Built to harness the tremendous power of the Colorado River, the Hoover Dam is one of the world's most impressive engineering marvels. Rising 726 feet above the border of Arizona and Nevada, the dam attracts thousands of tourists each year. From 1931 to 1935, more than five thousand men worked twenty-four hours a day, seven days a week to successfully complete the dam-some of them losing their lives. Since its completion, the dam has provided essential power and water throughout the Southwest and continues to fuel the growth and economies of many cities and communities.

Every part of the project had to be designed, budgeted, and accounted for so Congress could allocate the funds. On January 10, 1931, Congress released the specifications for Hoover Dam to the public and asked for bids. Although the government created the design and put up the money, private construction companies would bid for the right to build the dam. For five dollars, any private construction company could obtain a copy of the plans. All bids had to be submitted by March 4, 1931. Whoever built Hoover Dam would have seven years to do it. Deadlines were set for the completion of various phases of the work, with penalties for deadlines not met.

To discourage frivolous bids, the government required that every bid had to be accompanied by a $2 million refundable deposit. The bid winner would have to deposit an additional $5 million with the government.

The dam designers gave the government an estimate of $48, 866,955 as the cost of constructing the dam. The contract for the dam's construction would be the largest ever awarded by the government.

When private companies bid on a government project, they aren't told the government's estimated cost. They have to look at the plans and specifications, then figure out how much it will cost them to fulfill the requirements. The bidder that comes closest to the undisclosed estimate usually gets the project.

In 1931 the United States was in the depths of the Great Depression. Banks had closed, companies had gone bankrupt, and millions of people were unemployed. For many construction companies, the opportunity to build part of the world's largest dam was extremely welcome. Their employees would be working, and the companies would be making money again. Scores of private construction companies sent for the plans. Everybody was very enthusiastic.

When they looked closely at what was required, however, their enthusiasm waned. No single construction company in the world could build Hoover Dam. The project was too huge. The requirement that the company put up $2 million, with a potential for another $5 million, was another limiting factor. In the midst of the Great Depression, few companies - even successful ones - could raise that much money.

The only way to build the dam was for companies to form partnerships. During the spring of 1931, two of the largest dam-building construction companies in the West, Utah Construction and Morrison-Knudsen, did just that. Before they could bid on the project, Utah Construction and Morrison-Knudsen had to add still more partners-J. F. Shea, Pacific Bridge, MacDonald & Kahn, and Bechtel-Kaiser-Warren Brothers.

Called Six Companies, Incorporated, the group put together a bid and submitted it to the government. Even with six large, successful companies banding together, it was still difficult to come up with the initial money required. To get $2 million and have another $5 million lined up, the group pledged to the bank 25,000 cattle and 30,000 sheep, among other assets.

On the morning of March 4, 1931, the Denver office of the U. S. Bureau of Reclamation was packed with people. Cigar smoke filled the air, newspaper reporters spilled out into the corridors, and contractors waited nervously. Although many companies had been interested in bidding on the project, only five bids had been submitted.

Raymond Walter, chief engineer of the Bureau of Reclamation, spread the sealed envelopes containing the bids on a table at the front of the room. Neither of the first two bids was accompanied by the required $2 million. The next two bids were in order. One was for $53.9 million and the other was for $58.6 million. Only the bid from Six Companies remained. Walter opened the last envelope and read, "Six Companies, Incorporated, San Francisco, California, $48,890,955." Their bid was only $24,000 more than the government's estimated cost of the project.

ON THE MORNING OF MARCH 11, 1931, a crowd of dignitaries, politicians, and newspaper reporters waited anxiously as a smoke-belching, black locomotive chugged into the dusty Las Vegas train station. The train ground to a halt with an ear-splitting screech. The crowd on the platform surged forward, peering into the windows. Frank Crowe, the man in charge of building Hoover Dam, was on that train, and everyone wanted to meet him.

The dam builders of the West were a small, almost elite, fraternity. Only a handful of private companies built dams, so the engineers and experienced workers traveled from site to site following the work. Although the engineers were well educated, they were a rough-and-tumble lot who preferred the wide-open spaces of the West to desk jobs in the East.

Frank Crowe was already a legend within this group. With an engineering degree from the University of Maine, he was not only well educated but also smart and creative. He had an uncanny ability to solve tough engineering problems in unique ways. His specialties were high concrete dams and cable transportation systems. Only in his forties, he had already built six dams. He, finished all of them on time and under budget, which made employers love him. And as a supervisor he was fair, so field-workers loved him too.

31

AS 1T ROSE FROM THE FLOOR of Black Canyon, Hoover Dam looked like a tumble of children's building blocks. Large wooden box forms, between 25 and 60 feet square (21 and 330 in'), were placed next to each other. The concrete was poured into these molds. It took 230 of these boxes to form the base of the dam.

Six Companies liked to work fast, but this part of the project would take more time. As concrete hardens, it creates a chemical reaction that produces heat. If Hoover Dam had been poured in one continuous block, its temperature would have risen 40 degrees Fahrenheit (4 degrees Celsius). It would have taken 125 years for the concrete to cool and harden, and it would have cracked in the process, making the dam useless. Even pouring concrete in 5-foot (1.5-m) layers created a lot of heat.

To meet their deadlines, Frank Crowe created an ingenious method for cooling the concrete. A network of thermometers and 1-inch (2.5-cm) pipes were laid in the wet concrete. Refrigerated water was run through the pipes to cool down and harden the concrete faster. The thermometers indicated when the concrete was cool enough to pour another layer. When the dam was finished, the pipes were pumped full of grout, which sealed them and strengthened the dam. By the time Hoover Dam reached its full height, 582 miles (937 km) of pipe had been laid.

