Doesn't everyone?

I wonder how difficult or cost-worthy it might be to install a syphon-type system over the E-spillway to help lower lake levels. The tubes wouldn't be all that large, but if they built a number of them side by side, I imagine they could syphon about as much as the powerplant puts out.

The idea would be to fill the tube with lake water on the river side up to the fill port, then pop open the gate valve at the bottom & let it syphon out however much water they need to. The Gate valve I think would be the hard part as it would have to be able to essential burst open to let the water out quickly to start the syphon?, and they would probably also have to install a separate closing valve to shut off the flow...

I don't know.
Something like this maybe? (forgive me for the crappy MS Paint skills - this image is obviously not to scale & yes - the entry point would be much lower in practice.)


And you know... Whenever they were through with it, they could always just convert it into one hell of a Slip & Slide.

Can you imagine the vacuum that would be needed and the very thick walled pipe. Also notice that the reservoir is shallow at the sides.

I don't know - I think it would all depend on what diameter size of pipe they actually used...
After that, the only questions are then - How many to use, & lastly - could they still be used for Slip & Slide purposes afterwards. lol

It works for small reservoirs. Doesn't scale up well.

Appurtenant Structures for Dams  (Spillways and Outlet Works)  Design Standard

Siphon spillways is on page 3-52.

At the end of the day - they still need to retain water for dry season power generation, recreation, and the ability to keep water in the downstream water system.   I don't think they want to roll into the dry season much below full pond (around 850'   Don't recall the exact number)

Disappointed dam didn't break flooding a good deal of commie CA.

If we were to attempt this with a garden hose, I imagine what would happen is at some point up the hose from the outlet the hose would become sucked in on itself (flat) only allowing a tiny amount of water to syphon down the hose - Solution? - get a hose with a stronger cross section?

The question with this syphon proposal is - How big of a diameter of pipe/tubing & how thick of a wall for said pipe/tubing to hydrostatically support an approximately 700-900ft column of water at said pipe/tubing's diameter? The larger(higher?) the difference from entrance to exit, the less water (per tube) can be moved, because the tube must be smaller (& thicker walled) in order to support the hydrostatic forces (weight/vacuum)  of the column of water being gravity fed / syphoned?

This kind of stuff makes my head hurt...

I came as close as I ever have to pushing the button on this one ........... but I didn't.

Mayhap a stouter fellow will do so.

Not cool. They aren't all assholes.

I second this.

ARFCOM has a long-standing habit and tradition of so doing.

I have no idea how hard this is but what about boring a tunnel, or series of tunnels, through the bedrock in order to use as a spillway, obviously a flow control gate would need to be added. Probably a dumb idea. To me it's more practical than a siphon though.

These are all just pictures I found online...  most of them from DWR's image site... which sucks and takes a bit of tinkering to obtain the pictures from it so I can rehost with imgur.

This is the site: https://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/Oroville-Spillway-Damage

Where you think the river went while the dam was being constructed?

And then plug up one end of the big pipes so they could only handle the minuscule turbine flow,
and not the entire river bypass flow.
You know, why would one ever need to bypass the entire river flow ever again.

I get that but I figure it may need to be a longer run and much more costly to do it as a spillway.

Probably cheaper to build a syphon system..lol.

I think they need to put in one of these.

Gloryhole.

There are two river diversion tunnels that were used to route flow around the dam area during construction of the dam. Both were plugged with 150' concrete plugs once construction was complete. They are connected to the power house intake and all water from the diversion tunnels now goes through the power house. Tunnel 1 is generally half out of the water, tunnel 2 is below it  and always under water. The river bypass valve was damaged (see details earlier in the thread) in 2009, IIRC, and currently inoperative. Some repairs have been done but not enough to use the tunnels as a bypass.

