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Colowyo Coal Company <br />201OAnnual Reclamation and Hydrology Report <br />4) MT-95-02 Well: <br />Parameter Mean S <br />dev <br />td <br /> <br />Range <br /> <br />Max. <br /> <br />Min. <br /> <br />Max at <br /> <br />Min at <br /> <br />Trend <br />Lab pH 7.77 0.18 0.6 8.0 7.4 8/19/09 11/10/08 Static <br />Lab Cond. 2639.17 218.9 210 2860 2650 6/03/09 11/02/09 Decreasing <br />TDS 2222.50 78.99 290 2330 2040 3/17/09 11/02/09 Decreasing <br />Sulfate 917 45.29 137 968 831 8/19/09 11/10/08 Increasing <br />Calcium 217 11.35 30 231 201 3/17/09 6/18/08 Decreasing <br />Iron 0.05 0.004 0.01 0.06 0.05 11/10/08 11/2/09 Decreasing <br />Magnesium 203.92 9.86 27 219 192 3/17/09 11/2/09 Increasing <br />Sodium 145.33 17.73 69 163 94 6/03/09 8/13/08 Increasing <br />Elevation 6436.18 1.75 3.08 6437.76 6434.68 11/2/09 8/19/09 Increasing <br />TDS and conductivity are expected to temporarily increase over time as a result of an <br />increased potential for transport of salts and minerals due to the mining process. In <br />time, these slight increases should stabilize. Due to the benign chemical <br />characteristics of the overburden, relatively low permeability, and the nature of the <br />strata to restrict water movement, any potential impacts to groundwater quality will <br />continue to be extremely limited and insignificant to the current land uses in the area. <br />• SPOIL SPRING DEVELOPMENT <br />A limited number of low impact spoil springs are expected to develop occasionally, <br />however their aerial extent and low level or non-existent surface flow will have a <br />very minor impact (if any) on surface (and shallow groundwater/perched aquifer) <br />water quality and quantity in the future. In specific instances such as the Streeter <br />Fill, pre existing springs are likely the major source for the nearly continual low level <br />discharge for the Streeter Pond. Adjacent Gulch A pond may receive very minimal <br />flow from the occasional developing spoil springs should surface flow make it to the <br />pond location. Impacts to water quality and quantity at the Gulch A pond are non- <br />existent as this pond tends to become dry after spring runoff events and it is primarily <br />influenced by runoff events. Additionally, many years of NPDES discharge <br />monitoring at both locations does not support the notion that water quality is being <br />negatively affected by water that is or has managed to migrate through the <br />reclamation areas and associated spoil. <br />• <br />Page 2-8