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

 

[saikee119]

So the people worrying about the fresh water mussels in the Wixom Lake and the ability of running boats in their back garden called the shot and might have caused the dam to collpase. They probably know more about the dam saftey than the party who operates it. Whaterever the arrangement it was reported Boyce the hydro owner was instrcuted to raise the lake to a specified level with court papers.

It is evidently clear that the interest of the dam owner was in a planet different to that of the local residents so it was a time bomb waiting to be set off.

If the dam has now been sold for 8 millions then Boyce has done everything right. The generration only earned revenue of 1 million each year. After the licence was revoked 2018 Boyce lost $6000 per day according to court papers. Thus the best way out isfor a sucker come along legally instructed the Wixom Lake level to raise and the dam failed.

 

[saikee119]

There was a video footage based on which the local agencies decided to ask the residents to move out. In it the two sets of spillays of Edenville were seen operational. I could not detect if the hydro units were letting out water or not. It the hydro units were passing water through they might have bought more time.

In theory to generate 4.8WM with a 16m head the discharge would have been around 30m3/s or 30 tons of water every second pushing through the tailrace of the hydro. The Francis machines there would have to be a free spinning mode (not generating or sychronzing).

 

[Spartan5]

Can anyone here who is crying foul at the local/state agencies show anything substantial that indicates that Boyce lowered the water level due to safety concerns?

Is there a report somewhere I’ve missed that details what the structural deficiencies were that required Boyce to immediately lower the water 8 feet without any notification to regulators or residents?

Legal posturing aside, all indications are that Boyce took it upon themselves to lower the water level to save money on winter operations costs; at great expense to environment and economy of the region. Of course the state made them put it back to the NORMAL operational level.

Absent some report detailing the reasons the water level had needed to be lowered for safety, the state’s requirement that they keep the lake at the level it had always been kept at was not a proximate cause of the failure.

 

[3DDave]

The state had already identified the dam as deficient; any ordering of increased water level was irresponsible for the state to mandate regardless of the dam operator's motives; in fact, the state should have been demanding the water be drained earlier for concerns over insufficient spillway capacity. The state already had information that the normal level was unsafe.

 

[Spartan5]

You’re talking about the deficiencies that the federal regulators had identified in 1999, right? And had not required any lowering of the water levels to mitigate the issue? Those deficiencies? FWIW, the state was working to complete their own engineering analysis when the dam collapsed.

 

[LittleInch]

Well most things it was a balance of issues and risk. At the time no one j=knew what the rainfall was going to be, but the immediate crisis was a relatively sudden lowering of the lake level resulting in significant ecological damage.

The real crime here was in apparently not having a reliable emergency spillway suitably protected to avoid washing the rest of the dam away.

That bit should have been relatively cheap to do.

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

 

[saikee119]

I have been saying all along that everyone was flogging a dead horse.

The dam is 96 years old and its design was acceptable then.

A little guy bought the dam for $4.8 millions and got $1 million income from generating the hydro.

The state agency in 2004 found the dam unable to cope with modern flood conditions and need to double the capacity of its spillways which there were two.

As millions were involved in the modification so the little guy did nothing more than maintaining the existing system. Due to his inaction he was punished by revoking the generation licence thereby stripping off his income stream.

At the same time the regulatory power was transferred to the local agency EGLE. It demanded from the little guy more facilities for the lake like car parks, disable bays, access steps, railings etc at specified locations.

It is doubtful that the little guy could be obligated to provide the extra facilties and/or to expand the infrastructure. He could choose to drain the lake to a safe level when the hydro was not allowed to generate while waiting to find a buyer for the asset. He was apparently prevent from lowering the lake level as that could trash the property values of the surrounding houses.

After the dam failure it was eveident from the post-failure video footage that we do not have a large river here but just a modest stream. Technically if the little guy was able to call the shot he should be able to bring the lake water to a safe level or even drain it substantially using the pipework associated with the 4.5MW hydro plant which I estimate to have the flow rate around 30m3/s (or 30 ton of water in every second). This is just by opening the main inlet valve, let the water passing through the system, the generator electrically disconnected and the turbine allowed to spin freely. The little guy would minimize such operation as it wears the parts down. Based on published data the little guy should have a good chance to keep the dam safe against one in 500 years flood simply by adjusting the lake level low enough to anticipate the flood.

The interest of the little guy is different to the interest of the local residents represented by the local agency EGLE. The latter has taken upon themselves to serve written instruction to the little guy to raise the lake level to a specific level now proved to be fatal.

