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  1. #301
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    Quote Originally Posted by Moe Ped View Post
    Sure: Oroville Dam earthquake investigation may be needed | The Sacramento Bee

    There are others. This is more book-ish: EARTHQUAKE AND LAKE LEVELS AT OROVILLE, CALIFORNIA

    And your reason for linking a 1951 book is?
    My apologies and thanks for posting the links. Interesting read but I don't get a sense for how great the seismic risk is. It's also a bit counter-intuitive. I would have thought the activity would increase as the reservoir filled due to isostatic loading but it appears the opposite is true.

    And the reasoning behind posting a 1951 book is that contains the geological assessment of the dam site. Seems clear enough.

    Quote Originally Posted by EddyKilowatt View Post
    So one would hope, so I have been telling friends all weekend (well not the "metavolcanics" part)... but then why do we have a garage-sized erosion feature advancing right to the toe of the spillway weir after just 36 hours at a paltry flow rate?
    This is the million (billion?) dollar question. The dam and main spillway are pinned to bedrock but the emergency spillway is sitting on concrete weirs on top of surface soils. Not sure if that's actually true or not but it sure looks that way.

    OT: The Oroville Reservoir situation-spillway-erosion2.jpg
    Source: Major sinkhole on spillway at Lake Oroville - LA Times
    Last edited by rockman; 02-13-2017 at 06:49 PM.
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  2. #302
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    Quote Originally Posted by rockman View Post
    My apologies and thanks for posting the links. Interesting read but I don't get a sense for how great the seismic risk is. It's also a bit counter-intuitive. I would have thought the activity would increase as the reservoir filled due to isostatic loading but it appears the opposite is true.

    And the reasoning behind posting a 1951 book is that contains the geological assessment of the dam site. Seems clear enough.



    This is the million (billion?) dollar question. The dam and main spillway are pinned to bedrock but the emergency spillway is sitting on concrete weirs on top of surface soils. Not sure if that's actually true or not but it sure looks that way.

    Click image for larger version. 

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    To put the earthquake matter to bed here's the best link, couldn't find it earlier: https://watershed.ucdavis.edu/shed/l...e/Oroville.htm

    This is where I got accurate figures of the dimensions of the emergency spillway.

    Of interest is that it notes that during the earthquake no structural damage occurred to the dam facilities but that the generators did trip off-line.

    Also interesting is that it is generally accepted that the stresses from the weight of the water behind the dam is what triggered this quake.

    Where do you see that the main spillway is "pinned to bedrock"?
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  3. #303
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    Quote Originally Posted by Moe Ped View Post
    To put the earthquake matter to bed here's the best link, couldn't find it earlier: https://watershed.ucdavis.edu/shed/l...e/Oroville.htm

    This is where I got accurate figures of the dimensions of the emergency spillway.

    Of interest is that it notes that during the earthquake no structural damage occurred to the dam facilities but that the generators did trip off-line.

    Also interesting is that it is generally accepted that the stresses from the weight of the water behind the dam is what triggered this quake.

    Where do you see that the main spillway is "pinned to bedrock"?
    Actually I don't know that's pinned per say like the foundation of the house. Just an assumption from looking at pictures. It's clear they excavated down to bedrock, although some of it may be soft because it's jointed. And the main spillway is on top of bedrock. Look at the pics of the hole as well as the bedrock buttress at the base.

    Just saw this on twitter. Look where they're dropping the sandbags. This can't be good. https://twitter.com/KTVU/status/8312...rc=twsrc%5Etfw
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  4. #304
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    Quote Originally Posted by rockman View Post
    Just saw this on twitter. Look where they're dropping the sandbags. This can't be good. https://twitter.com/KTVU/status/8312...rc=twsrc%5Etfw
    That sort of says that they had water going under that end of the emergency spillway. Damned gophers...
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  5. #305
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    Quote Originally Posted by Moe Ped View Post
    That sort of says that they had water going under that end of the emergency spillway. Damned gophers...
    That was my conclusion as well. I can't find it atm but I saw one report that mentioned seeing a boil on the water surface next to the spillway.

    Anyhow, here's a pic of the main spillway from the 1968 dedication ceremony and it sure looks like it's excavated into bedrock. Pixel - California Department of Water Resources
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  6. #306
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    Quote Originally Posted by rockman View Post
    That was my conclusion as well. I can't find it atm but I saw one report that mentioned seeing a boil on the water surface next to the spillway.

    Anyhow, here's a pic of the main spillway from the 1968 dedication ceremony and it sure looks like it's excavated into bedrock. Pixel - California Department of Water Resources
    That certainly looks rocky if not solid rock. Less so on the opposite side.

    That ravine the chopper is dropping the bag of rock in is actually on the downstream side of the weir @ the parking lot; I checked on Google Earth. So that's not near as bad as it first seems.
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  7. #307
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    Going to be some good panning just downstream this summer...


    OT: The Oroville Reservoir situation-49er.jpg

  8. #308
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    Quote Originally Posted by rockman View Post
    Just saw this on twitter. Look where they're dropping the sandbags. This can't be good. https://twitter.com/KTVU/status/8312...rc=twsrc%5Etfw
    Well that's terrifying.
    :wq

  9. #309
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    Political bickering in this thread is ever so mild compared to some other forums on this topic.

    Here's my mild rant:

    Somewhat off topic, this perilous circumstance is a clear example of the 20th century's legacy of problems.

    Generations after will inherit a complex variety of technical responsibilities.

    Perhaps the most egregious ones are nuclear reactors. These facilities are aging.

    Short term thinking, and immoral acts (to define morality cannot be expounded upon here) have tangible results.

    I don't know if it's been mentioned here, but Anderson Reservoir is over-filled right now.

