The Lake Oroville saga continues, yesterday we wondered if the collapse of the spillway might have been due to missing or substandard REBAR, and many experts weighed it on that topic. It now appears that there was REBAR there, and the failure was likely of a nature of lack of maintenance and age combined. It appears the earth underneath the spillway was compromised, and that led to the collapse of the structure without anything to support it.
Today, it is a race against time and water, as DWR has ramped up outflow to 65,000 cubic feet per second, and in doing so, is sacrificing the damaged spillway in hopes that there will not be an uncontrolled release from the emergency spillway, something that has never happened in the history of the dam. During the super El Niño of 1997-1998, it came within 1 foot of the emergence spillway. Now, given the fact that inflow is still exceeding outflow, and emergency release looks very likely.
Here’s video from yesterday showing the damage and concrete blowing out:
Unfortunately, the last update of data at 11:00AM PST today shows a water surface elevation value of 895.84 feet, or 4.16 feet to the top at the 900 foot mark where the emergency spillway starts to kick in.
The rate of rise has slowed from yesterday, and no new additional rain is expected today, but with afternoon temperatures expected to be above freezing well above 4000 feet, we are going to see snow-meltwater continue to flow in. As of 11 AM, they were letting out 65,029 CFS, but have a staggering inflow of 132,107 CFS, more than double the release rate:
Source: https://cdec.water.ca.gov/cgi-progs/queryF?ORO
What’s more worrying is this graph comparing the 1997/98 super El Niño year to this year:
They’ve got a hockey-stick of storage going on, and much earlier in the water year than 1997/98…and they have a busted spillway.
We’ll update this story as more is known.
Here is a historical video for perspective:
https://www.youtube.com/watch?v=CF4ToIhKEeI
UPDATE1: about an hour ago, officals say they “think” they can avoid the emergency spillway:
OROVILLE
With a break in the weather and increased outflow from Oroville Dam’s heavily damaged spillway, state officials said Friday morning they no longer believe the swollen reservoir will breach the dam’s emergency spillway.
After a grim assessment late Thursday, officials announced Friday morning they think they can avoid using the dam’s emergency spillway, which they’ve been working feverishly to avoid. The emergency structure feeds into an unlined ravine, and the water would propel soil, trees and other debris into the Feather River.
The announcement came after William Croyle, director of the state Department of Water Resources, told reporters Thursday evening that water levels in Lake Oroville could reach the brim sometime Saturday, forcing activation of the emergency spillway. The emergency system, which has never been used, would dump water onto an exposed hillside, dislodging trees and earthen debris into the Feather River and potentially affect communities downstream.
Read more here: http://www.sacbee.com/news/state/california/water-and-drought/article131743014.html#storylink=cpy
UPDATE2:
As of 11PM on 2/10/17, Lake Oroville is now less than a foot from the top and overflow on to the emergency spillway.
Update 3: Oroville water level tops 900 feet, water will start flowing down spillway
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Maybe they can print out a few million pages of “permanent drought” articles and use that to block the water.
Maybe Peter Gleick will come and stick his finger in the hole in the spillway.
I didn’t want to be accused of VER (Violent Eliminationist Rhetoric – mostly coming from the left these days anyway), but yes, having a few dozen CAGW folks linking arm to arm across the hole did come to mind as well.
So we electric customers can expect a check instead of a bill this month right? So we water customers can expect a check instead of a bill this month right? The carbon taxes will be suspended?
What was the cause of the earth underneath the spillway being compromised? Hopefully not seepage from the dam.
Earth is already compromised by definition. If it wasn’t earth it could have been granite. That’s nearly as good as bed rock.
g
I have a book which contains a photograph that is captioned “Fixing the reinforcing steel on the spillway of Dibbis Dam, Iraq.” The steeply sloping slab in the picture is 7 to 8 feet thick between the top and bottom rebar mats. This is in contrast with the concrete slabway slab at Oroville which seems to be hardly more than 1 foot thick.
So I’m wondering if the problem is more basic than ‘not enough rebar’. I suspect it may be more like a case of ‘not enough concrete’.
For as long as a spillway slab can act like a ‘freeway for water’ (i.e. with water flowing on top and the underside kept dry) it only needs to be as thick as a freeway slab. But any water which manages to permeate *under* the slab high up the spillway could become highly pressurised lower down and ‘blow’ the slab off its substrate. Prevention of this from happening would require either a) some very clever and expensive pressure relief drains or b) a very heavy slab.
