Grantham Canal - bits of rusty metal and other interesting stuff.

What's the idea of having water flowing through the letterboxes into the lock chamber instead of down the bywash? If water flows in all the time, how do you empty the lock for a boat to pass to or from the lower pound?

And another question: why the insistence on using lime mortar when the original design is being changed substantially in other respects; lock walls raised to allow for higher water level in the upper pound and extended by a couple of metres increased length, walls at the bottom with level tops instead of sloping?

 

The intention is to close off the by-wash - see posts #149,150 & 151. The flow of water is usually not a raging torrent, more like that of a babbling brook - although flow rates can vary depending on the weather or lock operation further up the canal. If the lower gates are left open, the water will just flow through the lock chamber into the lower pound. If the lower gates are closed, any build up of water in the lock chamber can be released through the paddles in the lower gates before allowing a boat to enter the lock from the lower pound.

As for your second question; What I will say is that this project is C&RT's train set and they specify what work is to be done and how. We unpaid volunteers merely carry out their instructions. We (the volunteers) do ask questions as to the whys and wherefores but at the end of the day, it is down to C&RT management how the project proceeds - after all, they are the canal professionals.

b.

 

First of all, my apologies for the loss of the photos in earlier posts. Photobucket have blocked my account because they do not allow third-party hosting - it's only taken them two years to tell me! I will attempt to keep you up-dated with a reduced level of reporting until I work something else out.

The near-side letter-box awaiting some TLC.



Inside the near-side letterbox after some pointing.



The off-side letterbox wall is coming along.



Iona's mark.

 

Looking at one of the earlier posts, if lime mortar has been specified then I can understand why - it is more flexible. If there is any problem it will crack rather than the brick or stone and cracks in lime mortar are said to self heal. Very useful in a water tight lock chamber I should think. Well worth looking up the properties of this traditional material.

 

Back after a few enjoyable days in the land of the SDR and the DSR.

Whilst I have been skiving relaxing in the sunshine, the lads and lasses of C&RT and GCS have been carrying on the good work.

The by-wash at the lower end of the lock has been re-routed and extended to allow further work to move the temporary dam. The original by-wash route back into the canal was behind the big bush. Whilst this new route was being excavated, our excavator driver also discovered a mains water pipe which was thought to be somewhere else. Fortunately no damage was done and the presence of the pipe has been marked to warn others.




The stop-board channels have also been secured in their final place by means of rather large nuts and bolts. Grouting has been poured in behind the channels to provide a watertight seal.
That big lump of wood in the foreground is an oak beam which will be bolted into the forebay floor to provide a beam on which the stop boards will rest when they are in place. That way, a better seal will be provided rather than if the stop boards were in direct contact with the (uneven) concrete floor. Any leaks through the stop boards, when they are in place, will be sealed by the use of coal ash. The beam is secured in place by M20 nuts and bolts. The top of the stop board channels will be trimmed to size once the edge capping stones have been installed.



We are concentrating on the off-side off the lock where work has continued on restoring the off-side letterbox. It's fairly slow-paced work as replacement stones are having to be cut from some old lock chamber edge capping stones which are no longer fit for that purpose. It's looking pretty good.



Work has also taken place in the upper forebay to re-shape the approach walls. Investigation showed that stone blocks had been placed directly onto the earth embankment. Consequently, in order to make the approach walls more robust, block walls are being installed below the water level and the original stone blocks will be used to build up the upper layers which will be seen when the lock is re-watered.



Work will transfer to restoring the near-side once we have finished this part of the task.

As I mentioned in an earlier post, there is a hitch with photos which were stored on Photobucket. Restoring those photos is a bit of a drawn out process - I'm having to check out three SD cards to identify particular photos but I will try to re-instate them as and when time permits - childminding two very active little grandsons takes its toll - so please bear with me. Thanks.

 

Here's a taster for the next report.

The lower dam has been relocated and has exposed the full extent of the inlet timber floor for the first time since 1797. It's got to be kept wet to preserve the timbers!!


Photo courtesy of Bob Taylor of the GCS Thursday gang.

 

Thought I better do another update seeing we've had the WRGs on site for the month of August and the WRG's Sam told me to keep the updates flowing. I've split this latest update into two separate reports - one for the lower end of the lock and one for the upper end.

The re-positioned lower dam has been effectively sealed and there is only a very minor trickle of water coming through. It's a useful leak as it is sufficient to keep the inlet timbers at the lower end of the lock in a wet condition. Further excavation at the lower end has revealed more of the wing wall and remnants of the mooring wharf on the near-side. The mooring wharf seems to have consisted of nothing more than crudely placed stone blocks laid directly onto the earth embankment without the use of any form of mortar mix.





With the area drained, this allowed the visiting WRGs to get to work and turn the approach walls into a more substantial structure which should withstand boats bumping into the wall as they await to enter the lock. (wishful thinking for far into the future).



