THE POWER PLANT AT THE GRAND COULEE DAM
Introduction
Dams on the Columbia
Capacity
River Regulation
Features of the Dam
Contents
Page 1 1 1 1 1
Drum Gates
Penstocks
The Powerhouse
Turbines
Scroll Cases
Wicket Gates
Runner
Shafts
Guide Bearings
Thrust Bearing
Governors
Generators
Transformers
Lightning Arresters
Electric Grounding System
Control System
3
3
3
3
3
4 4 4
5-7
7
8 8 8
Station Power
Transportation and Handling Facilities
Lighting
Heating and Ventilation
Oil, Air, and Water Service
Energy Available
Irrigation and Pumping
Personnel
9
9
10
10
10
11
11
11
Bureau of Reclamation
Coulee Dam, Wash.
GOVERNMENT PUBLICATIONS UNIV. OF WASH. LIBRARIES
U.S. DEPOSITORY COPY\
introduction
The biggest hydro-electric generating set ever built has just begun to deliver power from the Grand Goalee Dam to defense industries on the Bonneville-Grand Coulee power distributing system in the Pacific Northwest. An identical unit will go on the line during the winter, and another in the spring. Three more, already ordered, are to be added within the next two years.
Dams on the Colombia
The Grand Coulee Dam is the uppermost of ten dams by means of which it is proposed to develop 92 per cent of the fall of the Columbia River between tho Canadian border and the sea. Bonneville, at the head of tidewater, is the lowermost. Between them, only ono damsite is developed, that at Rock Island, near Wenatchee, "Washington, where the Puget Sound Power and Light Company has a plant in operation.
Capacity
’.then finished, the paver plant at Coulee Dam will be the biggest in the world, housing eighteen generators of IOS,000 kw. capacity and three station-service units of 12,500 kv—a. rating, Two of the latter have been in operation since March 1941, delivering power to the Bonneville transmission system end carrying the local load of Bureau of Reclamation activities. Power for construction was obtained by the contractors from the Washington Yfater Power Company over a 30-mile line, tapping the power company’s cross-stale line near Coulee City.
River Regulation
In addition to furnishing more power than any of the projected dams below it on the Columbia, the Grand Coulee Dam will store water, to bo released during the low ’water season of winter, and will thus double the firm power capacity of other plants above the mouth of tho Snake River, and increase by half the firm power capacity of plants below that point. There will be no drawdom of the reservoir on account of the irrigation of 1,200,OCX) acres of land, to be accomplished during the next 25 to 50 years, because the high water and irrigation seasons are coincident.
Features of the Dam
The dam is of the gravity type with a 1650-foot central spillway section flanked by powerhouse and abutment sections 1200 to 1500 feet long. At the foot of the spillway, below the level of tho river channel, is a ’’bucket” or artificial plunge-pool, 90 feet wide and 30 feet deep, with its downstream edge submerged 30 to 75 feet, depending upon the river’s flow.
iDrum Gatos
Over cloven drum gates, each spanned by a 135-foot reinforced concrete highway bridge at the crest of the dam, and into this bucket will plunge the entire flow of the river, less water diverted through the powerhouses or future pumping plant. By means of controlling floats, the drum
gates will be caused to rise and fall automatically, as the river flow varies, to maintain the reservoir surface at elevation 1290. Sixty 8y-foot conduits through the dam make it possible to drain the reservoir.
Penstocks
The bases of the two powerhouses were built under the contract which covered the construction of the base of the dam. Under the contract for the completion of the dam, the 'west powerhouse was completed, and all penstocks for both powerhouses were installed. They are 18-foot steel tubes embedded in the concrete of the dam, ranging in thickness from 3/4 to 1| inches, with centerlines of inlets at elevation 1041, and with connections to turbine scroll cases at elevation 933. Each was installed vrith a hemispherical bulkhead at its upper end, to bo burned out as the turbines are installed. The stream-lined entrances to the penstocks are rectangular, so as to limit to reasonable dimensions the spans of the 115-ton, 15- x 30-foot "coaster” gates, 'with which they can be closed.
The Powerhouse
The powerhouse is a heavy reinforced concrete structure which actually consists of eleven buildings, separated by 1-inch, cork-filled expansion joints, extending from bedrock to the roof. Nine sections are to accommodate generating units, spaced 65 feet between centerlines. These,
'with an 85*-foot service bay, constitute the main powerhouse, which is adjoined by an 85~foot control bay, making a structure 84 foot wide and 785 feet long. The height, from the floors of the draft tubes at elevation 896 to the parapet of the control bay is 200 feet.