In my book the little guy should be off the hook now.

 

[saikee119]

The real crime here was in apparently not having a reliable emergency spillway suitably protected to avoid washing the rest of the dam away.

That bit should have been relatively cheap to do.

The Edenville had an emergency spillway comparable in size to the one integrated with the hydro. This is evident in the footage I posted on 24 Jun 20 19:22 which is possibly one of the most important piece of evidence.

The modification work could be quite substantial if the dam was still impounding Lake Wixom. Also when the dam failed it is evident the dam was just an earth filled dam without any erosion protection. The modification is likely to require extra dam height, extra widths, extensive erosion protection, rehabitation of the existing spillways and reinforcing the downstream areas with concrete apron and energy dissipators. It wouldn't be just adding 100% more spillway but bringing a 96 years design to the current standard.

Also the two existing spillways have taken up a good portion of the dam section so the addtional capacity has to be fitted in with the existing infrastructure which comprises of partially man-make dams plus natural earth mounts.

 

[LittleInch]

Saikee,

I watched the video listed but I would term the spillway as just that - a controlled spillway.

What I mean is a purposeful slightly lower area of the main dam which is suitably protected but allows spillage over a large length to protect the rest of the dam.

Contrast that dam with the smallwood dam

https://www.youtube.com/watch?v=EaWPQNa6OjE

where although it "overflowed" and consequently did flood the downstream, but no where near as much as if the whole dam had gone.

You can see the sheet piling work around the earth core dam and the emergency spillway working as it should to reduce water level to prevent uncontrolled overtopping and complete dam failure.

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

 

[saikee119]

LittleInch (Petroleum),

I would agree that there were two spillways, called Tabacco River and Tittabawassee River spillways according to the Spicer Report. The emergency sections of them for overflow, if existed, were not clear.

It is interesting to note the court papers served on Boyce the dam owner was about a drawdown of 8'.

The Spcier report describes the sill level of the spillways being 667.8ft and the normal lake level of 675.8ft. Thus the difference is exactly 8'. It is possible that Boyce wanted to leave the lake at a level so that all excess water would be discharged via the spillway, as that mean no attendent would be necessary for a defunct hydro plant.

The Spicer report also described the Federal estimates of Probable Maximum Flood (PMF) being between 74,360cfs (original), 61,936cfs(2011) and 67,800cfs(2013) for the Titabawassee/Tobacco rivers. Michgan State's own standard is apparently to mandate the dam to pass 1/2 PMF.

The combined net width of the two spillways was 129ft. Since the top of the dam is 682ft so the discharge capacity of the two spillways when the water level breached the top of dam is about 21,000 cfs which does not meet either the state or Federal requirement, according to the Spicer report.

Historical peak flow rates according to this site ranged between 39,000 to 28,000cfs between 2017 to 1943. On the day of dam failure one report claimed a maximum flow of 60,000 cfs while another quoting a station further downstream at Sanford dam recorded 85,000 cfs

If the flow rate was anywhere near 60,000cfs then the dam was doomed even it has been modified to pass 1/2 PMF to satisfy the State's requirement.

 

[JohnRBaker]

Haven't heard much since June, so I guess this will have to do as a bit of an update:

Four Lakes Task Force: $338 million to rebuild dams, restore lakes

https://www.abc12.com/2020/09/11/four-lakes-task-force-338m-to-rebuild-dams-restore-lakes/

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[dik]

Why do the dams have to be reconstructed? Can they import the hydro?

Dik

 

[JohnRBaker]

The dams are not needed for power generation, but rather to restore the lakes, as noted in the article:

“This is a 100-year-old lake system almost. It’s got a history of being lakes, it’s got a legal lake level. We see this now as an environmental restoration program,” said Four Lakes Task Force President Dave Kepler.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[dik]

What's the downside of the lakes being smaller... like they were, originally?

Dik

 

[SWComposites]

Environmental restoration. BS. It is simply restoration of the former “lake front property” values.

 

[r13]

Without costly maintenance, the lake will only getting larger but shallower. I think they shall invest in building diversion channels to lessen the pressure on the lake, and start dredging.

 

[LittleInch]

Hence why the lake front properties are going to pay.

Don't know how many but if there were 1000 per lake, paying an average of $2500 per year for 40 years that's $100M.

Now whether the owners actually pay is another issue, but it might work.

The lake bed has now apparently re generated and starting growing so in 5 years time they'll probably find some protected creature and decide they now can't flood it and / or all the vegetation would create pollution when it decomposes under water. Or smells a lot.



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