Backfilling in any street opened or excavated pursuant to an excavation permit issued hereunder shall be compacted to a degree equivalent to that of the undisturbed ground in which the trench was dug. Compacting shall be done by mechanical tappers or vibrators, by rolling in layers, or by water settling, as required by the soil in question and sound engineering practices generally recognized in the construction industry. The decision as to whether a trench shall be backfilled by water settling shall be based upon such engineering practices and shall be made by the Deputy Service Director/Superintendent of Engineering. When water is taken from a fire hydrant the permittee shall assign one man to operate the hydrant and shall make certain that such man has been instructed by the City Water Department in the operation of the hydrant. The Water Department shall like wise be notified at both the beginning and end of the job so that the condition of the fire hydrants can be checked on both occasions. Any damage done to the hydrant during the excavation shall be the responsibility of the permittee. Water shall be paid for by the permittee on the terms agreed upon with the Water Department. (Ord. 2002-106. Passed 11-2-02)
(a) Backfilling by Water Settling. When backfilling is done by water settling, excavated materials above utility installations shall be deposited uniformly in layers of not more than five feet in thickness and shall be thoroughly flooded. During the flooding the water shall be allowed to flow slowly to the trench from high points and shall be worked down to the full depth of the layer of backfill with bars. All bars used shall be long enough to extend entirely through the layer being filled and shall be forced down through the loose backfill material. As the bars are withdrawn the water shall be allowed to flow downward around the bar. The channel or hold formed by the bar shall be kept open and the water kept running into it until the fill has settled. All work shall be done in such manner as to obtain a relative compaction through the entire depth of the backfill of not less than that existing adjacent to the excavation.
(b) Dry Backfilling. Backfilling up to the first eighteen inches above the top of the utility pipes or similar installations shall be done with thin layers. Each layer is to be tamped by manual or mechanical means. Layers that are hand tamped shall not exceed four inches in thickness. Layers that are power tamped shall not exceed six inches in thickness. The same requirements shall apply to the remainder of the backfilling if tamping is the method used for backfilling. Backfilling of all pipes of over twenty four inches in diameter shall be carried up to the spring line of the pipe in three inch layers, with each layer moistened and thoroughly tamped with suitable mechanical equipment. (Ord. 1978-27. Passed 3-1-78.)