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KITTITAS COUNTY SOLID WASTE ON-CALL <br />CLE ELUM TRANSFER STATION FRONT ENTRANCE DESIGN <br />TRENCH BACKFILL PW\JA\KITTCO02\ENTRANCE <br />31 23 23.15 - 6 JUNE 2023 <br />©COPYRIGHT 2023 JACOBS <br />provide a cushion before laying each section of pipe, conduit, direct-buried <br />cable, or duct bank. <br />F. Install to form continuous and uniform support except at bell holes, if <br />applicable, or minor disturbances resulting from removal of lifting tackle. <br />3.05 BACKFILL PIPE ZONE <br />A. Upper limit of pipe zone shall not be less than following: <br />1. Pipe: 12 inches, unless shown otherwise. <br />2. Conduit: 3 inches, unless shown otherwise. <br />3. Direct-Buried Cable: 3 inches, unless shown otherwise. <br />4. Duct Bank: 3 inches, unless shown otherwise. <br />B. Restrain pipe, conduit, cables, and duct banks as necessary to prevent their <br />movement during backfill operations. <br />C. Place material simultaneously in lifts on both sides of pipe and, if applicable, <br />between pipes, conduit, cables, and duct banks installed in same trench. <br />1. Pipe 10-Inch and Smaller Diameter: First lift less than or equal to <br />1/2 pipe diameter. <br />2. Pipe Over 10-Inch Diameter: Maximum 6-inch lifts. <br />D. Thoroughly tamp each lift, including area under haunches, with handheld <br />tamping bars supplemented by “walking in” and slicing material under <br />haunches with a shovel to ensure voids are completely filled before placing <br />each succeeding lift. <br />E. Do not use power-driven impact compactors to compact pipe zone material. <br />3.06 MARKING TAPE INSTALLATION <br />A. Continuously install marking tape along centerline of buried piping, on top of <br />last lift of pipe zone material. Coordinate with piping installation drawings. <br />1. Detectable Marking Tape: Install with nonmetallic piping and <br />waterlines. <br />3.07 BACKFILL ABOVE PIPE ZONE <br />A. General: <br />1. Process excavated material to meet specified gradation requirements. <br />2. Adjust moisture content as necessary to obtain specified compaction.