The Hoover Dam is a hydraulic structure and hydroelectric power plant in the United States. It was built 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 states of Nevada and Arizona. It was named in honor of the 31st President of the country - Herbert Hoover, who played an important role in its construction. The construction of the dam took place in 1931-1936.
Hoover Dam is administered by a division of the US Department of the Interior, the Bureau of Reclamation. It is one of the most famous attractions in Las Vegas.
Backstory
Before the construction of the dam, the Colorado (river) often showed its violent temper. During the period of snowmelt in the mountains, it very often flooded the lands of farmers who were downstream. The planners believed that the construction of dams would help smooth out fluctuations in the river's level. In addition, this reservoir was expected to boost the development of irrigated agriculture and becomesource of water supply for many areas of Southern California.
One of the main obstacles to the implementation of this project was the doubts of the representatives of the states that were in the Colorado basin. The river, or rather its water resources, had to be fairly distributed among consumers. It was thought that California, with all its influence and finances, would lay claim to the bulk of the reservoir's water reserves.
Because of this, a commission was set up that included one representative from each state concerned, as well as a representative from the federal government. The result of its activities was the signed Colorado River Convention. It fixed the ways of distribution of water resources. This opened the way for the construction of the dam.
The construction of a hydraulic structure of this magnitude required the attraction of substantial funds from the state budget. The funding bill was not immediately approved by the White House and the US Senate. In 1928, Calvin Coolidge signed a bill giving the go-ahead for the implementation of this project. The first appropriations for the construction were allocated only after 2 years. Herbert Hoover was already president then.
The plan was to build a dam in Boulder (Canyon of the Colorado River). And although it was finally decided to build it in the Black Canyon, this project became known as the Boulder Canyon Project.
Construction
The construction of dams in a row was entrusted to several companies. Among them: Six Companies, Inc., Morrison-Knudsen Company; Utah Construction Company; Pacific Bridge Company; Henry J. Kaiser & W. A. Bechtel Company; MacDonald & Kahn Ltd., J. F. Shea Company.
Workers
Thousands of workers took part in the construction (in 1934 the maximum number was 5251 people). According to the terms of the contract, the employment of Chinese workers was not allowed, and the total number of black mercenaries did not exceed 30 people, while they were employed in the least paid jobs. It was supposed that a small town would be built near the dam for construction workers, but the schedule was redesigned in favor of increasing the number of jobs and speeding up the process (to reduce unemployment, which was the result of the Great Depression). Because of this, by the time the first mercenaries arrived, the city was not yet ready, and the builders of the dam spent the first summer in the camps.
Dangerous working conditions and delayed housing led to a strike that took place in 1931. At the same time, the workers were dispersed with the use of force (the police used batons and weapons). However, it was decided to accelerate the pace of construction of the town, and in the spring of the following year, people moved to permanent dwellings. During construction, gambling, prostitution, and the sale of alcoholic beverages were banned in Boulder City. The last ban here remained until 1969. Gambling is not allowed here to this day, making Boulder City the only city in Nevada that has such a ban.
Working conditions
The Hoover Dam, the photo of which is presented in this article, was built in the most difficult conditions. Some part of the work took place in the tunnels, where the workers suffered from carbon monoxide, which was in abundance here (some builders died or became disabled as a result). The employer then stated that the deaths were the result of pneumonia, and he was not responsible. At the same time, the construction of this dam was the first construction site where protective helmets were issued to workers.
During the construction of the dam (dam), a total of 96 people died. The very first of these was the topographer J. Tierney, who drowned in Colorado at the end of 1922, choosing the best places for construction. Ironically, the last victim of the dam was Patrick Tierney, his son, who died 30 years later after falling from a spill tower.
Preliminary work
The construction of a dam dam has been slated on the border between Arizona and Nevada in a narrow canyon. To divert water away from the construction site, 4 tunnels were created. It should be noted that their total length was 4.9 km. In 1931, the construction of the tunnels themselves began. Their decoration was created from concrete, the thickness of which was 0.9 m, due to which the effective diameter of the conduits reached 15.2 m.
Tunnels after completion of construction were partially blocked by "plugs" of concrete and are used in places to dump excess water. The fact that the spillway does not occur through the body of the dam itself, but through tunnels that are located in the rocks, givesstability of the whole structure.
Construction of caisson dams
To prevent possible flooding, as well as to isolate the construction site, 2 caisson dams were built. The upper dam began to be built in 1932, although at that time the diversion tunnels were not completed.
To ensure the safety of work, before the start of construction, various measures were taken to clear the walls of the canyon from rocks and loose stones: they were first blown up with dynamite, and then thrown down.
Construction of a concrete dam
The first concrete was poured into the base of the dam in 1933. For its production, the nearest deposits of non-metallic materials were discovered. In addition, concrete plants were built specifically for this.
