Barhale is now ready to start internal shaft work at the Victoria Embankment foreshore.
The next steps include the installation of the baffle/divider wall and vortex surround – the two elements that facilitate the flow transfer from the top to the bottom of the shaft where a 17-metre tunnel connects to the new super sewer.
The secondary lining of the connection tunnel has also just been completed.
The Ferrovial Laing O'Rourke (FLO) joint venture, principal contractor for the 12.7km central section of the 25km Thames Tideway Tunnel, appointed Barhale to carry out the works at the Victoria Embankment foreshore. When completed, the site will be used to control the existing local combined sewer overflow, known as the Regent Street CSO, through the connection of the northern Low Level Sewer No.1 to the main tunnel.
The lining is a key structural element of the 48-metre shaft. It will protect against the chemical and physical impact of the sewer discharges and ensure its 120-year design life.
Barhale used a custom-specified concrete mix for the lining. Using more than 70% ground granulated blast furnace slag (GGBS) and admixtures, it generates fewer CO2 emissions than traditional ordinary Portland cement (OPC) concrete mixes.
Contracts manager Filipe Mello said that, although approximately 1,900m3 of concrete had been used in total, the team had been able to maintain good progress throughout.
“We employed thermocouplers, maturity curves and the on-site testing of cubes to confirm the in situ concrete strength,” he said. “That allowed us to jump the formwork in the next pour position to maximise progress.”
Barhale regional director Phil Cull highlighted the importance of reaching the milestone. “Tideway is a huge project which will upgrade London’s infrastructure not only to meet existing demand but also for generations to come,” he said. “At Victoria Embankment we are working on a key site within the Whitehall conservation area and adjacent to one of the capital’s principal arterial routes. It means completing major infrastructure works to a very tight schedule so it is very pleasing to get the shaft lining completed.”