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VI. ESTIMATED COSTS A. General Four different types of dams were examined as a part of this study. The dams studied were: 1. Earthfill with Impervious Core 2. Rockfill with Impervious Core 3. Rockfill with Concrete Face. . i '.l ',"1 4, Concrete Arch In all cases, the preliminary site investigations and the spillway were common to all the different dam types. B. Type of Dam ''''i " ',:! ",.'1 ::! , "",j II ; ,~ ~. ~ Ik"~ >-': ',.j , , 1. Earthfill with Impervious Core Construction of the Earthfill dam with Imper~~ vious Core would involve excavation of a cutoff trench to bedrock and installation of a grout curtain in the foundation rock. The dam itself would be comprised of a Zone II random fill sec- tion with an upstream slope of 3 horizontal to 1 vertical, and downstream slope of 2 horizontal to 1 vertical. The crest width of the dam is 15 feet. The Zone I core would have a minimum thickness of 5 feet and a maximum thickness of 102.5 feet at the foundation at the deepest sec- tion. A chimney drain and horizontal drainage blanket are provided downstream of the core. Filter materials may be required between the Zone I and Zone II materials depending on the gradation. 2. Rockfill with Impervious Core In this design all overburden and loose material would be removed from the full base width of the dam and a grout curtain installed along the centerline the full width of the dam. The upstream and downstream slopes would be 2 horizontal to 1 vertical. The Zone I impervious core would have a minimum thickness of 10 feet and a maximum thickness of 80 feet at the founda- tion at the deepest section, Filter zones would be provided upstream and downstream of the core. The Crest width is 15 feet, -30-