Because no work of this scale had ever been done before (it's worth noting here that no dam in the world could match the scale of this construction), several of the technical solutions used in the process were truly unique. For example, one of the problems was the cooling of concrete. Due to this, instead of a solid monolith, the Hoover Dam was built as a series of interconnected columns in the form of trapezoids. This allowed the excess heat that was released during the solidification of the mixture to dissipate.
Engineers realized that if the Hoover Dam were built as a monolith, it would take 125 years for the concrete to cool to the required temperature. Due to this, cracks could appear, and in the future this would entail the destruction of the dam. ExceptIn addition, each form to speed up the cooling of the concrete layers contained a cooling system of metal inch pipes, which received chilled river water. It must be said that the curing of concrete has not been completed today.
Power plant
The excavation of the hydroelectric power station was carried out along with the excavation of a foundation pit, which was intended for the foundation of the dam. The necessary earthworks were completed in 1933, and the first concrete was poured into the power station that same year.
The first electricity was generated by the station's generators in 1936. After 25 years, in the course of the modernization of this station, other additional generators were launched. At the moment, electricity is generated here by seventeen generators, the maximum capacity of which is 2074 MW.
The role of the power plant today
The power plant plays a very important role in balancing energy consumption in the western US. Energy consumption determines the load adjustment for each of the generators, which is regulated by the distribution station located in Phoenix. Interestingly, until 1991, a manual control system was used; later the system was computerized.
Architecture
The original project assumed a very simple architectural solution for the building of the hydroelectric power station and the dam. It was assumed that the outer side of the dam would be an ordinary wall, framed on top by a neo-Gothic balustrade. While the power plant building is not at allshould have been different from a simple factory floor.
Many contemporaries criticized the proposed project for its excessive simplicity, which, in their opinion, did not correspond to the epoch-making nature of the Hoover Dam. As a result, Los Angeles architect Gordon Kaufman was invited to redesign the project. He managed to rework the project by completing the exterior of these structures in the Art Deco style. As a result, the upper part of the dam was decorated with turrets that “sprouted” directly from the dam. In addition, he placed clocks on spillway towers. One of them shows Mountain time, and the second - Pacific North American time.
dam name
The original Hoover Dam was to be built in Boulder Canyon, hence the official name of it "Boulder Dam". At the same time, at the official opening of this building, Ray Wilbur, Secretary of the US Department of the Interior, announced that this building would be named after US President Hoover. With this statement, Wilbur continued the tradition of naming the largest dams in the United States after presidents. The US Congress approved this official name in 1931.
A year later, Hoover lost the election to Franklin Delano Roosevelt, the Democratic nominee. After Roosevelt took office, the US administration proposed changing the name of the dam to Boulder Dam. No official decision was made on this occasion, but Hoover's name disappeared from all tourist guides and official documents of those years.
In 2 yearsAfter Roosevelt's death, Jack Anderson, a California congressman, presented a proposal to return the Hoover name to the building. The corresponding bill was signed by the president, and since that moment the dam has been called the Hoover Dam.
Transport value
Until 2010, Highway 93 passed through the dam, which ran in the meridional direction and connected the Mexican border with the state of Arizona. The part of the highway, which was adjacent to the dam, did not correspond to the volume of traffic and the highway. The road has only one lane in each direction, and its serpentine going down to the dam includes several narrow and sharp turns, places with very poor visibility. In addition, the road is prone to frequent landslides.
It should be noted that after the terrorist attack in 2001, traffic through this dam was restricted. Some types of vehicles are subject to mandatory security checks before passing through to exclude explosives, while others are only periodically inspected.
In 2010, the Mike O'Callaghan Bridge opened near the Hoover Dam. He significantly increased the capacity of this highway.
Influence on nature
The formation of the Mead Reservoir and the construction of this dam had a tangible impact on the Colorado River, its water regime, and especially on its ecosystem. Many large dams have such a detrimental effect. During the 6 years of the construction of the dam and the filling of the reservoir, the water of the delta practically did not reach.
Building stopped frequent floods,which distinguished the canyon of the Colorado River. But this directly threatened a number of plant and animal species that have already adapted to regular flooding. The construction of a dam downstream has reduced the fish population. At the moment, 4 species of fish are under the threat of complete extinction.
Even today in the area near Mead Reservoir, you can see the trace of the upper water level, which was reached in 1983. This was due to unusually high rainfall, which fell as a result of the El Niño effect in the western United States.
The image of this dam has been used in various works of art. For example, the dam was mentioned in the book "One-Storied America" by Ilf and Petrov, in the films "Universal Soldier" and "Transformers", as well as in the animated film "Beavis and Butt-Head".
