Review of Foundations, Abutments and Footings (Hool and Kinne, Eds., 1923), Sections 5 (Underpinning) and 6 (Foundations requiring special consideration), featuring the St. Francis Dam as a case study

By Michael Bennett, P.E. (GFT: Audubon, PA)

 

 

The St. Francis Dam breach on March 12th, 1928, drowned over 450 victims. The plentiful paper trail left by the disaster has led over the subsequent century to many follow-up studies of it utilizing more modern geotechnical analyses. Thus, a consensus (never a given in historical studies) exists around what happened geotechnically at the scene of the St. Francis breach. Engineer William Mulholland, legendary designer of the Los Angeles Aqueduct, selected a site in the St. Francis Canyon about 40 miles northeast of the City of Angels for a reservoir to expand the city’s water supply. Yet he never considered the site’s engineering geology and thus overlooked a fragile, fracture-prone mica schist formation and a dormant paleo-landslide at the proposed structure’s east abutment along with a friable sandstone formation along its proposed west abutment. As design progressed, Mulholland failed to incorporate adequate measures for uplift mitigation into his dam. During construction, he increased its height without also widening its base. The dam initially functioned well after its opening in 1926, but heavy rains in early 1928, kept the reservoir just inches below the dam’s crest for weeks. Permeation through the fissile mica schist beneath the east abutment and the dam itself thus increased per Darcy’s Law, and locals began noticing (Hundley and Jackson 2015, Rogers 1995).

 

Eventually, the growing leaks caught the attention of St. Francis’s dam keeper, Tony Harnischfeger. On the morning of March 12th, he telephoned Mulholland with his concerns. Mulholland and deputy engineer Harvey Van Norman promptly headed out to the St. Francis Dam, which they toured with Harnischfeger for about 90 minutes. Mulholland and Van Norman noted the multitude of leaks at the east abutment that had caught the dam keeper’s eye, as well as some more visible ones at the west abutment. While Mulholland told Harnischfeger to monitor the situation and check in with him regularly, neither engineer felt particularly concerned by what he had seen. However, at around 8 PM that evening, water level readings for the dam indicate that the St. Francis Reservoir started falling perceptibly. Eyewitnesses recalled no signs of increasingly severe leakage causing such a drop, and the reality was even more terrifying. The uplift forces against the St. Francis Dam were increasing as the swollen reservoir ever more deeply infiltrated the mica schist beneath and east of the massive structure, slowly raising it (Hundley and Jackson 2015, Rogers 1995).

 

 

By roughly 11:55 PM, the increasing permeation through the mica schist was causing two compounding problems at the St. Francis Dam. A significant piece of the dam’s east abutment, labeled as “Block 35” by investigators, broke away and effectively created a nozzle through which water cascaded from the reservoir. Simultaneously, the water seeping into the mica schist reactivated the ancient landslide, a problem only worsened by the “nozzle” that had formed at Block 35. At 11:57 PM, the entire east abutment gave way; the precise time is known because it knocked out a power line just downstream of the reservoir. The abutment’s failure in turn removed the final check on the ancient landslide, which broke loose in full force and left a trail of mica schist fragments through the St. Francis Valley. The St. Francis Reservoir wrenched the dam’s center away from its west abutment as its waters surged through the final breach. Once the reservoir had fallen about 40 feet, if not more, the crack between these two sections had grown wide enough that the roaring waters poured through it and the west abutment also gave way, although the delay resulted in considerably less damage along the valley’s west side. All that remained standing when the Sun rose on March 13th was the dam’s center, looming – in a macabre yet fitting way – like a tombstone over the scene. The mammoth crack in its base testified to just how close it, too, had come to being toppled by the torrent that had killed over 450 Californians, including Tony Harnischfeger (Hundley and Jackson 2015, Rogers 1995).

 

 

The St. Francis Dam breach remains the second deadliest in American history, behind only the South Fork Dam breach of 1889 (see Johnstown Flood). A recap of famous dam failures written in the immediate aftermath of St. Francis prominently listed the South Fork breach, and the two disasters have some parallels. At the center of both stood men overconfident in their abilities to safely design and construct dams – Benjamin Ruff at South Fork, William Mulholland at St. Francis. Shortcomings in the dam-building process at each site were apparent to others almost from the start but went unheeded. Following the disasters, public outcry was enormous. More recently, both sites are now memorialized by the US government. In 2019, President Trump signed the St. Francis National Memorial into law on the disaster’s 91st anniversary, and fundraising to build a visitors’ facility at the breach site is ongoing (Bowers 1928, Hundley and Jackson 2015, SFDNMF 2021).

