Tring Summit closure

[sheriff]

Frozen in at tescos, where you?

I was on coal from little venice to bulls bridge...not frozen in at tesco..moored where the parakets are in the mobile mast....not frozen here.some section are near me...

Edited January 17, 2012 by sheriff

[LEO]

Today's very boring New Ground Bridge stop plank pictures!

 

Plastic sheeting added to Cow Roast side,(sort of!....)

Comparing to yesterday's pictures, I would say it has dropped by less than an inch since then, (both sides, as I don't think there was any level difference either day).

 

Alan,

 

Looks to me as though the level has dropped by about 1 course of bricks, counting from the bottom of the lower course of engineering bricks.

 

M

[alan_fincher]

Alan,

 

Looks to me as though the level has dropped by about 1 course of bricks, counting from the bottom of the lower course of engineering bricks.

 

M

Not between the two days where I have taken pictures, I think Mike.....

 

The original ones were taken on Cath's phone, but I have tried to crop part out of one.......

 

Sunday at 2:30 PM

 

 

Monday at 5:30 PM

 

 

I still don't think it is even as much as 1 inch.

[alan_fincher]

Someone with greater mathematical ability than mine ought to be able to predict how far the canal will have dropped if it loses water at the rate of 60 megalitres a week. It's a bit like those O level maths problems that I used to struggle with in the dim and distant past:

 

"If a tank of water 4.13km long and 5m wide loses water at the rate of 60 megalitres a week, how long will it take to lower the level by 400 cm?"

 

Will it take days/weeks to drop the level?

[EDIT: "Batavia" has pointed out first critical error in my maths, so now reworked - any more, please ?]

 

Well I'd say it's more realistic, including the arm to say it is.....

 

4.5 miles = 7,200 metres approx in "new money)

Average 30 feet wide = 9 metres approx

Plan to drop (max) 0.4 metres.

 

So that is 72,000 x 9 x 0.4 cubic metres = (about) 26,000 cubic metres = 26 mega litres.

 

26 megalitres at 60 megalitres per week should therefore drain out in around 3 days. (Not quite the 4.3 weeks I made it initially with decimal place in wrong place!)

 

Go on - someone show where I have decimal point in the wrong place!!

[EDIT: Ho! Ho! - Someone just did!]

 

EDITED:

 

I added something to the above, but on reflection wish to completely change it!

 

Thinking some more, I actually think, if you believe BW's version of events, that despite (hopefully) answering the above calculation, as requested by Koukouvagia, it is based on false logic!

 

The current rate of leakage is supposed to be 60 megalitres a week, but the argument goes that most of the water is leaking out through the top 300 to 400 mm of bankside, and much less so lower down.

 

So follow that logic through, by the time the level is dropped 300 to 400 mm, much of the leakage should be stemmed, and be massively less than 60 megalitres a week.

 

So when it is (say) "half-dropped", the rate of leakage should be far less, say possibly around 30 mega litres a week.

 

So I've now changed my mind about any validity in such a calculation, other than "rate of fall right now".

 

At current claimed rate of leakage it could go down 400 mm in just 3 days, but in practice, if that rate slows right down, it will not have dropped that far in that time, and should actually reach a point where it is draining very much slower.

 

So I now don't think you can answer Jim's question, unless you start making assumptions about what percentage of the leakage is taking place at various depths below water level, can you ?

 

YET ANOTHER EDIT:

 

If I'm now right, and at current rates of leakage, it would go dowmn in just 3 days, then I would say that either it isn't leaking at 60 mega litres a week, or that those planks are not actually working much at all.

 

I wonder if they are actually sat on a couple of fridges, rather than the bottom!

Edited January 17, 2012 by alan_fincher

[Batavia]

4.5 miles = 72,000 metres approx in "new money)

 

Ahem! Decimal point trouble?

 

Chris G

[alan_fincher]

Ahem! Decimal point trouble?

 

Chris G

Did well, didn't I!

 

I knew I should not have attempted at this time of morning!!

 

Will start to correct, but eagerly await my next mistake!

[LEO]

Did well, didn't I!

 

I knew I should not have attempted at this time of morning!!

 

Will start to correct, but eagerly await my next mistake!

 

Ok, so the class 'swots' live in Berko!, I guess you will also have to feed into the equation the reduced dimentions of the Wendover Arm, not nearly so wide or deep..

