The 35m-deep shaft will be used to combine intercepted sewage overflows at Acton, in west London, and connect them into the main 25km tunnel.
Since the operation started in October 2021, around 850 cubic metres of concrete across 28 pours were required to complete the lining. Two different mixtures of concrete were designed for the process to ensure the shaft has resistance to abrasion, ensuring the 120-year design life while providing a smooth and consistent finish.
Now the secondary lining is complete, critical works will continue to complete the shaft, including construction of the tunnel portal to connect the shaft with the main tunnel.
