May 25, 2020 SANDRP
On Tuesday, May 19, 2020 evening following two days of heavy (4-7 inches) rains, Edinville Dam breached at 1740 and downstream Sanford dam overflowed at 1900 hours, leading to highest ever water level in downstream towns, leading to evacuation of over 10 000 people, besides massive damage, including to roads, bridges, buildings and crops. Both were earthen dams, Edinville dam famously did not have sufficient spillway capacity to pass even half the PMF (Probable Maximum Flood) it was expected to get. USA has much better dam safety situations legally, institutionally and practically that we in India have, and yet this happened where problems were known. As India awaits in the South West Monsoon 2020, there is a lot we need to learn here and worry about our dams. The Disaster The Tittabawassee River on which Edinville and Sanford were situated had flows of one in 500-year flood downstream from Sanford dam, flooding Edinville, Sanford and Midland downtown in Michigan when the state was fighting one in 100-year pandemic Covid 19, as Michigan’s Governor Gretchen Whitmer said over television on that fateful night. The Tittabawassee River in Midland surpassed the previous record of 33.89 feet (the river flood level is 24 feet) on Wednesday, which was set during a major flood in the city in 1986. The river water level crested at 35.05 feet around 12:30 p.m. on Wednesday, though earlier it was forecast to reach 38 ft. The new water level was still the highest ever surpassing previous high by 1.16 ft.
At 5:30 a.m., the Tittabawassee River, a tributary of the Saginaw River (which flows into Lake Huron, one of the Great Lakes on border between Canada and USA) had broken the record of 33.9 feet set during a flood event in 1986. At 12:45 p.m. Wednesday, the river level was 35.013 feet and rising. Nasa has provided satellite images of the disaster.
“In the 1986 flood, it was considered a 100-year flood,” Midland city manager Brad Kaye said. “Current flood is predicted to be the equivalent of a 500-year flood.”
Gov. Whitmer declared a state of emergency for one county. Both the Edenville and Sanford Dams breached (though later it was revealed that the dam did overflow, but did not breach) May 19, 2020 night, the governor said in a news release, and urged residents to evacuate the affected areas in Midland County immediately. Downtown Midland was expected to be under 9 feet of water next day. Whitmer said in a news conference. “We are anticipating an historic high water level.” Mark Bone, Chairman of the Midland County Board of Commissioners, said about 3,500 homes and 10,000 people have so far been affected by the evacuation notices. No deaths or injuries have so far been reported, he said. Live video of the Edinville dam breach is available.
Edenville Dam, spanning the confluence of the Tittabawassee and Tobacco Rivers is about 225 km north of Detroit, and the Sanford Dam, about 11.26 km downriver. Midland city with a population of 42000 is 12.9 km downstream of Sanford dam. Dow Chemical Co.’s main plant sits on the city’s riverbank. Emergency responders went door-to-door early Tuesday morning warning residents living near the Edenville Dam of the rising water. Some residents were able to return home, only to be told to leave again following the dam’s breach several hours later. The evacuations included the towns of Edenville, Sanford and parts of Midland.
Earlier on Monday, the National Weather Service had warned of flash flood warning for south-central Gladwin County along the Tittabawassee River below Secord Dam, just upstream of the Midland county. Just after 3 pm Monday, Gladwin County dispatch reported high flows being passed through Secord and Smallwood Dams on the Tittabawassee River in Gladwin County.
Two lawsuits seeking class-action status over the dam failure were filed Friday, with one suit focusing on the dam’s owners and managers, and another encompassing the dam owners, its manager and the state of Michigan. Both lawsuits seeking upwards of $5 million in damages were filed in the federal district court in Detroit.
It is not clear what advance action was taken at Edinville dam following these warnings and rainfall starting Sunday. Considering that the dam was known to be vulnerable, one expected that action would have been taken to lower the risk at the Edinville dam. [For salient features of Edinville and Sanford Dams, see Annexure 1 below.]
“This incredible damage requires that we hold people responsible, and we are pursuing every line of legal recourse that we can,” Whitmer added. On May 20, FERC ordered the Boyce company, which also owns the Sanford Dam, to open an independent forensic investigation into the operation of the two failed dams.
