On May 19, 2020, the Edenville dam on the Tittabawassee and Tobacco Rivers in central Michigan was breached during historic flooding. The downstream FERC-licensed Sanford Dam (Project No. 2785) was later overtopped by the increased flows from the Edenville breach. Evacuation orders were issued for around 10,000 residents in the area and floodwaters from the dam failures encroached on downtown Midland, Michigan, and a nearby Dow Chemical complex.
Prior to its failure, the Edenville dam had a long history of noncompliance with the dam safety requirements of its Federal Energy Regulatory Commission (Commission or FERC) license. Over 15 years ago, FERC began notifying the then-licensee of concerns at the Edenville project, including the project’s inadequate spillway capacity and its inability to pass the Probable Maximum Flood (PMF)—the flood that could be expected from the most severe combination of meteorological and hydrologic conditions reasonably possible in the area. After the licensee failed to respond to FERC’s dam safety directives for years, FERC in 2017 issued a formal compliance order finding the licensee in violation of its license and Commission regulations. FERC’s primary concern was that the licensee had failed to increase the spillway capacity. The Commission’s compliance order noted that the Edenville dam had a high hazard potential rating, meaning that a failure of the project’s works would create a threat to human life or cause significant property damage.
By issuing the 2017 compliance order, FERC met statutory requirements under section 31 of the Federal Power Act (FPA) to impose penalties on the licensee if it failed to comply with license obligations. And several months later, the Commission did just that, ordering the licensee to cease generation of power at the Edenville project based on its continued failure to comply with the terms of the compliance order.
Several months later, after the licensee continued its failure to bring the Edenville dam into compliance with FERC dam safety requirements, the Commission in 2018 invoked its rarely used authority under FPA Section 31 to revoke the license for the project. In its order, FERC referred to its repeated attempts over 14 years to get the licensee to correct noncompliance with Commission requirements and noted that at the time of license revocation, the spillway capacity at the project could only pass 50% of the PMF. Following revocation of the license, jurisdiction over the license passed to the Michigan Department of Environment, Great Lakes, and Energy (EGLE) for dam safety regulatory purposes.
On May 20, 2020, one day after the Edenville and Sanford dam failures, FERC issued a directive to the licensee for the three dams for which is still holds a FERC license: the Sanford Dam, the Secord Dam (Project No. 10809) and the Smallwood Dam (Project No. 10810), the latter two of which are upstream of the failed Edenville dam. “Due to the extensive damage to the projects and the region as a result of the floodwaters and the Edenville breach,” FERC directed the licensee to fully lower the reservoirs behind all three dams, perform a dam safety inspection of the dams within three days after the flows recede, and immediately provide a verbal summary of the findings to FERC. In addition, FERC ordered the licensee to begin formation of a fully independent forensic investigation team to focus on the three dams. FERC noted that it would coordinate investigation of the Edenville breach with Michigan EGLE.
In response, the licensee made a filing in the FERC record, but this communication was filed as Critical Energy Infrastructure Information, and is therefore not available for public review. FERC issued a follow-up letter to the licensee on May 26, 2020 noting that the Sanford Dam was fully breached due to the high flows from the Edenville breach. In the letter, the Director of FERC’s Dam Safety and Inspections Division refuted the licensee’s claim that the Smallwood Dam sustained no consequential damage, explaining that its own site assessment revealed that the dam sustained erosion damage in multiple locations. FERC granted the licensee’s request for a two-day extension of time to submit a proposal for the forensic team, but indicated no further extensions would be granted. FERC issued an additional letter to the licensee on May 28 recounting the damage to the Sanford and Smallwood dams and additionally noting some erosion on the downstream slopes of the Secord dam. The May 28th directive ordered the licensee to file an incident report under section 12 of the Commission’s dam safety regulations for all three licensed dams by June 16, 2020.