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Colowyo Coal Company <br />2017 Annual Reclamation and Hydrology Report <br />LCG: <br />Parameter <br />Mean <br />Std <br />dev <br />Range <br />Max. <br />Min. <br />Max at <br />Min at <br />Lab pH <br />8.42 <br />0.11 <br />0.4 <br />8.5 <br />8.1 <br />03/13/13 <br />03/14/12 <br />Lab Cond. <br />990.57 <br />138.94 <br />539 <br />1230 <br />691 <br />03/18/14 <br />05/04/11 <br />TDS <br />673.21 <br />95.69 <br />420 <br />860 <br />440 <br />11/01/12 <br />05/24/17 <br />Sulfate <br />200.86 <br />44.62 <br />188 <br />288 <br />100 <br />11/01/12 <br />05/24/17 <br />Calcium <br />99.00 <br />11.89 <br />39 <br />114 <br />75 <br />11/01/12 <br />05/24/17 <br />Iron <br />0.98 <br />1.55 <br />7.12 <br />7.17 <br />0.05 <br />04/26/16 <br />08/18/11 <br />66.68 <br />10.07 <br />40 <br />80 <br />40 <br />08/01/12 <br />05/24/17 <br />-Magnesium <br />Sodium <br />26.79 <br />7.05 <br />27 <br />41 <br />14 <br />11/01/12 <br />03/22/11 <br />Flow rate <br />0.35 <br />0.49 <br />1.54 <br />1.57 <br />0.03 <br />05/04/11 <br />10/20/15 <br />Evaluation of 2017 datafor LGC <br />Minimum values for TDS, Sulfate, Calcium, and Magnesium were recorded during this <br />period. Mining impacts associated with the Collom expansion did not occur in 2017. <br />WFJC: <br />Parameter <br />Mean <br />Std <br />dev <br />Range <br />Max. <br />Min. <br />Max at <br />Min at <br />Lab pH <br />8.44 <br />0.11 <br />0.6 <br />8.6 <br />8 <br />11/19/13 <br />03/14/12 <br />Lab Cond. <br />1236.50 <br />146.06 <br />858 <br />1740 <br />882 <br />03/22/11 <br />05/04/11 <br />IDS <br />909.29 <br />125.08 <br />680 <br />1450 <br />770 <br />03/22/11 <br />05/04/11 <br />Sulfate <br />330.29 <br />71.75 <br />415 <br />651 <br />236 <br />03/22/11 <br />11/08/11 <br />Calcium <br />119.00 <br />8.98 <br />39 <br />135 <br />96 <br />11/05/14 <br />09/18/17 <br />Iron <br />0.40 <br />0.66 <br />3.52 <br />3.57 <br />0.05 <br />05/04/11 <br />08/18/11 <br />101.00 <br />11.47 <br />64 <br />143 <br />79 <br />03/22/11 <br />05/04/11 <br />-Magnesium <br />Sodium <br />19.54 <br />23.44 <br />126 <br />139 <br />13 <br />03/22/11 <br />11/29/17 <br />Flow rate <br />0.03 <br />0.03 <br />0.12 <br />0.13 <br />0.01 <br />05/15/11 <br />11/01/12 <br />Evaluation of 2017 data for WFJC <br />Minimum values for Calcium and Sodium were recorded in 2017. Mining impacts <br />associated with the Collom expansion did not occurred in 2017. <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 1 B. <br />Page 9 <br />