 

 

Yet while history often rhymes, it doesn’t repeat itself exactly, and several important distinctions remain between the South Fork and St. Francis Dam failures. William Mulholland, unlike Benjamin Ruff, had decades of engineering experience before designing the St. Francis Dam. Most of his prominent contemporaries in California civil engineering during the Jazz Age had on-the-job, not academic, training in their field, and Mulholland had previously supervised the design and construction of several dams which remain in service to this day. Moreover, the St. Francis breach was speedily investigated. Expert panels and independent engineers and geologists started their work within weeks of the dam’s demise and published their findings within the year – in some cases, within a month. The St. Francis tragedy also got the wheels of government turning. The Roaring Twenties remain renowned for their laissez-faire economics, but the Progressive Era belief that government regulation was needed to safeguard public health and safety remained intact. Thus, in 1929, California tightened its laws to require that all dams be built under a licensed engineer’s supervision. By then, William Mulholland – a titan in the Los Angeles engineering and water scene for nearly half a century – had been ushered into retirement; he died in 1935, shattered by the disaster (Hundley and Jackson 2015, Rogers 1995).

 

 

The St. Francis Dam breach also broke sharply from the Johnstown saga in the technical record it left behind. By 1928, civil engineering had matured vastly from where it had stood in 1889, well more than even the passage of four decades would indicate. The investigative reports on the St. Francis disaster make this clear, reflecting a degree of technical precision and breadth of scope far beyond what ASCE’s 1891 South Fork Dam report contained. To be sure, the St. Francis reports – like the Johnstown report – were influenced by the powers that were and their interests. As of 1928, California’s delegation in Washington, DC was working to steer the Boulder (now Hoover) Dam through Congress, and the failure of an extant concrete gravity dam in the Golden State threatened the new structure’s prospects. It was undoubtedly for this reason that the Governor’s Commission, the blue-ribbon panel investigating the St. Francis breach, concluded that the dam’s surviving center section demonstrated the strength of concrete gravity dams while blithely skating past evidence that it, too, had nearly failed. Overall, though, the St. Francis reports avoided the egregious whitewashing and disingenuous interpretation of technical details that had permeated ASCE’s South Fork Dam report. The St. Francis investigations’ findings have since been debated and at times found incorrect, but the experts presented the technical facts of the case straightforwardly, and their assessments of what had happened were relatively well-developed, if not yet quantitative (Hundley and Jackson 2015, Wiley et al. 1928).

 

Far more historical and civil engineering consensus exists on how the St. Francis Dam breached than on whether Mulholland’s admittedly flawed design met the standard of care for its day. Some researchers have stated it did, stating that many dam engineers in the 1920s did not consider factors such as uplift. Others have disagreed, concluding that uplift concerns were increasingly of interest to Jazz Age civil engineers. An authoritative source on best practices for design and construction of dam foundations in the mid-1920s, when the St. Francis Dam was on the drawing board, would certainly shed new light upon the debate. Foundations, Abutments, and Footings by Hool and Kinne (1923), a readily available engineering text of its time, seems to be an excellent example of such a reference. Sections 5 and 6 of the book cover specialty topics in foundation engineering, including, fortuitously, dam foundations. These sections can thus provide a valuable perspective on contemporary best practices for engineering dam foundations and how many of these William Mulholland incorporated or overlooked as he oversaw the design of the St. Francis Dam in 1923 (Hool and Kinne 1923, Hundley and Jackson 2015, Rogers 1995).

Section 5 of Hool and Kinne (1923) was penned by Edmund Prentis. “Ted,” as he was known, was the Chief Engineer of Spencer, White, and Prentis, the major New York City foundation engineering firm which did extensive work on the city’s then-new subway system and on Yankee Stadium. Prentis and his colleague Lazarus White, a fellow contributor to Hool and Kinne (1923), literally wrote the book on underpinning several years later – 1931’s Underpinning (see Hool and Kinne (1923), Section 3, Part A).  “Underpinning,” Prentis began, “is the art of installing new foundations, either in lieu of old ones, or under them, and is distinctly an art, rather than a science.” While geotechnical work today is far more scientific and quantifiable than it was in 1923, it remains somewhat of an art as well, much more so than most subdisciplines of civil engineering.  Prentis ably covers several valuable topics in his 12 pages, most notably the support of excavations and existing foundations (Prentis 1923).

