## Health and Safety Code - HSC ## DIVISION 20. MISCELLANEOUS HEALTH AND SAFETY PROVISIONS [24000 - 28002] ( Division 20 enacted by Stats. 1939, Ch. 60. ) ## CHAPTER 6.7. Underground Storage of Hazardous Substances [25280 - 25299.8] ( Chapter 6.7 added by Stats. 1983, Ch. 1046, Sec. 3. ) ## 25281. For purposes of this chapter and unless otherwise expressly provided, the following definitions apply: (a) “Automatic line leak detector” means any method of leak detection, as determined in regulations adopted by the board, that alerts the owner or operator of an underground storage tank to the presence of a leak. “Automatic line leak detector” includes, but is not limited to, any device or mechanism that alerts the owner or operator of an underground storage tank to the presence of a leak by restricting or shutting off the flow of a hazardous substance through piping, or by triggering an audible or visual alarm, and that detects leaks of three gallons or more per hour at 10 pounds per square inch line pressure within one hour. (b) “Board” means the State Water Resources Control Board. “Regional board” means a California regional water quality control board. (c) “Compatible” means the ability of two or more substances to maintain their respective physical and chemical properties upon contact with one another for the design life of the tank system under conditions likely to be encountered in the tank system. (d) (1) “Certified Unified Program Agency” or “CUPA” means the agency certified by the Secretary for Environmental Protection to implement the unified program specified in Chapter 6.11 (commencing with Section 25404) within a jurisdiction. (2) “Participating Agency” or “PA” means an agency that has a written agreement with the CUPA pursuant to subdivision (d) of Section 25404.3, and is approved by the secretary to implement or enforce the unified program element specified in paragraph (3) of subdivision (c) of Section 25404, in accordance with Sections 25404.1 and 25404.2. (3) “Unified Program Agency” or “UPA” means the CUPA, or its participating agencies to the extent each PA has been designated by the CUPA, pursuant to a written agreement, to implement or enforce the unified program element specified in paragraph (3) of subdivision (c) of Section 25404. For purposes of this chapter, a UPA has the responsibility and authority, to the extent provided by this chapter and Sections 25404.1 to 25404.2, inclusive, to implement and enforce only those requirements of this chapter listed in paragraph (3) of subdivision (c) of Section 25404 and the regulations adopted to implement those requirements. Except as provided in Section 25296.09, after a CUPA has been certified by the secretary, the UPA shall be the only local agency authorized to enforce the requirements of this chapter listed in paragraph (3) of subdivision (c) of Section 25404 within the jurisdiction of the CUPA. This paragraph shall not be construed to limit the authority or responsibility granted to the board and the regional boards by this chapter to implement and enforce this chapter and the regulations adopted pursuant to this chapter. (e) “Department” means the Department of Toxic Substances Control. (f) “Facility” means any one, or combination of, underground storage tanks used by a single business entity at a single location or site. (g) “Federal act” means Subchapter IX (commencing with Section 6991) of Chapter 82 of Title 42 of the United States Code, as added by the Hazardous and Solid Waste Amendments of 1984 (Public Law 98-616), or as it may subsequently be amended or supplemented. (h) “Hazardous substance” means either of the following: (1) All of the following liquid and solid substances, unless the department, in consultation with the board, determines that the substance could not adversely affect the quality of the waters of the state: (A) Substances on the list prepared by the Director of Industrial Relations pursuant to Section 6382 of the Labor Code. (B) Hazardous substances, as defined in subdivision (a) of Section 78075. (C) Any substance or material that is classified by the National Fire Protection Association (NFPA) as a flammable liquid, a class II combustible liquid, or a class III-A combustible liquid. (2) Any regulated substance, as defined in subsection (7) of Section 6991 of Title 42 of the United States Code, as that section read on January 1, 2012, or as it may subsequently be amended or supplemented. (i) “Local agency” means one of the following, as specified in subdivision (b) of Section 25283: (1) The unified program agency. (2) Before July 1, 2013, a city or county. (3) On and after July 1, 2013, a city or county certified by the board to implement the local oversight program pursuant to Section 25297.01. (j) “Operator” means any person in control of, or having daily responsibility for, the daily operation of an underground storage tank system. (k) “Owner” means the owner of an underground storage tank. (l) “Person” means an individual, trust, firm, joint stock company, corporation, including a government corporation, partnership, limited liability company, or association. “Person” also includes any city, county, district, the state, another state of the United States, any department or agency of this state or another state, or the United States to the extent authorized by federal law. (m) “Pipe” means any pipeline or system of pipelines that is used in connection with the storage of hazardous substances and that is not intended to transport hazardous substances in interstate or intrastate commerce or to transfer hazardous materials in bulk to or from a marine vessel. (n) “Primary containment” means the first level of containment, such as the portion of a tank that comes into immediate contact on its inner surface with the hazardous substance being contained. (o) “Product tight” means impervious to the substance that is contained, or is to be contained, so as to prevent the seepage of the substance from the containment. (p) “Release” means any spilling, leaking, emitting, discharging, escaping, leaching, or disposing from an underground