2012-02-28_REVISION - M1980244 (95)

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ground water resources above GV -01 (see Figure 2 -2 for WHEX limits). The development of WHEX also will capture a portion of the precipitation (snow and rain) in the upper reaches of Grassy Valley, which will be infiltrated to the Diatreme. However, due to the widespread and on -going vertical drainage of the Diatreme and adjacent granites in the upper, middle, and lower reaches of Grassy Valley, the impacts to the shallow and deep bedrock ground water resources in the middle and lower reaches of Grassy Valley will be minimal in the monitor wells, piezometers, and boreholes. The water quality in the remaining monitor wells, piezometers, and boreholes completed in the alluvium and bedrock in the middle and lower reaches of Grassy Valley is expected to be stable and perhaps improve with removal of historic mine features in the upper and middle reaches of Grassy Valley. Water quality conditions in the water that infiltrates to the Diatreme will be controlled by hydrogeochemical conditions detailed in "Cresson Project Hydrogeochemical Evaluation" dated February 2012 and prepared by ABC. The development of WHEX will remove many of the monitor wells, piezometers, and boreholes in the upper reaches of Grassy Valley. The development of the ECOSA will remove numerous monitor wells, piezometers, and boreholes in the middle reaches of Grassy Valley on the south side of the valley. The monitor wells, piezometers, and boreholes that will be lost to MLE2 are noted on Table 4. The ground water levels and water quality conditions in the Grassy Valley will continue to be monitored by the remaining monitor wells, piezometers, and boreholes listed in Section 3 and in Table 6 -4. 7.0 SUMMARY AND CONCLUSIONS Surface water data (flows and water quality) have been updated through 2011. Surface water flows in the major drainages of the District are generally low and dominated by seasonal runoff from snowmelt and precipitation. Flows in Cripple Creek and Wilson Creek also are sustained by waste water treatment discharges from the City of Cripple Creek and the City of Victor, respectively. The low surface flows in the District are due to the normal water balance processes (e.g., evapotranspiration) and the vertical drainage within the Diatreme created by the drainage tunnels installed in the early half of the 20 century. These tunnels (represented by the Carlton Tunnel) have lowered the ground water table and in turn, depleted the surface water flows Surface flows in Arequa Gulch also have declined in the last decade due to the phased implementation of the AGVLF, which has captured nearly all the precipitation in the upper reaches of the drainage. Water quality conditions of the surface waters in the District have remained relatively stable over the monitoring record for most of the monitor locations. The 9 "Cresson Project Hydrogeochemical Evaluation" dated February 2012 and prepared by ABC. 'Cripple Creek & Victor Gold Mining Company Cresson Project Hydrologic Evaluation for Mine Life Extension 2 39