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PostPosted: Tue Feb 28, 2017 11:07 am 
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The power lines will not be all that hard to restore. They removed the insulators on two towers, so that the towers could fall down without pulling the whole line down, and they left the wires hanging. Both of those towers were there to stabilize the lines over low spots, not to hold the wires up.

Keep in mind I'm stating that from having watched videos, not from having read anything about it.

They've already been dredging around the spot where the spillway flow made it impossible, so getting after that spot might not take that long.

I think they filled in a spot between two hills and that is the part which washed away. The end of the spillway appears to be anchored to bedrock.

If I were filling in that hole in between I would order a lot of styrofoam blocks. I would place a lattice of rebar in the hole and pour a bottom layer, then place styrofoam blocks between the rows of rebar and fill the gaps with the rebar with concrete, and then top over the blocks with another layer of concrete. Then repeat that process over and over until it reached the top where a new chute is needed. For the edge slip forms would be used to create the wall.

I would do that because it would keep the concrete volume in any one place down to an amount which could cure without overheating. The structure would be about 40% concrete, and 60% styrofoam which would remain in the structure. Kind of like a concrete building where the walls and ceiling/floors are concrete, and the rooms are solid styrofoam.

If they tried to pour that structure as solid cement they would need to mix it with ice instead of water to keep it cool during the curing period. And that would mean a very slow curing period which would not be ready in time for a chuit to be built on top before winter.

I wouldn't try to fill it with earth, they don't have time to both fill it, and stabilize it, and then build a chute on top of it before next winter.

Bridging it, interesting point. i'd rather see boulders and slurry as a base, but you're right. That'd be one hellava lot of concrete. Perhaps a modified soil to bring it up to the proper elevation that the chute could be rebuilt on. Only problem, that's a huge amount of modified soil. Don't know if they have the time. It's something new and will be interesting to see how they attack it.

i was hoping that the new channel cut was far enuf away from the chute that not much backfilling would have to be done., but it sure doesn't look like it now.

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PostPosted: Tue Feb 28, 2017 12:18 pm 
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Boulders and slurry are what they're using along the base of the auxiliary spillway, and it would solve the heat of hydration problem in thick built up areas because the boulders volume would provide an adequate heat sink to offset the slurry volume.

If they basically filled in that channel and squared off and reinforced the end and drop off face of the existing chute they could turn this into a two stage, two year job. I'm saying that because they could discharge water through it next winter with little additional erosion. It could be for the first year made into a decent working cascade spillway.

That is the other way a spillway can be designed to absorb the excess energy of the falling water. Nature's way, a jumble of huge solid rock on top of solid bedrock.

The fill under that broken off end of the undamaged chute appears to be thick, and where more fill was gouged out before the missing part of the chute reaches that hill top, that part was scooped out to bedrock. They could fill that in somewhat with bolder and slurry, and be able to direct the flow over that hill top. They could add glass and carbon fiber to the slurry mix and produce a very strong reinforced bed which might even be stronger than the original bedrock.

Then allow next winter's flow to be the working force to strip the remaining parts of the end of the remaining chute away for the next stage of construction the following summer.

That would mean dredging that pool twice. And shutting down the power house twice. After looking at that video I see two years of work there, perhaps three. There is such a limited access to the site, and there is that slope to consider, I can't see how that amount of work could be done in just one working season.


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PostPosted: Tue Feb 28, 2017 1:23 pm 
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True. The working season is a fairly short one there. Same reason the seasons on the roads up to Tahoe seem to be fall, winter, spring, and construction.

Excellent aerial in the L.A. Times of the main spillway minus the 100,000 cfs of water and passing only a trickle. The bedrock, and lack thereof, are clearly exposed. The middle portion of the spillway is gone, as in no longer extant, and it's clear to see where bedrock has diverted the flow into that new gorge that would be out of frame to the right.

Cascades are an interesting idea. Famous old William Mulholland solution that seems to work on his smaller scale.

Now... someone will have to tell me if it's possible to move water through the powerhouse without turning the (currently loadless) generators.

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PostPosted: Tue Feb 28, 2017 1:58 pm 
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Speaking of rain, in San Diego we received the equivalent of an average February on Monday. Normally, San Diego gets about 2.2 inches in February and from late Sunday night until early Tuesday morning we received 2.34 inches. Petco Park, home of the San Diego Padres, was flooded. Fortunately, the grass was removed before the storm for a monster truck rally.

