2010-03-22_REPORT - C1994082 (2)

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. - NPDESI0. This sediment pond on Annand Draw was completed in August 1996. Flow was observed at this site for the first time ever on February 24, 1997. Flow at this pond is normally continuous. Average flow this year was 0.1058 cfs, which is 33% below its historic (1997-2009) average, 0.1588 cfs. The timing of when flow values are collected affects these averages. This pond was dredged out. in 2002. Baseline data for this site, both downstream (Site YSA4) and upstream (Site YSAF4) of the pond, have been provided in Appendix D1. NPDES10 exhibits a recently stable TDS trend (SF=0.5), peaking in 2002. - NPDESII. This pond exists on a Grassy Creek tributary and was completed in October 1997. Flow was first observed at this site in 1998. No discharge occurred in 1999 or 2000. This year, this pond started flowing in April and stopped flowing in June. This year's average flow, 0.0394 cfs, is 53% above its historic (1998-2009) average, 0.0257 cfs. The timing of when flow values are collected affects these averages. Due to high sediment level, this pond was dredged out in the fall of 2003. TDS values exhibit an increasing trend. - Site YSGFS. This site exists on Grassy Creek below the NPDESII pond. A statistical summary of baseline chemistry data is provided in Appendix D1. Its TDS plot indicates a recently decreasing trend (SF = 0.5), with the peak value occurring in 2002. - Site YSGS. This site exists on Grassy Creek below all discharges from both the Yoast and Seneca II Mines. It became part of the required monitoring program in October 1995. TDS values here are affected more by the Seneca II Mine than the Yoast Mine. TDS values exhibit a decreasing trend (SF = 0.5). Springs - Spoil Spring 1 (YSSPGI). This spoil spring was discovered in September 2002. It is located just above the old haul road culvert crossing Annand Draw. Its TDS plot displays a'decreasing trend. 11