Located roughly forty miles northwest that Los Angeles, California, St. Francis Dam was a curved concrete gravity dam constructed in between 1924 and 1926 in stimulate to provide a storage reservoir for the Los Angeles Aqueduct system. It was only the 2nd concrete dam of nine dams developed by the Los Angeles Bureau of Waterworks & Supply beginning in 1921. If the dam’s upstream face exhibited a practically vertical profile, the downstream side to be equipped with a stairway step design that led to base and also crest thicknesses that 175 and also 16 feet, respectively. The key structure reached a height of 205 feet and spanned 700 feet along its curvilinear crest. The design and also construction that the St. Francis Dam to be executed solely by the Los Angeles office of Waterworks & supply under the supervision of the organization’s chief engineer william Mulholland. The 1928 fail of the dam which brought about the deaths of end 400 civilians to be attributed to a series of human errors and poor design judgment. Due to the significant loss of life and property damages estimated to be $7 million, some think about the failure of the St. Francis Dam come be the “worst American civil engineering catastrophe of the 20th century.”


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Aerial check out of St. Francis dam website after failure.

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William Mulholland was a “self-taught” engineer who had achieved national recognition and admiration between 1906 and 1913 as soon as he orchestrated the design and building and construction of the Los Angeles-Owens River Aqueduct, the longest water conveyance system at the time. In addition, throughout his time as a supervising engineer, Mulholland had actually overseen the perfect of numerous embankment dams. Mulholland’s experience in concrete dam design, however, was lacking. Prior to the architecture and construction that the St. Francis Dam, he had actually only participated in the architecture of one other concrete gravity dam. Mulholland Dam, which was named in his honor, is a bent concrete gravity dam of similar height, constructed between 1923 and 1925. Back his suffer resided mainly in the architecture of embankment dams, Mulholland proposed that a concrete gravity dam would be the proper structure because that the canyon terrain throughout which St. Francis would certainly be built.

Multiple instances of poor judgment by Mulholland and several of his subordinates considerably contributed come the reason of the fail of St. Francis Dam. Plans for the dam to be based top top those previously prepared by Mulholland for the Mulholland Dam with tiny regard for site-specific investigations. When these plans were finalized and after building and construction began, the elevation of the dam was increased by ten feet on two separate occasions in bespeak to administer additional reservoir storage necessary to sustain the growing neighborhood surrounding the dam. Return these adjustments increased the dam’s elevation by twenty feet, no transforms were made to its base width. As a result, the intended security margin for structure stability reduced significantly. Mulholland’s team recognized this effect, however the design analysis, obtaining of extr materials, and extended building time come properly minimize the height increase were considered to be too costly come the project and to those stakeholders that were financially invest in the completion and operation of the dam.

St. Francis Dam failed at midnight on march 12-13, 1928 only twelve hours after its critical inspection by Mulholland. Because that a considerable period leading up to the critical inspection, leaking cracks to be observed within the key dam and also at its abutments which were dismissed together conditions usual of the dam type.

When investigate the cause of failure, it was clear that the proposed St. Francis Dam design was no reviewed by any kind of independent party. It to be also clear that it was designed to stop small foundation stresses only and also not accommodate complete uplift. The is estimated that the style exhibited a safety and security factor less 보다 one when Mulholland claimed it was designed utilizing a safety aspect of four. Back opinions vary, an ext recent and more thorough investigations assign the ultimate failure setting to weakening that the left abutment foundation rock because of the saturated problem created by the reservoir i beg your pardon essentially re-activated a large landslide that linked with a destabilizing uplift pressure on the key dam brought about failure come initiate at the dam’s left end. In rapid succession as catastrophic failure was arising at the left end, the maximum height section tilted and rotated i beg your pardon destabilized the right finish of the key dam causing catastrophic failure at the right finish as well.

In the after-effects of the failure, Mulholland took complete responsibility because that the accident during a hear stating, “Don’t reference anyone else, you know you can just close it top top me. If over there was human being error, ns was the human” and he “only envied those who were killed.” He ended his career by stepping under as head of the City the Los Angeles office of Waterworks & Supply shortly after the failure.

References:

(1) Alvi, I. A. (2013). Human factors in Dam Failures. ASDSO yearly Conference. Providence: association of State Dam safety and security Officials.

