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. SECTION IV SUMMARY OF GEOTECHNICAL FEASIBILITY STUDY A. GENERAL ATEC Associates Limited, Inc. (ATEC) completed a feasibility-level geologic and goetechnical engineering investigation for the proposed Webster Hill Dam. The intent of this study was to aid in evaluating the suitability of the proposed dam site for construction of a water- and-power-supply dam. The objective of this study was to identify surface and/or subsurface conditions that would either facil itate or preclude the development of this project. Geologic mapping was performed, test borings were drilled, and field and laboratory tests of rock and soil were performed in the area of the proposed dam axis. . The following is a summary of ATEC's findings, conclusions, and recommendations. For more detailed information and evaluation, see Appendix A, Geotechnical Feasibility Report. B. SITE GEOLOGY Geologic mapping was done at both abutments: on the north river bank for a distance of 1~ mi downstream and 1 mi upstream of the dam axis, and on the south river bank in the vic inity of the south abutment to include 1,600 ft of the river bank, bluffs, and terraces. Mapping was conducted to determine the continuity of the bedrock and the elevation of its contact with overlying gravel and soil deposits. This elevation had been crucial to the location of a higher dam proposed by the Bureau of Rec 1 amat ion ~ mi downstream of the Webster Hill site, and was believed to be crucial to the feaSibility of this project. . The proposed dam site is located at a sharp bend, where the river cuts through a resistant bedrock ridge of shale and sandstone of the Wasatch Formation. At the bend, the north side of the river channel is against an abandoned railroad bed notched into the steep bank that 3686-a/8 IV-l