Grand Coulee Dam

On July 16, 1933, a crowd of 3,000 watched the driving of the first stake at the low dam site, and excavation soon began. Core drilling commenced that September while the Bureau of Reclamation accelerated its studies and designs for the dam.[26] It would still help control floods and provide for irrigation and hydroelectricity, though at a reduced capacity. Most importantly, it would not raise its reservoir high enough to irrigate the plateau around the Grand Coulee. However, the dam's design provided for future raising and upgrading.[22]

The east-side cofferdam after the west base was complete

Before and during construction, workers and engineers experienced problems. Contracts for companies to construct the various parts of the dam were difficult to award as few companies were sizable enough to fill them. This forced companies to consolidate. In addition, Native American graves had to be relocated and temporary fish ladders had to be constructed. During construction additional problems included landslides and the need to protect newly poured concrete from freezing.[21] Construction on the downstream Grand Coulee Bridge began in May 1934 and more considerable earth-moving began in August. Excavation for the dam's foundation required the removal of 22 million cubic yards (17 million m³) of dirt and stone.[27] To reduce the amount of trucking required in the excavation, a conveyor belt nearly 2 mi (3.2 km) long was built.[28] To further secure the foundation, workers drilled 660–880 ft (200–270 m) holes into the granite and filled any fissures with grout, creating a grout curtain.[29] At times, excavated areas collapsed from overburden. In order to secure these areas from further movement and continue excavation, 3-inch (76 mm) diameter pipes were inserted into the mass and chilled with cold liquid from a refrigeration plant. This froze the earth and secured it so construction could continue.[30]

Final contract bidding for the dam began June 18, 1934, in Spokane, and four bids were submitted. One bid was from a lawyer with no financial backing; another was from actress Mae West which consisted of nothing more than a poem and promise to divert the river.[31] Of the two serious bids, the lowest bid was from a consortium of three companies: Silas Mason Co. from Louisville, Kentucky; Walsh Construction Co. of Davenport, Iowa and New York; and Atkinson-Kier Company of San Francisco and San Diego. The consortium was known as MWAK, and their bid was $29,339,301, almost 15% lower than the $34.5 million option submitted by the next bidder, Six Companies, Inc., which was building Hoover Dam at the time.[32]

Two large cofferdams were constructed for the dam, but they were parallel to the river rather than straddling its width, so drilling into the canyon walls was not required. By the end of 1935 about 1,200 workers completed the west and east cofferdams. The west cofferdam was 2,000 ft (610 m) long, 50 ft (15 m) thick and was constructed 110 ft (34 m) above the bedrock.[33] The cofferdams allowed workers to dry portions of the riverbed and begin constructing the dam, while water continued to flow down the center of the riverbed.[34] In August 1936, once the west foundation was complete, portions of the west cofferdam were dismantled, allowing water to flow through part of the dam's new foundation. In February 1936, MWAK had begun constructing cofferdams above and below the channel between the east and west cofferdams. By December, the entire Columbia River was diverted over the foundations constructed within the east and west cofferdams. On December 15, 1936, the Wenatchee Daily World announced the river was diverted and by early the next year, people were arriving in large numbers to see the riverbed.[35]

Base of the dam in 1938

On August 4, 1934, President Franklin D. Roosevelt visited the construction site and was impressed by the project and its purpose.[36] He spoke to workers and spectators, closing with this statement: "I leave here today with the feeling that this work is well undertaken; that we are going ahead with a useful project, and we are going to see it through for the benefit of our country."[37] Soon afterward, Reclamation was allowed to proceed with the high dam plan but faced the problems of transitioning the design and negotiating an altered contract with MWAK. In June 1935, for an additional $7 million, MWAK and Six Companies, Inc. agreed to join together as Consolidated Builders Inc. and construct the high dam. Six Companies had just finished the Hoover Dam and was nearing completion of Parker Dam. The new design, chosen and approved by the Reclamation office in Denver, included several improvements, one of which was the irrigation pumping plant.[36]

