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2.05.3 <br />Hydraulic Conductivity specification of 1x10"' cm/sec, the native soils are <br />proposed to be amended with bentonite. Huddleston -Berry Engineering and <br />Testing (HBET), or another approved Geotechnical firm will complete a mix <br />design to establish the percentage of bentonite required to be blended into the <br />native soils in order to meet the Hydraulic Conductivity specification. <br />Subsequently, the full suite of testing outlined in Appendix T, Table 1 will be <br />completed on the blended material to be used for the liner construction. If <br />bentonite is to be used, it will be obtained off-site and the blended liner will be 12 - <br />inches thick. <br />During installation, in order to ensure the soil liner will perform as designed, <br />construction materials testing will be conducted by qualified engineering <br />technicians under the direction of a Field Testing Services Manager and/or <br />Project Engineer. Prior to liner construction, the subgrade will be evaluated to <br />ensure that it is free of unsuitable materials. In addition, a geotechincal engineer <br />will observe proofrolling of the subgrade to ensure subgrade stability in <br />accordance with referenced Solid Waste Guidance Document, as incorporated in <br />Exhibit 20. Subsequent to proofrolling, but prior to liner placement, a <br />geotechnical engineer will verify that subgrade is properly scarified. In <br />accordance with the referenced Solid Waste Guidance Document, materials <br />testing during liner construction for the sediment pond will be conducted as <br />summarized in Appendix T, Table 1. <br />Twelve inches of native soil will be used as a liner cover in order to prevent <br />cracking of the liner, and damage during sediment cleanout. The soil cover will <br />be compacted until it attains at least 90% of the maximum dry density attained in <br />a laboratory compaction test in accordance with ASTM D698. Compaction <br />testing will be taken at a frequency and location of not less than one per every <br />other layer, at random locations across the ponds. <br />(ii)(C) Operations and maintenance requirements forthe pond. The sediment pond <br />must be dewatered if it contains water above the maximum sediment level. <br />Dewatering events should occur within 48 hours after the storm event or <br />mine discharge which caused the water accumulation. Sediment must be <br />removed from the sediment pond no later than when the sediment is 60% of <br />the ponds maximum sediment level. <br />PR -02 2.05-20- 10/12 <br />