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Schwartzwalder Mine -Hydrologic Evaluation of Mine Closure and Reclamation 1 ~ <br />In general, LSGH, MS, and Schwartz Trend rocks have low primary permeability. Underground <br />observation suggests that regional faults and associated fracture systems control the limited occurrence and <br />flow of groundwater in bedrock. The primary structural features present at the mine include the West <br />Rogers Fault, which strikes northwest and dips steeply to the northeast, and the Illinois Fault, which strikes <br />north and dips steeply to the west (Figure 3). These two fault systems combined with high angle pegmatite <br />dikes, steeply dipping regional foliation, and the high relief of the project area impart a strong vertical <br />component to groundwater flow system. <br />4.1.1 Depth to Water and Groundwater Flow <br />Information about the depth to water and groundwater flow in bedrock is available from two monitoring <br />wells, MW10 and MW11, which are located on the hillside above the mine (Figure 5, Figure 1). <br />Groundwater gradients in bedrock near the mine and on the slopes beside Ralston Creek, are dominantly <br />vertical as demonstrated by water levels in MW10 and MW11. Monitoring well MW11 is completed in <br />bedrock to a depth of 200 feetb, where observed water level ranged from 82 to 122 feet below top of the <br />casing (btoc). Shallow monitoring well, MW10, is located adjacent to MW11 and was installed to evaluate <br />the vertical gradient in the area of the mine. MW 10 is completed to a depth of 75 feet' and is dry for much <br />of the year. In 1999, the depth to groundwater in MW 10 was observed to be 67.2 ft btoc in May and 71.25 <br />ft btoc in September. On the same dates, water levels in MW11 were measured to be 82.89 and 89.10 ft <br />btoc (Table 8). Using the mid-point of the saturated screened intervals in the two wells as reference points, <br />the downward vertical gradient near the mine is calculated to vary from 0.15 to 0.17 (Table 9). <br />Both wells exhibit marked seasonal variation in water levels. MW 10 is commonly dry, as it was when <br />measured most recently on November 2, 2007. MW 11 has not been dry when measured, although its water <br />level varies significantly with the seasons, as shown in Figure 9. Note that limited water level data are <br />available for MW11 because the road leading from the mine site has been reclaimed, and access is now <br />limited. <br />Table 8. Water Levels and Well Data for Bedrock Monitoring Wells MW10 and MW11 <br /> Mid-Point of <br /> Depth to Collar Water Top of Well Bottom of Saturated <br />Date Well Water Elevation Elevation Screen Well Screen Screen <br /> (ft. btoc) (ft. amsl) (ft.amsl) (ft.amsl) (ft.amsl) ft.amsl <br /> 36 <br />7370 36 <br />7320 7323.51 <br />5/27/99 MW10 <br />MW11 67.20 <br />82.89 7393.86 <br />7394.27 7326.66 <br />7311.38 . <br />7244.27 . <br />7194.27 7219.27 <br /> <br />9/21/99 MW10 <br />MW11 71.25 <br />89.10 7393.86 <br />7394.27 7322.61 <br />7305.17 7370.36 <br />7244.27 7320.36 <br />7194.27 7321.49 <br />7219.27 <br /> <br /> <br />11/09/07 MW 10 <br />. ,..,.. >77.6 <br />~ ~~ n 7393.86 <br />72od ~~ <7316.26 <br />77721_7 7370.36 <br />7244.27 7320.36 <br />7194.27 N/A <br />7219.27 <br />a 200 ft is approximate total depth from ground surface when drilled in 1999. MW11 total depth was measured on 11/2/2007 at <br />189 ft below top of casing (btoc). <br />' 75 ft is approximate total depth from ground surface. MW10 total depth was measured on 11/2/2007 at 77.6 ft below top of <br />casing (btoc). <br />Whetstone Associates <br />4109B.071116 <br />