No person not a city employee shall uncover, make any connections with or opening into, use, alter or disturb any public sewer or appurtenances thereof without first obtaining a written permit or permits from the public works department. Said permit or permits should be posted in a conspicuous place on the property during performance of work and may not be removed until work is approved by the city. (Ord. 781 § 12, 1975; Ord. 147 § 5.01, 1963)