 

 

Section 6 of Hool and Kinne opened with a subsection on deep basement foundations by Horace Baker, the Chief Engineer of Chicago firm F.D. Chase. He reviewed several case studies of basement construction and well-point excavation dewatering, most notably the Ritz-Carlton Hotel in Atlantic City, NJ. (The building still stands as a condo tower and gained some fame through the HBO drama series Boardwalk Empire, where it was the home of politician/gangster Nucky Thompson.) Baker’s section was followed by one on foundation waterproofing by Earl Swanson, then an independent civil engineer in Chicago. Swanson spent his rather brief section discussing methods of waterproofing concrete basement walls; one such method, paraffin wax, remains in geotechnical use, albeit now for sealing Shelby tubes. Swanson’s write-up was in turn followed by an even shorter subsection on retaining wall foundations by James Meem, who had previously contributed to Section 3 of Hool and Kinne (1923). Meem attempted to give his Section 6 pointers on retaining wall foundations a stronger theoretical basis than his notes on well foundations and cofferdams in Section 3. However, his valiant efforts were largely fumbling, as Meem – like geotechnical engineering writ large in 1923 – remained unaware of how effective stress worked (Baker et al. 1923).

 

A meatier subsection of Section 6 came from Philadelphia engineer Stephen Slocum, who discussed foundations for machinery. He correctly noted that such foundations required considerations from structural dynamics, such as resonant frequencies, and explained through a series of clear derivations how these could be incorporated into foundation design for turbines, stationary engines, looms, and other industrial equipment. Slocum knew of what he spoke, since he worked in 1923 for N.W. Akimoff, a firm specializing in the production of vibration-dampening bracing for heavy machinery. A century after Hool and Kinne (1923), Akimoff remains in business as the Vibration Specialty Corporation, and its technologies have been utilized in engines ranging from Model T Fords to the US Navy’s nuclear submarines. While Slocum’s expertise was undeniable, his lengthy discussion of the value of Akimoff systems in preventing common issues tied to excessive vibration of machinery foundations was clearly self-promotional. Modern geo-professionals are taught that such obvious commercialism in technical literature is unacceptable, and potential publications that cross this red line are usually rejected by journals and conferences. Still, the technical merits of the Akimoff technologies Slocum described were undeniable, as was his verve in covering them (VSC 2021).

Nestled between Baker, Swanson, and Meem’s short, sweet write-ups and Slocum’s longer, grandstanding-adjacent one was Charles Paul’s subsection on dam foundations. Paul, an 1895 graduate of MIT, had worked on municipal water supply and filtration projects for the first decade of his career, then had spent another decade with the US Bureau of Reclamation tackling irrigation, canal, and dam projects. Notably, he had been the chief engineer for the design and construction of the Arrowrock Dam in Idaho, the world’s highest dam upon its completion in the mid-1910s. In 1923, Paul was closing in on a decade as the Chief Engineer of the Miami Conservancy District in Ohio, a flood control organization founded after floods had devastated southwestern Ohio in 1913. (The District survives today.) Only the previous year, he had published a paper on his experiences with the District’s hydraulic fill dams in the Transactions of ASCE. Paul’s portion of Section 6 therefore provides an excellent benchmark for assessing the standard of care for dam foundation design and construction in 1923 and whether William Mulholland met it during his work on the St. Francis Dam (Baker et al. 1923, Marquis 1922, MCD 2025 B).

