Hoover Dam is a hydraulic structure and hydroelectric power plants in the United States.It was erected in the lower reaches of the Colorado River.The height of the dam is 221 m. It is located in the Black Canyon, near the Nevada and Arizona.It was named in honor of the 31 th president - Herbert Hoover, who played in the construction of her role.The construction of the dam took place in 1931-1936 gg.
Hoover Dam is operated by Interior Ministry units US Bureau of Reclamation.It is one of the most famous attractions of Las Vegas.
Background Prior to the construction of the dam the Colorado (River) often showed his explosive temper.During the melting of the snows in the mountains it is often flooded lands farmers who are downstream.Designers believe that the construction of dams to help smooth out fluctuations in the level of the river.In addition, it was expected that the reservoir will push the development of irrigated agriculture and become a source of water in many areas of Southern California.
One of the main obstacles to the implementation of the project proved to doubt the representatives of the states located in the basin of Colorado.The river, or rather its water resources were equitably distributed among consumers.There were thoughts that California, with all its influence and finances, to lay claim to the bulk of the water reserves of the reservoir.
Because of this commission was created, which included one representative from each of the States concerned as well as a representative from the federal government.Their work has become signatories to the Convention of the Colorado River.It was fixed modes of distribution of water resources.This paved the way for the construction of the dam.
construction hydraulic structure of this scale required to attract significant funds from the state budget.The bill was approved on the financing of the White House and the US Senate immediately.In 1928 Calvin Coolidge signed a bill giving the go-ahead for the implementation of the project.The first allocations have been allocated for the construction of only 2 years later.Then there was President Herbert Hoover.
plan called for the construction of the dam at Boulder (Canyon of the Colorado River).Although finally it was decided to erect it in the Black Canyon, the project became known as the Boulder Canyon Project.
Construction for the construction of dams in a row has been charged several companies.Among them are: Six Companies, Inc., Morrison-Knudsen Company;Utah Construction Company;Pacific Bridge Company;Henry J. Kaiser & amp;W.A.Bechtel Company;MacDonald & amp;Kahn Ltd., J. F. Shea Company.
workers participated in the construction of thousands of workers (in 1934, the maximum number was 5251 persons).Under the contract, was not allowed to work hiring Chinese workers, and the total number of black mercenaries did not exceed 30 people, while they were engaged in the most poorly paid jobs.It was assumed that near a dam will be built for the builders of the small town, but the schedule was revised in favor of increasing the number of jobs and speed up the process (to reduce unemployment, which was the result of the Great Depression).Because of this, the time of arrival of the first mercenaries city was not ready yet, and the builders of the dam first summer spent in the camps.
Hazardous working conditions and delay in delivery of housing led to a strike that took place in 1931.At the same time the workers were dispersed by force (police used batons and guns).However, the pace of construction of the town, it was decided to speed up, and in the spring of next year, people have moved into permanent homes.During construction in Boulder City were banned gambling, prostitution and the sale of alcoholic beverages.Last ban remained here until 1969.Gambling is a business here is not resolved to this day, making Boulder City the only city in the state of Nevada, which operates such a ban.
working conditions
Hoover Dam, a photo of which are presented in this article, was built in the hardest conditions.Some of the work took place in the tunnels, where the workers suffered from the carbon monoxide, of which there were in excess (some builders therefore had died or become disabled).The employer is then said that the deaths were a consequence of pneumonia, and he can not be held liable.Meanwhile, construction of the dam was the first building, in which employees were given helmets.
During the construction of the dam (dam) killed a total of 96 people.The very first of them was the surveyor George. Tierney, who drowned at the end of 1922 in Colorado, choosing the best place for construction.Ironically, the latest victim of the dam proved Patrick Tierney, his son, who died 30 years later, falling from the tower spillway.
Preliminary work
construction dam dam was planned on the border between Arizona and Nevada in the narrow canyon.For draining the water away from the construction point 4 have been created tunnel.It should be noted that the total length of 4.9 km.In 1931 began the construction of the tunnels themselves.Their decoration was created out of concrete with a thickness of 0.9 m, whereby the effective diameter culverts reached 15.2 m.
Tunnels after construction had been partially covered "plugs" in concrete and sometimes used to resetexcess water.The fact that the spillway is not through the body of the dam itself, and through tunnels, which are located in the cliffs, gives the stability of the entire structure.
Construction of dams, caissons
to prevent the likelihood of flooding, as well as isolation of the construction site of the dam was built 2-caisson.The upper dam construction began in 1932, although at that time allocating tunnels were not completed.
to ensure safe operation before construction were carried out various activities to rid the canyon walls of rocks and loose stones lying: they are first undermined dynamite, and then thrown off downward.
building concrete dam
In the first concrete foundation of the dam was flooded in 1933.For its production it was discovered the next field of non-metallic materials.In addition, especially for the concrete plants were built.
