ABSTRACT
London’s 150-year-old Victorian sewerage network was originally designed to service a population half the size of its current 8.7 million inhabitants. The system is in good working order but is operating over-capacity. Each year, millions of tonnes of untreated sewage and stormwater is discharged into the River Thames at the overflow points. This poses considerable health risk to river users and the environment. A £3.8 billion Tideway tunnel is currently underway to capture and divert overflows to be treated before being discharged. At Vauxhall Bridge, an interception chamber on the tidal foreshore of the River Thames directs two existing overflows to the new tunnel via a 50m deep drop shaft. This paper describes numerical modelling carried out for the design of the shaft and field monitoring of the shaft excavation and modelling for the interception chamber. The results provide valuable information for the design of deep excavations in typical London basin strata.