“The main requirements to be considered for a dam foundation,” Paul began, “are: bearing power, water tightness or control of seepage [,] prevention or control of upward pressure, prevention of sliding of the dam on its foundation or of the foundation itself, and protection against scour below the downstream toe or apron.” He noted that the crucial nature of these considerations could scarcely be overstated, as “failure to understand foundation conditions, or to appreciate their importance, has often resulted in disaster.” Paul then discussed foundation requirements for dams of various heights. For masonry or concrete dams over 200 feet tall, he declared (the St. Francis Dam would top out at 205 feet), “firm, hard rock, without open seams, fissures, or faulting,” was “the only suitable foundation” for ensuring adequate bearing capacity, seepage control, and uplift prevention. Clearly, the friable sandstone and fissile mica schist at the site Mulholland had chosen hardly met this definition. Paul was surely unfamiliar with the St. Francis site, but he knew not every site would present ideal subsurface conditions for whatever dam engineers desired to build there, and he cautioned his readers accordingly. “Subsurface examinations become increasingly important as the character of the material is less reliable,” Paul explained, “and special treatment is often necessary to meet the various foundation requirements” (Baker et al. 1923, Hundley and Jackson 2015).

“It is desirable,” Paul wrote, “to have a careful geological examination of the foundation conditions,” ideally one in the form of “an investigation and report by an expert practical geologist.” The factors he listed as important ones for such a study to ascertain on a site included the bedrock’s “probability of fissures and faulting, [and] former upheavals and disturbance” – in other words, historical geologic hazards such as paleo-landslides. Such a study at the St. Francis site would most likely have uncovered the vulnerability of the sandstone and mica schist formations to seepage, as well as the paleo-landslide flanking the proposed dam’s east abutment (which several geologists readily observed at the site after the breach). However, William Mulholland neglected to consider the site’s engineering geology as he began designing the dam. He and J.P. Branner, an esteemed Stanford geology professor (and mentor of future President Herbert Hoover), had briefly visited the site prior to design getting underway, but such a trip hardly qualified as a proper geologic study. The oversight was particularly egregious given that a decade earlier, workers constructing the Los Angeles Aqueduct under Mulholland’s supervision nearby had complained of the mica schist’s hazardous dip and its tendency to expand upon excavation (Baker et al. 1923, Rogers 1995).

 

Paul then went into detail about what a proper subsurface investigation for a dam entailed. He recommended the use of wash borings for soil samples, a common technique at the time (see Hool and Kinne (1923), Section 1). Paul added that these borings were most valuable if used in conjunction with test pits, which he noted – in a phrase as true now as then – “afford the only opportunity to inspect the material in place.” Moreover, he noted that rock corings extending at least 20 feet were necessary to assess the character of the site’s bedrock, such as its quality, potential faulting, and verifying its presence. Paul cited his experiences at the Arrowrock Dam as evidence of bedrock corings’ importance. The cores there, he explained, the cores had encountered a layer of soil beneath a layer of bedrock, revealing the presence of a buried paleo-ledge that could have severely compromised the dam’s foundation had it not been revealed. Paul noted that boulders could similarly be mistaken for intact bedrock with rock corings; modern geo-professionals might well add karstic formations to the list (Baker et al. 1923).

Unfortunately, William Mulholland’s site investigation for the St. Francis Dam fell far short of Charles Paul’s guidelines. His engineers and workers excavated no test pits and performed only 4 or 5 borings for the dam. All these borings were concentrated along the proposed west abutment and extended a mere 14 to 16 feet deep. The men did conduct a crude falling-head permeability test in one boring, which Paul didn’t describe in his write-up. While the design team performed additional exploration on the east abutment, their technique of choice likely did far more harm than good. In testimony to a coroner’s jury after the St. Francis breach, multiple workers recollected excavating – partially with blasting powder – a tunnel about 30 feet long and “big enough for a man to work running a wheelbarrow” into the mica schist to assess its quality. Not until the construction of the dam began was the tunnel backfilled with concrete. Excavating a sizable tunnel into the mica schist using uncontrolled explosives and then leaving it open for a lengthy period could only have harmed the geological stability of the site and the dam. This was especially true given the mica schist’s tendency to expand upon atmospheric exposure, which led the workers to refer to the formation as “heavy ground” (Hundley and Jackson 2015).

Paul next turned to how to properly excavate bedrock for a dam foundation, which he knew well from his work at the Arrowrock Dam. “The preparation of the rock foundation for a high masonry dam,” he wrote (Paul used the terms “masonry” and “concrete” somewhat interchangeably in his subsection), “is one of the vital features of construction [and] all loose or soft rock should be carefully cleaned off and removed.” Paul qualified his instructions to account for the susceptibility of some rock types to decomposition upon exposure. He explained that such rock should initially be excavated only to within a few inches of the dam foundation’s intended limits and that the remaining material would most prudently be removed just prior to the placement of concrete. Alas, Paul’s guidance on rock excavation seems to have gone unheeded at the St. Francis Dam site. The workers’ testimony about their ill-advised tunnel into the mica schist is compounded in the historical record by photographs showing construction of the dam’s foundation proceeding without proper clearing of talus and loose rock from the hillsides prior to pouring concrete (Baker et al. 1923, Hundley and Jackson 2015).

