California spillway collapse

They should just do a controlled breach now. Blow out a 5-foot notch, stick a big pipe in it so it doesn't erode the embankment, let that drain out, and repeat as often as they need to. Better than a 30-foot wall going at once. Do it while it's still dry.

 

You should all encourage your elected officials to support Valadao's GROW Act.

 

Two public FB posts by John Ringo, bestselling military science fiction writer. I'm not an engineer, but I strongly suspect that the general sense of this is accurate, and it's a no bullshit assessment. He's a right wing kinda guy, so if you get that sense you are correct. Still, lots of good analysis here.

1.
"Sooo... Let's talk about Oroville.

Usual caveat: I'm the son of a civil engineer, not a civil engineer. That being said, what you have here is an engineering failure. The real failure was the emergency spillway, not the 'GOTH-plan-emergency back-up-please-God-we'll-never-have-to-use-this' spill-over system that triggered the evacuation. (Frankly, they should have evacuated when they had to go to that at all.) GOTH = Go To Hell Plan

But let's first talk about how you build a spill-over system then talk about the main reasons they fail. Then look at what happened in Oroville.

The way you build a spill-over like the long concrete one, which is called a 'flume', goes like this:

1. You determine the best route, taking into account that in the event of a failure you don't want it to impact on the primary dam. (Which would be the real 'OMG WE'RE FUCKED' crisis if it took damage.)

2. You determine what is the current geological sub-structure.

(The two above fall into the category of 'feasibility studies.)

3. You determine how best to use the sub-structure to support the structure.

4. When you build the structure it goes like this:

5. Remove the majority of the substructure down to a point that is determined by its nature (what the soil underneath is like) that you can build a good foundation.

6. Refill that area with 'clean' dirt. The soil has to be of a certain consistency (not too much sand or clay material) and lacking 'organics', vegetation such as tree branches and roots, otherwise they'll later decompose and cause 'voids'.

7. Pack the dirt down (compression) to a particular level using compactors. Generally, that means laying down a six inch layer of dirt then compacting it. Do that over and over in the formation to take the concrete of the main flume. As compactors have improved, some states have allowed thicker layers. But last time I checked, 6" was the general rule. (And it's a regulation in engineering.)

8. Pour your flume. The concrete material has to meet certain standards. It can't have too much cement (the binding agent) nor too much sand (the primary agent) nor may it have the 'wrong' sort of water (chemicals in the water can affect the concrete). Concrete, alone, is a very complicated material. One item with most flumes is that the concrete has to be made of materials which harden in the face of water. Those types of cements (colloquially called 'Roman' cement vs 'Portland' cement) are more expensive than common cements.

9. The flume has to be capable of expansion and compression. Concrete expands and contracts under environmental pressures.

10. The flume has to be monitored and maintained. Even with the best possible engineering and construction (two different things), you're going to have environmental wear and tear. It has to be checked to ensure that nothing is breaking.

So let's talk about some of Dad's experiences in general but specifically in California.

His take was that CA grading contractors (the guys who put down the dirt and compact it) were 'the most corrupt and lazy bastards I've dealt with outside the third world.'

CA grading contractors habitually:

Tried to get away with not doing specified compaction. Because if you can lay down twelve inches of dirt instead of six you spend half the time. And since you're getting paid the same you make twice the money. (More or less.)

Regularly included 'organics' including large tree stumps. Because filtering the dirt costs money. And they can't see it from their house.

Concrete contractors frequently tried to deliver substandard concrete.

When Roman cement was specified they frequently delivered Portland cement concrete then tried to blow it off by saying either 'we didn't know it was different' or 'it's basically the same thing'. (It's not. Portland cement will not harden in the presence of water.)

Regularly over or under watered concrete. Generally overwatered. Overwatered concrete is often easier to lay down. But it also layers and creates voids.

Cement also hardens unevenly when laid down in certain temperature regimes. Dad had a screaming match with a CA government inspector over whether concrete could be laid in cold conditions. The inspector was just fine with it because shallow, narrow, concrete lays are generally fine down to below freezing. But. They were doing a thick concrete lay which in cold weather causes layering which can lead to failures.

What caused the flume failure will probably be forever unknown. All the evidence has been washed away. That being said, here's the most likely scenario:

There was an area under the flume which was:

a. Poorly compacted.
b. Probably included organics.

This created a weak support structure for the concrete body of the flume which lead to:

a. a leak. Which
b. increased the void area. Which
c. lead to a larger leak as the concrete around the initial leak started to fail.

The above scenario would have been exaccerbated if:

a. the flume was constructed of poorly poured or mixed concrete.
b. There was poor maintenance of the flume. Maintenance should have included
c. regular sonar and ground penetrating radar 'walks' of the flume to check for voids and leaks.
d. color or radiological leak flow detection.

Engineering failures like this don't come out of the blue. A properly constructed, maintained and engineered flume should last a century. That this one didn't means one of the three, or possibly all three, were done improperly. But even very good maintenance and inspection should have at least given some warning.

Engineering and construction is expensive. Good engineering and construction is more expensive in the short run than bad engineering.

Bad engineering and construction will bite you in the ass enormously.

They're made even worse when there's poor inspection and maintenance.

Alas, given there is no evidence on which to base anything and given that most of the companies involved in construction are probably long defunct and given that it's CA which means its going to be lots of finger pointing and nothing done, don't expect this to be the last such issue.

BTW: Screaming about the 'Go To Hell Plan' final overflow being 'not properly reinforced' is an utterly fucking pointless distraction. It was only necessary because of the other failures and at the end of the day worked exactly as designed. (Including all the erosion.)"

 

2. "
2."Okay, about Oroville again.

