Why Was the Hoover Dam Built? Planning the Dam Plans for the dam took over 30 years of research, lobbying, organization and design. Construction of the Hoover Dam After surveying and choosing Black Canyon as the spot to build the dam, explosives were used to blast away the sides of the canyon for construction. DirtStories is all about the people and companies who build the construction industry.
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Snow Removal Rentals. Products for Rental Companies. DOZR Marketplace. DOZR Account. Ninety-six of the deaths occurred during construction at the site. Of the fatalities, 91 were Six Companies employees, three were BOR employees, and one was a visitor to the site, with the remainder employees of various contractors not part of Six Companies.
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,, saw between 10, and 20, unemployed descend on it. Work on the upper cofferdam began in September , even though the river had not yet been diverted. The cleared, underlying rock foundation of the dam site was reinforced with grout, called a grout curtain.
Holes were driven into the walls and base of the canyon, as deep as feet 46 m into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock. September 11, Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem.
Bureau of Reclamation engineers calculated that if the dam was built in a single continuous pour, the concrete would take years to cool, and the resulting stresses would cause the dam to crack and crumble.
Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square 15 m and 5 feet 1. The concrete was delivered in huge steel buckets 7 feet high 2. Officials ride in one of the penstock pipes of the soon-to-be-completed Hoover Dam. Water flowing over the spillways falls dramatically into foot-long m , foot-wide 15 m spillway tunnels before connecting to the outer diversion tunnels, and reentering the main river channel below the dam.
Student engineers stand atop one of the 2 million-pound hydroelectric generators for the dam at the General Electric factory in Schenectady, New York.
Simply put, the arch-gravity Hoover Dam curves upstream to direct water pressure outward and against the canyon walls.
While the dam is expected to last for centuries, engineers predict the structure could last for more than 10, years, surpassing most remnants of human civilization if humans were to disappear from the earth. We at Del Zotto Products hoped you enjoyed our journey through history. We have been in the concrete business for more than 50 years, providing the industry the highest level of service and the most advanced equipment systems. Stop by our office and contact us today. Skip to content. The U.
Reclamation Service, renamed the Bureau of Reclamation in , was created to design and build these systems. By this time, however, Reclamation's objective was changing and expanding.
Where agency efforts had focused on building dams and irrigation systems to supply water to small farms, Reclamation was now envisioning vast projects that would cover whole river basins and use the water to do more than irrigate agricultural fields. These new projects would also control floods, supply water to growing cities, and generate electricity to fuel industrial growth in a new West. The first of these great multipurpose projects would be a huge dam on the lower Colorado River.
Reclamation Service and the Bureau of Reclamation. The geographic area drained by a river and its tributaries is called a "basin. The canals and aqueduct in California receive water from the Colorado. This map shows only Reclamation's dams in the basin. Questions for Map 1. Trace the course of the Colorado River. Where does it start? Where does it end? There are two places where the river forms the boundary between two states.
Which states are they? Trace the boundaries of the Colorado River Basin. Which states are within the Basin? Which are in the Upper Basin and which are in the Lower Basin? Most of the water in the Colorado comes from melting snow in the Upper Colorado Basin. Most of the water is used in the Lower Colorado Basin. If you had to decide how much of the river's water each state could have, what factors might you consider?
If the states did not agree with what you recommended, who do you think should have the right to make a final decision? The river crosses the border into Mexico. How would you decide how much water Mexico could claim? Who could make that decision? How many dams can you find on the Colorado River? Hoover Dam was the first of those on the map.
Why do you think there are so many now? Before the building of Hoover Dam, the Colorado River was dangerous and unreliable. Melting snow in the mountains caused damaging floods during the late spring and early summer. Unpredictable flash floods could occur in any season. In , the Colorado River flooded rich, irrigated farmland in the Imperial Valley in southern California.
It caused enormous damage and permanently flooded thousands of acres. Reclamation engineers began to study the Colorado River soon after passage of the Reclamation Act in They were looking for places to build dams to store the water from the annual spring runoff, releasing it gradually during the summer for irrigation. By the early s, most people thought that building a big dam on the lower Colorado was the best way to store water to irrigate the low-lying valleys of Arizona and southern California and to protect them from floods.
By this time, too, developers in Los Angeles and other rapidly growing cities in Southern California had added their powerful support for the project. They saw the dam as a potential source of water and hydroelectric power for homes, businesses, and factories. In , the seven states of the Colorado River Basin met to decide how to divide the waters of the river.
