Commonly abbreviated AST, an aboveground storage tank is a storage tank that is aboveground, regardless of whether they are used for to store petroleum products, hazardous waste, or other hazardous material.
Aboveground storage tanks (ASTs) used for the store of petroleum products is regulated primarily under 40 CFR 112. The regulation does not actually use the terms "aboveground storage tank." Instead the term "bulk storage container" is used and is defined as "any container used to store oil. These containers are used for purposes including, but not limited to, the storage of oil prior to use, while being used, or prior to further distribution in commerce. Oil-filled electrical, operating, or manufacturing equipment is not a bulk storage container."
A bulk storage container is 55 gal. or greater and may be aboveground, partially buried, bunkered, or completely buried. "Bunkered tanks" are defined as "a container constructed or placed in the ground by cutting the earth and re-covering the container in a manner that breaks the surrounding natural grade, or that lies above grade, and is covered with earth, sand, gravel, asphalt, or other material. A bunkered tank is considered an aboveground storage container for purposes of 40 CFR 112"