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Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
http://www.msn.com/en-us/news/us/gaping-hole-in-or...

Quote:

Erosion has created a 300-foot-deep hole in the concrete spillway of Oroville Dam and state officials say it will continue grow.
State engineers on Wednesday cautiously released water from Lake Oroville's damaged spillway as the reservoir level climbed amid a soaking of rain.

Situated in the western foothills of the Sierra, Lake Oroville is the second-largest manmade reservoir in California after Shasta....

Member Spartan: Stage storage flow data here for those interested:
https://cdec.water.ca.gov/cgi-progs/queryF?s=ORO

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Saw that, wondered why they weren't already dumping concrete into it, actually.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

If the hole is already 300 ft deep, how can the dam not be at risk?

Mike Halloran
Pembroke Pines, FL, USA

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Man that's splitting hairs! It's the dirt next to the damn face that makes up the reservoir.

Somethings also odd. I can't see how you'd get a 300ft DEEP hole from that. Is that even possible?

I would not want to be living in Orville at the moment.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I don't see how it is "splitting hairs" to point out that the spillway is a separate structure from the earthfill dam wall. If the downstream face of the dam had a hole like that, look out all points downstream.

They probably mean the hole is 300 ft LONG, but you never know what to believe in a newspaper article.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I'd say 300ft wide is more like it.



RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

While not an accurate news source I saw this on imgur this morning: http://imgur.com/gallery/xHfxx

Apparently the current solution is to try to use the spillway at reduced capacity:

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

So total collapse of the spillway surface off the edge and the water is now going around the spillway - probably further taking out the underlying soil beneath the spillway slab.
Probably will take the whole thing down to the bottom before too long.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I guess they figure that wrecking the damaged spillway is better than utilizing the emergency spillway adjacent to the this which would just run down the side of the slope anyways.

Another picture at a higher flow rate:



Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Those baffle blocks seem to be working well... the water is going pretty damn slow once it hits the end of that spillway wink

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I notice the color of the water downstream of the hole; brown.
I.e., there's dirt in it, that didn't come over the top of the spillway.
This bodes ill.

Mike Halloran
Pembroke Pines, FL, USA

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
The issue to me is obvious seepage under or through the dam above that undermined the spillway.

I would be far more concerned with the stability of the dam.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Seeing it run down NEXT to the spillway is a whole nother layer of 'oh damn'. Pretty chilling.

Mike, good eye.

Isn't it great too, how they are feverishly working to make the emergency spillway functional by removing
trees etc. I guess you always have lots of time to get emergency systems operational
during EMERGENCIES.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

<inexpert opinion>

I hope they are not removing entire trees.

I'd guess that severely pruning the tops but not killing the tree, turning them into giant Bonsai, and leaving the roots intact, might be better for stabilizing the soil.

</inexpert...>

Mike Halloran
Pembroke Pines, FL, USA

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Yea, I'd say it's pretty unlikely that this will weaken or even damage the dam itself. In the image #6 it looks like one of those 'sink-holes' you see in the news all the time.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The sinkholes that you see in the news are often associated with a substantial water flow that you don't see.


Mike Halloran
Pembroke Pines, FL, USA

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Hmmm -- A picture ostensibly from 2013 -- looks like they're checking out that area of the spillway.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

... and it sure looks like what they're investigating is water coming up through the spillway paving.

Where do you suppose such water might come from?

Mike Halloran
Pembroke Pines, FL, USA

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Perhaps from "a substantial water flow that you don't see."

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
According to the article posted by mintjulip above, the spillway is not paved and has not been used since 1968. It is an overflow spillway away from the dam proper. Hopefully the abutment of the dam whereby his spillway is located is solid rock.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

btw, measurement in Google Earth puts the spillway width at about 160 ft, so deep probably means deep.
The hole is considerably larger now

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

A TV Channel Facebook Vid. (Just hit Not Now to avoid)


After watching a long movie of a helli cruising the spillway I see now that the water really does run horizontally for a couple of hundred yards before sloping down. So indeed it doesn't look like the dam's left natural structure is ever going to be in jeopardy. They can let it eat the entire mountain from the Hole down with out affecting the structure. And that's likely exactly what they're going to do rather than let the emergency spillway, which is merely a concrete lip go into operation.

You can see the water has pretty much stopped being muddy and only bedrock is remaining.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As an observation on the photo above, there's a lot of water seeping through the drains into the tailrace from the surrounding land. Ground conditions must be very wet there.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It's been very, very, rainy here in California Scotty for weeks - really months - now.

The river in the middle of our town hits minor flooding at 16.7 feet and major flooding at 21 feet. Tuesday it was at 23 feet.

Normal is about 24 inches and we have 37.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As of Monday (02/06/2017) the year-to-date rainfall totals for Los Angeles (which is still technically considered to be suffering drought conditions) was nearly 15 1/2 inches, already more than the normal yearly total, and it has been raining most of yesterday and more is predicted today as well as another storm possible by the end of next week. I don't think we'll break the yearly rainfall record for SoCal, which is close to 37 inches, but whatever we end-up with, it should take the edge off out local drought conditions. I realize that Northern California may break some records, and that's great because much of our municipal water comes from there via the state aqueduct system. This should also help the farmers in the Central Valley.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Perhaps one of our civil engineering hydraulics experts can comment on the drainage systems there. The side walls have some form of drainage, with the many outlets for that drain system spewing water. Could they be connected some how to a drain system under the slab? No way could one expect that slab system not to leak, so a drainage system under it would be mandatory or downstream the uplift would cause the slab to fail.. But where would it discharge? To to those side walls? Looking at the close up photo it appears that the slab is full of cracks, no reinforcing, and may wall have started an undermining process well up hill from the right side(in photo). I'd sure like to see a cross section of the slab details.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Today, Saturday 11 February, the primary (floodgate-controlled, 160 foot wide, concrete-lined) spillway that failed (see photo's above) has washed out another few hundred feet sideways and down the hillside.
Lake level is now up even higher at 900 foot (+) and has begun washing over the emergency spillway this morning.
The primary spillway is separated from the earth-fill dam by a raised hillside and some bedrock, but the erosion from the primary spillway concrete failure is washing into that hillside - Don't know how many hundred feet are left of "original" rock and hillside between the spillway and the earth dam itself.
The emergency spillway is of course not regulated at all, so it will continue flowing as long as lake level is above emergency spillway height.
The emergency spillway is beside the primary spillway, but looks like they are separated by a few hundred feet of of (what used to be) hillside and trees. SO water over the emergency spillway could rejoin the washout from theprimary spillway.
Don't know if they (California Water Resources Board ?) are going to close or throttle the primary spillway once the emergency spillway starts flooding. Seems like they would not want to throttle flow in the primary spillway, but, the primary is waashing hillside away.
So what is better?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

With the damage to the spillway, I'd be very concerned about the dam... it all starts with a trickle...

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)



Image shows the emergency spillway (with concrete lip now being overwashed and flowing over the dam road below), the controlled spillway entrance channel, then the raised hillside between the normal spillway and the dam itself, then the earthen dam,

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Overspilling at 12,000cf/s now. I hope that little lip at the bottom is up to the task of stopping the
initial K.E. of the vertical water.

I was given a half-day tour of the Oroville power plant when I was in my 20s. Of the many technical
tours I've been lucky enough to have that was one of the most memorable. Fascinating. The whole plant
is underground.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Wow! That's a hole and a half.

BTW, I still remember seeing the construction of Oroville Dam (which ran from 1961-1968) when I was a kid. My grandparents lived in nearby Chico and had a cabin at Lake Madrone in the forested hills above Lake Oroville. According to my dad, my first trip to the cabin (and thus past the construction site) was in the summer of 1963. just before I turned 5. My family, coming up from Fresno, made 2 to 3 trips to the cabin each year until my grandparents sold it in about 1974. On every trip past the dam while it was under construction, we would stop for a while at a viewpoint and my dad would explain what was going on. I didn't understand much, but I was fascinated. My younger brother had no interest in it.

Fred

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

And, your little brother is now an attorney and makes 7 figures?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

And here is the link JAE is talking about but that actually IS the link.
Back side of emergency overflow

And, yes it looks like one frozen image frame as the water looks entirely static but if you
full-screen it you will see moving cars and the foreground tree dancing around.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Thanks, itsmoked. I seemed to have grabbed the wrong one.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

That is some great footage! Thanks.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

itsmoked…

Nope. He's an electronics tech with a local school district and makes less than 2/3 what I make. He's actually proud to be "doing this well" and only having to work a fraction as hard as I do.

My brother talked about becoming an electrical engineer, but dropped out of college because taking two 4-units classes (Calculus and Physics) at the local community college, and getting A's in both, while not having a job was "too much work." At the time, I was taking 18 units/semester in civil engineering at the local university, working 35 hours/week, and maintaining better than a B average.

Funny you should mention attorneys because my old high school mints attorneys like the are coming off a copy machine. Back in the 1960s and 1970s, my high school was the top academic high school in all of Central California and one of the best in the state. In my class of 535 graduates, there are something like 40 attorneys. My wife's class (the next year) has a similar number of attorneys, including my old debate partner. My class has about 20 doctors, a physicist, several college professors, no famous athletes, and just 3 civil engineers. We have about 10 engineers total.

Fred

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Thousands told to flee California town as nearby dam faces emergency spillway failure

http://www.cbc.ca/1.3979524

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
The UH OH just got a lot bigger...

I would really like to see some facility drawings on the project. For the emergency spillway to function without failure, it had to be designed for overtopping. What is the maximum design lake level though, and that been exceeded?

I am confused too.. the original emergency spillway first posted was limited in wodth. JAE'S drone shots are much, much wider. What is the extent of rhe emergency overflow? Total release at this point has to be in excess of 140000 cfs at this point from everything I can gather...

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

msquared: The pictures of the guy pumping concrete into the riprap below the lip of the emergency spillway two days agodidn't give me warm fuzzies regarding the state of that outfall.





Go to 4 minutes for the video:
https://www.youtube.com/watch?v=N3x4r7jmD9Y

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Town just got evacuated (edit: missed the mention of this above, sorry. Though there were a few updates since then). http://gizmodo.com/california-town-given-one-hour-to-evacuate-before-dam-s-1792281839
http://abcnews.go.com/US/wireStory/latest-officials-order-evacuation-california-dam-45446241
Looks like the emergency spillway was eroding which triggered the evac but has since slowed down it's erosion. They're planning to plug the eroding area with rocks airdropped by helicopters.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
About 188,000 under evacuation according to 10 pm news, King tv 5, Seattle.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Some good aerial pics of the emergenc slipway here http://www.kcra.com/article/get-a-birds-eye-view-o...

Can only assume the bit they were worried about was the junction of the emergency spillway and the normal one, where they were busy pouring concrete....

The road has already gone that was there.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

They pulled out the stops on the primary spillway. "To hell with the down hill erosion". It was cranked up to 100,000cfs (plus the 17kcfs used in generation) in hopes of taking the pressure off the emergency spillway.

It worked.

At about 1AM the emergency spillway went dormant.

It's still a mystery what was seen to be eroding that was so concerning to officials.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I'm wondering if the thing they were concerned about was on the LHS of the spillway as you look from downstream. You can see that the water level was so high that water was flowing from the entire area to the ~LHs and creating a gully right at the end of the concrete slope. If you look at the picture racoope posted you can see the concrete seems to end abruptly. Maybe that end was being eroded by water flowing from the grassy areas and getting behind the concrete face of the spillway / eroding the toe??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It wasn't obvious what the issues were with the normal and emergency spillway, but one issue is the transmission towers at the lower left of this Google Maps image, which sit between the two spillways, and either one could generate hill erosion that could potentially topple the towers.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The mighty engineer

I got a 404 to that link, but this is where I think they were concerned - I would have been.

Basically the end of the concrete ramp where the water from the rest of the area is funneling down, threatening to get behind the concrete wall.

Also very difficult to inspect until the water stopped.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Do we know if engineers are making the decisions about spillway opening (throttling or free release), or are enviro's, bureaucrats, and politicians?

I know sheriifs are deciding on the evacuations downstream, and that is (more or less reasonable) since they do have to respond if/when flooding occurs to their people.

(By the way. How many delta smelt have been washed out into the Pacific Ocean? Bet the newly-muddy river has none left in its banks.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (LittleInch)

The mighty engineer

I got a 404 to that link, but this is where I think they were concerned - I would have been.

Fixed the link but it's the same area you showed.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I needed to get some perspective on the volumes of water being referred to. The current estimate for flow over the primary spillway is 100,000 cfs, plus additional over the emergency spillway. For comparison, the average flow over Niagara Falls is 85,000 cfs. WOW!

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Does 2800 tonnes per second make it easier to visualise? The forces at work here are difficult to imagine.

I've lived on the North Sea coast for most of my life and I've often thought that each time man builds something to defy Mother Nature it is a very one-sided fight we are entering into.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Water's moving somewhere between
30 to 60 fps depending on the cross section of flow. Lotsa energy there!

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Hopefully, major flooding will not result.

After this is all over, and soon, there needs to be some major redesign and construction of these spillways. I understand that the Oroville primary spillway was supposed to be able to pass 250,000 cfs, yet it couldn't cope with 100,000 cfs. In comparison, the Wivenhoe Dam on the Brisbane River above Brisbane has a reported primary spillway design capacity of 420,000 cfs, and this is on a much smaller catchment than Oroville.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)


An interesting link to the Mercury News discussing how during the last FERC re licensing that the issue of erosion of the spillway was discussed and improvements not undertaken because the water users didn't want to pay the price. Smart move, in that now the taxpayers will.

http://www.mercurynews.com/2017/02/12/oroville-dam...

Obviously, there's a difference in perspective when the event might be imminent.

Perhaps some of the 6+ billion that the the California legislature set aside for dam reclamation and improvements will be tapped - if they can find where that money went. Or since California has asked for Federal aid for the flooding this can just be tacked on to that bill.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I finally figured out what the "hole" is. To figure it out I had to
compare several days of video and pictures.

