Laserfiche WebLink
Ground Water Quality Summary. Increasing TDS trends were observed at <br />eight wells downgradient of mining. Seven downgradient wells exhibit <br />stable or decreasing TDS trends. The GWPOC well for the Dry Creek <br />Alluvium, DCAL-02, did not exceed the TDS GWPOC standard, 3195 mg/l, but <br />did exceed the ambient -based iron standard. <br />In the Probable Hydrological Consequences (PHC, Tab 17) section of the <br />Seneca II -W Mine PAP, predictions were made as to the expected TDS <br />increases to be observed at various monitoring wells. The following <br />table outlines these predictions along with this year's observed average <br />values (annual average for bedrock wells, May -September average for <br />alluvial wells). <br />Well Predicted TDS values (mg/1) <br />WHAL7-2 1299 <br />WOV14 4385 <br />WOV17 4295 <br />WOV25 none <br />WW14 2630 <br />WW17 3002 <br />WW25 none <br />* indicates value above prediction <br />This year's average TDS (mg/1) <br />1235 <br />3005 <br />5715* <br />2160 <br />4895* <br />648 <br />2345 <br />For Well Wadge Overburden WOV17, a value of 4295 mg/l was predicted, <br />while a value of 5715 mg/l was observed in this year. The predicted <br />value for Well WOV17 was predicated on a 5.5% increase of the pre -mining <br />(prior to August 1990 for the central area) value of 4072 mg/l, which is <br />an average of several overburden wells. However, Well WOV17 exhibited a <br />pre -mining TDS average value of 8043 mg/l, while the next highest TDS <br />Wadge overburden well (WOV15) had a baseline TDS average of 3741 mg/l. <br />Well WOV17 also exhibited a high degree of baseline TDS variability <br />(min. = 6860, max. = 8586 mg/1). The TDS value in this year, 5715 mg/l, <br />was below the PHC prediction using the average baseline value (8043 + <br />5.5% = 8485 mg/1), and is also below a 5.5% increase of the maximum <br />baseline TDS value (8586 + 5.5% = 9058 mg/1) . In 2008, 2009 and 2011, <br />10 <br />