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St. Francis Dam Disaster Melissa Schlothan 15 February, 2007 Environmental Geology Dr. Sarah Gray

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Presentation on theme: "St. Francis Dam Disaster Melissa Schlothan 15 February, 2007 Environmental Geology Dr. Sarah Gray"— Presentation transcript:

1 St. Francis Dam Disaster Melissa Schlothan 15 February, 2007 Environmental Geology Dr. Sarah Gray

2 Outline Geography and Geology Background Impacts Disaster Management and Response Why did the St. Francis Dam fail? What happened to the community? Recommendations Lessons

3 Geography Located 40 miles NE of Los Angeles –In city of Santa Clarita –Developing city Agriculture, electricity (Edison), mostly immigrants Inside San Francisquito Canyon

4 Castaic Lake St. Francis Dam

5 Geology San Francisquito Fault line Paleolithic landslide area Schist (severely laminated, cross-faulting, interspersed with talc) Sandstone Conglomerate


7 Background Designed by William Mulholland, Dept. of Power and Water 1924 – construction began –Originally Capacity: 30,000 acre-feet 180 ft high, 600 ft long –1 st change 10ft height increase Capacity: 32,000 acre-feet –2 nd change (July 1925) 10ft height increase Capacity: 38,000 acre-feet Wing dyke added (600ft long) 1926 – construction complete William Mulholland

8 St. Francis Dam Construction

9 Completed and filled reservoir St. Francis Dam construction

10 1926-1928 –Cracks developing in dam and abutments Mulholland investigates and dismisses –7 March 1928 Reservoir fills to capacity More leaks develop Mulholland investigates and dismisses –12 March 1928 East side of reservoir roadbed sagging 1 – 5 feet More leaks and cracks Mulholland and assistant inspect and dismiss Evidence of leaks

11 12 March 1928 – Dam fails 11:57 pm –12 bill gallons of water –18 mi/hr initially, 5 mi/hr into Pacific –Traveled 55 miles to the Pacific Ocean Took 5 ½ hrs Dam after failure

12 View of water entering Pacific Ocean

13 Reservoir Area

14 Flood path

15 Impacts Deaths: 450 estimated –Many found downstream –Tent residents of unknown count +900 homes destroyed 1,200 buildings damaged 10 bridges knocked out Power lost in multiple cities Crops, businesses and livestock affected

16 Overturned railroad tracks Debris and overturned cars

17 Flood path Damaged highway

18 Damaged pecan fields Broken electric poles

19 Waterline

20 Disaster Management Awareness and preparedness –No disaster plan No one ever thought it would break –Mulholland was aware of cracks/leaks and maximum capacity Dismissed them because said, “This is typical for a concrete dam of this size.”

21 Disaster Response Immediate response by Red Cross –Set up national fund drive –100’s of volunteers –Provided: Search and rescue Care for injured/needy Clearing debris and dying or dead people and animals –Total spent: $237,190

22 Los Angeles County –Took full responsibility for event –$1 million set aside for programs and funds –“Council of Fourteen” –Continued work on clean-up 1,000’s volunteers and 100’s tractors utilized –Completed in 90 days

23 Reconstruction Phases I and II Mulholland Dam –Reinforced with rocks and earth on face Built like St. Francis Fears of similar dam break Bouquet Reservoir – 1934 –15 miles west of Palmdale –Part of L.A. Aqueduct system Castaic Dam – 1973 –Near Castaic –Hydroelectric power plant

24 Why did the dam fail? Major reasons: –Rock Formations Conglomerate: expands with water Schist: badly laminated, interspersed with talc –Fault line –Erosion from running water at cracks along sides –Paleolithic landslide,7260,264377-,00.html

25 Why did the dam fail? Cracks –Created when conglomerate on side swelled when wet causing the dam to rise and crack Construction –Underground base missing steps Tilting –from extra capacity unaccounted for with increased height Sabotage theory –Previous unrest about taking water into aqueduct from Owens River Valley

26 How was the community affected? Many people lost jobs –Edison electric power plants ruined –Agriculture crops devastated Agriculture devastated –7,900 acres Citrus, walnuts, apricots, grapes, alfalfa, pecans Tent residents –Lost jobs and displaced Rebuild homes and businesses –Took very long for people to get back on their feet

27 Recommendations Warning system needed –You can never be too careful, the risk of failure will always be there no matter the confidence More response by police force –Efficiency needed with system of communication Reservoir shouldn’t have been built there –The geography is extremely dangerous

28 Lessons More geological knowledge of area Complete reinforcement for changes is always needed

29 Sources arned_from_the_st_francis_dam_failure(geostrata_mar- apr_2006).pdf arned_from_the_st_francis_dam_failure(geostrata_mar- apr_2006).pdf ent_of_st_francis_dam_failure.pdf ent_of_st_francis_dam_failure.pdf 20the%20St%20Francis%20Dam%20Outburst%20Flood %20with%20GIS.pdf 20the%20St%20Francis%20Dam%20Outburst%20Flood %20with%20GIS.pdf Outland, Charles F. Man – Made Disaster: the story of St. Francis Dam. Glendale, California: The Arthur H. Clark Company, 1963.

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