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sulfate concentrations in well GD -2 indicate the QR aquifer near well GD -2 may have started to be <br />affected by the upgradient backfill aquifer water quality. <br />Figure B -9 also presents sulfate concentrations for additional QR wells. This figure shows <br />that sulfate concentrations in backfill well GF -11, which is upgradient of QR well GF -6, were <br />decreasing in 2006 and 2007, and overall steady in 2008 through 2012 showing a decline from the <br />historic peak in 2001. Future monitoring is needed to define the maximum sulfate concentration in <br />this backfill aquifer which may have been defined in 2001 and 2002. The sulfate concentrations <br />gradually increased in well GF -6, downgradient of well GF -11. Sulfate concentrations for the last <br />few years had also overall gradually increased in QR well GP -5 until becoming fairly steady the last <br />few years. <br />Figure B -10 presents the sulfate concentrations for KLM aquifer wells GP -2, GP-4 and GP -8. <br />Sulfate concentrations in eastern well GP -2 have varied significantly but were similar in 2012 to <br />historic values. These changes are within the natural historic range defined at this well prior to <br />mining in this area. Overall steady sulfate concentrations in well GP-4 have existed the last few <br />years with the 2007 and 2008 levels at lower levels and the 2009 through 2012 values at a higher <br />concentration. Sulfate concentrations in well GP -8 have stayed steady and small as mining <br />approaches this area. <br />Sulfate concentrations for the HI aquifer wells are presented in Figures B -11 and B -12. The <br />sulfate concentration in wells in the HI aquifer wells in Figure B -11 are fairly similar except for the <br />values in backfill well GF -7, which are substantially greater than those in downgradient well GF-4. <br />Steady sulfate concentrations have been observed in well GF-4 after a very gradual increase for <br />several years. These small variations are well within the natural variation of sulfate concentrations in <br />the HI aquifer but could be defining the very small effects of the backfill aquifer upgradient. Sulfate <br />Trapper Mining Company 3 -5 <br />2012 Annual Report <br />