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i <br />• <br />• <br />• <br />i <br />r <br />r <br />• <br />Slurry viscosity, as measured using a Marsh funnel apparatus, and unit weight values, as measured <br />using a mud balance, were maintained within the acceptable range (V >_40 seconds-Marsh, S.G. _ <br />1.03 to 1.40) except as noted. In a few instances the viscosity dropped below the 40 seconds- <br />Marsh due to an excess of water in the slurry mix. These cases of low viscosities were corrected at <br />the location so that the slurry viscosity in the trench was maintained above the minimum acceptable <br />levels. <br />Filter cake fonmation of the slurry and filtration loss were analyzed using an ambient temperature <br />filter press assembly. Filter loss was generally within the acceptable range. The texture of the cake <br />formation ranged from slightly sandy to very sandy. A sand content kit was used to measure the <br />percent sand by volume suspended in the slurry. Sand content was found to generally range from <br />10 to 18 percent. In a few instances the sand content of the in-trench slurry sample was found to be <br />above the desired maximum value of 20 percent. In these cases, the problem was corrected by <br />adding more slurry from the mixing pond at the point of trenching and a stoppage of backfilling. <br />Trench depth measurements taken in front of the leading edge of the backfill indicated that athree- <br />foot key way depth was maintained in all of the areas where the sand content was found to be above <br />20 percent. <br />Slump cone, gradation, and moisture content test results on the S-B backfill material were used to <br />control the backfill material properties. Test results in each of these areas were consistently within <br />the acceptable range, except as noted in the "Backfill Quality" section. In a couple of instances, the <br />slump test and/or visual inspection resulted in construction directives, which specified corrective <br />action that were carried out immediately. Corrective action included addition reduction of slurry <br />added to backfill material and adjustments to the mixing operations. <br />Visual inspection of excavated soils and bedrock were extensively conducted during trenching to <br />detect when adequate bedrock was encountered. As the trenching progressed, the depth of the <br />trench was periodically checked to determine if the bedrock key trench depth was maintained and <br />not filling with sediment or other material. Depth monitoring confirmed that athree-foot key into <br />approved bedrock was maintained (Appendix B). <br />Comparison of quality control requirements to the field testing and observations indicate that the <br />project requirements were adequately met. Adjustments were made when required by test results <br />and visual inspections. <br />Genera[ <br />Slurry wall construction began in early October 2005 and was completed in late December 2005. <br />Construction was delayed temporarily on occasion due to equipment maintenance, logistics, and <br />very cold weather. When working in below freezing temperatures, cold weather operation <br />equipment, such as heated blankets were used to prevent the slurry and backfill from freezing. <br />Field adjustments to the slurry wall alignment were made when necessary. The slurry wall as-built <br />alignment is shown on Plate I. <br />- 4 - January 2005 <br />sugecoaeh Finel Cmisnudion Repnn Eoc <br />