2015-03-31_REPORT - C1982057 - Laserfiche WebLink

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Well Predicted TDS values (mg /1) WHAL7 -2 1299 WOV14 4385 WOV17 4295 WOV25 none WW14 2630 WW17 3002 WW25 none * indicates value above prediction This year's average TDS (mg /1) 1070 4045 5945* 2280 4945* 645 2660 For Well Wadge Overburden WOV17, a value of 4295 mg /l was predicted, while a value of 5945 mg /l was observed in this year. The predicted value for Well WOV17 was predicated on a 5.5% increase of the pre- mining (prior to August 1990 for the central area) value of 4072 mg /1, which is an average of several overburden wells. However, Well WOV17 exhibited a pre- mining TDS average value of 8043 mg /1, while the next highest TDS Wadge overburden well (WOV15) had a baseline TDS average of 3741 mg /1. Well WCV17 also exhibited a high degree of baseline TDS variability (min. = 6860, max. = 8586 mg /1). The TDS value in this year, 5945 mg /1, was below the PHC prediction using the average baseline value (8043 + 5.516 = 8485 mg /1) , and is also below a 5.5% increase of the maximum baseline TDS value (8586 + 5.5% = 9058 mg /1) . In 2008, 2009 and 2011, unusually high TDS values (over 10,000 mg /1) were observed at this well. These values were over the pre- mining average, 8043 mg /1, for this well. The TDS value for this well in 2010, 2012, 2013, and 2014 dropped back down to a value within the 1988 -2007 range (3766 to 9580 mg /1) . The overall TDS trend for this well is decreasing. The Seneca II -W PHC predicts an annual average TDS value of 2630 mg /l for Wadge Coal Well WW14, while a value of 4954 mg /l was observed this year. However, for Wadge Coal Well WW17, a value of 3002 mg /l was predicted, while a value of 645 mg /l was observed this year. As noted in the previous paragraph, Well WW14 experienced this year a TDS exceedance of the PHC prediction. This prediction was based on several assumptions. 1) Baseline water quality values were an average of 7