What's your point here? Seems to be drifting into speculation.
Oroville Dam Spillway Failure
- Thread starter Mick West
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whoosh
Member
Good lead, sushi. I searched the ChicoER archives and came up with this detail on "long time":
Spillway unused for 5 years, and only twice in 10 years, prior to spring '16.Author: By Ryan Olson rolson@chicoer.com @NorCalJustice on Twitter
Date: March 25, 2016
Publication: Chico Enterprise-Record (Chico, CA)
Article ID: 1817521
Page: 1
Oroville >> Dozens of people made their way toward Oroville Dam to see water surge down the dam’s controlled spillway Thursday.
It’s the first time the spillway has been in opened in five years to maintain storage space in Lake Oroville for flood control. Over the past 10 years, the spillway has been open for flood control just twice.
Daily outflows since 1/1/2000:
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whoosh
Member
sushi
Member
Thanks for the data whoosh. My reading of that graph is that the FCS spillway flowed for a single time in the period of March to May 2016 and then sat unused until the recent event.
JCL
New Member
http://www.gridleyherald.com/article/20170218/NEWS/170219637
When one gentleman, a Mr. King told Supervisors he had called a friend who worked on the spillway many years ago to ask what happened when the spillway was built in regards to the condition now. "My friend said "When the spillway was built we did it as economically as we could. When asked why no rebar noticed," the friend stated, "When we knew an inspector wasn't there at night we cut corners."
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SeanT
Member
If they aren't true he'll still get a visit.
sushi
Member
EricL
Member
This probably sounds great to anyone with a natural tendency to believe the worst, but even with my rather-average amount of time spent on construction sites, it sounds like a bunch of hooey.
First, within each pour section, it takes many, many times longer to set the rebar than it takes to place the concrete, so the idea that there'd be certain small windows of opportunity to avoid performing such a time-consuming operation simply doesn't make sense. It wouldn't be reasonable to think a single evening without inspection might be enough time to skip this step and get away with it.
Second, you can be sure that on a project of this type, inspectors would have been present to perform field tests on the fresh concrete and to take samples for later strength evaluation at regular intervals during every single pour. The person or persons responsible for this sampling would have noticed that something was amiss if re-bar had not been placed on some occasions, even if inspecting re-bar was not their job.
Third, the quantity of re-bar of every size and configuration would have been determined ahead of time, and the material would have been stockpiled on site before actually being used. Further, receipts for re-bar purchase and shipping records would have been part of the billing records, and these would need to match pre-construction statements as to quantity. Being "government work", this is a detail that would have been scrutinized.
Fourth, we humans are not good at keeping secrets, and with the iron-working crew consisting of at least dozens of individuals (likely more), what are the chances that they could simply skip out on doing their job on certain occasions and the word of that wouldn't leak? What are the odds that not a single worker wouldn't have complained that they weren't getting the hours of work that they expected? Again, simply as a bit of gossip, this idea makes no sense at all.
whoosh
Member
Furthermore, the construction workers I know don't take shortcuts or intentionally do shoddy work, or try to cut back on their hours. Cost saving measures are only taken by management types dumb enough to think that they're not dealing with a bunch of unionized whistle blowers who know their trade and take pride in their work.
sushi
Member
Fifth, each one of those workers will likely have family, friends, co-workers, and future work locations, downstream in the flood zone. I have worked in these type of environments and these are typically tight knit crews that look out for one another and have a strong sense of moral integrity . If they don't, their own co-workers will drive them to quit.
The writer is presenting a stereotype.
My experience in management consulting in the O&G industry is that the folks at the bottom of the food chain live by the rules. They have family to feed, mortgages to pay, parents and relatives to assist. They are not going to put their world at risk. If a supervisor ordered them to take an action they know to be inappropriate, they would find a way to get the message up the chain of command. In my experience, the real problem cases are at the top of the food chain. They have access to the goodies, they believe themselves to be above suspicion, and they think they can get away with it. They are always surprised when reality intrudes.
Nada Truther
Senior Member
Accountability catches up with you. If something goes wrong, which it did, and then someone finds out that you might be responsible due to gross negligence.... I would imagine that you would either need to be dead or living in a cabin in the woods for the authorities to not come knocking on your door. I think most reputable contractors worry about this. I would think that the contractors that built the dam and spillway would not have been just picked out of the phonebook. I would speculate that the architects and engineers and project financers would have done their homework to get people who were going to do things by the book. Especially in the case where screw=ups could result in major catastrophic damage and possible loo of life, if their work is shoddy. If anything, I would think these things might happen due to mistakes or just plain operator error. "The new guy didn't read the plans right and forgot to lay rebar", rather than "just leave out that rebar, no one will ever find out!"