Herbert Hoover, at that time the secretary of commerce for Republican President Calvin Coolidge, led the discussions. Most of the states were afraid California was going to get more than its fair share of the water.
Ultimately, they managed to agree on a document, called the Colorado River Compact. The compact also committed the U. Some states were not happy about the compact; Arizona did not ratify it until It did permit planning for the dam to proceed, however. Also in , congressional representatives from California introduced a bill to authorize Reclamation to build the big dam on the lower Colorado.
By this time, they were among the most knowledgeable and experienced dam builders in the world, but even they had never done anything this big. Hoover Dam would be the highest dam in the world, far taller than anything they had built so far. The lake it created would be the largest in the world. The proposed dam would be so tall and the pressure of the water it held back so great that many people were worried.
Others wondered whether the expected benefits would be enough to justify the enormous cost. Despite these questions, planning and design went forward. Six Companies was a group of some of the largest construction companies in the country.
They joined specifically for this project. The contract divided the work between Six Companies and Reclamation. Reclamation engineers designed the dam and created the hundreds of detailed plans and specifications that the contractors would follow.
If the work was consistent with the plans, they approved it for payment. They hired and housed the workers. They transported supplies to the dam site. They were responsible for keeping the project on schedule and within budget. The plan was for construction to start in the fall of , in the depths of the Great Depression, which had begun with the stock market crash of Herbert Hoover, now president, wanted to start work on the dam earlier, probably as a way to ease high unemployment.
Work actually began during the summer and continued around the clock until the dam was completed in , two years ahead of schedule. By this time, Franklin D. Roosevelt, a Democrat, had been elected president. The huge dam on the Colorado captured the imagination of journalists, authors, and filmmakers.
The New Deal was famous for using public works projects to put Americans back to work. In the early 21st century, almost a million visitors a year still come to see the great dam on the Colorado River. Hoover Dam is 1, feet long at the top. It is feet high from the lowest point of the foundation to the crest. The dam is feet thick at the base and tapers to 45 feet thick at the top. Its reservoir was the largest artificial lake in the world for decades and is still the largest in the United States.
Questions for Reading 1 1. Why did many people think something needed to be done to control the Colorado River? What sort of problems did the river create? What benefits would controlling it provide and to whom? Why were congressional representatives from the state of California the leading supporters of a big dam on the Colorado? Why do you think President Coolidge's secretary of commerce led the discussions leading up to the Colorado River Compact? What role might the federal government be able to play in making decisions like this?
An acre-foot is the volume of water that would cover one acre one foot deep. Why do you think they used a measure like that, rather than something like gallons? How many gallons of water are in an acre-foot? How much would that weigh?
What were some of the concerns people had about its construction? How did Reclamation and Six Companies divide the work on the dam? Department of the Interior, ; and Donald C. The guide included the instructions excerpted below: 15 Minute Course in Engineering Full? In fact there are still quite a few nice canyons along the Colorado River. You can take one of them—no one will miss it—maybe. And you will need to build some roads and erect a power line. At Boulder Dam they had to get the electricity from Los Angeles to build the dam which now sends electricity back to Los Angeles.
Sand and gravel—get quite a bit of this to mix with the cement; enough to make 4,, cubic yards of concrete. Pipe for ice water— miles of it will do. Plate steel for making pipes—88 million pounds—when you get into pipe 30 feet in diameter, you have to make your own. Structural steel, nuts, bolts—and other stuff like that—18 million pounds. Assorted steam shovels, etc. Make them each 56 feet in diameter, then line them with three feet of concrete. When you finish you will have 3 miles of tunnel 50 feet in diameter.
At the other end of the tunnels build another cofferdam to keep the water from backing up, pump the puddles out from between, and there you have it—a dry spot in the river, with the stream running right around it, through the tunnels. Lower several hundred men from the top on ropes and let them drill the cliffs full of holes. Stuff the holes with dynamite, and blast it away. Repeat as necessary. Better do that right now. Build a platform so spectators can watch, and dig down about feet from the river bed to bed rock, removing all loose material as you go.
You are now ready to install the main portion of the dam. Concrete has a nasty habit of cracking. The lime in cement causes it to get hot when it is mixed with water. Obviously you must not allow this to happen when you are building a dam. If cracks were to appear in your dam it might cause severe criticism from people living below the dam—or from their heirs.
It would take years for all that concrete in the dam to cool under normal conditions.
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