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Main Forums => The Roundtable => Topic started by: Hawkmoon on February 12, 2017, 12:05:30 PM
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Ben may know about this. The Lake Oroville Reservoir in California has risen to record levels, and the bypass spillway has failed and is eroding due to the amount of water spilling out of the lake.
https://www.rt.com/usa/377016-oroville-dam-emergency-salmon/
So the DWR (Department of Water Resources?) and the Army Corps of Engineers say the dam is safe and there's "no risk" to the public:
The DWR says the public is not currently at risk, as the US Army Corps of Engineers has said the main dam is sound.
"None of this emergency we have now is affecting the integrity of the dam itself," said Bill Croyle, deputy director of the DWR. "I think that’s important ... there’s no risk to the public."
BUT ...
Nevertheless, authorities have told residents near the Feather River to be prepared for a potential emergency evacuation, Reuters reported.
So, there's no risk ... but be prepared to evacuate anyway.
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I think you are being unfair Hawk. That's a pretty accurate statement.
There is no risk right now. But the Army Corps of Engineers is going to try and fix it, so you should be prepared to evacuate.
That's just prudent.
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Ben may know about this.
Hadn't heard it, but we have spillways overflowing all over the state right now. The storms have hit in such a way that the ground is now supersatured, and the storm from a couple of days ago was really warm, so it melted a bunch of the lower snowpack. We've got about a week before the next major rain is supposed to hit, which wil lbe good for the ground.
We've got an intermittent river that runs through town for whenever they open the dam at the local reservoir (which has been a pond for the last five years). There has been practically no water running through it for the last few years, and apparently that created a great place for the homeless. I drove over the bridge going into town after the second big storm of the season, and there were probably thirty cop, fire, and other city/county vehicles there with people evacuating homeless and their stuff out of the nearly overflowing river and surrounding area.
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I think you are being unfair Hawk. That's a pretty accurate statement.
There is no risk right now. But the Army Corps of Engineers is going to try and fix it, so you should be prepared to evacuate.
That's just prudent.
I'm not arguing that preparing to evacuate isn't prudent -- it obviously is. What I'm pointing out is the idiocy of acknowledging there's enough risk that preparing to evacuate is prudent ... while saying there's no risk.
As for the .gov trying to repair the damage ... http://www.denverpost.com/2015/08/06/animas-river-fouled-by-1-million-gallons-of-contaminated-mine-water/
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And the water level has now risen high enough to be flowing over the emergency spillway.
http://www.sacbee.com/news/local/article132154774.html
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"This is an evacuation order.
Immediate evacuation from the low levels of Oroville and areas downstream is ordered.
A hazardous situation is developing with the Oroville Dam auxiliary spillway. Operation of the auxiliary spillway has lead to severe erosion that could lead to a failure of the structure. Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville. In response to this developing situation, DWR is increasing water releases to 100,000 cubic feet per second.
Immediate evacuation from the low levels of Oroville and areas downstream is ordered.
This in NOT A Drill. This in NOT A Drill. This in NOT A Drill."
http://www.sacbee.com/news/state/california/water-and-drought/article132332499.html
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Nope -- no risk at all.
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"This is an evacuation order.
Immediate evacuation from the low levels of Oroville and areas downstream is ordered.
A hazardous situation is developing with the Oroville Dam auxiliary spillway. Operation of the auxiliary spillway has lead to severe erosion that could lead to a failure of the structure. Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville. In response to this developing situation, DWR is increasing water releases to 100,000 cubic feet per second.
Immediate evacuation from the low levels of Oroville and areas downstream is ordered.
This in NOT A Drill. This in NOT A Drill. This in NOT A Drill."
http://www.sacbee.com/news/state/california/water-and-drought/article132332499.html
Aaaand halfway down the page is why I don't let me vehicles get much below half a tank. Everyone is stopping for gas on their way out of town. Either they're on empty or they're incredibly stupid and stopping for gas in town with a 1/4 tank or more instead of driving 20-30 miles first.
http://twitchy.com/gregp-3534/2017/02/12/prayers-evacuations-ordered-over-possible-failure-of-oroville-dam-in-calif/
Also it should be noted that the dam is not collapsing, the spillways are. Still dangerous, but not as dangerous as the whole dang lake heading to town.
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Also it should be noted that the dam is not collapsing, the spillways are. Still dangerous, but not as dangerous as the whole dang lake heading to town.
