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<br />. <br /> <br />A topographic saddle is upstream from the right abutment, The <br />findings from exploratory work strongly indicate that a tongue of the <br />main glacier that formerly occupied the valley may have entered this <br />area and together with its outwash scoured a deep channel in the saddle, <br /> <br />Dam and Dike Structures <br /> <br />The dam shown on the feasibility desigu drawing, exhibit 2, <br />would be a zoned earthfill structure with a height above streambed <br />of 313 feet, a crest width of 30 feet, and a length of 1,300 feet <br />,at crest elevation 7885,0, A cutoff trench to bedrock backfilled with <br />impervious material would extend across the valley under the dam, <br /> <br />A dike, also shown on exhibit 2, would be located across the <br />saddle upstream from the right abutment of the dam. It would also <br />be a zoned earthfill structure with a height of 78 feet above original <br />ground surface, a crest width of 30 feet, and a length of 450 feet <br />at crest elevation 7885,0, A rolled earthfill blanket with a thickness <br />of 10 feet would be placed under the upstream side of the dike and <br />down into the reservoir to about elevation 7600 to prevent excessive <br />seepage under the dike, The upstream faces of both the dam and dike <br />would be protected by a 3-foot layer of riprap. Total volume of embank- <br />ment in the dam and dike would be about 7,675,000 cubic yards, <br /> <br />. <br /> <br />The uncontrolled spillway would consist of a 100-foot-wide <br />channel intake in the right abutment delivering to a covered <br />rectangular box section extending through the crest of the dam <br />and thence into a rectangular chute ending in a stilling basin, <br />The spillway, with a crest elevation of 7860,0, the top of the <br />active conservation pool, was designed with a capacity of 30,000 <br />cubic feet per second with the reservoir water surface at elevation <br />7879, the top of surcharge capacity. A bridge over the stilling <br />basin is provided for a service road, <br /> <br />The primary outlet works would be located in the right abutment, <br />This complex would be comprised of a glory-hole-type intake, an <br />Il-foot-diameter tunnel leading to a gate chamber housing an emergency <br />gate, and a 90-inch-diameter steel outlet pipe, placed within a <br />12-foot-diameter horseshoe tunnel and extending from the gate chamber <br />to the control house, The control house would have four high-pressure <br />gates discharging into a circular stilling basin, The capacity of <br />the outlet works would be 2,000 cubic feet per second with the <br />reservoir water surface at elevation 7695, the bottom of the active <br />conservation pool, The intake structure is designed so that a low <br />inlet is available for diversion during construction of the dam, <br />Upon completion of the dam the low inlet would be plugged and the <br />higher glory-hole inlet used, <br /> <br />An auxiliary outlet works, also to be located in the right <br />abutment, would be used to make releases during the period required <br /> <br />. <br /> <br />7 <br /> <br />