dc10lover
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Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 12:34 am

Californis is expecting 14" of rain through March. I think people in Sacramento, California need to be ready to evacuate. Officials are not expecting Oroville Dam to make it. Plus the mountain snow runoff will not help. Please watch youtube videos and such to keep up for the latest.

Thanks
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salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 12:54 am

dc10lover wrote:
Californis is expecting 14" of rain through March. I think people in Sacramento, California need to be ready to evacuate. Officials are not expecting Oroville Dam to make it. Plus the mountain snow runoff will not help. Please watch youtube videos and such to keep up for the latest.

Thanks
Do you have a source for the 14" of rain prediction? I haven't seen anything like that.
Do you have a citation for "Officials are not expecting Oroville Dam to make it", I haven't heard that.
 
Okie
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 1:03 am

Do not worry the EPA is sending its crew from Colorado to help. :duck:

Short term all they have to do is patch the normal spillway.
That is not a lifetime job opportunity.
They should be able to temporarily repair that pretty quickly between storms.

While there is a danger here of erosion of the spillway it is not near the problem of dealing with the emergency overflow destroying the dam itself.

Okie
 
johns624
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 1:05 am

That dam is less than 50 years old. Who hasn't been doing their job? Didn't they learn anything from Johnstown?
 
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einsteinboricua
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 1:40 am

The dam itself is structurally sound and officials are not concerned about its integrity.

What concerns officials are two things:
1. The primary spillway has a sinkhole which opened up last week. To keep pumping water down that spillway means eroding the sinkhole and making it bigger.
2. The emergency spillway is really just an overflowing wall to allow excess water to go down if the primary spillway cannot pump water fast enough. However, with the recent usage, terrain began crumbling away. If it continues to erode, the wall could collapse and send a 30ft surge of water down the hill in an uncontrolled manner. Oroville and nearby towns would definitely be destroyed if that happened. Sacramento? They probably won't feel a thing: there are many bypasses designed to take on some of that flow.

Officials over the weekend had their hands tied: do they shut off flow to the primary spillway and allow water to go through the emergency spillway (eroding the structure) or do they open the primary spillway and take the risk of destroying the primary spillway altogether?

There is rain in the forecast so officials are trying their best to pump out enough water so that the expected inflow does not merit the use of the emergency spillway or maybe even the primary spillway. That would allow officials to begin repairs, at least temporarily, until the dry season hits.

The dam is safe, Sacramento is safe, even Yuba is safe.
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salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:01 am

einsteinboricua wrote:
The dam itself is structurally sound and officials are not concerned about its integrity.

What concerns officials are two things:
1. The primary spillway has a sinkhole which opened up last week. To keep pumping water down that spillway means eroding the sinkhole and making it bigger.
2. The emergency spillway is really just an overflowing wall to allow excess water to go down if the primary spillway cannot pump water fast enough. However, with the recent usage, terrain began crumbling away. If it continues to erode, the wall could collapse and send a 30ft surge of water down the hill in an uncontrolled manner. Oroville and nearby towns would definitely be destroyed if that happened. Sacramento? They probably won't feel a thing: there are many bypasses designed to take on some of that flow.

Officials over the weekend had their hands tied: do they shut off flow to the primary spillway and allow water to go through the emergency spillway (eroding the structure) or do they open the primary spillway and take the risk of destroying the primary spillway altogether?

There is rain in the forecast so officials are trying their best to pump out enough water so that the expected inflow does not merit the use of the emergency spillway or maybe even the primary spillway. That would allow officials to begin repairs, at least temporarily, until the dry season hits.

The dam is safe, Sacramento is safe, even Yuba is safe.

I'm in the middle between you and the OP. There are portions of Sacramento which are vulnerable to flooding even in periods of heavy rain and the American River levees have caused some sleepless nights for Sacramento residents in the past. If the main spillway is required to handle massive amounts of water it can also fail completely and start an erosion process that could have disastrous consequences. The officials have a hard choice, to continue dumping water to lower the level of the lake will add to the damage to the spillway, but I don't see that shutting down the release of water is an option because there is no longer an emergency spillway available. They can't fix the main spillway and dump water at the same time. Strengthening the hillside below the emergency spillway would be a massive job, I can't picture that being done before next fall, if then.

This is a dangerous situation and a large surge of water into the feather river could flood significant parts of Sacramento.

