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Tring Summit closure


koukouvagia

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I am assuming that it would involve reinforced concrete, and deep anchor piles to stop the channel floating up when the water table rises?

Assuming the water levels, in the trough, are maintained higher than the water table, then there is no way it could float.

 

The far greater risk would be that the water table continues to fall and the ground beneath subsides.

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There are about 3 miles ot Tring Summit, and adding the navigable bit of the Wendover Arm makes it more like 4.5 miles of continuous water.

 

Given they haven't even yet been able to establish a dam at one single "narrow" on the length, my guess is they have very little way of knowing which bits of that length are actually contributing most to the current water loss.

 

Clearly lining it throughout would be a massively costly exercise, and any initiative would somehow have to concentrate on shorter lengths considered to deal with a large percentage of the losses ?

 

It surely doesn't have to be concrete lined, necessarily, or at least not with solid concrete ? Where new parts of the Wendover arm are being worked on, (that was always a heavy water loser on some stretches), the solution is a membrane, covered over by blocks, that I don't think use any more than gravity to (hopefull!) stay put. I suspect there may be a number of options if cost (and length of outage) were no object, but in the current climate, I can't see any of them being funded.

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I suspect there may be a number of options if cost (and length of outage) were no object, but in the current climate, I can't see any of them being funded.

 

Then that may mean that the Grand Union link, between South and North, may be severed permanently.

 

The Oxford is going to get mighty busy, if that is the case....

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Then that may mean that the Grand Union link, between South and North, may be severed permanently.

 

The Oxford is going to get mighty busy, if that is the case....

Briefly, yes - until excessive water use leads to dramatic falls in water levels and BW close that as well! We had better all head down the K&A and whoop it up with the CMs while we still can.

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Briefly, yes - until excessive water use leads to dramatic falls in water levels and BW close that as well! We had better all head down the K&A and whoop it up with the CMs while we still can.

The oxford summit operated for most of last Summer at low levels. It is a contour cut canal so shouldn't suffer from the problems that the Tring summit is currently experiencing.

 

As long as the Napton back pumps continue to operate it should remain open but with very restriced time scales (see the posts in the Oxford Summit topic: link)

Edited by Proper Job
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There are about 3 miles ot Tring Summit, and adding the navigable bit of the Wendover Arm makes it more like 4.5 miles of continuous water.

 

Given they haven't even yet been able to establish a dam at one single "narrow" on the length, my guess is they have very little way of knowing which bits of that length are actually contributing most to the current water loss.

 

Clearly lining it throughout would be a massively costly exercise, and any initiative would somehow have to concentrate on shorter lengths considered to deal with a large percentage of the losses ?

 

It surely doesn't have to be concrete lined, necessarily, or at least not with solid concrete ? Where new parts of the Wendover arm are being worked on, (that was always a heavy water loser on some stretches), the solution is a membrane, covered over by blocks, that I don't think use any more than gravity to (hopefull!) stay put. I suspect there may be a number of options if cost (and length of outage) were no object, but in the current climate, I can't see any of them being funded.

 

Alan,

 

This is basically what they have done in part on the Wendover arm. The part newly opened was worked upon when empty, bentomat was laid and this covered with concrete with re-inforced concrete sides. An expensive option.

 

The lenghts currently being worked on are again dry beds, re-profiled and lined with bentomat with concrete blocks laid (blocks strenghtend with concrete infill). This is necessary to give the banks protection from boat chines. Mooring laybys are constructed using the method pioneered on the section renewed and already in water.

 

Extensive tests were carried out to check for leaks before the section from Tringford pumping station was opened and specifications for works to be undertaken by the Trust are agreed with BW first.

 

Bentomat laid unprotected would not last for long.

 

Repairs have also had to be made to the dry canal bed to cap the clay feeder pipe, then the bentomat and concrete are laid.

 

I doubt BW could afford to carry out similar works to the Tring summit and it would have to be drained.

