# Oroville Spillway is failing with enough rain dam may break



## buckmanriver (Apr 2, 2008)

Outflow data real time: CDEC - Data Application


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## Andy H. (Oct 13, 2003)

Man, I hope that spillway's underlain by bedrock! Better call for some RediMix, guys....


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## Pinned (Apr 19, 2012)

I doubt there will be failure of the gates but the lower spillway is likely completely gone at this point.


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## jgrebe (Jan 16, 2010)

I think Andy has it right. Not unusual to have serious erosion / damage on emergency spillways during high flow events. Saylorville 2010, and even Glen Canyon in 83 are good examples. Looks scary but what is important is that there is good bedrock structure below the spillway that will limit undermining the dam. My experience is that there generally is but guess time will tell


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## Andy H. (Oct 13, 2003)

There's a dusty old geotech report that just got pulled off the shelf and is the subject of a great deal of attention right now. 

OK, Bonus for the day - I went looking for the passage in Cadillac Desert describing when Glen Canyon Dam's spillway chutes were eroded out in '83, "the put-put of the Briggs and Stratton mowing the lush lawn over the turbine rooms..." and found this instead. Go to the Youtube site and there's a bunch more.

Enjoy!

Cadillac Desert


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## restrac2000 (Mar 6, 2008)

Wow. Watching the West cycle through decades of drought and now epic snowpack is wild. I am betting the political debate over water allotment the next few years in Cental Cali will be as turbulent as that spillway video.

Why are spillways so prone to this sort of damage? Isn't their primary purpose to be used in moments like this, ie shouldn't design incorporate these types of forces? Or are they assumed to perform well enough and repairs just assumed to be part and parcel?


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## Pinned (Apr 19, 2012)

They are not designed to fail in this or any other way at all. Unfortunately they are rarely used to capacity and are poorly maintained.


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## restrac2000 (Mar 6, 2008)

Sounds like this has potential to severely damage the nearby hatchery.

http://www.sfchronicle.com/bayarea/article/Uncharted-territory-as-Oroville-Dam-10921941.php


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## btreat (Apr 24, 2012)

*Oroville Dam Spillway breach*

With all the attention Oroville Dam is getting, here is some helpful information. The dam is offset from the spillway which runs down a natural hillside. Even the alternate spillway is far away from the dam itself. Here is a link to a descriptive picture.
Spillway crumbling but flows resume as DWR balances flood threat




buckmanriver said:


> Things are looking scary at the Oroville Dam currently as the spillway is falling apart rapidly as the lake continues to rise.
> 
> Anyone, care to chime in on with thoughts on the risk of catastrophic failure?
> 
> ...


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## restrac2000 (Mar 6, 2008)

Some of the photos emerging from the last 36 hours are just frightening. Such a rapid increase in erosion.


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## mattman (Jan 30, 2015)

Oh Wow!!
"When trying to control the most powerful force on the planet goes wrong"?!?!?


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## benpetri (Jul 2, 2004)

restrac2000 said:


> Why are spillways so prone to this sort of damage? Isn't their primary purpose to be used in moments like this, ie shouldn't design incorporate these types of forces? Or are they assumed to perform well enough and repairs just assumed to be part and parcel?


Cavitation is a likely cause for these types of failures. A lot of these large dams were designed and constructed back in the 1950s or 60s or earlier, before engineers had a good understanding of cavitation and how to prevent it. Spillways can probably be retrofitted to prevent this, but it requires some infrastructure spending. Spending on such infrastructure has largely dwindled since these dams were built. For what money is spent on dam upgrades, my guess is that the Army Corps and other agencies that manage dams prioritize their projects based on risk. Overall, Army Corps is addressing some serious risks (e.g. seismic, flood, stability, etc.) at other dams and I don't know where spillways fall in the priority list.


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## Raft Dad (Jan 20, 2017)

*Evacuation order issued*

Just reading on the CBC (Canadian) website that an evacuation order has been issued downstream of the Oroville due to believed imminent failure of the spillway. Stay safe folks if your in the area.


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## Electric-Mayhem (Jan 19, 2004)

They are saying the Emergency spillway is on the brink of failing. Its not the main one shown in the pictures above. The report I read says they are gonna put more water down the main spillway so that less goes down the emergency one but its still pretty tenuous. Damage to the main spillway is still a worry and with more water will be accelerated.

