Asset Retirement Obligations

3 Months Ended

Mar. 31, 2012

Asset Retirement Obligation [Abstract]

Asset Retirement Obligations

ASSET RETIREMENT OBLIGATIONS

At the end of each period, Asset Retirement Obligations (“ARO”) are equal to the present value of all estimated future costs required to remediate any environmental disturbances that exist as of the end of the period, using discount rates applicable at the time of initial recognition of each component of the liability. Included in this liability are the costs of closure, reclamation, demolition and stabilization of the mines, processing plants, infrastructure, tailings storage facilities, waste dumps and ongoing post-closure environmental monitoring and maintenance costs. While the majority of these costs will be incurred near the end of the mines' lives, it is expected that certain on-going reclamation costs will be incurred prior to mine closure. These costs are recorded against the asset retirement obligation liability as incurred. At March 31, 2012, and March 31, 2011, the total undiscounted amount of the estimated future cash needs was estimated to be $70.3 million and $84.1 million, respectively. Discount rates used to value the ARO range between 8% and 10%. The schedule of payments required to settle the December 31, 2011, ARO liability extends through 2029.

The changes in the carrying amount of the ARO during the three months ended March 31, 2012, and March 31, 2011, are as follows:

	For the three months ended
	March 31,
	2012			2011
Beginning balance	$	33,880		$	44,952
Accretion expense	703			933
Additions and change in estimates	—			3,748
Cost of reclamation work performed	(2,575		)	(3,883		)
Balance at March 31	$	32,008		$	45,750
Current portion	$	8,626		$	23,220
Long term portion	$	23,382		$	22,530