    It does appear to me that many of the titanic public works of the past century, and the personalities and agencies involved in their creation are insane.

    Why is technical ability and the desire to wield it apparently more seductive than intelligence, patience, humility, and empathy for future generations?

    In aggregate the human race behaves as though it is ethically ignorant.

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  10. #310
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    As if the water itself isn't enough, I have heard rumours from knowledgeable folks that the as built plans for the dam show some of it built on mine tailings from the gold mining around gold rush times. Putting tailings under a dam or spillway for fill is certainly cheaper than properly disposing of them, but what is now going down the Feather river? These tailings would be a toxic mix of heavy metals and mercury left over from the gold rush.

    Is this true? I hope not.

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    Quote Originally Posted by telemike View Post
    As if the water itself isn't enough, I have heard rumours from knowledgeable folks that the as built plans for the dam show some of it built on mine tailings from the gold mining around gold rush times. Putting tailings under a dam or spillway for fill is certainly cheaper than properly disposing of them, but what is now going down the Feather river? These tailings would be a toxic mix of heavy metals and mercury left over from the gold rush.

    Is this true? I hope not.
    Yes; dredger tailings---probably not as nasty as tailings from hard rock mining:

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  12. #312
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    Quote Originally Posted by telemike View Post
    As if the water itself isn't enough, I have heard rumours from knowledgeable folks that the as built plans for the dam show some of it built on mine tailings from the gold mining around gold rush times. Putting tailings under a dam or spillway for fill is certainly cheaper than properly disposing of them, but what is now going down the Feather river? These tailings would be a toxic mix of heavy metals and mercury left over from the gold rush.

    Is this true? I hope not.
    It's all large sluice dredge tailings. No stamp mills or anything using mercury. Out in that area it was the floating barge dredge sluices. Take a look at google maps aerial and you can really see what they are talking about. It's all cobbles from baseball to basketball size and larger. There's that gold mining show called Gold Rush where they're using one of this style if you want to see it. There's also one in the Yuba Gold fields in either Teichert or Nordics (can't recall which) quarry operations out there.
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  13. #313
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    Irony:

    The much reviled Sierra Club, among other organizations, asked that the emergency spillway be lined with concrete in 2005. This did not happen.

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    Quote Originally Posted by Buzzaro View Post
    It's all large sluice dredge tailings. No stamp mills or anything using mercury. Out in that area it was the floating barge dredge sluices. Take a look at google maps aerial and you can really see what they are talking about. It's all cobbles from baseball to basketball size and larger. There's that gold mining show called Gold Rush where they're using one of this style if you want to see it. There's also one in the Yuba Gold fields in either Teichert or Nordics (can't recall which) quarry operations out there.
    Dredgers used as much mercury as did the stamp mills, it was the best/only way back then to recover the "fines". If you google it you'll find that in some areas the mercury levels are well above what is considered toxic.
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  16. #316
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    the rain effen sucks.

    i am too old to work the 8 pm to 8 am shift i am about to go on..that highway aint gonna open itself.
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  17. #317
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    Quote Originally Posted by Finch Platte View Post
    About four weeks of rain. 160,000 people evacuated, I80 was closed for a day or two, 50 now closed "indefinitely". If only we had money for infrastructure around here.
    :wq

  18. #318
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    Quote Originally Posted by nachomc View Post
    Well that's terrifying.
    must have been extra sacks of rocks.

  19. #319
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    Quote Originally Posted by rockman View Post
    Just saw this on twitter. Look where they're dropping the sandbags. This can't be good. https://twitter.com/KTVU/status/8312...rc=twsrc%5Etfw
    I need to build up some jumps and berms, can they drop a few of those SACKS down on my track!? ;-)

  20. #320
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    this is relevant


    OT: The Oroville Reservoir situation-16602513_1347968691945150_364114368087941082_o.jpg
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  21. #321
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    Quote Originally Posted by cragnshag View Post
    Going to be some good panning just downstream this summer...


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    That's exactly what I was thinking too.
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  22. #322
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    Lots of new info since I checked in yesterday:

    This LA times article has a cartoon, sourced from DWR, that shows the emergency spillway directly on the ground with no pinning. That's not good, but for an "emergency" spillway probably about all they could justify. The other part to consider is that while the area overall is technically underlain by bedrock, unless it's freshly weathered like in the channel of a canyon or like pluton domes (yosemite et al) there is usually a considerable weathering rind that exists. Depending on all sorts of conditions (soil type, moisture, bedrock type) you can have a pretty good thickness (10 feet? 20 maybe?) of slowly degrading bedrock. Hard to explain but like the soil sort of progressively grades into competent (re: hard) bedrock. So what you saw from the runoff was the removal of that weathered bedrock rind down to the competent rock. If that e-spillway is on top of that rind and not competent rock then the water will go right under.
    LA Times article with spillway cartoon:
    Here's the nightmare scenario at Oroville Dam that officials are fighting to prevent - LA Times

    Also that area they are dropping rocks. Whoa. Totally not what I assumed and is pretty troubling. I would think it would be more productive to sandbag/pour soil/rock along the edge of the parking lot and the lake. Any water is just going to pour around those sacks of rocks and keep eating away that soil. But what do I know I'm just a silly geologist and not an engineer.

  23. #323
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    Quote Originally Posted by nachomc View Post
    About four weeks of rain. 160,000 people evacuated, I80 was closed for a day or two, 50 now closed "indefinitely". If only we had money for infrastructure around here.
    Caltrans did a fairly massive mudslide remediation program this past summer (and not yet finished, probably thanks to the early and hard rains) on 80, really close to where it slid at Baxter. The project is on the eastbound side, so that probably saved considerable headache, considering the similar characteristics of that particular corridor.