It will be interesting to see what happens with it. I'm glad they are evacuating so that less people are at risk if/when it fails.


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## BmfnL (May 23, 2009)

Here's some local news for a live feed:


https://www.youtube.com/watch?v=vwIst1YiMdo

This is gut wrenching.


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## BmfnL (May 23, 2009)

Another news link:

Watch KCRA Nowcast Newscasts Live and On Demand


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## restrac2000 (Mar 6, 2008)

I hope any MB folks in the area are safe. Its tough to know how timely the news alerts remain but it sounds like the evacuation orders are creating some chaos.

They are saying 100,000 cfs is going down the main spillway. Sounds like they are trying to shore up the breaches on the emergency spillway.

Sounds absolutely frightening.

Phillip


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## crispy (May 20, 2004)

they should have just put up plywood like at glen canyon in '83...


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## richp (Feb 27, 2005)

Hi,

It does look like they could have gone to school on Glen Canyon '83 when it comes to learning how to retrofit a smooth concrete surface to resist cavitation.

FWIW.

Rich Phillips


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## restrac2000 (Mar 6, 2008)

Talking about '82-'83, the "8 station index" is showing moisture content is easily on a path to beat that season. They are forcast to get another 4-6" of rain in the storm starting Wednesday night. With saturated soils all of that is heading to Oroville. There is no way they make meaningful headway on repairs to the emergency spillway in 48 hours. 

The damage to the main spillway is continuing to undercut earth closer to the concrete dam. How much damage will it take to it or the emergency spillway to compromise the concrete structures in place? I can't imagine the number crunching going on right now to evaluate the integrity of this behemoth structure.

And to top it off, if they keep it mostly intact, the state and agencies are likely facing serious questions given the promises they made a decade ago about the integrity of the spillway structures. They were challenged to reinforce it for ba scenario exactly like this and claimed it was fine.

Epically scary when you start hearing the word liquefaction on the news. 

Phillip


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## buckmanriver (Apr 2, 2008)

Below is my take based on current data, which suggest a more positive outlook. 

Discussion welcome. 

https://www.youtube.com/watch?v=IHITD8lU51Q

Thanks,

~ B


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## restrac2000 (Mar 6, 2008)

Thanks for sharing.

Definitely seems likely, given those forecast flows, that they can get the reservoir lower. The engineering chatter i hear is definitely worst case given the number of uncertainties in weather forecasts. 

When is the historic peak inflow for Oroville? 

The part i don't have the skill to vet is the structural implications if the emergency spillway fails. Does that have any effect on the primary spillway's integrity and eventually the dam (mostly the earthen support? While it seems they can probably avoid worst case for now it seems like the issue could haunt them for weeks to months through the primary melt (depending on answer to earlier question).


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## restrac2000 (Mar 6, 2008)

Side note, as someone buying their first home in FEMA designated flood zone, i sure hope most of those folks downstream already had policies. There is a 30-day delay on coverage through the FEMA sponsored system. And i have to wonder if they will even offer new policies in the middle of a designated state of emergency.


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## restrac2000 (Mar 6, 2008)

Photo of some of the damage to emergency spillway found today.


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## Droboat (May 12, 2008)

*Cost Control Cavitated Environmental Groups' Crest Control Critique*

Oroville Dam: Feds and state officials ignored warnings 12 years ago

Three environmental groups — the Friends of the River, the Sierra Club and the South Yuba Citizens League — filed a motion with the federal government on Oct. 17, 2005, as part of Oroville Dam’s relicensing process, urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen hillside.


The groups filed the motion with FERC, the Federal Energy Regulatory Commission. They said that the dam, built and owned by the state of California, and finished in 1968, did not meet modern safety standards because in the event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause a failure, known as “loss of crest control.”

“A loss of crest control could not only cause additional damage to project lands and facilities but also cause damages and threaten lives in the protected floodplain downstream,” the groups wrote.

FERC rejected that request, however, after the state Department of Water Resources, and the water agencies that would likely have had to pay the bill for the upgrades, said they were unnecessary. Those agencies included the Metropolitan Water District of Southern California, which provides water to 19 million people in Los Angeles, San Diego and other areas, along with the State Water Contractors, an association of 27 agencies that buy water from the state of California through the State Water Project. The association includes the Metropolitan Water District, Kern County Water Agency, the Santa Clara Valley Water District and the Alameda County Water District.


