Would you really want a dam named after you? I wonder how Herbert Hoover would have felt if he knew a big dam was named for him? Anyway, Hoover Dam, also known as Boulder Dam is a huge arch-gravity dam in the Black Canyon of the Colorado River. It was built during the Great Depression, between 1931 and 1935. One of the most important contributions of this project, apart from the dam itself, was the formation of the precursor to the world’s largest HMO, the Kaiser Health Plan.
It was dedicated on September 30, 1935, by President Franklin Roosevelt. The dam was created to create flood control, provide irrigation, and produce hydroelectric power. Congress authorized the project in 1928. The winning bid was a consortium of companies called Six Companies Inc. and began building in 1931. A concrete structure of this magnitude had never been built before. Some of the techniques were unproven at the time.
But despite awful summer conditions, and the lack of support facilities near the site, the Six Companies finished more than two years ahead of schedule. The dam’s generators provide power for California, Nevada, and Arizona. Nearly a million visitors make the journey to Hoover Dam each year. The Dam created the largest reservoir by volume in the U.S. It sits only thirty miles southeast of Las Vegas. It is a National Historic Landmark.
The dam is named for our 31st President, Herbert Hoover. For the dam, more importantly, he was the Secretary of Commerce in 1925 when the dam was first proposed. Hoover, himself, preferred to use the name, “Boulder Dam” rather than his own name. And despite widespread use of the term, Boulder Dam, it was never an official name of the dam.
The chief design engineer for the Bureau of Land Management was John Savage. A total of 96 workers died during the construction of the dam. There are no workers buried in the concrete dam. During the Depression, thousands of men came here to look for work. Many found it.
Here are a few statistics. The dam weighs 6,600,000 tons, with a pressure of 45,000 pounds per square foot at the base of the dam. The dam itself is 3 and one-quarter million cubic yards of concrete. I find that difficult to imagine. Placed on an ordinary city block, it would rise higher than the Empire State Building. The principal materials, all of which were purchased by the federal government, were:
•reinforcement steel, 45,000,000 pounds;
•gates and valves, 21,670,000 pounds;
•plate steel and outlet pipes, 88,000,000 pounds;
•pipe and fittings, 6,700,000 pounds or 840 miles;
•structural steel, 18,000,000 pounds;
•miscellaneous metal work 5,300,000 pounds.
The dam took 5 years to complete. A total of 21,000 men worked on the dam with an average of 3,500 and a maximum of 5,218 daily, which occurred in June 1934. The average monthly payroll was $500,000.
Curiously, this is how the river was diverted to build the dam. The river was diverted around the dam site through four 50-foot-diameter tunnels, two drilled through the canyon walls on each side of the river. The tunnels, with a total combined length of 15,946 feet, or about three miles, were excavated to 56 feet and lined with three feet (300,000 cubic yards) of concrete. They could carry over 200,000 cubic feet – more than 1.5 million gallons – of water per second! The river was first diverted through the two Arizona tunnels on November 14, 1932.
How are the tunnels used now? The inner tunnels were plugged with concrete approximately one-third their length below the canyon wall inlets, and the outer tunnels were plugged approximately halfway. The two inner tunnels now contain 30-foot-diameter steel pipes (penstocks) which connect the intake towers in the reservoir with the powerplant and canyon wall outlet works. The downstream halves of the two outer tunnels are used for spillway outlets.
The bigger question now is whether or not such a dam could be built today. The collision of the need for water and hydroelectric power versus the environmentalists. I am not sure there is just one answer or even a correct answer. Various countries around the world, like China, Chile, and Ecuador want to dam up rivers for hydroelectric power. It would change the lives of millions forever. What can we do? What should we do?