storage tank into or on the waters of the state, the land, or the subsurface soils. (q) “Secondary containment” means the level of containment external to, and separate from, the primary containment. (r) “Single walled” means construction with walls made of only one thickness of material. For purposes of this chapter, laminated, coated, or clad materials are considered single walled. (s) “Special inspector” means a professional engineer, registered pursuant to Chapter 7 (commencing with Section 6700) of Division 3 of the Business and Professions Code, who is qualified to attest, at a minimum, to structural soundness, seismic safety, the compatibility of construction materials with contents, cathodic protection, and the mechanical compatibility of the structural elements of underground storage tanks. (t) (1) “Storage” or “store” means the containment, handling, or treatment of hazardous substances, either on a temporary basis or for a period of years. (2) “Storage” or “store” does not include the storage of hazardous wastes in an underground storage tank if the person operating the tank has been issued a hazardous waste facilities permit by the department pursuant to Section 25200 or 25201.6 or granted interim status under Section 25200.5. (3) “Storage” or “store” does not include the storage of hazardous wastes in an underground storage tank if all of the following apply: (A) The facility has been issued a unified program facility permit pursuant to Section 25404.2 for generation, treatment, accumulation, or storage of hazardous waste in a tank. (B) The tank is located in an underground area, as defined in Section 280.12 of Title 40 of the Code of Federal Regulations. (C) The tank is subject to Chapter 6.67 (commencing with Section 25270). (D) The tank complies with the hazardous waste tank standards pursuant to Article 10 (commencing with Section 66265.190) of Chapter 15 of Title 22 of the California Code of Regulations. (4) “Storage” or “store” does not include the storage of hazardous wastes in an underground storage tank if all of the following apply: (A) The facility has been issued a unified program facility permit pursuant to Section 25404.2 for generation, treatment, accumulation, or storage of hazardous waste in a tank. (B) The tank is located in a structure that is at least 10 percent below the ground surface, including, but not limited to, a basement, cellar, shaft, pit, or vault. (C) The structure in which the tank is located, at a minimum, provides for secondary containment of the contents of the tank, piping, and ancillary equipment, until cleanup occurs. (D) The tank complies with the hazardous waste tank standards pursuant to Article 10 (commencing with Section 66265.190) of Chapter 15 of Title 22 of the California Code of Regulations. (u) “Tank” means a stationary device designed to contain an accumulation of hazardous substances that is constructed primarily of nonearthen materials, including, but not limited to, wood, concrete, steel, or plastic that provides structural support. (v) “Tank integrity test” means a test method capable of detecting an unauthorized release from an underground storage tank consistent with the minimum standards adopted by the board. (w) “Tank tester” means an individual who performs tank integrity tests on underground storage tanks. (x) “Unauthorized release” means any release of any hazardous substance that does not conform to this chapter, including an unauthorized release specified in Section 25295.5. (y) (1) “Underground storage tank” means any one or combination of tanks, including pipes connected thereto, that is used for the storage of hazardous substances and that is substantially or totally beneath the surface of the ground. “Underground storage tank” does not include any of the following: (A) A tank with a capacity of 1,100 gallons or less that is located on a farm and that stores motor vehicle fuel used primarily for agricultural purposes and not for resale. (B) A tank that is located on a farm or at the residence of a person, that has a capacity of 1,100 gallons or less, and that stores home heating oil for consumptive use on the premises where stored. (C) Structures, such as sumps, separators, storm drains, catch basins, oil field gathering lines, refinery pipelines, lagoons, evaporation ponds, well cellars, separation sumps, and lined and unlined pits, sumps, and lagoons. A sump that is a part of a monitoring system required under Section 25290.1, 25290.2, 25291, or 25292 and sumps or other structures defined as underground storage tanks under the federal act are not exempted by this subparagraph. (D) A tank holding hydraulic fluid or dielectric fluid for a closed loop mechanical system that uses compressed air, hydraulic fluid, or dielectric fluid to operate lifts, to operate elevators, to act as an electric cooling or insulation system, and other similar devices. (E) A tank in an underground area, as defined in Section 25270.2, and associated piping, that is subject to Chapter 6.67 (commencing with Section 25270). (2) Structures identified in subparagraphs (C) and (D) of paragraph (1) may be regulated by the board and any regional board pursuant to the Porter-Cologne Water Quality Control Act (Division 7 (commencing with Section 13000) of the Water Code) to ensure that they do not pose a threat to water quality. (z) “Underground tank system” or “tank system” means an underground storage tank, connected piping, ancillary equipment, and containment system, if any. (aa) (1) “Unified program facility” means all contiguous land and structures, other appurtenances, and improvements on the land that are subject to the requirements of paragraph (3) of subdivision (c) of Section 25404. (2) “Unified program facility permit” means a permit issued pursuant to Chapter 6.11 (commencing with Section 25404), and that encompasses the permitting requirements of Section 25284. (3) “Permit” means a permit issued pursuant to Section 25284 or a unified program facility permit as defined in paragraph (2). (Amended by Stats. 2025, Ch. 89, Sec. 4. (AB 1459) Effective January 1, 2026.)
