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hand tampers, and hand-tamping continued during the placing of the backfill until the backfill reaches an elevation such that its moisture content will permit the use of mechanical tampers. When the backfill has reached such elevation, normally acceptable backfill material may be used and compaction shall be obtained by the use of mechanical tampers. The mechanical tamping shall be done in such manner and to such extent as to transfer the compacting force into the previously hand-tamped fill. E. Requirements for Thick Lift Compaction in Granular Materials: 1. If the CONTRACTOR has compaction equipment with which the required density can be obtained in thicker lifts than permitted above and upon satisfactory evidence that the proposed equipment will produce work equal in quality to that produced by the specified methods, the ENGINEER may permit placement of granular material of soil groups A-1, A-2, or A-3 in lifts up to a maximum of three foot compacted thickness. The CONTRACTOR will be required to furnish equipment and labor to excavate and backfill test pits to be dug for the performance of density tests. 2. Use of thick lift compaction procedures will not be allowed for first stage backfilling (beneath the haunches) of pipe culverts and storm sewers. 3.10 CONSTRUCTION METHODS FOR RIP RAP HEADWALLS A. The sand and cement shall be mixed dry, in the proportions of five cubic feet of sand to one bag of cement, until the mixture is of uniform color. B. The mixed material shall be accurately measured into each sack, with care being taken to place the same amount of material in each sack, and at least the top six inches of the sacks shall remain unfilled to allow for properly tying or folding and to insure against breakage of the sack during placing. C. The filled sacks shall be placed with their tied or folded ends all in the same direction unless otherwise shown on the plans. The sacks shall be laid with broken joints, in a regular pattern. The sacks shall be rammed or backed against each other so as to form a close and molded contact after the sand and cement mixture has set up. Sacks ripped with sound, unbroken sacks. Reinforcing rods shall be added as shown on the plans. All sacks shall then be thoroughly saturated with water. D. Immediately after watering, all openings between sacks shall be filled with dry grout composed of one part Portland cement and five parts sand. E. After the bags have been set up, a concrete cap shall be formed and poured on the headwall as shown on the plans. City of Sunny Isles Beach NE 174th Street Roadway Improvements 02630 - 17 Storm Drainage 14-1758 / 09-19-2014