Turbines are set lew, with centerlines of their scroll cases at elevation 938, so as to reduce the vacuum and attendant difficulties to a minimum at low water seasons. The generator floor, at elevation 991, is 6 feet above the maximum flood-water stage reached since observations began in 1913; and the transformer deck, and the entrances to the perwerhouse (elevation 1012) arc 12 feet above the estimated flood line of 1894. The downstream powerhouse wall is designed to resist a head of 90 feet above the lerwest open gallery space, the floors and walls of the galleries acting as box girders, carrying the horizontal water-thrust to the massive walls between the turbine pits.
Transformer decks, at elevation 1012, are located between the dovrnstreom face of the dam and the upstream wall of the powerhouse, A concrete structure along the powerhouse wall houses the connections between generators and transformers. Beneath the deck is space for electrical
2equipment, control cables, conductors, step-down station-service transformers, distributing panels, and, in the left powerhouse, space for 13,800-volt conductors which will extend from the first six generators to motors in a pumping plant in the reservoir, at the left abutment.
Turbine s
The turbines, built by the Newport Mews Shipbuilding and Drydock Company, are of the Francis reaction type, rated 150,000 horsepower at 330 feet, the weighed averaged head, and 90,000 horsepower at 263 feet, the minimum head, at 120 rpm. An efficiency of 90 per cent is guaranteed at loads of 120,000 to 130,000 horsepower.
Scroll Cases
The 290-ton turbine scroll case consists of 14 steel castings, bolted together, and buried in reinforced concrete while under an internal hydraulic pressure of 145 psi. The scroll case diameter, normal to the entrance, is 51 feet 5b inches. Speed rings, integral with the scroll case, are stiffened by 14 fixed guide vanes.
V’ickct Gates
Each cf the 9-inch shafts of the 24 wicket gates is carried in three prcssure-grease-lubricated bronze bushed guide bearings, one in the curb plate below the speed ring, and two in the. crown plate, one above and one below a stuffing box. A shear pin in the gate operating levers protects each gate from injury in case its movement is obstructed: and eccentric pins provide means of adjusting and compensating for wear. Two large, double-
acting hydraulic cylinders, under control of the governor, operates the wicket gates.
Runner
The turbine runnel’ is a single steel casting, 16 feet 5 inches in diameter, ■with an entrance height of 34“3/3 inches, find with 19 vanes. Water, passing around the turbine casing at a speed of about 20 miles per hour (29 fps) enters the wheel at a velocity of about 53 mph., and leaves the draft tube at less than 5 mph.
Shafts
Shafts are 44-inches in diameter, with 6-inch axial holes for inspection, which servo, also, to admit air to any vacuum spaces within the turbine to reduce vibration and cavitation. An 18—foot section of the shaft, attached to the runner, and a 24~foot intermediate section were furnished by the turbine builder. The 31-foot upper section was made by the
3Westinghouse Electric and Manufacturing Company, the generator builders.
The sections are joined by means of 75-inch flanges, holes in the flanges being reamed and fitted with ground bolts, 25 to 50 ten-thousandths inch oversize. Bolts are shrunk by cooling in dry-ice before being put in place. They can be shrunk for removal by passing liquid air through axial holes in then, provided for that purpose.
Guide Bearings
Three guide bearings are provided, the heaviest located just above the turbine runner. It is a' split-shell babitted bearing, 4-5 inches In diameter and 41*2 inches long, sot in a tapered seat In the turbine body. Forced lubrication is provided, normally by an AC-notcr driven punp, but in emergencies from a DC-motor driven pump, vhich is operated from storage batteries, and is started automatically if the oil pressure falls.
A segmental guide bearing below the generator rotor runs In a bath of oil, cooled by water circulating through coiled copper pipe. The upper guide bearing consists of 20 segmental babbited shoes bearing against the edge of the thrust runner.
Thrust Bearing
The Kingsbury-type thrust bearing, designed to carry a gross load of 1300 tons at 400 pounds per square Inch of bearing surface, is mounted on the'upper generator bracket. It consists of an 8-foot cast iron thrust collar, attached to the end of the generator shaft by means of a steel hub, and 8 babbited steel thrust shoes supported on pivots. The thrust bearing and the upper guide bearing run in a bath of water-cooled oil.
