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furnessvale

Whaley Bridge Evacuated

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12 minutes ago, StarUKKiwi said:

First off, the Basin, Transhipment Shed, houses, Railway Station, then The aquaduct next to B&M/Tesco on the Bugsworth Arm would go, the next major structure is the A6 bridge, then the main viaduct carrying the Sheffield Line at New Mills, plus the two bridges over the Goyt in New Mills. (hence they're all closed). 

There is a command meeting at 11am but the BBC shared this 

https://www.bbc.co.uk/news/amp/uk-england-derbyshire-49231384?__twitter_impression=true

I could see extensive damage happening along the length of the Upper Peak Forest. The water would travel as a huge wave along the canal from the basin, overwhelming the bywashes. It would escape over the towpath side in to the valley, but likely wash away and breach the bank and towpath in multiple places. Similar too, but worse than what happened to the Calder & Hebble in the floods a couple of years ago. How far it would go along the Peak Forest before dissipating I don't know. Worse case for the Peak Forest is if the Marple Aquaduct were damaged too from the Goyt flowing underneath. Insignificant compared with the damage to everything else in the valley, but more millions for CaRT to find in addition to repairing/demolishing the dam and possible legal action if they are found to have been negligent.

 

Jen

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13 hours ago, Cheshire cat said:

You are ignoring Sutton Reservoir which is there to supply Bosley

 

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)

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15 hours ago, MartynG said:

I see what you mean.

In 1970 perhaps they did not have  all the rainfall data that is a available now. And climate change had not been invented.

No engineering offers guarantees - just that some areas are more explicit about the risk than others. 

 

There always a cost benefit tradeoff, as well as a cash (ie investment) availability.

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I am no expert, but, I have seem pictures, on BBC internet news, of the levels this morning. They are well down on what they were. Surely the pressure on the dam has reduced dramatically in the last few days. Has the danger now passed?

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1 minute ago, Nightwatch said:

I am no expert, but, I have seem pictures, on BBC internet news, of the levels this morning. They are well down on what they were. Surely the pressure on the dam has reduced dramatically in the last few days. Has the danger now passed?

IT seems the forecast thunderstorms for Sunday passed them by. We had them here though. Weather forecast this week is better. Hopefully the risk is now lower.

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We are at Langley Mill and we had a couple of light showers yesterday, but by all accounts heavy rain, thunder and lightening wasn't far away.

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14 hours ago, magpie patrick said:

I'm not recommending this route, but United Utilities do look after Gorton Reservoir even though it is redundant for their purposes, and they do a good job, including spending rather a lot on a new spillway not that long ago.

Presumably they are keeping it for some good reason, such as a long term contingency in case the climate change people are right after all.

14 hours ago, TheBiscuits said:

Don't forget that the 1200 locks figure is only Marple flight - Bosley adds another 3000 lock fulls, so the reservoir looks like one year 's usage takes 60-70% of the reservoir (without leakage/evaporation etc) so it's probably the correct size!

But the Todd Brook continues to refill much of the time. The capacity of the reservoir is relevant to its buffering requirement not total supply although it is interesting to note that it would require a 12 month drought to get anywhere near empty, plus the capacity of the other reservoir.

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We left our boat temporally (😏) at Furness Vale Marina a few weeks ago and hope to rescue it next week by heading back down the Macclesfield.

With a draft of 31”, should I be concerned about CRT’s ability to maintain levels for a week or so once the stop planks at bridge 29 have been removed? Is Toddbrook the only supply?

There has been talk of the feeder being damaged and of course there is a dwindling amount of water in the reservoir. 

Thanks.

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On 03/08/2019 at 18:21, Naughty Cal said:

Funny how everyone suddenly becomes a civil engineer in these cases👷‍♂️

Why does that surprise you? I seem to remember when you were a new member, and without any training or experience of Child Psychology, you constantly complained about how badly your neighbours were raising their newborne child. -  Many people become back room experts without any real knowledge or experience of the subject under discussion. It is the reason why I no longer engage in discussions which embrace my former profession.

