This typical utility trench detail specifies excavation geometry, bedding layers, and pavement restoration for underground piping. The trench features side slopes conforming to local, state, and federal OSHA requirements with compacted backfill extending to the subgrade. The pipe rests on a shaped stable foundation with a minimum four-inch bedding layer, supplemented by a six-inch minimum sand or gravel layer required in unstable areas or through rock excavation. The pipe zone is surrounded by sand and gravel bedding extending eighteen inches above the pipe crown, utilizing two-inch minus material for hard wall pipe or three-quarter-inch minus material for PVC pipe. The trench width is dimensioned as the pipe outside diameter plus eighteen inches. Surface restoration consists of a minimum four-inch asphalt pavement over an eight-inch minimum road base, with saw-cut edges requiring a clean and tack coat.
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