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Watlge overburden well (WOV15) had a baseline 1DH average of 3741 mg/1. Well WOV17 also <br />• exhabr ted a high degree of baseline TOS variability (min. = 6860, max. = 8586 mq/1). <br />While both the 1988 (8860 mg/1) and 1999 (8935 mg/1) values exceeded the PHC prediction <br />using the average baseline value (8043 + 5.58 = 8485 mg/1), both values are below a 5.58 <br />increase of the maximum baseline TDS value (8586 + 5.58 = 9058 mg/1). Also, as explained <br />previously in the alluvium section, calculated TDS values aza often preferable to measured <br />TOS values. The calculated TDS average values xexe 8610 mg/1 in 1998 and 8150 mq/1 in <br />1999. Hone data will be needed to evaluate the long-term TDS trend. <br />- Wedge Coal. Four wells monitor the Watlge coal seam. Well WW14 exhibiis a recently <br />increasing TDS trend. Well Wi116 displays an incraae ing TD9 trend. Well WW77 exh ibite a <br />nearly level TDS trend. Well WW4 exists in the II-W South Expansion area. Mona torinq at <br />this yell vas resumed in July 1997 after being discontinued in June 1985. This well, so <br />far, has not been impacted by mining. <br />The Seneca II-W PHC predic is an annual average TDS value of 2630 mg/1 for Well WW14, rhile <br />a value of 4250 mg/1 was observed this year. For Well WW17, a value of 3002 mg/1 was <br />predicted, xhile a value of 740 mg/1 was observed this yeas. <br />• <br /> As noted in the previous paragraph, Well WW14 experienced this yeaz a TDS exceedence of <br /> the PHC prediction. This prediction was based on several assumptions. 1) Baseline water <br /> quality va luea were an average of all Wedge coal rella at 9enaea II-W. 2) Aquifer <br /> charac to riatica were an average of all Wedge coal walla at Sanaca II-W. 3) The Wedge coal <br /> seam was saturated £or its entire thi ekneae (11 .8 fao t). <br />These assumptions, however, do not hold true for Well WW14. Prior to mining in the north <br />area (November 1992), this well xas almost alxaye dry (see the 1993 AHR for a complete <br />listing of earlier water level data). Since this particular portion of the Wadqe seam xas <br />dry prior to mining, spoils water rill nor contribute 1008 of the rater present. The <br />Seneca II-W PHC uses a TDS value of 4500 mg/1 for its spoil water calculations, therefore <br />Well WW14 is nor expected to achieve a similar TDS value. <br />- Wolf Creek Coal. One rell monitors this coal seam. Well WWC4 exists in the II-W South <br />Expansion area. Monitoring at this roll was resumed in July 1997 after being discontinued <br />in June 1985. This rell, so faz, has oat been impacted by mining. <br />u <br /> <br />