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B. An acceptable substitute for the initial placing of backfill by the use of a clamshell bucket may be a <br /> lead-in trench. The lead-in trench shall begin at a point outside of the limits of work and provide <br /> sufficient distance for the backfill face to form, by placing the backfill into the trench, before the toe of <br /> the backfill reaches the point where the cut-off is required. The lead-in trench shall be lv: lh or flatter <br /> 3.6 COLD WEATHER CONSTRUCTION REQUIREMENTS <br /> A. No frozen backfill or slurry shall be placed in the soil-bentonite slurry wall trench. All ice forming on <br /> the surface of the slurry trench shall be removed prior to the start of each shift. No frozen or frost <br /> bearing backfill material shall be placed into the trench. When freezing temperatures exist the Engineer <br /> will conduct visual inspections of the slurry in the trench and the soil-bentonite backfill. The inspection <br /> may include measurement of the temperature if necessary to evaluate the potential for frozen material. <br /> The frequency of these inspections will be a minimum of once per day typically, early in the day prior to <br /> the placement of any backfill. Additional inspections may be required if conditions warrant or change. <br /> B. Slurry wall construction work scheduled between November 1 st and March 31 st will require an <br /> additional section in the Work Plan Submittal detailing cold weather construction procedures. <br /> 3.7 TREATMENT FOR TOP OF BACKFILL <br /> A. Upon completion of slurry wall construction, a protective cap shall be constructed on top of the slurry <br /> wall. The cap shall consist of a non-compacted soil cover placed within one day over each backfilled <br /> 100 foot reach. The temporary cover is to be removed after settlement(approximately 2 weeks)and <br /> replaced with a compacted soil cover over the completed slurry wall. <br /> 3.8 CLEAN-UP <br /> A. After completion of the backfill and capping, all remaining excavated material and slurry shall be <br /> removed and the surface shall be cleaned and leveled as directed by the Engineer. Excess slurry shall be <br /> disposed by drying, mixing with dry materials or spreading in thin layers on adjacent areas designated <br /> by the Engineer. No slurry shall be left in ponds, and all ponds shall be pumped dry and backfilled in a <br /> manner approved by the Engineer. <br /> 3.9 QUALITY CONTROL <br /> A. Testing services performed by the Contractor and testing services performed by the Owner's Material <br /> Testing Agency shall be as stipulated in Table 1 at the end of this section. <br /> B. The Contractor shall provide test equipment and a testing trailer with electricity and water for the <br /> Engineer's use. The Owner's QA in no way relieves the Contractor from performing quality work;the <br /> Contractor shall perform its own QC testing as designated by"Contractor" in Table 1 and other tests as <br /> it deems appropriate. <br /> C. Final acceptance of all materials and placement methods will be based on a review of quality control <br /> tests and on visual observations made by the Engineer during construction. The Contractor shall submit <br /> testing results per Table 1 on a daily basis to the Engineer. <br /> D. If a test fails to meet the specified criteria, another test shall be performed after Contractor has <br /> completed the necessary corrective work. Contractor shall bear the expense of all the necessary <br /> corrective action and re-tests performed. <br /> 31 66 17-9 <br /> Prowers Aggregate Operators, LLC <br /> West Farm Pit Phase 2 Slurry Wall Soil-Bentonite Slurry Walls <br />