Here is the main spillway damage.
Image
Last edited by salttee on Wed Feb 15, 2017 2:06 am, edited 2 times in total.
 
wingman
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:04 am

It pains me somewhat to say it but Trump is right about our infrastructure problem. It really is shameful how wealthy this country is and what a piece of shit it is compared to our peers in the G8. We're just cheap ass bastards when it comes to anything that isn't stealth and carries bombs. Dams, highways, schools..you name it, we do suck at building quality, long-lasting product. Just a few weeks ago I was in SF and took my first ride down 101 in 2-3 years. That thing was under reconstruction for about 5 years prior and I was simply stunned that it was already crumbling again. Hit the highways in France, Germany, Japan, Korea..totally different story.

But we'll never change unless we really can convince Mexico to pay for it all. Only mass death causes an uproar and even then we still just slap the shit back together again with the lowest possible bid and cheapest possible materials you can find. The Oroville Dam itself is probably a high quality marvel like the Hoover but those days in this country are long gone. Now we're just a patchwork of potholes. Would you pay an extra 10% in federal taxes if someone could guarantee wed look like Switzerland in 10 years? I would.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:14 am

wingman wrote:
It pains me somewhat to say it but Trump is right about our infrastructure problem

Trump is no rocket scientist when it comes to infrastructure or economics. Liberal economists such as Paul Krugman have been advocating spending on infrastructure for years but Obama would never have been able to get the Republican congress to go along with any plan to fund such a stimulus package. Deficit spending is a big no no when we have a Democratic president.
 
ltbewr
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:19 am

The Oroville dam was built and budgeted to likely handle a '100 year' or '300 year' extreme weather event with an emergency spillway just for those expected level of excessive water. This is likely a '500 year' event, something that would have meant many millions needed to be spent of limited budgets. Global warming and Climate Change may be additional issues here, pushing unusual volumes of moisture-laden clouds, very heavy snows along with too warm temps melting snow more quickly than historically occurred. This is not a design failure situation.
Still, this is very serious, with potential devastation of the homes and lives of about 190,000 people and possibly many 1,000 more further downstream.
 
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einsteinboricua
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:35 am

salttee wrote:
Here is the main spillway damage.

It's actually larger than that. That was when they first assessed the damage. It has since extended to the other side.

Image
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salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:55 am

einsteinboricua wrote:
It has since extended to the other side.

WoW! The lower part is a goner for sure..
 
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WarRI1
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 3:13 am

That is scary. This is the first pictures I have seen of the damage to the spillway. Is the danger from a collapse of the upper wall because of undermining the dam wall itself?? It looks possible if the whole hill collapses.
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Raventech
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 3:31 am

WarRI1 wrote:
That is scary. This is the first pictures I have seen of the damage to the spillway. Is the danger from a collapse of the upper wall because of undermining the dam wall itself?? It looks possible if the whole hill collapses.


That's not the dam, the spillway was built into the hill that anchors one side of the dam. The emergency spillway is then on the opposite of side. both the dam and the emergency spillway are off camera in that shot.
 
rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 4:23 am

wingman wrote:
It pains me somewhat to say it but Trump is right about our infrastructure problem.


I agree we have infrastructure problems, but I disagree that dams like Oroville are part of that problem.

IMHO our biggest problem with major infrastructure is that we have no consistent standards. We have 52 different sets of laws/ regulations. We have thousands of different contracting methods.

Because we all know that having the individual states and counties control the contracts in their area is much better than having a federal government with one nationwide set of standards.

---------

The current issues with Oroville only demonstrates a problem with ALL dams worldwide.

Spillways and emergency relief channels are designed to handle the biggest event the designers can imagine. By their very nature they cannot be tested to maximum design stress. There are literally a couple thousand spillways and emergency relief channels that have never carried overflow water. Every one of them is an 'untested' design. Each of them might suffer similar failures.

We cannot force Mother Nature to not put more stress/ water into the dam/ lake than the design specs.

Oroville has not demonstrated an infrastructure or design failure. It has only demonstrated that we don't and never will know everything, and Murphy is alive and well.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 4:54 am

rfields5421 wrote:
Oroville has not demonstrated an infrastructure or design failure.

How can you say that? The spillway is a part of the dam, you can't build a dam without some way of discharging water.
The spillway failed didn't it?
 
seb146
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 6:25 am

This is what infrastructure spending is supposed to prevent or at least minimize. Just sayin'
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seahawk
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 6:34 am

More sloppy construction. The concrete is a bit thin and it seems like they have not added any anchors to fix it to the compact stone. And considering the height and lay of the land I am wondering why they decided to go for a long ramp and not for an emergency overflow tower feeding closed pipes.
 
