The Thames Tideway is an ambitious project to upgrade London’s combined sewer-stormwater network, first built in the 1860s. This venerable system of brickwork tunnels has served the city well, but London’s growth is putting it under strain. When heavy storms hit the city, the trunk sewers back up to pumping stations that try to deal with the extra flow. In the worst-case scenarios, the overflow spills into the river itself.
McAllister has been providing essential work for the Tideway project since 2016. We conducted the initial surveys, made major contributions to the design phase, and we are now delivering mitigation work across the city to ensure that construction doesn’t interfere with the sewer’s day-to-day operations. One of the most ambitious aspects of this work is our mitigation work at Cremorne Wharf, where one of the Tideway’s enormous vertical shafts descends to the main sewer line. This is the site of one of the London sewer’s notorious overflows. The shaft will descend some 50 metres below street level to capture the sewerage that once flowed to the river. It’s being excavated around the existing sewer and we were commissioned to reinforce this line. This specialised work required us to install hundreds of steel ribs inside the sewer line to reinforce the 150-year-old brickwork.
The sewer line crosses the new shaft, so we built a “flume” – a bridging pipe suspended between the shaft’s walls – that keeps the sewer connected even as the excavation work goes on around it. We will remove the bridging tunnel once the Tideway project is complete, allowing the sewer to discharge into the new shaft.
Watch the video to see some extraordinary shots from this exciting project, and get in touch to learn how our specialist design and construction expertise can serve you.