State Water Resources Control Board
December 28, 2023
PERMANENT CLOSURE REQUIREMENT OF SINGLE-WALLED UNDERGROUND
STORAGE TANKS ON OR BEFORE DECEMBER 31, 2025
UST Owners and Operators:
Single-walled underground storage tanks (USTs) must be permanently closed byDecember 31, 2025. This requirement includes both single-walled tanks and nonexempt single-walled piping per California Health and Safety Code, chapter 6.7, section
25292.05. Permanent closure of a single-walled UST system shall consist of either:removal of the UST in accordance with California Code of Regulations, title 23,division 3, chapter 16 (UST Regulations), section 2672(b), or if approved by the Unified
Program Agency (UPA), closure-in-place in accordance with UST Regulations, section
2672(c). Soil samples must be collected and analyzed in accordance with UST
Regulations, section 2672(d). Owners and operators cannot avoid enforcement bysimply emptying USTs of their contents prior to the deadline. There are no exemptions,variances, or extensions to the single-walled UST closure deadline.
Single-walled UST systems that are not permanently closed by December 31, 2025 will
be out of compliance and cannot be operated. The State Water Resources Control
Board (State Water Board) has strongly encouraged the UPAs to proceed withenforcement actions, to include affixing red tags and pursuing civil penalties, against
owners and operators of any remaining single-walled UST systems beginning
January 1, 2026. USTs with a red tag affixed must be emptied of all remaining contents
within 48 hours and cannot accept fuel deliveries nor dispense any remaining fuel.
Single-walled UST owners and operators will also be subject to civil penalties of $500 to$5,000 per day, per tank, per violation for failure to permanently close by
December 31, 2025.
Licensed UST contractors are currently scheduling through 2025. Additionally, leadtimes for UST replacement equipment can take up to one year or more once ordered,and prices continue to increase with demand. Failing to secure a contractor orreplacement equipment ahead of the closure deadline will not relieve a single-walled
UST owner and operator from civil penalties. Please reach out to your UPA for closure
guidance and local permitting requirements. Additional details on the single-walled UST
closure deadline are found at https://www.waterboards.ca.gov/ust/single_walled.html.

UST Owners and Operators-2-December 28, 2023

For questions regarding the single-walled UST permanent closure deadline, contact
Jenna Hartman from the UST Leak Prevention Unit at (916) 327-8563 orJenna.Hartman@waterboards.ca.gov.
Sincerely,

Tom Henderson
UST Leak Prevention Unit andOffice of Tank Tester Licensing Manager
State Water Resources Control Board
cc: [Via email only]
Cheryl L. Prowell, P.E.
UST & Site Cleanup Program Manager
State Water Resources Control Board
Cheryl.Prowell@waterboards.ca.gov
Julie M. Osborn, Attorney IV
Office of Chief Counsel
State Water Resources Control Board
Julie.Osborn@waterboards.ca.gov
Bryan Elder, P.E.
Investigation and Technical Assistance Section Manager
Office of Enforcement
State Water Resources Control Board
Bryan.Elder@waterboards.ca.gov
Brian Taylor, PG
UST Enforcement Unit Manager
Office of Enforcement
State Water Resources Control Board
Brian.Taylor@waterboards.ca.gov
Jenna Hartman, REHS
UST Leak Prevention Unit
State Water Resources Control Board
Jenna.Hartman@waterboards.ca.gov