12.04.180: PIPELINE PIPES TO BE BACKFILLED AND TAMPED:
All pipeline pipes shall be backfilled with approved material and carefully hand-tamped to a minimum depth of six inches (6"), compacted thickness, over the top of the pipe. Then the backfill material shall be compacted with a mechanical tamper in successive six inch (6") layers for the amount of cover specified to be placed over the pipe. (Ord. 205 § 8, 1977)