Barhale will inspect 35km of raw water tunnels across west and north London, removing debris and silt.
The contractor will also remove invasive fauna, such as zebra mussels, which gather 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.
As a further part of the allocation, Barhale will also carry out inspections and replacement/refurbishment of the internal valves at sites, which can be up to 2.4m diameter. They include: 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 separate schemes, is being delivered under the AMP7 Lot 5 framework. Work is expected to complete in 2025.
Barhale director Phil Cull said: “This is a hugely important part of London’s water infrastructure and we are delighted to get the go ahead from Thames Water. We have built a huge amount of expertise and experience on the Thames Water network and to be selected on this project is 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.”
He added: “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. We will again be collaborating to minimise the length of isolations and to maximise what is achieved during each one.”
Regional manager John Prendergast added: “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.”
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