On Saturday (11th) pictures you can see the road that cuts down slightly diagonally to the E-spillway.
That road runs across the entire E-spillway and then back up around to the recreational area.

That road was on a berm to get it level, well not dippy, it had slope. That berm created what is being called
a "catch basin". That basin filled up a couple of hours after the E-spill started. It didn't fill as quickly
as one would've guessed because the whole E-spill was in operation and most of the water wandered downhill
using many different paths.

But fill it inevitably did. Once it filled the rec-road became a secondary spillway. Being sloped though got
some concentrated flow on it and it quickly failed in it's short spillway life. Once the pavement left the
entire berm vacated in a very short time probably around an hour. This translated the "catch-basin" into a
shockingly large "hole" as the people onsite watched. Since this large hole is fairly close to the E-spill
it now gathers the lion's share of all the spill. Of course this focuses the erosion in the hole. At that
point the officials believed the erosion was progressing rapidly back towards the E-spill wall. The reality is
it was probably not as fast as they thought but more of a story allusion fed by the rapid transformation from
catch-basin to hole.

Anyway, the decision to really crank-up the primary-spillway was probably the best idea.

The helicopter rock bag delivery is to fill that "hole".

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

improvements not undertaken because the water users didn't want to pay the price. Smart move, in that now the taxpayers will.

Right! When in the history of public works projects has that result ever been avoided. "Hey, do you guys want to pay for this?", just never seems to work. Then again I suppose nobody ever wanted to increase user fees, or taxes to pay for it either. Can you imagine?

So back to lesson one. No taxes, or user fees (tolls, etc.) = no infrastructure.

Makes me wonder from where the 50 Americas Most Needed Infrastructure Improvements will materialize.
Popular Mechanics Article: 50 States, 50 Things America Must Fix Now

Edited to add this.
OK so this morning I woke up to hear that the USgov debt ceiling will be increased. That fits perfectly with the new administration's plan to build a trillion in infrastructure while they also propose to reduce taxes .... and kick the resulting "No money to fix breaking infrastructure problem" down the road. The more things change, the more they stay the same, just the swamp keeps getting bigger.

Reaction to change doesn't stop it smile

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Story from the LA Times today. There is a picture about halfway down the article, that shows the hole in the ground and the roadway washed out, after they got the lake level down enough to stop the spillway topping over.
B.E.

You are judged not by what you know, but by what you can do.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Good description and the big hole was probably what caused the initial fear, but this one to me is more worrying.



what we don't know is how deep the foundations of the wall go and what they are toed into, but much more loss of earth and they are in trouble.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

If you dig into that data from Spartan5's link, you can see how fast the water was coming into the reservoir. Inflows of 180 to 190k CFS and the lake level was rising almost a foot per hour. Couple that with the recently found (at that time) damage to the primary spillway and you can see how this became a problem so quickly.


6 days of data

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

At some stage we need to see the original plans. Why did the main spillway fail? That's what started this whole problem.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Exactly, oldestguy. That primary was supposed to be able to take 250,000 cfs. Inflow never got close to that.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Looks like more weather is coming. Wonder what they do if there are more huge inflows. They haven't dumped more than 100k cfs from the primary spillway since the damage. There could be a decision between exceeding 100k or letting the emergency spillway crest again.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Given the 7 yrs of dry conditions, it's not inconceivable that the soil simply subsided from the spillway, and when it needed to be used, the concrete didn't have sufficient support and simply gave way.

Additionally, it's a bit unclear, after the fact, whether the spillway walls were tall enough. It looked to me that some water was going over the edges of the spillway, which might have hastened the erosion under the spillway and resulted in the gaping hole. I think they were about 15 ft shorter than they ought to have been.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Spartan5,

Wikipedia, admittedly not the most reliable source. When I reported that yesterday, the number was 250,000. I was looking right at it when I typed. It has now been revised to 150,000.

https://en.wikipedia.org/wiki/Oroville_Dam

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

LA Times Page

On this link are the hands-down best dronage I've seen of this whole thing. The first video down the page is actually 5 back-to-back ones. In no particular temporal order you can see the entire E_Spill evolution and the birth of the Hole and it's finger snaking right back up to the spillway. Some have great sound even. The absolute mass of water that came over the E-spill is readily apparent where its not been on any other vids I've seen. It gives a sort of fascinating-horror feel.


The evacuation has ended.


Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

azcats, an interesting point. When Wivenhoe Dam in Australia contributed to flooding in Brisbane, there was a lot of scrutiny over whether more water should have been released earlier, and whether releases of water from the dam contributed to more flooding downstream than there should have been.

With predictions of more rain, it would certainly be within the scope of discussions as to how much more water can be released in order to allow for additional capacity in the dam versus holding water in the dam and hoping that the water level won't rise again.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

But the problem is that we have to wait for the 20/20 hindsight to see that clearly.

Reaction to change doesn't stop it smile

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

A very common issue I'm told (and makes a lot of sense to me) is that these projects are built directly in response to near annual flooding that disrupts everything, damaging infrastructure, and frequently killing people. So with a mandate to stop-the-flooding the project is funded and built. Mission accomplished!

Time goes by and pretty quickly no one remembers the flooding and the original point of the entire thing. Furthermore, operational costs go up and up and up. So in an effort to get the dam to fund itself the dam's mission statement quickly evolves into providing water for irrigation and money thru energy sales. The flood control becomes a side-note.

Any bean-counter looking at it can't resolve operating costs with the state's savings from flooding disasters.

The changed mission demands more of a brinkmanship operation of how full can we keep the dam and can we end the rain season at 100%. This, of course, paves the way for disaster if exceptional rain occurs. Q.E.D.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Wivenhoe Dam (and the near-over-topping in 2011) is an interesting case - it was conceived as multi-purpose dam from the start - water supply (a bit over a million mega-litres), flood mitigation (another million and a half mega-litres above Full Supply Level), and pumped storage power generation (about 30,000 mega-litres which can be pumped up to Splityard Creek reservoir and returned in a typical 24-hour cycle).

However, south-east Queensland had been in the grip of a major drought (is anything about this story ringing any bells with the situation in California?) for about seven years, which saw the dam at very low levels, until the drought broke in 2007. Being "drought resilient" was very high in the public and government perception in the years following, so the prevailing wisdom was to let the dam reach full supply level when runoff permitted, and maintain it as high as practical to Full Supply Level.

And then came the wet season of 2011 ...

And we're still trying to figure out the best way to use Wivenhoe for both flood prevention and drought mitigation.

Should we draw the dam down at the start of the wet season, to provide more than 1 1/2 million mega-litres of flood storage? What happens if the wet season "fails", and we hit another extended drought like 2000 - 2007?

Or should we take advantage of the wet season to top the dam up to its nominal Full Supply Level, and live with "only" 1 1/2 million mega-litres of flood storage "buffer"? What happens if we then get another wet season similar to (or wetter than) 2011?

And will these questions become even more crucial due to the effects of climate change? (Will our wet seasons get wetter, and / or our drought years become drier and longer?)

http://julianh72.blogspot.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Damned if you do, and dammed if you don't, eh, Julian? "If my foresight was as good as my hindsight, I'd have a devil of a sight."

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

This has been a great Thread- I have been getting a completely different story from the news. When it comes to engineering topics- the news is "Fake"- or at least incompetent/clueless.

Star for the post


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Fake, I'd say not so much. Alternate facts, no facts, yes definitely.

Reaction to change doesn't stop it smile

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

itsmoked: On your statement that these projects originally were for flood control, check this out. I recall in the 60's hearing talks by a famous engineer who had opinions on several subjects including water projects, his main specialty. Adolph J.Ackerman complained about the wishful payment plans for these projects and mentions the Feather River project as a planed major source of drinking water, not flood control. He predicted funding failures.

Here is part of a paper on this subject and a portion about Ackerman.

https://www.google.com/?gws_rd=ssl#q=Adolph+Ackerm...

The Google search also shows a number of other references for this famous engineer.

I will add one more part of the California Water project

http://res.cloudinary.com/engineering-com/image/upload/v1487177366/tips/Califoria_water_project_1_sip9jp.bmp

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

If you've ever been involved in anything that made the news, you know that they get pretty much 95% of everything kinda sideways with alternative facts when they rush to report on anything, a mixture of ineptitude on the topic of discussion and framing the story for the most clicks possible. I wish I didn't have the experiences that led me to know that.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Other than a few errors, most of what's here is from the news, as no one here has claimed to have first-hand knowledge of the actual facts.

TTFN (ta ta for now)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

But has been done in this thread is that people have looked back to earlier information, and compared various sources. This is called research, and there isn't much of it these days.
When I lived in OK the dams were for flood control, any other use was viewed as very low priority and there was enough backing to keep it that way.
In CA we have flood control, power generation, drinking water, AG irrigation, and recreation all fighting over how to operate the dams. Good luck.

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P.E. Metallurgy, Plymouth Tube

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

We have the advantage here of looking at everything in less than real time. Moreover, as engineers, we have our STEM education that helps in the analysis, which a typical journalism graduate doesn't necessarily have, and I don't have a deadline, other than self-imposed, to process the available data.

Oroville Dam was part of the Central Valley Project, which was to control spring floods and provide a year-round water source for farming further south of the delta. As with most projects of this type, multi-functionality always sells better than single-functionality. Therefore, the ability to supply drinking water and generate electricity simply adds to the appeal of the project. The CVP plays a major role in allowing the southern half of the Central Valley to be part of the agribusiness of California.

TTFN (ta ta for now)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Regardless of the primary and secondary intents of the facility, I think we can dispel ourselves of the notion that somehow "brinkmanship" in operation (AKA playing chicken with the water levels) contributed to this disaster.

The spillway failed at a third of its rated capacity. That seems like a pretty routine operation to me.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
http://www.msn.com/en-us/weather/topstories/bigges...

As of this morning according to the local news, a drawdown of about 20 feet below the level of the emergency spillway had been attained.

I hope this will be getting close considering what is coming.

It will get interesting this weekend...

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Here is an interesting protect for the geotech engineers here. Google EARTH SEARCH the Oroville, CA area and examine the valley trends around the area, as well as look at the closeup photos of the regular spillway when dewatered. What I interpret is the bedrock there is folded "beds' probably metamorphic rock each bed with variable hardness. The direction of the discharge from the spillway failed area follows the apparent weaker rock zones leaving the failure zone. Thus, future migration of that main spillway failure erosion likely will not head for the earth dam. It also might explain "Why the failure is there?" What do you guys think? Armchair engineering, but interesting none the less.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

For anyone who wants to vicariously watch the weather in the Oroville area, please go to:

https://radar.weather.gov/radar.php?rid=BBX&pr...

If you're going to want to keep an eye eon this for any length of time, be sure to toggle ON the 'AutoUpdate' in the lower-right corner of the page.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I wonder how long it's been since that spillway had to release 100k cfs? I bet it's been a long, long time since it's seen even 10k.

And it's crazy how fast that lake filled. It was at 720' in December.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

With respect to how fast the dam filled - that's how it goes with large dams in a major rainfall event.

Back in about 2008, Gladstone (a major industrial city in central Queensland) was getting very close to running out of water - being affected by the same extended drought that impacted Brisbane and Wivenhoe Dam, 500 km to the south. The major industrial consumers had been put on notice that their allocations from Awoonga Dam would be cut drastically in a few months. I was working on some big projects to reduce water consumption (e.g. installation of dry heat exchangers to replace conventional wet cooling towers, substitution of sea water cooling in place of fresh water, etc) which were being fast-tracked - orders for major equipment and stainless steel piping were placed before civil / structural design was beyond concept layout stage in several cases.

One Friday afternoon we got a phone call from the site office that it was "pi$$ing down" (a very Australian colloquialism!) and they were heading home.

The near-empty 770 giga-litre Awoonga Dam over-topped the spillway before Monday morning, and the projects were all cancelled within a week.

http://julianh72.blogspot.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

azcats: per the link I posted above there is data going back to late 1999. There was a peak flow of 32K cfs in March 2011. I'm guessing that's combined flow including the flow through the power plant. Prior to that was the highest observed flow of 80K cfs in January of 2006. There were a couple of 40K cfs releases that year as well. Otherwise, combined outflow rarely exceeded 20K cfs.

If anyone can find any pre-2000 historical data that would be neat to see as well.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As someone who works on little parts I can barely pick up with my fingers and have to look at through microscopes all day long, I find the scale of these dams mind boggling. This particular statistic on the repair of the emergency spill way especially so:

"California Department of Water Resources continues to examine and repair the erosion with construction crews working around the clock, placing 1,200 tons of material on the spillway per hour using helicopters and heavy construction equipment."

1,200 tons per hour = 2,400,000 pounds per hour or ~58 million pounds per day. Where do you find 58 million pounds of rock? I suppose it's better to look at it on a volume basis, that equates to about 13,000 cubic yards per day depending on what type of rock they are using. How much can one of those helicopters lift?

----------------------------------------

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (msquared48)

I would really like to see some facility drawings on the project. For the emergency spillway to function without failure, it had to be designed for overtopping. What is the maximum design lake level though, and that been exceeded?

Some really great information in this document here:
http://yubariver.org/wp-content/uploads/2017/02/10...

SHOCKED to learn that they had planned in the course of normal flood control operation to allow for water to surcharge 10' higher than the top of that emergency spillway surprise and they they could take it up to 16' in an emergency!! Decorum be damned, WTF???

Look at what happened when they allowed a 2' surcharge surprisesurprisesurprisesurprise

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As someone who has worked in micro amps and Kilo amps, it is hard to get your mind wrapped around the sizes of things. But the only differences in the calculations is the qualifier (Pico, micro, kilo, mega, giga).

But I do admit that I have never seen our civil engineer work with tea spoons.

Sometimes it helps to look at what your working on so you get a since of scale.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

dgallup. Think of this in units you can understand works for me.

1200 tonnes of rock equates to around 50 trucks - so around 1 per minute.

To be fair that's a lot of trucks and not sure if they meant 1200 tonnes per day.

