[onlooker]

Not to sound morbose and maybe a heads up to some but anybody like to weigh in as to what may the next big structure to fail?

[hvacman]

H-man - You seem to be very familiar withe subject so I have some questions. Might sound like criticism but not...just curiosity.

A) Given the arid nature of the rergion did they delay an earlier release in order to save resources?

B) Not that I've read more about the deterioration/lack of maintence wss the evacuation called much later then it should have been? Evacuations themselves can be deadly but was the late call PR driven?

C) Some comments seem to indicate it would have been a prudent safety policy to have been holding a much lower reservoir long before the rains hit.

The situation reminds on the huge mudslide a few years ago that took out a whole community. Afterwards a geologist showed maps of numerous massive mudslides that happened in the same valley for thousands of years. IOW even though it was inevitable the homes were still built.

RM - A) The the "rainy" season is from October to April. Except when it it November to February. Except when it is just two days in December. So figuring out how to both provide adequate flood control space through March and have a full reservoir in June is as much art and guesswork as science. With 5 years of drought, I'm thinking many reservoir managers have had some "upstairs" pressure to hang onto more water sooner than perhaps their own personal best judgment dictated.

In California, we have at least 4 types of people who have a say about how our reservoirs and dams are managed. The flood control people want a reservoir that is always half-empty. The recreation people want a full lake year-round. Irrigation people want a full lake in the spring and an empty lake in the fall. And the fish/wildlife people want the dam completely removed. Let's not even get into what the hydroelectric power people want.

Now you know why Mark Twain said in California, whiskey is for drinkin' and water is for fightin'

B) People in Oroville have ALWAYS been scared about the reservoir. Picture living in a town immediately downstream of the nation's highest dam, and it is an EARTH dam. There were quite a few, when the concrete spillway started to break apart and the DWR was talking about letting the reservoir rise to spill over the "emergency spillway" directly onto the dirt, who decided on their own to get outta Dodge. The local government was taking their cues for evacuation from the DWR (state Department of Water Resources). It wasn't until AFTER the emergency spillway started to also fall apart that the DWR alerted local agencies and the evacuation order was quickly placed. The evacuation wasn't just for the town of Oroville (about 40,000 people). The Feather River that would get flooded included several moderate cities further downstream, lots of town, a huge chunk of rice farms...hundreds of thousands in total. If that spillway actually did fail, we're talking Katrina-level rapid flooding. A 30'x1000' wall of water. The east coast/midwest, with regular flooding and hurricane experience, is perhaps more trained for evacuation orders like this.

C) This is the first that I've really been familiar with the technical aspects of Oroville's dam. I'm much more familiar with Shasta Dam, which is federally-managed by the Bureau of Reclamation. At Shasta, once the level gets to within 30', the BOR starts bleeding off water to hold that level as best they can without flooding downtown Redding, Anderson, and Red Bluff downstream. They did a bleed like that 4 weeks ago and again started to ramp up that bleeding last week as soon as the last of the bad storms past. Still, they came within 5 feet of being "full". They are blowing 70,000 cfs now to get the lake back down to 30' of freeboard. Looking at the available Oroville inflow and outflow data, it looks like Oroville did not blow off as much, nor as soon as Shasta from several weeks ago, nor blew off as much before this new set of storms set in.

There is a fundamental engineering difference between Shasta and Oroville and the tools they have for water level control. Oroville has two primary tools - their hydro plant (18,000 CFS capacity) and their primary spillway. But the primary spillway can only take off the top 30 feet or so. They do not have any intermediate vents through the dam.

Besides their own hydo plant, Shasta has about 15 different vents through the dam at different elevations. The water level doesn't have to get near the top to blow off water. They can blow off water much earlier, and with all those individually-controlled vent valves, they have redundancy if something fails. As their final level control function, they have several drum-gates at the very top of the spillway, which they can, if everything else doesn't work, fully lower and spill up to 250,000 CFS of water from the top of the lake down the dam spillway. The dam's face itself is the spillway, consisting of 50 feet (at the top) to 500 feet (at the bottom) of reinforced concrete. Solid rock and massive concrete energy dissipaters at the bottom. The dam is considered the safest place to be in case of nuclear attack.