 

 

Edited by David Schweizer
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15 hours ago, Chris Williams said:

Perhaps there should be a separate body to look after reservoirs and such like.  Entrusting it to a 'Charity' with all its other problems does not make sense.  I would not trust CaRT to look after the local duckpond.

I thought that there was in the form of an independent inspectorate whose recommendations are mandatory. When was the last 10 year inspection? Last November! Not just CaRT engineers who did not anticipate the failure mode.

2 minutes ago, gbclive said:

We left our boat temporally (😏) at Furness Vale Marina a few weeks ago and hope to rescue it next week by heading back down the Macclesfield.

With a draft of 31”, should I be concerned about CRT’s ability to maintain levels for a week or so once the stop planks at bridge 29 have been removed? Is Toddbrook the only supply?

There has been talk of the feeder being damaged and of course there is a dwindling amount of water in the reservoir. 

Thanks.

Look back over the thread - there is also the Coombs Reservoir and other inputs to the Macc (as is true for all canals)

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17 hours ago, Arthur Marshall said:

The design wasn't fllawed - it was fine when it was designed. Without being a po-faced self-righteous plonker, no one then expected us to trash the planet, or could even imagine that it could be done. 

However, politicians and professional designers (and inspectors) of weather dependent stuff have known about it for years, taken their salaries and lied. Too late to do much about it now. 

I suspect that the question of the appropriateness of the design might well be in question.

 

The emergency spillway was added in the 1970s I believe, and meets the requirement that even in an extreme storm it should not be possible for an earth dam to be overtopped.

 

Its design will have taken account of the maximum possible flow, so to that extent it was well designed.

 

Of course, in the years before there was an emergency spillway, there was never a problem, because an employee was responsible for ensuring that it never overtopped. Emergency spillways reduced the reliance on the employee.

 

Where it IS flawed though is that the emergency spillway introduces a new potential point of failure. The original spillway comes out of the side, not through the dam, because they knew that running water over an earth dam was a bad idea. The emergency spillway is a poor design, because it inevitably means that a crack in the concrete can do this.

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47 minutes ago, Nightwatch said:

I am no expert, but, I have seem pictures, on BBC internet news, of the levels this morning. They are well down on what they were. Surely the pressure on the dam has reduced dramatically in the last few days. Has the danger now passed?

there was never any specific danger of the dam failing from water pressure - it was an unknown but seemed unlikely.

 

there was and is a danger of the dam failing as a result of the spillway failing, and if we had another catastrophic rainfall event it could happen.

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43 minutes ago, Mike Todd said:

Look back over the thread - there is also the Coombs Reservoir and other inputs to the Macc (as is true for all canals)

Thanks Mike - sorry, I missed that part of the thread.

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1 hour ago, mayalld said:

I suspect that the point he was making was that there was no question that a lack of funds had led to a failure to properly maintain the reservoir

No, Tuscan has the correct version, Mr Parry said they had all the funds they needed.

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20 minutes ago, mayalld said:

 

Where it IS flawed though is that the emergency spillway introduces a new potential point of failure. The original spillway comes out of the side, not through the dam, because they knew that running water over an earth dam was a bad idea. The emergency spillway is a poor design, because it inevitably means that a crack in the concrete can do this.

 

Many dams have had to have additional spilway capacity added as a result of increasing dam safety standards over the years. And the spillway capacity can only be increased by increasing the length of the weir crest. For an earthfill dam which spans across a valley there is often nowhere else to provide the additional length of weir other than along the top of the dam itself.

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1 hour ago, mayalld said:

I suspect that the point he was making was that there was no question that a lack of funds had led to a failure to properly maintain the reservoir

That was surely the point he was making. He did receive quite a grilling from the interviewer:

https://www.bbc.co.uk/programmes/p07jk6k9

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1 minute ago, matty40s said:

No, Tuscan has the correct version, Mr Parry said they had all the funds they needed.

 

Having watched the episode on Newsnight that Emma Barnett had a really weird line of questioning. Basically she just kept asking what CRT had done with their increased Gov't grant, and why they had not used it stop this dam failure. Richard seemed unable to say they used it to maintain the canal network and engineers' reports said there was nothing to suggest the dam needed any extra expenditure. 

