Underground storage means storage of hazardous liquid in a subsurface stratum or formation of the earth.
Underground storage tank system means an underground storage tank and the connected underground piping, underground ancillary equipment, and containment system, if any.
Underground area means an underground room, such as a basement, cellar, shaft or vault, providing enough space for physical inspection of the exterior of the tank situated on or above the surface of the floor.
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:
Underground mining means all methods of mining other than surface mining.