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Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA) 36

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msquared48

msquared48

Structural
Aug 7, 2007
14,745

Erosion has created a 300-foot-deep hole in the concrete spillway of Oroville Dam and state officials say it will continue grow.
State engineers on Wednesday cautiously released water from Lake Oroville's damaged spillway as the reservoir level climbed amid a soaking of rain.

Situated in the western foothills of the Sierra, Lake Oroville is the second-largest manmade reservoir in California after Shasta....
Click to expand...

Member Spartan: Stage storage flow data here for those interested:

Mike McCann, PE, SE (WA)
 
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itsmoked…

Nope. He's an electronics tech with a local school district and makes less than 2/3 what I make. He's actually proud to be "doing this well" and only having to work a fraction as hard as I do.

My brother talked about becoming an electrical engineer, but dropped out of college because taking two 4-units classes (Calculus and Physics) at the local community college, and getting A's in both, while not having a job was "too much work." At the time, I was taking 18 units/semester in civil engineering at the local university, working 35 hours/week, and maintaining better than a B average.

Funny you should mention attorneys because my old high school mints attorneys like the are coming off a copy machine. Back in the 1960s and 1970s, my high school was the top academic high school in all of Central California and one of the best in the state. In my class of 535 graduates, there are something like 40 attorneys. My wife's class (the next year) has a similar number of attorneys, including my old debate partner. My class has about 20 doctors, a physicist, several college professors, no famous athletes, and just 3 civil engineers. We have about 10 engineers total.

Fred

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
 
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The UH OH just got a lot bigger...

I would really like to see some facility drawings on the project. For the emergency spillway to function without failure, it had to be designed for overtopping. What is the maximum design lake level though, and that been exceeded?

I am confused too.. the original emergency spillway first posted was limited in wodth. JAE'S drone shots are much, much wider. What is the extent of rhe emergency overflow? Total release at this point has to be in excess of 140000 cfs at this point from everything I can gather...


Mike McCann, PE, SE (WA)


 
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msquared: The pictures of the guy pumping concrete into the riprap below the lip of the emergency spillway two days agodidn't give me warm fuzzies regarding the state of that outfall.

2017-02-12_23_51_09-Oroville_Dam_Spillway_-_02_10_2017_-_YouTube_bdrmsx.png


2017-02-12_23_51_44-Oroville_Dam_Spillway_-_02_10_2017_-_YouTube_misi3s.png


Go to 4 minutes for the video:
 
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Town just got evacuated (edit: missed the mention of this above, sorry. Though there were a few updates since then). [URL unfurl="true"]http://gizmodo.com/california-town-given-one-hour-to-evacuate-before-dam-s-1792281839[/url]
[URL unfurl="true"]http://abcnews.go.com/US/wireStory/latest-officials-order-evacuation-california-dam-45446241[/url]
Looks like the emergency spillway was eroding which triggered the evac but has since slowed down it's erosion. They're planning to plug the eroding area with rocks airdropped by helicopters.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
 
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About 188,000 under evacuation according to 10 pm news, King tv 5, Seattle.


Mike McCann, PE, SE (WA)


 
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Some good aerial pics of the emergenc slipway here
Can only assume the bit they were worried about was the junction of the emergency spillway and the normal one, where they were busy pouring concrete....

The road has already gone that was there.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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They pulled out the stops on the primary spillway. "To hell with the down hill erosion". It was cranked up to 100,000cfs (plus the 17kcfs used in generation) in hopes of taking the pressure off the emergency spillway.

It worked.

At about 1AM the emergency spillway went dormant.

It's still a mystery what was seen to be eroding that was so concerning to officials.

Keith Cress
kcress -
 
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I'm wondering if the thing they were concerned about was on the LHS of the spillway as you look from downstream. You can see that the water level was so high that water was flowing from the entire area to the ~LHs and creating a gully right at the end of the concrete slope. If you look at the picture racoope posted you can see the concrete seems to end abruptly. Maybe that end was being eroded by water flowing from the grassy areas and getting behind the concrete face of the spillway / eroding the toe??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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It wasn't obvious what the issues were with the normal and emergency spillway, but one issue is the transmission towers at the lower left of this Google Maps image, which sit between the two spillways, and either one could generate hill erosion that could potentially topple the towers.

oroville_dam_ktze0s.jpg


TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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The mighty engineer

I got a 404 to that link, but this is where I think they were concerned - I would have been.

Basically the end of the concrete ramp where the water from the rest of the area is funneling down, threatening to get behind the concrete wall.

Also very difficult to inspect until the water stopped.

dam_vgdzey.png


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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Do we know if engineers are making the decisions about spillway opening (throttling or free release), or are enviro's, bureaucrats, and politicians?

I know sheriifs are deciding on the evacuations downstream, and that is (more or less reasonable) since they do have to respond if/when flooding occurs to their people.

(By the way. How many delta smelt have been washed out into the Pacific Ocean? Bet the newly-muddy river has none left in its banks.
 
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I needed to get some perspective on the volumes of water being referred to. The current estimate for flow over the primary spillway is 100,000 cfs, plus additional over the emergency spillway. For comparison, the average flow over Niagara Falls is 85,000 cfs. WOW!
 
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Does 2800 tonnes per second make it easier to visualise? The forces at work here are difficult to imagine.

I've lived on the North Sea coast for most of my life and I've often thought that each time man builds something to defy Mother Nature it is a very one-sided fight we are entering into.
 
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Water's moving somewhere between
30 to 60 fps depending on the cross section of flow. Lotsa energy there!

Mike McCann, PE, SE (WA)


 
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