    And 50 is more or less a highway in the bottom of a slot canyon. It looks like there's maybe 100 vertical feet of loose Tahoe moondust hillside immediately adjacent to the roadway. Not sure there's much "infrastructure" that could be done here, short of a massive earthmoving effort. https://twitter.com/CHPSouthLake/sta...07870473838592

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    Quote Originally Posted by BStrummin View Post
    Lots of new info since I checked in yesterday:

    This LA times article has a cartoon, sourced from DWR, that shows the emergency spillway directly on the ground with no pinning. That's not good, but for an "emergency" spillway probably about all they could justify. The other part to consider is that while the area overall is technically underlain by bedrock, unless it's freshly weathered like in the channel of a canyon or like pluton domes (yosemite et al) there is usually a considerable weathering rind that exists. Depending on all sorts of conditions (soil type, moisture, bedrock type) you can have a pretty good thickness (10 feet? 20 maybe?) of slowly degrading bedrock. Hard to explain but like the soil sort of progressively grades into competent (re: hard) bedrock. So what you saw from the runoff was the removal of that weathered bedrock rind down to the competent rock. If that e-spillway is on top of that rind and not competent rock then the water will go right under.
    LA Times article with spillway cartoon:
    Here's the nightmare scenario at Oroville Dam that officials are fighting to prevent - LA Times

    Also that area they are dropping rocks. Whoa. Totally not what I assumed and is pretty troubling. I would think it would be more productive to sandbag/pour soil/rock along the edge of the parking lot and the lake. Any water is just going to pour around those sacks of rocks and keep eating away that soil. But what do I know I'm just a silly geologist and not an engineer.
    The Billion-Dollar question is how deep is the concrete footing under the emergency spillway weir. Of course that info is currently hidden from the public thank you 9/11. I downloaded a 1950 topo of the site and looks like they may have even had to add fill in the spillway area (this could be good or bad). When I get back from doing some trail maintenance I'll upload a screen shot.
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  25. #325
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    I'm just not sure what to think about the bag drops. Seems like a bandaid at best. And this is over by the parking lot.

    OT: The Oroville Reservoir situation-bag-drop.jpg

    As for the geology it sure looks like headcutting was also involving bedrock and not just soil. Perhaps the concrete wier is on top of bedrock but also quite possibly weathered and fractured. Mafics like gabbro turn orange when weathered. Some of the minerals holding these ultramafics together like plagioclase, olivine, and pyroxene are prone to chemical weathering (ah, water migration). Just from looking at the pics it appears it's not just soil that was eroding away but probably highly weathered bedrock. Not good.

    OT: The Oroville Reservoir situation-headcut-erosion.jpg

    The big question now is whether they can keep up 100,000 cfs on the main spillway? No doubt the concrete is being headcut up the spillway toward the dam. It was only two days ago that 55k was all they wanted to release. All eyes on the sky now. No way in hell they will try the emergency spillway again.
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  26. #326
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    ^^^ Agreed

    Lake is at 888 last I checked this am. They are still aiming for 850. At 3 feet a day? Yikes.

  27. #327
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    Was the parking lot supposed to be part of the emergency spillway??? Cause that is what happened. Hundreds of feet of unprotected lip backside.

    OT: The Oroville Reservoir situation-58a2f73cc36188c93c8b461f.jpg
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  28. #328
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    Unfortunately they are never going to make 850 feet by the time it starts raining again. I don't see how they are not going to use the emergency at there current rate of discharge vs inflow. Hopefully they will let people back into Orville to get there belongings out. I'm hoping for the best, but the engineer in me see's this failing and not in a small way. As soon as any uncontrolled water starts flowing it's pretty much game over.

  29. #329
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    moar photos of the scarred area. The water also spilled over the parking lot in a huge way and messed that area up.

    OT: The Oroville Reservoir situation-c4kckrgwiamijpy.jpg

    OT: The Oroville Reservoir situation-c4o9we-ucaemeds.jpg
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  30. #330
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    Here is a 360 degree view of ground zero.

    https://www.google.com/maps/@39.5459...!7i7680!8i3840
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    Somewhere along in this thread there was a description of the Emergency Spillway as being 900 something yards plus another 800 something yards which I took to be inclusive of that entire parking area frontage.

    And for the rock bags stacked on that area of percolation...any kid that played with a garden hose in the dirt/mud damming up Hot Wheels scaled mini-reservoirs, knows how well that's going to work out.

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  32. #332
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    Quote Originally Posted by Moe Ped View Post
    From here https://www.nps.gov/lake/learn/natur...-lake-mead.htm this:

    "After the completion of Hoover Dam in 1935, sediment began accumulating in the new reservoir as the flow of the Colorado River was captured by the rising waters of Lake Mead. Initial estimates were that the new reservoir would last a little over 200 years as it filled with fine silt and sand from the high sediment load carried by the Colorado River. However, revised estimates in 1948 based on new data increased the life expectancy of the reservoir to more than four centuries.

    With the completion of Glen Canyon Dam in 1963 upstream of Hoover Dam, sediment volume entering Lake Mead from the Colorado River was reduced to only about a tenth of its previous volume. Much of the sediment is now trapped within Lake Powell behind Glen Canyon Dam. With the reduced sediment input into Lake Mead, the lifetime of the reservoir has been extended to potentially more than a thousand years."
    Thanks! Although I guess I wasn't considering the idea of upstream dams blocking sediment. Those dams then take the brunt of the accumulation therefore we really haven't won any battles.

  33. #333
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    Love this thread.

    I just read this:

    Engineers race to lower water level of Oroville reservoir before new storms move in - LA Times

    In the five days from Feb. 6 to Friday, Oroville received more than 6 inches of rain, Rowe said. The surrounding mountains and foothills received up to 24 inches of rain and snow in the same time period, he said.

