1. The Hoover Dam is situated along the border of the states of Arizona and Nevada in USA. It has been built in the Black Canyon of the Colorado River. It was originally called the Boulder Dam, as it was supposed to come up in the Boulder Canyon.
2. The Colorado River was prone to flooding, and unsuccessful attempts had been made to construct levees and canals. In 1928, Congress authorised the Boulder Canyon Project. Along with the dam, the project included a hydroelectric plant and a reservoir.
3. The Bureau of Reclamation issued the bid along with a detailed plan of the dam’s construction. The companies had to post a 2 million dollar bid bond, and the winning company would have to post a performance bond of 5 million dollars. Six different construction companies formed a consortium called Six Companies Inc. and won, with a bid of nearly 49 million dollars. The time given for completion of the project was seven years, with an incentive bonus and fines for time overrun. The architects were Henry Kaiser and Gordon Kaufman.
4. The dam construction posed a number of challenges. The weather was very hot and there were no facilities on site. The Colorado River had to be re-routed before construction could begin, and some of the techniques would be put into practice for the first time. Despite these difficult conditions, the dam was completed two years ahead of schedule.
5. The first step was to create tunnels to re- route the river. This was done by blasting the canyon walls. With the excavated material, coffer dams were built, and the river was successfully diverted. Next, the canyon walls had to be cleared of loose rocks and debris. Workers were suspended from 800 ft. above the floor of the canyon, armed with jack hammers and metal poles to do the job. This was a risky operation, and there were many casualties. When the river bed dried, the construction began. Cement was mixed at the site, and was transported by cables across the canyon at the rate of a bucket every 78 seconds. The concrete blocks had to be cooled off, so they had pipes embedded in them. Iced water was pumped through these pipes.
6. The Hoover Dam was constructed during the time of the Depression. Large numbers of people migrated to the area in the hope of gaining employment. Those who were selected were eventually settled in Boulder City, which came up for this specific purpose. A highway was constructed from Boulder City to the dam site.
7. The reservoir created by the dam is called Lake Mead. It is one of the largest artificially created lakes in the world. It is approximately 185 km long and 180 m deep. It can store about 35 billion cubic metres of water.
8. The Hoover Dam is an imposing structure. It is an arch- gravity type of dam. The water load is carried by horizontal arch action and gravity action. It is 221 m high and 379 m long. Its concrete base is 200 m thick. The concrete used in the making of the dam would be enough to make a two- lane highway all the way from San Francisco to New York. It has been rated as one of America’s Modern Civil Engineering Wonders by the American Society of Civil Engineers.
9. The construction of the Hoover Dam provided multiple benefits, apart from controlling the flooding of the Colorado River. The power plant, with a capacity of 2080 megawatts from its 17 turbines, provides power to Arizona, Nevada and southern California. Lake Mead provides water to roughly 8 million people in Arizona, Nevada and California. Formerly, a highway (US Route 93) passed over the top of the dam. Due to concerns over terrorist attacks, a bypass has been built, and the road on the dam is now used for tourists only. The construction of the dam and its benefits contributed to the growth of Los Angeles, Las Vegas and Phoenix.
10. In 1985, Hoover Dam was designated as a National Historic Landmark. It is a major tourist attraction, attracting a million visitors to the dam alone. Lake Mead is one of the most popular recreation areas in USA, with about 9 million people coming annually to enjoy swimming, fishing, boating and water skiing.