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COAL CANYON REALIGNMENT <br />As part of the design for CRDA 2 the Coal Canyon drainage channel was <br />realigned to provide a more uniform, controlled flow between CRDA 1 and 2. <br />The initial design called for rock drop structures with a 2h:1v slope to drop the <br />water in approximately 5 foot elevation intervals. The rock size was not well <br />defined. The channel between the drop structures was 0.6%. This channel <br />design was reevaluated in 1996, see pages Misc-11 thru 19, appendix 13-2. The <br />new drop structures were constructed but sediment backed up between the drop <br />structures which caused numerous maintenance problems. <br />During the reclamation of CRDA-2 in 2002, the sediment retained by the drop <br />structures was harvested for cover material. The realigned channel was <br />excavated on a uniform grade between the upper dip section and the two 81" X <br />59" culverts located under haul road number 4. <br />• See exhibit 60 for the location of the realigned channel and Exhibits 53 and 55 <br />for typical channel cross sections. <br />The realignment of the Coal Canyon drainage past CRDA 3 will not be <br />pertormed since the Operator does not plan to construct CRDA-3 because the <br />mine has been sealed. The proposed channel location is shown on Exhibit 52 <br />and cross sections are shown on Exhibits 53 and 55. <br />• 13-16 (Rev. 12/02) <br />