BREAKING: Fearing collapse of emergency spillway at Oroville Dam, Oroville evacuated

originally posted by: In4ormant
a reply to: Reverbs

I'm not confused as to what it is but one screen says spillway has failed and the other says spillway could fail.

There are two spillways.

The main spillway is broken - and has been for a few days - which has meant they had to limit the amount of water they could pass down it. As a result, the water level increased and eventually started to flow down the emergency spillway (which is the second one).

The water flowing over this second emergency spillway might be causing erosion that is putting it at risk of failure. This is a bigger problem than the main spillway breaking, because it would trigger the uncontrolled and uncontrollable release of lots and lots of water.

They are now releasing far more water down the main (broken) spillway than is safe, because it's still less dangerous than letting the emergency spillway collapse.

originally posted by: EvillerBob

originally posted by: In4ormant
a reply to: Reverbs

I'm not confused as to what it is but one screen says spillway has failed and the other says spillway could fail.

There are two spillways.

The main spillway is broken - and has been for a few days - which has meant they had to limit the amount of water they could pass down it. As a result, the water level increased and eventually started to flow down the emergency spillway (which is the second one).

The water flowing over this second emergency spillway might be causing erosion that is putting it at risk of failure. This is a bigger problem than the main spillway breaking, because it would trigger the uncontrolled and uncontrollable release of lots and lots of water.

They are now releasing far more water down the main (broken) spillway than is safe, because it's still less dangerous than letting the emergency spillway collapse.

What is/was the problem with the main spillway? In what way did it break or become ineffective?

More updates to the original OP article. Map of areas possibly affected, and evacuations expanded.

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

www.facebook.com...

Live Copter Recording over the dam right before dusk. Shows
both spillways aerial view, shows the area to the left of the
emergency spillway that is breached. Basically, water in the
parking lots overflowing the lots down and around the
emergency spillway edge.

originally posted by: annoyedpharmacist


What is/was the problem with the main spillway? In what way did it break or become ineffective?

that was the Big water slide

the bottom half of that slide is gone. eroded from underneath like a sink hole.

they didn't want it to keep breaking off higher and higher up closer to the top..

And now they are risking it's full failure to release pressure on the second spill way.

the second spillway has a hole in it.. They feared that hole would spread.. but every second the pressure on that hole and on other parts of the structure is lowering.

here is the original spillway



So both spill ways have holes in them.. But the first one if it fails is not anywhere as bad as if they let the side of the lake burst out..

Here is a good graphic to get bearings.



See the red marks showing the emergency spillway? the water coming over that part is eroding the earth back towards the dam..
And that part of the dam even has a hole in it now.. That's when they increased the water over the main spillway, further destroying that part, in order to not let the entire lake blow out..

originally posted by: stosh64
a reply to: jappee

Thanks stosh64 for the live stream.

Your welcome, Thanks for the thread.

Prayers are with these people tonight. Scary enough in daylight, can't imagine fearing a wall of water like this in the dark

Yes, this will get very bad if it breaches in the dark.
I hope people are wise and seeking higher ground and not be stubborn.


Side note; My 1000th post.

originally posted by: annoyedpharmacist

originally posted by: EvillerBob

originally posted by: In4ormant
a reply to: Reverbs

I'm not confused as to what it is but one screen says spillway has failed and the other says spillway could fail.

There are two spillways.

The main spillway is broken - and has been for a few days - which has meant they had to limit the amount of water they could pass down it. As a result, the water level increased and eventually started to flow down the emergency spillway (which is the second one).

The water flowing over this second emergency spillway might be causing erosion that is putting it at risk of failure. This is a bigger problem than the main spillway breaking, because it would trigger the uncontrolled and uncontrollable release of lots and lots of water.

They are now releasing far more water down the main (broken) spillway than is safe, because it's still less dangerous than letting the emergency spillway collapse.

What is/was the problem with the main spillway? In what way did it break or become ineffective?

A great big hole opened up in it. It appears (and to be clear this is speculation based on pictures) that the spillway was only partially built on bedrock and part of the supporting earth was compromised - almost like a sinkhole or something. Nobody realised until they needed to use the spillway and part of it... basically disappeared.

Water can still be let out through the gates at the top. The problem is that the spillway is there to guide the water safely to the river below. Because of that hole, water is no longer being safely directed and is eroding the surrounding soil - which may or may not cause other problems. So, they had to reduce the amount of water flowing down the spillway to reduce the impact of that erosion.

At this stage, they've clearly realised "to hell with it, it's the lesser of two evils" and cranked open the gates to increase the water flow.

originally posted by: EvillerBob


At this stage, they've clearly realised "to hell with it, it's the lesser of two evils" and cranked open the gates to increase the water flow.

yea.

