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Memo to Dave Bucknam <br /> Dutch Creek Flume Recommendations <br /> page 2 <br /> Tuesday evening, June 13th. There are several possible failure scenarios: (1 ) Flow <br /> exceeds the design capacity and the channel overflows, undercutting the flume, which <br /> fails; (2) coarse debris plugs the pipe and the flume overflows, is undercut, and fails; <br /> or (3) a debris flow from up gradient on Dutch Creek obliterates the flume and pipe. <br /> Any of these events will cause the flume and pipe to fail. <br /> To forestall failure mode one, we should attempt to maximize the flow capacity of the <br /> flume and pipe. Steve has suggested using Jersey concrete barriers to raise the flume <br /> side boards. This appears an appropriate and realistic response. Using a hand level <br /> we determined how far up the flume the elevation matched that of the pipe invert. <br /> This appeared to be -a point approximately 85 feet above the up gradient end of the <br /> pipe. We propose to place one rum of Jersey barriers along each flume side board to <br /> provide additional side board height. These barriers will not be watertight, but they <br /> should prevent major erosion of the slope material. They should be heavy enough to <br /> resist the impact of the flowing water. This will require approximately 20 barriers and <br /> can be accomplished with a crane. Bogue construction has a source for the barriers <br /> in Carbondale. They can be installed within a few days, before the warm up is <br /> predicted. <br /> The second response priority, to be implemented in the event of plugging and <br /> imminent failure of the flume and pipe, is to provide notice to the local emergency <br /> preparedness officials. These officials have the infrastructure with which to predict <br /> any hazard which may exist to downstream occupants, and with which to implement <br /> appropriate emergency response and warning. Steve Renner contacted the Pitkin <br /> County Under Sheriff wednesday, June 7th and appraised him of the situation. The <br /> Under Sheriff instructed Steve to contact his office in the event of a failure of the <br /> flume or pipe. <br /> The third response priority is to prepare a contingency plan for implementation in the <br /> event that the flume and pipe plugs. The old wash plant coal refuse pile is located <br /> immediately south of the flume. Erosion of this pile would yield coal waste which <br /> would be washed into Coal Creek and may leave the mine permit area. If the flume <br /> or pipe were to fail into Coal Creek they might contribute to a blockage of Coal Creek. <br /> If this blockage were subsequently breached by Coal Creek it could result in an <br /> elevated water level breakout which could exacerbate damage down stream on Coal <br /> Creek. In the undesirable event of a failure it appears preferable for the stream flow <br /> to exit the flume toward the north into the yard area, rather than to the south and <br />