Floodpath

by Jon Wilkman

  When he was told about this startling revelation, Mayor Cryer was noncommittal but admitted, “I have been suspicious from the beginning that the dam may have been tampered with.” In support of his doubts, Cryer noted that there had been no heavy rainfall around the time of the collapse, as in other famous dam failures. He added that Mulholland had investigated the site only hours before and declared it safe. Finally, the Mayor found it suspicious that the dam collapsed almost exactly at midnight “when everybody was in bed and asleep.”41

  The Los Angeles Evening Express editorially shivered at the thought that someone would dynamite the St. Francis Dam. The paper described the culprit, or culprits, as having “a soul 10,000 times blacker than killer Hickman’s, and the hand colder, infinitely more cruel, than the one that carved the body of little Marion Parker … If it is proven that the dam was dynamited then there will be recorded in history the most dastardly crime of the century.”

  The beleaguered residents of the Owens Valley responded with outrage: “Of all the various things that the Water and Power Department has stooped to many years past in its treatment of the Owens Valley, nothing more despicable has ever been done than trying to hoodwink the people of the country with this cry of dynamite … certainly something that cannot stand the light of day, and shows that to our sorrow those responsible for the great catastrophe of last week are thinking more about saving their own reputations than they are about the immense damage that they have done.”

  Board of Water Commissioners Chairman R.F. Del Valle replied, “We turned the evidence over to the proper officials. We don’t say it’s proof of the dynamiting. We only say it seems important and should be further investigated.” The editors of the Los Angeles Record sneered, describing the new “evidence” as “a ghastly joke.”

  Despite Del Valle’s claims that the rope and note were in the hands of the proper authorities, Coroner Nance was quoted as saying: “I have no knowledge of any evidence being found in support of the dynamiting theory. My investigators have made no such report to me.” The Los Angeles Chief of Detectives weighed in that he had not received anything either. County District Attorney Asa Keyes said the same. Ventura Deputy Sheriff Harry Wright was more blunt: “It’s all bull. If anybody had this evidence I would have. I haven’t got anything.”42

  Representatives of the Los Angeles Board of Water and Power Commissioners denied separate knowledge of the Pyles investigation and issued a prudently worded statement to reassure suspicious Ventura County leaders and flood victims: “Los Angeles is not evading whatever moral responsibility the city may have. It will go ahead with relief work and restoration without slackening.”43 Dynamite or not, the City of the Angels was still on trial, and questions remained. Everyone was eager for answers from one man—William Mulholland. What did he know, and, most important, what had he done?

  10.

  Los Angeles on Trial

  Nine days after the St. Francis flood ebbed into the Pacific, accusations of a link between the disaster and a dynamite plot headlined newspapers and clashed with angry denials. In the midst of this furor, the Los Angeles County Coroner’s Inquest was just beginning. The Inquest wasn’t a criminal trial, but the hearing could lead to indictments—and perhaps a conviction for mass murder. The stakes were high for William Mulholland, the city of Los Angeles, and the future of dams in the United States and perhaps around the world.

  Dams, reservoirs, and an aqueduct were critical to Mulholland’s 1920s survival and growth plan for Los Angeles, just as large-scale waterworks had been central to human civilization for more than six thousand years. Whatever the cause of the catastrophe that began in San Francisquito Canyon, to understand what happened, it was essential to know what should have kept the St. Francis Dam strong, as well as what could have brought it down.

  Since the first dams in the ancient Middle East, engineers learned as much from failures as they did from successes—perhaps more. During millennia of trial, error, and applied computations, two approaches to dam design were developed: massive and structural. A massive dam depends on gravity and the barrier’s weight to resist hydrostatic pressure. A structural dam uses its shape. An arched dam is an example. When the weight of water presses against the upstream curve of the arch, the load is distributed to either side, pushing against the abutments to increase the structure’s strength and stability. Another kind of gravity-based barrier, a buttress dam, uses the additional surface area of sloping faces to spread the hydrostatic pressure. Sometimes characteristics of both gravity and structural approaches are combined. The St. Francis Dam was an arched gravity dam.