I find it a little worrying when I hear all those officials talking as though they have any say about the control/use of the emergency spillway.
When one designs a dam wall -, say for a water level of 904 feet – you leave a section of the wall at 904′ and raise the remainder of the wall a metre or so higher. This means that you have a some say as to where the dam will overflow and that is all.
When the water level reaches 904′ the water spills over and away. No official has any control in the matter.
The water will continue to discharge down the emergency spillway until the water level drops to 904′ and then miraculously stop.
I guess the public mustn’t be alarmed.
“No official has any control in the matter.”
Never say an official has “no control” or they may decide to start sandbagging the emergency spillway.
If anything exhibits a fat tails distribution it’s weather .
oo bad that california has not had any droughts lately so they could do preventive maintence — oh right — they need the money to support their illegals population
and trains to nowhere
The California Department of Water Resources has a Twitter Page where you can get updates, photos, press releases etc. about the Oroville Dam situation.
https://twitter.com/CA_DWR
They have renamed it, it is now the Auxilliary Spillway no longer an Emergency
Here is something that undoubtedly added to this problem, “…The most recent inspection of the Oroville Dam spillway did not include a close examination of the discharge channel, according to a state dam safety report…” That is an excerpt from here, …http://www.redding.com/story/news/2017/02/09/dam-spillway-checked-distance-last-inspection/97723936/
Nice catch and thank you for posting. Using your info I went digging a little deeper and found this page:
Oroville Facilities – Project No. 2100
http://www.water.ca.gov/hlpco/p2100.cfm
Notable: “DWR anticipates that FERC will issue a new license order in 2017 pending issuance of the aquatic biological opinion from the National Marine Fisheries Service.”
Brief summary of facilities:
Oroville Dam is the tallest earth-fill dam, at 770-feet, in the United States and forms Oroville Lake with a capacity of 3.5 million acre-feet (California’s second largest reservoir). The facilities generate 762 megawatts (MW) of hydropower and provide storage to deliver water to areas of need. The spillway, located on the right abutment of the dam, has two separate elements: a controlled gated outlet and an emergency uncontrolled spillway designed to convey excess water over the spillway weir and down the undeveloped canyon slope to the river.
Edward Hyatt Powerplant has six generators (three for reversible pumpback operation), and a capacity of approximately 645 MW. In the bedrock beneath Oroville Dam, a cavern -large enough to hold almost two football fields- was blasted out to house Edward Hyatt Powerplant.
This is a perilous way to go about it, but all river systems need a good flushing every now and then.
With regard to the damaged Oroville Dam spillway: the initial fissure that opened in the spillway surface was initiated by hydraulic pressure being built up/exerted within a void in the soil substructure under the spillway floor. Any expanding pocket (void) was excavated by venturi effect from the water flowing over the joint(s) of the concrete slabs (similar to the principle of how a suction dredge functions in gold mining). At a certain critical point the this void pressurized sufficiently to “lift” an edge of the slab by some increment. As this lifting occurs, the water flowing over the slab structure from continuing releases, increases the pressure within the joint of the incrementally “lifted” slab, and the pressure within the void in the sub soils below spillway. This process continues to incrementally force the section(s) of concrete apart/up to a point that the actual velocity and mass of the surface water flowing down the spillway can exert force on the now lifted edge of the concrete. It is at this point that the failure viewed in the videos becomes obvious as “chunks” of concrete etc. in the spillway.
I was guessing slow positive pressure subsurface loses rather than negative pressure surface migration, with water getting in from somewhere uphill/cross slope. Hard to tell, but it appears in the photos that there was a good gunite type seal/base under the concrete….
+1000
I remember in 1992 when Belton Lake (Belton, TX) crested its spillway. It was very impressive to see what water can do when it isn’t controlled.
Going to be dangerous for any activity in the water downstream of Lake Oroville. Slabs of concrete and a rats nest of rebar.
Using Google maps there is a second dam or a set of gates just downstream. All that concrete and rebar will be fun to clean up when it bunches up there.
Downstream are the forebay and afterbay used to solar warm the water for rice farming. When the dam was built, rice farmers pointed out the cold snowmelt from the lake bottom layers, would kill the rice, so that feature was added. There is a slow section of river from below the dam to the forebay. Any junk will settle out there.