Roosevelt envisioned the dam would fit into his New Deal under the Public Works Administration; it would create jobs, farming opportunities and would pay for itself. In addition, as part of a larger public effort, Roosevelt wanted to keep electricity prices low by limiting private ownership of utility companies, which could charge high prices for energy.[22] Many opposed a federal takeover of the project, including its most prominent supporters, but Washington State lacked the resources to fully realize the project.[38][39] In August 1935, with the help of Roosevelt and a Supreme Court decision allowing the acquisition of public land and Indian Reservations, Congress authorized funding for the upgraded high dam under the 1935 River and Harbors Act.[40] The most significant legislative hurdle for the dam was over.[41]

That for the purpose of controlling floods, improving navigation, regulating the flow of the streams of the United States, providing for storage and for the delivery of the stored waters thereof, for the reclamation of public lands and Indian reservations, and other beneficial uses, and for the generation of electric energy as a means of financially aiding and assisting such undertakings the projects known as "Parker Dam" on the Colorado River and "Grand Coulee Dam" on the Columbia River are hereby authorized and adopted.

— 1935 Rivers and Harbors Act SEC 2, August 30, 1935, [H.R. 6250] [Public, No. 409][41]

The dam after completion, with water moving into the spillway

On December 6, 1935, Governor Clarence Martin presided over the ceremonial first concrete pour.[42] During construction, bulk concrete was delivered on site by rail-cars where it was further processed by eight large mixers before being placed in form. Concrete was poured into 50 sq ft (4.6 m²) columns by crane-lifted buckets, each supporting eight tons of concrete.[43] To cool the concrete and facilitate curing, about 2,000 mi (3,200 km) of piping was placed throughout the hardening mass. Cold water from the river was pumped into the pipes, reducing the temperature within the forms from 105 °F (41 °C) to 45 °F (7 °C). This caused the dam to contract about 8 inches (20 cm) in length; the resulting gaps were filled with grout.[34]

Until the project began, the stretch of the Columbia River where the dam was to rise was as yet unbridged, making it difficult to move men and materials.[44] In January 1936, the Grand Coulee Bridge (a permanent highway bridge) was opened after major delays caused by high water; three additional and temporary bridges downstream had moved vehicles and workers along with sand and gravel for cement mixing.[30][45] In March 1938, MWAK completed the lower dam and Consolidated Builders Inc. began constructing the high dam. The west power house was completed in December 1939 and about 5,500 workers were on site that year. Between 1940 and 1941, the dam's eleven floodgates were installed on the spillway and the dam's first generator went into operation in January 1941. The reservoir was full and the first water flowed over the dam's spillway on June 1, 1942, while work was officially complete on January 31, 1943.[46][47] The last of the original 18 generators did not operate until 1950.[5]

Banks and Smith felling the last tree in the reservoir zone

In 1933, Reclamation began efforts to purchase land behind the dam as far as 151 mi (243 km) upstream for the future reservoir zone. The reservoir, known later as Lake Roosevelt, flooded 70,500 acres (285 km²) and Reclamation acquired an additional 11,500 acres (47 km²) around the future shoreline. Within the zone were eleven towns, two railroads, three state highways, about one hundred and fifty miles of country roads, four sawmills, fourteen bridges, four telegraph and telephone systems, and many power lines and cemeteries. All facilities had to be purchased or relocated, and 3,000 residents were relocated.[48] The Anti-Speculation Act was passed in 1937, limiting the amount of land farmers could own to prevent inflated prices.[19] The government appraised the land and offered to purchase it from the affected residents. Many refused to accept the offers, and Reclamation filed condemnation suits.[49] Members of the Colville Confederated and Spokane tribes who had settlements within the reservoir zone were also resettled. The Acquisition of Indian Lands for Grand Coulee Dam Act of June 29, 1940, allowed the Secretary of the Interior to acquire land on the Colville and Spokane Reservations, eventually accounting for 21,100 acres (85 km²).[50] By 1942, all land had been purchased at market value: a cost of $10.5 million that included the relocation of farms, bridges, highways and railroads. Relocation reimbursement was not offered to property owners, which was common until U.S. laws changed in 1958.[49]

