Grand Coulee Dam
Grand Coulee Dam
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Grand Coulee Dam
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Location of the dam in
the western U.S.
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Location
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Grant / Okanogancounties,
near Coulee Dam and Grand Coulee,Washington, US
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Coordinates
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Purpose
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Power, regulation, irrigation
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Status
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Operational
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Construction began
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July 16, 1933
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Opening date
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June 1, 1942
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Construction cost
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Original dam: $168 million
Third Powerplant: $730 million |
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Dam and spillways
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Concrete gravity
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Height
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550 ft (168 m)
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Length
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5,223 ft (1,592 m)
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Crest width
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30 ft (9 m)[1]
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Base width
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500 ft (152 m)
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Volume
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11,975,520 cu yd (9,155,942 m3)
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Impounds
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Type of spillway
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Service, drum gate
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Spillway capacity
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1,000,000 cu ft/s (28,317 m3/s)
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Reservoir
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Creates
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Capacity
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9,562,000 acre·ft (12 km3)
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5,185,400 acre·ft (6 km3)
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74,100 sq mi (191,918 km2)
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Surface area
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125 sq mi (324 km2)
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Power station
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Commission date
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1941–1950 (Left/Right)
1975–1980 (Third) 1973–1984 (PS) |
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380 ft (116 m)
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Turbines
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33:
27 × Francis turbines 6 × pump-generators |
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Installed capacity
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Maximum capacity
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7,079 MW
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Annual generation
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21 billion KWh
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Grand Coulee Dam is
a gravity dam on the Columbia River in the U.S. state of Washington built
to produce hydroelectric power
and provide irrigation. It was constructed between 1933 and 1942, originally
with two power plants. A third power station was completed in 1974 to increase
its energy production. It is the largest electric power-producing facility in the
United States[3]and one of the largest concrete
structures in the world.[1]
The proposal to build
the dam was the focus of a bitter debate during the 1920s between two groups.
One wanted to irrigate the ancient Grand Coulee with a gravity canal and the
other supported a high dam and pumping scheme. Dam supporters won in 1933, but
for fiscal reasons the initial design was for a "low dam" 290 ft
(88 m) high which would generate electricity, but not support irrigation.
The U.S. Bureau of
Reclamation and a consortium of three companies called MWAK
(Mason-Walsh-Atkinson Kier Company) began construction that year. After
visiting the construction site in August 1934, President Franklin Delano
Roosevelt began endorsing the "high dam" design
which, at 550 ft (168 m) high, would provide enough electricity to
pump water to irrigate the Columbia Basin. The high dam was approved by Congress in 1935 and completed in 1942;
the first water over-topped its spillway on June 1 of that year.
Power from the dam
fueled the growing industries of the Northwest United States during World War II. Between 1967 and 1974, the
Third Powerplant was constructed. The decision to construct the additional facility
was influenced by growing energy demand, regulated river flows stipulated in
the Columbia River Treaty with
Canada and competition with the Soviet Union. Through a series of upgrades and
the installation of pump-generators,
the dam now supplies four power stations with an installed capacity of
6,809 MW. As the center-piece of the Columbia Basin
Project, the dam's reservoir supplies water for the irrigation of
671,000 acres (2,700 km2).
The reservoir is called Franklin Delano
Roosevelt Lake, named after the United States President who presided
over the authorization and completion of the dam. Creation of the reservoir
forced the relocation of over 3,000 people, including Native
Americans whose ancestral lands were partially flooded. The dam
has also blocked the migration of salmon and other fish upstream to spawn.
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Contents
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[edit]Background
The Grand Coulee is an ancient river bed on
the Columbia Plateau created
during the Pliocene Epoch (Calabrian) by retreating
glaciers and floods. Originally, geologists believed the Grand Coulee was
formed by a glacier diverting the Columbia River but it was revealed in the
mid-late 20th century that massive floods from Lake Missoula carved most of the gorge.[4] The earliest known proposal to
irrigate the Grand Coulee with the Columbia River dates to 1892, when the Coulee
City News and The Spokesman Review reported on a
scheme by a man named Laughlin McLean to construct a 1,000 ft (305 m)
dam across the Columbia River, high enough that water would back up into the
Grand Coulee. A dam that size would have its reservoir encroach into Canada,
which would violate treaties.[5] Shortly after the Bureau of
Reclamation was founded, it investigated a scheme for pumping water from the
Columbia River to irrigate parts of central Washington. An attempt to raise
funds for irrigation failed in 1914, as a bond measure was rejected by Washington
voters.[6]
Such a power if developed would operate railroads,
factories, mines, irrigation pumps, furnish heat and light in such measure that
all in all it would be the most unique, the most interesting, and the most
remarkable development of both irrigation and power in this age of industrial
and scientific miracles.[7]
“
”
– Rufus Woods
An attorney from Ephrata, Washington,
named William M. Clapp proposed in 1917 that the Columbia be dammed immediately
below the Grand Coulee.[8] He suggested a concrete dam
could flood the plateau, just as nature blocked it with ice centuries ago.
