15-24-280 Underground and enclosed tanks.

   Construction Materials. Underground and enclosed tanks for flammable liquids shall be constructed of galvanized steel, or open hearth steel, or of wrought iron of thickness and weight not less than provided in the following table:

Capacity (Gallons)	Minimum Thickness of Materials
	U.S. Standard Gauge	Pounds Per Sq.Ft.
1 to 285	16	2.5
286 to 560	14	3.125
561 to 1,100	12	4.375
1,101 to 4,000	7	7.5
4,001 to 12,000	1/4 in.	10
12,001 to 20,000	5/16 in.	12.5

 

   Any tank built in accordance with Underwriters' Laboratories Standard 172 shall be acceptable.

   All material used in underground and enclosed storage tanks, for which material is lighter than No. 7 U. S. Standard gauge shall be galvanized. If internal bracing is provided, tanks for the storing of Class III liquids, having a capacity of from 12,001 to 30,000 gallons, shall be built of steel plate not less than one- fourth-inch thick. All joints of tanks shall be riveted and caulked, brazed or welded. Underwriters' Laboratories, Inc. labeled or any other nationally recognized testing laboratories approved glass-fiber reinforced plastic tanks may be used for underground storage of flammable liquids. Tanks shall be tight and sufficiently strong to bear without injury the most severe strains to which tanks are subjected. Shells of tanks shall be properly reinforced where connections are made. All connections shall be made through the top of the tank above the liquid level. Tanks and systems under pressure shall be designed for four times the maximum working pressure. All iron or steel tanks shall be coated on the outside with tar or asphaltum or heavy protective paint. All concrete tanks shall be constructed in accordance with the provisions of Chapter 13-136 of this Code. Compartmented tanks shall not be permitted. Inlet openings for flammable liquid tanks inside buildings shall be piped down to four inches from the bottom of the tank unless they are equipped with a trap. Gauging openings inside of buildings shall not be permitted.

   All enclosed and underground tanks when installed shall be tested to a pressure equal to the static head of the height of the vent, but not smaller than five psi. Such test shall be held for not less than 30 minutes without loss of air of more than ten percent air pressure drop. When it is necessary to test such tank to a pressure of more than five psi, the test shall be of hydrostatic nature utilizing water. Pressure tanks shall be tested to one and one-half times their working pressure.

   Covering for Metal Tanks. All flammable liquid tanks buried underground shall have the top of the tank not less than two feet below the surface of the ground except in lieu of such covering, tanks may be buried under not less than 12 inches of earth, with a cover of reinforced concrete not less than six inches in thickness provided over such tanks, which shall extend not less than one foot horizontally beyond projected limits of the tanks in all directions. All concrete work shall be in accordance with Chapter 13-136 of this Code. Where tanks are liable to be displaced because of moisture in the ground, all tanks shall be securely anchored or weighted. Where tanks are located under driveways, such tanks shall not be less than three feet below the top surface of the driveway; provided, however, that if such driveways are paved with concrete not less than six inches in thickness, the total coverage above the top of the tank shall be not less than two feet.

   Covering for Underwriters' Laboratories, Inc. Labeled Glass-fiber Reinforced Plastic Tanks.

      Depth and Cover. Glass-fiber reinforced plastic tanks shall be set upon firm earth which has not been previously disturbed and may be set on a minimum of six inches of number 4 run gravel or sand. Glass-fiber reinforced plastic tanks shall be buried with two and one-half feet of compacted well graded granular soil, number 4 run gravel or sand, with a cover of reinforced concrete not less than six inches in thickness provided over such tanks, which shall extend not less than one foot horizontally beyond the projected limits of the tank in all directions, a minimum clearance of eighteen inches between tanks. When anchoring is required, hold down straps shall be installed. A minimum clearance of two inches between bottom end of pipe and tank bottom shall be maintained. Dipstick shall be made of wood without sharp tips. Means shall be provided not to allow dipstick to reach bottom of tank.

      Capacity. The individual capacity of underground tanks is limited in respect to the lowest floor, basement or lot line as given in the following table:

	Class I	Class II and III Gallons
If top of tank is above the lowest floor, basement or part of any building with a clearance of 10 feet or less	550	50,000
More than 10 feet	551 to 2,000	50,001 to 75,000
More than 20 feet	2,001 to 5,000	75,001 to 100,000
More than 25 feet	5,001 to 15,000	100,001 to 150,000
More than 30 feet	15,001 to 20,000	150,001 to 200,000
More than 40 feet	20,001 to 50,000	200,001 to 500,000
More than 50 feet	Unlimited	Unlimited

 

      Clearances on the side adjacent to a public street or alley may be waived.

      The capacity of any tank containing flammable liquid of Class I shall not exceed 15,000 gallons in any filling station.

      Distance from sewers, conduits and vaults shall be the same as outlined in the above table. When said sewer, conduits, or vault are below the top of the tank, the term “sewer” includes a line out of the said site; provided, however, these clearances shall not be required from a sewer line out of said site if such sewer is constructed of cast iron with hot poured lead joints.

   Abandonment or Removal of Underground Tanks. Underground tanks taken out of service shall be disposed of by any one of the three following means:

   (a)   Being placed in “temporarily out of service” condition; provided, however, that no temporarily out of service tank shall be built upon;

   (b)   Abandoned in place; or

   (c)   Removed.

   Tanks Rendered “Temporarily Out of Service”.

      “Tanks rendered ‘Temporarily Out of Service”' means flammable liquid storage tanks which are temporarily not being used for a period of time less than six months.

      (a)   Remove all flammable liquid that can be pumped out with the service pump;

      (b)   The fill line, gauge hatch and pump suction shall be capped and secured against tampering;

      (c)   The vent line shall be left open.

   Abandoning Underground Tanks in Place.

      (a)   Remove all flammable liquid from tank and from all connecting lines;

      (b)   The suction, inlet, gauge and vent lines shall be disconnected;

      (c)   The tank shall be flooded with water, pumped out and then filled with an inert solid material;

      (d)   Remove all connecting lines below ground level, and cap or plug all tank openings below ground level.

   Removal of Underground Tanks.

      (a)   Remove all flammable liquid from tank and connecting lines;

      (b)   Disconnect the suction, inlet, gauge and vent lines;

      (c)   The tank shall be flushed with water and cleaned until rendered gas-free as indicated by combustible gas indicator;

      (d)   If a tank is to be disposed of as junk, it shall be retested for explosive vapors, and rendered gas- free. Before releasing to a junk dealer, a sufficient number of holes or openings shall be made at the bottom of the tank. The net cross-sectional area for such holes shall not be less than 78 square inches per tank;

      (e)   The tank shall be removed immediately from said site.

   Prohibition of Abandonment of Aboveground Flammable Liquid Tanks.

      (a)   Abandoned aboveground flammable liquid tanks shall be removed. The tank shall be flushed with water and cleaned until rendered gas-free as indicated by a combustible gas indicator.

      (b)   The tank shall be dismantled and junked. If in one piece before releasing to a junk dealer, a sufficient number of holes or openings shall be made in the tank. The net cross-sectional area for such holes shall not be less than 78 square inches per tank.

(Prior code §  129.1-22)