Eighty-six years after America's worst civil engineering disaster, the lessons appear painfully obvious.
Engineers now know that each big project has its own set of unique challenges; there's no one-size-fits-all solution. They know that calculations must be made and that project heads must be degreed and registered. And they know that giant concrete dams must be built with the input of geologists.
None that that seemed obvious, however, at 11:57 p.m. on the night of March 12, 1928. It was at that moment, the St. Francis Dam, located 40 miles northwest of Los Angeles, catastrophically failed. Within seconds, 12.4 billion gallons of water roared down the San Francisquito Canyon, creating a wall of water 140 feet high. The deluge demolished one of the dam's heavy concrete powerhouses and quickly took the lives of 64 workmen and their families who lived nearby. It continued on from there, drowning a construction crew of 84 men downriver, washing away the town of Castaic Junction, devastating the cities of Santa Paula and Fillmore, as well as a town now known as Bardsdale. By the time the torrent had travelled the 54 miles from the dam site to the Pacific Ocean, approximately 600 people were dead. Countless bodies were washed into the ocean, with some found as far away as the Mexican border.
Click on the photo of the damaged dam to start the slideshow.
William Mulholland, the legendary engineer who headed the dam's design, ultimately took the blame. "If there was an error in human judgment, I was the human, and I won't try to fasten it on anyone else," he later said. "I envy those who were killed."
Today, engineers say there were multiple causes of the failure. The dam was unknowingly built on a landslide. During construction, designers raised the height of the dam by 11%, without a corresponding increase in the base width. And workers plugged expansion cracks with oakum on the downstream side, which actually raised the uplift pressure on the dam. In retrospect, experts now say those were just a few of the engineering problems.
"When you look at what causes a levee to break, it's never just a single thing," J. David Rogers, chair in geological engineering at Missouri University of Science & Technology, told Design News. "In the case of the St. Francis Dam, we've looked at eight different failure modes and it failed by all eight."
More disturbing, however, was the approach to the design. Engineers made no formal calculations, instead following examples from books, such as Construction of Masonry Dams, Water Supply Engineering, and The Design and Construction of Dams. The dam's design was simply transferred from the books to the St. Francis site, with little or no modification. "It was a cookbook design," Rogers told us. "Draftsmen simply drafted up their plans based on the books."
Experts contend that the tragedy wouldn't have happened if Mulholland's ideas had been subject to outside review. But Mulholland, widely credited as the force that brought water to Los Angeles, was given carte blanche on the project. Oversight from outside engineers and geologists was almost non-existent.
"If he had had a consulting board looking over his shoulder, it wouldn't have happened," Rogers said. "But he was William Mulholland. He was the engineer who foresaw the need to bring the water supply to the city of Los Angeles. No one in the history of mankind had ever done what he had done."
The problem was that Mulholland had little experience in dam design and none in engineering geology. Equally troubling, he had no formal education. Starting as a ditch digger, he had worked his way up through the Los Angeles Bureau of Water and Power, educating himself in engineering, hydrology, and geology before reaching the level of chief engineer and general manager.
Today the lessons learned in the wake of the St. Francis Dam disaster are easily visible across much of the engineering profession, particularly so in civil engineering. A year after the disaster, the state of California passed a Civil Engineering Registration Bill, requiring that anyone practicing in the field must be registered. Such laws are now enforced in all 50 states. Moreover, geologic input in the design of dams, which had been all but absent in the 1920s, became commonplace in the '30s, remaining intact today.
"The world learned a lot from the St. Francis Dam," Rogers said. "But the engineering profession gained even more from it."
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