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What Is An Underground Storage Tank System?

An underground storage tank (UST) system is a tank (or a combination of tanks) and connected piping having at least 10 percent of their combined volume underground. The tank system includes the tank, underground connected piping, underground ancillary equipment, and any containment system. The federal UST regulations apply only to underground tanks and piping storing either petroleum or certain hazardous substances.

The following types of tanks do not have to meet federal UST regulations:

However, some implementing agencies may include these tank types in their UST regulations. Be sure you check with these authorities if you have questions about the requirements for your tank type.

Other storage sites, such as surface impoundments, pits, ponds or lagoons are not covered by the federal UST requirements.

For more detailed information on the applicability of federal UST requirements for different types of USTs, please refer to Subpart A of Part 280 of the Code of Federal Regulations (CFR).

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