2012-12-06_PERMIT FILE - M2012032 (25)

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4.3 Surface Water Quality Overall, the pH of the surface water is approximately neutral. TDS ranges from 100 mg /liter for Sneffels upstream to 190 mg /liter for the Revenue Seep. The Atlas drainage, although high in zinc, the TDS is not outside of 100 -200 range. Samples of both the Seep and downstream Sneffels show a significant drop -off in zinc values versus the mine discharge. Table G -5 shows how zinc levels rise and fall along Sneffels Creek each quarter. The Atlas drainage values are included, since the Sneffels upstream sample point is upstream of the Atlas drainage as well, however, the Atlas was not sampleable in February 2012 since the surface water flows were frozen. The material at the Atlas portal is an alluvial fan, so it is believe that Atlas water flows below the surface down to Sneffels Creek. The Revenue Seep has a lower zinc concentration than the Revenue Mine Discharge, despite that at the time of sampling (Oct 2011) there was no water leaving the mine water pond via the spillway: all water was passing through the waste pile and likely coming out at the Revenue Seep. Due to the permeable nature of the waste pile, it is impossible to say with absolute certainty that the mine water is all coming out at the Seep. However, the estimated flow rates at the time of sampling suggest that most of the mine water was coming out at the Seep, meaning that some part of the hydrological process between the discharge of mine water into the pond and the Seep reduces the zinc content of the mine water. As discussed in the subsection on ground water, the mine water also showed dramatic reductions in zinc as the water passed through the Revenue Tunnel. Table G -5 shows the mass balance calculations for both the mine water and surface water flows. Zinc tends to drop out of the water both underground in the Revenue tunnel and in the surface water system. Exhibit T contains a detailed discussion about why SMO believes the zinc levels are dropping without treatment. The Q4 2011 samples of Sneffels upstream combined with the Atlas drainage compared to Sneffels downstream showed a drop in zinc, which was expected. The Q1 2012 samples showed an increase, which was a surprise. The mass balance in Table G -5 shows that there must have been another contributor to zinc before the downstream sample location was reached. John Trujillo, the company geologist and mine manager who is in charge of taking the samples, believes that although this sample period showed no flow in the Atlas drainage due to frozen conditions, water was still actually flowing Revenue Mine August 2012 G -17