provide notice of Surface Site Lease from Ruby & Billy Grimes to American Central Eastern Texas Gas Company, L.P.  Being a 72.22 acre tract, described in a deed from Dolores Harris, et vir to Ruby Grimes as recorded in Volume 991, Page 450, said tract being situated in the C. Flanagan Survey, Abstract 215, Panola County, Texas; and recorded in Volume 1110, Page 342, Panola County, Texas.  (File 3280 - Thompson Compressor Station -10-year lease)

11.Memorandum of Agreement to provide notice of Surface Site Lease from Joe G. and Sam L. Allison to American Central Eastern Texas Gas Company, L.P. Being a .129 acre

2

station site being over, under and across a called 189.593 tract as described in a deed from C. E. Moore, Jr., et ux, Ida Rose Moore, To Joe G. Allison and Sam L. Allison as recorded in Volume 621, Page 392, said tract being situated in the James M. Hatcher Survey, Abstract 313, Panola County, Texas; and recorded in Volume 1110, Page 334, Panola County, Texas. (File 3281 - - Thompson Low Pressure Separator Station - 10-year lease)

12.Memorandum of Agreement to provide notice of Surface Site Lease from Ruby & Billy Grimes to American Central Eastern Texas Gas Company, L.P.  Being an additional 0.228 acre site, said site being over, under and across a called 72.22 acre tract, described in a deed from Dolores Harris, et vir to Ruby Grimes as recorded in Volume 991, Page 450, said tract being situated in the C. Flanagan Survey, Abstract 215, Panola County, Texas; and recorded in Volume 1155, Page 548, Panola County, Texas.  (File 3361 - Thompson Compressor Station Expansion - 10-year lease)

13.Memorandum of Agreement to provide notice of Surface Site Lease from Dan E. & Pamela S. Morton to American Central Eastern Texas Gas Company, L.P. Being a 50’ x 50’ site, said site being on a called 104.71 acre tract, described in a deed from C.F. Nance, et ux to Dan E. Morton, et ux as recorded in Volume 1047, Page 464, said tract being situated in the Sarah Harrell Survey, Abstract 280 and the Madison E. Alford Survey, Abstract 25, Panola County, Texas; and recorded in Volume 1172, Page 46, Panola County, Texas. (File 3399 - Deadwood valve site to Lagrone - 10-year lease)

Perpetual Leases - One Time Payment

14.Easement from James L. Wedgeworth and Dorothy Wedgeworth to South Central Intrastate Pipeline Company.  Being an 80’ x 150’ site located in that certain 203.1 acre tract (Third Tract) in the John A. Horton Survey Abstract No. 325, the Adam Johnson Survey, Abstract No. 349, and the John T. Copeland Survey Abstract No. 875 as conveyed from Velda Cassity Clark to James Wedgeworth and Wife Dorothy Wedgeworth by deed dated and recorded in Volume 761, Page 364 of the Deed Records of Panola County, Texas.  Recorded in Volume 855, Page 452, Panola County, Texas.  (SCIPC 8” Carthage Gas System - File 830)

15.Surface Site Agreement from Ann Ramsey Burk, Caroline Burk Casteel and F. R. Casteel to South Central Intrastate Pipeline Company.  Being a 50’ x 55’ site located in that certain 233.20 acre tract in the Harrison Davis Survey, Abstract No. 157 and conveyed from Percy Burk and wife, Mildred R. Burk to Ann Ramsey Burk and Caroline Burk Casteel recorded in Volume 579 Page 43 of the Deed Records of Panola County, Texas.  Recorded in Volume 856, Page 547 and Volume 858, Page 700, Panola County, Texas.  (SCIPC 4” NGPL to TUFCO - Files 970 and 980)

16.Surface Easement and Road Easement from Michael R. Perry to American Central Eastern Texas Gas Company, L.P.  Being 0.365 of an acre site (American Central Eastern Texas Gas Gathering Company, Limited Partnership) situated in the Thomas Kelly Survey, Abstract 372, Panola County, Texas, said 0.365 of an acre site being out of a called 45.232 acre tract (save and except 3.054 Ac.) described in a deed from Michele D. Perry, to Michael R. Perry, dated January 21, 1998, and recorded in Volume 1023, Page 147,

3

of the Deed Records of Panola County, Texas.  Recorded in Volume 1034, Page 332, Panola County, Texas.  (File 2559 - Hancock Compressor Station)

17.Road and Equipment Station Right of Way Easement from Sustainable Forests, L.L.C. to American Central Eastern Texas Gas Company, L.P.  Being 5.739 acre Station Site (American Central Eastern Texas Gas Company, Limited Partnership, Hancock Gathering System Compressor Station) situated in the Jas. F. Johns Survey, Abstract 364, Panola County, Texas, said 5.739 acre site being out of a called 640 acre tract of land, and being described in a deed to I.P. Timberlands Operating Company, Ltd., dated March 29, 1996, and recorded in Volume 973, Page 766, said 640 acre tract also being the same land as described in Volume 69, Page 90, of the Deed Records of Panola County, Texas.  Recorded in Volume 1040 Page 299, Panola County, Texas.  (File 2564 Hancock Compressor Station)

18.Surface Easement and Road Easement from Elizabeth Hancock, (widow of O.L. Hancock) and Rosanne Hancock Williamson to American Central Eastern Texas Gas Company, L.P. Being a 0.13 acre station site situated in that certain called 406.75 acre tract in the Thomas Kelly Survey, Abstract 372, Panola County, Texas, and being described in a deed to Rosanne Hancock Williamson, et al., dated November 13, 1975, and recorded in Volume 591, Page 79 of the Deed Records of Panola County, Texas.  Recorded in Volume 1036, Page 329, Panola County, Texas.  (File 2598 - Hancock CDP)

19.Grant of Right of Way, Surface Easement, and Road Easement from Cosette C. Chamness, individually and as Trustee to Barber E. and Cosette C. Chamness Living Trust, to ACGC Gathering Company, L.L.C.  Being a centerline description for a proposed right of way, said right of way being over, under and across a called 75 acre tract, described in a deed from Cosette C. Chamness to Cosette C. Chamness (Trustee of the Barber E. & Cosette C. Chamness Living Trust) as recorded in Volume 1024, Page 666, of the official deed records of Panola County, Texas, said tracts being situated in the Geo. Robert Survey A-565 of said Panola County, Texas; also being over, under and across a called 5.672-acre tract described in a deed from Bobby L. Belew, et al to Barber E. Chamness as recorded in Volume 557, Page 694, of the said deed records of Panola County, Texas, said tract being situated in the Ben Smith Survey, A-886 of said Panola County, Texas; being a .344 acre station site over, under and across a called 5.672 acre tract described in a deed from Bobby L. Belew, et al to Barber E. Chamness as recorded in Volume 557, Page 694, of the official deed records of Panola County, Texas. Recorded in Volume 1052, Page 94, Panola County, Texas.  (File 2668 - Collins Dehy)

20.Grant of Right of Way, Surface Easement, and Road Easement from Ruby Grimes and Billy Grimes to ACGC Gathering Company, L.L.C.  Being a centerline description for a proposed right of way being over, under and across a called 72.22 acre tract described in a deed from Dolores Harris, et vir to Ruby Grimes as recorded in Volume 991, Page 450, of the official deed records of Panola County, Texas, said tracts being situated in the C. Flanagan Survey A-215 of Panola County, Texas; being a .336 acre station site and being a part of a called 72.22 acre tract described in a deed from Dolores Harris, et vir to Ruby Grimes as recorded in Volume 991, Page 450.  Recorded in Volume 1050, Page 253, Panola County, Texas.  (File 2674 - Thompson Dehy)

4

21.Surface Site Easement from Gordon A. Darnell, Darnell Lumber Co., Inc. to American Central Eastern Texas Gas Company, L.P.  Being a 0.888 acre surface site, said site being over, under and across a called 721.19 acre tract described in a deed to Darnell Lumber Company as recorded in Volume 564, Page 509, said tract being situated in the J. M. Lambert Survey, Abstract 418 and the T. Applewhite Survey, Abstract 35 of Panola County, Texas; and recorded in Volume 1110, Page 170, Panola County, Texas.  (File 3262 - Hull Compressor Station)

22.Surface Site Easement from M.C. & JoNell Young to American Central Eastern Texas Gas Company, L.P.  Being a 1.722 acre site situated in a called 91.25 acre tract as described in a deed from James Hollis Young to M.C. Young, et ux as recorded in Volume 751, Page 412, said tract being situated in the Samuel White Survey, Abstract 743 of Panola County, Texas; and recorded in Volume 1104, Page 457, Panola County, Texas.  (File 3272 - Roberts Compressor Station)

23.Surface Site Easement from Susan Stough Anthony & Janet Stough Young, by Debra Jones, Power of Attorney, to American Central Eastern Texas Gas Company, L.P. Being a 0.069 acre site being over, under and across a called 400 acre tract as described in a deed from R. Michael Hallum, Independent Administrator of the estate of Joy Powers to Susan Stough Anthony, et al as recorded in Volume 991, Page 675, said tract being situated in the John Parmer, Abstract 899, of Panola County, Texas; and recorded in Volume 1169, Page 90 and Volume 1169, Page 94, Panola County, Texas. (File 3409 - Deadwood valve site to Lagrone)

24.Right of Way Agreement from Richard & Annette Anderson to American Central Eastern Texas Gas Company, L.P. Being a 30’ x 30’ site, said site being over, under and across a tract of land situated in the Issac Hall Survey, Abstract 311, said tract being a called 117.87 acre tract described in a deed from G. W. Anderson, et al to Richard Anderson, et ux Annette Anderson as recorded n Volume 839, Page 66; recorded in Volume 1182, Page 115, Panola County, Texas.  (File 3437 - Hunt Allison CDP connect)

25.Grant of easement from Torch Energy Marketing, Inc. to American Central Gas Companies, Inc. to a 50’ x 50’ site located in the George Gillaspie Survey, Abstract 222, Panola County, Texas as stated in Article XVI, Miscellaneous Section of the Gas Gathering Agreement dated September 1, 1997.

5

Equipment and Vehicle Leases

Compressor Site	Specs	Number	Lease Payment	Term	Buyout Date	Buyout Amount
Big Tony	CAT 3516	4EK03292	7,511.03	36 Mo’s	6/27/2005	$	350,787.55
				48 Mo’s	6/27/2006	$	278,585.81
				62 Mo’s	8/27/2007	$	—
Devon/Ocean	CAT 3516	4EK03786	7,459.01	36 Mo’s	2/2/2006	$	350,695.71
				48 Mo’s	2/2/2007	$	278,585.81
				62 Mo’s	4/2/2008	$	—
	CAT 3516	4EK04004	8,554.85	60 Mo’s	7/1/2009	$	355,367.80 FMV
	CAT 3516	4EK04011	8,554.85	60 Mo’s	7/1/2009	$	355,367.80 FMV
	CAT 3516	4EK04010	8,554.85	60 Mo’s	7/1/2009	$	355,367.80 FMV
Hull	CAT 3516	4EK03104	7,452.15	36 Mo’s	9/1/2005	$	337,378.99
				48 Mo’s	9/1/2006	$	266,876.32
				60 Mo’s	9/1/2007	$	—
	CAT 3516	4EK03259	7,452.15	36 Mo’s	2/2/2006	$	337,378.99
				48 Mo’s	2/2/2007	$	266,876.32
				60 Mo’s	3/2/2008	$	—
Cheairs	CAT 3516	4EK03118	8,315.43	36 Mo’s	8/1/2005	$	301,144.10 FMV
				48 Mo’s	8/1/2006
	CAT 3516	4EK03108	8,315.43	36 Mo’s	8/1/2005	$	301,144.10 FMV
				48 Mo’s	8/1/2006
	CAT 3516	4EK03111	8,315.43	36 Mo’s	8/1/2005	$	301,144.10 FMV
				48 Mo’s	8/1/2006
Prior	CAT 3516	4EK03833	7,808.34	36 Mo’s		$	362,178.92
				48 Mo’s		$	283,018.47 FMV
				60 Mo’s
BP West Carthage	CAT 3516	4EK03996	8,554.85	60 Mo’s	7/1/2009	$	355,367.80 FMV
	CAT 3516	4EK04003	8,554.85	60 Mo’s	7/1/2009	$	355,367.80 FMV
Bethany	CAT 3516	NA	8,994.96	60 Mo’s	7/30/2009
	CAT 3516	NA	8,994.96	60 Mo’s	7/30/2009
	CAT 3516	NA	8,994.96	60 Mo’s	7/30/2009
	CAT 3516	NA	8,994.96	60 Mo’s	7/30/2009
	CAT 3516	NA	8,994.96	60 Mo’s	7/30/2009

VEHICLES - Closed-End Leases

Year; Make; Series; Body Style; Engine	Vin Number
2004 Chevrolet Silverado 2500HD 4WD	1GCHK29U94E190744
2003 Chevrolet Silverado 2SOOHD 4WTJ	1GCHK29U23E253732	eLynx
2004 Chevrolet Silverado 1500 ExtCab 4WD	2GCEK18T141213794
2004 Ford F150 4x4 Super Cab XL	1FTPX14534NA23903	eLynx
2003 Ford SD F250 4x4 Crew Cab	1FTNW21L83EC28375
2003 Chevrolet Silverado 1500 4WD	1GCEK19V13E263772
2004 Dodge Ram 2500 QuadCab	3D7KU28D34G177763
2004 Chevrolet Silverado 2500HD 2WD	1GCHC29U84E116373
2004 Chevrolet Silverado 2500 HO	1GCHK29U64E268736	eLynx
2004 Ford F150 4x4 Super Cab XL	1FTRW14W24KC71078
2002 Ford F150 4x4 Supercrew XLT	1FTRW08652KD25992
2004 Dodge Ram 2500 QuadCab	3D7KU28D54G177764
2003 Chevrolet Silverado 2500HD	1GCHK29U23E242567	eLynx

6

VEHICLES - Closed-End Leases

Year; Make; Series; Body Style; Engine	Vin Number
2004 Chevrolet Silverado 2500HD 4WD	1GCHK29U94E190744
2003 Chevrolet Silverado 2SOOHD 4WTJ	1GCHK29U23E253732	eLynx
2004 Chevrolet Silverado 1500 ExtCab 4WD	2GCEK18T141213794
2004 Ford F150 4x4 Super Cab XL	1FTPX14534NA23903	eLynx
2003 Ford SD F250 4x4 Crew Cab	1FTNW21L83EC28375
2003 Chevrolet Silverado 1500 4WD	1GCEK19V13E263772
2004 Dodge Ram 2500 QuadCab	3D7KU28D34G177763
2004 Chevrolet Silverado 2500HD 2WD	1GCHC29U84E116373
2004 Chevrolet Silverado 2500 HO	1GCHK29U64E268736	eLynx
2004 Ford F150 4x4 Super Cab XL	1FTRW14W24KC71078
2002 Ford F150 4x4 Supercrew XLT	1FTRW08652KD25992
2004 Dodge Ram 2500 QuadCab	3D7KU28D54G177764
2003 Chevrolet Silverado 2500HD	1GCHK29U23E242567	eLynx
2004 Chevrolet Silverado 2500 HD	1GCHK29U44E255175
2003 Ford F-350 4 x 2 Spr Cab Chas	1FDWX36P83EC02891
2004 Ford F350 4x2 Spr Cab XL	1FDWX36PX4EA49707
2004 Chevrolet Fleetside C2	1GCHK29U84E274781
2004 Ford F350 4x2 Super Cab XL	1FDWX36P34EC42460
2004 Ford F350 4x2 Super Cab XL	1FDWX36P84EA49706
2004 Ford F350 4x2 Super Cab XL	1FDWX36P64EA49705
2004 Chevrolet 3/4 ton 4x4 Ext. Cab	1GCHK29UX4E239255
2004 Ford F350 4x2 Super Cab XL	1FDWX36PX4ED81906

SCHEDULE 7.12

AGREEMENTS RESTRICTING LIENS ON LEASEHOLD INTERESTS

1.             Lease Agreement between Equitable Production Company and MarkWest Energy Appalachia, L.L.C.

SCHEDULE 10.02

ADDRESSES FOR NOTICES TO BORROWER,

GUARANTORS AND ADMINISTRATIVE AGENT

ADDRESS FOR NOTICES TO BORROWER

MARKWEST ENERGY OPERATING COMPANY, L.L.C.

155 Inverness Drive West

Suite 200

Englewood, Colorado 80112

Attn: Manager of contract Administration

Telephone: (303) 290-8700

Facsimile: (303) 290-8769

ADDRESS FOR NOTICES TO GUARANTORS

[Name of Guarantor]

155 Inverness Drive West

Suite 200

Englewood, Colorado 80112

Attn: Manager of contract Administration

Telephone: (303) 290-8700

Facsimile: (303) 290-8769

ADDRESSES FOR ROYAL BANK OF CANADA

Royal Bank of Canada’s Lending Office:

Royal Bank of Canada

New York Branch

One Liberty Plaza, 3^rd Floor

New York, New York 10006-1404

Attention: Manager, Loans Administration

Telephone: (212) 428-6332

Facsimile: (212) 428-2372

For matters related to letters of credit:

Attention: Manager, Trade Products

Telephone: (212) 428-6235

Facsimile: (212) 428-3015

1

in each case with a copy to:

Royal Bank of Canada

2800 Post Oak Boulevard

5700 Williams Tower

Houston, Texas 77056

Attention: Jason York

Telephone: (713) 403-5679

Facsimile: (713) 403-5624

Electronic Mail: Jason.York@rbccm.com

Administrative Agent’s Office:

Royal Bank of Canada

Agency Services Group

Royal Bank Plaza

P. O. Box 50, 200 Bay Street

12^th Floor, South Tower

Toronto, Ontario M5J 2W7

Attention: Manager Agency

Telephone: (416) 842-3901

Facsimile: (416) 842-4023

Wiring Instructions:

JPMorgan Chase Bank, New York, New York

ABA 021-000021

For account Royal Bank of Canada, New York

Swift Code: ROYCUS3X

A/C 920-1033363

For further credit to A/C 293-746-4, Transit 1269

Ref: MarkWest Energy

Attn: Agency Services

2

EXHIBIT A-1

FORM OF BORROWING NOTICE

Date:                         ,           

To:          Royal Bank of Canada, as Administrative Agent

Ladies and Gentlemen:

Reference is made to that certain Second Amended and Restated Credit Agreement, dated as of July      , 2004 (as amended, restated, extended, supplemented or otherwise modified in writing from time to time, the “Agreement;”the terms defined therein being used herein as therein defined), among MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), MarkWest Energy Partners, L.P., a Delaware limited partnership (the “MLP”), Royal Bank of Canada, as Administrative Agent, and the Lenders from time to time party thereto.

The undersigned hereby requests (select one):

I.              REVOLVER FACILITY

1.             Status Information for the Revolver Facility

(a)Amount of Revolver Facility: $265,000,000

(b)Loans outstanding prior to the Borrowing requested herein: $

(c)Letters of Credit outstanding prior to the Borrowing requested herein:  $

(d)Principal amount of Loans available to be borrowed (1(a) minus the sum of 1(b) and 1(c)): $

2.             Amount of Borrowing: $

3.             Requested date of Borrowing:                               , 200  .

4.             Requested Type of Loan and applicable Dollar amount:

(a)Base Rate Loan for $

(b)Eurodollar Rate Loan with Interest Period of:

(i)	one month for	$
(ii)	two months for	$
(iii)	three months for	$
(iv)	six months for	$

1

5.             Purpose of Loan:

• To refinance Indebtedness under First Amended and Restated Credit Agreement

• To finance the ACET Acquisition

• Working Capital and other general corporate purposes

• To fund Permitted Acquisitions

• To pay fees, costs and expenses owed pursuant to the Agreement

• To fund Quarterly Distribution (Section 6.12(b)(v) of the Agreement)

II.            TERM LOAN FACILITY

1.             Amount of Borrowing: $

2.             Requested date of Borrowing:                               , 2004.

3.             Requested Type of Loan and applicable Dollar amount:

(a)Base Rate Loan for $

(b)Eurodollar Rate Loan with Interest Period of:

(i)	one month for	$
(ii)	two months for	$
(iii)	three months for	$
(iv)	six months for	$

4.             Purpose of Loan:

• To refinance Indebtedness under First Amended and Restated Credit Agreement

• To finance the ACET Acquisition (no portion to be used to finance the acquisition of acquired working capital in connection with the ACET Acquisition)

The undersigned hereby certifies that the following statements will be true on the date of the proposed Borrowing(s) after giving effect thereto and to the application of the proceeds therefrom:

2

(a) the representations and warranties of the Borrower and the MLP contained in Article V of the Agreement are true and correct as though made on and as of such date (except such representations and warranties which expressly refer to an earlier date, which are true and correct as of such earlier date);

(b) on the day immediately following the ACET Acquisition the Borrower will have a minimum of $25,000,000 in Revolver Loan availability (inclusive of any L/C Obligation unrelated to the ACET Acquisition); and

(c) no Default or Event of Default has occurred and is continuing, or would result from such proposed Borrowing(s).

The Borrowing requested herein complies with Sections 2.01, Sections 2.02 and 2.03 of the Agreement, as applicable.

MARKWEST ENERGY OPERATING COMPANY,
L.L.C., a Delaware limited liability company, as Borrower
By	MARKWEST ENERGY PARTNERS, L.P.,
	its Managing Member
By	MARKWEST ENERGY GP, L.L.C., its
	General Partner
By:
Name:
Title:

3

EXHIBIT A-2

FORM OF CONVERSION/CONTINUATION NOTICE

Date:                                  ,           

TO:         Royal Bank of Canada, as Administrative Agent

Ladies and Gentlemen:

Reference is made to that certain Second Amended and Restated Credit Agreement, dated as of July      , 2004 (as amended, restated, extended, supplemented or otherwise modified in writing from time to time, the “Agreement;” the terms defined therein being used herein as therein defined), among MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), MarkWest Energy Partners, L.P., a Delaware limited partnership (the “MLP”), Royal Bank of Canada, as Administrative Agent, and the Lenders from time to time party thereto.

The undersigned hereby requests (select one):

I.              REVOLVER FACILITY

1.Amount of [conversion] [continuation]: $

2.	Existing rate:			Check applicable blank
	(a)	Base Rate
	(b)	Eurodollar Rate Loan with Interest Period of:
		(i)	one month
		(ii)	two months
		(iii)	three months
		(iv)	six months

3.If a Eurodollar Rate Loan, date of the last day of the Interest Period for such Loan:                        , 200   .

The Revolver Loan described above is to be [converted] [continued] as follows:

4.Requested date of [conversion] [continuation]:                                  , 200    .

5.Requested Type of Loan and applicable Dollar amount:

(a)Base Rate Loan for $

(b)Eurodollar Rate Loan with Interest Period of:

1

(i)	one month for	$
(ii)	two months for	$
(iii)	three months for	$
(iv)	six months for	$

II.            TERM LOAN FACILITY

1.Amount of [conversion] [continuation]: $

2.	Existing rate:			Check applicable blank
	(a)	Base Rate
	(b)	Eurodollar Rate Loan with Interest Period of:
		(i)	one month
		(ii)	two months
		(iii)	three months
		(iv)	six months

3.If a Eurodollar Rate Loan, date of the last day of the Interest Period for such Loan:                     , 200    .

The Term Loan described above is to be [converted] [continued] as follows:

4.Requested date of [conversion] [continuation]:                            , 200   .

5.Requested Type of Loan and applicable Dollar amount:

(a)Base Rate Loan for $

(b)Eurodollar Rate Loan with Interest Period of:

(i)	one month for	$
(ii)	two months for	$
(iii)	three months for	$
(iv)	six months for	$

2

The [conversion] [continuation] requested herein complies with Sections 2.01, Sections 2.02 and 2.03 of the Agreement, as applicable.

MARKWEST ENERGY OPERATING
COMPANY, L.L.C., a Delaware limited liability
company, as Borrower
	By	MARKWEST ENERGY PARTNERS, L.P.,
		its Managing Member
	By	MARKWEST ENERGY GP, L.L.C., its
		General Partner
	By:
	Name:
	Title:

1

EXHIBIT B-1

FORM OF REVOLVER NOTE

$ July      , 2004

FOR VALUE RECEIVED, the undersigned (the “Borrower”), hereby promises to pay to the order of                             (the “Lender”), on the Revolver Maturity Date (as defined in the Credit Agreement referred to below) the principal amount of                           Dollars ($                     ), or such lesser principal amount of Revolver Loans made by Lender under the Revolver Facility (both as defined in such Credit Agreement) due and payable by the Borrower to the Lender on the Revolver Maturity Date under that certain Second Amended and Restated Credit Agreement, dated as of even date herewith (as amended, restated, extended, supplemented or otherwise modified in writing from time to time, the “Credit Agreement”; the terms defined therein being used herein as therein defined), among the Borrower, MarkWest Energy Partners, L.P., a Delaware limited partnership, the Lenders from time to time party thereto, and Royal Bank of Canada, as Administrative Agent.

The Borrower promises to pay interest on the unpaid principal amount of each Revolver Loan from the date of such Revolver Loan until such principal amount is paid in full, at such interest rates, and at such times as are specified in the Credit Agreement.  All payments of principal and interest shall be made to the Administrative Agent for the account of the Lender in Dollars in immediately available funds to the account designated by the Administrative Agent in the Credit Agreement.  If any amount is not paid in full when due hereunder, such unpaid amount shall bear interest, to be paid upon demand, from the due date thereof until the date of actual payment (and before as well as after judgment) computed at the per annum rate set forth in the Credit Agreement.

This Revolver Note is one of the Revolver Notes referred to in the Credit Agreement, is entitled to the benefits thereof and is subject to optional and mandatory prepayment in whole or in part as provided therein.  This Revolver Note is also entitled to the benefits of each Guaranty.  Upon the occurrence of one or more of the Events of Default specified in the Credit Agreement, all amounts then remaining unpaid on this Revolver Note shall become, or may be declared to be, immediately due and payable all as provided in the Credit Agreement.  Revolver Loans made by the Lender shall be evidenced by one or more loan accounts or records maintained by the Lender in the ordinary course of business.  The Lender may also attach schedules to this Revolver Note and endorse thereon the date, amount and maturity of its Revolver Loans and payments with respect thereto.

This Revolver Note is a Loan Document and is subject to Section 10.10 of the Credit Agreement, which is incorporated herein by reference the same as if set forth herein verbatim.

The Borrower, for itself, its successors and assigns, hereby waives diligence, presentment, protest and demand and notice of protest, notice of intent to accelerate, notice of acceleration, demand, dishonor and non-payment of this Revolver Note.

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THIS REVOLVER NOTE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

MARKWEST ENERGY OPERATING
COMPANY, L.L.C., a Delaware limited liability
company, as Borrower
By	MARKWEST ENERGY PARTNERS, L.P.,
	its Managing Member
By	MARKWEST ENERGY GP, L.L.C., its
	General Partner
By:
Name:
Title:

2

EXHIBIT B-2

FORM OF TERM NOTE

$ July      , 2004

FOR VALUE RECEIVED, the undersigned (the “Borrower”), hereby promises to pay to the order of                       (the “Lender”), on the Term Loan Maturity Date (as defined in the Credit Agreement referred to below) the principal amount of                            Dollars ($                 ), or such lesser principal amount of Term Loans made by Lender under the Term Loan Facility (both as defined in such Credit Agreement) due and payable by the Borrower to the Lender on the Term Loan Maturity Date under that certain Second Amended and Restated Credit Agreement, dated as of even date herewith (as amended, restated, extended, supplemented or otherwise modified in writing from time to time, the “Credit Agreement”; the terms defined therein being used herein as therein defined), among the Borrower, MarkWest Energy Partners, L.P., a Delaware limited partnership, the Lenders from time to time party thereto, and Royal Bank of Canada, as Administrative Agent.