Governors
The Woodward governors on the large turbines are of the so-called ’’actuator" type, that is, the' speed-responsive clement (fly-balls), the valves, the control mechanism, and the oil pressure pumps are in a unit separate from the hydraulic cylinders which operate the turbine gates (the servo-motors). There are three connections between a turbine and its actuator, (a) a three-phase circuit connecting a small synchronous motor, driving the speed—responsive element in the actuator, to a permanent-magnet generator on the main shaft, (b) the "restoring" or "compensating" connection, which returns the pilot valve to its normal position after a gate movement has brought the turbine to normal speed as a consequence of a change of load, and (c) the oil piping tlircugh which power to move the turbine gates is transmitted from the actuator to the servo-motor.
Within the actuator housing are the synchronous—motor—driven speed-responsive element, valves, rostering mechanism, and tvro 40-horsepower motor—driven oil pumps of sufficient capacity to operate the turbine gates through full range three times per minute. An external 250-pound pressure tank contains sufficient oil and compressed air to open or close the gates five times, independently of the oil pumps.
4The 400,000 foot-pound, double-acting servo-motors are of a capacity to move the wicket gates through their full stroke in 4 seconds, with oil pressure at 250 psi. and an operating head of 355 feet. Gate operating time is adjustable from 4 to 12 seconds.
A variation of 0.01 per cent in the speed of the turbine is sufficient to cause the speed-responsive element in the actuator to pass oil to the servo-motors, and shift the turbine gates.
Other devices embodied in the governor equipment are manually or electrically operated gate-limit, speed level, and starting and stopping controls, speed indicators, oil and air pressure gauges, overspeed switch, and speed-droop adjustment.
Brakes on the rotor, controlled from the governor cabinet, cannot be applied automatically until the turbine gates are closed and the speed has fallen to 30 rpm. The automatic braize action may be continuous or intermittent, as desired, with adjustable time intervals.
Generators
(Characteristics)
The Westinghouse generators are 3-phase, 60-cycle, 135800-volt, totally inclosed, air-cooled machines, rated 103,000 kv. at 100 deg. C. Inorganic insulation, suitable for an operating temperature of 120 deg. C. was specified, as a means of insuring overload capacity and long life.
In order to provide sufficient charging capacity and stability to enable a generator to energise a 250-mile 230,000-volt line, and to maintain synchronism if a double' line-to-ground fault at the end. of the line were cleared in 0.013 second, generators were required to have short-circuit ratios of 1.75 or more, and flywheel effects of not less than 150,000,000 pounds at a one-foot radius. Approximate normal values for direct-axis unsaturated transient reactance of not more than 30 per cent were specified.
Guaranteed efficiencies range to 97.4 per cent at full load.
?rom 93.4 at 25 per cent capacity
(Cooling)
Each generator is inclosed Air within the housing is circulated leaver rims of the rotor, discharging cores, and through eight openings in 2,625-so. ft. fin-tube cooler. With coolers will maintain the air within
within a housing 45 feet in diameter, by means of blowers on the upper and the air through gaps in the stator the stator frame, each covered by a cooling 'water at 25 deg. C., seven the generator at 40 deg. C.
(Stator Winding)
parallel,
St at or windings in each phase.
are connected 11 coils in scries and 12 groups in In each coil, there are five turns of laminated
5copper, transposed at coil connections. Insulation is'to withstand, between turns, a test voltage of 5,500 volts, crest value, and, between conductors and ground, 40,500 volts. Strands, conductors, and coils are insulated with impregnated mica tape, hot-pressed several times during manufacture to produce compact, homogeneous coils, free from air pockets. Asbestos tape, treated with a semi-conducting graphite suspension, to provide corona shielding, forms the outer protective coil covering.
(Connections)
The generator windings are star-connected, with a neutral lead brought out from each half of each phase, for the installation of a current transformer in each half of each phase. This arrangement provides for the connection of relays between these two neutral-lead current transformers, each carrying half the phase current, and the main-lead current transformers carrying the full current In the same phase, so as to detect failures of insulation between turns or betw-een phases. The neutrals are grounded through potential transformers, to vmich are connected relays to indicate the occurrence of any line-to-ground fault.
