River Wandle, Wandsworth

Where the River Wandle enters the Thames in Wandsworth, a multi span Victorian brick-built rail bridge carries trains over the flow of the Wandle and the adjacent Bell Lane Creek.

It was here that urgent vegetation management and brick repairs were needed to be carried out.

Having previously visited Bell Lane Creek to help carry out bridge repairs our team were familiar with the location. Due to the River Wandle having several stepped weirs as it enters the Thames, built to encourage new wildlife, there is a relatively small tidal range of less than two metres. However, this section of the river proved to be shallow and heavily silted.

The decision was to take a 4 metre by 5metre pontoon along with one of our Rigiflex work boats. But as the river was so shallow spud legs would not be the right solution for securing the pontoon under the bridge. Instead, we installed two post floats at one end of the pontoon on the corners, the same end the Rigiflex work boat was to be attached. This allowed two lightweight scaffolding poles to be dropped down through the centre of the modular floats and pushed into the mud of the riverbed securing the pontoon.

To launch the pontoon, we used our spider crane, the Jekko SPX532, which could sit alongside the riverbank and boom out over the water, easily lifting the slabs of modular pontoon and the Rigiflex. The pontoon was quickly put together, edge protection put in place and loaded for work to start.

Working all week the pontoon was easily moved and set in place using the lightweight poles and with an aluminium scaffold tower to reach the brick arch even at its highest point. The pontoon could be left between shifts and left to rise and fall with the tide as needed.

To demobilise, the spider crane was brought back at the end of the week and the pontoon and boat loaded on to the trailer to transport back.