 

From what I experienced over recent weeks, I guesstimate it will run down in about 4/6 days.

 

L.

 

Not between the two days where I have taken pictures, I think Mike.....

 

The original ones were taken on Cath's phone, but I have tried to crop part out of one.......

 

Sunday at 2:30 PM

 

 

Monday at 5:30 PM

 

 

I still don't think it is even as much as 1 inch.

 

 

Alan,

 

But bear in mind BWs pumping activities yesterday..

 

M

[alan_fincher]

But bear in mind BWs pumping activities yesterday..

 

M

Yes, but if those planks are sealing, then BW pumping water in on the Cow Roast side should not be helping to keep the level up on the Bulbourne side, (the one in the pictures),bshould it !

 

If those planks are not working now, what will suddenly make them ?

 

I guess you will also have to feed into the equation the reduced dimentions of the Wendover Arm, not nearly so wide or deep..

Well the depth only enters into it if you consider bits where it is less that 400 mm deep at the bank, so the canal starts to narrow as you lower it.

 

I would contend there is actually more places like that on the main line than the arm, actually, (thinking about areas around Marshcroft "high" bridge, where waters lap the non-towpath side a bit like a beach!)

 

I went for 30 feet, rather that Jim's much less generous 15 metre wide suggestion, because in many places if the water were deep enough, Sickle, at 40 feet, could be turned on the summit.

 

Admittedly you would struggle to find anything like that width that could be safely used, but it's not physically as narrow as many think, along much of it's length.

 

Don't forget the wides near the buffer depot, and at Bulbourne. Perhaps 25 feet average might be better ? That would change the 3 day calculation to about 2.5 days.

Edited January 17, 2012 by alan_fincher

[Timleech]

 

 

If those planks are not working now, what will suddenly make them ?

 

It'll need water to be removed from or added to one side at a rate which is enough to show up leakage, so that they can then attempt to seal that leakage. How quickly water needs removing/adding to do this will very much depend upon the area of leakage.

 

Tim

[alan_fincher]

It'll need water to be removed from or added to one side at a rate which is enough to show up leakage, so that they can then attempt to seal that leakage. How quickly water needs removing/adding to do this will very much depend upon the area of leakage.

Yes,

 

I'm not claiming any great knowledge, but from what I have seen of planks in over the years, this looks not to be the best chances of forming a good seal I've ever seen!

 

I guess it is a very, very, long while since anybody tried to use this point to stank the canal, and I'll admit it's hard to see how they could fully repair any shortcomings to the grooves and what the planks need to bed down onto, without draining the entire summit.

 

I'm not expecting to pass near there again for a few days, but when I do, I'll try and keep taking pictures.

[Batavia]

So that is 72,000 x 9 x 0.4 cubic metres = (about) 26,000 cubic metres = 26 mega litres.

 

Agreed.

 

At first glance, your initial result looked sensible - I am currently working on the design of a fuel storage depot which has some 60,000 m3 tanks (about 60 m dia x 20m high) and it is difficult to visualise that the contents one of these could fill the summit level to a depth of about 0.9m!

 

 

Chris G

[debbifiggy]

Yes,

 

I'm not claiming any great knowledge, but from what I have seen of planks in over the years, this looks not to be the best chances of forming a good seal I've ever seen!

 

I guess it is a very, very, long while since anybody tried to use this point to stank the canal, and I'll admit it's hard to see how they could fully repair any shortcomings to the grooves and what the planks need to bed down onto, without draining the entire summit.

 

I'm not expecting to pass near there again for a few days, but when I do, I'll try and keep taking pictures.

 

Update released this morning to BW boating and trade customers:

 

Tues 17th Jan

 

Summary of current status :-

- Action plan communicated to customers via Waterscape, meetings and letter drop to many boats moored in the affected area ( Sat 7th – Mon 9th Jan )

- Boats allowed to move from affected area on specific days last week including Saturday.

- Most boats have chosen to leave the affected area.

- Planks were installed last Thursday.

- The pound is now down 330mm. We have switched on the Cowroast (borehole) pump to bring the level up in the ‘marina’ section of the canal. It is our intention to now seal (rack up) the planks to enable the Cowroast section of the pound to maintain a differential head of water from the level on the north side of the planks.

