Cal. Health & Safety Code § 25395.82

(a) Notwithstanding Sections 25395.69, 25395.70, and 25395.75, on and after the date when the immunity specified in subdivision (c) of Section 25395.81 attaches, the person shall remain eligible for immunity if a release of hazardous materials at the site during a response action is de minimis and the agency determines that all necessary response actions to address the release have been taken.
(b) Notwithstanding Sections 25395.69, 25395.70, and 25395.75, on and after the date when the immunity specified in subdivision (c) of Section 25395.81 attaches, the person shall remain eligible for immunity if either of the following occur:
1. (1) Both of the following conditions are met:
  1. (A) A release of hazardous materials that poses an unreasonable risk is discovered before the agency makes a finding of no further action pursuant to Section 25395.95 or issues a certificate of completion pursuant to Section 25395.97.
  2. (B) The release specified in subparagraph (A) is appropriately resolved to the satisfaction of the agency pursuant to paragraph (8) of subdivision (a) of Section 25395.96.
2. (2) All of the following conditions are met:
  1. (A) A release of hazardous materials that poses an unreasonable risk is discovered after the agency makes a finding of no further action pursuant to Section 25395.95, or issues a certificate of completion pursuant to Section 25395.97.
  2. (B) The innocent landowner, bona fide purchaser, or contiguous property owner did not cause or contribute to the release.
  3. (C) The release specified in subparagraph (A) is appropriately resolved to the satisfaction of the agency pursuant to paragraph (8) of subdivision (a) of Section 25395.96.
(c) Notwithstanding Sections 25395.69, 25395.70, and 25395.75, on and after the date when the immunity specified in subdivision (c) of Section 25395.81 attaches, the person shall remain eligible for immunity obtained pursuant to this chapter with regard to a release that is the subject of a finding of no further action made pursuant to Section 25395.95 or a certificate of completion issued pursuant to Section 25395.97. If the person causes or contributes to a release of a hazardous material, that person shall be responsible for responding to that release in accordance with all applicable statutes.
(d) Notwithstanding Sections 25395.69, 25395.70, and 25395.75, on and after the date when the immunity specified in subdivision (c) of Section 25395.81 attaches to a site and a release of hazardous materials is discovered on or under the site, a response action shall be conducted at the site in accordance with the following:
1. (1) If the response action is for petroleum related contamination caused predominately by a release from an underground storage tank, the funds in the Underground Storage Tank Cleanup Fund shall, to the extent permissible by law, be used in accordance with Section 25299.51.
2. (2) If the response action is for a hazardous materials release not otherwise subject to paragraph (1), and the agency determines the hazardous material release endangers public health or safety, the person who entered into the agreement with the agency shall pay for, or undertake, the response action. If the agency determines the hazardous materials release does not endanger public health or safety, the person who entered into the agreement shall not be required to pay for, or undertake, the response action.