Role of Geology in the Construction of Hoover Dam Case Study

Role of Geology in the Construction of Hoover Dam - Case Study Example Studying the geology of a building site is a vital first step before designing and constructing any structure, particularly formidably large and heavy works like concrete dams. For both civil engineers and environmental scientists, a study of geology is vital, for understanding the soil mechanics and its functions as a building site, and for understanding the environmental impacts of a construction project. Thesis Statement: The purpose of this paper is to investigate why geology is important for a civil engineer or an environmental scientist, using a case study of the Hoover Dam. The Hoover Dam: A Construction Miracle of the Twentieth Century The Colorado River was chosen for constructing the Hoover Dam because of its steep gradient of 11,000 feet in 1,450 miles, more than any of the larger rivers. It was expected that the sharp fall of the Colorado river would facilitate the spinning of turbines at the highest speeds. Black Canyon was selected as the site for the dam, and not the e arlier choice of Boulder Canyon. Both sites were on the lower Colorado River beyond the mouth of the Grand Canyon; however the advantages with Black Canyon lay in â€Å"a more solid and therefore safer bedrock foundation† (Powell 2008: 72), which is reiterated by Stevens (1990) who states that the bedrock at Black Canyon had less jointing and faulting than at Boulder Canyon, after diverting the river there would be less silt and debris to clear, tunneling through the canyon walls would be much easier, and the dam would require less concrete for building because the gorge was narrower. Further, the advantages of constructing the dam at Black Canyon included its easier access, and facilitation for sediment accumulation at the deepest part of the reservoir. The Hoover Dam was unprecedented in the number of hazards and problems the construction project presented. The pressure caused by the reservoir of over nine trillion gallons of water was countered by using the principle of th e arch shape to the dam. To anchor the dam firmly, its base was designed to be several times thicker than its crest. Additionally, to keep the dam site dry during construction, the river had to blocked with a coffer dam and the water diverted through bypass tunnels bored through the bedrock (Powell 2008: 74, 58). Further, tremendous measures had to be undertaken for overcoming natural obstacles such as jagged mountains of volcanic rock, the rapid flow of the Colorado River rushing through a narrow gorge, and the rugged and inaccessible Black Rock Canyon between Nevada and Arizona situated against a desert background infested with wildlife including rattlesnakes. The dam site was also in an isolated area, away from human habitation, with the model town for workers being about eight miles from the dam site. There were sharp differences in temperature, from 140 degrees on the canyon floor in summer to below 20 degrees in the winter. Other daunting construction problems included the nec essity to â€Å"divert the Colorado river through freshly made tunnels in nearby rocks and a temporary coffer dam while the site was cleared and the dam built† (McGovern 2000: 144). Additionally, the possibility of stress imposed by temperature changes and the use of large volumes of concrete in relatively small areas, resulting in cracks in