TPA pontoon helps Amey drill down on a walkway detail

06 Jul
More than two years after a walkway along the River Don in Sheffield collapsed during floods, pontoons from TPA are helping to determine its future.
The project

Engineering specialists Amey were called in to oversee core sampling on a 50m stretch of the Five Weirs Walk along the River Don from Sheffield city centre to Meadowhall shopping centre. The five-mile stretch is also part of National Cycling Route 6.

The walkway collapsed during floods in November 2019 and Amey were investigating whether it could be reinstated with sheet piling. They called in geotechnical engineers Strata Geotechnical to carry out core sampling 25m down into the riverbed. Two samples were taken over a five-day period of high water in the depths of winter.


The main challenge on this project was finding a suitable access point for the TPA pontoon. This was eventually sourced via a grass bank located in some industrial works, about 100m from the sampling site. The bank was protected from the drill rig’s landside manoeuvres by plant access ramps.


A six-float TPA NATO modular steel pontoon was specified by Amey with edge protection handrails, deck protection mats, aluminium bracing planks and central moon pool to allow access for the tracked drill rig.

A medium-load solution for working on water, the pontoon also featured 4m auto-winch spud legs to anchor it, complemented by a 7m telehandler and qualified operator for installation and recovery, on-site pontoon crew to operate the spuds and help with manoeuvres, and a safety boat and qualified skipper to assist with manoeuvres to and from the drill site as well as for water safety cover.

The pontoon floats were lowered into the water by a telehandler using hoisting chains on the floats’ integral lifting lugs. On the water, the floats were pushed together and coupled by connecting the elements (connection forks and connection rings). The complete pontoon was then pushed to the sample site by the safety boat.

Client comment

Amey’s construction manager Andrew Thirlwall said they had chosen to work with TPA again because the company offered the complete one-stop-shop package.

“We know what TPA are capable of. They offer a very good service,” he said.

“There were some complications to this project but there were no big issues. Everything ran well. In terms of TPA’s performance on it, it was a very well-run project and they worked well together with Strata.”