Canal Closed

[nicknorman]

 

I'm not trying to play the awkward card here Lawrence, nor am I coming down on either side of the arguement as to whether the stoppage is due to vandalism or lack of maintenance but I'm having great difficulty getting my head around your 'tidal wave'. How exactly would that happen. I can understand that a ;lot of water would have been released and may well have ended up in roadways and resident's houses if three pounds were to be drained over a period of time, but I would have thought it beyond the wit of the average scroat to do this in such a manner as to create a tidal wave. I genuinely would welcome your explanation as I'm sure it would help me the next time I have to refill the top five pounds of the Northampton flight. The last time I cruised up it, it took me four hours to do the last five locks and even with all paddles and bottom gates open it took a hell of a long time to reach the top of the gates of the next lock down.Surely at any one moment in time, you can't have a flow volume any greater than that able to pass through the paddles of the topmost lock being drained other than by careful management of the paddles on the lower locks?

Open top and bottom paddles of lock 16. That drains the pound above to the pound below, and it starts to run over the bywash weir of lock 17. Now open the top and bottom paddles of lock 17. So going into the pound below lock 17 you have the flow from the paddles, plus the flow from the weir. When that arrives at lock 18 it cannot be accommodated by its bywash, so it starts to overflow the lock. Now open the top and bottom paddles on that lock as well, so what arrives at lock 19 is way too much for the bywash and there is significant flow over the lock structure, which is presumably what caused the damage. Fast flowing water is a very powerful weapon!

Edited June 25, 2013 by nicknorman

[alan_fincher]

Either would do.

To try and take the guessing out of it, (unless Allan knows), I have emailed Stuart Mills to see if he can provide more detail on what is, and is not, included in the Investment Property income section of the bar graph used at his presentation in February.

 

(Last time I asked Stuart a question the answer took quite a while to arrive, though!)

[sueb]

But this lock was already the subject of regular inspections by paid staff, who presumably know how to spot defects that are openly visible.

 

According to Vince Moran inspections had not shown it to be a lock any more at risk than many others.

 

I think to predict which locks are about to fail spectacularly you would need more than volunteer ex-engineers giving them an "eyeball", however thorough that "eyeball" was.

I suggest it needs more than just looking at. It needs a person with a hammer to sound the walls and any other equipment that can look for faults

[churchward]

I suggest it needs more than just looking at. It needs a person with a hammer to sound the walls and any other equipment that can look for faults

And they do. Inspection doesn't just mean having a quick look.

 

However just hitting the wall with a hammer isn't going to do the trick. The void that may be forming behind the lock wall is likely to be 6ft or so away from the lock wall face and with the thickness of the wall you are not going to tell what is there.

[Tuscan]

And they do. Inspection doesn't just mean having a quick look.

 

However just hitting the wall with a hammer isn't going to do the trick. The void that may be forming behind the lock wall is likely to be 6ft or so away from the lock wall face and with the thickness of the wall you are not going to tell what is there.

 

 

Out of interest can you confirm what the inspection regime is for a lock in this category?

Edited June 25, 2013 by Tuscan

[richardf]

Is there a technique for filling these voids - some sort of forced grout technique for example?

[Timleech]

Is there a technique for filling these voids - some sort of forced grout technique for example?

 

I think they have done that in the past, no idea whether or not it's a currently favoured technique.

 

Tim

[Pluto]

He was just playing at it, a cowboy builder who took year and years to complete a small job. In ancient China, large canals for river transport had already been established. The longest being the Grand Canal of China. Which is still the longest canal in the world today, and the oldest extant one. Which is not bad considering that it is over 1100 miles long. The project began in 605 and was completed in 609. Even in its narrowest sections it is rarely less than 90 feet wide. Imagine building a canal 1100 miles long and a minimum of 98 feet wide in just four years. Then some 1400 years later is is still in daily use. All on a bowl of rice a day.