In late 1938, the Works Progress Administration began clearing what would be 54,000 acres (220 km²) of trees and other plants. The cut timber was floated downstream and sold to the highest bidder, Lincoln Lumber Company, which paid $2.25 per thousand board feet (equivalent to $41 in 2019).[51] The pace of clearing was accelerated in April 1941 when it was declared a national defense project, and the last tree was felled on July 19, 1941. The felling was done by Reclamation Supervising Engineer Frank A. Banks and State WPA Administrator Carl W. Smith during a ceremony.[52] 2,626 people living in five main camps along the Columbia worked on the project. When it was finished, $4.9 million had been spent in labor.[53]

Workers installing a penstock section

Workers building the dam received an average of 80¢ an hour; the payroll for the dam was among the largest in the nation. The workers were mainly pulled from Grant, Lincoln, Douglas, and Okanogan counties and women were allowed to work only in the dorms and the cookhouse.[54] Around 8,000 people worked on the project, and Frank A. Banks served as the chief construction engineer. Bert A. Hall was the chief inspector who would accept the dam from the contractors. Orin G. Patch served as the chief of concrete.[21][55][56] Construction conditions were dangerous and 77 workers died.[26]

To prepare for construction, housing for workers was needed along with four bridges downstream of the dam site, one of which, the Grand Coulee Bridge, exists today. The Bureau of Reclamation provided housing and located their administrative building at Engineer's Town, which was directly downstream of the construction site on the west side of the river.[30] Opposite Engineer's Town, MWAK constructed Mason City in 1934. Mason city contained a hospital, post office, electricity and other amenities along with a population of 3,000. Three-bedroom houses in the city were rented for $32 a month.[57] Of the two living areas, Engineer's City was considered to have the better housing.[58] Several other living areas formed around the construction site in an area known as Shack Town, which did not have reliable access to electricity and the same amenities as the other towns.[59] Incorporated in 1935, the city of Grand Coulee supported workers as well and is just west of the dam on the plateau.[60] MWAK eventually sold Mason City to Reclamation in 1937 before its contract was completed.[61] In 1956, Reclamation combined both Mason City and Engineer's Town to form the city of Coulee Dam. It was incorporated as a city in February 1959.[58]

With the onset of World War II, power generation was given priority over irrigation. In 1943, Congress authorized the Columbia Basin Project and the Bureau of Reclamation began construction of irrigation facilities in 1948. Directly to the west and above the Grand Coulee Dam, the North Dam was constructed. This dam, along with the Dry Falls Dam to the south, enclosed and created Banks Lake, which covered the northern 27 mi (43 km) of the Grand Coulee. Additional dams, such as the Pinto and O'Sullivan Dams, were constructed alongside siphons and canals, creating a vast irrigation supply network called the Columbia Basin Project. Irrigation began between 1951 and 1953 as six of the 12 pumps were installed and Banks Lake was filled.[62]

Canadian Prime Minister John Diefenbaker (seated left) and US President Dwight Eisenhower at the signing of the Columbia River Treaty, 1961

After World War II, the growing demand for electricity sparked interest in constructing another power plant supported by the Grand Coulee Dam.[63] One obstacle to an additional power plant was the great seasonality of the Columbia River's streamflow. Today the flow is closely managed—there is almost no seasonality. Historically, about 75% of the river's annual flow occurred between April and September.[64] During low flow periods, the river's discharge was between 50,000 cu ft/s (1,400 m³/s) and 80,000 cu ft/s (2,300 m³/s) while maximum spring runoff flows were around 500,000 cu ft/s (14,000 m³/s). Only nine out of the dam's eighteen generators could run year-round. The remaining nine operated for less than six months a year.[65] In 1952, Congress authorized $125,000 for Reclamation to conduct a feasibility study on the Third Powerplant which was completed in 1953 and recommended two locations. Nine identical 108 MW generators were recommended, but as matters stood, they would be able to operate only in periods of high water.[63]