(2) Rogers, J. D. (2006, 6:2). Class Learned from the St. Francis Dam Failure. Geo-Strata, 14-17. 

(3) Rogers, J. D. & McMahon, D. J. (1993). Reassessment the the St. Francis Dam Failure. ASDSO annual Conference. Kansas City: association of State Dam safety and security Officials. 

(4) Rogers, J. D. & Hasselmann, K. F. (2013). The St. Francis Dam Failure: Worst American design Disaster the the 20th Century. AEG Shlemon Specialty Conference: Dam Failures and Incidents. Denver: association of Environmental and Engineering Geologists.

(5) VandenBerge, D. R., Duncan, J.M., & Brandon, T. (2011). Lessons Learned native Dam Failures. Virginia Polytechnic Institute and State University.

 


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View looking upstream throughout the beforehand stages of construction of St. Francis Dam (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).
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View of St. Francis Dam during building looking upstream. The two vertical towers, one at facility of key dam and also the various other at the ideal abutment (looking downstream), room for elevators come lift concrete to sluicing troughs (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).
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View spring upstream that St. Francis Dam prior to failure (colorized by Pony Horton). Note west concrete thrust block and west concrete dike extending from best abutment (looking downstream) of key dam i beg your pardon was added during construction to accommodate a 20 foot increase in structural height (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).

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View looking upstream at functioning St. Francis Dam (circa 1926 – colorized through Pony Horton). View reflects water gift released native one of five outlets for the objective of conducting downstream streamflow trial and error with regard to a water rights problem by downstream farmers and also ranchers. The test results supported your complaints (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).
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Destruction and also debris on a highway downstream ~ the failure of the St. Francis Dam (Photo source: the Los Angeles Times, 1928).
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Aerial watch of the submarine City of Santa Paula the job after the St. Francis Dam failure (Photo source: the Los Angeles Times, 1928).

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View spring downstream in ~ concrete dam fragments that were carried from and worked out downstream of the original dam site. Note elevation along sink slopes in i m sorry vegetation has actually been gotten rid of by floodwaters (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).
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A group of specialists assessing the St. Francis Dam continues to be after gift selected by branch C.C. Young to inspection the failure. This state commission checked out the site just once and published their findings within only 5 days after convening. Lock attributed the failure to piping the the foundation rock in ~ the ideal abutment primarily based on the observation that concrete fragments from this component of the dam traveled the the furthest downstream. Succeeding investigations by others insurance claim the fail initiated in ~ the soft structure rock at the left abutment where an old landslide had actually existed (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).
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Schematic mirroring the downstream distribution of concrete dam fragments and also their suspected initial placement at the dam. Soil and soft absent scoured through water flowing with the early stage dam breach produced silt-laden floodwaters which have actually been attributed with providing sufficient buoyancy to float the concrete fragments and carry lock as much as 4,000 feet downstream (Photo source: L.C. Hill et al., 1929 ASCE Proceedings).

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William Mulholland accepting complete responsibility because that the failure of St. Francis Dam at the Los Angeles county Coroner’s inquest (Photo source: J. David Rogers, 2013 AEG Shlemon Specialty Conference).


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Part 1 of an instructional video by Dr. Don U. Deere ~ above dam structures as component of the commonwealth Emergency management Agency’s professional Video series on dam safety.
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Part 2 of an instructional video by Dr. Don U. Deere ~ above dam structures as component of the commonwealth Emergency monitoring Agency’s professional Video series on dam safety.

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Local historian and St. Francis Dam experienced Frank absent summarizes the failure of St. Francis Dam and its aftermath.
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Dramatization that the failure of St. Francis Dam using video clip footage created by models and also miniatures.

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Frank Rock, St. Francis Dam expert, explains the disaster using historical visual aids during an episode of SCVTV’s ‘Legacy: Santa Clarita’s Living background with Leon Worden.’
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Brief clip native J. David Rogers’ presentation on the failure of St. Francis Dam at the 2013 Kansas Dam safety and security Conference.

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Video of J. David Rogers’ presentation on the causes of the St. Francis Dam failure at the 2013 Kansas Dam safety Conference
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Physics simulation that the St. Francis Dam failure and ensuing flood.

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Compilation that photographs arranged and manipulated to tell the story of the St. Francis Dam failure.