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Formation and Silver Plume Granite at the Henderson Mill site, approximately 60 miles to the <br />north and east of the Climax Mine. A summary of these packer tests is presented in Appendix <br />C. These data show that the average hydraulic conductivity of the Precambrian bedrock is <br />3.6 x 10" centimeters per second (cm /sec), which is considered a low to very low hydraulic <br />conductivity (Lambe and Whitman, 1969). <br />The summary data in Appendix C also show a definite trend of decreasing hydraulic <br />conductivity with depth. This trend corresponds to a decrease in fracture frequency which was <br />noted in the coring logs. Therefore, jt is evident the Precambrian Idaho Springs Formation <br />and Silver Plume Granite become less permeable with depth. <br />Based on the packer test data, the Precambrian bedrock is considered relatively impermeable <br />as compared to typical ranges of hydraulic conductivity for the overlaying glacial and alluvial <br />material [10 to 10-4 cm /sec (Freeze and Cherry, 1979)]. Therefore, the Precambrian bedrock <br />is not considered capable of transmitting significant quantities of ground water. <br />Water Balance Data <br />In addition to the packer tests, the low permeability of the Precambrian bedrock is evident <br />from water balance data for the Climax mine dewatering sump and estimated recharge to the <br />underground mine workings. The recharge /discharge record for 1984 is presented in Figure 1 <br />of Appendix D. This figure shows that the total annual recharge to the underground workings <br />(via precipitation and snow melt through the Glory Hole) balances very closely to the mine <br />pump discharge record. The closeness in the discharge /recharge record demonstrates that the <br />vast majority of water pumped from the underground workings was from precipitation <br />recharge and that ground water entering the mine workings from the surrounding intact rock <br />mass is a minor component of the overall inflow. <br />It is important to note that the underground workings at Climax covered an area of <br />approximately 9 million square feet with an average depth of 600 feet. The dewatering <br />operation for these workings would have created a significant sink to ground water. Since the <br />water balance data demonstrates only a small total contribution from bedrock ground water, it <br />can then be inferred that the Precambrian bedrock has a very low permeability. If the <br />