(a)  For purposes of this section, the following definitions apply:

(1)  “Agency” means the California Environmental Protection Agency.

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(2)  “Contaminant” means all of the following:

(A)  A substance listed in Tables II and III of subparagraphs (A) and (B) of paragraph (2) of subdivision (a) of Section 66261.24 of Title 22 of the California Code of Regulations.

(B)  The five halogenated hydrocarbon industrial solvents that, in the experience of the State Water Resources Control Board and the Department of Toxic Substances Control are most commonly found as contaminants at sites subject to remediation under the Carpenter-Presley-Tanner Hazardous Substances Account Act (Part 2 (commencing with Section 78000) of Division 45) and the Porter-Cologne Water Quality Control Act (Division 7 (commencing with Section 13000) of the Water Code).

(C)  Ten hazardous substances not included under subparagraphs (A) and (B) that, in the experience of the Department of Toxic Substances Control and the State Water Resources Control Board, are most commonly found as contaminants at sites subject to remediation under the Carpenter-Presley-Tanner Hazardous Substances Account Act (Part 2 (commencing with Section 78000) of Division 45) and the Porter-Cologne Water Quality Control Act (Division 7 (commencing with Section 13000) of the Water Code).

(3)  “Screening number” means the concentration of a contaminant published by the agency as an advisory number pursuant to the process established in subdivisions (b) and (c). A screening number is solely an advisory number, and has no regulatory effect, and is published solely as a reference value that may be used by citizen groups, community organizations, property owners, developers, and local government officials to estimate the degree of effort that may be necessary to remediate a contaminated property. A screening number may not be construed as, and may not serve as, a level that can be used to require an agency to determine that no further action is required or a substitute for the cleanup level that is required to be achieved for a contaminant on a contaminated property. The public agency with jurisdiction over the remediation of a contaminated site shall establish the cleanup level for a contaminant pursuant to the requirements and the procedures of the applicable laws and regulations that govern the remediation of that contaminated property and the cleanup level may be higher or lower than a published screening number.

(b)  (1)  During the same period when the agency is carrying out the pilot study required by Section 57009 and preparing the informational document required by Section 57010, the agency shall initiate a scientific peer review of the screening levels published in Appendix 1 of Volume 2 of the technical report published by the San Francisco Regional Water Quality Control Board entitled “Application of Risk-Based Screening Levels and Decision-Making to Sites with Impacted Soil and Groundwater (Interim Final-August 2000).” The agency shall conduct the scientific peer review process in accordance with Section 57004, and shall limit the review to those substances specified in paragraph (2) of subdivision (a). The agency shall complete the peer review process on or before December 31, 2004.

(2)  The agency, in cooperation with the Department of Toxic Substances Control, the State Water Resources Control Board, and the Office of Environmental Health Hazard Assessment, shall publish a list of screening numbers for contaminants listed in paragraph (2) of subdivision (a) for the protection of human health and safety, and shall report on the feasibility of establishing screening numbers to protect water quality and ecological resources. The agency shall determine the screening numbers using the evaluation set forth in Article 13 (commencing with Section 79260) of Chapter 5 of Part 2 of Division 45 and the results of the peer review, and shall use the most stringent hazard criterion established pursuant to Subpart E of the National Oil and Hazardous Substances Pollution Contingency Plan (40 C.F.R. § 300.400 et seq.), as amended. The agency shall set forth separate screening levels for unrestricted land uses and a restricted, nonresidential use of land. In determining each screening number, the agency shall consider all of the following:

(A)  The toxicology of the contaminant, its adverse effects on human health and safety, biota, and its potential for causing environmental damage to natural resources, including, but not limited to, beneficial uses of the water of the state, including sources of drinking water.

(B)  Risk assessments that have been prepared for the contaminant by federal or state agencies pursuant to environmental or public health laws, evaluations of the contaminant that have been prepared by epidemiological studies and occupational health programs, and risk assessments or other evaluations of the contaminant that have been prepared by governmental agencies or responsible parties as part of a project to remediate a contaminated property.

(C)  Cleanup levels that have been established for the contaminant at sites that have been, or are being, investigated or remediated under Part 2 (commencing with Section 78000) of Division 45, or cleaned up or abated under Division 7 (commencing with Section 13000) of the Water Code or under any other remediation program administered by a federal or local agency.

(D)  Screening numbers that have been published by other agencies in the state, in other states, and by federal agencies.

(E)  The results of external scientific peer review of the screening numbers made pursuant to Section 57004.

(c)  (1)  Before publishing the screening numbers pursuant to subdivision (b), the agency shall conduct two public workshops, one in the northern part of the state and the other in the southern part of the state, to brief interested parties on the scientific and policy bases for the development of the proposed screening numbers and to receive public comments.

(2)  Following publication of the screening numbers pursuant to subdivision (b), the agency shall conduct three public workshops in various regions of the state to discuss the screening numbers and to receive public comments. The agency shall select an agency representative who shall serve as the chairperson for the workshops, and the agency shall ensure that ample opportunity is available for public involvement in the workshops. The deputy secretary for external affairs shall actively seek out participation in the workshops by citizen groups, environmental organizations, community-based organizations that restore and redevelop contaminated properties for park, school, residential, commercial, open-space or other community purposes, property owners, developers, and local government officials.

(d)  Following the workshops required by subdivision (c), the agency shall revise the screening numbers as appropriate. The agency shall, from time to time, revise the screening numbers as necessary as experience is gained with their use and shall add screening numbers for contaminants to the list as information concerning remediation problems becomes available.

(e)  The agency shall publish a guidance document for distribution to citizen groups, community-based organizations, property owners, developers, and local government officials that explains how screening numbers may be used to make judgments about the degree of effort that may be necessary to remediate contaminated properties, to facilitate the restoration and revitalization of contaminated property, to protect the waters of the state, and to make more efficient and effective decisions in local-level remediation programs.

(f)  Nothing in this section affects the authority of the Department of Toxic Substances Control, the State Water Resources Control Board, or a regional water quality control board to take action under any applicable law or regulation regarding a release or threatened release of hazardous materials.

(Amended by Stats. 2022, Ch. 258, Sec. 106. (AB 2327) Effective January 1, 2023. Operative January 1, 2024, pursuant to Sec. 130 of Stats. 2022, Ch. 258.)