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liaw <br /> 5 Trenching,bedding Recommended practices <br /> and backfilling <br /> Although fiberglass pipe has excellent strength,it must be protected against impact <br /> which may occur from improper handling or during backfilling. <br /> _ Provide atrench width equal to the pipe diameter plus six inches on each side. <br /> Separate multiple lines by at least 4 inches.Refer to Fig.5-1. <br /> • Provide a minimum of 18 inches of select backfill between the top of the pipe <br /> and unpaved ground surfaces. <br /> • Provide a minimum of 4 inches of select backfill between the top of the pipe and <br /> reinforced concrete pavement(4 inches minimum thickness). <br /> • Provide a minimum of 8 inches of select backfill between the top of the pipe and <br /> asphalt pavement(2 inches minimum thickness). <br /> • Slope the trench bottom evenly from the dispensers back to sumps or tanks ata <br /> minimum'A in/ft. <br /> • Maintalnthetrench bottomfraeof hard orsharpobiects. <br /> • Grade the trench bottom with at least 6 inches of select backfill to provide firm, <br /> even support for the pipe.Compact the subgrade wel I to prevent differential <br /> settling. <br /> • protect the pipe from impact during backfilling and abrasion during operation by <br /> surrounding it with four to six Inches of select backfill such as washed send,pea <br /> gravel CA-inch maximum)or crushed stone('h-inch maximum). <br /> • Wrap pipe lying near concrete with rubber or foam padding to avoid direct <br /> contact with the concrete. <br /> No pavement <br /> /// Aapnah 2(mn) <br /> Concrete . <br /> 4(MN - to(rnln) <br /> 4(mn) O O O <br /> Fig.5-1.Use oNyselactmatedals - <br /> for bedding and back/JIing sekn baCkf T atM) <br /> Dualoy 3000/L fuelhandling <br /> systems-Native materials - <br /> era rarely suffable an d <br /> shouidnotbe used. Nson 4(m�N�a(min) <br /> sell <br /> 6 pry fining contained <br /> Recommended practices <br /> primary piping • Have island forms.boxes,and shear valves in place before dryftting. <br /> • fay out and dry fit primary and containment piping at the same time- <br /> Allow sufficient clearance when dry fitting the primary to accommodate the <br /> containment fittings. <br /> Dimensions of containment <br /> fittings may be found at the end <br /> of this document. <br /> F,g-6.1.Duringtayot4 bonding �-�" ' r -- system, <br /> andinspeetlon,support the ' Do not bond Primary <br /> piping on 2x4 blocks tokeep the ' together before the i <br /> loins clean and to keep bedding secondary containment i <br /> outofthepipe.Remove _ system has been dry fit. <br /> supports before burial L !——'—_——J <br /> 5 <br />