COMPLIANCE INFO_2007-2011 - Laserfiche WebLink

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Piping system layout Trenching, bedding and backfilling Although fiberglass pipe has excellent strength, it must 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 ortanks at a minimum 'A in/ft of slope. The use of "batter boards" is a very good way to achieve a proper 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 forthe pipe. Compact the subgrade well to prevent differential settling. • Protect the pipe from impact during backfilling and abrasion during operation by surrounding it with a minimum of four inches of select backfill such as washed sand, pea gravel (N -inch maximum) or crushed stone (1h -inch maximum). Fig. 6-1. Use only select materials for bedding and backfilling Dualoy 3000/L fuel handling systems. Native materials are rarely suitable and should not be used. 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. None ® Asphalt I • 2 (min) Concrete 4 (min) - 16 (min) 4`�` a, oq'o14 a- _ �.. ° .. 6 (min) 4 (min) Select backfill - 6 (mm) Native 4 (mm) 6 (min) SQA 7