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Section 7.2 Seneca II-W South Hydrologic Description <br />Ground Water Levels • <br />Introduction. Table 15-2 (Tab 15, Hydrologic Monitoring Plan) provides a summary of all <br />ground water monitoring sites at Seneca 11-W. Appendix 7-1 provides well completion <br />summaries for these wells where the most recant data is presented in Appendix 2A. Appendix <br />7-2 provides ground water level reports, hyclrographs, and statistical summaries for these <br />wells. Finally, Exhibits 7-2A and :r_3A have been prepared to show the potentiometric surfaces <br />for the Wedge overburden and coal in the II-W :iouth area. <br />Alluvium. Six monitor wells IG\N-52W-6A1 [0 4, 7A1, and 7A21 exist in the Hubberson <br />Gulch(Sage Creek downgredient of the II-W South area. Review of their hydrographs indicate <br />seasonal trends typical to .this region, i.e., shallow after the spring recharge, deepening <br />towards the fall. Since May 1989, wells 6A1 to 6A3 have experienced higher than normal <br />water levels during May through .luly due to irrigation of the hay meadow where these wells <br />are located. <br />Wadge Overburden. Two monitor wells IGW-S2W-40V1 and 40V2) exist in the II-W South <br />area. In addition, well GW-S2W-18OV exist just to the north of the II-W South area. Wells <br />40V1 and 40V2 exhibit the same typical seasonal variation as described for the alluvium. Well <br />180V has generally experienced increasing water levels since 1995. <br />Wedge Coal. One monitor well IGW-S2W-4W) exists in the II-W South area. Seasonal <br />variability here is much smaller than year to year variations. Well GW-S2W-18W exists <br />adjacent to wall 180V (see previous paregraphl. Seasonal variability of water levels is small <br />compared to the generally increasing levels noted as this well. <br />Wolf Creek Coal. One monitor well IGW-S2W•4WC1 exists in the II-W South area. Water <br />levels are generally over a hundred feet deeper than the adjacent Wadge Coal well, indicating <br />no hydraulic communication between the two units. <br />Ground Water Quality <br />Introduction. Aground water quality database of historical ground water quality may be found <br />in Appendix 7-4A. Data provided for each well in this appendix beings with a total dissolved <br />solids (TDSI vs. Time plot. The retlressions line on this plot is generated by a method known <br />as LOWESS (Locally Weighted Scatr,er Plot Smoothing). A smoothness factor of 1 lon a scale <br />of 0 to 11 was used, which gives maximum smoothing. The TDS plot is followed by a table <br /> <br />146 <br />