Accrued Capping, Closure and Post Closure (Tables)

6 Months Ended

Oct. 31, 2013

Asset Retirement Obligation Disclosure [Abstract]

Changes to Accrued Capping, Closure and Post-Closure Liabilities

The changes to accrued capping, closure and post-closure liabilities for the six months ended October 31, 2013 and 2012 are as follows:

	Six Months Ended October 31,
	2013			2012
Beginning balance	$	43,170		$	39,629
Obligations incurred		1,918			1,960
Accretion expense		1,999			1,789
Payments		(1,106	)		(2,089	)
Ending balance	$	45,981		$	41,289