The Hoover Dam in the United States is a large conventional dammed-hydro facility, with an installed capacity of 2,080 MW. It is a megastructure built upon the Colorado River providing electricity to more than 1.3 million people in America. In all sense, the Hoover Dam was an incredible feat achieved by mankind during the 20th century, yet its magnificent history overshadows the grueling details of its construction.
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona.
To put it simply, the construction of Hoover Dam was a kind of devil’s bargain in the desert.
In the early 20th century, the U.S has expanded from coast to coast yet many areas in the southwest region were deprived of water resources. Though the canals built in the Colorado River did support the problem, yet its regular flooding and erratic flow made it an unreliable source for agricultural practices. Along with this, the growing industrialization in the area also means the growing need for energy. Thus to solve these problems, in 1922, the Bureau of Reclamation decided to build a massive hydroelectric dam in the area.
On December 21, 1928, President Coolidge signed the bill authorizing the dam. The Boulder Canyon Project Act appropriated $165 million for the project along with the downstream Imperial Dam and All-American Canal. Once the water rights were ensured, the Bureau determined that the black canyon’s narrow gorge would be the best location to build the dam.
The monolithic dam would be thick in the bottom and thin at the top, and face converse towards the water. The wedge-shaped dam would be 660 ft (200 m) thick at the bottom, narrowing to 45 ft (14 m) at the top, leaving room for a highway connecting Nevada and Arizona. A giant workforce was recruited to build the massive structure.
A year later when the Great Depression struck, thousands of people looking for jobs converged to the site. The workers were provided with makeshift camps called ‘Ragtown’ but the lack of basic amenities and scorching heat of the area killed several workers within the first few months. Thus, the government build the model city in 1930 known as Boulder City. The still-thriving city provided surplus supplies and included the state-of-the-art hospital.
Before the construction of the dam could begin, the Colorado River needed to be diverted away from the site. To allow the river to re-route, four diversion tunnels were driven through the canyon walls and created 17-meter tall tubes. The almost 5 kilometers long tunnels diverted roughly 5600 cubic meters of water per second. This process was extremely tough to accomplish as the already scorching heat of the area made it nearly impossible for the workers to complete the task and several died of heatstroke. But this was nothing against the task lying ahead of them.
In the next two years, by 1932, the river has been successfully rerouted and now the next task was to clear over 1 million cubic meters of loose rock. Here come the ‘high scalers’, they suspended from the top of the canyon with ropes, and climbed down the canyon walls, and removed the loose rock with jackhammers and dynamite. The process took the lives of many workers and the death from falling objects was an everyday event of the construction site. These death-defying high scalers became a media sensation especially after an incident when one of them saved a government officer from falling off the cliff.
The construction become a magnet for tourists and the high scalers were prime attractions. To protect themselves from falling objects, these workers soaked their hats in tar to allow them to harden and shield them from any skull damage. Many companies ordered thousands of what were called “hard-boiled hats” and encouraged their use.
After the clearance was complete, it was finally time to pour in concrete and build the dam. This required pouring in around 6.6 million tons of concrete which would have taken a very long time to harden if poured all at once. Thus, they built interlocking blocks of various sizes with each containing steel pipes with cold flowing water. The concrete was poured into these blocks to speed up the cooling process. A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased in May 1935.
The final structure was completed 2 years ahead of the schedule and it was the tallest manmade structure in the world. Yet, what remains hidden in the cost of the speed that took hundreds of lives. Over one hundred workers died during the construction and several others were fatally injured. Many died of pneumonia and others by injuries. The reservoir also destroyed communities like St. Thomas and tampered Colorado’s ecosystem.
The monuments at the top of Hoover Dam to its engineers, and laborers is the small acknowledgment of the incredible feat they have achieved.