Dam Solution?

The goyte is a fast running river, canals are designed for slow movement of water have a very small 'fall' except for locks wich have small byewiers to maintain levels are not designed for large volume discharge. The river has few constructions to be damaged and generally not much in the way of adjacent buildings. I have spent many an hour letting water down a canal lock flight in order to refill an empty pound that vandals had drained and it takes some deal of time when everything has to go through the gate paddles. The normal feeder for the canal will be small bore, little more than a drainage pipe. The video's I've seen have shown the discharge from the pumps flooding the bottom of the spillways which are adjacent to the reservoir. The spillways themselves are designed to discharge excess water direct into the local water course and are as such the intended way of dumping water.

regards Martin

regards Martin

Edited By Martin Kyte on 07/08/2019 09:40:30

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Have a look at this gallery, to get an idea of the work that has actually been involved: **LINK**

https://www.manchestereveningnews.co.uk/news/greater-manchester-news/gallery/view-top-toddbrook-reservoir-16699220

Kier construction built a new 'road' whilst we were pondering how things could be done!

... and there are some good detail shots of the pipework.

MichaelG.

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Looks like they've won: https://www.buxtonadvertiser.co.uk/news/fifth-day-of-operations-to-secure-toddbrook-reservoir-in-whaley-bridge-live-updates-1-9915919

Thanks and congratulations to them all 

Edited By Michael Gilligan on 07/08/2019 10:18:11

The well known fount of all knowledge Wikipedia says it is 24m deep, https://en.wikipedia.org/wiki/Toddbrook_Reservoir we've already been into why you can't syphon more than 10m or so (unless you have degassed water and a laboratory). However I've just looked at Michael's link and the BBC think it is less than 24m, but more than 10m

Edited By duncan webster on 07/08/2019 10:16:16

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Sorry, Duncan ... I'm still really struggling to understand why you can't syphon more than 10m or so, given that the water is 'all in one piece'

Regardless of the actual physical depth of Toddbrook reservoir, I'm certain that its bed is above the local elevation of both the Goyt and the Canal.

I would be genuinely grateful if you can explain the syphon problem in terms that I understand

MichaelG.

Micheal

I would suggest something far stronger than coffee.

In thermodynamics there is the concept of an enclosed system. Something, a device or anything, in a sealed box cannot be influenced by outside events or influence the outside. Such a concept is hypothetical but useful. It is easy for one to think of exceptions, if you do I will just redefine the sealing of the box.

In this case the pipe is the box. What ever you do to the outside will not increase the pressure.

There is another way of looking at this. The pressure of the water in the pipe is the water's internal energy. If you increase the altitude you have done nothing to the water, all one has done is to increase the potential energy of the whole system.

I hope this makes sense.

I like the photographs. I thought more pipes were being used. What I see can be quickly put on the back of some trucks and driven up the M5 and M6.

JA

Edited By JA on 07/08/2019 11:15:11

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Thanks for this JA ... I will try again tonight, with a glass of good Malt.

Regarding the pipes: Yes indeed ... it was probably on Monday that I walked past a couple of vehicles loaded with same; parked-up on the A6, presumably waiting to be let through the Police road-block.

MichaelG.

When you find someone using phrases like 'pressure potential energy' be very wary. It shows a confusion with Bernoulli's equation which can be expressed as p + rho*V^2/2 + rho*g*z = constant, the rho*V^2/2 looks like kinetic energy but it isn't. Similar, but no coconut.

I'm not sure what I can add to previous discussions on why you can't suck more than 10m or so in a normal atmospheric pressure with normal run of the mill water

Edited By duncan webster on 07/08/2019 12:12:27

Shouldn’t be a problem discharging from the pumps into the canal as canals have their own discharge spillways strategically positioned along their length to discharge excess water and prevent said canal from flooding.

Dave W

The canal over spills into the Goyt at Whaley canal basin, perhaps 20 yards from where any water coming from the reservoir arrives.

At its closest point the Goyt is much closer to the reservoir than the canal.

The flow channel from the reservoir to the canal is not large: you would not get much flow down it.

Pumping into the canal instead of the Goyt would not have been in any way a reasonable option.

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MichaelG.

Eric, thanks for the info, I don’t know the specifics of the canal in question and so logically straight to the river was the preferred option. I know that canals in general have spillways at specific locations in order to dump excess water having seen them on my travels.

Dave W

Lots of things have been done by cheapskate methods, including that dam. Long term, they should rebuild it properly from the ground up in massive rocks which cannot be dissolved/washed away like mud.Fill gaps with concrete, job done and 'everlasting.'

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I think that, eventually, they are much more likely to drain it and build houses.

MichaelG.

Where are Dams built like this not a construction i have heard of?

Steve

I've done some more googling on why you can have a suction height more than 10m with degassed water. It seems to be analogous to the reason you can heat water to more than 100C at atmospheric pressure without it boiling. You need a nucleation site for the vapour bubbles to start to form. This is why some companies won’t allow you to heat your coffee in a microwave, get it to more than 100C and give it the slightest disturbance and it begins to boil vigorously and can scald you. I know it happens because SWMBO got caught out. In similar vein it appears you can reduce the pressure to less than zero (ie apply tension) to water at low temperature without it boiling, but only if it is degassed and has no solid impurities. This plainly doesn’t apply to most real life situations.

**LINK**

It does however apply to trees, otherwise the sap wouldn’t be able to get past 10m and we wouldn’t have giant redwoods which can be 100m tall. Perhaps tree sap has something in it which inhibits bubble formation. The measured 'tensile strength' seems to be about 33MPa

**LINK**

but I still object to that use as the water is clearly not in uniaxial loading. For Imperialists, 33 MPa is about 2 tons/sq.in

I'd suspect that in the case of trees there isn't a single 100m channel being sucked on. There's lots of cross linking, tiny channels with capillary effects and there'll be the equivelent of pools along the way: think of a cascade series where you vacuum pump up the steps in stages from pool to pool...?

pgk

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I'm a bit closer to my comfort-zone there, Duncan

Most of the force lifting water in a tree is produced by transpiration: Water evaporates from the leaves, and the column is 'sucked' up the tree, through lots of capilliary tubes.

MichaelG.

The Victorian construction of the dam appears to be perfectly sound. It's well over a century old and even with the failure of the spillway it's remained functioning despite taking some very serious damage.

In part this will be because using a flexible, self-healing clay core is probably the best long-term construction for a dam that has to cope with movement or even earthquakes.

What failed is the new 1960s spillway. It's 'everlasting' concrete slab construction appears to have been vulnerable to water getting between and then under the slabs so the eddies washed away the supporting soil.

Don't blame the Victorian engineers!

Neil

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**LINK**

https://www.scientificamerican.com/article/how-do-large-trees-such-a/

quote above : "The Victorian construction of the dam appears to be perfectly sound. It's well over a century old and even with the failure of the spillway it's remained functioning despite taking some very serious damage."

The above is something I agree with, although I am not a dam or construction expert and I have only seen the broadcast pictures. Local residents are saying things like "we were saved from an imminent collapse". Who ever thought it was about to give way? There were no reports of water penetration, which normally precedes a collapse.

Certainly any consulted engineer would have to report that its condition was weaker than before the overspill, and that it might give way if more water came over the top and removed a substantial amount of the soil wall. I suspect that liability and risk management then took over and the various agencies all stated that it was in danger of imminent collapse with the need for evacuation.

It will be interesting if any reports appear from any construction expert regarding how much soil wall had been removed and how much weaker it then was, with the full head of water behind it.