Unlike the tunnel boring machines, which are constructing the Thames Tideway sewer itself along with two connection tunnels, Ward & Burke's pipe-jacking machines are unmanned excavators that are controlled by a team working at ground level.
The first pipe-jacker is at Tideway’s site in Barn Elms where it will create a 200-metre tunnel to link the west Putney Storm relief combined sewer overflow (CSO) to the main super sewer.
Diverting the spills just at this point into the super sewer will prevent around 35,000m3 of untreated sewage entering the Thames each year.
The second pipe-jacking machine is at Tideway’s site along Putney Embankment, where Tideway is ‘intercepting’ another CSO beneath Putney Bridge, which spills around 68,000m3 of raw sewage into the River Thames each year.
In Putney, the pipe-jacking machine will be used to create two tunnels, using two different methods of excavation due to the ground and location. The 135-metre tunnel linking the main shaft to the CSO, will use a closed-face method of construction using slurry pressure to maintain tunnel face stability and prevent over-excavation. The 43-metre connection into the main super sewer uses an open-faced machine using an excavator arm.
Putney project manager David Miles said: “It’s fantastic to welcome these machines to Tideway, and it just shows the diversity of the tunnelling work underway on this project.”