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A plan view of the actual channel is shown on Exhibit M-3 <br />for the Northen # 1 Mine. <br />• <br />A profile of the established channel is given on the <br />following page. As is seen on the profile, the maximum grades <br />are 1n two sections: one at the upper reach and one at the lower <br />reach. The grades in these two reaches are 7.18%. The total <br />length of reconstructed channel 1s 950 feet. <br />Velocities for the maximum grade have been calculated as <br />follows: <br />bottom width = lU.U feet <br />slideslopes = 3H:iV <br />depth = 1.5 feet <br />channel slope = 7.18 <br />Manning's n for 8 retardance grass = U.05 <br />• <br />Area of channel <br />Wetted perimeter <br />Hydraulic radius <br />= 36.75 sq. ft. <br />= 19.49 ft. <br />= 1.246 <br /> <br />Using Manning's low equation results in a flow of 34U cfs <br />and a velocity of 9.25 ft/second. <br />The high retardance grass will be used throughout the <br />channel. The mix used was prescribed in a memo from Gregg Squire <br />to Candy Thompson on January 2, 1986. It is enclosed on the <br />following page. <br />The miramat fabric was installed under the direction of a <br />Mirafi representative present during the installation. The grass <br />came up rapidly in the fall of 1986 and the channel has shown no <br />signs of erosion since that time. <br />/~1-5C ~// /~~ <br />-- - -- --- - - - <br />