(A) Special backfill shall be used at all locations and of the type called for on the drawings, and at other locations specified herein whether called for on the drawings or not. The type and method of backfilling is dependent on its locations and function and shall conform with the following requirements. The applicant will supply field testing on the special backfill compaction requirements.
(B) Backfilling of trenches in the shoulder area and under private gravel drives shall be carried to within six inches of the existing surface as specified under Trench A or Trench B as required. The shoulder shall be defined herein as the area within five feet of the pavement edge, or the width of the existing graveled shoulder, whichever is greater. The remaining depth shall be backfilled with six inches of compacted 21AA aggregate. Backfilling of trenches crossing gravel roads or streets shall be carried to within eight inches of the existing surface and the remaining depth shall be backfilled with eight inches of compacted 21AA aggregate. Compaction shall be performed by a pneumatic-tired roller or a vibratory compactor until the compaction requirements as required for Trench A or Trench B and as detailed in the following divisions are met.
(C) The requirements as specified herein are in addition to the conditions provided for under permit granted by the Road Commission for Oakland County (RCOC) or the Michigan Department of Transportation (MDOT) where applicable.
(D) Trench A. All trenches under graveled, slag or hard surfaced roads, pavements, hard surfaced parking lots and driveways, sidewalks, curbs and where the trench edge is within three feet of a pavement shall be backfilled with bank run sand meeting the requirements of granular material, MDOT Class II. The material shall be placed by the controlled density method or other effective means having the approval of the Engineer and is to be compacted to 95% of maximum unit weight as determined by ASTM D-1557 Modified Proctor. Trenches under pavement to be constructed in the near future, as noted or shown on the drawings, shall be backfilled with granular material, meeting the requirements of current MDOT Standard Specifications for Construction.
(E) Trench B. Trench B shall be used where called for on the drawings. All trenches shall be backfilled with granular material, MDOT Class II to a point 12 inches above the pipe for diameters less than 24 inches and up to the spring line with materials meeting the requirements of the current MDOT Standards for diameters 24 inches or larger. This portion of the backfill is to be placed in layers not exceeding six inches in depth, and shall be thoroughly compacted by mechanical tamping to not less than 95% of maximum unit weight utilizing ASTM D-1557 Modified Proctor. The remainder of the backfill shall be made with suitable excavated material (excluding blue and gray clays, peat, muck, marl or other organic materials) placed in one foot layers with each layer being thoroughly compacted by approved mechanical methods, or other effective means having the approval of the Engineer, to a density of 90% of maximum unit weight utilizing ASTM D-1557 Modified Proctor.
(Ord. 31.26, passed 5-13-13)