Clapp was joined by another attorney, James O'Sullivan, and by Rufus Woods,
publisher of the Wenatchee Worldnewspaper. Together, they became
known as the "Dam College".[9] Woods began promoting the Grand
Coulee Dam in his newspaper, often with articles written by O'Sullivan. The dam
idea gained popularity with the public in 1918. Backers of reclamation in
Central Washington split into two camps. One side, known as the
"pumpers", favored a dam with pumps to elevate water from the river
into the Grand Coulee from which canals and pipes could be used to irrigate
farmland. The other side, known as the "ditchers", favored diverting
water from northeast Washington's Pend Oreille River via
a gravity canal to irrigate farmland in Central and Eastern Washington. Many
locals such as Woods, O'Sullivan and Clapp were pumpers, while many influential
businessmen in Spokane associated with the Washington
Water and Power Company (WWPC) were staunch ditchers. The
pumpers argued that hydroelectricity from the dam could be used to cover costs
and claimed the ditchers sought to maintain a monopoly on electric power.[5]
The ditchers took a
number of steps to ensure support for their proposals. In 1921, WWPC secured a
preliminary permit to build a dam at Kettle Falls, about 110 mi (177 km)
upstream from the Grand Coulee. If built, the Kettle Falls Dam would have lain
in the path of the Grand Coulee Dam's reservoir, essentially blocking its
construction.[10] WWPC planted rumors in the
newspapers, incorrectly stating that exploratory drilling at the Grand Coulee
site found no granite on which a dam's foundations could rest, only clay and
fragmented rock. This was later disproved with Reclamation-ordered drilling.
Ditchers hired General George W. Goethals,
engineer of the Panama Canal, to
prepare a report. Goethals visited the state and produced a report backing the
ditchers. The Bureau of Reclamation was unimpressed by Goethals' report,
believing it filled with errors.[10] In July 1923, President Warren G. Harding visited Washington
state and expressed support for irrigation work there, but died a month later.
His successor, Calvin Coolidge,
had little interest in irrigation projects. The Bureau of Reclamation, desirous
of a major project that would bolster its reputation, was focusing on the Boulder Canyon
Project that resulted in the Hoover Dam. Reclamation was authorized to
conduct a study in 1923, but the project's cost made federal officials
reluctant. The Washington state proposals received little support from those
further east, who feared the irrigation would result in more crops, depressing
prices.[11] With President Coolidge
opposed to the project, bills to appropriate money for surveys of the Grand
Coulee site failed.[12]
Photo
of the dam site taken before construction, looking south
In 1925, Congress
authorized a U.S. Army
Corps of Engineers study of the Columbia River.[13] This study was included in the
Rivers and Harbors Act of March 1925, which provided for studies on the
navigation, power, flood control and irrigation potential of rivers. In April
1926, the Army Corps responded with the first of the "308 Reports"
named after the 1925 House Document No. 308 (69th Congress, 1st Session).[14] With the help of Washington's
Senators, Wesley Jones and Clarence Dill, Congress ordered $600,000 in
further studies to be carried out by the Army Corps and Federal Power
Commission on the Columbia River Basin and Snake Rivers.[15] U.S. Army Major John Butler
was responsible for the upper Columbia River and Snake River and in 1932, his
1,000-page report was submitted to Congress. It recommended the Grand Coulee
Dam and nine others on the river, including some in Canada. The report stated
that electricity sales from the Grand Coulee Dam could pay for construction
costs. Reclamation—whose interest in the dam was revitalized by the
report—endorsed it.[14][16]
Although there was
some support for the Grand Coulee Dam, others argued there was little need for
more electricity in the Northwest and crops were in surplus. The Army Corps did
not believe construction should be a federal project and saw low demand for
electricity. Reclamation argued that energy demand would rise by the time the
dam was complete.[17] The head of Reclamation, Elwood Mead, stated he wanted the dam built no
matter the cost.[18] President Franklin D. Roosevelt,
who took office in March, 1933, supported the dam because of its irrigation
potential and the power it would provide, but he was uneasy with its $450
million price tag. For this reason, he supported a 290 ft (88 m)
"low dam" instead of the 550 ft (168 m) "high
dam".[19]He provided $63 million in
federal funding, while Washington State provided $377,000.[16] In 1933, Washington governor Clarence Martin set up the Columbia Basin
Commission to oversee the dam project,[20] and Reclamation was selected
to oversee construction.[19]
Construction
Low
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.[21] 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.[17]
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.[16] 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 22,000,000
cu yd (17,000,000 m3) of dirt and stone.[22] To reduce the amount of
trucking required in the excavation, a conveyor belt nearly 2 mi
(3.2 km) long was built.[23] 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.[24] 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.[25]
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 Westwhich consisted
of nothing more than a poem and promise to divert the river.[26] 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.[27]
[edit]Cofferdams
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.[28] 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.[29] 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. InFebruary
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
that the river was diverted and by early the next year, people were arriving in
large numbers to see the riverbed.[30]
[edit]Design
change
