Dam Failure Case Study: Edenville Dam (Michigan, 2020)

Edenville Dam experienced a static liquefaction instability failure of its downstream slope on May 19, 2020. The resulting breach flow reached and overtopped the downstream Sanford Dam about 2-3 hours later, resulting in the failure of that dam as well. Fortunately, there was no loss of life because a cautious decision had been made to evacuate about 10,000 people about 18 hours before it was clear that either dam was going to fail, resulting in an estimated 10 to 20 lives saved.

The primary reason why Edenville Dam was vulnerable to static liquefaction failure was that it was not built in accordance with the construction plans and specifications, resulting in the downstream slope being too steep in the location of the failure and the embankment soils being loose due to receiving little or no compaction during construction. These geotechnical vulnerabilities and their implications were not recognized during decades of inspections and evaluations of the dam.

The geotechnical vulnerabilities actualized as instability failure when the impounded lake rose to a record high level as a result of operational decisions and of portions of the watershed having become frozen due to overnight freezing temperatures just prior to heavy rain, with the frozen ground resulting in disproportionately high runoff. This watershed behavior was unforeseen, but was not unprecedented.