The choppers can't carry much , maybe 2-3 tonnes and cycle time is quite long so the heavy lifting is being done by the trucks.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

dgallup - the images I saw looked like Sikorsky S-70 family so depending on what exact mark the external load could be up to 9000 lb - I don't know the elevation of Oroville I'm guessing not high enough to decrease that much.

If they were serious they'd be borrowing some CH-53's from the Marines, if any of them are currently air worthy that is.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (cranky108)

Sometimes it helps to look at what your working on so you get a since of scale.

Like dg, I work at the micro scale when it comes to PCB design... once in a while I need to actually pull a board out to remind myself how small those features I'm designing with actually are compared to what I see on the monitor. Helps to avoid mistakes when you remember how big/small something actually is.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

For the first time in several days, they've just started ticking down the main spillway. It's been right at 100k since sometime on the 12th. 97k and 95k in the last two hours.

Link

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Well, they have drawn it down about 35 feet and increased the available storage capacity for the new storms to about 55,000 acre feet before elevation 902.5 is realized again that was seen on Saturday.

The reduced flow may not be by partly closing the gates, but by the reduced head behind the gates...

I wonder what the elevation of the main spillway is?

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Link

"At the same time, the Department of Water Resources announced it was reducing flows down the dam’s main spillway as crews get ready to remove the large volume of debris that has fallen into the channel below."

I couldn't find (in my admittedly brief search) info on the gate elevation.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (ChicoER News)

At the Diversion Pool, heavy equipment and barges are removing the debris
that has piled up at the bottom of the main spillway. The debris has raised the level of the
pool to the point the Hyatt Powerhouse can’t be used.

If the powerhouse were in operation, another 13,000 cfs could be drained from the lake.

PG&E is also at work, moving some transmission line towers from below the emergency spillway,
in an area that could theoretically flood if that spillway were to be brought back into use.

Ouch! More insult to the dam.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

According to the document referenced by Spartan 5 the bottom of the main spillway gates is 90 feet below the top of the emergency spillway.

Interestingly this also gives section details of the spillway - looks rather simple to me.... No wonder they were worried. The section is noted later as being in the middle of the emergence spillway.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

JINX!

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

SNAP!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Mutual assured confirmation!

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
WOW!
90 feet of head on a 33 foot high Radial Gate.
These must be some honkin' gates!

At elevation 855 or so where they are now, they still have 44 feet of head on the 33 foot gates.

You'd think that they have some lower sluice gates they could open too, but maybe not.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

BTW, here's what the spillway looks like from the inside of the dam, taken obviously during dryer times:

John R. Baker, P.E. (ret)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As to the questions about why wasn't it brought up earlier, it was. 12 years ago, when three groups of "tree huggers" (Friends of the River, the Sierra Club and the South Yuba Citizens League) predicted this in a report they prepared for re-licensing by FERC, the Army Corps of Engineers and the California Dept. of Water Resources. They called for the concrete paving of the emergency spillway, saying it could not be used as designed. But in all the efforts at the time to reduce government spending, the entire dam was declared perfectly safe and fine, so no need to spend one dime on it. At that time it would have cost roughly $100 million, now it's going to be 3x that much.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It would appear that they were right. An expensive lesson in pay me now, or pay me later. Delay is usually counterproductive on all fronts, here very much so.

Reaction to change doesn't stop it smile

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I see the primary spillway as the first priority. Then the auxiliary spillway, which actually did its job, albeit with a lot of erosion.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Assuming we, in our armchairs, are right and at least as I view things, the metamorphic rock under the main spillway will, from time to time, lose material from weak zones and erode, resulting in everyone scurrying around to "fix" them, I wonder if now might be the time to seriously consider abandoning the whole dam and its lake. etc. Perhaps placing this dam and its spillways where the rocks are not the best for this use was a mistake to begin with. This is question that certainly should be considered as repairs or upgrades are considered. If no abandonment, will the fix take some form of cementing the rock under that spillway (and maybe the emergency one also) so that erosion in the future is "assured" to never happen? Costs for that treatment likely will be very difficult to justify. There is a post elsewhere providing pretty good geologic information, including signs of faults near the dam itself. A post on another web group shows an old photograph of the excavation for the main spillway with "rock" being loosened with crawler tractors pulling a two teeth ripper. That's pretty damming info. Even photos now close up show the rock in pieces, not cemented together and deeply eroded zones apparently even weaker. A common construction technique when questionable material is found under a structure is replacement with much better material, such as concretes. At this site, is this even possible if most of the stuff needs replacement by this rule? and how deep?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Sometimes, topography is more essential than geology when dam sites are selected. I don't think there are credible reasons for doubting the dam. It is the spillways that are suspect.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

So because of the flood, you are proposing removing the dam that was partly built to hold back the flood. Is that correct?

I am just wanting to know.

I personally think they should keep the dam, as I am tired of hearing about the lack of water in states where they don't manage the water resources very well.

And I don't doubt that there maybe flaws in the design or construction of the dam or spillway, but the purpose seems sound in reducing flooding.

Otherwise we could declare the land down stream as not buildable for housing, and pay to buy the land, and to move those people.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (Little Inch)

Interestingly this also gives section details of the spillway - looks rather simple to me.... No wonder they were worried. The section is noted later as being in the middle of the emergence spillway.

The toe directly at the bottom of the emergency spillway looks very, very thin to be projecting out that far at the first point where the water coming over the top of the emergency spillway "bounces" off towards the river below. Not surprised the emergency spillway was a point of concern for erosion once it was over-topped.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Let's say this facility is still here 500 years or more. If these spillway problems continue at unpredictable intervals, even if there are paved spillway chutes, will the need to protect downstream people from an unexpected 10 or 20 ft. wave finally get to be too much to deal with? Sure near full lake volume flood control will stay, even if there is complete loss of the spillway area "rock" and earth holding back that upper 20 to 30 feet of water head. Even now major improvements at spillways will be difficult to fund.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I am getting into this conversation late but do have some comments:

The large helicopters are Sikorsky S-64E Sky Cranes - capacity 20k lifts. Probably contracted with Siller Brothers out of Yuba City.

In about 1963, there were a number of new smaller dams just being completed. This project was for the Oroville-Wynandot Irrigation District. There was a dam recently completed and empty. I believe it was called the Ponderosa Dam. The thinking at the time was that it would take two years to fill the dam. There was a heavy storm that came through and it filled the dam in one day. I was working for Guy F. Atkinson at the time and on another project when we heard that they had almost lost the dam. Apparently two of GFACO's people went up to the dam in the evening and discovered the almost full dam. There were large tainter gates that could be opened with electric motors. But the storm had taken out the electricity and the emergency generator wouldn't start. There was a large wheel (mayby 8 feet in diameter) that one could manually turn to open the gates but very slowly. Remember there wasn't mobile phones in 1963. The two fellows worked all night in heavy rain downpours to slowly open the gates and were able to release the water down the spillway. Within the company, these guys were hero's, but I do not know what their bonuses were like that year.

There is a report (which was sent to me) called: "Report on Feasibility of Feather River Project and Sacramento-San Joaquin Delta Diversion Projects - Proposed as Features of the California Water Plan." published May, 1951. It should provide quite a bit of background. Through some conversations I have heard was that some people did not want to do the project if there was people below the new dam.



RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Sounds to me that these structures were not designed to the maximum PMF they could see. Probably need reanalysis and major spillway modifications...

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The captions on one of the photos indicates that Yuba City was flooded on one occasion due to its levees failing after an 100 kgal/s discharge from Oroville. The entire project as a WHOLE is the mechanism for dealing with floods, which includes Oroville itself, the levee system, and other flood control gates further downstream. As population increases and more people wind up in the flood plains, the potential for damage increases.

TTFN (ta ta for now)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As does the need for a reliable water supply.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

2
Anyone with a 3D Printer, you too can have your very own model of the Oroville Dam, perfect for setting up a miniature hydrology lab in your bathtub:

https://sketchfab.com/models/a2e069b5196945b79d948...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
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The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Thank you!

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It's missing some of the newly developed 'features'. :)

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I wonder if it is possible to print part of the spillway with water soluble media. A real working model. grin

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

JR... ditto...

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Bill... hehehehehehehe

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

For an overall picture of the current status of California reservoirs, including Oroville, here's an interesting graphic:



For the full article, which includes some additional graphics showing river levels throughout the greater Sacramento Valley, go to:

http://www.sacbee.com/news/state/california/water-...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Lake Berryessa (at the Napa Valley area) is also refilled 100% + from the used-to-be-permanent drought, and is pouring back out its spillway (the Glory Hole behind the dam.)

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Lake Berryessa; Last time I drove around it it was going over the terrifying lip
of the overflow and the water was coming out the pipe a hundred yards away at the
bottom of the dam like a Devil's fire-hose. The road that goes around the
southern edge of the lake had a handful of creeks running across it that were a
foot deep. It provided a lot of pucker-factor in a Renault 10. I bet those creeks
are really ripping now.

As for the San Luis Reservoir... It has provided me with lots of interesting
learning experiences. As a kid in high school my dad dropped me off on a hundred
foot diameter island two hundred yards from shore. This was so I could sit in a
duck blind in the center of it with my 12 gauge in hopes of bagging some ducks.
To my horror I soon realized just how fast they could raise the level with their
pumped storage. I could see my fifty foot shore line shrinking by the minute.
I was starting to consider the swim to shore when my dad came back. My island was
about 10 feet in diameter when he returned. He thought my 2 hour torture was hilarious.

Recently I stopped at the visitors center with my son at 3am on the way back from Fresno
so we could relieve ourselves. Of course it was closed so we only made it half way to the
center barred by their gate. In desperation we jumped out into the star dazzling pitch dark
in a steady 40 mph wind.

We both learned that peeing in that much wind was a very bad idea, best described as
omni-peeing.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Despite the reservoirs being at, or over, capacity, California's aquifers were severely depleted over the past 7 years, and those may take as many years, if not more, to replenish.

Oddly, San Francisco's beloved Hetch Hetchy Dam is not part of the state's water project, so statistics aren't listed there for it, but are here: https://waterdata.usgs.gov/nwis/uv?cb_00054=on&...

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Inflow and outflow have reached equilibrium at about 60,000 cfs. Upstream reservoirs are at capacity. Up to 10" of rain is forecast. These are not good things.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

There have been 90k inflows the last several hours & the lake level is slowly rising.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

itsmoked: Since you are digressing and no complaints appear, maybe you can tell us how's come you picked that handle.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Since he's electrical... no smoke or sparks; it's a software problem.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Here is yesterdays update on you tube.
B.E.

You are judged not by what you know, but by what you can do.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

More armchair comments. Noting that there was a geologist way back at the beginning chipping at rock samples and photos showing erodible rock then (at least near the hill surface and likely deeper), and seeing the grid transmission towers placed where the emergency spillway erosion could take them out, and now that they have been disconnected, and hearing that the release of water via the penstocks to the hydro plant, but the hydro generators can't be run due to high tail water and that they must be connected to the grid to be running, and that there is no grid power now to run the spillway gates, this certainly will rate as one of the greatest engineering disasters of all time.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (oldestguy)


...this certainly will rate as one of the greatest engineering disasters of all time.

If there is no downstream flooding and the public is not seen as being in danger, I really doubt that the average man-on-the-street will agree with you. Granted, among engineers and others like the present company, you might be able to make an argument that it belongs on some list of "Greatest Engineering Disasters" but that will be about it. As far as the media is concerned, as soon as the threat to life and limb was removed, so was their desire to cover the "disaster" since from their point of view, there was NO disaster and therefore NO news.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Mr. Baker you are right, but the general public doesn't read these posts, only engineers. Without that designation,or another designation (medical, human, etc.), it would not fly in general. Regardless, looking back how could such a group of mistakes be made by engineers apparently with so much experience? Politics in the way?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

If it fails entirely, then it probably would exceed all of the other major dam failures in the US combined: https://www.rt.com/usa/377210-dam-disasters-in-ame...

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I don't know, I consider this a failure of maintenance as much as anything. Something was going on with the main spillway awhile ago and they didn't fix it. Then when they needed it, it caused severe damage....

But, it was through excellent design of the overall dam system that the severely damaged spill way posed little to no threat to the overall dam stability.

Then the emergency spillway was used in lieu of the damaged spillway instead. Not sure why. Maybe to limit the cost of repairing the damaged spill way this summer.

To me, the emergency spillway is the only thing that shows a true flaw in design. And, that's in a redundant system that was never supposed to be used. Though you could also say that this is something of a maintenance issue as the problem was identified 10 years ago.

Even then a failure of the emergency spillway wall doesn't jeopardize the overall stability of the main dam. It just means that 30 feet or so of water could be released. Enough to cause a major disaster and loss of life, for sure. But, not like what would happen if the main dam itself were to fail.

Overall, there is lots of impressive redundancy engineered into this system.


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The main spillway failed probably due to a very weak zone in the "rock" (look up the geology of Oroville quadrangle A real jumble of different "rocks".). During construction weak zones like that should have been replaced with much harder material, a very common technique. Note the direction of the flow matching valleys in the area as to orientation. Enough erosion of the weaker "rock" traveling up stream is the main concern now at the emergency spillway and could, in time, also take out the gates of the main spillway. After that how long before a new gully forms there in this weak "rock" draining the lake. Redundancy in design maybe, but why the scrambling now? It's a botched redundancy job.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Another point of concern I found out last night.

Apparently the power to the main spillway gates has been cut as the turbines are currently shut down pending debris removal downstream. This removal process necessitated disconnecting the turbines from the power grid, as well as the main spillway gates. So, except for any possible manual manipulation, they are stuck at 60,000 cfs or so for the moment.

Seems to be doing OK for the moment.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

oldestguy; I probably shouldn't digress further here. Ask me in the pub sometime.

The power plant and dam still have power as the transmission line running across
the "party area" simply ties two substations together for redundancy and probably
to support summer cooling loads. Hence, they still can run the gates and start the
plant up whenever they can.

