Dam in CA coming from together....

PaulS said:
The dam is at risk Shawn, why do you suppose they are evacuating 190,000 people? The crisis seems averted for now, but the fear was the hillside would be eroded by the spillover and the dam would fail. More rain is expected now and they are trying to repair the spillways. The main spillway was eroding at a fast rate, guess which direction the failure was headed? Ignorance is bliss.
Click to expand...
The current major problem is erosion on the emergency spillway (just below the concrete lip). From what I read, if that erodes and gives way, there is about 30 vertical feet at risk below the emergency spill way itself. That would let a lot of water out of the lake, but does not equate to the dam itself giving way (which is 800 vertical feet).
 
f
Shawn said:
Where do you get your information? Twitter and Facebook? Educate yourself before you make arguments.

I opted to pay attention to CalOES, Department of Water Resources, and the agencies involved in the incident for the facts.
Click to expand...

Ok Shawn, whatever, why don't you start calling all those people and let them know you are of the opinion they are safe.
 
John221us said:
The current major problem is erosion on the emergency spillway (just below the concrete lip). From what I read, if that erodes and gives way, there is about 30 vertical feet at risk below the emergency spill way itself. That would let a lot of water out of the lake, but does not equate to the dam itself giving way (which is 800 vertical feet).
Click to expand...

Ok, I stand corrected, the hillside next to the dam is in danger of breaching bringing a 30 foot wall of water through a city of 190,000.
 
Shawn, you are right, the "dam" is safe, start calling all those people. :rolleyes:
 
PaulS said:
You basically just said the dam isn't at risk but they are worried the dam is at risk.
Click to expand...
No. That isn't what I said at all. The main dam is the part that is holding back most of the water. I'm talking about two spillways. Sure they're components of the entire dam complex. But there's a difference between the alternator in my car and the car itself.

A main dam breach would be significantly more catastrophic that what we're discussing here.
 
Here's what I found:

spillway0212.jpg


and here's a picture in lower water level days:

1adcf8ea0b8554d8c2fa4e7c13bfd20e.jpg
 
PaulS said:
Shawn, you are right, the "dam" is safe, start calling all those people. :rolleyes:
Click to expand...

I have been...trying to relax the fear from all that chicken littles that have been screaming "The damn is failing".

There is a big difference between downstream flooding which is very clear and precent danger and catastrophic damn failure which would indeed be a disaster of epic proportions...but not currently the danger contrary to a lot of sensationalism and political insinuations.

You want entrainment and insight in into the complete inability of the general public to process actual information?...just search the latest tweets of #orovilledamn on twitter.
 
Last edited:
MAKG1 said:
It would suck donkeys for the airport to be closed during an evacuation.
Click to expand...

Everyone always says that there is no such thing as an emergency takeoff. I disagree.
 
PaulS said:
Ok, I stand corrected, the hillside next to the dam is in danger of breaching bringing a 30 foot wall of water through a city of 190,000.
Click to expand...

Ah, no. That's not what is going to happen.
 
MAKG1 said:
It would suck donkeys for the airport to be closed during an evacuation.
Click to expand...
The chart says the lake is a seaplane base and under the TFR, so maybe "would" doesn't apply here.
 
asicer said:
The chart says the lake is a seaplane base and under the TFR, so maybe "would" doesn't apply here.
Click to expand...

No planes are actually based there. There is just a designated landing zone in the main body of the lake for seaplanes to have some fun.

My first inclination that I ever wanted to get into aviation was the idea that I could land in lake Oroville and motor right up to my houseboat for vacation! Spend quite a few summers wakeboarding and houseboating on that lake.
 
Ok folks, there is danger, but you know it's just a little danger, a little bit of death potential and probably a lot of destruction potential. It's not the dam that is in danger right now, but part of the dam complex. The problems were identified at least ten years ago, but, you know, money, so here we are, 190,000 evacuated from their homes, apparently unnecessarily, but some guys on the internet say we shouldn't be so worried because, you know, you said dam, instead of dam complex (good description by the way) and the experts who said this dam complex was safe 10 years ago told us a 30 foot wall of water could escape at once if the spillways continue to erode, but of course that wall of water would disperse over a larger area so, that's not as bad. Of course it could be worse, but the dam officials, who said this wouldn't happen, said no. Oh, and you know, there are a lot of problems, so why would you address something like this.... it's too hard.

I think I've got it now.
 
That metabunk site is excellent. Thanks for posting it. Doesn't sound like the actual dam is in jeopardy because of the bedrock between it and the spillway, but Yaysus, the manager has only had the job for 2 months? Talk about drawing the short straw.
 
