The Construction of the Hoover Dam
Published 20 Dec 2016
The Hoover dam is a concrete-made dam located in the Colorado River on the boundary between Nevada and Arizona. It was named after President Herbert Hoover that was very influential in the construction of the dam. The construction of this project started in 1931 and was finished in 1935. The objective of the construction of this dam was multi-purpose. First was to control the flooding in the nearby counties along the Colorado River. Next was to provide irrigation to agricultural lands of California and Arizona. And last was to provide hydro-electric power to nearby regions. It was measured to be 726 feet high and 1,244 feet long. The base of this dam is 660 feet thick that is 60 feet longer than 2 football fields placed end-to-end.
The Hoover dam is one of the modern day construction projects that show a very creative and ingenious side of a construction corporation. The company named Six Companies Inc. was the lucky construction company that was given the job to do this state-of-the-art dam project. The construction company was called the Six Companies Inc. because in reality, it was a consortium of six construction companies that merged and worked together for this project. The six companies included were J.F. Shea Co., Morrison-Knudsen Co., MacDonald & Kahn Ltd., Pacific Bridge Co., Utah Construction Co., and joint venture of Henry J. Kaiser, Warren Brothers & W.A. Bechtel Co.
These construction companies merged together for this project because of the reason that no construction company could produce the required $5,000,000 performance bond. Another company was contracted to assist the refrigeration needs of the concrete during the pouring and curing stage of the construction. The Union Carbide Corporation was contracted for this job.
The onset of the Great Depression in 1931 paved way to massive migration of unemployed workers from Las Vegas and earned them jobs in building this historical project. The workers and their families were temporarily housed in camps like Ragtown as the work in the town advanced. Then after the construction of Boulder City, the workers were moved from Ragtown to this place where they stayed until the completion of the dam.
During the construction, two cofferdams were built to protect the construction area from flooding. The upper cofferdam was constructed in September 1932, although the persion of the Colorado River was not yet finished. A temporary dike secluded the cofferdam from the river. The construction of the project was boosted when the Arizona tunnels and the persion of the Colorado River were completed. After the construction of the cofferdams, the excavation for the foundation of the dam started. Loose materials were removed so that the dam would rest on solid rock. The excavation for the foundation of the dam was completed in June 1933. Approximately 1,500,000 square yards of loose materials was removed that includes materials from the canyon walls. The people who were assigned to remove the loose rocks from the canyon walls were called high-scalers. These high-scalers were suspended from the top of the canyon using ropes and they used jackhammers and dynamites for removing the loose rocks on the canyon walls.
Four persion tunnels were constructed through the canyon walls to pert the river flow around the construction site. Two were built on the Arizona side and the other two were built on Nevada side. The diameter of these tunnels was approximately 56 feet. The total aggregated length of these tunnels was around 16,000 feet. The work on the tunnels began at the lower entrance of the Nevada tunnels in May 1931. Afterwards, the work on the tunnels at the Arizona soon started. Lining of the tunnels with concrete started in March 1932. The concrete base for the tunnels was first poured. In order to execute this efficiently, gantry cranes, moving along the rails positioned through out the entire length of each tunnel, were utilized to pour the concrete. The sidewalls were then constructed. Moveable segments of steel forms were employed. The overheads were constructed last. The thickness of the concrete was measured to be 3 feet, hence reducing the final tunnel diameter to only 50 feet. The entrances to the two outer tunnels were sealed after the completion of the dam.
On June 6, 19333, the first concrete block was positioned into the dam. Because of the fact that no construction as big as the Hoover dam was done before, a lot of the procedures and techniques employed in the construction of the dam were untested. The uneven cooling and contraction of the concrete posed a very big problem for the construction engineers. The engineers of the project calculated that if one continuous pours of concrete was done to build the dam; it would take around 125 years for the concrete to cool down. It would definitely result to stresses on the concrete and therefore create cracks on the concrete walls. The solution to this dilemma was to build a series of trapezoidal pillars interlocking with each other.
