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ASSET RETIREMENT OBLIGATION: | 12 Months Ended
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Dec. 31, 2011
ASSET RETIREMENT OBLIGATION: |
ASSET RETIREMENT OBLIGATION: |
NOTE 10-ASSET RETIREMENT OBLIGATION: The Company maintains an estimated asset retirement obligation for its mining properties in Peru, as required by the Peruvian Mine Closure Law. In accordance with the requirements of this law, the Company’s closure plans were approved by MINEM. As part of the closure plans, commencing in January 2010 the Company is required to provide annual guarantees of $2.6 million over a 34 year period to furnish the funds for the asset retirement obligation. In the near-term future the Company has pledged the value of its Lima office complex as support for this obligation. The accepted value of the Lima office building, for this purpose, is $17 million. The closure cost recognized for this liability includes the cost, as outlined in its closure plans, of dismantling the Toquepala and Cuajone concentrators, the smelter and refinery in Ilo, and the shops and auxiliary facilities at the three units. In 2010, the closure plan for the new Ilo marine trestle was added to the asset retirement obligation. The following table summarizes the asset retirement obligation activity for the two years ended December 31, 2011 and 2010 (in millions):
|  | 2011 |  | 2010 |
Balance as of January 1 |  | $ | 59.1 |  | $ | 48.9 |
Changes in estimates |  | — |  | 5.3 |
Additions |  | — |  | 1.6 |
Closure payments |  | (0.5 | ) | — |
Accretion expense |  | 3.4 |  | 3.3 |
Balance as of December 31, |  | $ | 62.0 |  | $ | 59.1 |

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- 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 143 -Paragraph 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7569-110849 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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