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1.0 EXCAVATION AND BEDDING <br />1.1 The bottom of the excavation shall be covered <br />with a minimum of 12 inches (305 mm) of <br />bedding, suitably graded and leveled. Bedding <br />and backfill material surrounding the tank, to a <br />width and depth of 12 inches (305 mm) all <br />around the tank, shall be clean material. <br />1.2 Where anchoring by means of a concrete pad, <br />the tank shall not be placed directly on the pad. <br />Bedding material at least 6 Inches (152.4 mm) <br />deep must be spread evenly over the <br />dimensions of the pad to separate the tank from <br />the pad. <br />1.3 Bedding and backfill material shall consist of pea <br />gravel, crushed stone, dean sand or natural <br />earthen materials. Crushed stone, dean sand <br />and natural earthen materials shall be capable of <br />passing 100° through a 1/2 inch (13 mm) sieve <br />and no more than 12% by dry weight through a <br />#200 sieve (0.0029 inch (0.0754 mm)), Pea <br />gravel shall be no larger than 3/4 -inch (19 mm). <br />The materials shall be free of all foreign <br />materials, such as but not limited to, bricks, <br />metals, concrete and plastics. <br />1.4 The backfill material may be from the tank site if <br />it meets this description, or it may be delivered to <br />the site from another source. <br />1.5 Sand or natural earthen materials used as <br />backfill shall be placed into the excavation in 12- <br />18 Inch (305-458 mm) vertical lifts, compacted <br />after each lift, at least 60% up the vertical height <br />of the tank. <br />l <br />1.6 If earthen material from the site, or other earthen <br />material, is to be used as bedding or backfill <br />material, a minimum of four 1 cu,ft, samples shall <br />be taken from different locations which are <br />representative of the backfill material and the <br />site. Samples shall be sieved to determine if the <br />material complies with this specification. <br />1.7 In a tidal area, the tank "bedding" material shall <br />be crushed stone or pea gravel. Sand and <br />natural earthen material may be used only if <br />measures are taken to prevent washout of., <br />material during the design life of the syste6i. <br />r <br />2.0 AIR TEST AT JOB SITE 1. <br />2.1 Temporary plugs and thread protectors Installed <br />by the manufacturer shall be removed. Apply <br />compatible, non -hardening pipe sealant to <br />internal bushing threads. Permanent metal <br />plugs shall be installed at all unused openings. <br />2.2 The nylon bushings in the tanks shall not be <br />removed from the unused openings. Plugs used <br />to temporarily seal the tank for the aboveground <br />air test, but later removed for pipe installation, <br />shall not be over -tightened. Do not cross thread <br />or damage the nylon bushings when replacing <br />plugs or installing required tank piping. <br />2.3 Test pressure shall be maintained at, without <br />exceeding, 5 psig (34.5 kPa) while a soap;' <br />solution is applied to the area of pipe <br />connections and welds. <br />1 (6 <br />