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1 <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br />1 <br /> <br /> <br />LJ <br /> <br />1 <br /> <br /> <br /> <br /> <br />• i <br />Water samples collected during the pump tests followed the QA/QC protocols as identified in <br />the submittal for Technical Revision-06 (Halepaska and Associates, Inc., April 1992). <br />HYDROGEOLOGIC ASSESSMENT FROM MONITORING WELL DATA <br />The uppermost water-bearing strata in the vicinity of the tailings facility and collection pond is <br />in the Santa Fe Formation and is generally at a depth of approximately 140 to 190 feet (Table <br />3). By triangulating the water level elevation data and contouring the potentiometric surface in <br />the Santa Fe Formation, it is estimated that the local ground water gradient is approximately <br />0.05 feet per feet (ftlft). With an average aquifer hydraulic conductivity of 0.2 ft/day, and an <br />estimated effective porosity in the Santa Fe Formation of 25 percent, it is estionated that tl+e <br />aquifer seepage velocity is 0.04 ft/day (14.6 ft/yr). These data indicate very slow-moving <br />ground water, with the estimated travel time from the collection pond to Battle Mountain's <br />downgradient property boundary of 1 LO years. <br />Given a width of the tailings facility of 2,000 feet, a saturated interval of approxyrnately 20 feet <br />and an average hydraulic conductivity of 0.2 ftlday, it is estimated that this Flow window can <br />ot~` transmit 2.1 gpm. Overall, these Flow characteristics are extremely tight. However, this is <br />believed consistent with recharge through 150 feet of tight Santa Fe Formation On a hill at the <br />upper end of the drainage. <br />Using geologic data obtained from the logging of monitoring wells M-9, M-12 and M-13, as <br />well as interpretation of the geophysical logs, a structural contour map of the base of the <br />production interval in M-9 and a geologic cross-section have been prepared whJch depict our <br />interpretation of the alluvial deposits and underlying Santa Fe Formation in the vicinity of tl+e <br />tailings facility and collection pond. The structural contour map of the base of the production <br />interval in M-9 is presented in Figure 8. The location of the geologic cross-section is shown <br />in Figure 1, and the geologic cross-section itself is presented in Figure 9. As indicated, <br />lithologic bedding planes in the Santa Fe Formation dip to the northwest at approximately 20 <br />-6- <br />1 <br />