2008-04-15_REVISION - M1980244 (351)

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• • • 9.0 SURFACE WATER MANAGEMENT 9.1 General The hydrologic design parameters used to design the surface water management system for the MLE activities are the same as those used for previous submittals including Amendment No. 7, Amendment No. 8 and the East Cresson Mine Expansion. The design storms for the Cresson Project previously approved by the OMLR are as follows (from the NOAA iso-pluvial charts): ¦ 10-year, 24-hour=2.4 inches ¦ 100-year, 24-hour = 3.5 inches The mines, overburden storage areas, VLF, and support facilities for the Cresson Project incorporate designs to protect the quality and quantity of Project area ground and surface waters. The VLF, including the Phase 5 extension, and the existing ADR facilities are designed as zero discharge systems with upgradient runoff diverted around the facilities. The VLF is designed and constructed to contain precipitation from a 100-year, 24-hour storm event within the lined area. Integration of the ADR facilities into the VLF liner system provides for further containment of solutions. Runoff from undisturbed areas is diverted around areas of disturbance to the extent possible. Runoff from disturbed areas will be controlled with best management practices to minimize erosion and to retain excessive sediment. CC&V operates in accordance with the Colorado General Storm Water Permit for the facility. Surface flows resulting from intense, but infrequent, storm events will be controlled and routed around the new disturbance areas associated with the Phase 5 VLF extension, North Cresson Mine area, WHEX of the East Cresson Mine area, SGOSA Extension and ECOSA. This will be accomplished with a series of diversion ditches constructed at various stages in the operations. The size and geometry of the diversions will be based on the anticipated location and longevity of the structure as well as the peak storm water flow estimates. These estimates are developed using practical graphic- or computer-based modeling techniques, in this case the SEDCAD4 model. Cripple Creek & Victor Gold Mining Company Cresson Project Mine Life Extension 9-1