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r <br />. r PIPING <br />r .. <br />Before the piping system is backfilled, it must be isolated <br />from the tanks and subjected to a pipe tightness test on <br />the primary and secondary piping. <br />For tightness testing of DoubleTrac® flexible piping, the <br />primary piping is pressurized with air to a level of 1.5 <br />times the maximum operating pressure of the system. <br />Maintain this pressure for a minimum of one hour, making <br />sure there is no drop in pressure. <br />SECTION 10.0—INSTALLATION OF CHECK VALVES <br />Once all testing has been completed, remove body of <br />Schrader valve and thread on check valve to Schrader <br />valve. The arrow on the check valve should point away <br />from the fitting. <br />NOTE: If check valves are not installed, then the plug which <br />originally came with the fitting must be installed. Prior <br />to releasing for service, either a plug or check valve <br />must be installed. Failure to do so voids all warranty. <br />SECTION 11.0—PIPE BURIAL, TRENCHING AND <br />BACKFILL REQUIREMENTS <br />Provide a trench width equal to the pipe diameter plus <br />six inches on each side. Separate multiple lines by at <br />least 4 inches. The distance between any piping and the <br />trench excavation walls must be at least 6 inches. For <br />example, an installation of three 2" diameter pipes, the <br />trench would be 26" wide and a minimum of 26" deep. <br />Whenever possible, product lines should be run in a <br />single trench between the tank area and pump dispenser <br />island area. Vent lines between the tank and the structure <br />to which the aboveground vent lines are attached should <br />also be installed in a single trench. Where more than one <br />trench is required, piping should not cross over each <br />other or cross over underground, above ground and <br />marina tanks. <br />The trench bottom must be sloped uniformly from the <br />dispensers back to the tanks or sumps at a minimum <br />slope of 1/8 inch per foot and be free of any sharp or <br />protruding hard objects. The trench bottom must be <br />graded with a minimum of six inches of backfill such as <br />washed sand, or pea gravel. <br />For backfilling, provide a minimum level of clean backfill <br />between the top of the pipe and the surface as provided <br />in Table 6. <br />Table 6 <br />Page 7 <br />Native back fill materials should never be used. <br />ENVIRONMENTAL HEALTE <br />DEpARTMENT <br />