Asset Retirement Obligations

3 Months Ended

Mar. 31, 2013

8. Asset Retirement Obligations

Changes in the carrying amount of our AROs were as follows (in thousands):

	2013
Balance at January 1,	$	240,634
Accretion expense	4,127
Revisions to estimated cash flows	(2,057		)
Payments	(327		)
Balance at March 31,	242,377
Less: current portion	(3,693		)
Asset retirement obligation, net of current portion	$	238,684

Revisions to estimated cash flows pertain to revisions in the estimated amount and timing of legally required reclamation activities throughout the lives of the respective mines and reflect changes in estimates of closure volumes, disturbed acreages, and third-party unit costs as of March 31, 2013.

- Definition

The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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