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obtained during the Response Plan indicates that the increase in TDS is naturally occurring and is <br />likely due to such factors as the further dissolution of calcite, flushing of salts from the unsaturated <br />zone above the water table, and changes in sampling protocols over time. <br />Water quality results from well M -14 show that it is a calcium - bicarbonate water, which is <br />consistent with the geology of the Santa Fe Formation at the San Luis Project site. The results <br />show that the water chemistry 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/l. 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 slightly. Additionally, through 2012, 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 the salts (calcium, bicarbonate, sulfate, chloride etc.) from <br />the unsaturated zone above the water table, leading to the slightly higher calcium and TDS levels <br />in well M -14. <br />The increased TDS variability seen in 2008 through 2013 is likely attributable to the removal of <br />the dedicated pump from the well at this time and changes to the sampling protocols. While issues <br />with parameter stabilization persisted during this time, the amount of water purged and subsequent <br />mixing of waters from various natural sources around well M -14 decreased, likely resulting in <br />higher TDS concentrations. The low -flow sampling technique utilized in the Response Plan <br />reduced this variability. <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 changes in the site conditions (water levels, pH) over time, it is likely that the increased <br />calcium and alkalinity are naturally occurring rather than a result of any LTF leakage. In fact, the <br />absence of increases in sodium in well M -14 preclude significant leakage from the LTF. <br />TR -32 M -14 TDS Response Plan Report AES, Inc. <br />Battle Mountain Resources — San Luis, CO 14 January 2015 (Update) <br />