DOEE Reproposes Changes to Underground Storage Tank Regulations for Aged Tanks

The District of Columbia's Department of Energy and Environment (DOEE) first proposed changes to the city's underground storage tank (UST) regulations for tanks that are 30 years or more old on September 12, 2025. The recently issued Second Proposed Rulemaking does not appear to materially alter the core framework described in the First Proposed Rulemaking. The reproposal keeps the same central policy in focus, but it replaces age-based mandatory removal with recurring integrity testing and continued compliance obligations for aged USTs. (For additional background on the First Proposed Rulemaking and 2020 aged-tank requirements, see Holland & Knight's previous alert, "District of Columbia's DOEE Proposes Changes to Underground Storage Tank Regulations," September 22, 2025.)

The Second Proposed Rulemaking, published in the D.C. Register on June 26, 2026, opens a new opportunity for affected owners, operators and real estate stakeholders to comment on how aged tanks should be regulated before DOEE takes final action.

Key Proposed Changes

The proposed amendments would revise Title 20 of the District of Columbia Municipal Regulations (DCMR) § 5700.10. Under the existing regulations, an owner or operator of an aged UST (i.e., one that is more than 30 years old) would have had to remove that tank by February 21, 2025. Under the reproposal, the owner or operator would be able to continue operating the UST if it conducts tank tightness testing every three years and submits those results to DOEE. If an aged UST fails the tank tightness test, the owner or operator would be required to permanently close the UST within one year of test failure.

The proposal also would add a new 20 DCMR § 6007.6 stating that an owner or operator of a UST that is more than 30 years old must perform tank tightness testing in accordance with Section 6007 pursuant to Section 5700.11. DOEE describes the triennial testing requirement as an additional safeguard, not a substitute for other compliance obligations. DOEE states that the triennial tank tightness testing would be in addition to annual piping and leak detection equipment testing and monthly leak detection testing that are currently required.

Why This Matters

Substantively, the proposal remains important for owners and operators of gas stations, commercial properties, institutional facilities and other district properties with USTs that were installed more than 30 years ago because the proposed rule would determine whether those tanks may continue to operate under a triennial testing regime rather than being removed based solely on age.

The proposal also may affect real estate diligence and deal timing. Parties to transactions involving district properties with USTs should consider whether tank age, testing history, release detection records, closure obligations and potential future testing costs are addressed in purchase agreements, leases, loan documents and environmental indemnities. The parties should address in deal documents who is responsible for testing and/or removal of aged inactive or abandoned tanks. Because the proposal would allow continued operation of the tanks only if the owner or operator complies with the revised testing framework, diligence should focus not only on whether a tank is more than 30 years old but also on whether testing was performed as required, whether results were submitted to DOEE and whether any failed test triggered permanent tank closure obligations.

Open Comment Period

The comment period for the Second Proposed Rulemaking is open now. DOEE states that comments on the proposed rulemaking should be submitted in writing no later than 30 days after publication, i.e., by July 26, 2026.

Stakeholders may wish to comment on whether triennial tank tightness testing is the appropriate interval for aged tanks, whether the proposed 90-day initial testing period is feasible, whether the one-year permanent closure period following a failed test is workable, whether the requirements apply to inactive and abandoned USTs in the district, and how the new requirements apply to tanks that were already subject to the February 21, 2025, removal deadline. These issues arise directly from the proposed revisions to Sections 5700.10, 5700.11 and 6007.6.

Next Steps

Owners and operators of USTs in the district should identify tanks that are at or approaching 30 years of age, confirm testing histories and recordkeeping, and evaluate whether any compliance gaps should be addressed during the comment period. DOEE requires tank tightness testing to be performed in accordance with Section 6007, and the proposed rule would make that testing a recurring obligation for USTs more than 30 years old. Owners and operators also should coordinate with qualified UST professionals because district rules require UST system testing to be conducted under the continuous on-site supervision of a certified UST System Tester licensed to do business in the district.

Holland & Knight will continue to monitor the Second Proposed Rulemaking and related developments affecting UST owners, operators, purchasers, sellers and lenders in the District of Columbia. For further information or to provide comments on the reproposal, please contact the authors.

Information contained in this alert is for the general education and knowledge of our readers. It is not designed to be, and should not be used as, the sole source of information when analyzing and resolving a legal problem, and it should not be substituted for legal advice, which relies on a specific factual analysis. Moreover, the laws of each jurisdiction are different and are constantly changing. This information is not intended to create, and receipt of it does not constitute, an attorney-client relationship. If you have specific questions regarding a particular fact situation, we urge you to consult the authors of this publication, your Holland & Knight representative or other competent legal counsel.