2014-02-05_REPORT - C1982057 - Laserfiche WebLink

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Alluvium, DCAL -02, did not exceed the TDS GWPOC standard, 3195 mg /1, but did exceed the ambient -based iron standard. In the Probable Hydrological Consequences (PHC, Tab 17) section of the Seneca II -W Mine PAP, predictions were made as to the expected TDS increases to be observed at various monitoring wells. The following table outlines these predictions along with this year's observed average values (annual average for bedrock wells, May - September average for alluvial wells) . 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) 900 3220 6340* 1670 5020* 650 2840 For Well Wadge Overburden WOV17, a value of 4295 mg /l was predicted, while a value of 6340 mg /1 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 WOV17 also exhibited a high degree of baseline TDS variability (min. = 6860, max. = 8586 mg /1). The TDS value in this year, 6340 mg /1, was below the PHC prediction using the average baseline value (8043 + 5.5% = 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, and 2013 dropped back down to 7