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present at YSGF5 during this event(0.7 gpm) and the elevated TSS is likely from the <br /> disturbance of sediment at the base of the channel during sample collection. If this sample is <br /> excluded all remaining post mining TSS results fall within the pre-mine range. <br /> Analytical results for the mines five NPDES outfalls for 2014—2018 are provided in Tables 6— <br /> 10. TSS was removed as a monitoring requirement from the outfalls when their drainage status <br /> was changed to reclamation. Outfalls 010 and 011 were reclassified as reclamation in November <br /> 2006 and Outfalls 012, 013, and 014 were reclassified to reclamation in July 2010. Between <br /> 2014 and 2018 only 13 TSS samples were collected from the outfalls (010: 4; 011: 1; 013: 8) and <br /> the TSS ranged from <0.5 - 12 mg/L.None of these samples exhibited TSS above the pre-mine <br /> maximums measured in Grassy Creek and Sage Creek(Table 5). Table I I includes a summary <br /> of the five outfalls TSS analytical data during the five years prior to the reclamation drainage <br /> status change. <br /> The TSS at Outfall 010 during this time period ranged from <5 —46 mg/L (mean: 8.9 mg/L) and <br /> is less than the pre-mine concentrations observed at Grassy Creek point YSGF5 (range: 33.8 — <br /> 296 mg/L; mean: 33.8 mg/L). The TSS at Outfall 011 during this time period ranged from <5 — <br /> 38 mg/L (mean: 13.8 mg/L) and is less than the pre-mine concentrations observed at Grassy <br /> Creek point YSGF5 (range: 33.8 —296 mg/L; mean: 33.8 mg/L). The TSS measured at the three <br /> outfalls that discharge to Sage Creek during the five years prior to being classified as reclamation <br /> drainage ranged from <5 —25 (mean: 8.6) at Outfall 012, <5 —26 mg/L (mean: 8.5 mg/L) at <br /> Outfall 013, and<5 — 170 mg/L (mean: 26.8 mg/L) at Outfall 014. The average TSS <br /> concentration at Outfalls 012 and 013 are below the pre-mine average measured at downstream <br /> point YSS2 (23.6 mg/L) and the average TSS concentration at Outfall 014 only exceeds the pre- <br /> mine average at downstream point YSS2 by a few milligrams per liter. The average at Outfall <br /> 014 is strongly influenced by a single sample with elevated TSS (170 mg/L) and its important to <br /> note that TSS concentrations in the 13 other samples collected during this time period did not <br /> exceeded 42 mg/L. A statistical comparison of pre-mine stream points and post mine NPDES <br /> TSS concentrations is provided in Attachment 1. The analysis indicates there is no statistically <br /> significant difference (95% Confidence Level) between the TSS concentrations measured at the <br /> Yoast NPDES outfalls and the pre-mine stream concentrations. This further indicates that the <br /> reclaimed parcels reporting to these ponds are adequately stable. <br /> SL-7 - 33 <br />