In the July/August issue, History Lesson examined the construction of the St. Francis Dam in California and its catastrophic failure in 1928. This second and final installment examines the causes and aftermath of the deadly event.

The St. FranciS Dam collapse on March 12, 1928, claimed the lives of at least 450 people and destroyed 8,500 acres of farmland; it remains one of the greatest

civil engineering disasters in American history. The collapse happened with virtually no warn-ing. An inquest by the Los Angeles District At-torney’s office noted that “the only safety measure possible at that time would have been to warn ev-eryone in the possible path of the flood to move out, since, with all gates wide open, it would have taken many days to have drawn the water low enough to re-move the danger.”

Nevertheless, in the aftermath of the dam’s failure, leg-endary engineer William Mulholland, who led the Los An-geles Bureau of Water Works and Supply (now the Depart-ment of Water and Power), found himself in the crosshairs of a public demanding accountability.

Reaction in Los Angeles ranged from lurid (“Mulholland’s Heart Torn by First Disaster,” blared one Los Angeles Times headline; “Resign—Now!” demanded the Los Angeles Record) to threatening. Margaret Leslie Davis’s account of the disaster

(Rivers in the Desert: William Mulholland and the Inventing of Los Angeles [New York: HarperCollins Publishers, 1993]) not-ed that a woman who had lost her family to the dam paint-ed these words in red on a sign next to her destroyed home: “KILL MULHOLLAND.”

Mulholland was devastated by the failure; one employee claimed the tragedy had aged him 20 years. In a long, icon-ic career of taming western waterways to serve the growing

ambitions of Los Angeles, Mulholland confronted his greatest challenge in facing an angry public and his own failure.

Within days of the disaster, no fewer than four separate inquiries, involving eight agencies at the city, county, state, and federal levels, had begun. Governor C.C. Young convened a six-person panel

that issued a report in less than a week. More significant was the two-week coroner’s inquest led by ambitious Los Angeles District Attorney Asa Keyes. Keyes—believing he could at-tain the governorship of California if he could successfully take down Mulholland—relentlessly badgered Mulholland, known as the Chief, questioning and mocking his competence.

According to the website of the Santa Clarita Valley His-torical Society, “Keyes and the coroner’s jury relentlessly ques-tioned Mulholland about the composition of the concrete, the selection of the dam site on an earthquake fault, the construc-tion and drainage of the foundation of the dam, the anchoring W

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From Fame to Failure: The St. Francis Dam (Part 2)

. Hi s to ry Le s s on.

Only one section of the St. Francis Dam withstood

the catastrophic failure.

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of the dam to the walls of the canyon, and Mulholland’s unquestioned role in supervising the dam construction.”

Keyes was showy and ambitious, and the histrionics of the inquest galled Mulholland. Davis described it this way: “To Mulholland’s engineering mind, Keyes didn’t build or create any-thing; he only shuffled papers back and forth while languishing on the city pay-roll, using the misfortune of others as a rostrum for his own political agenda, all the while espousing advocacy for law and order.”

Still, Mulholland had little lever-age. When pressed, Mulholland ad-mitted he wouldn’t build on the same spot again, but this may have had less to do with the site’s geology than with Mulholland’s unfounded suspicion that Owens Valley ranchers—who felt Mul-holland had stolen their water years ear-lier—had sabotaged the dam.

The district attorney’s inquest last-ed two weeks, and Mulhol-land owned up to what had happened. “Don’t blame any-body else,” he testified. “You just fasten it on me. If there is an error of human judgment, I was the human.”

“It has become a cliché to say that Mulholland was bro-ken by the failure of the dam, and it is true that...Mulhol-land took ever greater refuge in silence,” his granddaugh-ter, Catherine Mulholland, wrote in an essay titled “Wil-liam Mulholland and the St. Francis Dam” in The St. Francis Dam Disaster Revisited (Histori-cal Society of Southern Califor-nia, Ventura County Museum of History and Art, 1995).But Catherine Mulholland quoted the Chief’s nephew, also named Wil-liam Mulholland, who told her that Mulholland, despite his famous line about blame, didn’t really consider himself at fault because he was not sat-isfied by the official explanations of the dam collapse. The nephew told her that Mulholland “was not broken by that mishap because he never accepted the responsibility of something that was beyond his power.”

No charges were filed against Mul-

holland, but the jury of the coroner’s inquiry did provide a devastating crit-icism of the project, which has been published on scvhistory.com. The errors of St. Francis Dam weren’t just in the mistakes Mulholland and staff made, the jury concluded. They were errors “in regard to fundamental policy relat-ing to public safety.”

