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.