Published in the winter 2011 issue of MyLIFE magazine
The wonders of Hoover Dam remain with us in the 21st century, an illustration of the impact of the history of technology on our daily lives.
The building of Hoover Dam was a massive technological undertaking that lasted almost five years. The U.S. government went forth with the project to harness the power of the Colorado River, particularly for the generation of hydroelectricity. To this date, the river and the dam are used to generate electric power, conserve water and supply water to parts of the American Southwest. The story of the construction of the dam celebrates the triumphs of an age of technological development in America, but it also suggests the human price of progress.
The enormous Hoover Dam, also called Boulder Dam, sits in the Black Canyon of northern Arizona and southern Nevada, about 30 miles southeast of Las Vegas. This modern-day wonder is a concrete arch gravity dam that sends water from the Colorado River to a colossal power plant for the generation of electric power. The movement of this water is created by gravity and the immense pressure created by its horizontal arch, an architectural design created by the Romans. At its tallest point, it is 726 feet high and weighs 6.6 million tons, a weight that is comprised of concrete, steel and metalwork.
During the age of major technological advancement in the late 1800s, the desire to create large sources of electricity led many to consider the use of hydraulics to generate it. As early as 1902, surveyors had been eyeing the Lower Colorado River as a new source of hydroelectric power. By 1922, the U.S. government had become involved in the process of surveying and planning for the dam after the Reclamation Service (now the Bureau of Reclamation) suggested the area as a good site not only for the generation of electricity, but also for flood control in the region. Congress authorized the funding to build the dam in 1928, but the project stalled until 1931 because of engineering concerns about the feasibility of such a large project.
After careful consideration, engineers suggested that to pull off an effort of such magnitude, major modifications would have to be made to the equipment considered essential to the building of the dam. By the time construction of the dam began, numerous American companies had been recruited by the government and the main contractor of the job, Six Companies, Inc., to supply not only the materials to construct the dam, but also newly modified and massive machinery to transport the materials and put them in place. The truck manufacturer Mack, which had already cornered the American market for building heavy duty, industrial trucks, created a new truck expressly for the Hoover Dam project. The 250-horsepower truck carried twice the load of the biggest truck manufactured to that date.
Construction on the nearly 2,000-foot-long bridge dividing Arizona and Nevada began in January 2005. The effort, known as the Hoover Dam Bypass Project, was completed on Oct. 19, 2010.
Major American power supplier General Electric, formed in 1892 through the merger of a Massachusetts power supplier and Thomas Edison’s Edison General Electric, used the continued advancement of X-ray technologies first introduced in the late 1800s to execute the largest known X-ray project for the dam. Throughout the project, GE’s X-ray technicians would take more than 100,000 films, altogether measuring more than 24 million square inches of X-ray film, to ensure the quality of the welding that fused the pipes that moved the water to the power plant.
Hoover Dam has a number of heroic-size works of art and monuments, including this 30-foot-tall bronze winged figure by sculptor Oskar Hansen, who said the sculpture symbolizes “the immutable calm of intellectual resolution and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific achievement.
Movement of the materials needed to construct the dam and transport workers back and forth was performed by a massive cable car system manufactured by New Jersey-based Ledgerwood Manufacturing. The cars ran along a cableway five times longer than any other cableway in existence in the 1930s. Given the weight of the materials that needed to be transported by the cable cars, the cableways also needed to be stronger than any other in the world to that point. When pushed to their limits, these steel cables, which were 3.5 inches in diameter, could hold almost 200 tons of material.
The building of the dam commenced with the diversion of the Colorado River by tunnels that measured 50 feet in diameter (larger than the tunnels used for the New York subway system) and were three miles in length. The construction site was then enclosed in two structures called cofferdams, made of concrete, rock fill and earth fill. The larger cofferdam was 96 feet high. These structures created a dry work environment by protecting the site from the Colorado River.
LARGER THAN THE EGYPTIAN PYRAMID OF GIZA
Excavation of the site began with the removal of 5.5 million cubic yards of rock from the canyon by jackhammers and dynamite. After the filling in of cavities in the remaining rock used for the foundation of the dam with a synthetic grout, the true construction began. Concrete, which comprises more than three fourths of the dam’s mass, was put into large buckets that were transported by the cable cars and then lowered to where the workers needed them by overhead cables. The enormous amount of concrete used in the project made the dam, at least in 1936, the only man-made structure larger than the Egyptian pyramid of Giza.
There are 17 giant generators at Hoover Dam, each of which can generate up to 133 megawatts.
The enormous nature of the construction of the dam called for more than 21,000 workers to carry out the engineers’ plans. These men labored on the dam throughout its construction, and they lived either in government camps or in Boulder City, the new town built in 1931 specifically to house those connected with the project. Because of the economic hardships of the Great Depression, many workers descended on the area before work on the project began, to stand in line for jobs.
The technical nature of the project, with new and enormous tools that were foreign to laborers, the torrid weather conditions of the area, where summer temperatures could reach upwards of 119 degrees, and the treacherous working conditions of Black Canyon led to numerous deaths among this community of workers. Various reports have estimated the number of deaths at around 119, which include offsite and onsite deaths from disease, exposure and injuries.
The Bureau of Reclamation reports 96 men as “industrial fatalities”—in other words, men who died on site while attending to the task of building the dam. These fatalities occurred because of the blasting of Black Canyon, constant rockslides, falls from the heights of the canyon or the structure of the dam and fatal injuries sustained while working the machinery or being hit by equipment and trucks. Around the site of the dam are numerous markers memorializing the sacrifices of these workers and their contribution to the progress of technology and humanity.
Franklin Delano Roosevelt dedicated the Hoover Dam in September 1935, though it was not officially completed until March 1, 1936. The final bill for the project topped $49 million. This union of technology and human labor proved to be the largest attempt at mechanical engineering seen in the modern world and, as of 1939, the largest generation of electric power in the world. The wonders of this technology remain with us in the 21st century, an illustration of the impact of the history of technology on our daily lives.
More than 20,000 vehicles a day cross Hoover Dam between Arizona and Nevada. Thousands take the Hoover Dam tour and ride the elevator down into the inner workings of the dam. For more information, visit www.usbr.gov/lc/hooverdam/.