 Book of Dams Page 80 - Tunnel Systems

The design of the dam isn't the problem. The problem is that required maintenance hasn't been done or when it has been done it's been done poorly. They basically destroyed the diversion tunnel valves during the maintenance mentioned above and detailed earlier in the thread. Had they inspected the spillway and maintained it during the previous low water conditions this all would be an non-event. High speed trains and social programs for criminal invaders were more important. Plus globe warming, climate change, whatever you call it, were going to cause it to never rain again.

Looks like a fun day at work for both the air crew and lineman.
Good post

Scale again. Plus pipes and tunnels are subject to cavitation damage at high flow rates. I've posted the Bureau of Reclamation Spillway design doc several times through the thread. Here's a picture of the damage at Glen Canyon Dam during a flood control event that almost over topped the dam.

It does seem like a better idea in that type of situation. It will help equalize the water pressure down the river better.

Disappointed some guys need a pocket on their t-shirt to carry extra chromosomes.

You do realize that the part of California it would have flooded is a far cry from commie?

My first underground job was working behind a Tunnel Boring Machine that was part of the Utah water projects.

It was an 8 mile tunnel started on each side of the mountain.  Was a 1/4 inch off where they joined up.
When it was finished a dam was built and now is the upper stillwater dam, and resivoir.  

That tunnel takes water from the dam to the Hanna Utah side of the Mtn.

A glory hole spillway could be, say,built back in some
canyon and connected to a tunnel that went where you wanted it to go.
Upon completion the earth between the Gloryhole and resivoir would need dredged out .
So to me while possible even with the res. full.  It would be far easier and less costly to fix what they have. Let alone the time.
I'm waiting to see if the plan is to save parts of the spillway or remove it all and rebuild.

Why not just build a new spillway net to the old one and when near completion hook it up to the gates. The same way they do when replacing a bridge. The new one is completed and then the connection to the old road is made in very quickly. Then route the emergency spillway to the main spillway so it has an actual path to follow, not just wash out the hillside.

You have the bottom end of the siphon immersed in the river water...

Re-think that component...

Hint--- Chicken Waterer...

Concrete guys.... How long would they need to leave the water off of a newly poured spillway?

Trivial...

Solution---

Vents along the hose...

On a pipe sized to do any good it is far from trivial.

They didn't mention this in the interview but when the report comes out it will likely be one the major contributing factors to the loss of control of water release and I will take particular interest in the math. I think it's possible that the emergency spillway may not have been needed much if at all if the diversion tunnels had been available.

Why do you think so?

It is the standard in dam construction.

Glen Canyon, Hoover, all of the big ones.
The diversion tunnels are plugged on the upper end.

Yup, we are all commies here...

How about thinking about how much vacuum you would need to pull water up say 100 feet a 5
foot or bigger diameter pipe. Think about what that vacuum would do to that pipe.

I have seen piping collapse that was not designed for vacuum. I have seen how thick
piping designed for vacuum is for a very much smaller pipe and to imagine the scale
of such a project I do not believe there is any pipe made like that.

The gated spillway is the designed primary flood control mechanism. It has been run at 150 KCFS in the past. It's rated for 300 KCFS but that means down stream gets washed away but the dam itself will be safe. The original diversion tunnels allowed them to limit the use of coffer dams during construction and reduced the size of them when necessary. Their capacity was drastically reduced after they were plugged and the intake of both of them shifted to the Power House intakes. The limiting factor being how much water can pass through the power turbines. Having the river outlet valves working in the diversion tunnels would have been a big help, they probably would have been able to manage the lake's level with the recent reduced inflows. They would have still had to run the spillway at high flow rates last month but the E spillway would never have come into play.

I worded this poorly. The penstock tunnels from the lake inlet to the power house are physically separate tunnels from the diversion tunnels.

The way they have managed the lakes capacity is an issue too. The dam was designed as a flood control dam, not a irrigation reservoir. Design full pool is 850, they were above that in January. They didn't open the spillway until they had an oh shit moment that having pool level at 850 with 150 KCFS inflows wasn't a good idea. When they did open spillway their lack of proper maintenance bit them in the ass.