How do I know? About 1969 or 70 a couple of us kids built a raft and put it in at Oroville, then took a couple of days to go 12 land miles downstream. There are gates to control water in and out of the bays while the main channel still has a bypass if desired
FWIW, I watched the dam be built and attended the dedication.
The dam is fine. The spillway is well removed from it. It has served well for over 45 years so not a design fault. Just regular aging with insufficient maintenance and inspections. It would not have been hard at all to have even done a full remove and repour had inspection shown it needed. They just didn’t look hard enough to find the issues building up. Heck, they could even have concrete lined the Emergency Spillway over that 45 years had anyone cared.
Would I rebuild it stonger? Sure, but I’m prone to overdesign. Heck, I’d even use basalt rebar to eliminate corrosion concerns:
https://chiefio.wordpress.com/2014/12/21/unlimiting-resources-basalt-for-a-high-tech-stone-age/
Yes, it exists…
The dam itself has a giant concrete footer to anchor it to the bedrock, then a topper of clay in the middle (to block water flow) and gravel / dirt mix for the bulk of the mass (all heavily compacted by big roller trucks) then boulders and rock riprap facing. At least, that’s what I remember from watching it be built over several years. They used a giant bucket wheel digger to dig up dredger tailings for much of it. We used to go shooting and fishing in the resultant flat depression about 8? Miles downstream. Last time I visited, the State had posted that area off limits. Too many folks enjoying themselves…
I watched the first test of the spillway a few years later. Spectacular show as the water hit the teeth at the bottom (to prevent erosion of the opposite bank). At that time the highway on the other side was important… don’t know about now (I think they added a back road in). I’d be worried that uncontrolled flow will wash out the other bank and road… or that loss of the tooth section will cause the same.
Hello Mr. Smith.
You seem to know more than a lot of posters here. I posted this as another reply so it is probably lost in action. I’m not an engineer, so a question. Why does a spillway need such a long run over a “ramp” that is built over fill? I assume the top of the spillway and associated gates are built into the bedrock. Couldn’t the spillway be a shorter concrete “cap”, with no long concrete run at all? Downstream flow would just run over bedrock.
Thanks in advance for any response.
You must get water from near the top, to the bottom. The geography sets the available slope choices and then that determines the design. The ground is typically not smooth rock of the right slope, so you put a slab over it (to avoid manual excavation or uncontrolled scour as is happening now…)
While the base is rock, under the dirt, it is jagged and irregular. As all engineering is compromise and money not unlimited, it is far cheaper and generally just as good to lay a well footed and reinforced slab over compacted base (with drains as needed). The alternative, excavation to jagged rock, then deep pouring brings in heat of cure removal and reinforcing design issues (how to form rebar over irregular rocks?) Or blasting to resurface (and crack base?…) issues.
The problem here was unlikely to be design. It has worked well for almost 1/2 century. I watched the first test of it with big flows and it was fine. What failed was inspection and repair to spec. That would not be fixed by more concrete.
To the extent any design improvement could be done, I’d speculate added sub-panel drains with sensors (that they didn’t have in the vacuum tube era when this was first designed…) would have assisted in inspection and detection along with removal of sub-panel pressurized water (if any). Then again, ground penetrating radar and sonar would likely have found issues too, if deployed IMHO.
FWIW one could install penstocks and gates like for the generator room, and avoid slope, but the cost is horrific (especially in the pre tunnel-boring machine era when this was built.). Also, failure modes are more spectacular and repair is done by draining the lake… some of the smaller dams here work that way.
@Joe Kirklin:
The short answer is “yes you can” and that is how the “Emergency spillway” is built. The problem is the debris accumulating at the bottom from the scour of the rock. That has caused water backup to the powerhouse, so it is now shut down to protect it… Eventually you would get all the debris washed out, but it’s better to just put a slab in.
Why worry about aging and crumbling infrastructure today when you can worry about a degree or two of warming 100 years from now?
Just think, in another seven years or so we can all drive to the Central Valley and ride all 32 miles of the California Bullet Train. Who needs to fix the pot holes in our freeways or, God forbid, build more surface storage.
It would seem prudent to use the emergency spillway now at a moderate flow , which in combination with the damaged spillway will provide a larger margin of safety that they won’t have to discharge a large volume of water thru the emergency spillway .