The Borrower promises to pay interest on the unpaid principal amount of each Term Loan from the date of such Term Loan until such principal amount is paid in full, at such interest rates, and at such times as are specified in the Credit Agreement.  All payments of principal and interest shall be made to the Administrative Agent for the account of the Lender in Dollars in immediately available funds to the account designated by the Administrative Agent in the Credit Agreement.  If any amount is not paid in full when due hereunder, such unpaid amount shall bear interest, to be paid upon demand, from the due date thereof until the date of actual payment (and before as well as after judgment) computed at the per annum rate set forth in the Credit Agreement.

This Term Note is one of the Term Notes referred to in the Credit Agreement, is entitled to the benefits thereof and is subject to optional and mandatory prepayment in whole or in part as provided therein.

This Term Note is also entitled to the benefits of each Guaranty.  Upon the occurrence of one or more of the Events of Default specified in the Credit Agreement, all amounts then remaining unpaid on this Term Note shall become, or may be declared to be, immediately due and payable all as provided in the Credit Agreement.  Term Loans made by the Lender shall be evidenced by one or more loan accounts or records maintained by the Lender in the ordinary course of business.  The Lender may also attach schedules to this Term Note and endorse thereon the date, amount and maturity of its Term Loans and payments with respect thereto.

This Term Note is a Loan Document and is subject to Section 10.10 of the Credit Agreement, which is incorporated herein by reference the same as if set forth herein verbatim.

The Borrower, for itself, its successors and assigns, hereby waives diligence, presentment, protest and demand and notice of protest, notice of intent to accelerate, notice of acceleration, demand, dishonor and non-payment of this Term Note.

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THIS TERM NOTE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

MARKWEST ENERGY OPERATING
COMPANY, L.L.C., a Delaware limited liability
company, as Borrower
By	MARKWEST ENERGY PARTNERS, L.P.,
	its Managing Member
By	MARKWEST ENERGY GP, L.L.C., its
	General Partner
By:
Name:
Title:

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EXHIBIT C

FORM OF COMPLIANCE CERTIFICATE

(Pursuant to Section 6.02of the Agreement)

Financial Statement Date:                       ,       

To:          Royal Bank of Canada, as Administrative Agent

Ladies and Gentlemen:

Reference is made to that certain Second Amended and Restated Credit Agreement, dated as of July    , 2004 (as amended, restated, extended, supplemented or otherwise modified in writing from time to time, the “Agreement;” the terms defined therein being used herein as therein defined), MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), MarkWest Energy Partners, L.P., a Delaware limited partnership, the Lenders from time to time party thereto, and Royal Bank of Canada, as Administrative Agent. Capitalized terms used herein but not defined herein shall have the meaning set forth in the Agreement.

The undersigned Responsible Officers hereby certify as of the date hereof that they are the                                of the General Partner of the MLP and the                              of the Borrower, and that, as such, they are authorized to execute and deliver this Certificate to the Administrative Agent on the behalf of the MLP and the Borrower, and that:

[Use the following for fiscal year-end financial statements]

Attached hereto as Schedule 1are the year-end audited consolidated financial statements of the MLP and its Subsidiaries required by Section 6.01(a)of the Agreement for the fiscal year of the MLP ended as of the above date, together with the report and opinion of an independent certified public accountant required by such section; and

Attached hereto as Schedule 2are the year-end unaudited consolidated financial statements of the MLP and its Subsidiaries required by Section 6.01(b) of the Agreement for the fiscal year of the MLP ended as of the above date, which financial statements fairly present the financial condition results of operation and cash flows of the MLP and its Subsidiaries in accordance with GAAP.

[Use the following for fiscal quarter-end financial statements]

Attached hereto as Schedule 1are, the unaudited consolidated financial statements of the MLP and its Subsidiaries required by Section 6.01(c) of the Agreement for the first three fiscal quarters of the MLP ended as of the above date, together with a certificate of a Responsible Officer of the MLP or the Borrower, as applicable, stating that such financial statements fairly present the financial condition, results of operations and cash flows of the MLP and the Borrower, as applicable, and their respective Subsidiaries in accordance with GAAP as at such

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date and for such period, subject only to normal year-end audit adjustments and the absence of footnotes.

[Use the following for both fiscal year-end and quarter-end financial statements]

1.             The undersigned has reviewed and is familiar with the terms of the Agreement and has made, or has caused to be made under his/her supervision, a detailed review of the transactions and condition (financial or otherwise) of the Borrower during the accounting period covered by the attached financial statements.

2.             A review of the activities of the MLP and the Borrower during such fiscal period has been made under the supervision of the undersigned with a view to determining whether during such fiscal period the MLP and the Borrower performed and observed all their respective Obligations under the Loan Documents, and no Default or Event of Default has occurred and is continuing except as follows (list of each such Default or Event of Default and include the information required by Section 6.03 of the Credit Agreement):

3.             The covenant analyses and information set forth on Schedule 3 attached hereto are true and accurate on and as of the date of this Certificate.

IN WITNESS WHEREOF, the undersigned has executed this Certificate as of                     ,
                .

	MARKWEST ENERGY OPERATING
	COMPANY, L.L.C., a Delaware limited liability
	company, as Borrower
By	MARKWEST ENERGY PARTNERS, L.P.,
	its Managing Member
By	MARKWEST ENERGY GP, L.L.C., its
	General Partner
By:
Name:
Title:

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For the Quarter/Year ended                                                          (“Statement Date”)

SCHEDULE 3

to the Compliance Certificate

($ in 000’s)

*[MAY NEED TO BE UPDATED IF SUBORDINATED INDEBTEDNESS NOT PERMITTED]

I.      Section 7.04 — Indebtedness
1.     Outstanding Principal Amount of Subordinated Indebtedness permitted by Section 7.04(c).	$
a.     Has all such Refinancing Indebtedness been Subordinated pursuant to Section 7.04(c)	Yes/No
2.     Outstanding Principal Amount of Purchase Money Indebtedness for fixed or capital assets permitted by Section 7.04(e)(may not exceed $7,500,000)	$
3.     Outstanding Principal Amount of other Indebtedness permitted by Section 7.04(f)(may not exceed $7,500,000)	$
II.    Section 7.15(a) — Interest Coverage Ratio.
A.    Consolidated EBITDA for four consecutive fiscal quarters ending on the Statement Date (“Subject Period”)(see Credit Agreement definition of “Consolidated EBITDA”):
[See WORKSHEET A for Lines 1-9]
10.   Consolidated EBITDA (prior to pro forma adjustments for Permitted Acquisitions pursuant to Section 7.15(e)(i))(from Worksheet A):	$
11.   Pro forma adjustments to EBITDA for Permitted Acquisitions during the Subject Period (Section 7.15(e)(i)),giving effect to such Permitted Acquisitions on a pro forma basis for the Subject Period as if such Permitted Acquisitions occurred on the first day of the Subject Period:	$
12.   Consolidated EBITDA, including pro forma adjustments for Permitted Acquisitions (Lines 11.A.10 + 11.A.11):	$
B.    Consolidated Interest Charges for Subject Period:	$

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1.     Consolidated Interest Charges for the four consecutive fiscal quarters ending on the Statement Date:
2.     Pro forma adjustment for Interest Charges during the four consecutive fiscal quarters ending on the Statement Date (Section 7.15(e)(ii)):			$
3.     Consolidated Interest Charges, including pro forma adjustments (Lines II.B.1 + II.B.2):			$
C.    Interest Coverage Ratio:
1.     Consolidated EBITDA adjusted for Acquisitions (Line II.A.12):			$
2.     Consolidated Interest Charges adjusted for Permitted Acquisitions (Line II.B.3):			$
3.     Imputed interest charges on Synthetic Lease of the MLP and its Subsidiaries for Subject Period:			$
4.     Interest Coverage Ratio (Line II.C.1  (Lines II.C.2 + II.C.3)):			to 1.0
		Minimum required: before 12/31/04:  2.0:1.0 on and after 12/31/04:  3.0:1.0
III.   Section 7.15(b) - Leverage Ratio
A.    Consolidated Funded Debt (borrowed money indebtedness, Capital Leases, and Synthetic Leases):			$
B.    Consolidated EBITDA (including pro forma adjustments for Permitted Acquisitions) (Line II.A.12 above):			$
C.    Leverage Ratio (Line III.A ÷ III.B):			to 1.0
	Maximum permitted: before 12/31/04:  6.75:1.0 on or after 12/31/04:  5.5:1.0
IV.   Section 7.15(c) - Minimum Net Worth			$

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A.    Net Worth at Statement Date	$
B.    50% of proceeds of all equity issued subsequent to Restatement Date:	$
C.    Minimum Net Worth ($125,000,000 + Line IV.B):	$
D.    Is Line IV.A greater than or equal to Line IV.C?	Yes/No
V.    Calculation of Compliance with Sections 7.07(c) and Section 2.04(b)(Dispositions and Mandatory Prepayments)
A.    Section 2.04(b)(i)and Section 7.07(c): Attach a report showing each Disposition of property for fair market value for cash during the two (2) fiscal quarters ending on the Statement Date. For each such Disposition show:
1.     The date that Net Cash Proceeds from such Disposition were received (the “Receipt Date”).	$
2.     The amount of Net Cash Proceeds received from such Disposition.	$
3.     The total amount of Net Cash Proceeds from Dispositions for fair market value for cash during the period from the Closing Date to such Receipt Date.	$
4.     reserved.	$
5.     reserved.	$
6.     reserved.	$
7.     reserved.	$
8.     reserved.	$
9.     Amount of Loans to be prepaid and amount of Commitment reduction (Line V.A. 8).	$

[END OF SCHEDULE 2 - WORKSHEET A, B AND C FOLLOW]

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WORKSHEET A
CONSOLIDATED EBITDA CALCULATION

Consolidated EBITDA for four consecutive fiscal quarters ending on the Statement Date (“Subject Period”)(see Credit Agreement definition of “Consolidated EBITDA”):
For fiscal quarters ending on or after June 30, 2004:
1.     Consolidated Net Income for Subject Period:	$
2.     Consolidated Interest Charges for Subject Period:	$
3.     Provision for income taxes for Subject Period:	$
4.     Depreciation expenses for Subject Period:	$
5.     Depletion expenses for Subject Period:	$
6.     Amortization expenses for Subject Period:	$
7.     Other non-cash charges and expenses:	$
8.     [reserved]	$
9.     [reserved]	$
10.   Consolidated EBITDA (prior to pro forma adjustments for Permitted Acquisitions pursuant to Section 7.15(d)(i)) (Lines A.1. + A.2. + A.3. + A.4 t A.5 + A.6 + A.7) (to be entered as Line II.A. 10. on Schedule 3):	$

6

WORKSHEET B

Intentionally Omitted

7

WORKSHEET C
CALCULATION OF AVAILABLE CASH

Available Cash of the MLP (calculated pursuant to the MLP’s Partnership Agreement)
A.    Cash and cash equivalents of the MLP, the Borrower, and their respective subsidiaries (the “Partnership Group”) on hand at the end of the quarter:	$
B.    All additional cash and cash equivalents of the Partnership Group on hand on the date of determination resulting from working capital borrowings made after the end of the quarter:	$
C.    Cash reserves to provide for the proper conduct of the business of the Partnership Group (including reserves for future capital expenditures and for future credit needs of the MLP and its subsidiaries) after the quarter:*	$
D.    Cash reserves to comply with applicable law, or any loan agreement, security agreement, mortgage, or any debt instrument or other agreement or obligation to which the Partnership Group is a party or its assets are subject:*	$
E.     Cash reserves to provide funds for distributions under Section 6.4 or 6.5 of the MLP’s Partnership Agreement for any one or more of the next four quarters:*	$
F.     Available Cash of the MLP (Line A + B - C - D - E) (to be entered as Line VI.A on Schedule 3):	$

*If there is an amount entered in C, D, or above, attach a general description of purpose/reason for such reserves.

Available Cash of the Borrower (calculated pursuant to the Borrower’s Limited Liability Company Agreement)
A.    All cash and cash equivalents of the Borrower or any of its subsidiaries (the “Company Group”) on hand at the end of the quarter:	$
B.    All additional cash and cash equivalents of the Company Group on hand on the date of determination of Available Cash with respect to such quarter resulting from working capital borrowings made subsequent to the end of such quarter (limited to $2,250,000 in any four (4) consecutive fiscal quarters):	$

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C.    Cash reserves to provide for the proper conduct of the business of the Company Group (including reserves for future capital expenditures and for anticipated future credit needs of the Company Group) subsequent to such quarter:*	$
D.    Cash reserves to comply with applicable law or any loan agreement, security agreement, mortgage, debt instrument or other agreement or obligation to which any member of the Partnership Group is a party or by which it is bound or its assets are subject:*	$
E.     Cash reserves to provide funds for distributions under Section 6.4 or 6.5 of the MLP’s Partnership Agreement in respect of any one or more of the next four quarters:*	$
F.     Available Cash of the Borrower (Line A + B - C - D - E) (to be entered as Line VI.B on Schedule 3):	$

*If there is an amount entered in C, D, or above, attach a general description of purpose/reason for such reserves.

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EXHIBIT D

FORM OF ASSIGNMENT AND ASSUMPTION

This Assignment and Assumption (the “Assignment and Assumption”) is dated as of the Effective Date set forth below and is entered into by and between [Insert name of Assignor] (the “Assignor”) and [Insert name of Assignee] (the “Assignee”). Capitalized terms used but not defined herein shall have the meanings given to them in the Second Amended and Restated Credit Agreement identified below (as may be amended, the “Credit Agreement”), receipt of a copy of which is hereby acknowledged by the Assignee. The Standard Terms and Conditions set forth in Annex I attached hereto are hereby agreed to and incorporated herein by reference and made a part of this Assignment and Assumption as if set forth herein in full.

For an agreed consideration, the Assignor hereby irrevocably sells and assigns to the Assignee, and the Assignee hereby irrevocably purchases and assumes from the Assignor, subject to and in accordance with the Standard Terms and Conditions and the Credit Agreement, as of the Effective Date inserted by the Administrative Agent as contemplated below (i) all of the Assignor’s rights and obligations in its capacity as a Lender under the Credit Agreement and any other documents or instruments delivered pursuant thereto to the extent related to the amount and percentage interest identified below of all of such outstanding rights and obligations of the Assignor under the respective facilities identified below and (ii) to the extent permitted to be assigned under applicable law, all claims, suits, causes of action and any other right of the Assignor (in its capacity as a Lender) against any Person, whether known or unknown, arising under or in connection with the Credit Agreement, any other documents or instruments delivered pursuant thereto or the loan transactions governed thereby or in any way based on or related to any of the foregoing, including, but not limited to, contract claims, tort claims, malpractice claims, statutory claims and all other claims at law or in equity related to the rights and obligations sold and assigned pursuant to clause (i) above (the rights and obligations sold and assigned pursuant to clauses (i) and (ii) above being referred to herein collectively as, the “Assigned Interest”). Such sale and assignment is without recourse to the Assignor and, except as expressly provided in this Assignment and Assumption, without representation or warranty by the Assignor.

1.	Assignor:
2.	Assignee:
		[and is an Affiliate/Approved Fund of [identify Lender](1)
3.	Borrower(s):	MarkWest Energy Operating Company, L.L.C.
4.	Administrative Agent:	Royal Bank of Canada, as the administrative agent under the Credit Agreement

(1)Select as applicable.

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5.	Credit Agreement:	The $315,000,000 Second Amended and Restated Credit Agreement dated as of July 30, 2004 among MarkWest Energy Operating Company, L.L.C., MarkWest Energy Partners, L.P., the Lenders parties thereto, and Royal Bank of Canada, as Administrative Agent.
6.	Assigned Interest:

	Aggregate Amount of Commitment/Loans for all Lenders*	Amount of Commitment/Loans Assigned*	Percentage Assigned of Commitment/Loans(2)
Revolver Loans:	$	$		%
Term Loans:	$	$		%
Total:	$	$		%

[7.Trade Date:                                     ](3)

Effective Date:                             , 20       [TO BE INSERTED BY ADMINISTRATIVE AGENT AND WHICH SHALL BE THE EFFECTIVE DATE OF RECORDATION OF TRANSFER IN THE REGISTER THEREFOR.]

The terms set forth in this Assignment and Assumption are hereby agreed to:

ASSIGNOR

[NAME OF ASSIGNOR]

By:

Title:

ASSIGNEE

[NAME OF ASSIGNEE]

By:

Title:

*Amount to be adjusted by the counterparties to take into account any payments or prepayments made between the Trade Date and the Effective Date.

(2)Set forth, to at least 9 decimals, as a percentage of the Commitment/Loans of all Lenders thereunder.

(3)To be completed if the Assignor and the Assignee in end that the minimum assignment amount is to be determined as of the date specified in paragraph 7 (the “Trade Date”).

2

Consented to and Accepted:
[NAME OF ADMINISTRATIVE AGENT], as Administrative Agent
By
	Title:
[Consented to:](4)
MARKWEST ENERGY OPERATING COMPANY, L.L.C., a Delaware limited liability company
By:		MARKWEST ENERGY PARTNERS, L.P.,
		its Managing Member
By:		MARKWEST ENERGY GP, L.L.C.,
		its General Partner
By
Name:
Title:

(4)To be added only if the consent of the Borrower is required by the terms of the Credit Agreement.

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ANNEX 1

TO ASSIGNMENT AND ASSUMPTION

STANDARD TERMS AND CONDITIONS FOR

ASSIGNMENT AND ASSUMPTION

1.Representations and Warranties.

1.1Assignor. The Assignor (a) represents and warrants that (i) it is the legal and beneficial owner of the Assigned Interest, (ii) the Assigned Interest is free and clear of any lien, encumbrance or other adverse claim and (iii) it has full power and authority, and has taken all action necessary, to execute and deliver this Assignment and Assumption and to consummate the transactions contemplated hereby; and (b) assumes no responsibility with respect to (i) any statements, warranties or representations made in or in connection with the Credit Agreement or any other Loan Document, (ii) the execution, legality, validity, enforceability, genuineness, sufficiency or value of the Loan Documents or any collateral thereunder, (iii) the financial condition of the Borrower, any of its Subsidiaries or Affiliates or any other Person obligated in respect of any Loan Document or (iv) the performance or observance by the Borrower, any of its Subsidiaries or Affiliates or any other Person of any of their respective obligations under any Loan Document.

1.2.Assignee. The Assignee (a) represents and warrants that (i) it has full power and authority, and has taken all action necessary, to execute and deliver this Assignment and Assumption and to consummate the transactions contemplated hereby and to become a Lender under the Credit Agreement, (ii) it meets all requirements of an Eligible Assignee under the Credit Agreement (subject to receipt of such consents as may be required under the Credit Agreement), (iii) from and after the Effective Date, it shall be bound by the provisions of the Credit Agreement as a Lender thereunder and, to the extent of the Assigned Interest, shall have the obligations of a Lender thereunder, (iv) it has received a copy of the Credit Agreement, together with copies of the most recent financial statements delivered pursuant to Section 6.01 thereof, as applicable, and such other documents and information as it has deemed appropriate to make its own credit analysis and decision to enter into this Assignment and Assumption and to purchase the Assigned ~Interest on the basis of which it has made such analysis and decision independently and without reliance on the Administrative Agent or any other Lender, and (v) if it is a Foreign Lender, attached to the Assignment and Assumption is any documentation required to be delivered by it pursuant to the terms of the Credit Agreement, duly completed and executed by the Assignee; and (b) agrees that (i) it will, independently and without reliance on the Administrative Agent, the Assignor or any other Lender, and based on such documents and information as it shall deem appropriate at the time, continue to make its own credit decisions in taking or not taking action under the Loan Documents, and (ii) it will perform in accordance with their terms all of the obligations which by the terms of the Loan Documents are required to be performed by it as a Lender.

2.Payments. From and after the Effective Date, the Administrative Agent shall make all payments in respect of the Assigned Interest (including payments of principal, interest, fees and other amounts) to the Assignor for amounts which have accrued to but excluding the

4

Effective Date and to the Assignee for amounts which have accrued from and after the Effective Date.

3.General Provisions. This Assignment and Assumption shall be binding upon, and inure to the benefit of, the parties hereto and their respective successors and assigns. This Assignment and Assumption may be executed in any number of counterparts, which together shall constitute one instrument. Delivery of an executed counterpart of a signature page of this Assignment and Assumption by telecopy shall be effective as delivery of a manually executed counterpart of this Assignment and Assumption. This Assignment and Assumption shall be governed by, and construed in accordance with, the law of the State of Texas.

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Exhibit E-1

AMENDED AND RESTATED GUARANTY

Originally dated as of May 24, 2002

and

as amended and restated as of July 30, 2004

THIS AMENDED AND RESTATED GUARANTY (this “Guaranty”), dated as of July    , 2004, is made by MARKWEST ENERGY PARTNERS, L.P., a Delaware limited partnership (the “Guarantor”), in favor of ROYAL BANK OF CANADA, as administrative agent for the Lenders (as defined below).

W I T N E S S E T H:

WHEREAS, MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), Guarantor, Bank of America, N.A., individually and as initial administrative agent (“Bank of America”), Fortis Capital Corp. (“Fortis”), Wells Fargo Bank, N.A. (“Wells Fargo”), U.S. Bank, National Association (“US Bank”), Bank of Oklahoma, N.A. (“Bank of Oklahoma”) and Royal Bank of Canada (“Royal Bank”; Bank of America, Fortis, Wells Fargo, US Bank, Bank of Oklahoma and Royal Bank collectively called the “Original Lenders”) entered into a Credit Agreement originally dated May 20, 2002 providing for an aggregate credit facility of $60,000,000 (the “Original Credit Agreement”); and

WHEREAS, as a condition precedent to the Original Lenders making advances under the Original Credit Agreement, the Guarantor entered into a Guaranty dated May 24, 2002 in favor of the Original Lenders guaranteeing payment of the indebtedness of the Borrower under the Original Credit Agreement (as amended, ratified and supplemented from time to time, the “Original Guaranty”); and

WHEREAS, the Original Credit Agreement was amended by a First Amendment to Credit dated March 28, 2003 among the Borrower, the Guarantor and the Original Lenders (the “First Amendment”) and pursuant to the First Amendment (A) Royal Bank of Canada (“Royal Bank”) succeeded Bank of America as administrative agent (the “Administrative Agent”) under the Original Credit Agreement (the Original Credit Agreement, as amended by the First Amendment herein called the “Original Amended Credit Agreement”) and (B) the aggregate credit facility was increased to $75,000,000; and

WHEREAS, the Original Amended Credit Agreement was amended and restated in its entirety by an Amended and Restated Credit Agreement dated December 1, 2003 among Borrower, the Guarantor, Royal Bank, as administrative agent, Bank One, NA (“Bank One”), as documentation agent, and Fortis, as syndication agent, providing for an aggregate credit facility of $140,000,000 (as amended, the “First Amended and Restated Credit Agreement”); and

WHEREAS, Borrower has requested an increase in the number and amount of the credit facilities under the First Amended and Restated Credit Agreement and Royal Bank and certain other lenders party thereto (collectively, the “Lenders”) are willing to increase the number and

1

amount of the credit facilities under the First Amended and Restated Credit Agreement and will do so by amending and restating the First Amended and Restated Credit Agreement in its entirety of even date herewith pursuant to a Second Amended and Restated Credit Agreement (as the same may hereafter be amended, supplemented and restated, the “Second Amended and Restated Credit Agreement”); and

WHEREAS, as a condition precedent to the making of Loans under and as defined in the Second Amended and Restated Credit Agreement, the Guarantor is required to execute and deliver this Guaranty;

WHEREAS, the Guarantor has duly authorized the execution, delivery and performance of this Guaranty;

WHEREAS, the Guarantor owns all of the membership interests in the Borrower and controls the management of the Borrower;

WHEREAS, it is in the best interests of the Guarantor to execute this Guaranty inasmuch as the Guarantor will derive substantial direct and indirect benefits from the extensions of credit made from time to time to or for the account of the Borrower;

NOW THEREFORE, for good and valuable consideration the receipt of which is hereby acknowledged, and in order to induce the Lenders to make Loans to the Borrower pursuant to the Second Amended and Restated Credit Agreement by fulfilling the requirements of the Second Amended and Restated Credit Agreement, the Guarantor agrees, for the benefit of each Lender, as follows:

ARTICLE I

DEFINITIONS

SECTION 1.1Certain Terms. The following capitalized terms when used in this

Guaranty, including its preamble and recitals, shall have the following meanings (such definitions to be equally applicable to the singular and plural forms thereof):

“Administrative Agent” is defined in the third recital.

“Borrower” is defined in the first recital.

“Commitments” means each Commitment as defined in the Second Amended and Restated Credit Agreement.

“Guarantor” is defined in the preamble.

“Guaranty” is defined in the preamble.

“Lenders” is defined in the first recital.

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“Loans” means each Loan as defined in the Second Amended and Restated Credit Agreement.

“Loan Documents” means the Loan Documents as defined in the Second Amended and Restated Credit Agreement.

“Note” means each Note as defined in the Second Amended and Restated Credit Agreement.

“Obligations” means the Obligations as defined in the Second Amended and Restated Credit Agreement.

“Obligor” means the Borrower or any other Person (other than the Administrative Agent or any Lender) obligated under any Loan Document.

“Required Lenders” means the Required Lenders as defined in the Second Amended and Restated Credit Agreement.

“Subsidiary Guarantors” means Subsidiaries of Borrower that have guaranteed all or any part of the Obligations.

“Taxes” is defined in clause (a) of Section 2. 7.

“U.C.C.” means the Uniform Commercial Code as in effect in the State of Texas.

SECTION 1.2Second Amended and Restated Credit Agreement Definitions. Unless otherwise defined herein or the context otherwise requires, capitalized terms used in this Guaranty, including its preamble and recitals, have the meanings provided in the Second Amended and Restated Credit Agreement,

SECTION 1.3U.C.C. Definitions. Unless otherwise defined herein or the context otherwise requires, terms for which meanings are provided in the U.C.C. are used in this Guaranty, including its preamble and recitals, with such meanings.

ARTICLE II

GUARANTY PROVISIONS

SECTION 2.1Guaranty. The Guarantor hereby absolutely, unconditionally, and irrevocably (1) guarantees the full and punctual payment when due, whether at stated maturity, by required prepayment, declaration, acceleration, demand or otherwise, of all Obligations of the Borrower and each other Obligor now or hereafter existing under each of the Second Amended and Restated Credit Agreement, the Notes and each other Loan Document to which the Borrower or such other Obligor is or may become a party, whether for principal, interest, fees, expenses or otherwise (including all such amounts which would become due but for the operation of the automatic stay under Section 362(a) of the United States Bankruptcy Code, 11 U.S.C. §362(a),

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and the operation of Sections 502(b) and 506(b) of the United States Bankruptcy Code, 11 U.S.C. §502(b) and §506(b)), and (2) indemnifies and holds harmless each Lender and each holder of a Note for any and all costs and expenses (including reasonable attorney’s fees and expenses) incurred by such Lender or such holder, as the case may be, in enforcing any rights under this Guaranty; provided however, that the Guarantor shall be liable under this Guaranty for the maximum amount of such liability that can be hereby incurred without rendering this Guaranty, as it relates to the Guarantor, voidable under applicable law relating to fraudulent conveyance or fraudulent transfer, and not for any greater amount. This Guaranty constitutes a guaranty of payment when due and not of collection, and the Guarantor specifically agrees that it shall not be necessary or required that any Lender or any holder of any Note exercise any right, assert any claim or demand or enforce any remedy whatsoever against the Borrower or any other Obligor (or any other Person) before or as a condition to the obligations of the Guarantor hereunder.

