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5.3.2.2 Robinson Mill Water Return Pipeline System <br /> Description: This pipeline system transfers industrial water from Robinson Lake to the Mill <br /> Complex via a 30-inch and parallel 26-inch pipeline for a distance of 3 miles, of which 2.5 miles <br /> are above the Chalk Mountain Interceptor Canal. <br /> Location: The pipeline system traverses the north and east faces of Chalk Mountain from <br /> Robinson Lake to the Mill Complex. <br /> Spill Potential: Failure of either of the pipelines could result in a discharge of industrial water <br /> that could enter the upper portion of the Chalk Mountain Interceptor Canal. This interceptor <br /> canal discharges directly into the Eagle River. Another potential problem is erosion of native <br /> materials above the interceptor if the pipeline system ruptures. Sediment loading in the <br /> interceptor would be increased and industrial water could reach the canal. Rupture of the line in <br /> that portion of the Robinson Mill Water Return Pipeline located downgradient of the Chalk <br /> Mountain Interceptor would have no effect on the Eagle River because it would be contained <br /> within the tailing system. <br /> Potential Volume Spilled: Based on flow rates, and assuming all pumps were running when the <br /> spill occurred, up to 15,000 gallons could be released into the Chalk Mountain Interceptor Canal. <br /> Prevention and Control: Several "cut-outs" have been installed along the Chalk Mountain <br /> Interceptor Canal to divert any spills back into the tailing system to eliminate or minimize <br /> discharges to the Eagle River. <br /> Countermeasures: If either of the pipelines fail, all Robinson Lake pumps would be shut down <br /> and valves in the mill complex would be closed to prevent backflow. Any discharge to the Chalk <br /> Mountain Interceptor Canal would be diverted through the"cut-outs" into the tailing system. <br /> Nearest Clean-up Equipment: Mobile heavy equipment (back-hoes, dozers, etc.) is available <br /> throughout the minesite. <br /> Monitoring: When operational and when the roads are passable, the system is visually checked <br /> daily. When the mine is idle, the system is visually checked weekly. The water level in the 2 <br /> million-gallon storage tank at the Mill Complex is telemetrically transmitted to the Mill Control <br /> Room. Should this level remain static, or decline for a long period, it would be indicative of a <br /> "no-flow" condition in the pipeline, which would signal a leak in the line. Similarly, a pressure <br /> drop at Robinson would be indicative of the need to investigate the lines for potential leakage. <br /> 47 <br />