The person obtaining a permit must retain the number thereof and must notify the City Engineer or the Division of Engineering utility inspector at least two hours before the tap is ready for connection. In so reporting, the number of the permit must be given so the inspector may know the exact location of the sewer to be inspected. No tap or connection shall be made except in the presence of the utility inspector. Prior to the making of any tap or connection, the working condition of all sewer laterals shall be checked by the use of a six-inch screw and extension rods to the satisfaction of the utility inspector. The completed connection shall not be used until written approval of the connection and house sewer has been issued by the office of the City Engineer.