Imminent Failure Condition: The Fontenelle Dam Incident






Fontenelle Dam incident was, arguably, the largest dam incident in US history that did not result in failure. A large leak developed in Bureau of Reclamation’s new dam and quickly eroded a very large cavity on the downstream slope. It was only through large-scale and prompt intervention that the dam was saved. In the decades following the incident, few people – even at Reclamation – knew that it had occurred. Starting in 2010, the author located an extensive dam incident technical report, a first-person incident narrative, two moving picture color films, hundreds of photos, a post-incident geology report, design/construction data, original correspondence, and dozens of news articles.  In 2011, he interviewed the 91-year-old man who led the response from the scene 46 years previously. From this extensive research we now have not only a compelling day-by-day visual account of the incident, but an in-depth understanding of the complex, and well-advanced failure mechanisms that nearly breached the dam.  Webinar attendees will learn about incident response techniques, incident monitoring, marshaling of equipment/materials, dealing with the press, dam/abutment interface, need for proper foundation treatment, seepage erosion, sinkhole development, seepage control, and investigative techniques.  But most importantly, attendees will learn not to be complacent with past success and to be diligent in the important work of designing and repairing dams.


Key Takeaways:

  1. Peer review and defensive designs are critically important
  2. The behavior of seepage at the interface of embankment dams and their foundation is difficult to model but is a potential major weakness
  3. Past success can create confidence bias
  4. Incident intervention is challenging but can be successful
  5. To properly learn from dam and levee incidents, we must not only understand the physical failure mechanisms, but also the human and organizational factors that designed, built, and operated the dam.

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