Joe Hennessey
New Member
The dam and spillway date from 1968. They worked. I'd first look at maintenance and whether or not the staff is competent to maintain what their grandfathers could build.
DirtyLaundry
New Member
Curiously, in 50 years the spillway has seen very little use, especially at flows of 50kcfs (the failure flow) or more. Consider the the top 15 crests on the Feather river, measured at the Gridley gage (below Oroville). Table here: http://www.water.weather.gov/ahps2/crests.php?wfo=sto&gage=gric1&crest_type=historic
The 15th highest crest (April 1974) clocked a flow a bit over 50 kcfs. Graph here:
https://waterdata.usgs.gov/ca/nwis/...od=&begin_date=1974-03-25&end_date=1974-04-16
6 of these crests occurred before the spillway was finished. Adding this most recent event, we have 10 50kcfs spillway uses in 50 years, at most (the flow at Gridley includes more than just the spillway). Looking at a few of these uses, the spillway runs at this level for a few days or a week. I'm not sure that's enough usage to claim it works, versus a milder claim that the damage sustained during each use did not cause an obviously critical failure until the tenth use.
By analogy, perhaps we've been driving a topfuel dragster - highly engineered and well maintained, but sometimes blows the engine on its way down the track. Joe's point is well taken though - we should study the maintenance and engineering to learn any lessons. Maybe we want a steady, reliable, boring Corolla.
Eddie Weeks
New Member
The rated capacity is 150,000 cfs... failed at 50,000 and it was not used very often.
Stack Dump
New Member
Minor nit-pick: the rated capacity of the main spillway (Maximum Release) is 296,000 cfs (albeit at an absurd water level of 917 feet).
See: https://www.metabunk.org/oroville-dam-spillway-failure.t8381/page-9#post-200148
According to the Emergency Spillway Release Diagram, the maximum capacity of the main spillway before the emergency spillway kicks in, is 250,000 cfs. The 150,000 cfs value is an operational limit determined by what happens downstream at Oroville.
See: https://www.metabunk.org/oroville-dam-spillway-failure.t8381/page-9#post-200142
But that probably just emphasizes your point.
deirdre
Senior Member.
Because this Current Event is over i am locking this thread for now. If you have anything relevant that doesnt fit into any of the other Oroville threads, please write to Mick and he can decide if he wants to open it again.
You can find started threads on Oroville (click Forums top of page) in General Discussion: subforum Current Events
There is also a thread topic or two in the Open Discussion or Rambles forums.
Any future posts that make statements as fact, which are really only opinion WILL BE deleted unless accompanied with modifiers such as "i think", "it seems to me", "it looks like" "i wonder" etc.
Please do not start new threads without reading MB's Posting Guidelines. Metabunk is a debunking site, not a general chat forum. Many exceptions have been made for the Oroville spillway damage event, but other than "erosion watch" and adding to the database of historical photos found, the event is over.
If you'd like to engage in speculation about what caused the spillway failures, please find another forum on the internet.
Thank you everyone for your many informative contributions. As i'm sure you've read from members, having a source of trusted information/facts is invaluable to readers.
You can find started threads on Oroville (click Forums top of page) in General Discussion: subforum Current Events
There is also a thread topic or two in the Open Discussion or Rambles forums.
Any future posts that make statements as fact, which are really only opinion WILL BE deleted unless accompanied with modifiers such as "i think", "it seems to me", "it looks like" "i wonder" etc.
Please do not start new threads without reading MB's Posting Guidelines. Metabunk is a debunking site, not a general chat forum. Many exceptions have been made for the Oroville spillway damage event, but other than "erosion watch" and adding to the database of historical photos found, the event is over.
If you'd like to engage in speculation about what caused the spillway failures, please find another forum on the internet.
Thank you everyone for your many informative contributions. As i'm sure you've read from members, having a source of trusted information/facts is invaluable to readers.
