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0 DEPTH OFEXCAV&N <br />The hole must be deep enough to provide sufficient <br />bedding and cover depth as determined by the type of <br />surface pavement and loading. NFPA 30 and 31 should <br />be consulted as well as local codes. <br />Tanks subjected to <br />traffic loads must have <br />a cover depth of at <br />least 30 inches (75cm) <br />of backfill plus 6 inches <br />(15cm) of asphalt. An <br />acceptable alternative <br />is a minimum of 18 <br />inches (45cm) of <br />backfill plus 6 inches <br />(15cm) of steel re -bar <br />reinforced concrete. <br />Tanks subjected to <br />traffic loads and high <br />water must have a <br />minimum of 30 inches <br />(75cm) of backfill and <br />either 8 inches (20cm) <br />of asphalt or 6 inches <br />(15cm) of steel re -bar <br />reinforced concrete. <br />Tanks not subjected to <br />traffic loads must have <br />f a minimum cover <br />depth of 24 inches <br />(6Ocm) of backfill, or 12 <br />inches (30cm) backfill <br />plus 4 inches (10cm) <br />of steel re -bar rein- <br />forced concrete. <br />Tanks in high water <br />areas not subjected to <br />traffic loads must have <br />a minimum of 36 <br />inches (92cm)`,of <br />backfill covering. <br />8" 6, <br />f' - <br />30 E �T WETIC\ <br />CONDITIONS rTe <br />NOTE: These depths of cover are MINIMUMS for high water areas <br />without traffic over the tank. <br />NOTE: Asphalt and concrete pads must extend a minimum of 12 inches <br />(30cm) beyond tank in all directions. <br />NOTE: Maximum burial depth is 7 feet (2.1 meters) of cover over top <br />of tanks up to 20,000 gallons (76 cu. meters) in size. <br />© EXCAAON SIZE <br />Where shoring is not required to maintain a vertical wall <br />from top to botfom of the excavation, the minimum <br />spacing between the sidewall or endcap of the tank and <br />side of excavation must be 24 inches (60cm). <br />If more than one tank is to be installed in the same hole, <br />there must be at least 24 inches (60cm) between the <br />tanks. <br />If the soil has less than 750 lbs/sq. ft. cohesion as cal- <br />culated from an unconfined compression test; or in soils <br />having an ultimate bearing capacity of less than 3500 <br />lbs/sq. ft.; or where soil will not maintain a vertical wall, <br />the excavation must allow a minimum space equal to 1/2 <br />the diameter of the tank between the side and endcap <br />of the tank and the excavation wall. The spacing be- <br />tween adjacent tanks, 24 inches (60cm), remains the <br />same_ <br />