(Excitation)
power for the excitation of the 10S,000 low. generators is derived from motor-generator sets, driven by the station-service power plant, not from direct-connected exciter units. By this arrangement, a generator field can be excited before the generator is started, and a generator can thus bring up to speed, simultaneously, as it comes up to speed, two 65,000 horsepower synchronous puap motors, to which it will supply power at generator voltage. Mo circuit breakers or rheostats are provided in the main generator field circuits.
The field—exciter sets each consists of a 600 horsepower, 6,600-volt, 3—phase, 60—cycle synchronous motor, running 900 rpm., a 400 kw., 250-volt generator, and a direct-connected pilot-exciter, which supplies current to the fields of the motor and the generator. As an aid to generator stability, a maximum exciter voltage of 120 per cent normal, at full load, and a voltage-response ratio of not less than 0.5 were specified. A pullout torque of not less than 250 per cent of normal, and a pull-in torque of not less than 120 per cent, at normal voltage, was specified for the exciter motors, in order to assure sufficient torque to prevent loss of generator excitation on account of momentary drops in station-service voltage, such as might occur during a temporary fault on some other circuit energized from the same source.
(Stators)
The stator frames, 37 feet In diameter and 9 feet 9 inches high, were fabricated of welded steel plate, in quadrants, w-hichwere shipped with laminated cores complete, and with armature coils in place, except at joints. The stator frames were assembled and the windings were completed in a spare turbine pit in the powerhouse^ and with the upper bracket temporarily in place as stiffeners, they were set in place by means of two bridge cranes,
oStators weigh
each equipped with two 175-ton hooks, and two 30-ton hooks.
274 tons, and upper brackets weigh 160 tons, each.
Sole-plates for the stators, and lower brackets, supporting brake shoes and the intermediate guide bearings, were set accurately in the concrete piers on which the generators are carried. The air-operated brakes will bring the rotors from 25 rpm. to a stop in one minute. Substituting oil for air in the brakes, they become hydraulic jacks, by means of 'which the entire rotating load, rotor, shaft, and turbine runner, can be lifted to allow the adjustment or removal of a thrust bearing.
(Rotors)
The rotors were assembled on a heavy special fixture, set up in an unoccupied turbine pit. First, the 31-foot shaft was set up on an accurately leveled casting, which was machined to match the 75~inch flange on its lower end; and, after being heated by space heaters, hung inside the hub, to expend the bore 55-thousandths of an inch, the cast steel spider 'was lowered over the shaft, with a 6-inch by 9-inch key already in place.
Then, the laminated rim was built up to a vertical thickness of 79 inches by piling l/8-inch steel plates on accurately leveled castings arranged in a circle around the spider, and clamping them together with 1,080 through-bolts, l-l/4-inch in diameter. For the purpose of making a rigid radial connection between the rim and spider, the rim vras expanded by means of electric heaters mounted, under sheet asbestos, on its outer surface; and rectangular keys were driven in keyways in the ends of the spider arms.
The 60 field pole pieces, each weighing about 4,400 pounds, were mounted on the rotor rim by moans of dove-tail joints, spring pressure plates, and wedges.
A 65-ton structural steel equalizer has been provided for the purpose of lifting the 587-ton rotor, with the four 175-ton hooks of the two powerhouse bridge cranes.
Transformers
Each generator is to deliver its output'to transmission lines through a bank of throe single-phase, 36,000 kv-a. oil-immersed, water-cooled, inert-gas-filled, outdoor type transformers, with 13,800-volt, delta-connected primaries, and 230,000 or 115,000-volt, wye-connectcd secondaries. One bank of three transformers is provided with both 115,000 and 230,000-volt full capacity secondary windings. High-voltage neutrals may be grounded solidly or through reactance coils.
Transformers are located on a deck between the powerhouse and the downstream face of the dam, where provisions are made for moving them, on their own trucks and a transfer car, between their installed positions and the service bay in the powerhouse. Connections with generator loads are made by ITE inclosed, isolated-phase buses, passing through openings in the wall of a conductor-protecting structure along the upstream side of tho powerhouse.
7Transformers for the first three units were furnished by the Goner al Electric Company.
Lightning Arresters
Lightning arresters are supported on pedestals on the face of the dam. Steel structures spanning the transfer track carry both arrester disconnecting switches, and de-icing switches. In case spray from, the spill-v;ay waterfall causes ice to form on insulators and conductors which connect the generators with the switchyards, a circuit so affected can be cut off from its generator and from the switchyard buses, short-circuited at the switchyard, and connected by means of the de-icing switches to an unexcited station service unit. Building up the generator field will heat and relieve the ice-burdened circuit.