The most far-reaching insight of the coroner’s inquiry was also the one that displayed the most common sense: “A sound policy of public safety and busi-ness and engineering judgment de-mands that the construction and op-eration of a great dam should never be left to the sole judgment of one man, no matter how eminent, without check by independent expert authority, for no one is free from error.”

“Their conclusions were right on,” says J. David Rogers, Ph.D, P.E., P.G., CEG, CHG, F.ASCE, a professor and the Hasselmann Chair in Geological Engi-

neering at Missouri University of Sci-ence and Technology. “They’re just as timely today, 91 years later, as they were in 1928.”

Mulholland, who once claimed, “The only people I envy in this whole thing are the dead,” endured the inqui-

ry as best he could. He resigned from the Bureau of Water Works and Supply soon after and died in 1935.

When asked about Mulholland’s complicated legacy, Rogers says, “He’s highly respected. He did do a lot of clever and great things. Every person has their faults. The thing I admired about him when I was younger was that he admit-ted his culpability and responsibility, and you don’t see people do that anymore.”

But Rogers became less sympathetic to Mulholland as he reviewed the volu-minous transcripts from the coroner’s inquest. “I don’t think he was altogeth-er forthcoming. I don’t think he wanted the world to know it wasn’t actually de-signed for that site. They didn’t recover rock cores and test the rock cores. They made assumptions.”

The district attorney’s inquest, de-spite not charging Mulholland or his of-fice with any crimes, was critical as well. “The exploration work, both before and

during construction, was practically lim-ited to the boundaries of the concrete structure and did not adequately reveal the topography and character of the bed-rock structure beyond these boundaries,” the inquest’s conclusion states.

The governor’s commission, which released a report in less than a week, blamed the failure on the dam’s defec-tive foundations—in particular, the west, or right, abutment, which it stated was composed of a “reddish conglomer-U

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The flood resulting from the dam failure claimed the lives of at

least 450 and ravaged the res-ervoir’s electrical substation.

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ate which, even when dry, was of decidedly inferior strength and which, when wet became so soft that most of it lost al-most all rock characteristics.” The governor’s panel concluded that the failure occurred first on the west (right) end, which “caused a heavy scour against the easterly canyon wall at the toe of the dam,” cutting away the schist on the east (left) side.

But Rogers contends that the dam failure began on its left abutment, which consisted of Pelona schist that had shifted before the dam’s collapse and had experienced uplift when the reservoir was first filled. This uplift helped further destabilize a poorly engineered structure.

The concept of hydraulic uplift was largely unknown to en-gineers around the time the dam was built, only gaining atten-tion after the dam failed. “Uplift pressures are caused by buoy-ancy due to simple submergence or percolation,” Rogers wrote in his essay titled “A Man, a Dam, and a Disaster: Mulholland and the St. Francis Dam” for The St. Francis Dam Disaster Re-visited. “When water fills behind a dam, the dry dead weight of the dam is significantly reduced because of the water pressure within the founda-tion rock beneath the dam...pushing upward.”

In most of the masonry dams designed be-fore the St. Francis failure, subdrainage was lim-ited to the maximum cross section and often ig-nored altogether at the abutments. Until 1945, Rogers wrote in a 2013 presentation on the subject, “most engineers assumed that concrete was sufficiently impervious to resist complete saturation and that dams founded on relatively impervious strata, such as granite or gneiss, would not be sub-ject to hydraulic uplift.”

Renowned Harvard geotechnical en-gineering professor Karl von Terzaghi, Hon.M.ASCE, published the findings of his permeability studies on concrete in the mid-1940s. He proved that “pore pressure does transmit through good, solid, well-poured concrete,” says Rogers. The reason, which Terzaghi suspected, took another 40 years to confirm: microfissuring.

For the most part, the St. Francis Dam had no systems to counter such uplift. If it had, “the dam’s foundations would have been deeper, a cutoff wall employed, and grout curtain with seepage relief wells installed beneath the entire struc-ture,” Rogers states. As it turned out, the only portion of the dam to survive (the center) was constructed with 10 uplift relief wells.

(The 1959 failure of France’s Malpasset arch dam, which killed 421, further drove home the vulnerability of concrete arch dams to uplift, according to Rogers, espe-cially those constructed on steeply sloping abutments.”)

But the biggest mistake, according to

Rogers, was that Mulholland grouted or “chinked” four huge transverse contraction cracks that had appeared on the dam’s downstream face. This was, Rogers says, the worst mistake the water chief could have made. “What you never want to do with a hydraulic structure is chink the downstream face. You want to chink the upstream face, so water pressure doesn’t get into the structure. When you chink the downstream face, now you have that full reservoir hydraulic pressure, which is hydrostatic, internally in the structure. That would far and away be more serious to the factor of safety.