- We intend to monitor the levels either side of the planks to establish how effective the seal on the planks is. We will also monitor the hours run per day on any/all pumps used to maintain levels.

- It is our intention to maintain the northern side of the planks at no lower than 450mm for the time being. NB – this is likely to need a feed of water to maintain this level, we will look to overpump using Cowroast borehole supply for this, where need be.

 

It is clearly too early to give indications of the water conserved from this action – we will be better placed to inform you of this next week

 

Car parking at Marsworth – the old BW yard has now been opened up as a temporary car park for displaced moorers

 

How long will these current measures continue ?

 

I recognise that this is a question that is concerning many.

If reservoir savings that result are meaningful then possibly throughout February – it is too early to speculate any further than this.

We will share results by way of this weekly update and take a view in consultation with the Trade and boaters who are directly affected

 

Many thanks

 

Jeff Whyatt

 

I will post any further updates as I receive them.

D

[beardshave]

As a moorer in the Cowroast Lagoon I was worried by a report on the Waterways World website that the situation is much worse than hitherto announced.

 

"The stop planks are going in at Northmoor Top Lock ........... and at Marsworth Bottom Lock (No. 39, near Marsworth Junction) – will allow the water level to be lowered to below the upper section of the canal bank, which BW says is the section most prone to leaks"

 

As Northmoor Lock is on the Upper Reaches of the Thames this is a matter of grave concern and I do not envy Alan et al in their task of doing the maths over that area!Our sympathy and greetings to brother boaters stranded at Lechlade

 

Link http://www.waterwaysworld.com/latestpost.cgi?post=2988

[matty40s]

As a moorer in the Cowroast Lagoon I was worried by a report on the Waterways World website that the situation is much worse than hitherto announced.

"The stop planks are going in at Northmoor Top Lock ........... and at Marsworth Bottom Lock (No. 39, near Marsworth Junction) – will allow the water level to be lowered to below the upper section of the canal bank, which BW says is the section most prone to leaks"

As Northmoor Lock is on the Upper Reaches of the Thames this is a matter of grave concern and I do not envy Alan et al in their task of doing the maths over that area!Our sympathy and greetings to brother boaters stranded at Lechlade

Link http://www.waterwaysworld.com/latestpost.cgi?post=2988

 

I would say they need to use these stop planks if they are that worried about water loss.........

[alan_fincher]

Today's scintillating pictures, (about 15:00).

 

Frankly, other than the addition of the plastic yesterday, I could have reused the ones from two days ago!

 

I estimate the water level has risen about 1" on both sides of the planks, bringing it back more or less exactly to Sunday's levels

 

 

 

According to BW men who were just about to look at it, they have been pumping water in at Cow Roast again today, which is why the level is back up slightly on the whole summit.

 

They suggest it is simply flowing through and topping up the whole pound, as it is not possible to get planks to seal in a situation like this.

 

I have now spoken to more than one set of BW staff on the ground who have suggested that if they had been consulted about what was planned, they would have been happy to say what they thought the chances of success actually were, (but they were not...).

 

Perhaps I had better say no more than that, other than they were surprised that a public statement has been made that it has been intentionally dropped 330 millimetres!

[jenlyn]

All those in favour of Geoff Wyatt walking the plank say aye!

[alan_fincher]

All those in favour of Geoff Wyatt walking the plank say aye!

Apparently finding planks suitable for a specific purpose isn't that easy in these parts......

[jenlyn]

Apparently finding planks suitable for a specific purpose isn't that easy in these parts......

They should try Ivory Towers, plenty of suited-able planks there

[koukouvagia]

 

4.5 miles = 7,200 metres approx in "new money)

Average 30 feet wide = 9 metres approx

Plan to drop (max) 0.4 metres.

 

So that is 72,000 x 9 x 0.4 cubic metres = (about) 26,000 cubic metres = 26 mega litres.

 

26 megalitres at 60 megalitres per week should therefore drain out in around 3 days.

 

 

I've just spotted another correction that needs to be made. The length that's being lowered is only 4.13 km, not 4.5 miles.

[alan_fincher]

I've just spotted another correction that needs to be made. The length that's being lowered is only 4.13 km, not 4.5 miles.

Not sure about that ?

 

You are correct that with the Wendover arm included, I have inadvertently added an extra half mile! Should be about 4 miles to Little Tring Winding hole ? (My 4.5 wrongly includes the half mile it is not intended to lower).