I wonder how the two barges and cranes that have been trying to remove the debris
from the tail-water bay are making out. No one ever seems to report on the nitty-
gritty. Someone should have a science reporter tagged to the mess.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
itsmoked:

So are you saying that even with the turbines off line, the gates are able to draw power from another source on the grid?

I understood that the main transmission line from the powerhouse to the switchyard had been disconnected too, creating the situation I described.

There is so much ^&T^ here, I just do not know what to believe anymore.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"...should have a science reporter..."

While a few are competent, too many science reporters haven't got a clue.

Excuse the interruption; carry on...


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

msquared48,

It would surprise me that there wasn't in-house emergency generation available to operate safety-critical equipment such as the penstocks, control systems, etc. Being on internal generator power obviously isn't ideal, but a whole lot of things in that plant are a long way from ideal. I'm not from a hydro plant background but internal generator backup is certainly normal with thermal, CCGT or nuclear plants.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I gathered from the video that they have to rely on emergency standby generation to operate the gates, and this power may not be available. Pretty scary situation. I don't know what's downstream for a substantial distance, but, if it is occupied and the dam fails, there could be a loss of life in the thousands. I pray (and I'm not overly religious) this is not the case.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

To answer a couple of the questions that has been asked...

msquared48 at 21 Feb 17 23:03 wondered about how the spillway gates were being powered. If you go back to berkshire 21 Feb 17 17:33 post and watch the video you'll see where there are emergency generators providing power to the dam and the spillway gate mechanism. This should also answer ScottyUK 22 Feb 17 00:13 question.

As for the questions asked by itsmoked at 21 Feb 17 22:21 the video below should help with that as well as more discussion about the emergency generators and some good video showing the current level of the water in the dam:

https://www.youtube.com/watch?v=Nrz-U1yxOWM

And from what I've seen in his videos, this guy Juan Browne might also answer the issue highlighted by VE1BLL at 21 Feb 17 23:51 when he was asking if there might be a "competent" science reporter around. Now I don't know his background or if he's even an actual reporter, but so far he appears to be doing the job fairly well:

https://www.youtube.com/channel/UCphqjYZxxzjNbONVm...

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Thanks John for that YT link. That guy did a great job! I liked it a lot.

About the power, cripes. I watched on TV as an Oroville 'engineer' stated
that the power lines, "Only go between substations and do not affect power
plant operations".

It certainly is hard to see thru all the BS.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Being from a power background, Portable power units can be rented, so that should not be an issue.

Also, reporters almost always get it wrong when it comes to reporting about the power industry.

Power transmission lines do go from substation to substation, and most power plants have an interface substation. The exception is if the power plant capacity is very small.

Some hydro plants have backup generation that is from the same source as the main generation, i.e. hydro. But if the tailrace level is too high, none of the generation can produce much output.

Assumption: If the main generation can't be used, and it's not from a lack of water behind the dam, then the tailrace water level might be too high. Question: Why is the tailrace water level so high?
Why is the water not flowing downstream?

Another possibility is the transmission lines/towers may have issues. Is it possible some of the transmission towers have been undermined?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

cranky108 - I presume the tailrace water elevation is so high because the area downstream is packed with debris.

My biggest concern with this whole situation at the moment, is with the "fucntional", non-damaged portion of the spillway. The lower portion failed at 50,000 cfs, after a relatively short period of time at that flow rate. And after not having regularly been subjected to flows like that for some time. And for an undetermined reason.

They have been "stress testing" the rest of it for some time now, and will have to do so for the foreseeable future. How long can it hold up? If there is an insidious little crack growing, or cavitation eating away at something out of sight; we won't know about it until, well, we know about it. I would imagine they would really like to have a look at it in the near future.

Otherwise everything seems about as under control as it can be at this point.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Another question. Looking at the recent posts on the Water Department web site I see a large group of workers (some volunteers) carrying buckets if road gravel in the backfill area outside of the walls alongside the main spillway. It would appear they are trying to place a graded filter between adjacent earth and cobbles forming an apparent drain system behind these walls. Any comment from those more familiar? I still need an explanation as to where the water comes from that we see spilling into the spillway from these walls. Is that water originally from a drain system under the spillway floor or collected from nearby earth and rock outside the wall area? Noting where they are placing the road gravel, maybe the latter is the source.

http://pixel-ca-dwr.photoshelter.com/galleries/C00...

For cranky Note the large "delta" in the river below the spilling water near the main spillway. That will be difficult to remove in a hurry.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I don't know if Juan Browne is correct, but he stated in the video JRB linked that they will have to route the power house output in a completely new direction. Seems like that could take quite awhile depending on how far and how many towers have to be erected. Seems like it will be a long time before they can restart the power house and use it to lower the lake.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

If that's the case, why are they in such a hurry to clear the debris?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

This video taken Tuesday 21st indicates the tail water is up 22 feet from normal due to debris at the spillway area. Looks like a long way to go before back to normal.

https://www.youtube.com/watch?v=Nrz-U1yxOWM

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

From what has been reported, there appears to be no way to bypass the turbines when using the main spillway. All of the water that goes into the powerhouse must pass through at least one of the turbines and without them being connected to at least some sort of ballast load, there's no way to control their speed.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

IIRC you walk out the door of the plant, everything being concrete, -level concrete-,
and to the immediate right is down to the tailway water, and spreading out to the left
is the PP switch yard.

If the water is lapping at the door in then it is also lapping at all the transformers
and switchgear.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Kenat:

If water is being channeled through the scroll case to the turbines, unless the impeller vanes can be closed completely, the turbines will turn, generating electricity. The vanes are usually fixed though.

Two other things:
1. Debris in the downstream channel could affect the tail water elevation, and
2. Debris in the water could damage the turbines if it entered the intake.

I am a little unclear where in the project the debris cleanup is occurring that closed the power plant.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Thanks John & msquared, was wondering about the turbine over speed issue hence my term 'productively produce' and you pretty much support my concerns. I'm pretty sure none of my ideas for using up the 'spare' electricity would pass muster eithersmile

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Kenat See my post above and the link. That will answer your question. Passing a bunch of water through the tribunes would over spin them without hooking to the grid, now not hooked up. However, note that the water is so high there that it is above the floor level of that area. If the wall gives way the generator sections will be under water. It now is one heck of a mess, not soon to be back to normal by any meas. I'd give it a few years at the least.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Debris is blocking the channel downstream and raising the level at the power house. Discharging water through the power house may raise the water level further.
Many years ago, an ice storm took took out a couple of towers on a 500 kV line feeding Vancouver Canada.
They brought in a couple of cranes and suspended cross arms with insulator strings in place of the downed towers.
I don't see it taking very long for a temporary connection to the grid, but anything that may raise the water level further may be the real issue with not being able to use the power plant.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

On the plus side, maybe there will be some fresh gold downstream for us panners.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote:

On the plus side, maybe there will be some fresh gold downstream for us panners.

Oh yeah! That spillway brings a whole new scale to hydraulic mining.

They should just request gold miners to come pan the debris field requiring them to dump the dross into dump trucks. It would all be removed in about a week.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Gold is heavy, so you should expect it in the bottom of the lake. Wait for the next low water event and pan the bottom of the lake.

Many floods have been caused by not keeping creeks and streams clear of trees. The problem being that because of the water table, the trees like to grow in those low areas.

On the other hand, the debris is limiting the amount of water downstream, which maybe good for those people as long as the earth and debris dams don't break.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

An interesting article which offers a possible explanation for the failure of the spillway:

Oroville Dam: What made the spillway collapse?

http://www.mercurynews.com/2017/02/17/oroville-dam...

This item is a week old, but I can't recall anyone mentioning this specific issue previously. If they did, I apologize for offering something that has already been presented.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I'd agree that cavitation is more likely over hyped-up moles.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Mr. Baker: This is another example of non-professionals codgering up a story without checking with professionals. If you look way back on this forum you will see a likely version from me. Also look at the crummy "rock" situation at the emergency spillway and it all fits together . This whole site is crummy "rock". It hardly can be fit to be called rock. Locating a dam here based upon topography and hoping to do enough changing of what is there to make it work has failed. Let's wait for a clear explanation from those close to the situation. Let's have some expert from there explaining the presence of workers (volunteer?) on the outside of the spillway walls with buckets of road gravel apparently trying to place some filtering of water before it reaches the cobbles backfill to those walls. Why? Also where is the water coming from that squirts out from the walls into the chute? As of now this forum does not have an expert's explanation of this chute failure.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Rock Badgers. It had to be Rock Badgers!

Don't discount cavitation. The failure seems to have started in an area of transition from laminar to turbulent flow, but we will see.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I did not offer this item as if it were from a 'scientific journal'. It's a newspaper article, written by what appears to have been their science reporter. And I only suggested that it might provide a "possible explanation". That being said, I did find it interesting that this "non-professional" at least took the time to research and reference other examples where this cavitation phenomenon had been shown to have apparently damages the spillways of other dams around the globe.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

OG once more: I have a general rule that might apply here. If the article has one thing obviously wrong, the rest of it is highly questionably. Saying the main spillway is 3,000 feet long when it really is 1,700 fits the rule.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Cavitation damage at the transition from laminar to turbulent flow is well-known even on smaller river structures like weirs, except I imagine that the forces at Oroville are an order of magnitude larger. I take an interest in weir design as a kayaker because some of the anti-scour designs are outright dangerous to a kayaker or canoeist, but while learning about them you also pick up layman's knowledge of the problems they are designed to prevent.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I wonder if the same cause could be attached to the local road problems we are having?

Or could it just be one or more bad pours of cement. Bad soil compaction, or something a little more simple.

It's likely we won't find out for several years, as those who know may not be talking about it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

@oldestguy: If you look on google maps aerial (earth) view, it does indeed look like the main spillway is about 3000 ft long. The 1700ft number is the length often quoted for the emergency spillway. (Which is "width" if the 3000 ft is a "length"!). I'm not sure if that 1700 ft includes the parking lot, as the emergency spillway wall looks like only about 1000 ft to me on the aerial image.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

OG again: I use my age as a excuse if I was wrong, 1,700 vs 3,000. After a log search found one newspaper says 3,000, so I was wrong. Anyhow, who might be able to explain these guys on the 20th, carrying road gravel, presumably to provide filtering of water entering the cobbles there behind the side walls of the main spillway? Seems like some soft of band aid to features not built right in the beginning.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The article was partly talking about issues with the Glen Canyon Dam, which has two spillways, and they could be on the order of 1700 ft long, but they're tunnels, so there's no way to get an accurate measurement of length.
<edit>
I did a crude measurement of the attached, and came up with 1524 ft for Glen Canyon Dam's right spillway, but the left one was the one mostly damaged


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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Three five-gallon buckets in each hand filled with gravel? That's about 200 lbs in each hand.
Don't start any trouble with these guys. They're a lot stronger than they look.

Bill
--------------------
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Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

That's what I was thinking too.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Apparently on some other sites there is an explanation for the water spouts into the main spillway from side walls. There is a drain system under the base slab, with pipes on an angle leading to side walls and then into a sloping pipe under the exterior wall backfill, periodically dumping the collected water into the sluceway. Cracking the concrete base slab in many places seems to follow that diagonal drain locations.





RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Another view showing cracks.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"Another view showing cracks."

As Adam Savage (ex Mythbusters host) would say:
"Well, THERE'S your problem!"

http://julianh72.blogspot.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It was just announced that they were planning to throttle back the flow on the main spillway today to remove debris affecting the power plant.

I'm eager to see the damage to the main spillway, after all this time of near-full water release.



CF

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I've been told that concrete is guaranteed to crack.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The question at the spillway with cracks above the perforated drain pipes tends to indicate a thinner slab at these locations. However, the mix of materials going into the product as well as the site conditions have a great deal to do with potential for cracking. A major player is the water content of the mix. Generally the higher the water content, the more shrinkage that may occur later. I've noticed on some jobs that within as little as less than an hour that shrinkage has started.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

As an unfortunate repeated victim of the Spartan Race's "Bucket Brigade" obstacle....

Those buckets have to be empty. There's no way.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Apparently the buckets and the road gravel are filled at a lower part of the hill and the worker is just taking them back to be filled. The reported work is merely making a walking path over those cobbles for visitors.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

So, these guys aren't super human after all. I was going to say that carrying 400 lbs down a hillside is an injury waiting to happen. Here is a NFL player doing it and it is a struggle for him on flat ground.

https://www.instagram.com/p/BDVxoJjJFvG/

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

They are going to need so much JB weld to put this Humpty back together again.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Here's the latest video 'blog' from Juan Browne, dated today, Feb 27th:

https://www.youtube.com/watch?v=9lmYJAg3Evs

John R. Baker, P.E. (ret)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Wow - the power of water moving.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

HamburgerHelper... good thing they weren't going uphill with them...

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"Wow - the power of water moving."

It was doubly bad because when the water hit the break, it also went sideways and took out the terrain on the right side of the spillway, which allowed the hillside under the spillway a much easier egress from under the spillway

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

After looking at the latest photos, I was thinking the same thing. If all of the loose rocks and debris has been washed out and they get the basin opened-up and the water level drops to the point where they can start to release water through the main spillway (through the turbines in the powerhouse) perhaps there might not be a need for a completely reconstruction secondary spillway. But then I'm not a civil engineer so I'll leave that to the professionals.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

What you see is technically the "main" spillway, the operative word being "spill" The turbine waterway is typically limited to very low flow, only enough to turn the turbines. The typical requirement is that it needs to be as low as possible while still providing adequate for whatever is needed downstream, whether it's keeping the delta dart alive, or provide irrigation water for farmers.

The spillway, on the other hand, is to keep the reservoir from overtopping the dam

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

After weeks of blazing 50kcfs the erosion seems to have reached a static situation. Why
not just concrete in the few remaining areas that look erodable instead trying to refill
and re-create the original poorly functioning spillway?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Some of the comments remind me of a solution one university had to pathways in a new section of campus... they let the students walk wherever they wished for several months, then they put in concrete paths along the areas where the grass was worn away.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Some of the comments remind me of a solution one university had to pathways in a new section of campus... they let the students walk wherever they wished for several months, then they put in concrete paths along the areas where the grass was worn away.