The damage to the main spillway is a bit downstream from the dam, but my understanding is that the so-called emergency spillway is eroding right at the lip that forms the edge of the reservoir. If that lets go, the dam will have failed. That seems to be why they started pushing more water over the damaged main spillway -- they needed to lower the water level to below the level of the emergency spillway.
Falling depths do not mean the areas below the dam are safe. The emergency spillway is essentially part of the dam and the concern is that it will fail, something that could happen even if water stops flowing over its top.
It's certainly a good thing there was no risk as of noon on Sunday.
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"Aaaand halfway down the page is why I don't let me vehicles get much below half a tank."
Yep. In years past I was rigorous about filling up before I hit 1/4 tank.
Then, when my commute was so short, I got out of that habit.
Well, I was heading out of town on vacation, and I was intending on getting gas on my way out of town. The night before I left the Derecho hit Northern Virginia and knocked power out just about everywhere, and I didn't have enough gas to get beyond the power outage zone.
Fortunately I was able to finally find an open station fairly near my house, but I learned my lesson.
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Somebody help me with this one. Is this Trump's fault or Bush's?
Logic would/should dictate that Trump hasn't been in office long enough to damage California's infrastructure by deporting all their cheap, illegal immigrant labor there by making it Bush's fault. But as we have seen so much of here lately logic and liberal are mutually exclusive.
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Am I correct in that this is the first time the reservoir has been full since it's completion in '68 or 9? This spillways failed the first time they were needed?
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Interesting juxtaposition...
People have been screaming that they want to succeed from the United States because of Trump.
Apparently some of the same people are screaming that they want the Trump government to declare California a disaster area because... Money.
If they actually do pull out of the United States they'd better plant their own crop of magical money trees and hope that they'll be ready for harvest soon.
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The damage to the main spillway is a bit downstream from the dam, but my understanding is that the so-called emergency spillway is eroding right at the lip that forms the edge of the reservoir. If that lets go, the dam will have failed. That seems to be why they started pushing more water over the damaged main spillway -- they needed to lower the water level to below the level of the emergency spillway.
It's certainly a good thing there was no risk as of noon on Sunday.
This is really scary sheet. I read through some of the comments on an article about this and there is a name for this type of potential failure of the earthen dam. Apparently erosion from spillways at the bottom of the dam can undermine the integrity of the main earthen structure. One engineer posted was "pants on fire" telling people to get far away if you are anywhere downstream. He indicated the best case is that they just don'y know whether the main structure will be compromised. Not very comforting.
Erosion of downstream toe: The toe of the dam at the downstream side may be eroded due to i) heavy cross-current from spillway buckets, or ii) tail water. When the toe of downstream is eroded, it will lead to failure of dam. This can be prevented by providing a downstream slope pitching or a riprap up to a height above the tail water depth Also, the side wall of the spillway should have sufficient height and length to prevent possibility of cross flow towards the earth embankment.
http://theconstructor.org/water-resources/failure-of-earthfill-dams/2287/
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I wikipedia searched for a list of earthen dam failures, and by dam it's a big list.
Most have no to low fatality counts.
Then there's the 1889 dam collapse in Johnsontown, PA that killed over 2,000 people.
But the winner? A dam in China in 1975... estimated 171,000 dead.
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The cops probably had it blocked off, but if I lived in Oroville, I'd be inclined to evacuate in the opposite direction of the gridlock. That is, up HWY 162 towards the lake. Five miles out of town and you're already a couple hundred feet higher than the lake surface, let alone the spillways.
I understand with the sheer numbers why they had them head to the lowlands where people can spread out, but if you're in a traffic jam trying to get to HWY99 and the dam breaks, you're kinda screwed.
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Yep. In years past I was rigorous about filling up before I hit 1/4 tank.
Then, when my commute was so short, I got out of that habit.
If you've got a lawn mower or anything else that runs on gas, it's not hard to justify keeping a 5 gallon can in the garage, dumping it into the tank quarterly and refilling. Then, even if you evac on a full tank, tossing that in the trunk will extend your total range before you have to buy gas significantly.
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If you've got a lawn mower or anything else that runs on gas, it's not hard to justify keeping a 5 gallon can in the garage, dumping it into the tank quarterly and refilling. Then, even if you evac on a full tank, tossing that in the trunk will extend your total range before you have to buy gas significantly.
That's the problem. I don't. I don't have any gasoline powered devices.
