Sunday, February 12, 2017

Wow - This is intense. I thought they had dodged a bullet(For a few days).  Evacuation orders for low levels of Oroville.

We have sort of entered the world of the unknown. Oroville only has about 16 thousand people. But rain is suppose to come mid week. Four storms are coming. I'd be surprised if the dam could be compromised.... but?

5 comments:

Post Alley Crackpot said...

When I made all of those jokes, I actually did look at the site planning ...

The chunky concrete debris eventually gives way (literally) to erosion through the sluiceway that will weaken the dam, which is itself an earthen dam rather than one made of concrete.

The "wonky trapezoid" I mentioned would wind up having "two wings", and the one on the side of the dam would eventually cause as much as half of the dam to weaken, but there will be problems well before the damage would get that far.

Some engineers in California said as much as I suspected, but I don't think anyone heard them.

Controlled demolitions along the footpath in the "emergency sluiceway" won't help because there's a downstream flow limit problem that's a bigger problem.

100k cubic feet/second may be all that the downstream dams are rated for -- it doesn't look like they're up to the task of handling a large deluge. You might not have noticed them in the middle of Oroville, but they remind me of the surprisingly small dams that are meant to hold back the Great Ouse in England.

In fact, there are as far as I can see no places where controlled demolitions would do any good, and it's possible they could do a considerable bit of bad.

People seem to be wanting some action out of the State of California ...

But as far as I can tell, all of the options that involve heroic immediate action are probably very bad options.

Running like blazes the first chance you get would in fact be a very, very good option.

she said: said...

I imagine you did. It's the kind of thing engineers like to do. ;)

To be fair about the people not listening, they are trying to be hopeful and not panic people. They are careful not to call it a failure, but if the Lake drops 30 feet and some have said could happen - that is a effing failure. Just because it doesn't totally fail - doesn't mean it nots *a* failure.

I really only thought it would walk up to the limit and surface tension would be enough - but who knows what happens next. All the storms this year start in the North and are being pushed to raze down by Hawaii. I think it's unknown what type of water content is in them. So.....

Thankfully I'm several hours South. Like or so an hour below Sacramento.

she said: said...

Oh, as a follow up. I think everything downstream is rated for 150,000 cfs. Even down to the levees. HOWEVER - before Obama and the recession (put it in whatever order you want) all people were bitching about is how the levee system in Sacramento was "the Next big thing" to cause catastrophe. I'm sure they have been maintained in a similar fashion as the dam. So... the real answer is nobody knows.

Post Alley Crackpot said...

Different country, different time, same ruddy awful politicians ...

http://hansard.millbanksystems.com/lords/1938/feb/08/great-ouse-flooding

Let's check in with 1938 and the House of Lords, shall we?

"My Lords, it will be within your Lordships' knowledge, as reported in the Press, that a short time ago the catchment board of the Great Ouse River came to the conclusion that they were unable to proceed with the major scheme necessary for that area because they were unable to raise the contribution of 25 per cent. of the total cost which His Majesty's Government were asking them to make. I should like to take this opportunity of asking your Lordships' House to review this matter because this marks another year of postponement, another year of dangerous drift in this very critical matter."

Things did not work out all that well for the people in that area at that time, in case you were wanting the shorter version.

I'm not just an engineer, I'm a politician-hardened cynic as well. :-)

she said: said...

Is it really cynicism if they keep proving me right? That is just called reality. Right? Sorry about getting your profession wrong. I though you had said that in previous comments. But I do have a bit of the ADD.