Figure 183. --Whiskeytown Dam outlet works--Gate chamber.

+2" Dia SEC G-G

RUBBER SEAL

and functioning as an orifice, air will enter and become confined in the horizontal portion of the tunnel. The compressed air will release itself through the intake shaft, and the backlash will displace the standing water in the shaft with such force that the intake structure may be severely damaged. Therefore, the "Designers' Operating Criteria" includes a requirement that the upper level system must not be operated when the reservoir water surface is lower than elevation 1120.0. If the reservoir water surface rises above elevation 1210.0 during flood conditions, all outlet works guard and regulating gates are to be operated in the fully open position until the reservoir water surface recedes to elevation 1210.0.

238. Outlet Works Intake Structure. The outlet works (lower level) intake structure is a reinforcedconcrete box type with metal trashracks and stoplog slots, as shown on figure 182.

Two 9-foot-wide by 19. 56-foot-high bulkheads are provided for temporarily sealing off the outlet works tunnel to reservoir water for inspection, maintenance, and repair of the guard gates. The bulkheads are to be raised or lowered only under conditions of balanced pressure with no flow through the tunnel.

239. Upper Level System Intake Structure. The upper level system intake structure is a reinforcedconcrete drop-inlet type with metal trashrack, as shown on figure 185.

A reinforced-concrete bulkhead is provided for unwatering the tunnel and shaft. Normally, the bulkhead will be in the raised position, supported on seats in the intake structure columns. In the raised position, the bulkhead should be secured in place with treated wooden blocks and stainless steel rods at each support, as shown on figure 185.

(a) Water Temperature Blending for Downstream Releases. --It was desirable that facilities be included in the outlet works design to permit temperature control of the regulated releases into Clear Creek for the enhancement of salmon and steelhead fisheries. For optimum spawning conditions, the water temperature should approximate 55° F. during the autumn spawning season, September through December. By combining suitable proportions of releases from two levels--elevation 972.0 for the outlet works (lower level) intake structure and elevation 1111.0 for the upper level system intake structure--the desired temperature can be achieved. The warmest water will rise and can be withdrawn through a high level outlet during the period from January through August. Colder water lying between the levels of the two outlets can be retained for withdrawal through the low level outlet after the beginning of the autumn spawning season.

240. Steel Outlet Pipes. For plan, elevation, and details of the steel outlet pipes, see figure 187. The pressure tunnel from the outlet works (lower level) intake structure terminates at the gate chamber; and two 45-inch-diameter steel outlet pipes extend downstream from two outlet guard gates in the gate chamber, about 723 feet to two regulating gates in the control house. (See sec. 241.) A short 45-inch-diameter steel branch pipe connects the upper level tunnel to a third outlet guard gate in the gate chamber and conveys water from the upper system into the right steel outlet pipe. A 14-inch-diameter steel discharge pipe branches from the right steel outlet pipe near its terminus and discharges downstream from the control house.

241. Outlet Gates and Controls. As previously indicated, five 2.75- by 3.75-foot outlet gates with controls are installed in the outlet works. The three gates located in the gate chamber serve as guard gates to shut off the flow through the outlet works in an emergency or for inspection, maintenance, or repair of the regulating gates or steel outlet pipes. Two of the three guard gates are connected to the right, or No. 2, outlet pipe in such a manner as to permit selection of the water intake elevation to control the temperature of the water released from the reservoir. The No. 2 guard gate connects the lower level intake to the right outlet pipe; and the No. 3 guard gate connects the upper level intake to the same outlet pipe. The No. 1 guard gate connects the lower level intake to the No. 1, or left, outlet pipe.

Two 2.75- by 3.75-foot gates with controls are located in the control house at the downstream ends of the outlet pipes and are used for regulating the flows through the respective outlets.

Some of the installation and assembly details are shown on figure 188.

242. 10-Inch Jet-Flow Gate Valve. A 10-inch jet-flow gate regulates the flow of water through the outlet works when the discharge requirements are less than can be satisfactorily controlled by the 2.75- by 3.75-foot outlet (regulating) gates. A jet-flow gate was required because of its dependable regulating

characteristics.

The jet-flow gate is located at the discharge end of a 12-inch outlet pipe (a downstream extension of the 14-inch steel discharge pipe discussed in section 240) in the outlet works control house, as shown on figure 185. Some of the details of the installation are shown on figure 189. A 12-inch gate valve, which will be used for servicing or for emergency closure, is installed immediately upstream from the jet-flow gate. The jet-flow gate is supported on a steel base and is located near the downstream wall of the outlet house. The valve will discharge into a 16-inch outlet pipe to pass the water through the outlet works control house wall into the river channel.

243. Flowmeters. The flowmeters are used to measure the flow of water through the outlet works. One meter is installed in each of the two 45-inch outlet pipes at station 11+11.00, as indicated on figure 187, and one meter is installed in the 14-inch outside-diameter discharge line at station 17+63. 47 in the control house, as shown on figure 184.

244. Gate Chamber and Tunnel Ventilation System. A forced-air ventilation system provides fresh air to the gate chamber and the tunnel. Principal equipment in the system to provide fresh air are an inlet louver in the control house wall, an electric motor-driven fan unit mounted on the wall adjacent to the inlet louver, a 22-inch outside-diameter pipe extending from the fan discharge to the upstream end of the 19-footdiameter tunnel where it reduces to a 10-inch outside-diameter pipe which terminates in the gate chamber. Two 20-inch outside-diameter pipes branching from the 22-inch pipe terminate at blast gates in the tunnel. At the downstream tunnel end, adjacent to the control house, an air shaft equipped with manually operable louvers provides passage for return airflow from the tunnel to the outside.

245. Reservoir Level Gage. The inlet for the reservoir level gage for Whiskeytown Reservoir is located at elevation 1091.25 on the left side of the intake structure for Spring Creek Power Conduit. The intake structure is in Whiskeytown Reservoir approximately a mile and a guarter northeast of Whiskeytown Dam.

A 1-1/4-inch copper tube, protected by a 2-inch standard pipe embedded in concrete, runs from the inlet to the bottom of the gate shaft, where the line emerges and is connected to the bottom of the floatwell. The 20-inch-outside-diameter steel pipe well rests on the bottom of the shaft and rises to elevation 1234. 54. A table at the top of the well is provided to support the recording and transmitting instruments, and a platform is provided for access to the instruments. These instruments were furnished by Leupold and Stevens Instruments, Inc., under invitation No. (H) 33, 465-A. Whiskeytown Reservoir levels are transmitted to Keswick Powerplant.

246. Electrical Service. A 3-phase, 120/240-volt, 60-cycle, 4-wire (grounded-neutral) circuit, energized from the distribution system of a commercial power company, supplies electric service to the outlet works structures. Lighting service is 120/240 volts, single-phase, 3-wire (grounded-neutral), and power service for operation of motors is 240 volts, 3-phase. The service circuit extends to a main fused disconnect switch and control board installed outdoors near the control house.

247. Grounding System. The basic ground electrode for the grounding system consists of a length of No. 4 A. W. G. bare cooper wire buried adjacent to the control house structure. Conduit systems and metal enclosures containing electrical equipment and devices in the control house are connected to the grounding system with the intended purpose of conducting static charges or accumulations to ground and to limit maximum potential of circuits to ground due to application of normal operating voltages to such circuits.

248. Outlet Works Lighting System. Lighting fixtures and outlets and convenience outlets are provided in the control house, the control house substructure region, the outlet tunnel, and the gate chamber. The lighting convenience outlet circuits originate and emanate from the lighting distribution panel in the control house.