  Dams are further defined by the materials used to build them. The oldest and most common types are embankments, constructed with earth and rock. Some include a core of compacted clay, often sealed with an outside sheath of mortar or concrete. In 1928, dams constructed of mass concrete were relatively new. The first, Crystal Springs Dam, built between 1887 and 1889, supplied water to San Francisco. It was strong enough to survive the 1906 earthquake.1

  During the first decades of the twentieth century, dam engineering and construction techniques evolved rapidly. Dams became larger and stronger, but not always safer.2 Between 1900 and 1928, at least twenty-five dams failed in the United States.3 Worldwide, the number was seventy-three.4 There was much to learn—and unlearn—and it could take time for the latest ideas to move from state-of-the-art to common practice. Failures hastened the pace.

  From the Valley of the Nile to San Francisquito Canyon, dam failures usually result from a few basic causes. One third occur because of “overtopping.” When a reservoir overflows the crest of a dam, hydrostatic pressure can become greater than the structure is designed to resist. As a result, the barrier can tip over—overturn—or just break apart. This is often a consequence of excessive rain and flooding. In Pennsylvania, the infamous Johnstown Flood of 1889 was caused when the South Forks Dam, which had been poorly maintained and built with inadequate spillways, overtopped during a torrential storm. In 1916, the collapse of the Lower Otay Dam near San Diego was another overtopping disaster hastened by inadequate spillways. In some situations, a buildup of river-borne silt and sediment also increases forces acting on a dam, leading to failure.

  About 30 percent of dam disasters are blamed on poor foundations or inadequate anchoring to the site. The 1911 failure of the Austin Dam in Pennsylvania is an example. The concrete gravity structure slid on a water-saturated shale foundation and broke open.

  Internal erosion can pick apart the rock and sand in a dam’s foundation. This process, called “hydraulic piping,” accounts for approximately 20 percent of dam failures. In 1909, hydraulic piping led to the failure of the Ashley Dam, a forty-foot-high reinforced concrete barrier in Pittsfield, Massachusetts, that collapsed when the reservoir was filled for the first time.

  The remaining percentage of dam failures are blamed on various design flaws, environmental impacts (yes, even burrowing rodents), and in rare instances sabotage. In 1924, a man in Saltville, Virginia, was arrested for allegedly dynamiting a one-hundred-foot-high dam, causing a flood that killed nineteen. Like accusations against alleged Owens River Aqueduct bomber Perry Sexton, the case was dismissed for lack of credible evidence. Even less common than sabotage, a 6.3 earthquake on June 28, 1925, brought down the Sheffield Dam in Santa Barbara, California. Intense shaking “liquefied” the sandy foundation of the twenty-five-foot-tall barrier. The center section of the embankment broke apart and “floated away.”5

  The engineers and construction contractors on the Los Angeles County Coroner’s Inquest jury knew that a gravity dam like the St. Francis is essentially a giant wedge jammed between canyon walls—wider at the base, where water pressure was greatest, angled on the upstream face, flatter in the back, and narrower toward the crest, where hydrostatic forces were least. In profile, a concrete dam suggests an old high-button shoe. At the base of the barrier, a protruding downstream “toe” spans the width of the structure, adding stability.
A “heel,” beneath the greatest amount of water, serves a similar function along the upstream base.

  A dam faces physical assaults from all sides. As early as the sixteenth century, engineers tried to quantify these forces. By the 1700s, some basic construction principles had been developed, but it wasn’t until the 1850s that French engineers J. Augustin de Sazilly and F. Emile Delocre devised formulas to locate and measure stresses in masonry dams.6 In the 1870s, a Scots civil engineer and mathematician, W.J.M. Rankine, established that the strength of the middle third of a dam, as viewed in cross section, determined the structure’s resistance to tipping or cracking.7

  Cross-section diagram of the St. Francis Dam (Author’s collection)

  In 1913, George Holmes Moore described the cross section of a properly built dam as a giant triangle with a proportion of three to two—three being the height and two the base.8 Additions and improvements to this evolving mathematical approach allowed designers to determine a dam’s most effective height, width, and shape, taking into account gravity, or the weight of the structure, hydrostatic pressure from the reservoir, and the nature of construction materials used.9

  During the process of design and construction, applying these engineering principles builds in a “factor of safety.” A dam should have at least twice the strength and stability it needs, and ideally more. Just as important, even ancient engineers knew a solid and secure foundation was critical to a successful design. For maximum stability, a dam should be as impervious as possible to water, sit tightly on a solid base, and be firmly anchored to the abutments. When William Mulholland built the St. Francis Dam, he was well aware of these requirements. His responsibility was to decide how to respond to them.