Anna Reynolds
Member
The KCRA livecopter filmed the spillway and pool area today. https://m.facebook.com/story.php?story_fbid=10155081453926514&id=115763581513
I noticed there is still quite a bit of water flowing down the spillway on the south side and some coming from the drains on the north wall. I haven't been able to find photos of other times when the gates were closed but the lake level was still behind them. It would be interesting to compare if this is normal flow around the "closed" gates gates or something more. In the video there are surveyors on the spillway chute and in the damage hole, so it does appear to be considered relatively safe despite the flow.
Screenshot at about the 27 min mark showing the flow:
And about 36:36 showing the whole spillway:
I noticed there is still quite a bit of water flowing down the spillway on the south side and some coming from the drains on the north wall. I haven't been able to find photos of other times when the gates were closed but the lake level was still behind them. It would be interesting to compare if this is normal flow around the "closed" gates gates or something more. In the video there are surveyors on the spillway chute and in the damage hole, so it does appear to be considered relatively safe despite the flow.
Screenshot at about the 27 min mark showing the flow:
And about 36:36 showing the whole spillway:
deirdre
Senior Member.
Water observed flowing down the spillway is less than 10 cfs, Murray said. [a liaison officer with the Department of Water Resources in Oroville.]
“It’s leakage from around the gate structures,” he said.
Workers have used sandbags to control that leakage, which increases as the elevation of Lake Oroville lowers because the gates are pressurized and the lower water makes for lower pressure.
Divers on the lake side of the spillway structure have also been working to control water in the area, Murray said.
http://www.orovillemr.com/general-n...lway-debris-hyatt-powerplant-starting-up-soon
it's a big hole.. workers in my red circles
Stack Dump
New Member
Here's a photo showing leakage around the spillway gates, taken on 2011-07-20. Notice water is coming over the top of the gates, not underneath. At that time, the water level was near maximum, at slightly over 899 feet. They might have repaired or adjusted the spillway gates since then, but this illustrates the problem:
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Stack Dump
New Member
That sentence would make sense if the word "increases" were replaced with "decreases".
I think you are misreading it. Lower pressure gives a weaker seal, so allows for more leakage.
The question I would have is whether that is considered acceptable or not. Given that the reservoir was at 899 feet, it might have been acceptable to have water passing. They might even have wanted to keep a small amount of water flowing down the spillway for some other reason - maybe to keep it cooler, I don't know (speculating here).Here's a photo showing leakage around the spillway gates, taken on 2011-07-20. Notice water is coming over the top of the gates, not underneath. At that time, the water level was near maximum, at slightly over 899 feet. They might have repaired or adjusted the spillway gates since then, but this illustrates the problem:
I did look at outflow data for a 3 day period including 7/21/2011 - it ranged from near 5600 cfs to 5235 cfs, all of which could easily have come through the power plant.
FYI, an update. The power plant is in operation. 1 unit on line for sure this afternoon, [unsourced information removed] When 5 units of the 6 are on and loaded up, they expect around 14,500 cfs of flow through the dam. [text not found in article removed]
http://www.sacbee.com/news/state/california/water-and-drought/article136267538.htmlOne of six turbines at the Hyatt Power Plant was operational as of 10 a.m. Friday. The turbine’s outlet allows for 1,750 cubic feet of water per second to exit Lake Oroville, California’s second-largest reservoir.
Read more here: http://www.sacbee.com/news/state/california/water-and-drought/article136267538.html#storylink=cpy
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Anna Reynolds
Member
It looks like flows from Hyatt were stopped sometime between 9 and 10am this morning?
https://cdec.water.ca.gov/cgi-progs/queryF?s=ORO&d=04-Mar-2017+10:26&span=12hours
https://cdec.water.ca.gov/cgi-progs/queryF?s=ORO&d=04-Mar-2017+10:26&span=12hours
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SeanT
Member
Yep.
Source: https://twitter.com/CA_DWR/status/838157539803971584
Took them a while to say anything about it...
Started raining about an hour ago as well.
Boilermaker
Member
It's true that DWR only reported this on their social media accounts late today but the local press had the information within a couple of hours: http://www.krcrtv.com/news/local/bu...85?utm_medium=social&utm_source=twitter_KRCR7
In the press briefing yesterday there was no mention of the turbine restart being a "test" or only lasting 24 hours but it's hardly surprising that they've decided to enlarge the channel further.
One interesting point to come out of the press briefing, although only as an aside, is that the debris field includes a quantity of what was described as (paraphrasing what Mr Croyle said) fill put up there in the 60s. I took him to mean backfill under the spillway where the bedrock is uneven. There was no indication whether or to what extent there was such fill under the point where the spillway failed. It was also said that DWR has not moved on to the "forensic" analysis of what caused the failure.
