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Examples of recent dam failures and their implications
Aznalcollar mine:
just a few miles from the Los Frailes mine
courtesy of
Jonny Soljberg (#) |
April 25, 1998: the tailings dam at the
Los Frailes mine near Seville, Spain failed due to an earthslide in the
bedrock below the dam. The slide was caused by excess pressure from the
weight of the dam and the tailings. This shift in the earth caused the dam to
shift and cracks to form in the dam. A crack at the southeast end of the dam
discharged 1.3 million m3 of solid waste and 5.5 million
m3 of water. This has had BIG societal implications -- the toxic
waste has killed many fish and birds and flooded thousands of hectacres of
farmland. Who is to blame????
Is it Apirsa, the Spanish company which
operates the mine?
Is it the Canadian firm, Boliden Ltd. (#), who owns Apirsa?
Is it
the contractor, Dragados y Construcciones?
Is it the engineering firms,
Itecsa and Geocisa, who designed the dam?
Neither the original project
survey in 1977 or a 1996 Geocisa stability report of the geology beneath the
dam indicated possible problems.
Who is responsible for the damage? |
Eptisa Servicios de Ingeneria, S.A. directed the investigation of
the cause of the dam's failure. Investigations are still underway, but Apirsa
has gotten the go-ahead to reopen the Los Frailes mine for business. Estimated
losses are up to $42.5 million. Once the mine is back to full production, it
should produce up to 125,000 tonnes of zinc and 2.9 million ounces of silver
each year.
sources: Reuters Full text of Boliden press
release from Canada News Wire, 4/21/99
"Report on the Los Frailes Dam
Failure," Engineering & Mining Journal
This story has made the news a couple times recently. Check out the Dam
News for coverage: february 26th,
march2nd, and april 22nd.
Also, this page discusses many of the questions:
WISE Uranium Project (#)
They also list other
tailings dam failures (#)
February 26, 1999 marks the 27th anniversary of the failure of another
tailings dam on Buffalo Creek, West Virginia. 125 peoople were killed and
4000 were left without homes. The dam failure was compounded by the fact
that it was waste that was escaping; the waste caught fire and an explosion
eventually occured. source: Thomas, Henry. The
Engineering of Large Dams
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June 5, 1976: the failure in the Teton Dam led to flooding in the
cities of Sugar City and Reburg in Idaho. The dam failure killed 14 people and
caused over $1 billion in property damages. Water was seen flowing down the
downstream face of the dam, an earthfill embankment dam 300 ft. high, early
on the day of the failure. Just a few hours later a crack in the dam had
grown to a large hole, which soon led to the breach of the dam. Erosion of
the underlying soil, settlement of the soil, and seepage were found to be the
main causes of the failure. For more information regarding this disaster,
visit The Teton Flood Museum (#)
source: "Four major dam failures
re-examined," Water Power & Dam Construction
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 | See some of the devastation of the Teton Dam failure as its wrath is
described.
 clip courtesy of KIDK TV (#),
Idaho |
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July 17, 1995: a spillway gate of Folsom Dam failed, increasing flows
into the American River significantly. There are some
great photos of the failure on a UVA website (#).
The spillway was repaired and the USBR carried out an
investigation (#) of the water flow patterns around the spillway using
numerical modelling. No flooding occured as a result of the partial failure,
but flooding is still a major concern for this area. It seems that the Folsom
Dam may be due for a height increase as an answer to this concern -- check it
out in the Dam News! |
source: US Bureau of
Reclamation (#) |
In recent years, dam failure numbers have decreased dramatically with the
increased consciousness about dam safety. In 1983, the Association of State Dam
Safety Officials (#) was formed to to improve dam safety across the
country and educate the public on it. Other organizations of this nature
include:
United States Committee on Large
Dams (#)
International Commission on Large Dams (#)
World Commission on Dams (#)
European Club of ICOLD National
Committees (#)
Dam-Reservoir Impact & Info.
Archive (#)
Canadian Dam Association (#)
Federal Energy Regulatory
Commission Office of Hydropower Licensing (#)
Reported dam failures in 1997 was
below 10. To see some more numbers on dam failures and incidents, check out
the National Performance of Dams
Program (#).
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You have reached the end of the Scenarios section!
Crack your own dam and analyze it in the Simulation section
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