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. 2. Dam Stability The stability of several possible proposed dam sections was eva luated with respect to bearing capacity, overturning about the toe, sliding along the base, and uplift. Once these factors had been considered, a preliminary design section for the dam was se lected. . A roller-compacted concrete dam section with its foundation at an elevation of 5,168 ft, crest at an elevation 5,256 ft, maximum normal pool at an elevation of 5,250 ft, and downstream pool at an elevation of 5,180 ft, was assumed. The proposed dam had a 20-ft crest width, a 1:24 (horizontal:vertical) upstream face slope, and a 1:0.6 downstream face slope. This preliminary study has assumed that only 4 ft of freeboard is available at the maximum pool elevation. It is expected that additional freeboard will be required; however, because additional freeboard improves stabil ity, a minimum freeboard was used in the preliminary analysis. A detailed analysis was conducted to evaluate the stability of the selected section. This analysis was a static analysis and considered hydrostatic and earth pressures on both the upstream and downstream faces of the dam, as well as bearing, uplift, and frictional forces along the base of the dam. The dam was checked for stabil ity with the reservoir both full and empty. Results of the analysis are summarized in Table IV-I. While this is not a complete analysis sufficient for final design, it does indicate that few, if any, problems will be encountered in maintaining stability at this site. The selected section proved to be quite good in that the resultant force for the full-reservoir case has a resultant line of action with an eccentricity of less than 1 ft from the centroid of the base of the dam. . 3686-a/8 IV-6