Storage tank
Storage tank means a stationary unit that is constructed primarily of nonearthen materials (such as wood, concrete, steel, or reinforced plastic) that provide structural support and is designed to hold a bulk quantity of liquid. Storage tanks do not include: (1) Units permanently attached to conveyances such as trucks, trailers, rail cars, barges, or ships; (2) Pressure vessels designed to operate in excess of 204.9 kilopascals and without emissions to the atmosphere; (3) Bottoms receivers; (4) Surge control vessels; (5) Vessels storing wastewater; or (6) Reactor vessels associated with a manufacturing process unit.