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PostPosted: Wed Feb 08, 2017 5:03 pm 
Lake Oroville, one of the three largest reservoirs in the State of California has developed a massive 40-hole in its spillway as the result of recent heavy rainfall.

http://www.mercurynews.com/2017/02/07/h ... avy-rains/.

The set of storms had been originally predicted to only light, but tropical moisture turned into an "Atmospheric River" drenching Northern California.

Winds in excess of 60-Miles Per Hour blowing across the Golden Gate Bridge forced Bridge Authorities to close the pedestrian walkway across the Bridge.

South Bound U.S. 101 is backing up starting at Mill Valley due local flooding in Marin City (Where I live), about only thing not be diverted away from the South Bound Marin City/Sausalito Exit are the Golden Gate Transit Buses carrying passengers to and from San Francisco.

Schools in Sausalito/Marin City were closed yesterday and today its basically hour by hour.

Another storm is expected to blow through starting Thursday and Friday promising more wind and rain. Drying Saturday through Valentine's Day.

The rainy season in California runs until at least late April or early May.

The drought is all but over. The ground is saturated and runoff is creating local heavy flooding along the Russian River.

Mother Nature is a cast iron bitch.


Last edited by justme01 on Fri Feb 10, 2017 7:38 pm, edited 1 time in total.

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PostPosted: Wed Feb 08, 2017 5:58 pm 
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Your characterization of this story is deceptive and incomplete. As the article cited states, a hole has opened up in the dam's spillway -- but not the dam, itself.

This is a serious matter, to be sure, as the dam is a major source of drinking water for California. But as the article also notes, "In a statement, the state agency said there was 'no anticipated threat to the dam or the public.'”


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PostPosted: Wed Feb 08, 2017 6:09 pm 
Your characterization of this story is deceptive and incomplete. As the article cited states, a hole has opened up in the dam's spillway -- but not the dam, itself.

This is a serious matter, to be sure, as the dam is a major source of drinking water for California. But as the article also notes, "In a statement, the state agency said there was 'no anticipated threat to the dam or the public.'”


Blah....Blah....Blah. I stated facts. I am surprised your not blaming President Obama.


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PostPosted: Thu Feb 09, 2017 7:55 pm 
The damaged spillway of California's third largest reservoir is currently spilling approximately 35,000 cubic feet of water per minute.

http://www.sfgate.com/news/article/Orov ... 920358.php.

With ongoing storms, the repairs necessary to fix the damaged spillway will have to wait.

Parts of the San Francisco Bay Area have experienced up to one half inch of rain an hour. Several homes have been damaged/destroyed due mudslides.


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PostPosted: Fri Feb 10, 2017 12:01 pm 
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Your characterization of this story is deceptive and incomplete. As the article cited states, a hole has opened up in the dam's spillway -- but not the dam, itself.

This is a serious matter, to be sure, as the dam is a major source of drinking water for California. But as the article also notes, "In a statement, the state agency said there was 'no anticipated threat to the dam or the public.'”


Reading comprehension - read the first sentence again.
Lake Oroville, one of the three largest reservoirs in the State of California has developed a massive 40-hole in its spillway as the result of recent heavy rainfall.


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PostPosted: Fri Feb 10, 2017 12:11 pm 
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"Lake Oroville Dam Has A Huge Hole Opened."

Do you see the word "spillway" anywhere in that title? This will require that you do something -- what's it' called again? -- oh, yes, READING, in order to comprehend. That title implies that there was a hole in the dam, itself. Anywhere else such a deceptive link would be regarded as "clickbait" (or "fake news" :) ).


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PostPosted: Fri Feb 10, 2017 12:52 pm 
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The spillway is part of the dam and it has a huge hole in it.

A pond near my shop didn't have spillway, today it doesn't have a dam. When it overflowed over the dam in that same rain storm earlier this week, it washed out a huge hole in the dam. The dam washed out and literally spilled the pond. It's gone, the pond I mean is gone.