Typically you do not have a choice about “using” the emergency spillway. In the absence of sandbagging, it will automatically start discharging water when it is overtopped. This is to prevent overtopping of the main structure which would undergo catastrophic erosion and a ‘pulse’ of flow an order of magnitude greater than the volume flowing into the reservoir, until the reservoir is essentially completely drained.
The emergency spillway has no flow control. Once the water level reaches that height it’s going over.
They probably used FUBAR instead of REBAR in the spillway construction.
This would be s good time to be thinking about “what’s the worst thing that can happen ” and act accordingly.
re: “the worst thing that can happen”
No “fish” available during Lent on Fridays? Sorry, had to do it.
Let them eat Tofu.
Design standards from USBR, for dam spillways. Includes photos and diagrams.
https://www.usbr.gov/tsc/techreferences/designstandards-datacollectionguides/finalds-pdfs/DS14-1.pdf
Good thing the GFS weather model forecast says only 12 inches of rain in the next two weeks.
http://www.tropicaltidbits.com/analysis/models/gfs/2017021018/gfs_apcpn_us_48.png
Mr Bill;
wow, that is a very interesting prognostic website.
I was able to recreate your pix with only minor flogging.
Those dam engineers had better get those lake levels down promptly, even if the precip will be less than another foot.
The peak discharge I saw was 275 kcf/second at the Yolo Bypass above Rio Vista.
Regarding spillway engineering, I wonder about the slope of the gated spillway.
From the pictures, I thought I saw a step-change in the slope, becoming steeper about 1/4 or 1/3 of the way down. I recall reading about other spillway failures that involve a ‘hydraulic skip’ ,where the water stream departs from the surface and then reimpinges.
That story about need to re-engineer the Glen Canyon overflow system struck a note for me. I suggest that operating for extended periods at a particular spill rate might tend to exacerbate issues at certain places along the spillway. Perhaps they need to slowly modulate the spill rate to avoid sitting on a particular ‘resonance’ , by ‘spreading’ the ‘sprectrum’ of the purported ‘rumble’ phenomena. The allocation of ‘spill rates’ looks rather linear and static, if recent release history is representative.
I propose a pool on just when a newly eroded ravine in the Oroville Dam emergency spillway starts uncontrollable massive draining of the reservoir. And I choose Sunday, February 25.
Jim Berryi,
The worst case is that downstream levies around the river side of floodplains north of Sacramento are breached. There are 100,000+ homes in the Natomas floodplain alone.
http://www.sacbee.com/opinion/op-ed/article2604482.html
Before that, it will breach about 12 miles downstream and flood into the central valley there. In about 1960? I went to the river with my Dad to see when we would flood. (North of Sacramento about 70 miles) At that tine, 1/2 of the bridge had washed out and we were about 2 feet from the levy tops. This was part of why they built the dam.
My home town has curbs about 2 to 2.5 feet high with a step in them. In the 1800s they raised the whole town two feet as that was the usual flood level. In winter, the streets become large drains… this is 4 miles from the levy… 32 foot elevation over about 210 miles to the SF Bay…
Sacramento tends to flood when the American River has excess water or the Sacramento River (Lake Shasta) has issues, while the Feather hits Marysville and north. Spread it out 2 feet deep over 30 miles wide and 200 to the bay, it holds a lot of water.
So that’s why we went to see how soon to plan on staying in the house if the river overtopped… Needless to say no flood improvements have been made since the dam was built.
IIRC, flow rate was about the present inflow rate to the lake now…and flood would happen at something like 150k? Hey, it was a long time ago…
Well here it is Fed 12 and the dams are full everywhere. Essentially, there is nothing left for flood control in the North State.Rain will start again in just 5 days. The 50′ lake level margin for flood control was lost in a few days during the rains as the spillway broke. Now the dam needs protection from overtopping. A big storm + perhaps some wave action can overtop the dam. Lake is now 1.55 feet HIGHER than the emergency overflow….I do not know how much freeboard is left on the dam itself. This is a very precarious situation. Rain can still wreck this dam. That emergency overflow can’t ship enough water. The prudent thing is to build TWO spillways. 330000 acrefeet is the historic max inflow. Spillway is good for 150000 AF. Is my math wrong or is this thing undersized?
