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W 'W RESOURCE <br />HYDROGEOLOGIC <br />V SERVICES <br />II Mine facilities. The sample collection locations are shown in Figure 1. The upstream ditch water <br />contains concentrations of total dissolved solids (TDS, the top of the stacked bars) that are less than <br />300 mg/L, and the downstream ditch water contains highly variable concentrations of TDS, ranging <br />from 100 mg/L, to 700 mg/L, reflecting a potential seasonal variability in the downstream water quality. <br />Concentrations of sulfate and chloride are greater in the downstream ditch water, especially during the <br />fall and winter months, which are also a potential seasonal trend. Measured pH of the ditch water <br />indicates slightly alkaline to alkaline (pH 7.8 to 8.7) conditions, with concentrations of nitrate, total <br />organic carbon, and trace metals all below the applicable drinking water standards for samples <br />collected from the Hay Gulch ditch. <br />ALLUVIAL GROUNDWATER <br />Water analyses of samples collected from three alluvial wells are shown in Figure 3. The three <br />sampling locations are shown in Figure 1. The Wiltse well is close to the historical King I Mine facilities, <br />the Well #1 Upgradient is roughly halfway between the Wiltse well and the mouth of the side gulch in <br />which the King II Mine facilities are located, and the Well #2 Downgradient is in Hay Gulch downstream <br />the King II Mine facilities. <br />Major ion analyses from these three alluvial wells do not show a steady increase in salinity in the <br />direction of flow, as the January 2016 King I & II Coal Mine Area Hydrology Study Report (RHS 2016) <br />prepared by RHS on behalf of GCC showed. That report also showed that salinity in the Wiltse well <br />varied considerably over its 33 year record of sampling, with TDS typically between 1,500 and 2,000 <br />mg/L but also reaching as much as 2,500 and as little as 1,000 mg/L. The pattern of variability did not <br />appear to correlate with mining activity. Figure 4 is taken from that report. Concentrations of sulfate in <br />the Wiltse well continue to be much greater than measured in Well #1 Upgradient and Well #2 <br />Downgradient, and may reflect an influence of coal material in contact with alluvial water. The location <br />of the Wiltse well adjacent to the historical King I Mine and visible coal deposits in the natural hillslopes <br />suggests that the interaction of alluvial water and coal deposits is likely. <br />The January 2016 Hydrology Study Report (RHS 2016) also indicated that total salinity (TDS) was <br />approximately 500 to 600 mg/L in Well #1 Upgradient and Well #2 Downgradient between 2005 and <br />2015, with a noted greater sulfate concentration observed in Well #2 Downgradient. In the 2016 <br />samples (Figure 3), Well #1 Upgradient showed greater TDS than in Well #2 Downgradient, accounted <br />for by greater sodium and sulfate concentrations. The downstream Well #2 Downgradient showed very <br />little sodium in the 2016 samples. Variation in the major ion chemistry between Well #1 Upgradient and <br />Well #2 Downgradient may be related to localized variations in flow and soil composition. <br />In general, the alluvial groundwater in Hay Gulch is not used for drinking water, mostly because the <br />sulfate is naturally elevated in some wells and emetic even for stock. Most alluvial water samples <br />exceeded the total dissolved solids drinking water standard of 500 mg/L. Concentrations of nitrate and <br />nitrite were less than the drinking water standard of 10 mg/L. However, traces of nitrate and nitrite up <br />to 1 mg/L in some well samples can be attributed to infiltration of stock urine (wildlife or cattle). Two <br />GCC ENERGY, LLC <br />2016 ANNUAL HYDROLOGY REPORT <br />6 <br />