The requirements for bedding, haunching and initial backfilling shall be in accordance with the following.
(A) Bedding. A minimum layer of 6-inch bedding consisting of #67 granular bedding material shall be provided upon a stable undisturbed subgrade. If an unstable subgrade is encountered, the city's authorized representative shall determine the method of building the required subgrade support.
(B) Haunching. After the pipe has been placed on the approved bedding material, #67 granular material shall be placed around the sides of the pipe from the undisturbed trench wall to the pipe. Under no circumstances shall the maximum allowable trench width for the type, size and depth of pipe be exceeded. Unless otherwise approved or ordered, the maximum allowable trench widths measured at the top of the pipe shall be 27 inches for 6- and 8-inch diameter pipe, 30 inches for 10-inch diameter pipe and 33 inches for 12-inch diameter pipe.
(C) Initial backfill. No backfill shall be placed until after inspection is completed by the city's authorized representative. After the haunching of the pipe has been completed, the pipe shall be covered with #67 granular material to a plane, 6 inches above the top of the pipe.
(D) Backfill. Upon completion of the initial backfill, the best excavated material shall be used for backfilling the trench. Trash, boulders, frozen soil, and the like, shall not be used as backfill material. If the pipe is laid under a pavement or berm area, the pipe shall be backfilled with approved granular material, a minimum of 5 feet beyond the edge of the berm or edge of pavement in absence of a berm.
(1981 Code, § 51.061) (Ord. 6405-90, passed 9-10-1990) Penalty, see § 51.999