 

regards

 

Mick

Actually, part of the Grand Canal near Yangzhou could date from 400BC, though this was part of the original line of the canal which was extended and completed circa 600AD. The route was completely changed circa 1250AD. The oldest surviving navigation canal in China is probably the Lingqu or Magic Canal, a summit level canal built around 220BC. It was around that time that canals for irrigation and navigation began to be built in Mesopotamia (Iraq), and the Egyptians were also working on canals and inclines based on the Nile not that long afterwards. There was also the Xerxes Canal in Greece, so canal building was being undertaken in most of the 'civilised' parts of the world by 200BC.

And they do. Inspection doesn't just mean having a quick look.

 

However just hitting the wall with a hammer isn't going to do the trick. The void that may be forming behind the lock wall is likely to be 6ft or so away from the lock wall face and with the thickness of the wall you are not going to tell what is there.

At one time, maintenance inspectors would carry a good walking stick through which they could listen for any water flowing underground. I have also used dowsing to find underground watercourses when working on water mills. It has always been effective for me. I can remember the Section Inspector at Burscough, when I first became interested in canals circa 1970, saying that he had to walk and inspect his length once a week, though I suspect that the widespread introduction of maintenance vans shortly after put an end to that.

[pearley]

Just received this email from Brenda Ward:

Hi All

Please find below an update from Dean Davies West Midlands Waterway Manager on the Wolverhampton lock 20 problem. Whatever the cause it would seem there was no apparent problem in March when the lock was inspected. See attached photo.

Regards

Brenda

 

Just a quick update.

 

Further to the incident last Friday when we were forced to close the navigation due to the partial chamber wall failure at Lock 20 on the Wolverhampton flight we have met with May Gurney and their sub-contractor, Hills, to agree a way forward.

 

Following the incident we have also taken our local Engineering Manager, John Ward, to site and he agrees with our suspicions that this was trigged by the act of vandalism on the flight the previous day and with our reactive actions.

 

To summarise our actions following this site meeting:

 

· May Gurney to fence off the lock today 25/6 to prevent unauthorised access to the site,

· MG/CRT to design a prop system to help retain the structure,

· Possible site start on Wednesday for installation of the prop system and removal of brick sheeting and coping stones,

· Site meeting also arranged with Heritage advisor and contractors for Wednesday to discuss the detailed repair solution and any consents required. We hope that as it is an emergency job they will not require these. However the lock is Grade II listed so we just need to make sure the conservation officer is happy.

· Following the meeting on Wednesday we should have a better idea of timescales, method and delivery mechanism,

· Emergency Environmental Appraisal submitted today,

· A Project Manager has been appointed,

· A full works information package is being prepared ready to handover to Project Manager. After Wednesday’s meeting we hope that this this can be firmed up with a formal start date for the full works agreed

· John Ward to raise an authorisation request for around £80k to cover the works,

 

I think that it for now but as I hear things I shall keep you updated. I’ve also copied in a photograph of the lock taken in March – which shows there wasn’t any outward signs of a problem then i.e. no cracks evident.

 

I will let you have some more information as I get it.

 

Regards - Dean

 

 

Dean Davies

Waterway Manager

West Midlands Waterway

[churchward]

 

 

Out of interest can you confirm what the inspection regime is for a lock in this category?

No I don't specifically and in particular what they do now it is CRT.

 

However lock inspections can range from emptying and just looking to canal closure and fully draining pound to see the full extent of the brickwork. I believe they use some kind of sound scanning gear to find voids either like ground survey equipment ie wacking the ground and seeing what the sound echo looks like or ground penetrating radar something like you see on "time team". They take measurements of the walls to see if there is movement between inspections and take not of any cracks for potential subsidence. I did see a strain gauge on end wall of a lock structure once too. It is also possible to use a strong dye in the water and see where it goes and comes out although I have not see this done in a canal context.

Is there a technique for filling these voids - some sort of forced grout technique for example?

I believe you can drill down and back fill with concrete or indeed dig and back fill. Water tracking through mortar joints in the thick lock walls I imagine is much harder to remedy but I suppose possible not heard of it being done.

[RLWP]

Dean is on the case - not only sorting the lock, he's communicating to boaters as well

 

Richard

[churchward]

 

Just received this email from Brenda Ward:

Hi All

Please find below an update from Dean Davies West Midlands Waterway Manager on the Wolverhampton lock 20 problem. Whatever the cause it would seem there was no apparent problem in March when the lock was inspected. See attached photo.