    The storm’s runoff sent water into the Oroville reservoir at an average rate of 115,260 cubic feet per second, data show. The lake’s water level climbed 50 feet in five days.


    So as long as the upcoming storms have significantly less precipitation and as long as the the main spillway holds up, we may have just averted a major catastrophe.

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    Quote Originally Posted by BStrummin View Post
    Lake is at 888 last I checked this am. They are still aiming for 850. At 3 feet a day? Yikes.
    At least it will take less volume of outflow to drop the vertical feet of water the lower the lake gets.

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    Quote Originally Posted by ron m. View Post
    So as long as the upcoming storms have significantly less precipitation and as long as the the main spillway holds up, we may have just averted a major catastrophe.
    Unfortunately I don't think they've averted anything yet, more like scrambling just to stay in the game. 10 day forecast calling for up to 4 feet additional snow in Sierra on top of what is looking like a record breaking year. And March is often just as wet as Jan & Feb. If their lucky these will be colder storms with lower snow levels that will buy them more time but eventually all that water in the snow pack is gonna have to melt. Scary to think about what will happen if that melt comes quickly due to a couple really warm late season storms.

    OT: The Oroville Reservoir situation-gfs_6hr_snow_acc_norcal_38.png

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    Why did it take so long for me to discover this webcam!?!
    https://www.parks.ca.gov/?page_id=29411

    Dropbox with numerous slides and info compiled by Anne Jefferson (Kent State hydrologist)
    https://www.dropbox.com/s/ccex3qtlj1...ville.pdf?dl=0

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    Harvey's ran out of tonic water in 97...

    Quote Originally Posted by Finch Platte View Post
    I got trapped in South L Tahoe by the January '97 flood. On the third or fourth day I ordered a gin and tonic at Harvey's and the cocktail waitress appologized and said the tonic water was all gone and no more G and Ts until the supply trucks could get in.
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  38. #338
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    What happened to all the people complaining that they let too much water out of the dams during the winter?

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    Evac order is being lifted - now it's an evacuation "warning"

  40. #340
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    Quote Originally Posted by BStrummin View Post
    Evac order is being lifted - now it's an evacuation "warning"
    Traffic jam! Those people need to get back to their homes. Not all at once though.
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  41. #341
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    Quote Originally Posted by Mr.P View Post
    What happened to all the people complaining that they let too much water out of the dams during the winter?
    Don't worry, we are just reloading.

    The only complaint was about Folsom releases that would dump water to below 50%. This is a wet season of a 100 years so all these water dumping can be justified after the fact.

    But the Oroville problem only exists because the spillway failed at 1/4 of its claimed ability. Otherwise, there would be no problem. So someone's gonna unleash on the jokers responsible. There's gonna be a trail of tears from construction, inspection, decision making. Seem like nice people but not competent enough.

    Shasta is doing it right and there's no problem. Water conserved safely.

    New Melones almost has more %water now than Folsom.

    fcOT: The Oroville Reservoir situation-screen-shot-2017-02-14-1.49.31-pm.jpg
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    Quote Originally Posted by fc View Post
    Traffic jam! Those people need to get back to their homes. Not all at once though.
    Good luck widdat!

    At least they got some swag to take back with them.
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    Quote Originally Posted by Mr.P View Post
    What happened to all the people complaining that they let too much water out of the dams during the winter?
    There wouldn't have been a problem at Oroville at all, except that the primary spillway developed the gaping hole and then they had to reduce the flows out of it. If the primary spillway were undamaged, then most likely none of this drama would have happened. And I base my opinion on the fact that I stayed at a Holiday Inn, so its as good as gold.

    Once the new spillway at Folsom is finished I hope they will revise their practices to take into account better forecasting and such, and hopefully keep more water in the lake because they will have the ability to let more water out if need be. Folsom lake has been Folsom pond the last few years.
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    I heard that Folsom would've exceeded capacity this year if they hadn't released down to 60%. Anyone have the data that backs that up?

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    Quote Originally Posted by Oh My Sack! View Post
    Somewhere along in this thread there was a description of the Emergency Spillway as being 900 something yards plus another 800 something yards which I took to be inclusive of that entire parking area frontage.

    And for the rock bags stacked on that area of percolation...any kid that played with a garden hose in the dirt/mud damming up Hot Wheels scaled mini-reservoirs, knows how well that's going to work out.

    Water?....meet Path of Least Resistance.
    935 feet main emergency spillway weir, 800 feet parking lot spillway weir. My guess is that the weirs slope up towards the parking lot side.
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    They've dropped Folsom well below 60%, to nearly 40%, twice and it looks totally justified by what followed.

    https://cdec.water.ca.gov/cdecapp/re...tion?resid=FOL

    PS. What is the deal with how vBulletin keeps track of what you've read in a thread? This one keeps going back to post #167 whenever I try and use the "go to first new post" icon next to the thread title on the main forum page.

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    Quote Originally Posted by fc View Post
    Here is a 360 degree view of ground zero.

    https://www.google.com/maps/@39.5459...!7i7680!8i3840
    That view along with the 1950 topo data leads me to the conclusion that at least the upstream side of the emergency spillway is fill dirt. And probably some of the parking lot.

    Low point in the saddle to the north of the main spillway was between 850' and 875' in elevation. Top of emergency spillway is 901'. Do the math.


    (1950)


    (1970)

    Those map views are about 2 miles square. Use the section numbers (35, 36, 2, 1) to orient between views.

    Sorry, scale is off between the 2 maps because they're screen-grabs.
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    Quote Originally Posted by somanygoodbikes View Post
    They've dropped Folsom well below 60%, to nearly 40%, twice and it looks totally justified by what followed.

    https://cdec.water.ca.gov/cdecapp/re...tion?resid=FOL

    PS. What is the deal with how vBulletin keeps track of what you've read in a thread? This one keeps going back to post #167 whenever I try and use the "go to first new post" icon next to the thread title on the main forum page.

