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<br /> <br />. <br /> <br />7 <br /> <br /> <br />. <br /> <br />Cache la Poudre Power Oonduit <br /> <br />A pressure tunnel 20 feet in diameter and 5,000 feet in length <br />would convey flows ranging up to 3,000 cfs from the forebay (Oache <br />la Poudre Forebay) to the surge tank for the Cache la Poudre <br />Powerplant. An inlet structure and a trash rack would be installed <br />at the in1et portaJ. of the tunne1 followed by a gate shaft and <br />emergency gates. The forebay and the outlet portal of the tunnel <br />would be connected by a service road. <br /> <br />Cache la Poudre Powerplant, Penstock 1 Surge Tank, <br />and Channel Contr01 Structures <br /> <br />. <br /> <br />The Cache la Poudre powerplant would be located on the north <br />shore of Grey Mountain Reservoir. The draft tubes wou1.d be set <br />about 50 feet below the normal water surface of the reservoir to <br />gain additionaJ. head when the reservoir is in a drawn down condition. <br />The plant would be used for peaking; the head would vary with the <br />water surface in Grey Mountain Reservoir and in the fore bay . <br />Installed capacity of the 4-unit plant would be 250,000 KW. The <br />plant factor would be about 7.2 percent on an annual basis and 9.2 <br />percent on a weekly basis assuming 5-1/2 days per week. <br /> <br />A steel surge tank about 48 feet in diameter and 160 feet <br />high would be constructed at the lower end of Cache la Poudre <br />Conduit. Four penstocks originating at the surge tank each 88 <br />inches in diameter would convey the water 1,500 feet to the power- <br />plant. The design head of the plant would be 1,180 feet and the <br />maximum capacity would be 3,000 cfs. <br /> <br />The following structures, aJ.so included in powerplant costs, <br />are designed to permit operation of the powerplant without <br />injurious effects when Grey Mountain Reservoir is at 10w stages. <br />An overflow weir would maintain a pool for keeping the draft tubes <br />submerged at aJ.l times. Dmmstream from the pool a baffled apron <br />drop extending to the river channel would be provided to prevent <br />erosion. <br /> <br />When the water in Grey Mountain Reservoir is at the top of <br />the dead storage level, the headwaters would be about 1-1/2 miles <br />downstream from the powerplant. To prevent fluctuations in this <br />1-1/2-mile reach of the river, at low water elevations, two concrete <br />ogee-type overflow dams, each 35 feet in height, would be con- <br />structed to maintain two permanent pools. At times when the water <br />level is rising above the top of the dead storage pool the dams <br />and successively more of the baffled apron drop would be submerged. <br />