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Aire & Calder Breach


Joe Bourke

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There's a credible explanation by Tony Dunkley on Thunderboat Forum about how the breach may have been caused. Seems because CRT haven't been dredging the inside of the bend barges have to turn very close to the left bank. Same old story spend the budget on media and marketing instead of maintenance.

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1 hour ago, Midnight said:

There's a credible explanation by Tony Dunkley on Thunderboat Forum about how the breach may have been caused. Seems because CRT haven't been dredging the inside of the bend barges have to turn very close to the left bank. Same old story spend the budget on media and marketing instead of maintenance.

And of course Mr Dunkley is a totally unbiased commentator on all things CRT

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Tony's suggestions as to why it occured :

 

 

Lack of inspections and checks cause of Aire & Calder breach

 PUBLISHED: WEDNESDAY, 23 DECEMBER 2020

BENEATH the Aire & Calder, right next to where that hole has appeared near New Bridge is a largish culvert, writes Tony Dunkley.

It carries a land drain for the area that's been flooded, and the land drain runs to a pumping station on the Dutch River (the river Don) about a hundred yards away. There have been leaks at this spot in times past, which is why the heavy duty Larssen piling that can be seen in the photographs was driven next to and inside of where the original waterway walls were. If the culvert has collapsed, partially collapsed, or is damaged in any way, then this could turn into a long and expensive job to fix.

Barges passing close to the piling

Not an immediately obvious connection, but years of mud and silt build up—going back to the latter days of BW—on the inside of the bend just on the Knottingley side of the breach always used to force loaded Westbound 180'(+) long 500 and 600 ton barges to take a very wide course round there with the stern passing very close to the pilingsometimes only inches awayand the powerful backwash from the propellers blasting away at the canal bed right where the hole has now appeared.

The timing of the breach may or may not be significant, but the minor increase in barge traffic over the last few weeks could well have caused some final bit of extra canal bed erosion adjacent to the piling where the hole has appeared sufficient to lead to the massive leakage that began last Sunday.

Inattention to routine maintenance

If that is so then the root cause of this breach goes back to BW's inattention to routine maintenance spot dredging during their latter years, followed by CaRT's eight and a half years of total inattention to anything, . . and in particular, as in every recent instance of serious leakage or collapse, regular inspections and checks by competent experienced lengthsmen who can recognize the signs of imminent structural failures BEFORE they happen.

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46 minutes ago, Alan de Enfield said:

regular inspections and checks by competent experienced lengthsmen who can recognize the signs of imminent structural failures BEFORE they happen.

How would competent experienced lengthsmen have seen an imminent failure of the canal bed before it happened?

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It would be easier to take people seriously if they were not prone to gross exaggeration.

 

followed by CaRT's eight and a half years of total inattention to anything, . . 

 

This being completely factually incorrect.

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13 minutes ago, The Happy Nomad said:

It would be easier to take people seriously if they were not prone to gross exaggeration.

 

followed by CaRT's eight and a half years of total inattention to anything, . . 

 

This being completely factually incorrect.

There is enough evidence to suggest crt are winding down the navigation, this whether you like to admit it or not.

The clear out of staff with canal knowledge and replacing with digital marketing support in itself is enough to suggest issues will continue. Add to this the ridiculous lack of dredging and things look very downhill.

Anyone not recognising the problems obviously does not want to.

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6 hours ago, Midnight said:

but none-the-less very knowledgeable in these matters. 

I have read many of his posts about the Trent and canals,and agree he is very knowledgable.

But his rather blunt manner and at times almost slanderous critiscism of CRT has not won him many friends in high places.

Got libel and slander the wrong way around.Slander is spoken and libel is written.

Edited by Mad Harold
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1 hour ago, Jon johan said:

There is enough evidence to suggest crt are winding down the navigation, this whether you like to admit it or not.

The clear out of staff with canal knowledge and replacing with digital marketing support in itself is enough to suggest issues will continue. Add to this the ridiculous lack of dredging and things look very downhill.

Anyone not recognising the problems obviously does not want to.

This completely misses the point of what I actually said. But never mind.

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32 minutes ago, Col_T said:

 

Genuine question - what are the above-water signs of an imminent failure of a canal / river bed?

I would expect that prior to a big breach like that there would be tell tale signs of imminent failure such as evidence of a smaller trickle/flow of water which gradually gets worse until the breach size becomes so large it gives way.

 

When the River Aire (not the canal) breached in 1988 near Lemonroyd lock there was evidence of increasing fissures in the mine side the day before but they allegedly all ignored it and went home from the mine. When they returned the next day they had a new very large pond instead of an open cast mine.

 

When the Middlewhich breach occurred in 2018 ISTR there were reports of it being preceded by a visible flow before giving way big style.

 

I guess a lot depends on how much opportunity you have to do something about it when there is evidence of a leak.

 

 

Edited by The Happy Nomad
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12 hours ago, David Mack said:

How would competent experienced lengthsmen have seen an imminent failure of the canal bed before it happened?

 

4 hours ago, Jon johan said:

By being competent and experienced of course. 
Seriously, you think they would not recognise the signs?

 

If Tony's explanation is correct, that barges forced to that side of the canal caused scouring of the bed adjacent to the piling, that scouring would not have been visible to anyone unless the canal had been drained. By the time you get to a whirlpool in the canal you are not talking about 'imminent failure' - you already have a failure.  All a bankside presence can do by that time is raise the alarm, which might result in stop planks going earlier and perhaps reducing the extent of the flooding.

