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0 Xeres tanks must be installed using either pea gravel or crushed stone which meets the following specifications. GENERAL: The material is washed, free flowing and free of ice, snow and debris. It conforms to the specification of ASTM C-33 par. 9.1, sizes 6 through 8. No more than 5%< (by weight) of the material may pass through a #8 sieve. It is recommended that the supplier certify that the material conforms to ASTM C-33 and any other applicable specifications. (For additional information, refer to the Xeres pamphlet Fiberglass Tank Backfill Guidelines.) PEA GRAVEL CRUSHED STONE FIGURE 3-1 FIGURE 3-2 PEA GRAVEL: Mix of rounded particles - sizes between 1/8" and 3/4". CRUSHED STONE: Mix of angular particles - sizes between 1/8" and 1/2". NOTE: If material which meets these specifications is not available, contact the Xerxes Technical Service Department for information on approved alternate materials and installation instructions. Using other than approved bedding and backfill materials without Xerxes prior written approval will void the tank warranty and may result in tank failure. The installing contractor must take all precautions necessary to protect employees working in or near a tank excavation. These precautions should include, but are not limited to: • Location and protection of any utility installations near the excavation before opening the excavation; • Means of securing the walls of the excavation; • Means of preventing exposure of employees to hazardous fumes from the excavation; • Protection of employees from hazards associated with water accumulation in the excavation; • Barricades, etc. to prevent unauthorized vehicle or pedestrian traffic; • Inspection of the excavation and surrounding area at least daily. For additional information on excavation, trenching and shoring safety practices, consult OSHNs Construction Industry Standards Part 1926, Subpart R The minimum depth of the excavation is normally determined by the presence or absence of groundwater and the presence or absence of traffic at the site. These dimensions are critical to the successful installation of a tank and are often regulated by code. 0 Refer to: • federal, state and local codes • NFPA 30 & API 1615 • figures 4-1 to 4-4 below. NOTE: Numbers in brackets [ [ refer to 12 foot tanks. FIGURE 4.1 Tanks subjected to traffic loads must have a cover depth of at least 18 [36] inches of backfill plus 9 inches of asphalt. An acceptable alternative is a minimum of 18 [36] inches of backfill plus 6 inches of reinforced concrete. FIGURE 4-2 NOTE: Numbers in brackets [ refer tot 2 foot tanks. Tanks subjected to traffic loads and high water must have a minimum of 30 [36] inches of backfill and either 9 inches of asphalt or 6 inches of reinforced concrete. NOTE: Numbers in brackets [ refer to 12 foot tanks. FIGURE 4-3 Tanks not subjected to traffic loads must have a minimum cover depth of 24 [48] inches of backfill, or 12 [36] inches of backfill plus 4 inches of reinforced concrete or 6 inches of asphalt. FIGURE 4-4 NOTE: Numbers in brackets [ 1 refer to 12 foot tanks. Tanks in high water areas not subjected to traffic loads must have a minimum of 36 [48] inches of backfill covering.