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. . . CHAPl'ER III DESIGNS AND ESTIMATES the upstream face of the dike, on the stream side of the county road fill, and at the end of the concrete downstream from the spillway, slui~ way, and headworks. Curecanti Creek Diversion Dam The Curecanti Creek Diversion Dam would be constructed on the Curecanti Creek immediately below the confluence of Buffalo Gulch with Curecanti Creek. The structure would be approximately 175 feet long. It would be designed to divert a maxi~of 250 second-feet into the Black Mesa tunnel through an inclined shaft which would drop approximately 480 feet in elevation over a horizontal distance of about 650 feet. The diversion structure and inlet to the intake shaft would be constructed in the West Elk breccia, which would provide a stable foundation. About 75 percent of the intake shaft would be constructed through Mancos shale. The diversion dam would be a concrete gravity structure with an uncontrolled ogee spillway in the center portion of the dam. The overall length of the dam would be about 175 feet with a top elevation of 8,752 feet. The spillway would have a crest length of 40 feet and is designed to pass 560 second-feet, the flood flow of laO-year frequency, at a maximum water surface elevation of 8,749 feet. A 30-inch pipe con- trolled by a slide gate would be installed to the right of the spillway to bypass water to Curecanti Creek. The inlet to the intake shaft ;/ould be a concrete structure consisting of a trashrack, grating, a 10-foot covered Parshall flume with a recorder house, and a transition to the shaft. Releases to the concrete-lined intake shaft would be regulated by two 72-inch by 72-inch cast iron slide gates e>t the inlet. The shaft would consist of a 6-foot diameter horseshoe section with flat bottom inclined at an angle of about 520 from the horizontal stilling pool and a short 7-foot diameter horseshoe section with flat bottom. The stilling pool would be a 16-foot diameter horseshoe section with flat bottom and about 80 feet in length. The transitions at each end of the stilling pool would be horseshoe- shaped with flat bottoms. Black Mesa Conduit Black Mesa Canal The Black ~~sa Canal would have a capacity of 275 second-feet and would convey water about 2.8 miles from Soap !?ark Reservoir to the inlet portal of the Black Mesa tunnel. The first 1.1 mile would include 0.4 mile of concrete bench flume that would be constructed along steep side slopes and 0.7 mile of unlined earth cana.l. This reach of canal would be constructed primarily in the West Elk breccia. The remainder of the canal would be an earth-lined section constructed in Mancos 20