2010-03-22_REPORT - C1994082 (2)

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flow value, 0.1293 cfs. The timing of when flow values are collected affects these averages. A statistical summary of baseline chemistry data from Site YSSF2 (Yl outflow) and YSS3 (Y1 inflow) is provided in Appendix Dl. NPDESI2 exhibits a recently decreasing TDS trend (SF=0.5), with the peak value occurring in July 2007. A slide north of Pond 012 remains active this year, most likely a result of a high snowpack runoff. An additional pond, 012A, was constructed in August 2008 to compensate for the lost capacity in Pond 012. - NPDESI3. Construction of this pond was completed in December 2003. It first began discharging on March 14, 2005. This year, this pond started flowing in March and stopped flowing in May. Average flow this year was 0.0077 cfs, which was 270 less than the historic (2005-2009) average value, 0.0105 cfs. The timing of when flow values are collected affects these averages. The TDS trend is increasing. - NPDESI4. Construction of this pond was completed in September 2001. It discharged for the first time on April 4, 2006. This year, this pond started flowing in March and stopped flowing in June. The average flow this year was 0.0139 cfs, which was 30% less than the historic (2006- 2009) average value, 0.0200 cfs. The timing of when flow values are collected affects these averages. TDS values are increasing, but the peak value (June 2008) was only 720 mg/l. - Site YSS2. This site exists on Sage Creek below all potential Yoast Mine discharges. Monitoring at this site was resumed in 1998 after the monitoring requirement was discontinued in 1993 (although field parameters were occasionally collected in 1994 to 1997). A statistical summary of baseline chemistry data is provided in Appendix D1. Its TDS plot indicates a recently decreasing trend, with the peak value occurring in September 2006. Grassy Creek / Annand Draw • '10