Note 5. Property, Plant and Equipment

The historical costs of our property, plant and equipment and related accumulated depreciation balances were as follows at the dates indicated:

	Estimated Useful Life	December 31,
	in Years	2016		2015
Plants, pipelines and facilities (1)	3-45 (5)	$	35,124.6	$	32,525.0
Underground and other storage facilities (2)	5-40 (5)		3,326.9		3,000.5
Transportation equipment (3)	3-10		165.8		159.9
Marine vessels (4)	15-30		800.7		769.8
Land			264.6		262.7
Construction in progress			3,320.7		3,894.0
Total			43,003.3		40,611.9
Less accumulated depreciation			9,710.8		8,577.2
Property, plant and equipment, net		$	33,292.5	$	32,034.7

(1)Plants, pipelines and facilities include processing plants; NGL, natural gas, crude oil and petrochemical and refined products pipelines; terminal loading and unloading facilities; buildings; office furniture and equipment; laboratory and shop equipment and related assets. (2)Underground and other storage facilities include underground product storage caverns; above ground storage tanks; water wells and related assets. (3)Transportation equipment includes tractor-trailer tank trucks and other vehicles and similar assets used in our operations. (4)Marine vessels include tow boats, barges and related equipment used in our marine transportation business. (5)In general, the estimated useful lives of major assets within this category are: processing plants, 20-35 years; pipelines and related equipment, 5-45 years; terminal facilities, 10-35 years; buildings, 20-40 years; office furniture and equipment, 3-20 years; and laboratory and shop equipment, 5-35 years. (6)In general, the estimated useful lives of assets within this category are: underground storage facilities, 5-35 years; storage tanks, 10-40 years; and water wells, 5-35 years.

The following table summarizes our depreciation expense and capitalized interest amounts for the periods indicated:

	For the Year Ended December 31,
	2016		2015		2014
Depreciation expense (1)	$	1,215.7	$	1,161.6	$	1,114.1
Capitalized interest (2)		168.2		149.1		77.9
(1)Depreciation expense is a component of “Costs and expenses” as presented on our Statements of Consolidated Operations. (2)Capitalized interest is a component of “Interest expense” as presented on our Statements of Consolidated Operations.

Fire at Pascagoula Facility

We acquired the remaining 60% undivided interest in the Pascagoula natural gas processing facility (the “Pascagoula Facility”) for $35.0 million in March 2016 and assumed operatorship of the facility on June 1, 2016. The facility is located in Pascagoula, Mississippi and processes natural gas received from third-party production developments located in the northern Gulf of Mexico. On June 27, 2016, we experienced a fire at the facility, which resulted in significant damage to the processing equipment. Repairs to the Pascagoula plant were completed in December 2016 and the facility was returned to commercial service.

As a result of this event, we recorded a $7.1 million non-cash loss in 2016 attributable to assets damaged in the fire. The $7.1 million is a component of operating costs and expenses on our Statements of Consolidated Operations, and a component of asset impairment and related charges on our Statements of Consolidated Cash Flows. We also incurred $10.4 million of expense during 2016 for fire response activities at the Pascagoula Facility.

We capitalized the costs we incurred to replace the damaged equipment and continue to evaluate the possibility of filing an insurance claim related to this event.

Sale of Offshore Business

In July 2015, we completed the sale of our Offshore Business, which primarily consisted of our Offshore Pipelines & Services business segment, to Genesis for approximately $1.53 billion in cash. Our Offshore Business served drilling and development regions, including deepwater production fields, in the northern Gulf of Mexico offshore Alabama, Louisiana, Mississippi and Texas and included approximately 2,350 miles of offshore natural gas and crude oil pipelines and six offshore hub platforms. Our results of operations reflect ownership of the Offshore Business through July 24, 2015.

We viewed our Offshore Business as an extension of our midstream energy services network. As such, the sale of these assets did not represent a strategic shift in our consolidated operations, and their sale did not have a major effect on our financial results. At December 31, 2014, segment assets for our Offshore Pipelines & Services segment represented 4.3% of consolidated total segment assets. Likewise, gross operating margin from this business segment represented only 3.1% of our consolidated total gross operating margin for the year ended December 31, 2014. The sale of this non-strategic business allowed us to redeploy capital to other business opportunities that we believe will generate a higher rate of return for us in the future (e.g., our acquisition of EFS Midstream – see Note 12). Also, proceeds from the closing of this sale reduced our need to issue additional equity and debt to support our capital spending program.

Asset Retirement Obligations

We record AROs in connection with legal requirements to perform specified retirement activities under contractual arrangements and/or governmental regulations. Our contractual AROs primarily result from right-of-way agreements associated with our pipeline operations and real estate leases associated with our plant sites. In addition, we record AROs in connection with governmental regulations associated with the abandonment or retirement of above-ground brine storage pits and certain marine vessels. We also record AROs in connection with regulatory requirements associated with the renovation or demolition of certain assets containing hazardous substances such as asbestos. We typically fund our AROs using cash flow from operations.

Property, plant and equipment at December 31, 2016 and 2015 includes $44.9 million and $17.6 million, respectively, of asset retirement costs capitalized as an increase in the associated long-lived asset.

The following table presents information regarding our AROs for the periods indicated:

	For the Year Ended December 31,
	2016			2015			2014
ARO liability beginning balance	$	58.5		$	98.3		$	90.2
Liabilities incurred		4.2			2.7			0.1
Liabilities settled		(5.7	)		(6.3	)		(2.7	)
Revisions in estimated cash flows		24.6			49.7			4.6
Accretion expense		3.8			5.2			6.1
AROs related to Offshore Business sold in July 2015		--			(91.1	)		--
ARO liability ending balance	$	85.4		$	58.5		$	98.3

Revisions to estimated cash flows for the year ended December 31, 2015 included a $39.5 million adjustment made in the second quarter of 2015 related to the Matagorda Gathering System, which was a component of the Offshore Business. In June 2015, we were notified by the U.S. Army Corps of Engineers (the “CoE”) to fully remove two pipeline segments included in this system that we had originally requested to abandon in-place. As a result, we adjusted the ARO liabilities for those pipeline segments under CoE jurisdiction to account for the estimated cost of removal. All ARO liabilities related to our Offshore Business (including those of the Matagorda Gathering System) were removed from our Consolidated Balance Sheet upon the sale of the Offshore Business on July 24, 2015.

The following table presents our forecast of accretion expense for the periods indicated:

2017				2018				2019				2020				2021
$	5.4			$	5.7			$	6.1			$	6.5			$	6.8