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Underground Storage Tank Regulations: The UST Program

EH&S Compliance

Written by: Virginia McCormick, NES, Inc.

The UST Program, as part of California’s Unified Program, helps to protect the public and the environment from discharges and releases of hazardous substances from USTs.


This article is part of a special dedicated series that covers California CUPAs and the Unified Program. For a complete overview, see the June 2019 NES article California CUPA Overview: Enforcing the CalEPA Unified Program.


The UST Program: Protecting California’s Environment

In the United States, large quantities of gasoline, diesel, biodiesel, and waste oils are typically stored using underground storage tanks, or USTs. Underground storage of hazardous materials can be convenient for many businesses, such as gas stations or manufacturing facilities, but may also present unique environmental and safety risks. In order to mitigate these risks, California’s UST Program was introduced.

The UST Program is intended to protect the waters of the State from discharges of hazardous substances from underground storage tanks. An underground storage tank is defined as, “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.”

Most UST owners and operators in California take the initiative to voluntarily comply with environmental laws and regulations. Some, however, do not comply due to lack of information, neglect, or deliberate intent. The UST Program is intended to identify, correct, and support the California UST owners that fail to comply with these laws and regulations.

The program is overseen by the California State Water Resources Control Board (SWRCB) and enforced through local CUPAs and/or PAs as part of the Unified Program.


Underground storage tanks do not have to be completely buried in order to be regulated under the UST Program.


The Four Elements of the UST Program

The purpose of the UST Program is to protect public health and safety, the environment, and State waters from discharges and releases of hazardous substances from USTs. In order to achieve this, four elements are utilized under the UST Program: leak prevention, cleanup, enforcement, and tank testing licensing. These elements are derived from the UST regulations under California Code of Regulations, Title 23, Chapter 16 (23 CCR, Chapter 16), which was updated in October 2018.

Leak Prevention

Requirements for tank installation, construction, testing, leak detection, spill containment, and overfill protection are all included within the UST Program. California UST laws and regulations give local agencies such as CUPAs the authority to issue permits for tank operation and to enforce tank testing requirements within their jurisdiction.

As stated in 23 CCR, Chapter 16, all forms of leak monitoring equipment used in relation to USTs must be, “demonstrably able to detect a leak at the earliest possible opportunity” and testable. Leak monitoring equipment is required to have a probability of detection of 95% or higher, and a probability of false alarm of 5% or less. Leak prevention also covers leak interception devices, secondary containment systems, and exterior informational markings of the UST.


If a leak does occur, cleanup is implemented. Cleanup, as an element of the UST Program, is conducted under the direction of the CUPA/PA and may include, “product removal, vapor extraction, ozone sparging or technologies such as groundwater extraction.” In some cases, soil excavation and disposal may be included in the cleanup.

Additionally, the Underground Storage Tank Cleanup Fund provides UST owners with financial assistance when meeting federal and State operating requirements by providing some reimbursement for expenses associated with cleanup efforts. The fund also provides money to the Regional Water Boards and local regulatory agencies to, “abate emergency situations or to cleanup abandoned sites that pose a threat to human health, safety, and the environment, as a result of a UST petroleum release.”


The four elements that comprise the UST Program help keep the public safe, the environment healthy, and California waters clean.



According to the SWRCB, the UST Enforcement Unit was established in order to support the UST Program, primarily through investigating violations, monitoring tank facilities, and ensuring adherence to cleanup requirements. These include violations such as failure to monitor tank systems, failure to perform required testing, and tampering with leak detection devices.

The UST Enforcement Unit works closely with various local, State, and federal agencies to conduct inspections, review data, and assist in UST investigations to, “achieve compliance of USTs and minimize threats to water quality and the environment.” The UST Enforcement Unit also supports the execution of the California Tank Tester Licensing Program.

Tank Tester Licensing

The Tank Tester Licensing Program establishes the minimum qualifications for those who test underground storage tanks and associated piping under the UST Program. The SWRCB licenses and regulates tank testers under California Health and Safety Code, Chapter 6.7, Section 25284.4, and California Code of Regulations, Title 23, Division 3, Chapter 17, Sections 2730 – 2802.

Since 1990, a license has been required to conduct tank integrity testing on underground storage tanks. The SWRCB and California take this element of the UST Program very seriously; conducting a test without a license is considered a misdemeanor.

Frequent tank tests ensure that a UST is operating correctly by using leak detection equipment and methods, which are required to be evaluated by an independent third-party testing organization. A tank tester’s license may also be used to conduct annual monitoring and secondary containment testing.


In addition to the California UST Program, UST owners must ensure they comply with federal EPA regulations.


Federal Equivalent to the UST Program

In 1988, the federal Environmental Protection Agency (EPA) issued UST regulations that were divided into three sections: technical requirements, financial responsibility, and state program approval objectives.

By design, these EPA regulations closely mirror various states’ UST programs. According to the federal agency, states are the primary implementers of UST regulations and are in the better position to oversee USTs. While California regulations tend to be more extensive, owners and operators of USTs should ensure they are adhering to federal UST regulations.

Additionally, EPA will often support local CUPAs/PAs by encouraging the use of better practices in UST owners’ corrective action programs, such as risk-based decision-making processes. By offering federal support through certain state-level programs, EPA helps local communities deal with potentially dangerous UST releases more quickly and efficiently.


Environmental Consulting with NES

NES has been providing environmental consulting services on behalf of a wide array of public and private businesses and government agencies for the past 30 years. We provide UST Owner/Operator training and other valuable programs on behalf of various CUPAs throughout California. If you need help with or have questions regarding underground storage tanks or associated regulatory requirements, please contact NES at or 916-353-2360 / 1-800-NES-ADVISE.



23 CCR, Chapter 16

California State Water Resources Control Board: Division of Water Quality – Underground Storage Tank Program

UST Program – Cleanup

Underground Storage Tank Cleanup Fund

Underground Storage Tank Enforcement

Office of Tank Tester Licensing Program

Local Guidance (LG) Letter 113: List of Leak Detection Equipment and Methods for Underground Storage Tanks

California CUPA Forum: Underground Storage Tanks

EPA: Federal Underground Storage Tanks (USTs) Requirements