In the first week of January we were joined on site by Walsh Construction. They were contracted to reinforce 60m of canal wall and sheet pile 130m on the non-towpath side. The idea being that the volunteers would follow on with the concrete canal base.
During January and February we had some of the wettest weather on record, which hampered us and the Walsh team. The public footpath (and future towpath) next to our cabin became water logged so we created a higher path using hardcore material.
Following the collapse of two sections of towpath wall, Walsh had to fit sacrificial piling in front of the remaining sections. As we are mainly retirees, it was good to witness more modern and safe methods of working.
The shuttering for the reinforcing wall was a German design – far lighter and safer to use than the system we used. It was quicker to install as well, as once it was assembled it was only partially ‘struck’ (i.e. demounted) before being hoisted into its new location, using two special brackets fitted to the shuttering.
Sheet piling was faster as well. Walsh hired in an excavator-mounted vibrator plate which did the work of both our machines and was far quieter in operation. As it held the sheets it could also remove them again if they started to move out of alignment.
We’d historically poured a maximum of 2.4m wide sections of canal base at a time and waited for the concrete to cure. We needed to greatly increase our pace to achieve the target of getting this section in water in May. So we devised a rolling pour method, enabling us to pour four times as much in one go.
However it proved problematic for both groups to schedule deliveries and concrete pours. Getting space for machines to safely pass each other also became increasingly difficult as the 6-metre wide channel was created.
We decided to keep out of the way of Walsh, and concentrate on the London Road end. Working on the first of the four locations where we need remedial works to deal with our nemesis big pipe, became our main aim.
We constructed a tank wall (below left) encompassing the first of the pipe sections and then installed a 450mm MDPE plastic pipe from the tank wall to the side of the wharf wall and back into the concrete pipe (below right).
As this is designed to sit on a gravel bed, we made suitable bracketing to withstand the significant weight of water if the pipe fills to capacity.
It was tricky to get the plastic pipe back into the concrete pipe, so we needed additional fittings to get it into the right shape.
Once the tank wall was completed, some of the team started finishing off the reinforcing wall by increasing its height with several courses of blue bricks. When the canal is filled only the blue bricks will be visible and the concrete will be below the water line.
Meanwhile our contractors Walsh made great progress and by the end of March had completed 60 metres of reinforcing wall and around 130 metres of sheet piling. It would have taken our volunteers the best part of a year to do this work.
By late March our very own Rick-the-brick had returned to complete the London Road steps. The first five are brick transitioning to eight steel ones, so there has to be a consistent riser and tread width across them all. Rick settled on a 170mm riser. A single continuous handrail needs to be fitted to each side before the steps are brought into use.
I hope to be able to report next time that we’ve removed the first section of our nemesis pipe at Phase 2 and we may even have completed the concreting under it.
Mike Babb
Workparty volunteer
This blog first appeared in Cut Both Ways, our members’ magazine, become a member to get your copy.
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