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Whetstone <br />Associates <br />Technical Memorandum <br />Table 8-5. Completion Data for Bedrock Monitoring Wells <br /> Total Depth to Screened Completion <br />Well Completion <br />Depth <br />Bedrock Well <br />Interval Depth to <br />ID Date (ft) (ft) Construction (ft) Water <br /> ft <br />MW 10 10/23/1998 75 5 4" PVC 25 - 75 67.2 <br />MWl 1 10/26/1998 200.0 5 4" PVC 150 - 200 82.89 <br />MW 13 to be completed TBD TBD 2" PVC TBD TBD <br />MW14 to be completed TBD TBD 2" PVC TBD TBD <br />Note: TBD = to be determined, proposed depths and screened intervals are provided in Section 15(c). The deepest well is <br />expected to be 300 feet deep and the shallower well is expected to be 80 to 120 feet deep. <br />4) Operator states on pg. 8-37 "Ralston Creek does not appear to be in strong hydraulic connection <br />with the Schwartzwalder Mine based on stream flow rates, mine pumping rates, and isotopic <br />comparison of mine water and surface water. " <br />DRMS does not agree with this statement. Considering the elevated concentrations of uranium and <br />molybdenum in the mine pool, adverse impacts to Ralston Creek could result from relatively small <br />inflow rates that might not be discernible in the stream flow or isotopic data. Please provide an <br />evaluation ofpossible seepage from the mine pool to the alluvium. <br />Flow must be distinguished from chemistry. Section 8 of the EPP addresses the hydrologic flow <br />system. The flow data collected over time clearly indicates that there is not a strong hydraulic <br />connection between the Ralston Creek and the mine. <br />Groundwater chemistry was discussed in Section 9 of the EPP. DRMS's observation that "impacts <br />to Ralston Creek could result from relatively small inflow rates" does not alter the fact that flow <br />rates between the creek and the mine (during dewatering) and between the mine and the creek (after <br />flooding) are so low as to be unmeasurable. <br />A mixing calculation to evaluate the potential range of mine water seepage was presented in Section <br />9(b)(ii).1 (page 9-5) of the April 19, 2010 EPP. Although DRMS subsequently stated that the <br />evaluation should be disregarded (Bird, July 12, 2010), the seepage evaluation has been retained in <br />the current version of the EPP in response to this written comment. <br />5) Operator states on pg. 8-41 "These results indicate that mine pool is not contributing loading to <br />Ralston Creek at this location. " This issue requires further analysis to more thoroughly assess any <br />connection between the mine pool, the regional ground water gradient and possible hydraulic <br />communication along the Schwartz Trend. A lack of geochemical evidence for a connection at <br />present should not be taken as irrefutable evidence that a connection does not or will not exist in the <br />future under conditions of hydraulic equilibrium. <br />The text in Section 8(e)(ii) of the revised EPP has been modified as follows: <br />These results indicate that mine pool is not contributing loading to Ralston Creek at this location at <br />this time. <br />4109C.100731