It wasn't a very big pond but the nesting pair of Herons who came to it year after year to nest will also be gone I suppose. :(


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PostPosted: Fri Feb 10, 2017 2:47 pm 
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The dam has a spillway which is supposed to send overflow into the Feather River. The spillway has developed a large hole in it. This interferes with its proper operation.

If water tops the earthen dam and starts breaching it, the biggest reservoir in that part of California will end up much like Sam's pond. This would be catastrophic for a number of reasons.

The dam was built with a means of avoiding the above, but it's never been used and no one's sure what will happen if it is. The water runs down a second emergency spillway over a hill which has no concrete lining and which would rapidly erode into the river. Not as bad as losing the dam, but not good either.

This sort of thing is common. Even the Sepulveda Basin in L.A. has an emergency spillway. The level only got close once. Were the basin to spill, the 405 freeway would become a waterway.

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PostPosted: Fri Feb 10, 2017 2:49 pm 
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Why even bother reacting to what the con said in this thread, trying to make an argument out of nothing...

Rhetorical


Post #2 is worthy of being ignored as are all of his posts

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PostPosted: Fri Feb 10, 2017 2:55 pm 
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I read the papers. Don't you wish everyone did?

The hole in the spillway is worth a Google. It's in the bottom of the thing, and it's a real nice example of what water molecules do when there are a lot of them all wanting to be in the same place at the same time.

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PostPosted: Fri Feb 10, 2017 3:26 pm 
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That wasn't my pond ZoWie, it was my neighbor's pond.

If it had been my pond I would have put an 18 to 20 inch culvert in the dam just below the top to be a spillway. Even if I hadn't got around to putting that culvert in, I would have been out there in the pouring rain with a shovel and that pond would still be there.

It is amazing what can be done with a shovel in the pouring rain. It's even kind of fun.

Spillways for a big dam are a problem, there is an incredible amount of energy which has to go somewhere when a large amount of water drops to a lower elevation. That water is just a boiling to do some work with that excess energy. Nature refuses to allow energy to go to waste, it violates natural laws of physics. Designing the spillway is the most difficult part of a dam's design. The math used to model that part is hair raising, a computer is really handy and when that dam was designed there were no computers.

If that moving water can't move earth and stone with that energy it will literally boil that water and make steam with it. If you look at the photos of that spillway you will see five or six tooth like concrete things sticking up toward the bottom. That's where the energy is extracted from the flow, they're literally boilers. If it all works right for a dam of that height, about 1/5 of the water which goes down the spillway will be flashed into low temperature steam, and it forms a cloud which depending on the conditions of the day may momentarily holds that water before it rains it down. Or it may hold it for a while longer which allows wind to blow it elsewhere which causes it to rain down somewhere else, or rise and form a cloud.

The other 4/5 of that water having its excess energy drained away will flow downstream.

If the spillway is not designed just right that energy will destroy it. No materials are hard or strong enough to survive a bad design.



There are waterfalls which have a sufficient height that all of the water must flash into steam to absorb the energy. One of those water falls is near where I live. On a very cool day a bit a water will make it to the bottom as water, on a hot day none of it will. If one stands under it you will get wet from the mist recondensing, but that is rain. A continuous rainstorm at the bottom.

This happens on a steep slope during runoff. I see it happening here. For an hour or two after the rain has stopped but the water is still flowing, I will see some of that water turning back into a cloud, and then locally turning back into a bit more rain, a small shower later that day. My rain gage measures that rain water twice.


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PostPosted: Fri Feb 10, 2017 3:43 pm 
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So THAT's why they put those tooth shaped things in spillways. I always wondered. Thanks, Sam.

Much good video here:

http://www.sacbee.com/news/state/califo ... 59579.html

Yes we're talking serious laws of physics on this stuff. I have photos I took of the huge boulders in the Redondo Beach breakwater which wound up several hundred feet inland, in the parking lot. Hell of a time moving them back out. And that was from just surf.

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PostPosted: Sat Feb 11, 2017 4:12 pm 
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The Oroville Dam situation has gotten to the stage of troubling.