SECTION 2.2Acceleration of Guaranty. The Guarantor agrees that, in the event of the occurrence of any event of the type described in Section 8.01(f) or Section 8.01(g) of the Second Amended and Restated Credit Agreement, with respect to the Borrower, any other Obligor or the Guarantor, and if such event shall occur at a time when any of the Obligations may not then be due and payable, the Guarantor will pay to the Lenders forthwith the full amount which would be payable hereunder by the Guarantor if all such Obligations were then due and payable.

SECTION 2.3Guaranty Absolute, etc.  This Guaranty shall in all respects be a continuing, absolute, unconditional and irrevocable guaranty of payment, and shall remain in full force and effect until all Obligations of the Borrower and each other Obligor have been paid in full, all obligations of the Guarantor hereunder shall have been paid in full, all Commitments shall have terminated and, except as provided in Section 10.01(e) of the Second Amended and Restated Credit Agreement, all Lender Hedging Agreements have terminated. Guarantor may not rescind or revoke its obligations hereunder. The Guarantor guarantees that the Obligations of the Borrower and each other Obligor will be paid strictly in accordance with the terms of the Second Amended and Restated Credit Agreement and each other Loan Document under which they arise, regardless of any law, regulation or order now or hereafter in effect in any jurisdiction affecting any of such terms or the rights of any Lender or any holder of any Note with respect thereto.  The liability of the Guarantor under this Guaranty shall be absolute, unconditional and irrevocable irrespective of:  (1) any lack of validity, legality or enforceability of the Second Amended and Restated Credit Agreement, any Note or any other Loan Document; (2) the failure of any Lender or any holder of any Note (a) to assert any claim or demand or to enforce any right or remedy against the Borrower, any other Obligor or any other Person (including any other guarantor) under the provisions of the Second Amended and Restated Credit Agreement, any Note, any other Loan Document or otherwise, or (b) to exercise any right or remedy against any other guarantor of, or collateral securing, any Obligations of the Borrower or any other Obligor; (3) any change in the time, manner or place of payment of, or in any other term of, all or any of the Obligations of the Borrower or any other Obligor, or any other extension, compromise or renewal of any Obligations of the Borrower or any other Obligor; (4) any reduction, limitation, impairment or termination of any Obligations of the Borrower or any other Obligor for any

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reason, including any claim of waiver, release, surrender, alteration or compromise, and shall not be subject to (and the Guarantor hereby waives any right to or claim of) any defense or setoff, counterclaim, recoupment or termination whatsoever by reason of the invalidity, illegality, nongenuineness, irregularity, compromise, unenforceability of, or any other event or occurrence affecting, any Obligations of the Borrower, any other Obligor or otherwise; (5) any amendment to, rescission, waiver, or other modification of, or any consent to departure from, any of the terms of the Second Amended and Restated Credit Agreement, any Note or any other Loan Document; (6) any addition, exchange, release, surrender or non-perfection of any collateral, or any amendment to or waiver or release or addition of, or consent to departure from, any other guaranty, held by any Lender or any holder of any Note securing any of the Obligations of the Borrower or any other Obligor; (7) the insolvency or bankruptcy of, or similar event affecting, the Borrower or any other Obligor; or (8) any other circumstance which might otherwise constitute a defense available to, or a legal or equitable discharge of, the Borrower, any other Obligor, any surety or any guarantor. Guarantor waives all rights and defenses which may arise with respect to any of the foregoing, and Guarantor waives any right to revoke this Guaranty with respect to future indebtedness. Guarantor waives all rights or defenses under (1) Section 34.01 et seq. of the Texas Business and Commerce Code, as amended, (2) Section 17.001 of the Texas Civil Practice and Remedies Code, as amended, (3) Rule 31 of the Texas Rules of Civil Procedure, as amended, or (4) common law, in equity, under contract, by statute, or otherwise.

SECTION 2.4Reinstatement. The Guarantor agrees that this Guaranty shall continue to be effective or be reinstated, as the case may be, if at any time any payment (in whole or in part) of any of the Obligations is rescinded or must otherwise be restored by any Lender or any holder of any Note, upon the insolvency, bankruptcy or reorganization of the Borrower, any other Obligor or otherwise, all as though such payment had not been made.

SECTION 2.5Waiver, etc.   The Guarantor hereby waives promptness, diligence, notice of acceptance and any other notice with respect to any of the Obligations of the Borrower or any other Obligor and this Guaranty and any requirement that the Administrative Agent, any other Lender or any holder of any Note protect, secure, perfect or insure any security interest or Lien, or any property subject thereto, or exhaust any right or take any action against the Borrower, any other Obligor or any other Person (including any other guarantor) or entity or any collateral securing the Obligations of the Borrower or any other Obligor, as the case may be.

SECTION 2.6Waiver of Subrogation. Until the Obligations are paid in full, all Commitments have terminated and all Lender Hedging Agreements have terminated, the Guarantor shall not enforce or exercise any claim or other rights which it may now or hereafter acquire against the Borrower or any other Obligor that arise from the existence, payment, performance or enforcement of the Guarantor’s obligations under this Guaranty or any other Loan Document, including any right of subrogation, reimbursement, exoneration, or indemnification, any right to participate in any claim or remedy of the Lenders against the Borrower or any other Obligor or any collateral which the Administrative Agent now has or hereafter acquires, whether or not such claim, remedy or right arises in equity, or under contract, statute or common law, including the right to take or receive from the Borrower or any other Obligor, directly or indirectly, in cash or other property or by set-off or in any manner, payment or security on account of such claim or other rights. If any amount shall be paid to the Guarantor

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in violation of the preceding sentence, such amount shall be deemed to have been paid to the Guarantor for the benefit of, and held in trust for, the Lenders, and shall forthwith be paid to the Lenders to be credited and applied upon the Obligations, whether matured or unmatured. The Guarantor acknowledges that it will receive direct and indirect benefits from the financing arrangements contemplated by the Second Amended and Restated Credit Agreement and that the waiver set forth in this Section is knowingly made in contemplation of such benefits.

SECTION 2.7Payments Free and Clear of Taxes, etc.   The Guarantor hereby agrees that:

(a)All payments by the Guarantor hereunder shall be made in accordance with Section 3.01 of the Second Amended and Restated Credit Agreement free and clear of and without deduction for any present or future income, excise, stamp or franchise taxes and other taxes, fees, duties, withholdings or other charges of any nature whatsoever imposed by any taxing authority, but excluding franchise taxes and taxes imposed on or measured by any Lender’s net income or receipts (such non-excluded items being called “Taxes”). In the event that any withholding or deduction from any payment to be made by the Guarantor hereunder is required in respect of any Taxes pursuant to any applicable law, rule or regulation, then the Guarantor will (i) pay directly to the relevant authority the full amount required to be so withheld or deducted; (ii) promptly forward to such Lender an official receipt or other documentation satisfactory to such Lender evidencing such payment to such authority; and (iii) pay to such Lender such additional amount or amounts as is necessary to ensure that the net amount actually received by such Lender will equal the full amount such Lender would have received had no such withholding or deduction been required. Moreover, if any Taxes are directly asserted against any Lender with respect to any payment received by such Lender hereunder, such Lender may pay such Taxes and the Guarantor will promptly pay such additional amounts (including, if incurred as a result of Guarantor’s or the Borrower’s action, omission or delay, any penalties, interest or expenses) as is necessary in order that the net amount received by such Lender after the payment of such Taxes (including any Taxes on such additional amount) shall equal the amount such Lender would have received had such Taxes not been asserted.

(b)If the Guarantor fails to pay any Taxes when due to the appropriate taxing authority or fails to remit to any Lender the required receipts or other required documentary evidence, the Guarantor shall indemnify such Lender for any incremental Taxes, interest or penalties that may become payable by such Lender as a result of any such failure.

(c)Without prejudice to the survival of any other agreement of the Guarantor hereunder, the agreements and obligations of the Guarantor contained in this Section 2.7 shall survive the payment in full of the principal of and interest on the Loans.

SECTION 2.8Subordination. Guarantor hereby subordinates and makes inferior to the Obligations any and all indebtedness now or at any time hereafter owed by the Borrower or other Obligor to the Guarantor. Guarantor agrees that after the occurrence of any Default or Event of Default under the Second Amended and Restated Credit Agreement, it will not permit the Borrower to repay such indebtedness or any part thereof and it will not accept payment from the Borrower of such indebtedness or any part thereof without the prior written consent of the

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Required Lenders as defined in the Second Amended and Restated Credit Agreement. If Guarantor receives any such payment without the prior required written consent, the amount so paid shall be held in trust for the benefit of the Lenders, shall be segregated from the other funds of such Guarantor, and shall forthwith be paid over to the Administrative Agent to be held by the Administrative Agent as collateral for, or then or at any time thereafter applied in whole or in part by the Administrative Agent against, all or any portions of the Obligations, whether matured or unmatured, in such order as the Administrative Agent shall elect.

ARTICLE III

MISCELLANEOUS PROVISIONS

SECTION 3.1Loan Document. This Guaranty is a Loan Document executed pursuant to the Second Amended and Restated Credit Agreement and shall (unless otherwise expressly indicated herein) be construed, administered and applied in accordance with the terms and provisions thereof.

SECTION 3.2Releases. At such time as the Loans shall have been paid in full, the Commitments have been terminated, and, subject to Section 10.01(e) of the Second Amended and Restated Credit Agreement, no Lender Hedging Agreements are outstanding, the Administrative Agent shall, at the request and expense of the Guarantor following such termination, promptly execute and deliver to the Guarantor such documents and instruments as the Guarantor shall reasonably request to evidence termination and release of this Guaranty.

SECTION 3.3Administrative Agent and Lenders; Successors and Assigns.

(a)The Administrative Agent is Administrative Agent for each Lender under the Second Amended and Restated Credit Agreement. All rights granted to Administrative Agent under or in connection with this Guaranty are for each Lender’s ratable benefit. The Administrative Agent may, without the joinder of any Lender, exercise any rights in Administrative Agent’s or Lenders’ favor under or in connection with this Guaranty. The Administrative Agent’s and each Lender’s rights and obligations vis-a-vis each other may be subject to one or more separate agreements between those parties. However, the Guarantor is not required to inquire about any such agreement and is not subject to any terms of it unless the Guarantor specifically enters into such agreement. Therefore, neither Guarantor nor its successors or assigns is entitled to any benefits or provisions of any such separate agreement nor is it entitled to rely upon or raise as a defense any party’s failure or refusal to comply with the provisions of any such agreement.

(b)This Guaranty benefits the Administrative Agent, the Lenders, and their respective successors and assigns and binds Guarantor and its successors and assigns. Upon appointment of any successor Administrative Agent under the Second Amended and Restated Credit Agreement, all of the rights of Administrative Agent under this Guaranty automatically vests in that new Administrative Agent as successor Administrative Agent on behalf of Lenders without any further act, deed, conveyance, or other formality other than that appointment. The rights of the Administrative Agent and the Lenders under this Guaranty may be transferred with

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any assignment of the obligations hereby guaranteed pursuant to and in accordance with the terms of the Second Amended and Restated Credit Agreement. The Second Amended and Restated Credit Agreement contains provisions governing assignments of the obligations guaranteed under this Guaranty.

SECTION 3.4Amendments, etc.   No amendment to or waiver of any provision of this Guaranty, nor consent to any departure by the Guarantor herefrom, shall in any event be effective unless the same shall be in writing and signed by or on behalf of the party against whom it is sought to be enforced and is in conformity with the requirements of Section 10.01 of the Second Amended and Restated Credit Agreement.  Each such waiver or consent shall be effective only in the specific instance and for the specific purpose for which given.

SECTION 3.5Addresses for Notices to the Guarantor. All notices and other communications hereunder to the Guarantor shall be in writing and mailed or delivered to it, addressed to it at the address set forth below or at such other address as shall be designated by the Guarantor in a written notice to the Administrative Agent at the address specified in the Second Amended and Restated Credit Agreement complying as to delivery with the terms of this Section. All such notices and other communications shall, when mailed, be effective when deposited in the mail, addressed as aforesaid. Address for notices:

155 Inverness Drive West, Suite 200

Englewood, CO 80112-5000

Attn: Contract Administrator

Facsimile: (303) 290-8769

Telephone: (303) 290-8700

SECTION 3.6No Waiver; Remedies. In addition to, and not in limitation of, Section 2.3 and Section 2.5, no failure on the part of any Lender or any holder of a Note to exercise, and no delay in exercising, any right hereunder shall operate as a waiver thereof, nor shall any single or partial exercise of any right hereunder preclude any other or further exercise thereof or the exercise of any other right.  The remedies herein provided are cumulative and not exclusive of any remedies provided by law.

SECTION 3.7Section Captions. Section captions used in this Guaranty are for convenience of reference only, and shall not affect the construction of this Guaranty.

SECTION 3.8Setoff. In addition to, and not in limitation of, any rights of any Lender or any bolder of a Note under applicable law, upon the occurrence of an Event of Default under or as defined in the Second Amended and Restated Credit Agreement, each Lender and each such holder shall be entitled to exercise (for the benefit of all Lenders pursuant to Section 10.09 of the Second Amended and Restated Credit Agreement) any right of offset or banker’s lien against each and every account and other property or interest that the Guarantor may now or hereafter have with, or which is now or hereafter in the possession of, any such Lender, to the extent of the full amount of the Obligations.

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SECTION 3.9Severability. Wherever possible each provision of this Guaranty shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Guaranty shall be prohibited by or invalid under such law, such provision shall be ineffective to the extent of such prohibition or invalidity, without invalidating the remainder of such provision or the remaining provisions of this Guaranty.

SECTION 3.10Continuation of Liens on Collateral.   The Guarantor has granted a Lien on Collateral to secure its guarantee of obligations of the Borrower under the Original Amended Credit Agreement, as amended by the First Amended and Restated Credit Agreement, and to secure the Borrower’s obligtions under the Original Amended Credit Agreement, as amended by the First Amended and Restated Credit Agreement.  Guarantor hereby agrees, acknowledges and confirms that all such Liens are renewed and carried forward, not released, diminished or extinguished, and secure Guarantor’s guarantee under this Guaranty of the Obligations of Borrower as defined in the Second Amended and Restated Credit Agreement.

SECTION 3.11Governing Law. THIS GUARANTY SHALL BE DEEMED TO BE A CONTRACT UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF TEXAS AND APPLICABLE FEDERAL LAW. THIS GUARANTY AND THE OTHER LOAN DOCUMENTS CONSTITUTE THE ENTIRE UNDERSTANDING AMONG THE PARTIES HERETO WITH RESPECT TO THE SUBJECT MATTER HEREOF AND SUPERSEDE ANY PRIOR AGREEMENTS, WRITTEN OR ORAL, WITH RESPECT THERETO.

SECTION 3.12Forum Selection and Consent to Jurisdiction. ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS GUARANTY, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE LENDERS OR THE GUARANTOR MAY BE BROUGHT AND MAINTAINED IN THE COURTS OF THE STATE OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF TEXAS. THE GUARANTOR HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE NONEXCLUSIVE JURISDICTION OF THE COURTS OF THE STATE OF TEXAS AND OF THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED THEREBY IN CONNECTION WITH SUCH LITIGATION. THE GUARANTOR FURTHER IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS BY PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF TEXAS. THE GUARANTOR HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO TIM LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT FORUM.

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SECTION 3.13Waiver of Jury Trial. THE GUARANTOR HEREBY KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVES ANY RIGHTS IT MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS GUARANTY, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE LENDERS OR THE GUARANTOR. THE GUARANTOR ACKNOWLEDGES AND AGREES THAT IT HAS RECEIVED FULL AND SUFFICIENT CONSIDERATION FOR THIS PROVISION AND THAT THIS PROVISION IS A MATERIAL INDUCEMENT FOR THE LENDERS ENTERING INTO THE SECOND AMENDED AND RESTATED CREDIT AGREEMENT.

SECTION 3.14Entire Agreement. THIS GUARANTY AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be duly executed and delivered by an officer duly authorized as of the date first above written.

MARKWEST ENERGY PARTNERS, L.P.,
a Delaware master limited partnership
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and
	Treasurer

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Exhibit E-2

AMENDED AND RESTATED GUARANTY

(Subsidiary)

Originally dated as of May 24, 2002 (with respect to certain Subsidiaries)

and

Originally dated as of March 28, 2003 (with respect to certain Subsidiaries)

and

Originally dated as of December 1, 2003 (with respect to certain Subsidiaries)

and

Originally dated as of July 1, 2004 (with respect to a certain Subsidiary)

and

as amended and restated as of July 30, 2004

THIS AMENDED AND RESTATED GUARANTY (this “Guaranty”), dated as of July      , 2004, is made by each of the undersigned (individually, a “Guarantor” and collectively, the “Guarantors”), in favor of ROYAL BANK OF CANADA, as administrative agent for the Lenders (as defined below).

WITNESSETH:

WHEREAS, MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), MarkWest Energy Partners, L.P., a Delaware limited partnership (the “MLP”), Bank of America, N.A., individually and as initial administrative agent (“Bank of America”), Fortis Capital Corp. (“Fortis”), Wells Fargo Bank, N.A. (“Wells Fargo”), U.S. Bank, National Association (“US Bank”), Bank of Oklahoma, N.A. (“Bank of Oklahoma”) and Royal Bank of Canada (“Royal Bank”; Bank of America, Fortis, Wells Fargo, US Bank, Bank of Oklahoma and Royal Bank collectively called the “Original Lenders”) entered into a Credit Agreement originally dated May 20, 2002 providing for an aggregate credit facility of $60,000,000 (the “Original Credit Agreement”); and

WHEREAS, as a condition precedent to the Original Lenders making advances under the Original Credit Agreement, the MLP entered into a Guaranty dated May 24, 2002 in favor of the Original Lenders guaranteeing payment of the indebtedness of the Borrower under the Original Credit Agreement; and

WHEREAS, also as a condition precedent to the Original Lenders making advances under the Original Credit Agreement, the then existing subsidiaries of the Borrower, namely,

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Basin Pipeline L.L.C., a Michigan limited liability company (“Basin”), MarkWest Energy Appalachia, L.L.C., a Delaware limited liability company (“Appalachia”), and West Shore Processing Company, L.L.C., a Michigan limited liability company (“West Shore”) each executed a Guaranty, each dated May 24, 2002, in favor of the Original Lenders guaranteeing payment of the indebtedness of the Borrower under the Original Credit Agreement; and

WHEREAS, the Original Credit Agreement was amended by a First Amendment to Credit dated March 28, 2003 among the Borrower, the MLP and the Original Lenders (the “First Amendment”) and pursuant to the First Amendment (A) Royal Bank of Canada (“Royal Bank”) succeeded Bank of America as administrative agent (the “Administrative Agent”) under the Original Credit Agreement (the Original Credit Agreement, as amended by the First Amendment herein called the “Original Amended Credit Agreement”) and (B) the aggregate credit facility was increased to $75,000,000; and

WHEREAS, as a condition precedent to effectiveness of the First Amendment, the following newly created subsidiaries of the Borrower, namely, MarkWest Blackhawk, L.P., a Texas limited partnership (“Blackhawk”), MarkWest Pinnacle, L.P., a Texas limited partnership (“Pinnacle”), MarkWest PNG Utility, L.P., a Texas limited partnership (“Utility”), MarkWest Texas PNG Utility, L.P., a Texas limited partnership (“PNG Utility”), MarkWest Texas GP, L.L.C., a Texas limited liability company (“Texas GP”), and MW Texas Limited, L.L.C., a Texas limited liability company (“Texas Limited”) each executed a Guaranty, each dated March 28, 2003, in favor of the Original Lenders guaranteeing payment of the indebtedness of the Borrower under the Original Amended Credit Agreement; and

WHEREAS, the Original Amended Credit Agreement was amended and restated in its entirety by an Amended and Restated Credit Agreement dated December 1, 2003 among Borrower, the MLP, Royal Bank, as administrative agent, Bank One, NA (“Bank One”), as documentation agent, and Fortis, as syndication agent, providing for an aggregate credit facility of $140,000,000 (as amended, the “First Amended and Restated Credit Agreement”); and

WHEREAS, as a condition precedent to effectiveness of the First Amended and Restated Credit Agreement, the following newly created subsidiaries of the Borrower, namely, MarkWest Power Tex, L.P., a Texas limited partnership (“Power Tex”), MarkWest Western Oklahoma Gas Company, L.C.C., an Oklahoma limited liability company (“Western Oklahoma”) and MarkWest Michigan Pipeline Company, L.L.C., a Michigan limited liability company (“Michigan”) each executed a Guaranty, each dated December 1, 2003, guaranteeing payment of the indebtedness of the Borrower under the First Amended and Restated Credit Agreement; and

WHEREAS, Borrower formed a new subsidiary to acquire certain pipeline and gathering assets in Texas and pursuant to Section 6.15 of the First Amended and Restated Credit Agreement, this new subsidiary, MarkWest New Mexico, L.P., a Texas limited partnership

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(“New Mexico”), executed a Guaranty dated July 1, 2004  guaranteeing payment of the indebtedness of the Borrower under the First Amended and Restated Credit Agreement; and

WHEREAS, Borrower has requested an increase in the number and amount of the credit facilities under the First Amended and Restated Credit Agreement and Royal Bank and certain other lenders now or hereafter a party thereto (collectively, the “Lenders”) are willing to increase the number and amount of the credit facilities under the First Amended and Restated Credit Agreement and will do so by amending and restating the First Amended and Restated Credit Agreement in its entirety of even date herewith pursuant to an Amended and Restated Credit Agreement (as the same may hereafter be amended, supplemented and restated, the “Second Amended and Restated Credit Agreement”); and

WHEREAS, the Guarantors are wholly owned subsidiaries of the Borrower and wish to amend and restate their respective guaranties to evidence that they continue to guarantee payment of the Borrower’s indebtedness under the Second Amended and Restated Credit Agreement;

WHEREAS, the Guarantors have duly authorized the execution, delivery and performance of this Guaranty;

WHEREAS, it is in the best interests of the Guarantors to execute this Guaranty inasmuch as the Guarantors will derive substantial direct and indirect benefits from the extensions of credit made from time to time to or for the account of the Borrower;

NOW THEREFORE, for good and valuable consideration the receipt of which is hereby acknowledged, and in order to induce the Lenders to make Loans to the Borrower pursuant to the Second Amended and Restated Credit Agreement by fulfilling the requirements of the Second Amended and Restated Credit Agreement, the Guarantors agree to amend and restate their guaranties, for the benefit of each Lender, as follows :

ARTICLE I

DEFINITIONS

SECTION 1.1Certain Terms. The following capitalized terms when used in this Guaranty, including its preamble and recitals, shall have the following meanings (such definitions to be equally applicable to the singular and plural forms thereof):

“Administrative Agent” is defined in the fourth recital.

“Borrower” is defined in the first recital.

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“Commitments” means each Commitment as defined in the Second Amended and Restated Credit Agreement.

“Guarantor” is defined in the preamble and means individually each of Basin, Appalachia, West Shore, Blackhawk, Pinnacle, Utility, PNG Utility,  Texas GP, Texas Limited, Power Tex, Western Oklahoma, Michigan and New Mexico and collectively “Guarantors” means all of the foregoing.

“Guaranty” is defined in the preamble.

“Lenders” is defined in the first recital.

“Loans” means each Loan as defined in the Second Amended and Restated Credit Agreement.

“Loan Documents” means the Loan Documents as defined in the Second Amended and Restated Credit Agreement.

“Note” means each Note as defined in the Second Amended and Restated Credit Agreement.

“Obligations” means the Obligations as defined in the Second Amended and Restated Credit Agreement.

“Obligor” means the Borrower or any other Person (other than the Administrative Agent or any Lender) obligated under any Loan Document.

“Required Lenders” means the Required Lenders as defined in the Second Amended and Restated Credit Agreement.

“Subsidiary Guarantors” means Subsidiaries of Borrower that have guaranteed all or any part of the Obligations.

“Taxes” is defined in clause (a) of Section 2. 7.

“U.C.C.” means the Uniform Commercial Code as in effect in the State of Texas.

SECTION 1.2Second Amended and Restated Credit Agreement Definitions. Unless otherwise defined herein or the context otherwise requires, capitalized terms used in this Guaranty, including its preamble and recitals, have the meanings provided in the Second Amended and Restated Credit Agreement,

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SECTION 1.3U.C.C. Definitions. Unless otherwise defined herein or the context otherwise requires, terms for which meanings are provided in the U.C.C. are used in this Guaranty, including its preamble and recitals, with such meanings.

ARTICLE II

GUARANTY PROVISIONS

SECTION 2.1Guaranty. Each Guarantor hereby absolutely, unconditionally, and irrevocably (1) guarantees the full and punctual payment when due, whether at stated maturity, by required prepayment, declaration, acceleration, demand or otherwise, of all Obligations of the Borrower and each other Obligor now or hereafter existing under each of the Second Amended and Restated Credit Agreement, the Notes and each other Loan Document to which the Borrower or such other Obligor is or may become a party, whether for principal, interest, fees, expenses or otherwise (including all such amounts which would become due but for the operation of the automatic stay under Section 362(a) of the United States Bankruptcy Code, 11 U.S.C. §362(a), and the operation of Sections 502(b) and 506(b) of the United States Bankruptcy Code, 11 U.S.C. §502(b) and §506(b)), and (2) indemnifies and holds harmless each Lender and each holder of a Note for any and all costs and expenses (including reasonable attorney’s fees and expenses) incurred by such Lender or such holder, as the case may be, in enforcing any rights under this Guaranty; provided however, that each Guarantor shall be liable under this Guaranty for the maximum amount of such liability that can be hereby incurred without rendering this Guaranty, as it relates to such Guarantor, voidable under applicable law relating to fraudulent conveyance or fraudulent transfer, and not for any greater amount. This Guaranty constitutes a guaranty of payment when due and not of collection, and each Guarantor specifically agrees that it shall not be necessary or required that any Lender or any holder of any Note exercise any right, assert any claim or demand or enforce any remedy whatsoever against the Borrower or any other Obligor (or any other Person) before or as a condition to the obligations of such Guarantor hereunder.

SECTION 2.2Acceleration of Guaranty. Each Guarantor agrees that, in the event of the occurrence of any event of the type described in Section 8.01(f) or Section 8.01(g) of the Second Amended and Restated Credit Agreement, with respect to the Borrower, any other Obligor or any other Guarantor, and if such event shall occur at a time when any of the Obligations may not then be due and payable, such Guarantor will pay to the Lenders forthwith the full amount which would be payable hereunder by such Guarantor if all such Obligations were then due and payable.

