Storage tank means a stationary unit that is constructed primarily from nonearthen materials (such as wood, concrete, steel, fiberglass, or plastic) which provides structural support and is designed to hold an accumulation of liquids or other materials used in or generated by a semiconductor manufacturing process unit. The following are not storage tanks for the purposes of this subpart:
(1) Tanks permanently attached to motor vehicles such as trucks, railcars, barges, or ships;
(2) Flow-through tanks where wastewater undergoes treatment (such as pH adjustment) before discharge, and are not used to accumulate wastewater;
(3) Bottoms receiver tanks; and
(4) Surge control tanks.
40 CFR § 63.7195
Terms used in this subpart are defined in the Clean Air Act, in 63.2 and 63.981, the General Provisions of this part (40 CFR part 63, subpart A), and in this section as follows: