Dredging on the Cannock Extension

[springy]

Today on the Cannock Extension - Canal and River Services Dredging and offside overhanging trees have been cut back

 

springy

 

[matty40s]

....

'bout time, I complained in December 2015 that Baldock had stuck and I had to employ the services of a local signwriter who happened to be passing by to help me over the silt/leaf mounds.

Cheers Dave Moore

[BEngo]

If the 'dredging' is to a similar standard to that through Brockhall Spinneys and from Horton to Soulbury on the GU you will not notice much difference next year and none in 2023.  Both stretches are now as bad as they were before the dredging.  No doubt Land and Water made a load of  money though.

 

N

[JamesWoolcock]

As  I understand it, it's not so much the contractor doing an indifferent job, but the specification they are given in their contract with CRT, such as not dredging the full width and thus what is left slides down into the now deeper channel. This happened when Land & Water dredge from Fradley Junction to Streethay on the Coventry Canal a year or so back. True that the really bad bits held up longer ,but all in all a waste of time, money and opportunity. That's what happens when you do a job on the cheap.

[fanshaft]

On 01/12/2021 at 10:51, BEngo said:

If the 'dredging' is to a similar standard to that through Brockhall Spinneys and from Horton to Soulbury on the GU you will not notice much difference next year and none in 2023.  Both stretches are now as bad as they were before the dredging.  No doubt Land and Water made a load of  money though.

 

N

Land & Water have to bid for the national contract against other operators so I doubt margins are especially generous. 

[fanshaft]

On 01/12/2021 at 11:27, JamesWoolcock said:

As  I understand it, it's not so much the contractor doing an indifferent job, but the specification they are given in their contract with CRT, such as not dredging the full width and thus what is left slides down into the now deeper channel. This happened when Land & Water dredge from Fradley Junction to Streethay on the Coventry Canal a year or so back. True that the really bad bits held up longer ,but all in all a waste of time, money and opportunity. That's what happens when you do a job on the cheap.

That's an important question James - and much debated within the CRT dredging group.  We have c £8 million to spend annually (so not very cheap!)and allocate it according to reports from the Trust survey teams and from interested users such as the commercial operators, HNBC etc.  Do we recommend a comprehensive dredge at a smaller number of locations to the fullest spec i.e. full width (assuming that is possible which it isn't always) or at more locations /longer lengths just dredge  the 'box' section that allows boats of a certain width and depth to pass each other (typically for the narrow canals a loaded coal boat) but risk 'slip back' into the channel over time?  It wasn't such a problem when loaded boats were regular and the norm as they kept the channel clear and the silt to each side.  One problem now is that many pleasure craft skippers are unaware there is a channel and the need to keep to it - some even 'keep to the right' all the time thus encouraging the silt back into the channel.  I will mention Fradley to Streethay at the next meeting.

[JamesWoolcock]

PM sent 

[BEngo]

Fanshaft, 

 

Whether to dredge properly to original profile or to  do the minimum job has long been debated.   

 

Both approaches have the same basic quantity of muck to be removed. Leaves, towpath mowing, bank damage and inflow from streams etc.  are not much changed by the frequency or extent of removal of silt.

 

Original profile is undoubtedly more cost effective.  Typically,  once dredged, the waterway will not require re-dredging for 10 -15 years.  One set of set up costs is thus  spread out over 10 -15 years.  Plus muck disposal costs for 10 -15 years worth of muck.

 

Minimal channel is headline attractive, because a greater mileage can be claimed.  Unfortunately it means repeated dredging at shorter intervals.  Each bout of dredging incurs set up costs so if minimal dredging lasts 5 years the money spent on set up is 2 or 3 times as great as for full profile.  Since there is a fixed pot of money for dredging, if there is more money spent on set up there is less overall spent on actual muck removal, even though the muck disposal cost per dredge is lower.

 

One is better for boating, and for water  management, one allows the management to  claim they have done more.  No surprise which one CRT like.

 

Streethay to Fradley is a bit of a struggle, again,  particularly the bridgeholes but it is not silt IMO.  The stretch has a lot of waterside vegetation and the leaves all end up in the cut, but do not rot very fast so they fill up the narrow, minimum depth channel.  There is no real answer to that as even a wider deeper channel will fill up in a couple of years.  Unless of course the vegetation is cut back away from the cut,  not just to a vertical plane from the offside water edge.  

 

N

[Rob-M]

The leaves at Wood End lock were terrible last week, trying to get in and out of the lock using the engine was very difficult.  I ended up bowhauling in and out having watch a couple of other boats struggle.

I think it is Bridge 88 before Fradley that is always bad for getting through.

[fanshaft]

Just to clarify - dredging is discussed and agreed by the volunteers and CRT staff within the dredging sub-group of the Navigation Advisory Group.  CRT managers do not press the group members to agree to dredging which shows a greater mileage or quantity of silt removal for its own sake  as you suggest. That would not be acceptable.

 

[BEngo]

7 minutes ago, fanshaft said:

Just to clarify - dredging is discussed and agreed by the volunteers and CRT staff within the dredging sub-group of the Navigation Advisory Group.  CRT managers do not press the group members to agree to dredging which shows a greater mileage or quantity of silt removal for its own sake  as you suggest. That would not be acceptable.

 

They have no need to.  CRT control the contract with Land and Water, and the specifications for each dredging.  These are either  not set up to require full profile or the requirements are poorly expressed.

Either way the need for re dredging comes around sooner than it need.

N