  In June 1924, when the Chief began work on the St. Francis Dam, he ordered a six-days-a-week construction schedule. DWP reports and testimony during the Inquest described what happened. The canyon floor and hillsides were prepared by hydraulic sluicing, a method miners used in the 1800s to uncover and loosen mineral deposits during the California Gold Rush. Mulholland and other engineers also employed sluicing during the construction of earthen and rock-filled dams. Water-sifted soil and compacted clay is used in the core and foundations of structures called, appropriately, “puddle fill” or “hydraulic fill” dams, a construction process that dates to the late eighteenth century.10

  The Chief had considerable experience with hydraulic sluicing to construct earthen dams.11 The two earthen barriers that support the Haiwee Reservoir, near the beginning of the Owens River Aqueduct, and the Lower and Upper San Fernando Dams, at the end, involved sluicing. The Chief’s earthen dam-building experience was impressive, but not perfect. As a consultant for the private San Francisco–based Spring Valley Water Company, Mulholland was involved in hydraulic sluicing during the construction of the Calaveras Dam, a concrete-faced earthen structure northeast of the California town of Milpitas. On March 24, 1918, the dam’s foundation liquefied and partially collapsed.12 Fortunately, there were no casualties, but Mulholland’s Irish countryman and fellow engineer M.M. O’Shaughnessy, who worked for the Spring Valley Water Company, privately criticized the Chief—fairly or not—for his role in the failure.13

  Sluicing is wet and sloppy work but the only practical way to excavate massive volumes of rock and soil before the development of large earth-moving machinery. In San Francisquito Canyon, men on wooden platforms held heavy hoses and confronted the terrain like determined firemen, directing jets of water to blast away surface soil and debris to expose beds of underlying, harder rock. Afterward, laborers wearing rubber hip boots waded through muck with picks and shovels to remove remaining pieces of rock.

  The next step was to divert San Francisquito Creek to allow work to continue in a relatively dry environment. To do this with the assistance of sluicing, a low eight-foot-high concrete barrier, called a cofferdam or cutoff wall, was dug by hand and extended across the canyon floor—but in the case of the St. Francis Dam, not up and into the abutments. Pumps sucked away excess water trapped behind the cofferdam, and a system of drainage wells and pipes (Mulholland called them “bleeders”) were installed where the wall of concrete would eventually stand. Later, as the base of the emerging structure grew wider, the cutoff wall was incorporated into the upstream base of the wall of concrete, and the bleeders kept water from accumulating beneath the foundation.

  Continuing flow from the creek was redirected via an elevated wooden channel, or flume, and released downstream. DWP reports and Inquest testimony described the use of additional sluicing and a steam shovel to excavate a ten-to-twenty-five-foot-deep trench across the canyon, creating a subsurface foundation for the St. Francis Dam, ideally anchoring the structure to bedrock. When young Bob Phillips visited the site during construction with his father, DWP engineer J.E. Phillips, the boy remembered the bottom of the finished foundation trench as “wet, shiny … like a well-laid patio floor.”14

  To mix mass concrete for the job, the DWP plant in Monolith, about fifty miles north of the dam site, supplied Portland cement that was combined with sand and gravel excavated from the creek bed of San Francisquito Canyon. Workers operated large steel grids, called “grizzlies,” that served as sieves to separate larger stones and remove impurities such as clay. The sifted sand-and-gravel aggregate was combined with the water and cement in a batch-mixing plant built at the base of the dam. Beginning on October 1, 1924, a steel tower with a hoisting bucket lifted and poured concrete down a series of movable chutes into broad wooden forms where five-foot layers, or “lifts,” defined the rising shape of the St. Francis Dam.15 Two mixes were used. There was more gravel in the main body of the dam. The gravel was cut by one fifth to make a smoother contact surface against the abutments.16

  One hundred seventy-five thousand cubic yards of concrete were used to finish the structure, which at its highest stood about 208 feet tall. Including the wing dike, according to official plans, the dam spanned 1,288 feet with a base 156 feet wide, narrowing to sixteen feet at the crest. The final price tag was reported as $1,250,000. Rushing to stay ahead of L.A.’s burgeoning population and drought-diminished water resources, the St. Francis Dam was finished in sixteen months. It took only minutes to collapse.

