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Peak Forest Canal


Hudds Lad

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Notice Alert

Peak Forest Canal
Starts At: Lock 16
Ends At: Lock 1

Monday 11 September 2017 09:00 until further notice

Type: Navigation Closure
Reason: Structure failure


 

Original message:

 

We have had to close the lock flight at Marple until further notice due to subsidence at lock 15 . Our engineers will be carrying out inspections later today.

We understand that this closure may disrupt your schedule. We are taking every step to look into this problem as soon as possible and we will keep you updated of our progress.

 

You can view this notice and its map online here:
https://canalrivertrust.org.uk/notice/11519/peak-e-flight-

You can find all notices at the url below:
https://canalrivertrust.org.uk/notices

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Update on 11/09/2017:

 

Over the weekend subsidence has become evident at Lock 15, Marple and we have had to close the canal here while this is investigated.  Following inspections on site today we are now concerned that there has been some movement to the towpath side lock wall as well.

 Our engineering team will be undertaking a thorough examination of the lock over the next few days so that we can be clear about the true extent of the problem and what repairs are now needed.   

Given the uncertainty about the full extent of the problem we cannot estimate a reopening date for the lock at the moment, when we know more we will be able to issue a further update. 

We’re sorry if this problem has caused you delays but want to assure you that we are giving this highest priority.

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Thanks for this Mac. I was able to head off a chap taking his new boat back to West Yorkshire and about to turn onto the Macc. Last seen heading down the Cheshire locks, presumably for the Bridgewater and Rochdale.

 

We're doing a there-and back up the Macc, so wave as you pass on your long way home :)

 

MP.

 

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5 hours ago, MoominPapa said:

Thanks for this Mac. I was able to head off a chap taking his new boat back to West Yorkshire and about to turn onto the Macc. Last seen heading down the Cheshire locks, presumably for the Bridgewater and Rochdale.

 

We're doing a there-and back up the Macc, so wave as you pass on your long way home :)

 

MP.

 

I'm not going the long way home.  I have neither the energy nor inclination for singlehanding all that.  I'd already arranged to leave the boat with the North Cheshire Cruising Club for a few days, and after that if the stoppage looks like being a long one will probably find somewhere to stay on the Macc.

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On ‎11‎/‎09‎/‎2017 at 15:04, Mac of Cygnet said:

This looks like it may be a major stoppage. Several of the working boats caught by this after the Bollington festival have now turned back to go 'the long way round'. 

Daphne has just got down Cheshire locks, and is hoping to be up the Rochdale nine and the Ashton by weekend. Long diversion eighty odd miles and eighty odd locks!

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Update on 14/09/2017:

 

Following initial surveys and investigations at the lock we have confirmed that alongside the subsidence evident on the lock side the towpath side wall has moved and the lock is narrowed.  We have further work to do to confirm precisely the scale of the problem which will take place over the next week. 

We are hopeful that the lock can be reopened, albeit with a reduced width for the time being.  We expect that the restriction would mean that only boats up to 6’10” width will be able to pass through it.  We will be able to confirm this when the more detailed survey has been completed.  We also have work to do to repair the superficial damage to the lock side and install gauging at the top and bottom of the lock flight before we can reopen it.  We’re currently estimating that the lock will reopen with a restriction around 22nd September 2017.

Looking towards a more permanent repair, we have started the work of developing a repair solution so that we can decide how best this might be taken forward.

We’ll provide a further update when we’ll be able to confirm the restricted reopening date.

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37 minutes ago, MoominPapa said:

Well done CRT. that's a better outcome than I was expecting.

 

MP.

 

Indeed, though " developing a repair solution" made me wonder if they were going to use Plastic Padding type elastic rather than just work out how they are going to do it... :giggles:

Ah, the dear dead days of trying to bodge the rusty holes in your car with smelly gunge just before the nightmare of the MoT.

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I think the right hand wall is visibly bowed (and it's not just a distortion in the lens)

As Cheshire Cat says, there are sinkholes by the ladder, one can be seen between the orange mesh and the white bollard (and on several other locks in the flight as well...)

IMarple-0460.jpg.f09211c9853e6e4656fb9205cb23ac92.jpg

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4 hours ago, 1st ade said:

I think the right hand wall is visibly bowed (and it's not just a distortion in the lens)

Marple-0460.jpg.f09211c9853e6e4656fb9205cb23ac92.jpg

It is definitely the right side wall that is bowed into the lock , reducing the available width significantly. Worst part is by the lock ladder near the top. I'm not sure what the proper engineering solution  for this is: rebuild the wall or jack it back into position . Leaving it as it is long term, is not an option.

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1 hour ago, billh said:

It is definitely the right side wall that is bowed into the lock , reducing the available width significantly. Worst part is by the lock ladder near the top. I'm not sure what the proper engineering solution  for this is: rebuild the wall or jack it back into position . Leaving it as it is long term, is not an option.

Marple Locks are notorious for sink holes, although mostly lower down the flight.