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PostPosted: Tue Feb 28, 2017 2:23 pm 
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True. The working season is a fairly short one there. Same reason the seasons on the roads up to Tahoe seem to be fall, winter, spring, and construction.

Excellent aerial in the L.A. Times of the main spillway minus the 100,000 cfs of water and passing only a trickle. The bedrock, and lack thereof, are clearly exposed. The middle portion of the spillway is gone, as in no longer extant, and it's clear to see where bedrock has diverted the flow into that new gorge that would be out of frame to the right.

Cascades are an interesting idea. Famous old William Mulholland solution that seems to work on his smaller scale.

Now... someone will have to tell me if it's possible to move water through the powerhouse without turning the (currently loadless) generators.


A very small amount of water can be expanded into a very large pipe through a hardened orifice. Perhaps one to two thousand cfs. Not enough to make any difference. And the life of the orifice will not be long, as it will be worn away.

Of freeze shut, that kind of unchecked expansion flow will refrigerate and create an ice plug if the orifice is not heated.

Remember how carburetors would sometimes ice in the venturi, and how that would power down the engine on cold foggy days?



Any large release would blow away the powerhouse and open a hole in the bottom of the dam which would cause its collapse. There must be a load.

There is more than that to it too.

That video Bernie posted brings up an issue about the water level outside of the power house, about how the water level of the pool must be below the level of the outlet pipes for the turbines to be able to operate even with a load. That is a superheat issue, the turbines must operate with some degree of superheat. The superheat must never be zero. That is to say there must be some available expansion space at the turbine outlet. If there is none the hydraulic pressures will make some. And that will lift the turbine moving parts part up off of the turbine housing. Then the turbine's blades would strike the housings side and break.

The back pressure caused by the pool level being a bit high wouldn't be much, 5 or 6 psi, one would think it would be overcome by the immense pressure of the height of the dam and the mass of the water, but that little bit of back pressure would be enough at that critical juncture right at the turbine's outlet where it connects to the tube leading out of the powerhouse to deprive the turbines of the superheat it needs to hold together. It would move the superheat from that juncture to the ends of the outlet tubes which is the wrong place for that expansion to be.

This issue comes up in normal refrigeration, occasionally a thermal expansion valve will not operate correctly or a service tech will put too much freon into a system and it will move the superheat from the refrigerator expansion coil all the way through the coil and down the suction pipe leading to the compressor. That means the cooling effect moves from the freezer box to the body of the compressor, so the food doesn't stay frozen, and the compressor drinks liquid instead of gas, and that blows the valves out of the compressor.

Boilers must have superheat as well. There must be space inside of the boiler for water to flash into steam. If they lose the superheat inside of their working vessel they might blow up. It all depends on the pop off valves, it they are large enough they will save the boiler. although some or all of the fire tubes may be lost.


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PostPosted: Tue Feb 28, 2017 3:30 pm 
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Speaking of rain, in San Diego we received the equivalent of an average February on Monday. Normally, San Diego gets about 2.2 inches in February and from late Sunday night until early Tuesday morning we received 2.34 inches. Petco Park, home of the San Diego Padres, was flooded. Fortunately, the grass was removed before the storm for a monster truck rally.


That was strange. I looked at the radar and San Diego looked the way Santa Barbara usually does in a SoCal rain storm. It came up from the south instead of down from the north. North of Orange County, it stayed bone dry.

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PostPosted: Tue Feb 28, 2017 8:14 pm 
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That was strange. I looked at the radar and San Diego looked the way Santa Barbara usually does in a SoCal rain storm. It came up from the south instead of down from the north. North of Orange County, it stayed bone dry.

IIRC, the local weatherman said there was a front from Alaska coming down the coast and it was drawing in the "atmospheric river" that originated in Hawaii into the San Diego area. Good thing about the rain was it cleared out the skies of hazy/smog leaving partly cloudy skies and unlimited views. When I went over the Coronado Bridge early this afternoon you could clearly see the Coronado Islands about 20 miles away.