Page 92 states, "The flood control outlet was sized on the basis of limiting Feather River flow to leveed channel capacity of 180 KCFS during occurence of the standard project flood (peak inflow 440 KCFS)." Even at the 100K rate they were flowing after they over topped the E spillway there were some levee problems down stream. More maintenance issues.

Page 82 states, "Maximum discharge through Tunnel No. 1 during generation is 12,000 CFS (picking up flow from units Nos. 3 through 6) Discharge through Tunnel No. 2 is 6,000 CFS (units Nos. 1 and 2)."

Before the plugs were put in the diversion tunnels had very large flow capacities. Chart on page 98 shows 103 KCFS with one tunnel and 183 KFS with both tunnels running. However tunnel 2 was plugged in August 1966 when the embankment (dam) was high enough to control flooding with only tunnel 1 functioning. 1 was plugged in November 1967 when the embankment was topped out and the spillway essentially finished. "Gates were lowered at the intake of Tunnel No. 1 to dewater the tunnel for plug construction. This act marked the beginning of filling Lake Oroville."

This is all from this document titled California State Water Project, Volume III, Storage Facilities. Bulletin Number 200, November 1974. Book of Dams
The section on Oroville Dam and Lake Oroville is Chapter V and starts on page 62.

I was thinking back to the numbers that they can release through the diversion tunnels and it isn't that much, it would have helped but without a reserve capacity they had no choice but to use the emergency spillway. I just thought they were missing something not mentioning it as one of the contributing factors in the interview.

Depends on what you make the pipe out of & how thick the pipe wall is, but even aside from that - why 5ft diameter for a single pipe? If you could do the same job with a thicker-walled 5 inch pipe using 500 of them or so to produce a similar overall flow-rate?

I don't know what the answer would be, I only know that there is one. Like I said before - this kind of stuff gives me a headache.

Cost prohibitive. Image having 500 pumps as well as 10's of thousands of feet of a thick walled pipe.

This would cost far more than repairing the dam and your idea does not even factor the protection
needed from the discharge of those 500 pipes.

That was deliberate from what I can tell. They didn't want to call attention to how badly they fucked up "maintaining" the river valve system.

This has been one of my contentions all along.
But the original tunnels would have to be used, not the modified, reduced ones, with the faulty valve, to get enough flow to solve the problem.
However, upon further reflection, I have come up with the following, prompted in part by the 'siphon' concept/discussion above.

The 'bypass' tunnel and valve, that failed, is 72" dia. and capable of a flow of ~7500 cfs. After the accident, it was restricted to a flow of ~ 5000 cfs because the turbulence ring, or whatever it is called, was not replaced. "because we will never need it again". That 5000 cfs would have made very little difference to the 'big picture' of the amount of water that needed to be released. Remember, inflow was around 190,000 cfs at peak, during the initial crises.

The original bypass tunnels are ~32' in diameter. And they handled ALL river flow, including during flood season, during construction of the dam. They were spec'd for peak river flow of over 200,000 cfs.
 But there is a HUGE difference in design / performance between atmospheric pressure, and the pressure generated by ~700 ft of head, = 350 psi +/-.

Just look at the water flow over the main spillway, when that was running at 100,000 cfs, that was generated by 80 ft of head, ~ 40 psi. (spillway height 820 ft, ES height 901ft =81 ft, gate opening ~3 ft)
Now compare that to the 10,000 cfs that was running over the emergency spillway at atmospheric pressure.

If those 32 ft tunnels were turned on at those sorts of flows  and pressures, the turbulence, cavitation, and resultant damage would tear them apart in very short order. They were built to handle large flow at atmospheric pressure - think road culvert flowing 1/2 full.
Now look at how culverts disintegrate shortly after they fill up and turn into a solid 'fire hose' type flow, with only a few feet of head, eg when the road overflows.

Look at the photos of the cavitation damage done to the tunnels shown above, and to the damage done to the Hoover dam spillways when they were used, back in '98.