Friend of mine lives in pretty rural Northern Virginia, and has been hit with power outages lasting days on more than a few occasions. He's got a generator, and does exactly that kind of rotation, only with about 50 gallons of gasoline.
"before you have to buy gas significantly."
But, what if you have to buy gas insignificantly? What then?
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That's the problem. I don't. I don't have any gasoline powered devices.
Still, it's $20 for a can, and an extra $10 at some point to fill it up the first time. After that, just dump the gas in the tank and toss the can in the trunk when you do some monthly-to-quarterly errand.
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It's a lot easier just to keep my tank above a quarter full, and better yet, above half full.
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It's not doublespeak to say there is no risk at this current time, but prepare for worst case scenario. Best of luck to the engineers involved.
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It's a lot easier just to keep my tank above a quarter full, and better yet, above half full.
But then due to memory effect you'll get reduced overall capacity.
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Saw an article that the emergency spillway was "rated" to take a couple of hundred thousand cubic feet per second.
It's now showing signs of failure with a flow rate of 12,000 - 14,000 cubic feet per second.
Authorities were WARNED about the earthen emergency spillway back in 2005 . . . and did NOTHING.
Can some of these bureaucrats be jailed . . . please? Preferably in the lowlands just downstream from the dam? :mad:
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Saw an article that the emergency spillway was "rated" to take a couple of hundred thousand cubic feet per second.
The bit that only gets used if something else goes horribly wrong. It's like having your fire extinguishers made by the lowest bidder, to a bad spec.
Authorities were WARNED about the earthen emergency spillway back in 2005 . . . and did NOTHING.
Can some of these bureaucrats be jailed . . . please?
Of course not. Holding government accountable? That's unthinkable.
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I have been religious about filling up when I hit 1/2 a tank since I was in the Army, and had to put $900 worth of diesel into 10 HWMMV's on a REFORGER, when my Company Commander refused to send the Fuel Tanker, that I CAPTURED from VII Corps, to come refuel my platoon.
Then the *expletive deleted*er threatened to Article 15 me for asking for reimbursement after we got back.
Good thing I had 32 *expletive deleted*ing witnesses and a receipt...
[ar15] [ar15] [ar15] [ar15] [ar15]
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It's not doublespeak to say there is no risk at this current time, but prepare for worst case scenario. Best of luck to the engineers involved.
It's doublespeak when the gov says, don'tchaknow?
Of course, any of us would make similar statements, but that's different.
Chris
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Am I correct in that this is the first time the reservoir has been full since it's completion in '68 or 9? This spillways failed the first time they were needed?
The dam and reservoir are fifty years old. This is the first time the water level has risen above the top of the emergency spillway. Twelve YEARS ago concerns were raised about the adequacy of the emergency spillway, and both state and federal agencies said it was safe. In fact, the Army Corps of Engineers said it was good for 350,000 cfs of flow. At the peak on this incident, it was flowing about 12,000 cfs and they had to dump more water through the primary spillway because the emergency spillway was in danger of failing.
http://www.mercurynews.com/2017/02/12/oroville-dam-feds-and-state-officials-ignored-warnings-12-years-ago/
Let's see -- twelve years ago, who was President? YES! IT'S BUSH'S FAULT.
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But then due to memory effect you'll get reduced overall capacity.
No, due to memory effect I'll end up with a 4 year old can of stale maple syrup gasoline in the basement.
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In fact, the Army Corps of Engineers said it was good for 350,000 cfs of flow.
There you go; CoE isn't supposed to be in the business of making stuff safe beyond the end of the current conflict. Put them back to building fortifications and finding better ways to blow up our enemies' dams.
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No, due to memory effect I'll end up with a 4 year old can of stale maple syrup gasoline in the basement.
Sell it on eBay as vintage fuel.
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https://youtu.be/_6AvEZO34xI
Note the name of the engineer involved. The dam burst the day after he visited it and said everything was OK.
More examples abound:
https://youtu.be/cdOGPBnfoKE
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If it's not doublespeak, it's outright incompetence.
Officials defended their decision to issue the hasty order to abandon homes downstream from the nation's tallest dam, about 150 miles northeast of San Francisco. They said it was necessary for public safety after engineers spotted a hole in an emergency spillway, which they feared could have failed within an hour.
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The acting head of the state's Department of Water Resources said he did not know if anything had gone wrong and was unaware of a 2005 report that recommended reinforcing the earthen emergency spillway with concrete for just such an event. The spillway had never been used in the dam's nearly 50 years of operation, and it was not near capacity when it began to fail.
