Barhale Lands £12.5m Thames Water Tunnel Maintenance Deal

Barhale has secured a £12.5 million contract from Thames Water to inspect and maintain almost 48km of critical tunnel infrastructure across London and the South East.

The programme has been awarded under Thames Water’s AMP8 Tunnels and Aqueducts framework and will cover major assets including the Thames Water Ring Main, the North London Abstraction system and the New River Zone raw water network.

The work will also take in production tunnels within Thames Water’s treatment works, making it a wide-ranging programme across some of the company’s most important underground water infrastructure.

On the Thames Water Ring Main, Barhale will inspect 12 tunnel sections at depths of up to 65m. Most of the work will be carried out through man-entry inspections, supported by limited use of remotely operated vehicles where required. The sections represent around a fifth of the Ring Main’s total length.

Further north, Barhale will undertake 24 inspections across the North London Abstraction and New River Zone, with much of the activity focused around the Lee Valley reservoir complex. These tunnels vary significantly in size and length, with some buried up to 50m deep and individual sections ranging from 30m to 5,450m. In total, almost 25km of tunnel will be inspected in the Lee Valley area.

Where access for workers is not possible, Barhale will use remotely operated vehicles, CCTV and sonar surveys to assess tunnel condition.

Steve Best, Senior Project Manager at Barhale, said the programme involves highly technical work in challenging environments.

“This programme involves complex work in confined spaces and live water environments,” he said.

“We have developed inspection and isolation processes with Thames Water over more than 20 years, and they are designed to keep our teams safe while maintaining reliable operation of the network.”

Teams will access the tunnels through existing shafts and all activities will be carried out under confined space working conditions. The programme will include removing sludge, silt, stones and invasive species, with mussel build-up identified as a particular issue affecting water flows.

Around 3,120 tonnes of waste is expected to be removed during the works.

Barhale will also carry out a range of minor repairs, including mortar restoration, leak sealing and resin injection. Access equipment such as ladders, platforms and covers will be repaired or replaced where needed, while specialist diving teams will undertake work on inlet screens, eel screens and external shaft repairs.

Major repair requirements identified during the inspections will be passed on for further action, with final checks carried out by Thames Water’s reservoir engineering teams.

The programme will also include the replacement of nine large-diameter valves.

Environmental protection will be a key part of the works, particularly in the Lee Valley, where several project locations fall within Sites of Special Scientific Interest and Ramsar-designated wetlands. Walthamstow Wetlands, which is open to the public, will require careful planning to protect local wildlife, including bat and newt populations found in the tunnel environment.

Best said Barhale is continuing to strengthen its approach to safety, particularly around confined space working.

“We are proud of our safety record and continue to improve how we manage risk through the introduction of a new confined space working training regime,” he said.

“It imposes new site entry controls and will see all operatives qualified to the highest level.”

He added that the company’s double isolation procedure, developed with Thames Water, provides an additional safeguard for teams working close to live tunnel sections.

“Our double isolation protocol, developed with Thames Water, also ensures that there is an additional layer of protection for teams working near live tunnel sections.”

The award follows a run of recent contract wins for Barhale, including a £16 million four-year project to build a new service reservoir in Scarborough for Yorkshire Water and work to complete the final section of the £17 million Greenwich Trunk Main scheme.

The latest Thames Water programme further strengthens Barhale’s position in the water infrastructure sector and highlights the continuing demand for specialist inspection, maintenance and confined-space expertise across the UK’s ageing utility networks.