2 dam failures in MI 7

[Phil1934]

https://www.cbsnews.com/news/michigan-dam-breach-10000-evacuated-state-of-emergency-declared

For those wondering if 2020 could get any worse

 

[GeoEnvGuy]

I looked at the video and seen the Edenville dam at the moment before collapse. The downstream slope appears to be 1.5H:1V with a vegetative cover. It looks like a shallow failure occurred likely due to the high phreatic levels in the dam causing an elevated seepage emergence at the toe of the dam. This then allowed for an internal erosion mechanism to erode the core of the dam and finally cause a collapse of the crest to allow for continued erosion of the dam and large release of the upstream reservoir. From the video the Sanford Dam has a working spillway which was probably inundated to quickly to dissipate the surge of water and over topped, where it likely did not have an emergency spillway to protect from a large release.

The video states the last assessments gave them a unsatisfactory and fair condition for the upstream and downstream dams. As tragic as this is I believe that both dams failed because of a reliance of previous track record, a lack of a emergency spillways, relying on outdated hydro-logical and stability modelling and lack of real time instrument monitoring. This could have been prevented if the Edenville dam downstream slope was flattened slightly and if both dams had emergency spillways.

 

[Spartan5]

https://water.weather.gov/ahps2/hydrograph.php?wfo=dtx&gage=midm4

 

[EdStainless]

I recall discussions about these dams when I lived in MI 45 years ago.
It must be a real mess up there.

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P.E. Metallurgy

 

[GeoEnvGuy]

I found this article from the detroit news and it has a nice commentary of the life of the dam which was built in 1925 as a hydro power dam and the flood risk was identified in 1999 by FERC. I find it odd that the owners were unable or unwilling to increase the spillway capacity for 20 years. The article states the dam is set to be sold in 2022 so $100 million dollars in upgrades can happen but the current upgrade plan is in court for being insufficient to provide probable maximum flood protection.

https://www.detroitnews.com/story/n...voked-failure-reinforce-structure/5226539002/

 

[charliealphabravo]

Has anyone seen a video of the failures? I'm surprised I can't find one considering how closely they were being monitored.

 

[Phil1934]

The Edenville dam lost its license 2 years ago

https://www.freep.com/story/news/lo...-dam-permit-flood-midland-gladwin/5226648002/

 

[human909]

Has anyone seen a video of the failures? I'm surprised I can't find one considering how closely they were being monitored.

Here is one of Edenville Dam.

https://www.youtube.com/watch?v=Hc3u_CHVHJ8

As far as I am aware the Sanford Dam hasn't failed yet. But it is overtopping so it is likely a matter of time...

https://www.mlive.com/news/saginaw-...undment-at-sanford-dam-in-midland-county.html

 

[3DDave]

The technical failure of the dam is of nearly no interest. It's an old earth dam, operated by a financially failing company that is desperate for a buyout and it rained a great deal. Earth dams blow out. It's what they always do if they are poorly maintained and this dam was already on the list as being poorly maintained. However it wasn't under government control to demand it be repaired so the owners blew off repairs. It's a minor echo of the Johnstown Flood.

There was no surprise in this failure and, in fact, a large number of people were there to photograph the breach as it happened.


I expect the cleanup to involve throwing paper towels again.

 

[Sym P. le]

As far as I am aware the Sanford Dam hasn't failed yet. But it is overtopping so it is likely a matter of time...

The Sanford dam, for all intents and purposes, no longer exists.

Youtube

 

[Alistair_Heaton]

This is a global comment not to the geographical location of these two.

I don't understand why when operating licenses are removed that they are not forced to empty these dams, drain them and keep them empty until they are sorted.

Most things if it fails a safety check then it gets shut down. To leave something full and operating is just unbelievable.

I have zero clue how dams work or are constructed.

 

[Phil1934]

They can't see what is gone from Sanford dam until the water level drops, but this feature makes no sense. "However, Sanford Dam's "fuse plug" — a spillway feature designed to wash away in high flood conditions to keep the dam from collapsing — has been washed out."

