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Reilly
Mountain climber
The Other Monrovia- CA
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Mar 13, 2017 - 08:46am PT
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Engineering and construction done right...
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Mar 15, 2017 - 02:41pm PT
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Looks like DWR plans to start using the damaged main spillway again this weekend.
http://www.mercurynews.com/2017/03/14/oroville-dam-spillway-flows-to-resume-this-week/
FYI, this photo posted on the DWR website shows an exposure of amphibolite but the caption refers to it as granite ;-( At least one of the people on that outcrop must be a geologist. Hopefully that caption was not reviewed by a geologist.
For the rebarbarians...
Here's a good closeup photo of the contact between the iron stained amphibolite overlying the blue-green, non-iron stained amphibolite. The contact is the obvious joint/fracture surface that the two individuals are standing on. The iron staining looks to be surficial along joint planes as you can see the blue-green amphibolite on freshly exposed surfaces. All the rock exposed in this photo appears to be competent bedrock, the "soft" weathered/altered bedrock now eroded away.
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August West
Trad climber
Where the wind blows strange
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Mar 15, 2017 - 06:33pm PT
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So using the spillway isn't causing additional damage. Rather, they are cleverly using hydraulic mining to remove the dirt so they can build on a solid foundation.
Nice.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Mar 15, 2017 - 08:31pm PT
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Rather, they are cleverly using hydraulic mining to remove the dirt so they can build on a solid foundation.
I'm glad someone is paying attention ;-)
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Mar 15, 2017 - 09:33pm PT
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Recent Feather River erosion of an almond orchard down stream of the Oroville Dam...
@ 11:30 in this Juan Browne video...
[Click to View YouTube Video]
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Reilly
Mountain climber
The Other Monrovia- CA
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Mar 16, 2017 - 09:57am PT
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TT, we rebarbarians thank you. So there was an upper and a lower mesh, sadly inadequate in any event: far too widely spaced! And why don't we see any of the transverse members as opposed to just the longitudinals? Also very telling is the fact that so much of the concrete was literally stripped off the rebar indicating a poor bond due to improper storage prior to pouring* and/or way too low of a cement percentage. Bottom line: way too little engineering and quality control.
*meaning heavy rusting or oily contaminants
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Mar 16, 2017 - 11:37am PT
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Reilly: maybe they'll get it right on the 2nd try, especially now that the "soft" rock has been removed.
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dirtbag
climber
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Mar 24, 2017 - 08:37am PT
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Thanks dingus. I had suspected (probably along with most people) that the problems would be too great to fix in one dry season.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Mar 24, 2017 - 08:53am PT
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Sounds like a complete rebuild, bottom up, of the main spillway ($500M - $1B). Likely to take > 1 year, meaning the farmers won't get their water.
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Carbo
Trad climber
Too far south
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Mar 24, 2017 - 09:15am PT
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Wouldn't they need the dam to be at least partly functional for flood control?
I think it's mostly the central valley that would suffer as Socal gets water from Eastern Sierra and Colorado river (Colorado supplies 80% of the water for San Diego)
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Ksolem
Trad climber
Monrovia, California
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Mar 24, 2017 - 01:12pm PT
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It seems to me that there is an elephant in the corner regarding any discussion of infrastructure in California...
When this elephant becomes a major topic in The Economist it might be time to get real.
...According to the Proposition 1A Bond Act, the high-speed rail project has to be financially viable; trains have to operate (without subsidy) every five minutes in either direction during the day; and funds for each segment of the route need to be identified before work on the leg in question can commence. Above all, trains have to make the 520-mile (840-km) journey between the Los Angeles basin and the San Francisco in two hours and 40 minutes, reaching speeds of 220 mph (350 kph). As for ridership, the rail authority reckoned some 65m to 96m passengers per year would be travelling the route by 2020. The basic fare was to be $55 one way.
