Accrued Capping, Closure and Post Closure

6 Months Ended

Oct. 31, 2013

Asset Retirement Obligation Disclosure [Abstract]

Accrued Capping, Closure and Post Closure

4. ACCRUED CAPPING, CLOSURE AND POST CLOSURE

Accrued capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for closure and post-closure of our landfills. We estimate our future capping, closure and post-closure costs in order to determine the capping, closure and post-closure expense per ton of waste placed into each landfill. The anticipated timeframe for paying these costs varies based on the remaining useful life of each landfill, as well as the duration of the post-closure monitoring period. 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