Every concrete pour was no more than half-foot deep, which ensured that no construction would be accidentally buried alive in the concrete. To quicken the cooling of the concrete, cooling coils were contained in each concrete pillar. Water from the Colorado River was circulated along these cooling coils to help disperse the heat from the concrete. Overall, the Hoover dam required more than 3,250,000 cubic yards of concrete for its construction. The base of the Hoover dam alone needed 230 inpidual massive concrete blocks. Five foot high blocks of different width, varying from 25 square feet on the downstream side to 60 square feet on the upstream side constituted the dam. The columns or pillars of concrete were connected together with a system of alternating horizontal and vertical plots.
The excavation for the power plants was performed simultaneously with the excavation of the foundation of the dam. The excavation for the U-shaped construction situated at the downstream side of the dam was completed in 1933. After the completion of the excavation, seventeen turbine-generators were installed at this powerhouse. These generators provided a maximum hydro-electric power of 2,074 Megawatts to the nearby region of the Colorado River. The first transmission of electricity happened on October 26, 1936 when the power plants provided electricity to Los Angeles, California that was 266 miles away from the Colorado River.
The original plans for the front wall of the dam and the powerhouse comprised of simple concrete wall with gothic-inspired barrier and the plant that appear to be a warehouse. But many criticized the plan to be too simple for a ground-breaking project. Gordon Kaufmann was assigned to do the redesign of the exteriors. He restructured the buildings and employed a stylish Art deco design to the project, with structured turrets on the face of the dam.
The construction was finally completed in 1935. The total cost of the entire project was $165 million and took four and half years to complete. A total of 4.4 million cubic yards of concrete was used for the whole project. U.S. President Franklin Roosevelt dedicated the project on September 30, 1935 that drew massive crowds. He called the project as an Engineering victory for the American ingenuity.
But sadly, there were 112 deaths related with the construction of the Hoover dam. The first person killed in the construction was J. G. Tierney. He drowned while he was finding a perfect spot for the dam. His son P. W. Tierney also died in the construction of this dam. A total 96 deaths happened on the construction site.
There was a controversy with the naming of this dam. The dam was originally planned to be constructed in the Boulder Canyon. This was the reason why the dam was sometimes called the Boulder dam. But it was moved to the Black Canyon for better impoundment. At the official start of the project construction, Interior Secretary Ray Wilbur declared that the new dam would be named Hoover dam in honor of the U.S. President Herbert Hoover, who was in seat when the construction of the project started. Secretary Wilbur adhered to the tradition of naming the important dams after the U.S. President who was in seat when the construction started. The name Hoover dam became official when the U.S. Congress passed an act on February 14, 1931. But during the 1932 U.S. Presidential elections, Hoover lost to Franklin Roosevelt for the Presidential seat. Roosevelt took his seat on March 4, 1933, and he placed Harold Ickes as Secretary of Interior.
Ickes sought for the removal of Hoover’s name from the Boulder dam project. He made a memorandum to the Bureau of Reclamation renaming the project, the Boulder dam. After few years, all references to the Hoover dam disappeared in favor of the Boulder dam. But after the death of President Roosevelt 1945 and the retirement of Harold Ickes in 1946, California Congressman Jack Anderson submitted a resolution on March 4, 1947 to return the name of the Boulder dam back to Hoover dam. This resolution passed the House on March 6, 1947 and the Senate on April 23, 1947. President Harry Truman signed the new law on April 30, 1947 stating the restoration of the name Hoover dam to the dam constructed on the Colorado River in Black Canyon.
The Hoover dam is a National Historic Landmark in the United States. It attracts millions of tourists each year. And currently, the Hoover dam is one of the busiest U.S. National Park. It also serves as a passage for U.S. Route 93.
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- Construction of Hoover dam: A Historic account prepared in cooperation with the Department of Interior. KC Publications, 1976.
- “Historic Construction Company Project – Hoover dam.” 2006. Construction Company.com. 1 December 2007 < http://www.constructioncompany.com/historic-construction-projects/hoover-dam/>.
- Stevens, Joseph E. Hoover dam: An American Adventure (Paperback). University of Oklahoma Press, 1990.