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Tugger
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 7:00 am

salttee wrote:
rfields5421 wrote:
Oroville has not demonstrated an infrastructure or design failure.

How can you say that? The spillway is a part of the dam, you can't build a dam without some way of discharging water.
The spillway failed didn't it?

But that is not due to design. It could be just a mechanical failure or construction flaw that became a failure event under duress of the current weather conditions.

I will note that the main spillway is built on bedrock, the bedrock the dam is anchored with. The hillside foundation beneath is won't erode to failure but the damage will be extensive.

Roughly the real problem is that the inflows to the reservoir are going to (and have been) exceed its maximum outflow capacity (which is exasperated by other outside factors,there are powerline towers that may be eroded), necessitating the use of the emergency spillway, and the emergency spillway is not on bedrock and the concrete apron is not cover enough ground to prevent erosion back to the reservoir itself. The inflows are expected to be potentially 250,000 cu ft/sec while the main spillway is normally a max of 200,000 but is currently limited to 100,000.

Tugg
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rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 7:24 am

salttee wrote:
rfields5421 wrote:
Oroville has not demonstrated an infrastructure or design failure.

How can you say that? The spillway is a part of the dam, you can't build a dam without some way of discharging water.
The spillway failed didn't it?


The spillway is a concrete channel which has held that volume of water before without problem.

What has occurred is that something left part of the spillway unsupported and the weight of the water appears to have broken through the surface of the spillway.

We don't yet know what failed. It could be undetected seismic activity has shifted something under the spillway. To could be something went down the spillway in the flooding that stressed the surface and created a minor crack. My suspicion is that an undetected weeper in the rock surrounding the dam will be determined to be the blame. (The documents I've been able to find indicate the spillway is not physically on the dam but on the virgin rock beside the dam.) Another note - ALL dams leak/ weep. Not just compacted earthen dams like Oroville, but also concrete dams like Boulder and Grand Coulee.

That volume of water is a force which can not be tested, only modeled. The 'low' volume of water was something close to 10,000 cfs- cubic feet per second - that is a volume of water approx 10 ft by 10 ft by 100 ft weighing as much as an empty B747.

The weight of another 747 pounding down the channel every second - 60 times a minute, 360 times an hour - constantly. And despite the best efforts, that much water does not travel smoothly and quietly. It is a driving hard force like a tsunami.

This dam has two methods to discharge excessive water and thus protect the dam. The designed gated spillway, which developed the collapse/ sinkhole. The emergency spillway which is a last desperate attempt to prevent failure of the dam.

The emergency spillway worked exactly as planned. Using the emergency spillway always presumed there would be major damage likely downstream.

Even if the emergency spillway had lost its shape and allowed 30 vertical feet of water through the channel, destroying much of the city - that is doing what it was designed to do.

In a strong enough flood, the goal is to contain the damage to the expected area and prevent a catastrophic failure of the dam.

Re: a tower pitock system - those always have a maximum capacity which cannot ever be exceeded. They accelerate the flow of water tremendously which greatly increase the chance of catastrophic failure of the pitock/ tubing system.

Read up on when the overflow spillways were used at Boulder / Hoover Dam. That dam always carries a risk of overtopping. A sufficient flood could do that if it put enough water into Lake Mead. An overtopped dam will fail catastrophically if the flow is not stopped quickly.

The Oroville Dam cannot be overtopped unless some seismic event changes the geography around the dam.

No dam can guarantee that there will never be major flooding / damage downstream if the inflow of water is sufficient. The folks operating the Oroville Dam appear to be doing a decent job of trying to minimize the damage.

I'm quite impressed by the orderly evacuation and the willingness to conduct that evac rather than risk lives should a more severe flood occurred.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 7:53 am

Tugger wrote:
salttee wrote:
rfields5421 wrote:
Oroville has not demonstrated an infrastructure or design failure.

How can you say that? The spillway is a part of the dam, you can't build a dam without some way of discharging water.
The spillway failed didn't it?

But that is not due to design. It could be just a mechanical failure or construction flaw that became a failure event under duress of the current weather conditions.

I don't see any sign of rebar, that looks like a design problem to me; if there were rebar it would have been evident in the picture I posted. If the concrete for the spillway had been poured with rebar in it, it wouldn't have failed. But if not a design fault, it was an infrastructure problem anyway. I can't understand how someone could say it was neither.