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    Quote Originally Posted by Moe Ped View Post
    Dredgers used as much mercury as did the stamp mills, it was the best/only way back then to recover the "fines". If you google it you'll find that in some areas the mercury levels are well above what is considered toxic.
    We're getting a little off topic but oh well.

    You're right. I didn't know that mercury was used in a facets of gold mining in the 1800's including hydraulic mining. I thought it was only in the stamp mills. Here's a govt article I found on it that's pretty informative.

    https://pubs.usgs.gov/fs/2005/3014/
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    Quote Originally Posted by Buzzaro View Post
    We're getting a little off topic but oh well.

    You're right. I didn't know that mercury was used in a facets of gold mining in the 1800's including hydraulic mining. I thought it was only in the stamp mills. Here's a govt article I found on it that's pretty informative.

    https://pubs.usgs.gov/fs/2005/3014/
    I've got a little bit of an inside track on the info because my grandfather worked on building dredges in the Marysville area and my wife's great-grand-uncle delivered mercury in that area via wagon.

    I think hard-rock mining wastes tend to be a little more toxic because of the likelihood of other heavy metals besides the mercury.
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    Quote Originally Posted by Moe Ped View Post
    I've got a little bit of an inside track on the info because my grandfather worked on building dredges in the Marysville area and my wife's great-grand-uncle delivered mercury in that area via wagon.

    I think hard-rock mining wastes tend to be a little more toxic because of the likelihood of other heavy metals besides the mercury.
    What are the Mercury levels that they are detecting in the Feather River discharge downstream of the Oriville Dam?

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    Quote Originally Posted by Switchblade2 View Post
    What are the Mercury levels that they are detecting in the Feather River discharge downstream of the Oriville Dam?
    Not sure if you mean currently (after the spillway failure) or in general but the Feather River is pretty contaminated.

    2 good reports:

    http://oehha.ca.gov/media/downloads/...ts092414_0.pdf

    http://oehha.ca.gov/media/downloads/...lito092414.pdf

    It's interesting how the different fish species uptake mercury based on location.

    Lots of PCB's and DDT in the Thermalito waters too.

    Bought me a fishing license this year, glad I'm over 45 and not pregnant.
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  54. #354
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    Quote Originally Posted by fc View Post
    Was the parking lot supposed to be part of the emergency spillway??? Cause that is what happened. Hundreds of feet of unprotected lip backside.

    Click image for larger version. 

Name:	58a2f73cc36188c93c8b461f.jpg 
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    Yes, the parking lot is part of the spillway by design. It's sounding more and more like the emergency spillway sole purpose was to save the dam during an extremely rare event like a 1000 year flood. It was never intended to be a secondary source of water release. The dam engineers in the 1950s and 60s weren't clueless. However, they are all dead or retired so who do you ask when the shyte stars to hit the fan. You'd think the dam managers knew the ins and outs of their facility but maybe not. They made a decision to use it in the hopes of minimizing further damage to the main spillway not fully realizing the consequences.

    Now that the situation is largely under control it's going to be interesting in the coming months the lessons learned. The reservoir is dropping 10' every 24 hours. The probably won't make the 50' goal as the next series of storms roll in but should be plenty of margin. Ideally, they won't have to use the emergency spillway ever again. It will be interesting to see how far the erosion of the main spillway has migrated uphill (and towards the powerlines) once they do get a chance to shut off the spillway.
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    Here's a diagram of the emergency spillway:OT: The Oroville Reservoir situation-oro-emergency.jpg

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    hmm, yes and likely grouted into less than suitable bedrock. I just don't get it. One estimate was that it would withstand 700,000 cfs with 15' of flow going over it (source: Army Corps of Engineers). I can't remember where I saw that but the other discharge cited is 350,000 cfs. Even at the lower amount 12,000 cfs that's 3% of the flow it was supposedly able to withstand. Very interesting and still sounds like all it was intended to do was blow out and save the dam.

    Also of note, is all the debris from the main spillway has back filled the powerplant so they can't release water through the outlet works. Big effort also underway there.
    Spillway repairs not only project underway at Oroville Dam
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  57. #357
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    The diversion pool issue sounds like the job for some old fashioned clearing via dynamite.

  58. #358
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    Level is now at 877 feet. Dumping water is still full gas at 100,000 cfs.

    Started to rain up there now.

    https://cdec.water.ca.gov/cgi-progs/queryF?ORO
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    Really interesting, if back-of-the-envelope, post here on lake levels and the incoming storm: https://www.metabunk.org/oroville-da...16#post-200513

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    Quote Originally Posted by BStrummin View Post
    Here's a diagram of the emergency spillway:
    Cool... good old pencil-and-sliderule engineering. Don't suppose you can magically come up with the mentioned "A-3K1-8 grouting details" as well?
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    Quote Originally Posted by BStrummin View Post
    Here's a diagram of the emergency spillway:Click image for larger version. 

Name:	oro emergency.jpg 
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    Where'd you find that? I'd love to see the rest of the details. "Enriched" concrete; not "reinforced"???
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    Quote Originally Posted by Moe Ped View Post
    Where'd you find that? I'd love to see the rest of the details. "Enriched" concrete; not "reinforced"???
    It's from this 1974 California State Water Project document. That drawing is on page 97. I haven't looked through it but it looks really cool. Found on twitter. https://archive.org/stream/zh9califo...ge/n0/mode/2up

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    From the last entry in the link from Knobs (unformatted):

    "Below is a table showing the amount of time for the dam storage to reach threshold capacity for a given amount of rainfall per day.

