Section 154.315 - Asset retirement obligations(a) A natural gas company that files a tariff change under this part and has recorded an asset retirement obligation on its books must provide a schedule, as part of the supporting workpapers, identifying all cost components related to the asset retirement obligations that are included in the book balances of all accounts reflected in the cost of service computation supporting the proposed rates. However, all cost components related to asset retirement obligations that would impact the calculation of rate base, such as gas plant and related accumulated depreciation and accumulated deferred income taxes, may not be reflected in rates and must be removed from the rate base calculation through a single adjustment.(b) A natural gas company seeking to recover nonrate base costs related to asset retirement obligations in rates must provide, with its filing under § 154.312 or § 154.313 , a detailed study supporting the amounts proposed to be collected in rates.(c) A natural gas company who has recorded asset retirement obligations on its books but is not seeking recovery of the asset retirement costs in rates, must remove all asset retirement obligations related cost components from the cost of service supporting its proposed rates.Order 631, 68 FR 19622, Apr. 21, 2003