The failures of the Edenville and Sanford dams in May 2020 could have been avoided according to a final report released by a five member panel of dam safety experts appointed by the Federal Energy Regulatory Commission.
The Independent Forensic Team (IFT) 502 page report released Wednesday, May 5 said design and construction flaws in the Edenville Dam when it was built in the 1920s were part of the problem. The original construction used loose sand for the embankment interior. This resulted in liquefaction, when soil becomes saturated with water and loses strength and stiffness, acting like a liquid. 18 hours of rain prior to May 19, 2020 saturated the soil embankment of the Edenville Dam and liquefied the soil. The rain also raised Wixom Lake’s water level three feet higher than previously recorded levels.
However, human error also plays a factor in the dam’s failure. Boyce Hydro, the dams’ former owner, often didn’t have enough money to effect repairs or pay regulation fines since the dam didn’t generate enough electricity. The report says inspectors often overlooked issues which could have prevented their failures.
When the Edenville Dam collapsed, it released a torrent that overtopped the downstream Sanford Dam causing widespread flooding. Nearly 11,000 people were evacuated and 150 homes were destroyed, with damages of more than $200 million.
Several lawsuits are currently underway following the resulting flood. There are suits against the former owner, Boyce Hydro and the state of Michigan. How the final report will factor in those lawsuits remains to be seen.