So it's sort of controllable this way..

I think they passed the worst point and things will improve, only thing is it's going to rain three times next week..

If any of you live downstream those rivers are taking a lot of extra water from the dam and then the rains that are coming so just watch that as well.

the thing i dont get is why the emergency spillway is in danger of erosion. its not much of a spillway if its not capable of being a spillway. probly one of those infrastructure deals that had its money appropriated for some politicians pet project so it was neglected.

Anyone know who the contractor was that poured this dam? I have done a little looking, but cannot find anything...

TheBorg

originally posted by: Reverbs

originally posted by: EvillerBob


At this stage, they've clearly realised "to hell with it, it's the lesser of two evils" and cranked open the gates to increase the water flow.

yea.

So it's sort of controllable this way..

I think they passed the worst point and things will improve, only thing is it's going to rain three times next week..

If any of you live downstream those rivers are taking a lot of extra water from the dam and then the rains that are coming so just watch that as well.

I think... that we've had a few days of hearing "oh, we're over the worst of it" and it's still going wrong.

Hopefully the levels are now being brought under control but I wouldn't rest easy just yet. I still don't entirely trust the officials to be giving the entire story. The same people telling us that it's coming under control, are the same people who were saying a few days ago that the emergency spillway wouldn't be needed...

originally posted by: TheBorg
Anyone know who the contractor was that poured this dam? I have done a little looking, but cannot find anything...

TheBorg

all I know it was made in the 50s..

And the emergency spill way has Never been used before.

originally posted by: EvillerBob


I think... that we've had a few days of hearing "oh, we're over the worst of it" and it's still going wrong.

Hopefully the levels are now being brought under control but I wouldn't rest easy just yet. I still don't entirely trust the officials to be giving the entire story. The same people telling us that it's coming under control, are the same people who were saying a few days ago that the emergency spillway wouldn't be needed...

No I'm not saying it's safe. I'm saying the spill way has already passed it's max pressure level from water. It's down to two inches over the emergency spill way.
it's now less pressure but it could still break.

originally posted by: TheBorg
Anyone know who the contractor was that poured this dam? I have done a little looking, but cannot find anything...

TheBorg

its and earthfill embankment dam. so very little concrete in comparison to a solid concrete dam

And we are due for more rain here in Cali on Wednesday. Im at a safe distance, southwest of the dam.

The portions that began the failure in the main spillway, were spots that had been repaired previously. They didn't take the added water pressure, so the repair may be extensive, and costly. I read, up to $200,000,000

originally posted by: TheBorg
Anyone know who the contractor was that poured this dam? I have done a little looking, but cannot find anything...

TheBorg

I found this

I saw footage of the engineers surveying the spillway damage the other day. I was surprised to see how thin the concrete is on the spillway. It appeared to be 3-4 inches, with minimal reinforcement. I pour backyard patio slabs thicker, with more rebar, than one of California's most important dams. It's a dam shame, honestly.

a reply to: Naturallywired

Do you work for the government?

"old news, it's fine now, already posted...."

It's fine folks, nothing to see here, move along now...

We are with the government...we are here to help...please tell us everything...

Stay safe all. Glad to see the thread for people to share updates, needing help, etc.

UPDATE: Oroville Dam evacuations extended to Sutter County line
Source

Shelters:
Oroville Emergency Peer Accommodation Matching
Site

Neighborhood Church of Chico at 2801 Notre Dame Blvd., is welcoming evacuees that are affected by the #OrovilleSpillway @theorion_news

Twitter

The Chico Elks Lodge on Manzanita Avenue is offering emergency shelter. RVs can be parked in the lot, people can sleep in the lodge.

Twitter


Pets:
Sadly many people are having to leave pets behind. Please accommodate them if so, such as food, water and a dry space if the home floods.

Shelters accepting large animals

Rolling Hills Casino RV park has several spaces left and will accept large animals. @rhcasino @ButteSheriff @ChicoFD 3 replies 102 retweets 47 likes

Twitter

#orovilledam #evacuation Rolling Hills Equestrian Center has 300 stalls and will house your horses call Carol at (916) 826-1074 #california

Twitter

G eneral Shelter List-may have after hour contacts and info?:Will update as info is released.

Watching live news reports. They are saying gas stations are out of gas. Traffic is moving slow. One family said it took 4 hours to go 50 miles. That's to be expected i guess with so many people on the roads.

They are dropping huge rocks from helicopters to shore it up. Looks like they are doing all they can to prevent this disaster.

The jail was just evacuated and the hospital is on stand-by for evacuation.