How the Edinville Dam breach happened Lynn Coleman, who has a property close to the Edinville dam has shot a remarkable video that shows the dam breach process. “There was a low spot in the dike and it was obvious that was going to be the point of the breach,” Coleman said on Saturday. “We stood there maybe five to 10 minutes, and it starting spitting water from the middle. Next thing you know, the mudslide happened.”
Dave Petley, landslide expert at the University of Sheffield (UK) has shared three blogs on the Edinville dam breach so far Petley interprets the Edinville Dam Breach video: “I think the video shows that the crest of the dam has deformed and dipped, creating a depression through which water has started to flow. In other words, the video starts with the dam wall undergoing the early stages of failure, which in turn has allowed a small amount of overtopping. The Edenville Dam failure then develops apace. The slope fails rapidly, initially forming a large toe bulge and there is major deformation at the crest… the dam appears to have undergone a slope failure; a failure of its integrity. This should never occur, and to me it suggests that the problems at the Edenville Dam went further than known issues with the spillway.”
Petley rejects the possibility of engineered failure: “this was not an engineered failure – in other words, it was not planned. There was some discussion on Twitter and in the comments that this was the failure of a fuse plug – i.e. a designed failure point that would release water to prevent overtopping. I can find no evidence that Edenville Dam had a fuse plug, and I do not think that a fuse plug failure would behave in the way shown in the video… I would be surprised if a fuse plug is intended to leave this type of catastrophic breach… I favour the interpretation that high pore water pressures, and a loss of unsaturated conditions, through the dam volume drove the failure. There are some indications in the video that high pore water conditions were present in the lower part of the structure.”
Petley also refers to Climate change-induced increased in PMF at such dams: “These structures, worldwide, are going to need a substantial upgrade to cope with that increase in rainfall, and that’s going to be very expensive. In the interim, we will see more failures of this type.”
Michigan state officials have said years of disinvestment in infrastructure combined with heavy rains and high winds were factors in the 96-year-old dam’s failure. The dam owners have acknowledged years of regulatory concerns about the Edenville infrastructure that predated May 19’s heavy rains and wave action that saturated an earthen dyke at the east end of Edenville and washed out about 900 feet of the dam.
Dow Chemical Company The Dow Chemical Company, headquartered in Midland, Michigan, released an updated statement on Wednesday, saying that while there were confirmed flood waters that mixed with an on-site pond used for storm water, brine system and groundwater remediation – the material from the pond commingling with flood waters “does not create any threat to residents or environmental damage.” The critics, however, are skeptical of Dow’s claims considering the company’s track record.
The concern downriver, according to Allen Burton, a professor of earth and environmental sciences at the University of Michigan, is that contaminated sediments on the river floor could be stirred up by the floodwaters, spreading pollution downstream and over the riverbanks.
There is also a tiny nuclear research reactor on the Dow site. Overnight, Dow filed an “unusual event” report with the federal Nuclear Regulatory Commission warning of potential flooding at the site. But the reactor had already been shut down because of the coronavirus crisis, and there were no indications of flood damage on May 20.
Michigan Dams The two dams involved in the floods in Michigan on Tuesday are among at least 170 dams in the state that are classified as having a “high” hazard potential by the U.S. Army Corps of Engineers, meaning that a failure could result in the loss of life. An additional 151 dams are rated with a hazard potential of “significant” based on their potential for economic and environmental damage. That means that nearly a third of Michigan’s 1,059 dams have the highest hazardous ratings. Map of Michigan dams in NYT. The state’s dam safety unit has three full-time employees who manage more than 1,000 dams.
American Rivers wrote: Dam removal can be the best way to address a dam that poses a safety risk. There are tens of thousands of dams across the country that no longer serve the purpose they were built to provide and whose removal could eliminate the cost and liability associated with owning a dam. Unless they are well maintained, their condition only gets worse every year. The most cost-effective and permanent way to deal with obsolete, unsafe dams is to remove them.
