The Hoover Dam is a hydraulic structure and hydroelectric station in the USA. It was built downstream 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 after the 31st president of the country - Herbert Hoover, who played an important role in its construction. The construction of the dam occurred in 1931-1936.
Hoover Dam is managed by the US Department of Homeland Bureau of Land Reclamation. It is one of Las Vegas most famous attractions.
Background
Before the construction of the Colorado Dam (river), it often demonstrated its wild temper. During the snowmelt in the mountains, it very often flooded the lands of farmers who were downstream. Designers believed that dam construction would help smooth out river level fluctuations. In addition, it was expected that this reservoir would push the development of irrigated agriculture and become a source of water for many areas of Southern California.
One of the main obstacles to the implementation of this project was the doubts of state representatives who were in the Colorado basin. The river, or rather its water resources, should have been fairly distributed among consumers. It was thought that California, with all its influence and finances, would claim the bulk of the reservoir’s water reserves.
Because of this, a commission was created that included one representative from each interested state, as well as a representative from the federal government. The result of its activities was the signed Colorado River Convention. It fixed ways of distributing water resources. This paved the way for the construction of the dam.
The construction of a hydraulic structure of this scale 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.
The plan included the construction of a dam in Boulder (Colorado River Canyon). And although it was finally decided to erect it in the Black Canyon, this project became known as the Boulder Canyon Project.
Construction
Several companies were entrusted with the construction of dams in a row. Among them: Six Companies, Inc., Morrison-Knudsen Company; Utah Construction Company; Pacific Bridge Company; Henry J. Kaiser & WA Bechtel Company; MacDonald & Kahn Ltd., JF Shea Company.
Workers
Thousands of workers took part in the construction (in 1934, the maximum number was 5, 251 people). According to the terms of the contract, Chinese workers were not allowed to work, and the total number of black mercenaries did not exceed 30 people, while they were busy at the lowest paid jobs. It was assumed that a small town would be built near the dam for builders, but the schedule was revised in favor of increasing the number of jobs and accelerating 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 a delay in the commissioning of 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, the pace of construction of the town, it was decided to accelerate, and in the spring of next year, people moved to already permanent homes. During the construction period, gambling, prostitution, and the sale of alcohol were prohibited in Boulder City. The last ban remained here until 1969. Gambling is not allowed here to this day, which makes Boulder City the only city in Nevada that has a similar ban.
Working conditions
The Hoover Dam, the photo of which is presented in this article, was built in difficult conditions. Some of the work took place in the tunnels, where workers suffered from carbon monoxide, which was abundant here (some builders died or became disabled as a result of this). 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 on which protective helmets were issued to workers.
During the construction of the dam (dam), a total of 96 people died. The very first of them was the topographer J. Tierney, who drowned in Colorado at the end of 1922, choosing the best place for construction. Ironically, the last victim of the dam was Patrick Tierney, his son, who died 30 years later, falling from a spillway tower.
Preliminary work
The construction of the dam dam was scheduled on the border between Arizona and Nevada in a narrow canyon. 4 tunnels were created to divert water away from the construction point. It is worth noting 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 useful diameter of the water pipes reached 15.2 m.
The tunnels after completion of construction were partially blocked by “traffic jams” made of concrete, and in some places they are used to discharge excess water. The fact that the spillway does not occur through the body of the dam itself, but through the tunnels located in the rocks, gives stability to the entire structure.
The construction of dykes
To prevent possible flooding, as well as isolating the construction site, 2 caissons were built. The upper dam began to be built in 1932, although at that time the outlet tunnels were not completed.
To ensure the safety of work before the construction began, various measures were taken to clean the walls of the canyon from rocks and loose stones: they were first blown up with dynamite and then dropped down.
Concrete dam construction
The first concrete was poured into the foundation 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.
Since work of this magnitude has never been done before (it is worth noting that no dams of the world could compare with the scope of this construction), several technical solutions used in the process were truly unique. For example, one of the problems was cooling the concrete. Due to this, instead of a solid monolith, the Hoover Dam was built as a series of interconnected columns in the form of trapezoidal structures. This allowed the excess heat that was released during the solidification of the mixture to dissipate.
Engineers realized that if the Hoover Dam would be erected as a monolith, then it would take 125 years to cool the concrete to the required temperature. Due to this, cracks could appear, and in the future this would entail the destruction of the dam. In addition, each form to accelerate the cooling of concrete layers contained a cooling system of metal inch pipes, which received chilled river water. I must say that the hardening of concrete is not completed today.
Power station
The creation of a pit for a hydroelectric power station was carried out along with digging a pit, which was intended for the foundation of the dam. The necessary excavation work was completed in 1933, in the same year the first concrete was poured into the premises of the power plant.
The first electricity was generated by the station's generators in 1936. 25 years later, during the modernization of this station, other additional generators were launched. At the moment, seventeen generators are generating electricity here, with a maximum capacity of 2074 MW.
The role of power plants today
A power plant plays a very important role in maintaining the balance of energy consumption in the western United States. Adjusting the load on each of the generators depends on energy consumption, which is regulated by a distribution station located in Phoenix. Interestingly, until 1991 a manual control system was used; later computerization of this system was carried out.
Architecture
The initial design involved a very simple architectural solution for the hydroelectric building and dam. It was assumed that the dam's outer side would be an ordinary wall framed on top with a balustrade created in a neo-Gothic style. While the building of the power plant should not have been different from a simple factory floor.
Many contemporaries proposed the project was criticized for its excessive simplicity, which, in their opinion, did not correspond to the epochal nature worn by the Hoover Dam. As a result, Los Angeles architect Gordon Kaufman was invited to remake 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 "grew" directly from the dam. In addition, he placed the watch on the spillway towers. Some of them show Mountain Time, and the second - Pacific North American Time.
Dam name
Initially, the Hoover Dam was to be erected in the Boulder Canyon, therefore, in official documents it was called the “Boulder Dam”. At the same time, at the official opening of this construction, Ray Wilbur, the US Secretary of the Ministry of Internal Affairs announced that this building will be named in honor of US President Hoover. With this statement, Wilbur continued the tradition of naming presidents to the largest US dams. The U.S. Congress approved this official name in 1931.
A year later, Hoover lost the election to Franklin Delano Roosevelt, a Democratic candidate. After Roosevelt took office, the US administration proposed changing the name of the dam to "Boulder Dam." No official decision was made on this, but Hoover’s name has disappeared from all the tourist guides and official documents of those years.
Two years after the death of Roosevelt, Jack Anderson, a California congressman, presented a project to return the building to the name of Hoover. The corresponding bill was signed by the president, and from that moment the dam bears the name "Hoover Dam."
Transport value
Until 2010, Highway 93 ran along the dam, which ran along the meridional direction and connected the Mexican border with the state of Arizona. The part of the highway that was adjacent to the dam did not correspond to the volume of transport allowed and the highway. The road has in each direction only one lane, and its serpentine descending 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 of 2001, traffic through this dam was limited. Before traveling, some types of vehicles are subject to mandatory inspection to exclude the transport of explosives, while others are inspected only periodically.
In 2010, the Mike O'Callaghan Bridge opened near the Hoover Dam. He significantly increased the throughput of this highway.