My alma mater, North Carolina State University, followed that philosophy. Knowing what battles to take on with mother nature, and when to let her have her way, is an important piece of wisdom for any engineer.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (trying to re-create the original poorly functioning spillway?)


The spillway was not functioning poorly until it failed. Up to that point, from what I understand, it worked just fine.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The arm chair thoughts also were mine until I looked at the close ups to just leave it as is. The gray rock appears competent and holds pretty well, but that material that is brown color does not. Leaving things as they sit now may well get erosion backing up toward the inlet. That was the concern at the emergency spillway, possibly still not well reinforced. Maybe the water department had better bite the bullet and do it right this time. Enough information was there when they originally built to avoid this. Now there is a second chance to do it properly.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
Looks like they need to do some selective blasting to me to create a viable channel that is stable and can be maintained. Use of some high pressure grouting would be in order too with all the fracturing.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Just found part 2 of the DWR video above, which has a little closer view of the geology surrounding the primary spillway and distant shots of the work beginning to get the down stream channel cleared so the generators can be restarted.

https://youtu.be/GlSGDGTaCh0

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

More arm char thoughts. That delta appears to the harder chunks from the gully areas. I'd first do some soundness tests on representative chunks. If it meets specs for concrete, then set up a crushing plant, sieving and then a concrete batching plant, possibly on the side hill between the main spillway and the dam. Maybe an aggregate washing plant also. Then rig a cable system from there to the gully. Heck, that would take care of the disposal problem and serve as an aggregate source. The stuff probably has had all the soft parts washed away. Right now playing around with a dozer or two and a back-hoe to try to open a channel isn't going to really do the job needed for a good fix. It would be nice to see a well thought out plan.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (jgqri)

The spillway was not functioning poorly until it failed. Up to that point, from what I understand, it worked just fine.
Famous last words angel

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Look at the size of some of those boulders compared to the bulldozer. It will take way to long to clear a channel in that with a trackhoe and a dozer.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Then along comes another required release of water moving a lot of debris and fills the channel made for allowing the turbines to run. To work on a big job like this ya gotta think big. So far it's like no big plan yet.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It's likely that the reason they needed to use the spillway was also the reason for the compromise of the spillway itself. What was unusual about this year is the heaviness of the rainfall, which, coupled with the years of drought might have allowed rain to undercut the spillway, and the rapidity of the reservoir filling up didn't even allow time to fix things. Note that this year is particularly unusual because the rainfall and reservoir filling were essentially concurrent. Typically, the reservoir level peaks after April. I can't post pictures directly into the thread from work, but the data is here:
https://cdec.water.ca.gov/histPlot/DataPlotter.jsp...

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
This scenario kinda reminds me of one of my boys who wanted some new Scooby Doo underpants.

My wife did not want to buy them for him, but in the store he did the unthinkable, and she relented.

He got the new pants.

So goes a new spillway...

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

@ oldestguy: "Then along comes another required release of water"

Under the heading of;
STUFF HAPPENS.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Right no release right now, but who knows about that weather there these days.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The same site referenced above has historical data for outflows back to 1984, and shows that the last major use of the spillway was indeed in 2011, and before that, 2006

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I saw this decent overview of videos showing the events.

https://imgur.com/gallery/mpUge

oldestguy - A massive amount of hillside got moved. They can't begin to properly move it back or clear the river within days of the spillway being shut down...

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

They need to quit pissing around with such small equipment.
They need to address this like an open pit mine and really move some earth.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

60,000cuft/day being moved is pissing around?
Seems reasonable to me.
Isn't that just a month? It would take more than a month to get open pit mine style equipment in place.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

My thoughts too itsmoked - some of the big pit mining equipment may not be practical to get there, or may not be available on demand. Isn't some of it essentially assembled in place?

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Here's a recent article with several animated GIF's showing Lake Oroville's recent change in water-level:

http://www.huffingtonpost.com/entry/california-cli...;

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

How about a walking dragline?
Some specs from memory of one of the first machines used at the Syncrude operation.
Working radius; 360 Feet.
Bucket capacity: 85 Cu yards, more or less.
Weight; About 7000 tons.
Height to top of boom: 214 feet.
Width: about 100 feet.
Walking speed: About 1.5 miles per day.
Prime movers: 4 x 3000 HP synchronous motors.
Production: 100,000 Yards per 24 hour day.
Energy source: 25,000 Volt trailing cable.
Assembly time: Six to ten months.
The dragline on display north of Fort Mac' could be walked down to California in about 3 years.
You would need a really long cable and may have to wait for a number of highways and bridges to be extended to over 100 feet wide.
100,000 yards per day versus the present 60,000 yards per day.
This increase in eventual production may be hard to justify.
Let's just keep doing what we are doing for the next month or so.
https://tce-live2.s3.amazonaws.com/media/media/121ddd79-8aeb-4e3a-8cc2-b4970e94c0ca.jpg

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Evaporation, perhaps winky smile

John R. Baker, P.E. (ret)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I was thinking of equipment in the mid-range, not draglines.
Stuff like a Cat 992/3 loader and a 200-250t haul truck.
These are not uncommon, used in many smaller mine operations, some of which are not that far away.
As flat as mine work is I would think that there is idle equipment in the west.
So they are moving 2,000 cu yards a day (60k cu ft?), and they need to move 1.5 mill cuyds, that is 2 years of work.

Have they talked at all about long range plans? How they are going to re-build and reinforce the structure?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Do they have to remove ALL of the debris or will it be enough, at least in the short term, to simply dredge a channel that would allow the backed-up water to flow downstream into the main branch of the Feather River?

John R. Baker, P.E. (ret)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
itsmoked:

Those rates from the top left chart you posted look like release rates to me, not inflow rates.

Perhaps I am not looking at the correct chart?

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

They're moving 60,000 CY a day. Since the spillway shutdown February 27th, they've moved 427,000 CY. That's nothing to sneeze at. I believe they are trying to dredge a channel to allow the powerplant to operate at a minimum, but are trying to move as much material in the window they have.

Incident Update

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Where is it showing sub-zero flows? The upper left graph is the inflow into the reservoir, and the upper right is the outflow. The inflow is is around 16,000 cfs, while the outflow is around 1,750 cfs. The lower right graph shows a slight increase in total stored water, as expected.

TTFN (ta ta for now)
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I don't know about mining being flat, as it is not flat here. But then again it is mostly just rock for construction, which is local.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (EdStainless )

So they are moving 2,000 cu yards a day (60k cu ft?)
I miss typed 'cuft' when it was really cubic yards.. I even did the math correctly but blew that. "Isn't that just a month?"

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (IR)

Where is it showing sub-zero flows?

It's not anymore. There was one day about 4 days ago that was about 200cfs BELOW ZERO. The vertical
auto scaling actually went to zero and the data point was below that.

Odd.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

My guess is that any sub zero flow information is just noise in the instrumentation.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Pitt lake in British Columbia is unique in that it is a fresh water lake but it is tidal. When the tide comes in, the Fraser river backs up and forces the Pitt river to run backwards and raise the lake level.
A friend and I discovered this in the middle of the night when we were camping on a beach. We woke up just in time to avoid getting our sleeping bags flooded.
Not so sure about Oroville lake.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

If the river below the dam backed up into the lake (reservoir) 800+ feet above, then it'd probably be on the news. smile

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Ah.. That sure explains it IR. Thanks.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I caught one!



See, I wasn't insane.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Anyone have info on the reconstruction plan, if any. The shotcrete work at the overhang above the failure would appear to me to be just a temporary bandage in case the spillway has to take some water soon. Considering this dam probably has an infinite expected usable life, spending bucks now would conform with the typical engineering approach as on other jobs. Maybe politics will override that.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

(OP)
I took a look at the inflows and outflows in the link posted in my original post in this string and noticed something odd. The inflow is less than the outflow yet rhe reservoir is rising.

Seems like this is evidence that their hydrologic model is off.

Mike McCann, PE, SE (WA)


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I don't see comments related to cavitation as a likely cause for the spillway failure, but the ChicoER had an article back on 2/16 that mentions it (link below). The reverse camber of the spillway just seems wrong to me, as it creates an accelerating profile for the water flow, creating ideal conditions for cavitation bubbles to form. Since about 50 years ago, stepped spillways and other aeration schemes to mitigate cavitation have been incorporated in spillway designs, but never got retrofitted to this one? I've seen other spillway channels in California with the big block-shaped aerators spaced all along the channel slope, dunno why that could not have been done on the Oroville spillway.

http://www.chicoer.com/article/NA/20170216/NEWS/17...

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I find Itsmoked's attachment to the latest Youtube videos fascinating. Certainly gives a good overview of the scale of construction taking place today. Megamillions of $$$$$$$ for sure and even allowing for the emergency nature of the repairs , probably not that much money being wasted. However my immediate thoughts are " Which engineering group was able to get their act together so quickly to generate recommended repairs?". I'll guess that the necessary approvals came quite quickly as the consequences of procrastination mustve been evident , even to non engineers , early on. Would this have been the US Corps of engineers or a private group??

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I posted an article back on 24 Feb 17 14:58 which suggested that cavitation could be the cause of the spillway failure. However, at least one person here took issue with the item suggesting that it was "highly questionable" due to it having being written by a "non-professional", that is a person who appeares to be the science-reporter for 'The Mercury News', a Bay Area newspaper.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Looking at the flows:
http://cdec.water.ca.gov/river/res_ORO.html

It looks like they've got all the turbines (one is removed for repair) running today.

And. That means they can drain the dam faster than the inflow without using the main brokenway.

And. They cut it realllly close to their quasi-arbitrary 'we shall not exceed 860 feet' level, or 'we would have to use the spillway'.

This will mean the sheriff's "I won't lift the warning until this list of conditions has been reached" list
is, I believe, now covered.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote:

I took a look at the inflows and outflows in the link posted in my original post in this string and noticed something odd. The inflow is less than the outflow yet rhe reservoir is rising.

Seems like this is evidence that their hydrologic model is off.

I don't understand how they even have a semi-real-time inflow figure for this reservoir. It has at least four major inflow arms and countless minor streams, all of which are flowing significantly after the frog chokers they have experienced all winter. There can't be stream gauges on all of them, so they are either leaving them out (which would account for the unexplained increase) or guessing at them, and possibly getting them wrong.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It looks like they post the immediate flows but that they are eventually corrected somehow. Really
large ones and negative ones appear then disappear. Probably a human checking and adjusting the
horribly noisy data IR showed us back a few days ago.

John; On a billion dollar reservoir I can easily see multiple flow meters on even the tiniest contributor.
They also have the absolute final word via the reservoir depth and the fact that they probably have very
accurate outflow sensors. That probably allows them to correct any inflow flyers confidently.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Looking at the whole picture, I put my money on cavitation and some sloppy engineering design.
Let us keep Bernouli on the side for the moment, and bring Uncle Newton in. That area is below the curve in the spilway. The water want to continue straight, but eventually gravity will win,slamming that water mass down on the concrete.

Now the big problem. One never ever pour high load bearing concrete directly on bedrock,unless you dowl deep or pile support it. That concrete starts to "hop" on the bedrock and the cavitation hammers it away from the top.the result, a total failure of the concrete itself. Now the demolition continue on the bedrock.

That bedrock should have been removed way back, and layer filled that base foundation,compact each layer to 98 % mod, built it up for about 3 meters. Only then cast the concrete and build the spillway. Secondly, add synthetic fiber as additional re-inforcement in the concrete at a dose of about 5kg/m3,will reduce the amount of expansion joints and give the air bubbles less bite on the edges of the individual concrete slaps.
My 2 pennies for what it is worth.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"Secondly, add synthetic fiber as additional re-inforcement in the concrete at a dose of about 5kg/m3,will reduce the amount of expansion joints and give the air bubbles less bite on the edges of the individual concrete slaps."

Not a structural guy or engineering historian but would that technique have been available when the spill way was built?

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (KENAT)

Not a structural guy or engineering historian but would that technique have been available when the spill way was built?

Maybe they could have coated the whole thing in Flex Seal and called it a day. If they can cover a 1950's era pickup truck in the stuff and make it a submarine surely it is up to the task.




RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Hey RockLove your comments are interesting. Since when is a slab of concrete with even 8 feet of water a heavy load? Also tell us where compacted soil at a high percentage of Proctor is less likely to erode away than even the weaker rock at this site? My bet is the deep erosion areas will have a fill of well cemented material, likely similar to concrete. That would be much less likely to erode than your suggestion. With an estimated "design period" for the repair of three months, I hope all these possible deficiencies will be covered. Certainly the original design and construction really "missed the boat".

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Didn't see your earlier post, sorry John. But, I'm also about 100 years off (and probably more) in my estimate for the development of energy dissipation and aeration designs in spillways...see:

https://en.wikipedia.org/wiki/Spillway#/media/File...

