Chelsea Embankment Foreshore and Heathwall Pumping Station excavated their connection tunnels using sprayed concrete lining. The team would excavate forward one metre at a time before shotcreting the exposed tunnel surfaces.

The Chelsea Embankment team began mining the 55m-long tunnel from the base of the shaft which is located within the site’s cofferdam. The tunnel was completed when work was resumed after the coronavirus lockdown, with the team working under the new safety guidelines.

At Heathwall Pumping Station, a 43m-long tunnel was excavated from the deeper of two shafts on site. Completion of the tunnel brings to an end almost 14 months of constant excavation, which included the two shafts, a connection culvert – linking the two shafts – and the new connection tunnel out to the main tunnel.

The teams will now turn their attention to waterproofing the tunnels before they commence the secondary lining.

Tideway is the 25km sewer tunnel which will run for the most part beneath the River Thames at depths of between 30 and 60m, transferring waste eastwards under gravity. The £1.1bn project is designed to intercept, store and ultimately prevent around 39mt of raw sewage entering the river annually through combined sewage overflows. Construction is scheduled for completion in 2024.

Source: Tideway