Page 3 of 21 FirstFirst 123456713 ... LastLast
Results 31 to 45 of 301

Thread: OT: Oroville Dam queries.

  1. #31
    Don't worry all that climate change date will soon be eliminated and forgotten...
    The purge has begun...

    Quote Originally Posted by BGolden View Post
    "Drought will likely persist through the winter in many regions currently experiencing drought, including much of California and the Southwest"

    http://www.noaa.gov/media-release/us...r-wetter-north

    The California legislature passed 898 new laws that went into affect in 2017.

  2. #32
    Closer to home, the Anderson Dam/Reservoir above Morgan Hill has too much water in it; a few days ago it was 91% full. It's not supposed to be more than 68% full because it could fail in the event of a major earthquake, and the dam itself is very close to the Calaveras Fault. $400M retrofit scheduled for 2020. They're releasing as much water as they can, but it'll be a few weeks before they get it down to an acceptable level. And more rain is on the way later this week.

  3. #33
    Real Bear tc3590's Avatar
    Join Date
    May 2009
    Location
    Marysville CA
    Posts
    1,690
    Quote Originally Posted by burritos View Post
    Are you getting the feeling that this is precautionary? Good luck.
    I have typed out a few different responses to tell you what I think and honestly, I have came to a conclusion that I don't know what to think.

    Part of me thinks in the case of the structure collapsing Oroville, Gridley and the smaller cities in between would be without a doubt a total loss while Marysville and Yuba city would be at extreme risk. So obviously right now it's precautionary but it could turn south fast.

    For Marysville and Yuba City, we would just have to pray that the levees do their job. This would be an incredible amount of water coming down the Feather River so who really knows what to expect.

    Good news is I have Flood Insurance so the house and stuff inside can be replaced besides a few of my sentimental items. Bad news is my family business would be wiped out and I really wouldn't know where to go from there. We install and monitor home security systems and are a small locally owned company. If the area gets wiped out not only does our office get destroyed but so does all of our clients homes and businesses. Not sure what we would do at that point.

  4. #34
    Golden Bear oskirules's Avatar
    Join Date
    Aug 2010
    Location
    outside the matrix
    Posts
    5,444
    Quote Originally Posted by Goobear View Post
    That's what happens when the state supports social causes but does not allocate enough money for infra structure. A more balanced approach would be appreciated...
    Going from severe drought to overflowing dams in less than a year caught everyone by surprise.

  5. #35
    Quote Originally Posted by sp4149 View Post
    My college roommate was from Oroville (he's the DA there now); needless to say I heard plenty about That Dam Project.
    First it is earthen fill covered with a concrete shell to prevent erosion of the earth. This is an ancient construction method
    used for millennia, a hard shell covering a soft core. The Failed spillway was constructed the same way. Once the concrete
    spillway shell failed rapid erosion of the soft core produced a massive hole. I've known about Oroville for a long time,
    there are several similar dams in California, the long delayed New Melones dam near Sonora for example; Trinity...

    There are a relatively few all concrete dams in the state, Hetch Hetchy may be the most famous, Shasta Dam is the largest;
    being all concrete they are much less massive, but do not have a vulnerable soft core. Their chief danger is water cutting
    a path around the concrete structure; one reason that like Hoover they typically are located in rock walled canyons as
    opposed to dirt slopes like Oroville and Trinity. Once the concrete skin/shell of an earthen fill dam is breached, erosion can
    produce sinkholes and ultimate failure is a possibility. The erosion can move laterally, which is why the spillway was not
    located next to the dam itself but separated by the 'hill'. I saw images of the water flowing over the dam itself. That is bad
    news for an earthen dam is not always hardened on the back side.

    We can talk about maintenance, but this is really a problem of poor water management.

