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

[msquared48]

http://www.msn.com/en-us/news/us/ga.../ar-AAmLuQj?li=AA4ZnC&ocid=spartandhp#image=1

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....

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

https://cdec.water.ca.gov/cgi-progs/queryF?s=ORO

Mike McCann, PE, SE (WA)

 

[JStephen]

Saw that, wondered why they weren't already dumping concrete into it, actually.

 

[MikeHalloran]

If the hole is already 300 ft deep, how can the dam not be at risk?



Mike Halloran
Pembroke Pines, FL, USA

 

[hokie66]

Mike,
The spillway is not over the dam, but still a big problem.

http://www.water.ca.gov/swp/facilities/Oroville/index.cfm

 

[itsmoked]

Man that's splitting hairs! It's the dirt next to the damn face that makes up the reservoir.

Somethings also odd. I can't see how you'd get a 300ft DEEP hole from that. Is that even possible?

I would not want to be living in Orville at the moment.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[hokie66]

I don't see how it is "splitting hairs" to point out that the spillway is a separate structure from the earthfill dam wall. If the downstream face of the dam had a hole like that, look out all points downstream.

They probably mean the hole is 300 ft LONG, but you never know what to believe in a newspaper article.

 

[sbisteel]

I'd say 300ft wide is more like it.

 

[TehMightyEngineer]

While not an accurate news source I saw this on imgur this morning: [URL unfurl="true"]http://imgur.com/gallery/xHfxx[/url]

Apparently the current solution is to try to use the spillway at reduced capacity:

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[JAE]

So total collapse of the spillway surface off the edge and the water is now going around the spillway - probably further taking out the underlying soil beneath the spillway slab.
Probably will take the whole thing down to the bottom before too long.



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[TehMightyEngineer]

I guess they figure that wrecking the damaged spillway is better than utilizing the emergency spillway adjacent to the this which would just run down the side of the slope anyways.

Another picture at a higher flow rate:

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[MacGyverS2000]

Those baffle blocks seem to be working well... the water is going pretty damn slow once it hits the end of that spillway

Dan - Owner

http://www.Hi-TecDesigns.com

 

[MikeHalloran]

I notice the color of the water downstream of the hole; brown.
I.e., there's dirt in it, that didn't come over the top of the spillway.
This bodes ill.


Mike Halloran
Pembroke Pines, FL, USA

 

[msquared48]

The issue to me is obvious seepage under or through the dam above that undermined the spillway.

I would be far more concerned with the stability of the dam.



Mike McCann, PE, SE (WA)

 

[itsmoked]

Seeing it run down NEXT to the spillway is a whole nother layer of 'oh damn'. Pretty chilling.

Mike, good eye.

Isn't it great too, how they are feverishly working to make the emergency spillway functional by removing
trees etc. I guess you always have lots of time to get emergency systems operational
during EMERGENCIES.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MikeHalloran]

<inexpert opinion>

I hope they are not removing entire trees.

I'd guess that severely pruning the tops but not killing the tree, turning them into giant Bonsai, and leaving the roots intact, might be better for stabilizing the soil.

</inexpert...>


Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

See picture 6 in the slide show.

http://www.latimes.com/local/lanow/la-me-oroville-erodes-explainer-20170210-story.html

Hole is much farther from the dam than it appears in elevation pictures.

 

[JohnRBaker]

Yea, I'd say it's pretty unlikely that this will weaken or even damage the dam itself. In the image #6 it looks like one of those 'sink-holes' you see in the news all the time.

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

 

[MikeHalloran]

The sinkholes that you see in the news are often associated with a substantial water flow that you don't see.




Mike Halloran
Pembroke Pines, FL, USA

 

[cswilson]

Hmmm -- A picture ostensibly from 2013 -- looks like they're checking out that area of the spillway.

 

[MikeHalloran]

... and it sure looks like what they're investigating is water coming up through the spillway paving.

Where do you suppose such water might come from?



Mike Halloran
Pembroke Pines, FL, USA