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Unexpected Interim Results in the Independent Investigation of the 2020 Breaches of Edenville and Sanford Dams
A view of Sanford Dam, which was overtopped and breached by the failure flood from Edenville Dam, looking downstream.
T
he catastrophic breach of central Michigan’s Edenville and Sanford Dams in May 2020 forced the evacuation of thousands of area residents and resulted in serious property damage. After the incident, the Federal Energy Regulatory Commission (FERC) engaged an independent forensic team (IFT) to investigate its causes. The IFT has recently released an interim report in which, among other findings, it identifies static liquefaction as the most likely mechanism by which Edenville Dam failed. Because this has not historically been considered a common failure mode for embankment dams, this finding is significant for the dam and hydropower industries. In this interview, consultant John France, who is leading the IFT, tells us more about the investigation. Hydro Leader: Please tell us about yourself and about your professional background.
Hydro Leader: Please tell us about the failure of Edenville and Sanford Dams.
14 | HYDRO LEADER | November/December 2021
hydroleadermagazine.com
PHOTOS COURTESY OF EGLE.
John France: I have been a private consultant for about 46 years. Since about 2018, I have worked on my own as an independent consultant through JWF Consulting LLC. My career has been focused on dam engineering, safety, and risk analysis.
John France: On May 19, 2020, two dams failed near the city of Midland in central Michigan. The dams were two of four dams owned by Boyce Hydro. All four dams were built in the mid-1920s on the Tittabawassee River. From upstream to downstream, they are Secord and Smallwood Dams, both of which suffered some damage but not failure; Edenville Dam, which experienced the initial failure; and Sanford Dam, which subsequently failed. Storms brought heavy rainfall to the area on the days before the incident. At Secord, the rainfall between May 17 and May 19 was as much as about 6 inches, and at the other three dams the rainfall was in the range of 3–4 inches. It was a significant but not extreme rainfall—nowhere near approaching the probable maximum precipitation. Over the night of May 17, the reservoirs began to rise, but they were still within their normal operating range. All four dams have gated spillways, and by the morning of May 18, the dam operators began to operate the gates. There were gate operations throughout the day, concluding at Sanford at about 8:00 p.m. The water continued to rise on the night of May 18–19. On the afternoon of May 19, lake levels peaked and began to recede at Secord and Smallwood, the two most upstream dams, but the water continued to rise at Edenville until 5:35 p.m.