SECTION 2.3Guaranty Absolute, etc.  This Guaranty shall in all respects be a continuing, absolute, unconditional and irrevocable guaranty of payment, and shall remain in full force and effect until all Obligations of the Borrower and each other Obligor have been paid in

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full, all obligations of the Guarantors hereunder shall have been paid in full, all Commitments shall have terminated and, except as provided in Section 10.01(e) of the Second Amended and Restated Credit Agreement, all Lender Hedging Agreements have terminated. No Guarantor may rescind or revoke its obligations hereunder. Each Guarantor guarantees that the Obligations of the Borrower and each other Obligor will be paid strictly in accordance with the terms of the Second Amended and Restated Credit Agreement and each other Loan Document under which they arise, regardless of any law, regulation or order now or hereafter in effect in any jurisdiction affecting any of such terms or the rights of any Lender or any holder of any Note with respect thereto.  The liability of each Guarantor under this Guaranty shall be absolute, unconditional and irrevocable irrespective of: (1) any lack of validity, legality or enforceability of the Second Amended and Restated Credit Agreement, any Note or any other Loan Document; (2) the failure of any Lender or any holder of any Note (a) to assert any claim or demand or to enforce any right or remedy against the Borrower, any other Obligor or any other Person (including any other guarantor) under the provisions of the Second Amended and Restated Credit Agreement, any Note, any other Loan Document or otherwise, or (b) to exercise any right or remedy against any other guarantor of, or collateral securing, any Obligations of the Borrower or any other Obligor; (3) any change in the time, manner or place of payment of, or in any other term of, all or any of the Obligations of the Borrower or any other Obligor, or any other extension, compromise or renewal of any Obligations of the Borrower or any other Obligor; (4) any reduction, limitation, impairment or termination of any Obligations of the Borrower or any other Obligor for any reason, including any claim of waiver, release, surrender, alteration or compromise, and shall not be subject to (and each Guarantor hereby waives any right to or claim of) any defense or setoff, counterclaim, recoupment or termination whatsoever by reason of the invalidity, illegality, nongenuineness, irregularity, compromise, unenforceability of, or any other event or occurrence affecting, any Obligations of the Borrower, any other Obligor or otherwise; (5) any amendment to, rescission, waiver, or other modification of, or any consent to departure from, any of the terms of the Second Amended and Restated Credit Agreement, any Note or any other Loan Document; (6) any addition, exchange, release, surrender or non-perfection of any collateral, or any amendment to or waiver or release or addition of, or consent to departure from, any other guaranty, held by any Lender or any holder of any Note securing any of the Obligations of the Borrower or any other Obligor; (7) the insolvency or bankruptcy of, or similar event affecting, the Borrower or any other Obligor; or (8) any other circumstance which might otherwise constitute a defense available to, or a legal or equitable discharge of, the Borrower, any other Obligor, any surety or any guarantor. Each Guarantor waives all rights and defenses which may arise with respect to any of the foregoing, and each Guarantor waives any right to revoke this Guaranty with respect to future indebtedness. Each Guarantor waives all rights or defenses under (1) Section 34.01 et seq. of the Texas Business and Commerce Code, as amended, (2) Section 17.001 of the Texas Civil Practice and Remedies Code, as amended, (3) Rule 31 of the Texas Rules of Civil Procedure, as amended, or (4) common law, in equity, under contract, by statute, or otherwise.

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SECTION 2.4Reinstatement. Each Guarantor agrees that this Guaranty shall continue to be effective or be reinstated, as the case may be, if at any time any payment (in whole or in part) of any of the Obligations is rescinded or must otherwise be restored by any Lender or any holder of any Note, upon the insolvency, bankruptcy or reorganization of the Borrower, any other Obligor or otherwise, all as though such payment had not been made.

SECTION 2.5Waiver, etc.   The Guarantors hereby waive promptness, diligence, notice of acceptance and any other notice with respect to any of the Obligations of the Borrower or any other Obligor and this Guaranty and any requirement that the Administrative Agent, any other Lender or any holder of any Note protect, secure, perfect or insure any security interest or Lien, or any property subject thereto, or exhaust any right or take any action against the Borrower, any other Obligor or any other Person (including any other guarantor) or entity or any collateral securing the Obligations of the Borrower or any other Obligor, as the case may be.

SECTION 2.6Waiver of Subrogation. Until the Obligations are paid in full, all Commitments have terminated and all Lender Hedging Agreements have terminated, the Guarantors shall not enforce or exercise any claim or other rights which they may now or hereafter acquire against the Borrower or any other Obligor that arise from the existence, payment, performance or enforcement of any Guarantor’s obligations under this Guaranty or any other Loan Document, including any right of subrogation, reimbursement, exoneration, or indemnification, any right to participate in any claim or remedy of the Lenders against the Borrower or any other Obligor or any collateral which the Administrative Agent now has or hereafter acquires, whether or not such claim, remedy or right arises in equity, or under contract, statute or common law, including the right to take or receive from the Borrower or any other Obligor, directly or indirectly, in cash or other property or by set-off or in any manner, payment or security on account of such claim or other rights. If any amount shall be paid to any Guarantor in violation of the preceding sentence, such amount shall be deemed to have been paid to such Guarantor for the benefit of, and held in trust for, the Lenders, and shall forthwith be paid to the Lenders by the Guarantor receiving such payment to be credited and applied upon the Obligations, whether matured or unmatured. Each of Basin, Appalachia and West Shore acknowledges that it did receive direct and indirect benefits from the Original Credit Agreement, each of Blackhawk, Pinnacle, Utility, PNG Utility, Texas GP and Texas Limited acknowledge that it did receive direct and indirect benefits from the Original Amended Credit Agreement, each of Power Tex, Western Oklahoma, Michigan and New Mexico acknowledge that it did receive direct and indirect benefits from the First Amended and Restated Credit Agreement,  and each Guarantor acknowledges that it  will receive direct and indirect benefits from the financing arrangements contemplated by the Second Amended and Restated Credit Agreement and that the waiver set forth in this Section is knowingly made in contemplation of such benefits.

SECTION 2.7Payments Free and Clear of Taxes, etc.   Each Guarantor hereby agrees that:

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(a)All payments by such Guarantor hereunder shall be made in accordance with Section 3.01 of the Second Amended and Restated Credit Agreement free and clear of and without deduction for any present or future income, excise, stamp or franchise taxes and other taxes, fees, duties, withholdings or other charges of any nature whatsoever imposed by any taxing authority, but excluding franchise taxes and taxes imposed on or measured by any Lender’s net income or receipts (such non-excluded items being called “Taxes”).  In the event that any withholding or deduction from any payment to be made by a Guarantor hereunder is required in respect of any Taxes pursuant to any applicable law, rule or regulation, then such Guarantor will (i) pay directly to the relevant authority the full amount required to be so withheld or deducted; (ii) promptly forward to such Lender an official receipt or other documentation satisfactory to such Lender evidencing such payment to such authority; and (iii) pay to such Lender such additional amount or amounts as is necessary to ensure that the net amount actually received by such Lender will equal the full amount such Lender would have received had no such withholding or deduction been required. Moreover, if any Taxes are directly asserted against any Lender with respect to any payment received by such Lender hereunder, such Lender may pay such Taxes and such Guarantor will promptly pay such additional amounts (including, if incurred as a result of such Guarantor’s or the Borrower’s action, omission or delay, any penalties, interest or expenses) as is necessary in order that the net amount received by such Lender after the payment of such Taxes (including any Taxes on such additional amount) shall equal the amount such Lender would have received had such Taxes not been asserted.

(b)If a Guarantor fails to pay any Taxes when due to the appropriate taxing authority or fails to remit to any Lender the required receipts or other required documentary evidence, such Guarantor shall indemnify such Lender for any incremental Taxes, interest or penalties that may become payable by such Lender as a result of any such failure.

(c)Without prejudice to the survival of any other agreement of the Guarantors hereunder, the agreements and obligations of the Guarantors contained in this Section 2.7 shall survive the payment in full of the principal of and interest on the Loans.

SECTION 2.8Contribution Agreement.  Upon full and final payment of the Obligations, each Guarantor and all other Subsidiary Guarantors which have made payments upon all or any part of the Obligations shall be entitled to contribution from all of the other Guarantors and Subsidiary Guarantors, to the end that all such payments upon the Obligations shall be shared among all Guarantors and Subsidiary Guarantors who guaranteed such Obligations in proportion to their respective Net Worths (defined below); provided that the contribution obligations of each of the Guarantors and Subsidiary Guarantors shall be limited to the maximum amount that it can pay at such time without rendering its contribution obligations voidable under applicable law relating to fraudulent conveyances or fraudulent transfers. As used in this subsection, the “Net Worth” of each of the Guarantors and Subsidiary Guarantors means, at any time, the remainder of (i) the fair value of such Guarantor’s assets (other than such right of

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contribution), minus (ii) the fair value of such Guarantor’s liabilities (other than its liabilities under its guaranty of the Obligations).

SECTION 2.9Subordination. Each Guarantor hereby subordinates and makes inferior to the Obligations any and all indebtedness now or at any time hereafter owed by the Borrower or other Obligor to such Guarantor. Each Guarantor agrees that after the occurrence of any Default or Event of Default under the Second Amended and Restated Credit Agreement, it will not permit the Borrower to repay such indebtedness or any part thereof and it will not accept payment from the Borrower of such indebtedness or any part thereof without the prior written consent of the Required Lenders as defined in the Second Amended and Restated Credit Agreement. If a Guarantor receives any such payment without the prior required written consent, the amount so paid shall be held in trust for the benefit of the Lenders, shall be segregated from the other funds of such Guarantor, and shall forthwith be paid over to the Administrative Agent to be held by the Administrative Agent as collateral for, or then or at any time thereafter applied in whole or in part by the Administrative Agent against, all or any portions of the Obligations, whether matured or unmatured, in such order as the Administrative Agent shall elect.

ARTICLE III

REPRESENTATIONS, WARRANTEES AND COVENANTS

SECTION 3.1Representations, Warranties and Covenants. By execution hereof, each Guarantor covenants and agrees that certain representations, warranties, terms, covenants, and conditions set forth in the Second Amended and Restated Credit Agreement and other Loan Documents are applicable to such Guarantor and shall be imposed upon such Guarantor, and such Guarantor reaffirms that each such representation and warranty is true and correct as to it and covenants and agrees to promptly and properly perform, observe, and comply with each such term, covenant, or condition applicable to it. Moreover, each Guarantor acknowledges and agrees that this Guaranty is subject to the offset provisions of the Second Amended and Restated Credit Agreement in favor of the Administrative Agent and the Lenders.

ARTICLE IV

MISCELLANEOUS PROVISIONS

SECTION 4.1Loan Document. This Guaranty is a Loan Document executed pursuant to the Second Amended and Restated Credit Agreement and shall (unless otherwise expressly indicated herein) be construed, administered and applied in accordance with the terms and provisions thereof.

SECTION 4.2Releases. At such time as the Loans shall have been paid in full, the Commitments have been terminated, and, subject to Section 10.01(e) of the Second Amended

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and Restated Credit Agreement, no Lender Hedging Agreements are outstanding, the Administrative Agent shall, at the request and expense of the Guarantors following such termination, promptly execute and deliver to the Guarantors such documents and instruments as the Guarantors shall reasonably request to evidence termination and release of this Guaranty.

SECTION 4.3Administrative Agent and Lenders; Successors and Assigns.

(a)The Administrative Agent is Administrative Agent for each Lender under the Second Amended and Restated Credit Agreement. All rights granted to Administrative Agent under or in connection with this Guaranty are for each Lender’s ratable benefit. The Administrative Agent may, without the joinder of any Lender, exercise any rights in Administrative Agent’s or Lenders’ favor under or in connection with this Guaranty. The Administrative Agent’s and each Lender’s rights and obligations vis-a-vis each other may be subject to one or more separate agreements between those parties. However, the Guarantors are not required to inquire about any such agreement and are not subject to any terms of it unless the Guarantors specifically enter into such agreement. Therefore, neither Guarantors nor any of their successors or assigns are entitled to any benefits or provisions of any such separate agreement nor are they entitled to rely upon or raise as a defense any party’s failure or refusal to comply with the provisions of any such agreement.

(b)This Guaranty benefits the Administrative Agent, the Lenders, and their respective successors and assigns and binds each Guarantor and its successors and assigns. Upon appointment of any successor Administrative Agent under the Second Amended and Restated Credit Agreement, all of the rights of Administrative Agent under this Guaranty automatically vests in that new Administrative Agent as successor Administrative Agent on behalf of Lenders without any further act, deed, conveyance, or other formality other than that appointment. The rights of the Administrative Agent and the Lenders under this Guaranty may be transferred with any assignment of the obligations hereby guaranteed pursuant to and in accordance with the terms of the Second Amended and Restated Credit Agreement. The Second Amended and Restated Credit Agreement contains provisions governing assignments of the obligations guaranteed under this Guaranty.

SECTION 4.4Amendments, etc.   No amendment to or waiver of any provision of this Guaranty, nor consent to any departure by any Guarantor herefrom, shall in any event be effective unless the same shall be in writing and signed by or on behalf of the party against whom it is sought to be enforced and is in conformity with the requirements of Section 10.01 of the Second Amended and Restated Credit Agreement.  Each such waiver or consent shall be effective only in the specific instance and for the specific purpose for which given.

SECTION 4.5Addresses for Notices to the Guarantors. All notices and other communications hereunder to the Guarantors shall be in writing and mailed or delivered to it,

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addressed to it at the address set forth below or at such other address as shall be designated by the Guarantors in a written notice to the Administrative Agent at the address specified in the Second Amended and Restated Credit Agreement complying as to delivery with the terms of this Section. All such notices and other communications shall, when mailed, be effective when deposited in the mail, addressed as aforesaid. Address for notices:

155 Inverness Drive West, Suite 200

Englewood, CO 80112-5000

Attn: Contract Administrator

Facsimile: (303) 290-8769

Telephone: (303) 290-8700

SECTION 4.6No Waiver; Remedies. In addition to, and not in limitation of, Section 2.3 and Section 2.5, no failure on the part of any Lender or any holder of a Note to exercise, and no delay in exercising, any right hereunder shall operate as a waiver thereof, nor shall any single or partial exercise of any right hereunder preclude any other or further exercise thereof or the exercise of any other right.  The remedies herein provided are cumulative and not exclusive of any remedies provided by law.

SECTION 4.7Section Captions. Section captions used in this Guaranty are for convenience of reference only, and shall not affect the construction of this Guaranty.

SECTION 4.8Setoff. In addition to, and not in limitation of, any rights of any Lender or any bolder of a Note under applicable law, upon the occurrence of an Event of Default under or as defined in the Second Amended and Restated Credit Agreement, each Lender and each such holder shall be entitled to exercise (for the benefit of all Lenders pursuant to Section 10.09 of the Second Amended and Restated Credit Agreement) any right of offset or banker’s lien against each and every account and other property or interest that a Guarantor may now or hereafter have with, or which is now or hereafter in the possession of, any such Lender, to the extent of the full amount of the Obligations.

SECTION 4.9Severability. Wherever possible each provision of this Guaranty shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Guaranty shall be prohibited by or invalid under such law, such provision shall be ineffective to the extent of such prohibition or invalidity, without invalidating the remainder of such provision or the remaining provisions of this Guaranty.

SECTION 4.10Continuation of Liens on Collateral.   Each Guarantor that has granted a Lien on Collateral to secure its guarantee of obligations of the Borrower under the

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Original Amended Credit Agreement or First Amended and Restated Credit Agreement, as the case may be, or to secure the Borrower’s obligtions under the Original Amended Credit Agreement or First Amended and Restated Credit Agreement, as the case may be, hereby agrees, acknowledges and confirms that all such Liens are renewed and carried forward, not released, diminished or extinguished, and secure such Guarantor’s guarantee under this Guaranty of the Obligations of Borrower as defined in the Second Amended and Restated Credit Agreement.

SECTION 4.11Governing Law.  THIS GUARANTY SHALL BE DEEMED TO BE A CONTRACT UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF TEXAS AND APPLICABLE FEDERAL LAW. THIS GUARANTY AND THE OTHER LOAN DOCUMENTS CONSTITUTE THE ENTIRE UNDERSTANDING AMONG THE PARTIES HERETO WITH RESPECT TO THE SUBJECT MATTER HEREOF AND SUPERSEDE ANY PRIOR AGREEMENTS, WRITTEN OR ORAL, WITH RESPECT THERETO.

SECTION 4.12Forum Selection and Consent to Jurisdiction. ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS GUARANTY, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE LENDERS OR THE GUARANTORS MAY BE BROUGHT AND MAINTAINED IN THE COURTS OF THE STATE OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF TEXAS. EACH GUARANTOR HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE NONEXCLUSIVE JURISDICTION OF THE COURTS OF THE STATE OF TEXAS AND OF THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED THEREBY IN CONNECTION WITH SUCH LITIGATION. EACH GUARANTOR FURTHER IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS BY PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF TEXAS. EACH GUARANTOR HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO TIM LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT FORUM.

SECTION 4.13Waiver of Jury Trial. EACH GUARANTOR HEREBY KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVES ANY RIGHTS IT MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS

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GUARANTY, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE LENDERS OR THE GUARANTORS. EACH GUARANTOR ACKNOWLEDGES AND AGREES THAT IT HAS RECEIVED FULL AND SUFFICIENT CONSIDERATION FOR THIS PROVISION AND THAT THIS PROVISION IS A MATERIAL INDUCEMENT FOR THE LENDERS ENTERING INTO THE SECOND AMENDED AND RESTATED CREDIT AGREEMENT.

SECTION 4.14Entire Agreement. THIS GUARANTY AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

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IN WITNESS WHEREOF, each Guarantor below has caused this Guaranty to be duly executed and delivered by an officer duly authorized as of the date first above written.

MARKWEST PINNACLE, L.P.,
a Delaware limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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MARKWEST PNG UTILITY, L.P.,
a Texas limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer
MARKWEST TEXAS PNG UTILITY, L.P.,
a Texas limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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MARKWEST BLACKHAWK, L.P.,
a Texas limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer
MARKWEST TEXAS GP, L.L.C.,
a Delaware limited partnership, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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MW TEXAS LIMITED, L.L.C.,
a Delaware limited partnership, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer
MARKWEST WESTERN OKLAHOMA GAS COMPANY, LLC,
an Oklahoma limited liability company, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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MARKWEST MICHIGAN PIPELINE COMPANY, LLC,
a Michigan limited liability company, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer
WEST SHORE PROCESSING COMPANY, LLC,
a Michigan limited liability company, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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BASIN PIPELINE, LLC,
a Michigan limited liability company, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer
MARKWEST ENERGY APPALACHIA, LLC,
a Delaware limited liability company, as a Guarantor
	[CONFIRM THIS IS CORRECT]
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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MARKWEST POWER TEX, L.P.,
a Texas limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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MARKWEST NEW MEXICO, L.P.,
a Texas limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:
	Andrew L. Schroeder
	Vice President and Treasurer

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Exhibit E-3

GUARANTY

(Subsidiary)

THIS GUARANTY (this “Guaranty”), dated as of         , 200   , is made by [Subsidiary], a                     limited liability company (the “Guarantor”), in favor of ROYAL BANK OF CANADA, as administrative agent for the Lenders (as defined below).

WITNESSETH:

WHEREAS, pursuant to that certain Second Amended and Restated Credit Agreement, dated as of July 30, 2004 (as the same may hereafter be amended, supplemented and restated, the “Credit Agreement”), among MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), MarkWest Energy Partners, L.P., a Delaware limited partnership, the various financial institutions that are, or may from time to time become, parties thereto (individually a “Lender” and collectively the “Lenders”) and Royal Bank of Canada (“Royal Bank”), as administrative agent (the “Administrative Agent”), the Lenders have agreed to make Loans for the account of the Borrower;

WHEREAS, the Guarantor is a wholly owned subsidiary of the Borrower;

WHEREAS, the Guarantor is required to deliver this Guaranty pursuant to Section 6.15 of the Credit Agreement;

WHEREAS, the Guarantor has duly authorized the execution, delivery and performance of this Guaranty;

WHEREAS, it is in the best interests of the Guarantor to execute this Guaranty inasmuch as the Guarantor will derive substantial direct and indirect benefits from the extensions of credit made from time to time to or for the account of the Borrower;

NOW THEREFORE, for good and valuable consideration the receipt of which is hereby acknowledged, and in order to induce the Lenders to make Loans to the Borrower pursuant to the Credit Agreement by fulfilling the requirements of the Credit Agreement, the Guarantor agrees, for the benefit of each Lender, as follows:

ARTICLE I

DEFINITIONS

SECTION 1.1Certain Terms. The following capitalized terms when used in this

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Guaranty, including its preamble and recitals, shall have the following meanings (such definitions to be equally applicable to the singular and plural forms thereof):

“Administrative Agent” is defined in the first recital.

“Borrower” is defined in the first recital.

“Commitments” means each Commitment as defined in the Credit Agreement.

“Guarantor” is defined in the preamble.

“Guaranty” is defined in the preamble.

“Lenders” is defined in the first recital.

“Loans” means each Loan as defined in the Credit Agreement.

“Loan Documents” means the Loan Documents as defined in the Credit Agreement.

“Note” means each Note as defined in the Credit Agreement.

“Obligations” means the Obligations as defined in the Credit Agreement.

“Obligor” means the Borrower or any other Person (other than the Administrative Agent or any Lender) obligated under any Loan Document.

“Required Lenders” means the Required Lenders as defined in the Credit Agreement.

“Subsidiary Guarantors” means Subsidiaries of Borrower that have guaranteed all or any part of the Obligations.

“Taxes” is defined in clause (a) of Section 2. 7.

“U.C.C.” means the Uniform Commercial Code as in effect in the State of Texas.

SECTION 1.2Credit Agreement Definitions. Unless otherwise defined herein or the context otherwise requires, capitalized terms used in this Guaranty, including its preamble and recitals, have the meanings provided in the Credit Agreement,

SECTION 1.3U.C.C. Definitions. Unless otherwise defined herein or the context otherwise requires, terms for which meanings are provided in the U.C.C. are used in this Guaranty,

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including its preamble and recitals, with such meanings.

ARTICLE II

GUARANTY PROVISIONS

SECTION 2.1Guaranty. The Guarantor hereby absolutely, unconditionally, and irrevocably (1) guarantees the full and punctual payment when due, whether at stated maturity, by required prepayment, declaration, acceleration, demand or otherwise, of all Obligations of the Borrower and each other Obligor now or hereafter existing under each of the Credit Agreement, the Notes and each other Loan Document to which the Borrower or such other Obligor is or may become a party, whether for principal, interest, fees, expenses or otherwise (including all such amounts which would become due but for the operation of the automatic stay under Section 362(a) of the United States Bankruptcy Code, 11 U.S.C. §362(a), and the operation of Sections 502(b) and 506(b) of the United States Bankruptcy Code, 11 U.S.C. §502(b) and §506(b)), and (2) indemnifies and holds harmless each Lender and each holder of a Note for any and all costs and expenses (including reasonable attorney’s fees and expenses) incurred by such Lender or such holder, as the case may be, in enforcing any rights under this Guaranty; provided however, that the Guarantor shall be liable under this Guaranty for the maximum amount of such liability that can be hereby incurred without rendering this Guaranty, as it relates to the Guarantor, voidable under applicable law relating to fraudulent conveyance or fraudulent transfer, and not for any greater amount. This Guaranty constitutes a guaranty of payment when due and not of collection, and the Guarantor specifically agrees that it shall not be necessary or required that any Lender or any holder of any Note exercise any right, assert any claim or demand or enforce any remedy whatsoever against the Borrower or any other Obligor (or any other Person) before or as a condition to the obligations of the Guarantor hereunder.

SECTION 2.2Acceleration of Guaranty. The Guarantor agrees that, in the event of the occurrence of any event of the type described in Section 8.01(f) or Section 8.01(g) of the Credit Agreement, with respect to the Borrower, any other Obligor or the Guarantor, and if such event shall occur at a time when any of the Obligations may not then be due and payable, the Guarantor will pay to the Lenders forthwith the full amount which would be payable hereunder by the Guarantor if all such Obligations were then due and payable.

SECTION 2.3Guaranty Absolute, etc.  This Guaranty shall in all respects be a continuing, absolute, unconditional and irrevocable guaranty of payment, and shall remain in full force and effect until all Obligations of the Borrower and each other Obligor have been paid in full, all obligations of the Guarantor hereunder shall have been paid in full, all Commitments shall have terminated and, except as provided in Section 10.01(e) of the Credit Agreement, all Lender Hedging Agreements have terminated. Guarantor may not rescind or revoke its obligations

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hereunder. The Guarantor guarantees that the Obligations of the Borrower and each other Obligor will be paid strictly in accordance with the terms of the Credit Agreement and each other Loan Document under which they arise, regardless of any law, regulation or order now or hereafter in effect in any jurisdiction affecting any of such terms or the rights of any Lender or any holder of any Note with respect thereto.  The liability of the Guarantor under this Guaranty shall be absolute, unconditional and irrevocable irrespective of:  (1) any lack of validity, legality or enforceability of the Credit Agreement, any Note or any other Loan Document; (2) the failure of any Lender or any holder of any Note (a) to assert any claim or demand or to enforce any right or remedy against the Borrower, any other Obligor or any other Person (including any other guarantor) under the provisions of the Credit Agreement, any Note, any other Loan Document or otherwise, or (b) to exercise any right or remedy against any other guarantor of, or collateral securing, any Obligations of the Borrower or any other Obligor; (3) any change in the time, manner or place of payment of, or in any other term of, all or any of the Obligations of the Borrower or any other Obligor, or any other extension, compromise or renewal of any Obligations of the Borrower or any other Obligor; (4) any reduction, limitation, impairment or termination of any Obligations of the Borrower or any other Obligor for any reason, including any claim of waiver, release, surrender, alteration or compromise, and shall not be subject to (and the Guarantor hereby waives any right to or claim of) any defense or setoff, counterclaim, recoupment or termination whatsoever by reason of the invalidity, illegality, nongenuineness, irregularity, compromise, unenforceability of, or any other event or occurrence affecting, any Obligations of the Borrower, any other Obligor or otherwise; (5) any amendment to, rescission, waiver, or other modification of, or any consent to departure from, any of the terms of the Credit Agreement, any Note or any other Loan Document; (6) any addition, exchange, release, surrender or non-perfection of any collateral, or any amendment to or waiver or release or addition of, or consent to departure from, any other guaranty, held by any Lender or any holder of any Note securing any of the Obligations of the Borrower or any other Obligor; (7) the insolvency or bankruptcy of, or similar event affecting, the Borrower or any other Obligor; or (8) any other circumstance which might otherwise constitute a defense available to, or a legal or equitable discharge of, the Borrower, any other Obligor, any surety or any guarantor. Guarantor waives all rights and defenses which may arise with respect to any of the foregoing, and Guarantor waives any right to revoke this Guaranty with respect to future indebtedness. Guarantor waives all rights or defenses under (1) Section 34.01 et seq. of the Texas Business and Commerce Code, as amended, (2) Section 17.001 of the Texas Civil Practice and Remedies Code, as amended, (3) Rule 31 of the Texas Rules of Civil Procedure, as amended, or (4) common law, in equity, under contract, by statute, or otherwise.

SECTION 2.4Reinstatement. The Guarantor agrees that this Guaranty shall continue to be effective or be reinstated, as the case may be, if at any time any payment (in whole or in part) of any of the Obligations is rescinded or must otherwise be restored by any Lender or any holder of any Note, upon the insolvency, bankruptcy or reorganization of the Borrower, any other Obligor or otherwise, all as though such payment had not been made.

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SECTION 2.5Waiver, etc.   The Guarantor hereby waives promptness, diligence, notice of acceptance and any other notice with respect to any of the Obligations of the Borrower or any other Obligor and this Guaranty and any requirement that the Administrative Agent, any other Lender or any holder of any Note protect, secure, perfect or insure any security interest or Lien, or any property subject thereto, or exhaust any right or take any action against the Borrower, any other Obligor or any other Person (including any other guarantor) or entity or any collateral securing the Obligations of the Borrower or any other Obligor, as the case may be.

