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well (WOV15) had a baseline TDS average of 3741 mg/1. Well WOV17 also <br />exhibited a high degree of baseline TDS variability (min. = 6860, max. _ <br />8586 mg/1). The average TDS value this year, 8450 mg/1, was below the <br />PHC prediction using the average baseline value (8043 + 5.5~ = 8485 <br />mg/1), and is also below a 5,5~ increase of the maximum baseline TDS <br />value (8586 + 5.5~ = 9058 mg/1). Also, as explained previously in the <br />alluvium section, calculated TDS valves are often preferable to measured <br />TDS values. The calculated TDS average value this year was 7865 mg/1. <br />More data will be needed to evaluate the long-term TDS trend. <br />- Wadge Coal. Four wells monitor the Wadge coal seam. We11 WW14 <br />exhibits an increasing TDS trend. Well WW16 has not have enough water in <br />it to sample since May 1999. In past years it displayed an increasing <br />TDS trend. Well WW17 exhibits a nearly level TDS trend. Well WW4 exists <br />in the II-W South Expansion area. Monitoring at this well was resumed in <br />Scaly 1997 after being discontinued in June 1985. This well has been dry <br />since May 2002. Previous samples displayed an increasing TDS trend. <br />The Seneca II-W PHC predicts an annual. average TDS value of 2630 mg/1 <br />for Well WW14, while a value of 4820 mg/1 (4550 mg/1 calculated) was <br />observed this year. For Well WW17, a value of 3002 mg/1 was predicted, <br />while a value of 780 mg/1 was observed this year. <br />As noted in the previous paragraph, Well WW14 experienced this year a <br />TDS exceedence of the PHC prediction. This prediction was based on <br />several assumptions. 1) Baseline water quality values were an average of <br />all Wadge coal wells at Seneca II-W. 2) Aquifer characteristics were an <br />average of all Wadge coal wells at Seneca II-W. 3) The Wadge coal seam <br />was saturated for its entire thickness (11.8 feet). <br />These assumptions, however, do not hold true for Well WW14. Prior to <br />mining in the north area (November 1992), this well was almost always <br />dry (see the 1993 AHR for a complete listing of earlier water level <br />data). Since this particular portion of the Wadge seam was dry prior to <br />mining, spoils water will now contribute 100 of the water present. <br />l__J <br />• <br />I <br />8 <br />