When the Levee Breaks

[Jimr]

Well, I found both the motion and response. I also found 397 additional documents filed. Fortunately, my scope was limited. I do see why Mr. Rogers wrote the article the way he did. I also think there is a bit of a slant with the implication that they (DWR & Metro) just didn't want to spend the money. If you believed that what was there, was within established requirements and sound from an engineering and geological stand point, why would you. The big question, since it is failing at the very first test, under much lower flows than designed is, did they really believe it was sound or were they just relying on meeting the requirements. I found where the last DWR inspection was basically a flyover. Hmmmm. Seems like an incompetent form of inspection to me. Since they are supposed to have it inspected every 5 years by an independent engineer (?), I would like to know what that report says.

[rlown]

They actually covered the FERC filing on KTVU-2. I was surprised.

They'll use the primary spillway until they can't. A good question was asked in another forum.. "where is the rebar?" not saying they didn't use it but the size of the hole in the primary and the pics don't point to rebar use.

Now back to youtube and clerks and clerks II vignettes.

[giantbrookie]

We should probably merge the two threads. Folks should be aware that it is catastrophic erosion around the auxilliary spillway that is the concern at this point NOT failure of the main dam as has been posted in some reports (including on the other thread).

There is still a flooding threat from major erosion around the auxilliary spillway but this pales in comparison to a breach of the main dam which would be a flooding disaster of epic proportions indeed. Fortunately the main dam is considered sound.

[rlown]

I have to say if the aux spillway fails, a 30' wall of water might have an impact.

[Wandering Daisy]

This next week's storms are supposed to bring 7 inches of rain in the next 10 days in the Oroville watershed. Thankfully the later storms are cold ones, mostly with snow. Well, maybe thankfully - we get the runoff one way or another. With as much snow as is piling up in the mountains, a speedy thaw could cause serious problems later. Snow levels are supposed to get down to 3-4000 feet next week.

I heard (not sure if it is substantiated) that if the spillway failed, it would stop at 30 feet due to hitting bedrock. I also heard, again who knows how true, that the "failing within the hour" was used for the evacuation to get people to comply quicker- a worst case scenario, not the likely. We actually had some really good news coverage today on Sacramento NPR.

[Tom_H]

WaPo article re. CA drought and current conditions:

https://www.washingtonpost.com/news/ene ... 2a19ca6cad

[druid]

It could well be that "failing within the hour" was a scare tactic designed to get people actually moving. On the other hand, there was a staggering amount of erosion from the day and a half of ~12000 cfs that went over the emergency spillway that was "rated" to handle 250000 cfs. And I wonder where this "bedrock" actually is that was supposed to limit the failure -- it doesn't appear to be anywhere near the erosion gashes that took out the spillway access roadway and threatened to undermine the emergency spillway itself, which is what prompted the evacuation, at least from what I read. It's hard to get reliable information, but one civil engineer interview I read in the Bee said it ultimately might not matter much if the main dam held, as erosion of the emergency spillway hillside could ultimately cause a good portion of the reservoir to drain eventually.

According to this article, something similar came close to happening to the Glen Canyon Dam in 1983. That is, the dam itself was in little danger of failing but there was concern that all of the water might be released anyway.

I makes me wonder if the current state flood situation isn't all that much different than it was in 1862 after all. Dams prevent a lot of minor flooding (and probably give people a false sense of security) but it remains to be seen if they will make things better or worse when the "big one" hits.

[rlown]

Oroville has a new irrigation capability.

[youtube_vid]<iframe width="854" height="480" src="https://www.youtube.com/embed/fhwlJD4ENn0" frameborder="0" allowfullscreen></iframe>[/youtube_vid]

[ERIC]

I makes me wonder if the current state flood situation isn't all that much different than it was in 1862 after all.

I was totally with you until this. Following this logic, if one 777 crashes then we should assume every 777 down to a Cesna not only can, but will, crash. CA has a lot of flood infrastructure. Not just dams but conveyance. Sure, no solution is perfect. But let's be realistic.

[druid]

I agree that sentence wasn't phrased very well. I don't doubt that most or all of today's infrastructure would mostly continue to work even in an 1862-like event. But that wouldn't be much consolation for the people downstream of a dam that failed catastrophically with little warning. So, not the same as 1862, probably much better for most people but possibly much worse for an unfortunate few.