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John Hamrick and Randy Whicker <br />Cotter Corporation (N.S.L) <br />October 10, 2011 <br />Page 2 <br />2.2 Uranium, Molybdenum, and Ra -226 Chemistry <br />amee) <br />concentrations of sulfate, bicarbonate, magnesium, and TDS. Sump No. 10 contains major ion <br />and TDS concentrations that are intermediate between upgradient alluvial groundwater and <br />mine pool water. With increasing distance downgradient of Sump No. 10 (Figures 1 and 2), <br />major ion concentrations in alluvial groundwater decrease, but remain above those observed at <br />the upgradient locations (MW -0, MW -1, Sump No. 9). <br />When plotted on a trilinear diagram, both the cation and anion composition of the alluvial <br />groundwater migrates linearly toward a mine pool signature with increasing distance <br />downgradient in the alluvium from MW -1 (Figure 3). Further analysis using a Durov Plot (Figure <br />4) also shows a linear migration of major ions, TDS, and pH toward that of mine pool water. <br />These results are consistent with conservative mixing of alluvial groundwater and mine pool <br />water. Of the alluvial groundwaters analyzed, Sump No. 10 contains a major ion signature which <br />is most similar to that of mine pool water (Figures 3 and 4). <br />Sump No. 10 also contains elevated concentrations of uranium (16.6 mg /L) compared to the <br />other upgradient and downgradient alluvial groundwater evaluated (0.262 — 3.05 mg /L) (Table <br />1). Prior to pumping at Sump No. 10, uranium concentrations in alluvial groundwater at this <br />location were intermediate between upgradient Sump No. 9 and downgradient Sump No. 4 <br />(Figure 5). However, since pumping began, uranium concentrations in Sump No. 10 have <br />increased to a maximum of 20,660 ug /L (20.66 mg /L). The current concentrations of uranium in <br />Sump No. 10 are lower than those observed in the mine pool water (26.4 mg /L) but elevated <br />compared to other upgradient and downgradient alluvial groundwater (Table 1, Figure 5). <br />A comparison of recent Sump No. 10 uranium concentrations to mine pool water and alluvial <br />groundwater across the site (Figure 6) shows similar trends to those of TDS and major ions <br />(Figure 2). Sump No. 10 contains uranium at a concentration that is intermediate between <br />upgradient alluvial groundwater and mine pool water. With increasing distance downgradient of <br />Sump No. 10, uranium concentrations in alluvial groundwater decrease, but remain above those <br />observed at the upgradient locations (MW -0, MW -1, Sump No. 9) (Figure 6). <br />Similar to uranium, the most elevated concentrations of molybdenum occur in mine pool water, <br />and with concentrations in Sump No. 10 that are intermediate between mine pool water and <br />other alluvial groundwater (Figure 6). Radium -226 activities are also most elevated in the mine <br />