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Whaley Bridge Evacuated


furnessvale

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46 minutes ago, Mike the Boilerman said:

 

Actually Tony, if I remember my fluid dynamics from college correctly, turbulent flow is lower resistance than laminar.

 

In fact if you look at the photos/videos there are pairs of concrete nibs set all over into the spillway, presumably to break up laminar flow. 

 

 

One possibility is that the overflow created lift to the concrete slabs which may well have been designed on the assumption that they would always have a positive force towards the dam. Once lifted then the flow was probably sufficient to wash out the gap that occurred. 

 

Design failures are often the result of unanticipated conditions arising rather than insufficient consideration of known conditions.

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4 hours ago, BruceinSanity said:

In that documentary on BBC1 Canals: The Making of Britain, Liz McIvor pointed out that before Brindley, engineers were invariably military, so the new breed were “civilian engineers”, shortened to civil.

There certainly were 18th century military engineers, but they had nothing to do with canals, other than waterways associated with defence. Our canals were built by craftsmen, some better educated than others, usually the ones from Scotland. Civil engineers, capable of using formula and other calculations to design structures, were beginning to appear on the mainland of Europe from the end of the 18th century. In this country, we lagged behind significantly, with the civil engineering profession only really becoming established from the 1840s or 50s. The craftsmen of the 18th century were, in most cases, well up to the design of the civil and mechanical engineering of the time. What they could not do is design and build to the rapidly improving 19th century standards, so the Victorian era is when we started to loose our position at the head of technical development. One of the main factors was the poor take-up of the modern mathematics of the time, such as calculus, a area of knowledge which was much more advanced elsewhere in Europe. Unfortunately, during the mid-19th century we also lost sight of the skills which craftsmen did have, with our education system becoming more and more academic. This has resulted in many at the top of their profession, and not just in engineering, not really understanding what they profess to have been educated about.

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5 hours ago, David Mack said:

My guess is they will reinstate the downstream slope protection which has failed. They might also square up the side wall so that there isn't the concentration of water that results from the existing angled wall.  

They cannot square up the side wall as there is no river flowing directly away from the dam. The sidewall is angled(as previously discussed), to create a direction for the water flowing down. Although it was extreme at the bottom of the slide the other day, the turned water takes power out of the downward flow and steers the flow down the chute to the River Goyt. 

Mike is correct in his fluid knowledge, the nibs are very important to break up the downward flow. 

The experts on that article are quite illuminating, each has their own theory and each theory is different! 

There is no doubt that water ingress through plant growth, and winter frost damage with trapped water in the concrete joints will be the eventual culprit, although obviously the pictorial evidence I and others have posted corresponding with the initial failure area are not valid as we arent worthy....sorry, qualified.

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1 hour ago, matty40s said:

They cannot square up the side wall as there is no river flowing directly away from the dam. The sidewall is angled(as previously discussed), to create a direction for the water flowing down. Although it was extreme at the bottom of the slide the other day, the turned water takes power out of the downward flow and steers the flow down the chute to the River Goyt. 

Are you guessing, or do you have specific knowledge of this?  A few angled concrete diverters at the foot of the spillway could do that, if it is necessary, without creating unnecessary turbulence and a concentration of flow against the side wall.

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2 hours ago, mayalld said:

 

 

"As an All Reservoirs Panel Engineer I would say that there is nothing in the photos that would cause me concern, and nothing that would indicate that the dam is not being maintained properly in general"

 

Make of that what you will....

 

 

I would agree that vegetation growing on the spillway, presumably with the roots bedded in the joints between the slabs, should not be a major concern.  I believe it will be shown that there may have been voids beneath the slabs that developed over the life of the concrete spillway because it was never possible to properly compact the substructure (gravel fill?).  Such voids would not have been observed during routine 'maintenance' and inspection without using sophisticated sonic techniques.  Vegetation roots would tend to stabilise the soils beneath the slabs, not erode them.

