[Synapsid]

pstarr,

Many a gardener has been fooled, I've been told, by the dark soil that serpentinite can weather to. It looks like just what you want for your plants but they get hit by magnesium poisoning.

Art Kruckerberg, who died I think it was last year, was the chair of the Department of Botany at the University of Washington for years, and he made a career study of flora adapted to soils derived from serpentinite. It's worth looking up his works on the subject; he was pretty much the authority on the subject, I guess, and he wrote well. Neat guy, too.

[hvacman]

The expert opinions on the spillway failure are starting to roll in. Things are not looking good:

http://www.sacbee.com/news/state/califo ... 90898.html

http://www.mercurynews.com/2017/03/22/o ... structure/

[Cog]

As those articles explain there is not a sufficient dry period to replace the entire spillway. There might be enough time to repair the section that has eroded away depending on how wet the summer is. That will still leave you with the other sections of the spillway with voids under a too thin concrete slab sitting on a crumbly bedrock.

There are times you want to over-engineer structures like this to withstand conditions that are in excess of what you expect to happen. This was one of those times.

[hvacman]

The smart and safe thing to do would be to drain the reservoir all the way down and keep it there as much as possible through next winter so they don't even have to think about using the main spillway and can actually engineer and execute both a proper replacement for the damaged section and complete a forensic engineering investigation of the remaining intact portions to determine it's actual condition. Concrete core samples. Underlying rock tests. Void tests. re-bar surveys. Then they can make a decision of rehabilitation vs total replacement. We're talking not just one summer, not just one year, but multiple years before the main spillway could be brought back into service with any confidence.

But they may not be able to do that, as once the lake gets down to 813 feet, they have hit the bottom lip of the main spillway gates and the only way out for the remaining 2.5 million acre-feet of water is to drain it through the hydro plant. As the record snow-pack melts will create summer inflows almost equal to the hydro plant's capacity, so the lake would drop very slowly. Reports of the high mountain snowpack is up to 10 feet of net water content. We'll have the final count for expected inflows April 1 after the final snow-pack assessment, but the number will be HUGE. The DWR, the water contractors relying upon water from Lake Oroville in the future, the residents downstream of Oroville Dam who rely upon Oroville's flood protection, and the State of California which will have to ultimately foot the bill are all royally, royally, royally-screwed.

[hvacman]

Good time to money wrench it and set the salmon free. We'll all going to die anyway, might as well go out with a bang

You ever been to the Oroville dam, Pete? It is a sight to behold, if you like giant piles of dirt. 77 million cubic yards of it. I wanna see the monkey wrench that can set its salmon free. It takes moving heaven and earth to just take down a little-ol' diversion dam. It took 8 years of giant earth movers to pile up the dirt to make the 770'-tall Oroville dam. Even if the emergency spillway had blown completely out, that would have just been a hole in the top 50 feet of that dam. 720 feet of dam still left. Even though it is an earth dam, erosion wouldn't do the trick, as the sediment would just make multiple dams downstream, eventually plugging up the Delta. And even if most of the dirt was washed away, you would get to the concrete core in the heart of it, which is a sizable dam structure in itself. Any way you look at it, Oroville dam is a prime example of the Anthropocene...man has cut off salmon migration up the Feather River for eons, even if we as a species go extinct...

[hvacman]

A very powerful technical analysis presentation by several local (to Chico/Oroville) engineers, Chico State professors, water project managers, and geologists who really know dams, local geology, the DWR, and Oroville Dam specifically. Great Q&A afterwards. This is powerful stuff and well worth the time to watch the whole video. The best analysis I've seen to-date from any source. I'm going to watch it again this weekend to make sure I didn't miss anything.

https://www.youtube.com/watch?v=8CEXOkd3544

[hvacman]

A nuke then?

It seems the Dems are aching to use one against the Russians. Why not use one for a good purpose?

Yeah, nothing says "Save the Salmon" like 100 megatons of dam-destroying thermonuclear energy and radiation;)

[KaiserJeep]

hvacman, I'm not sure how "smart" it would be to drain the second largest reservoir in this state after a 5+ year drought. We don't know if one really wet year following one average rainfall year actually represents a flipping of the rainfall patterns in the state from "dry" to "wet".

I think the smart thing to do is to lower the water level for flood control purposes, but retain enough water for a couple of dry years. We are after all, aware that there is a problem with this dam. But not having enough water is also a problem.

[hvacman]

I recently listened online to a panel discussion at Chico state of local hydrologists, engineers, and geologists with a wealth of dam design and operation experience and with very specific experience with the seasonal flow patterns and capacities of the Oroville reservoir, and the current condition of its level regulation structures.

One of the engineers lives in Oroville. He opined that, despite the huge economic value of the stored water in the reservoir, with his and his family literally living below the dam, he would very, very much recommend the reservoir be drained "so low that there is storage room for "Noah's flood" without having to rely upon either the main or emergency spillway for level control".

I suspect we would see the locals taking up pitchforks and pouring hot tar to any DWR officials who try to store much water in that reservoir before both the main and emergency spillways are completely reconstructed from top to bottom and control gate structures at both spillways that meet current dam operation standards. Would YOU live in the shadow of a 770-foot high dirt wall holding back a humongous wall of water, with a watershed upstream of it that could pour up to 4 million additional acre-feet of water into it in less than a year, and with a completely broken overflow system?

