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A limiting permissible velocity of 5.0 feet per second (fps) was used to ensure that the postmining <br />drainage channels would be nonerodible and stable. The permissible velocity was obtained, Table <br />3.4, from 'Red Book" by Barfield et al., 1981 for a grass mixture vegetated channel. The shape <br />of the reclaimed channel was assumed for design purposes to be trapezoidal with 10h:1v side <br />slopes as a worst case condition. The side slopes will be no steeper than 10h:1v. <br />The channel bottom was calculated using the SEDCAD+ Version 3.0 computer program. The <br />channel width was increased to insure that the peak velocity was below the limiting velocity. The <br />typical trapezoidal channel section was selected for design purposes only for the entire length of <br />the reclaimed channel. 'Reclaimed Drainage Channel Design" on the following pages contains the <br />specific design information of the reclaimed drainage channel in the eastern portion of the New <br />Horizon 2 permit area (San Miguel Draw). <br />The reclaimed drainage channels will be topsoiled and revegetated according to Sections <br />2.05.4(2)(d) and (e) respectively. Attachments 2.05.4(2)(C) -1 and 2.05.4(2)(C) -3, which <br />immediately follow this section, show the designs for these restored channels. <br />Any other channels which are left after reclamation are road ditches, as described in Section <br />2.05.3(3) - Mine Facilities. <br />(Revised June 2010) 2.05.4(2)(c) -12 <br />