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DRAFT <br />_ 3.08 BACKFILL PLACEMENT <br />The backfill shall be placed continuously from the beginning of the trench, in the direction of the excavation, to <br />the end of the trench. The toe of the slope of the trench excavation shall precede the toe of the backfill slope so <br />that the toe of the backfill shall no[ interfere with excavation, or as required to permit proper cleaning of the <br />trench bottom and to permit inspection and measurement. Placing operations shall proceed in such a fashion <br />that the surface of the backfill below [he slurry shall follow a reasonably smooth grade and shall not have <br />hollows which may trap pockets of slurry during subsequent backfilling. Free dropping of backfill material <br />through the slurry will not be permitted. Initial backfill shall be placed by lowering it to the bottom of the <br />trench with clamshell bucket until the surface of the backfill rises above the surface of the slurry trench at the <br />end of the trench. Additional backfill may than be placed in such a manner that the backfill enters the trench by <br />sliding down the forward face of the previously placed backfill. To accomplish this, sufficient backfill shall be <br />piled on the edge of the existing backfill to cause a slump and sliding action on the face of the in-place backfill. <br />The backfill shall not be dropped or deposited in any manner that will cause segregation. An acceptable <br />substitute for the initial placing of backfill by [he use of a clamshell bucket, shall be to begin excavation at a <br />point outside of the limits of work which will provide a sufficient distance for the backfill face to form, by <br />pushing backfill into the trench, before the toe of the backfill reaches the point where the cut-off is required. <br />3.09 TREATMENT FOR TOP OF CUT-OFF TRENCH <br />Upon completion of backfill placement, and before drying of the backfill can occur, the cut-off trench shall be <br />capped in accordance with [he details shown on the drawings or as directed by [he Engineer. <br />3.10 CLEAN-UP <br />After completion of the backfill and capping, all remaining excavated material and slurry shall be removed and <br />placed in a manner acceptable to the Owner and the surface shall be cleaned and leveled as directed by the <br />Engineer. Excess slurry shall be disposed of by spreading in thin layers on adjacent areas designated by the <br />Engineer. No slurry shall be left in ponds, and all ponds shall be pumped dry and backfilled as designated by <br />the Owner or Engineer. <br />3.11 QUALITY CONTROL <br />The Contractor shall review the quality control tests for the cut-off wall constmction conducted by the <br />Engineer. Any deficiencies revealed by the quality control testing will be corrected immediately by the <br />Contractor. Testing requirements are surmnarized in Table 1 and specified herein. <br />3.12 TRENCHING CONTINUITY AND KEY <br />The Contractor shall be responsible for demonstrating to the satisfaction of the Engineer that [he trench is <br />continuous and keyed into the bedrock surface. Trench continuity shall be assured by the action of movement <br />of the trench excavation equipment such that the digging tools can be passed vertically from top to bottom of <br />the trench as well as moved horizontally along the axis of the trench without encountering unexcavated <br />material. Penetration of [he bottom of the trench into the bedrock shall be demonstrated by observation of the <br />cuttings removed from the trench and the action of the excavating tools on [he bedrock surface. <br />7/04 Section 02168 -Page 4 of 5 <br />