David Cragg <[EMAIL PROTECTED]> wrote:

>On the S&W they seem to use two systems. The one used above Compton previously 
>was mallet man installing (we assume) coir rolls held to the old bank with the 
>stakes. The system used below Compton on the offside involves stakes and wires 
>(with anchors in bank) with a black porous material being installed, 
>(narrowing the channel by anything up to a quarter in places) then dredgings 
>are dumped behind the material. 

Where the bank has eroded away (and in some lengths of some waterways
this has happened to an amazing degree), it may be considered a good
thing to recover the original line of the bank as this can reduce
future erosion by eliminating beaches, and if you are doing that you
can sensibly put dredgings behind the new edge.

However, it is definitely not a good thing IMHO to use this method to
make the waterway narrower than it was built.  This was done e.g. on
the Rochdale during restoration, where IIRC the spoil form dredging
undertaken to reopen the route was simply dumped in the channel
against the (original) waterway walls in (too) many locations, and
held in place in the way you describe.  This was done to avoid the
cost of removing the stuff.  The result is a seriously reduced water
cross-section, making life difficult for those with broad and wide
craft.  Of course, it was a "temporary" solution, but I believe the
spoil is still there?  Is that "temporary" as in the pyramid of Gizeh?

Which has happened at Compton?

Adrian

.


Adrian Stott
07956-299966

Reply via email to