Further regulation of the Columbia's flows was necessary to make the new power plant feasible. It would require water storage and regulation projects in Canada and a treaty to resolve the many economic and political issues involved. The Bureau of Reclamation and Army Corps of Engineers explored alternatives that would not depend on a treaty with Canada, such as raising the level of Flathead Lake or Pend Oreille Lake, but both proposals faced strong local opposition.[63] The Columbia River Treaty, which had been discussed between the U.S. and Canada since 1944, was seen as the answer. Efforts to build the Third Powerplant were also influenced by competition with the Soviet Union, which had constructed power plants on the Volga River larger than Grand Coulee.[66] On September 16, 1964, the Columbia River Treaty was ratified and included an agreement by Canada to construct the Duncan, Keenleyside, Mica Dams upstream and the U.S. would build the Libby Dam in Montana.[67] Shortly afterward, Washington Senator Henry M. Jackson, who was influential in constructing the new power plant, announced Reclamation would present the project to Congress for appropriation and funding.[68] To keep up with Soviet competition and increase the generating capacity it was determined the generators could be upgraded to much larger designs. With the possibility of international companies bidding on the project, the Soviets who had just installed a 500 MW hydroelectric generator on the Yenisei River indicated their interest. To avoid the potential embarrassment of an international rival building a domestic power plant, the Department of the Interior declined international bidding. The Third Powerplant was approved and President Lyndon Johnson signed its appropriation bill on June 14, 1966.[69]

One of the new turbines in the Third Powerplant

Between 1967 and 1974, the dam was expanded to add the Third Powerplant, with architectural design by Marcel Breuer.[70] Beginning in July 1967, this involved demolishing the northeast side of the dam and building a new fore-bay section. The excavation of 22,000,000 cu yd (16,820,207 m³) of dirt and rock had been completed before the new 1,725 ft (526 m) long section of dam was built. The addition made the original 4,300 ft (1,300 m) dam almost a mile long. Original designs for the powerhouse had twelve smaller units but were altered to incorporate six of the largest generators available. To supply them with water, six 40 ft (12 m) diameter penstocks were installed.[71] Of the new turbines and generators, three 600 MW units were built by Westinghouse and three 700 MW units by General Electric. The first new generator was commissioned in 1975 and the final one in 1980.[5] The three 700 MW units were later upgraded to 805 MW by Siemens.[72]

Cross-section of the Pump-Generating Plant

After power shortages in the Northwest during the 1960s, it was determined the six remaining planned pumps be pump-generators. When energy demand is high, the pump-generators can generate electricity with water from the Banks Lake feeder canal adjacent to the dam at a higher elevation.[73] By 1973, the Pump-Generating Plant was completed and the first two generators (P/G-7 and P/G-8) were operational. In 1983, two more generators went online, and by January 1984 the final two were operational. The six pump-generators added 314 MW to the dam's capacity.[74] In May 2009, the Pump-Generating Plant was officially renamed the John W. Keys III Pump-Generating Power Plant after John W. Keys III, the U.S. Bureau of Reclamation's commissioner from 2001 to 2006.[75]

A major overhaul of the Third Powerplant, which contains generators numbered G19 through G24, began in March 2008 and will be continuing for many years. Among the projects to be completed before the generators themselves can begin to be overhauled include replacing underground 500 kV oil-filled cables for G19, G20 and G21 generators with overhead transmission lines (started in February 2009), new 236 MW transformers for G19 and G20 (started in November 2006), and several other projects.[76] Planning, design, procurement and site preparation for the 805 MW G22, G23 and G24 generator overhauls are scheduled to begin in 2011, with the overhauls themselves to start in 2013 with the G22 generator, then G23 starting in 2014, and finally G24 starting in 2016, with planned completions in 2014, 2016 and 2017, respectively. The generator overhauls for G19, G20 and G21 have not been scheduled as of 2010.[77]