Designed and built in 1880, but apparently still standing 100+ years later. People (not just our US Dept. of Reclamation - see Glen Canyon dam spillway erosion problems recurring as late as the 1983 floods) are still underestimating cavitation and erosion rates on spillways. Arrogance or ignorance, dunno which.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

To Oldest, the base would only corrode if the concrete on top is damaged,but it provide a much more stable foundation as what bedrock is. its not the 8 feet of water thats the problem. its the tiny air bubbles in the water that cause cavitation. In the past many believe cavitation is a minor only to realize now that it is still a nightmare if not taken in consideration.
No argument from my side. Well,whatever, going to be a very costly 3 months.I wonder what the cost is up to now since all this started this year.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Rocklve: Notice any of the photos of the spillway walls when it was operating. That water spouting out of the side walls is from under the slab, getting there from a herringbone layout of perforated clay tile pipes (shown in a few damage photos) under the slab FULL LENGTH. The whole length of spillway had leaks getting to those drain pipes. It seeped downward via MANY MANY shrinkage and joint cracks, not likely cavitation. Once under the slab and moving there, the ultra weak sections of the bedrock easily eroded, causing the failures. Any repair that does not address the erodability of the stuff under the slab is just half the job needed. In my view the entire remaining spillway needs to be torn out and these weak zones replaced with hard stuff, such as concrete. Fixing the cavities is a good idea, but not doing a complete replacement of crap under the slab will only result in another situation like this some day. Looking at the emergency spillway you see the rotten nature of the bedrock in this area.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I thought cavitation was caused by fast moving fluid that that has low pressure pockets that cause the liquid to turn to a gas. I thought the damage was done when the bubbles collapse back into a fluid when they move back into a higher pressure region. I didn't think air bubbles ,not cavitated water, caused damage.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

rocklove... the problem comes from the water surface wanting to lift off the concrete, creating the negative pressure required for cavitation. Water slapping the concrete (other than the wave created) is not normally associated with cavitation.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

HH... it's caused by a partial vacuum and the air 'bubbles' that form collapsing with the fluid on the opposite side of the 'bubble' collapsing through the bubble and 'smacking' or impinging on the opposite side.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Oldest, We are on the same page. Agree fully what you say,that the whole bottom part must be redone and serious attention to the base material before a new slab is cast.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

What troubles me is the large number of spillway failures. And the implications of those failures. And the root cause of those number of failures.

First, clearly the problem (failure of the concrete surface and substructure) ON and ABOVE the surface of the spillway walls at high flows is not being solved now, nor was it correctly approximated and solved in the past assumptions and construction. The combination of huge (but constantly, instantaneously varying) turbulent impact forces, combined with small but also continuously varying cavitation forces (the vacuum formation, then rapid re-collapse and micro-shocks as the bubbles re-form and re-collapse) is immense - and not be solvable at all even with today's higher-speed computational fluid dynamics FEA models. But even that is telling: If we cannot even determine consistently with the "pure theory" of these massive water flows, how do you design a system to withstand them under emergency conditions? If the models are not "accurate" to a sufficient degree to predict the specific multiple failures we see worldwide when the spillways are used at high flows, how do you re-design existing spillways to prevent a future loss? If "testing" breaks the spillways that are tested, you have to rely on the CFD models to go forward.

Second, the failure inside the walls between the impact and cavitation are not being absorbed reliably in what was the original (and repaired) concrete, rebar, and steel liner designs. Here at Oroville, if the mid-span conrete and rebar were adequate, the spillway would not have torn in half between the upper curve (a lower flow pressure area), and the lower straight discharge region with its spray breaks. Instead, the spillway floor tore out at the concrete expansion joint/construction joint.

Third, the failure BELOW the walls and floors between the spillway concrete and the rock below. Maybe that is inevitable: After all, if you don't know the underlaying material and so cannot estimate how much strength is needed to support the open "spans" between good support and weak support areas under the concrete being pounded by unknown forces from above, you can't design and pour the concrete around the any rebar network strong enough to absorb the blows. But, how many existing dams worldwide have been properly surveyed and prepared underneath? Almost as soon as the Hoover Dam was filling, the poured "joint" between the dam and the rock underneath began needing repairs and grout to seal leaks, strengthen the rock against tearing forces.

The tunnel walls under Hoover used steel liners to define the flow lines and reduce turbulence in the original bypass tunnels, which were then plugged at the mid-point and adapted as spillway tunnels. Expensive, but those liners might be needed many places.

Here, bare concrete over bad rock failed even before significant emergency flows were needed in a spillway - for a dam designed 30+ years after Hoover. Doesn't speak well for "lessons learned" and "better design analysis" for the dam industry over the slide rule era. Now, in the computer era, what else do we "not know we don't know"?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The damage observed may portend future damage due to climatic changes. Now is the time to examine the issue, not when it occurs.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Quote (https://en.wikipedia.org/wiki/Stepped_spillway)

Historical developments
Stepped spillways, consisting of weirs and channels, have been used for over 3,500 years since the first structures were built in Greece and Crete. During Antiquity, the stepped chute design was used for dam spillways, storm waterways, and in the town water supply channels. Most of these early structures were built around the Mediterranean sea, and the expertise on stepped spillway design was spread successively by the Romans, Muslims and Spaniards.
The solutions may not be that new.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Air bubbles, purposely injected, help mitigate cavitation by limiting the minimum bubble size during collapse, and thus the peak pressure in collapsing bubbles. I.e., if you have air bubbles before cavitation onset, then the original bubbles grow under low pressure (cavitation) conditions, and upon collapse don't get much smaller than they started - and the air that was originally in the bubble acts as a spring, limiting peak collapse pressure. Conversely, in bubble-free flow, cavitation bubbles are filled with water vapor only, and upon collapse, the water vapor returns to liquid, the bubble becomes infinitely small and the peak pressure ridiculously high. See https://en.wikipedia.org/wiki/Cavitation and its references, for starters.

As for your comments, racooke, agree mostly - except that the use of stepped (aerated)/baffled/energy-dissipating spillways has been a thing since 1880 at least. One can only surmise arrogance and ignorance of the designers precluded such designs at Oroville.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Following the stepped spillway link, one can arrive at an entry for the Gold Creek Dam, which bears eerie similarities to the extant dam, and was first built with a simple chute spillway, which failed when actually used, in 1890.

I don't think the root cause is repeating history that you didn't study, or even arrogance; it's simple economics. A straightish chute is certainly cheaper to build than any sort of stepped structure, and the MBAs who typically end up steering projects would openly scoff at any assertion that tiny bubbles could eat concrete, and publicly deride any engineers who spoke up, while secretly figuring that:
- thanks to drought, the original design would 'function' long enough to deflect blame.
- once the used food hit the fan, the problem would be big enough to justify emptying bigger pockets.




Mike Halloran
Pembroke Pines, FL, USA

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Yeah, probably right Mike, except an 1890 failure is fairly easy to describe to pesky dis-believing MBA's, one would think.

... MBA's again, where's Snorgy?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I think way back people at projects from a different angle as what we do today. Seen it in some dams built by Even large foreign companies in AFRICA. The project was kept within the budget, no matter what come up. Then 20/30/40/or like in the case of KARIBA, 60 years later, it become somebody else's problem. Same story there. Cavitation was the main culprit and now to repair will cost 100,s of millions dollars. And in some cases, it was a case of lets take the money and walk. Again, making it somebody else's problem. Do anyone know what is the cost to date more or less on this episode on the spillway(excavations on soil washed into the river below). Then not to talk about the repairs. As I can see, this will not be cheap if they want to do it properly and repairs that last. I still try to work myself around the drainpipes under the spillway. My design might be much more expensive,but I guarantee that it would have been still cheaper then all this repairs to date.
Link to the KARIBA project. Problem described on page 16
https://c.ymcdn.com/sites/irmsa.site-ym.com/resour...

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Construction projects have been falling down since the "Bent Pyramid" began falling apart because it was sloped too strongly.

But... The "theory" of massive, unconstrained random and turbulent (but I repeat myself, don't I ) water flows down a "simple" spillway MUST BE better evaluated, or we will lose the dams right at the very point when they are at extremely high levels with uncontrollable waters going down the spillway.

Compare it to a high pressure boiler or pressure vessel. Two relief valves are mandated by law, and by common sense. By law and by common sense, we do not operate pressure vessels above their maximum design pressure. BUT.

We cannot "regulate" water flows during flood conditions into a dam. We can, at best, make estimates of the maximum expected water flow and maximum expected snow pack levels and maximum allowed water levels before the rain begins and before the snow pack begins accumulating. We cannot "stop" the flood before, during over after the rainfall, nor prevent more water from coming downstream into an overloaded dam. We have a "pressure vessel" that - basically - is uncontrollable.

But that "pressure vessel" has been built with a relief valve that not only has never been tested under real world conditions, but cannot be tested before it is needed, and consistently, when that "approved officially designed" relief valve HAS BEEN used, it fails more often than not in most of the dams around the world!

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

There's been a lot of supposition that "cavitation" is the problem, which remains to be proven. Note that when the spillway was used c2006, with high flow rates, there presumably was not a specific problem associated with the spillway, since it was then used in 2011 with no obvious deleterious effects. The initial hole development occurred with only 40-60 kcft/s flow for less than a day on 2/6, and that was a fairly substantial failure of the spillway surface, which then caused a shutdown of the spillway. Prior to that, the flow had been 10-30 kcft/s, on and off, for almost a month, but it was mostly at or under 20 kcft/s until 2/3.

It seems to me that the damage had to have been from the drought and the heavy rains this year that undermined the spillway, just simply because there hadn't been any sort of flow that would have experienced much cavitation prior to 2/7, going all the way back to 2006

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I also suspect that the state dam operators were victims to some extent of the 'drought mentality' in California these past several years.

A year ago, during the 2015/2016 rainfall season, we were supposed to get an unseasonable amount of rain due to the so-called 'El Nino' effect, but it never really materialized. The levels of the major reservoirs were allowed to fall in anticipation of the heavy rainfall that never came and so it was a struggle all summer to keep water available for the farmers and the municipal water districts (which some politicians used to make their case, particularly with farmers, for getting rid of state and federal water conservation rules, with one candidate going so far as to say that if elected he would simply declare the drought over which would solve everyone's problems). Then when the rains started this past fall, the state's water managers gave orders to allow the reservoirs to fill again so that could capture as much of this early rainfall as possible in anticipation of another dry year like that last several, but as we all know now the rains continued to come in and much heavier than anyone expected, and before you knew it, places like Oroville were topping out. Granted, perhaps someone should have been keeping a better track of what was happening and been quicker to adjust their assumptions but looking back on what we had experienced statewide the last 5 or 6 years you can't help but have at least a little sympathy for the water managers and what they were confronted with. I hate to state what some will suggest is a pun, but what we had here was a "Prefect Storm".

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

IRstuff, sure one could certainly imagine that the sudden switch from extremely dried out conditions to extremely wet could well have led to erosion or subsidence or similar but I don't know about 'had to have' quite yet.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

All I was intending to say is that cavitation is a cumulation of stress and time; the fact that the surface failed under relatively low flow and duration would suggest that cavitation itself was not likely to have been the problem.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

What d-ya suppose is the reason for the quarry drill making a drill hole just up hill from the main failure. I sure hope they are looking to remove any crappy stuff under the slab in the zone above that failure and replace it, full length with hard stuff, like concrete. Take the bull by the horns there and do it right this time.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Sure, but the entire hillside is like that, so even if that section is backfilled, a different year with heavy rains might washout a different section of spillway.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Just a observation from studying the various photo's ,it is clear that the composition of the material in that hill is not stable, nor solid granite. So whatever one built on top, will need a solid man made foundation. I agree with a previous poster, now it is time to redo that whole Shute. With either piling or layered compacted material at least 3 meters deep. We had tremendous success with that in other parts of the world before. The same counts for the emergency spillway. I think whatever cosmetics they apply now, will in due time, should this happen again, wash away. I just cannot see how only a layer of cosmetic cement will solve the problem there(emergency spillway). I understand what they trying to do now by filling the area up in steps, but that will be gone in no time, should there be a heavy flow again over the emergency spillway. This can be a very interesting project. I like this kind of problem, as you surrounded with obstacles and yet, there is a way out. Sort of putting a puzzle together. The other issue is to harnass the flow in the main shute. That on its own is interesting as one face various problems as you slowly increase the flow there. I just simulated it on a flow program.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

We can agree on doing it right this time, but there are the factors called money and politics. At least they are kind enough to keep us posted on the job in general. They could keep it a secret, hiding their past mistakes.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Yes this is an example of the thesis put forward by Prof Henry Petroski, currently of Duke University where he teaches Civil Engineering and History, that since most civil engineering projects are paid for with taxpayer's dollars that the requirement to let the contracts to the lowest bidder will eventually result in the inevitable engineering failures. It's the nature of the process, but that we can learn from this because when a failure does occur, it establishes what it meant to go "one step too far", and that engineers need to learn from these failures to determine what is the appropriate level of safety that has to be laid down as the minimum below which no project can be taken irrespective of what the political or monetary pressures might be. He covered this in a series of books, several of which concentrated on public works such as bridges and public structures, like arenas and such.

Note that I've read several of his books including 'To Engineer Is Human: The Role of Failure in Successful Design' and 'Design Paradigms: Case Histories of Error and Judgment in Engineering' both of which included extensive discussions about the limitations imposed on public works projects and how engineering failures are often the result of compromises having been made by public officials and/or to live within the funding of such projects.

https://en.wikipedia.org/wiki/Henry_Petroski

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I've long figured that we'd save money on projects and get a better result in the end by going with somebody other than the lowest bid. Even taking the second low bid would save a tremendous amount of heartache;
nobody would be able to buy the project, the best they could do would be to get out of somebody else's way. Even better, with a good field of bidders, would be ignore the bottom and top bids and then take the bid
closest to the median (or mean) of the remaining bids. At that point you're getting somebody that spent some time trying to understand the project and put some effort into trying to coming up with a number that
makes sense. It seems to me that it would be impossible to game that without extensive collusion among (nearly) all of the bidders.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Even better might be to have the resources to properly review the bids for things like technical compliance, past performance history and all the other stuff beyond simple price. Then out of acceptable bids determine which is the best value.

Of course, doing so objectively and thoroughly is pretty tricky.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

These last few posts raise the issue of awarding construction contracts to the lowest bidder. The builder of this dam may indeed have been the lowest bidder, but I don't think we have any evidence at hand to suggest that the construction was not accomplished in accordance with the design.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

@KENAT:

The most successful major project tender evaluations that I have seen have split the process into two teams - Technical Evaluation, and Commercial Evaluation.

Bids are received in two separate packages - Commercial, and Technical.

The Technical Evaluation team don't know the prices of the bids they are looking at - they simply assess whether the Tenderer has the capacity to undertake the work, whether the bid is conforming, and if not, whether the non-conformance is acceptable. If it is considered to be unacceptable, a request is sent out for a revised offer which conforms with the requirements - and again, any price adjustment is passed on to only the Commercial Evaluation team, NOT the Technical Evaluation team. If a non-conforming offer is deemed acceptable, all Tenderers will be notified of the nature of the non-conformance, to allow them to adjust their offers so as to not be disadvantaged. Only conforming or acceptable bids are considered further.