 

It must be bourne in mind that considerable sections of the summit are piled or have similarly re-inforced sides - no piling between the ends of the long term moorings at Cowroast to Tring station, no piling on the off side beyond Marshroft bridge to Bulbourne bridge and no piling on the Wendover Arm (except renewed sections) so initially these sections must be suspect - or the bottom of the canal must be causing the problem.

 

Mike

 

PS some good pics of the restoration works on the Wendover Arm Trust website - Restoration section.

Edited by LEO
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The oxford summit operated for most of last Summer at low levels. It is a contour cut canal so shouldn't suffer from the problems that the Tring summit is currently experiencing.

 

Yes, I was there too! But it did NOT operate much of the time, that's my point - the Claydon flight was open only four hours per day for several weeks. That was with its normal traffic - add on the projected extra GU Deviation traffic and there could be a much more severe shortage this year than last

Why does its being a contour canal make a difference? It's not as if it's flat all the way, there are quite a few locks along it.

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Hi,

 

Whilst looking through the Wendover Arm Trust's website I was reminded that in 2003 the Trust made an important archive discovery - records of water flow from the Wendover Springs had been kept and gave details of flow rates from 1841, presumably to the present day.

 

The metering equipment may be housed close to what would have been the Wharf in Wharf Road, Wendover.

 

The Wendover Springs are the result of water drainage from a large area of the Chilterns, several flow freely, one at least is contained in a small reservoir (a recent announcement says that fishing is no longer permitted in this pond (Hampden Pond) due to low water levels).

 

Water from the Springs then flows down through Wendover and into the Canal, eventually ending up in Wilstone reservoir.

 

Presumably BW have these records, or the benefit of modern day ones so sub ground water availability can be checked.

 

The Wendover Springs have shown a steady flow over the years, it will be interesting to see if this has changed.

 

The Wendover Gap through the 'Chalky' Chilterns is the next one west from the Tring gap, through which the GU canal runs.

 

Unlike the Tring Gap, the water to the Wendover Springs is not affected by extraction for domestic puposes. The only extraction plant is, like the one at New Mill (Tring Gap) on the escarpment of the Chilterns (ie the slope down towards London) at the Dutchlands summit ( a point well know by railway men).

 

It might be of interest to see if Jeff Wyatt has access to or info relating to this metering at Wendover.

 

Leo.

Edited by LEO
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So, presumably, if it rains from now until the start of the tourist season, there will be sufficient water for a few weeks, assuming the canal sides are not leaking even worse, due to them drying out.

 

What happens if we have another dry summer, then autumn and we are back here, in a worse state, next January?

 

Are there any long term plans to seal the canal bed or are we looking at a long term cutting off of the North from the South of the system?

 

This "make do and mend", long term, appears to be a "make do and make worse".

 

Which is exactly why situations like this show that the transition trustees need to walk if they cannot achieve more than £39M per year (that currently is not indexed). Unless of course you take the contracts management on Carl :help:

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I walked by the resovoirs at Tring yesterday. The sight of all the empty pounds was a very sad thing to see. Hardly a drop of water at all.

 

I was wondering about the fish. Where would they have gone? There was almost no sign of life of any sort, just a few fresh water mussels, no plants just mud and rubber pipe fenders.

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I walked by the resovoirs at Tring yesterday. The sight of all the empty pounds was a very sad thing to see. Hardly a drop of water at all.

 

I was wondering about the fish. Where would they have gone? There was almost no sign of life of any sort, just a few fresh water mussels, no plants just mud and rubber pipe fenders.

I daren't go and look, I would be gutted.

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I walked by the resovoirs at Tring yesterday. The sight of all the empty pounds was a very sad thing to see. Hardly a drop of water at all.

 

I was wondering about the fish. Where would they have gone? There was almost no sign of life of any sort, just a few fresh water mussels, no plants just mud and rubber pipe fenders.

 

The Tring Anglers did a fish rescue before the pound was lowered.