 

After this build-up, Charles Paul covered three key techniques for preventing uplift and seepage beneath dams: subsurface grouting, cutoff trenches, and uplift wells. “Prevention or control of upward pressure in masonry dams is a subject which has been under lively discussion for many years,” he wrote, and “is not difficult usually.” By 1923, civil engineers had been sounding the bugle of uplift warnings for over a decade, particularly after the uplift-induced Austin Dam breach had killed 78 people in north-central Pennsylvania in 1911. (Only a timely telephone call from a woman whose home overlooked the dam had spared hundreds more.) “It is a crime to design a dam without considering upward pressure,” one prominent US civil engineer had declared in the wake of the Austin breach, and an article on addressing the issue appeared in the Transactions of ASCE the next year. Civil engineers were still disputing how best to compute it in 1923, but, as Paul wrote, “all are agreed that it must not be disregarded and should reasonably be provided for” (Baker et al. 1923, Hundley and Jackson 2015, Kline et al. 2021).

Paul discussed subsurface grouting first, noting that doing so for rock foundations beneath dams was “often resorted to as a matter of precaution. In fact,” he elaborated, “it is standard practice in the construction of high masonry” and concrete dams. Paul proceeded to spend several pages discussing grouting techniques in a refreshingly organized manner compared to the somewhat slapdash write-ups on many geotechnical topics in Foundations, Abutments and Footings. Grouting had already been employed successfully at several major US dams by 1923, including by Charles Paul himself at the Arrowrock Dam in the mid-1910s. There, he had directed crews in drilling two lines of holes 30 to 40 feet deep along the length of the dam, one of which workers had then grouted. Later in the 1910s, Paul had supervised similar operations at the Lockington Dam for the Miami Conservancy District. (His handiwork there was superb; additional grouting was not required for another 90 years.) Paul knew from Darcy’s Law that creating a grout curtain beneath a dam lengthened the flow path, l, of water under the structure, thereby decreasing the hydraulic gradient, i, and thus the total seepage below it. Yet the St. Francis Dam incorporated no program of foundation grouting despite the known potential for permeability issues in the “heavy ground” mica schist. In fact, no evidence has emerged that Mulholland and his lieutenants even considered undertaking such a program there (Baker et al. 1923, Geo-Solutions 2022, Hundley and Jackson 2015).

Paul also peered far into the geotechnical future at least once during his discussion of subsurface grouting. One particularly robust grouting method, he noted, involved “drilling holes, properly spaced, to the depth required, and grouting in reinforcing bars which will be carried up and tied into the masonry in such a manner as to effectually tie dam and foundation together.” Paul observed that this technique both curtailed subsurface seepage and firmly anchored the dam to the subsurface strata underlying it. Modern geo-professionals, however, may well envision broader applications for this method – it constitutes the fundamental design of a micropile! Currently, these are understood to have originated in Italy following World War II. However, Paul’s description of the technology indicates that the geotechnical history books may be due for some revision on this count (Baker et al. 1923, FHWA 2005).

Paul next gave his attention to the engineering of cutoff trenches for controlling seepage and uplift below dams. He noted that such trenches were most commonly excavated “across the foundation along the heel or upstream face of the dam” and “should be at least 3 or 4 ft. deep in any case, and should be continued up the abutments, and along the full length of the dam.” For dams on softer rock, Paul added, “deep cut-offs or curtain walls of concrete are also desirable at both upstream and downstream faces of the dam.” Paul knew of what he spoke, having designed constructed several cutoff trenches for his dams in the Miami Conservancy District. Yet William Mulholland once again missed the mark on this method of seepage and uplift mitigation. Carl Grunsky, a well-regarded civil engineer on the California water supply scene during the Jazz Age, noted during a March 1925 visit to the St. Francis Dam construction site that “there was no indication of trenching up the hillsides to provide vertical abutment faces.” The situation was equally woeful in the dam’s center, where the upstream portion of the foundation not only was excavated 8 feet shallower than the remainder but was not even excavated through overburden soils to bedrock. Mulholland and his St. Francis team could scarcely have made a less considered decision in this regard (Baker et al. 1923, Hundley and Jackson 2015, Rogers 1995).

