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Minworth embankment repair


nicknorman

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20 hours ago, nicknorman said:

Hmmmm, came up Minworth today. Glided over the point where we had previously grounded, before coming to an abrupt stop just beyond (slightly nearer the lock). Something solid, mid channel. Felt rather familiar! As we left the bottom lock, I noted significant flow over the weir. Fortunately there was a boat entering the middle lock and after they had started to drain the lock, we were able to float free with much revving of the engine. Disappointing! We were pretty much mid-channel. At least this shallow point is now only a few feet long. Probably if I had been going a bit faster we would have got through, but I had slowed to await the descending boat. Here we are firmly on the bottom with the stern abeam the towpath barrier

 

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Have you reported it again Nick?

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7 hours ago, Victor Vectis said:

We came through yeaterday too and got stuck, briefly, in the same place.

Nowhere near as bad as when going the other way last month but still not good.

 

22 hours ago, nicknorman said:

Hmmmm, came up Minworth today. Glided over the point where we had previously grounded, before coming to an abrupt stop just beyond (slightly nearer the lock). Something solid, mid channel. Felt rather familiar! As we left the bottom lock, I noted significant flow over the weir. Fortunately there was a boat entering the middle lock and after they had started to drain the lock, we were able to float free with much revving of the engine. Disappointing! We were pretty much mid-channel. At least this shallow point is now only a few feet long. Probably if I had been going a bit faster we would have got through, but I had slowed to await the descending boat. Here we are firmly on the bottom with the stern abeam the towpath barrier

 

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Out of curiosity what depth are your boats? We passed through there on Monday and I've always taken our boat to be 2'8" draught so was expecting some problems, but we had none at all. We were going down the flight however rather than up but you say that the water was passing over the by-weir so it must have been at maximum depth.

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1 minute ago, Wanderer Vagabond said:

 

Out of curiosity what depth are your boats? We passed through there on Monday and I've always taken our boat to be 2'8" draught so was expecting some problems, but we had none at all. We were going down the flight however rather than up but you say that the water was passing over the by-weir so it must have been at maximum depth.

2’ 8.5” static (and we were only at tickover). I think there is a pile of stones there and probably if I had been a few feet towards the towpath I’d have missed it.

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2 minutes ago, nicknorman said:

2’ 8.5” static (and we were only at tickover). I think there is a pile of stones there and probably if I had been a few feet towards the towpath I’d have missed it.

Curiously I think I went through a couple of feet to the right (possibly) of where your photo shows your boat to be. You're not bothering to pick any lottery tickets this weekend are you?:unsure:

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As he promised me at the weekend, Richard Parry has now forwarded me the summary from Jane Marriot, the CRT project engineer at Minworth, that shows the huge discrepancy between the work they actually thought they had to carry out, and what it actually evolved into once they were on-site and working.

This resulted in them being under far more pressure that they expected to be if the canal was to be re-opened by Easter.

Nobody from CRT is pretending anything other than a big error was made when they thought that enough material had been removed that boats would be able to pass through, but clearly they wee trying to avoid the criticism they would have got had the canal remained closed.  (I'm also guessing that shallower draughted boats - the vast majority of all boats, probably would have been largely OK).

I don't think I'm being "gulled" here - I believe the following notes, and respect CRT for their honesty in the explanation of what went wrong.

 

Quote

 

Minworth

 

Original planned scope

 

33m of wall repairs

31m x 12m area of bed leak repairs

 

Scope required once project commenced on site

 

33m of wall rebuild including new foundations – significant increase in works required.

36m length x 12m wide area of bed voids repaired with an additional bed void being discovered. This required a huge tonnage of stone (300 I think) to be brought to site to build back the ground beneath the canal bed.

5m coping repairs (carried out by Volunteers)

30m of sand bagging repairs (carried out by Volunteers)

100 tonne of contaminated hazardous silt removed during the works

450 tonne of contaminated hazardous waste, stone and debris removed in the short (4 day) stoppage after the re-opening to

(and 2 safes removed from the bridge approach!)

 

The works were also complicated because of the heavy rainfall during January – with additional pumping required - and the extremely cold weather / snow during February / early March also caused disruption to the works.  We experienced two vandalism events with pounds drained down the flight. 

I believe the outturn cost was close to double the original budget anticipated.

I hope that explains why we encountered some of the problems you are aware of.  Our decision to re-open before Easter was based on a judgement that enough material had been removed (and the remained re-profiled) so that boats would get through.  That proved to be wrong and hence the additional closure required to put it right.

 

 

 

Edited by alan_fincher
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I think one clue is that there is mention of 300 tonnes or so of rocks etc being put into the canal, with only 100 tonnes being removed. In other words, 200 tonnes of material added to a stretch of a few 10s of yards on what was already a pretty shallow stretch. Basic maths tells me it’s going to end up a lot shallower than it started!

