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performed and the toe of the backfill slope was typically maintained within 120-ft of the <br />excavation end of the open trench. <br />The Contractor placed the SB backfill mixture into the trench using a lead-in slope or <br />on top of previously placed backfill. The backfill mixture was pushed in by dozer. The <br />backfill formed a slope of approximately 8:1 (horizontal to vertical) slope in the trench, <br />advancing through the trench by a sliding and slumping displacement action. Batches <br />were prepared and placed in approximately 20-30 minutes. <br />As a daily routine, prior to placing backfill, the bottom of the trench was measured by <br />the Contractor to ensure the trench bottom was clean of caved material and sand <br />accumulation, and to determine the toe location and the profile of the backfill slope. At <br />each days end, the trench's profile would be recorded in order to compare the following <br />morning's measurement. A Komatsu PC800 was used to clean out the trench bottom <br />and to sample for the location of the backfill toe. <br />3.4.3 Soil-Bentonite Backfill Sampling Procedure <br />Lyman Henn collected 78 samples from the backfill prior to placing it into the trench <br />and performed sieve analysis and moisture content measurement. A sample was <br />collected twice per day to determine slump and density, and once per day for moisture <br />content and grain size distribution. Slump tests were performed according to ASTM <br />C143-90a. Density tests were performed using a 0.25 cubic foot bucket according to <br />ASTM C 138-92. Moisture and grain size distribution were performed using ASTM D <br />2216 and ASTM C 136, respectively. Table V presents the results for each sample. <br />Lyman Henn collected eight bulk samples (PERM-1 through PERM-8, approximately <br />every 1,000 linear ft.) of soil-bentonite backfill for permeability performance testing. <br />Knight Piesold performed permeability testing in accordance with ASTM D5084 using <br />10 psi confining pressure, with a maximum gradient of 15. Table VI presents the <br />results for each sample. Appendix B contains the permeability test reports by Knight <br />Piesold. <br />3.5 Deviations from the Plans and Specifications <br />Several aspects of the SB slurry wall construction were altered from the design plans and <br />specifications during the construction phase and are summarized below. <br />1. The actual depth to massive bedrock varied from the design depths. The top of bedrock <br />profile presented on the design plans was determined by interpolation and extrapolation of <br />test boring information along the slurry wall alignment. The actual depth to unweathered <br />bedrock was determined in the field by the Contractor and confirmed by Lyman Henn as <br />excavation proceeded. Recorded depths are provided in Table III of this report <br />2. On the testing occasions when the as-mixed slurry viscosity dropped below 40 sec, Lyman <br />Henn notified the Contractor and the slurry mixture was adjusted to meet specifications as <br />' tested by the Contractor and Lyman Henn's field representative. <br />p GAPROJEUSU07021-W0 Loveland Ready Mix Slurry Wall\R. Records and Conespondence\R.11 Reports\As-Built report stufl\As•builtreportFnal.doc