(a) Underground steel storage tanks with STI-P3 or equal corrosion control system tanks shall bear U.L. Label and be in conformance with Underwriters Laboratories.
(1) The excavation shall be free from material that may cause damage to the tank coating. (Care shall be taken during installation that foreign matter is not introduced into the excavation of backfill.)
(2) The bottom of the excavation shall be covered with clean sand or gravel to a depth of one foot, suitably graded and leveled.
(3) The excavation shall extend a distance of at least one foot around the perimeter of the tank.
(4) An air test of the tank aboveground is required. Pressure should not exceed five pounds per square inch (PSIG) while a soap solution is applied to weld seams.
(5) Before placing the tank in the excavation, all dirt clods and similar foreign matter shall be cleaned from the tank, and areas of coating damages shall be repaired with a suitable coating.
(6) Equipment to lift the tank shall be of adequate size to lift and lower the tank without dragging and dropping to ensure no damage to the tank or the coating.
(7) Tanks shall be carefully lifted and lowered by use of cables or chains of adequate length (not less than forty-five degrees included angle) attached to the lifting lugs provided. A spreader bar should be used where necessary. Under no circumstances use chains or slings around the tank shell.
(8) Where anchoring by means of a concrete slab is required, tanks shall be separated from the slab by at least six inches of sand and gravel. Under no circumstances shall the tank be set directly on the concrete slab, nor shall the tank be placed on any other hard or sharp material that can cause deformation of the tank or damage to the coating.
(9) Anchor straps and ground anchors, if required, shall be installed in such a manner that they do not damage and shall be electrically isolated from the protective coating of the tank.
(10) Backfill consisting of clean sand, gravel, or other noncorrosive inert materials shall be placed along bottom sides of tank by hand shoveling and tamping to ensure that the tank is fully and evenly supported around bottom quadrant.
(11) The backfill shall be deposited carefully around tank and to a depth of at least one foot over tank to avoid damage to coating especially where tamping is required. (See N.F.P.A. 30 and state or local codes for depth of coverage required.)
(12) Hydrostatic testing is required after installation, it is recommended that the pressure applied shall not be in excess of five pounds per square inch (PSIG) as measured at the top of the tank.
(13) The plugs at unused tank openings shall be removed, a pipe compound shall be added and the plugs shall be reinstalled in the unused opening.
(14) The di-electric bushings in STI-P3 tank, or equal to shall not be removed from the unused openings. The plugs in tank openings which are to be used should not be overtightened as this may cause the bushing to unscrew with the plug. Care shall be taken not to cross-thread or damage the nonmetallic bushings when replacing plugs or installing required tank piping.
(Ord. 21-1989. Passed 6-6-89.)