Skip to comments.Emergency: California’s Oroville Dam Spillway Near Failure, Evacuations Ordered
Posted on 02/12/2017 4:26:47 PM PST by janetjanet998Edited on 02/12/2017 9:33:58 PM PST by Admin Moderator. [history]
The Oroville Dam is the highest in the nation.
“Oro” is Spanish word for “gold”
Those barges could strike at rich but what a waste if it went to government. Anyway this gold angle could get interesting
New images added at the beginning of the series. They’re really attacking that pile of debris/rubble at the bottom of the spillway.
Related to those picture, the two issues I see and posted earlier are...
1) The Main Spillway damage is so gargantuan that until the rainy season is over, if the Main Spillway is needed, it will continue to move earth and rock into the middle of the river below and back it up into the power plant. I mean even remedial repair looks like it would take weeks or months to fix that problem. I dont know exactly what they plan to do in the next seven days. I dont know how long a permanent fix would take.
2) The Emergency Spillway looks more threatening to cause a catastrophic emptying of the reservoir and flooding from its failure. Maybe the whole Emergency Spillway design needs an overhaul including the un-anchored upside-down half shell at the top. Have no idea how long that could take.
Is it possible that the time to do the job right on these spillways could take more that one summer season? If so, couldnt that change the priorities of what the do first to reasonably hold off a problem next winter and finish the job the following summer?
Have to wonder about the condition of that lake side floor to the main spillway gates. Had to be some serious hydraulics there, too...
All that activity in that small of space is impressive. Hope they have a good safety culture that is an accident waiting to happen.
Wonder how they got that many little people on one crew. ;-)
I think that they have the trucks working basically a loop where they get loaded, then move on and out to the dump area. Wherever that is.
They come in a little box with the ant hill already assembled.
CAT’s PR department will have field day...
this is far from over....pattern turns more active/wet again soon
and huge snowpack about to start melting
there is still some water flowing out.....and it may be slowly eroding under the ledge of the main spillway similar to the hillside of the ES spillway? When the water was on the flow of the water was pushing it out but now it falling straight down
Where's the water? Apparently there were years of pre-warning signs  of an anomaly at the area where the main spillway failed. It is missing water. The main spillway has drain pipes under the concrete slabs that collect any penetrating sub-slab water and route it up into drain outlets in the concrete sidewalls.
btw- Scott Cahill, a dam expert, notes that a well designed/sealed/maintained spillway would have very little drain water during spillway operation  (should not be "jets of water" - these "jets" reveal how much volume and pressure the water may "scour" underneath the spillway slabs and substructure rock).
You can see water from these drains from 2013 and in 2017 (just prior to the "blowout failure"). Critically, the "blowout area" has missing water from the drain outlets. This is a critical indicator as a non-presence of waterflow indicates that water is not being collected (possible drain pipe failure) OR the water is not entering the drain either by an improper gravel layer emplacement OR the water has found a deeper flow path (or combinations of all three). Water has been observed to well up from under the main spillway slabs at the area of the blowout failure. The 2013 image reveals this. The 2017 image also shows a "defect" chip in a seam in the main spillway slab (at/near the blowout failure area). This 2017 picture was taken in the last week of Jan 2017, just before the Feb flooding & main spillway failure. Having this defect present would have likely initiated very damaging cavitation erosion from spillway flow (jackhammer effect on the concrete). Likely a precursor to the "missing water" substructure penetration = (i.e. potential sub-structure erosion deep under the slabs or undermining the "backfill concrete" chunks ).
= = reference notes:
1. Stagnation Pressure' as described by the Bureau of Reclamation: "Stagnation pressure refers to two conditions that can result in damage and/or failure of the spillway: (1) High velocity, high pressure flows enter cracks or open joints in the spillway flow surface (such as a chute), which results in uplift pressure that lifts (displaces) portions of the spillway conveyance feature; and (2) High velocity, high pressure flows enter the foundation through cracks or open joints in the spillway flow surface, which results in internal erosion of the foundation and loss of support of portions of the spillway conveyance feature ."
2. Alarms Raised Years Ago About Risks of Oroville Dam's Spillways:
..excerpt: "The cratering of the main spillway which spiraled into the current crisis in Butte County occurred in a spot where cracks and other defects had been found repeatedly since 2009, said Robert Bea, a professor emeritus and engineering expert at UC Berkeley." My God, we had evidence that there was trouble going back to 2008, 2009, said Bea, who at The Chronicles request reviewed 14 dam inspections from 2008 to 2016 conducted by the Division of Safety of Dams, which is part of the Department of Water Resources.
Yes, they had detected the defects (in the main spillway) and yes, they had put into gear remedial measures, Bea said. Were those repairs sufficient? No. The result was a breach.
.. end excerpt
3. One highly respect dam design expert, Scott Cahill, had some very enlightening information regarding Oroville's main spillway & issues linked to his extensive knowledge on dam failures. Three of the key issues he noted in detail was (1) thorough & expert level maintenance (2) the Oroville main spillway had too high of an underflow of water beneath the concrete [as he noted by the amount, volume, and velocity of the "jetting" underdrains - this is a significant issue to address to prevent erosion scouring and sub-spillway pressurized leakage] - [i.e. this was an "early warning" that should have been taken action upon] (3) the original construction MUST be thorough on its bedrock/concrete and anchoring stability.
Workers in 2013 at pre-failure blowout area - notice the missing drain flow (red circle) and the notable upwelling of water in the main spillway.
Same missing waterflow in drain near pre-failure blowout area. notice the defect in the concrete slab seam at/near the pre-failure blowout area.
.......and don’t forget those high priority sex change operations for prisoners!
Appreciate it, abb and EarthResearcher333.
Metabunk’s been a good resource for studying this situation and learning.
You load sixteen tons, what do you get
Another day older and deeper in debt
Saint Peter don’t you call me ‘cause I can’t go
I owe my soul to the company store
I remember that song!
A local news article from Oroville...
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