The procedures established by this regulation govern the arbitration of EPA claims for recovery, under section 107(a) of CERCLA, 42 U.S.C. § 9607(a), of response costs incurred at or in connection with a facility by the United States pursuant to section 104 of CERCLA, 42 U.S.C. § 9604. The procedures are applicable when:

(a) The total past and projected response costs for the facility concerned do not exceed $500,000, excluding interest; and

(b) The Administrator and one or more PRPs have submitted a joint request for arbitration pursuant to § 304.21 of this part.