Saint Francis Dam Disaster: Los Angeles
A dam is a massive barrier built across rivers and streams to confine and utilize the flow of water. Dams are often used as a source for hydroelectricity generation and also for irrigation where it stop a river’s natural course so that water could be sent to different places. Dams are also utilized for flood control often used as detention dams which are either to stop or slow the amount of water in the river.
There are various types of dams that are used and constructed worldwide as shown in the figure below. And, Saint Francis Dam is an example of a gravity dam. The qualities of the catastrophic events are constantly changing due to the development of normal and social conditions. In structural building, a mistake is not an alternative because even a small problem can cause casualties to other individuals. In connection to civil engineering, engineers from different specializations play a major in the construction of dams. A structural architect is the one who is responsible when the infrastructure that he/she has constructed or built was destroyed.
Civil Engineering has 3 roles:
The first is to construct or build a strong framework that has high cataclysmic event protection to lessen or even the loss of lives and to the livelihood of the society. Second, they improve the frameworks of the building, advancement of new innovations, and elite structure. Lastly, civil engineers are involved in the rescue operation, and reconstruction and restoration work after a disaster happen. Civil engineers need to keep themselves updated about the latest research and developments in construction technology, advances in construction materials, and analysis or design procedures. A convenient way of achieving this goal is by attending seminars, workshops, training programs, and conferences. Civil engineers should also take support from other branches of engineering for the better planning, execution, and functioning of their building and infrastructure projects.
St. Francis Dam was a curved concrete gravity dam, the dam was built to create a large regulating and storage reservoir for the city of Los Angeles, California. The repository was a fundamental piece of the city's Los Angeles Aqueduct water supply framework. It was in San Francisquito Canyon of the Sierra Pelona Mountains, around 40 miles (64 km) northwest of downtown Los Angeles, and roughly 10 miles (16 km) north of the present-day city of Santa Clarita. The dam was planned and worked with some support in the range of 1924 and 1926 by the Los Angeles Department of Water and Power, at that point was named the Bureau of Water Works and Supply. The division was under the course of its head supervisor and boss specialist, William Mulholland.
In the early long stretches of Los Angeles, the city's water supply was acquired from the Los Angeles River. This was accomplished by occupying water from the waterway through a nexus of a trench called 'Zanjas'. Around then a private water organization, the Los Angeles City Water Company, rented the city's waterworks and gave water to the city. Obtained in 1878 as a Sanjuro (discard delicate), William Mulholland demonstrated to be a very impressive worker who in the excitement of doing his days’ worth of effort would think about books on arithmetic, and power through pressure, and topography and instructed himself in building and geography.
Mulholland immediately moved up the positions of the Water Company and was promoted to Superintendent in 1886. In 1902, the City of Los Angeles finished its rent with the private water organization and assumed responsibility for the city's water supply. The city gathering set up the Water Department with Mulholland as it’s Superintendent and when the city sanction was changed in 1911, the Water Department was renamed the Bureau of Water Works and Supply. Mulholland became the Superintendent and was named as its Chief Engineer. Mulholland accomplished extraordinary acknowledgment among individuals from the building network when he managed the structure and development of the Los Angeles Aqueduct, which at the time was the longest reservoir conduit on the planet and utilizations gravity alone to bring the water 233 miles (375 km) from the Owens Valley to Los Angeles.
The task was finished in 1913, on schedule and under spending plan, regardless of a few difficulties. Barring the occurrences of treachery by Owens Valley inhabitants in the early years, the water system has kept on functioning very well since the day it was utilized and stays in activity today. It was during the way toward building the Los Angeles Aqueduct that Mulholland initially considered areas of San Francisquito Canyon as a potential dam site. He believed that there ought to be a store of enough size to give water to Los Angeles for an all-inclusive period in case of a dry season or if the reservoir pipe were harmed by seismic tremor. He supported the zone between where the hydroelectric power plants Powerhouses No. 1 and No. 2 were to be worked, with what he saw as ideal geography, a characteristic narrowing of the gulch downstream of a wide, upstream stage which would permit the making of a great repository zone with a base conceivable dam.
A huge camp had been set up to the house, the laborers close to this region, and Mulholland utilized his extra time to get comfortable with the region's geographical highlights. In the territory where the dam would later be placed, he found the mid and upper portion of the western slope comprised basically of a rosy shaded combination and sandstone development that had little composition of gypsum mixed inside it. Below the red aggregate, down the rest of the segment of the western slope, crossing the gulch floor and up the eastern divider, a radically extraordinary composition won. These territories were comprised of mica schist that was seriously overlaid, cross-blamed in numerous regions and scattered with powder. Albeit later numerous geologists differ in the careful area of the zone of contact between the two developments, a lion's share supposition put it at the latent San Francisquito Fault line.
Mulholland requested exploratory passages and shafts unearthed into the red combination slope to decide its qualities. He additionally had water permeation tests performed. The outcomes brought him to believe that the slope would make a good placement or site for a dam should the need ever arise. A surprising part of the early geologic investigation came later when the requirement for a dam emerged. Even though Mulholland was composed of the hazardous idea of the substance of schist on the eastern side of the gulch in his yearly report to the Board of Public Works in 1911, it was either misinterpreted or overlooked by the development boss of the St. Francis Dam, Stanley Dunham. Dunham affirmed, at the Coroner's Inquest, that tests which he had requested produced results that demonstrated the stone to be hard and of a similar sort all through the whole region which would turn into the eastern projection. His supposition was that this zone was more than appropriate for the development of the dam.
