Barhale has been named as the major contractor on a £9m package of schemes under Thames Water’s Raw Water Tunnel Inspection & Refurbishment programme.
The civil engineering and infrastructure specialist will inspect 35km of raw water tunnels across west and north London.
The work will involve removing debris, silt and invasive species, such as Zebra Mussels, which form substantial concentrations across the network.
It is anticipated that in the most affected tunnels as much as 140 cubic metres of mussels will be removed.
Once cleared, the tunnels will be inspected and any structural repairs will then be carried out.
Phil Cull, director of Barhale, sees the programme as a key element in the maintenance and upgrade of the south east’s water supply.
“This is a hugely important part of London’s water infrastructure and we are delighted to get the go ahead from Thames Water,” he said.
“We have built a huge amount of expertise and experience on the Thames Water network and to be selected on this project is a great vote of confidence in our team’s capabilities.
“While maintaining good flows through the raw water tunnels is essential, it is also of paramount importance that works are delivered efficiently and on time to ensure that there is no unnecessary pressure on the system.
“We have been working closely with the Thames Water team to optimise isolations and are bringing a great deal of new thinking, developed through the maintenance of the Thames Water Ring Main, to the Raw Water programme.”
He added that collaborating on the schemes would minimise the length of isolations and maximise what is achieved during each one.
Barhale has also been tasked with carrying out inspections and the replacement or refurbishment of internal valves of up to 2.4 metres in diameter at sites including Moor Lane shaft (gate and butterfly valves); Ashford Common shaft (gate and butterfly valves); Queen Mary Outlet – Hampton Leg (gate valves); Wraysbury Shaft (butterfly valve); and Queen Mother (penstock).
Two gate valves at the King George VI Reservoir will also be refurbished.
The work, which comprises a total of 12 schemes, is being delivered under the AMP7 Lot 5 Framework.
Barhale will work closely with Thames Water to manage the isolation programme.
John Prendergast, Barhale regional manager, said: “This award builds on the successful delivery of the first three years of the Thames Water AMP7 Tunnels and Aqueducts programme, in which Barhale has already completed monitoring and maintenance on almost half of the length of the Thames Water Ring Main tunnels and a further 9km of raw water tunnels.”
Work is expected to complete in 2025.