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overburden (see Exhibit 7-1). Table 7-14 summarizes pertinent comments about rater types depicted on trilinear diagrams end table listings of percent milliequivalents presented in Appendix 7-4. Well YLOV4 was sampled only once during the baseline period for the full ground water quality suite, and featured a MpCaNa504HC03 Water type. The one TDS measurement et YLOV4 was 2030 mg/l. Yell YLOV3 Was sampled several times during baseline, end consistently showed a Ng504 Water type. TDS at Yell YLOV3 ranged much higher than YLOV4, from 3460 up to 6432 mg/l. During the baseline period, TDS at YLOV3 generally Was highest during the spring, often lover(n9 significantly as fall progressed. Sulfate at Yell YLOV3 ranged from 1790 to 4157 mg/l, end followed the same seasonal pattern as iDS. Field pH measured at both reps was virtually constant, varying only by one-tenth from 6.8 to 6.9 S.U. Hardness es CeC03 ranged from 3480 to 6290 mg/l in Yell YLOV3, and was measured once in Yell YLOV4 at a much lower toneentration of 1400 mg/l; regerdLes s, Lennox overburden water is et least one order of magnitude higher in hardness compared to any alluvial ground water measured in the vicinity of the Yoast Mine. Detectable concentrations of several trace elements were measured in the Lennox overburden including Ba, B, F, Fe, Ni, Si, end 2n. Of these, only silica was measured at e concentration Greater then 1.0 mg/L (14.0 mg/l, YLOV4). Ni is included in this 1 mg/l comparison because there is a proposed Livestock standard of 1000 ug/L and this geologic unit does not yield sufficient water for irrigation purposes. Yedge Overburden. Yells YOV1, YOV25, YOV28, YOV30, and YOV4 all monitor water quality in the Yadge overburden (see Exhibit 7-1). Table 7-15 presents summary information regarding water types depicted on trilinear diagrams and table listings of percent milliequivalents presented in Appendix 7-<. Table 7-15 indicates the Wadge overburden features variable water quality. Yells YOV25 end YOV28, located in the northeastern portion of the Toast Mine and within one-quarter mile of each other (see Exhibit 7-1), have both yielded a CeNgHC03 rater type. YOV25 consistently exhibits this type with no seasonal variability. Yell TOV2B predominantly features a CeNgHC03SO4 water type during the summer and fall, end a CeM gHC03 water type during the spring. Occasionally, Mg replaces Ce et YOV2B during the fall. Yells YOV1, YOV9, end YOV30 ere located just dorngradient of the cadge coal cropline on the western portion of the Yoest Mine (see Exhibit 7.1). YeIL YOV1 exhibits a NgCa504HC03 predominant rater type with little seasonality (occasionally HC03 replaces 504 during the 46 • •