Finally, thanks to the assistance of the WRGs, a shot of we have been working to achieve - edge capping stones mortared into place on a restored wall. Just need to repeat this for both sides of the lock, add some gates and that's the job jobbed!



edited to correct a mis-speeling.

 

Meanwhile, at t'other end of the lock, things have been moving on apace.

Work on the upper offside consisted of re-building the letterbox and the off-side approach wing wall. Both these areas have now been completed with the exception of the edge capping stones.

The completed letter box.



The rebuilt off-side approach wing wall.



Our attention then transferred to the nearside letterbox and the wing wall. In the background of this photo, the footings for the approach wall have just been dug.



After much huffing, puffing and one or two naughty words, the near-side letterbox was finished.



Caught in the left had side of this photo is the first of the corner stones against which the lock gates will be anchored. Here it is in all its glory fixed into place. A little bit of trimming was necessary on the cut-out portion, but our masonry expert soon put that right with his trusty mallet and chisel



More edge capping stones awaiting installation.



Work on the near-side approach wall has also advanced thanks to the efforts of the WRGs.



Anyone visiting the area over this bank holiday will be able to view the work as the site is now open on Bank Holiday Sunday and Monday (10.00 am - 4.00 pm) - as of yesterday. I believe I am rostered for Monday, so make yourself known if you do turn up. I'll be wearing a name tag just to remind myself of who I am.

 

Been a while since the last update, but that doesn't mean nothing has been happening. It hasn't helped that I lost my camera but the Gods have smiled on me and it has been recovered.

An amendment to the plans meant that work was diverted to building a new mooring wharf at the lower end of the lock. This wharf is an extension of the wing wall shown in picture #4 in the post above. We also have to install a new mooring wharf extension to the upper near-side wing wall, although that will be constructed only of steel pilings.

The extension was started by driving in steel piles and back filling with concrete. No pumps or big lorries this time. The concrete was mixed on site and barrowed to where it was required. Who needs the gym to keep fit?



A considerable number of slate blocks which had previously been laid directly onto the nearside bank, were recovered and re-laid above the concrete-backed pilings. This time, instead of being loose, they were laid on a bed of lime mortar. The gap behind the slate blocks was back-filled with more concrete.



Once the layers of slate blocks were up to height, more concrete was poured to provide a wider surface to allow for the laying of the edge capping stones. We used the capping stones that were previously positioned on the top of the lock chamber - more edge capping stones are being obtained for that part of the job. Those edge stones are blooming heavy and it was a blessing that we could use the excavator to help position them. Under the yellow bucket (left side of the photo) is the outflow of a drain that runs diagonally across the site from the trackbed of the old railway line that used to run alongside the site. Previously, it was a piece of clay pipe that had fractured ends, but the guys have tidied it up and it looks a quite respectable culvert now.



The last edge capping stones were laid this week and all that remains to do on this part of the project is to backfill behind the capping stones, install some mooring bollards and re-instate the towpath. There is still some work to do at this end of the lock in the form of installing some stop-board grooves and associated hardware (in the same manner as we did at the upper end of the lock). Once that is done, it will allow the installation of the stop-planks which, in turn, will allow the temporary dam to be removed and the water return.



After finishing laying the edge capping stones at the lower end, we turned our attention to the upper wing walls where more edge capping stones have been laid.

This is the off-side upper wing wall.



...and this is the near-side upper wing wall. Just a couple more blocks to lay then it will a case of installing the new upper mooring wharf.



Edge capping stones have not yet been laid over the letterboxes as we are still awaiting a decision on the way forward in that area. Apparently some form of access is required to allow the clearing of the letterboxes should an obstruction occur within. At the moment, the letterboxes will remain covered by wooden pallets (on the left of the above photo) to prevent anyone falling into them.

Finally, Iona, one of the C&RT Heritage trainees has left us to return to uni to do her Masters degree. Iona was a very enthusiastic member of the team and has left her mark on the restored walls. She will be missed and we wish her well on her chosen path.

 

Good stuff! Why is (was?) there a batter on the wall by the lock?

 

Please forgive my ignorance. "Batter"??

 

Meaning the wall is built leaning backwards.

 

Thanks for the explanation. I will have to ask someone more knowledgable than me.

That said, up close it looks like it matches the shape of the bow of a narrow boat, so it may have been shaped like that to allow a boat waiting to enter the lock to moor closely to the short mooring wall yet leave enough space for a boat coming in the opposite direction to leave the lock. When we first saw the batter, we thought the wall had collapsed but subsequent examination showed that the shape was intentional as the structure behind had not been compromised - see photo #2 in post 167 above. It will be interesting to see if Lock 14 - the next one to be restored - has a similar feature.

As I said earlier, I will ask. Everyday's a school day on this project.

 

Do you mean the stone wall at the end of the sheet piling in the photograph above, I would imagine it acts as part of the transition from the puddle lining to the brick/stone invert within the lock? Seals at such points were notoriously difficult to maintain as clay moves/expands/contracts at a different rate to stone/brick.

 

I spoke to a man from C&RT and asked about the batter on the lower near-side wall. As I initially suspected, he confirmed that it was to allow a boat, waiting to enter the lock, to leave sufficient passing space for a boat exiting the lock. Apparently it is also a feature on other locks on the canal but usually isn't visible as it is normally under-water.

The GCS volunteers have been very active since the previous report and a major milestone has been reached.

Unused edge capping stones were located elsewhere in C&RT's estate and a team of volunteers were despatched to recover them to the site. Other volunteers set too putting them into place and in a little over a fortnight - job done!!! Apparently, there are enough of the unused stones available to complete the restoration Lock 14 which is the next lock to be tackled.

A couple of photos showing the newly laid blocks along the the lock chamber wall.

The off-side wall.


The near-side wall.


The final block being "persuaded" into position as part of the 'topping out'.



Two GCS volunteers check that the final block has been laid true, level and square.



The completed end wall.



Our attention has now turned to installing the lower end stop-board channels (one of then is just visible below the end wall). Some work is needed to align the slots cut into the brickwork of the lower approach walls before the metal channels can be permanently fixed. We are confident that job will be completed this week. There are still a number of other jobs to be done before the lock is finished, but at least that number is steadily reducing.

 

Since my previous dribblings report, I've been grounded with a bit of a back problem which meant I was house-bound whilst my colleagues carried on their good work. At the moment I'm relegated to tea-making and a bit of fetching stuff but no heavy lifting/navvying.

Our volunteers have successfully installed the stop board channels on both sides at the lower end of the lock. We are awaiting delivery of the oak beam that will be laid between the channels; the stop planks will rest on that beam which will, hopefully, provide a better seal than if the planks were laid directly onto concrete.



Mooring bollards have been installed on the lower mooring wharf and on both sides of the lock chamber. They will eventually be painted black and white to match in with other canal-side furniture across the network. (personal note: if they were to be coloured red and white then I wouldn't touch them with a barge pole).





At the upper end letter-boxes, stone blocks have initially been positioned so that further work can be undertaken. In a departure from the original layout, instead of stone blocks covering the sluice, a grill will be installed to allow access to the sluice should it become obstructed when the lock is back in normal use. Some more work is required to get it right then the work will be repeated on the other letter-box.





The stone blocks with the cut grooves will be rotated through 90º then another groove will be cut to form a recess on which the grill cover will rest after being suitably secured to prevent it going walkabout into the lock.

At the lower near-side corner, the first brick quadrant has been built. When the gates are installed, this quadrant provides some purchase to the person opening/closing the gates. The temporary fencing is made from a load of redundant scaffolding planks kindly donated to us by Wastecycle and generously delivered to the site FOC by John A Stephens Ltd.



A start was made on landscaping the lower end of the lock but it was realised that the gradients were too steep and there was a risk of earth slippage and of falls for towpath users, so additional wing/retaining walls are being built which will allow more gentler gradients. The walls will be supported by concrete infill behind them, stepped in a similar fashion to the main lock chamber walls. The walls will be topped by edge capping stones.





Meanwhile, in the main lock chamber, the scaffolders have started dismantling all the scaffolding which means some more of the restoration has been revealed. It's quite a sight!

From the upper end.


From the lower end.


Apologies for the glare, the sun was in the wrong position.

Once all the scaffolding has been removed, we will have to clean the floor of the lock chamber to remove all the debris/detritus that has gathered/been spilt during the re-build, also it will allow the lock ladders to be installed in their respective recesses.

It's all coming together, but we still have stuff to do - finish the new wing walls, build a mooring wharf at the upper end of the lock, finish the letter boxes, regrade the landscaping, drink more tea, etc. You never know, this time next month we may see even more changes to the scenery.

 

You may have noticed that I have managed to replace nearly all the photos which were lost on the earlier pages when Photobucket spat their dummy out over third party hosting.

It was a bit of a grind trying to match the text with the correct photo, a situation not helped by the fact that some of the original photos were deleted off the SD cards after I had uploaded to Photobucket (doh!!); in trying to maintain the flow of the reports, I have had to insert a replacement photo or amend the text in just a few cases.

Thanks for your patience and understanding.

John

 

Very interesting. Thanks.

I'll bet they were really pleased about that.

A workaround, for Photobucket - pinched from another Forum.

I've installed it on my 'puter [for Firefox] but haven't really tried it. Others have reported successful results.

 

I should have written (my bold):

bearing in mind that the navvies were probably supplied with copious quantities of ale during the construction of the canal.

Thanks for the advice on the Photofbucket fix advice. I deleted my account when I cut my ties with that site - there's no point in having a photosharing account if I can't use the photos.

 

The scaffolding has gone!!

Not my photo - lifted from Grantham Canal Society's web-site.