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Environmental Protection Plan, Schwartzwalder Mine 9-43 <br />(iv).2 Evaluation of Chemical Trends in Mine Water as a Function o Time <br />Chemical trends in mine water were evaluated as a function of time by plotting concentrations for the <br />various constituents against the date sampled (Figure 9-9 through Figure 9-11). Observations from this <br />analysis are summarized as follows: <br />1. The ORP of the mine water has decreased with time from a high of near 517 mV during flooding to <br /> 22.8 mV in late 2007. <br />2. Prior to the November 2007, measured ORP varied from 83 to 517 mV. <br />3. The pH of mine water has remained relatively stable through time, fluctuating near 7 with no <br /> distinct trend toward acidification or increasing pH. <br />4. Bicarbonate alkalinity increased rapidly during initial flooding of the mine (from 280 to about 410 <br /> mg CaCO3/L). The rate of increase was slower after May 2001 and bicarbonate alkalinity currently <br /> appears to be stable between about 450 and 480 mg CaCO3/L. <br />5. After an initial rapid increase in TDS during flooding, TDS concentrations have stabilized at their <br /> current level of about 3,300 mg/L. <br />6. After an initial rapid increase in sulfate during flooding, sulfate concentrations have stabilized at <br /> their current level near 2,000 mg/L. <br />7. Sodium and chloride concentrations are stable near 200 mg/L and 30 mg/L respectively. <br />8. Calcium concentrations increased rapidly during the early flooding of the mine to about 280 mg/L <br /> by the fall of 2000 and them increased at a much slower rate to about 430 mg/L by September <br /> 2008. <br />9. Magnesium concentrations increased rapidly during the early flooding of the mine and have been <br /> stable between about 200 mg/l and 250 mg/l since about September 2000. <br />10. Potassium concentrations increased slowly from about 10 mg/L during early flooding of the mine <br /> to about 24 mg/L by October 2008. <br />11. Manganese concentrations have increased from about 1 mg/L during early flooding of the mine to <br /> more than 5 mg/L in 2008. <br />12. Molybdenum concentrations increased from about 1 mg/L at the start of mine flooding to a peak of <br /> about 2.6 mg/L in mid-2001. Since 2001, molybdenum concentrations have been steadily <br /> decreasing to near 1.4 mg/L in 2008. <br />13. Uranium concentrations increased from about 4 mg/L at the start of mine flooding to a peak of <br /> about 59.5 mg/L in October 2002. Since October 2003, uranium concentrations have been steadily <br /> decreasing to near 42 mg/L by 2008. <br />14. Dissolved iron concentrations were stable near or below the detection limit until spring 2007, and <br /> have ranged from 0.11 to 0.97 since November 2007. Total iron concentrations are generally <br /> significantly higher than dissolved Iron concentrations. <br />4109C.090807 Whetstone Associates 6