Figure 97. —Upper part of main outlet works intake structure. Trashracks are partially installed and the elliptical bulkhead is being installed at the top of the structure using a 60-ton high-lift crane. P711-422-973, January 18, 1961.

Figure 99. —72-inch hollow-jet valve as seen from downstream end. P711-D-47162.

Figure 100. —72-inch ring-follower gate hoist cylinder. P711-422-1642, February 27, 1963. control piping holes in the cylinder had rotted and allowed sand and dirt to enter the oil chambers.

The hollow-jet valves did not function during the first trial run, and it was found that the restrictor valve in the return line was not open enough to permit a return flow of oil. After adjustment was made on the restrictor valve, the hollow-jet valves opened and closed satisfactorily, although the opening time was considerably longer than the design estimate of 6 to 9 minutes. No leakage was detected during the water leakage test.

The gasket grooves around the top of the 72-inch ring-follower gate bodies were irregular in depth and width, and the groove in the left gate required both grinding and filling to bring it within specifications requirements. The erection contractor made the repairs in the field by grinding and using a commercial plastic compound to fill the depressions. After assembly, the ring-follower gates operated smoothly and opened and closed in normal time—approximately 8 minutes one way. The seals on the ring-follower gates checked out under the specified 0. 005-inch tolerance, and leakage was negligible during the water leakage test.

The control system for the 72-inch valves and gates was found to hold approximately 800 gallons of oil instead of the 500 gallons listed in the control data.

148. 30-Inch Ring-Follower Gate and 30-Inch Hollow-Jet Valve. One 30-inch ringfollower gate and one 30-inch hollow-jet valve (fig. 101) were installed in the control house during the early part of 1963. The ring-foHower gate was supplied by the Charles C. Steward Machine Co., Birmingham, Ala., under invitation No. DS-5439. The hollow-jet valve was supplied by Pacific Coast Engineering Co., Alameda, Calif., under invitation No. DS-5472. The hollow-jet valve is used to control the normal flow of the San Juan River, and the ring-follower gate is used to shut off the flow to the hollow-jet valve when it is taken out of operation for maintenance or repair.

During filling of the 30-inch system for the trial run, the hollow-jet valve would not open under the normal pressure of 500 pounds per square inch and the relief valve which limits the opening pressure was somewhat erratic in its operation. Cleaning of the relief valve corrected its malfunction, but the hollow-jet valve still required a pressure of 600 pounds per square inch to function properly. There was no leakage during the leakage test. The ring-follower gate operated smoothly and leakage was negligible during the water leakage test.

149. Hydraulic Control Systems. Four hydraulic control systems were installed at Navaje-49amior-operating, the. valves and.gates. The..control cabinet located orTth'e operating-floor-of the outlet works valve house operates the two 72-inch hollow-jet~vaTves and the two 72-inch ring-follower gates; one control cabinet lbcaled-dh. the'operating-ffoor of the control house for the SO-tnch-hollow^'-emralve will.ciperaiejhe 30-inch hollow-jet valve and the 30-inch ring-follower gatej. one. qabineJ-located in the. gate chamber "oijjj^jiixiliary outlet works will operate the 4- by 4-foot tandem outlet gate; and one control cabinet located in the hoist house at the top 6F.th.e-gate .shaft of the main outlet works will, operate the hoist'for the 6- by 13-foot fixed-wheel gate. The..cQHtrol systems includeCihe cabinets], oil tanks; all pipe, fittings, valves, and supports between the cabinets and the operating cylinders] and hydraulic75.il toF the systems.

The control for the 4- by 4-foot tandem outlet gate was received August 22, 1961. Installation ,started"Tn' August 1962 and was completed in-DeceirQie£l9.6^r^^6'^nrfpls for the 72-inch hollow-jet valves and 72-inch ring-follower gates were shipped on December 19, 1961. The controls required some modification^'by-ihe-addition,at^S^inch tubing.and 1/4-inch check valves before they could be installed. This.work-was-performed by the construction'contractor under order -for changes No.- 4-4e~specificatiQcs..No^.D.C5056 and backcharged to the supply contractor. The installation of these controls was completed in February 1963.