SeanT
Member
I think the pictures posted on this site clearly show they had to fill the area near the failure (https://www.metabunk.org/pre-failur...ay-historical-images.t8410/page-2#post-202401) and your own post https://www.metabunk.org/pre-failur...ay-historical-images.t8410/page-2#post-202430 I'm really curious where they are moving all this material pulled from the river, I'm up on Kelly Ridge just to the east of the spillway/dam and I haven't noticed any trucks hauling material in or out of town recently. Perhaps they plan on reusing the same material for road fixes and spillway fixes?
SeanT
Member
They have not moved it far.
(Source: KCRA video, Screengrab someone posted on Twitter)
Are they building something there with it? Looks pretty leveled out, but for what?
Boilermaker
Member
Again drawing on what was said in the press briefing, there are now five spoil sites. (7:10 in video)I haven't seen a map of where they are but there's no indication they are anywhere off site. The one(s) you can see in photos/videos are on the hillside below the emergency spillway, as shown in Mick's photos.
https://www.facebook.com/CADWR/videos/10154484302022449/
No indication the material being dumped there is intended to be recycled in some way. Apparently people are interested in whether the spoil contains any gold. Sheesh.
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SeanT
Member
I wouldn't be surprised if there wasn't a good amount of gold dumped in the river below. Hell, I have shit washed up in my yard from a seasonal creek that flooded, I probably have small amounts of gold stuck in the runoff debris. Having never done any 'prospecting' I'm debating about panning some of it.
deirdre
Senior Member.
Hyatt Powerplant was successfully re-operated with one turbine generator unit running at full capacity since 2pm, March 3, 2017. This test provided vital feedback for construction crews working on the channel excavation and the planning efforts for short and long term reservoir management.
Work continues on the area below the emergency spillway, access roads, and various eroded areas created by emergency spillway runoff. Rock benches and check dams are being constructed to slow water and reduce erosion should the emergency spillway be required for use again. http://www.water.ca.gov/news/newsreleases/2017/030417_am_factsheet.pdf
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Boilermaker
Member
Three new photos taken and posted today on the DWR Spillway Incident page:
https://pixel-ca-dwr.photoshelter.c...g/G00003YCcmDTx48Y/Oroville-Spillway-Incident
The first shows the channel being dug at the diversion pool. Slightly difficult to tell exactly from what vantage point this was taken but it it appears to me that it is from the base of the spillway. The area in the middle of the scene may be partly flooded by water (note the channel next to the excavator furthest from the camera):
For contrast with the position yesterday there is this photo from the San Francisco Chronicle:
http://www.sfchronicle.com/bayarea/...apse-after-Oroville-Dam-spillway-10976144.php
The other two DWR photos are of the spillway itself and indicate the extent of the damage to the concrete:
Today's incident update from DWR notes in part that:
"Contractors continue to remove sediment and debris below the spillway. This operation will continue 24 hours per day. Approximately 329,000 cubic yards of material have been removed from the debris pile to date."
http://www.water.ca.gov/news/newsreleases/2017/030517_am_factsheet.pdf
https://pixel-ca-dwr.photoshelter.c...g/G00003YCcmDTx48Y/Oroville-Spillway-Incident
The first shows the channel being dug at the diversion pool. Slightly difficult to tell exactly from what vantage point this was taken but it it appears to me that it is from the base of the spillway. The area in the middle of the scene may be partly flooded by water (note the channel next to the excavator furthest from the camera):
For contrast with the position yesterday there is this photo from the San Francisco Chronicle:
http://www.sfchronicle.com/bayarea/...apse-after-Oroville-Dam-spillway-10976144.php
The other two DWR photos are of the spillway itself and indicate the extent of the damage to the concrete:
Today's incident update from DWR notes in part that:
"Contractors continue to remove sediment and debris below the spillway. This operation will continue 24 hours per day. Approximately 329,000 cubic yards of material have been removed from the debris pile to date."
http://www.water.ca.gov/news/newsreleases/2017/030517_am_factsheet.pdf
Boilermaker
Member
Update because as of now (6:00 P.M. PST) there is a total of 14 new photos added to the DWR Spillway Incident gallery.
https://pixel-ca-dwr.photoshelter.c...g/G00003YCcmDTx48Y/Oroville-Spillway-Incident
Several of these relate to the condition of the area where the "waterfall" was located when the spillway was in use. Two of them are inserted below. They show the scale of the void underneath the concrete at that point especially on the right side (kayaker's left). At that point the remaining spillway wall is still cantilevered over the rock that remains beneath it.