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2 hours ago, Mike the Boilerman said:

 

Not having a degree in the subject, I'm not allowed to discuss it :giggles::giggles::giggles:

 

 

We used to deal in coulds and mights. Its great. If you absolutely said something would happen it didnt, if you said it might it would.

My reports used to have so many caveats, they looked like a used car warranty.

Didnt keep me out of court though.:

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3 hours ago, Mike the Boilerman said:

 

Not having a degree in the subject, I'm not allowed to discuss it :giggles::giggles::giggles:

 

 

 

3 hours ago, Tony Brooks said:

Me neither !!!

 

2 hours ago, Tony Brooks said:

and so it goes on but it appears only degree holders who know about dams should be allowed to comment CaRT's maintenance procedures.

I'm not saying it cannot be discussed (Nor commented on) I'm saying that in this thread alone I've seen 3 or 4 theories all different.  Until some kind of investigation has taken place its mostly just theory and what people think. But with only 3 posts I'm not sure I'm allowed to say more.  

 

Already the post above mine says the vegetation was of no major concern.    

 

And no, i don't work for CART.  I've just tired of the incessant theorising.   I will say that the vegetation seen on that spillway would not restrict water flow greatly - should it have been there, probably not - i don't know I've only got 4 posts now.

 

Edited by Dustin Wright
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Having just watched the interview from Newsnight I think Richard did well not to tell Emma to do one and from some of the comments in this thread I'm not sure everybody is watching the same interview.

Regarding funding Richard said that there was sufficient funds for resorvoirs, there was no mention of whether there was adequate funding to maintain the entire canal network.

 

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Might as well shut the forum down if we can't state our views and have an opinion. Any pending investigation will be interesting, but likely no more accurate than the opinions on here.

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Pictures emerged today of the dam wall three years ago, which has raised questions about the maintenance of the concrete panels on the spillway. Vegetation is growing through it, leading one engineer to speculate over historic harm to the 180-year-old structure. Dr Mohammad Heidarzadeh, an assistant professor at Brunel University, said the vegetation on the 2016 video taken from a drone indicated likely gaps between the panels where water could have swept in, making the damage worse. He said: ‘That could be the whole problem right there. ‘The spillway needs to be kept sealed and clear of these kind of weeds and plants.’ The reservoir is maintained by the Canal and River Trust who have said it is looked at twice a week. The latest inspection on Thursday revealed the blooming big hole that caused the military and firefighters to be called in.

 

Read more: https://metro.co.uk/2019/08/04/whaley-bridge-residents-told-not-return-storms-set-hit-crumbling-dam-10516332/?ito=cbshare?ito=cbshare

 

Plants and weeds growing out of Toddbrook Reservoir dam in pictures taken just weeks before the partial collapse at Whaley Bridge. See SWNS copy SWLEdam: A Whaley Bridge resident has said it's "no surprise" part of the Toddbrook Reservoir dam collapsed - as a series of images showing the structure in disrepair emerge. The pictures were taken by the town homeowner, who wants to remain anonymous, in the weeks and months before last week's devastating floods. Hundreds of plants can be seen growing from the earth and creeping through the concrete spillway, which partially collapsed on Thursday (1/8).

 

Edited by Alan de Enfield
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48 minutes ago, catweasel said:

Might as well shut the forum down if we can't state our views and have an opinion. Any pending investigation will be interesting, but likely no more accurate than the opinions on here.

I don't think having opinions is a problem, it could put up a variety of scenarios that perhaps hadn't been thought about; what is problematic is going into the 'blame game' when the people targetted aren't on here to defend either themselves or the decisions that they may, or may not have made. Everyone can have 20/20 hindsight vision, how many people before the event said, "A torrential downpour of rain is going to rip up half of that spillway".  We have disagreeing views even on here , one saying that plants growing would have weakened it, others saying that the plant roots would have bound the earth together more.

