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• Upon termination of the operation of the enhanced evaporation system, all materials (i.e. piping, <br />electrical, etc.) would be removed from the site. The exposed geomembrane covering would <br />then be closed in place in the collection pond or removed and disposed of in accordance with <br />applicable federal, state, and local requirements. <br />Evaporation of the pumped water could not be accomplished during the winter, and an additional <br />form of water treatment would be required during the initial phase of water management. BMRI <br />proposes to utilize nanofiltration to treat the flow of groundwater pumped from the backfill <br />during the winter. Nanofiltration (see Section 4.2) would be employed for a time period of 6 to 7 <br />months. <br />6Z Long-term Water Management Plan <br />The long-term water management plan would maintain the reversed hydraulic gradient at the <br />steady-state flow rate of approximately 110 gpm. In addition, the water treatment method will be <br />• changed from enhanced evaporation to a passive treatment system that would ultimately route all <br />of the treated water back into the Rito Seco hydrologic system. <br />Short-term laboratory testing of the passive treatment systems, as described in Section 4, has <br />provided proof-of-principle evidence that the groundwater flowing from the West Pit can be <br />effectively treated for sulfate, manganese, and TDS without the need to employ active water <br />treatment. Because passive treatment systems rely on naturally occurring biologically-mediated <br />reactions, the time required to fully test and design an effective full-scale water treatment system <br />is longer than the time needed to test active water treatment systems (e.g., nanofiltration). <br />Therefore, field-scale pilot testing will be conducted in pazallel during the initial phase of <br />implementation of the water management plan such that the passive treatment system will be <br />engineered to ensure long-term operation over the range of environmental conditions present at <br />the San Luis Project. <br /> <br />Battle Mountain Resources, lnc. <br />pa1001671reportslmarchrpdtrl6wvrmnglmarch.doc 67 March 1?, 1999 <br />