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Water in the collection sump will be either pumped to the VLF or ESP when the <br />pumpback system is operating, or flow into the experimental ponds (e,g., concrete <br />overflow pond and Arequa limestone pond)and/or treatment works (e.g., sedimentation <br />pond). Four pumps have been installed to accommodate varying pumpback rates and <br />provide aback-up in the event of a mechanical or electrical problem. Two submersible <br />pumps, each with a rating of 15 horsepower (hp), are both capable of pumping up to 110 <br />gallons per minute (gpm) over the elevation change from the pumpback system to the <br />VLF or ESP. A pair of vertical turbine pumps rated at 75 hp each have the ability to <br />move a design rate of approximately 500 gpm from the pumpback building to the VLF or <br />ESP. pumpback water is transmitted to the VLF or ESP via a six inch diameter pipe that <br />changes from steel construction at the pumpback building to high density polyethylene <br />(HOPE) pipeline with pressure ratings increasing as the distance from the pumps <br />becomes greater. The majority of the pumpback pipeline is buried for further protection. <br />Check valves are installed at strategic locations to minimize the amount and velocity of <br />back flow into the collection sump where the pumps aze located when the pumpback <br />system is deactivated. The check valves also would limit the amount of water that could <br />escape from the pipeline in the event of a line break. Any flows from a line break would <br />be captured by the sedimentation pond. A totalizing flow meter is installed on the <br />pipeline in the pumpback building. <br />Flows that aze not pumped back to the VLF or ESP aze usually directed into the <br />experimental ponds. This is accomplished via a pipe that extends from the pumpback <br />collection sump to the concrete overflow pond. Water in the concrete overflow pond <br />flows to the Arequa limestone pond through a riser pipe connected to a network of <br />dispersion lines installed beneath a layer of limestone rock and/or over the spillway. <br />Flow from the Arequa limestone pond enters the sedimentation pond via an armored <br />spillway. Alternatively, flow can be directed to the sedimentation pond impoundment or <br />spillway. Water exiting the sedimentation pond enters Arequa Gulch and is measured for <br />compliance with the requirements of the revised Cresson Project Permit at Outfall OOIA. <br />Post-Mining Management: <br />The Arequa Gulch pumpback system will be operated during the reclamation and closure <br />phases in the same manner as described above for the active operations. Water that is <br />pumped back may be utilized for rinsing of ore, dust suppression, irrigation of reclaimed <br />portions of the VLF, or other appropriate uses. CC&V will monitor water quality within <br />the VLF during reclamation and closure. As specified in the permit issued by the Boazd, <br />puncturing of the VLF liner system will not be allowed until water quality meets <br />applicable standazds. Puncturing of the VLF liner system will re-establish a hydrologic <br />regime and provide for a stable reclaimed azea. It is presently anticipated that the <br />treatment works and pumpback system will be removed and the dischazge permit <br />terminated once the VLF liner system can be and is punctured. <br />6/6/2003 <br />