and a ground wire encased in concrete. A total of 252 feet of 2-inch galvanized metal conduit, 84 feet of 2-1/2-inch galvanized metal conduit, and 80 feet of No. 4 A. W. G. stranded copper conductor was used in the construction of this bank.

4. Mechanical Installations

382. Metalwork for Powerplant Superstructure. The structural steel was furnished and installed under schedule No. 1, item 22 of specifications No. DC-5320. The installation extends upward from elevation 1928.00.

Column anchor bolt installation was started in February of 1961, and continued through April. The first column baseplate was set in July. The rocker bearing areas at the column tops were not within specification tolerances; however, the manufacturer performed corrective work at the railhead in Redding prior to delivering the columns to the jobsite.

After the column installation, the rocker shims were adjusted to allow the crane girder no more than the implied tolerance. Since neither the specifications or drawings noted a tolerance from a constant elevation, the tolerance was reduced to the thickness of the thinnest shim (No. 22 gage) supplied.

The general fabrication was good, with reasonably good hole alinement. During the leveling of the crane girder, the roof purlins and cross members were added.

Columns within lines 3b through 7b, inclusive, were painted with a fire-retardant paint. This area is adjacent to the transformer deck. The galvanized siding has a zinc content of over 1 ounce per square foot. One coat of primer and one finish coat were applied to the exterior only.

383. Metal Pipe and Fittings. Pipe installation started in November of 1960 with the draft tube unwatering line. This unwatering line was a bell-and-spigot jointed, 14-inch-diameter, AWWA cast-iron pipe. To assure tight joints the contractor was requested to use angle iron supports at each unsupported joint. The line was installed progressively as each concrete placement was made. Testing was also progressive, following each installation and preceding embedment. Test pressure was a minimum of 30 pounds per square inch. The draft tube unwatering pipe construction was typical of the bell-and-spigot embedded lines installed under this contract.

The various piezometer lines were tested at a minimum pressure of 50 pounds per square inch, which pressure was maintained during embedment of the lines. One piezometer line in placement 5c was found to have moved during the placement and corrective action was taken.

Plumbing to the septic tank from the sewage ejector area was installed under this contract. The short section of pipe for the 24-inch emergency drain was embedded in February. The butterfly valve and the flap valve for the emergency drain were first prime painted and then installed late in October.

Installation of drain piping from the roof was started in October and given a final test in mid-November. The test was performed by plugging the lower end of the discharge line and filling the lines with water.

384. Miscellaneous Metalwork. Most of the items of metalwork were bolt-on installations such as the draft tube bulkhead gate guides, roof hatches, hatch frames, and drain gratings. In instances where close tolerances were required, such as the bulkhead gate guides, the installation was adjusted to the necessary standards and then grout was placed around the installation in a blockout provided.

The inserts for the cable trays were formed with the overhead placements and followed the concrete tolerances. The hangers used to support the cable trays were nonadjustable and required shimming to bring the cable trays back to their required tolerances.

385. Installation of Oil Storage Tanks. Four oil storage tanks were supplied under invitation No. DS-5333 by McCulloch and Sons of Portland, Oreg. The installation was performed under specifications No. DC-5320. Two 13, 000-gallon tanks were installed for governor and lubricating oil.

The oil storage tank installation began February 16, 1961, and was completed February 20, except for leveling and paint repair. The paint had been damaged during handling and installation. This repair was made by the contractor at no expense to the Government. After the internal finish was repaired, the tanks were vacuum cleaned and wiped with an oil-dampened cloth. All fittings on the tanks were closed with blind flanges until suitable piping could be installed by the completion contractor.

Leveling of the tanks was accomplished on August 21, 1961. Bolts set in expansion anchors were used to fasten the tanks to the floor.

386. Installation of the Draft Tube Bulkhead Gates, Seats, Guides, and Lifting Frame. The supply contract for the draft tube gates, seats, guides, and lifting frame was awarded to Gate City Steel Inc., of Boise, Idaho. The rubber seals for the bulkhead gates were supplied by H. K. Porter Co., Inc., of Pittsburgh, Calif. The rubber seal had to be cut, fitted, and installed in the field by the installation contractor.

