5706.4.5.3 Height of aboveground storage tanks.

The maximum height of aboveground flammable and combustible liquid storage tanks shall not exceed 40 feet (12 192 mm).

   Exception: Aboveground vertical cylindrical tanks storing combustible liquids shall not exceed 48 feet (14 630 mm) in height.

5706.4.5.4 Distance from aboveground tanks to buildings.

The distance between any part of an aboveground storage tank and buildings or structures used for housing of fire extinguishing equipment, central heating plant or electrical distribution equipment shall not be less than 50 feet (15 240 mm).

5706.4.5.5 Maximum capacity for aboveground tanks.

The maximum capacity of any aboveground tank used for storage of a flammable liquid shall not exceed 500,000 gallons (1892 500 L). The maximum capacity of any aboveground tank used for storage of combustible liquid shall not exceed 6,000,000 gallons (22 710 000 L).

5706.4.5.6 Distance from aboveground tanks to exposures.

No aboveground tank shall be installed within:

   1.   1,000 feet (304 800 mm) of the nearest wall of a building occupied as a school or hospital, or an entrance to or exit from a tunnel for motor vehicles, subway or railroad trains, or the ventilating buildings or shafts of such tunnels.

   2.   250 feet (76 200 mm) of any point under a bridge for pedestrians, motor vehicles, subway or railroad trains, a public park or a land zoned for residential purposes.

5706.4.5.7 Depth of underground storage tanks.

The maximum distance between the top and bottom plates of an underground flammable and combustible liquid storage tank shall not exceed 40 feet (12 192 mm).

5706.4.5.8 Underground tank location.

Underground tanks shall be located such that the top plate thereof shall be at least 2 feet (610 mm) below the established grade. No such tank shall be buried within 10 feet (3048 mm) of any building or adjoining property line. Individual underground tanks shall be covered with 2 feet (610 mm) of earth or 4 inches (102 mm) of reinforced concrete extending 10 feet (3048 mm) beyond all the vertical walls of the tank, and the excavation made to receive the tank shall be backfilled with well-compacted clean sand or earth, free of any ash or other corrosive substance, and free from stones larger than will pass through a 1-inch (25-mm) mesh. Underground tanks may be erected in groups of 2 or more, when such tanks are separated by a space of 1 foot (305 mm), and provided the reinforced concrete top cover extends unbroken over the open space between the tanks.

5706.4.5.9 Mounded-over tanks.

Mounded-over tanks shall be considered underground tanks. A mounded-over tank may be erected with its base at any desired elevation not higher than the grade plane of the premises. It shall be enclosed with a steel, reinforced-concrete, or closed-face-concrete cribbing wall extending from the established grade to the top of the top cover, with the exterior face of the wall at least 10 feet (3048 mm) from the exterior face of the wall of the tank, and backfilled between the tank and the enclosing wall with compacted clean earth or sand containing no ash or other corrosive substance. The wall and backfill may be replaced with compacted similar fill, extending from the established grade to the level of the top cover on the tank, at the normal angle of repose of the material so used, with the provision that the width of the sloped material at the level of the top of the top cover shall be at least 10 feet (3048 mm) wide. When two or more mounded-over tanks, either rectangular or vertical-cylindrical, are grouped together, the tanks shall be at least 1 foot (305 mm) apart from each other, and the group of tanks shall be enclosed around the periphery with the same type of wall and backfill described above for one mounded-over tank.