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Article on water transfer plan utilising the Grand Union Canal


rgreg
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12 minutes ago, Loddon said:

Some of those are old plans discussed 25 years ago.

Severn to Thames

Transfer down the GU

 are two that I remember being mooted.

Nothing new really

 

Perhaps not, but may have increased interest now due to the focus on climate change. 

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The Severn to Thames one there were plans to do it in a pipe and it was pointed out that restoring the canal would be a cost effective way of doing it and there would be the benefit of the restoration.

Not sure what happened in the end I assume it was shelved.

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ALL these water transfer schemes falter when the through-life cost of pumping the water up to the summits in the volumes needed is worked out.

There is also usually a secondary problem when the flow rate and water speed needed through bridges is looked at.  It is frequently high enough to mean an end to boating on the canal.

The Llangollen is often used as an example of a successful water transfer scheme  but that is downhill all the way and, in the scheme of things, transfers piddly amounts of water. Fortunately, or Chirk and Ellesmere tunnels would take even longer uphill than they do now.

N

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54 minutes ago, Loddon said:

The Severn to Thames one there were plans to do it in a pipe and it was pointed out that restoring the canal would be a cost effective way of doing it and there would be the benefit of the restoration.

Not sure what happened in the end I assume it was shelved.

I think its still on the books and the water companies were told to go and look again. Its understandable, if the water comes through a pipe you have full control, if it comes along what could be a very dirty canal belonging to someone else its another story.

 

Just looked at the web but havent read the details https://www.cotswoldcanals.org.uk/2018/03/20/water-transfer-latest-update-call-to-action/

 

Edited by ditchcrawler
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43 minutes ago, BEngo said:

ALL these water transfer schemes falter when the through-life cost of pumping the water up to the summits in the volumes needed is worked out.

There is also usually a secondary problem when the flow rate and water speed needed through bridges is looked at. 

 

A canal channel cross section is an order of magnitude greater than that of a pipeline. So if canal transfer results in unacceptable speeds for boating, what is the water flow speed in a pipe?

 

The costs of pumping up lock flights is an issue, but pipelines also have to be pumped to overcome frictional losses, particularly if flow velocities are as high as you imply. So I'm not sure how the energy requirement in each case differs.

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1 hour ago, David Mack said:

 

A canal channel cross section is an order of magnitude greater than that of a pipeline. So if canal transfer results in unacceptable speeds for boating, what is the water flow speed in a pipe?

 

The costs of pumping up lock flights is an issue, but pipelines also have to be pumped to overcome frictional losses, particularly if flow velocities are as high as you imply. So I'm not sure how the energy requirement in each case differs.

The water flow speed in a pipe can be as high as you like.  There are no boats so it only matters for things like pumping costs,  coating erosion and water hammer on valve closing.

 

The energy requirement would not much differ if the pipeline was alongside the canal.  But pipelines can take more direct routes and overcome hills by boring/tunneling.  That increases capex àbut saves opex.

 

The Thames Water ring main round London seems to be about the biggest pumped pipeline scheme and that is small scale compared with shifting water from oop North to down Sarf. The Welsh, Lakes and Peak District reservoir pipelines I think are all powered by gravity.

 

Now, if you were to look at Mr. Pownall's plan for a contour canal, you might be cooking on charcoal.  That, IIRC,  included water transfer in its capabilities.

 

N

Edited by BEngo
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8 hours ago, BEngo said:

if you were to look at Mr. Pownall's plan for a contour canal, you might be cooking on charcoal.  That, IIRC,  included water transfer in its capabilities

 

Boris Johnson once mentioned it as something worth building.  Shame he went for HS2 instead as one of his vanity projects.  

 

I'd love to see the grand contour canal built, if only because we consider the 300 foot level to be home waters!

 

 

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19 hours ago, BEngo said:

The water flow speed in a pipe can be as high as you like.  There are no boats so it only matters for things like pumping costs,  coating erosion and water hammer on valve closing.

 

The energy requirement would not much differ if the pipeline was alongside the canal.  But pipelines can take more direct routes and overcome hills by boring/tunneling.  That increases capex àbut saves opex.

 

The Thames Water ring main round London seems to be about the biggest pumped pipeline scheme and that is small scale compared with shifting water from oop North to down Sarf. The Welsh, Lakes and Peak District reservoir pipelines I think are all powered by gravity.

 

Now, if you were to look at Mr. Pownall's plan for a contour canal, you might be cooking on charcoal.  That, IIRC,  included water transfer in its capabilities.

 

N

The Thames Water Ring main is run under gravity not pumped, The only pumping is from the tunnel up to ground level at distribution points

 

 

Edited by Tim Lewis
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There are technical problems but not the ones most people think. Flow can be increased (or velocity eased depending on how you look at it) with short run culverts at pinchpoints and, wait for it, dredging to the original depth :o One problem for the Llangollen is that it is a small canal to start off with, and badly dredged to boot. 

Restoring a canal is generally an order of magnitude less in cost terms compared to a pipeline. Plenty of cash left over for peripherals like dredging and fixing leaks. 

The biggest problem is expected to be water quality, not from run of the mill industrial contaminants, but eutrophication and all the other water courses that end up in a canal carrying everything from decaying rat flesh to discarded pharmacuetical. 

Of course flow CAN be an issue, a few years ago I saw a presentation at the world canals conference regarding irrigation canals in Tucson (I think) and how they had become focuses for community activity but not boating as they flowed at around 4mph. When asked why not pipe them the guy commented that a pipe the same guage had greater friction and far greater maintenance issues. 

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