 

Are BW saying they are planking off the arm, and not lowering that, then ?

 

There were certainly no planks in at Bulbourne Junction on Sunday afternoon.

 

4.13 KM is not far off the distance from New Ground to Marsworth top lock, I agree, but so far I have seen nothing that said that the level in the Wendover arm isn't being dropped too, (or have I !?!")

 

Certainly Leo's posts implied it was, I'd say....

 

EDIT: The calculation again if you include Wendover arm.....

 

4.0 miles = 6,400 metres approx in "new money)

Average 30 feet wide = 9 metres approx

Plan to drop (max) 0.4 metres.

 

So that is 6,400 x 9 x 0.4 cubic metres = (about) 23,000 cubic metres = 23 mega litres.

 

23 megalitres at 60 megalitres per week should therefore drain out in around 2.7 days.

 

But it has had over 2.7 days, and not dropped at all, possibly because they are still topping it up at Cow Roast ???

Edited January 17, 2012 by alan_fincher

[Timleech]

So far as I know they should have inflatable dams available for situations where there are no facilities for stop planks. I have no idea, though, whether they are any easier to seal than are stop planks in knackered grooves.

 

Tim

[ditchcrawler]

Surly if the ground is porous at the upper levels of the canal, is it not possible that as the water level rises on one side of the stop planks it just flows through the soil and into the canal the other side and maybe if they dammed the bridge hole up solidly water would still fine its way round

[alan_fincher]

And another thing, that I have felt was wrong with the initial statement, if we are trying to talk correct numbers.............

 

Cow Roast or Marsworth Top Locks.

 

Dimensions, say (between gates).....

 

Long 80 feet / 24 metres

Wide bit under 15 feet / 4.5 metres

Fall 6 feet / 1.8 metres

 

Sound about right ? (It's going to be at least that, I'd say, not less in any dimension.)

 

So volume on each lockage is about 24 * 4.5 * 1.8 cubic metres = (as near as damn it) 200 cubic metres, or 200,000 litres.

 

So 61 megalitres is surely over 300 lock fulls per week being lost through leakage, if that is the correct number in the first place. However you juggle the lock dimensions, it is certainly not as little as 220 lock-fulls.

 

OK, it doesn't actually change the losses, but they seem to be more than 25% out in that "lock-full" conversion, to my way of thinking, which is more than a rounding error.

[sheriff]

They should try Ivory Towers, plenty of suited-able planks there

your get your license revoked if your not carefull,insulting a plank of wood,(planks have many uses) frozen in now by the way.how about you

[LEO]

Not sure about that ?

 

You are correct that with the Wendover arm included, I have inadvertently added an extra half mile! Should be about 4 miles to Little Tring Winding hole ? (My 4.5 wrongly includes the half mile it is not intended to lower).

 

Are BW saying they are planking off the arm, and not lowering that, then ?

 

There were certainly no planks in at Bulbourne Junction on Sunday afternoon.

 

4.13 KM is not far off the distance from New Ground to Marsworth top lock, I agree, but so far I have seen nothing that said that the level in the Wendover arm isn't being dropped too, (or have I !?!")

 

Certainly Leo's posts implied it was, I'd say....

 

EDIT: The calculation again if you include Wendover arm.....

 

4.0 miles = 6,400 metres approx in "new money)

Average 30 feet wide = 9 metres approx

Plan to drop (max) 0.4 metres.

 

So that is 6,400 x 9 x 0.4 cubic metres = (about) 23,000 cubic metres = 23 mega litres.

 

23 megalitres at 60 megalitres per week should therefore drain out in around 2.7 days.

 

But it has had over 2.7 days, and not dropped at all, possibly because they are still topping it up at Cow Roast ???

 

Hi Alan,

 

I assumed the Wendover Arm would be dropped to the same level as the rest of the summit as no mention had been made of stop planks at Bulbourne.

 

The chances of getting a good seal the way the planks are currently fitted at New Ground is low due to the condition of the bottom of the canal.

 

Until this is resolved BW are wasting time.

 

Your pics are brill, but I can instantly judge the water level by the step down onto my boat - Small (normal), now very large (boat on bottom of canal) and the height of the top of the piling up the portholes......

 

All good fun..

 

ATB

 

Mike.