2012-02-28_REVISION - M1980244 (95)

Home Browse Search

alluvium (monitor wells, piezometers, and boreholes) are generally shallow at 9.83 to 37.18 feet bmp. Ground water levels in shallow bedrock monitor wells vary from 6.88 to 53.95 feet bmp. Ground water levels in the deeper bedrock monitor well vary from 185.88 to 218.65 feet bmp to dry ( >800 feet bmp). GVMW -3A, GVMW -12B, GVMW - 13B/C, GVMW- 14B /C, GVMW- 16A/B, GVMW -17A/B have been dry or have very limited sample data since installation. Figures 6 -3 and 6 -4 show the hand measured depths to water and pressure transducer calculated depths to water in the upper reaches of Grassy Valley. A comprehensive analysis of the horizontal and vertical ground water flow and ground water gradients in the Diatreme and the adjacent granites for the Cresson Project area, and specifically Grassy Valley is presented in "Cresson Project Hydrogeochemical Evaluation" dated February 2012 and prepared by ABC. The timing and magnitude of the peaks in water level in the monitor wells, piezometers, and boreholes appear to be related to the melting and infiltration of the snow in the spring months and the precipitation events in the summer and fall months. Water quality conditions for the monitor wells GVMW -1B, GVMW -2B, GVMW -3B, GVMW -5, and GVMW -21A in the upper reaches of Grassy Valley are provided in Tables 6 -5 through 6 -8, and 6 -29 respectively. Water quality conditions for the piezometers GVPZ -1, GVPZ -2, GVPZ -3, and GVPZ -4 in the upper reaches of Grassy Valley are provided in Tables 6 -9 through 6 -12, respectively. Shallow alluvium ground water is generally characterized as sodium- sulfate water. Shallow and deeper bedrock ground waters (when present) are characterized as sodium - bicarbonate to calcium- sulfate waters. The data in Tables 6 -5 to 6 -8 (monitor wells) show median field pH values for the shallow bedrock and deeper bedrock to range from 5.74 SU to 6.72 SU. Median nitrate values range from 0.60 mg/L as N to 10.7 mg/L as N. Median sulfate values range from <10 mg/L to 118.5 mg/L. The elevated values of nitrate and sulfate are from GVMW -5. This area will be mined by the WHEX surface mine The data in Tables 6 -9 to 6 -12 (piezometers) show median field pH values for the alluvium to range from 6.05 SU to 6.21 SU. Median nitrate values range from 0.08 mg/L as N to 2.2 mg/L as N. Median sulfate values range from 31.6 mg /L to 78.5 mg/L. Time series plots are provided in Figures 6 -5 and 6 -6. For discussion purposes, shallow bedrock monitor wells are completed at 200 feet or less. S For discussion purposes, deep bedrock monitor wells are completed greater than 200 feet. 'Cripple Creek & Victor Gold Mining Company Cresson Project Hydrologic Evaluation for Mine Life Extension 2 35