    RainfallStorage Added/DayRemaining StorageTime to Reach Threshold:

    1 inch per day
    -5,243.5307,145
    No storage gain

    2 inch per day+131,547307,1452.334 days ~ 56 hours

    3 inch per day+268,337.5307,1451.144 days ~ 27 hours"

    As I read it, this is a precarious situation.

    It is not beyond the scope of imagination to have 2 consecutive days in excess of 3 inches of precip over the upper Feather River watershed.

    Much depends upon the integrity of the emergency spillway and the weather.

    I am optimistic though. But if I lived below a levee downstream, I would be relocating some things just in case.




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    Quote Originally Posted by BStrummin View Post
    Here's a diagram of the emergency spillway:Click image for larger version. 

Name:	oro emergency.jpg 
Views:	226 
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ID:	1121714
    I did a quick read of the text associated with the above drawing and it appears the "foundation" is competent rock they excavated down to. The worrisome flaw IMHO is that the grout curtain sealing/solidifying the foundation rock is only located on the upstream side of the emergency spillway structure. So if it gets cut back from the downstream side (which is what was happening) the force of the water in the reservoir could cause the structure to topple forward which would be huge release of water.
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  66. #366
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    Quote Originally Posted by Moe Ped View Post
    I did a quick read of the text associated with the above drawing and it appears the "foundation" is competent rock they excavated down to. The worrisome flaw IMHO is that the grout curtain sealing/solidifying the foundation rock is only located on the upstream side of the emergency spillway structure. So if it gets cut back from the downstream side (which is what was happening) the force of the water in the reservoir could cause the structure to topple forward which would be huge release of water.
    My thoughts are in harmony with yours Moe Ped.

    What I propose in the armchair engineer manner of speaking is draping a huge thick and tough impermeable membrane across the emergency dam lip, including the auxiliary parking lot/launch ramp which would be anchored by deep screws and lapped to ballast in the bottom of lake of possible, over the spill way draining areas and down across the surface of the ground to a point past where the gradient steepens. That way the under cut effect could be eliminated. It could only be temporary because it would eventually shred to bits unless a hefty supply of Mithril can be conjured up by some sorcery.



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    A few gems have popped up via Google in the last couple of days:

    From: Current Hydraulic Research United States 1966

    OT: The Oroville Reservoir situation-not-tested.jpg

    And then from 2014: Mid and Upper Sacramento River
    Regional Flood Management Plan WORKING DRAFT


    "The spillway of the Oroville emergency spillway is an unprotected hillside, which would suffer
    severe erosion in the event that the emergency spillway is used. The hillside damage, as well as
    the downstream transport of eroded soil and rock, would both be operational concerns, leading to
    consideration of options for limiting such structural damage under large flood scenarios. Erosion
    of the hillside would also release large amounts of soil and rock into the channel downstream,
    with potential impacts on downstream channel capacity and environmental quality. Therefore,
    erosion protection for this hillside may be considered a long-term investment in the integrity and
    environmental quality of the channel system downstream of the dam. By eliminating this
    operational concern, there is a greater likelihood that DWR would elect to surcharge the reservoir
    rather than exceed the 150,000 cfs objective release during major flood events, such as occurred
    during the 1997 New Year’s Flood.

    There may also be opportunities to upgrade facilities, including gates, spillways, dam raises, and
    power plants to improve reliability, efficiency, capacity and performance."


    If you go to the document the preceding paragraph highlights that much of Oroville's troubles stem from the Marysville Dam never being built on the Yuba River. (I almost bought lake front property on Marysville Lake) Not having that dam on the Yuba means that the Oroville dam must work harder controlling floodwaters. Limits Oroville's margin of safety inasmuch as they can't always release as much water as they should to keep Oroville drawn down to a better level.

    I wonder why the Sierra Club didn't sue to have the Marysville Dam built? (Since they were so concerned about Oroville not being built correctly)
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    https://en.m.wikipedia.org/wiki/U.S....eers_Bay_Model

    There's a great place to stop by on a bike ride in the GGNRA Headlands and on up to Mt Tam is Sausalito that is a huge model of the San Francisco Bay hydrology.

    I wonder what they are saying there about the situation up stream and the Feather River?

    If someone lived up there lurking in this forum could and visit and ask around, they might be able to dredge up some information.





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    Ahhh, the Bay Model. Haven't been there for years, but it's a great learning experience!
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    Here's a simple explanation of events so far
    Attached Thumbnails Attached Thumbnails OT: The Oroville Reservoir situation-oroville_dam_infographic_feb_14.jpg  


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    I didn't know there was a bay model! I knew there was a Mississippi river one but not a SF Bay one. Cool.

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    Quote Originally Posted by bluegixxer600 View Post
    Here's a simple explanation of events so far
    Nice find.
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    Level is dropping right now despite the rains. What's really saved the day in this whole saga is:

    They were able to run the broken spillway at 100,000 CFS!

    This was a big wildcard as it broke at 60,000 cfs. But they sacrificed the whole bottom spillway and opened the floodgates! Luckily, it hit bedrock quickly and the erosion stabilized. Also, the top of the spillway was not damaged too much while doing this. Without this success, things would have gone to HELL for sure.

    I'm sure they'd love to turn it off for a few hours and inspect exactly what's happened. Soon, I'm sure.
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    Quote Originally Posted by BStrummin View Post
    I didn't know there was a bay model! I knew there was a Mississippi river one but not a SF Bay one. Cool.
    It's in a huge building down by the wharf in Sausalito. I went on field trips with my boys when they were in grammar school.
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    On a relative basis, it is lucky that the bulk of the Friday storm is heading south. Sounds like they are going to get hammered.

