Tunnels under pavement shall not be permitted except by permission of the City Engineer, and, if permitted, shall be adequately supported by timbering and backfilling under the direction of the City Engineer. Where possible, the pipe shall be driven through or bored under a roadway, except sidewalks, in a casing of sufficient strength, which casing shall be left in place with the ends closed around the pipe. [Ord. 1021 § 19.11, 1961; Code 1970 § 12.24.320; Code 1954 § 4-5.128.]