 

[LittleInch]

From this drone video I rather suspect the Sanford dam is no more. Part remains, but the main section to the North west looks like it has been completely destroyed.

https://www.youtube.com/watch?v=lzgu_Mnkfgk

There may be some little hump remaining, but it will be several metres lower than it once was

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[Milliontown]

They can't see what is gone from Sanford dam until the water level drops, but this feature makes no sense. "However, Sanford Dam's "fuse plug" — a spillway feature designed to wash away in high flood conditions to keep the dam from collapsing — has been washed out."

Fuse Plugs are pretty common on smaller dams, but they are on larger ones too. Its usually an earthen berm across a low spot along a spillway. It acts as an automatic natural "gate" that will be "opened" (eroded) once the water either erodes internally or overtops. Then the spillway can pass more water. It's a technique to help manage outflows during larger events. Common lower rain events may not trigger the fuseplug to activate, which will spare downstream innundation when its not necessary.


I'm still wondering what the initiating failure mode is for the Edenvill Dam. The video posted earlier shows the downstream face relatively intact, with some upstream depressions. There was water running over the crest indicated some form of overtopping, but did it overtop because there was a natural low spot along the crest, or did that potion of the crest settle because there was an internal erosion feature.

90% of my projects are Dam Safety projects on Earth and Rockfill dams, and I am waiting to see what the results of the investigation are, and if it will change our dam safety programs. However, I have a feeling this was avoidable based on current practices, but I will wait on a full investigation.

 

[LittleInch]

The issue about lowering the lake which has built up behind the edenville dam is now evident after its failure - huge mud flats and lots of no doubt expensive lake side properties with jetties now several metres above water level and a long way from the shallow river in the middle of the valley. The residents would not have been happy.

Lowering a lake that big would take a very long time to not flood the downstream areas.

The dam which nearly burst in yorkshire this year was a small fraction of the size and it took days to drain it with huge pumps and the drains fully open.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[3DDave]

This article seems to cover the history -

https://www.mlive.com/news/saginaw-...ends-floodwaters-hurtling-toward-midland.html

 

[LittleInch]

I suspect the fuse plug was that concrete structure but it only works if it is not completely destroyed by the water.

It's not clear if the mass of timber and debris is cause or effect in terms of blocking the main sluice gates, but any dam which is already high from rain to contain an upstream dam failure is asking rather a lot.

The initial edenville dam failure looks like a slope failure to me - see the video earlier posted by human909

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Also: If you get a response it's polite to respond to it.

 

[JohnRBaker]

Here's an image from Google Earth showing the Sanford Dam taken in June 2018. I assume that the circled area is this so-called 'plug':

Compare this with the pictures posted by LittleInch. BTW, my wife has an Aunt who lives less than 3/4 mile Southwest of the dam and a 1/4 mile from the river. We tried reaching her yesterday but got no answer on either her cell or landline. If we don't reach her today, we'll try calling her son.

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[Milliontown]

The initial edenville dam failure looks like a slope failure to me - see the video earlier posted by human909

That was what caused the breach, the loss of downstream slope. However what caused the slope failure is what will be the initiating failure mode. If the video was a little longer before the slope failure, there could be a little more info. I am starting to think it was an internal erosion failure mode. This failure event tree shows how this would happen. A void was formed within the embankment from erosion, which then lead to a collapse crest when the void collapsed. This also gave a seepage path along the base of that slope failure; you can see the water flowing out just at the bottom of the mass of soil. The slope then failed, leading to breach.

Interestingly, both dams were rehabilitated with a toe drain system to help prevent internal erosion. However, it appears from historic aerial imagery on Google Earth that the portion of Edenville dam that failed did not have this toe drain system installed.

This is all purely speculation and my personal opinion, and I am waiting for more facts and investigations to come out.

I suspect the fuse plug was that concrete structure but it only works if it is not completely destroyed by the water.

Concrete cannot effectively erode, so it was not the fuseplug. The concrete spillway appears to have a soil cover based on aerial imagery. This soil would act as the fuseplug. On-the-ground photos will help establish that. I'm sure some of this is available through FERC.

 

[Milliontown]

Sorry for the multiple messages, but I'm still thinking this through. It is possible this was purely a slope failure due to the increased seepage and rain saturation. In that case, the slope was not stable during an unusual event and should have been rehabilitated. As I said before, this portion did not have the toe drain. Looking at the other portions that did have this toe drain, an additional berm was constructed at the toe. This berm could have helped with slope stability, but again this is all purely speculation.