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19 minutes ago, David Mack said:

 

 

If Tony's explanation is correct, that barges forced to that side of the canal caused scouring of the bed adjacent to the piling, that scouring would not have been visible to anyone unless the canal had been drained. By the time you get to a whirlpool in the canal you are not talking about 'imminent failure' - you already have a failure.  All a bankside presence can do by that time is raise the alarm, which might result in stop planks going earlier and perhaps reducing the extent of the flooding.

How often would a lengthsman walk every foot of canal

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17 hours ago, ditchcrawler said:

I thought it was the traditional thing to go, go round the outside of bends so you don't go aground

Indeed yes.  The culvert narrows here is a nuisance as it prevents you from starting the turn a bit earlier with anything big going upstream.  I'm not sure why dredging the inside would help.  I suspect this failure is something to do with the culvert but we will have to wait for the investigation to find out.

Aire & Calder Navigation Main Line
Location: Pollington Lock and Goole Caisson
Starts At: Lock 13, Pollington Lock
Ends At: Goole Pipe bridge

Sunday 20 December 2020 14:30 until Monday 4 January 2021 23:59

Type: Navigation Closure
Reason: Structure failure


Update on 23/12/2020:

On the 22nd December the team on site placed around 150 tonne bags of stone on either side of the breach hole and this slowed the flow of water leaving the canal. The plan for the 23rd December is to continue with this work, with the helicopter placing probably around another 100 bags of stone, to shore up the hole. Once enough have been placed we will start to place clay around the bags to create a water tight seal and depending on how works proceed today, this could be later today or tomorrow. We have taken the decision to keep the navigation closed until January 4th as a precaution.

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9 minutes ago, fanshaft said:

Indeed yes.  The culvert narrows here is a nuisance as it prevents you from starting the turn a bit earlier with anything big going upstream.  I'm not sure why dredging the inside would help.  I suspect this failure is something to do with the culvert but we will have to wait for the investigation to find out.

Aire & Calder Navigation Main Line
Location: Pollington Lock and Goole Caisson
Starts At: Lock 13, Pollington Lock
Ends At: Goole Pipe bridge

 

Sunday 20 December 2020 14:30 until Monday 4 January 2021 23:59

 

Type: Navigation Closure
Reason: Structure failure

 


Update on 23/12/2020:

 

On the 22nd December the team on site placed around 150 tonne bags of stone on either side of the breach hole and this slowed the flow of water leaving the canal. The plan for the 23rd December is to continue with this work, with the helicopter placing probably around another 100 bags of stone, to shore up the hole. Once enough have been placed we will start to place clay around the bags to create a water tight seal and depending on how works proceed today, this could be later today or tomorrow. We have taken the decision to keep the navigation closed until January 4th as a precaution.

 

I doubt very much an investigation will shed light on anything, especially if it’s anything like the hilariously redacted report from CRT on the Toddbrook reservoir shambles.

 

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6 minutes ago, Jon johan said:

Up until 2013, daily. I can remember seeing lengthsmen and bank staff on a daily basis. 
I consider myself lucky to see 1 or 2 over a 12 month period these days.

So if a lengthsman walks 20 miles a day that would be 100 lengthsmen ish, 

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Using a general visual inspection isn’t a robust method of identifying potential earthwork failures which is the generic cause of breaches. As others have identified the best a general visual inspection could achieve is to alert to the imminent likelihood of a breach.

 

The kinds of features that cause earthwork failures require the inspector to be on and about the earthwork itself and therefore it is a specific detailed inspection. This is how CRT’s contemporaries manage their earthworks - and other critical assets - and it may also be CRT’s method. General visual inspections are far from foolproof even with diligent and well trained inspectors.

 

There is evidence that CRT’s inspection policies aren’t the problem. They are an organisation that has a large maintenance backlog. This is indicative that their inspection regimes are better are identifying work than their workbank management system is at effectively prioritising, scheduling and executing the work that the inspection processes identify.

 

Similarly at Toddbrook reservoir dam there would have been a legally specified requirement for inspection on account of the risk profile of such a structure. That still didn’t prevent a failure.

 

The suggested reason for the breach is entirely plausible - even without the effects of any lack of dredging - but it would require an inspection of the de-watered channel to identify the root cause. I suspect some of CRTs high criticality structures are subject to an inspection regime that requires inspection in the de-watered state to a specified frequency, but I’d hazard a guess that culverts in general are not in that category.

 

I’d be surprised if CRT are at the same place as their asset management contemporaries - their risk profile is a lot lower after all - but even if they were the occasionally failure couldn’t be ruled out, it’s the nature of the beast to a degree.

 

So I suspect they could improve their management of risk around breaches but my guess is that inspection isn’t the place to start. In this instance I’d also look at whether the risks associated with re-commencing a commercial flow with large vessels were properly identified and mitigated. That ought to be part of their own internal consideration.

 

JP

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I suspect the restarting of commercial traffic is a it of a red herring. The major problem they have is that they are dealing with a 200-year-old structure (190 in this case) for which there are few records. It is for that reason that locally-employed maintenance workers were important as they built up local knowledge about structures in their area. Unfortunately, modern business economics does not provide finance for such people, though earlier in the last century, the L&LC engineer thought that one man per mile was the minimum he could get away with in safety.

 

Another problem with the area around the Knottingley & Goole Canal is that since the canal was built, there have been many improvements in land drainage. This could well have resulted in the land subsiding, leaving the canal on an embankment. The L&LC has had several breaches for this reason. If the piles, which could be thirty or forty year old, were not long enough to cope with the subsidence, they would be a weak spot, though identifying when they would fail because of water making its way underneath them would be difficult.

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