If a spillway fails, it can erode a path for the water AROUND the dam and drain the dam. Anyway, they don't evacuate 150,000 people if there isn't a real danger. I don't think anyone on this board really understands the failure mode except to make some guesses.
 
coloradobluesky said:
If a spillway fails, it can erode a path for the water AROUND the dam and drain the dam. Anyway, they don't evacuate 150,000 people if there isn't a real danger. I don't think anyone on this board really understands the failure mode except to make some guesses.
Click to expand...

Right, but in post 47 the picture shows how long and gradual the run-up is to the spillway. It isn't likely (IMO) that you'd see a failure across a substantial portion of that spillway's width on a short term basis. And I'd think if they started seeing a problem, they could dump rubble into the <small> channel to stem the erosion.
 
Should we tell them, based on your assesment, to rescind the evacuation order? I mean they NEED TO KNOW SOON!!!!
 
Let's face it, they have some gray haired, wrinkled brow Civil Engineer experts on it. I guarantee it.
 
I just started following this (no I'm not in the States right now.) It's a scary situation. The Folsom dam was just recently upgraded with a new emergency spillway, installed for the purpose of protecting the dam which has known to be a weak link. Folsom is also fairly insignificant among the three major CVP dams (Shasta, Oroville and Folsom) in terms of water storage capacity. I would have thought the Corps of Engineers would have paid more attention to Oroville than they have, since it's the #2 piece of infrastructure in the CVP. Its loss would devastating to the state's agricultural economy, flooding damage not withstanding.

Late last year I attended a presentation by the Bureau of Reclamation on the construction of the Folsom spillway and got a tour. The politics behind getting these improvements constructed is incredible. The Corps is responsible for building the dams, and the Bureau is responsible for operating them. They don't get along. It took and act of congress (literally) to get them to work together on the spillway project.
 
I can't get over the price to repair these spill ways, 200 to 300 million? Sounds like we need Trump to do some negotiating here.
 
coloradobluesky said:
Let's face it, they have some gray haired, wrinkled brow Civil Engineer experts on it. I guarantee it.
Click to expand...

Grey hair. Check.
Engineering Degree. Check (though not a CE)
Wrinkled brow. Check
Appreciation for the fact that water always wins. Check.

(Engineers only fight delaying actions against water.)
 
coloradobluesky said:
If a spillway fails, it can erode a path for the water AROUND the dam and drain the dam... I don't think anyone on this board really understands the failure mode except to make some guesses.
Click to expand...

You are guilty of making those same exact guesses that you accuse others of in these two lines alone.
 
Time for folks who get their water from that lake to start watering their lawns and take real long showers.
 
On the bright side, CA might have a new attraction after that spillway water is gone.

Fossils.

That's what we got when a flood overwhelmed our dam in Iowa. Spillway overflow washed out a gorge revealing the bedrock, which turned out to be a 375 million year old fossil bed with all kinds of weird Devonian fossils, and now the Corps of Engineers encourages you to just walk over this fresh fossil bed and enjoy it. It's especially popular as a family outing, to show kids.
 
NoHeat said:
On the bright side, CA might have a new attraction after that spillway water is gone.

Fossils.

That's what we got when a flood overwhelmed our dam in Iowa. Spillway overflow washed out a gorge revealing the bedrock, which turned out to be a 375 million year old fossil bed with all kinds of weird Devonian fossils, and now the Corps of Engineers encourages you to just walk over this fresh fossil bed and enjoy it. It's especially popular as a family outing, to show kids.
Click to expand...

Ahhh, you're a silver lining kind of guy. :)
 
Yeah, just after this record year they had all that water being stored, for Summer. Now they have to release it to get back to work on the dam, no other choice.

Bummer.
 
So the emergency spillway IS concrete. There's 1000 feet of spillway. The problem appears to be threefold...

1. Where the water is LANDING isn't concrete, except for a small portion, so the impact of the water lead to significant erosion, which risks undercutting the existing structure.

2. The other is that the water extended above and beyond the edge of the spillway and started overflowing from that parking lot area, going *around* the end of the auxiliary spillway and risking cutting a channel on the side of the auxiliary spillway.

3. The main spillway is compromised and is allowing water to dip under it and is cutting away at the hillside beneath the spillway and the hillside next to it.

None of that is that the main structure of the damn is threatened. It's so hard to find good info that isn't sensationalist. I was looking earlier for new video/still photos of the area... but everyone is showing the main spillway since that's the most impressive water display.
 
You must log in or register to reply here.
Back
Top