Underground Storage Tank (UST) Low-Threat Closure Policy
Regulatory agencies direct corrective actions and evaluate site conditions for leaking underground storage tank (UST) petroleum cases to safeguard human health, safety, and the environment, as mandated by Health and Safety Code section 25296.10, subdivision (g). Through over 40 years of investigating and remediating petroleum UST releases, the State Water Resources Control Board (State Water Board) has identified specific site conditions and characteristics that, when met, generally guarantee the protection of human health and the environment while leaving limited residual hydrocarbons in the ground that naturally degrade over a reasonable time. Cases that meet these criteria are deemed “low-threat” and may be proposed for case closure.
The State Water Board adopted the Low-Threat Underground Storage Tank Case Closure Policy (Policy) on May 1, 2012 (Resolution No. 2012-0016), and the Policy became effective on August 17, 2012. The Policy outlines standardized criteria to meet low-threat closure conditions and is accompanied by three Technical Justifications for groundwater, soils, and soil vapor, that detail how these criteria were determined. This Policy is essential for ensuring consistent statewide standards when closing low-threat petroleum UST cases in California.
Looking to report an unauthorized UST leak? Contact your local Certified Unified Program Agency (CUPA).
Highlights
- Policy Adoption Documentation has been moved to its own page!
Low-Threat Closure Policy
Implementation Plan
Policy FAQs
Policy Adoption
Technical Justifications - Media Specific Criteria
Groundwater
Vapor Intrusion
Soil/Direct Contact
On November 6, 2012, the State Water Board approved the Plan for Implementation of Low-Threat Underground Storage Tank Case Closure Policy and Additional Program Improvements (Plan) (Resolution No. 2012-0062). The Plan aims to ensure consistent application and uniform implementation of the UST Cleanup Program statewide.
The approved Plan:
- implements the Policy as adopted by the State Water Board under Resolution No. 2012-0016, and
- summarizes other actions to improve the administration of the UST Cleanup Program.
The Plan outlines the roles and responsibilities of the implementing agencies, focuses on prioritizing the highest risk cases (such as those affecting drinking water wells, human health, or containing free product), and establishes Path to Case Closure Plans for each open case, complete with specific milestones and timelines.
Resolution No. 2012-0062 instructs staff from the State Water Board and other regulatory agencies (e.g., the Regional Water Quality Control Boards and the Local Oversight Program (LOP) agencies) to actively implement the approved Plan and undertake various additional measures to enhance the UST Cleanup Program.
Resolution No. 2012-0062 also mandates State Water Board staff to review decisions made by regulatory agencies when they deny a responsible party's request for case closure under the Policy. Within six months of the closure denial, the State Water Board should either update GeoTracker with the closure denial concurrence or propose the case for closure, whichever is appropriate.
- 92-49 – Cleanup and Abatement Policies and Procedures
- 2012-0016 – Adoption of Low-Threat Closure Policy
- 2012-0062 – UST Cleanup Program Implementation Plan
- 2013-0001 – UST Local Oversight Program
- 2023-0036 – Delegation of Authority for Executive Officer
- Order No. 2013-0109 - Salvatore precedential decision on commingled plumes
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