2011-03-24_REPORT - C1981019 (8)

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Colowyo Coal Company 2010 Annual Reclamation and Hydrology Report • MT-95-02 Well - located just south of the rail loop facility and represented on the Surface & Ground Water Sampling Sites Map located in Exhibit 2C. Monitoring started in the first quarter of 2008 and has continued through 2010. GENERAL TRENDS Colowyo currently samples each surface water site for a variety of quality parameters. Of all the parameters that are analyzed for, several key indicator parameters are identified. These are lab pH, lab conductivity, TDS, sulfate, calcium, iron, magnesium, sodium and flow rate. Statistical analysis is completed and illustrates historical trends for each parameter. See graphs for the trend lines in Exhibit 2A. Surface Water Data - The RZ value for linear regression is indicated below. Site Id Lab pH Lab Conductivity TDS Sulfate Calcium Iron Magnesium Sodium Flow rate (cfi) NUGSC 0.0514 0.0005 0.0136 0.0006 0.0096 0.0044 0.0029 0.0682 0.0067 LGSC 0.0704 0.0601 0.0989 0.0165 0.00005 0.0121 0.00001 0.0888 0.041 UWFGSC 0.2028 0.0698 0.0959 0.1135 0.1114 0.0327 0.0639 0.0606 0.0049 -LTC 0.0191 0.0972 0.0489 0.0006 0.0147 0.0001 0.0011 0.0436 0.1314 IV Summary of the indicator parameters for each surface water site is provided in the following tables. NUGSQ Parameter Mean Sted Range Max. Min. Max at Min at Trend Lab pH 8.13 0.24 1.1 8.6 7.5 04/27/98 10/24/02 Increasing Lab Cond. 1503.61 279.53 2842 3600 758 03/06/98 05/27/93 Increasing TDS 1140.59 244.79 1250 1610 360 08/06/01 05/08/02 Increasing Sulfate 509.55 145.43 760 930 170 07/08/02 05/20/97 Increasing Calcium 126.69 19.70 165.6 169 3.4 08/02/02 06/01/93 Increasing Iron 0.78 1.63 8.53 8.54 0.01 05/17/99 02/11/02 Decreasing Magnesium 123.15 29.76 226.9 228 1.1 08/02/02 04/27/98 Increasing Sodium 47.67 16.41 121.1 138 16.9 11/10/08 04/27/98 Increasing Flow rate 2.97 3.21 19.8 20 0.2 04/27/98 03/18/96 Increasing Page 2-3