  March 21, 1928, was a clear and balmy Wednesday, but showers were expected—not the kind of weather the Los Angeles Chamber of Commerce preferred to tout. The tragedy of the St. Francis Dam was something else the city wasn’t eager to advertise. At 9:30 A.M., inside the Sierra granite Los Angeles County Courthouse, only a short distance from the downtown headquarters of the Department of Water and Power, reporters and select members of the public crowded into a small hearing room in the Hall of Justice. With some effort, they found places in rows of wooden seats. The Los Angeles Times explained that “Special arrangements have been perfected … and the limited space will prove a barrier to the hundreds who expected to attend.”17

  Officially, the Coroner’s Inquest was an inquiry into the circumstances surrounding the deaths of sixty-nine people in the County of Los Angeles as a result of the collapse of the St. Francis Dam. For the record, the fate of twenty-nine-year-old Julia Rising, wife of Powerhouse 2 survivor Ray Rising, was chosen to represent them all.

  Another inquest already was under way in Ventura County, where fatalities were far greater. Coroner Oliver Reardon was concerned with identifying victims found in his jurisdiction and establishing the cause of death, not exploring the reasons for the failure or determining liability. In Los Angeles, Coroner Nance and County District Attorney Keyes promised an investigation that would produce more than death certificates—perhaps even a murder trial.

  Coroner Nance called the hearing to order at ten A.M. From his judge’s bench he looked down on a table where an array of lawyers were seated. They included District Attorney Keyes and his counterpart from Ventura County, as well as attorneys associated with Los Angeles and the DWP. Along with Nance, Los Angeles Assistant District Attorney E.J. Dennison was ready to lead the questioning. Know
n as a skilled interrogator with a booming voice, Dennison had been active in the Rose Parade grandstand-collapse case, which resulted in jail time for the contractor.

  Immediately to the Los Angeles Coroner’s left, an empty straight-backed chair was positioned on the witness stand. In the jurors’ box, only a few feet farther, nine men sat, ready to listen, occasionally ask questions, and ultimately deliver a verdict. The Inquest jury had been closely scrutinized by DWP critics looking for indications of collusion or bias. The foreman, Irving Harris, was a graduate of Caltech and a noted hydraulic engineer. Sterling Lines played golf with Coroner Nance, but his more relevant qualifications were as a mining and petroleum engineer and consultant. Blaine Noice, a local structural engineer, worked on the new Walt Disney Studios, where, in the same year as the St. Francis Dam failure, Mickey Mouse was born.

  Oliver Bowen was another successful Los Angeles structural engineer and architect. Along with Bowen and Noice, Chester Waltz would go on to found the Structural Engineers Association of California. One man on the panel had a familiar name: local construction contractor William H. Eaton Jr., the nephew of Mulholland’s erstwhile friend Fred Eaton. Harry Holabird, a real estate appraiser, had another connection with California water history. His father had been involved in rebuilding the Imperial Valley after the disastrous 1905–07 floods. Ralph Ware, a Los Angeles contractor, was active in the local chapter of the American Society of Civil Engineers. For some reason, Ware was identified in the press as “an insurance executive.” Today little is known of the last juror, “engineer” Z. Nathanial Nelson. Although none of the jurors specialized in dams or geology, their construction and engineering experience prepared them to ask tough questions and carefully weigh the evidence.18

  Bureau of Water Works and Supply employee Ray Rising took the stand. Wearing an ill-fitting suit and bow tie, he struggled to maintain his composure as he described identifying his wife Julia’s body in the makeshift Newhall morgue. He told the jury that she, along with his three daughters, were victims of the St. Francis flood. Still in mourning, Rising had refused to allow the Joint Los Angeles and Ventura County Restoration Committee to negotiate reparations for his losses. Instead, like the two other Powerhouse 2 survivors, Lillian Curtis and her young son, Danny, he signed with personal-injury attorneys Honey and Edwards.