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Colowyo Coal Company <br />2013 Annual Reclamation and Hydrology Report <br />Evaluation of2013 data for LTC <br />No results from 2013 sampling were minimum or maximum values for any parameters <br />listed above during the monitoring period. Trend line analysis determined no significant <br />correlations over time. No samples were taken during the third and fourth quarter of <br />2013 due to the fact the stream was dry at the time of sampling. <br />GENERAL TRENDS - Groundwater <br />Colowyo currently samples each groundwater site for a variety of quality parameters. Of <br />all the parameters that are analyzed for, several key indicator parameters are identified. <br />These are lab pH, lab conductivity, TDS, sulfate, calcium, iron, magnesium, sodium and <br />elevation. Statistical analysis is completed and illustrates historical trends for each <br />parameter in Exhibit 2B. <br />Ground Water Data - The R2 values for linear regression of the trend lines of the graphs <br />in Exhibit 2A were evaluated. Only one trend was identified as being potentially <br />significant, TDS at the Gossard Well location, therefore, it is the only information <br />provided in summary format below. Overall, analysis supports the assumed probable <br />hydrologic consequences of minimal impacts to groundwater due to mining activities. <br />Site Id TDS <br />Gossard 0.8003 <br />Summary of the indicator parameters for each ground water site is provided in the <br />following tables. <br />A -6 Well: <br />Parameter <br />Mean <br />Std dev <br />Range <br />Max. <br />Min. <br />Max at <br />Min at <br />Lab pH <br />7.69 <br />0.36 <br />1.9 <br />8.6 <br />6.7 <br />11/30/93 <br />11/21/02 <br />Lab Cond. <br />1106.75 <br />79.33 <br />512 <br />1440 <br />928 <br />05/01/85 <br />04/27/98 <br />TDS <br />695.35 <br />88.92 <br />750 <br />930 <br />180 <br />07/17/01 <br />03/13/93 <br />Sulfate <br />140.75 <br />55.16 <br />334.2 <br />430 <br />95.8 <br />07/17/01 <br />05115100 <br />Calcium <br />63.47 <br />17.57 <br />121.1 <br />169 <br />47.9 <br />11/18/97 <br />11/13/00 <br />Iron <br />0.30 <br />0.42 <br />1.81 <br />1.82 <br />0.01 <br />09/26/98 <br />11/18/97 <br />Magnesium <br />54.95 <br />16.57 <br />128 <br />169 <br />41 <br />11/18/97 <br />03/21/11 <br />Sodium <br />122.46 <br />19.51 <br />128.1 <br />146 <br />17.9 <br />3/11/08 <br />04/27/98 <br />Elevation <br />6897.98 <br />2.88 <br />14.53 <br />6902.53 <br />6888 <br />05/01/85 <br />07/31/00 <br />Evaluation of 2013 data for A -6 Well <br />No results from 2013 sampling were minimum or maximum values for any parameters <br />listed above during the monitoring period. Trend line analysis determined no significant <br />correlations over time. <br />Page 2 -5 <br />