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    Quote Originally Posted by cohenfive View Post
    On a relative basis, it is lucky that the bulk of the Friday storm is heading south. Sounds like they are going to get hammered.
    They are still in 'slight drought'. This may end all of that talk.

    The problem with their landscape and our is it's just not geared to handle this much water at once. Soil quality and lack of drainage means mudslide, sinkhole and flooding.
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    Quote Originally Posted by jibmaster View Post
    Sorry Jib, this is classic fear mongering. 13'? What a bunch of horse sh*t. Pathetic really.
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  84. #384
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    Quote Originally Posted by fc View Post
    They are still in 'slight drought'. This may end all of that talk.

    The problem with their landscape and our is it's just not geared to handle this much water at once. Soil quality and lack of drainage means mudslide, sinkhole and flooding.
    Sinkhole? What are you referring to? How are the soils different from nocal? The climate is different for sure but not necessarily the soils or rock type. And not many places in the world that can handle 4 to 8" of rain without some sort of impact.

    And the drought is far from over just because some reservoirs are full. Ground water tables are still low and still being pumped dry by agriculture which is 80% of the water use in CA. It will take some time, decades even, for the aquifers to recover.
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    Quote Originally Posted by rockman View Post
    Sinkhole? What are you referring to? How are the soils different from nocal? The climate is different for sure but not necessarily the soils or rock type. And not many places in the world that can handle 4 to 8" of rain without some sort of impact.

    And the drought is far from over just because some reservoirs are full. Ground water tables are still low and still being pumped dry by agriculture which is 80% of the water use in CA. It will take some time, decades even, for the aquifers to recover.
    I'm referring to California as opposed to other states and other areas. Oregon, Washington, British Columbia get a ton of rain their land seems to handle it much better.
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    Based on the "street value" of water of $750 per acre foot (what I paid last year for 1 a/f for my little farm) the State has almost 2 billion dollars worth of water in Oroville it can push annually to those of us with a water addiction. This may have something to do with how they manage those flood control releases. Hard to let go of something that valuable.
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    Quote Originally Posted by fc View Post
    Level is dropping right now despite the rains. What's really saved the day in this whole saga is:

    They were able to run the broken spillway at 100,000 CFS!

    This was a big wildcard as it broke at 60,000 cfs. But they sacrificed the whole bottom spillway and opened the floodgates! Luckily, it hit bedrock quickly and the erosion stabilized. Also, the top of the spillway was not damaged too much while doing this. Without this success, things would have gone to HELL for sure.

    I'm sure they'd love to turn it off for a few hours and inspect exactly what's happened. Soon, I'm sure.
    It's not over yet. It won't be over until the wet season has passed.

    Quote Originally Posted by Jack Burns View Post
    https://en.m.wikipedia.org/wiki/U.S....eers_Bay_Model

    There's a great place to stop by on a bike ride in the GGNRA Headlands and on up to Mt Tam is Sausalito that is a huge model of the San Francisco Bay hydrology.

    I wonder what they are saying there about the situation up stream and the Feather River?

    If someone lived up there lurking in this forum could and visit and ask around, they might be able to dredge up some information.
    I haven't been there since early this century. I was in the USCG stationed at the Marine Safety Office in SF. Really cool place.

    Quote Originally Posted by cohenfive View Post
    On a relative basis, it is lucky that the bulk of the Friday storm is heading south. Sounds like they are going to get hammered.
    Yeah...I'm not looking forward to it.

    Quote Originally Posted by fc View Post
    They are still in 'slight drought'. This may end all of that talk.
    Oh, no, locals are already *****ing about wanting rates to be dropped since we are "out of the drought" now. I'm getting tired of hearing about it. Everyone wants to flood their lawn and pretend nothing ever happened.

    Quote Originally Posted by rockman View Post
    And the drought is far from over just because some reservoirs are full. Ground water tables are still low and still being pumped dry by agriculture which is 80% of the water use in CA. It will take some time, decades even, for the aquifers to recover.
    I keep trying to tell people that, but they just see the rain and ignore all the rest of the data.

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    Quote Originally Posted by fc View Post
    The problem with their landscape and our is it's just not geared to handle this much water at once. Soil quality and lack of drainage means mudslide, sinkhole and flooding.
    Or in other words, three-sigma weather may look different in different places, but it's going to cause issues no matter where it happens.
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    We will survive. Even if that mofo of a dam lets go at some point it will be horrific and lives will be lost for sure, but California will continue on. Managers will continue to play with their dams, collecting releasing collecting releasing. The real water related tragedy in California is aquifer compaction. That we will never get back until Ma nature swipes the slate clean....

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    Armchair engineering

    After looking at those project drawings in the book posted by BStrummin it's pretty obvious that the main spillway wasn't built to specification (nor likely the emergency spillway); it was supposed to be built after the hillside was excavated down to competent rock. Looking at this photo it's easy to see that it failed in the area where it was built on very soft rock/dirt. (the reddish stuff)



    Also plainly visible in the original photo (not in the miserly size MTBR lets us post) is rebar and also the rods used to pin the structure to the "rock". Where you see the blue rock the spillway mostly stayed stuck; no blue rock no spillway. Some news accounts are blaming the recent heavy rains for undercutting the spillway; had it been built/maintained/repaired properly the rains would have no effect. There's a complex network of drains built into the spillway; they can be seen operating in other photos.
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    I think areas that for thousands of years have gotten lots of rain, adjust to the rainy weather, by growing vegetation that flourishes in wet conditions. The death of that vegetation adds lots of organic matter to the soil and allows for better absorption of water . Am I wrong rockman?

