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Discussion Starter · #1 ·
There is a catastrophe looming. The spillway is broken and dam is filling up. It will be full by Saturday.

This is the 2nd biggest reservoir in CA, after Shasta.

16507892_10154860849813213_3936172785582866385_n.jpg
The damage caused by releasing water.

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The scale of the problem.
 

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Ride On!
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Pretty scary stuff. Saw on the news tonight that they most likely are going to let it flow and deal with the damage after the rainy season. This is assuming that the 2 hr test they ran today at 4 pm went ok, guess the next decision is going to be made tomorrow A.M. The Dam does have an emergency spillway in case it is needed; it however, is not controlled by gates and could cause some flooding if used.
 

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Discussion Starter · #3 ·
Pretty scary stuff. Saw on the news tonight that they most likely are going to let it flow and deal with the damage after the rainy season. This is assuming that the 2 hr test they ran today at 4 pm went ok, guess the next decision is going to be made tomorrow A.M. The Dam does have an emergency spillway in case it is needed; it however, is not controlled by gates and could cause some flooding if used.
Yep, the emergency spillway is uncontrolled and will release a torrent of water onto the hillside with trees and powerlines.

At the current rate of inflow and outflow, Oroville is estimated to FILL UP by this weekend.

https://ww2.kqed.org/news/2017/02/07/engineers-assess-spillway-problem-at-oroville-dam/

The current hole is 30 feet deep 180' long 90 feet wide and there is no access to it with heavy machinery. The hillside is steep and there is no road.

The spillway is taller than Hoover Dam!
 

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Discussion Starter · #5 ·
Is damage caused by old age or releasing water? Neglect?
It was caused by a defective spillway and a high release of 60,000 cfs. That is a high release but the officials thought it was well within design constraints of the spillway.


The way these things go though, one small crack will degrade quickly.
 

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Discussion Starter · #6 ·

Here is the 60,000 cfs release and the subsequent crumbling.
 

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bipedal
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Wow! Thanks for the photos and video.

The dam and spillway impressive, but mother nature more so of course! There's a huge drainage area into Oroville. Hope the reservoir is not overwhelmed by the rain and snow melt predicted for the next few days.
 

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great videos & photos! really like that history channel vid. the last couple of times i headed to downieville from south bay The Google hivemind-traffic-avoidance algorithm sent me up the 99 and through Oroville across to Marysville Rd. The dam is nearby and the drive takes you across the dam top to Bullards Bar Reservoir that has an impressive spillway & viewing area too. Worthwhile drive once or thrice. Listen to the book-on-tape Cadillac Desert if you'd like to hear more about the history of California's water projects.
 

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Fart smeller
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A buddy tells me it's now 28 feet from the top. When it gets to 25, they'll evacuate Oroville.
 

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middle ring single track
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It was caused by a defective spillway and a high release of 60,000 cfs. That is a high release but the officials thought it was well within design constraints of the spillway.
Obviously something was defective; one reporter has commented about not seeing any rebar in the broken concrete of the structure (might just be a reinforcing mesh too small to see at a distance).

I don't think a 50,000 or 60,000 (I heard 50) cfs release is a "high" release (still a damn lot of water pun intended); I've read that the spillway is designed for anywhere from 150,000 to 250,000 cfs. The Feather River can inflow at 300,000 cfs per one report so yes Houston we have a problem if they can't keep the reservoir drawn down for flood control.

Google the Oroville Flood of 1997 for some photos of the spillway working at the max.

BTW +++ on the "Cadillac Desert" being a good read; 25-words-or-less it's about how SoCal stole NorCal's water and got away with it.
 

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middle ring single track
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Another interesting anecdote is that in the late '70s I was working construction in Sac Town and made friends with a Fed building inspector and we'd have lunch on a weekly basis (straight up guy, he would always pay for lunch because if I paid it could be construed as a bribe).

Anyway, one thing he got off his chest was that the rumor was that the largest supplier of ready-mix concrete in the area was cheating on the strength qualifications and getting away with it. Passing off "4-sack" as "5-sack" by post-dating the test coupons which would give it more time to cure before the test. (concrete gains strength as it cures so week-older 4-sack appears to be as strong as 5-sack) The ready-mix company was using 20% less cement which was worth millions $$$. I think he said this concrete was for the paving being used for the I5 project.

Wonder if some of this stuff was used at Oroville?
 

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Captain One Lung
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that's a big hole!!

not so sure about the concrete scandal above. the State has some stringent test all along the way. and during construction, they take samples every 150 yards and make and break cylinders at 7 14 28 days to make sure the strength curves match those in the certified test batch papers.

i do know first hand a concrete company tried to sneak in sub par recycled aggregates. this was in SF. the FEDs got involved and people went off in handcuffs. that company doesnt exist anymore.
 

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Clever Title
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As long as the damage doesn't progress upward this is not really that big of a deal. The area under the spillway clearly is bedrock (minus that upper part of soil), and the dam itself is a good distance away from the spillway. Yeah they're going to be needing some more concrete to repair it once we're out of the rainy season, but as long as that knickpoint where the break first starts doesn't migrate up to the dam itself Oroville etc downstream will be fine.

Edited to add: There will clearly be substantial cost involved in rebuilding the spillway so I'm not intending to make light of what is a serious situation, but the OMG evacuate is not a real concern from my understanding of the situation.
 
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