Regards

Brenda

 

 

Thanks for posting the update. It is good to have some facts.

[lydfordcastle]

Open top and bottom paddles of lock 16. That drains the pound above to the pound below, and it starts to run over the bywash weir of lock 17. Now open the top and bottom paddles of lock 17. So going into the pound below lock 17 you have the flow from the paddles, plus the flow from the weir. When that arrives at lock 18 it cannot be accommodated by its bywash, so it starts to overflow the lock. Now open the top and bottom paddles on that lock as well, so what arrives at lock 19 is way too much for the bywash and there is significant flow over the lock structure, which is presumably what caused the damage. Fast flowing water is a very powerful weapon!

 

It is indeed but I still can't see a the procedure outined above producing a 'tidal wave' of fast flowing water in a manner or on a route likely to cause the damage shown in the photographs. Perhaps someone has witnessed this phenomenum but until this 'tidal wave' theory can be proved or witnessed I prefer to believe the much more likely explanation that the damage is due to a flow and turbulence over a period of time occuring behind the lock wall. The worrying feature is that if the one-off 'tidal wave' theory is correct, the problem could easily happen again only a few days after it has been fixed and CaRT could have an ongoing battle on their hands with the local scroats.

[magpie patrick]

 

It is indeed but I still can't see a the procedure outined above producing a 'tidal wave' of fast flowing water in a manner or on a route likely to cause the damage shown in the photographs. Perhaps someone has witnessed this phenomenum but until this 'tidal wave' theory can be proved or witnessed I prefer to believe the much more likely explanation that the damage is due to a flow and turbulence over a period of time occuring behind the lock wall. The worrying feature is that if the one-off 'tidal wave' theory is correct, the problem could easily happen again only a few days after it has been fixed and CaRT could have an ongoing battle on their hands with the local scroats.

It's happened before, the Falkirk Wheel had trouble shortly before it opened with Vandals forcing the paddles on the two rise above it and washing away significant volumes of earth. Because that was brand new, the structural concrete wasn't damaged (and being RC is wasn't likely to be) but run that over the back of a brick wall and problems start to occur.

[Allan(nb Albert)]

Allan what do you think might be included in the gross income?

I'm afraid property income figures are like visitor numbers. They change according to the circumstances!

 

However, I do have an actual net contribution figure for 2010/11 which was £19.6m for property. This does not include BW's losses on joint ventures which drag the figure even further down to about £17m.

 

Comparable figures for BW's other two main income sources, Leisure (mainly boating) and Utilities were over £22m each.

 

Having said that the situation should have improved greatly over the last two years due to having disposed of loss making or simply unprofitable joint ventures and better performance of property generally.

 

 

 

 

 

 

Edited June 25, 2013 by Allan(nb Albert)

[dmr]

The Caan Hill flight, which is not prone to vandalism, has a padlock on the top and bottom lock each night.

As Wolverhampton is prone to vandalism, and local rumour has it that said vandals possess a handcuff key, then maybe its time to do the same on the Wolverhampton flight, plus padlocks on every third or forth lock all the way down. There is a CaRT yard at the top so someone can cycle the flight at the start and end of each day to unlock and lock.

Lets say 3 hours labour each day at £50/hour, that's £27,000 pa.

Make it request only out of season, and recruit some brave volunteers, and the cost could be under £10,000, that's a lot cheaper than a £80,000 repair every few years.

 

No great inconvenience for boaters as I assume no sane boater does this flight at night.

 

.............Dave

[RLWP]

 

No great inconvenience for boaters as I assume no sane boater does this flight at night.

 

.............Dave

 

I bet you are wrong

 

Richard

[Semitrad]

So as far as I can deduce, the collapse has been caused by pressure behind the lock wall forcing it into the lock. Very likely to be water pressure. There must have been a void behind the wall, otherwise the water could not have got there. In normal operation, the water remaining in the void when the lock was emptied had only a slight effect on the lock wall, causing a small crack which had been previously filled.