    Dam managers do not fill up dams in the winter; they hold the level down to be able to contain the forecast spring runoff
    (roughly 15-20% of capacity). Somebody made a big miscalculation; allowing the dam to fill up in the middle of the
    winter. There is also the issue of shoreline covered by waters from the dam. When full Shasta Lake has 365 miles of shoreline
    compared to 160 miles for a full Oroville. When the waterlevel at Shasta is 60 feet from the top, the shoreline shrinks nearly
    70 miles. When the waterlevel drops 137 feet the shoreline has shrunk over 160 miles; the impact on lake businesses, recreation
    and neighbors is magnified by drops in water level. I suspect, for some reason, Oroville operators were maintaining the lake water
    level higher than might have been advised. The Corps may have dictated maximum downstream flow rates to prevent damaging
    downstream structures like levees, bridges, piers, etc... and that flow rate wasn't enough to drop the Oroville water level to safe levels.

    It's a lot like driving 130mph on tires rated for 110mph and experiencing a blowout; yes the tires failed, but why the need to drive 130mph?
    That's very interesting. Thanks.

  6. #36
    Quote Originally Posted by oskirules View Post
    Going from severe drought to overflowing dams in less than a year caught everyone by surprise.
    Exactly, anyone who may been vocally predicting this 1 year ago would have been considered a madman, especially when El Nino didn't pan out(at least not for socal).

  7. #37
    Quote Originally Posted by burritos View Post
    Exactly, anyone who may been vocally predicting this 1 year ago would have been considered a madman, especially when El Nino didn't pan out(at least not for socal).
    That's why there is a licensing process. Things get reviewed at specific intervals because people aren't just daily thinking about damn (or other) preventive maintenance. The licensing process in 2005 failed in this case. It is absolutely appropriate to review what happened in 2005 and consider what was done right and what was done wrong.

  8. #38
    Quote Originally Posted by oskirules View Post
    Going from severe drought to overflowing dams in less than a year caught everyone by surprise.
    Why? It's the history of the West.

  9. #39
    Golden Bear oskirules's Avatar
    Join Date
    Aug 2010
    Location
    outside the matrix
    Posts
    5,444
    Quote Originally Posted by GB54 View Post
    Why? It's the history of the West.
    West coast or western civilization?

  10. #40
    Golden Bear Cal89's Avatar
    Join Date
    Jul 2008
    Location
    South Bay Area
    Posts
    5,161
    Quote Originally Posted by RioDelMarBear View Post
    Closer to home, the Anderson Dam/Reservoir above Morgan Hill has too much water in it; a few days ago it was 91% full. It's not supposed to be more than 68% full because it could fail in the event of a major earthquake, and the dam itself is very close to the Calaveras Fault. $400M retrofit scheduled for 2020. They're releasing as much water as they can, but it'll be a few weeks before they get it down to an acceptable level. And more rain is on the way later this week.
    RDMB - Welcome to the forum.

    You are correct. Looking at Anderson, the largest reservoir in Santa Clara County, as I type... While our home is not in direct jeopardy, it's a bit scary alright. Apparently the precious water being released would be enough for 60,000 households for one year.
    The University of California - One of the finest universities in the world, is the oldest public university in our great state with origins dating back to 1855, and university status granted in 1868. Go Bears!

  11. #41
    Quote Originally Posted by GB54 View Post
    Why? It's the history of the West.
    +1

    Anyone who has lived in NorCal for more than 40+ years would know this is the pattern...5+ years of dry weather followed by a big wet year. Go back and look at the history.

  12. #42
    How could the guy in charge of the dam say he was not aware of the 2005 report that said the emergency overflow should be reinforced with concrete? Was he hired yesterday? Would it have been prudent to be aware if the history of the dam?

    Maybe a better reply would have been,"I knew about that but we were not given the money to do it". Likely truth

  13. #43
    Without looking at it, I suspect this is the account of the SJ Merc article linked previously. I heard the following on the radio this morning.

    12 years ago there was an attempt to sue (so as to force) for construction of the overflow emergency spillway to be given a concrete path rather than the current dirt path, which is now degrading RAPIDLY. Instead, the water agencies that would have had to pay for this backup concrete path, which would only be used if the actual spillway failed (which is what has happened), argued that it was not necessary.

    Well, now the main spillway has failed, and water was sent over the emergency spillway, but the water degraded the path so fast that the entire hill is in jeopardy.

