Underground storage tank
Underground storage tank or UST means any one or combination of tanks (including underground pipes connected thereto) that is used to contain an accumulation of regulated substances, and the volume of which (including the volume of underground pipes connected thereto) is 10 percent or more beneath the surface of the ground. This term does not include any:
(1) Farm or residential tank of 1,100 gallons or less capacity used for storing motor fuel for noncommercial purposes;
(2) Tank used for storing heating oil for consumptive use on the premises where stored;
(3) Septic tank;
(4) Pipeline facility (including gathering lines):
(i) Which is regulated under 49 U.S.C. chapter 601; or
(ii) Which is an intrastate pipeline facility regulated under state laws as provided in 49 U.S.C. chapter 601, and which is determined by the Secretary of Transportation to be connected to a pipeline, or to be operated or intended to be capable of operating at pipeline pressure or as an integral part of a pipeline;
(5) Surface impoundment, pit, pond, or lagoon;
(6) Storm water or wastewater collection system;
(7) Flow-through process tank;
(8) Liquid trap or associated gathering lines directly related to oil or gas production and gathering operations; or
(9) Storage tank situated in an underground area (such as a basement, cellar, mineworking, drift, shaft, or tunnel) if the storage tank is situated upon or above the surface of the floor.