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1. Do nothing and assume the risl:s of flash flooding in tfie future. <br />• 2. Provide flood protection for the mina site by: (a) diverting <br />excessive storm runoff from the upper basin into adjacent <br />watersheds, and (b) construct an adequate storm runoff drainage <br />system in the loo-rer basin. <br />The large diversion channel is proposed in alternative 2 only because <br />of the advanced development in the lo~rer basin, and cbliteration of the <br />natural drainage system in that part of the watershed. The diversion <br />channel will provide the necessary flood protection and can also be used <br />effectively to divert runoff from normal precipitation and thus avoid <br />environmental problems from water continually passing over and through the <br />mine site. mother advantage which :rill be realized by excavating this <br />channel is the development of borro~:~ materials (top soil) that is suitable <br />for reclairing the fearer basin after mining ceases. <br />Alternative 2 should be considered as a package. ~ storm runoff sv~'.em <br />in the lower basin arithout upstream protection would control minor runoff; <br />however, during extreme hydrologic events, such a system would be almost <br />ineffective. This report proposes a drainage plan which mitigates the <br />potentially serious situation that presently exists. <br />Drainage Plan <br />The drainage plan proposes tc divert storm runoff from the upper basin <br />by means of a contour channel. This channel arould be laid out on a 5 to 7 <br />percent grade from an apex in the center and discharge water into adjacent <br />watersheds to the east and west of Restr.,oreland Canyon. Since failure would <br />result in extrec.e dar~age and perhaps less of life, the channel would <br />• be designed to carry runoff from the ?MTS as she~,~n in Fieure 4. <br />