I stand by all of the below:
https://www.facebook.com/john.ringo.90857/posts/10154234841900887?pnref=story

That being said.

As part of the discussion, it was revealed (new information to me) that in 2012 the dam was 'redesignated' as a reservoir primary and generation secondary. But it was DESIGNED as a generation primary, reservoir secondary.

"So what?" you might ask. "Does that matter?"

I'm sure that people like Governor Moonbeam would ask that question.

YES IT FUCKING MATTERS.

The simplest metaphor is this: You're driving along and you see a bridge. The bridge says 'No trucks, cars only, no vehicles over a certain weight.' We've mostly seen bridges like that. Say it's in your local area.

Then one day some politician says 'We're 'redesignating' flimsy bridge to be a RAILROAD BRIDGE. Because: Reasons.'

Some people who have any knowledge of physics might take exception to this. Because if it can't handle a truck, IT SURE AS SHIT CAN'T HANDLE A TRAIN.

How does this factor into Oroville...

(Sigh... Here we go.)

The way dams work is during periods of high flow, they fill to a certain level. Then during periods of low flow, they slowly drain to supply whatever they are designed to supply.

With primary generation dams, during high and low flow they generate. They are designed to only fill to a certain point and the generation is designed for the estimates of average flow rate. When they get REALLY low you stop generation. But the never get REALLY HIGH cause you're generally ahead of the flow because you're making lectricity. But sometimes flow is SUPER HIGH. And you have to go to max. Rarely. Once in a hundred years sort of thing.

Then you use your 'emergency spillway' and everything is under control.

Thus the 'emergency spillway' (flume) is only used IN EMERGENCIES. The 'spillover' (which started to fail and triggered the evacuation) is putting on belts and suspenders you're never going to need. (Indicating good design, by the way.)

With RESERVOIRS you want them to get REALLY HIGH so that you have lots of water for hungry customers.

Thus RESERVOIRS are designed to fill ALL The Way To The Top.

Generation lakes are designed to fill PART of The Way To The Top.

Repeating: Geneator lakes only go to All The Way in emergency situations. And when they get REALLY FULL then there is an 'emergency spillway' that lets off the flow. (See also: Flume)

RESERVOIRS have multiple emergency spillways designed to take off full maximum flow because you want them to fill ALL THE WAY UP.

You can use them for both but they are primary for one or the other and the ENGINEERING DESIGN AND CONSTRUCTION are VERY VERY DIFFERENT.

(I know I repeated myself but are we all clear...? Yes? Questions? Moving on...)

So in 2012 some DOUCHEBAG decided without ANY CHANGE IN DESIGN to 'redesignate' Oroville as a RESERVOIR when it was designed as a GENERATOR.

Now the whole thing in 2012 about 'environmental' groups wanting the emergency overflow rebuilt makes perfect sense. Just out-of-the-blue it sounded like idiot environmentalists.

No. It sounded like something the AMERICAN SOCIETY OF CIVIL ENGINEERING should have supported.

The flume which failed WAS NOT DESIGNED TO BE USED ON A CONSTANT BASIS. It was not constructed to be used on a constant basis. And I'll be dollars to donuts they didn't increase maintenance on it.

And then we get to the dam itself.

Water has mass. It exerts power on whatever it is up against. When a dam is designed to hold water up to, say, its 60% height most of the time with some periods when it gets to 80% height but only in emergencies gets to 100%...

But instead is regularly at 80% and occasionally gets near to 100%...

Then you have an issue with the dam itself. Which is kitty bar the door...

OH, MY FREAKING GOD! THE STUPID IT BURRRRRRNS PRECIOUS!

'Redesignating' it a 'reservoir' if California was in a 'permanent drought' makes sense. If it was never going to go to 100%.

But letting it get NEAR 100% not to mention REGULARLY USING AN EMERGENCY FLUME was FREAKING INSANE.

Thus in all likelihood the primary reason the flume failed was it WASN'T DESIGNED OR CONSTRUCTED TO BE REGULARLY USED. I was wondering looking at some old sat photos why the end was all torn up. Now the reason is obvious because IT HADN'T BEEN DESIGNED FOR CONTINUOUS USE.

The idiocy, the lack of foresight, the stupid... It really just boggles the mind.

You don't use a bridge barely designed for cars as a railroad bridge.

You don't use a spillway designed for emergencies as a regular system.

You don't use a dam designed for generation and moderate levels for a maxed-out reservoir.

Unless you're a complete flipping idiot.

Wait, I take it back. This is California.

Of course you do.

There are no words.

The stupid, it burns."

 

Spillway problems and epic rainstorms caused the Johnstown Flood and it sounds as if the situation in Oroville might be eerily similar.

David McCullough's book The Johnstown Flood will give you an idea of how bad this could be.

 

Before we're so quick to point fingers at the usual suspects: Who was the governor of California on watch when Oroville Dam was completed? I forget.

 

You post this with a sly smile?? I've been thinking about this for a few days, that Edmund G. Brown Sr. was the governor when a lot of the state's water issues were being dealt with back in the early '60s. He created the California Aqueduct, which is very cool. A lot of the comments I read this morning have the state officials playing the CYA game.

 

Trying to pin everything solely on Ronald Reagan when he just did the ribbon cutting a half century ago after a decade-long project serves no useful purpose. Let there be an actual investigation. I'd guess it will turn up plenty of malfeasance to be shared through the years.

 

Sorry for the brain fart on the dam/spillway mistake. As a tailwater trout fisherman, I certainly spend enough time around both to know the difference.

 

Butte County Sheriff Kory Honea: Butte County lifts immediate evacuation, Oroville residents may return home

 

The stunning destruction at Oroville Dam and the work ahead