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For Middle Grassy Valley shallow alluvium ground water is generally characterized as a <br />calcium- sulfate water, similar to the surface waters. Shallow and deeper bedrock ground <br />waters (when present) also are characterized as sodium - bicarbonate to calcium- sulfate <br />waters. Median field pH values in the shallow to deeper bedrock (monitor wells) to range <br />from 6.18 to 7.67. Median nitrate values range from <0.05 mg/L -N to 0.73 mg/L -N. <br />Median sulfate values range from <10 mg/L to 583 mg/L. Field pH values in the <br />alluvium (piezometers) to range from 4.04 to 6.79. Nitrate values range from 0.59 <br />mg/L -N to 5.92 mg/L -N. Sulfate values range from 57.9 mg/L to 712 mg/L. <br />There are two boreholes screened in shallow, alluvial /colluvial materials in Lower Grassy <br />Valley. These monitoring sites range in depth from 29 to 39 feet bgs. Ground water <br />levels in the alluvium are dry at 28 and 39 feet below the measuring point. There are six <br />monitor wells screened in shallow bedrock (defined as less than 200 feet in depth) in <br />Lower Grassy Valley. Of these six monitor wells, two are in the diatreme and the <br />remainder are in the granite bedrock. The wells range in depth from 30 to 100 feet bgs. <br />Ground water levels in shallow bedrock monitor wells vary from <1 to 100 feet below <br />measuring point. Deeper bedrock ground water monitoring wells (defined as greater than <br />200 feet) include two in Lower Grassy Valley both of which are in the diatreme. Ground <br />water levels in the deeper bedrock monitor wells are relatively stable at 128 feet below <br />measuring point for GVMW -24A and variable from approximately 110 -150 feet below <br />measuring point for GVMW -8A. As with the rest of Grassy Valley, the timing and <br />magnitude of the peaks in water level in the monitor wells, piezometers, and boreholes <br />appear to be related to the melting and infiltration of the snow in the spring months and <br />the precipitation events in the summer and fall months. Note that many of the shallow <br />and deeper bedrock wells are dry, particularly in Upper Grassy Valley, due to the <br />drainage of bedrock water into the diatreme. <br />For Lower Grassy Valley shallow alluvium ground water is generally characterized as a <br />calcium- sulfate water, similar to the surface waters. Shallow and deeper bedrock ground <br />waters (when present) also are characterized as calcium- sulfate waters. Median field pH <br />values in the shallow bedrock and deeper bedrock range from 6.0 to 7.91. Median <br />nitrate values range from <0.05 mg/L -N to 1.52 mg /L -N. Median sulfate values to range <br />from 16.4 mg/L to 83 mg /L. <br />Additional details on the monitoring wells in Grassy Valley can be found in Appendix 2 <br />in Volume II. <br />Cripple Creek & Victor Gold Mining Company <br />Cresson Project Mine Life Extension 2 <br />4 -18 <br />