2021-03-02_REVISION - M1990057 (5)

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The Meadville Mill M 1990-057 EXHIBIT C-MILL PLAN Page 4-19 Table DAF 30 appFeNimately 2.31b/day will be added as a fleeeulent (same Feagent as used the coneentFate thiekeneF). T cBEE4-4: CHEMIGAL USAGE, ThILINGs THIGKENER Reagents OAF-30 Rate A-998�.� . /..- TOTTTCCCI TTVJO�CryT flewnt Used Q944Y 1 Reagent Fate based en dFy tailings feed tennage !1 2:Fens of. 4.3 TAILINGS STORAGE FACILITY (TSF) (6 .3 .3(2)(b)) Note: TSF earthworks were completed in 2014. The remaining TSF construction will be completed in Spring 2021. The current mill configuration, process and operations have been modified to treat an ore different than was processed during the last operational period, as described in Section 4.2. This necessitates rephrasing the initial TSF plan to provide tailings disposal capacity for a more efficient concentrating system and increased tails reporting to the TSF. The historical TSF embankment compaction was inadequate for current production requiring complete removal of the existing embankment and reconstruction of the TSF facility with a lined facility. The reconstruction honors the original permit parameters as follows: • The same 4.6ac TSF is utilized. • The pond excavation at a maximum 21ft depth does not impact the known aquifers at 80-100ft below the surface. • The TSF embankment will be constructed from available onsite soils borrowed from the tailings disposal area as outlined in the recommendation of CTL Thompson, Inc., Permeability Study, April 10, 1990, presented as Appendix 15- 2, and Slope Stability Evaluation,July 8, 2011, presented as Appendix 15-5. • The TSF will be constructed as a zero-discharge facility with 3ft of freeboard in accordance with the Probable Maximum Precipitation Estimates - United States between the Continental Divide and the 103rd Meridian.