Tugger wrote:
I will note that the main spillway is built on bedrock, the bedrock the dam is anchored with. The hillside foundation beneath is won't erode to failure but the damage will be extensive.

I'm no geologist but that "bedrock" looks like sandstone to me. Pretty flimsy stuff as far as rock goes, you can see that the water has already dug holes in it.

Tugger wrote:
Roughly the real problem is that the inflows to the reservoir are going to (and have been) exceed its maximum outflow capacity (which is exasperated by other outside factors,there are powerline towers that may be eroded), necessitating the use of the emergency spillway, and the emergency spillway is not on bedrock and the concrete apron is not cover enough ground to prevent erosion back to the reservoir itself. The inflows are expected to be potentially 250,000 cu ft/sec while the main spillway is normally a max of 200,000 but is currently limited to 100,000.

The problem is that the main spillway failed while it was operating within its designed capacity. This forced the operators to reduce the flow below what was needed and caused an emergency condition.

The secondary problem is that the emergency spillway failed because it was poorly designed. Apparently they didn't hire a soils engineer to verify that the slope could support the amount of water flow that would take place in an emergency.

IMO the spillway system was built by cheapskates. Sort of like if Boeing or Airbus wanted to save money by cutting back on the size of the wing spar.
Maybe it's time for someone to go back and audit the construction of the rest of the dam.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 7:59 am

rfields5421 wrote:
In a strong enough flood, the goal is to contain the damage to the expected area and prevent a catastrophic failure of the dam.

The goal in building a dam is to build it so that it never fails - ever. Just like you build airliners so that their wings don't fall off - ever.

Why are you apologetic about this obvious engineering failure?
 
rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 2:40 pm

Actually airliners are built to a standard which will allow the wings to fall off in certain conditions. If they were built to a never ever possible for the wings to fall off - they would not be able to fly. They would weigh too much.

All engineering is to a standpoint where the risk of failure is minimized. It is ALWAYS a cost/ benefit decision. Yes, this is too often to a risk point others might/ do find unacceptable. And Monday morning quarterbacking is the basis of much of the US legal system.

Dams are designed to not fail, but engineers also design to deal with the possibility that the inflow of water might exceed the capacity of the base spillway system.

I can't find anything on the bedrock in the area of the dam. I doubt it is sandstone since most of the rock in the area is igneous. The choice to build a dam on the Feather River is of course a political / engineering decision which is subject for debate. Whether or not the Central Valley agriculture in California should be artificially supported by structures like the Oroville Dam is a valid debate. Whether or not the electricity to support the population of the Sacramento River valley is a valid debate. My personal opinion is that the state of California and its population/ agricultural level are artificially supported by political decisions which have no justification.

What is not subject to debate is that without this dam, the city of Oroville would have been destroyed by the flooding which filled the lake to near capacity. That flooding would likely have occurred before an evacuation could get everyone to safety. Likely deadly flooding as far down river as Sacramento.

No, I do not think this an engineering failure. The systems worked as planned/ designed. The volumes of water and forces it creates are beyond the comprehension of most people. That level of water can eat through the hardest rock at a near visible level.

The July 2002 spillway usage at the Canyon Lake Dam on the Colorado River of Texas - was up to 67,000 cfs. In six weeks, a canyon was created over a mile long, hundreds of yards wide and 50 feet deep through the bedrock limestone.

There were damages and problems revealed by the Oroville flood. The 2005 re-licensing decision to not provide additional support to the emergency spillway, to not re-engineer it to avoid the type of damage it sustained in this flood do point to some need to consider again that decision.

Even if the emergency spillway had "lost crest control" it would have done its designed job. It is not designed to prevent all damage to the mountainside nor to the downstream area. It is an EMERGENCY spillway to only be used in an emergency to protect the main dam from damage. The two spillways did do that job.

Some further study has revealed to me that in 2013 some cracks were observed and repaired in the main spillway. That does merit further investigation.

re: rebar - I'm not certain there is not, however a concrete spillway is similar to a railroad track or a bridge. It has to be able to flex and move as the forces of the water hit it. Something solidly anchored to not move at all only increased the possibility of failure due to point pressures. While this spillway was carrying a heavy volume of water, it was not carrying all the water in the area. There was obviously other water traveling down the embankment, and that non-spillway contained water could be the source of the initial failure.

I think you are expecting an impossible level of foresight from engineers.

