WORLD’S LARGEST

Evening Star, Issue 21640, 8 February 1934, Page 7

WORLD’S LARGEST

HEW TUNNEL JOB COLORADO AQUEDUCT The metropolitan water district of Southern California, representing a population of 1,665,833 persons and a property value of more than 1,650,000,UOOdol/is a confederation of municipalities of the south coastal basin of California, comprising the cities of Anaheim, Beverly Hills, Burbank, Compton, Fullerton, Glendale, Long Beach, Los Angeles. Pasadena, San Marino. Santa Ana, Santa Monica, and Torrance (writes F. E. Weymouth, in the ‘ Literary Digest '). Such a population needs a large and adequate water supply. Its water at present is largely derived from underground storage basins. In addition, the Los Angeles aqueduct from the Owens River, 275 miles north of Los Angeles, furnishes most of the water used by that city. These sources have provided an ample supply to the present time, but the amount required ,s now in excess of their safe yield. In order to supplement it to put end to the continued overdraft and provide for the normal growth of population the district has undertaken the construction of the Colorado' River aqueduct. It is a large and spectacular undertaking. This aqueduct will be 239 miles in length from the,intake,at the Upper Parker dam site on'the Colorado River to Cajalco Reservoir, the aqueduct terminus, south of Riverside, California. In addition, the distribution system . for the delivery of this water to the thirteen member cities will aggregate 144 miles, in length. the delivery capacity of the aqueduct is 1,500 cubic feet per second, or about 1.000. gallons per day. This is approximately double the present consumption of the district. The entire project will cost about 220,000,000d01. • A DECADE AGO. Investigations of the ■ feasibility of a Colorado River aqueduct were started, in 1923, and during the following eight years topographic surveys were made covering 24,01)0 square miles of the deserts and mountain ranges whicn separate the Colorado River from the Southern California coastal plain. More than 100 different routes between the river and the Los Angeles metropolitan area were mapped and studied. Actual construction work on the aqueduct was started in November. 1932. The route from the Colorado River to San Gorgonio Pass traverses for more than 200 miles a country entirely desert, and the first work to be done" involved the construction along this route of roads, construction water supply lines, power transmission lines, and communication facilities, the cost of which will aggregate more than 5,500,000d01. This preparatory ..work was to have been practically completed by the end of 1933. "Ninety-one miles of the aqueduct will bo in tunnel, of which 82 miles are already under construction. This is believed to be the largest tunnel job ever carried forward at one time in the history of the world. The tunnels are of horseshoe section, concrete lined, with a diameter inside the lining of 16ft. The tunnel requiring the'longest construction period is the San Jacinto tunnel, which will be" 12.7 miles in length. This .tunnel is. expected to. require about six . years for completion, and will cost in the neighbourhood of 10.000, OOOdol. In addition to the tunnels,'the aqueduct comprises 65 miles of open con-' crete-lined canal, -55-miles of cut-and-cover conduit, and 28 miles of siphon and pressure pipe. , Besides the diversion dam and the terminal reservoir there will also be three intermediate storage reservoirs and five pump lifts. WORK FOR THOUSANDS. At the present time more than 2,500 men are employed on the work, and this force will be expanded as rapidly as additional funds become.available until the anticipated maximum of 15,000 is,reached. On account of the inaccessible location of: much of the work and the severe climatic conditions under which it is being performed, especial provisions for the health and comfort of the employees are being made. Air-conditioned sleeping quarters are provided in their permanent camps by the contractors, and in addition to the medical facilities maintained by the contractors the district has constructed at one of its camps a fully-equipped hospital, with resident physicians and nurses and an ambulance service. The water to be diverted at the Upper Parker dam site will be stored at Boulder dam, now under construction 155 miles upstream, and electrical energy purchased at Boulder dam will be used, to operate, the pumps at the five pumping plants, the total lift of which aggregates 1,616 ft. The diversion dam site is located 17 miles above the town of Parker, Arizona. The dam will be of concrete, with a maximum height of 220 ft above bedrock- The rise in water surface will be 72ft. and the reservoir formed by the dajn will extend nearly to the town of Needles, 58 miles up stream.