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Hydro Investigation Results <br /> Santa Fe Formation-West Pit Battle Mountain Resources Inc. <br /> Using the Neuman method of analysis for an unconfined aquifer,the transmissivity estimated from <br /> the WP-6 pumping test was 0.094 ft3/d. The hydraulic conductivity is estimated at 0.0027 ft/d. A <br /> plot of the graphical analysis is provided in Figure 5. <br /> As previously described, storativity of the Santa Fe Fm aquifer could not be reliably estimated <br /> from the pumping well data. <br /> 4.0 SANTA FE FORMATION GROUNDWATER DISCHARGE TO THE WEST PIT <br /> The rate of groundwater discharge from the Santa Fe Fm into the West Pit through the alluvial <br /> window is estimated using the following equation: <br /> Q=Kia <br /> where Q=groundwater discharge (ft3/d) <br /> K=hydraulic conductivity of the alluvial aquifer(ft/d) <br /> i=hydraulic gradient(ft/ft), and <br /> a=cross-sectional area perpendicular to flow (ft2) <br /> A similar calculation was performed for the alluvial aquifer following the testing that was <br /> completed in May 2021. In that calculation, a hydraulic gradient of 0.10 ft/ft was used to represent <br /> flow from the alluvial aquifer into the southeast side of the West Pit along a distance of 488 feet. <br /> Because the water level in the Santa Fe Fm appears to be similar to that observed in the alluvial <br /> monitor wells, it is reasonably assumed that the hydraulic gradient of the Santa Fe Fm aquifer will <br /> also be similar to the alluvial aquifer. The saturated thickness of the Santa Fe Fm is approximately <br /> 30 feet. The cross-sectional area along the line is 14,650 ft2 (488 ft x 30 ft). The hydraulic <br /> conductivity of the Santa Fe Fm aquifer estimated from the WP-6 pumping test averages <br /> approximately 0.003 ft/d. The calculation of discharge from the Santa Fe Fm into the West Pit <br /> along the alluvial window follows: <br /> Q=0.003 ft/d x 0.10 ft/ft x 14, 650 ft2=4.395 ft3/d <br /> Q=4.395 ft3/d x ld/1440 min x 7.48 gal/1 ft3=0.022 gpm <br /> The calculated discharge from the alluvial aquifer was 173 gpm compared to 0.022 gpm for the <br /> Santa Fe Fm. These calculations indicate that the alluvial aquifer system provides the bulk of the <br /> water that flows into the West Pit,under the current pumping conditions. <br /> 5.0 SUMMARY <br /> EA conducted an investigation to further characterize hydrologic properties of the Santa Fe Fm <br /> aquifer along the southeast edge of the West Pit where groundwater flows into the pit through an <br /> alluvial window. The volume of groundwater water entering into the West Pit through this alluvial <br /> window relative to that entering from the surrounding bedrock is a critical factor in evaluating the <br /> long-term effectiveness of potential remedial alternatives such as a slurry wall, interceptor trench, <br /> or extraction wells. <br /> February 2023 7 Engineering Analytics,Inc. <br />