SECTION 2.6Waiver of Subrogation. Until the Obligations are paid in full, all Commitments have terminated and all Lender Hedging Agreements have terminated, the Guarantor shall not enforce or exercise any claim or other rights which it may now or hereafter acquire against the Borrower or any other Obligor that arise from the existence, payment, performance or enforcement of the Guarantor’s obligations under this Guaranty or any other Loan Document, including any right of subrogation, reimbursement, exoneration, or indemnification, any right to participate in any claim or remedy of the Lenders against the Borrower or any other Obligor or any collateral which the Administrative Agent now has or hereafter acquires, whether or not such claim, remedy or right arises in equity, or under contract, statute or common law, including the right to take or receive from the Borrower or any other Obligor, directly or indirectly, in cash or other property or by set-off or in any manner, payment or security on account of such claim or other rights. If any amount shall be paid to the Guarantor in violation of the preceding sentence, such amount shall be deemed to have been paid to the Guarantor for the benefit of, and held in trust for, the Lenders, and shall forthwith be paid to the Lenders to be credited and applied upon the Obligations, whether matured or unmatured. The Guarantor acknowledges that it will receive direct and indirect benefits from the financing arrangements contemplated by the Credit Agreement and that the waiver set forth in this Section is knowingly made in contemplation of such benefits.

SECTION 2.7Payments Free and Clear of Taxes, etc.   The Guarantor hereby agrees that:

(a)All payments by the Guarantor hereunder shall be made in accordance with Section 3.01 of the Credit Agreement free and clear of and without deduction for any present or future income, excise, stamp or franchise taxes and other taxes, fees, duties, withholdings or other charges of any nature whatsoever imposed by any taxing authority, but excluding franchise taxes and taxes imposed on or measured by any Lender’s net income or receipts (such non-excluded items being called “Taxes”). In the event that any withholding or deduction from any payment to be made by the Guarantor hereunder is required in respect of any Taxes pursuant to any applicable law, rule or regulation, then the Guarantor will (i) pay directly to the relevant authority the full amount required to be so withheld or deducted; (ii) promptly forward to such Lender an official receipt or other documentation satisfactory to such Lender evidencing such payment to such authority; and (iii) pay to such Lender such additional amount or amounts as is

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necessary to ensure that the net amount actually received by such Lender will equal the full amount such Lender would have received had no such withholding or deduction been required. Moreover, if any Taxes are directly asserted against any Lender with respect to any payment received by such Lender hereunder, such Lender may pay such Taxes and the Guarantor will promptly pay such additional amounts (including, if incurred as a result of Guarantor’s or the Borrower’s action, omission or delay, any penalties, interest or expenses) as is necessary in order that the net amount received by such Lender after the payment of such Taxes (including any Taxes on such additional amount) shall equal the amount such Lender would have received had such Taxes not been asserted.

(b)If the Guarantor fails to pay any Taxes when due to the appropriate taxing authority or fails to remit to any Lender the required receipts or other required documentary evidence, the Guarantor shall indemnify such Lender for any incremental Taxes, interest or penalties that may become payable by such Lender as a result of any such failure.

(c)Without prejudice to the survival of any other agreement of the Guarantor hereunder, the agreements and obligations of the Guarantor contained in this Section 2.7 shall survive the payment in full of the principal of and interest on the Loans.

SECTION 2.8Contribution Agreement.  Upon full and final payment of the Obligations, Guarantor and all other Subsidiary Guarantors which have made payments upon all or any part of the Obligations shall be entitled to contribution from all of the Subsidiary Guarantors, to the end that all such payments upon the Obligations shall be shared among all Subsidiary Guarantors who Guaranteed such Obligations in proportion to their respective Net Worths (defined below), provided that the contribution obligations of each of the Subsidiary Guarantors shall be limited to the maximum amount that it can pay at such time without rendering its contribution obligations voidable under applicable law relating to fraudulent conveyances or fraudulent transfers. As used in this subsection, the “Net Worth” of each of the Subsidiary Guarantors means, at any time, the remainder of (i) the fair value of such guarantor’s assets (other than such right of contribution), minus (ii) the fair value of such Guarantor’s liabilities (other than its liabilities under its guaranty of the Obligations).

SECTION 2.9Subordination. Guarantor hereby subordinates and makes inferior to the Obligations any and all indebtedness now or at any time hereafter owed by the Borrower or other Obligor to the Guarantor. Guarantor agrees that after the occurrence of any Default or Event of Default under the Credit Agreement, it will not permit the Borrower to repay such indebtedness or any part thereof and it will not accept payment from the Borrower of such indebtedness or any part thereof without the prior written consent of the Required Lenders as defined in the Credit Agreement. If Guarantor receives any such payment without the prior required written consent, the amount so paid shall be held in trust for the benefit of the Lenders, shall be segregated from the other funds of such Guarantor, and shall forthwith be paid over to

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the Administrative Agent to be held by the Administrative Agent as collateral for, or then or at any time thereafter applied in whole or in part by the Administrative Agent against, all or any portions of the Obligations, whether matured or unmatured, in such order as the Administrative Agent shall elect.

ARTICLE III

REPRESENTATIONS, WARRANTEES AND COVENANTS

SECTION 3.1Representations, Warranties and Covenants. By execution hereof, Guarantor covenants and agrees that certain representations, warranties, terms, covenants, and conditions set forth in the Credit Agreement and other Loan Documents are applicable to Guarantor and shall be imposed upon Guarantor, and Guarantor reaffirms that each such representation and warranty is true and correct and covenants and agrees to promptly and properly perform, observe, and comply with each such term, covenant, or condition. Moreover, Guarantor acknowledges and agrees that this Guaranty is subject to the offset provisions of the Credit Agreement in favor of the Administrative Agent and the Lenders.

ARTICLE IV

MISCELLANEOUS PROVISIONS

SECTION 4.1Loan Document. This Guaranty is a Loan Document executed pursuant to the Credit Agreement and shall (unless otherwise expressly indicated herein) be construed, administered and applied in accordance with the terms and provisions thereof.

SECTION 4.2Releases. At such time as the Loans shall have been paid in full, the Commitments have been terminated, and, subject to Section 10.01(e) of the Credit Agreement, no Lender Hedging Agreements are outstanding, the Administrative Agent shall, at the request and expense of the Guarantor following such termination, promptly execute and deliver to the Guarantor such documents and instruments as the Guarantor shall reasonably request to evidence termination and release of this Guaranty.

SECTION 4.3Administrative Agent and Lenders; Successors and Assigns.

(a)The Administrative Agent is Administrative Agent for each Lender under the Credit Agreement. All rights granted to Administrative Agent under or in connection with this Guaranty are for each Lender’s ratable benefit. The Administrative Agent may, without the joinder of any Lender, exercise any rights in Administrative Agent’s or Lenders’ favor under or in connection with this Guaranty. The Administrative Agent’s and each Lender’s rights and obligations vis-a-vis each other may be subject to one or more separate agreements between those parties. However, the Guarantor is not required to inquire about any such agreement and is

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not subject to any terms of it unless the Guarantor specifically enters into such agreement. Therefore, neither Guarantor nor its successors or assigns is entitled to any benefits or provisions of any such separate agreement nor is it entitled to rely upon or raise as a defense any party’s failure or refusal to comply with the provisions of any such agreement.

(b)This Guaranty benefits the Administrative Agent, the Lenders, and their respective successors and assigns and binds Guarantor and its successors and assigns. Upon appointment of any successor Administrative Agent under the Credit Agreement, all of the rights of Administrative Agent under this Guaranty automatically vests in that new Administrative Agent as successor Administrative Agent on behalf of Lenders without any further act, deed, conveyance, or other formality other than that appointment. The rights of the Administrative Agent and the Lenders under this Guaranty may be transferred with any assignment of the obligations hereby guaranteed pursuant to and in accordance with the terms of the Credit Agreement. The Credit Agreement contains provisions governing assignments of the obligations guaranteed under this Guaranty.

SECTION 4.4Amendments, etc.   No amendment to or waiver of any provision of this Guaranty, nor consent to any departure by the Guarantor herefrom, shall in any event be effective unless the same shall be in writing and signed by or on behalf of the party against whom it is sought to be enforced and is in conformity with the requirements of Section 10.01 of the Credit Agreement.  Each such waiver or consent shall be effective only in the specific instance and for the specific purpose for which given.

SECTION 4.5Addresses for Notices to the Guarantor. All notices and other communications hereunder to the Guarantor shall be in writing and mailed or delivered to it, addressed to it at the address set forth below or at such other address as shall be designated by the Guarantor in a written notice to the Administrative Agent at the address specified in the Credit Agreement complying as to delivery with the terms of this Section. All such notices and other communications shall, when mailed, be effective when deposited in the mail, addressed as aforesaid. Address for notices:

155 Inverness Drive West, Suite 200

Englewood, CO 80112-5000

Attn: Contract Administrator

Facsimile: (303) 290-8769

Telephone: (303) 290-8700

SECTION 4.6No Waiver; Remedies. In addition to, and not in limitation of, Section 2.3 and Section 2.5, no failure on the part of any Lender or any holder of a Note to exercise, and no delay in exercising, any right hereunder shall operate as a waiver thereof, nor shall any single

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or partial exercise of any right hereunder preclude any other or further exercise thereof or the exercise of any other right.  The remedies herein provided are cumulative and not exclusive of any remedies provided by law.

SECTION 4.7Section Captions. Section captions used in this Guaranty are for convenience of reference only, and shall not affect the construction of this Guaranty.

SECTION 4.8Setoff. In addition to, and not in limitation of, any rights of any Lender or any bolder of a Note under applicable law, upon the occurrence of an Event of Default under or as defined in the Credit Agreement, each Lender and each such holder shall be entitled to exercise (for the benefit of all Lenders pursuant to Section 10.09 of the Credit Agreement) any right of offset or banker’s lien against each and every account and other property or interest that the Guarantor may now or hereafter have with, or which is now or hereafter in the possession of, any such Lender, to the extent of the full amount of the Obligations.

SECTION 4.9Severability. Wherever possible each provision of this Guaranty shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Guaranty shall be prohibited by or invalid under such law, such provision shall be ineffective to the extent of such prohibition or invalidity, without invalidating the remainder of such provision or the remaining provisions of this Guaranty.

SECTION 4.10Governing Law. THIS GUARANTY SHALL BE DEEMED TO BE A CONTRACT UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF TEXAS AND APPLICABLE FEDERAL LAW. THIS GUARANTY AND THE OTHER LOAN DOCUMENTS CONSTITUTE THE ENTIRE UNDERSTANDING AMONG THE PARTIES HERETO WITH RESPECT TO THE SUBJECT MATTER HEREOF AND SUPERSEDE ANY PRIOR AGREEMENTS, WRITTEN OR ORAL, WITH RESPECT THERETO.

SECTION 4.11Forum Selection and Consent to Jurisdiction. ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS GUARANTY, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE LENDERS OR THE GUARANTOR MAY BE BROUGHT AND MAINTAINED IN THE COURTS OF THE STATE OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF TEXAS. THE GUARANTOR HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE NONEXCLUSIVE JURISDICTION OF THE COURTS OF THE STATE OF TEXAS AND OF THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN

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DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED THEREBY IN CONNECTION WITH SUCH LITIGATION. THE GUARANTOR FURTHER IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS BY PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF TEXAS. THE GUARANTOR HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO TIM LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT FORUM.

SECTION 4.12Waiver of Jury Trial. THE GUARANTOR HEREBY KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVES ANY RIGHTS IT MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS GUARANTY, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE LENDERS OR THE GUARANTOR. THE GUARANTOR ACKNOWLEDGES AND AGREES THAT IT HAS RECEIVED FULL AND SUFFICIENT CONSIDERATION FOR THIS PROVISION AND THAT THIS PROVISION IS A MATERIAL INDUCEMENT FOR THE LENDERS ENTERING INTO THE CREDIT AGREEMENT.

SECTION 4.13Entire Agreement. THIS GUARANTY AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

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IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be duly executed and delivered by an officer duly authorized as of the date first above written.

[Subsidiary], a                  limited liability company
By:	MarkWest Energy Operating Company, L.L.C.,
	its Managing Member
	By:	MarkWest Energy Partners, L.P.,
		its sole Member
			By:	MarkWest Energy GP, L.L.C.,
				its General Partner
					By:
						Andrew L. Schroeder
						Vice President and Treasurer

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Exhibit F

LEGAL OPINION

[TO BE ATTACHED]

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Exhibit G

PLEDGE AND SECURITY AGREEMENT

(Subsidiary)

THIS PLEDGE AND SECURITY AGREEMENT (herein referred to as this “Security Agreement”) is executed as of              , 200  , by [Subsidiary], a              limited liability company (“Debtor”), whose address is 155 Inverness Drive West, Suite 200, Englewood, Colorado 80112, and ROYAL BANK OF CANADA., a national banking association (in its capacity as “Administrative Agent” for the Lenders (hereafter defined)), as “Secured Party,” whose address is Royal Bank Plaza, P.O. Box 50, 200 Bay Street, 12th Floor, South Tower, Toronto, Ontario M5J 2W7.

RECITALS

WHEREAS, pursuant to that certain Second Amended and Restated Credit Agreement, dated as of July     , 2004 (as the same may hereafter be amended, supplemented and restated, the “Credit Agreement”), among MarkWest Energy Operating Company, L.L.C., a Delaware limited liability company (the “Borrower”), MarkWest Energy Partners, L.P., the various financial institutions that are, or may from time to time become, parties thereto (individually a “Lender” and collectively the “Lenders”) and Royal Bank of Canada, as administrative agent (in such capacity, the “Administrative Agent”) for purposes of holding liens, administration, and enforcement;

WHEREAS, Debtor is a wholly owned subsidiary of the Borrower;

WHEREAS, Debtor has agreed to guarantee the obligations of the Borrower under the Credit Agreement and to secure its guaranteed obligations by the pledge of its assets hereunder;

WHEREAS, the Debtor has duly authorized the execution, delivery and performance of this Security Agreement;

WHEREAS, it is in the best interests of the Debtor to execute a Guaranty of the Obligations as herein defined and this Security Agreement inasmuch as the Debtor will derive substantial direct and indirect benefits from the Loans made from time to time to the Borrower by the Lenders pursuant to the Credit Agreement; and

WHEREAS, this Security Agreement is integral to the transactions contemplated by the Loan Documents, and the execution and delivery of this Security Agreement is a condition precedent to the Lenders’ obligations to extend credit under the Loan Documents.

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ACCORDINGLY, for valuable consideration, the receipt and adequacy of which are hereby acknowledged, Debtor and Secured Party hereby agree as follows:

1.REFERENCE TO CREDIT AGREEMENT. The terms, conditions, and provisions of the Credit Agreement are incorporated herein by reference, the same as if set forth herein verbatim, which terms, conditions, and provisions shall continue to be in full force and effect hereunder so long as the Lenders are obligated to lend under the Credit Agreement and thereafter until the Obligations are paid and performed in full.

2.CERTAIN DEFINITIONS. Unless otherwise defined herein, or the context hereof otherwise requires, each term defined in the Credit Agreement or in the UCC is used in this Security Agreement with the same meaning; provided that, if the definition given to such term in the Credit Agreement conflicts with the definition given to such term in the UCC, the definition in the Credit Agreement shall control to the extent legally allowable; and if any definition given to such term in Chapter 9 of the UCC conflicts with the definition given to such term in any other chapter of the UCC, the Chapter 9 definition shall prevail. As used herein, the following terms have the meanings indicated:

Borrower has the meaning set forth in the First recital.

Collateral has the meaning set forth in Paragraph 4 hereof.

Collateral Note Security has the meaning set forth in Paragraph 4 hereof.

Collateral Notes has the meaning set forth in Paragraph 4 hereof.

Control Agreement means, with respect to any Collateral consisting of investment property, Deposit Accounts, electronic chattel paper, and letter-of-credit rights, an agreement evidencing that Secured Party has “control” (as defined in the UCC) of such Collateral.

Copyrights has the meaning set forth in Paragraph 4 hereof.

Credit Agreement has the meaning set forth in the first recital.

Deposit Accounts has the meaning set forth in Paragraph 4 hereof.

Intellectual Property has the meaning set forth in Paragraph 4 hereof.

Lender means, individually, or Lenders means, collectively, on any date of determination, the Administrative Agent and Lenders, and their permitted successors and assigns.

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Material Agreements has the meaning set forth in Paragraph 4 hereof.

Obligations means, collectively, (a) the Obligations as such term is defined in the Credit Agreement, and (b) all indebtedness, liabilities, and obligations of Debtor arising under this Security Agreement or any Guaranty assuring payment of all or any part of the Obligations; it being the intention and contemplation of Debtor and Secured Party that future advances will be made by one or more Lenders to the Borrower for a variety of purposes.

Obligor means any Person obligated with respect to any of the Collateral, whether as an account debtor, obligor on an instrument, issuer of securities, or otherwise.

Partnerships/Limited Liability Companies shall mean (a) those partnerships and limited liability companies listed on Annex B-1 attached hereto and incorporated herein by reference, as such partnerships or limited liability companies exist or may hereinafter be restated, amended, or restructured; (b) any partnership, joint venture, or limited liability company in which Debtor shall, at any time, become a limited or general partner, venturer, or member; or (c) any partnership, joint venture, or corporation formed as a result of the restructure, reorganization, or amendment of the Partnerships/Limited Liability Companies.

Partnership/Limited Liability Company Agreements shall mean (a) those agreements listed on Annex B-1 attached hereto and incorporated herein by reference (together with any modifications, amendments, or restatements thereof); and (b) partnership agreements, joint venture agreements, or organizational agreements for any of the partnerships, joint ventures, or limited liability companies described in clause (b) of the definition of “Partnerships/Limited Liability Companies” above (together with any modifications, amendments or restatements thereof), and “Partnership/Limited Liability Company Agreement” means any one of the Partnership/Limited Liability Company Agreements.

Partnership/Limited Liability Company Interests shall mean all of Debtor’s Rights, title and interest now or hereafter accruing under the Partnership/Limited Liability Company Agreements with respect to all distributions, allocations, proceeds, fees, preferences, payments, or other benefits, which Debtor now is or may hereafter become entitled to receive with respect to such interests in the Partnerships/Limited Liability Companies and with respect to the repayment of all loans now or hereafter made by Debtor to the Partnerships/Limited Liability Companies.

Patents has the meaning set forth in Paragraph 4 hereof.

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Pledged Securities means, collectively, the Pledged Shares and any other Collateral constituting securities.

Pledged Shares has the meaning set forth in Paragraph 4 hereof.

Rights means rights, remedies, powers, privileges and benefits.

Security Interest means the security interest granted and the pledge and assignment made under Paragraph 3 hereof.

Trademarks has the meaning set forth in Paragraph 4 hereof.

UCC means the Uniform Commercial Code, including each such provision as it may subsequently be renumbered, as enacted in the State of Texas or other applicable jurisdiction, as amended at the time in question.

3.SECURITY INTEREST. In order to secure the full and complete payment and performance of the Obligations when due, Debtor hereby grants to Secured Party a Security Interest in all of Debtor’s Rights, titles, and interests in and to the Collateral and pledges, collaterally transfers, and assigns the Collateral to Secured Party, all upon and subject to the ten-ns and conditions of this Security Agreement. Such Security Interest is granted and pledge and assignment are made as security only and shall not subject Secured Party to, or transfer or in any way affect or modify, any obligation of Debtor with respect to any of the Collateral or any transaction involving or giving rise thereto. If the grant, pledge, or collateral transfer or assignment of any specific item of the Collateral is expressly prohibited by any contract, license, law or regulation, then the Security Interest created hereby nonetheless remains effective to the extent allowed by the UCC or other applicable Law, but is otherwise limited by that prohibition.

4.COLLATERAL. As used herein, the term “Collateral” means the following items and types of property, wherever located, now owned or in the future existing or acquired by Debtor, and all proceeds and products thereof, and any substitutes or replacements therefor:

(a)All personal property and fixture property of every kind and nature including, without limitation, all accounts, chattel paper (whether tangible or electronic), goods (including inventory, equipment, and any accessions thereto), software, instruments, investment property, documents, deposit accounts, money, commercial tort claims, letters of credit or letter-of-credit rights, supporting obligations, Tax refunds, and general intangibles (including payment intangibles);

(b)All Rights, titles, and interests of Debtor in and to all outstanding stock, equity, or other investment securities owned by Debtor, including, without limitation, all

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capital stock of each Subsidiary of the Debtor set forth on Annex B-1 (“Pledged Shares”);

(c)All Rights, titles, and interests of Debtor in and to all promissory notes and other instruments payable to Debtor, including, without limitation, all inter-company notes from Subsidiaries and those set forth on Annex B-1 (“Collateral Notes”) and all Rights, titles, interests, and Liens Debtor may have, be, or become entitled to under all present and future loan agreements, security agreements, pledge agreements, deeds of trust, mortgages, guarantees, or other documents assuring or securing payment of or otherwise evidencing the Collateral Notes, including, without limitation, those set forth on Annex B-1 (“Collateral Note Security”);

(d)The Partnership/Limited Liability Company Interests and all Rights of Debtor with respect thereto, including, without limitation, all Partnership/Limited Liability Company Interests set forth on Annex B-1 and all of Debtor’s distribution rights, income rights, liquidation interest, accounts, contract rights, general intangibles, notes, instruments, drafts, and documents relating to the Partnership/Limited Liability Company Interests;

(e)(i) All copyrights (whether statutory or common law, registered or unregistered), works protectable by copyright, copyright registrations, copyright licenses, and copyright applications of Debtor, including, without limitation, all of Debtor’s Right, title, and interest in and to all copyrights registered in the United States Copyright Office or anywhere else in the world and also including, without limitation, the copyrights set forth on Annex B-2; (ii) all renewals, extensions, and modifications thereof, (iii) all income, licenses, royalties, damages, profits, and payments relating to or payable under any of the foregoing; (iv) the Right to sue for past, present, or future infringements of any of the foregoing; and (v) all other rights and benefits relating to any of the foregoing throughout the world; in each case, whether now owned or hereafter acquired by Debtor (“Copyrights”);

(f)(i) All patents, patent applications, patent licenses, and patentable inventions of Debtor, including, without limitation, registrations, recordings, and applications thereof in the United States Patent and Trademark Office or in any similar office or agency of the United States, any state thereof or any other country or any political subdivision thereof, including, without limitation, those set forth on Annex B-2, and all of the inventions and improvements described and claimed therein; (ii) all continuations, divisions, renewals, extensions, modifications, substitutions, reexaminations, continuations-in-part, or reissues of any of the foregoing; (iii) all income, royalties, profits, damages, awards, and payments relating to or payable under any of the foregoing; (iv) the right to sue for past, present, and future infringements of any of the

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foregoing; and (v) all other rights and benefits relating to any of the foregoing throughout the world; in each case, whether now owned or hereafter acquired by Debtor (“Patents”);

(g)(i) All trademarks, trademark licenses, trade names, corporate names, company names, business names, fictitious business names, trade styles, service marks, certification marks, collective marks, logos, other business identifiers, all registrations, recordings, and applications thereof, including, without limitation, registrations, recordings, and applications In the United States Patent wid Trademark Office or in any similar office or agency of the United States, any state thereof or any other country or any political subdivision thereof, including, without limitation, those set forth on Annex B-2; (ii) all reissues, extensions, and renewals thereof; (iii) all income, royalties, damages, and payments now or hereafter relating to or payable under any of the foregoing, including, without limitation, damages or payments for past or future infringements of any of the foregoing; (iv) the right to sue for past, present, and future infringements of any of the foregoing; (v) all rights corresponding to any of the foregoing throughout the world; and (vi) all goodwill associated with and symbolized by any of the foregoing, in each case, whether now owned or hereafter acquired by Debtor (“Trademarks”, and collectively with the Copyrights and the Patents, the “Intellectual Property”);

(h)(i) All of Debtor’s Rights, titles, and interests in, to, and under those contracts pursuant to which a default in or breach of the performance or observance of any provision could result in the opinion of the Secured Party in a Material Adverse Effect (the “Material Agreements”), including, without limitation, all Rights of Debtor to receive moneys due and to become due under or pursuant to the Material Agreements, (ii) all rights of Debtor to receive proceeds of any insurance, indemnity, warranty, or guaranty with respect to the Material Agreements, (iii) all claims of Debtor for damages arising out of or for breach of or default under the Material Agreements, and (iv) all rights of Debtor to compel performance and otherwise exercise all rights and remedies under the Material Agreements;

(i)All present and future automobiles, trucks, truck tractors, trailers, semi-trailers, or other motor vehicles or rolling stock, now owned or hereafter acquired by such Debtor (collectively, the “Vehicles”);

(j)Any and all material deposit accounts, bank accounts, investment accounts, or securities accounts, now owned or hereafter acquired or opened by Debtor, including, without limitation, any such accounts set forth on Annex B-1, and any account which is a replacement or substitute for any of such accounts, together with all monies, instruments, certificates, checks, drafts, wire transfer receipts, and other property deposited therein and all balances therein (the “Deposit Accounts”);

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(k)All  permits, licenses and other authorizations (“Authorizations”) issued by any governmental authority, to the extent and only to the extent that the grant of a security interest in any such Authorization does not result in the forfeiture of, or default under, any such Authorization;

(l)All present and future distributions, income, increases, profits, combinations, reclassifications, improvements, and products of, accessions, attachments, and other additions to, tools, parts, and equipment used in connection with, and substitutes and replacements for, all or part of the Collateral described above;

(m)All present and future accounts, contract Rights, general intangibles, chattel paper, documents, instruments, cash and noncash proceeds, and other Rights arising from or by virtue of, or from the voluntary or involuntary sale or other disposition of, or collections with respect to, or insurance proceeds payable with respect to, or proceeds payable by virtue of warranty or other claims against the manufacturer of, or claims against any other Person with respect to, all or any part of the Collateral heretofore described in this clause or otherwise; and

(n)All present and future security for the payment to Debtor or any Subsidiary of any of the Collateral described above and goods which gave or will give rise to any such Collateral or are evidenced, identified, or represented there *in or thereby.

The description of the Collateral contained in this Paragraph 4 shall not be deemed to permit any action prohibited by this Security Agreement or by the terms incorporated in this Security Agreement.

5.REPRESENTATIONS AND WARRANTIES. Debtor represents and wan-ants to Secured Party that:

(a)Credit Agreement. Certain representations and warranties in the Credit Agreement are applicable to the Debtor or its assets or operations, and each such representation and warranty is true and correct,

(b)Binding Obligation/Perfection. This Security Agreement creates a legal, valid, and binding Lien in and to the Collateral in favor of Secured Party and enforceable against Debtor. For Collateral in which the Security Interest may be perfected by the filing of Financing Statements pursuant to Article 9 of the UCC, once those Financing Statements have been properly filed in the jurisdictions described on Annex A hereto, the Security Interest in that Collateral will be fully perfected and the Security Interest will constitute a first-priority Lien on such Collateral, subject only to Permitted Liens. With respect to Collateral consisting of investment property (other than Pledged Securities

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covered by Paragraph 5(j)), Deposit Accounts, electronic chattel paper, letter-of-credit rights, and instruments, upon the delivery of such Collateral to Secured Party or delivery of an executed Control Agreement with respect to such Collateral, the Security Interest in that Collateral will be fully perfected and the Security Interest will constitute a first-priority Lien on such Collateral, subject only to Permitted Liens. None of the Collateral has been delivered nor control with respect thereto given to any Person other than the Administrative Agent. Other than the Financing Statements and Control Agreements with respect to this Security Agreement, there are no other financing statements or control agreements covering any Collateral, other than those evidencing Permitted Liens. The creation of the Security Interest does not require the consent of any Person that has not been obtained.

(c)Debtor Information. Debtor’s exact legal name, mailing address, jurisdiction of organization, type of entity, and state issued organizational identification number are as set forth on Annex A hereto.

