California Code, Health and Safety Code - HSC § 25299.93

(1) Each person named in the joint claim is an owner, operator, or other responsible party ordered to perform corrective action or remedial action pursuant to this chapter, Chapter 6.7 (commencing with Section 25280), or Division 7 (commencing with Section 13000) of the Water Code.

(2) After performing a soil and water investigation in accordance with Article 11 (commencing with Section 2720) of Chapter 16 of Division 3 of Title 23 of the California Code of Regulations, the joint claimants demonstrate to the satisfaction of the local or regulatory agency and the board that a commingled plume exists and that every identified unauthorized release or discharge has contributed substantially to the commingled plume.

(3) At least 85 percent of the commingled plume is comprised of petroleum contamination resulting from an unauthorized release from a tank whose owner or operator is eligible for payment of a claim pursuant to Section 25299.54.

(4) At least two contributing sites involve an unauthorized release.

(5) The joint claimants have coordinated corrective action as soon as practicable.

(6) The joint claimants agree to seek preapproval of corrective action costs in accordance with subdivision (c) of Section 25299.57.

(7) The joint claimants have entered into a written agreement that provides for a coordinated corrective action plan. The written agreement shall require the joint claimants to do the following:

(1) The conditions set forth in subdivision (a) are satisfied.

(2) An owner or operator named in the joint claim is liable for a third-party compensation claim.