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f <br /> Mr. Clapper and Mr. Romig <br /> September 24, 1996 <br /> Page 2 <br /> South, Range 79 West,of the 8th P.M., In Eagle County. It is anticipated that the tailing <br /> removal process will be completed by the end of 1996. After the removal of the tailing <br /> Is complete, the reservoir will be filled with fresh water. It is anticipated that In this <br /> process it could take several years before the quality of the seepage flow through the <br /> foundation and embankment will meet Eagle River discharge standards. <br /> Currently, the seepage water that flows from the toe of the structure is collected <br /> and pumped back over the embankment into the Dam 4 water pool. The pH of the water <br /> is in the 6 to 7 range and the water contains concentrations of heavy metals. After the <br /> removal of the tailings is complete, it will be necessary to pump the seepage water up to <br /> Robinson Reservoir which is currently within the process water system. <br /> Exilling &jliawater System <br /> The seepwater return system was modified to its current configuration In 1985. <br /> The system consists of an earthen cutoff dike below the downstream toe of Dam 4 which <br /> creates the primary seepwater pond, and a secondary containment concrete cutoff wall <br /> located immediately downstream of the earthen dike. The Seepwater Pump Station, which <br /> Is located between the two barriers, is a wet well type, enclosed structure with outside <br /> dimensions of 12 feet by 16 feet. Three pumps are installed In the pump station: two 15 <br /> horsepower (approximate capacity of 150 gpm) and one 30 horsepower (approximate <br /> capacity of 400 gpm)submersible dewatering pumps. The larger pump is used only during <br /> the snowmelt period of unusually wet years. The start/stop operation of the pumps is <br /> automatically controlled by contact level probes in the wet well. The pump station wet <br /> well Is hydraulically connected to the primary seepwater pond by two 8-Inch diameter <br /> stainless steel pipes. <br /> 20' d Z00" oN Tb: TT 96 bZ daS Z08Z-T9Z-20s�-T : -131 aosSd �8 Jalaaym . m. m <br />