(d)Location/Fixtures. (i) Debtor’s place of business and chief executive office is where Debtor is entitled to receive notices hereunder; the present and foreseeable location of debtor’s books and records concerning any of the Collateral that is accounts is as set forth on Annex A hereto, and the location of all other Collateral, including, without limitation, Debtor’s inventory and equipment is as set forth on Annex A hereto; and, except as noted on Annex A hereto, all such books, records, and Collateral are in Debtor’s possession, and (ii) the Collateral that is or may be fixtures is located on or affixed to the real property described in deeds of trust or mortgages executed by Debtor in favor of Secured Party pursuant to the Credit Agreement or on Annex A hereto.

(e)Governmental Authority. Other than the filing of Financing Statements contemplated hereby and appropriate filings to perfect the Security Interest in the Intellectual Property, no Authorization, approval, or other action by, and no notice to or filing with, any Governmental Authority is required either (i) for the pledge by Debtor of the Collateral pursuant to this Security Agreement or for the execution, delivery, or performance of this Security Agreement by Debtor, or (ii) for the exercise by Secured Party of the voting or other Rights provided for in this Security Agreement or the remedies in respect of the Collateral pursuant to this Security Agreement (except as may be required in connection with the disposition of the Pledged Securities by Laws affecting the offering and sale of securities generally).

(f)Maintenance of Collateral. All tangible Collateral which is useful in and necessary to Debtor’s business is in good repair and condition, ordinary wear and tear excepted, and none thereof is a fixture except as specifically referred to herein in Paragraph 5(d) hereof.

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(g)Liens. Debtor owns, leases or has valid rights to use all presently existing Collateral, and will acquire or lease all hereafter-acquired Collateral, free and clear of all Liens, except Permitted Liens.

(h)Collateral. Annex B-1 accurately lists all Collateral Notes, Collateral Note Security, Pledged Shares, Partnership/Limited Liability Company Interests, commercial tort claims, and Deposit Accounts, and Annex E accurately lists all Material Agreements in which Debtor has any Rights, titles, or interest (but such failure of such description to be accurate or complete shall not impair the Security Interest in such Collateral).

(i)Instruments, Chattel Paper, Collateral Notes, and Collateral Note Security. All instruments and chattel paper, including, without limitation, the Collateral Notes, have been delivered to Secured Party, together with corresponding endorsements duly executed by Debtor in favor of Secured Party, and such endorsements have been duly and validly executed and are binding and enforceable against Debtor in accordance with their terms. Each Collateral Note and the documents evidencing the Collateral Note Security are in full force and effect; there have been no renewals or extensions of, or amendments, modifications, or supplements to, any thereof about which the Secured Party has not been advised in writing; and no “default” or “event of default” has occurred and is continuing under any such Collateral Note or documents evidencing the Collateral Note Security. Debtor has good title to the Collateral Notes and Collateral Note Security, and such Collateral Notes and Collateral Note Security are free from any claim for credit, deduction, or allowance of an Obligor and free from any defense, condition, dispute, setoff, or counterclaim, and there is no extension or indulgence with respect thereto.

(j)Pledged Securities, Pledged Shares. All Collateral that is Pledged Shares is duly authorized, validly issued, fully paid, and non-assessable, and the transfer thereof is not subject to any restrictions, other than restrictions imposed hereunder and by applicable securities and corporate Laws. The Pledged Securities securing the Obligations as defined in the Credit Agreement include 100% of the issued and outstanding common stock or other equity interests of each Subsidiary of the Debtor. Debtor has good title to the Pledged Securities, free and clear of all Liens and encumbrances thereon (except for the Security Interest created hereby), and has delivered to Secured Party (i) all stock certificates, or other instruments or documents representing or evidencing the Pledged Securities, together with corresponding assignment or transfer powers duly executed in blank by Debtor, and such powers have been duly and validly executed and are binding and enforceable against Debtor in accordance with their terms or (ii) to the extent such Pledged Securities are uncertificated, an executed Acknowledgment of Pledge with respect to such Pledged Securities. The pledge of the Pledged Securities in accordance with the terms hereof creates a valid and perfected first priority security interest in the Pledged Securities securing payment of the Obligations.

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(k)Partnership/Limited Liability Company Interests. Each Partnership/Limited Liability Company issuing a Partnership/Limited Liability Company Interest, is duly organized, currently existing, and in good standing under all applicable Laws; there have been no amendments, modifications, or supplements to any agreement or certificate creating any Partnership/Limited Liability Company or any material contract relating to the Partnerships/Limited Liability Companies, of which Secured Party has not been advised in writing; no event of default, default, breach, or potential default has occurred and is continuing under any Partnership/Limited Liability Company Agreement; and no approval or consent of the partners of any Partnership/Limited Liability Company is required as a condition to the validity and enforceability of the Security Interest created hereby or the consummation of the transactions contemplated hereby which has not been duly obtained by Debtor. Debtor has good title to the Partnership/Limited Liability Company Interests free and clear of all Liens and encumbrances (except for the Security Interest granted hereby), ‘Me Partnership/Limited Liability Company Interests are validly issued, fully paid, and nonassessable and are not subject to statutory, contractual, or other restrictions governing their transfer, ownership, or control, except as set forth in the applicable Partnership/Limited Liability Company Agreements or applicable securities Laws. All capital contributions required to be made by the terms of the Partnership/Limited Liability Company Agreements for each Partnership/Limited Liability Company have been made. No limited liability company interests are evidenced by certificates.

(1)Accounts. All Collateral that is accounts, contract rights, chattel paper, instruments, payment intangibles, or general intangibles is free from any claim for credit, deduction, or allowance of an Obligor, from any defense, condition, dispute, setoff, or counterclaim (collectively “Deductions”), and there is no extension or indulgence with respect thereto, except to the extent such Deductions, extensions and indulgences could not reasonably be expected to have a Material Adverse Effect.

(m)Material Agreements. Each Material Agreement is in full force and effect; there have been no amendments, modifications, or supplements to any Material Agreement of which Secured Party has not been advised in writing; and no event of default, default, breach, or potential default by Debtor or, to Debtor’s knowledge, by any other party thereto has occurred and is continuing under any Material Agreement, except as disclosed on Annex E hereto.

(n)Deposit Accounts. With respect to the Deposit Accounts, (i) Debtor maintains each Deposit Account with the banks listed on Annex B-1 hereto, (ii) upon request by the Administrative Agent, Debtor shall use its best efforts to, within thirty (30) days of such request, cause each such bank to acknowledge to Secured Party that each such Deposit Account is subject to the Security Interest and Liens herein created, that the

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pledge of such Deposit Account has been recorded in the books and records of such bank, and that Secured Party shall have “control” (as defined in the UCC) over such Deposit Account, and (iii) Debtor has the legal Right to pledge and assign to Secured Party the funds deposited and to be deposited in each such Deposit Account.

(o)Intellectual Property.

(i)All of the Intellectual Property is subsisting, valid, and enforceable. The information contained on Annex B-2 hereto is true, correct and complete. All issued Patents, Patent applications, registered Trademarks, Trademark applications, registered Copyrights, and Copyright applications of Debtor are identified on Annex B-2 hereto.

(ii)Debtor is the sole and exclusive owner of the entire and unencumbered Right, title, and interest in and to the Intellectual Property (other than off-the-shelf software) free and clear of any Liens, including, without limitation, any pledges, assignments, licenses, user agreements, and covenants by Debtor not to sue third Persons, other than Permitted Liens or licenses permitted by Paragraph 8(c).

(iii)To Debtor’s knowledge, no third party is infringing any of Debtor’s Rights under the Intellectual Property.

(iv)Debtor has performed and will continue to perform all acts and has paid and will continue to pay all required fees and Taxes to maintain each material item of the Intellectual Property in full force and effect throughout the world, as applicable.

(v)Each of the Patents and Trademarks identified on Annex B-2 hereto, to the extent required in Debtor’s reasonable business judgment, has been properly registered with the United States Patent and Trademark Office and in corresponding offices throughout the world (where appropriate) and each of the Copyrights identified on Annex B-2 hereto has been properly registered with the United States Copyright Office and in corresponding offices throughout the world (where appropriate).

(vi)To Debtor’s knowledge, no claims with respect to the Intellectual Property have been asserted and are pending (i) to the effect that the sale, licensing, pledge, or use of any of the products of Debtor’s business infringes any other party’s valid copyright, trademark, service mark, trade secret, or other intellectual property Right, (ii) against the use by Debtor of any Intellectual Property used in the Debtor’s business as currently conducted, or (iii) challenging

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the ownership or use by Debtor of any of the Intellectual Property that Debtor purports to own or use, nor, to Debtor’s knowledge, is there a valid basis for such a claim described in this Paragraph 5(o)(vi).

The foregoing representations and warranties will be true and correct in all respects with respect to any additional Collateral or additional specific descriptions of certain Collateral delivered to Secured Party in the future by Debtor. The failure of any of these representations or warranties or any description of Collateral therein to be accurate or complete shall not impair the Security Interest in any such Collateral.

6.COVENANTS. So long as any Lenders are committed to make Credit Extensions under the Credit Agreement, and until the Obligations are paid and performed in full, Debtor covenants and agrees with Secured Party that Debtor will:

(a)Credit Agreement. (i) Comply with, perform, and be bound by all covenants and agreements in the Credit Agreement that are applicable to it, its assets, or its operations, each of which is hereby ratified and confirmed (INCLUDING, WITHOUT LIMITATION, THE INDEMNIFICATION AND RELATED PROVISIONS IN SECTION 10.05 OF THE Credit Agreement); AND (ii) CONSENT TO AND APPROVE THE VENUE, SERVICE OF PROCESS, AND WAIVER OF JURY TRIAL PROVISIONS OF SECTIONS 10.16 AND 10. 17 OF THE CREDIT AGREEMENT.

(b)Information/Record of Collateral. Maintain, at the place where Debtor is entitled to receive notices under the Loan Documents, a current record of where all Collateral is located, permit representatives of Secured Party at any time during normal business hours to inspect and make abstracts from such records, and furnish to Secured Party, at such intervals as Secured Party may request, such documents, lists, descriptions, certificates, and other information as maybe necessary or proper to keep Secured Party informed with respect to the identity, location, status, condition, and value of the Collateral. In addition, from time to time at the request of Secured Party deliver to Secured Party such information regarding Debtor as Secured Party may reasonably request.

(c)Annexes. Together with the delivery of compliance certificates pursuant to Sections 6.01 and 6.02 of the Credit Agreement, update all annexes hereto if any information therein shall become inaccurate or incomplete. Notwithstanding any other provision herein, Debtor’s failure to describe any Collateral required to be listed on any annex hereto shall not impair Secured Party’s Security Interest in the Collateral.

(d)Perform Obligations. Fully perform all of Debtor’s duties under and in connection with each transaction to which the Collateral, or any part thereof, relates, so

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that the amounts thereof shall actually become payable in their entirety to Secured Party. Furthermore, notwithstanding anything to the contrary contained herein, (i) Debtor shall remain liable under the contracts, agreements, documents, and instruments included in the Collateral to the extent set forth therein to perform all of its duties and obligations thereunder to the same extent as if this Security Agreement had not been executed, (ii) the exercise by Secured Party of any of its Rights or remedies hereunder shall not release Debtor from any of its duties or obligations under the contracts, agreements, documents, and instruments included in the Collateral, and (iii) Secured Party shall not have any indebtedness, liability, or obligation under any of the contracts, agreements, documents, and instruments included in the Collateral by reason of this Security Agreement, and Secured Party shall not be obligated to perform any of the obligations or duties of debtor thereunder or to take any action to collect or enforce any claim for payment assigned hereunder.

(e)Notices. (i) Except as may be otherwise expressly permitted under the terms of the Credit Agreement, promptly notify Secured Party of (A) any change in any fact or circumstances represented or warranted by Debtor with respect to any of the Collateral or Obligations, (B) any claim, action, or proceeding affecting title to all or any of the Collateral or the Security Interest and, at the request of Secured Party, appear in and defend, at Debtor’s expense, any such action or proceeding, (C) any material change in the nature of the Collateral, (D) any material damage to or loss of Collateral, and (E) the occurrence of any other event or condition (including, without limitation, matters as to Lien priority) that could reasonably be expected to have a material adverse effect on the Collateral (taken as a whole) or the Security Interest created hereunder; and (ii) give Secured Party thirty (30) days written notice before any proposed (A) relocation of its principal place of business or chief executive office, (B) change of its name, identity, or corporate structure, (C) relocation of the place where its books and records concerning its accounts are kept, (D) relocation of any Collateral (other than delivery of inventory in the ordinary course of business to third party contractors for processing and sales of inventory in the ordinary course of business or as permitted by the Credit Agreement) to a location not described on the attached Annex A, and (E) change of its jurisdiction of organization or organizational identification number, as applicable. Prior to making any of the changes contemplated in clause (ii) preceding, Debtor shall execute and deliver all such additional documents and perform all additional acts as Secured Party, in its sole discretion, may request in order to continue or maintain the existence and priority of the Security Interests in all of the Collateral.

(f)Collateral in Trust. Hold in trust (and not commingle with other assets of Debtor) for Secured Party all Collateral that is chattel paper, instruments, Collateral Notes, Pledged Securities, or documents at any time received by Debtor, and promptly deliver same to Secured Party, unless Secured Party at its option (which may be

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evidenced only by a writing signed by Secured Party stating that Secured Party elects to pen-nit Debtor to so retain) permits Debtor to retain the same, but any chattel paper, instruments, Collateral Notes, Pledged Securities, or documents so retained shall be marked to state that they are assigned to Secured Party; each such instrument shall be endorsed to the order of Secured Party (but the failure of same to be so marked or endorsed shall not impair the Security Interest thereon).

(g)Control. Execute all documents and take any action required by Secured Party in order for Secured Party to obtain “control” (as defined in the UCC) with respect to Collateral consisting of Deposit Accounts, investment property, uncertificated Pledged Securities, and letter-of-credit rights. If Debtor at any time holds or acquires an interest in any electronic chattel paper or any “transferable record, “ as that term is defined in the federal Electronic Signatures in Global and National Commerce Act, or in the Uniform Electronic Transactions Act as in effect in any relevant jurisdiction, promptly notify Secured Party thereof and, at the request of Secured Party, take such action as Secured Party may reasonably request to vest in Secured Party control under the UCC of such electronic chattel paper or control under the federal Electronic Signatures in Global and National Commerce Act or, as the case may be, the Uniform Electronic Transactions Act, as so in effect in such jurisdiction, of such transferable record.

(h)Further Assurances. At Debtor’s expense and Secured Party’s request, before or after a Default or Event of Default, (1) file or cause to be filed such applications and take such other actions as Secured Party may request to obtain the consent or approval of any Governmental Authority to Secured Party’s Rights hereunder, including, without limitation, the Right to sell all the Collateral upon an Event of Default without additional consent or approval from such Governmental Authority (and, because Debtor agrees that Secured Party’s remedies at Law for failure of debtor to comply with this provision would be inadequate and that such failure would not be adequately compensable in damages, Debtor agrees that its covenants in this provision may be specifically enforced); (ii) from time to time promptly execute and deliver to Secured Party all such other assignments, certificates, supplemental documents, and financing statements, and do all other acts or things as Secured Party may reasonably request in order to more fully create, evidence, perfect, continue, and preserve the priority of the Security Interest and to carry out the provisions of this Security Agreement; and (iii) pay all filing fees in connection with any financing, continuation, or termination statement or other instrument with respect to the Security Interests.

(i)Encumbrances. Not create, permit, or suffer to exist, and shall defend the Collateral against, any Lien or other encumbrance on the Collateral, other than Permitted Liens, and shall defend Debtor’s Rights in the Collateral and Secured Party’s Security Interest in the Collateral against the claims and demands of all Persons except those

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holding or claiming Permitted Liens. Debtor shall do nothing to impair the Rights of Secured Party in the Collateral.

(j)Estoppel and Other Agreements and Matters. Upon the reasonable request of Secured Party, either (i) use commercially reasonable efforts to cause the landlord or lessor for each location where any of its inventory or equipment is maintained to execute and deliver to Secured Party an estoppel and subordination agreement in such form as may be reasonably acceptable to Secured Party and its counsel, or (ii) deliver to Secured Party a legal opinion or other evidence (in each case that is reasonably satisfactory to Secured Party and it counsel) that neither the applicable lease nor the Laws of the jurisdiction in which that location is situated provide for contractual, common Law, or statutory landlord’s Liens that is senior to or pari passu with the Security Interest.

(k)Fixtures. For any Collateral that is a fixture or an accession which has been attached to real estate or other goods prior to the perfection of the Security Interest, use commercially reasonable efforts to furnish to Secured Party, upon reasonable demand, a disclaimer of interest in each such fixture or accession and a consent in writing to the Security Interest of Secured Party therein, signed by all Persons having any interest in such fixture or accession by virtue of any interest in the real estate or other goods to which such fixture or accession has been attached.

(1)Certificates of Title. Upon the request of Secured Party, if certificates of title are issued or outstanding with respect to any of the Vehicles or other Collateral, cause the Security Interest to be properly noted thereon.

(m)Warehouse Receipts Non-Negotiable.  If any warehouse receipt or receipt in the nature of a warehouse receipt is issued in respect of any of the Collateral, agree that such warehouse receipt or receipt in the nature thereof shall not be “negotiable” (as such term is used in Section 7-104 of the UCC) unless such warehouse receipt or receipt in the nature thereof is delivered to Secured Party.

(n)Impairment of Collateral. Not use any of the Collateral, or permit the same to be used, for any unlawful purpose, in any manner that is reasonably likely to adversely impair the value or usefulness of the Collateral, or in any manner inconsistent with the provisions or requirements of any policy of insurance thereon nor affix or install any accessories, equipment, or device on the Collateral or on any component thereof if such addition will impair the original intended function or use of the Collateral or such component.

(o)Collateral Notes and Collateral Note Security. Without the prior written consent of Secured Party not (i) modify or substitute, or permit the modification or substitution of, any Collateral Note or any document evidencing the Collateral Note

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Security or (ii) release any Collateral Note Security unless paid in full or otherwise specifically required by the terms thereof.

(p)Securities. Except as permitted by the Credit Agreement, not sell, exchange, or otherwise dispose of, or grant any option, warrant, or other Right with respect to, any of the Pledged Securities; to the extent any issuer of any Pledged Securities is controlled by Debtor and/or its Affiliates, not permit such issuer to issue any additional shares of stock or other securities in addition to or in substitution for the Pledged Securities, except issuances to Debtor on terms acceptable to Secured Party; pledge hereunder, immediately upon Debtor’s acquisition (directly or indirectly) thereof, any and all additional shares of stock or other securities of each Subsidiary of Debtor; and take any action necessary, required, or requested by Secured Party to allow Secured Party to fully enforce its Security Interest in the Pledged Securities, including, without limitation, the filing of any claims with any court, liquidator, trustee, custodian, receiver, or other like person or party.

(q)Partnerships/Limited Liability Companies and Partnership/Limited Liability Company Interests. (i) Promptly perform, observe, and otherwise comply with each and every covenant, agreement, requirement, and condition set forth in the contracts and agreements creating or relating to any Partnership/Limited Liability Company; (ii) do or cause to be done all things necessary or appropriate to keep the Partnerships/Limited Liability Companies in full force and effect and the Rights of Debtor and Secured Party thereunder unimpaired; (iii) except as expressly permitted by the Credit Agreement, not consent to any Partnership/Limited Liability Company selling, leasing, or disposing of substantially all of its assets in a single transaction or a series of transactions; (iv) notify Secured Party of the occurrence of any event of default, default, breach, or potential default under any contract or agreement creating or relating to the Partnerships/Limited Liability Companies; (v) not consent to the amendment, modification, surrender, impairment, forfeiture, cancellation, dissolution, or termination of any Partnership/Limited Liability Company, or material agreement relating thereto; (vi) except as permitted by the Credit Agreement, not transfer, sell, or assign any of the Partnership/Limited Liability Company Interests or any part thereof; (vii) to the extent any Partnership/Limited Liability Company is controlled by Debtor and/or its Affiliates, cause such Partnership/Limited Liability Company to refrain from granting any Partnership/Limited Liability Company Interests in addition to or in substitution for the Partnership/Limited Liability Company Interests granted by the Partnerships/Limited Liability Companies, except to Debtor, (viii) pledge hereunder, immediately upon Debtor’s acquisition (directly or indirectly) thereof, any and all additional Partnership/Limited Liability Company Interests of any Partnership/Limited Liability Company granted to Debtor; and any and all additional shares of stock or other securities of each; (ix) deliver to Secured Party a fully-executed Acknowledgment of Pledge,

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substantially in the form of Annex D, for each Partnership/Limited Liability Company Interest; and (x) take any action necessary, required, or requested by Secured Party to allow Secured Party to fully enforce its Security Interest in the Partnership/Limited Liability Company Interests, including, without limitation, the filing of any claims with any court, liquidator, trustee, custodian, receiver, or other like person or party.

(r)Material Agreements. (i) Promptly perform, observe, and otherwise comply with each and every covenant, agreement, requirement, and condition set forth in the Material Agreements, except to the extent non-compliance could not reasonably be expected to have a Material Adverse Effect; (ii) do or cause to be done all things necessary or appropriate to keep the Material Agreements in full force and effect and the Rights of Debtor and Secured Party thereunder unimpaired, except to the extent that failure to do so could not reasonably be expected to have a Material Adverse Effect; (iii) notify Secured Party of the occurrence of any default, breach or event of default under any Material Agreement; and (iv) without the prior written consent of Secured Party, not consent to the amendment, modification, surrender, impairment, forfeiture, cancellation, dissolution, or termination of any Material Agreement, other than (A) cancellation or termination in accordance with the terms thereof, and (B) any amendment, modification, surrender, impairment, forfeiture, cancellation, dissolution, or termination that could not reasonably be expected to have a Material Adverse Effect.

(s)Depository Bank. With respect to any Deposit Accounts, (i) maintain the Deposit Accounts at the banks (a “depository bank”) described on Annex B-1 or such additional depository banks as described in the notices given pursuant to clause (iv) of this Section 6(s) as have complied with item (iv) hereof, (ii) upon request of the Secured Party, deliver to each depository bank a letter in the form of Annex C hereto with respect to Secured Party’s Rights in such Deposit Account and use commercially reasonable efforts to (provided however, that if a Default or Event of Default has occurred and is continuing, Debtor shall) obtain the execution of such letter by each depository bank that the pledge of such Deposit Account has been recorded in the books and records of such bank and that Secured Party shall have dominion and control over such Deposit Account; (iii) upon request of the Secured Party, deliver to Secured Party all certificates or instruments, if any, now or hereafter representing or evidencing the Deposit Accounts, accompanied by duly executed instruments of transfer or assignment in blank, all in form and substance reasonably satisfactory to Secured Party; and (iv) notify Secured Party upon establishing any additional Deposit Accounts and, at the request of Secured Party, use commercially reasonable efforts to (provided however, that if a Default or Event of Default has occurred and is continuing, Debtor shall) obtain from such depository bank an executed letter substantially in the form of Annex C and deliver the same to Secured Party.

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(t)Marking of Chattel Paper. At the request of Secured Party, not create any chattel paper without placing a legend on the chattel paper acceptable to Secured Party indicating that Secured Party has a security ‘interest in the chattel paper.

(u)Modification of Accounts. In accordance with prudent business practices, endeavor to collect or cause to be collected from each account debtor under its accounts, as and when due, any and all amounts owing under such accounts. Except in the ordinary course of business consistent with prudent business practices and industry standards, without the prior written consent of Secured Party, Debtor shall not (i) grant any extension of time for any payment with respect to any of the accounts, (ii) compromise, compound, or settle any of the accounts for less than the full amount thereof, (iii) release, in whole or in part, any Person liable for payment of any of the accounts, (iv) allow any credit or discount for payment with respect to any account other than trade discounts granted in the ordinary course of business, (v) release any Lien or guaranty securing any account, (vi) modify or substitute, or permit the modification or substitution of, any contract to which any of the Collateral which is accounts relates.

(v)Intellectual Property.

(i)Prosecute diligently all applications in respect of Intellectual Property, now or hereafter pending;

(ii)Except to the extent not required in Debtor’s reasonable business judgment, make federal applications on all of its unpatented but patentable inventions and all of its registrable but unregistered Copyrights and Trademarks;

(iii)Preserve and maintain all of its material rights in the Intellectual Property and protect the Intellectual Property from infringement, unfair competition, cancellation, or dilution by all appropriate action necessary in Debtor’s reasonable business judgment, including, without limitation, the commencement and prosecution of legal proceedings to recover damages for infringement and to defend and preserve its rights in the Intellectual Property;

(iv)Not abandon any of the Intellectual Property necessary to the conduct of its business in the exercise of Debtor’s reasonable business judgment;

(v)(A) Not sell or assign any of its interest in any of the Intellectual Property other than in the ordinary course of business for full and fair consideration without the prior written consent of Secured Party; (B) not grant any license or sublicense with respect to any of the Intellectual Property other than as permitted by Paragraph 8(c) hereof without the prior written consent of

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Secured Party; and (C) maintain the quality of any and all products and services with respect to which the Intellectual Property is used;

(vi)Not enter into any agreement, including, but not limited to any licensing agreement, that is or may be inconsistent with Debtor’s obligations under this Security Agreement or any of the other Loan Documents;

(vii)Give Secured Party prompt written notice if Debtor shall obtain Rights to or become entitled to the benefit of any Intellectual Property not identified on Annex B-2 hereto; and

(viii)If a Default or Event of Default exists, use its reasonable efforts to obtain any consents, waivers, or agreements necessary to enable Secured Party to exercise its rights and remedies with respect to the Intellectual Property.

7.DEFAULT; REMEDIES. If an Event of Default exists, Secured Party may, at its election (but subject to the terms and conditions of the Credit Agreement), exercise any and all Rights available to a secured party under the UCC and other applicable law, in addition to any and all other Rights afforded by the Loan Documents, at law, in equity, or otherwise, including, without limitation, (a) requiring Debtor to assemble all or part of the Collateral and make it available to Secured Party at a place to be designated by Secured Party which is reasonably convenient to Debtor and Secured Party, (b) to the extent permitted by Debtor’s insurance carrier, surrendering any policies of insurance on all or part of the Collateral and receiving and applying the unearned premiums as a credit on the Obligations, (c) applying by appropriate judicial proceedings for appointment of a receiver for all or part of the Collateral (and Debtor hereby consents to any such appointment), and (d) applying to the Obligations any cash held by Secured Party under this Security Agreement, including, without limitation, any cash in the Cash Collateral Account (defined in Section 8(h)).

(a)Notice. Reasonable notification of the time and place of any public sale of the Collateral, or reasonable notification of the time after which any private sale or other intended disposition of the Collateral is to be made, shall be sent to Debtor and to any other Person entitled to notice under the UCC; provided that, if any of the Collateral threatens to decline speedily in value or is of the type customarily sold on a recognized market, Secured Party may sell or otherwise dispose of the Collateral without notification, advertisement, or other notice of any kind. It is agreed that notice sent or given not less than five Business Days prior to the taking of the action to which the notice relates is reasonable notification and notice for the purposes of this subparagraph.

(b)Condition of Collateral; Warranties. Secured Party has no obligation to clean-up or otherwise prepare the Collateral for sale. Secured Party may sell the Collateral without giving any warranties as to the Collateral. Secured Party may

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specifically disclaim any warranties of title or the like. This procedure will not be considered to affect adversely the commercial reasonableness of any sale of the Collateral.

(c)Compliance with Other Laws. Secured Party may comply with any applicable state or federal law requirements in connection with a disposition of the Collateral and compliance will not be considered to adversely affect the commercial reasonableness of any sale of the Collateral.

(d)Sales of Pledged Securities.

