Asset Retirement Obligations

12 Months Ended

Dec. 31, 2011

Asset Retirement Obligation Disclosure [Abstract]

ASSET RETIREMENT OBLIGATIONS

7. ASSET RETIREMENT OBLIGATIONS

Our accrued asset retirement obligations relate to our gas storage and transmission facilities. At the end of the useful life of our facilities, we are legally obligated to remove certain transmission facilities including underground pipelines, major river spans, compressor stations and meter station facilities. These obligations also include restoration of the property sites after removal of the facilities from above and below the ground.

During 2011 and 2010, our overall asset retirement obligation changed as follows (in thousands):

		2011		2010
Beginning balance		$	65,155	$	86,749
	Accretion		5,162		6,058
	New obligations		2,257		27
	Changes in estimates of existing obligations (1)		8,116		(27,679)
	Property Dispositions & Settlements		(377)		-
Ending balance		$	80,313	$	65,155
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• Changes in estimates of existing obligations are primarily due to the annual review process, which considers various factors including inflation rates, current estimates for removal cost, discount rates, and the estimated remaining life of assets.