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• In the lower reach, a topsoiled channel would have an <br />estimated peak flow velocity of 5.2 fps (Figure 1). Flow <br />velocities of this magnitude would be marginally erosive on this <br />steep slope. Therefore, ECC proposes to leave, as a permanent <br />stream channel, the existing rip rapped drainage channel that has <br />been constructed along the lower reach. This channel is approxi- <br />mately 8 to 10 ft wide, and has been riprapped with material <br />approximately one foot in diameter. This channel conforms with <br />performance standards for properly stabilized stream channels. <br />This area is currently covered by winter snowpack, and the <br />channel geometry and size of the rip rap cannot be confirmed. <br />Following snowmelt, the existing channel will be examined to <br />confirm its capability to pass the peak flow from the 10-year, <br />• 24-hour precipitation event. If this capacity cannot be con- <br />firmed, ECC will either modify the existing channel to bring it <br />into conformance, or remove the existing riprap and construct an <br />earthen channel with the capacity to pass the peak flow from the <br />10-year, 24-hour precipitation event. The Colorado Division of <br />Mined_Land Reclamation-wi-1.1_be informed of ECUs proposed action <br />within 120 days of this submittal. <br />5 <br />• <br />