Blood Concrete and Dynamite Building the Hoover Dam
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High above the of Nevada’s Black Canyon, a group of men repelled down the face. Suddenly, a man over the canyon rim. He plummeted past the men, too fast for them to — when another swung out from the rocks and carried him to . Once they’d the engineer up the cliff, his swung back to business as usual— just another day in the of the Hoover Dam. In the early 20th century, the United States had from coast to coast, but many cities in the southwest still lacked reliable water sources. While the Colorado River had been into a series of canals, its flow and frequent floods made it unreliable for agriculture. At the same time, the region’s growing cities and industries needed more energy. So in 1922. the Bureau of decided to solve all these problems in by building a massive hydroelectric dam. Ensuring water rights for the project required cooperation between all seven states along the river.But once local governments , the Bureau that Black Canyon’s narrow gorge was best suited for an arch-gravity dam. This design curves , using the force of oncoming water to push the structure into its supports— in this case, the walls. Arch dams have been built since ancient times, but never on such a massive . When complete, the would be 221 by 379 meters. It would take an labor force to build a dam this massive. And when the Great struck only a year after the project’s approval, thousands of families looking for work began to the site. The earliest arrivals lived in a makeshift called Ragtown. With no infrastructure, supplies, and little protection from the elements, several residents died of . So to better house workers, the government designed and built the still Boulder City, complete with numerous , including a state-of-the-art hospital. Before construction on the dam could begin, the entire river had to be . Building these tunnels required blasting into each side of the canyon to create 17 meter tall . With a combined length of almost 5 kilometers, these could divert roughly 5.600 cubic meters of water per second. However, workers faced conditions to finish these on time, and dozens to the scorching heat. By the fall of 1932. the river had been successfully . But the most dangerous work was still ahead. Over 1 cubic meters of loose rock needed to be cleared from the canyon walls. So brought in high scalers who descended the cliffs on ropes, removing with jackhammers and dynamite. From circus acrobats and former sailors, to local , these death-defying individuals performed some of the most dangerous— and — work on site. After the walls were cleared, it was time to build the dam. This required pouring over 6.6 million tons of — enough to a road across the entire US. But so much concrete at once would take far too long to cool and harden. So to speed this process up, concrete was poured in blocks of varying sizes, each steel pipes flowing with cold water. By 1935. most of the structure had been completed two years ahead of . On February 1st, the diversion tunnels opened to fill the dam’s , of holding twice the Colorado River’s annual flow. Upon , the dam was the tallest manmade structure in the world. However, the of its construction came at the cost of worker safety. While this project employed roughly 21.000 Americans during a major economic , over 100 people during construction. Creating the reservoir also destroyed like St. Thomas and the Colorado River ecosystem. Today, the Hoover Dam over 4 billion kilowatt-hours annually, providing for over 1.3 million people. But the consequences of its construction continue to over this structure.