This is a curious one, because the wall that has moved is NOT holding back that much land. The towpath side of these locks is embanked down to the road.

I suspect that the engineering solution will be to dug out the embankment, jack the stonework back then backfill with concrete, which should fix it permanently.

However, my concern here is that the wall has moved with no significant forces behind it. Most logical failure modes here would see the wall moving OUTWARDS rather than inwards. That suggests that the underlying problem is more that the usual void behind a wall. Possibly there is a void opened out beneath the invert, and the invert has fallen, leading to the observed movement. If that is the case, then we are looking at underpinning the invert and wall. A much bigger job.

 

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Waiting at the top of the locks.  I phoned this morning to see if it would indeed be opened on a restricted width basis tomorrow, and was promised an update this afternoon, but nothing yet. Two of us are just above the top lock, but others are 'waiting in the wings'. No sign of any further inspection today, but it was raining.........

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On 18/09/2017 at 13:03, mayalld said:

Marple Locks are notorious for sink holes, although mostly lower down the flight.

This is a curious one, because the wall that has moved is NOT holding back that much land. The towpath side of these locks is embanked down to the road.

I suspect that the engineering solution will be to dug out the embankment, jack the stonework back then backfill with concrete, which should fix it permanently.

However, my concern here is that the wall has moved with no significant forces behind it. Most logical failure modes here would see the wall moving OUTWARDS rather than inwards. That suggests that the underlying problem is more that the usual void behind a wall. Possibly there is a void opened out beneath the invert, and the invert has fallen, leading to the observed movement. If that is the case, then we are looking at underpinning the invert and wall. A much bigger job.

 

A simpler explanation is that the walls leak and the fill behind the wall has become saturated with water and very heavy. We've not done Marple flight for a while, but Bosley, which have similar stone-block  construction are pisser-central.  Those locks are seriously deep, so the overturning force on the wall from wet fill would be high when the lock was empty.

 

MP.

 

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27 minutes ago, MoominPapa said:

A simpler explanation is that the walls leak and the fill behind the wall has become saturated with water and very heavy. We've not done Marple flight for a while, but Bosley, which have similar stone-block  construction are pisser-central.  Those locks are seriously deep, so the overturning force on the wall from wet fill would be high when the lock was empty.

 

MP.

 

And water which leaks out through the walls when the lock is full may leak back  into the chamber through the bottom when the lock is empty. If in the process it carries soil particles with it then there can be a loss of material from under the bottom of the walls. And with the weight of wet fill behind, there is only one way the wall will move...

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3 hours ago, Mac of Cygnet said:

An update on this (by word of mouth - not a published CRT update!).

The restricted opening planned for today has been put back to 'next week', and no guarantee of that either.  It's looking increasingly likely I'll be wintering on the Macc.........

You could get stuck in worse places!

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20 hours ago, MoominPapa said:

A simpler explanation is that the walls leak and the fill behind the wall has become saturated with water and very heavy. We've not done Marple flight for a while, but Bosley, which have similar stone-block  construction are pisser-central.  Those locks are seriously deep, so the overturning force on the wall from wet fill would be high when the lock was empty.

 

MP.

 

It is an interesting theory!

However, experience of the flight suggests it to be less likely.

If you wait until the gushers subside, the most obvious thing is that the last bit of water to ooze out is a milky colour. Each time the lock fills, water goes through the walls, and each time it empties, it comes back, bringing with it the very fine particles from the infil.

on many occasions we have seen sinkholes at the side of a lock where the repeated operation of this process has left a large cavity at the side of the lock with a turf cap that eventually gives way. It is unlikely that there is much fill left in contact with the wall.

 

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5 hours ago, Mac of Cygnet said:

An update on this (by word of mouth - not a published CRT update!).

The restricted opening planned for today has been put back to 'next week', and no guarantee of that either.  It's looking increasingly likely I'll be wintering on the Macc.........

Now official:

Update on 22/09/2017:

Following investigation and getting detailed surveys of the lock subsidence, it is not possible to re-open the lock today as we originally anticipated. Further works are still ongoing and we hope to be able to provide an update early next week.

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4 hours ago, mayalld said:

It is an interesting theory!

However, experience of the flight suggests it to be less likely.

If you wait until the gushers subside, the most obvious thing is that the last bit of water to ooze out is a milky colour. Each time the lock fills, water goes through the walls, and each time it empties, it comes back, bringing with it the very fine particles from the infil.

on many occasions we have seen sinkholes at the side of a lock where the repeated operation of this process has left a large cavity at the side of the lock with a turf cap that eventually gives way. It is unlikely that there is much fill left in contact with the wall.

 

cf this. https://www.gov.uk/government/news/report-102017-partial-collapse-of-a-bridge-at-barrow-upon-soar

 

Water infiltration from the damaged pipe caused subsidence, then saturating the ground when the pipe was cut by the corer provided enough weight to push the wall over.

 

MP.

 

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