Electric Grounding System
Four mats of bare copper cables of 200,000 to 500,000 circular-mil section, one under each powerhouse and one under the riprap on each tailbay, provide ground connections for all electrical, equipment. Cables connect the ground mats to 750,000 circular-mil cables, which extend the length of the powerhouse and serve as main ground buses. Ground connections between plant equipment and the ground bus can be opened for testing purposes.
Control System
In addition to generator unit control stations, located in the governor gallery (elevation 951), for the starting of turbines, the indicating of loads and temperatures, and the automatic maintaining of voltage and frequency, a main control room occupies the greater part of the upper floor of the control building, situated at the west end of the powerhouse. From the control room, the principal circuit breakers arc operated, loads arc distributed among the generators, and voltages and frequency arc adjusted.
The equipment includes a frequency controller and a master clock for the automatic adjustment of frequency for system interconnections and as a moans of making electric clocks on the system reliable timekeepers. Arranged on opposite sides of the operators’ desks arc two bench—type control boards, one for the main generator sets and one for the station service units.
An automatic telephone exchange, installed in the control building by the Pacific Telephone and Telegraph Company, provides for communication between various parts of the power plants and with all other Bureau offices. Trunk lines connect the exchange with the Pacific Telephone and Telegraph system. An inter-communicating system, for emergency use, connects important points in the powerhouse; and a codc^call system, operable from, any automatic telephone station, can be used to call certain persons by means of audible signals distributed throughout the powerhouse. Carrier-current telephone equipment, operating over the transmission system, keeps the operating staff in touch with the load dispatcher of the Bonneville Power Administration.An extensive system of protective relays was provided. Relays for the generators and transformers are mounted on the unit control boards in the governor gallery (elevation 951), and relays for the transmission system were installed in the control bay of the powerhouse. In case of an electrical fault in a generator, circuit breakers are opened, turbine gates are closed, and carbon dioxide is released into the generator housing.
Annunciators at control stations show the occurrence and location of electrical troubles, abnormal temperature rises, and interruptions of oil and water circulation in vital lines.
An acid-type, 120-cell, storage battery furnishes energy for the operation of control and relay systems.
Station Power
The station-service power plant will. supply energy for light, power, and heat in the powerhouses, pumping plant, and dam, for public and domestic uses in the village, and for exciting the six large generators which will supply power to the pumping plant. The plant now includes two, and finally will include three generating units, each consisting of a 11,000 horsepower reaction-type turbine and a 12,500 kv-a., 60-cycle, 6,900-volt, three-phase generator, running 100 rpm.
The turbines, built by the Pelton Waterwheel Company, include cast steel scroll cases IS feet 5~3/4 inches outside width, normal to their 5-foot 1-inch entrances. Runners arc 53| inches in diameter, with 11-3/l-inch entrances. Turbine shafts are 11 inches in diameter. An efficiency of 90 per cent at 11,500 horsepower, under a 330-foot head, is guaranteed.
Facilities for the distribution of power at generator voltage include a double-bus, metal-clad switchgear assembly with withdrawal type oil circuit breakers. The 6,900-volt load consists of the exciters of six of the large generators, the power and lighting supply system of the dam, and the load of the nearby townsites. Other motor-driven equipment in the plant and the building heating system arc operated from 160-volt, 3-phase circuits provided with air circuit breakers and contactors and fed from transformers on the 6,900-volt system. An automatic contactor will start 250-volt D.C, auxiliaries provided at important points in case of failure of the A.O. power supply.
Transportation and Handling Facilities
Access to the powerhouse is provided by a hard-surfaced highway and a railroad spur, over either of which deliveries can be made to bridge cranes in the generator room. Each of the two double-trolley cranes is equipped with two 175-ton and two 30-ton heists. By means of structural steel equalizers, one crane can apply both its large hooks to a load, or the two cranes together can make an 875-ton gross lift, talcing advantage of their overload capacity.
nDeliveries to the station-service power plant and intermediate floors can be made through a hatch in the service bay floor. A single-trolley 50-ton bridge crane, with a 12-ton auxiliary hoist, was installed in the station-service plant.
