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during periods of runoff less than the 10-year, 24-hour event. However, <br />this sample was collected during a snowmelt runoff event that was <br />greater than the 10-year, 24-hour event, and therefore, an alternate of <br />the STS limit ("report") is allowed for in Seneca's discharge permit. <br />2 and 3. A sample collected by Seneca on April 29 had a total iron <br />concentration of 3280 ug/l and a total recoverable iron concentration of <br />3520 ug/1. The effluent limits are 3000 ug/l and 1.000 ug/l (monthly <br />average), respectively, during periods of no precipitation or snowmelt. <br />However, this sample was collected during a snowmelt' runoff event and <br />therefore, an alternate of the iron limits ("report") is allowed for in <br />Seneca's discharge permit. <br />Surface Water Summary <br />The Yoast Mine PHC (PAP Tab 17, Attachment 17-5) predicts TDS increases <br />to be observed at various stream sites during the irrigation season <br />(June-September). The following table outlines those predictions along <br />with this year's observed averages. <br />Stream Site Predicted TDS values (mg/1) This years average TDS (mg/1) <br />YSGF5 1337 805 <br />NPDES10 3938 2160 <br />NPDESI2 4291 3378 <br />WSSF3 (Seneca II-W site) 2118 665 <br />No sites exceeded the PHC predictions. <br />TDS trends are increasing at NPDESII, NPDESI3, NPDESI4 and one <br />downstream stream site (YSS2) and Spoil Spring 1. TDS values have <br />decreased at two downstream stream sites (YSG5 and YSGF5), and have <br />stabilized at NPDESIO and NPDESI2. Average flow values this year were <br />above historic averages at all NPDES ponds. <br />Water discharged from the Yoast Mine is not used directly for <br />irrigation. Indirectly, although, water discharged from the mine is <br />14