In this connection it's worth noting that at the 3rd March press briefing Mr Croyle of DWR, in response to a question about what inspections of the spillway had revealed and whether any remedial action had been decided upon, answered that it was proposed to "shotcrete" areas within the splash pool to strengthen them against further erosion in case the spillway has to be used again. These comments begin at 26:00 mins. into the video posted on DWR's Facebook page:
https://www.facebook.com/CADWR/videos/10154484302022449/
"Shotcrete" is wet mix concrete sprayed at high pressure on to a surface and may be reinforced by mesh or metal (or other) fibers: https://en.wikipedia.org/wiki/Shotcrete. Mr Croyle referred to applying it to "mats" laid over the rock.
https://pixel-ca-dwr.photoshelter.c...g/G00003YCcmDTx48Y/Oroville-Spillway-Incident
Several of these relate to the condition of the area where the "waterfall" was located when the spillway was in use. Two of them are inserted below. They show the scale of the void underneath the concrete at that point especially on the right side (kayaker's left). At that point the remaining spillway wall is still cantilevered over the rock that remains beneath it.
In this connection it's worth noting that at the 3rd March press briefing Mr Croyle of DWR, in response to a question about what inspections of the spillway had revealed and whether any remedial action had been decided upon, answered that it was proposed to "shotcrete" areas within the splash pool to strengthen them against further erosion in case the spillway has to be used again. These comments begin at 26:00 mins. into the video posted on DWR's Facebook page:
https://www.facebook.com/CADWR/videos/10154484302022449/
"Shotcrete" is wet mix concrete sprayed at high pressure on to a surface and may be reinforced by mesh or metal (or other) fibers: https://en.wikipedia.org/wiki/Shotcrete. Mr Croyle referred to applying it to "mats" laid over the rock.
So basically they are looking to see if this rock is good enough to hold up the remaining spillway if they help out by reinforcing it. A temporary fix. But obviously something they have to look into in case a warm storm comes in and melts all the snowpack (or even just if a couple of large storms roll in).
So basically they are looking to see if this rock is good enough to hold up the remaining spillway if they help out by reinforcing it. A temporary fix. But obviously something they have to look into in case a warm storm comes in and melts all the snowpack (or even just if a couple of large storms roll in).
I would reinforce it without hesitation. There was evidence when they were tapering down the flow that around 35,000 gps or so, the water started eroding right under the end of the spillway, which would be detrimental to being able to use it at a lower flow rate. My opinion - reinforce it, use rock and concrete to give it a downward slope so that it can be used to flow lower amounts of water during the spring melt. Being able to pass 5000-25000 gps with the generation plant also in service would be very helpful.
Boilermaker
Member
To be clear, what Mr Croyle was talking about in the briefing referenced in my earlier post was simply reinforcing the surface of the splash pool which is below the remaining edge of the spillway because of the issue you identify. He did not go on to say that the rock under the spillway would be reinforced although from the photos it's obvious that they are investigating its condition. He did not address whether the course of the flow might be diverted from the "canyons" or gullies that have formed on the right and left although that must be a concern because of the potential for washing a quantity of further debris down into the area being cleared. Watch this space.
Boilermaker
Member
Another 11 photos now posted by DWR:
https://pixel-ca-dwr.photoshelter.c...g/G00003YCcmDTx48Y/Oroville-Spillway-Incident
As these show they are in fact applying "shotcrete" to the rock face beneath the edge of the spillway; it remains to be seen whether they do so elsewhere in that area including below in the splash pool:
https://pixel-ca-dwr.photoshelter.c...g/G00003YCcmDTx48Y/Oroville-Spillway-Incident
As these show they are in fact applying "shotcrete" to the rock face beneath the edge of the spillway; it remains to be seen whether they do so elsewhere in that area including below in the splash pool:
On the spillway above they are doing a variety of repairs, including filling the gaps between slabs with what looks like epoxy crack weld.
Probably something like this:
Obviously there's a very good chance the main spillway will be used again at some point.
Probably something like this:
Obviously there's a very good chance the main spillway will be used again at some point.
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