56.4430—Storage facilities.
(1)
Capable of withstanding working pressures and stresses and compatible with the type of liquid stored;
(4)
Vented or otherwise constructed to prevent development of pressure or vacuum as a result of filling, emptying, or atmospheric temperature changes. Vents for storage of Class I, II, or IIIA liquids shall be isolated or separated from ignition sources. These pressure relief requirements do not apply to tanks used for storage of Class IIIB liquids that are larger than 12,000 gallons in capacity.
(c)
Fixed, unburied tanks located where escaping liquid could present a hazard to persons shall be provided with—
(2)
Drainage of a remote impoundment area that does not endanger persons. However, storage of only Class IIIB liquids does not require containment or drainage to remote impoundment.