Figure 215. --Spring Creek Powerplant steel penstocks, station 170+05. 00 to station 174+53. 24--Alinement and profile. Penstock Figure 216. --Spring Creek Powerplant steel penstocks, station 174+53. 24 to station 180+23. 06--Alinement and profile. PENSTOCK NO. 2 PENSTOCK NO. 1 410-030-6 Sta 180+23.06 EI. 651.87 650 CPM DEPARTMENT OF THE INTERIOR ALINEMENT AND PROFILE Anchor No. 7 (905) Figure 217. --Spring Creek Powerplant steel penstocks, station 180+23.06 to end of penstocks--Alinement and profile. The wye branch is provided with a 12-inch drain. The valves for the drain are located in the penstock valve structure. The water drains into a concrete box below anchor No. 2 and then into the concrete drainage ditch. The exposed portions of the penstocks are supported on concrete piers spaced approximately 40 feet apart. The penstock sections are connected by sleeve-type couplings and each section is supported by one fixed ring support and one sliding ring support. The sliding ring supports and the sleeve-type couplings provide for the expansion and contraction due to temperature changes. Portions of the penstocks below anchor No. 7 are installed with sleeve-type couplings and encased in concrete. The penstocks from the midpoint of the encasement to the powerplant are buried and are installed with sleeve-type couplings. Seven manholes on each penstock provide access at various locations. 265. Hydraulic Considerations. The maximum hydraulic gradient, including water hammer, varies linearly from elevation 1234 at the surge tank, to elevation 1500 at the centerline of the generating units. The water hammer was computed using a turbine wicket gate closure time of 10 seconds from the full open position. 5. Mechanical and Electrical Installations 266. Intake Structure Trashracks. (a) General Description. --Sixty trashracks are installed in the intake structure to protect the 11- by 18.5-foot fixed-wheel gate from oversize trash. The trashrack sections, approximately 11 feet 1 inch wide by 9 feet 8 inches high, were furnished under specifications No. DC-5294. The trashracks are installed in vertical slots of the intake structure. The racks consist of 2- by 5/8-inch trash bars supported by 10- by 1/4-inch horizontal load-carrying members which in turn transmit the load to the side members. The 4-inch clear opening between trash bars is considered sufficient protection for the fixed-wheel gates. The estimated weight of the 60 trashracks is 312, 000 pounds. (b) Design. --The trashracks were designed for a differential head of 40 feet at a stress of 33,000 pounds per square inch. 267. 11- by 18.5-Foot Fixed-Wheel Gate. (a) Requirement. --One 11- by 18.5-foot fixed-wheel gate, located in the gate shaft of the Clear Creek Power Conduit, is provided for emergency closure of the power conduit in case of damage to the conduit or the associated powerplant equipment, and also to permit unwatering of the conduit for inspection and maintenance purposes. In normal operation the gate will be closed only after flow through the conduit has been stopped by closing the turbine wicket gates; however, in an emergency, the gate may be closed with water at full reservoir head flowing through the conduit. Except for opening the gate about 6 inches to backfill the conduit, the gate should only be opened under balanced head, no-flow conditions. The gate is operated by a hydraulic hoist located near the top of the gate shaft. (b) General Description. --The general arrangement and some details of the gate installation are shown on figure 218. The nominal gate size of 11 feet wide by 18.5 feet high represents the size of the gate opening in the conduit at the gate shaft. The gate normally operates in a vertical slot formed in the concrete, which extends from the gate sill to the service deck. The gate is a flat structural-steel member consisting of a skinplate on the upstream side of beams which are fastened together with rivets and ribbed bolts. Šix horizontal beams frame into double vertical beams at each end. The gate was fabricated in three units for ease of shipment and field erection. The overall gate leaf is 16 feet 3-3/4 inches wide by 19 feet 7/8 inch high. Seven wheels on each side of the gate transfer the hydrostatic load from the gate to tracks attached to bases embedded in the downstream face of the gate slot. Two guideshoes on each end of the gate contact guides which are embedded in concrete at each end of the gate slot. These shoes center the gate laterally whenever the gate is relieved of the hydrostatic load. The guides and the tracks extend high enough above the gate opening to permit contact with the gate at the top of its travel during the opening cycle. The normal gate travel is 19 feet. Solid-rubber, double-stem, brass-clad seals are fastened across the top and on each side of the upstream face of the skinplate. Hydrostatic pressure is admitted behind the top and side seals. When the gate is closed, these seals contact plates attached to bases embedded in the upstream face of the gate slot. A solid-rubber, round-nose flat Seal is used across the bottom of the gate. The bottom seal contacts the bottom seal seat which is attached to the base embedded in the concrete conduit floor. A single hoist stem connection is located on the gate directly above the approximate center of gravity of the gate. The estimated weight of the gate is 91, 000 pounds, and that of the frames and embedded metal is 30,000 pounds. The estimated maximum hoisting effort is 186, 000 pounds. (c) Gate Design. --The gate was designed for a head of 145 feet acting uniformly over the gate leaf. The hoist connection was designed for the maximum hoist load at the gate. Friction forces of the wheels, pins, seals, etc., which resist vertical gate movement, were investigated to determine that the gate had sufficient weight to close by gravity under a design head of 145 feet. |