Accrued Final Capping, Closure and Post Closure

6 Months Ended

Jun. 30, 2016

Asset Retirement Obligation Disclosure [Abstract]

Accrued Final Capping, Closure and Post Closure

5. ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE

Accrued final capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for final capping, closure and post-closure of our landfills. We estimate our future final capping, closure and post-closure costs in order to determine the final 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. A summary of the changes to accrued final capping, closure and post-closure liabilities follows:

	Six Months Ended June 30,
	2016			2015
Beginning balance	$	41,041		$	39,829
Obligations incurred		1,143			1,116
Revisions in estimates (1)		(56	)		—
Accretion expense		1,782			1,665
Obligations settled (2)		(432	)		(984	)
Ending balance	$	43,478		$	41,626

(1) Relates to changes in estimates and assumptions concerning anticipated waste flow, cost and timing of future final capping, closure and post-closure activities at certain of our landfills.

(2) Includes amounts that are being processed through accounts payable as a part of our disbursement cycle.