The population in Los Angeles was expanding quickly. In 1900 the populace was at more than 100,000. By 1910, it had turned out to be multiple occasions that number at 320,000, and by 1920 the figure arrived at 576,673. This commencement of fast development brought interest for enough sources of water supply. Between the range of 1920 and 1926, seven littler repositories were structured, and adjustments were made to raise the stature of its biggest of the time, the Lower San Fernando, by seven feet, however, the requirement for a still bigger store was clear. Initially, the arranged site of this new enormous supply was to be in Big Tujunga Canyon, over the city currently known as Sunland, in the upper east bit of the San Fernando Valley, yet the high worth put on the farms and private land which would be required were, in Mulholland's view, an endeavored hold-up of the city. He stopped the endeavors at acquiring those terrains and, either careless of or dismissing his prior affirmation of geographical issues at the site, restored his enthusiasm for the region he had investigated twelve years sooner, the governmentally claimed and far more affordable private land in San Francisquito Canyon.
The sort and measurements of the dam were adequately adequate whenever dependent on the reasonable establishment. The solid of which the dam was fabricated was of abundant solidarity to oppose the worries to which it would ordinarily be oppressed. The distress can't be laid to the development of the world's hull. The dam bombed because of faulty establishments. This discontent reflects not the slightest bit the strength of a well-structured gravity dam appropriately established on reasonable bedrock. The agreement of most of the exploring commissions was that the underlying break had occurred at or close to the separation point, which had been an issue zone since water originally secured the zone, on the western projection. The predominant idea was that expanding water permeation through the separation point had either undermined or debilitated the establishment to a point that a part of the structure was smothered, or the dam fell from its very own gigantic weight. As their hypotheses, water from the store had saturated far over into the schist arrangement of the eastern projection. This greased up the stone and it gradually started to move, applying an enormous measure of weight against the dam, which as per the Grunskys was at that point winding up less steady because of 'elevate'. Bitter things, Dr. Willis built up, was that the aggregate, on which the western placement of the dam rested, responded after getting to be wet by growing. The measure of expanding was to such an extent that it would raise any structure based upon it. This theory was toughened when studies have taken of the wing divider after the disappointment were contrasted and those taken at the time it was assembled. They uncover that in certain territories the divider was 2 to 6 inches higher than when built. Therefore, the dam was gotten between powers that were following up on it much like a tight clamp, as the red aggregate expands on one side, and the moving mountain squeezed in on it from the other.
When the dam was relaxed on its base the toe of the structure spilled off. This was likely the start of its separation, and most likely happened at some point after 11:30 PM during the 23 minutes where the water in the store obviously fell 3/10 of afoot. Immediately, very likely, a piece of the east finish of the dam, in the meantime undermined, went out and the dam at this end lost its slope support. Hydrostatic elevate at the effectively free west and the heaviness of the rest of the bit of the undermined east end caused a transitory tilting of the dam towards the east, joined by a fast washing continuously of the slope under the dam at its west end which at that point likewise started to separate. The store water was presently hurrying with colossal power against the two closures and against the upstream substance of every one of that was remaining of the dam. This surge of water diverted huge squares of cement from the two parts of the deal.
In spite of the fact that this examination was useful, the hypothesis, close to others which figured out an obviously expanding measure of leakage only preceding the disappointment, turns out to be more uncertain when it is thought about against the observer records of the conditions in the gulch and close to the dam during the most recent thirty minutes before its breakdown. Grunsky guessed, however, neglected to clarify, the activity of the dam tilting as he depicted. This activity would have the dam moving as a solitary unit while on the other hand, the declaration given at the Coroner's Inquest demonstrates that the dam was broken transversely in at any rate four spots. Moreover, the two breaks, which flanked each side of the standing focus segment, would have filled in as pivots to counteract this.
The disappointment of the dam is presently accepted to have started with the eastern projection of the dam giving way, conceivably because of an avalanche. This situation, having its underlying foundations in the progress of Willis and Grunsky, was developed by the writer Charles Outland in his book Man-Made Disaster: The Story of St. Francis Dam which was first distributed in 1963. The material on which the eastern projection of the dam had been fabricated may itself has been a piece of an antiquated avalanche, however, this would have been unimaginable for practically any geologists of the 1920s to recognize. To be sure, the site had been reviewed twice, on various occasions, by two of the main geologists and structural architects of the day, John C. Branner of Stanford University and Carl E. Grunsky; neither one of the founds deficiency with the San Francisquito shake. J. David Rogers, propelled by crafted by Outland, explored the disappointment and distributed a broad situation, though to some degree dubious, of the conceivable land and shake repairman activities which may have prompted the dam's disappointment. He credited the inability to three main considerations: the unsteadiness of the old avalanche material on which the dam was fabricated, the inability to make up for the extra stature added to the dam's plan, and the structure and development being administered by just a single individual.
In conclusion, Engineers, Civil Engineers specifically should have patience in assessing of examining the placement of construction. It is also essential for Civil Engineers, no matter what their specializations are should have connections and understanding in planning and during the construction proper. It is also important to create a detailed plan not just for the present conditions but also for future purposes and safety. Proper maintenance should also be observed when the project is fully done. The detailed inspection could also save a million of money, save hundreds of lives, and many more for it reviews the infrastructure in detail.
References
- https://amp.interestingengineering.com/23-engineering-disasters-of-all-time
- https://www.britannica.com/event/St-Francis-Dam-disaster
- SAINT FRANCIS DAM PRIOR TO ITS COLLAPSE
