St. Francis Dam Disaster

St. Francis Dam Disaster

Melissa Schlothan15 February, 2007

Environmental GeologyDr. Sarah Gray

http://web.umr.edu/~rogersda/st_francis_dam/046.jpg

Outline

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

Geography

• Located 40 miles NE of Los Angeles– In city of Santa Clarita– Developing city

• Agriculture, electricity (Edison), mostly immigrants

• Inside San Francisquito Canyon

Castaic Lake

St. Francis Dam

Geology• San Francisquito Fault line• Paleolithic landslide area• Schist (severely laminated, cross-faulting, interspersed with

talc)• Sandstone• Conglomerate

http://en.wikipedia.org/wiki/Image:Schist.jpg

http://wps.prenhall.com/esm_keller_envgeology_8/0,7260,264377-,00.html

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

– 1st change• 10ft height increase• Capacity: 32,000 acre-feet

– 2nd change (July 1925)• 10ft height increase• Capacity: 38,000 acre-feet• Wing dyke added (600ft long)

• 1926 – construction completeWilliam Mulhollandhttp://web.umr.edu/~rogersda/st_francis_dam/reassessment_of_st_francis_dam_failure.pdf

St. Francis Dam Construction

http://web.umr.edu/~rogersda/st_francis_dam/reassessment_of_st_francis_dam_failure.pdf

Completed and filledreservoir

St. Francis Damconstruction

http://www.scvhistory.com/scvhistory/scvhistory.htm

• 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 leakshttp://www.scvhistory.com/scvhistory/scvhistory.htm

• 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 failurehttp://www.scvhistory.com/scvhistory/scvhistory.htm

View of water entering Pacific Ocean

http://web.umr.edu/~rogersda/st_francis_dam/Mapping%20the%20St%20Francis%20Dam%20Outburst%20Flood%20with%20GIS.pdf

Reservoir Area


Flood path


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

Overturned railroad tracks

Debris and overturned cars


Flood path

Damaged highway


Damaged pecan fields

Broken electric poleshttp://www.scvhistory.com/scvhistory/scvhistory.htm

Waterline


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.”

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

http://news.softpedia.com/images/news2/1-Week-After-Katrina-The-American-Red-Cross-Is-Setting-A-Record-Relief-Pace-2.jpg

• 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

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

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

http://wps.prenhall.com/esm_keller_envgeology_8/0,7260,264377-,00.html

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

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

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

Lessons

• More geological knowledge of area

• Complete reinforcement for changes is always needed

Sources

• http://www.scvhistory.com/scvhistory/scvhistory.htm• http://en.wikipedia.org/wiki/San_Francisquito_Canyon• http://web.umr.edu/~rogersda/st_francis_dam/lessons_le

arned_from_the_st_francis_dam_failure(geostrata_mar-apr_2006).pdf

• http://web.umr.edu/~rogersda/st_francis_dam/reassessment_of_st_francis_dam_failure.pdf

• http://web.umr.edu/~rogersda/st_francis_dam/Mapping%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.


http://en.wikipedia.org/wiki/San_Francisquito_Canyon

http://web.umr.edu/~rogersda/st_francis_dam/lessons_learned_from_the_st_francis_dam_failure(geostrata_mar-apr_2006).pdf





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St. Francis Dam Disaster