2013-03-06_REPORT - C1982057 - Laserfiche WebLink

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is to "Report" only. This outfall has a NPDES Compliance Schedule to meet the selenium limit by December 31, 2015. SCC is currently investigating means of selenium control and treatment methods. SCC is also performing an aquatic life survey in this drainage (2012 and 2013), an extensive water quality monitoring program (2013), and is also investigating the possibility of a site - specific standard. Surface Water Summary. Flow values from all NPDES ponds were below average this year due to low snowpack runoff and rainfall. One NPDES site experienced a record low annual average flow; two NPDES sites had the second lowest annual average .flows on record, while one NPDES site did not flow at all. TDS values at all NPDES Ponds (except 015 and 016) are increasing, as are TDS values at downstream surface water Sites WSHF1, WSD5, WSSF3 and all Spoil Springs. The TDS trend is decreasing at NPDES Ponds 015 and 016. The TDS trend is stable at upstream site WSH9. NPDES discharges are normally suitable for livestock and irrigation, but sometimes exceed water quality standards for aquatic life. In the Probable Hydrological Consequences (PHC, Tab 17, Table 17 -42b) section of the Seneca II -W Mine PAP, predictions were made as to the expected TDS increases to be observed at various surface water sites. The following table outlines these predictions along with this year's observed average values (irrigation season, June - September). Site Predicted TDS values (mg /1) WSHF1 2527 WSD5 2451 WSSF3 676 * indicates value above prediction This year's average TDS (m /1) 2$70* 2000 (no flow September) (no flow July and September) One surface water site had TDS values below the PHC predictions. Only one site, WSHF1 on Hubberson Gulch, exceeded PHC predictions. This high TDS value is most likely due to drought conditions. 22