Despite the 'emergency' the main point is the system functioned mostly correctly. A completely uncontrolled flood was averted. Even if they had lost the crest of the emergency spillway, the resulting flood would have been within expected limits.

Now we can have another discussion about whether or not people and industry should be allowed to build in flood plains, or how the "Army Corps of Engineers/ EPA have been forcing unnecessary limits and costs on business due to their unrealistic flood plain designations".

A great many people would consider the area evacuated around Oroville not in a flood plain.
 
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 3:50 pm

rfields5421 wrote:
Actually airliners are built to a standard which will allow the wings to fall off in certain conditions. If they were built to a never ever possible for the wings to fall off - they would not be able to fly. They would weigh too much.

All engineering is to a standpoint where the risk of failure is minimized. It is ALWAYS a cost/ benefit decision. Yes, this is too often to a risk point others might/ do find unacceptable. And Monday morning quarterbacking is the basis of much of the US legal system.

Dams are designed to not fail, but engineers also design to deal with the possibility that the inflow of water might exceed the capacity of the base spillway system.

.......


Great writeup rfields.

Here is an article detailing how the engineers are working to shore up the embankments and lower the level of the Oroville resevoir in order to weather the next set of storms.

http://www.latimes.com/local/california ... story.html


Currently northern California is having what looks to be the wettest Oct-Feb period on record. If this continues it will beat out the infamous 82-83 season.

It seems amazing when you consider for the last 7 years we have been watching a parching drought, and this year the atmospheric river has delivered the mother load. I use the word "seems" though as this may be the new normal due to changes in the climate, that seem to be indicative of the atmosphere carrying more moisture, but the moisture plumes may be few and far between for California.
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ER757
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 5:20 pm

The situation appears to be less dire now that some emergency repairs are underway. Evacuation orders have been lifted as officials are more confident it can now handle the incoming storms

http://www.npr.org/sections/thetwo-way/ ... nd-next-st
 
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 5:25 pm

rfields5421 wrote:
The current issues with Oroville only demonstrates a problem with ALL dams worldwide.

Spillways and emergency relief channels are designed to handle the biggest event the designers can imagine. By their very nature they cannot be tested to maximum design stress. There are literally a couple thousand spillways and emergency relief channels that have never carried overflow water. Every one of them is an 'untested' design. Each of them might suffer similar failures.


Baloney and neocon hogwash.

What you see is caused by pronounced maintainance shortcomings. Sorry, no money. we need the cash for profits.
https://en.wikipedia.org/wiki/Oroville_ ... nspections
https://en.wikipedia.org/wiki/2017_Oroville_Dam_crisis

Nothing unexpected or "fought valiantly and lost" about it.
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rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 5:30 pm

Here in Texas we have seen a lot of damage to dams, spillways and lake shores due to the combination of a multi-year drought followed by major rainfall/ flooding in 2015/16.

Long droughts damage the supporting under structure of dams and spillways. They are designed to use the weight/ pressure of the normal water levels to strengthen the impoundment.

We've had many embankments and such collapse as the water levels rose because the surface currents undercut places that were not designed to ever be above the water level.

Mother Nature continues to show the limits of our knowledge.
 
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Tugger
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 5:35 pm

I don't think people are understanding the scale of the structures:

There is definitely re-bar in the spillway structure:
https://wattsupwiththat.files.wordpress ... hicoer.jpg

The damage being caused by the main spillway to the hillside is a long way from the dam.

The big issue is that the emergency spillway really does have some engineering issues, the engineering done for when it was constructed was insufficient to its final requirements. It should have been upgraded when the standards were adjusted to more real world levels based on other failures/problems that had been witnessed.

Image
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jetwet1
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 5:39 pm

rfields5421 wrote:

Read up on when the overflow spillways were used at Boulder / Hoover Dam. That dam always carries a risk of overtopping. A sufficient flood could do that if it put enough water into Lake Mead. An overtopped dam will fail catastrophically if the flow is not stopped quickly.


With the current situations at Lakes Powell and Mead getting those to overflow would mean we are in serious trouble anyways, but yes, the thing is, when in1983, when both dams had to use their emergency spill ways damage was found at both sites (at Glen Canyon holes were found in 3ft thick concrete, now, while part of that is down to design (bends in the intakes of the dams overflows compared to an almost straight run at Oroville) shouldn't it have given pause to all involved to look at their dams?

