17/06/2026
Barhale secures £12.5M tunnel inspection and maintenance programme.
Thames Water has appointed Barhale to deliver a £12.5M programme of statutory tunnel inspection and maintenance across key infrastructure including the Thames Water Ring Main (TWRM) and North London Abstraction and New River Zone raw water assets.
The projects, awarded under the AMP8 Tunnels and Aqueducts programme, will also include the production tunnels within Thames Water’s treatment works, bringing the total length of tunnels under inspection to almost 48 kilometres.
On the TWRM, civil engineering, infrastructure and tunnelling specialist Barhale will use mainly man entry with some limited Remotely Operated Vehicles (ROV) to inspect 12 sections of the tunnel at depths of up to 65m, representing around 20% of the asset’s extent.
At the North London Abstraction and New River Zone, Barhale will carry out 24 inspections concentrated around the Lee Valley reservoir complex. The varying diameter tunnels are buried up to 50m deep and range from 30m to 5,450m in length. The overall length to be inspected in the Lee Valley area is 24.9km.
ROV, CCTV and sonar surveys will be conducted where in person inspection of the tunnels is not possible.
The tunnels will be accessed from existing shafts. Works will be carried out under Confined Space Working conditions and will include clearing sludge, silt, stones and invasive species – particularly mussel concentrations which impact flows. It is estimated that 3,120 tonnes of waste will be removed.
See more: https://www.barhale.co.uk/news/barhale-secures-12-5m-tunnel-inspection-and-maintenance-programme