If the UST system remains in temporary closure for 90 days or more, the owner/operator must leave the vent lines open and functioning, cap and secure all other lines, pumps, manways, and ancillary equipment, and empty the UST so that no more than one inch of residue remains in the system. The owner/operator will also need to obtain an out-of-service permit, unless the 90 days is part of a scheduled seasonal disuse and the owner/operator has obtained written approval from the state fire marshal.
Permanent removal of a UST system must comply with the following requirements.
- Prior to removal, the UST must be checked to ensure that no explosive vapors have accumulated in the UST.
- All liquid and residue must be removed from the UST prior to removal.
- The UST must be rendered unusable and free of explosive vapors before it leaves the site. This can be accomplished by cutting up, crushing or perforating the UST using explosion-proof non-sparking tools.
- All backfill from the tank cavity excavation, piping trenches, dispensing unit areas, and remote fill pipe trenches must be removed.
- No more than 12 inches of native soil may be removed from the excavation area.
- Backfill and native soil removed from the excavation area may be stored on site for up to 120 days if it has been placed on a concrete pad, asphalt pad, or impermeable synthetic liner, covered to prevent infiltration of rain water, and has been surrounded by a berm to minimize water run-off.
If a UST is temporarily closed for more than twelve months, it must be either returned to service or permanently closed. At least 30 days prior to permanently closing the UST, the owner/operator must notify the state fire marshal’s office of the intent to close the UST. When a tank has been permanently closed, it must undergo a change-in-service, be emptied and removed, or be closed-in-place.
To undergo a change-in-service, the UST must be completely emptied and cleaned and all piping and ancillary equipment that is not part of the change-in-service must be closed-in-place or removed.
Closure-in-place must be approved in writing by the state fire marshal or a certified fire safety inspector with delegated authority. Closure-in-place will only be allowed if:
- Removing the UST will damage or weaken adjacent equipment or structures;
- The UST is situated in a location where removal is physically impossible; or
- Removal of the UST will expose people or the environment to unreasonable hazards.
The UST must be filled with an inert solid material with a density greater than the density of water.
If a UST or any portion of the UST system is removed, undergoes a change-in-service, is closed-in-place, is out-of-service for more than twelve months without an approved extension, or is out-of-service for more than the approved out-of-service period, the owner/operator will be required to conduct a closure assessment. The closure assessment will include:
- A visual evaluation of the UST site to identify evidence of past or present operational problems;
- Collection of soil samples for laboratory analysis; and
- Collection of water samples (in cases of permanent removal) for laboratory analysis.
Within 90 days of completing the closure assessment, the owner/operator must submit a written closure report to the state fire marshal.