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On ‎02‎/‎08‎/‎2019 at 15:26, Tuscan said:

Richard Parry stated on Newsnight that CRT were not short of funds for reservoir works so there should be no problem.............

No, he did not say that at all.

On ‎03‎/‎08‎/‎2019 at 17:43, LancaCanal said:

Someone who lives in WB  has told me the following

The reason this has happened is neglect since BW was abolished by the govt and the Canal and River Trust took over without sufficient funding.

There used to be a BW employee living in a tied house right next to the dam;  he managed the reservoir on a daily basis, controlling the water levels with the side sluices and the gates at the bottom, so there was enough capacity to take extra in when necessary, without it getting to the point of flowing over the spillway which is only meant to happen as a 'last resort'.  This employee was made redundant when BW was abolished, and the house was sold.  Daily monitoring has thus been lacking for several years; visits and observations for brief periods a couple of times a week is no substitute  for daily active management of reservoir levels!  People in WB - some of whom knew the BW employee and had helped him in the past - have contacted the CRT over the years with concerns about  damage to the spillway when it was overflowing, but were basically told they were wrong. Now it is alarmingly clear that they were right.   

 

Honestly.  You really believe that to be the case. Sounds like the comments from someone who retired many years ago. 

 

3 hours ago, Jerra said:

I was interested to see a Civil Engineer (funny how none claim to be uncivil engineers) on TV pointing out that emptying the dam too quickly could damage the dam on the side towards the water.   So clearly it isn't just a case of getting the water out as quick as you can.

Amen.  Something the armchair engineers never thought of. 

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11 minutes ago, Mike the Boilerman said:

 

Having watched the episode on Newsnight that Emma Barnett had a really weird line of questioning. Basically she just kept asking what CRT had done with their increased Gov't grant, and why they had not used it stop this dam failure. Richard seemed unable to say they used it to maintain the canal network and engineers' reports said there was nothing to suggest the dam needed any extra expenditure. 

To me it seemed that he hadn't been briefed at all. He had no explanation whatsoever for the failure and appeared to have very little idea about anything. While the questioning was pretty pathetic too, you would have thought he could have given some impression that he knew anything at all about canals. He just looked and sounded nervous - not a reassuring look. 

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5 minutes ago, Dustin Wright said:

Something the armchair engineers never thought of. 

Wasn't that who thought of shoring up the dam with horse hair and sack cloth?

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25 minutes ago, David Mack said:

 

Many dams have had to have additional spilway capacity added as a result of increasing dam safety standards over the years. And the spillway capacity can only be increased by increasing the length of the weir crest. For an earthfill dam which spans across a valley there is often nowhere else to provide the additional length of weir other than along the top of the dam itself.

It is always POSSIBLE to provide additional spillway capacity other that over the weir crest, but probably considered prohibitively expensive in the 1970s.

 

Protecting the dam against overtopping by allowing it to overtop with a protective surface is playing with fire.

 

It will be interesting to see what they do to repair.

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18 hours ago, Mike Todd said:

I guess it would be fairly easy to do an order of magnitude calculation about the number of lockfuls per day needed as a canal reservoir. Does anyone local know how many boats pass through Marple each day (the crucial point for the feeder)

I'm sure they do, but do they know how much water is lost through leakage of the locks and seepage/leakage if the canal.

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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.

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29 minutes ago, Mike the Boilerman said:

 

Having watched the episode on Newsnight that Emma Barnett had a really weird line of questioning. Basically she just kept asking what CRT had done with their increased Gov't grant, and why they had not used it stop this dam failure. Richard seemed unable to say they used it to maintain the canal network and engineers' reports said there was nothing to suggest the dam needed any extra expenditure. 

I think he did: see 5 min 30 secs into clip.

 

https://www.bbc.co.uk/programmes/p07jk6k9

 

To be fair, I think he spoke pretty well and can't really see what more he could have said.

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1 hour ago, Nightwatch said:

I am no expert, but, I have seem pictures, on BBC internet news, of the levels this morning. They are well down on what they were. Surely the pressure on the dam has reduced dramatically in the last few days. Has the danger now passed?

Article linked to above states they have now reduced the levels by 48% but need to get down to 25% before the full dam wall can be inspected. 

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