Boyce Hydro The company that owned all four lakes and related infrastructure in the area is Boyce Hydro. According to federal documents, Boyce Hydro insisted there was little chance that a catastrophic flood could happen. “Boyce Hydro states that the probability of such a flood occurring in the next 5 to 10 years ranges from 5 to 10 in one million,” one report said. Late Wednesday, Boyce Hydro issued a statement expressing distress over what had transpired. It said the company’s operators had made efforts to lower water levels and prepare for the incoming rain, but that a combination of rainfall and high winds reached extraordinary levels.
FERC revoked Edinville license in Sept 2018 The Edinville dam, however, has a complicated history since 1999 when USA’s national regulator, Federal Electricity Regulatory Commission (FERC) asked Edinville owner to increase the Edinville Dam’s spillway capacity equal to the Probable Maximum Flood (PMF) or the likely worst flood that the dam is could experience. That almost two-decade-long saga saw FERC accuse Boyce Hydro indulging in several violations, slow-walking and stone walling every effort of FERC. Its shocking as to why did FERC waited for so many years before finally revoking the generation license of the Edinville dam owner company. Had FERC taken more stringent stand against the company, may be this disaster could have been avoided. [For detailed dateline for developments related to legal process around Edinville Dam, plz see Annexure 2 below.]
FERC order of Sept 10, 2018 concludes (Para 58): “In sum, Boyce Hydro has, for more than a decade, knowingly and willfully refused to comply with major aspects of its license and the Commission’s regulatory regime, with the result that public safety has been put at risk… The record demonstrates that there is no reason to believe that Boyce Hydro will come into compliance; rather, the licensee has displayed a history of obfuscation and outright disregard of its obligations… Within 15 days of the date of this order, the Boyce Hydro must permanently disable all generating equipment in the project’s powerhouse and file written notification with the Secretary of the Commission, providing the date and time that generation ceased, the generator meter reading at that time and a photograph of the reading on the meter. Following the revocation of the license, the Commission’s jurisdiction will end, and authority over the site will pass to Michigan DEQ (Department of Environment Quality) for dam safety regulatory purposes.”
The Edenville Dam was rated in the unsatisfactory condition in 2018 by the state. The Sanford Dam received a fair condition rating. Both dams are in the process of being sold as per process described in Four Lakes Task Force Report of 2019. The designs for remediation of the hazard at Edinville Dam were being prepared, with construction anticipated in the period 2021 to 2023.
The existence of over a thousand lake front properties complicated the matter. These properties would lose huge value if the lake behind the Edinville dam were to be lowered down following FERC revoking the license. In January 2020 came the news that the Four Lakes Task Force signed a $9.4 million purchase agreement for the acquisition of Wixom, Sanford, Secord and Smallwood lakes and their dams from Boyce Trusts.
Lessons for India Like in case of other recent dam disasters of US that SANDRP has been writing about, there is a lot that India needs to learn from the Michigan Dam Disaster of May 2020.
• The first point to note is that both Edinville and Sanford are earthen dams, like thousands of India’s dams. Such dams are clearly more vulnerable.
• Secondly, issue of spillway capacity of dams able to pass PMF affects large number of dams, since they have been designed at different points of time with different criteria and a lot of changes have occurred since those designs were approved or not. Now that the PMF has already gone up hugely with increasing rainfall intensities in changing climate, and when we have not even assessed what impact climate change has.
• USA has a clearly defined system of assessing, certifying the dams that come under Federal or State domains, which we do not have. In this case, US system too failed to stop an avoidable disaster, but the existence of a system will help them, hopefully in quickly fixing the gap. When no such credible system or clearly defined code exists as in case of India, we have bigger task. Our Dam Safety Bill, the first step in that direction is still stuck in the Parliamentary approval process for over a decade, and in case, even if passed, that act is not going to help too much for lack of credible and independent process devoid of conflict of interest.
Hope India learns before we experience more disasters. Unfortunately, the experience so far with Tiware dam disaster of July 2019, the latest one, does not inspire confidence.
SANDRP (ht.sandrp@gmail.com)
