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- NPDESI4. Construction of this pond was completed in September 2001. <br />It discharged for the first time on April 4, 2006. The average flow for <br />the year was 0.020 cfs. The average TDS for the year was 190 mg/1. <br />- Site YSS2. This site exists on Sage Creek below all potential Yoast <br />Mine discharges. Monitoring at this site was resumed in 1996 after the <br />monitoring requirement was discontinued in 1993 (although field <br />parameters were occasionally collected in 1994 to 1997). A statistical <br />summary of baseline chemistry data is provided in Appendix D1. Its TDS <br />plot indicates an increasing trend. <br />Grassy Creek / Armand Draw <br />- NPDESI0. This sediment pond on Armand Draw was completed in August <br />1996. Flow was observed at this site for the first time ever on February <br />24, 1997. Average flow this year was 0.209 cfs, which is 28~ above its <br />historic (1997-2006) average, 0.163 cfs. This pond was dredged out in <br />2002. Baseline data for this site, both downstream (Site YSA4) and <br />upstream (Site YSAF4) of the pond, have been provided in Appendix D1. <br />NPDESIO recently exhibits a stable TDS trend (SF=0.5). <br />- NPDESII. This pond exists on a Grassy Creek tributary and was <br />completed in October 1997. Flow was first observed at this site in 1998. <br />No discharge occurred in 1999 or 2000. This year's average flow, 0.042 <br />cfs, is 121 above its historic (1998-2006) average, 0.019 cfs. This <br />year, this pond started flowing April and stopped flowing in Sune. Due <br />to high sediment level, this pond was dredged out in the fall of 2003. <br />TDS values recently exhibit an increasing trend.• -~ <br />- Site YSGFS. This site exists on Grassy Creek below the NPDESII pond. <br />A statistical summary of baseline chemistry data is provided in Appendix <br />D1. Its TDS plot indicates an increasing trend. <br />- Site YSG5. This site exists on Grassy Creek below all discharges from <br />both the Yoast and Seneca II Mines. It became part of the required <br />monitoring program in October 1995. TDS values here are affected more by <br />11 <br />