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Sunnyside Mine Pool Mitigation <br /> Page 2 <br /> The procedure for the project is to simply pump alkaline waters, using either caustic soda or <br /> hydrated lime to supply alkalinity, into an old ventilation raise above the 2200 ore pass. The mixture <br /> will flow into the ore pass and mix with waters that flow towards the Terry Tunnel but will be <br /> diverted to the 2200 ore pass after the Terry Tunnel bulkhead valve is closed. The 2200 ore pass is <br /> connected to six different levels of the mine and is the major conduit for water to spread into the <br /> workings. See attached drawing. <br /> The schedule for pumping of alkaline waters is limited to the short summer runoff period, <br /> typically July and August, due to limited access to the 12,000 feet plus site (elevation). In an eight <br /> week period a total of 12 million plus gallons of water can be added to the pool per season. Pumping <br /> could continue until physical equilibrium is established. Annual evaluation will determine if <br /> continuation after initial year is warranted. It will take an estimated 195 million gallons to reach <br /> equilibrium. Based on water treatment experience, to raise the pH from 6.5 to 9.5 will require the <br /> addition of at least 200 tons of lime to physical equilibrium. SGC would add additional lime to <br /> counteract acidity generated by the pool consuming its supply of oxygen. <br /> Analysis <br /> Pumping of high pH waters with buffering capability will enhance the following aspects of the <br /> hydraulic seal project. <br /> 1) Will speed the process of achieving physical equilibrium and allow the physical system to <br /> be evaluated over a shorter time period than would occur naturally. <br /> 2) Will speed the process of achieving chemical equilibrium by offsetting the production of <br /> acidity while pool is deoxygenating. <br /> 3) Any waters that flow through the mine and eventually report to the surface as seeps and <br /> springs will be of higher pH and have alkalinity to neutralize acid salts that may be present <br /> in the mine or historic flow paths. <br /> 4) Should future drawdown of the mine pool become necessary, drawdown could be done <br /> more rapidly because pool water would be of higher pH and better quality. <br /> As the entire system moves to equilibrium, the addition of high pH waters will force physical and <br /> chemical equilibrium faster and result in lower initial concentrations of dissolved heavy metals in the <br /> pool. <br /> If' <br />