Barhale has extended its role in the maintenance of the Thames Water Ring Main (TWRM).

The firm has secured works to replace almost 100,000 white caps in the tunnels between Kempton and Kew.

The £1.47 million project will see the civil engineering and infrastructure specialist isolate, drain, clean and inspect two sections of the TWRM from the Kempton shaft to the Mogden shaft (6.875Km) and from the Mogden shaft to the Kew shaft (4.820KM). Barhale will then replace the existing push-fit caps covering the lifting eye sockets on each tunnel plate with new, screw-fit types.


The TWRM was built between 1988 and 1994. It is 2.5m diameter and 80km long and is a critical part of London’s water infrastructure carrying around one-sixth of the capital’s daily water demand.

Access to this section of the Ring Main is only possible through access flanges at the Kempton, Mogden and Kew shafts so some enabling works may be required.

Barhale regional manager, John Prendergast described the works as an important element in the ongoing maintenance of the Ring Main.

"We have worked alongside Thames Water on the Ring Main for many years and we are pleased to be extending our long-standing relationship with this latest programme," he said.

"The close relationship between the two teams and our collaborative approach continues to yield positive outcomes for customers – not only in programme delivery but also in terms of the longer-term benefits where we are improving the network's resilience and safeguarding the future supply of drinking water to London."