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Piping system layoute Trenching,bedding and backfilling 6Although fiberglass pipe has excellent strength,it roust be protected against impact which may occur from improper handling or during backfilling. • Provide a trench width equal to the pipe diameter plus six inches on each side. Separate multiple lines by at least 4 inches.Referto Fig.6-1. • Provide a minimum of 18 inches of select backfill between the top of the pipe and unpaved ground surfaces. • Provide a minimum of 4 inches of select backfill between the top of the pipe and reinforced concrete pavement(4 inches minimum thickness). • Provide a minimum of 8 inches of select backfill between the top of the pipe and asphalt pavement(2 inches minimum thickness). • Slope the trench bottom evenly from the dispensers back to sumps or tanks at a minimum t/a iii of slope. • The trench bottom must be free of hard or sharp objects. • Grade the trench bottom with at least 6 inches of select backfill to provide firm, even support for the pipe.Compact the subgrade well to prevent differential settling. • Protect the pipe from impact during backfilling and abrasion during operation by surrounding it with four to six inches of select backfill such as washed sand,pea gravel(3/4-inch maximum)or crushed stone('h-inch maximum). • Wrap pipe lying near concrete with rubber or foam padding to avoid direct contact with the concrete. None-� Asphalt 2(min) / Concrete 4(min) 18(min) ^ 1 �- � (min) 4(Mir) Fig.6-1.Use only select materials for bedding and backfilling Dualoy 30001L fuel r Select backfill 6(min) handling systems.Native materials are rarely suitable and should not be used. Native 4(min) 6(min) soil Fig.6-2.During layout,bonding and inspection,support the piping on 2x4 blocks to keep the joints clean and to keep bedding out of the pipe. r 7