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HazeltinelRoad Runners Rest IllBrinkmann-Woodward Gravel Pits Lining Project -Design Technical Memorandum Denver Water August 2003 South Platte River indicate that an adequate "safe zone" to construct the soil-bentonite cutoff wall does not exist. Stabilization fill will be required at the above areas and other areas where the combined offset distances from both the interior and exterior slopes exceeded the total width of the crest or in areas where the interior and exterior offset lines crossed, which indicates no available safe crest space for wall installation. Stabilization fill was considered to consist of on-site sand and gravel with less than 10 percent fines from the Louviers Alluvium. Stabilization fill was considered to be placed by end dumping from trucks where the fill is below the water level in the gravel pit and placed and compacted in 8- to 9-inch lifts above the water level, with an exterior slope of about 2.SH:1 V below water. 3.9 Soil-Bentonite Cutoff Wall Horizontal Alignment As described in Section 3.5 Analysis Methodology, the horizontal alignment of the soil- bentonite cutoff wall was selected to be within a "safe zone" that includes the area between the calculated potential failure surfaces for the interior and exterior slopes. The selected alignment of the soil-bentonite cutoff wall is shown on Figure 3.2. The total length of the soil-bentonite cutoff wall is approximately 14,800 feet. In general, the wall was located close to the exterior edge within the safe zone to leave the maximum available space along the crest and interior slope of the reservoir for working platforms and construction access. In areas where sufficient crest width was not available, stabilization fill will be placed along the interior slope to provide the necessary safe zone width. Again, where stabilization fill is required, the alignment of the wall was generally located along the exterior edge of the safe zone to reduce the amount of fill required. The horizontal alignment was selected to maintain straight line segments and to reduce the number of acute angles. Important considerations that governed the alignment selection in different areas along the perimeter of the reservoir were: Between about Stations 0+00 and 40+00, the interior and exterior limits of the safe zone were determined in Draft Technical Memorandum, Soil-Bentonite Cutoff Wall Feasibility Study for the Hazeltine/Road Runners Rest II Gravel Pits (GEI, 2001 a). The horizontal wall alignment in this area is based on results of analyses presented in the reference indicated. GEI Consultants, Inc. 13 o:oso of-ozair-u~a~me o.~~ro rti