Teton Dam Failure and Legacy - Updated

Dams look like they are simple, but their design and construction can be complex. When they fail after 1 year, something has gone very wrong. Teton Dam (Idaho, 1976)

Construction on the Teton Dam, reservoir, and powerhouse began in 1972 and by November 1975 the zoned earthfill embankment was essentially complete with a structural height of 305 feet and a crest length of 3,100 feet. Less than one year later, the dam experienced catastrophic failure on June 5, 1976 during its first filling. Failure of the Teton Dam and subsequent draining of the reservoir caused the deaths of 11 people and approximately $400 million in damages.

Seepage started on 3 June 1976 in the range of 1/4 cubic feet per second, and by the 5th a sinkhole had appeared and scouring had begun. Water-flow was 20 to 30 cubic feet per second of muddy water by that time. The dam failed at 11:55 am releasing 75 to 80 billion gallons of water, or 230,000 acre-feet, at a rate of more than 1 million cubic feet per second. This second link is from the Bureau of Reclamation.

There were several contributing factors. The foundation of the dam wasn't well understood by the designers. The treatment of the foundation was inconsistent. The project was behind schedule, after all.

Investigations of the Teton Dam failure attributed the catastrophe to a series of design and construction related deficiencies. These inadequacies related primarily to the foundation treatment at the dam and adherence to the overall construction schedule. It was determined the most probable physical failure mode was cracking of the dam’s impervious core due to internal erosion initiated by hydraulic fracturing of the key trench fill material.

Teton Dam was located in an area with highly permeable foundation materials. During investigation of the failure, it was discovered that proper treatment of such foundation material was not implemented. It appeared that the dam’s designers did not take the site specific geological conditions into account when developing the structure. This oversight was exacerbated by the lack of communication between the design and construction engineers about the proper preparation of the dam foundation.

As I have read about a couple of times when a new dam fails, people don't believe it. "You must be joking." And they refuse to believe it. You can hear one example of that if you watch the video below. In the end, most people did heed the warnings, and evacuate.

The first link at the top has several tabs, one is photos and another is a collection of video. The photo above is from that site, and originally (I believe) from the U.S. Department of the Interior's Bureau of Reclamation from the day of the dam failure.

This video is a Compilation of footage and audio associated with the failure of Teton Dam. It includes mostly warnings that went out over local radio stations, as well as some interviews from after the fact. It is only 3 or 4 minutes, and does include some video of the dam breach.

[Update: Commenter Steve recommends the following video (and I wholeheartedly agree): A brief History of: The Teton Disaster (Documentary). The video is 20 minutes, so plan accordingly. It is a wonderful examination of "Completion Bias." That bias in large projects (especially .gov projects?) that once you've sunk money into a project, it must complete.]

So why is this coming to my attention now? The Teton Dam wasn't the first dam on the upper Snake River. The Teton Dam replaced the Linderman Dam, which was built on almost the same spot. Linderman Dam restoration project will begin Aug. 18. But in typical bureaucratic mode, even though the remnants of the Lindeman Dam were a hazard, nothing was done between 1976 and today. That is 45 years of ignoring a problem.

Linderman Dam was largely dismantled in 1972 for the construction of Teton Dam. After the 1976 failure of Teton Dam, the river resumed its previous course, and the footings of Linderman Dam were exposed. The structural remains are located on the Teton River approximately seven miles upstream from the Teton Dam site, just downstream from the Milk Creek confluence. Successful project completion will eliminate the safety hazards; improve passage for aquatic species, including native Yellowstone cutthroat trout; rehabilitate the river to a more natural and passable elevation profile; and maintain upstream pool elevation for irrigation demands.

At least it is being addressed.

There are more videos at the first link at the top. Some of them are interesting. One is from the Bureau of Reclamation, and while it does contain a small section of good information, it is mostly a .gov propaganda piece. "We are a world-class organization who people ask for help with dams." Sure you are. If you didn't learn "valuable lessons" from a $400 million failure of an engineering project, that failed almost as soon as it was completed, and cost 11 lives, your organization should have been disbanded, and the executives shot.

Though they are right about 1 thing. This was one of the dam disasters that lead to a whole bunch of safety changes to the way dams are designed and built. It didn't fix everything, of course, but it did do some things to break up the bureaucracies.

One of the interesting things from that propaganda video is a description of the insane management rules regarding engineers from design actually talking to engineers from construction management. They had to get management approval communicate in any way. They had to get management approval to make a long-distance call to or from the construction site.