First TBM breaks ground at Thames Tideway Tunnel project
October 30, 2019 – A joint venture of BAM Nuttall, Morgan Sindall and Balfour Beatty has announced that one of its two tunnel boring machines (TBMs) has become the first to break through the ground to complete a section of tunnel for the Thames Tideway Tunnel project, a new super sewer in London.
The TBM, Charlotte Despard, is digging the Frogmore Connection Tunnel from Wandsworth to Fulham as part of the Thames Tideway Tunnel project to clean up the River Thames from sewage pollution.
The 1.1km tunnel will help divert sewage overflows from King George’s Park into the main 25km super sewer at Fulham, where it will be transferred to east London for treatment instead of polluting the River Thames.
The 500m southern section of the Frogmore Connection Tunnel, from Dormay Street to King George’s Park, has been completed.
The tunnel boring machine will be lifted from the shaft, taken back to Dormay Street and placed back into the ground to tunnel 600m north to Fulham.
The joint venture project director Sally Cox said: “This breakthrough, the first on the Tideway project, marks another key step toward a cleaner, healthier River Thames.
“Despite being the smallest TBM on the Tideway project, Charlotte is creating vital infrastructure that will benefit Londoners and their river for many years to come.
“Our tunnelling team has done a fantastic job getting this machine to King George’s Park and will now focus on completing the northern section of the Frogmore Connection Tunnel.”
Charlotte is a 3m-wide machine and more than 70m long and the Frogmore Connection Tunnel is being made at a depth of around 30m.
The TBM has been refurbished as it previously worked on a water ring-main project in north London.
The first section of the main tunnel is nearing completion, with the TBM Millicent approaching Fulham after tunnelling nearly 5km from Battersea. So far, nearly 8km of the Thames Tideway Tunnel has been built, with four tunnelling machines working underground.
The Thames Tideway Tunnel will be a 25km tunnel running mostly under the tidal section of the River Thames through central London. The tunnel will capture, store and convey nearly all of the raw sewage and rainwater that currently overflows into the river.
Started in 2016, the project is expected to be completed in 2024. Upon completion, the main tunnel will have an internal diameter of 7.2m and will run from a depth of 30m at Acton in the west of London for over 25km under central London before reaching a depth of 70m at Abbey Mills in the east, connecting 34 of the most polluting combined sewer overflows (CSOs), via transfer tunnels.
The tunnel will transfer the captured sewage to the Stratford to East Ham part for onward delivery to Beckton Sewage Treatment Works for treatment. The recycled clean water will be released back into the river.