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mechanical tamping. The layers of ba ill shall be sprinkled lightly with water if additional moisture is required for proper compaction. This rocess of filling and tamping in layers shall be contieued until the backfill is brought up to the level of the top of the pipe. A sufficient amount of selected material shall then be cazefully placed over the top of the p pe so that, when consolidated in six-inch ]ifts, the level of the select material will be not less than twelve (12 inches above the top of the pipe. Before backfilling the remainder of the trench, the select material shal] consolidated by jetting and flooding or mechanical tamping, at the op[ion of the Contractor, to such an ex ent as to secure uniform consolidation. Uniform consolidated shall be considered to be the equivalent com ac[ion of 90% Standard Proctor Density (ASTM D-698). It shall be in the full res onsibility of the Contractor to explore the project and subsurface materials to deternune if the trench ex avation will be suitable for use as select materials and to follow as closely as possible this specification to sure a good, sound pipeline when completed. 2005.07 BACKFILLING Backfilling shall include the refilling and consolidating of the fill in trenches and excavations above the embedment up to the sunou ding ground surface or road grade at crossings. No backfill shall be placed until the City's representative ha inspected the trench and pipe in place and has authorized the placing of backfill. Backfilling shall be don with good earth, sand or gravel and shall be free from rocks latger than 6 inches in diameter or hard lumpy material. No material of a perishable, spongy or otherwise unsuitable nature shall be used in backfilling. After the pipe and em dment have been placed, [he method of backfilling pipe trenches shall be as follows: The remainder of the t ench shall be filled with material obtained from the spoil bank. The earth shall then be consolidated by jett' g and flooding until full settlement has been reached. The jetting shall be accomplished by pumping water t ough a pipe that is slowly inserted vertically into the trench backfill. The trench shall then be flooded in pu dles untIl no more appreciable absorption of water into the backfill occurs. The Contractor shall make p ovisions to allow the water used in jetting to freely drain from the trench and not accumulate in the tren h. Jetting of trench backfill shall be lunited to six (6) feet of cover. Where the depth of cover over the ipe is six (6) feet or greater, separate jetting operations shall be accomplished for each six-foot interv 1. Mechanical tamping in six-inch maximum lifts may be used, at the option of the Contractor, in lieu of th jetting and flooding and backfill. Flooding or jetting w ll not be allowed under future or existing pavements, or where consolidation is required above 90% tandazd Proctor Density. Backfill under pavements shall be placed at minimum 95% Standazd Proctor by h d or mechanical tamping. Where construction nters the limits of State or County rights-of-way, any specia] requirements of these agencies with r spect to backfilling shall be complied with. After the trench has bEen refilled, topsoil shall be replaced to the extent that rock excavated from the trench will be completely cqvered or removed and the area is returned to its original condition, except that in cultivated ueas a min"um of 12 inches of top soil shall be replaced. Any settling that occurs at the surface of the trench shall be r$filled to the extisting grade. Item 2005-6