Answer Happy

Project specifications of a half mile long storm drain require the 24-inch diameter pipe to be bedded on 6 inches of sand. Sand backfill is required within the pipe zone (from the bottom of the trench up to 2 inches above the crown (top) of the pipe). The new storm drain trench is excavated in native clayey soil to a depth of 6 inches below the bottom of the new pipe (to allow for the required 6 inches of sand bedding). The nominal width of the bottom of the trench is 48 inches. A minimum relative compaction of 90% is required for the sand bedding and pipe zone. A typical trench detail is provided below for your reference. The image has been resized - ignore the scale. Assume the trench wall slope (horizontal: vertical) is 14: 1. UNPAVED PAVED -RESTORED PAVEMENT -SAW CUT -PAVEMENT GRADE TRENCH FLOWABLE CONCRETE FILL W/500 PSI (MIN) COMPACTED EARTH TO 95% OF STANDARD PROCTOR -PIPE BANK RUN OR SAND ENCASEMENT Ales -SAND BED D5 TRENCH DETAIL A1.2) 1"=1'-0"