(i)Debtor agrees that, because of the Securities Act of 1933, as amended, or the rules and regulations promulgated thereunder (collectively, the “Securities Act”), or any other Laws or regulations, and for other reasons, there may be legal or practical restrictions or limitations affecting Secured Party in any attempts to dispose of certain portions of the Pledged Securities and for the enforcement of its Rights. For these reasons, Secured Party is hereby authorized by Debtor, but not obligated, upon the occurrence and during the continuation of an Event of Default, to sell all or any part of the Pledged Securities at private sale, subject to investment letter or in any other manner which will not require the Pledged Securities, or any part thereof, to be registered in accordance with the Securities Act or any other Laws or regulations, at a reasonable price at such private sale or other distribution in the manner mentioned above. Debtor understands that Secured Party may in its discretion approach a limited number of potential purchasers and that a sale under such circumstances may yield a lower price for the Pledged Securities, or any part thereof, than would otherwise be obtainable if such Collateral were either afforded to a larger number of potential purchasers, registered under the Securities Act, or sold in the open market. Debtor agrees that any such private sale made under this Paragraph 7(d) shall be deemed to have been made in a commercially reasonable manner, and that Secured Party has no obligation to delay the sale of any Pledged Securities to permit the issuer thereof to register it for public sale under any applicable federal or state securities Laws.

(ii)Secured Party is authorized, in connection with any such sale, (A) to restrict the prospective bidders on or purchasers of any of the Pledged Securities to a limited number of sophisticated investors who will represent and agree that they are purchasing for their own account for investment and not with a view to the distribution or sale of any of such Pledged Securities, and (B) to impose such other limitations or conditions in connection with any such sale as Secured Party reasonably deems necessary in order to comply with applicable

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Law. Debtor covenants and agrees that it will execute and deliver such documents and take such other action as Secured Party reasonably deems necessary in order that any such sale may be made in compliance with applicable Law. Upon any such sale Secured Party shall have the Right to deliver, assign, and transfer to the purchaser thereof the Pledged Securities so sold. Each purchaser at any such sale shall hold the Pledged Securities so sold absolutely free from any claim or Right of Debtor of whatsoever kind, including any equity or Right of redemption of Debtor. Debtor, to the extent permitted by applicable Law, hereby specifically waives all Rights of redemption, stay, or appraisal which it has or may have under any Law now existing or hereafter enacted.

(iii)Debtor agrees that five days’ written notice from Secured Party to Debtor of Secured Party’s intention to make any such public or private sale or sale at a broker’s board or on a securities exchange shall constitute reasonable notice under the UCC. Such notice shall (A) in case of a public sale, state the time and place fixed for such sale, (B) in case of sale at a broker’s board or on a securities exchange, state the board or exchange at which such a sale is to be made and the day on which the Pledged Securities, or the portion thereof so being sold, will first be offered to sale at such board or exchange, and (C) in the case of a private sale, state the day after which such sale may be consummated. Any such public sale shall be held at such time or times within ordinary business hours and at such place or places as Secured Party may fix in the notice of such sale. At any such sale, the Pledged Securities may be sold in one lot as an entirety or in separate parcels, as Secured Party may reasonably determine. Secured Party shall not be obligated to make any such sale pursuant to any such notice. Secured Party may, without notice or publication, adjourn any public or private sale or cause the same to be adjourned from time to time by announcement at the time and place fixed for the sale, and such sale may be made at any time or place to which the same may be so adjourned.

(iv)In case of any sale of all or any part of the Pledged Securities on credit or for future delivery, the Pledged Securities so sold may be retained by Secured Party until the selling price is paid by the purchaser thereof, but Secured Party shall not incur any liability in case of the failure of such purchaser to take up and pay for the Pledged Securities so sold and in case of any such failure, such Pledged Securities may again be sold upon like notice. Secured Party, instead of exercising the power of sale herein conferred upon it, may proceed by a suit or suits at Law or in equity to foreclose the Security Interests and sell the Pledged Securities, or any portion thereof, under a judgment or decree of a court or courts of competent jurisdiction.

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(v)Without limiting the foregoing, or imposing upon Secured Party any obligations or duties not required by applicable Law, Debtor acknowledges and agrees that, in foreclosing upon any of the Pledged Securities, or exercising any other Rights or remedies provided Secured Party hereunder or under applicable Law, Secured Party may, but shall not be required to, (A) qualify or restrict prospective purchasers of the Pledged Securities by requiring evidence of sophistication or creditworthiness, and requiring the execution and delivery of confidentiality agreements or other documents and agreements as a condition to such prospective purchasers’ receipt of information regarding the Pledged Securities or participation in any public or private foreclosure sale process, (B) provide to prospective purchasers business and financial information regarding Debtor and its Subsidiaries available in the files of Secured Party at the time of commencing the foreclosure process, without the requirement that Secured Party obtain, or seek to obtain, any updated business or financial information or verify, or certify to prospective purchasers, the accuracy of any such business or financial information, or (C) offer for sale and sell the Pledged Securities with or without first employing an appraiser, investment banker, or broker with respect to the evaluation of the Pledged Securities, the solicitation of purchasers for Pledged Securities, or the manner of sale of Pledged Securities.

(e)Application of Proceeds. Secured Party shall apply the proceeds of any sale or other disposition of the Collateral under this Paragraph 7 in the following order: first, to the payment of all expenses incurred in retaking, holding, and preparing any of the Collateral for sale(s) or other disposition, in arranging for such sale(s) or other disposition, and in actually selling or disposing of the same (all of which are part of the Obligations); second, toward repayment of amounts expended by Secured Party under Paragraph 8; and third, toward payment of the balance of the Obligations in the order and manner specified in the Credit Agreement. Any surplus remaining shall be delivered to Debtor or as a court of competent jurisdiction may direct. If the proceeds are insufficient to pay the Obligations in full, Debtor shall remain liable for any deficiency.

(f)Sales on Credit. If Secured Party sells any of the Collateral upon credit, Debtor will be credited only with payments actually made by the purchaser, received by the Secured Party, and applied to the indebtedness of the purchaser. In the event the purchaser fails to pay for the Collateral, Secured Party may resell the Collateral and Debtor shall be credited with the proceeds of the sale.

8.OTHER RIGHTS OF SECURED PARTY.

(a)Performance. If Debtor fails to keep the Collateral in good repair, working order, and condition, as required by the Loan Documents, or fails to pay when due all

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Taxes on any of the Collateral in the manner required by the Loan Documents, or fails to preserve the priority of the Security Interest in any of the Collateral, or fails to keep the Collateral insured as required by the Loan Documents, or otherwise fails to perform any of its obligations under the Loan Documents with respect to the Collateral, then Secured Party may, at its option, but without being required to do so, make such repairs, pay such Taxes, prosecute or defend any suits in relation to the Collateral, or insure and keep insured the Collateral in any amount deemed appropriate by Secured Party, or take all other action which Debtor is required, but has failed or refused, to take under the Loan Documents. Any sum which may be expended or paid by Secured Party under this subparagraph (including, without limitation, court costs and reasonable attorneys’ fees) shall bear interest from the dates of expenditure or payment at the Default Rate until paid and, together with such interest, shall be payable by Debtor to Secured Party upon demand and shall be part of the Obligations.

(b)Collection. If an Event of Default exists and upon notice from Secured Party, each Obligor with respect to any payments on any of the Collateral (including, without limitation, dividends and other distributions with respect to the Pledged Securities and Partnership/Limited Liability Company Interests, payments on Collateral Notes, insurance proceeds payable by reason of loss or damage to any of the Collateral, or payments or distributions with respect to Deposit Accounts) is hereby authorized and directed by Debtor to make payment directly to Secured Party, regardless of whether Debtor was previously making collections thereon. Subject to Paragraph 8(f) hereof, until such notice is given, Debtor is authorized to retain and expend all payments made on Collateral. If an Event of Default exists, Secured Party shall have the Right in its own name or in the name of Debtor to compromise or extend time of payment with respect to all or any portion of the Collateral for such amounts and upon such terms as Secured Party may determine; to demand, collect receive, receipt for, sue for, compound, and give acquittances for any and all amounts due or to become due with respect to Collateral; to take control of cash and other proceeds of any Collateral; to endorse the name of Debtor on any notes, acceptances, checks, drafts, money orders, or other evidences of payment on Collateral that may come into the possession of Secured Party; to sign the name of Debtor on any invoice or bill of lading relating to any Collateral, on any drafts against Obligors or other Persons making payment with respect to Collateral, on assignments and verifications of accounts or other Collateral and on notices to Obligors making payment with respect to Collateral; to send requests for verification of obligations to any Obligor; and to do all other acts and things necessary to carry out the intent of this Security Agreement. If an Event of Default exists and any Obligor fails or refuses to make payment on any Collateral when due, Secured Party is authorized, in its sole discretion, either in its own name or in the name of Debtor, to take such action as Secured Party shall deem appropriate for the collection of any amounts owed with respect to Collateral or upon which a delinquency exists. Regardless of any other provision hereof, however,

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Secured Party shall never be liable for its failure to collect, or for its failure to exercise diligence in the collection of, any amounts owed with respect to Collateral, nor shall it be under any duty whatsoever to anyone except Debtor to account for funds that it shall actually receive hereunder. Without limiting the generality of the foregoing, Secured Party shall have no responsibility for ascertaining any maturities, calls, conversions, exchanges, offers, tenders, or similar matters relating to any Collateral, or for informing Debtor with respect to any of such matters (irrespective of whether Secured Party actually has, or may be deemed to have, knowledge thereof). The receipt of Secured Party to any Obligor shall be a full and complete release, discharge, and acquittance to such Obligor, to the extent of any amount so paid to Secured Party.

(c)Intellectual Property. For purposes of enabling Secured Party to exercise its Rights and remedies under this Security Agreement and enabling Secured Party and its successors and assigns to enjoy the full benefits of the Collateral, Debtor hereby grants to Secured Party an irrevocable, nonexclusive license (exercisable without payment of royalty or other compensation to Debtor) to use, license, or sublicense any of the Intellectual Property. Debtor shall provide Secured Party with reasonable access to all media in which any of the Intellectual Property may be recorded or stored and all computer programs used for the completion or printout thereof. This license shall also inure to the benefit of all successors, assigns, and transferees of Secured Party. Upon the occurrence of an Event of Default, Secured Party may require that Debtor assign all of its Right, title, and interest in and to the Intellectual Property or any part thereof to Secured Party or such other Person as Secured Party may designate pursuant to documents satisfactory to Secured Party. If no Default or Event of Default exists, Debtor shall have the exclusive, non-transferable Right and license to use the Intellectual Property in the ordinary course of business and the exclusive Right to grant to other Persons licenses and sublicenses with respect to the Intellectual Property for full and fair consideration.

(d)Record Ownership of Securities. If a Default or Event of Default exists, Secured Party at any time may have any Collateral that is Pledged Securities and that is in the possession of Secured Party, or its nominee or nominees, registered in its name, or in the name of its nominee or nominees, as Secured Party; and, as to any Collateral that is Pledged Securities so registered, Secured Party shall execute and deliver (or cause to be executed and delivered) to Debtor all such proxies, powers of attorney, dividend coupons or orders, and other documents as Debtor may reasonably request for the purpose of enabling Debtor to exercise the voting Rights and powers which it is entitled to exercise under this Security Agreement or to receive the dividends and other distributions and payments in respect of such Collateral that is Pledged Securities or proceeds thereof which it is authorized to receive and retain under this Security Agreement.

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(e)Voting of Securities. As long as no Default or Event of Default exists, Debtor is entitled to exercise all voting Rights pertaining to any Pledged Securities and Partnership/Limited Liability Company Interests; provided however, that no vote shall be cast or consent, waiver, or ratification given or action taken without the prior written consent of Secured Party which would (x) be inconsistent with or violate any provision of this Security Agreement or any other Loan Document or (y) amend, modify, or waive any term, provision or condition of the certificate of incorporation, bylaws, certificate of formation, or other charter document, or other agreement relating to, evidencing, providing for the issuance of, or securing any Collateral; and provided further that Debtor shall give Secured Party at least five Business Days’ prior written notice in the form of an officers’ certificate of the manner in which it intends to exercise, or the reasons for refraining from exercising, any voting or other consensual Rights pertaining to the Collateral or any part thereof which might have a material adverse effect on the value of the Collateral or any part thereof. If an Event of Default exists and if Secured Party elects to exercise such Right, the Right to vote any Pledged Securities shall be vested exclusively in Secured Party. To this end, Debtor hereby irrevocably constitutes and appoints Secured Party the proxy and attorney-in-fact of Debtor, with fall power of substitution, to vote, and to act with respect to, any and all Collateral that is Pledged Securities standing in the name of Debtor or with respect to which Debtor is entitled to vote and act, subject to the understanding that such proxy may not be exercised unless an Event of Default exists. The proxy herein granted is coupled with an interest, is irrevocable, and shall continue until the Obligations have been paid and performed in full.

(f)Certain Proceeds. Notwithstanding any contrary provision herein, any and all

(i)dividends, interest, or other distributions paid or payable other than in cash in respect of, and instruments and other property received, receivable, or otherwise distributed in respect of, or in exchange for, any Collateral;

(ii)dividends, interest, or other distributions hereafter paid or payable in cash in respect of any Collateral in connection with a partial or total liquidation or dissolution, or in connection with a reduction of capital, capital surplus, or paid-in-surplus;

(iii)cash paid, payable, or otherwise distributed in redemption of, or in exchange for, any Collateral; and

(iv)dividends, interest, or other distributions paid or payable in violation of the Loan Documents,

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shall be part of the Collateral hereunder, and shall, if received by Debtor, be held in trust for the benefit of Secured Party, and shall forthwith be delivered to Secured Party (accompanied by proper instruments of assignment and/or stock and/or bond powers executed by Debtor in accordance with Secured Party’s instructions) to be held subject to the terms of this Security Agreement. Any cash proceeds of Collateral which come into the possession of Secured Party on and after the occurrence of an Event of Default (including, without limitation, insurance proceeds) may, at Secured Party’s option, be applied in whole or in part to the Obligations (to the extent then due), be released in whole or in part to or on the written instructions of Debtor for any general or specific purpose, or be retained in whole or in part by Secured Party as additional Collateral. Any cash Collateral in the possession of Secured Party may be invested by Secured Party in certificates of deposit issued by Secured Party (if Secured Party issues such certificates) or by any state or national bank having combined capital and surplus greater than $100,000,000 with a rating from Moody’s and S&P of P-1 and A-1+, respectively, or in securities issued or guaranteed by the United States of America or any agency thereof Secured Party shall never be obligated to make any such investment and shall never have any liability to Debtor for any loss which may result therefrom. All interest and other amounts earned from any investment of Collateral may be dealt with by Secured Party in the same manner as other cash Collateral. The provisions of this subparagraph are applicable whether or not a Default or Event of Default exists.

(g)Use and Operation of Collateral. Should any Collateral come into the possession of Secured Party, Secured Party may use or operate such Collateral for the purpose of preserving it or its value pursuant to the order of a court of appropriate jurisdiction or in accordance with any other Rights held by Secured Party in respect of such Collateral. Debtor covenants to promptly reimburse and pay to Secured Party, at Secured Party’s request, the amount of all reasonable expenses (including, without limitation, the cost of any insurance and payment of Taxes or other charges) incurred by Secured Party in connection with its custody and preservation of Collateral, and all such expenses, costs, Taxes, and other charges shall bear interest at the Default Rate until repaid and, together with such interest, shall be payable by Debtor to Secured Party upon demand and shall become part of the Obligations. However, the risk of accidental loss or damage to, or diminution in value of, Collateral is on Debtor, and Secured Party shall have no liability whatever for failure to obtain or maintain insurance, nor to determine whether any insurance ever in force is adequate as to amount or as to the risks insured. With respect to Collateral that is in the possession of Secured Party, Secured Party shall have no duty to fix or preserve Rights against prior parties to such Collateral and shall never be liable for any failure to use diligence to collect any amount payable in respect of such Collateral, but shall be liable only to account to Debtor for what it may actually collect or receive thereon. The provisions of this subparagraph are applicable whether or not an Event of Default exists.

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(h)Cash Collateral Account. If an Event of Default exists and is continuing, Secured Party shall have, and Debtor hereby grants to Secured Party, the Right and authority to transfer all funds on deposit in the Deposit Accounts to a Cash Collateral Account (herein so called) maintained with a depository institution acceptable to Secured Party and subject to the exclusive direction, domain, and control of Secured Party, and no disbursements or withdrawals shall be permitted to be made by Debtor from such Cash Collateral Account. Such Cash Collateral Account shall be subject to the Security Interest and Liens in favor of Secured Party herein created, and Debtor hereby grants a security interest to Secured Party on behalf of Lenders in and to, such Cash Collateral Account and all checks, drafts, and other items ever received by Debtor for deposit therein. Furthermore, if an Event of Default exists, Secured Party shall have the Right, at any time in its discretion without notice to Debtor, (i) to transfer to or to register in the name of Secured Party or any Lender or nominee any certificates of deposit or deposit instruments constituting Deposit Accounts and shall have the Right to exchange such certificates or instruments representing Deposit Accounts for certificates or instruments of smaller or larger denominations and (ii) to take and apply against the Obligations any and all funds then or thereafter on deposit in the Cash Collateral Account or otherwise constituting Deposit Accounts.

(i)Power of Attorney. Debtor hereby irrevocably constitutes and appoints Secured Party and any officer or agent thereof, with full power of substitution, as its true and lawful attorney-in-fact with full irrevocable power and authority in the name of Debtor or in its own name, to take after the occurrence and during the continuance of an Event of Default and from time to time thereafter, any and all action and to execute any and all documents and instruments which Secured Party at any time and from time to time deems necessary or desirable to accomplish the purposes of this Security Agreement and, without limiting the generality of the foregoing, Debtor hereby gives Secured Party the power and Right on behalf of Debtor and in its own name to do any of the following after the occurrence and during the continuance of an Event of Default and from time to time thereafter, without notice to or the consent of Debtor:

(i)to transfer any and all funds on deposit in the Deposit Accounts to the Cash Collateral Account as set forth in herein;

(ii)to receive, endorse, and collect any drafts or other instruments or documents in connection with clause (b) above and this clause (i);

(iii)to use the Intellectual Property or to grant or issue any exclusive (if Debtor has exclusive rights to such Intellectual Property) or non-exclusive license under the Intellectual Property to anyone else, and to perform any act necessary

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for the Secured Party to assign, pledge, convey, or otherwise transfer title in or dispose of the Intellectual Property to any other Person;

(iv)to demand, sue for, collect, or receive, in the name of Debtor or in its own name, any money or property at any time payable or receivable on account of or in exchange for any of the Collateral and, in connection therewith, endorse checks, notes, drafts, acceptances, money orders, documents of title or any other instruments for the payment of money under the Collateral or any policy of insurance;

(v)to pay or discharge taxes, Liens, or other encumbrances levied or placed on or threatened against the Collateral;

(vi)to notify post office authorities to change the address for delivery of Debtor to an address designated by Secured Party and to receive, open, and dispose of mail addressed to Debtor; and

(vii)(A) to direct account debtors and any other parties liable for any payment under any of the Collateral to make payment of any and all monies due and to become due thereunder directly to Secured Party or as Secured Party shall direct; (B) to receive payment of and receipt for any and all monies, claims, and other amounts due and to become due at any time in respect of or arising out of any Collateral; (C) to sign and endorse any invoices, freight or express bills, bills of lading, storage or warehouse receipts, drafts against debtors, assignments, proxies, stock powers, verifications, and notices in connection with accounts and other documents relating to the Collateral; (D) to commence and prosecute any suit,  action, or proceeding at Law or in equity in any court of competent jurisdiction to collect the Collateral or any part thereof and to enforce any other Right in respect of any Collateral; (E) to defend any suit, action, or proceeding brought against Debtor with respect to any Collateral; (F) to settle, compromise, or adjust any suit, action, or proceeding described above and, in connection therewith, to give such discharges or releases as Secured Party may deem appropriate; (G) to exchange any of the Collateral for other property upon any merger, consolidation, reorganization, recapitalization, or other readjustment of the issuer thereof and, in connection therewith, deposit any of the Collateral with any committee, depositary, transfer agent, registrar, or other designated agency upon such ten-ns as Secured Party may determine; (H) to add or release any guarantor, endorser, surety, or other party to any of the Collateral; (1) to renew, extend, or otherwise change the terms and conditions of any of the Collateral; (J) to endorse Debtor’s name on all applications, documents, papers, and instruments necessary or desirable in order for Secured Party to use or maintain any of the

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Intellectual Property; (K) to make, settle, compromise or adjust any claims under or pertaining to any of the Collateral (including claims under any policy of insurance); (L) to execute on behalf of Debtor any financing statements or continuation statements with respect to the Security Interests created hereby, and to do any and all acts and things to protect and preserve the Collateral, including, without limitation, the protection and prosecution of all Rights included in the Collateral; and (M) to sell, transfer, pledge, convey, make any agreement with respect to or otherwise deal with any of the Collateral as fully and completely as though Secured Party were the absolute owner thereof for all purposes, and to do, at Secured Parry’s option and Debtor’s expense, at any time, or from time to time, all acts and things which Secured Party deems necessary to protect, preserve, maintain, or realize upon the Collateral and Secured Party’s security interest therein.

This power of attorney is a power coupled with an interest and shall be irrevocable. Secured Party shall be under no duty to exercise or withhold the exercise of any of the Rights, powers, privileges, and options expressly or implicitly granted to Secured Party in this Security Agreement, and shall not be liable for any failure to do so or any delay in doing so. Neither Secured Party nor any Person designated by Secured Party shall be liable for any act or omission or for any error of judgment or any mistake of fact or Law. This power of attorney is conferred on Secured Party solely to protect, preserve, maintain, and realize upon its Security Interest in the Collateral. Secured Party shall not be responsible for any decline in the value of the Collateral and shall not be required to take any steps to preserve rights against prior parties or to protect, preserve, or maintain any Lien given to secure the Collateral.

(j)Purchase Money Collateral. To the extent that Secured Party or any Lender has advanced or will advance funds to or for the account of Debtor to enable Debtor to purchase or otherwise acquire Rights in Collateral, Secured Party or such Lender, at its option, may pay such funds (i) directly to the Person from whom Debtor will make such purchase or acquire such Rights, or (ii) to Debtor, in which case Debtor covenants to promptly pay the same to such Person, and forthwith furnish to Secured Party evidence satisfactory to Secured Party that such payment has been made from the funds so provided.

(k)Subrogation. If any of the Obligations are given in renewal or extension or applied toward the payment of indebtedness secured by any Lien, Secured Party shall be, and is hereby, subrogated to all of the Rights, titles, interests, and Liens securing the indebtedness so renewed, extended, or paid.

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(1)Indemnification. Debtor hereby assumes all liability for the Collateral, for the Security Interest, and for any use, possession, maintenance, and management of, all or any of the Collateral, including, without limitation, any Taxes arising as a result of, or in connection with, the transactions contemplated herein, and agrees to assume liability for, and to indemnify and hold Secured Party and each Lender harmless from and against, any and all claims, causes of action, or liability, for injuries to or deaths of Persons and damage to property, howsoever arising from or incident to such use, possession, maintenance, and management, whether such Persons be agents or employees of Debtor or of third parties, or such damage be to property of Debtor or of others. Debtor agrees to indemnify, save, and hold Secured Party and each Lender harmless from and against, and covenants to defend Secured Party and each Lender against, any and all losses, damages, claims, costs, penalties, liabilities, and expenses (collectively, “Claims”), including, without limitation, court costs and attorneys’ fees, and any of the foregoing arising from the negligence of Secured Party or any Lender, or any of their respective officers, employees, agents, advisors, employees, or representatives, howsoever arising or incurred because of, incident to, or with respect to Collateral or any use, possession, maintenance, or management thereof; provided however, that the indemnity set forth in this Paragraph 8(t) will not apply to Claims caused by the gross negligence or willful misconduct of Secured Party or any Lender.

9.MISCELLANEOUS.

(a)Continuing Security Interest. This Security Agreement creates a continuing security interest in the Collateral and shall (i) remain in full force and effect until the termination of the obligations of Lenders to make Credit Extensions under the Loan Documents and the payment in full of the Obligations; and (ii) inure to the benefit of and be enforceable by Secured Party, Lenders, and their respective successors, transferees, and assigns. Without limiting the generality of the foregoing clause (ii), Secured Party and Lenders may assign or otherwise transfer any of their respective Rights under this Security Agreement to any other Person in accordance with the terms and provisions of Section 10.07 of the Credit Agreement, and to the extent of such assignment or transfer such Person shall thereupon become vested with all the Rights and benefits in respect thereof granted herein or otherwise to Secured Party or Lenders, as the case may be. Upon payment in full of the Obligations, Debtor shall be entitled to the return, upon its request and at its expense, of such of the Collateral as shall not have been sold or otherwise applied pursuant to the terms hereof.

(b)Reference to Miscellaneous Provisions. This Security Agreement is one of the “Loan Documents” referred to in the Credit Agreement, and all provisions relating to Loan Documents set forth in Article X of the Credit Agreement are incorporated herein by reference, the same as if set forth herein verbatim.

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(c)Term; Release of Liens. Upon the later of (i) the termination of Lenders’ commitments to fund Borrowing under the Credit Agreement, and (ii) the full and final payment and performance of the Obligations, the Administrative Agent shall release the liens created by this Security Agreement in accordance with Section 10.01(d) of the Credit Agreement; provided that no Obligor, if any, on any of the Collateral shall ever be obligated to make inquiry as to the termination of this Security Agreement, but shall be fully protected in making payment directly to Secured Party until actual notice of such total payment of the Obligations is received by such Obligor. At such time as the Liens created by this Security Agreement are to be released pursuant to this paragraph, Secured Party shall, at the request and expense of the Debtor following such termination, promptly deliver to the Debtor any Collateral held by the Secured Party hereunder, and promptly execute and deliver to such Debtor such documents and instruments as the Debtor shall reasonably request to evidence such termination and release as provided in the Credit Agreement. In addition, if any of the Collateral shall be sold, transferred, assigned or otherwise disposed of by the Debtor in a transaction permitted by the Credit Agreement, then the Secured Party, at the request and expense of the Debtor, shall promptly execute and deliver releases as provided in the Credit Agreement.

(d)Actions Not Releases. The Security Interest and Debtor’s obligations and Secured Party’s Rights hereunder shall not be released, diminished, impaired, or adversely affected by the occurrence of any one or more of the following events: (i) the taking or accepting of any other security or assurance for any or all of the Obligations; (ii) any release, surrender, exchange, subordination, or loss of any security or assurance at any time existing in connection with any or all of the Obligations; (iii) the modification of, amendment to, or waiver of compliance with any terms of any of the other Loan Documents without the notification or consent of Debtor, except as required therein (the Right to such notification or consent being herein specifically waived by Debtor); (iv) the insolvency, bankruptcy, or lack of corporate or trust power of any party at any time liable for the payment of any or all of the Obligations, whether now existing or hereafter occurring; (v) any renewal, extension, or rearrangement of the payment of any or all of the Obligations, either with or without notice to or consent of debtor, or any adjustment, indulgence, forbearance, or compromise that may be granted or given by Secured Party or any Lender to Debtor; (vi) any neglect delay, omission, failure, or refusal of Secured Party or any Lender to take or prosecute any action in connection with any other agreement, document, guaranty, or instrument evidencing, securing, or assuring the payment of all or any of the Obligations; (vii) any failure of Secured Party or any Lender to notify Debtor of any renewal, extension, or assignment of the Obligations or any part thereof, or the release of any Collateral or other security, or of any other action taken or refrained from being taken by Secured Party or any Lender against Debtor or any new agreement between or among Secured Party or one or more Lenders and Debtor, it being understood that except as expressly provided herein, neither Secured Party nor any

31

Lender shall be required to give Debtor any notice of any kind under any circumstances whatsoever with respect to or in connection with the Obligations, including, without limitation, notice of acceptance of this Security Agreement or any Collateral ever delivered to or for the account of Secured Party hereunder; (viii) the illegality, invalidity, or unenforceability of all or any part of the Obligations against any party obligated with respect thereto by reason of the fact that the Obligations, or the interest paid or payable with respect thereto, exceeds the amount permitted by Law, the act of creating the Obligations, or any part thereof, is ultra vires, or the officers, partners, or trustees creating same acted in excess of their authority, or for any other reason; or (ix) if any payment by any party obligated with respect thereto is held to constitute a preference under applicable Laws or for any other reason Secured Party or any Lender is required to refund such payment or pay the amount thereof to someone else,

(e)Waivers. Except to the extent expressly otherwise provided herein or in other Loan Documents and to the fullest extent permitted by applicable Law, Debtor waives (i) any Right to require Secured Party or any Lender to proceed against any other Person, to exhaust its Rights in Collateral, or to pursue any other Right which Secured Party or any Lender may have; (ii) with respect to the Obligations, presentment and demand for payment, protest, notice of protest and nonpayment, and notice of the intention to accelerate; and (iii) all Rights of marshaling in respect of any and all of the Collateral.