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PostPosted: Wed Mar 01, 2017 3:44 am 
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The Sacramento Bee is reporting, "the water in the channel below the spillway dropped 23 feet in less than a day, enough to get at least one of the turbines up and running, perhaps as early as Thursday. Electrical crews are working to get transmission lines running from the plant reattached to the power grid.

http://www.sacbee.com/news/state/califo ... rylink=cpy

The video Bernie posted talked about needing to maintain some river flow for the fish. One of those turbines running would provide that. All six of them running would discharge enough water that they might not have to do a spillway release for about a month, depending on the amount it rains of course.


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PostPosted: Wed Mar 01, 2017 11:11 am 
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Sweeeeet. A warm feeling came over me to see booms swinging and earth moving. 8-)


The lone dozer seemed out of place though. Looks like he was building a haul road. For what though?

Two days they said they'd have the rubble out. No way. Maybe i misunderstood and they meant to have a channel cleared. That's a summer project alone. Sure would like to see the staging plans.

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PostPosted: Wed Mar 01, 2017 11:47 am 
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Yesterday I did some mowing round the house. This morning about sun up I stepped out into a flock of about a 100 wild turkeys who were feeding on the green frost covered clippings. The males were all doing their full strut, more than earth was moving there, there was wild turkey juices a flowing. Spring mating season is here.


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PostPosted: Wed Mar 01, 2017 2:45 pm 
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Apparently the front had no moisture to work with until it got nearly to Mexico and hit the feed from the tropics. It's nearly always the other way around. They dump on San Luis Obispo and Santa Barbara counties, then drop off as they move southward.

At some point they're going to have to make a new road to the parking lot at the far side of the weir, because the one they had is gone.

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PostPosted: Thu Mar 02, 2017 7:46 am 
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Isn't that a thing of beauty....

http://www.sacbee.com/news/state/califo ... 60663.html

Image

It looks like the haul roads built are exiting up and to the right of the emergency spillway. Now, how can we tighten that up a bit? To many trucks sitting at the top of the hill.

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PostPosted: Thu Mar 02, 2017 10:55 am 
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They got a lot of work done yesterday.


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PostPosted: Thu Mar 02, 2017 1:28 pm 
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Isn't that a thing of beauty....

http://www.sacbee.com/news/state/califo ... 60663.html

Image

It looks like the haul roads built are exiting up and to the right of the emergency spillway. Now, how can we tighten that up a bit? To many trucks sitting at the top of the hill.

Hard to tell from a still picture if the trucks are sitting still. From the positions of the excavators and the paths of the dump trucks it looks like the trucks at the top of the hill are moving into position to be loaded.

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Last edited by Number6 on Thu Mar 02, 2017 5:05 pm, edited 1 time in total.

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PostPosted: Thu Mar 02, 2017 1:55 pm 
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As of last night, the California Snowpack is at 185% of Normal. Estimates are as high 40 Feet of Snow if not more.

March is usually a called "Miracle March" for the snow storms in that month. Right now, California could not receive any rain or snow for the rest of the year and not be left hurting. The drought is all but over.

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PostPosted: Thu Mar 02, 2017 5:06 pm 
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As of last night, the California Snowpack is at 185% of Normal. Estimates are as high 40 Feet of Snow if not more.

March is usually a called "Miracle March" for the snow storms in that month. Right now, California could not receive any rain or snow for the rest of the year and not be left hurting. The drought is all but over.

The local weatherman was saying last night one of the ski resorts could stay open until the July 4th weekend.

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PostPosted: Thu Mar 02, 2017 5:34 pm 
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http://www.sfgate.com/news/article/Orov ... 971009.php

the drone video is absolutely fascinating....

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PostPosted: Fri Mar 10, 2017 9:36 am 
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Oh, look. Rock dams are now being built on the emergency slope....

Image

http://www.mercurynews.com/2017/03/08/o ... ne-online/
Crews have been working ever since to fill in eroded area and cover the slope with concrete slurry. Catch dams and other barriers are also being constructed to slow erosion should the emergency spillway need to be used again, according to DWR.

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PostPosted: Fri Mar 10, 2017 10:07 am 
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Hard to tell from a still picture if the trucks are sitting still. From the positions of the excavators and the paths of the dump trucks it looks like the trucks at the top of the hill are moving into position to be loaded.

