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• Water level monitoring results through year 1992 provided in Figures 18 through 20, in Section 2.04-7, Hydrology <br />Information, show no change in the piezometric levels in the Twenrymile Sandstone that could be attributable to <br />mining activities. The only trend indicated in these plots is, perhaps, a slight increase in the levels in Well 84-01. <br />Since both the potentiometric gradients and the influence of gravity is from the Twenrymile Sandstone toward the <br />target coal seam, no change in water quality would be expected as a result of longwall mining operations at the RAG <br />Empire #5 and #6 Mines. <br />The water quality data for the two Twenrymile Sandstone wells, No. 9 Mine Well and Well 259 show no adverse <br />impact or trend. Plots of field conductivity over time are presented in Figure 58c, and Exhibit 42, Figures 58P and <br />58Q for wells 259 and No. 9 MN, respectively. Likewise, plots of dissolved iron are presented in Figures 58R and <br />58S and plots of pH are provided in Figures 58T and 58U for these wells. The only apparent trend in the plots is an <br />apparent reduction in dissolved iron in well 259. This may be the result of improvements in sampling procedures or it <br />could simply be an artifact of large variability in the dissolved iron measurements as has been observed in other wells. <br />Ground water levels in the alluvium have remained fairly regular, with normal seasonal fluctuations, apparently <br />related to changes in river levels. Ground water levels in the alluvium are plotted in Figure 22, in Section 2.04.7, <br />Hydrology Information. The data indicates no impact on alluvial water levels related to mining. <br />Plot of field conductivity versus time for the three alluvial wells, AVF-3, AVF-5 and AYF-6, are presented in Figures <br />58V, 58W and 58X, respectively. Likewise, plots of dissolved iron are presented in Figures 58Y, 58Z and 58AA and <br />plot of pH is provided in Figures 58AB, 58AC and 58AD for these wells. One trend apparent in the plots is an <br />increase in the conductivity levels in well AVF-3. Review of water chemistry data indicates that this increase in <br />conductivity is primarily due to increases in the concentrations of calcium, chloride and sulfate. The source of this <br />increase in major ions in well AVF-3 is not known. However, it is unlikely due to mine discharge because tts location <br />and the dissimilar chemical composition of mine discharge. <br /> <br /> <br />MidTerm Response 2.05-42 ~~,~~ Revised 12/05/01 <br />