Oroville Dam

[tbm3fan]

I just finished up outside and came into turn on the 6 o/c news to hear about the imminent expected failure of the spillway at the Oroville Dam. Mandatory evacuations have been ordered and people told to head north.

BREAKING: Marysville, Yuba County evacuated as Oroville spillway collapse feared

This is an earthen dam and the tallest in the U.S. A failure would result in the uncontrolled release of water authorities say. No s--t Jose and all the way to Sacramento if it does. Note Sacramento is the second most flooded city in the U.S. between the Sacramento and American Rivers. Makes you wonder who was the idiot who thought this was a great place to build a city by surrounding it with a levee system.

 

[commando1]

Officials earlier Sunday stressed the dam was structurally sound and said there was no threat to the public.

 

[tbm3fan]

My guess is that it will fail. All that water over the concrete edge of the emergency spillway hits the bottom and not only runs downhill but some undermines the concrete structure. Only a matter of time before the earth base is gone with the way water is flowing into the dam.

 

[patrick66]

This is only the second time water has gone through the spillway. It is not looking good for people downstream from the dam. My cousins have property along the river about 40 miles away.

 

[67-Fury]

Maybe California will be all under water and Create Arizona Bay.

 

[patrick66]

Officials in central California order emergency evacuations amid imminent collapse of large dam

 

[MrMoparCHP]

Even if the "Emergency" Spillway (PINK) fails were only talking about the 30' high concrete spillway. The current path the water is taking is through a ravine (RED) that is down stream of the dam and conventional spillway. The damage to the conventional spillway (BLUE) has hit bedrock and isn't growing by any notable amount. Both of the spillways are separated from the dam by a ridge-line (GREEN).

Even if the Emergency Spillway was to fail we're talking about 450,000 acre/feet of water, I could see it cutting the area under the spillway another 15'-25', even adding another 200,000 acre/feet I doubt any of that energy would backwash 3/4 miles back upstream to the dam. Even with the potential erosion at the area between the Emergency Spillway and the Dam, I doubt it would come near the dam, that is about 200 yards away with both the conventional spillway and the ridge-line between them. I do not feel that the failure is imminent and no actual damage has been spotted, only the potential with erosion happening close to the emergency spillway at the far left end.

They have just about maxed out the conventional spillway and we'll know by morning if it is good enough.


Alan

 

[commando1]

The dam height was calculated for a worst case scenario imaginable .
But... just in case they made the dam too low, they had a main spillway engineered to handle that problem. We covered our asses.
And just to make sure that everything was accounted for, the emergency spillway would take care of everything else that we couldn't imagine.

With all that planning, what can go wrong.

 

[MrMoparCHP]

...With all that planning, what can go wrong.

The flow over the emergency spillway may undermine the emergency spillway structure.


Alan

 

[commando1]

Can't use the word "may" when dams are discussed.

 

[MrMoparCHP]

Can't use the word "may" when dams are discussed.

That is why there is an evacuation.


Alan

 

[saylor]

damn

 

[detmatt]

I heard last night that the capacity of the spillway is around 50k gallons per minute and the amount of runoff flowing into the lake from the most rain in 1200 years is something like 180k gallons per minute. Even if that number is exaggerated that's not good math.

 

[1978 NYB]

I heard on the news they're going to drop big rocks in there to fill the gap and stop it from failing.

 

[commando1]

188,000 people under forced evacuation. Twice the size of my entire county. I can't comprehend the immensity of this tragedy.

 

[MrMoparCHP]

I heard on the news they're going to drop big rocks in there to fill the gap and stop it from failing.

I think the key here is that they are trying to minimize to erosion enough to get through the season. If the erosion hasn't undermined the structure this may be all it needs.


Alan

 

[1978 NYB]

As much as they say it is so nice to live in California.....

If I lived anywhere near the threat area this Dam failure I would be permanently moving today!

 

[saylor]

its gonna be some good TV when this thing lets go . . .


thats a decent sized lake.

 

[1978 NYB]

We have a huge damn very close to where I live. The Conowingo Dam on the Susquehanna River. We've had small towns Port Deposit Perryville down river flooded because of the massive amount of water coming through that dam during storms and hurricanes.

 

[1978 NYB]

Conowingo dam was a CCC project back in the thirties. There is a special on PBS about the construction of the Conowingo Dam that's pretty interesting.