Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Cash Flows from Operating Activities:
Net loss	$ (154)	$ (163)
Adjustments to reconcile net loss to net cash provided by operating activities:
Income from discontinued operations, net of tax		(329)
Loss on disposal of discontinued operations, net of tax		378
Gain on sale of property and equipment	(25)	(164)
Depreciation and amortization	16,368	15,197
Depletion of landfill operating lease obligations	3,134	2,627
Interest accretion on landfill and environmental remediation liabilities	832	1,046
Amortization of discount on senior subordinated notes	64	59
Loss from equity method investments		977
Gain on derivative instruments	(69)	(654)
Stock-based compensation	562	631
Excess tax benefit on the vesting of share based awards	(59)	63
Deferred income taxes	224	260
Changes in assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(6,609)	(5,588)
Accounts payable	(4,416)	278
Prepaid expenses, inventories and other assets	(913)	(2,179)
Accrued expenses and other liabilities	4,642	7,087
Net cash provided by operating activities	13,581	19,526
Cash Flows from Investing Activities:
Acquisitions, net of cash acquired		(29)
Additions to property, plant and equipment	(16,881)	(13,407)
Payments on landfill operating lease contracts	(962)	(1,982)
Payments related to investments		(2,148)
Proceeds from sale of property and equipment	163	284
Net cash used in investing activities	(17,725)	(18,354)
Cash Flows from Financing Activities:
Proceeds from long-term borrowings	38,300	29,890
Principal payments on long-term debt	(34,314)	(29,310)
Payments of financing costs	(1)	(359)
Proceeds from the exercise of share based awards	143
Excess tax benefit on the vesting of share based awards	59	(63)
Net cash provided by (used in) financing activities	4,187	158
Discontinued Operations:
Net cash used in operating activities		(166)
Net cash provided by investing activities	88
Net cash provided by (used in) discontinued operations	88	(166)
Net increase in cash and cash equivalents	131	1,164
Cash and cash equivalents, beginning of period	2,464	1,755
Cash and cash equivalents, end of period	2,595	2,919
Cash paid during the period for:
Interest	1,868	1,902
Income taxes, net of refunds	61	720
Supplemental Disclosures of Non-Cash Investing and Financing Activities:
Receivable due from noncontrolling interest holder	155
Property, plant and equipment acquired through lease obligations		2,301
Acquisition [Member]
Cash Flows from Investing Activities:
Additions to property, plant and equipment	$ (45)	$ (1,072)