The Commercial Evaluation team assesses only the contractual and commercial matters, including any price adjustments required to bring the bid to technical conformance. Any bid which has suspect commercial capacity, IR, Safety, QA, etc is eliminated from the evaluation process.

Only bids which are both technically sound and commercially sound are left on the table - and the lowest-priced, commercially acceptable, technically-acceptable bid wins the contract.

This process has worked very well on large projects I have seen (power stations, dams, etc), but it does require a level of competence and diligence that seems to be missing in many public projects these days.

http://julianh72.blogspot.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

jhardy, even there the issue of 'best value' isn't fully addressed.

Consider a vendor who perhaps proposes a design with a higher life or some such spec beyond the minimum required for a relatively small price delta compared to a company that barely meets all specs for a slightly lower price.

There's a good chance the former is actually better 'value' but even your process may not appreciate that.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

In all honesty, you really need to read Petroski's books (or at least the second one I referenced earlier) to understand what his thesis is and it doesn't really have to with sloppy construction or even that the lowest bidder was under-qualified to do the job, but rather that until something fails there is very little that we can learn about what it would have taken to not fail. In other words, we learn much less than we think we do when something does NOT fail and works exactly as it was expected to. It's only when something fails that we learn that we have gone too far. His thesis basically postulated that over a period of time, as public works projects are completed, say a series of similar large bridges over a 70 or 80 year time span, that each subsequent contract bid will be based on the success of the last bridge but with the added pressure from those who will be financing it that perhaps that last project was a bit over-designed and so the tendency is to trim the 'margin of safety' just enough to demonstrate an appreciation for the need to get the most bang out of the taxpayer's dollar. But eventually you will trim it just a bit too much like, in that old adage about "the straw the broke the camel's back".

One of the examples that Petroski used in his book was the Tacoma-Narrows Bridge (AKA "Galloping-Gerty") in Washington state. Up until that bridge was built NOT a single large suspension bridge had ever failed. And NO large suspension bridge has failed that was constructed AFTER they learned why the Tacoma-Narrows Bridge failed. After nearly 60 years of successful construction of suspension bridges, starting with the Brooklyn Bridge in 1883, with each subsequent suspension bridge becoming more elegant and lightweight, until 1940 when the Tacoma-Narrows Bridge was finished. It doesn't take much of an expert to look at how suspension bridges evolved over that 60 year time span to see that Petroski's thesis has been borne out.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Kenat:

Although the model presented may have a couple of 'holes' it appears to be a basis to work from. It is much better than the 'lowest bid' approach.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I seriously doubt that anyone dealing with a multi-million dollar project is simply going to take the lowest bid without doing some level of due diligence. While few go to the levels outlined by Julian, we, as professionals, have to go through the technical proposals to ensure that the proposer is at least competent, and at least compliant to the KPPs. And certainly, in government, CYA is a major factor, so lowest bid is not guaranteed to win unless there's an extremely high confidence that the contractor can pull it off. If anything, CYA automatically dictates that lowest bid gets tossed out, along with highest bid.

Examples from aerospace/defense that I'm aware of

> We bid against a competior for the very last buy of a large subsystem and underbid the competior by a significant amount, and they had never built anything in that class of subsystem before. Nevertheless, they won, and wound up having to get help from us afterwards. CYA says that we were a totally bad risk for the contracting officer in charge because we had just gotten fined for falsification of test records in the year leading up to the RFP.

> We bid on a system and were probably 50% higher than the incumbent, but we won. CYA says that the incumbent had serious issues in the past, and we were later told by the customer that our proposal was substantially superior to the incumbent's, particularly in the area of a single KPP that was actually erroneously specified by the customer, which we caught and proposed a much tighter requirement that was correct for the intended application.

> In one case, our dreaded BD folks decided to drastically underbid on an effort that we had previously briefed a higher amount to the customer. The contracting officer did not do their due diligence, and didn't listen to CYA and awarded us the contract, which we promptly overran. The contracting officer was summarily fired from the program, although our BD folks escaped unscathed. To make it worse, the contracting officer took his windfall and funded a competitor, who later ate our lunch, and the program itself wound up getting mothballed.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Engineering can be a gamble to some extent, can't it? I read 'To Engineer Is Human: The Role of Failure in Successful Design' some years ago. But I recall a basic premise being that lots of people can design/build big strong (i.e. expensive) things that won't fail. But the art of engineering is designing things that are right on that edge (with acceptable factors of safety of course). Which is one of the main reasons we have failures.

Another fun read I covered at about the same time, while not directly related to this incident, was Mark Eberhardt's 'Why Things Break: Understanding the World By the Way It Comes Apart'. It was a good bridge for me to a better understanding of the principles of materials science.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"All I was intending to say is that cavitation is a cumulation of stress and time; the fact that the surface failed under relatively low flow and duration would suggest that cavitation itself was not likely to have been the problem."

How well was the spillway inspected for damage after the prior usages, and were repairs made? How good were the repairs?

This is an open flow channel at a very steep grade, flow will be supercritical at almost any discharge (see the capillary waves running down the slope at near-shutoff when the inspectors are futzing in the chasm?), velocities of the flow will be high enough, somewhere on that steep grade, to reach cavitation at small surface aspherities. I.e., it's a given, not a maybe. The thing would have to be smoother than glass to avoid cavitation, and even then I'd not be certain.

I don't disagree that other factors could be involved (subsidence of underlying layers, lack of reinforcement, loss of seal at expansion joints...) but without due consideration of fluid mechanics, fixes that ignore it won't work.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Almost like you would want to begin designing these style "open-flow" unconstrained spillway floors and walls like an inverted planing surface: Complete with multiple, small-height, slightly-angled but sharp-edged "steps" with air flow allowed back underneath the liquid mass possible from the sides.

Instead of a high-speed small boat continuously but steadily "bouncing" off of a still (ideally smooth) water surface, you'd have a still surface with a high-speed water flow going over it.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

IRStuff:

If the instruction to bidders contains the methodology for acceptance, it may be easier to disqualify an unsuitable bidder. The owner can be exposed to litigation without a 'real' reason for rejecting a bid, after a contractor has invested a substantial cost in preparing it.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

The last time the spillway was used to any extent was 2011, but the water level has been past the spillway gate in 3 of the intervening years, during the spring/summer melt, and one would expect that they would have done at least a cursory inspection in each of those years, which includes 2016. What's unusual this year is that the water level hit the spillway by the end of January, which means that this was local rainfall induced, as opposed to snowmelt induced. Therefore, the most likely explanation is the heavy rainfall undermining the spillway, particularly since the spillway surface broke in the first week of February, before the spillway really got much use, so just the 20,000 to 30,000 cft/s flow was enough to break the concrete, which ought not have happened without undermining of the ground underneath.



It's actually trivial to reject proposals; we recently got rejected because of a nitnoid in the presentation of a part of the cost data. That could have likewise been trivially
fixed, had the customer been interested in keeping us in the competition. Any halfway decent boilerplate will have lots of opportunities to miss a requirement that can get you rejected.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

In one of the movies shown by Juan the-777-longhaul-pilot the concrete looked to be pretty thin in the
area it failed. Everywhere else it was about 3 feet thick but right-of-center it looked to be only about
half that.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

dik, sure jhardy's approace is much better than lower price. And given that some aspects of 'better value' can be subjective is probably the best you can hope for in many circumstances.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Seems to me that the thickness variation is simply a reflection of the fact that the hillside wasn't level and couldn't be made level, so the concrete was simply poured to level out the hill. The fact that parts of the hillside that are severely washed out, but were the last parts to lose the concrete says that any water intrusion under spillway was likely to essentially create sinkholes.

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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

IRS Stuff:

Note that the side wall discharges from the under-slab herringbone drainage system ran pretty full. The crappy sections of "rock" under easily eroded from seepage water that leaked down through the many cracks and joints. Note now they are trying to seal those cracks., More band-aid type repairs rather than a full replacement and correction of the poor zones underneath.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Kenat.... agreed...

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Juan(Browne)-the-777-Pilot also moonlights at a local civil engineering firm so he knows what he is looking at, what to look for and what questions to ask. I really appreciate his perspective on this thing.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

My 2 cents.
Two issues I have with this design or rather, end product. sometimes the design and end product separate paths due to financial issues.

The emergency spillway seems to be more or less at the same height as the whole area where the parking area is. What bothers me about this.?

1. Whatever water flows downhill in a uncontrolled way, will cause erosion parallel to the mount of water and time period.It is as if somebody decided that there will never ever be a need for water to flow over it. Big mistake when it comes to us nature of harnessing nature. If you do not plan and most important,spend good money on your idea, nature will win,time and time again.

My solution, lower the emergency spillway be two or three feet and side channel it into the main shute. Unless they apply cosmetics all the way down, this will cause problems, if not serious corrosion,still mud into the river,oh,then they need to catch all the fish below again to save them.smile)

Main shute. Two issues I have. Not so much volume but the change in angle halfway down. Use specialized methods and remove some of the rock formations, reduce the curve radius, pay attention to energy dissipation and create a proper still basin that do not obstruct the flow from the powerhouse if max water is released.

Will still be miles cheaper then all the money this issue cost up to now,and which can and will repeat itself with their band-aid repairs(quote toe word from a previous poster who nailed it).
Lets just take the evacuation in its own. The loss of income and all other issues and expenses.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

From WIKI:
"Stepped spillways, consisting of weirs and channels, have been used for over 3,500 years since the first structures were built in Greece and Crete...........
Although the stepped spillway design was common up to the beginning of the 20th century, a lot of expertise has been lost since, and the present expertise is limited to very simple geometries, namely some flat horizontal stepped prismatic chutes, despite some recent interest in stepped spillway design.
"

Those who do not learn the lessons of history.........

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

another 2c or 1-1/2 CAN:

Water flowing over a lip will create a certain curvature determined by gravity. My understanding, from earlier hydrology courses, was that the shape of the concrete spillway should mimic a curve equivalent to 0.8 to 0.9 of the gravity value to ensure that the water has a direct positive bearing contact with the concrete and cavitation is avoided. Alternatively, the spillway should have energy absorbing blocks to create turbulence. (Caveat - did all my undergrad work in hydraulics, but, have not worked in that field).

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

They fired up the spillway again yesterday and plan to run it for three to four days. Great video of the restart here with other updates:
https://www.youtube.com/watch?v=kQe0J5NLLT4

Some highlights. They can only operate at 40,000 to 50,000 cfs now. Less than that and they have too much headcutting. More than that and well...

They shored the whole thing up with grout, crack sealing, and rock bolting. The latter focused on stabilizing the left wall which had started to show some movement.

They have a burn rate right now of about five million dollars per day.

They are evaluating two alternatives for the long term repair, and have already mobilized rock crushing and concrete batch plants. They expect to have a design finalist in two weeks. The new spillway may have much less capacity which will limit their ability to use the reservoir for water supply.

The power plant has to be taken offline during spillway operation as the tailwater still rises too high.

They expect to have 3-4 more releases like this over the course of the spring.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Now maybe they are starting to9 do things right. A small length core (maybe 5 feet) as visible in the storage box (yesterday photo) show pretty crappy looking stuff. Could this be interpreted that the full length of spillway will get replaced on top of corrected support by hard material rather than rotten rock? The core location appears to be on higher ground, possibly near the inlet gates. Getting rock cores for the full length of the spillway should have been a complete job way back when things were built. Better late than never.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Oroville reservoir dynamics in a nutshell: http://cdec.water.ca.gov/river/res_ORO.html

Looking at the top left graph of ORO inflow can anyone explain to me how these major daily fluctuations occur? I can only
imagine one slow increase/decrease over 24 hours and don't know why there would many large excursions a day. I don't
recall ever seeing a river flow go up and down 400% several times a day.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I haven't looked at the data, but an upstream hydro plant would be an easy explanation. There's a wide range of water flow from plants that aren't run as run-of-river. I've even seen advertisements for a white water adventure on some river back east the seems to be timed to the afternoon ramp up of one or more hydro plants.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I would think that it's the same sort of noise issue as the other measurement you mentioned a couple of weeks ago. Note the negative flow excursions on this one as well.
The long graphs show what the general trends look like:
http://cdec.water.ca.gov/jspplot/jspPlotServlet.js...

The graph your link pulls up is a 24-hr graph. The daily flows show fairly consistent behavior:
http://cdec.water.ca.gov/jspplot/jspPlotServlet.js...=

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

hmmm. Interesting.

I'm realizing that it's not just the Feather River but actually the Feather River and several tributaries all
running thru the Sierras that add to make the flow reading. I'm thinking the daily warm up / freeze down would be
affecting all the various tributaries at pretty much the same time every day but the actual time the water takes to
travel the hundred mile type distances could have a prior high flow at a particular drainage showing up many hours
later causing various staggered patterns at the near reservoir flow sensor.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

davidbeach - I was over in Tennessee a number of years back and went white-water rafting on the river you're talking about, the Ocoee River. It's the same river where they ran the kayaking events for the Atlanta Olympics.

I was in the very first group in the morning and we had the strangest experience. When we pulled up to the river to get into our boats, the river was raging like any other whitewater rafting river. As we paddled downstream everything seemed normal, but when we rounded one of the river bends we could see the entire downstream river bed was bone dry. We had caught up to the leading edge of the water flow! We had to pull into an eddy for about 15 minutes before we continued down the river. We had to do this about 3-4 more times during our run as we kept catching up to the flood.

Fun river otherwise, just a strange experience.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Sort of like surfing the river edge.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Here's a link to a 'live' webcam from the Oroville Dam:

https://www.youtube.com/watch?v=sqADyf9l99I

I realize that I'm posting this while the sun has just set in Northern California but perhaps tomorrow morning it will be worth watching.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

marty007, I hope you had fun, but what I was referring to was something on the Mohawk or Hudson (or a major tributary).