See the bottom hoe? Two trucks side by side at the bottom of the picture? One's leaving, one's being topped off and will fall in line behind the one that is leaving. If i were that hoe operator i'd be wondering where my next fucking truck is. Oh, there they are. All bunched up on the top of the hill. Happens all the time. Ya send four trucks out in the morning at 6:45. Ya send the next four at 7:00. The next at 7:15. Try to spread them out so they don't bunch like that. Never fails though, by noon they are riding each others asses back to the job. One minute you have no trucks and the next there's ten of them sitting in line. It makes the dirt foreman pissy. He's the one that insists those with half a brain be called, 'Truck Driver'. :)

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PostPosted: Fri Mar 10, 2017 1:58 pm 
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Rock and cement, from the look.

Hindsight is SO 20-20.

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PostPosted: Fri Mar 10, 2017 10:33 pm 
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And according to latest reports, California will be looking an El Nino next year....which is exactly we do not need.

http://www.sfgate.com/bayarea/article/A ... 991042.php.

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PostPosted: Sat Mar 11, 2017 2:52 am 
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And according to latest reports, California will be looking an El Nino next year....which is exactly we do not need.

http://www.sfgate.com/bayarea/article/A ... 991042.php.

If we could somehow figure out how to safely replenish our aquifers then the rains from an El Nino wouldn't be that much of a problem. We could lower water levels in our dams by putting it in the aquifers before the rains begin and then letting the water from the rains replenish the dam levels.

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PostPosted: Sat Mar 11, 2017 4:34 am 
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They'll manage the dams.

The summer will be long and hot. By next winter an El Nino will be refreshing. :)


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PostPosted: Sat Mar 11, 2017 7:59 am 
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See the bottom hoe? Two trucks side by side at the bottom of the picture? One's leaving, one's being topped off and will fall in line behind the one that is leaving. If i were that hoe operator i'd be wondering where my next fucking truck is. Oh, there they are. All bunched up on the top of the hill. Happens all the time. Ya send four trucks out in the morning at 6:45. Ya send the next four at 7:00. The next at 7:15. Try to spread them out so they don't bunch like that. Never fails though, by noon they are riding each others asses back to the job. One minute you have no trucks and the next there's ten of them sitting in line. It makes the dirt foreman pissy. He's the one that insists those with half a brain be called, 'Truck Driver'. :)



Then they charge you for waiting.


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PostPosted: Sat Mar 11, 2017 10:22 am 
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Rock and cement, from the look.

Hindsight is SO 20-20.


Notice, they said slow the erosion. i don't think they have enuf hill to armor and stop the erosion.

And i think we'll be hearing about this in the future.....

https://theconstructor.org/concrete/cav ... tion/8890/
Cavitation damage occurs on concrete surface when discontinuity or irregularities is encountered in the path of high velocity water flow. This discontinuity or irregularity in the flow path cause the water to lift off the flow surface, creating negative pressure zones and resulting bubbles of water vapor. These bubbles travel downstream and collapse. If the bubbles collapse against a concrete surface, it sends a very high pressure impact over an infinitely small area of the surface. Such high pressure impacts can remove particles of concrete, forming another discontinuity which then create more extensive cavitation damage.


The Glen Canyon Dam had the same problem. They almost lost it because of cavitation in 83. The retrofit with aeration slots helped alleviate the problem, but from what i understand so far, does not fully solve the problem.

https://www.usbr.gov/uc/feature/fg/index.html
Cavitation is the formation of partial vacuums or cavities in fast-flowing water which wears away solid surfaces such as concrete, as a result of the collapse of these vacuums. The subsequent repair of the Glen Canyon Dam spillway tunnels included aeration slots which inject air at the base of the water flow to prevent cavitation from occurring.

As a result of the lesson learned at Glen Canyon Dam, Reclamation retrofit other dam spillway tunnels with similar aeration slot designs. The spillway at Flaming Gorge Dam on the Green River in northeastern Utah was modified in the mid-1980’s not long after the Glen Canyon spillway. Although the Flaming Gorge Dam spillway has rarely been used, a periodic inspection of the spillway revealed damage to the concrete in the area where tunnel was modified to install the aeration slot, about four feet above the edge of the aeration slot itself.

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