Perhaps there is a way to build high flow, high pressure tunnels and controls that would work in this situation, but now I realize why spillways are atmospheric pressure, 'over the top chutes',
and not underground tunnels, when in regular usage.

So, I am eating some crow here, because earlier I was calling for opening up those bypass tunnels.

I was wrong.

I guess that is one of the many reasons that I'm just a dumb truck driver, and not the mech. eng. I aspired to become, 50 years ago.

PS - All the number mentioned above are very approximate, just to illustrate the concept. And physical numbers came from memory, from previous posts in this thread, and from reading the 'book of Dams' earlier.
Please, if any of my assumptions, numbers, math, etc are incorrect, please correct me.

ETA - beat like a drunk whore by XD-FAN, above, with a much clearer explanation of the bypass tunnels.
I started typing before he posted, however.

Another issue is that you can only lift, or suck, about 30 ft of head of water, which is ~ 15 psi, negative.
Dont need a very strong tube to not collapse under that. But only 30 ft of lift doesn't do much on the scale needed here.

What is wrong with you people? It's not like this is rocket science. You don't need to suck water from 30 ft, you just need to be able to pump a small rate of it (under pressure) to the high point of the system so as to fill the pipe on the river side...once. After you open the bottom valve on the pipe , the weight of the column of water in the pipe will create it's own suction (vacuum)... Thus the reason it is called a syphon.

& as for the cost effectiveness of such a venture, it still depends on the type & amount of materials used, not to mention that if it were to be a multi-pipe-type setup, you could build & use it one pipe at a time thus offsetting the amount of funds needed during a given timeframe, but hey - what do I know. You bunch a nay-sayers clearly have it all figured out.

Nailed it.

This is from the spillway doc. Hence my comment about it not scaling. There's probably more to siphon spillways, but there isn't much more in the spillway doc than the screenshots below. My wife is about feed up with "Oroville crap", as she puts it so I'm not putting any effort to finding more info on them. I know far more about dams and spillways than I ever planned on knowing at this point. I will say there are some spectacular pictures of spillway failures in the doc. The pictures of the Folsom dam gate failures are something to see.





So yes, you could put a mega shit load of siphons across the top of the E-spillway but that puts the pool at 872 feet before they can even come into play. The gated spillway had better be running at a pretty high flow at that pool height, dependent on inflow, by then. The gates are supposed to open early enough to control a crest to 850 feet. This is a flood control dam, not an irrigation reservoir, as these numbskulls have been operating it as. Pool should have been well below 850 in January, not at 850 like it was.

Are they about to conclude this release through the spillway?

He didn't nail anything, and neither did you. The hydrostatic pressure is dependent upon the amount of drop relative to the entry point. The examples in that document only use a 30ft drop (likely because no one has ever bothered trying anything the size of this since there was never a need), but while the Oroville dam has a maximum height/depth of @ 900ft, the syphon's entry would only need to be about half of that, leaving a hydrostatic drop of @ 450ft relative to the exit point. If both entry & exit points are under water (so as not to introduce large amounts of air into the system, the rate of flow can be easily controlled by gate valves. ...Also, that document only mentions pressurized syphon systems, not natural vacuum syphon systems such as this. The maximum amount of flow would depend upon the number of pipes used, and sure - it wouldn't be all that cost effective relative to the amount of overall discharge produced, but still - I have never heard of a syphon system having a failure such to the extent that it could ever possibly cause damage to the structure of the dam. When these type of systems fail, they simply stop functioning.

You can only pull it up about 30 feet no mater what.

You are relying on atmospheric pressure to provide the 'driving' force.  14.7 PSI.

Laminar flow is less damaging but very difficult to maintain as velocity climbs on a large drop.

The viscosity of water is the viscosity of water and that drives a whole lot of flow calculations.

I have not done any of this kind of work in 30 years.

We had to deal with Reynolds numbers and boundary flow conditions.

You can destroy all sorts of equipment when flow gets turbulent inside a line.