Medium voltage electrical conduits MVA and MVB are encased in a fluidized thermal backfill designed to provide a thermal resistivity value of less than ninety rho. The concrete encasement maintains a minimum three-inch clearance on sides and bottom, with conduits spaced ten point six two five inches on center. The surrounding excavation includes undisturbed earth at the base and backfill compacted in eight-inch nominal layers to ninety percent of maximum density. The upper profile transitions to finished grade and substrates or finished paving with a top six-inch backfill compacted to ninety-five percent of maximum density.
MVA MVB 7" MIN (TYP) 1'-9" UNDISTURBED EARTH 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
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