Cracking dams intro

Advanced level intro
Case Histories
Site Map

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

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

See some of the devastation of the Teton Dam failure as its wrath is described.

clip courtesy of KIDK TV (#), Idaho

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 (#).

You have reached the end of the Scenarios section!

Crack your own dam and analyze it in the Simulation section ...

Lives lost due to dam failure Intro to simulation