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grained native material will provide a high level of confidence <br />• in the containment capability of the liner. The potential for <br />permeation of water through the geomembrane material is <br />minimal. Installation of the geomembrane can however, be <br />anticipated to include a small number of flaws which could <br />create the potential of limited leakage. By constructing the <br />compacted fine-grained soil liner in contact with the <br />geomembrane, such leakage, if it occurs, will be further <br />limited to nominal levels. The containment capabilities are <br />enhanced this creates a level of redundancy which reduces the <br />risk of leakage. <br />D.6.5.2 Comoosite Liner <br />Selected fine grained native material will be used to <br />construct a 12-inch thick compacted foundation and liner <br />bedding layer. The selected native material will be placed in <br />two-ft lifts within approximately 2X of the optimum moisture <br />• content and compacted to 95X of the standard Proctor. A <br />continuous geomembrane of 40-mil VLDPE will be placed on the <br />prepared foundation. <br />For Phase 1 operations the liner will be anchored at an <br />elevation of 8,590 on a 25 foot wide bench. A .'t5 foot width <br />of 80-mil HDPE liner will be welded to the disposal area liner <br />at the downgradient edge of the bench and the 80-nail HDPE liner <br />will cover the bench. This segment will serve as a liner for <br />placement of the tailings slurry and water return lines as well <br />as a facilities access road. The heavier liner is necessary <br />to prevent possible damage by road traffic. By initially lining <br />this area, the road and pipelines can be used while placing <br />the next lift of 40-mil VLDPE liner for the Phase 2 disposal <br />area. The 40-mil VLDPE liner for the next lift will be welded <br />to the outside limit of the 80-mil HDPE. Intermediate anchor <br />u <br />U-32 <br />