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Letter to Larry Perino 3 October 18, 1993 <br /> SGC has suggested that both the monitoring program and the <br /> bulkhead inspections be terminated after five years or when <br /> the mine pool has approached equilibrium, whichever is first. <br /> The Division will require that the monitoring and inspection <br /> programs continue for as long as they can yield useful and <br /> pertinent data on the impacts of mine flooding. The best way <br /> to handle this aspect of the plan is for SGC to prepare a <br /> final report and request for termination of monitoring, with <br /> both data and justifications, once a point of diminishing <br /> returns has been reached. The Division will then determine if <br /> the monitoring and inspection program can be terminated, or <br /> perhaps modified, based on the information in the report. <br /> 5. The Division will require installation of a valve on the 1 <br /> inch pipe at the American Tunnel bulkhead that will allow <br /> direct sampling of the water impounded behind the bulkhead. <br /> Such sampling is necessary for two reasons: the quality of the <br /> impounded water will affect the rate of concrete decay, and, <br /> since the American Tunnel bulkhead is the lowest point of the <br /> flooded workings, any gravity settling of dissolved bromide <br /> could be detected. A sample should be drawn from the 1 inch <br /> pipe, and analyzed for the approved parameters, at least <br /> annually. <br /> 6. SGC has proposed that contingency plans be activated if <br /> bromide is detected in surface flows, indicative of emergent <br /> mine pool water. Be advised that action may be required, even <br /> if no bromide is detected, based on anomalies identified by <br /> the monitoring plan discussed above. The WQCQ regulates <br /> discharges to surface streams in Colorado, and will likely <br /> have input into what discharges will require remedial actions <br /> by SGC. <br /> 7. The Division has determined that the appropriate way to <br /> include the provisions of TR-14, once approved, into the <br /> financial warranty held for the Sunnyside Mine, is to hold a <br /> bond in the amount needed to replace the bulkheads one time. <br /> The bond will be held until the mine pool reaches equilibrium <br /> (when a graph of the rate of rise becomes asymptotic) plus <br /> five years. SGC must submit a detailed summary of the cost to <br /> replace the bulkheads for Division review. Submittal of such <br /> a summary can be made a condition of TR-14 approval, given the <br /> limited time before the decision date, and the fact that a <br /> more accurate cost analysis will probably be available after <br /> SGC has moved further along in the process of construction <br /> planning and mobilization. In any case, it would appear <br /> appropriate to require that the bond be in place prior to <br /> pouring the Terry Tunnel or American Tunnel plugs. <br /> The Division received four letters regarding TR-14 during the <br />