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<br />G' <br /> <br />- <br /> <br />5-foot wide chimney drain is connected to a 5-foot thick sand and <br />gravel blanket which will be placed under the downstream portion <br />of the dam below elevation 8,290 feet. A toe drain would be <br />located in the sand and gravel blanket. <br /> <br />The upstream face of the dam would be protected bya 3-foot <br />layer of riprap on 18 inches of sand and gravel bedding extending <br />from the crest to a 20-foot wide berm at elevation 8,230 feet. <br />Above and below the berm, the upstream face would also have a <br />slope of 3:1. The downstream portion of the dam would have a <br />15-foot layer of rockfill with a 2:1 slope from the crest down to <br />elevation 8250 feet, a 3:1 slope to elevation 8,170, and a 2:1 <br />slope below elevation 8,170 feet. <br /> <br />The embankment would have a total volume of 1,896,000 cubic <br />yards, including 1,520,000 cubic yards of earthfill, 50,000 cubic <br />yards of sand and gravel, and 246,000 cubic yards of cobble fill <br />and 34,000 cubic yards of riprap. A forest development road <br />would be relocated across the crest of the dam and have a 6-inch <br />layer of gravel surfacing. <br /> <br />A roller compacted concrete (RCC) alternative was initially <br />studied but is not feasible because of the poor foundation <br />conditions at the damsite. <br /> <br />Outlet Works <br /> <br />The outlet works are sized to meet downstream release <br />requirements as defined in the 1967 study and to meet evacuation <br />criteria in ACER TM No.3. The outlet works would include a <br />concrete conduit on the left abutment of the dam. The upstream <br />325 feet of the conduit would be 5-foot diameter steel-lined <br />concrete conduit that would lead to a dome-shaped gate chamber <br />housing a high pressure gate. Below the gate chamber the outlet <br />would consist of a 48-inch diameter steel pipe housed in an <br />8-foot diameter horseshoe conduit 500 feet long extending to an <br />access/control house located at the point where the conduit would <br />branch. Releases to Buzzard Creek would be controlled by a high <br />- pressure gate that discharges into a stilling basin. <br />provisions are included for making releases into a canal outlet <br />should future project requirements dictate this need. The outlet <br />works would be used to bypass the flows of Buzzard Creek during <br />construction of the dam. FOllowing placement of the embankment <br />to a point where storage could be initiated, a vertical shaft 40 <br />feet high, surmounted by a steel trashrack, would be installed as <br />an intake structure with a sill elevation of 8,180 feet. <br /> <br />6 <br />