 

 

P1090079-1.jpg

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Am I missing something with all this talk about leakage through the top foot of the bank when it has dried out?

 

As I understand what's been said here, the Tring Summit is unlined. That is because the water table is normally above canal water level (makes sense, I've seen small springs flowing into the canal along there). In normal circumstances lining the pound would make no sense because, if there were no lockage, there's a net inflow of water.

 

Most canals are lined with clay puddle. If that dries out it tends to leak. Therefore lowering the water in a puddled pound would result in greater leakage when the level returned to normal. That much I understand.

 

But what difference does it make where the canal is unlined, provided the water table returns to its normal level in due course? Once ground water is above the level of the canal, the status quo ante is restored and there is a net inflow. That would be the case even if drying out had resulted in leaks opening up. (If there's no clay puddle, would additional leaks open up anyway? Not that it matters in that scenario.) Reinforcing that thought is my belief (please correct me if I'm wrong) that the summit is cut through chalk - a highly porous material, which will allow water to pass quite freely whenever there's a difference in level.

 

If my thinking is correct, the talk (from Geoff Whyatt in the first instance?) of increased leakage when the water level is restored is a complete red herring, unless it's anticipated that the water table will remain below canal level for some time to come.

 

So is there anyone out there who can clarify this?

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I walked by the resovoirs at Tring yesterday. The sight of all the empty pounds was a very sad thing to see. Hardly a drop of water at all.

 

I was wondering about the fish. Where would they have gone? There was almost no sign of life of any sort, just a few fresh water mussels, no plants just mud and rubber pipe fenders.

I'm confused, I thought from post 393 yesterday BW were saying, yesterday, they were 47% full?

 

The Tring group of reservoirs benefited by a net inflow of 52 ML last week – without the actions taken locally this would have been only 22ML

 

As we stand the Tring reservoir group are holding 47% of their maximum capacity – this time last year it was 63%

 

From a water ‘consumption’ perspective :-

- We avoided drawing any water from the reservoirs : (last week presumably)

 

Can anyone help me out of my confusion?

 

Mick

Edited by zodiak
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I'm confused, I thought from post 393 yesterday BW were saying, yesterday, they were 47% full?

 

The Tring group of reservoirs benefited by a net inflow of 52 ML last week – without the actions taken locally this would have been only 22ML

 

As we stand the Tring reservoir group are holding 47% of their maximum capacity – this time last year it was 63%

 

From a water ‘consumption’ perspective :-

- We avoided drawing any water from the reservoirs : (last week presumably)

 

Can anyone help me out of my confusion?

 

Mick

Yes, he was talking about the canal (The sight of all the empty pounds was a very sad thing to see) not the reservoirs.

 

Ian

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Am I missing something with all this talk about leakage through the top foot of the bank when it has dried out?

 

As I understand what's been said here, the Tring Summit is unlined. That is because the water table is normally above canal water level (makes sense, I've seen small springs flowing into the canal along there). In normal circumstances lining the pound would make no sense because, if there were no lockage, there's a net inflow of water.

 

Most canals are lined with clay puddle. If that dries out it tends to leak. Therefore lowering the water in a puddled pound would result in greater leakage when the level returned to normal. That much I understand.

 

But what difference does it make where the canal is unlined, provided the water table returns to its normal level in due course? Once ground water is above the level of the canal, the status quo ante is restored and there is a net inflow. That would be the case even if drying out had resulted in leaks opening up. (If there's no clay puddle, would additional leaks open up anyway? Not that it matters in that scenario.) Reinforcing that thought is my belief (please correct me if I'm wrong) that the summit is cut through chalk - a highly porous material, which will allow water to pass quite freely whenever there's a difference in level.

 

If my thinking is correct, the talk (from Geoff Whyatt in the first instance?) of increased leakage when the water level is restored is a complete red herring, unless it's anticipated that the water table will remain below canal level for some time to come.

 

So is there anyone out there who can clarify this?

