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Memo to Dave Bucknam <br /> Dutch Creek Flume Recommendations <br /> page 3 <br /> the waste pile. We propose several tasks to attempt to preclude the breakout of <br /> Dutch Creek to the South. <br /> (1) A second tier of Jersey barriers will be placed above and slightly behind the first <br /> tier on the south side of the creek. Because we will not place a second tier on <br /> the north side of the flume, in the event of a breakout the water should <br /> preferentially flow toward the north and the yard area. <br /> (2) If the flow exits the Dutch Creek flume we do not want it to parallel the flume. <br /> It may then undercut the flume and pipe which could fail into Coal Creek. In <br /> order to accommodate flow across the yard area away from the flume and back <br /> into Coal Creek, we will excavate a subtle channel (approximately 1 .5 to 2 feet <br /> deep) from the area immediately adjacent to the up gradient end of the 9' pipe, <br /> diagonally towards the northeast. We will place heavy equipment scrap to <br /> armor the southeastern channel sideslope. The frame of an abandoned <br /> conventional underground miner and several pump casings exist in the <br /> immediate yard debris. Finally, we will remove the earthen berm which has <br /> been placed along the crest of the yard area outslope above Coal Creek in line <br /> with the subtle excavated channel. <br /> (3) If the flow breaks out of the Dutch Creek flume and enters the yard area it <br /> would encounter the varied collection of scrap metal, abandoned equipment, <br /> buses, abandoned trucks and other junk. In order to avoid the water from <br /> washing this assorted debris into Coal Creek we will push this material out of <br /> the immediate area of the subtle excavated channel. <br /> Debris Flow Threat <br /> Coal Basin is nationally noted for its unique proclivity for debris flow. The most recent <br /> documented debris flow events occurred in Dutch Creek in 1977 and 1983. The <br /> 1977 event actually damaged the mine office and change house. Evidence of the <br /> 1977 event is obvious in the form of the coarse rock debris levees which bound the <br /> Dutch Creek channel just west of the change house. These levees consist of open <br /> matrix linear ridges of coarse cobbles, up to six foot in diameter. The cobbles and <br /> boulders are angular, unlike normal rounded alluvial gravel cobbles. The levees' slopes <br /> approach 1 :1 , particularly adjoining the channel. As a result the levee material is <br /> easily undercut by flood flow-s within the Dutch Creek channel. This process results <br />