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    Quote Originally Posted by Switchblade2 View Post
    I think areas that for thousands of years have gotten lots of rain, adjust to the rainy weather, by growing vegetation that flourishes in wet conditions. The death of that vegetation adds lots of organic matter to the soil and allows for better absorption of water . Am I wrong rockman?
    Saturated soils are saturated soils no matter the location. Vegetation of course helps. But certainly not where there are recent burn scars. Socal is indeed about to take it but not sure that they are any more prone to mudslides and certainly have far less sinkholes than other parts of the country with Karst topography. But I'm no soil scientist, just a geomorphologist. Too much conjecture in this thread and not many posting factual information.
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    Quote Originally Posted by rockman View Post
    Saturated soils are saturated soils no matter the location. Vegetation of course helps. But certainly not where there are recent burn scars. Socal is indeed about to take it but not sure that they are any more prone to mudslides and certainly have far less sinkholes than other parts of the country with Karst topography. But I'm no soil scientist, just a geomorphologist. Too much conjecture in this thread and not many posting factual information.
    I think he meant that those areas with high amounts of annual rain (temperate rainforests) have more stable soils due to organic matter and biotic activity (aggregates forming glue) than do the relatively "dead dirt" of SoCal which has less holding capacity. However, once saturated water holding capacity is a moot point. It then comes down to soil structure and topography. So under normal conditions 10" of sudden rain will likely do less damage to soils in Western Washington than they will do in San Diego. You know this but for those that don't know the difference between dirt and soil.

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    Quote Originally Posted by JCWages View Post
    I think he meant that those areas with high amounts of annual rain (temperate rainforests) have more stable soils due to organic matter and biotic activity (aggregates forming glue) than do the relatively "dead dirt" of SoCal which has less holding capacity. However, once saturated water holding capacity is a moot point. It then comes down to soil structure and topography. So under normal conditions 10" of sudden rain will likely do less damage to soils in Western Washington than they will do in San Diego. You know this but for those that don't know the difference between dirt and soil.
    It's true that desert landscapes shed water faster than those that are vegetated in a maritime climate. That doesn't however, mean they are more prone to landslides or sinkhole formation. You could also make the case that landslides are more frequent in Western WA. I don't really know this or that increased vegetation matters at all but this one three years ago killed 44 people. https://www2.usgs.gov/blogs/features...hington-state/

    I'd argue that that any landscape disturbance that increases runoff like fire or logging is a bigger variable than climate or surface cover (ie., vegetation). Keep in mind southern CA is also vegetated it's just not lush. So is the Sonoran desert. But whatever, my point was that this, among other similar statements, was just another post in a thread that come across as factual when in fact the poster has no idea what he/she is talking about. But hey, it's a discussion forum. Post what you want right? Guess I'm just a stickler for accuracy. Carry on.
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    I think one of the big differences between the Los Angeles area and the Bay Area is that LA is built right up into the foothills of the San Gabriel Mountains that reach up to 10,000 feet. I think it's that interaction of a dense urban area butted up against a steep mountain range that raises the impact of natural hazard risks. Flat land environmental geologist here, I just drill holes and collect samples.

  96. #396
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    Quote Originally Posted by Moe Ped View Post
    After looking at those project drawings in the book posted by BStrummin it's pretty obvious that the main spillway wasn't built to specification (nor likely the emergency spillway); it was supposed to be built after the hillside was excavated down to competent rock. Looking at this photo it's easy to see that it failed in the area where it was built on very soft rock/dirt. (the reddish stuff)



    Also plainly visible in the original photo (not in the miserly size MTBR lets us post) is rebar and also the rods used to pin the structure to the "rock". Where you see the blue rock the spillway mostly stayed stuck; no blue rock no spillway. Some news accounts are blaming the recent heavy rains for undercutting the spillway; had it been built/maintained/repaired properly the rains would have no effect. There's a complex network of drains built into the spillway; they can be seen operating in other photos.
    I'm sure it was excavated down to bedrock per plan. The thing is bedrock isn't going to meet the design grade or anything close. So then fill will be put back of a certain material type that meets a design specification and then placed to a certain compaction. It probably was just fine when it was built. What we don't know (and maybe they do or don't) is what's been happening with that fill since the damn was built. Expansion/contraction, whatever critters get in there to make it more porous, it's next to a lake with high underground hydraulic pressure so it's likely it's got a higher moisture content than originally, who knows what else.
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    Survey says.... "tiny bubbles"

    Oroville Dam: What made the spillway collapse?
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    Ok, the battle lines are drawn at 860 feet. Mayday is 901 feet. The water should start rising again.

    https://cdec.water.ca.gov/cgi-progs/queryF?ORO

    OT: The Oroville Reservoir situation-screen-shot-2017-02-17-10.55.37-am.jpg
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    There is language in that big document that discusses what criteria they were using for "bedrock" - I'll see if I can find it. But was is really damning is that photo from 2009 or something with the trucks parked on the spillway and water seeping out. Clearly there was a big pocket of highly weathered material right there that was probably holding a lot of water, and through filling and draining of pore spaces over the years created voids which allowed the concrete to lose its structural stability. A small crack in a weak structure turns into a very large hole quickly when 60,000 cfs of water goes over it.

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    Here is what I was thinking of, but the context is the main dam and this language isn't in the spillway section:

    Excavation Criteria. The excavation criteria for the various parts of the foundation were:
    Concrete Core Block—Sound hard rock consisting of fresh to slightly weathered rock, with unstained to slightly iron-stained fractures.
    Embankment Core Trench—Sound hard rock that would be impervious after grouting. Trench slopes 1:1 or flatter downstream and Yi-.l upstream. Seams and shear zones excavated to a depth approximately equal to their width. Irregular rock to be removed to permit compaction of the core.
    Embankment Shells and Transitions—Weathered rock exhibiting definable rock structure of a strength equal to that of embankment materials placed thereon


    (also thank you kind archivist for OCRing a 546 page document before saving. You're doing the lord's work)

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