(1) In all cases, trenches must be of sufficient width to permit the proper jointing to the pipe. The trenches shall be at least six inches wider on each side, or a total width of 12 inches more than the exterior diameter of the pipe, except where pipes are of four inches in diameter or under. If a rock is excavated, it shall be removed to a depth of six inches below the bottom so the trench can be refilled with sand or noncorrosive soil and well tamped. Excavation for manholes and other structures shall be sufficient to leave at least 12 inches between their outer surfaces and the sides of the excavation.

(2) Except by special permission from the City Engineer, no trench shall be excavated more than 300 feet in advance of pipe laying, nor left unfilled for more than 700 feet where pipe has been laid. The length of the trench that may be opened at any one time shall not be greater than the length of pipe and the necessary accessories which are available to the site ready to put in place. The completed trench shall be kept not less than 30 feet ahead of the pipe layers.

(3) Trenches over four feet deep shall be braced and sheathed according to the standards and rules and regulations of the State Department of Labor and Industries, and as hereafter amended, to protect the workmen and the general public, as well as public and/or private property. No timber bracing, lagging, sheathing or other lumber shall be left in any trench. [Ord. 1021 § 19.08, 1961; Code 1970 § 12.24.290; Code 1954 § 4-5.116.]