Accrued Capping, Closure and Post Closure

3 Months Ended

Jul. 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 three months ended July 31, 2013 and 2012 are as follows:

	Three Months Ended July 31,
	2013			2012
Beginning balance	$	43,170		$	39,629
Obligations incurred		877			1,084
Accretion expense		1,011			899
Payments		(309	)		(1,119	)
Ending balance	$	44,749		$	40,493