Oroville Dam

[pwd72s]

Does this mean the drought has ended?

[Tobra]

I will take some shots of bridges over the Sacramento and American Rivers for you guys. Both are really high. The rivers around here are supposed to crest about 1600 today

As long the snow level does not get too high up the hill, it ought to be okay.

[rusnak]

I heard before the weekend that the Merced River would overflow. And the Fresno River looked like the Colorado.

[Fast Freddy 944]

Originally Posted by Crowbob

There's some amazing video of high voltage electricians dangling from helicopters flitting from transmission tower to transmission tower disconnecting equipment in case the emergency spillway gives out.

There's other video of a lone guy manipulating the nozzle of a cement pumper gluing thousands of tons of granite boulders together on one side of the reservoir near the dam itself.

The emergency spillway has split in two and is threatened by undermining at the bifurcation.

Dam!

[daepp]

So the spillway and gates were designed for a maximum water release of 250,000 cubic feet per second.

The DWR, who run the dam, say the releases at 65-70K CFS tore up the main spillway.
They have now throttled it back to 55K CFS.

I wonder what affect the environmentalists' favorite "pet" fish hatchery just downstream had on the timing and amounts of releases. I see lots of stories about the "heroics" of saving baby fish and fish eggs - threatened by the dirt in the fast-moving water - before they really opened up the floodgates.

I don't want to hear they waited to save the fish...

[lowyder993s]

Originally Posted by rusnak

I heard before the weekend that the Merced River would overflow. And the Fresno River looked like the Colorado.

This is a pier over the Merced...at least it USUALLY is...you can watch the salmon in the river from here. When I was here in Aug, the water was 15' below this pier!

[Crowbob]

Here's a pic, Curious George will love. I picked this up on my way into a government hydrologist, USGS, Corp of Wngineers town hall meeting when everybody was in a panic about Great Lake Levels.

After listening to harrowing stories about what could happen and whom to write letters of concern, I raised my hands for the Q&A.

A aksed what Lake Michigan looked like 10,000 years ago and the pencil neck said three words: Miniature Grand Canyon. Then I asked where is the rest of the data because this chart I have here doesn't even go back 100 years. Needledick said that's all the data.

[rusnak]

Not looking good for the Oroville spillway. They're trying to repair it one rock at a time.

[legion]

Originally Posted by daepp

I don't want to hear they waited to save the fish...

I thought I read an article that said, they did just that.

[jyl]

Originally Posted by rusnak

Not looking good for the Oroville spillway. They're trying to repair it one rock at a time.

What does that mean?

[billybek]

Originally Posted by jyl

What does that mean?

They are leaving no stone unturned....

Hope the situation doesn't get nasty for those downstream.

[Tobra]

They are dropping bags of rocks in the gap using helicopters

[jyl]

I'm reading the helicopters are dropping rocks in the eroded part, and they are then going to use cement to cover and stabilize the rocks. Access is very difficult.

[Holger]

Who builds a dam that cannot support a complete fill?

I hope this turns out well!
Today I heard in the news that the situation is a bit better this morning?

[jim72911t]

This thread hits close. Very close.

I have friends who have been displaced, and are either living in a shelter, or a crappy motel room many miles from home.

I also have friends who are working around the clock trying to rectify the situation.




Is it too much to ask to leave the politics out of it for the time being?

[ossiblue]

Originally Posted by jyl

I'm reading the helicopters are dropping rocks in the eroded part, and they are then going to use cement to cover and stabilize the rocks. Access is very difficult.

I witnessed this on the news. There was an aerial video shot of large rocks spread out at the foot of the emergency spillway, and a worker was shooting concrete from a hose around the gaps in the rocks. At the time, I thought that the concrete would not be cured enough to do any good, but if the mix was gunite, it would likely hold up fairly quickly.

Originally Posted by Holger

Who builds a dam that cannot support a complete fill?

I hope this turns out well!
Today I heard in the news that the situation is a bit better this morning?

Just to be clear, the dam is not in danger and certainly supports a complete fill. If you mean by "support a complete fill" that the regulation of the water level is faulty, then you may have a point. However, the main spillway has worked perfectly for 50 years, often in years with complete fills and then some. This time, there was a break in the spillway bed (which to my knowledge has not been explained) that caused the flow to be reduced to the point where the lake level rose to breach the emergency spillway brim--something that has never happened. Projections of the ability of the emergency spillway to handle the overflow were theoretical and have proved to be in error. That's why the situation is as it is, today.

[rusnak]

The answer as to why the spillway footing was eroded was addressed in an engineer's report. The answer as to why nothing was done is a story of California politics in the region that it is built.

[island911]

Clearly, before any repairs are made, we need a few years of environmental impact studies....

Seriously, from what I see, the engineers built in plenty of safety factor. What's being washed away appears to be fill-dirt on top of some serious granite.

[tevake]

"Just to be clear, the dam is not in danger and certainly supports a complete fill. If you mean by "support a complete fill" that the regulation of the water level is faulty, then you may have a point. However, the main spillway has worked perfectly for 50 years, often in years with complete fills and then some. This time, there was a break in the spillway bed (which to my knowledge has not been explained) that caused the flow to be reduced to the point where the lake level rose to breach the emergency spillway brim--something that has never happened. Projections of the ability of the emergency spillway to handle the overflow were theoretical and have proved to be in error. That's why the situation is as it is, today.[/QUOTE]

I'm just not sure how you can so positive about that, Osiblue, when the officials onsite have determined that a large scale evacuation is called for.
The compromised area in the emergency spillway as well as the large whole in the primary spillway, both may weaken the dam itself, or the critical surrounding terrain.

On Kauai we had a catastrophic earthen dam failure. When the intended spillway was partially filled in by the owner of the property was doing filling and grading in the area.
On a particularly persistent period of rain the water flowed over the dam itself causing erosion on the lower part of the dam, leading to a total failure and colapse of the dam.
With considerable loss of life down stream.

This was a much smaller dam and probably not exactly the same set up as the one in Ca.
But in my mind any time there are serious compromises in the body of an earthen dam,
The situation is serious and possibly catistrophic.

I certainly hope things with the dam go well, and the folks now having an evacucation, are soon safely back in their homes.

Cheers Richard

[rusnak]

Originally Posted by ossiblue

This time, there was a break in the spillway bed (which to my knowledge has not been explained) that caused the flow to be reduced to the point where the lake level rose to breach the emergency spillway brim--something that has never happened.

This could very well be a 100 year flood, which would explain why the dam has never failed.

But the worrying part is that the break in the main spillway is still there.

And they are releasing more water down it than ever before. It's kind of like hoping that the dam does not fail while trying to save it with procedures that can kill it.

http://www.vox.com/science-and-health/2017/2/13/14598042/oroville-dam-flood-evacuation?yptr=yahoo