Vastness of Hoover Dam

Manawatu Times, Volume LV, Issue 7039, 24 December 1932, Page 7

Vastness of Hoover Dam

HUNDRED MILLION SCHEME, NEW YORK, Dec. 15. President Hoover paused on his way back to Washington after the elections to inspect Hoover Dam, on the Colorado River—named after him as ho has for ten years been president of tho Colorado Commission, under which it is being built, and because he signed, two years ago, the Federal Law authorising the project. Mr. Hoover timed his visit to the moment when the Colorado was diverted into four tunnels, two on either side, to enable the concrete to bo laid. He deseribed it as ‘ ‘ the greatest engineering feat ever attempted at the hand of man.” The work is being carried on under the personal supervision of Dr. Elwood Mead, Commissioner of tho Bureau of Reclamation, who was, for eight years prior to the war, chairman of the fetate Rivers and Water Supply Commission for Victoria.

Briefly, hho scheme dams up the Colorado River to a height of 700 feet at Black Canyon, whoso sides tower nearly half a mile above the river. The work will take ten years, costing £100,000,000, creating a lake 125 miles long, twelve times the size of Assuan, that will serve six States in the southwest. The Colorado watershed is 244,000 square miles, nearly threo times the area of the State of Victoria, and flows for 1700 miles in a tortuous course from the Rocky Mountains to the Gulf of California. At flood periods its flow ranges up to 250,000 cubic feet per second. Four Great Tunnels. Work started on April 29, 1931. Truck loads were blasted through volcanic rock to the floor of the canyon to permit work commencing on the diversion tunnels. These four concrete-lined 56ft. circular bores will carry the waters of tho Colorado for about seven years, till the dam is completed. A truck bridge, suspension bridges, and cableways have been strung across the canyon, connecting Arizona and Nevada. To drill the tunnels giant steel-framed “jumbos” operated 25 pneumatic diamond drills simultaneously from three different levels. The crews of each of the drills met midway in the following March and held a celebration half a mile from the outer air.

Guards are posted upstream at various points to warn of any approaching freshes in the river, giving the crews 30 hours to get locomotives, trucks, and construction equipment off the floor of the canyon by means of railways that cling precariously to its walls. As the river was forcibly shoved fr>m the bed where it has flowed for centuries, intensive tests were made of the rock on which the dam will rest. It is estimated that, by 1934, all preliminary work will have been completed, and the pouring of the enormous masses of concrete will begin. A Payable Project. Tho whole project is financed by the Federal Government. More than half tho total cost will go to the erection of an aqueduct, 200 miles long, crossing the Sierra Divide, necessitating the water being raised 1200 feet. This will convey the stored waters of the dam to the Imperial Valley, in Southern California, an irrigation scheme that commemorates tho genius of the Chaffey brothers, ono of whom has been associated with similar developments in Australia. • A condition of the construction is that all money spent on the scheme must come back to the Federal Government, plus 4 pe\f cent., within 50 years. Revenues will be derived from water supplied to cities and towns and from power, for which contracts have already been signd. The scheme will bo free of taxation, and it is estimated it will return to the Government nearly £20,000,000 profit.