2012-02-28_REVISION - M1980244 (85)

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CC &V has developed a comprehensive, probabilistic (stochastic), dynamic water balance model, using GoldSim© software, which tracks water flow throughout the engineered water management facilities. This GoldSim© model was developed and is periodically refined for permitting /design purposes, and is included in the Mining and Reclamation Permit application. The model considers flows into and from the PSSAs and External Storage Pond, and accounts for the operating volume, draindown resulting from 12 hours of power loss, solution accumulation due to seasonal climatic variation, the 100 -year, 24- hour design storm event, and available pore space of the ore within the PSSAs. The model also simulates an eight -year post- mining leaching period, when no ore is placed on the VLF and solutions are applied to the ore, and considers the dynamic characteristics of the ore heap, which affect the timing of solutions reporting to the PSSAs. In addition to the GoldSim© model, CC &V maintains a spreadsheet- based, operational water balance model, which is managed daily by the Chief Site Metallurgist. The operational model considers rates at which solutions are applied to active areas of the VLF, ore moisture, precipitation, freshwater makeup to the ADR Plant and barren solution tanks, pump back from Arequa Gulch (underdrain flows) and the External Storage Pond, evaporation, and ore take up. Conservatively, the only loss considered by the water balance model, other than evaporation, is moisture up take by the ore. Because CC &V maintains diesel - powered, backup generators at the ADR Plant and because the VLF is designed to contain draindown resulting from a 12 -hour power outage, the water balance model itself does not directly consider the effects of power outages or equipment failures. CC &V collects onsite precipitation data from a meteorological station and enters the onsite precipitation data into the operational water balance on a monthly basis. The water balance model does not directly account for freezing and thawing effects; however, snowmelt (measured as inches in the precipitation data collected on site) is entered into the operational water balance on a monthly basis. Surface water flow from upslope drainage areas is diverted away from the process facilities by engineered structures. The primary operating criteria for the VLF include the maximum operating volumes of each PSSA (80 percent capacity), maximum hydraulic head on the secondary liner in each PSSA (2 feet), and maximum hydraulic head on the secondary liner in the External Storage Pond (2 feet). Pursuant to the Mining and Reclamation Permit, CC &V monitors the operating parameters of the water management facilities regularly, and deviations from the normal operating criteria require further action provided by written contingency procedures. Operations personnel monitor solution levels on a daily basis and provide results to the Chief Site Metallurgist for incorporation into the operational water balance. In addition to the routine inspection and monitoring performed by CC &V, the DRMS monitors solution levels on a monthly basis. Cresson Project ��- September 22, 2010 Name of Mine Signature of Lead Auditor Date Page 13 of 36