The damaged spillway has a gate, and it is somewhat controllable. When the damage occurred they closed the gate and they were able to inspect it and take those photos of that hole. Then they opened the gate some to allow 55,000 cfs of water to go through it. That hole is going to grow. But the spillway stretches across a hill beside the main dam, and unless the gate mechanism is undermined and all control is lost that seems manageable.

But that amount of water being released was unable to prevent the lake level from rising. Today the the lake slopped over emergency spillway. That spillway is not actually a spillway, it is a concrete lip sticking up and a chute extending for a distance before it becomes that hillside. Right now that emergency spillway is flowing 5,000 to 10,000 cfs, in addition to the 55,000 cfs of water going through the main damaged spillway. They run side by side for a bit and then the main spillway curves off to the side toward the main dam and powerhouse. The emergency spillway continues straight down the hill toward the river after the river has gone around a bend from the base of the main dam.

The engineers are saying that these flows will continue for 40 to 56 hours, based upon current modeling. That is a long time.

This is what is troubling. The power lines to the power house are laced over these spillways suspended on towers anchored to this eroding hillside. If those power lines go down they will have to shut off the flow to the generators at the base of the dam because the load has been lost. Without that load they cannot let water to continue to flow through the penstocks for the same reason that spillways are hard to design. It would blow a big hole in the bottom of the dam.

They can turn off that flow with the penstocks but if they do, that flow which had been generating electricity will be added to the flow going through the spillway. This kind of chain of events if they happen is known as a cascade failure. :|



It is supposed to be sunny tomorrow, with rains picking up again mid week.

http://www.sacbee.com/news/local/article132154774.html

I'm glad I don't live downstream from that dam!


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PostPosted: Sat Feb 11, 2017 4:37 pm 
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This just in,,

VIDEO: Water flowing over Oroville Damn emergency spillway - KRON

Really unfortunate day for the headline desk, I see. Anyway...

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PostPosted: Sat Feb 11, 2017 6:35 pm 
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That dam is not that old - I remember seeing it being built in the 60s. Last thing we need is to waste water, sending it down to the delta - I wonder how the delta/dikes are doing with all the water.


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PostPosted: Sat Feb 11, 2017 7:31 pm 
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Raw chopper video of the emergency spillway overtop. Farther in we see the new canyon being eroded out next to the now pretty much completely failed controlled spillway:

www.youtube.com Video from : www.youtube.com


Note the road downstream from the emergency overflow. That presumably will cease to exist if the spillage continues there.

This is a 700 foot high dam. Not small stuff here.

Pilot keeps mentioning a temporary flight restriction (TFR) over the dam.

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PostPosted: Sun Feb 12, 2017 12:37 pm 
http://www.sfgate.com/bayarea/article/O ... 925628.php.

The Lake Oroville Dam is only about Fifty Years Old. The damage to the spillway is slowly spreading, but the any meaningful repairs will have to wait until the end of the Rainy Season.

In the first forty days of this calendar year, the Bay Area has had over 26-Days of Rain. 13-Straight Rain in January alone.

The opening of the Emergency Spillway is a first, there is fear of damage to downstream salmon fisheries.

Two Months ago the rumors of a possible end to the California Drought were being dismissed, as of now the Drought is all but over.

Water Agencies in California will, depending on location lift some of drought restrictions. In the Santa Cruz Mountains, whole sections of highway 17 have been washed away. U.S. 1 is closed in both directions, closing access to Muir Woods and people living Stinson Beach are having a difficult into and out of their community.

Right now, we are dry. No rain until after Valentine's Day. But more storms are due next weekend.


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PostPosted: Sun Feb 12, 2017 1:20 pm 
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Up here in the hills according to my rain gage, we've have had 42 inches of rain in the 42 days since the year began. That isn't to say it has rained every day, those are totals.

I wonder if we will have 48 in 48, we'd be four footers.