The six 8.98-foot-wide by 10. 5-foot-high bulkhead gates, seats, guides, and lifting frame were installed at Trinity Powerplant under items 40, 41, and 43 of specifications No. DC-5320.

The seats and guides for the six bulkhead gates were delivered in 10 segments each. The segments for each gate were bolted in position on the anchor bolts previously embedded in the blockouts, in the gate slots, on the downstream face of the powerplant (see fig. 274).

Figure 274. --Structural-steel framework for Trinity Powerplant. Penstock header can be seen immediately

behind the powerplant. TD-8736-CV, August 30, 1961.

On June 19, 1961, the contractor began installation work on the bulkhead gate seats and guides. After all segments of the seats and guides were supported on the anchor bolts, plumblines were offset from each seat and guides were positioned on survey points set by Bureau personnel. During the bolting-up operations by the contractor, a constant check of alinement was made by contractor and Bureau personnel. All plumb and level checks of the seats and guides were held to within 1/64 inch. It was noted during alinement of the guide segments that openings and offsets were prevalent at the joints of the segments. The installation contractor welded the segments together and ground them smooth, to eliminate the possibility of the guide lugs on the gates from hanging up during opening and closing operations. On September 12, 1961, the contractor completed installation and alinement of the draft tube gate seats and guides.

On September 21, 1961, the contractor began work on fitting, drilling, and bolting the rubber seals to the draft tube gates. The rubber seals were fitted to each gate, marked and placed in a wooden jig to hold the rubber in position for drilling. After drilling, the seals were bolted in place by means of seal clamps, then checked for fit. This operation was completed September 28. On September 22, 1961, the painting subcontractor for Guy F. Atkinson, R. W. Reade Co., began sandblasting and painting the bulkhead gates. The sandblasting and painting operations were coordinated with the installation of the rubber seals in order that proper precautions could be taken to insure that no damage would be done to the seals or machined surfaces. On October 2, 1961, all painting of the bulkhead gates including seats and guides was completed.

October 3, 1961, all six bulkhead gates were stored on the gate latches in preparation for testing. On October 6, each gate was lowered and raised through several full ranges of travel. All phases of the operational testing were completed satisfactorily.

Owing to the condition of the tailrace and the contractor's operations in that area, no tests for leakage could be made at this time. All six gates were left in the raised position on the latches in order to protect the rubber seals from the sunlight, until a leakage test could be accomplished. To accomplish the final testing, the draft tube bulkhead gates were placed in the closed position and the tail race was allowed to flood. At this time an inspection was made to determine the leakage past the seals. No excessive leakage was encountered during the testing. See section 123 for gate design information.

387. Installation of Draft Tube Bulkhead Gate Hoist. The draft tube bulkhead gate hoist was manufactured by Wright Hoist Division of American Chain and Cable Co., Inc., and was furnished and installed by the contractor under item 42 of specifications No. DC-5320.

On September 29, 1961, the 4-ton bulkhead gate hoist was checked for oil, cable connections, and general overall condition. At this time the hoist was set in place on the monorail. After several operations through full travel with no load, the hoist was ready for operation. On October 6, 1961, the gate hoist was used for testing the operation of the draft tube bulkhead gates. During the testing of the bulkhead gates, the hoist proved to be mechanically satisfactory. See section 137 for hoist design information.

388. 300-Ton Crane Installation. The 300-ton crane for Trinity Powerplant was supplied under invitation No. DS-5383 by Star Iron and Steel Co. of Tacoma, Wash. The unit consisted of a 300-ton-capacity bridge, one 150-ton-capacity hoist, and one 25-ton-capacity hoist. The 300-ton capacity is developed by the addition of a second transferable 150-ton trolley (see sec. 136). Delivery was made by rail on August 29, 1961. Guy F. Atkinson Co. performed the installation under specifications No. DC-5320 beginning in Sep

tember of 1961.