This incident appears to have involved a collision of maintenance failures, a heavy winter (but not the worst ever), some questionable reservoir level management, and perhaps some under-appreciated design flaws. I'm just thankful no one had to die to discover this. It may cost the state a few hundred $million to fix and cost farmers a few million acre-feet of water and the local residents a whole lot of hassle.

We have several other tall earth dams around the north State. I'm betting they will all get a very deep inspection + some re-engineering of their level control systems, along with a fundamental re-evaluation on the operational logistics to balance storage and flood control priorities.

[Plantagenet]

[This is a Federal Problem.

Actually the Oroville dam is a state owned dam. It was designed, built, operated and maintained (or not maintained) by the State of California.

The federal dam up at Lake Shasta is doing fine. The problem is at this crappy state dam that was poorly designed to start with and then was not maintained adequately by the State of California.

[onlooker]

Here is another perspective on the situation
https://www.peakprosperity.com/blog/107 ... m=facebook

[Plantagenet]

The Oroville dam contains 60% of all the water in the California Water Project---thats the giant infrastructure system that supplies water to most of California's farmers and drinking water to 23 million people.

California_State_Water_Project#Dams_and_reservoirs

If they mess up at the Oroville Dam, California has pretty much screwed the farmers in the Great Valley ---not to mention 23 million people ----- out of a big hunk of their water supply.


Oroville is where most of the water supply comes from for the whole state of California.

[KaiserJeep]

The emergency spillway worked as designed, and prevented dam failure. If you want to call it a bad design, there is some merit there, but you don't line an emergency spillway with concrete, either - there is too much cost involved.

The regular spillway was undermined and the bottom collapsed about two thirds of the way down, due to poor maintenance. That's all water under the spillway, so to speak. It needs to be shut down for emergency repairs and backfilling with earth. Fortunately the rainy season will soon be over. Failure to have completed repairs in time for the next rainy season would comprise criminal negligence on the part of Moonbeam.

[Plantagenet]

Fortunately the rainy season will soon be over. Failure to have completed repairs in time for the next rainy season would comprise criminal negligence on the part of Moonbeam.

First lets see if the dam survives until next summer.

Right now more rain is predicted starting Wednesday----that means the lake level will start rising again. Will the repair on the regular spillway be enough to allow it to keep functioning? Will water reach the emergency spillway again? Will the spillways fail? Will the dam fail???

Git your popcorn ready....


Oh no....its RAINING AGAIN!!!!!! Look out California!!!! AAAAAaaagghhhhh!!!!!!!!!!

[potterpaul]

HV,

Really excellent post. Thanks.

potterpaul

[dohboi]

Seconded! Hvacman is a source of insight of a kind getting rarer and rarer around here lately.

[dohboi]

The fact that officials were trying to reassure everyone that everything was fine right up until they declared the evacuations should leave everyone a bit...worried who live downstream from a dam (or who eve drive over a bridge...)

[Cog]

Link to flood map, should the dam fail.

http://media.sacbee.com/static/newsroom ... dation.jpg

For reasons explained above, it is unlikely the dam itself could fail but parts of the spillway could.

[evilgenius]

I was joking with some friends yesterday about this. Some retired old man is sweating it out, knowing that he inspected that thing from the seat of his pickup truck up to a full mile away. Shit happens. It doesn't matter which party was in charge. It's more human nature than association.

I used to live in Southern California. Back when I did it hadn't rained much in years either. When we got our first big rains there was terrible flooding in the most unexpected places. People cut corners when they don't expect it will ever come back on them. Sometimes they do it for money, but mostly I think they do it for ease.

[KaiserJeep]

I was joking with some friends yesterday about this. Some retired old man is sweating it out, knowing that he inspected that thing from the seat of his pickup truck up to a full mile away. Shit happens. It doesn't matter which party was in charge. It's more human nature than association.