 

My limited understanding of another area, aviation, is that they have a blame free system of 'occurrence reporting', where the questions are what happened? why did it happen? what can we do to stop it happening again? are addressed without looking for a scapegoat. Once we start looking for who to blame the sensible system breaks down because everyone will direct blame elsewhere and you never really get to learn much, other than people can come up with some really strange defences.

4 minutes ago, Alan de Enfield said:

Pictures emerged today of the dam wall three years ago, which has raised questions about the maintenance of the concrete panels on the spillway. Vegetation is growing through it, leading one engineer to speculate over historic harm to the 180-year-old structure. Dr Mohammad Heidarzadeh, an assistant professor at Brunel University, said the vegetation on the 2016 video taken from a drone indicated likely gaps between the panels where water could have swept in, making the damage worse. He said: ‘That could be the whole problem right there. ‘The spillway needs to be kept sealed and clear of these kind of weeds and plants.’ The reservoir is maintained by the Canal and River Trust who have said it is looked at twice a week. The latest inspection on Thursday revealed the blooming big hole that caused the military and firefighters to be called in.

 

Read more: https://metro.co.uk/2019/08/04/whaley-bridge-residents-told-not-return-storms-set-hit-crumbling-dam-10516332/?ito=cbshare?ito=cbshare

 

Plants and weeds growing out of Toddbrook Reservoir dam in pictures taken just weeks before the partial collapse at Whaley Bridge. See SWNS copy SWLEdam: A Whaley Bridge resident has said it's "no surprise" part of the Toddbrook Reservoir dam collapsed - as a series of images showing the structure in disrepair emerge. The pictures were taken by the town homeowner, who wants to remain anonymous, in the weeks and months before last week's devastating floods. Hundreds of plants can be seen growing from the earth and creeping through the concrete spillway, which partially collapsed on Thursday (1/8).

 

The side of the spillway shown in the photo remained undamaged, why was that if the plants were the problem?

Edited by Wanderer Vagabond
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10 hours ago, mayalld said:

Sutton is the smallest of the 4 reservoirs, and doesn't contribute much.

 

Due to the much higher lockage at Bosley, Coombes and Toddbrook feed all the requirements for Marple Locks, and part of the requirements for Bosley (and the annual requirement to flood the recreation ground at Bollington)

Just spotted you have responded to me Dave. I was under the impression that it was the low levels at Sutton last summer that caused Bosley to be closed for a few months. 

 

Does Toddbrook need to be so big? I presume it was built to serve the needs of the quarrying industry which must have involved many more movements than the leisure industry generates today. 

 

I assume your last statement is a reference to the frequency with which the banks above Bollington fail

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6 minutes ago, Wanderer Vagabond said:

I don't think having opinions is a problem, it could put up a variety of scenarios that perhaps hadn't been thought about; what is problematic is going into the 'blame game' when the people targetted aren't on here to defend either themselves or the decisions that they may, or may not have made. Everyone can have 20/20 hindsight vision, how many people before the event said, "A torrential downpour of rain is going to rip up half of that spillway".  We have disagreeing views even on here , one saying that plants growing would have weakened it, others saying that the plant roots would have bound the earth together more.

 

My limited understanding of another area, aviation, is that they have a blame free system of 'occurrence reporting', where the questions are what happened? why did it happen? what can we do to stop it happening again? are addressed without looking for a scapegoat. Once we start looking for who to blame the sensible system breaks down because everyone will direct blame elsewhere and you never really get to learn much, other than people can come up with some really strange defences.

The side of the spillway shown in the photo remained undamaged, why was that if the plants were the problem?

It wasnt the side of the spill way that gave, it was the base at the upper end, the visible erosion beyond the spill way wall was caused after the concrete base had gone and undermined a very large area underneath.

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I agree a lesson or two needs to be learned. 

 

No one has been harmed have they?

 

Blame culture seems to me a relatively modern illness for which there may be no cure in sight. 

