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(Appendix A). This decrease of TDS values may indicate that the most readily soluble <br />constituents may have been flushed from the system. <br />Wadge Coat. Two wells are used to monitor [he water quality of this strata: 17-W and <br />19-W. Nell 77-W, situated downdip from spoils, receives recharge from the Wadge <br />Impoundment and the little Grassy Creek alluvium. It displays a Na-S04 type water. TDS <br />values have been increasing at this cell from 1985 to 1990, but has decreased sli ghtLy in <br />7991, most likely a result of water from the spoils (with high TDS values) discharging <br />into the Wadge Impoundment. Well 19-W, downdip of mining, has an anomalous eater quality <br />with a high percentage of sodium and bicarbonate. TDS values appear relatively stable. <br />Wolf Creek Overburden/Wadge Underburden- Three wells are used to monitor this strata: <br />7-WCO, SP7-U, and 11-U. Well 7-NCO, located downdip of the Wolf Creek pit, is a CaMg-504 <br />type water. Considerable range in the data makes it difficult to define a TDS trend. <br />Annual precipitation variation and variations in sampling techniques may be the cause. <br />The sampling procedure used since 1987 involves the removal of at least one casing volume <br />(CV) by pumping or baiting. Fol lowing the removal of one CV, only enough water for one <br />sample remains. TDS values have dropped from the 1987 value as stagnant well bore water <br />is removed from [his low recovery well prior to sampling. • <br />Either Well 8-U or 8P1-U have been sampled in past years, depending on the availability of <br />sampling equipment. Both cells are completed in the same strata and are only <br />approximately 50 feet apart. Wells 8-U, 8P1-U, and 71-U have a similar water quality to <br />Wadge coal Well 19-N. All exhibit a sodium bicarbonate type water with TDS values less <br />than 900 mg/l. Since [hey are all situated along the southwest boundary of the permit <br />area (see Exhibit 7-2) and are completed in adjacent strata, it is likely that they are <br />hydraulically connected and that local geochemical conditions are responsible for this <br />water type. The increase in TDS noted at Wells 8-U and 8P7-U since 1987 (see Table 8, <br />Appendix A) are probably due to the subsequent adoption of sampling procedures identical <br />to those mentioned for Well 7-WCO. <br />Trout Creek Sandstone. Well GW-SS-TC is used as the potable eater supply for the Seneca <br />II Mine facilities. It displays a Na-SO4HC03 type eater. TDS values show no discernable <br />trend. <br /> <br />8 <br />