 

I wonder how they measure the expected depth after refilling? These days, with rotary laser levels being ubiquitous, you would think it quite easy to put the level in the middle of the canal bed, raised so that the beam cuts the water line on the piling etc, and then wander about with a marked stick and see where the beam cuts it. They must have known, before refilling, that there would be less than 0.8m depth or if not, they should have!

 

And please pass back to Richard that even after the 4 day stoppage, there remains a small adjacent area mid-channel that is 0.8m or less, with a very hard bottom. Although conceivably some new debris added, it seems unlikely to be such as its mid channel and away from any bridges etc. Most probably a little pile of the rocks. We became completely stuck (boat not moving with full throttle reverse or forward) until the lock was drained. Would have been a little embarrassing as we were both on the boat!

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I am less than impressed with CRTs response. Instead of properly assessing of the depth was adequate they seem to have crossed their fingers and hoped nobody would notice. As nicknorman says, its very simple to assess the level. I  hope CRT have learnt something, not least that they should check and not rush.

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4 hours ago, jonesthenuke said:

I am less than impressed with CRTs response. Instead of properly assessing of the depth was adequate they seem to have crossed their fingers and hoped nobody would notice. As nicknorman says, its very simple to assess the level. I  hope CRT have learnt something, not least that they should check and not rush.

I think it is pretty obvious they realise a serious error of judgement was made, and would be amazed if those involved didn't learn from it.

What I have posted seems a pretty fair statement of fact.  They admit they got it wrong, but do you imagine they would have faced no criticism at all, had they concluded that they couldn't remove enough material to reopen the canal for Easter?

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1 hour ago, alan_fincher said:

I think it is pretty obvious they realise a serious error of judgement was made, and would be amazed if those involved didn't learn from it.

What I have posted seems a pretty fair statement of fact.  They admit they got it wrong, but do you imagine they would have faced no criticism at all, had they concluded that they couldn't remove enough material to reopen the canal for Easter?

Your persistence in getting to the real story is really important and I trust that you will continue to do so and not be put off by those who just want to take the opportunity to be cynical. As you say, the present story is entirely credible in the circumstances. Engineering is not science and always involves matters of judgement. Sometimes it doesn't pan out (look at bridges that spectacularly collapsed as a result of pushing at boundaries of knowledge) Progress is made when folk learn from mistakes - anyone who has never made the wrong call has never learnt anything!

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16 hours ago, alan_fincher said:

I think it is pretty obvious they realise a serious error of judgement was made, and would be amazed if those involved didn't learn from it.

What I have posted seems a pretty fair statement of fact.  They admit they got it wrong, but do you imagine they would have faced no criticism at all, had they concluded that they couldn't remove enough material to reopen the canal for Easter?

I take your point, but the implication is that this was a conscious decision. However if it had been a conscious decision and they were attempting to deliver an operable canal ready for Easter, they could have re-opened with a restricted depth, communicated this clearly to the canal users AND issued a plan to have another stoppage to recover the situation.  In the event they reopened the canal with the work apparently complete, no plan for recovery and then the subsequent stoppage appears to have improved but not fixed the problem properly.

 

 

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A part of me does wonder if they decided to fill it up and say nowt, hoping for the best, and to see what happened.

 

And possibly with a view to doing the same elsewhere in future if only a smattering of complaints from known whingers.

 

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Back in the murky recesses towards the beginning of this thread there is a post from Nick reporting a communication from Ian Lane which suggests he had been led to believe by the engineers that there was 0.9m of water depth in the pound. This suggests the engineers & Ian thought this would be an acceptable depth.

 

Disregarding the boats on the canal which require more than this to float standing still it displays a woeful understanding of what happens to a boat as it moves through the water and what happens to the water as it tries to move past the boat in a narrow channel.

 

0.9m was never going to work, boats of less draught than this were always going to be in trouble and that an engineer and a waterways manager didn't understand this calls into question their career choice.

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12 minutes ago, davidg said:

Back in the murky recesses towards the beginning of this thread there is a post from Nick reporting a communication from Ian Lane which suggests he had been led to believe by the engineers that there was 0.9m of water depth in the pound. This suggests the engineers & Ian thought this would be an acceptable depth.

 

Disregarding the boats on the canal which require more than this to float standing still it displays a woeful understanding of what happens to a boat as it moves through the water and what happens to the water as it tries to move past the boat in a narrow channel.

 

0.9m was never going to work, boats of less draught than this were always going to be in trouble and that an engineer and a waterways manager didn't understand this calls into question their career choice.

C&RTs own figures (well actually 'BW Dredging Standards') for the Birmingham & Fazeley states 5.3m x 1.1m minimum, but, they also quote 2mts (6' 6") for the River Trent, and we , at 4' 6" have hit the bottom several times in the 'main channel'.

Edited by Alan de Enfield
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