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Colowyo Coal Company <br />2008 Annual Reclamation and Hydrology Report <br />Colowyo currently samples each ground water site for a variety of quality parameters. <br />Of all the parameters that are analyzed for, several key indicator parameters are <br />identified. These are lab pH, lab conductivity, TDS, sulfate, calcium, iron, magnesium, <br />sodium and elevation. Statistical analysis is completed and illustrates historical trends <br />for each parameter in Exhibit 2B. <br />Ground Water Data - The R2 value for linear regression is indicated below. <br />Site Id Lab <br />pH Lab <br />Conductivity TDS Sulfate Calcium Iron Magnesium Sodium Elevation <br />(feet) <br />A-6 0.0528 0.0106 0.0383 0.0008 0.0006 0.0013 0.0039 0.0663 0.0004 <br />A-7 0.25 0.7184 0.7737 0.7982 0.6869 0.75 0.7378 0.5771 0.83 <br />A-8 0.75 0.75 0.75 0.0111 0.9985 0.75 0.0577 0.8421 0.9778 <br />NGSW 0.0188 0.0626 0.0979 0.0002 0.0169 0.2329 0.00005 0.2587 0.0257 <br />Gossard 0.021 0.6185 0.7849 0.6839 0.4093 0.081 0.4321 0.0616 0.4994 <br />MT-95- <br />02 0.5729 0.0777 0.8998 0.0421 0.0376 0.6 0.3208 0.0257 0.645 <br />Summary of the indicator parameters for each ground water site is provided in the <br />• following tables. <br />A-6 Well: <br />Parameter Mean Std dev Range Max. Min. Max at Min at Trend <br />Lab pH 7.60 0.3476 1.9 8.6 6.7 11/30/93 11/21/02 Increasing <br />Lab Cond. 1115.01 80.1968 510 1440 930 05/01/85 04/27/98 Increasing <br />TDS 695.59 99.9761 750 930 180 07/17/01 03/13/93 Increasing <br />Sulfate 147.54 60.5074 334.2 430 95.8 07/17/01 05/15/00 Increasing <br />Calcium 64.25 18.62 121.1 169 47.9 11/18/97 11/13/00 Decreasing <br />Iron 0.37 0.4638 1.81 1.82 0.01 09/26/98 11/18/97 Decreasing <br />Magnesium 55.84 17.1241 127 169 42 11/18/97 08/19/82 Decreasing <br />Sodium 120.73 18.8574 124.1 142 17.9 3/11/08 04/27/98 Increasing <br />Elevation 6897.77 3.2676 14.53 6902.53 6888 05/01/85 07/31/00 Level <br />Page 2-5