Water is pumped via the Pump-Generating Plant's 12-foot (3.7 m) diameter pipes 280 ft (85 m) from Lake Roosevelt to a 1.6 mi (2.6 km) feeder canal. From the feeder canal, the water is transferred to Banks Lake which has an active storage of 715,000 acre⋅ft (882 million m³). The plant's twelve 65,000–70,000 horsepower (48,000–52,000 kW) pumps can transfer up to 1,605 cu ft/s (45 m³/s) to the lake. Currently, the Columbia Basin Project irrigates 670,000 acres (2,700 km²) with a potential for 1.1 million.[73] Over 60 different crops are grown within the project and distributed throughout the United States.[62]

Grand Coulee Dam supports four different power houses containing 33 hydroelectric generators. The original Left and Right Powerhouses contain 18 main generators and the Left has an additional three service generators for total installed capacity of 2,280 MW. The first generator was commissioned in 1941 and all 18 were operating by 1950. The Third Power plant contains a total of six main generators with a 4,215 MW installed capacity. Generators G-19, G-20 and G-21 in the Third Power Plant have a 600 MW installed capacity but can operate at a maximum capacity of 690 MW which brings the overall maximum capacity of the dam's power facilities to 7,079 MW. The Pump-Generating Plant contains six pump-generators with an installed capacity of 314 MW. When pumping water into Banks Lake they consume 600 MW of electricity. Each generator is supplied with water by an individual penstock. The largest of these feed the Third Power Plant and are 40 ft (12 m) in diameter and can supply up to 35,000 cu ft/s (990 m³/s). The dam's power facilities originally had an installed capacity of 1,974 MW but expansions and upgrades have increased generation to 6,809 MW installed, 7,079 MW maximum. Grand Coulee Dam generates 21 TWh of electricity annually.[81] This means the dam generates about 2,397 MW of power on average, which results in a total plant factor efficiency of 35%.[5] In 2014, 20.24 TWh of electricity was generated.

Pump-Generating Plant and Roosevelt Lake at bottom, feeder canal to Banks Lake at top

Grand Coulee Dam's spillway is 1,650 feet (500 m) long and is an overflow, drum-gate controlled type with a 1,000,000 cu ft/s (28,000 m³/s) maximum capacity.[74] A record flood in May and June 1948 flooded lowland below the dam and highlighted its limited flood control capability at the time,[83] as its spillway and turbines hit a record flow of 637,800-cubic-foot-per-second (18,060 m³/s).[73] The flood damaged downstream riverbanks and deteriorated the face of the dam and its flip bucket at the base (toe) of the spillway.[84] The flood spurred the Columbia River Treaty and its provisions for dams constructed upstream in Canada, which would regulate the Columbia's flow.[85]

The Bureau of Reclamation in 1932 estimated the cost of constructing Grand Coulee Dam (not including the Third Powerplant) to be $168 million; its actual cost was $163 million in 1943 ($1.96 billion in 2019 dollars[2]). Expenses to finish the power stations and repair design flaws with the dam throughout the 1940s and '50s added another $107 million, bringing the total cost to $270 million ($2.1 billion in 2019 dollars[2]), about 33% over estimates.[86] The Third Powerplant was estimated to cost $390 million in 1967, but higher construction costs and labor disputes drove the project's final cost in 1973 to $730 million ($3.27 billion in 2019 dollars[2]), about 55% over estimates. Despite estimates being exceeded, the dam became an economic success, particularly with the Third Powerplant exhibiting a benefit-cost ratio of 2:1.[67] Although Reclamation has only irrigated about half of the land predicted, the gross value of crop output (in constant dollars) had doubled from 1962 to 1992, largely due to different farming practices and crop choices.[40] The Bureau expects the money earned from supplying power and irrigation water will pay off the cost of construction by 2044.[87]