The bridge was shipped in sections and assembled prior to placing on the rails. The assembly was made at the jobsite. All mechanical installations were completed by November 28, 1961. Acceptance testing was performed on November 1, 2, and 3, of 1961, with both the Bureau's and manufacturer's personnel in attendance.

The completion contractor utilized the bridge crane throughout his operations with no significant problems or adverse effect upon the crane. The stops for the trolley were modified by the completion contractor under a purchase order. This modification was made to allow the generator air circuit breaker to be handled without drifting. Two 15-ton-capacity electric hoists were supplied for mounting on the roof to handle the trolley transfer.

C. Construction Operations for Trinity Powerplant--Completion Contract

(Specifications No. DC-5640)

389. General. Work under the completion contract included principally installing the penstocks; completing and finishing the powerplant structure; installing butterfly valves, hydraulic turbines, governors, and accessory hydraulic equipment; furnishing and installing all electrical equipment and accessories except generators; and other work as listed in section 362.

1. Penstocks and Butterfly Valves

390. Steel Penstocks and Piezometer Piping. (a) Installation. --The penstocks were supplied under invitation No. DS-5334 by U.S. Steel Consolidated Western of San Francisco, Calif., and were installed under specifications No. DC-5640 by Gunther-Shirley-Lane, the completion contractor. The following items were included in the contract:

The penstocks (fig. 275) were designed to operate under a static head of 483 feet. The penstock sections were delivered to the Trinity Dam pipeyard where they were sandblasted, painted, and wrapped, August 23 through September 15, 1962.

Installation of the penstocks began January 17, 1963, with the placement of the spool (P-1) section in position on unit 2 spiral case. The spool sections were lowered into the butterfly rooms through the hatch openings in the transformer deck with a 30-ton crane. They were set on cribbing and pulled into position with "come-alongs. 11 Once the flanges were alined, the flange bolts were tightened until they were stretched about 0.0085 inch.

At this time the butterfly valves were assembled and moved into position for bolting to the spool sections. When the flanges were alined to within about 0.005 inch, the flange bolts were tightened. The expander sections were also lowered into position through the transformer deck hatch openings with the 30-ton crane.

Starting at the powerplant end and working upstream, each section of the penstock was lowered into position by using the 35- and 40-ton cranes in tandem. The final section, which was to be coupled to the header, was made a specified amount longer than drawing dimensions. It was trimmed to exact length just prior to being lowered in place.

The sleeve-type couplings were not made up until all sections were in place. When the final torque was completed, the penstock was filled and pressurized in order to check for leaks. The piezometer plugs were not tapped clear through. By observing a pressure gage in each line, a leak could be indicated by a pressure drop. The pressure was held throughout backfilling.

When it was determined that there were no leaks in the sleeve-type couplings or the piezometer piping, the couplings to be buried were enameled and wrapped, in accordance with specifications No. DC-5640.

The preceding procedure was essentially the same for both penstocks. Installations were completed June 7, 1963.

(b) Field Problems. --The pipe stops on the middle ring of the sleeve-type coupling located between the expander section and the first section of penstock, had to be removed. This was necessary in order to allow disassembly of the butterfly valves after the penstock was buried. In order to remove the expander section, the middle ring of the coupling had to be moved clear of the joint between the expander and the straight pipe section.

A spider jacking tool was fabricated to assist in rounding the ends of the penstock section. Figure 276 shows the spider being used.

Piezometer plugs in some cases were not perpendicular to the penstock centerline and consequently leaked. Consideration was given to correcting this by grinding the penstock surface to give full face contact between it and the plug head. It was decided that this operation might weaken the penstock beyond the limit of safety. Accordingly, the plugs were removed, the holes reamed out in proper position, and the plugs reinserted, welded, and peened all around.

391. Butterfly Valves. (a) Installation. --One 158-inch butterfly valve is installed upstream of each turbine (sec. 122). These valves are used to shut off the flow of water when the unit is taken out of service, during inspection or repair of portions of the conduit downstream of the butterfly valves, or for emergency shutdown.