I used to live in Southern California. Back when I did it hadn't rained much in years either. When we got our first big rains there was terrible flooding in the most unexpected places. People cut corners when they don't expect it will ever come back on them. Sometimes they do it for money, but mostly I think they do it for ease.

No, the dam was in fact inspected and digital photographs have been released of cracks in the concrete spillway, along with the 2013 report recommending immediate spillway repairs. Moonbeam had other budget priorities, he buried the report.

As for your experiences in the LA basin, a famous engineer named Mulholland lined the LA river with concrete, and established "runoff areas" to protect the dense inner city area and the high rise buildings from sudden intense rainfall. Then he recommended that the runoff areas be reserved as parks. After his death, many of these runoff areas were built into suburbs. About every 30-50 years or so, these suburbs do what they were designed to do - they flood to save the downtown area. The real estate salespeople will never tell you you are in a runoff area, you have to figure it out for yourself. The usual clue is you get a homeowners insurance quote that is 3X as high as it should be.

Mulholland is infamous in some people's view. He designed the Mulholland Dam which forms the Hollywood reservoir. This dam never failed, but a near exact copy of this dam built by the Los Angeles Department of Water and Power at another site rejected by Mulholland did fail. The St. Francis Dam disaster in 1928 killed over 400 people.

[ROCKMAN]

KJ - Nice history report. Mucho thanks

[hvacman]

Update on the Oroville dam statistics as of 12:42 PM PST:

The real-time data for Oroville dam shows releases of 100,000 cfs through the damaged main spillway and 118,000 cfs total river release, which means they got the hydro plant back up and running (it can divert 18,000 cfs). Lake level now down to 887.53 feet (down 14 feet from the top 901' elevation). The DWR says their goal is to get it down to and hold it at 50 feet below the top, as this level coincides with the level of the damaged base of the emergency spillway, relieving all hydraulic pressure from the spillway structure's face and reducing the potential for catastrophic failure.

I don't think they have the ability to release flows through the main spillway at lower elevations, as the base of the main spillway control gates appear to be about 50 feet below the emergency spillway crest. That leaves just the hydro plant to further draw down the reservoir, at a much slower pace. It would appear the original engineers never foresaw the possibility that future operators might really want to rapidly draw down the reservoir deeper than that. Hmmmm.....

Here is a link to the real-time data:

http://cdec.water.ca.gov/cgi-progs/quer ... 2017+12:42

[Plantagenet]

Its all better now.

The evacuation order has been rescinded.

The California Water Department now remembers that you have to draw down lake levels in advance in order to create space in the reservoirs for the extra streamflow that comes in when rain is predicted by the weather service.

Apparently it had been so long since they had enough water to fill the reservoirs in California, that the operators of the Oroville Dam had forgotten how to manage the reservoir.


The people running the Oroville Dam need a remedial course in "Dam Management"

[KaiserJeep]

Damn dumb dumb dam managers.



I saw Moonbeam on TV, scrambling to make up for his oversight, and pouring every resource into the dam. His first official act is to beg Trump for Federal disaster funds - except of course, he doesn't yet have a disaster, he only has a potential disaster, and even that was entirely due to his neglect of dam repairs.

[Plantagenet]

Damn dumb dumb dam managers.



I saw Moonbeam on TV, scrambling to make up for his oversight, and pouring every resource into the dam. His first official act is to beg Trump for Federal disaster funds - except of course, he doesn't yet have a disaster, he only has a potential disaster, and even that was entirely due to his neglect of dam repairs.

You are exactly right. There was a big screw-up at the dam by the California DWP, but no disaster.

This is California's mess and its California's fault. California should pay 100% of the cost of the dam repairs they caused and California should also reimburse the 200,000 people it ordered to evacuate for the inconvenience, loss of work time and personal expense they suffered due to the incompetence of the Oroville dam managers.