The federal requirements for closing your UST vary based on the length of the closure. Below are the requirements for both a temporary UST closure and a permanent UST closure.

Temporary Closure. You may temporarily close your UST for up to 12 months by following these requirements:

• Continue to monitor for leaks by maintaining the UST's leak detection. (If your UST is empty, you do not need to maintain testing or inspections for release detection.) Also, continue to monitor and maintain corrosion protection systems.
• If the UST remains temporarily closed for more than 3 months, leave vent lines open, but cap and secure all other lines, pumps, manways, and ancillary equipment.

After 12 months of temporary closure, UST owners have the following options:

• Permanently close the UST if it does not meet the applicable requirements for new or upgraded USTs (except for spill and overfill).
• Request your regulatory authority to grant an extension beyond 12 months if you provide an assessment that determines whether contamination is present at your site.
• Allow the UST to remain temporarily closed without an extension granted by the regulatory authority if the UST meets the applicable requirements for new or upgraded USTs (except for spill and overfill) and the preceding requirements.

Permanent Closure. The owner or operator must meet the following requirements for permanent closure:

• Notify authorities 30 days before closure provided in 40 Code of Federal Regulations (CFR) 280.71.
• Determine if leaks from the tank have damaged the environment, using the results of monthly vapor or groundwater monitoring or a site assessment. If there is damage, the owner or operator will be required to take corrective action under 40 CFR 280.72.
• Empty and clean the tank. If the tank is left in the ground, it must be filled with an inert solid material (e.g., sand) or closed in place in a manner approved by the implementing agency.

Governing laws and regulations:
40 CFR 280.70 to 40 CFR 280.71