 

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9 hours ago, bizzard said:

A lavatory cistern ball cock float and drain is needed. When the dam rain water rises to a predetermined level the float actuates the drain plug a bit to maintain the level. Must be Wicke's or plumbers nearby in Whaley Bridge.

Or a syphon weir

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3 minutes ago, matty40s said:

It wasnt the side of the spill way that gave, it was the base at the upper end, the visible erosion beyond the spill way wall was caused after the concrete base had gone and undermined a very large area underneath.

I believe that you may have misunderstood what I was saying, the photograph on the earlier posting shows the right hand side of the spillway (facing east) in which plants are visible. That part of the spillway remains undamaged, despite the visible plants as it was the left hand side of the spillway (facing east) that has been washed out. If the plants were the problem why has the right hand side remained undamaged?

7 minutes ago, MartynG said:

I agree a lesson or two needs to be learned. 

 

No one has been harmed have they?

 

Blame culture seems to me a relatively modern illness for which there may be no cure in sight. 

 

Unfortunately because there is money in it,"Where there's a blame there's a claim" saves having to work for a living :unsure:

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12 minutes ago, Wanderer Vagabond said:

I believe that you may have misunderstood what I was saying, the photograph on the earlier posting shows the right hand side of the spillway (facing east) in which plants are visible. That part of the spillway remains undamaged, despite the visible plants as it was the left hand side of the spillway (facing east) that has been washed out. If the plants were the problem why has the right hand side remained undamaged?

And yet one of the experts from a link earlier didn't see a problem with the vegetation shown in the photos. Goes to prove that all we have at the moment is conjecture.

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Whether the vegetation was a problem or not, it should not have been there.  Or passed inspection.  How big does a bush have to get before someone does something about it?  The same applies to lock walls, gates, etc.  The lengthsman at Oxford stood on the bows of my boat, pulling weeds out of the bottom gate of Wolvercote lock.  Long time ago. 

 

.weeds.jpg.24c77feb54214a7ce93f9466b311ca69.jpg

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1 hour ago, Graham Davis said:

And yet one of the experts from a link earlier didn't see a problem with the vegetation shown in the photos. Goes to prove that all we have at the moment is conjecture.

There are experts and there are experts who know what they are talking about.

A weed has roots, which growing on the join of a concrete spillway will be growing through the mortar, grout, sealant etc which is supposed to stop water ingress. The roots will have weakened this. Some of those concrete joins had large weeds over the whole length of the joints....meaning the whole join was compromised....over its whole length. 

Go figure.

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11 hours ago, bizzard said:

A lavatory cistern ball cock float and drain is needed. When the dam rain water rises to a predetermined level the float actuates the drain plug a bit to maintain the level. Must be Wicke's or plumbers nearby in Whaley Bridge.

Bit like the water waster on the Crinan!

https://canmore.org.uk/site/114372/crinan-canal-ardrishaig-water-waster

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8 hours ago, matty40s said:

There are experts and there are experts who know what they are talking about.

A weed has roots, which growing on the join of a concrete spillway will be growing through the mortar, grout, sealant etc which is supposed to stop water ingress. The roots will have weakened this. Some of those concrete joins had large weeds over the whole length of the joints....meaning the whole join was compromised....over its whole length. 

Go figure.

You seem to have assumed that the joints between the concrete slabs have been sealed with 'mortar, grout, sealant etc.'  Do you know this to be the case?  

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9 hours ago, matty40s said:

There are experts and there are experts who know what they are talking about.

A weed has roots, which growing on the join of a concrete spillway will be growing through the mortar, grout, sealant etc which is supposed to stop water ingress. The roots will have weakened this. Some of those concrete joins had large weeds over the whole length of the joints....meaning the whole join was compromised....over its whole length. 

Go figure.

All conjecture, as I said.

And how do you know that any of the experts, pro or anti, have actual experience of THIS dam?

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