Since the operation of such scale never before made (it is worth noting that none of the dam of the world could not compare with the scope of the construction), several technical solutions used in the process were truly unique character.For example, one of the problems appeared cooling concrete.In this way, instead of a solid monolith Hoover Dam was built as a series of interconnected pillars in the form of trapezoids.This enabled the excessive heat that is released during solidification of the mixture dissipated.
Engineers realized that if Hoover Dam will be built as a monolith, the concrete cooling to the required temperature would take 125 years.In this way could cause cracks, and later it would entail the destruction of the dam.In addition, each form to accelerate the cooling of the concrete layers contained the cooling system of metal pipes inch, which receives chilled river water.I must say that the hardening of concrete and today is not completed.
Power
Create pit for hydropower plants was carried out with rytёm pit, which was intended for the base of the dam.The required earthworks were completed in 1933, the same year the first concrete was poured into the room power.
first electricity generator station was produced in 1936.After 25 years in the modernization of the station was launched more additional generators.At the present moment here produce electricity generators seventeen, whose maximum power 2074 MW.
role of power today
Power plays a very important role in maintaining the balance of power in the western US.From energy consumption depends on the adjustment of each load generators that regulated the distribution station, located in Phoenix.It is interesting that until 1991 used to control the system in manual mode;It was further carried out computerization of the system.
Architecture
Initially, the project assumed a very simple architectural design and building of hydroelectric dams.It was assumed that the outer side of the dam is ordinary wall, framed by a balustrade on top, created in the Gothic Revival style.While building power plants in general should not be different from the simple factory shop.
many contemporaries proposed project has been criticized for its excessive simplicity, which, in their opinion, did not meet the epochal nature of which bore the Hoover Dam.As a result, the project was invited to rework the Los Angeles architect Gordon Kaufman.He was able to rework the project by completing the exterior of these buildings in the Art Deco style.As a result, the upper part of the dam was adorned with turrets that "grow" right out of the dam.Moreover, he posted a clock on the spillway towers.Some of them are show Mountain Time, and the second - the North American Pacific Time.
name dam
Initially Hoover Dam was erected in Boulder Canyon, consequently, in the official documents it was called "Boulder Dam".At the same time the official opening of the building, Ray Wilbur, United States Secretary of the Interior Ministry announced that the facility will be named in honor of US President Hoover.That statement continued Wilbur tradition Assigned Names Presidents of Major Dams United States.The US Congress has approved the official name in 1931.
year later, Hoover lost the election to Franklin Delano Roosevelt, the Democratic candidate.After Roosevelt took office, the US administration has proposed changing the name of the dam on the "Boulder Dam".On this occasion, a formal decision was not taken, but of all the tourist guides and official documents of those years, the name Hoover lost.
2 years after the death of Roosevelt, Jack Anderson, a California congressman introduced a draft structure for the return of the Hoover name.The corresponding bill signed by the president, and since the dam was named "Hoover Dam".
Transport value
the dam until 2010 held the highway 93 that runs in the meridional direction and bound the Mexican border with Arizona.Part of the highway, which is adjacent to the dam, the volume of the transmitted transport and highways did not match.The road in each direction has only one band, and her down to the dam serpentine includes several narrow and steep turns, places with very poor visibility.In addition, the road is subject to frequent landslides.
should be noted that after the terrorist attacks in 2001 were limited to traffic through the dam.Some types of vehicles before passing undergo mandatory inspection to avoid transportation of explosives, the rest are examined only occasionally.
In 2010, about Hoover Dam Bridge opened Mike O'Callaghan.It has significantly increased the capacity of the highway.
impact on nature
Formation of Lake Mead and the construction of this dam has had a significant impact on the Colorado River, its water regime, and especially on its ecosystem.Thus the pernicious influence of many different large dams.For 6 years the construction of the dam and reservoir filling water almost reached the delta.
Construction stopped frequent floods, which differ Canyon of the Colorado River.But it posed a direct threat to the right number of species of plants and animals that have adapted to regular flooding.The construction of the dam downstream of reduced fish populations.At the present moment four fish species are threatened with extinction.
Even today, in the area near Lake Mead, you can see the trail from the top of the water level, which was reached in 1983.This was due to an unusually large amount of rain that fell as a result of the effect of El Nino in the western United States.
image of this dam was used in a variety of works of art.For example, a dam was mentioned in the book "one-storey America" by Ilf and Petrov, in the movie "Universal Soldier" and "Transformers" as well as in the animated film "Beavis and Butt-head."
