1. (a) The temporary closure requirements of this section apply to underground storage tanks where the storage of hazardous substances has ceased but the underground storage tank will be used for the storage of hazardous substances again within the 12 consecutive months after temporary closure begins.
2. (b) At least 30 days prior to temporary closure, or within a shorter period of time if directed by the Unified Program Agency, an owner or operator who intends to temporarily close an underground storage tank system must provide to the Unified Program Agency for approval a proposal for compliance with this section. The owner or operator must receive approval for temporary closure from the Unified Program Agency prior to initiating temporary closure. Until temporary closure has been approved, the owner or operator must continue to meet the applicable construction, monitoring, testing, and operating permit requirements of articles 4, 5, 6, and 9.
3. (c) An underground storage tank that has had a release does not qualify for temporary closure unless the owner or operator has demonstrated to the satisfaction of the Unified Program Agency that appropriate authorized repairs have been made which make the underground storage tank capable of storing hazardous substances in accordance with this chapter.
4. (d) Monitoring required pursuant to the operating permit may be modified during the temporary closure period with approval by the Unified Program Agency.
5. (e) The owner or operator of an underground storage tank system in temporary closure must continue to comply with corrosion protection requirements, repair and recordkeeping requirements, release reporting and investigation requirements, and release response and corrective action requirements specified in this chapter and chapter 6.7 of division 20 of the Health and Safety Code.

6. (f) The owner or operator must comply with all the following requirements to qualify for temporary closure:

   1. (1) All residual liquid, solids, and sludge must be removed and handled in accordance with the applicable provisions of chapters 6.5 and 6.7 of division 20 of the Health and Safety Code.
   2. (2) If the underground storage tank contained a hazardous substance that could produce flammable vapors at standard temperature and pressure, if required by the Unified Program Agency, it must be inerted as often as necessary to levels that will preclude an explosion or to lower levels as required by the Unified Program Agency.
   3. (3) The underground storage tank may be filled with a noncorrosive liquid that is not a hazardous substance. Before removal of such liquid from the underground storage tank at the end of the temporary closure period, the liquid must be tested, and the test results must be provided to the Unified Program Agency.
   4. (4) Except for required venting, all fill and access locations and piping must be sealed using locking caps.
   5. (5) Power service must be disconnected from all pumps associated with the use of the underground storage tank. The power supply to equipment that the Unified Program Agency requires to remain in service during temporary closure, such as release detection equipment, or an impressed-current cathodic protection system, must remain connected.

7. (g) The underground storage tank must be inspected by the owner or operator at least once every 90 days to verify that the temporary closure requirements in subdivision (f) still are in place. The inspection must include, but is not limited to, the following:

   1. (1) Visual inspection of all locked caps;
   2. (2) At least one locked cap must be removed to determine if any liquids or other substances have been added to the underground storage tank or if there has been a change in the quantity or type of liquid added pursuant to subdivision (f)(3);
   3. (3) If applicable, verifying that the tank is inerted; and
   4. (4) Documenting the results of the inspection. Documentation must be made available within 36 hours at the request of the Unified Program Agency.
8. (h) At the end of 12 consecutive months, the Unified Program Agency may approve an extension of the temporary closure period for a maximum additional period of 12 months. The maximum consecutive period of time an underground storage tank system may be in temporary closure is 24 months. The Unified Program Agency only may grant an extension for temporary closure if the conditions for temporary closure specified in subdivisions (f) and (g) remain in effect and the owner or operator performs sampling in accordance with section 2681(g).
9. (i) At the end of temporary closure, the owner or operator may put the underground storage tank system back into operation only if it meets the requirements of chapter 6.7 of division 20 of the Health and Safety Code and the construction, monitoring, and testing requirements of articles 4, 5, and 6.
10. (j) The owner or operator must update all applicable data elements in the California Environmental Reporting System or local reporting portal within 30 days of the beginning and the end of the temporary closure period in accordance with section 2613(b).

Note: Authority cited: Sections 25299.3 and 25299.7, Health and Safety Code. Reference: Sections 25298 and 25404, Health and Safety Code; and 40 CFR Sections 280.70 and 281.36(a).

History

1. Amendment of section heading and subsections (a) and (b) filed 8-9-91 as an emergency; operative 8-9-91. Text remains in effect uninterrupted pursuant to Health and Safety Code section 25299.7 (Register 92, No. 14).

2. Editorial correction of printing errors in History 1 (Register 92, No. 43).

3. Amendment of article heading, section heading and text filed 4-5-94; operative 5-5-94 (Register 94, No. 14).

4. Repealer and new article 8 heading, section heading and section filed 10-28-2025; operative 1-1-2026 (Register 2025, No. 44).