40 C.F.R. § 307.33
A claimant receiving an award from the Fund is required to maintain all cost documentation and any other records relating to the claim, and to provide EPA with access to such records. These records must be maintained until cost recovery is initiated by EPA. If, after ten (10) years from the date of award of the final claim, EPA has not initiated a cost recovery action, the claimant need no longer retain the records. The claimant shall, however, notify EPA of the location of the records, and allow EPA the opportunity to take possession of the records before they are destroyed. The claimant shall cause to be inserted in all agreements between itself and contractors performing work at the site a clause providing for the same requirement to maintain records and to provide access to records as that required of the claimant.
40 C.F.R. § 307.33