Two underground machines being used to create part of London’s new super sewer have arrived in west London.
Unlike Tideway’s tunnel boring machines, which are creating the super sewer and two connection tunnels, these giant machines are unmanned and controlled by a team working at ground level.
The first of these excavator machines, known as pipe-jacking machines, arrived at Tideway’s site in Barn Elms where it will create a 200m tunnel linking the west Putney Storm relief combined sewer overflow (CSO) to the main super sewer.
Around 35,000m3 of untreated sewage enters the Thames from this point in the average year, so diverting these spills into the super sewer is vital to the health of the River Thames.
The second pipe-jacking machine to arrive in London was delivered to 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, utilising two different methods of excavation due to the ground and location.
The 135m 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 43m 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.’