Finally, Charles Paul covered the civil engineering aspects of uplift wells for dam foundations. In most large dams of the age, he noted, it was “feasible to construct drainage galleries lengthwise of the dam [and] close to the upstream face,” wherein uplift wells could be drilled “to provide relief for any upward [hydrodynamic] pressure which may exist.” Paul himself had used the technique at the Arrowrock Dam, where his crews had drilled two rows of holes to rock along the future structure’s foundation. After the workers had grouted one of the two rows of holes, they had used formwork to gradually extend the other row upward as the concrete dam and its drainage gallery were built. Nor was Paul alone in this regard, as many prominent dams of the era featured uplift wells. In fact, New Mexico’s Elephant Butte Dam, constructed in the late 1910s, incorporated subsurface grouting, a cutoff trench, and drainage wells. Lamentably, William Mulholland and the St. Francis Dam design and construction teams came up short on this count as well, albeit by less than on others. Mulholland did recognize the need for some uplift protection at St. Francis and included 10 wells 2 inches in diameter beneath the central 120 feet of the dam. Since it was 661 feet long, though, his design choice left 270 feet of the structure on either side of its center – i.e., both abutments – unprotected by such wells. Mulholland’s token uplift wells bore unfortunate parallels to the 20 lifeboats the RMS Titanic had carried on its ill-fated maiden voyage just over a decade prior to 1923. The St. Francis Dam’s handful of uplift wells and the Titanic’s handful of lifeboats sufficed only to check a box that safety measures had been included and not to make sure those measures were up to their intended tasks (Baker et al. 1923, Hundley and Jackson 2015).

Collectively, Charles Paul’s subsection of Section 6 paints a rather unflattering picture of William Mulholland’s design of the St. Francis Dam. The subdiscipline of dam foundation engineering was clearly coming into its own by the Roaring Twenties, but Mulholland’s work at St. Francis reflects an engineer badly behind his times in that regard. “The Chief,” as his men knew him, failed to have his team conduct a detailed geologic study or subsurface investigation of his intended dam site, even when existing geologic information was readily available from other projects he had done nearby. The limited investigation he and his team did complete may well have been counterproductive, as the large tunnel they excavated into the mica schist on the east abutment site likely factored into the St. Francis Dam’s demise. Nor did Mulholland incorporate sufficient means of warding off seepage and uplift issues into the structure’s foundation. His design for St. Francis included neither subsurface grouting nor cutoff trenches and utilized only a dismal smattering of uplift wells. Finally, Mulholland’s crews compounded their boss’s design errors by doing a poor job excavating the dam’s foundations (Baker et al. 1923, Hundley and Jackson 2015).

William Mulholland’s 50-year engineering career included many feats of technical ingenuity, persistence in the face of adversity, and triumphing over long odds. Sadly, Section 6 of Foundations, abutments and footings makes clear that his work at St. Francis fell dramatically short of the standard of care for the design and construction of dam foundations in the 1920s. In fairness, Mulholland was neither the first nor last civil engineer to fail to meet the best practices of their day and age, and geo-professionals must be ever on their guard against this peril. Indeed, the standard of care serves as a memorial to those who have suffered or perished when civil engineers have, wittingly or otherwise, failed to adhere to its previous iterations. Another such memorial stands in the form of engineering licensure laws. While California had such laws on its books prior to 1928, the St. Francis Dam breach justifiably heightened pressure on Golden State legislators to tighten these statutes, which they did the following year. Nearly a century on from the failure, such laws for civil engineering licensure – along with the standard of care and the crumbling remnants of the St. Francis Dam – stand as a stark reminder that the seal of a professional civil engineer is truly, as esteemed forensic engineer Roberto Leon has noted, a “license to kill” (Hundley and Jackson 2015).