"I'm not sure anything went wrong," Bill Croyle said. "This was a new, never-having-happened-before event."
Let's see ... an "emergency" spillway that a decade ago your agency said could handle 350,000 cfs was flowing maybe 12,000 cfs, had a hole in it, and was within a hour of failing ... and you're not sure anything went wrong? You're in the wrong job.
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Not knowing at all what happened in this case, but sometimes defects show up when a system is stressed that are not apparent to any kind of non-invasive inspection.
And, sometimes, there are no defects in a system, but a seemingly minor outside change stresses the system in ways that were never expected.
It will be interesting to see the forensic report on the cause of the failure.
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I've been digging around a little bit and I think I clarified in my own mind what's going on.
1. It appears that the weakest point in dams is usually at the sides, where it "attaches" to the surrounding geology.
2. Typically, this surrounding geology is earth rather than solid rock. Essentially, not to be flip about it, you have a concrete dam surrounded by two earthen dams.
3. In this case, it is not the emergency spillway which is the immediate problem, it's the regular concrete-lined spillway which broke, resulting in the "crater." I think this is a point of confusion in some of these posts.
4, Water rushing into this crater and roiling around in there is washing away the earth and rocks around the sides of the dam, thus possibly weakening it. I think I've seen some rather large boulders being thrown out by the water at that point.
5. The "emergency" spillway is not concrete lined.
6. If they have to go to the emergency spillway (earth-lined) there are at least three dangers involved.
a. this will increase the erosion of the earthen "sidewalls" of the dam, further weakening it
b. the larger amount of water heading down will flood the levee below the dam, which also protects a fish hatchery there, where "millions" of hatchlings will die
c. the larger amount of water heading down will also overflow other levees further downstream which protect those populated areas and infrastructure, hence the evacuations --let alone if the whole thing lets go because of weakening that side of the dam
7. They are dumping material into the "crater" in the concrete spillway to help in slowing the erosion under it.
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It will be interesting to see the forensic report on the cause of the failure.
I suspect it will be one or more, or all, of the following:
1. Somebody got stingy with the cement and aggregate mixture applied during construction of the spillway.
2. Improper compaction of the substrate material under that portion of the concrete of the regular spillway.
3. An unseen "pipeline" from the storage side of the dam weakened the substrate under the concrete at that point. Not that the water is that deep at the point of failure, but the dam itself is 770 feet high. The pressure of water at that depth would be about 360 psi*, and varies linearly with depth. A "pipeline" in terms of damming water is a sneaky little tiny leak which gradually gets bigger and bigger.
This is not intended to be "authoritative," but that's the way I understand the situation as of 13-14 February.
Terry, 230RN
* Quickly obtained from here:
http://www.calctool.org/CALC/other/games/depth_press
I'm not sure if that's for sea or fresh water, but it gives an idea of the magnitudes involved.
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Terry -
You're behind the curve. They already allowed water to flow over the emergency spillway. That water did erode the hillside below the spillway, completely washing out the road that ran below it. Then the lip of the spillway began to erode, and a hole appeared. That's what the "experts" decided was within an hour of failing. That was with water flows of between 6,000 and 12,000 cfs over the emergency spillway -- which a decade ago they said was capable of handing 350,000 cfs.
So when the emergency spillway proved to be a liability rather than an asset, they then started allowing more water to flow down the primary spillway, even though it is damaged. They ramped it up from around 80,000 cfs to over 100,000 cfs, managing to draw down the water level to below the lip of the emergency spillway. At last report, though, they want/need to draw it down to at least fifty feet below the emergency spillway elevation to allow room for the next anticipated storm flow to collect.
So, basically, the emergency spillway (which had never been used in the fifty years the dam has been in operation) was completely inadequate, useless, and dangerous.
So, now that California has a huge problem, they want Trump to authorize passing the cost of the repairs on to the rest of us.
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OK, thanks. I was reviewing from vids I saw from earlier in the event. I stand corrected.
Me: "...I think I clarified in my own mind..." I also removed the ??? from it before posting, and added that it was not meant to be authoritative.
Much appreciated, Hawkmoon.
Terry, 230RN
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I guess that the lowest bidder who built it didn't use structural bread dough...
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So, now that California has a huge problem, they want Trump to authorize passing the cost of the repairs on to the rest of us.
I wonder how the #Calexit crowd feels about that.
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