 

With the flood, (tidal wave?) however, the void filled to a higher than normal level and when the lock was emptied the extra water and leverage at the top of the wall was the straw that broke the camel's back.

 

The wall of the pound above Napton bottom lock had a slight bulge for some considerable time with no effect until the pound was drained for maintenance.

 

[dmr]

 

I bet you are wrong

 

Richard

 

I concede that one, we set off at 4am one day last year to get through a "bad bit", it was all very pretty at that time of day but it took me a week to recover!. Still waiting a couple of hours for the padlock to come off is less inconvenient than waiting for CaRT to refill a flight of locks, and much less inconvenient than waiting for a lock wall rebuild.

Maybe established CaRT customers could get a key sent to them on request!

 

................Dave

[RLWP]

it seems a pretty extreme solution to a very rare problem

 

I suppose I am just fundamentally opposed to a nine to five canal system

 

Richard

[Tom and Bex]

I suppose I am just fundamentally opposed to a nine to five canal system

 

Richard

Same here. A few years ago we spent much longer than planned at the black country museum and had to get our hire boat back to autherly junction the next morning so got to the bottom of the flight at 10pm.

 

I feel there are already far too many lock flights locked overnight and strongly object to any suggestion there should be more. This doesn't just apply to lock flights of course but any restricted hours on the canal system takes away some of the enjoyment out of a cruise.

[Little Else]

We often set off early or finish late,last time we did the 21 we started just after 6am in the snow. In the summer we have done it in the last of the evening sunshine.

[Tim Lewis]

From BCNS Facebook Page:

 

 

 

Just a quick update on Wolverhampton Lock 20.

Further to the incident last Friday when we were forced to close the navigation due to the partial chamber wall failure at Lock 20 on the Wolverhampton flight we have met with May Gurney and their sub-contractor, Hills, to agree a way forward.

Following the incident we have also taken our local Engineering Manager, John Ward, to site and he agrees with our suspicions that this was trigged by the act of vandalism on the flight the previous day and with our reactive actions.
...
To summarise our actions following this site meeting:

· May Gurney to fence off the lock today 25/6 to prevent unauthorised access to the site,

· MG/CRT to design a prop system to help retain the structure,

· Possible site start on Wednesday for installation of the prop system and removal of brick sheeting and coping stones,

· Site meeting also arranged with Heritage advisor and contractors for Wednesday to discuss the detailed repair solution and any consents required. We hope that as it is an emergency job they will not require these. However the lock is Grade II listed so we just need to make sure the conservation officer is happy.

· Following the meeting on Wednesday we should have a better idea of timescales, method and delivery mechanism,

· Emergency Environmental Appraisal submitted today,

· A Project Manager has been appointed,

· A full works information package is being prepared ready to handover to Project Manager. After Wednesday’s meeting we hope that this this can be firmed up with a formal start date for the full works agreed

· John Ward to raise an authorisation request for around £80k to cover the works,


I think that it for now but as I hear things I shall keep you updated. I’ve also copied in a photograph of the lock taken in March – which shows there wasn’t any outward signs of a problem then i.e. no cracks evident.

I will let you have some more information as I get it.

Regards - Dean
Dean Davies
West Midlands Waterways Manager

[magpie patrick]

it seems a pretty extreme solution to a very rare problem

 

I suppose I am just fundamentally opposed to a nine to five canal system

 

Richard

 

So are the IWA, who favour a minimum of "dawn to dusk" operation. This influences any restoration proposals, or at least any I make, as I avoid solutions that need staffing if at all possible.

 

Vandalism resulting in successive pounds being drained is rare, for this to lead to the near collapse of a lock wall is even rarer.

 

For some reason blaming CRT for 200 year old infrastructure being less than "as new" is surprisingly common. I propose that, before anyone is allowed on the canals, they are gagged and tied to a chair before listening to a slide show lecture on the history and operation of the canal system...

[churchward]

For some reason blaming CRT for 200 year old infrastructure being less than "as new" is surprisingly common. I propose that, before anyone is allowed on the canals, they are gagged and tied to a chair before listening to a slide show lecture on the history and operation of the canal system...

Good idea!!