Lake Oroville emergency spillway expected to fail

[SternWake]

It would be quite frustrating to be a resident of the area under the dam. They knew 12 years ago the emergency spillway was not upto the task should it ever be required. And the regular spillway was showing underengineering and deterioration in the past as well.

Seems the decidsion makers were not willing to spend any money on it during a drought and funnelled money elsewhere.

Now they will have to spend double of what it would have cost to pave it with concrete, and hopefully it does not collapse when levels rise to 900 feet again and a 30 foot wall of water rushes down the valley, and really Effs everything up.

Seems a whole bunch of incompetence was employed, and once again attempts to be frugal corrupt and greedy will cost taxpayers much much more.

 

[GotSmart]

It may be built on bedrock but it is still an earthen dam so could be described as dirt on bedrock. The concrete structure that you see is just at the high water level from what I understand.
http://www.latimes.com/local/lanow/la-me-ln-oroville-dam-how-20170213-story.html
https://en.wikipedia.org/wiki/Oroville_Dam

Guy

The concrete structure is the dam itself. 768 feet tall.  It is not in danger.  Not one bit, not at all, never break.  

Next to the dam, is a rock ridge that has the spillway structures built on it.  That is where the problem is.  The fill on that , perhaps 20 feet, is where the danger is. That is what is being reinforced woth stone and rock.

 

[TrainChaser]

SternWake: "Seems a whole bunch of incompetence was employed, and once again attempts to be frugal corrupt and greedy will cost taxpayers much much more."

Oh, just pass it on to the next official when the political incompetents move up the food chain.

 

[DannyB1954]

SternWake, we are looking at this from the east coast and don't see why it is such a problem.

If the dam fails, the damage done would be comparable to a nuclear explosion. 200,000 people have been evacuated. No big deal?

 

[GotSmart]

[font=Georgia,]I never said the main structure was solid concrete.  The use of the word was for reasons of identification on the picture. The face is concrete[/font]

[font=Georgia,]Why the Oroville Dam Won’t Fail[/font]
[font=Georgia,]February 12th, 2017 by Roy W. Spencer, Ph. D.[/font]
[font=Georgia,]While it is said, “never say never”, after researching this issue I’m pretty convinced that it would be nearly impossible for the Oroville Dam to fail.
Even though it is an earthfill embankment dam, which can be destroyed if the dam is topped, the following Metabunk graphic demonstrates why the Oroville design is virtually foolproof:
[img=550x356]http://www.drroyspencer.com/wp-content/uploads/oroville-why-no-collapse-metabunk-550x356.jpg[/img]
The emergency spillway (which is now in use) drains excess water along its 1,700 ft length when the lake level exceeds 901 ft. At this writing the lake level is 902.5 ft, which is 1.5 ft. above the lip of the spillway.
The water level would have to rise another 18.5 feet (!) in order to reach the top of the dam itself, which would never happen because the emergency spillway flow (which occurs over a natural ridge made of bedrock) would handle the excess flow long before the lake level ever reached that point.
Now, is there any scenario in which this might happen? I’m not a hydrologist, so I can’t answer that. But if there was a sudden warm spell in the next few weeks with say, 10-20 inches of rain over the watershed melting most of the mountain snowpack, adding tremendously to the inflow into the lake, I’m sure we would see a much greater flow over the emergency spillway. But I suspect it would never reach the top of the dam itself. Nevertheless, there would be a massive flooding event downstream in the Feather and Sacramento Rivers.[/font]

 

[29chico]

[font=Georgia,]I never said the main structure was solid concrete.  The use of the word was for reasons of identification on the picture. The face is concrete[/font]

[font=Georgia,]Why the Oroville Dam Won’t Fail[/font]
[font=Georgia,]February 12th, 2017 by Roy W. Spencer, Ph. D.[/font]
[font=Georgia,]While it is said, “never say never”, after researching this issue I’m pretty convinced that it would be nearly impossible for the Oroville Dam to fail.
Even though it is an earthfill embankment dam, which can be destroyed if the dam is topped, the following Metabunk graphic demonstrates why the Oroville design is virtually foolproof:
[img=550x356]http://www.drroyspencer.com/wp-content/uploads/oroville-why-no-collapse-metabunk-550x356.jpg[/img]
The emergency spillway (which is now in use) drains excess water along its 1,700 ft length when the lake level exceeds 901 ft. At this writing the lake level is 902.5 ft, which is 1.5 ft. above the lip of the spillway.
The water level would have to rise another 18.5 feet (!) in order to reach the top of the dam itself, which would never happen because the emergency spillway flow (which occurs over a natural ridge made of bedrock) would handle the excess flow long before the lake level ever reached that point.
Now, is there any scenario in which this might happen? I’m not a hydrologist, so I can’t answer that. But if there was a sudden warm spell in the next few weeks with say, 10-20 inches of rain over the watershed melting most of the mountain snowpack, adding tremendously to the inflow into the lake, I’m sure we would see a much greater flow over the emergency spillway. But I suspect it would never reach the top of the dam itself. Nevertheless, there would be a massive flooding event downstream in the Feather and Sacramento Rivers.[/font]

I have been there a few times.  On top of the dam itself and biking/hiking below it.

The face of Oroville dam is not concrete.   It is a rather sophisticated earthen dam.

 

[LeeRevell]

One question....
We have been hearing of major drought in California causing water rationing and supply problems. So, what caused this huge rise in water level? Rain? Snow melt? Just trying to understand the core problem. Has the drought ended?

 

[highdesertranger]

a combination of warm rain(lots) melting snow. highdesertranger

 

[GotSmart]

So far Northern California has recieved almost 200% of season normal rainfall, with more due in a couple days.  The drought is still in effect in some parts of Southern California.  Most of it in a short period. 

The evacuation has been lifted, and people are allowed back to their homes.. 

 https://www.yahoo.com/news/damaged-dam-system-threatens-northern-california-towns-075157958.html

 

[travlinman and wife]

check out what happened at wolf creek dam and lake Cumberland dam in ky and how much it cost tax payers.

 

[slynne]

I have been in Northern California for the past couple of weeks. Headed down to LA tomorrow. The first week I was here, there was soooooo much rain! Buckets of rain! And everyone said that it was even worse a couple of weeks before I arrived. There is moss growing all over the place. There has been a lot of flooding and road closures because of all the water. I just hope that the drought doesn't return.

 

[GotSmart]

There has been a historical  cycle of rain and drought.  Peope forget this little detail. 

file:///C:/Users/John/Downloads/California_Signficant_Droughts_2015_small.pdf

 

[TMG51]

There has been a historical  cycle of rain and drought.  Peope forget this little detail. 

file:///C:/Users/John/Downloads/California_Signficant_Droughts_2015_small.pdf

Pardon me but, you appear to have attempted to link a file on your local disk.

 

[GotSmart]

Speaking about forgeting little details...   :blush:

http://www.centralvalleybusinesstimes.com/links/California_Signficant_Droughts_2015_small.pdf

 

[DannyB1954]

I lived in the San Francisco Bay Area for about 30 years. During the dry years the cost of water went up as they said people were conserving so the cost to supply was higher per gallon. During the wet years some how the prices never went down.

Seems like any "emergency" is grounds for higher profits.

 

[TrainChaser]

The people have been allowed to go home, but they are expecting a series of five more storms, so there may be a repeat of this evacuation. Remain aware if you are in the area.