That was all pie in the sky, a way of selling the deal to voters in 2008. A review in 2011 put ridership at a more realistic 30m passengers a year, with an end-to-end ticket price of $89. Meanwhile, the overall cost of the project had soared to $98 billion. And instead of going into service by the end of the decade, the high-speed railway would not be ready until 2033.
$100B could go a long ways toward stabilizing CA's water supply systems.
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Carbo
Trad climber
Too far south
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Mar 24, 2017 - 03:35pm PT
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Interesting DMT, we do buy some water from LA while most comes from Colorado and local resevoirs.
While we should all rip out our lawns and conserve, it seems the price just goes up as the Water District needs to make the same amount of money
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August West
Trad climber
Where the wind blows strange
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Mar 24, 2017 - 04:09pm PT
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Of course DWR is saying they can fix it enough to allow the dam to partially refill next winter, because of course their only reason for being is their water customers in Socal, east bay and central valley project. The people in Oroville are just in the way, inconviently.
For a dam of this size, wouldn't there be some sort of Federal permit required/certification? Anybody know?
I would find it mildly surprising if something like this was left entirely to state law.
And if the Feds are involved, I can't see them signing off on a half-ass fix.
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Ksolem
Trad climber
Monrovia, California
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Mar 24, 2017 - 04:17pm PT
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I would find it mildly surprising if something like this was left entirely to state law.
You raise an interesting question. For starters who is to say that the Fed would have done a better job?
Ripped off from Wiki:
On October 17, 2005, three environmental groups filed a motion with the Federal Energy Regulatory Commission urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen spillway and that it did not meet modern safety standards. "In the event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause a failure, known as 'loss of crest control.'" FERC and water agencies responsible for the cost of the upgrades said it was unnecessary and concerns were overblown.[31][32]
In 2006, a senior civil engineer sent a memo to his managers stating “The emergency spillway meets FERC’s engineering guidelines for an emergency spillway,” and that “The guidelines specify that during a rare flood event, it is acceptable for the emergency spillway to sustain significant damage.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Mar 24, 2017 - 06:28pm PT
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FYI, according to Wikipedia...water from Oroville Dam irrigates 755,000 acres (> 1,150 sq mi) on the Westside San Joaquin Valley & provides drinking water for 25M people.
https://en.wikipedia.org/wiki/Oroville_Dam
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eeyonkee
Trad climber
Golden, CO
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Mar 26, 2017 - 01:11pm PT
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Damn! Like those dam pictures, DMT.
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rottingjohnny
Sport climber
Sands Motel , Las Vegas
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DMT.. sounds like a cover up but we all know any misdeeds will be handsomely rewarded...
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Reilly
Mountain climber
The Other Monrovia- CA
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Nothing like living in a mature democracy, huh? Makes me feel warm and cuddly.
I'm wating for Guvnor Moonbeam's response, but I'm not holding my breath.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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My contacts in the drilling and geophysical logging industries tell me that when they're not using the Oroville Dam main spillway there's a drilling and subsurface characterization campaign going on involving multiple drill rigs that are continuously coring the geologic material beneath the spillway and running optical televiewer logs in the boreholes to identify any other areas of decomposed or highly fractured amphibolite bedrock. In addition to inspecting and describing the rock quality characteristics of the core retrieved from the borehole, an optical televiewer is deployed in the borehole that records a high resolution, oriented, digital optical image of the borehole wall. This is critical information for any interim spillway modifications and the permanent spillway replacement design.
One of the latest concerns is the brown colored water flowing on the left side below the broken spillway. This may represent piping or undercutting and erosion of decomposed bedrock beneath the spillway. Photo posted on DWR website Mar 27, 2017.
This is what that area looked like before the shotcrete. Note highly sheared/decomposed bedrock on the left side corresponding to the where the brown colored water is flowing shown above. Similar sheared bedrock is also evident in the middle of the spillway where the guy is on his knees...
The extent of that sheared/decomposed bedrock material, especially if it extends back up to the top of the spillway, is a bit disconcerting.
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