As a note, my brother in law and his family live next to the American river in Cow Town, a couple of weeks ago the river was up to their patio, meaning it was about 10ft higher than normal, not good.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 8:36 pm

rfields5421 wrote:
What is not subject to debate is that without this dam, the city of Oroville would have been destroyed by the flooding which filled the lake to near capacity.

Without the dam there would have been levies.

rfields5421 wrote:
No, I do not think this an engineering failure. The systems worked as planned/ designed.
The main water discharge system failed and the backup failed; we were within a whisker of a major disaster (if you don't count the evacuation of 188,000 people a major disaster); at the current time we are far from out of danger. The snow hasn't begun to melt yet.

rfields5421 wrote:
Even if the emergency spillway had "lost crest control" it would have done its designed job. It is not designed to prevent all damage to the mountainside nor to the downstream area. It is an EMERGENCY spillway to only be used in an emergency to protect the main dam from damage.

I don't think you fully understand the carnage that would have ensued if the top 30 feet of water from the entire lake had been dumped into the Feather river within a few hours. You said "The volumes of water and forces it creates are beyond the comprehension of most people." I occurs to me that "loss of crest control" is beyond your understanding. On top of that we would have had a repeat when the snow melted; it would have happened again because such a washout could not have been repaired during the winter months.

rfields5421 wrote:
There was obviously other water traveling down the embankment, and that non-spillway contained water could be the source of the initial failure.

If there was water flowing "down the embankment" outside the spillway that would constitute a third failure.

rfields5421 wrote:
Despite the 'emergency' the main point is the system functioned mostly correctly. A completely uncontrolled flood was averted.
I notice that you put emergency in quotes which indicates that you don't quite understand what happened at Orville. "loss of crest control" could have flooded a half a million homes and businesses. And we were very close to "loss of crest control".

Tugger wrote:
There is definitely re-bar in the spillway structure:
https://wattsupwiththat.files.wordpress ... hicoer.jpg

What I see is trace amounts of undersized rebar in the floor of the spillway. There are evidences of the anchor points into the underlying rock and it seems that the sidewalls and their foundation had appropriate amounts of reinforcement, they held up so far.
 
rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 8:55 pm

There should be levees anyway on the river below the dam. I've seen many levees over topped and fail in Arkansas, Mississippi, Louisiana, Missouri, Oklahoma and Texas in my lifetime.
 
mham001
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 9:02 pm

salttee wrote:
I don't see any sign of rebar, that looks like a design problem to me; if there were rebar it would have been evident in the picture I posted. If the concrete for the spillway had been poured with rebar in it, it wouldn't have failed. But if not a design fault, it was an infrastructure problem anyway. I can't understand how someone could say it was neither..


It had wire mesh. Some practices used today do not require anything on a flat surface.

salttee wrote:
What I see is trace amounts of undersized rebar in the floor of the spillway. There are evidences of the anchor points into the underlying rock and it seems that the sidewalls and their foundation had appropriate amounts of reinforcement, they held up so far.


That is all that it should need for the forces it was designed for. It is not meant to hold up because they didn't repair a pothole or breach and the water tore it open.


WIederling wrote:
rfields5421 wrote:
The current issues with Oroville only demonstrates a problem with ALL dams worldwide.

Spillways and emergency relief channels are designed to handle the biggest event the designers can imagine. By their very nature they cannot be tested to maximum design stress. There are literally a couple thousand spillways and emergency relief channels that have never carried overflow water. Every one of them is an 'untested' design. Each of them might suffer similar failures.


Baloney and neocon hogwash.

What you see is caused by pronounced maintainance shortcomings. Sorry, no money. we need the cash for profits.
https://en.wikipedia.org/wiki/Oroville_ ... nspections
https://en.wikipedia.org/wiki/2017_Oroville_Dam_crisis

Nothing unexpected or "fought valiantly and lost" about it.


Oh crap, there you go again. Where do you get this 'neocon' crap? Profits? Who? The state? A more accurate statement might be "Sorry, no money, we need the cash for the legal protection of and full services to illegals." And whatever else the State of California, under one-party super-majority rule, wastes money on.

Apparently, there was $395 million allocated by the feds but nobody seems to know where it went. Such is the state of affairs in our state government.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 9:07 pm

mham001 wrote:
It had wire mesh.

That's a chain link fence you're seeing.

mham001 wrote:
Some practices used today do not require anything on a flat surface.

Yea, I'm dimly aware of a newer technology that uses fibers instead of or along with rebar. But the spillway was poured on 1968.

Yikes!

