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4.6.1.3.2 Sediment Control <br />• Disturbed Area Sediment Control <br />Sediment control structures are designed to prevent contribution of sediment to <br />the North Thompson Creek, Runoff from undisturbed areas will be directed away <br />from disturbed areas to prevent additional erosion or sediment loading. Where <br />mixture of disturbed and undisturbed runoff does occur, the combined drainage <br />will be treated as disturbed area drainage prior to discharge. Undisturbed <br />runoff, including clean area overflow from sediment Pond P-3, will be diverted <br />through the mine area with a termed ditch. This ditch is designed to isolate <br />the clean runoff from any disturbed overland flow. <br />Layout and details of the ditch are shown on Drawings D-4-6 and D-4-8. <br />Sediment loading will be reduced by revegetation of disturbed areas. Interim <br />revegetation areas are shown on Drawings D-4-17 and D-4-18, <br />• Sedimentation ponds will be located as near as possible to the disturbed area <br />and away from North Thompson Creek, Control of disturbed area runoff at the <br />mine site includes the design of three sedimentation ponds. Sediment storage <br />volume for each pond was determined using the Universal Soil Loss Equation. <br />These calculations are included in the final design section of Appendix 4-R, <br />Sediment delivery ratio was considered to be 100 percent in all cases. Sediment <br />will be removed from each pond when the volume of sediment accumulates to <br />60 percent of the design volume. Fines will be disposed of at the refuse site. <br />Two of the sediment ponds are shown on Drawing D-4-8, designated as Ponds P-3 <br />and P-g. The third sediment pond is located at the toe of the refuse disposal <br />site. <br />For both Ponds P-3 and P-g, a theoretical detention time of 24 hours is provided <br />for inflow entering the pond from a 10-year, 24-hour precipitation event, A <br />dewatering device, consisting of a 6-inch diameter pipe with a 3-inch diameter <br />hole and fitted with a non-clogging entrance device, is used in each of these <br /> <br />4-104 <br />