The controls for the 30 -inch ring-follower gate and 30-inch hollow-jet valve were shipped on November 2, 1961, and installed in March--1363. The controls for. the 6_-by 13-foot fixed-wheel gate and hoist were shipped on January 5, 1962, and installed irf January 1963.

150. Outlet Pipe and Walkway. The outlet pipe, located in the main outlet works tunnel downstream from the gate shaft, was supplied by the Eaton Metal Products Co. of Salt Lake City, Utah, under invitation No. DS-5280. This feature consisted of a 110-inchdiameter steel pipe ranging in thickness from 13/16 inch to 1-1/16 inches. It was manufactured in 40-foot lengths, coupled by sleeve-type couplings, and set on concrete pipe supports at 40-foot intervals. The extreme downstream end of the 110-inch pipe branches off into a wye section. Each branch of this wye section is 72 inches in diameter and contains a 72-inch ring-follower gate and 72-inch hollow-jet valve. Immediately upstream from the wye branch, a 110-inch-diameter capped stub projects out to the left approximately 18 feet for possible future power development (see fig. 102). Immediately upstream from the stub 110-inch pipe, a 30-inch-diameter pipe projects to the right and continues to the left spillway wall where it connects to the 30-mch ring-follower gate and 30-inch hollow-jet valve in the control house. The 30-inch outlet will be used for normal releases. A 3-foot 6-inch wide steel walkway parallels the 110-inch pipe for access through the pipe portion of the main tunnel.

The pipe manufacturer delivered the pipe to the jobsite where it was stored in the contractor's supply yard until ready for installation. The pipe was installed in the tunnel starting at the gate shaft, and work progressed downstream. Only minor difficulty was encountered in the installation. The installation was started in August 1962 and completed in December 1962. The total weight of the pipe installed was 1, 495, 846 pounds, including pipe supports and the walkway.

151. Ice-Prevention Air System. The ice-prevention air system consists of an air compressor set in the tunnel access house and a system of 1-1/2-inch piping leading through the main tunnel up through the intake structure to a system of air outlet nozzles, one set at elevation 5882 and the other set at elevation 5980 of the trashrack area.

The ice-prevention air system was supplied by the Spitzley Rettenmeir Sheet Metal Co., of Detroit, Mich., under invitation No. DS-5118. Installation progressed simultaneously

with the concrete work in the intake structure and the main tunnel. Upstream from the gate chamber, the piping consisted of 1-1/2-inch copper tubing embedded in concrete. Downstream from the gate chamber, the piping consisted of 1-1/2-inch standard galvanized pipe suspended by brackets near the crown of the tunnel arch.

152. Ventilating Systems. The ventilating systems were supplied by the Singleton Sheet Metal Co., of Pueblo, Colo., under invitation No. DS-5118. Installation was accomplished at the various locations as concrete work was completed.

One ventilating system is located in the drainage gallery adit and access house. The fan unit is located in the gallery access house on the spillway wall, and supplies air to a 10-inch-diameter galvanized-pipe system terminating approximately 10 feet up the drainage gallery on the spillway centerline near the bottom of the gallery.

The other system is in the main outlet works tunnel, access tunnels, and gate chambers. A 26-inch-diameter galvanized-pipe system starts with a fan unit at the tunnel access house and ends near the downstream side of the main tunnel gate chamber. An auxiliary to this system consists of a fan unit set at station 11+12 in the main tunnel which feeds a 9-inch-diameter galvanized-pipe system which traverses the access tunnels and access shaft leading to the main tunnel gate chamber and the auxiliary tunnel gate chamber.

153. Reservoir Level Recorder and Floatwell. The 20-inch-diameter floatwell pipe was supplied by the American Steel and Iron Works of Denver, Colo.; the 1-1/4-inch copper tubing and 2-inch standard black pipe by the Mine and Smelter Supply Co., of Denver; and the recorder by the Arrow Iron and Machine Works of Seattle, Wash.

The installation consists of an inlet at elevation 5879. 5 of the main outlet works intake structure, 1-1/4-inch copper tubing encased in 2-inch black pipe, all embedded in concrete. The system extends down through the intake structure, through the main tunnel