Out-of-door cranes include a 14-ton step-leg traveling crane for the raising and lowering of draft-tube bulkheads on the downstream face of the powerhouse, and a 150-ton gantry crane on the dam above the powerhouse, for handling the 115-ton coaster gates which close the penstock portals. A 25-ton movable hoist on the latter crane will, handle stop gates, for which provisions are made outside the coaster gates.
Lighting
The generator room is lighted from 115/230-volt, 3-wire, single phase circuits, and the control bay from 115/199-volt, /.-wire, 3-phase circuits, both deriving their energy from widely distributed transformers, connected by hand operated, fused, selector switches to one or the other of two 6,900-volt feeders. Certain important operating areas are normally lighted by two separate systems, connected to the two 6,900-volt feeders, and are provided with emergenc lights automatically connected to the 250-volt storage batteries in case of failure of the A-C lighting circuits.
Heating and Ventilation
Electric heaters of a combined capacity of about 3,000 kw. will be installed in each powerhouse, some of the heaters in the intakes of ventilating fans, and others in recesses in the walls in various parts of the building.
Air, taken tnrough adjustable louvers in the upstream wall of the powerhouse, will be forced into the lower operating galleries, from 'which it will circulate through the building, to be exhausted or recirculated by fans near the ceiling. In the summer, contact of the circulated air with lower control gallery walls will reduce its temperature. Six changes of air '.rill take place each hour in the operating galleries, and one in the generating room.
Oil, Air, and Vater Service
Separate tanks and distributing and collecting systems are provided for lubricating and insulating oils, in the control bay. Transfer pumps and combined filter and centrifugal purifiers ere located in a separate room, adjacent to the tank room. Banks of high-pressure carbon dioxide tanks, piping, nozzles, thermostats, and electrically-operated valves provide fire protection.
Compressors in the oil-pump room furnish air at 100 psi. for the operation of generator brakes, and miscellaneous tools.
Cooling water for generators and transformers is lifted from the tailbay by water-jet eductors, operated by high-pressure water from the penstocks. Potable water is dram from the system provided for the government
10camp. Septic tanks in the building dispose of sewage.
Energy Available
The energy economically available annually from the fully developed power plant at the Grand Coulee Dam is estimated to be 12,510,000,000 lev.-hr.; and billions of kilowatt-hours Till go to waste during the summer floods.
Annual requirements for pumping for irrigation may ultimately reach 1,970,000,000 kv.-hr., all available from surplus summer water. Local consumption, in the plant, dam, and associated village may reach 85,000,000 kv.-hr. annually, leaving 10,455,000,000 kv.-hr. of firm energy for sale. In years of lowest run-off, salable firm energy is not expected to fall below 8,100,000,000 kv.-hr. Generating capacity is not likely to be less than 920,000 kv., in critical periods of low run-off.
The output is distributed and sold by the Bonneville Power Administration, which has already built or has under construction 230,000-volt lines to Puget Sound and the lower Columbia, and 115,000-volt lines to Spokane.
Irrigation and Pumping
An important feature of the economic development of the Columbia River will, be the irrigating of a million and a quarter acres of land in central Washington, within the next 25 to 50 years, and the development of homes and employment for 350 to 400 thousand persons on the land and in the towns that will grow up In the area.
The irrigation plant, when completed, will include, in addition to an extensive system of canals and pertinent works, 12 single-stage pumps, each equipped with a 65,000 horsepower synchronous motor, and designed to lift 50 tons of water per second 280 to 360 feet from the storage reservoir behind the dam to a 27-mile balancing reservoir to be formed by means of earth dams in the upper Grand Coulee. Two pump motors vrill bo driven from one generator, through direct 13,800-volt connections between them. The motors will be brought up to speed as the generators are started, and, through the control of turbine speeds, pump speeds will be adjusted to the existing difference in elevation between the reservoirs.
Personnel
The officials responsible for the development of the Columbia Basin Reclamation project are Harold L. Ickes, Secretary of the Interior, John C. Page, Commissioner of the Bureau of Reclamation, and Harry W. Bashore, Assistant Commissioner, of Washington; S. 0. Harper, Chief Engineer, W. R. Young, Assistant Chief Engineer, J. L. Savage, Chief Designing Engineer, and L. N. McClellan, Chief Electrical Engineer, of Denver; and F. A. Banks, Supervising Engineer, J. H. Miner, Assistant Supervising Engineer, and A. F. Dorland, Construction Engineer, of Coulee Dam, Washington.
(Oct. 1941)