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Q <br /> <br />slump of 2 to 6 inches. To this end, the material shall be sluiced with slurry during blending operations. <br />Sluicing with water will not be permitted. Containment berths will be constructed where necessary to <br />prevent slung from entering rivers or ditches or flowing across the project boundary. <br />3.08 BACKFB.L PLACEMEM <br />The backfill shall be placed continuously from the beginning of the trench, in the direction of the <br />excavation, to the end of the trench. The toe of the slope of the trench excavation shall precede the toe of <br />the backfill slope so that the toe of the backfill shall not be less than 50 feet following the toe of the <br />excavation, or as required to permit proper cleaning of the trench bottom and to permit inspection and <br />measurement. Placing operations shall proceed in such a fashion that the surface of the backfill below the <br />slurry shall follow a reasonably smooth grade and shall not have hollows which may trep pockets of slung <br />during subsequent backfilling. Free dropping of backfill material through the slung will not be permitted. <br />Initial backfill shall be placed by lowering it to the bottom of the trenches with clamshell bucket until the <br />surface of the backfill rises above the surface of the slurry trench at the end of the trench. Additional <br />backfill may than be placed in such a manner that the backfill enters the trench by sliding down the forward <br />face of the previously placed backfill. To accomplish [his, sufficient backfill shall be piled on the edge of <br />the existing backfill [o cause a slump and sliding action on the face of the in-place backfill. The backfill shall <br />not be dropped or deposited in any manner that will cause segregation. An acceptable substitute for the <br />initial placing of backfill by the use of a clamshell bucket, shall be to begin excavation at a point outside of <br />the limits of work which will provide a sufficient distance for the backfill face to form, by pushing backfill <br />into the trench, before the toe of [he 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 <br />be capped in accordance with the details shown on the drawings or as directed by the Engineer. <br />3.10 CLEAN-UP <br />ARer completion of the backfill and capping, all remaining excavated material and slurry shall be removed <br />and placed in thin IiRs along the inside face of the reservoir and the surface shall be cleaned and leveled as <br />directed by the Engineer. Excess slung shall be disposed of by spreading in this layers on adjacent areas <br />designated by the Engineer. No slung shall be left in ponds, and all ponds shall be pumped dry and <br />backfilled. <br />3.11 QUALITY CONTROL <br />The Contractor shall maintain his own quality control for the cut-off wall construction under the direction of <br />a qualified Engineer. Testing requirements are summarized in Table 1 and specified herein. <br />3.I^_ TRENCHING CONTINUITY AND KEY <br />The Contractor shall be responsible for demonstrating to the satisfaction of the Engineer that the trench is <br />continuous and keyed into the bedrock surface. Trench continuity shall be assured by the action of <br />movement of the trench excavation equipmrnt such that the digging tools can be passed vertically from top <br />to bottom of the trench as well as moved horizontally along the axis of the trench without encountering <br />unexcavated material. Penetration of the bottom of the trench into the bedrock shall be demonstrated by <br />observation of the cuttings removed from the trench and the action of the excavating tools on the bedrock <br />surface. <br />3.13 SLURRY AND BACKFILL <br />01/99 Section 02168 -Page 4 of 5 <br />