The Fontenelle Dam Incident: Investigation, Likely Causes, and Lessons (Eventually) Learned

The author gave the presentation “The Race to Save Fontenelle Dam,” in a general session at the ASDSO 2010 Dam Safety Conference. In 1965, this 130-foot-high, mile-long embankment dam nearly failed by erosion. A 10,500 cubic yard cavity was eroded on the downstream face of the embankment dam. Heroic intervention over a 10-day period saved the dam.
The author’s additional original research has revealed much information about the subsequent investigation and the likely reasons for the incident. This paper and presentation will combine design data, historical photographs, a post-incident geologic report, and opinions of experts to explain the processes involved which led to the near-failure. An emphasis will be on visual aids to graphically portray the likely erosion mechanisms. Lessons from the incident were not adequately learned at the time and contributed to the failure of Teton Dam. 18 pp., 16 references.