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.[31] He gave a speech 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."[32] Soon after his visit,
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.[31]
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.[17] Many opposed a federal
takeover of the project, including its most prominent supporters, but
Washington State lacked the resources to fully realize the project.[33][34] In August 1935, with the
help of Roosevelt and aSupreme
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.[35] The most significant
legislative hurdle for the dam was over.[36]
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][36]
[edit]First concrete pour
and completion
The
dam after completion and water over-topping the spillway
On December 6, 1935,
Governor Clarence Martin presided over the ceremonial first concrete pour.[37] 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.[38] To cool the concrete and
facilitate curing, about 2,000 mi (3,200 km) of piping was placed
throughout the drying 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 eight inches in
length; the resulting gaps were filled with grout.[29]
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.[39] 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.[25][40] In March 1938, MWAK
completed the lower dam and Consolidated Builders Inc. began constructing the
high dam. The west power house was completed inDecember 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.[41][42] The last of the original 18
generators was not operational until 1950.[43]
Reservoir
clearing
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.[44] The Anti-Speculation Act was
passed in 1937, limiting the amount of land farmers could own in order to
prevent inflated prices.[14] 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.[45] 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).[46] 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 were
changed in 1958.[45]
In late 1938, the Works
Progress Administration began clearing the reservoir zone of
trees and other plants. A total of 54,000 acres (220 km2) were
cleared. The cut timber was floated downstream and sold to the highest bidder,
Lincoln Lumber Company, which paid $2.25 per thousand board feet.[47] 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.[48] A total of 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.[49]
[edit]Labor and supporting
infrastructure
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,
andOkanogan counties
and women were allowed to work only in the dorms and the cookhouse.[50] 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.[16][51][52] Construction conditions were
dangerous and 77 workers died.[21]
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 located directly downstream of the
construction site on the west side of the river.[25]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.[53] Of the two living areas,
Engineer's City was considered to have the better housing.[54] 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.[55] Incorporated in 1935, the city
of Grand Coulee supported
workers as well and is located just west of the dam on the plateau.[56] MWAK eventually sold Mason
City to Reclamation in 1937 before its contract was completed.[57] 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.[54]
Irrigation
pumps
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
createdBanks 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.[58]
Expansion
Third
powerplant
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.[59] 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.[60] 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.[61] In 1952, Congressauthorized $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.[59]
Further regulation of
the Columbia's flows was necessary to make the new power plant feasible. Water
storage and regulation projects in Canada would be needed, as well as a treaty
resolving 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.[59] 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 that were larger than Grand
Coulee.[62] On September 16, 1964,
the Columbia River Treaty was ratified and included an agreement by Canada to
construct the Duncan, Keenleyside and Mica Damsupstream.[63] Shortly afterward, Washington
Senator Henry M. Jackson,
who was influential in constructing the new power plant, announced that
Reclamation would present the project to Congress for appropriation and
funding.[64] To keep up with Soviet
competition and increase the generating capacity it was determined that 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 its appropriation bill was
signed by President Lyndon Johnson on June
14, 1966.[65]
One
of the new turbines in the Third Powerplant
Between 1967 and
1974, the dam was expanded to add the Third Powerplant. 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 to be accomplished 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.[66] Of the new turbines and
generators, three 600 MW units were built by Westinghouse and
three 700 MW units byGeneral Electric. The first new generator was
commissioned in 1975 and the final one in 1980.[43] The three 700 MW units
were later upgraded to 805 MW by Siemens.[67]
Pump-generating
plant
Cross-section
of the Pump-Generating Plant
After power shortages
in the Northwest during the 1960s, it was determined that 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.[68] By 1973, the Pump-Generating
Plant was completed and the first three generators were operational. In 1983,
two more generators went online, and by January 1984 the final was
operational. The six pump-generators added 314 MW to the dam's capacity.[69] 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.[70]
[edit]Overhauls
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.[71] 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.[72]
[edit]Operation
and benefits
Map
of the Columbia Basin
Project. Green denotes land irrigated by the project. Grand Coulee
Dam near top-right
The dam's primary
goal, irrigation, was postponed as the wartime need for electricity increased.
