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quality in the Yadge coal seam. Table 7-16 presents summary information regarding water • <br />types depicted on trilineer diagrams and listed in percent milliequivalent tables found in <br />Appendix 7.4. <br />Table 7-16 shows that Yell TY7 exhibits several anomalous water types in comparison with <br />the other six Yadge coal wells. In Yell YL7, calcium consistently dominates cations and <br />carbonate is the predominant anion, resulting in a CaC03 water type. The trilineer <br />diagram constructed for Vell YY7 (Appendix 7.4) shows significant anion scatter and at <br />least one occurrence of three additional different water types: CeC03Cl, CeC03C1504, and <br />CeC iSO4C03. Field pH values have ranged above 12 S.U. for full suite water quality <br />samples collected et this well. These water types end high pH values observed et YY7 <br />indicate cement grout used during well construction may have inadvertently mixed with the <br />gravel pack around the well screen (see Tab 15, Hydrologic Monitoring Program). Because <br />of the anomalous chemical nature of water analyzed at Yell YY7, all chemical data <br />collected at chic well is considered unrepresentative of the Yadge Coal, and will not be <br />included in the following discussion. <br />Similar to the Yadge overburden, the Yadge coal seam also exhibits variable water quality. • <br />Generally, bicarbonate is the dominant anion while no cation dominates, although calcium <br />or magnesium commonly yield the greatest influence. Wells YY18, YY23, and YY29 ell are <br />loteted in the middle portion of 'the Yoast mining area (see Exhibit 7.1). Yell YY18 <br />typically shows a MgCeHC03 water type, occasionally shifting to a CeM gxC03 type. Yell <br />YY23 consistently shows a CaXgxC03 tYPe and virtually no seasonal variability. In <br />contrast, Yell YY29 consistently exhibits a NeNC03 water type without seasonal variations, <br />end is the only Yadge coal well that features sodium es the dominant cation. Yell YY28 is <br />loteted in the no rt heestern portion of the Yoest area, and typically features a <br />CaMgNC03504 water type, and similar to previously discussed Wedge coal wells, no <br />appreciable seasonality in type. Wells YY2 and YY30 both commonly exhibit a MgCeYaHC03 <br />water type. Seasonal variability at both wells is minimal, evidenced by slight changes in <br />cation percentages only. <br />ToteL dissolved solids in the Yadge coal ranges from 234 to 1232 mg/l. TDS et Yells YY2, <br />YY23, end YY30 has not exceeded 900 mg/l, end the range of TDS veriabi lity at ell three <br />wells is less than 220 mg/l. TDS at YY18 has not exceeded 600 mg/l, but has varied just <br />more than 320 mg/l. Both YY28 and YY29 have shown TDS concentrations above 1000 mg/l • <br />(1232 end 1082, respectively), and TDS at both wells has varied more than 400 mg/l. <br />Seasonal variability of TDg in the Yadge coal seam is Benerelly low, typified by lower <br />50 Revised 03/07/95 <br />