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PROJECT PURPOSE <br />The intent of this project is to construct enlarge the existing spillway, which is located near <br />the dam's right abutment. Improvements will lower the crest elevation of the spillway by <br />1.5 feet and increase the width of the spillway from 350 feet to 585.7 feet. With these <br />improvements the dam will be able to contain the peak reservoir volume associated with <br />75% of the Probable Maximum Flood (PMF) as required. The new spillway will have the <br />ability to pass a peak flow of 22,888 cubic feet per second (cfs). During the design event the <br />maximum water level in the reservoir would be limited to elevation 4,809.58, which is 0.02 <br />feet below the crest of the dam. <br />Safely conveying the design flow requires a significant amount of earthworks both upstream <br />and downstream from the spillway crest. Upstream areas will be excavated to create an <br />efficient flow path from the reservoir to the spillway crest. Downstream of the spillway <br />crest grading is required to widen the existing channel to prevent a backwater condition. <br />Channel armoring will be added at key locations downstream of the spillway to minimize <br />erosion and prevent headcutting that could threaten the dam. <br />Minor work on the dam crest is included in this project. Currently several low spots exists. <br />Fill will be placed in these locations to raise the minimum elevation of the dam crest above <br />the water surface elevation that results from the PMF. <br />Planned improvements are intended to satisfy requirements of the SEO, provide for the <br />continued safe operations of the dam and prevent storage limitations from being placed on <br />the reservoir. <br />18 <br />