The dam's powerhouse began production around the time World War II began, and its
electricity was vital to the war effort. The dam powered aluminum smelters in Longview and Vancouver, Washington, Boeing factories in Seattle and Vancouver, and Portland's
shipyards. In 1943, its electricity was also used for plutonium production in Richland, Washington,
at the Hanford Site, which
was part of the top-secret Manhattan Project.[73][74]The demand for power at that project
was so great that in 1943, two generators originally intended for the Shasta Dam were installed at Grand Coulee
in an effort to hurry the generator installation schedule.[75]
[edit]Irrigation
Main
article: Columbia Basin
Project
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 (882,000,000 m3).
The plant's twelve 65,000–70,000 horsepower 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.[68] Over 60 different crops are
grown within the project and distributed throughout the United States.[58]
[edit]Power
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 Powerplant 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 Powerplant 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
Powerplant 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. In 2008, 21 billion kWh of electricity was generated with a plant factor of 38.24%.[43]
Spillway
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.[69] A record flood in May andJune
1948 flooded lowland below the dam and highlighted its limited flood
control capability at the time,[77] as its spillway and turbines
hit a record flow of 637,800-cubic-foot-per-second (18,060 m3/s).[68] The flood damaged downstream
riverbanks and deteriorated the face of the dam and its flip bucket at the base (toe) of the
spillway.[78] The flood spurred the Columbia
River Treaty and its provisions for dams constructed upstream in Canada, which
would regulate the Columbia's flow.[79]
[edit]Cost
benefits
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 ($1.85
billion in 1998). 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 ($2.6 billion in 1998), about 33% over
estimates.[80] 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 ($2.93
billion in 1998), 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.[63] 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.[35]
[edit]Environmental and
social consequences
The dam had severe
negative consequences for the local Native
American tribes whose traditional way of life revolved around salmon and the original shrub steppe habitat of the
area. Because it lacks a fish ladder, Grand
Coulee Dam permanently blocks fish migration, removing over 1,100 mi
(1,770 km) of natural spawning habitat.[81] By largely eliminating anadromous fish above the Okanogan River,
the Grand Coulee Dam also set the stage for the subsequent decision not to
provide for fish passage at Chief Joseph Dam (built in 1953).[82] Chinook, Steelhead, Sockeye
and Coho salmon (as well as other important species including Lamprey) are now
unable to spawn in the reaches of the Upper Columbia Basin. The extinction of
the spawning grounds upstream from the dam has prevented the Spokane and other
tribes from holding the first salmon ceremony.[83]
Grand Coulee Dam
flooded over 21,000 acres (85 km2) of prime bottom land where
Native Americans had been living and hunting for thousands of years, forcing
the relocation of settlements and graveyards.[84] Kettle Falls, once a primary
Native American fishing grounds, was inundated. The average catch of over
600,000 salmon per year was eliminated. In one study, the Army Corps of
Engineers estimated the annual loss was over 1 million fish.[85] In June 1941, Native
Americans throughout the Northwest met at the Falls for the "Ceremony of
Tears", marking the end of fishing there. One month later, the falls were
inundated.[83] The town of Kettle Falls,
Washington, was relocated. The Columbia Basin Project has affected
habitat ranges for species such as mule deer, pygmy rabbits and burrowing owls,
resulting in decreased populations. However, it has created new habitats such
as wetlands, and riparian corridors.[85] The environmental impact of
the dam effectively ended the traditional way of life of the native
inhabitants. The government eventually compensated the Colville Indians in the 1990s with a lump settlement
of approximately $53 million, plus annual payments of approximately $15
million.[86] The Spokane tribe still seeks
compensation, currently through congressional bill H.R. 3097.[87]
[edit]Tourism
Built in the late
1970s, the Visitor Center contains many historical photos, geological samples,
turbine and dam models, and a theater. The building was designed by Marcel Breuer and resembles a generator
rotor.[88] Since May 1989, on summer
evenings, the laser
light show at Grand Coulee Dam is projected onto the dam's
wall. The show includes full-size images of battleships and the Statue of Liberty, as well as some
environmental comments.[89] Tours of the Third Powerplant
are available to the public and last about an hour. Visitors currently take a
shuttle to view the generators and also travel across the main dam span
(otherwise closed to the public) as the formerly used glass elevator is
indefinitely out of service.[90][91]
Panoramic view of the dam, looking Southeast. The
Third Powerplant at left
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