Excavations to do work under this Ordinance shall be dug so as to occasion the least possible inconvenience to the public and to provide for the passage of water along the gutter. All such excavations shall have proper barricades at all times, and warning lights placed from one-half hour before sunset to one-half hour after sunrise. In refilling the excavation the earth must be laid in layers and each layer tamped thoroughly to prevent settlement, and this work, and any street, sidewalk, pavement or other public property that is affected, must be restored to as good a condition as it was previous to the excavation. The plumber must maintain the affected area in good repair to the satisfaction of the City Council for three months after refilling. All water service pipes must be laid so as to prevent rupture by settlement of freezing. No excavation shall be made within six (6) feet of any laid water or sewer pipe while the ground is frozen, and no water or sewer pipe shall be exposed to frost, except by special written permission of the Superintendent.