Philip,
Each spillway is good for somewhere near 250,000 cfs. The Emergency spillway alone is sufficient to prevent overtopping as the lake buffers inflows so you never need the peak inflow. Besides, at about 150,000 cfs my old home town gets flooded out anyway…. the goal is to stay under that via consistent 55,000 cfs from the damaged spillway.
If I am calculating correctly, a net 50kcf/second will remove 100TAF (100,000 acre-feet) of water per day of that net outflow. (actual outflow – actual inflow)
As of midnight on Feb 11, Oroville shows 790TAF of ‘encroachment’ above the ‘Top Of Conservation pool’. I don’t see how they could get Oroville down to TOC conditions before the next set of storms. (Top Of Conservation is apparently a seasonally dynamic value, and perhaps weather-dependent?)
As far as I can tell, the DWR engineers have a difficult dilemma;
Door#1 Operate the gated spillway at high flows and destroy it, and possibly silt in the generators
Door#2 Continue with less than 50kcf/sec net outflow, and risk uncontrolled releases from the ’emergency spillway’, apparently recently renamed by the PR department.
Have I miscalculated the situation? That 10 day forecast of precipitation from GFS that Bill Illis shared, shows quite a lot of precip in the watershed, unless I misread the geography as well. Maybe it will all be the lovely solid version of global warming.
I still miss your graphs with hair.
Thurber was a veteran of this flavor of disaster, from the front.
http://downwithtyranny.blogspot.nl/2011/01/thurber-tonight-my-life-and-hard-times_09.html
Echoing DonM’s remarks. In the absence of the dam, the river downstream would already have been flowing at up to nearly 180,000 cfs per the reported measure at the top of the table in the article. Salmon had to survive (or not) that flow rate on occasion in the past. Should the emergency overflow level be overtopped, there could be unusual local erosion in the emergency spillway, with detrimental effects downstream, but these pale in significance compared to dam failure.
I skimmed the Division of Water Resources page. My immediate impression is that PR over substance seems to dominate. I think the term flood is appropriate. If the upper river wasn’t flooding the dam wouldn’t be close to over topping. Damage was revealed when the spillway HAD to be used because there is too much water behind the dam. And, as was said above, there is no choice to use or not use the emergency spill way. That will happen when the “flood” is great enough to do so. Any impression that they have control is a function of the remaining time before the water reaches the emergency spillway. Which is running out faster than the water.
You expand capacity and maintain dams and reservoirs during drought when work is inexpensive, easier and will be easier to compress or cure. But not in CA. Not an acre foot of capacity or upgrades done during 10 years of drought. Unbelievable. A reflection of liberal thinking. The religion of global warming made it easy to ignore these problems.
It’s the hillbilly mindset: “When it ain’t rainin’, don’t need ta fix it; when it’s rainin’, cain’t fix it nohow”.
Oh, we did do something. We passed a proposition that funded $7 billion for new dams and repairs. Oh, wait… if you actually read the proposition, it allocated money for dam removal, funds for disadvantaged communities, and ‘studies’ for future dams. After the Sierra Club obstructed the Melones Reservoir in the mid-70,s, there ain’t gonna be any new dams here until their teeth are pulled, and that ain’t happening in Kalifornia. We are too leftist to allow that.
Not an expert’s comment:
Who has looked at the “as built” blueprints? As, I’m sure others have said, the straight line breaks all appear to be along the seams of the expansion joints. Did water seep in from neglected expansion joints?
Under Governor Moon Beam, was the money to maintain what exist neglected in favor of windmills and sunbeams?
Just questions. I don’t know the answers.
But, if we don’t maintain what we have, “California Dreamin'” will only end in a nightmare.
Yep: Moonbeam was busy buying sun beams and the dam built by the world’s greatest engineers was simply allowed to rot away.
Here is a short video of the building of the dam. Reagan makes an appearance at the dedication, …https://www.youtube.com/watch?v=p_5udzKfLQM#t=340.776053
Yes … as posted in the previews thread; proper credit and title: “The Birth of Oroville Dam” – produced and directed by Mark S Lambert
I was there too! See that teenager in about the 10th row toward the center right? 🙂 ….
Good point
Similar design of earth dam over-topped in semi rural Yorkshire – Dale Dyke Dam 153 yrs ago.
https://blog.geolsoc.org.uk/2014/03/11/the-great-sheffield-flood-of-1864/
sod the fish, they need to spill