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<br /> <br />can be constructed. We do not believe complete diversion of surface water will be <br />required. Temporary diversion ditches should be used as much as practical, <br />particularly for large area fills..The temporary diversion ditches can be planned for <br />inactive areas as construction processes evolve for each fill. <br />Keyways <br />Fills 4 and 6`extend into flatter areas with deep soil cover. We believe keyway <br />cuts should be provided at the toe of these fills, extending from the flow-line outward <br />until shallow bedrock or very stiff soils are found. A detail of the keyway is shown on <br />Fig. 5. For steeper valleys with little soil cover a keyway is not recommended. <br />Keyways are not required for contour area fills or the smaller fills below. <br />If the drain exk will be above the keyway cut, water accumulation in the keyway <br />•" . <br />could occur. For this conditions we do not recommend filling the keyway with spoil fill. <br />It would be preferable to have the base of the drain pass across the bottom of the <br />keyway, exit the toe and then be provided with a gravity outlet. If this is not feasible <br />then the keyway can be filled with compacted natural sands or clays or with durable <br />sandstone rock fill meeting drain rock requirements. Sand or clay fill should be <br />compacted to at least 95 percent of maximum standard Proctor dry density (ASTM D <br />698) within 2 percent of optimum moisture content. <br />Drain Systems <br />Drains are recommended below the "major" excess spoil fills (No., 4 through 9~. <br />Drains are also recommended below Fills 2-1 and 8-1 which cover existing drainages. <br />Drains are not recommended below contour fills areas or sidehill or mound type fills. <br />• LORENCITO COAL COMPANY, LLC <br />LORENCITO SURFACE MINE - PHA6E I <br />CTLR 32, 671 <br />14 <br />