Drain it dry until permanent repairs are made. I believe that when we get the final reports from the various governmental agencies investigating this situation, that will be the recommendation. So, yes, this year's wealth of water only goes to extend the "drought".

[hvacman]

Oroville Dam report to be "secret" - Sacramento Bee

Citing potential pointed and extremely-embarrassing-to-answer questions from the press and public security risks, state and federal officials have blocked the public’s ability to review the latest report from an independent panel of experts brought in to guide state officials’ repairs at the crippled Oroville Dam.

http://www.sacbee.com/news/state/califo ... 63119.html

[Cog]

LOL They think someone is going to blow up the dam now? Like you said, hvacman, they are embarrassed and trying to cover how bad the situation is.

Not about the dam failing in the future but the failures that led us up to this point.

[Outcast_Searcher]

One of the engineers lives in Oroville. He opined that, despite the huge economic value of the stored water in the reservoir, with his and his family literally living below the dam, he would very, very much recommend the reservoir be drained "so low that there is storage room for "Noah's flood" without having to rely upon either the main or emergency spillway for level control".

I certainly hope the final decision is made by a group of engineers who aren't influenced by living in harm's way of the dam. I sympathize with his situation, but that situation doesn't bode well for truly objective decision making on this.

[hvacman]

The DWR releases their plan for spillway re-construction and identifies the four contractors in the running for making the repairs - Sacramento Bee

OROVILLE

The repair job at the battered Oroville Dam spillway lacks a price tag and a finalized design. But it has drawn the interest of four leading construction contractors, all with experience in big dam projects.

The four contenders for the project are Kiewit Corp. of Omaha, Neb.; Granite Construction of Watsonville; Barnard Construction Co. of Bozeman, Mont.; and ASI Constructors Inc. of Pueblo West, Colo., according to the Department of Water Resources.

DWR released its repair plan Thursday, acknowledging the work won’t be finished until 2018 and will leave the fractured spillway partially undone when the next rainy season begins this fall. Nonetheless, Acting DWR Director Bill Croyle said the 3,000-foot-long concrete chute, whose problems led to a near catastrophe in February, will be functional by the time the rains arrive in November.

http://www.sacbee.com/news/state/california/water-and-drought/article143200489.html

From the San Jose Mercury News, we learn that because the DWR will not get the existing lower spillway fully repaired this year and peak spillway flows will be limited to 100,000 cfs. This will compromise their flexibility for reservoir level management next winter.

Oroville – The state Department of Water Resources Thursday outlined its plans for repairs and replacement of the Oroville Dam spillway by Nov. 1, with the undamaged top chute as the priority. At an afternoon press briefing, DWR Acting Directory Bill Croyle said the lower portion of the spillway would also be repaired by Nov. 1 to withstand a maximum outflow of 100,000 cubic-feet per second.

One good note from the Mercury News coverage - the final spillway design, when all parts are installed and/or upgraded to current standards, will have an upgraded capacity of 270,000 CFS. The old spillway was only rated at 150,000 CFS. This higher discharge rating will further reduce the possibility of the emergency spillway ever coming to play. How much will all this cost? No one is talking anymore. Will the DWR even release the bid amount for the successful bidder?

http://www.mercurynews.com/2017/04/07/oroville-dam-dwr-unveils-plans-to-replace-damaged-spillway/

[hvacman]

The Oroville Spillway failure joins Katrina and Deepwater Horizon as a failure worthy The UC Berkeley Center for Catastrophic Risk Management's attention

Watch this excellent video by Juan Browne. He breaks down and explains in layman's terms CCRM engineer Robert Bea's independent engineering analysis on the root causes of the spillway failure. Juan - a commercial pilot who lives in the Sierras above Oroville - has provided the best coverage I have seen of the Oroville spillway failure, going right back to its beginnings in early February. His Youtube channel is "blancolirio"

https://www.youtube.com/watch?v=1zqai2FodQg

Here is a link to the LA Time article and the full report by Robert Bea from the UC Berkeley Center for Castastrophic Risk Management. Bea also provided analysis on the Deepwater Horizon blowout and the New Orleans Katrina levee failures.

http://documents.latimes.com/report-fin ... -spillway/

Finally, we have a winner! Kiewit Construction was the low bidder for reconstructing the spillway - $275 million (plus the inevitable and enormously-profitable change-orders!!!)

Out of time right now, but tomorrow I'll edit and post Bea's executive summary text from his report for those who don't have the time to watch the video or read the report.

Like most disasters, Oroville's spillway failure was a combination of nature, engineering failure, construction failure, and maintenance failure colliding.

[vtsnowedin]

Hhvacman the LA times report seems very thorough and professional.

It seems an immense task to repair. The USA once rose to these events with alacrity and engineering prowess. I hope "the lowest bidders" know what they are up against.

Gas

While the quantities of material required are huge there is nothing especially difficult about this project though some will pump it up to get an award or two. This is much less difficult then building inside an operating airport or building a highway or tunnel in an inner city while maintaining traffic unimpeded. Why there isn't even a caisson to sink a foundation in a hundred feet of water and two hundred feet of muck.