Page images
PDF
EPUB
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
[graphic]

BOULDER CANYON PROJECT-LOCATION MAP

[blocks in formation]

Six Companies, Inc., San Francisco

Penstock & Outlet Pip............ The Babcock & Wilcox Co., New York

* Deceased.

FOREWORD

Colorado River, originating in the melting snows of the Wyoming and Colorado Rockies and augmented by rapid run-off from spasmodic rains and cloudbursts over a vast arid region, has menaced life and property in its descent to the Gulf of California since the days of the first covered wagon.

With increased population along the lower reaches of the river the problem of controlling the Colorado became more important. During recent years millions of dollars have been spent in mitigating the evils of silt deposition and in protecting the highly cultivated Imperial Valley lands from annual threats of inundation.

The need for a comprehensive plan of development to check the ravages of Colorado River, to regulate its flow, and to utilize a part of its enormous energy led, first, to investigations by the Reclamation Service of all water storage possibilities; next, to the Colorado River Compact, a mutual agreement for the protection of the seven basin states; and, finally, to the adoption of the Boulder Canyon Project, as the initial development.

The Boulder Canyon Project Act, approved December 21, 1928, authorized a total appropriation of $165,000,000 for the various features involved. These include Boulder Dam and appurtenant works, the power plant, the reservoir, and the All-American Canal System. The purposes of the project are: (1) flood and silt control for protection of lands along the lower river; (2) improvement of navigation; (3) river regulation and storage of water for irrigation and municipal use; and (4) development of electric power for domestic and industrial purposes. The project is self-liquidating, largely through contracts for disposal of electrical energy. It was constructed and is being operated under the supervision of the Bureau of Reclamation, United States Department of the Interior.

Boulder Dam is located on the Nevada-Arizona boundary near Las Vegas, Nevada, at a place where Colorado River has carved a deep gorge between towering rock cliffs, known as Black Canyon. The dam is a concrete arch gravity structure with a maximum height of 726 feet above foundation rock, a maximum base thickness of 660 feet, and a crest length of 1,244 feet. The dam and appurtenant works contain 4,400,000 cubic yards of concrete, of which 3,250,000 cubic yards were required in the dam.

During construction the river was diverted through four 50-foot

diameter, concrete-lined tunnels, two on each side of the river. These tunnels were subsequently plugged near the upstream ends. The spillways, each of 200,000 second-feet capacity, are connected through inclined shafts to the two outer tunnels. A 30-foot diameter steel power penstock is installed in each of the inner tunnels. Discharge from the reservoir is controlled by cylinder gates in four intake towers, founded on the canyon walls near the upstream face of the dam. Four 30-foot steel penstocks, connected to the bases of the intake towers, conduct water to the power plant and to the outlet valves for release of flood, irrigation, and domestic water supply when the power plant discharge is insufficient for such purposes. The reservoir above the dam is 115 miles long and has a capacity of 30,500,000 acre-feet, the equivalent of two years' normal river flow.

The power plant is in a U-shaped, reinforced concrete structure, over 200 feet high and 1,500 feet long, located immediately downstream from the dam. The plant is designed for an ultimate installation of fifteen 115,000 and two 55,000 horsepower units, making a total installed capacity of 1,835,000 horsepower.

The All-American Canal, located near the Mexican border, will carry water to irrigate lands in the Imperial and Coachella Valleys. The canal proper, with a diversion capacity of 15,000 second-feet, is the largest ever constructed for irrigation purposes in America.

The entire Boulder Canyon Project is characterized by the extraordinary. The height and base thickness of the dam, the size of the power units, the dimensions of the fusion-welded, plate-steel pipes, the novel system of artificially cooling the concrete, the speed and coordination of construction, and other major features of the project are without precedent. The magnitude of the undertaking introduced many new problems and intensified many usual ones, requiring investigations of an extensive and diversified character to insure structures representing the utmost in efficiency, safety, and economy of construction and operation.

The major credit for the conception of the project and the initiation of investigations leading to its adoption must be given to the late Arthur P. Davis, former Director of the Reclamation Service. Dr. Elwood Mead, Commissioner of Reclamation during the greater part of the construction period, passed away January 26, 1936, four months after the dedication of Boulder Dam. In commemoration of his untiring services on the Boulder Canyon Project, the reservoir created by the construction of the dam has been officially named "Lake Mead".

« PreviousContinue »