I just remembered that I used that fibered concrete stuff myself for a garage I built in Sacramento about 20 years ago.
I built the forms and ordered the truckload of muck.
Last edited by salttee on Wed Feb 15, 2017 9:29 pm, edited 1 time in total.
 
mham001
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 9:11 pm

salttee wrote:
mham001 wrote:
It had wire mesh.

That's a chain link fence you're seeing..


You are right.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 9:23 pm

delete please
 
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Tugger
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 9:42 pm

Remember the scale question. We haven't seen much to put the scale into perspective. The sidewalls are something like 18' high. and the spillway is around 180' wide:
Image
(Yes the hole/damage is much larger now, I am just using the pic since it has a person in it to help with scale.)

So what looks small in the picture may not be easily representative of the actual size. Quite honestly I am wondering how thick the re-bar really is since we can see it (in the pic I linked above) and how it looks when compared to the dimensions of the surrounding structure. If anyone here has the actual spec that would be helpful. This is the best I have found so far:
http://www.water.ca.gov/orovillerelicen ... it%20A.pdf
(Pg A-6)

Tugg
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 
mham001
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Re: Oroville Dam Might Not Make It (Northern California)

Wed Feb 15, 2017 9:58 pm

I liked this one.

Image
 
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Aesma
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 12:18 am

From what I'm used to see and a bit of research, most French dams have spillways that are part of the dam structure itself. I would expect those to not be a flimsy concrete slab (or here non continuous slabs it seems) but a structure that couldn't fail in the way this one is.

What is the reason to not go that route ?
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 12:32 am

Are the French dams concrete or earthen? Many high dams such as this one are not built from solid concrete. There is a tremendous issue with cooling the concrete in a massive dam. It can be done, but is expensive and takes a lot of time.

Many dams in the US include not only the primary dam over the main stream, but several small dikes over low points in the area to ensure safety for a specific water level.

This dam is almost 300 meters high and includes a huge underground power generation station.

An external spillway which empties into the river below the powerhouse likely protects that from back flow flooding.

One thing I've learned while volunteering with Corps of Engineers projects is that every dam project has unique elements based on the local conditions. Some similarities exist of course, but there are always differences.

Water coming over spillways as high as this dam creates incredible pressures/ forces. As mentioned above - when water flowed through the spillway tunnels at Glen Canyon Dam the water eroded away three foot (1 meter) thick concrete walls of the tunnels and started carving away the bedrock the tunnel was drilled through.

There is a very interesting Wikipedia article on different types of spillways and why certain types are better at some locations.

One thing I have been told is that if possible the spillway should not be located on the main dam structure. That way of the spillway fails, it does not threaten the main dam.
 
coolian2
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 7:10 am

wingman wrote:
It pains me somewhat to say it but Trump is right about our infrastructure problem.

Did he have a plan to fix it?
Q300/ATR72-600/737-200/-300/-400/-700/-800/A320/767-200/-300/757-200/777-300ER/
747-200/-300/-400/ER/A340-300/A380-800/MD-83/CRJ-700/-900
 
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seahawk
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 8:14 am

Aesma wrote:
From what I'm used to see and a bit of research, most French dams have spillways that are part of the dam structure itself. I would expect those to not be a flimsy concrete slab (or here non continuous slabs it seems) but a structure that couldn't fail in the way this one is.

What is the reason to not go that route ?


The only interesting difference to European designs seems be in the design of the overflow. In Europe you need to show that the emergency overflow alone will handle an event occurring every 500/1000 years, without using any other outlets, like the ground outlet. You must also show that you can handle the theoretical maximum flow with the biggest of your normal operational outlets (usually the ground outlet) not functional. (5000/10000 year event)
 
WIederling
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 11:35 am

"The only interesting difference to European designs seems be in the design of the overflow."

Looking at the pictures the apparent problems are not based in design shortcomings but in lack of maintainance.
( and potentially carelessness during building.) The spillway is covered with rather thin slabs of concrete.
poured on the insufficiently prepared inhomogenous earth/rock foundation.
The subsoil settled unevenly and/or was partly washed out over time. Nobody looked (carefully enough) or cared ..

How often is/was this spillway actually in use ?
Murphy is an optimist
 
rfields5421
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 2:13 pm

I can't find an exact answer, but the Oroville Spillway has carried large volumes of water many times. I can find about a dozen photos on the web from different years with water on the spillway.

The Popular Science website has a very impressive photo from 1972 of the water hitting the bottom of the spillway.