 

Acknowledgments

Sebastian Lobo-Guerrero, Ph.D., P.E., BC.GE, F.ASCE, (A.G.E.S., Inc.: Canonsburg, PA), the author’s former colleague, reviewed the entry’s geotechnical content. Thomas Kennedy (Geopier: Davidson, NC), the author’s Virginia Tech classmate, co-authored a 2021 version of the entry posted on an independent webpage. Prof. Donald “DC” Jackson (Lafayette College: Easton, PA) taught the author’s undergraduate History of Technology course, during which the students read Jackson’s book about the St. Francis Dam failure, Heavy Ground. Prof. Roberto Leon, P.E. (Virginia Tech: Blacksburg, VA) gave the author and his Virginia Tech geotechnical classmates a singularly memorable guest lecture on forensic engineering in 2018.

 

References

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Bowers, N.A. 1928. “St. Francis Dam catastrophe – a great foundation failure.” Eng. News-Record, 100 (12), 466-473.

Charitan, A. 2019. “America’s newest national monument honors the lesser-known history of the St. Francis Dam disaster.” Roadtrippers, May 23. Accessed May 11, 2025. https://roadtrippers.com/magazine/st-francis-dam-disaster-monument/

FHWA (Federal Highway Administration). 2005. Micropile design and construction reference manual. Pub. No. FHWA NHI-05-039. Washington, DC: FHWA.

Geo-Solutions. 2022. “Piqua, OH: Lockington Dam Foundation Pressure Grouting.” Geo-Solutions, Inc. Accessed May 15, 2025. https://www.geo-solutions.com/resources/piqua-oh-lockington-dam-foundation-pressure-grouting/

Harrison, S. 2018. “From the archives: The 1928 St. Francis Dam collapse.” Los Angeles Times, Mar. 12. Accessed May 11, 2025. https://www.latimes.com/visuals/photography/la-me-fw-archives-the-1928-st-francis-dam-collapse-20180206-htmlstory.html

Hundley, N., and D.C. Jackson. 2015. Heavy ground: William Mulholland and the St. Francis Dam disaster. Oakland, CA: University of California Press.

Kline, R.A., I.A. Alvi, and G. Richards. 2021. “The 1911 Bayless Dam failure: Physical and human factors.” In Proc., Dam Safety 2021 – 38th Annual Conference, 19 pp. Nashville, TN: Association of State Dam Safety Officials.

Marquis, A.N. 1922. Who’s who in engineering: a biographical dictionary of contemporaries. Chicago, IL, USA: A.N. Marquis and Co.

MCD (Miami Conservancy District). 2025. “Lockington Dam.” The Miami Conservancy District. Accessed May 15, 2025. https://www.mcdwater.org/flood-protection/lockington-dam

MCD (Miami Conservancy District). 2025. “Mission & philosophy.” The Miami Conservancy District. Accessed May 14, 2025. https://www.mcdwater.org/about-mcd

Moles. 1941. “Jack Madigan and Ted Prentis selected by Moles for outstanding achievement – award dinner Feb. 4.” The Moles, Nov. newsletter.

Prentis, E.A. 1923. “Section 5: Underpinning.” In Foundations, Abutments and Footings, G.A. Hool and W.S. Kinne, eds. New York, NY: McGraw-Hill, 252-263.

Rogers, J.D. 1995 “A man, a dam, and a disaster: Mulholland and the St. Francis Dam.” In The St. Francis Dam disaster, D. Nunis, ed. Los Angeles, CA: Historical Society of Southern California, 1-110.

SCV History. 2017. “St. Francis Dam disaster: William Mulholland, Harvey Van Norman inspect disaster site.” Santa Clarita Valley history. Accessed May 11, 2025. https://scvhistory.com/scvhistory/lw3084.htm

SFDNMF (St. Francis Dam National Memorial Foundation). 2021. “Latest news.” St. Francis Dam National Memorial Foundation, Feb. 1. Accessed May 11, 2025. https://stfrancisdammemorial.org/latest-news-2/?v=0b3b97fa6688 

VSC (Vibration Specialty Corporation). 2005. “Our History: 1918.” Vib.com. Accessed May 13, 2025. https://www.vib.com/history/1918/

Wiley, A.J., G.D. Louderback, F.L. Ransome, F.E. Bonner, H.T. Cory, and F.H. Fowler. 1928. Report of the commission appointed by Governor C.C. Young to investigate the causes leading to the failure of the St. Francis Dam near Saugus, California. Sacramento, CA: California State Printing Office.