Jump to content

Montgomery canal restoration.


Featured Posts

We've spent that last couple of days bumping down the Montgomery canal. Very pretty, very away-from-it-all and very quiet.

 

Walked from the limit of navigation at Gronwen to look at the extension work. Does anyone know why he channel is being rebuilt using concrete blocks over a sealing membrane? (photo below) "Geotextile" always seems to be referred to as a good thing, but it looks to me like contaminating the the soil with tons of non-biodegradable plastic. I guess there's a reason why clay puddle can't be used, but I'd like to know what it is.

 

The new winding hole is large enough to wind several narrowboats in formation, and if any small coasters get lost and end up there, the mooring rings should cope fine!

 

Final query. I understand that Graham Palmer lock is new, to drop the level over the march section where the ground has sunk due to drainage, but does it replace a previous lock elsewhere? The new level across the march extends past Rednal basin to the top lock at Aston, and there's much original stuff there with no sign of a level drop, so I guess it must.

 

 MP

IMG_20191015_155139093.jpg

IMG_20191015_154429904.jpg

Link to post
Share on other sites

Although it is almost universally accepted that canals were lined with clay, this was not the case. It is obvious, if you think about it, that clay could not be transported any distance in the quantities need for canal building before canals were built. Yes, clay was used where it was available locally, but elsewhere a mixture of loamy soil and small stones were used, set down in a layer of around eight inches and then puddled with water, before a further layer was added. The thickness of this type of canal lining could eventually be up to three feet, depending upon the depth of the canal. If the small stones were chalk or limestone, they could create a very weak concrete layer to retain the water, but this did not happen routinely. I have been told secondhand, that when the CRT engineers looked at this section of the Mongomery, they could not find any clay, only soil and small stones, so I suspect that this older form of puddling was originally used here. I have found specifications for this type of canal lining for the Lancaster Canal, and it is discussed in Rees' Cyclopedia, so it was definitely the system used where clay was not available locally.

  • Greenie 1
Link to post
Share on other sites
2 minutes ago, Pluto said:

Although it is almost universally accepted that canals were lined with clay, this was not the case. It is obvious, if you think about it, that clay could not be transported any distance in the quantities need for canal building before canals were built. Yes, clay was used where it was available locally, but elsewhere a mixture of loamy soil and small stones were used, set down in a layer of around eight inches and then puddled with water, before a further layer was added. The thickness of this type of canal lining could eventually be up to three feet, depending upon the depth of the canal. If the small stones were chalk or limestone, they could create a very weak concrete layer to retain the water, but this did not happen routinely. I have been told secondhand, that when the CRT engineers looked at this section of the Mongomery, they could not find any clay, only soil and small stones, so I suspect that this older form of puddling was originally used here. I have found specifications for this type of canal lining for the Lancaster Canal, and it is discussed in Rees' Cyclopedia, so it was definitely the system used where clay was not available locally.

I was under the impression the dead arm by the services went to a clay pit, plus I thought wixhall marina is an old clay pit.

I am often wrong ;)

Link to post
Share on other sites

The first bit of the recent restoration past the bridge (Redwith) was done with an impermeable membrane with concrete blocks to protect the membrane.

 

The next bit was done with a new material which basically a sort of gel between two Tyvek-like sheets.  It was supposed to be self-repairing and initially it was thought that they could therefore dispense with the concrete blocks.  Unfortunately in the canal bed (a new application for this type of membrane) it was subject to movement and leakage and I think they do not plan using it any further.

 

The Graham Palmer lock, named after a leading member of the Waterways Recovery Group (WRG) was built very early in the restoration.  It did not replace a pre-existing structure.  It was needed to lower the level to maintain sufficient depth below Frankton Locks whilst coping with subsidence which had lowered the canal further down.

 

If you are interested, you can find a lot of detail on the SUCS website, http://www.shropshireunion.org.uk  ; look under restoration. 

Link to post
Share on other sites
1 hour ago, tree monkey said:

I was under the impression the dead arm by the services went to a clay pit, plus I thought wixhall marina is an old clay pit.

I am often wrong ;)

The question you need to ask is how far would it be economical to move the volumes of clay need for lining a canal using horse-drawn vehicles. Whixall would probably be too far away to supply the Montgomery. The volumes of clay required would be quite large. A quick calculation suggests around 6,000 ton per mile, and with a horse-drawn cart likely to carry 2 ton at the most, this would mean 3,000 journeys. On the L&LC in the early 1800s, the engineer reported that they had around ten carts working on construction, so it would have been possible to supply enough clay for one mile per year, as the carts would also be needed elsewhere on site. Once the canal was built, it would have been much easier to supply clay, and I suspect that some clay pits were developed after a canal opened and they supplied maintenance works.

Link to post
Share on other sites
2 hours ago, dor said:

The Graham Palmer lock, named after a leading member of the Waterways Recovery Group (WRG) was built very early in the restoration.  It did not replace a pre-existing structure.  It was needed to lower the level to maintain sufficient depth below Frankton Locks whilst coping with subsidence which had lowered the canal further down.

 

I understand that the canal across the moss has lowered but  the level there goes all the way to Aston top lock, and there doesn't seem to have been any subsidence there, or lower in the flight, unless all three locks have dropped exactly the same distance. Nor are the tops of the walls at Aston top mysteriously two feet higher than they need be for the current water level. If you took Graham Palmer lock away, the water level would be too high at the bridge 74 and the A5 bridges, and overflowing Aston top lock. Logically, you might expect that the original canal had a lock at the south end of the moss, making the height change which is now done by Graham Palmer lock. If that's not the case, I'm at a loss for the explanation.

 

Might the high wall on the towpath side between the railway bridge and bridge 74 be the remains of such a lock?

 

MP.

