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Based upon the geologic and hydrogeologic conditions, theoretical surface and ion - exchange <br />reactions, and analytical data, we believe that leakage from the LTF is not causing the variability <br />and increased levels of TDS. The variability and concentration changes of TDS in well M -14 over <br />time are a result of the increase in calcium and alkalinity over this period. Importantly, the lack of <br />a significant increase in the sodium and sulfate concentrations and the absence of other analytes in <br />well M -14 clearly shows that there has been no detectable mixing of LTF and well M -14 waters. <br />Water quality results from well M -14 indicate that the water is a calcium - bicarbonate water, which <br />has not changed significantly since the well was installed. <br />Laboratory testing of water collected from well M -14 in 1995 showed concentrations of TDS near <br />500 mg/l and in 1999 results were above 500 mg/1. Geochemical modeling of these results showed <br />the water at that time was undersaturated with respect to calcite. Over time, well M -14 has <br />transitioned to being slightly oversaturated with respect to calcite and remains that way today. <br />This transition has increased the calcium levels. Additionally, over this time period we have seen <br />a general rise of the water table at well M -14. It is believed that this rise in water level may have <br />rinsed out existing naturally occurring salts (calcium, bicarbonate, sulfate, chloride etc.) from the <br />unsaturated zone above the water table, leading to the slightly higher calcium, alkalinity and TDS <br />levels in well M -14. <br />In summary, the water levels, TDS, calcium, and alkalinity concentrations in M -14 have been <br />stable throughout the Response Plan sampling. Based upon the geochemical modeling performed <br />and observed changes in the site conditions (water levels, pH) over time, it is likely that the <br />increased calcium and alkalinity are naturally occurring rather than a result of any LTF leakage. <br />In fact, the absence of increases in sodium in well M -14 precludes significant leakage from the <br />LTF. <br />TR -32 M -14 TDS Response Plan Report AES, Inc. <br />Battle Mountain Resources — San Luis, CO 11 January 2015 (Update) <br />