Probably the information we are missing, (well I certainly am!), is what bits of the entire 4.5 miles from Cow Roast lock to Marsworth TOP, and then down the navigable Wendover arm to Little Tring, are in the category of "unlined, because we expect net water in not out".

 

Whilst I can well imagine much of the deep dug out cutting itself is in this category, I would be far less certain that the bits not in a cutting, (and certainly bits of the Wendover arm), are actually designed for "inward leakage". I would suggest it is highly possible, (although I don't know), that quite a bit of this is just normal puddled canal, that even with the water tables at more normal level, would leak "outwards" not "inwards" if there was no puddle.

 

If that's the case, is there not a strong possibility that the puddle (where any does exist) will dry out and crack, so at least those bits are leaking worse, if the water is ever put back.

 

It isn't just us "armchair theorists" who have this concern. The BW chaps that actually work on the length think de-watering it will cause more water loss later. So apparently does the chap who was BW's former expert on water control on the summit.

 

Perhaps those discussing with BW management can ask which bits are puddled, which are not, and if they are concerned about possible effects of lowering levels in the puddled bits ?

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Probably the information we are missing, (well I certainly am!), is what bits of the entire 4.5 miles from Cow Roast lock to Marsworth TOP, and then down the navigable Wendover arm to Little Tring, are in the category of "unlined, because we expect net water in not out".

 

<snip>

 

If that's the case, is there not a strong possibility that the puddle (where any does exist) will dry out and crack, so at least those bits are leaking worse, if the water is ever put back.

 

<snip>

 

Perhaps those discussing with BW management can ask which bits are puddled, which are not, and if they are concerned about possible effects of lowering levels in the puddled bits ?

Thanks for this, I'd perhaps been taking over-literally the comments about the section being unlined. Now that's cleared up (well at least the principle of the thing) it would be good if we can clarify just what the situation really is; I second your request.

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I moor in the pound at the bottom of the Marsworth flight and went upto the boat this morning...expecting the pound to be down and the boat aground...but no it was afloat . The pound was down a bit but not drastically different from norm. Just wondering whether BW is pumping water into the pound to keep boaters there afloat.

In another thread I talked about problems starting the engine and spent this morning with a friend trying to work out why the engine was difficult to start....could it be the battery....could it be a fuel problem...could it be the glow plugs need replacing...well we started on the glow plugs...there was no current in them and then we realised there was no wire attatched to them...found the wire (which had been removed ealier in the year when the engine was taken out to replace a gearbox) re-attatched the wire...and the engine started first time!!

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Hi, Water situation sat 28th Jan

 

Leakage through Cowroast Lock - pictured 22 Jan.

Cowroastlowwater001.jpg

 

The water level below the lock is going down, this water inlet in the lock was about 250mm below the water line at the start of the week

005.jpg

 

Boats in the pound below the lock are aground

014.jpg

 

Bw have maintained the summit at this level for a week (plan B not put into action).

006.jpg

 

Leo.

Edited by LEO
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I was at the other end of the summit today, at Bulbourne, and walking down the Marsworth flight.

 

Too late to sort any pictures out tonight.

 

The gates and paddles on the top Marsworth lock are remarkably watertight, very little leakage there. (Yes, I know that's not the problem, but nice to see the gates that were replaced there not long back are really very good.)

 

About the top three pounds of the flight are more or less completely drained down.

 

As you get further down there is a bit more water about, but even the bottom "long" pound is down a good 2 feet.

 

It all looks very sad indeed!

 

If I have time I'll upload some pictures tomorrow.

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I see on Narrowboat World that the reservoirs are full, where did all the water come from?

They are idiots, basically!

 

I have never, ever, see the reservoirs look more sorry for themselves at this time of year.

 

They have managed to picture the only one of the group, (and probably one of the smallest ?), that is at anything approaching a sensible level.

 

The one alongside is exceedingly low, as is Wilstone reservoir.

 

There's no hope, really.

 

Dear old NBW - never let the truth get in the way of a good story!

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