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determined by adding up all the concentrations for all of the various • <br />dissolved constituents. For May-September 2004, the calculated TDS <br />average value is 1560 mg/l. Drought conditions probably have contributed <br />to the elevated TDS values. <br />- Wadge Overburden. Three wells monitor the Wadge overburden. Well <br />WOV14 exhibits an increasing TDS trend. Well WOV16 displays an <br />increasing TDS trend. Prior to October 1994, there was not enough water <br />to sample in this well. Therefore, all samples represent postmining <br />conditions (mining began in this area in 1990) . Well WOV17 exhibits a <br />stable TDS trend, with TDS values decreasing since 1998. Well WOV4-1 <br />(II-W South Expansion area) was sampled for the first time ever in May <br />1999. This well has been dry since then. Due to safety concerns because <br />of its proximity to the highwall, this well was abandoned in August <br />2003. A replacement Wadge overburden well was drilled in September 2004, <br />The Seneca II-W PHC predicts annual average TDS values at various Wadge <br />overburden wells. For Well WOV14, a value of 4385 mg/1 was predicted, <br />while a value of 4090 mg/1 was observed this year. For We11 WOV17, a <br />value of 4295 mg/1 was predicted, while a value of 7890 mg/1 was <br />observed this year. <br />The predicted value for Well WOV17, 4295 mg/1, was predicated on a 5.5$ <br />increase of the premining value of 4072 mg/l, which is an average of <br />several overburden wells. However, Well WOV17 exhibited a premining TDS <br />average value of 8043 mg/1, while the next highest TDS Wadge overburden <br />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, 7890 mg/1, was below the <br />PHC prediction using the average baseline value (8043 + 5.58 = 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 values are often preferable to measured <br />TDS values. The calculated TDS average value this year was 7340 mg/1. <br />More data will be needed to evaluate the long-term TDS trend, however ~ . <br />the peak TDS value occurred in 1998. <br />8 <br />