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PostPosted: Sun Feb 12, 2017 1:38 pm 
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It appears from the photo at one of these links that mud has flowed across the road to the parking lot, but the part on the little dam at the edge of the catch basin is holding nicely.

My understanding is that the powerhouse is shut down, further limiting release of water, and the lines are not only de-energized but in some places actually removed.

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PostPosted: Sun Feb 12, 2017 2:21 pm 
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It appears from the photo at one of these links that mud has flowed across the road to the parking lot, but the part on the little dam at the edge of the catch basin is holding nicely.

My understanding is that the powerhouse is shut down, further limiting release of water, and the lines are not only de-energized but in some places actually removed.


Yes, I came across that detail later in the day yesterday. Shutting down generation diverts an additional 12 to 13 thousand cubic feet per second over the spillway.

It is dual irrigation and hydroelectric dam, the power generation and associated turbine throughput aspect is not as significant portion of the total as it would be at say the Glen Canyon dam which is a dedicated hydroelectric dam.

I haven't seen anything about it in the news, however by deducing it, I would guess they weighed the risks and decided the potential loss of life in the power house was not worth the added drainage from the dam that 12000 cfs would provide.

It is very likely that having that much erosion occurring a bit downstream in the gorge, that soil and rock will cave off and block the main channel somewhat thus raising the overall level of that outlet pool at the base of the dam. Might raise it above the level of the powerhouse and even above the level of the entrance tunnel to the powerhouse which is under the dam.

It would be kind of like submerging a submarine with the deck hatch open. I would imagine they shut it down, got the people out of there and sealed it off so it won't be flooded.

It is way too technical to try to explain in the news, better to gloss over it by saying they were worried that the towers were on a hillside which they were worried might erode. And they would have to shut it down in any event if that power line did go down. Which is pretty darned likely to occur.

Once I saw the whole system and it's interconnections with other water systems in the state, it occurred to me that they have an option in the event downstream flooding becomes a concern, that would be to start up the irrigation system and get farmers in the central valley to irrigate their fields until this crisis has passed. That would move a lot more water than the power house moves.


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PostPosted: Sun Feb 12, 2017 2:34 pm 
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Wonder if they'd be ready for irrigation this early.

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PostPosted: Sun Feb 12, 2017 2:51 pm 
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No they wouldn't, and they'd grouse about having to do it.

But it is one way they could shunt a whole lot of water out if that drainage and impound it for a while thus reducing the peak flood potential in that drainage.

It is one of those it could be done, but is a political impossibility things. The pipes and canals are in place, but to make it work farmers would have to work. Oh, they'd piss and moan.


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PostPosted: Sun Feb 12, 2017 9:42 pm 
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This is getting serious. Now the emergency spillway is under suspicion of impending failure, and southern Butte County has a mandatory evacuation. 100,000 people are affected.

http://www.sfgate.com/news/article/Lake ... 926950.php

Quote:
OROVILLE, Butte County — Butte County residents near the Oroville Reservoir, including the entire town of Oroville, were ordered to evacuate Sunday evening after the emergency spillway next to the reservoir’s dam suffered a possible structural failure, officials said.

“There has been severe erosion of the emergency spillway and a possible structural breach that could send uncontrolled water down the stream,” said Chris Orrock, a spokesman with the California Department of Water Resources.

Residents downstream from Lake Oroville were ordered to evacuate. Counties around the reservoir, the second largest in the state, and down to Sacramento were notified about the possibility of flooding.

Department of Water Resources officials issued a statement just before 4:45 p.m. that the “auxiliary spillway at the dam was predicted to fail within the hour.”


Note: that was over an hour ago.

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PostPosted: Sun Feb 12, 2017 9:53 pm 
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BREAKING: Marysville, Yuba County evacuated as Oroville spillway collapse feared
http://www.sacbee.com/news/state/califo ... 32499.html

Has the orange one killed FEMA yet?

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PostPosted: Sun Feb 12, 2017 9:59 pm 
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There was a live stream but now it's dark. The night, I mean. The stream just went dark too.

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