 

ETA. Here is where I mean.

https://www.google.co.uk/maps/@52.8423644,-2.9644322,3a,60y,2.51h,81.7t/data=!3m6!1e1!3m4!1sjhqLXd1Xy8N1ragFpBa_lg!2e0!7i13312!8i6656

 

Edited by MoominPapa
Add streetview link.
Link to post
Share on other sites

I'm pretty sure that Aston top lock was rebuilt to a lesser depth than before to account for the drop at the Graham Palmer lock. The lock was extensively rebuild, including lowering the top cill, so there is now no visible evidence of its former depth.

Link to post
Share on other sites

Passed through there in August and the Graham Palmer lock was one of the worst I have encountered in recent years. The planking of the top gate leaked like a sieve and took ages to level off for such a shallow lock, the consolation being for the future in that it is due a refurb this winter.

 

I to walked the recently built section and was impressed with the mooring rings and huge winding hole, different. Not quite sure what is planned for the section from Gronwen to the newly completed section as just after Gronwen it looks as if it was started with the profile of the canal, then abandoned.

Link to post
Share on other sites

Briefly

 

Clay is expensive, it cracks if it dries, and it loses water faster than a geotextile membrane, "keeping it wet" means it absorbs water all the time

 

No, there was no lock that GP lock replaced, it just compensates for level changes, the level is lower all the way to Aston Top Lock

 

I was involved at the latter stages of the works to Queens Head at the start of my career - it was one reason I nagged WS Atkins to give me a job!

Link to post
Share on other sites
16 hours ago, MoominPapa said:

We've spent that last couple of days bumping down the Montgomery canal. Very pretty, very away-from-it-all and very quiet.

 

Walked from the limit of navigation at Gronwen to look at the extension work. Does anyone know why he channel is being rebuilt using concrete blocks over a sealing membrane? (photo below) "Geotextile" always seems to be referred to as a good thing, but it looks to me like contaminating the the soil with tons of non-biodegradable plastic. I guess there's a reason why clay puddle can't be used, but I'd like to know what it is.

 

The new winding hole is large enough to wind several narrowboats in formation, and if any small coasters get lost and end up there, the mooring rings should cope fine!

 

Final query. I understand that Graham Palmer lock is new, to drop the level over the march section where the ground has sunk due to drainage, but does it replace a previous lock elsewhere? The new level across the march extends past Rednal basin to the top lock at Aston, and there's much original stuff there with no sign of a level drop, so I guess it must.

 

 MP

IMG_20191015_155139093.jpg

IMG_20191015_154429904.jpg

Why were you "Bumping" down the canal - was it short of water?

Link to post
Share on other sites
1 hour ago, archie57 said:

Why were you "Bumping" down the canal - was it short of water?

Not short of water - it was on weir all the way down, just short of depth. To be fair, according to Nicholsons, the draught limit is 2' and we're 2'10" At that draught it's mostly fine in the middle, and you don't meet many boats going the other way to push you out of the middle. Downstream of bridges 75 and 77 (both within sight of winding holes, but a long reverse back to the previous one) was awful - had to dredge my own channel with repeated runs. Bridge 78 and the winding hole next to it are clogged with reeds and very hard work too. The winding at the end was fine.

 

Like many restored canals (Droitwich, for instance) it's not mooring-friendly except at designated spots, almost all of which are 48 hours. At the moment there are one or two visiting boats at a time on the canal, so that's fine. If they let down the limit of 12 a day in the summer, I guess that could be interesting. Boating is very much second-fiddle to nature reserves hereabouts.

 

MP.

 

Link to post
Share on other sites

Thanks for the info on the level changes. Wish I'd looked at bridges 74 and 75 for evidence of lowered water level now.

 

Has been a good trip down, just waiting at Frankton for our passage back up. Will definitely return when there's more open.

 

MP.

 

  • Greenie 1
Link to post
Share on other sites
  • 2 months later...
14 minutes ago, hmallett said:

Dragging this thread back up, for a bit a shameless self-promotion, I walked the section being restored and you can see it on YouTube.

It might help put the pictures above in context.

Nothing wrong with a bit of self promotion, that looks fantastic, do you know why the barrels are floating mid canal?

  • Greenie 1
Link to post
Share on other sites
8 hours ago, tree monkey said:

...do you know why the barrels are floating mid canal?

I had a rough idea, but I found more information on the Shropshire Union Canal Society restoration pages. During the restoration, sumps are left in the blocks to facilitate pumping (work parties often start with a lot of pumping!). Because this first section is left filled, but will need to be drained to connect to the next section, the drains have been left in, with drainage pipe left in place as "chimneys", to raise them above the waterline.

  • Greenie 1
Link to post
Share on other sites
1 hour ago, hmallett said:

I had a rough idea, but I found more information on the Shropshire Union Canal Society restoration pages. During the restoration, sumps are left in the blocks to facilitate pumping (work parties often start with a lot of pumping!). Because this first section is left filled, but will need to be drained to connect to the next section, the drains have been left in, with drainage pipe left in place as "chimneys", to raise them above the waterline.

Thank you :)

  • Greenie 1
Link to post
Share on other sites

I had a job down that way a year or two back, stayed in caravan not far from the canal. The locks are interesting, they have some sort of baffle wall below the top gates, is that to allow rapid filling and smooth out turbulence? If not what? 

Link to post
Share on other sites
  • 2 months later...
32 minutes ago, David Mack said:

Fulbourne at Gronwen Bridge no. 82, the then limit of navigation, March 2003.

 

A bit later, Keeping Up at Pryce's bridge No 84 in 2014

 

SAM_1790r.jpg

 

Knowing that we couldn't wind there, we reversed all the way from bridge 82. For a full report and lots of pictures, see here

 

  • Greenie 2
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.