§ 153.142  WIDTH OF EXCAVATION.
   (A)   The trench shall be excavated to an elevation four inches below the bottom of the pipe and so that the flow line of the finished pipeline will be at the depth and grade specified or established by the developer’s engineer. For trench depths of five feet or less and when sheeting and shoring is not required, the trench shall be excavated to a minimum width of two feet wider than the external diameter of the pipe, to permit thorough tamping of the material under the haunches and around the pipe. For trench depths of more than five feet and when sheeting or shoring is required, the trench width shall be a minimum of three feet wider than the external diameter of the pipe. The trench shall generally be excavated so that vertical faces are maintained, except that when authorized by the developer’s engineer and when physical conditions and safety will permit, the sides of the trench may be sloped or benched in accordance with OSHA’s 29 C.F.R. part 1926, subpart P, Excavation Standards.
   (B)   If these trench widths are exceeded without the written authorization of the developer’s engineer, the pipe shall be installed with a concrete cradle or with concrete encasement or a stronger pipe than originally specified shall be used as authorized by the developer’s engineer.
(Ord. 97-7, passed 7-1-1997, § 5.16)