§ 47-9. Underground tanks.

A. 

Underground tanks shall be buried with their tops not less than two feet below the surface of the ground and below the level of any piping to which the tanks may be connected, except that, in lieu of the two-foot cover, such tank may be buried under 12 inches of earth and a cover of reinforced concrete at least one foot beyond the outline of the tank in all directions. Such concrete slab shall be set on a firm, well tamped, earth foundation. Underground tanks shall be securely anchored or weighted in place to prevent floating, where condition, warrant.

B. 

If such tanks cannot be set below the level of all piping to which it is connected, satisfactory arrangements shall be provided to prevent siphoning or gravity flow in case of accident to piping.

C. 

When buried underneath a building, the tank shall be buried with top of tank not less than two feet below the level of the floor. The floor immediately above such tank shall be of reinforced concrete of at least six inches in thickness (for tanks of 1,500 gallons or less, four inches in thickness), or some other type of construction of equivalent strength and fire resistance, extending at least one foot beyond the outline of the tank in all directions and provided with ample means of support, independent of the tank.