Rule 22. The Division of Water and Wastewater Treatment reserves the right to specify the workmanship and materials used on the service from the curb stop to the meter. The service line shall be not less than one inch in diameter and shall be type "K" copper up to two inches in diameter and cast iron with slip type or mechanical joints over two inches in diameter. The service shall be at least four feet deep. Where the pipe is laid in an open cut it shall be bedded on two inches of fine earth and backfilled and tamped to a point at least twelve inches above the pipe in place. The remainder of the trench may be backfilled in the usual method being careful, however, that no stone over one foot in diameter is placed in the trench. These specifications also apply to trenches opened up for repairing of existing pipes.