What's Wrong with Beaver Dam?

[MickinMO]

With the auxiliary spillway added at Table Rock and the pile wall project at Beaver Dam in the 90s, now this:

https://www.swl.usace.army.mil/Media/News-Releases/Article/2748088/additional-interim-risk-reduction-measures-to-be-implemented-for-beaver-dam/

Something doesn't feel right.

[Devan S.]

Best I can tell there really isn't much change. 

 

[Ruger5555]

Rec boaters will be happy. Maybe they can fit under the 12 bridge more and quit asking if they can 🤣

[snagged in outlet 3]

Farmers down near Newport might not like it.   Isn’t that why they track that level down there?

[rps]

The only way to reduce a lake level is let or take the water out. This announcement means the Corps will release water sooner during rainfall "events" and longer afterward to avoid long periods of time at "flood" level. As always that will create a domino event down stream.

That means TR will get more water and sooner during rainfall "events." That leads to passing more water and sooner through Taneycomo and on to Bull.

An interesting part will be how well they meet the river height requirement.

Another will be the minimum flow changes and how they affect the fishing.

[Al Agnew]

Kinda interesting that "there is no imminent danger of catastrophic failure of the dam", but they want to "minimize" the risk of catastrophic failure.

I did a lot of reading about the Teton Dam a while back.  It was a dam in Idaho, built by the Bureau of Reclamation, which failed as soon as it was filled, and wiped out a couple towns downstream.  It was the only huge dam failure (so far), and was another factor in the defeat of the Meramec Dam in Missouri because it happened while all the controversy about finding caves in the Meramec Dam site was going on.  It failed because they allowed it to start filling before the main spillway was finished, so when it so happened that it was a record snow winter and the snowmelt coming into the lake was far greater than what they expected, the lake filled too fast and simply supersaturated the earthen dam.  Reading about it was amazing, and I wrote this about it for the book I was writing: 

The snowpack the following winter was extremely heavy, and by March of 1976 dam operators knew the reservoir would be filling more quickly than the standard rule of one foot per day.  They had no real choice in the matter, since the main outlet works that would have been able to carry off the excess water had not yet been completed, and they were depending upon the auxiliary outlet, which was designed to carry only a fourth of what the flow of the Teton River coming into the reservoir was going to be that spring.  By mid-May, the river was in full flood, and the dam was at its mercy.  No mercy was given.  On June 3, a small leak in the dam appeared.  The next day there were three leaks.  They remained small throughout the day.  But the next morning, Saturday, June 5th, 1976, there was a large stream of muddy water coming from the right abutment next to the dam.  Another leak developed at the contact point of the dam with the abutment.  At 9:30 AM yet another leak appeared twenty feet from the right abutment, which quickly became a torrent eroding the dam.  The chief engineer ordered the main outlet works to be opened even though he knew it would be hours or days before they could begin to carry off the water above the lake, and sent bulldozers in to try to stop the huge leak in the dam face.  At that point the hole was the size of a swimming pool, spewing pulses of muddy water.  The bulldozers had no effect.  A whirlpool was forming on the surface of the lake on the upstream side of the dam.  At 11:30 AM the hole suddenly widened by 20 feet and the bulldozers fell into it, their operators leaping off and running for their lives.  At 11:55, the crest of the dam collapsed into the reservoir, and two minutes later a third of the dam disappeared and a massive flood rolled down the canyon.

 Beaver Dam is a partially earthen dam.  It really sounds like that keeping the flood pool too long may be saturating the earthen part of the dam and weakening it.  Kinda worrisome.

[MoCarp]

 

[Devan S.]

I really think the entire press release is confusing.....it talks about minimum flow which only pertains to BS dumping into the white right? 

I've never really seen 950cfs from Beaver dam, 1900 cfs isn't even 1 generator at Beaver. It discusses the doubling of flow from 950cfs to 1900cfs which is something but really isn't considering BS has been releasing 5 to 10X that much over the last couple months and is still high.

Then they throw in the catch that TRL has to be below 917 which means its still "more important" and the 3 lake system has to be below 50% full for the doubling of the releases. 

Again talking purely from the standpoint of mitigating releases at Beaver I don't see it, at least from the press release. The only catch I can see is that previously I think BS and TRL had to be less than 2ft above normal before Beaver could dump. Now I guess they can do it if TRL is normal and BS is flooded but the 3 lake system isn't 50%. 

[Greasy B]

On 8/27/2021 at 8:17 PM, Al Agnew said:

Kinda interesting that "there is no imminent danger of catastrophic failure of the dam", but they want to "minimize" the risk of catastrophic failure.

I did a lot of reading about the Teton Dam a while back.  It was a dam in Idaho, built by the Bureau of Reclamation, which failed as soon as it was filled, and wiped out a couple towns downstream.  It was the only huge dam failure (so far), and was another factor in the defeat of the Meramec Dam in Missouri because it happened while all the controversy about finding caves in the Meramec Dam site was going on.  It failed because they allowed it to start filling before the main spillway was finished, so when it so happened that it was a record snow winter and the snowmelt coming into the lake was far greater than what they expected, the lake filled too fast and simply supersaturated the earthen dam.  Reading about it was amazing, and I wrote this about it for the book I was writing: 

The snowpack the following winter was extremely heavy, and by March of 1976 dam operators knew the reservoir would be filling more quickly than the standard rule of one foot per day.  They had no real choice in the matter, since the main outlet works that would have been able to carry off the excess water had not yet been completed, and they were depending upon the auxiliary outlet, which was designed to carry only a fourth of what the flow of the Teton River coming into the reservoir was going to be that spring.  By mid-May, the river was in full flood, and the dam was at its mercy.  No mercy was given.  On June 3, a small leak in the dam appeared.  The next day there were three leaks.  They remained small throughout the day.  But the next morning, Saturday, June 5th, 1976, there was a large stream of muddy water coming from the right abutment next to the dam.  Another leak developed at the contact point of the dam with the abutment.  At 9:30 AM yet another leak appeared twenty feet from the right abutment, which quickly became a torrent eroding the dam.  The chief engineer ordered the main outlet works to be opened even though he knew it would be hours or days before they could begin to carry off the water above the lake, and sent bulldozers in to try to stop the huge leak in the dam face.  At that point the hole was the size of a swimming pool, spewing pulses of muddy water.  The bulldozers had no effect.  A whirlpool was forming on the surface of the lake on the upstream side of the dam.  At 11:30 AM the hole suddenly widened by 20 feet and the bulldozers fell into it, their operators leaping off and running for their lives.  At 11:55, the crest of the dam collapsed into the reservoir, and two minutes later a third of the dam disappeared and a massive flood rolled down the canyon.

 Beaver Dam is a partially earthen dam.  It really sounds like that keeping the flood pool too long may be saturating the earthen part of the dam and weakening it.  Kinda worrisome.

Here is another fascinating dam collapse story, fortunately this one was a near miss. 
https://damfailures.org/case-study/fontenelle-dam/