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NPDESI2. <br />Mining in this basin began in 2000. Reconstruction of the water <br />augmentation Pond Y1 (Site YSSF2) was completed on September 13, 1999. It <br />is now referred to as Pond 012 (NPDESI2). This pond began to flow again <br />(after reconstruction) in April 2000. Flow at this pond is continuous. <br />The average flow value for this year was 0.12 cfs, and the historic (2000- <br />2017) average for Pond 012 is 0.10 cfs. The timing of when flow values <br />are collected affects these averages. A statistical summary of baseline <br />chemistry data from Site YSSF2 (Yl outflow) and YSS3 (Yl inflow) is <br />provided in Appendix Dl of the 2010 AHR. NPDESI2 exhibits a decreasing <br />TDS trend, with the peak value occurring in July 2007. <br />A slide north of Pond 012 was repaired in 2010 and 2011. An additional <br />pond, 012A, was constructed in August 2008 to compensate for the lost <br />capacity in Pond 012. Pond 012 was cleaned out in 2010 and 2012. <br />NPDESI3. <br />Construction of this pond was completed in December 2003. It first began <br />discharging on March 14, 2005. Average flow this year was 0.00 cfs and <br />the historic (2005-2017) average value is 0.01 cfs. The timing of when <br />flow values are collected affects these averages. The TDS trend is <br />increasing. <br />NPDESI4. <br />Construction of this pond was completed in September 2001. It discharged <br />for the first time on April 4, 2006. The average flow this year was 0.00 <br />cfs and the historic (2006-2017) average value is 0.02 cfs. The timing of <br />when flow values are collected affects these averages. TDS values are <br />increasing with the peak occurring this year. <br />Site YSS2. <br />This site exists on Sage Creek below all potential Yoast Mine discharges. <br />Monitoring at this site was resumed in 1998 after the monitoring <br />requirement was discontinued in 1993 (although field parameters were <br />occasionally collected in 1994 to 1997). Its TDS plot indicates a slightly <br />increasing trend, with the peak value occurring in September 2006. <br />10 <br />