SPAIN

EPOSITED BY

› STATES OF AMERICA

y Reclamation Commissioner

FLOYD E. DOMINY

THE

HE construction of large dams in Spain has greatly accelerated over the past 30 years. Although two dams built by the Romans are still n operation and four others were completed beore the beginning of the 18th century, the total number of dams completed and in operation in Spain in 1934 was only 97. Since that time 247 lams have been completed-a tremendous tribute o the vision, ingenuity, and skills of our Spanish contemporaries.

The greatest motivation for such increased acivity in dam construction has been the increasing critical need for electrical energy for industrial growth. Because Spain is not rich in deposits of fossil fuels, hydropower is of special importance o the national economy. As a result, 70 percent of the electricity now generated in Spain is of hydro origin, and more hydro projects are under construction or being planned.

Prior to 1934, water supplies were developed primarily for irrigation and domestic purposes. consequently, storage and regulating reservoirs on the arid Mediterranean watershed outnumbered those on the Atlantic watershed where year-round water supplies are more abundant.

Recent industrial advancement and the resulting ascending economic and social standards have greatly affected the Spanish concept of water resources development. At present, while not ignoring the necessary further development of available water supplies in the Mediterranean watershed, more emphasis is being placed upon the utilization of the large quantities of water that flow into the Atlantic Ocean for producing electrical energy. This is well demonstrated by the following chart on the location of that country's dams;

Torrential flows over the ages have cut deep, narrow gorges into even the hardest of rock. In this way Nature has provided sites which, when properly developed by man, result in benefits far in excess of the cost of development. Such physical characteristics of much of the Atlantic watershed are conducive to construction of high dams, which are the economical producers of electrical energy.

The topography and geology of hydropower damsites have favored construction of concrete dams and, in many instances, underground powerplants. One-fourth of the total completed powerplant capacity is installed underground.

Spanish engineers, intent on deriving optimum benefits from available water resources, have achieved excellence in all technological aspects of design and construction of dams and hydropower installations. From preliminary studies and investigations through all phases of design and construction, the latest engineering techniques have been scrutinized, applied where suitable, and extended as necessary to solve specific problems. Competent specialists in the fields of hydrology, hydraulics, rock mechanics, stress analysis, mechanical and electrical equipment, concrete technology, construction techniques, and operation and maintenance have been developed. Supporting facilities such as field testing equipment, hydraulic and structural laboratories, and electronic computer installations are widely utilized.

T

HE Bureau of Reclamation is building one of the largest dams in the world across one of the smallest creeks in California.

When completed in 1967, San Luis Dam will stand 320 feet high and stretch 31⁄2 miles across the normally dry bed of San Luis Creek.

But the water to fill San Luis Reservoir won't come from tiny San Luis Creek. As a matter of fact, the runoff from the creek won't match even the annual evaporation from the more than 2 million acre-feet of water that will eventually be stored behind the dam.

These anomalies provide a unique background for San Luis Dam, but the practical structure and its related works will have a high payoff from multiple-use operations.

San Luis Dam is part of the half-billion-dollar San Luis Unit of the Bureau of Reclamation's Central Valley Project.

The San Luis Unit is being constructed by the Bureau of Reclamation. Since its major features are to be used jointly with the State of California, the State is paying a proportionate share of the costs. This is the first such Federal-State project in the history of the Bureau.

By connecting the facilities of the Federal Central Valley Project with the California Water Project, the San Luis Unit will make it possible for water originating in the watersheds of the Trinity and Sacramento Rivers to be used as far south as San Diego. This is the geographical equivalent of taking water-from New York's Hudson River for use in Charleston, S.C.

Key features of the unit are rapidly assuming recognizable shape on the west side of the San Joaquin Valley, 12 miles west of Los Banos and 100 miles from the unit's water supply in the Sacramento-San Joaquin River Delta.

Huge machines, some of them especially designed for the challege of moving the 75 million cubic yards of material that will be packed into the dam, are digging, hauling, and compressing thousands of tons of earth 24 hours a day.

Towering above the valley floor, like a ferr wheel in a parking lot, is the giant excavator built to dig and load more than 100 tons of earth a minute.

Instead of seats, this "ferris wheel" has 10 bucke shovels which scoop more than 21⁄2 tons of earth at a bite from an embankment of earth. As the wheel turns, the buckets empty onto a conveyor belt.

At the other end of the belt are two loading chutes. As the gate on one of the chutes bangs closed, one truck pulls forward with its 100-to load and makes a 30-mile-per-hour run to the dam site. At the same time, the other chute opens sending earth cascading down into a second truck already in place. At blaring horn signals from the excavator operator, the second truck moves ahead in quick starts and stops so that the load may be evenly distributed-and still another truck pulls into place beneath the closed chute.

Munching Embankments

Every 45 seconds a truck is loaded and moves out. The wheel excavator slowly moves forward munching its way through the embankment a though it were a chocolate bar.

At the damsite, the bottoms of the truck beds drop open, spilling the earth material on the dam Bulldozers crawl in to spread it, followed by sheepsfoot rollers-heavy drums with hundreds of tiny cylindrical "feet"-which roll over and over and over it, tamping it into sure compactness This places the "zone 1" and "zone 2" material for the dam-the material that is most nearly imper vious to water and makes up the core of earthfill dams.

The heavier material used to anchor the dam in place and protect it from the elements is being blasted from the earth in the hills overlooking the

Workers' cars parked in lower left are in the bottom of the pumpgenerator plant area just below the main San Luis Dam. In a few months the dam will be built up as high as the top of the morning glory spillway tower at right.