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Ah, that would definitely do it.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Mtown's posted pdf file includes this comment from said consultants at page 7:

"Chute Spillway [Gated Spillway]. The chute spillway [Gated Spillway] has operated many times since its completion in 1968. Although the floor of the spillway chute [Gated Spillway] in this section has experienced a good deal of spalling and cracking, there has been no significant damage. The cracks and spalls have been repaired several times."

I.e. the floor of the spillway has been accumulating damage (spalls and cracks) every time it is run, likely from cavitation. "No significant damage" is a phrase that just sets off alarm bells for me, it is just too similar to the language used by NASA prior to (and in some cases after) the Columbia shuttle disaster. "It hasn't failed catastrophically yet"

Underfloor leakage (side drains run full when the spillway gates are opened) and subsidence is also noted, but the source of that water is not clear, but is likely moving through cracks and leaking expansion joint seals along the floor of the spillway. I.e. cavitation damage leads to leakage, leads to subsidence and further slab breakup, more cavitation and erosion, and a literal cascading disaster develops...

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I read that as simply saying the concrete had not aged very well. When I read it, I had believed it said the remaining floor simply wasn't in good condition. Another part indicated the concrete was thin above each drain pipe and in certain other areas. It read like poor initial construction was the root cause moreso than anything else. It also seems the chute is going to be re-built, but done better this time.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

ditto, John. A good clip.

Dik

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Love his appropriation of the closing cord from "a Day in the Life"! The Albert Hall is not amused.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

There is a Viewpoint article in the latest Engineering News Record that is very misleading and, in my opinion should not have been printed. Take a look at it and the headlines. How to Fix Oroville Dam. makes it look simple when it really isn't. The reference is not a complete copy of the article. See the actual magazine to read it all.

http://www.enr.com/articles/41664-how-to-fix-orovi...


RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"As an experienced civil engineer, I would like to make one point very clear: Oroville Dam was never in danger of failing."

Isn't the emergency spillway part of the dam? When the wall was overflowing and it appeared earth around the wall was washing away, was it not conceivable that the wall could have failed? No-one could see what was happening exactly or what damage was being done while it was overflowing. Should the authorities have erred on the side of caution or not?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I think it's obvious that the author was referring to the main structure of the earthen dam itself.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I consider the overflow wall to be part of the dam....

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"was it not conceivable that the wall could have failed?"
The failure concern was only the wall height between the normal spillway and the emergency spillway, which would have released 30 ft of water. The "dam" itself was going to be intact, retaining a few hundred feet of water that's below the normal spillway.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

My reason for posting the discussion section from the ENR WEB site was the fellow's off hand cure for the problem, which was printed in the final section of the magazine's article that didn't get carried to the discussion WEB pages. I felt the apparent endorsement of an idea by a national engineering magazine was a mistake. A simplified "cure" or "fix" (calling for a second service spillway at a predetermined location) dismisses all the side issues, all of which played a role in the failure and should be handled with any fix.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

There has always been a semantics issue with this event. The media talking about "dam failure" where
the entire Oroville staff understands the dam to be the actual man made gravity dam. Their
hackles go up every time someone sez the dam was about to fail as it wasn't ever about to fail.

Meanwhile, others consider "the dam" to be the entire reservoir containment. The 'reservoir
containment' was indeed threatening to fail due to foot cutting while the emergency spillway was
running - enough of a threat to panic evacuate 150k people.

And, "only the top 30 feet" is a total joke as having 'only' a million acre feet of water rushing
uncontrolled across any part of the reservoir's containment would have cut clear to the bottom exactly
like the main spillway's misguided water did.

BTW:
Oroville Update!! 4 April A closer look at the spillway

And
Oroville 6 April Update New Drone Footage and Press Briefing
Which announces today's 2 o'clock PST press briefing by the DWR.
Very cool drone footage!

That press briefing by the DWR is in 20 minutes!

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Here is the section of the ENR Opinion page that I object to. Makes it look too easy.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Thanks Keith for pointing out what I thought was somewhat obvious.

If that spillway wall did fail, does anyone here actually believe the earth below wouldn't be eroded as that much water washed uncontrolled over that area? There is no possible way anyone can say that if the wall had failed that "only" water the height of the wall would be released.

And even if the earth miraculously wasn't eroded, does anyone here actually believe that only 30' water quickly leaving the reservoir wouldn't be considered a catastrophic failure of the dam? A dam is basically a structure built to hold back water, so I consider the overflows as part of the dam.

oldestguy - yes, he made it out to be simple to fix, when it's not. I really didn't find it a big surprise after his rather dubious claim right off the top.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Oldestguy,

What is wrong with building a new spillway away from the old one - would that not allow the old spillway to operate if the new one is (inevitably) delayed in completion?

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Sacramento Bee video of press conference:
Scroll down front page

http://www.sacbee.com/

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Bill Croyle, acting director of Department of Water Resources, explains the current plans to fix the Oroville spillway and the emergency spillway. Video by Randy Pench Produced by Sue Morrow

Read more here: http://www.sacbee.com/news/state/california/water-...
OROVILLE
State officials sketched a two-year recovery plan Thursday for the battered Oroville Dam spillway, revealing a blueprint that's far from complete, still in need of a price tag and certain to leave the structure partially damaged as the next rainy season approaches.

The plan unveiled by the Department of Water Resources will proceed in phases and won’t be finished until 2018. Notably, the giant ravine that's been carved out of a nearby hillside, the result of water boiling out of the fractured spillway in recent weeks, could be used again next winter to handle excessive water releases.

Nonetheless, Acting DWR Director Bill Croyle said the 3,000-foot-long chute will be functional next winter.


Read more here: http://www.sacbee.com/news/state/california/water-...
The repair plan was released nearly two months to the day after a giant crater erupted in the dam's main spillway, eventually triggering a crisis that forced the temporary evacuation of 188,000 residents.

Croyle acknowledged the plan is a work in progress.

“We have a little less than a 60 percent design,” he told reporters. Nonetheless, the project is being circulated among four contracting firms, and DWR expects to execute a contract by April 17. The firms weren’t identified.

“We’re moving as fast as we can. We need this (contract) in a matter of hours or days, not weeks or months,” Croyle said.

Croyle said he was unable to provide a cost estimate beyond his original projection nearly two months ago that it would take up to $200 million to repair the structure. President Donald Trump made a disaster declaration over the weekend that’s expected to free up approximately $274 million in federal funds for Oroville repairs, although much of that money is being spent on debris removal and other functions not directly tied to repairing the spillway.

Gov. Jerry Brown moved to expedite the project Thursday, signing an executive order that waives state environmental laws and other red tape. Nonetheless, Croyle said DWR will be as sensitive as it can to environmental issues as work progresses.

The crater that erupted Feb. 7 essentially split the concrete spillway in two. Water gushing down the spillway, misdirected by the giant chasm, carved an enormous ravine in a nearby hillside.

Croyle said DWR plans to leave the ravine in place this year. It could serve as a kind of auxiliary outlet in case the reservoir is rising too high and the concrete structure, despite its repairs, can’t handle excessive water flows.

The lower spillway itself will be “demolished and replaced” over the summer, said DWR chief engineer Jeanne Kuttel. “It will be stronger than it was before,” she said. The state plans to use quick drying “roller compacted concrete” on the lower portion of the structure, she said.

Croyle and Kuttel said the upper portion of the spillway, although undamaged, might be partially or completely replaced this summer as well. However, recent geotechnical studies have shown much of the upper spillway is thicker than previously believed, and might not have to be replaced, Croyle said.

Croyle acknowledged that plenty of work will be left over to 2018. That includes building higher retaining walls alongside the concrete chute to handle extremely high flows.

OROVILLE MAIN SPILLWAY REPAIR PLAN
Multiple designs remain under consideration because of uncertainty about how spring weather will affect the construction timeline.

Diagram of spillway repair plan Source: Calif. Dept. of Water ResourcesNATHANIEL LEVINE nlevine@sacbee.com
Meanwhile, he said DWR plans to partially line the adjacent emergency spillway with concrete this summer – a first for the structure.

The emergency spillway turned out to be the weak link in the February near disaster.

After the main spillway fractured, it was shut down temporarily for inspection. Inflows from a heavy rainstorm spiked water levels at Lake Oroville to unprecedented levels, and water poured over the emergency spillway – a concrete apron perched atop a hillside – for the first time since the reservoir opened in 1968.

A day later, engineers discovered that the hilllside was eroding so badly that the concrete apron might crumble, unleashing a “wall of water” into the Feather River below. That sparked the evacuation of 188,000 downstream residents Feb. 12 until lake levels receded and the situation stabilized.

Butte County Sheriff Kory Honea, who ordered the evacuation, said he was encouraged with the progress on the repairs. “We’re moving from an emergency crisis management mode to a recovery mode,” he said. “We are in a much, much better position today than we were on Feb. 12th.”

Croyle said DWR, in consultation with the sheriff, won’t make bid documents public because they’re considered “critical energy infrastructure information,” and could be used to create “harm and havoc.” DWR cited the same explanation for sealing several investigatory documents with the Federal Energy Regulatory Commission last month. FERC licenses the dam and is overseeing the repair effort.

An earlier document, from a team of consultants hired by DWR to advise on the repairs, said fixing the spillway in one year would be nearly impossible because of design flaws and the severity of the damage. The report was the first sign that repairs would continue beyond 2017.

Croyle said that first report “shouldn’t have been made public” and DWR will make sure future reports by the consultants stay sealed.

Paul Tullis, an engineering consultant from Utah who has studied spillway designs, said DWR's approach to the repairs seems reasonable, given the impossibility of completely fixing the structure in time for the next rainy season.

"There's only so much they can repair in a half a year or so," Tullis said. "They can only do what they can do."

Tullis said it will be critically important to monitor the hillside next to the main spillway next winter if DWR has to let more water flow through the recently-carved ravine. If too much of the hillside gets washed away, it could potentially harm the earthen wall of the dam itself, he said.

The spillway has been shut off since March 27 for temporary repairs. As raindrops fell outside the giant tent where he briefed reporters, Croyle said he believes the upcoming storm won't raise lake levels to uncomfortable levels, even with the spillway not releasing any water.

He added that the spillway will probably be used once or twice more this spring, depending on how heavy the runoff gets as the Sierra snowpack melts. Before long DWR plans to shut it down for good to begin the major repairs.

Dale Kasler: 916-321-1066, @dakasler


MY FEED

Read more here: http://www.sacbee.com/news/state/california/water-...

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

"does anyone here actually believe the earth below wouldn't be eroded as that much water washed uncontrolled over that area?"

That presumes that it's "earth." The dam itself is earth-filled, but the spillway is on part of the original landscape, which is rock, some crumbly, some not.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I am using this definition. Earth - the solid matter of this planet making up the surface. Is that good or is more nitpicking necessary?

Whatever you wish to call the earth/rock/soil/dirt in that area, it quickly eroded both when the main spillway failed and while water flowed over the emergency spillway. To me, it seemed rather obvious that it would also erode if a 30' high wall of water 1700' long started washing over it, leading to far more water then the often quoted 30' actually being released.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Oldrunner thanks for the great summation of The Plan.


I just lost a lot of respect for Croyle with his moronic, "Croyle said that first report “shouldn’t
have been made public” B.S.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

It's official, at least for Northern California; this is the wettest season since they've been keeping rainfall/snowfall records:

Wet winter sets precipitation record in Northern California

http://www.latimes.com/local/lanow/la-me-ln-califo...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

2
A Report by Robert Bea of the Center for Catastrophic Risk Management at UC Berkeley gives a few reasons for the failed spillway. Design, construction, and maintenance defects and flaws where all blamed in the preliminary report. Lots of good pictures and analysis in the report.

http://documents.latimes.com/report-finds-serious-...

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

That is a great report. Thanks for sharing!

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

This report is excellent. Here's the link to the 2014 Bureau of Reclamation document referenced.

https://www.usbr.gov/tsc/techreferences/designstan....

Page 3-160 is very interesting because Oroville get very very hot.

There is a wealth of information in the Bureau's document because it shows other failures. I worked on the construction of the spillway of Mangla Dam in 1963-64, but don't know what the spillway thickness was. Tarbela Dam which was constructed a few years later appears to have had a spillway thickness of 24".

On page B-9 is the cavitation damage at Glen Canyon spillway tunnel. I had not seen this before but our firm provided the design for the work platform on the slope (Guy F. Atkinson project). For some reason I was told that the damage was in the ceiling so seeing the damage at the bottom of the tunnel was a unpleasant surprise.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Now fellow engineers. Looking back is always interesting, but now what to do? My suggestion is start over and do the whole spillway right this time.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

Well, if this was now my job, I would do the following. First off to my computer. Take the current spillway design and load it into a amazing program called 3D-FLOW (I am not working for them, heheheheh)and draw profiles at different flow rates. Then get the optimum design pattern which give satisfactory results where cavitation is none and water speeds do not go beyond 12 to 15 meters per second by playing with aerators positions and quantity. Then start at base level and get a smooth foundation level(specialist blasting methods is capable do that relatively very quick. Fill all voids with compacted and tested soil at max compact resistance. Dowels should form a inverted u shape. Redesign the spillway according to the profiles drawn up in 3D, and add a mix of around 6 kg 50 mm macro fibre per cubic meter concrete. Additional to my steel schedule. Lots of concrete and steelbut no brain drainer and not a complicated construction. Most important, keep your water flow rate below 12 m/s while still accommodating the flow capacity. In short and basic. The in-between cosmetics will land on the table of the structural engineers to sort out. I wish my company was close by. This is a nice project.

RE: Oroville Dam Spillway Concrete Failure (Feather River Flooding, CA)

I'd just add lots of concrete to the new right channel in the spots that dirt still exists and call
it a day. That would reduce the prep time to almost nothing so they could complete it all in a month
or two. It would look naturally great and there won't be any cavitation since the water breaks
somewhere about every 5 feet.

Admit it, it's a brilliant plan.

Keith Cress
kcress - http://www.flaminsystems.com

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