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Asset retirement obligations (“ARO”)
6 Months Ended
Jun. 30, 2012
Asset Retirement Obligation Disclosure [Abstract]  
Asset retirement obligations (“ARO”)
Asset retirement obligations (“ARO”)
Our asset retirement obligations consist primarily of costs associated with the disposal of spent pot liner used in the reduction cells of our domestic facilities.

The reconciliation of the changes in the asset retirement obligations is presented below:
 
Six months ended June 30,
Year ended December 31, 2011
Beginning balance, ARO liability
$
15,171

$
14,274

Additional ARO liability incurred
582

1,110

ARO liabilities settled
(690
)
(1,315
)
Accretion expense
584

1,102

Ending balance, ARO liability
$
15,647

$
15,171


Certain conditional AROs related to the disposal costs of fixed assets at our primary aluminum facilities have not been recorded because they have an indeterminate settlement date. These conditional AROs will be initially recognized in the period in which sufficient information exists to estimate their fair value.