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• 2.3.4 Sedimentation Controls <br />Surface runoff from the areas disturbed by the mine bench and the waste rock disposal <br />area will be routed to sediment control ponds or other approved structures. The ponds <br />and ditches have or will be designed in accordance with applicable criteria. Discharge <br />of water will be covered by an NPDES permit prior to construction of any ponds. <br />Mine Bench Area <br />The sedimentation reservoir will be located at the base of the embankment as shown in <br />Figure 2.2-14. A detailed plan view, hydrologic and hydraulic data used for the designs <br />are shown on Figure 2.2-3. All calculations used in the design are contained in <br />Appendix M(vi). <br />As shown in Figures 2.2-3 and 2.2-14, an eight inch diameter corrugated pipe will be <br />used to dewater the pond. The invert of the pipe will be installed at the elevation of the <br />maximum sediment storage level. Agate valve will be placed upon the discharge pipe <br />to allow for controlled discharges. The pond will be capable of storing slightly more <br />than the volume of runoff from one 10 year 24 hour precipitation event above the <br />discharge pipe. A marker will be installed in the pond to indicate the 60% sediment <br />storage level. <br />Waste Rock Disposal Area <br />See section 2.2.5 Waste Rock Disposal Site. <br />I• <br />M" 2.3-4 9/02 <br />