Laserfiche WebLink
concentrations in backfill well GF -7 overall gradually declined in 2010 and 2011 and slightly <br />increased in 2012. The water levels for the last few years have been fairly similar in well GF -7, <br />indicating that these changes are not due to new backfill being saturated but likely due to variations <br />in recharge. Sulfate concentrations have stayed low and steady in backfill well GF -5. These small <br />changes may be defining the very small effects of upgradient mining but the changes are well within <br />natural ranges. This monitoring indicates that if the HI aquifer has been affected in these wells by <br />upgradient mining, it has been very small. <br />Sulfate concentrations in well GMP -1, which are shown on Figure B -12, have been highly <br />variable indicating an increasing trend during 2006 and 2007 and an overall similar increasing trend <br />in 2008 through 2012. The water level in well GMP -1 had been steadily increasing for several years <br />prior to becoming fairly steady in 2002 and then gradually increasing the last seven years prior to a <br />small decline in 2012. Sulfate concentrations may stay higher and variable while water levels are <br />gradually increasing. Sulfate concentrations in this well should be influenced by the sulfate <br />concentrations in the backfill aquifer upgradient of GMP -1. The sulfate concentrations in well GP -3 <br />had shown a gradual increasing trend but concentrations have been steady the last ten years. Overall <br />steady sulfate concentrations have been observed in well GP -7. Sulfate concentrations in eastern HI <br />aquifer well GC -1 have been similar to the previous higher values in well GMP -1 and had to be <br />natural until the last few years. Therefore, a sulfate concentration of at least greater than 600 mg/1 is <br />needed to indicate that the increases may be due to the mining operation. The 2012 value from well <br />GC -1 was similar to past values. <br />Figure B -13 presents the sulfate concentrations for three 3rd White Sandstone wells. The last <br />eleven years of sulfate values from well P -8 had overall gradually decreased while the 2012 value is <br />a small increase. The magnitude and timing of the prior increase in sulfate concentrations in well P -8 <br />Trapper Mining Company 3 -6 <br />2012 Annual Report <br />