Four 6-inch medium voltage conduits are encased within a concrete duct bank measuring nineteen and five-eighths inches minimum in height and two feet seven inches in width, set over undisturbed earth. A continuous W4x4x4 Bigfoot welded wire fabric is wet-set over the top of the duct bank with three inches minimum concrete cover. The excavation is filled with fluidized thermal backfill designed to provide a thermal resistivity value of less than 90 rho. Above the thermal backfill, backfill is compacted in eight-inch nominal layers to 90% of maximum density, topped with a six-inch layer compacted to 95% of maximum density beneath finished paving and substrates.
UNDISTURBED EARTH MV 10.76" MIN (TYP) 7" MIN (TYP) 2'-7" 24" TOP 6" BACKFILL COMPACTED TO 95% OF MAX. DENSITY FINISHED GRADE & SUBSTRATES(S) AS SHOWN BACKFILL COMPACTED IN 8" NOMINAL LAYERS TO 90% OF MAX DENSITY FINISHED PAVING & SUBSTRATES(S) AS SHOWN FLUIDIZED THERMAL BACKFILL (TO PROVIDE THERMAL RESISTIVITY VALUE OF LESS THAN 90 RHO) 3" MIN 19.625"MIN 10.625" ON CENTER 3" MIN MV MV MV (4) 6" CONDUITS IN CONCRETE ENCASED DUCT BANK W4x4x4 BIGFOOT WWF WET SET OVER TOP CONTINUOUS
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