Dam Solution?

[mark costello 1Participant @markcostello1]

Water being discharged from a pipe gave Me the idea of, why not have a generator hooked up to supply electricity to run other pumps? Might help on remote locations. Lights to work at night, cook meals etc….

[Ian PParticipant @ianp]

Posted by mark costello 1 on 06/08/2019 23:53:55:

Water being discharged from a pipe gave Me the idea of, why not have a generator hooked up to supply electricity to run other pumps? Might help on remote locations. Lights to work at night, cook meals etc….

What you are suggesting is a sort of hydro-electric system, flowing water turning an impeller attached to a generator (well used and understood technology), however there are losses involved in generators and motors so better to use the discharging water to drive an impeller directly coupled connected to a pump. That pump will produce a flow of water from its output so that might as well be harnessed to drive another pump…. ad infinitum…

Do you realise that you have stumbled on to perpetual motion

Ian P

[John OlsenParticipant @johnolsen79199]

Going right back to Neil's original suggestion, I wonder if he has really thought it through? So OK, we know now that a big enough siphon pipe could shift enough water to help…but how does he plan to get the siphon started? I don't think any of us have a thumb big enough to block the end of the immersed pipe, nor would sucking on the bottom end be much fun. So it seems to me that getting the siphon started is going to need a big pump. So since you are going to need a pump anyway, why bother trying to set up a siphon?

John

[Michael HornerParticipant @michaelhorner54327]

Posted by John Olsen on 07/08/2019 05:32:37:

. So since you are going to need a pump anyway, why bother trying to set up a siphon?

John

Using a siphon would only require energy to prime it then it would run for free.

Cheers Michael

[JAParticipant @ja]

Slowly it dawns on me the difficulties with a syphon.

You will need a large diameter rigid pipe of that runs from near the bottom of the water side of the dam to the bottom of the dry side. All the joints in the pipe above the water level in the dam must be absolutely leak free otherwise the syphon fails. The pipe work will need to be restrained to prevent movement due to change of direction of the flow (restrained using the failing dam?). The water from the dam will be exhausted at the bottom of the dam instead of any side spillway. As already mentioned priming a big syphon is not easy. The time transporting and assembling such a device would be slow compared with bringing pumps from the River Severn which can just be dumped on the ground, hoses run out and started very quickly.

JA

[pgk pgkParticipant @pgkpgk17461]

Posted by JA on 07/08/2019 08:47:29:

Slowly it dawns on me the difficulties with a syphon.

You will need a large diameter rigid pipe of that runs from near the bottom of the water side of the dam to the bottom of the dry side.

Or a few hundred domestic hose pipes and one guy with good lungs to suck on them in turn…and a big banner 'sponsored by hozelock'

pgk

[Michael GilliganParticipant @michaelgilligan61133]

I thought I had found a helpful explanation of the syphon/siphon here: **LINK**

https://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20080512104921

…bur I'm struggling to comprehend this statement:

[quote]

Moreover, the pressure of water in a sealed pipe decreases with altitude, so the higher you look in that pipe, the less pressure potential energy you'll find. Because of this pressure effect, the total potential energy (gravitational plus pressure) of water in a closed pipe doesn't change, even as that water rises a short distance upward inside the pipe!

[/quote]

Two nations separated by a common language ? … or am I just being thick ?

I will have some coffee !!

MichaelG.

[Martin KyteParticipant @martinkyte99762]

Posted by julian atkins on 06/08/2019 23:51:46:

I don't know why the canal system hasn't been used to drain the reservoir.

Cheers,

Julian

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JA on 07/08/2019 08:47:29:

.

[….] The time transporting and assembling such a device would be slow compared with bringing pumps from the River Severn which can just be dumped on the ground, hoses run out and started very quickly.

JA

 

.

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.

.

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

[duncan webster 1Participant @duncanwebster1]

Posted by Michael Gilligan on 06/08/2019 21:42:09:

Posted by duncan webster on 05/08/2019 19:53:41:

Ah but, if you just have a syphon, once it empties the dam down to the level of the intake it will suck air and stop working, so you either need an air pump to re-prime the system, or a valve to stop the flow before it gets too low.

Also, the dam is 24m deep (to the water level, never mind the extra height of the wall), so you can't empty it with a syphon anyway

.

I'm not suggesting it would be a practical idea, Duncan … but I'm struggling to understand your assertion.

Please look at the elevation profile that I linked on the 'What did you do today …' thread when it all started.

[quote]

See the Google Earth & Elevation composite on this BBC page:

**LINK**

[/quote]

MichaelG.

.

Edit: or check the contours on the OS Map

Edited By Michael Gilligan on 06/08/2019 21:57:02

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by duncan webster on 07/08/2019 10:12:50:

[ … ] we've already been into why you can't syphon more than 10m or so (unless you have degassed water and a laboratory).

.

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.

[JAParticipant @ja]

Posted by Michael Gilligan on 07/08/2019 09:11:38:

I thought I had found a helpful explanation of the syphon/siphon here: **LINK**

https://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20080512104921

…bur I'm struggling to comprehend this statement:

[quote]

Moreover, the pressure of water in a sealed pipe decreases with altitude, so the higher you look in that pipe, the less pressure potential energy you'll find. Because of this pressure effect, the total potential energy (gravitational plus pressure) of water in a closed pipe doesn't change, even as that water rises a short distance upward inside the pipe!

[/quote]

Two nations separated by a common language ? … or am I just being thick ?

I will have some coffee !!

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JA on 07/08/2019 11:11:35:

[…]

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.

.

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.

[duncan webster 1Participant @duncanwebster1]

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

[SamsarandaParticipant @samsaranda]

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

[Eric SinclairParticipant @ericsinclair96776]

Posted by Samsaranda on 07/08/2019 13:59:44:

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.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Eric Sinclair on 07/08/2019 15:18:34:

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.

.

.

MichaelG.

[SamsarandaParticipant @samsaranda]

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

[DMBParticipant @dmb]

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.'

[Michael GilliganParticipant @michaelgilligan61133]

Posted by DMB on 07/08/2019 15:41:25:

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.'

.

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

MichaelG.

[S.D.L.Participant @s-d-l]

Posted by DMB on 07/08/2019 15:41:25:

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.'

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

Steve

[duncan webster 1Participant @duncanwebster1]

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

[pgk pgkParticipant @pgkpgk17461]

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by duncan webster on 07/08/2019 16:33:03:

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

.

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.

[Neil WyattModerator @neilwyatt]

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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