Federal officials at the time said that the emergency spillway was designed to handle 350,000 cubic feet per second and the concerns were overblown.


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## restrac2000 (Mar 6, 2008)

This is the best video I have seen of the damage to the emergency spillway. And this was after less than a days worth of flow. 

https://mobile.twitter.com/Cal_OES/status/831253413253885952/video/1


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## richp (Feb 27, 2005)

Hi,

It's the erosion at the bottom right in the picture of the emergency spillway that ought to be most worrisome. 

If that continues to cut back and undercuts the concrete apron -- and they can't release fast enough from the other damaged spillway -- then the next thing to stop the flow in that location will be bedrock.

I'm amazed they are not reinforcing that area. Or maybe they are, and the photos just haven't been showing it.

FWIW.

Rich Phillips


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## Andy H. (Oct 13, 2003)

Rich, yes, that's my understanding. Once the Emergency spillway starts to erode, they estimate that it could downcut about 30 feet into the rock. If this happened, then the entire top 30 feet of the reservoir would be released in very short order as the water rushing through tore out the concrete apron and began scouring and plucking the fractured metamorphic rock. 

Here's my back of the envelope calculation:

I just looked up that the reservoir has a surface area of 15,500 acrea
Assuming the emergency spillway were downcut by 30 feet, the volume released would be about 465,000 acre-feet
If that volume were released _evenly_ over one day (big assumption), this would equate to a flow of 235,000 cfs. This is over twice the outflow they're trying to release down the main spillway. 

It's pretty likely that there would be a catastrophic failure and the majority of the water would be released within a shorter period. For perspective, if it all went _evenly_ in a 12-hour period, that would be 470,000 cfs.

Holy shit.

Here's a good blog that I've been following as these storms have been coming ashore. He gets into the FERC relicensing issue also.

Geotripper - Liveblogging the Deluge This is written by a geologist, so you know it's spot on!


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## restrac2000 (Mar 6, 2008)

They are dropping bags full of boulders from helicopters into those erosion caused gullies. Hard to believe that is anything other than a desperate stop gap. Considering the next storm is now less than 48 hours away I doubt there are any other options. 

Curious, on the main spillway they built up features to diffuse the power of the water before it hits the river. But the emergency feature is a straight drop ( i have heard 30') right into the base of the concrete foundation. Why vertical? 

Thx for the blog, Andy. Will dive into it.


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## GilaRobusta (Mar 19, 2015)

These events have fascinated me from the moment the news broke. Who needs a monkey wrench when you have FERC. I imagine things are going to be getting weird throughout California and the rest of the West if this season keeps delivering the goods.


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## Bpsig (Mar 7, 2012)

really crazy drone footage of the spill of the emergency spillway: Drone video shows the Oroville Dam crisis - SFGate


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## DoStep (Jun 26, 2012)

richp said:


> Hi,
> 
> It does look like they could have gone to school on Glen Canyon '83 when it comes to learning how to retrofit a smooth concrete surface to resist cavitation.
> 
> ...


And maybe planning too!


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## restrac2000 (Mar 6, 2008)

The photos of the damage to the main spillway after they shut off releases yesterday are phenomenal. The scale of that spillway was lost on me until I saw the helicopter in the photo. Such a massive structure.

How do they fix something like that? Not to mention all of the dredging and cleanup of the river channel so the lower power station is protected for operation.

http://www.mercurynews.com/2017/02/...stop-flow-down-spillway-see-extensive-damage/


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## badkins (Oct 30, 2003)

Great drone footage of before/during/after.

oroville dam spillway - Album on Imgur
https://imgur.com/gallery/6IyCi


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## Andy H. (Oct 13, 2003)

*Followup on Oroville*

Here's an HCN article on the expert report on the Oroville Dam incident in 2017, when the dam was nearly lost due to overfilling:

What went wrong at Oroville?

From the article:



> [The report]...describes the physical factors that caused the spillways to crumble, problems like unstable rock foundations and cracked concrete that allowed water beneath the main spillway.
> 
> The report also highlighted human and organizational errors, including faulty design details, shortsighted inspections and “overconfident and complacent” management by the California Department of Water Resources. The department “take(s) the findings very seriously,” said then-director Grant Davis in a statement. “We will … incorporate the lessons learned going forward.”


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## Andy H. (Oct 13, 2003)

More follow up on Oroville:

Two Years after spillway crumbled


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