“As long as water can seep through, it’s not that big a deal,” Rogers explains. “It’s when you trap the water that it becomes a really big deal. Now the pore pressure elevates. When it elevates, that’s when you get into trouble.”

When trying to assess responsibility for the dam, one might reasonably ask, “Who designed the dam?” and expect a straight-forward answer: Mulholland or someone working in his office.

The truth is trickier. It’s not inaccurate to say no one else designed the St. Francis Dam. For starters, Mulholland’s staff merely copied the design of the 1924 Weid Canyon Dam (since re-named the Mulholland Dam), which overlooks the Hollywood section of Los Angeles. The de-sign of that dam, in turn, was based, Rogers contends, on lauded engineering textbooks of

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A man can be seen pointing out an enor-mous crack in a piece of what is left of the St. Francis Dam after

its collapse in this pho-tograph from 1928.

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the day—probably the sixth edition of De-sign and Construction of Dams, Including Ma-sonry, Earth, Rock-Fill, Timber, and Steel Struc-tures, Also the Principal Types of Movable Dams (Edward Wegmann. New York City: John Wiley & Sons Inc., 1918) and High Masonry Dam Design (Charles E. Morrison and Orrin L. Brodie. New York City: John Wiley & Sons Inc., 1910).

“It was pretty clear by the end of it that they didn’t really design it, not in terms of the way we would think of a design in the modern day,” Rogers says. “They just copied what had worked for other people previously.”

Neither of the highly regarded textbooks was written with California in mind, Rogers says. “California is on an ac-tive tectonic margin, so the rocks are much more broken up and deformed than you have in the glaciated parts of New England, where most of those water works started.”

The dam failure shaped a whole generation of thinking about dams. The San Gabriel Forks Dam, set to be the largest dam in the world and also in the Los Angeles area, was can-celed in 1929 after a state panel concluded the dam couldn’t be “constructed without creating a menace to life and proper-ty.” And in 1929 California passed the first law in the nation that required state review of every nonfederal dam or reservoir in the state. According to the Santa Clarita Valley Historical Society, “The new legislation allows the state to employ con-sultants as necessary, and the state has full authority to su-pervise the maintenance and operation of nonfederal dams.”

In this new era of renewed emphasis on safety, the Weid Canyon Dam, which encloses the Hollywood Reservoir, was fortified with 300,000 cu yd of earth fill in front of the dam, which both stabilized it and largely hid the size of the dam

from view; at the same time, the res-ervoir’s volume was reduced by two-thirds. It is now one of the most con-servative dams in the United States.

But perhaps the most significant consequence of the St. Francis Dam failure was its impact on the pro-posed Boulder Canyon Dam (now the Hoover Dam) in Nevada. Legislation for the dam had been stuck in Con-gress for years, and its fate was very much in question as Keyes grilled Mulholland in Los Angeles. After the inquest, Congress appointed a spe-cial board to review the Boulder Can-yon Dam project. The panel, which counted geologists among its ranks, took six months to make its recom-mendations to ensure that the dam’s design was fail-safe because if Boul-der Canyon Dam failed, it would also take out other planned dams down-stream and wipe out communities situated in California’s Imperial Val-ley, located below sea level.

After the board’s review, the Bureau of Reclamation raised the height of the Boul-der Canyon Dam by 25 ft and greatly in-creased its flood storage and spillway capac-ity. “You would not have had the structure we all know there today if St. Francis hadn’t failed,” says Rogers.

What’s more, all major dams, including federal dams, built in the United States now undergo regu-lar safety reviews.

According to a 2006 report for the U.S. Geological Survey (USGS) by Robert L. Schuster (Interaction of Dams and Land-slides—Case Studies and Mitigation, USGS Professional Paper 1723), 77 of the 153 U.S. dams that directly interact with landslides have received some kind of active mitigation over the years to prevent or alleviate dangers associated with landslides.

Rogers has been researching the St. Francis Dam since 1978; maybe the most important lesson from St. Francis is about hubris. “I still respect the guy, but all of us need to be cognizant of our limitations,” says Rogers. “Everybody is limited by their pedigree of professional and personal expe-rience. You only tend to see those things that you’re looking for. And you’re only going to look for things you’ve been pre-

viously exposed to. “We all have these blind spots,”

Rogers points out. “We haven’t worked everywhere and worked on every kind of structure. And there are a lot of things we can’t control.”

—t.r. Witcher

T.R. Witcher is a contributing editor to Civil Engineering.

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Witcher

In 1959, the Malpasset Dam in France collapsed under

circumstances similar to those surrounding the St. Francis Dam failure, solidifying the

importance of designing dams to counteract uplift.

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