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Privileged and Confidential—Attorney Client Communication G e o syntec <br /> consultants <br /> • The mine is remote(making the operation and maintenance of an active water <br /> treatment system difficult), <br /> • There is infrastructure in place at the mine site to construct a passive system, <br /> • Prior piloting conducted by OSMI indicated biological treatment is a viable <br /> approach for metals reduction, which are already low(generally below drinking <br /> water standards), <br /> • Numerous case studies have demonstrated that it is generally a viable <br /> technology for mine water if sufficient hydraulic retention time is provided <br /> (Ness, Janin, & Stewart, 2014), and <br /> • It will visually blend in with the high alpine environment, further supporting <br /> recreational use of the surrounding area. <br /> Table 1 lists site-specific design considerations for the Treatment System based on mine <br /> site conditions. <br /> Table 1: Mine Site Conditions for Design Considerations <br /> Design Consideration <br /> • Seasonal changes in pumped water flows from the portal <br /> • Design low flow: 100 gallons per minute(gpm)—October <br /> Water Flow Rate* through April(historical low on record was 111 gpm in <br /> December 2015) <br /> • Design high flow: 1,215 gpm** -May through September <br /> • Permit 30-Day Average: 1.75 MGD(1,215 gpm) <br /> • High monthly average temperature: July, 78°F <br /> Climate and • Low monthly average temperature: January, 15°F <br /> Temperature • Highest recorded temperature: June,96°F <br /> Fluctuations*** • Lowest recorded temperature: January,-22°F <br /> • Average number of days below 32°F: 182 <br /> • Ranged from 6.3 °C to 11.8°C over the span of the pilot <br /> Water Temperature system testing(March-September) <br /> • Average water temperature during pilot testing: 8.4 °C <br /> Precipitation** • 40"/year <br /> Evaporation** • 35"/year <br /> Elevation • Mine elevation is 10,600' <br /> rcatat ilitc I csting Repot 2 December 11,2018 <br />