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geochemical modeling program PHREEQC (USGS). The model was utilized to simulate the <br />saturation states over time. The results indicated that well M -14 was slightly undersaturated with <br />respect to calcite shortly after installation of the monitoring well and transitioned to a the state of <br />being slightly oversaturated with respect to calcite today. This transition from undersaturated to <br />oversaturated with respect to calcite would result in increase in calcium and bicarbonate <br />concentrations in well M -14, which would increase the TDS concentration. As mentioned <br />previously, scaling issues with the well M -14 dedicated pump that was removed were likely caused <br />by this oversaturation of calcite. <br />4.3.4 CO2, Temperature, and pH Effects <br />The solubility of calcium carbonate (CaCO3) increases as pH decreases at constant temperature. <br />As the solution becomes more acidic, the solubility equilibrium will move toward the formation <br />of HCO3 and H2CO3. Therefore, in case of increasing CO2 input, which reduces pH, CaCO3 will <br />be more susceptible to dissolution. The solubility of CaCO3 will also increase with the decrease <br />of temperature and increase of CO2 partial pressure. Over time the pH levels found in well M -14 <br />have shown a slightly decreasing trend which would contribute to an increase in dissolution of <br />calcite. The decrease in pH could be a result of a cycle of oxidation and reduction of iron or other <br />redox sensitive species as a consequence of water level fluctuations and dewatering of well M -14 <br />during sampling. <br />5.0 PRECIPITATION CHARACTERISTICS <br />The San Luis Valley is surrounded by the San Juan and La Garita Range to the west and the Sangre <br />de Cristo Range to the east where the BMRI San Luis project is located. As a result of being <br />surrounded by these mountain ranges, the San Luis Valley has an extremely and climate and the <br />San Luis project generally receives between 4 to 7 inches of precipitation annually. The majority <br />of the precipitation falls during the summer months, with July and August usually receiving the <br />highest precipitation. <br />Publicly available precipitation data from The National Weather Cooperative Observer Program <br />(COOP), The Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS), and the <br />Colorado Agricultural Meteorological Network (CoAgMet) were reviewed to identify significant <br />TR -32 M -14 TDS Response Plan Report AES, Inc. <br />Battle Mountain Resources — San Luis, CO, 9 January 2015 (Update) <br />