To ensure the structure wouldn't be weakened by the tiny hairline cracks that remained between the concrete boxes, grout was pumped into these spaces once the molds were removed. To make doubly sure the grout bonded securely, the upstream and downstream sides of each mold were scored (scratched) with vertical grooves. The two other sides were scored with horizontal grooves. The grout bonded better to this rough surface, and the columns locked together in a solid unit.

As far as Frank Crowe was concerned, waiting for the concrete to harden was the hardest part of the job. So far, nearly everything had been left up to Six Companies. Crowe could go; as fast or as slowly as he wanted, as long as he met their deadlines. But the Bureau of Reclamation controlled the speed of pouring the concrete for the dam structure.

The Six Companies contract stated that concrete could be poured no more than 5 feet (1.5 m) deep in a box column mold in any seventy-two-hour period. No more than a depth of 35 feet (11 m) of concrete could be poured into any mold over a thirty-day period. Because Six Companies had already raced through the greater part of the job, the Bureau of Reclamation sent one of its top men, Walker Young, to make sure the company slowed down on this part of the project.

Under normal circumstances, Young and Crowe liked each other. They'd known each other for twenty years and had worked on other dams together. But the two squabbled constantly about pouring the concrete for Hoover Dam. Crowe referred to Young as the Great Delayer, and Young referred to Crowe as Hurry Up.

With Hoover Dam finally going up, more newspaper reporters came to report on its progress. The feud between Walker and Crowe certainly spiced up their reports, although Walker admitted to one reporter, "Sometimes we fight with each other for the fun of it."

Whether it was fun or not, Walker held his ground. The concrete pouring proceeded slowly, based on contract terms and what the embedded thermometers revealed.

Pouring the concrete was one of the easiest and one of the hardest parts of the job. The easy part was simply pouring concrete into a series of box molds and waiting for it to harden. The hard part was that a lot was going on in a very small space. The dam would be nearly 800 feet (244 m) high, and Black Canyon was extremely narrow.

As Frank Crowe put it, "We had 5,000 men in a 4,000-foot [1,220 m] canyon. The problem, which was a problem in materials flow, was to set up the right sequence of jobs so [the workers] wouldn't kill each other off."

Concrete was the material that needed to flow. Mixing it was easy enough. High Mix was now running at full capacity. But getting it poured into the correct mold was difficult. To solve the problem, Crowe devised an aerial tramway system. Crowe's tram system consisted of ten aerial towers that spanned canyon. Each tower was 90 feet (27 m) tall, had wheels on its base, and was set on railroad tracks. This allowed the towers to move back and forth in the canyon. A complex network of steel cables connected all the towers to the concrete-mixing facilities and to all sections of the dam. By hooking giant buckets to the cable system, concrete could be delivered anywhere in the canyon.

The entire tram system was controlled by a cable operator sitting in a tiny shack, perched on a platform that extended 30 feet (9 m) into the canyon. He moved everything from this perch, based on hand signals received from signalmen at the bottom of the canyon. The operator could zoom an empty bucket over to High Mix, then send a loaded bucket of concrete back to the construction site. Buckets, each holding 8 cubic yards (6 m') of concrete, swung through the canyon. They could deliver a massive quantity of concrete to where it was needed.

ANUARY 31, 1935, WAS THE last day of freedom for the Colorado River. The next morning, a giant control gate slammed shut in Tunnel No. 4. This forced the river into Tunnel No. 1, where a network of opening and closing valves controlled its passage. Enough water was sent down Black Canyon to irrigate the Imperial Valley. The rest was blocked to begin forming a reservoir behind the dam.

On February 29, 1936, Frank Crowe stood on the crest of Hoover Dam surrounded by reporters. Flashbulbs popped as he announced to government representatives, "As representative of Six Companies, Inc., builders of this dam, I am very happy to turn over the job for your acceptance."

The next day, in Washington, D. C., the government formally signed off on its contract with Six Companies. The dam had been completed two years, one month, and twenty-eight days ahead of schedule. Six Companies had put everything on the line to have a chance to build the largest dam in the world. The gamble had paid of, and the job was done.

When all the expenses were paid, Six Companies was left with between $10.4 and $18 million in profit, which was distributed among the owners of the companies. All went on to continued financial success. They never built another gigantic dam together, but all members of the partnership remained friends and sometimes worked on other projects together.

Hoover Dam had made Frank Crowe a wealthy man. In addition to his salary of $18,000 a year, he had also received 2.5 percent of the profits. He finished Parker Dam ahead of schedule, then supervised the construction of several other dams. Since he loved building dams, he had no intention of retiring with his wealth. As he told a reporter two days after turning Hoover Dam over to the government, "I'm looking for a job and want to go right on building dams as long as I live."

Crowe didn't need to worry about work. He was always in demand among dam builders. Pacific Constructors hired him as the general superintendent for construction of Shasta Dam in northern California, a dam that rivaled Hoover in size and complexity. When it was finished in 1944, Crowe was sixty-two years old. He had been doing hard labor for most of his life.

In 1945, with the end of World War II, the U.S. government asked him to organize and direct all the reconstruction work for the U.S. Zone of Occupation in Germany. He wanted to accept the job, but his doctor advised him not to. Frank Crowe reluctantly retired to a cattle ranch he owned near Shasta Dam. He died there on February 26, 1946.