    The main concrete dam will not fail. But the rapid erosion occurring at the spillway and emergency spillway does mean that the water could all be let out of the lake above. Erosion is just pulling the hill down. Hopefully we can make it past this winter without catastrophe.

    Had the nervous nellies 12 years ago been heeded, none of this would be happening. I'm sure the people who argued against it are feeling like a pile of crap, because not only have 200,000 evacuated their homes, but the price tag involved is going to be tremendous.

    To repair the main spillway was said to be $200M.
    But now they are going to have to also repair the emergency spillway area.

    Here are pictures of what happened.



    This is the main spillway. Water started shooting at irregular angles, so they shut it down to inspect. This photo was taken at that time.
    Concerned that this would damage things worse, they decided to let the water rise and I suppose test the Emergency Spillway path.




    Below is the dam on the Right. You can see the extent of the damaged spillway on the middle, it's carved a path to the right, eroding the dirt hill. And on the left is the emergency spillway, as of this photo it was unused and so mostly naturalized in appearance (red dirt area).




    And below is the water as it began to flow over the Concrete Lip of the Emergency Spillway



    And below is the result of what happened to the earth (erosion) after all that water flowed over the Emergency Spillway.




    So now I guess they are back to running water back down the main Spillway, and dealing with whatever damage they suffer there.

    The threat is that either the hill below the main Concrete Spillway or the non-concrete Emergency Spillway erodes to the extent that either lip or the entire top of the restraint gives way, causing a huge rush of water downhill. This would flood or destroy towns, and wipe out levees and flood a huge massive area.

    My guess is it will play out until the rainy season ends in another 1-2 months, and then we'll have a huge repair effort and bill this summer.
    Last edited by concordtom; 02-13-2017 at 02:26 PM.

  14. #44
    True Blue Golden Bear Phantomfan's Avatar
    Join Date
    Jul 2008
    Location
    California
    Posts
    15,074
    Quote Originally Posted by oskirules View Post
    Going from severe drought to overflowing dams in less than a year caught everyone by surprise.
    I cant imagine how.

    This is the cycle for California and why our water system is designed like this. It is more apparent now with somewhat more severe weather, but this isnt the first time in the last 25 years.

  15. #45
    Having recently become acquainted with flood insurance last year in Louisiana. There are a few caveats that will greatly affect actual coverage. In our case coverage was by appraised value, not market value; a second residential unit on the property (not sharing a common roof) was not in the appraisal, also outbuildings like separate garages, workshops, storage buildings were not covered. Expect durable items to be depreciated; aka a 15 year old refrigerator will be a total loss. In older buildings, they will have to be rebuilt/repaired to current code; which typically means new electrical and plumbing and fixtures, water heaters may require new enclosures or locations; low flow toilets, and plumbing fixtures, proper venting; the whole nine yards. You need to have a separate rider covering code upgrades or you repairs will not be covered. Even homes only ten years old will likely require some code upgrades. Once condemned due to flooding the dwelling cannot be certified for occupancy until the repairs bring the dwelling into full code compliance. Even undamaged spaces have to be brought into compliance.

    Bringing a dwelling into code compliance is a major reason that homes with flood insurance in Livingston Parish, LA still are not being rebuilt, even though thousands were flooded last August. Some commercial properties like Walmart which got only a couple of feet of water still have not reopened. Newer businesses like BassPro and Sam's Club were built on elevated sites and never closed. But some competitors not on elevated sites may never rebuild. It's a real crap shoot if you need help from flood insurance; it may dictate a walk away away decision.

    Quote Originally Posted by tc3590 View Post
    I have typed out a few different responses to tell you what I think and honestly, I have came to a conclusion that I don't know what to think.

    ...

    Good news is I have Flood Insurance so the house and stuff inside can be replaced besides a few of my sentimental items. Bad news is my family business would be wiped out and I really wouldn't know where to go from there. We install and monitor home security systems and are a small locally owned company. If the area gets wiped out not only does our office get destroyed but so does all of our clients homes and businesses. Not sure what we would do at that point.




Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •