Drained ! The Pontcysyllte aqueduct. A ten year event !

[Music] [Music] oh [Music] hello my name is Martin welcome back to another video I'm here at world heritage site we're going to look today at the the pka Aqueduct right I struggle saying that I'm not going to say it anymore because it's an insult to the Welsh people and the Welsh language so I'm going to refer to it from now on as the aqueduct but it's a world heritage site look at it it's there it's absolutely amazing we've got an here from the YouTube channel trekking and exploration so today we've been invited by the canal and River trust to go beyond the gates and take a look at the aqueduct in its drained State and trying to see how Telford designed it and how he put it together it's a very unique thing it's only it's only drained once every 10 or 20 years this so we're very privileged so let's go beyond the gates so here we go once every 10 20 years are we dead when they do this again look at that one small step for a man one giant leap for m zero this is incredible to be down here in the actual trough so the first thing I wanted to show you was the stop boards that holding back the rest of the canal uh theyve put stock boards in here seal it with Ash believe it or not um and they hold back the canal and then as we walk in where normally that will be full of water we're basically in a cast iron tank built in segments that is also bolted together if we look down here uh you can see the bolted sections together it's actually very simple design to be honest with you so I actually thought when we came here I've was always terrified this uh Aqueduct because of the height and you see the boats going over and you stand on the edge of a boat you hear the drop below is terrifying because it's 5'3 deep I've not actually to to suffer the views although the views are fantastic but I'm not actually me vertigo is not kicked in so this week we're in North Wales and the nearest town to the aqueduct is rexam so this is a UNESCO world heritage site and the canal and River trust are custodians of this wonderful structure and I'm very grateful that we've been invited along today to uh take a look at it the aqueduct spans the river D it was constructed over 10 years between 1795 and 1805 during the canal build in frenzy it's 336 yd long 12T wide and 5' 3 in deep it's 126t high it's basically a cast iron trough supported on arched iron ribs and carried on 18 Stone pillars right come and look at this you see how it's bolted together here 11,000 bolts in the aqueduct and uh there's one of them there we actually get to see part of the way it's constructed and this will be repeated all along the the peers the stone peers so I'm going to give you a closeup now of that and then you'll know how the uh Iron Work fits to the stone and it give you an idea of construction and what it's like and I've got I think I've got some drawings that will show you how that is all fitted up you can see that uh it's actually Hollow underneath and obviously that makes it nice and lightweight r or reduces the weight on the peers but who do you get to build such a massive project as the canal the aqueduct and all the associated Earthworks well a dream team was put together and that team and I'm reading notes was Thomas Telford as you may know but there was other Engineers involved as well William Jessup now it sounds like William Jessup was a little bit older and a little bit more experienced than Thomas Telford and they kind of worked together and very much respected each other but for the aqueduct who would provide the metal work for such a project well there was a gentleman called William Hazel Dean and he was a master of iron work and he got the contract to provide all the iron work and John Simpson was the chief masonry contractor so those four names became the Dream Team to build the aqueduct now all these four men were very very well educated and Masters in their field it was very very much a group effort and they all had a mutual respect for each other and although telford's name is mentioned with the aqueduct it was very much down to these four men William Jessup seems to be in a consultancy role and he was an older gentleman and he was the master Canal engineer at the time they were very grounded and they had they had a quite a quite a concern for the people that would be working on the project the the guys up top doing the masing work and the iron work and of course not forgetting the Navies that would actually do all all the digging work and everything with him I'll give you an example of of the sort of like the spirit of Thomas Telford I'll quote you this now imagine Thomas Telford he's got multiple projects going on around the uh around the country and he had to travel and visit them and probably on Horseback or horse and car at the time so this is an account of when they stayed at a port in um so when he paid the bill when Mr tord paid the bill he gave the poor girl who had been a waiter chambermaid and probably cook in Chief a 20 Shillings bill I shall never forget the sudden expression of her countenance and her eyes when she understood it was for herself so there you go he's obviously paid somebody very handsomely for their services a very poor person and I just wanted to tell you that story because I wanted to put a humanity and and give you an maybe even though small insight into the nature of uh the people that were talking about that built this wonderful structure right so there you go there's the uh the toe path this is where the public would normally walk uh you can see the painting work here being done um this would terrify me I think it would terrify me if I was on a boat on that side um look at the views and you can see the valley here that they had to span from that side over to this side so this is Mark Abraham from the canal and River Trust Construction manager mark what is the purpose of the the work to on the aqueduct so what we're doing actually today this is all part of a grand maintenance schemes throughout so what we looking at doing so over the past four or five years what I've been looking at we've been replacing the handrails on the side because obviously the handrails like everything else need maintaining so due to the stoppage season we our main works are done between any between October right through to March the aspect of this time around is this is for a princial inspection so we actually dewatering the whole lot to look at the the bolts and all the mechanics and all the iron work to see what grade it is we will then then take patterns from those bolts as 11,000 bolts in here and then we'll make a decision of what we're going to replace whatever we replace we've got to try and make good and put back to for future generations and and do it forward so each time we take a bolt or a stay we'll then find out what material that's made and then we'll actually literally get a shopping list so when we come back in 2026 and eventually leave water again we've got everything on the Shelf ready to be fitted with the correct permissions as we do it brilliant so as you can see this side looks like it's concrete here it's actually not that'll just be a coating of uh mud and silk that's that's on it it looks like it's spray treat but it's not uh and every couple of feet as you can see here we've got the joins between the uh what I want to call the tank basically the truck so as you see it's joined up here every so often and we have to step over it and you can see here there's big uh huge bolts there you go you can see the bolts better in this this uh this footage here now as you can see the arrangement is this this tank that we're in was bolted together in segments so how did you make those segments watertight in 1795 SL 1805 you know in that around about that era what did they do to make it watertight well it's fascinating so what they did they had to use at the time what they had and they what they did was they took Welsh flannel which is obviously material and they dipped it in boiling sugar I presume this made it extremely sticky and tacky and they put that in between the the sections of tank and they bolted it up tight together and it all must have set and uh it made a watertight seal which I think as far as I'm aware is still working today some accounts that look at uh it'll say it was well schannel with white lead um and iron particles so I presume I'm guessing they tried various methods but hey ho it's still watertight today so the toour path now is uh obviously uh iron it's metal this used to be a wooden tow path and if you can imagine back in the day all the workers that used to come across here and horses pulling bols across here you may have noticed these RW iron Loops just on the floor of the the tank they were to do with the original um wooden tow path they're now redundant but that's what they're for John Simpson the stonemason uh used golden Limestone for the project quarried nearby it was said to be of an excellent quality imagine how deep they go down the foundations for them sat on the Bedrock probably so Mark I've seen pictures online of a big plug hole and we were looking just down here at sort like a a mechanism could you tell us how you drain the water from the aqueduct yeah so this time what we did is actually the sock planks are put in either side and we used man-made pumps now as Mark says even though this time they use pumps to pump out the uh the aqueduct they have in the past used a plug hole which would be a spectacular thing to see um while we were there said plug hole was being looked at and they were doing maintenance on it so that perhaps next time they drain the uh the aqueduct they can use it so this is the guys from the canal River trust doing some maintenance on the uh I call it plug hole I want of a better word so there you go and one of the things they've got to think about before they use that plug hole is they've got to test the water in the tank in the aqueduct to make sure there's no contaminants because you don't want to drop any anything down into the river D down below that might contaminate [Music] it so obviously when the canal came to the valley here um it was a daunting task what do you do how do you get a canal across this Valley across the D Valley well initially they were going to build a set of locks down the valley and build a lower level Aqueduct um and that was they went with that for a while but Thomas tford had a lot of faith in his ideas mathematically he worked it all out he' worked out the materials and he decided that he could build an aqueduct at a higher level and make the canal uninterrupted across the valley and that's what they wanted it was called The Stream in the sky when it was finished and so rather than the locks that would have hindered the process of the goods going across the he built his Aqueduct so even today we Marvel and Splendor at the aqueduct I think it's a wonderful thing but we aren't the only ones that appreciate it throughout history it's been appreciated and it's been admired the Scottish novelist Sir Walter Scott declared it the most impressive work of art I have ever seen and the American writer Washington Irving called it stupendous engineers and scientists were equally impressed in 1816 the French engineer Charles dupan called it something Enchanted a supreme work of architecture elegant and unadorned the scientist Michael Faraday crossed the aqueduct in 1819 noting that it was too Grand a thing to be hastily passed the skills of British Canal Engineers were now sought overseas and all around the world but let's not forget although we admire it as a piece of art why it was built it was built for business and it was built to trans Goods the area was rich in Coal iron o clay Limestone and slate and all this needed to be sold to the rest of the country and then it had value when they floated the shares in the canal not I'm not talking about the aqueduct now I'm talking about the whole Canal when they floated the shares um everyone had to go down to shrewbury to buy shares it was reported that the that shrewbury the night before the meeting for to buy shares was so crowded that accommodation was very difficult to come by several gentlemen being obliged to take care of their own horses cook their own meals and sleep two or three in a bed my God the shame say well this is what I love about round a cuz all the oldy worldly things look at this look at the way it's been eroded or worn down cuz loads of people over the years have done this hey now although we haven't got James here to make a brew we did find a very very nice nice te- room just across from the aqueduct it's a chapel but it's actual Aqueduct tea rooms which is very nice um and it's very civilized here we're having a a pot of tea for two of coffee this is called bar bar something it's like well fruit bread bar bread bar some yeah well won't try and offend everyone in wales's having a French coffee French filter coffee likes that where's James when you need him man I know missing out James slap up meal James slap up meal in order to get the stone down into the valley a counterbalanced tram Road was constructed as the peers got higher they also constructed these wooden walkways in the sky it must have been absolutely terrifying working up there and obviously no safety ropes or anything like that this concern for safety was reflected in a letter that William Jessup wrote to Tom Thomas Telford in 1795 he writes in looking forward to the time when we shall be laying the iron trough on the pears I foresee some difficulties that appear to me formidable in the first place I see the men Giddy and terrified in laying stones with such an immense depth underneath them and apparently one man fell now they prided themselves that only one man fell during the whole construction um some reports you you read uh they say no men fell but apparently according to what I'm reading somebody did fall off one of the peir now the trough just sits on top of the ribs and it's not fixed to them it's just prevented by lugs and its own weight from moving sideways and coming off all together also when you look in detail you'll see lug holes on the non handrail side of the aqueduct and that is just because all these plates were just built ident ially so it didn't matter which side of the trough they went on so Mark the aqueduct over 200 years old you're an engineer what do you think about the condition of the structure and and how do it stand today yeah it's very good I mean if you look at it you look at the bolts and you can actually see so you see some bolts in here that's 200 years old and I say to him look how do you get a comparison how do you grade it simple thing you look at one that's 200 years or you look at two one that's in 2003 or in between if one bolts on there you can see and it's degrading but that's degraded over 200 years so that bolt beside it is only 60 70 years you can say that's got another 100 years to go so it's almost partly guess what but you can physically see it from the erosion of the actual Bolt from Bolt to bolt we got some bolts in here it's are 200 years and you can actually see that one is better than the other what's that caused by didn't have quality control back 200 years so so each one is going to have its own characteristics but when you look at the ones have been replaced they appeared years you can almost grade him by years and you thinking look that was put in recently that's looking good that one's 200 years old still looking good so you can grade them say that's got another 40 50 years in that's got another 10 years in it as we're grow and evolving we're trying to make sure that whatever we put back in there as as original as possible wow so you can actually age of Bolt yeah age of bolts fantastic age of Bolt and incredible fact even 16 years after the aqueduct was built Thomas Telford wrote a letter and in it he said we are very vexed at the fact that there is still settlement in the uh The Columns so even though we've used the finest grit and we've gone put put the foundations right down onto the Bedrock there is still settlement and it must have been on inspections it must have been causing a little bit or the saw movement and uh so 16 years after the entire thing was still moving and settling okay so this is Mark Summerfield Heritage advisor Mark I've got a very very geeky question for you okay far away I do understand that part that most of the aqueduct is cast iron that's right however there is some raw iron in it where in this structure would you use raw iron and why would they use the combination of two so you would use RW iron in in places where you need malleable material so essentially things like um the stays were RW iron not not the uprights but the stays that hold them in place cuz RW iron is is stronger but flexible so it's made of fibers of metal so it's stronger and flexible so where you needed where you needed the metal to kind of have some give then that would be the case got the panels are cast iron because you you couldn't you couldn't make you couldn't make these panels at that scale you know it's a new technology so you were making cast iron panels at this size to ensure that you could build this very big maano kit and then bolt it together when you got it to side all this was made just down the road there and then brought to the sighting bits and then bolted together just like it would have been a MAO set Supply by Mr hazeline is that correct that's right that's the o is that original yeah yeah wow and if you look along you'll find a number one a number two a number three a number four and they are component parts that were marked so they knew exactly where they would go when they got on site bolted them together just like moo that is incredible thank you very much that's right now much of that meano set and indeed a lot of the um masonry would have been put together or worked on here a place called Trevor Basin just beyond the aqueduct this would have been a kind of like Goods in section of the building site this was where they kind of like the Hub of all the activity so a lot of stone got brought here was cut and then was got just sent down a short way down there to the aqueduct so 1795 onwards to 1805 this would have been a hive of activity and no doubt Mr Telford and um his various Associates would have strolled down here inspecting the work that was taking place and then just off the base is this which had us very confused um went inside it just filled in at one end it was a Spur off the Basin um and it went off I think to a works now I'm not going to go into that but here it is on the all maps it was a Spur off the Basin maintenance can you imagine the costs of maintaining and keeping this structure in pristine condition the canal and River trust are custodians of this UNESCO world heritage site and they want to see it obviously survive for generations to see and I'm obviously I'm in love with the thing now as well um there is a crowdfunder because the canal River trust are a charity and they are trying to raise some money to do the work the necessary work that needs to be done if you feel like dropping a couple of quid you can do I'll drop the link to the uh crowdfunder in the description to this video and I'll pin it in the first comment in on this video as well I've um left him a few quid and I think I got a little certificate to say that I'm a minor stakeholder in the the aqueduct well it's been a fantastic opportunity to visit and see the work going on and to see the aqueduct in its drained State and I have to thank the canal and River trust for inviting me along um all that's left for me to do is take a walk along that tow path uh in summer probably and admire the views because uh we were so concerned with what was going on down in the tank I actually never walked the full length of the tow path so uh I need to I still need to do that I need to go back and do that I might do it on a warm summer day and if anyone's sailing over there I should very much like to hit your ride uh and experience what it's like to look down from your canal boat um on that side of the uh the aqueduct so give me a shout if you're sailing across anyway I hope you enjoyed that I would like to thank the canal and River trust for inviting us down and getting us to do that once in a decade opportunity W it thank you very much for watching take care we'll see you in the next video bye for now

Channel: Martin Zero

Views: 232,622

Keywords: Pontcysyllte aqueduct, Pontcysyllte aqueduct drained, Canal history, canal engineering, Canal documentary, Thomas Telford, Georgian canal building, Welsh canal, Martin Zero

Id: JO_lZtX0Kf0

Length: 23min 4sec (1384 seconds)

Published: Sun Mar 24 2024