(f)Financing Statement; Authorization. Secured Party shall be entitled at any time to file this Security Agreement or a carbon, photographic, or other reproduction of this Security Agreement, as a financing statement, but the failure of Secured Party to do so shall not impair the validity or enforceability of this Security Agreement. Debtor hereby irrevocably authorizes Secured Party at any time and from time to time to file in any UCC jurisdiction any initial or other financing statements and amendments thereto (without the requirement for Debtor’s signature thereon) that (i) indicate the Collateral (A) as “all assets of Debtor” or words of similar effect, regardless of whether any particular asset comprised in the Collateral falls within the scope of Article 9 of the UCC of the state or such jurisdiction or whether such assets are included in the Collateral hereunder, or (B) as being of an equal or lesser scope or with greater detail, and (ii) contain any other information required by Article 9 of the UCC of the state or such jurisdiction for the sufficiency or filing office acceptance of any financing statement or amendment, including (A) whether the Debtor is an organization, the type of organization, and any organization identification number issued to Debtor and, (B) in the case of a financing statement filed as a fixture filing or indicating Collateral as-extracted collateral or timber to be cut, a sufficient description of real property to which the Collateral relates. Debtor agrees to furnish any such information to Secured Party promptly upon request.

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(g)Amendments. This Security Agreement may be amended only by an instrument in writing executed jointly by Debtor and Secured Party, and supplemented only by documents delivered or to be delivered in accordance with the express terms hereof.

(h)Multiple Counterparts. This Security Agreement has been executed in a number of identical counterparts, each of which shall be deemed an original for all purposes and all of which constitute, collectively, one agreement; but, in making proof of this Security Agreement, it shall not be necessary to produce or account for more than one such counterpart.

(i)Parties Bound; Assignment. This Security Agreement shall be binding on Debtor and Debtor’s heirs, legal representatives, successors, and assigns and shall inure to the benefit of Secured Party and Secured Party’s successors and assigns.

(i)Secured Party is the agent for each Lender under the NMP Credit Agreement, the Security Interest and all Rights granted to Secured Party hereunder or in connection herewith are for the ratable benefit of each Lender, and Secured Party may, without the joinder of any Lender, exercise any and all Rights in favor of Secured Party or Lenders hereunder, including, without limitation, conducting any foreclosure sales hereunder, and executing full or partial releases hereof, amendments or modifications hereto, or consents or waivers hereunder. The Rights of each Lender vis-a-vis Secured Party and each other Lender may be subject to one or more separate agreements between or among such parties, but Debtor need not inquire about any such agreement or be subject to any terms thereof unless Debtor specifically joins therein; and consequently, neither Debtor nor Debtor’s heirs, personal representatives, successors, and assigns shall be entitled to any benefits or provisions of any such separate agreements or be entitled to rely upon or raise as a defense, in any manner whatsoever, the failure or refusal of any party thereto to comply with the provisions thereof.

(ii)Debtor may not, without the prior written consent of Secured Party, assign any Rights, duties, or obligations hereunder.

(j)GOVERNING LAW. THE SUBSTANTIVE LAWS OF THE STATE OF TEXAS, EXCEPT TO THE EXTENT THE LAWS OF ANOTHER JURISDICTION GOVERN THE CREATION, PERFECTION, VALIDITY, OR ENFORCEMENT OF LIENS UNDER THIS SECURITY AGREEMENT, AND THE APPLICABLE FEDERAL LAWS OF THE UNITED STATES OF AMERICA, SHALL GOVERN THE VALIDITY, CONSTRUCTION, ENFORCEMENT AND

33

INTERPRETATION OF THIS SECURITY AGREEMENT AND ALL OF THE OTHER LOAN DOCUMENTS.

(k)The provisions of Section 10.10 of the Credit Agreement are incorporated herein as if set forth herein.

(1)All notices given pursuant hereto shall be given in the manner set forth in the Credit Agreement, if to Secured Party, to the address of Secured Party therein set forth and if to Debtor, to the following address:

155 Inverness Drive West, Suite 200

Englewood, Colorado 80112-5000

Attn: Contract Administrator

Facsimile: (303) 290-8769

Telephone: (303) 290-8700

THIS AGREEMENT AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

Remainder of page Intentionally Blank

Signature Page to Follow.

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IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be duly executed and delivered by an officer duly authorized as of the date first above written.

MARKWEST WESTERN OKLAHOMA GAS COMPANY, L.L.C.,
an Oklahoma limited liability company
By:	MarkWest Energy Operating Company, L.L.C.,
	its Managing Member
	By:		MarkWest Energy Partners, L.P.,
			its sole Member
		By:		MarkWest Energy GP, L.L.C.,
				its General Partner
					By:
						Andrew L. Schroeder
						Vice President and Treasurer

35

ANNEX A TO SECURITY AGREEMENT

DEBTOR INFORMATION AND LOCATION OF COLLATERAL

A.	Exact Legal Name of Debtor:
B.	Mailing Address of Debtor:		155 Inverness Drive West
			Suite 200
			Englewood, Colorado 80112
C.	Type of Entity:	Limited Liability Company
D.	Jurisdiction of Organization:
E.	State Issued Organizational Identification Number:
F.	Tax ID Number:
G.	Location of Books and Records:			155 Inverness Drive West
				Suite 200
				Englewood, Colorado 80112
H.	Location of Collateral:
I.	Location of Real Property:
J.	Jurisdiction(s) for Filing Financing Statements:
	Fixture filings in the relevant counties in which the properties are located:

36

ANNEX B-1 TO SECURITY AGREEMENT

COLLATERAL DESCRIPTIONS

A.Collateral Notes and Collateral Note Security:

B.Pledged Shares

C.Partnership/Limited Liability Company Interests

D.Agreements

E.Commercial Tort Claims

F.Deposit Accounts (including name of bank address and account number).

37

ANNEX B-2 TO SECURITY AGREEMENT

INTELLECTUAL PROPERTY

1.Registered Copyrights and Copyright Applications

2.Issued Patents and Patent Applications

3.Registered Trademarks and Trademark Applications

38

ANNEX C TO SECURITY AGREEMENT

DEPOSIT ACCOUNT CONTROL AGREEMENT

                   , 20   

Ladies and Gentlemen:

This letter is to notify you (the “Depository Bank”)that, pursuant to that certain Pledge and Security Agreement dated as of                , 2003 (as amended, modified, supplemented., or restated from time to time, the “Security Agreement”),                                    , a company organized under the laws of                 (the “Pledgor”),has granted to Royal Bank of Canada as Administrative Agent (“Pledgee”) a first priority security interest in and lien upon, (a) Account No.                 (the “Account”)maintained by Pledgor with you, (b) any extensions or renewals of the Account if the Account is one which may be extended or renewed, and (c) all of Pledgor’s right, title, and interest (whether now existing or hereafter created or arising) in and to the Account, all sums from time to time on deposit therein, credited thereto, or payable thereon, all instruments, documents, certificates, and other writings evidencing the Account, and any and all proceeds of any thereof (the items described in clauses (a), (b) and (c) being herein collectively called the “Collateral”),

In connection therewith, the parties hereto agree (which agreement by Pledgor will be construed as instructions to the Depository Bank):

1.The Depository Bank is instructed to register the pledge on its books and hold the Collateral in a pledged status account.

2.The Depository Bank is instructed to deliver to Pledgee copies of monthly statements on the account(s) identified below:

3.The Account will be styled:

4.All dividends, interest, gains, and other profits on the Collateral will be reported in the name and tax identification number of Pledgor.

5.If so notified by Pledgee, the Depository Bank will not, without the prior written consent of Pledgee, allow any of the Collateral or any interest therein to be sold, transferred, or withdrawn by or for the benefit of Pledgor.

39

6.This letter agreement gives Pledgee “control” of the Account and the Collateral. The Depository Bank agrees to comply with any order or instruction from Pledgee as to the withdrawal or disposition of any funds from time to time credited to the Account, or as to any other matters relating to the Collateral, without the further consent of Pledgor. The Depository Bank shall be fully entitled to rely upon such instructions from Pledgee even if such instructions are contrary to any instructions or demands that Pledgor may give to the Depository Bank.

7.Pledgee agrees to indemnify and hold the Depository Bank, its officers and employees, harmless from and against any and all claims, causes of action, liabilities, lawsuits, demands, and/or damages, including, without limitation any and all costs, including court costs and reasonable attorneys’ fees, that may arise or result from the Depository Bank complying with the instructions and orders of Pledgee given in connection with Pledgee’s exercise of its control over and secured rights in the Account and the Collateral except to the extent that such claims, causes of action, liabilities, lawsuits, demands, and/or damages are found in a final, non-appealable judgment by a court of competent jurisdiction to have resulted from the gross negligence or willful misconduct of the Depository Bank.

8.Pledgor agrees to indemnify and hold the Depository Bank, its officers and employees, harmless from and against any and all claims, causes of action, liabilities, lawsuits, demands, and/or damages, including, without limitation, any and all costs, including court costs and reasonable attorneys’ fees, that may arise or result from the Depository Bank entering into and performing its obligations under this letter agreement except to the extent that such claims, causes of action, liabilities, lawsuits, demands, and/or damages are found in a final, non-appealable judgment by a court of competent jurisdiction to have resulted from the gross negligence or willful misconduct of the Depository Bank.

9.The Depository Bank represents that it has not received notice regarding any lien, encumbrance, or other claim to the Account or the Collateral from any person other than pursuant to this letter agreement and has not entered into another agreement with any other party to act on such party’s instructions with respect to the Account. The Depository Bank further agrees not to enter into any such agreement with any other party.

10.The Depository Bank subordinates’ to the security interest of Pledgee any right of recoupment or set-off, or to assert any security interest or other lien, that it may at any time have against or in any of the Collateral on account of any credit or other obligations owed to the Depository Bank by Pledgor or any other person. The Depository Bank may, however, from time to time debit the Account for any of its customary charges in maintaining the Account or for reimbursement for the reversal of any provisional credits

40

granted by the Depository Bank to the Account, to the extent, in each case, that Pledgor has not separately paid or reimbursed Depository Bank therefor.

11.To the extent a conflict exists between the terms of this letter agreement and any account agreement between Pledgor and the Depository Bank, the terms of this letter agreement will control.

12.The terms of this letter agreement will in no way be modified except by a writing signed by all parties hereto.

13.Each of the parties executing this letter agreement represents that he has the proper authority to execute this letter agreement.

[Remainder of page intentionally blank Signature page follows.]

41

IN WITNESS WHEREOF, Pledgor and Pledgee have agreed to the terms of this letter agreement as of the date first indicated above.

Pledgor:
[NAME OF ENTITY]
By:
	Name:
	Title:
Pledgee:
ROYAL BANK OF CANADA,
as Administrative Agent
By:
	Name:
	Title:
Acknowledged and Agreed on                       , 200  :
Depository Bank:
[NAME OF ENTITY]
By:
	Name:
	Title:

42

ANNEX D TO SECURITY AGREEMENT

ACKNOWLEDGMENT OF PLEDGE

PARTNERSHIP/LIMITED LIABILITY COMPANY:                                                       

INTEREST OWNER:                                                      

BY THIS ACKNOWLEDGMENT OF PLEDGE, dated as of                             , 2003,                                                (the “Partnership/Limited Liability Company”) hereby acknowledges the pledge in favor of Royal Bank of Canada (“Pledgee”), in its capacity as Administrative Agent for certain Lenders and as Secured Party under that certain Pledge and Security Agreement dated as of                    ,  2003 (as amended, modified, supplemented, or restated from time to time, the “Security Agreement”), against, and a security interest in favor of Pledgee in, all of                                               ’s (the “Interest Owner”)Rights in connection with any partnership interest in the Partnership/Limited Liability Company now and hereafter owned by the Interest Owner (“Partnership/Limited Liability Company Interest”).

A.Pledge Records. The Partnership/Limited Liability Company has identified Pledgee’s interest in all of the Interest Owner’s Right, title, and interest in and to all of the Interest Owner’s Partnership/Limited Liability Company Interest es subject to a pledge and security interest in favor of Pledgee in the Partnership/Limited Liability Company Records.

B.Partnership/Limited Liability Company Distributions, Accounts, and Correspondence. The Partnership/Limited Liability Company hereby acknowledges that (i) all proceeds, distributions, and other amounts payable to the Interest Owner, including, without limitation, upon the termination, liquidation, and dissolution of the Partnership/Limited Liability Company shall be paid and remitted to the Pledgee upon demand, (ii) all funds in deposit accounts shall be held for the benefit of Pledgee, and (iii) all future correspondence, accountings of distributions, and tax returns of the Partnership/Limited Liability Company shall be provided to the Pledgee. The Partnership/Limited Liability Company acknowledges and accepts such direction and hereby agrees that it shall, upon the written demand by the Administrative Agent, pay directly to the Administrative Agent at its offices at 901 Main Street, 14th Floor, Dallas, Texas 75202 any and all distributions, income, and cash flow arising from the Partnership/Limited Liability Company Interests whether payable in cash, property or otherwise, subject to and in accordance with the terms and conditions of the Partnership/Limited Liability Company. The Pledgee may from time to time notify the Partnership/Limited Liability Company of any change of address to which such amounts are to be paid.

Remainder of Page Intentionally Blank.

Signature Page to Follow.

43

EXECUTED as of the date first stated in this Acknowledgment of Pledge.

By:
Name:
Title:
[PARTNERSHIP/LIMITED LIABILITY COMPANY]
By:
	as [General Partner] [Manager]
By:
	Name:
	Title:

44

ANNEX E TO SECURITY AGREEMENT

MATERIAL CONTRACTS

45

EX-99.2

Exhibit 99.2

FIRST AMENDMENT TO
SECOND AMENDED AND RESTATED CREDIT AGREEMENT

THIS FIRST AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT (this “Amendment”) is entered into as of August 20, 2004, among MARKWEST ENERGY OPERATING COMPANY, L.L.C., a Delaware limited liability company, as borrower (the “Borrower”), MARKWEST ENERGY PARTNERS, L.P., a Delaware limited partnership (the “MLP”), the undersigned Guarantors (collectively, the “Guarantors”), ROYAL BANK OF CANADA, as Administrative Agent for the Lenders parties to the hereinafter defined Credit Agreement (in such capacity, the “Administrative Agent”), FORTIS CAPITAL CORP., as syndication agent (in such capacity, the “Syndication Agent”), BANK ONE, NA and SOCIETE GENERALE, each as documentation agent (collectively in such capacity, the “Document Agents”), and the undersigned Lenders.

Reference is made to the Second Amended and Restated Credit Agreement dated as of July 30, 2004 among Borrower, the MLP, the Administrative Agent, the Syndication Agent, the Documentation Agents and the Lenders parties thereto (as amended, the “Credit Agreement”).  Unless otherwise defined in this Amendment, capitalized terms used herein shall have the meaning set forth in the Credit Agreement; all section and schedule references herein are to sections and schedules in the Credit Agreement; and all paragraph references herein are to paragraphs in this Amendment.

RECITALS

A.The Borrower has requested certain amendments to the Credit Agreement.

B.Subject to the terms and conditions of this Amendment, the Administrative Agent and the other Lenders are willing to agree to such amendments.

Accordingly, for adequate and sufficient consideration, the parties hereto agree, as follows:

Paragraph 1.Amendments. Effective as of the First Amendment Effective Date, the Credit Agreement is amended as follows:

1.1Definitions. Section 1.01 is amended as follows:

(a)Each of the following definitions is amended in its entirety to read as follows:

“Agreement means this Credit Agreement as amended by the First Amendment to Credit Agreement.”

“Permitted Acquisition means the ACET Acquisition and any other Acquisition by the Borrower or a Subsidiary of the Borrower resulting in ownership of assets inside the United States, or of equity interests in a Domestic

Person; provided, however, the purchase price for any Acquisition shall not, when aggregated with all other Permitted Acquisitions (excluding the ACET Acquisition) exceed $10,000,000 (or $25,000,000 after repayment of the Term Loans); and provided, further that the following requirements have been satisfied:

(i)if such Acquisition results in the Borrower’s ownership of a Subsidiary, the Borrower shall have complied with the requirements of Sections 6.15 and 6.16 as of the date of such Acquisition;

(ii)with respect to Acquisitions involving acquisitions of an equity interest, such Acquisition shall have been approved or consented to by the board of directors or similar governing entity of the Person being acquired; and

(iii)as of the closing of such Acquisition no Default or Event of Default shall exist or occur as a result of, and after giving effect to, such Acquisition.”

(b)The following definitions are inserted alphabetically into Section 1.1:

“First Amendment Effective Date means the date the First Amendment to Credit Agreement by its terms becomes effective among the parties thereto.”

“First Amendment to Credit Agreement means that certain First Amendment to Credit Agreement dated as of August 20, 2004, among the Borrower, the MLP, the Guarantors, Royal Bank of Canada, as Administrative Agent, Fortis Capital Corp., as Syndication Agent, Bank One, NA and Societe Generale, as Documentation Agents, and the Lenders.”

1.2Section 2.04(b).  Section 2.04(b) is hereby amended to read in its entirety as follows:

“(b)Mandatory Prepayments from Net Cash Proceeds.

(i)Subject to the proviso set forth in subsection (iv)(D) below, if any Net Cash Proceeds are received by a Company from any Disposition (including any deferred purchase price therefor and including sales of stock or other equity interests of Subsidiaries but excluding any Disposition permitted by Section 7.07(a) or (b)), the Aggregate Commitments shall be permanently reduced, and the Loans shall be prepaid, immediately upon receipt of such Net Cash Proceeds, in an amount equal to the amount of Net Cash Proceeds received from such Disposition.

(ii)Subject to the proviso set forth in subsection (iv)(D) below, if any Net Cash Proceeds are received by the MLP from an MLP Offering, the Loans shall be prepaid by the Borrower immediately after receipt of such Net Cash Proceeds by the MLP, in an amount equal to the amount of Net Cash Proceeds received by the MLP from such MLP Offering.

(iii)If any Net Cash Proceeds are received from the issuance or incurrence of Refinancing Indebtedness by a Company, the Aggregate Commitments shall be permanently reduced, and the Loans shall be prepaid, immediately upon receipt of such Net Cash Proceeds, in an amount equal to the amount of Net Cash Proceeds received from such Refinancing Indebtedness.

(iv)The prepayments and commitment reductions provided for in this Section 2.04(b) shall be applied as follows, unless a Default or Event of Default has occurred and is continuing or would arise as a result thereof (whereupon the provisions of Section 2.11(d) shall apply): (A) first, to repay any outstanding fees, costs or expenses owing to Administrative Agent or any Lender, including Attorney Costs, (B) second, as a payment of all Unreimbursed Amounts then outstanding, until paid in full, (C), third, as a repayment of the Term Loan Principal Debt, until paid in full, with a corresponding reduction in the Aggregate Term Loan Commitments and (D) fourth, as a repayment of the Revolver Principal Debt, until paid in full, with a corresponding reduction in the Aggregate Revolver Commitments, or if a Default or Event of Default exists, as specified by the Agents or the Required Banks; provided, however, any Net Cash Proceeds received by the MLP from an MLP Offering or by the Borrower from any Disposition in excess of $50,000,000, up to a  maximum of $75,000,000, will, after repayment of the Term Loans, be applied against the Revolver Principal Debt without a corresponding reduction in the Aggregate Revolver Commitments (but any Net Cash Proceeds in excess of $75,000,000 will be applied against the Revolver Principal Debt with a corresponding reduction in the Aggregate Revolver Commitments).

Paragraph 2.Effective Date. This Amendment shall not become effective until the date (such date, the “First Amendment Effective Date”) the Administrative Agent receives all of the agreements, documents, certificates, instruments, and other items described below:

(a)this Amendment, executed by the Borrower, the Guarantors, and each other Lender;

(b)from the Borrower and the existing Guarantors, such certificates of secretary, assistant secretary, manager, or general partner, as applicable, as the Administrative Agent may require, certifying (i) resolutions of its board of directors, managers or members (or their equivalent) authorizing the execution and performance of this Amendment and the other Loan Documents which such Person is executing in connection herewith, (ii) the incumbency and signature of the officer executing such documents, and (iii) no change in such Person’s organizational documents since July 30, 2004;

(c)fees and expenses required to be paid pursuant to Paragraph 5 of this Amendment, to the extent invoiced prior to the First Amendment Effective Date; and

(d)such other assurances, certificates, documents and consents as the Administrative Agent may require.

Paragraph 3.Acknowledgment and Ratification. As a material inducement to the Administrative Agent and the Lenders to execute and deliver this Amendment, each of the

Borrower and the Guarantors (i) consents to the agreements in this Amendment, (ii) agrees and acknowledges that the execution, delivery, and performance of this Amendment shall in no way release, diminish, impair, reduce, or otherwise affect the respective obligations of the Borrower or any Guarantor under the Loan Documents to which it is a party, which Loan Documents shall remain in full force and effect, and all rights thereunder are hereby ratified and confirmed.

Paragraph 4.Representations. As a material inducement to the Administrative Agent and the Lenders to execute and deliver this Amendment, each of the Borrower and the Guarantors represents and warrants to the Administrative Agent and the Lenders that as of the First Amendment Effective Date and as of the date of execution of this Amendment, (a) all representations and warranties in the Loan Documents are true and correct in all material respects as though made on the date hereof, except to the extent that any of them speak to a different specific date, and (b) no Default or Event of Default exists.

Paragraph 5.Expenses, Funding Losses.  The Borrower shall pay on demand all reasonable costs, fees, and expenses paid or incurred by the Administrative Agent incident to this Amendment, including, without limitation, Attorney Costs in connection with the negotiation, preparation, delivery, and execution of this Amendment and any related documents, filing and recording costs, and the costs of title insurance endorsements.

Paragraph 6.Miscellaneous. This Amendment is a “Loan Document “ referred to in the Credit Agreement.  The provisions relating to Loan Documents in Article X of the Credit Agreement are incorporated in this Amendment by reference.  Unless stated otherwise (a) the singular number includes the plural and vice versa and words of any gender include each other gender, in each case, as appropriate, (b) headings and captions may not be construed in interpreting provisions, (c) this Amendment must be construed, and its performance enforced, under Texas law and applicable  federal law, (d) if any part of this Amendment is for any reason found to be unenforceable, all other portions of it nevertheless remain enforceable, and (e) this Amendment may be executed in any number of counterparts with the same effect as if all signatories had signed the same document, and all of those counterparts must be construed together to constitute the same document.

Paragraph 7.ENTIRE AGREEMENT. THIS AMENDMENT REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES ABOUT THE SUBJECT MATTER OF THIS AMENDMENT AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

Paragraph 8.Parties. This Amendment binds and inures to the benefit of the Borrower, the Guarantors, the Administrative Agent, the other Lenders, and their respective successors and assigns.

Paragraph 9.Further Assurances. The parties hereto each agree to execute from time to time such further documents as may be necessary to implement the terms of this Agreement.

The parties hereto have executed this Amendment in multiple counterparts to be effective as of the Effective Date.

Remainder of Page Intentionally Blank

Signature Pages to Follow.

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed as of the date first above written.

MARKWEST ENERGY OPERATING COMPANY, L.L.C.,
a Delaware limited liability company, as Borrower
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	Its General Partner
	By:	/s/ Andrew L. Schroeder
			Andrew L. Schroeder
			Vice President
			and Treasurer
MARKWEST ENERGY PARTNERS, L.P.,
a Delaware limited partnership, as a Guarantor
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:	/s/ Andrew L. Schroeder
			Andrew L. Schroeder
			Vice President
			and Treasurer

6

MARKWEST PINNACLE, L.P.,
a Delaware limited partnership, as a Guarantor
MARKWEST PNG UTILITY, L.P.,
a Texas limited partnership, as a Guarantor
MARKWEST TEXAS PNG UTILITY, L.P.,
a Texas limited partnership, as a Guarantor
MARKWEST BLACKHAWK, L.P.,
a Texas limited partnership, as a Guarantor
MARKWEST POWER TEX, L.P.,
a Texas limited partnership, as a Guarantor
MARKWEST NEW MEXICO, L.P.,
a Texas limited partnership, as a Guarantor
MARKWEST ENERGY EAST TEXAS GAS COMPANY, L.P.,
a Delaware limited partnership, as a Guarantor
By:	MarkWest Texas GP, L.L.C.
	its General Partner
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:	/s/ Andrew L. Schroeder
			Andrew L. Schroeder
			Vice President
			and Treasurer

7

BASIN PIPELINE, L.L.C.,
a Michigan limited liability company, as a Guarantor
WEST SHORE PROCESSING, L.L.C.,
a Michigan limited liability company, as a Guarantor
MARKWEST ENERGY APPALACHIA, L.L.C.,
a Delaware limited liability company, as a Guarantor
MARKWEST TEXAS GP, L.L.C.,
a Delaware limited partnership, as a Guarantor
MW TEXAS LIMITED, L.L.C.,
a Delaware limited partnership, as a Guarantor
MARKWEST WESTERN OKLAHOMA
GAS COMPANY, LLC,
an Oklahoma limited liability company, as a Guarantor
MARKWEST MICHIGAN PIPELINE COMPANY, LLC,
a Michigan limited liability company, as a Guarantor
By:	MarkWest Energy Operating Company, L.L.C.,
	its sole Member
By:	MarkWest Energy Partners, L.P.
	its Managing Member
By:	MarkWest Energy GP, L.L.C.,
	its General Partner
	By:	/s/ Andrew L. Schroeder
			Andrew L. Schroeder
			Vice President
			and Treasurer

8

ROYAL BANK OF CANADA,
as Administrative Agent
By:	/s/ Gail Watkin
	Gail Watkin
	Manager Agency
ROYAL BANK OF CANADA, as a Lender
and L/C Issuer
By:	/s/ Jason York
	Jason York
	Authorized Signatory

9

BANK ONE, NA,
as Documentation Agent and Lender
By:	/s/ Jane Bek Keil
	Jane Bek Keil
	Director

10

SOCIETE GENERALE,
as Documentation Agent and Lender
By:	/s/ Francis Sacr
	Francis Sacr
	Managing Director, Project Finance

11

FORTIS CAPITAL CORP.,
as Syndication Agent and as a Lender
By:	/s/ Darrell W. Holley
	Darrell W. Holley
	Managing Director
By:	/s/ Casey Lowary
	Casey Lowary
	Senior Vice President

12

U.S. BANK NATIONAL ASSOCIATION,
as Manager and Lender
By:	/s/ Mark E. Thompson
	Mark E. Thompson
	Vice President

13