All trench excavations must be of sufficient width and depth for properly constructing the sewers, water mains, conduits or other structures in the manner and of the size specified, and for removing any material which the Engineer may deem unsuitable for foundations.
The trenches must be of sufficient width, within limitations hereinafter established, to admit ample room within the limits of the excavation, for the placing of sheeting and bracing should sheeting and bracing be necessary to secure the protection of the work.
The bottom of all excavation shall have as closely as possible the shape and dimensions of the outside of the pipe or masonry to be installed.
When pipe (sewer or water) of the bell and spigot type is to be installed in the trench, bell holes of sufficient depth shall be dug across the bottom of the trench to accommodate the bell and to permit adequate caulking.
Where pipe sewers are to be installed in the trench, the width of the trench at the top of the pipe to be installed shall not exceed four-thirds of the external diameter of the sewer, plus eight inches.
When it is necessary in sewer construction to sheet the trench, the maximum allowable trench width herein specified shall be measured between the inside facing of the sheeting.
If the width of the trench in sewer construction as excavated, measured at the top of the pipe to be installed, exceeds the maximum allowable width herein specified, the contractor shall furnish and install a concrete cradle to the section shown on the drawings, in compliance with the specifications hereinafter stated. The provisions of this paragraph shall apply unless specifically excepted for certain sections of sewers to be installed in shallow cut.
The minimum allowable trench width at the top of the pipe on all pipeline construction, in order to allow proper tamping, shall be not less than the outside diameter of the pipe, plus eight inches.
(Ord. 352. Passed 10-22-62.)