The spillway has definitely carried a lot of water safely in the past.

As I mentioned above - there was a repair done to some cracks in the spillway a few years ago. I don't think California has had enough rain/ snowmelt since those repairs to put much, if any, water down the spillway.
 
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casinterest
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 3:11 pm

rfields5421 wrote:
I can't find an exact answer, but the Oroville Spillway has carried large volumes of water many times. I can find about a dozen photos on the web from different years with water on the spillway.

The Popular Science website has a very impressive photo from 1972 of the water hitting the bottom of the spillway.

The spillway has definitely carried a lot of water safely in the past.

As I mentioned above - there was a repair done to some cracks in the spillway a few years ago. I don't think California has had enough rain/ snowmelt since those repairs to put much, if any, water down the spillway.



Google shows the Spillway in operation from over a year ago.

https://www.google.com/maps/place/Orovi ... 121.556359
Older than I just was ,and younger than I will soo be.
 
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Aesma
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 3:27 pm

rfields5421 wrote:
Are the French dams concrete or earthen? Many high dams such as this one are not built from solid concrete. There is a tremendous issue with cooling the concrete in a massive dam. It can be done, but is expensive and takes a lot of time.


Both types exist but I was mostly thinking of concrete dams. I have heard of this technique of cooling the concrete but I don't know much about it, would you believe I work for a company that pours tons of the stuff everyday ? Even surnamed "concretor". But I'm in IT...
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
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seahawk
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 3:50 pm

casinterest wrote:
rfields5421 wrote:
I can't find an exact answer, but the Oroville Spillway has carried large volumes of water many times. I can find about a dozen photos on the web from different years with water on the spillway.

The Popular Science website has a very impressive photo from 1972 of the water hitting the bottom of the spillway.

The spillway has definitely carried a lot of water safely in the past.

As I mentioned above - there was a repair done to some cracks in the spillway a few years ago. I don't think California has had enough rain/ snowmelt since those repairs to put much, if any, water down the spillway.



Google shows the Spillway in operation from over a year ago.

https://www.google.com/maps/place/Orovi ... 121.556359


That looks a bit unusual. The river and the follow up dam to fill the Thermalito bays do not indicate any flooding, yet the overflow is in operation. Normally the ground outlet should easily be enough to use.
 
WIederling
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 5:29 pm

the mandatory evacuation has been mooted:
http://www.accuweather.com/en/weather-n ... m/70000833

impressive images from the defect.
Image
Murphy is an optimist
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 6:35 pm

WIederling wrote:
the mandatory evacuation has been mooted:
http://www.accuweather.com/en/weather-n ... m/70000833

impressive images from the defect.
Image

The story you linked to is old news, but the picture is startling. It looks like the spillway has suffered a collapse of its left sidewall.
 
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casinterest
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 8:05 pm

salttee wrote:
WIederling wrote:
the mandatory evacuation has been mooted:
http://www.accuweather.com/en/weather-n ... m/70000833

impressive images from the defect.
Image

The story you linked to is old news, but the picture is startling. It looks like the spillway has suffered a collapse of its left sidewall.


Actually no. The sidewall is intact.
The water went under the wall. The bottom of the spillway is what went bad, and I would imagine this was due to a crack and possibly a sinkhole below the center.

https://www.google.com/search?q=orovill ... eiuDsFOweM:


I think at then end of the day, the awesome weight of what was going over that portion, caused a defective/weak portion of the spillway to be exploited.
Older than I just was ,and younger than I will soo be.
 
salttee
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 8:44 pm

casinterest wrote:
The sidewall is intact. The water went under the wall.

The wall won't be intact for long, the water is digging a new channel on the left side. (Edit: if you blow the picture up you can see that the wall is already gone)
You can use Google Earth to compare how it was before the event. A huge amount of earth has already been dug out on the side of the spillway.

This might be fortuitous, it could save the lower portion of the spillway which I considered doomed until now.
On the other hand.................
 
flipdewaf
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Re: Oroville Dam Might Not Make It (Northern California)

Thu Feb 16, 2017 9:21 pm

WIederling wrote:
the mandatory evacuation has been mooted:
http://www.accuweather.com/en/weather-n ... m/70000833

impressive images from the defect.
Image

This may be a stupid question but I see that the spillway is broken from how it was intended to be but in what way does the damage limit it's operation? As far as I can tell the water is still going broadly where the water is supposed to go.

Fred
Image

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