By Ashley Karen
Bachy Soletanche has finished its piling program for London’s new Silvertown Tunnel. Working on behalf of the Riverlinx CJV, Bachy Soletanche provided the £25m geotechnical works for the Greenwich side of the River Thames, which took only under two years to finish.
Bachy Soletanche installed rotary bored piles for the tunnel’s South Portal to form a secant wall, soldier piles, and jet-grouted columns. The firm also installed additional secant piles for the open cut and overbridge.
Another significant section of the contract contained a diaphragm wall shaft construction to form the Greenwich rotation chamber, which allowed the reception and rotation of the tunnel boring machine after it completed its southbound drive.
Bachy Soletanche installed unreinforced CFA piles outside the shaft to facilitate the safe maneuvering of the TBM and strengthen and reduce the permeability of the river terrace deposits.
The organization also installed CFA piles for the Millennium Way temporary bridge, the control building, a new footbridge, several gantries, plus cased CFA piles for the open-cut temporary utility bridge.
At its peak, the program demanded 24-hour working, and five rigs operated simultaneously.
Martin Stanley, Bachy Soletanche’s operations manager, said: “The company’s experience working in joint venture partnerships on other major infrastructure schemes in London, such as Thames Tideway and Crossrail, allowed it to support Riverlinx with specialist requirements, such as acquiring consents.
Bachy Soletanche’s Plant Department supported the team site, and it designed and manufactured a mechanical casing recovery tool that can retrieve lost segmental casing from a borehole. In 2021, the innovation was shortlisted for two Ground Engineering Awards and received the Special Jury Prize in the Vinci Environment Awards.
Moreover, Bachy Soletanche assisted with reducing the scheme’s environmental impact by surveying fuel use during the project and integrating electric pumps and equipment into its bentonite farms. The firm also worked with its suppliers to procure concrete mixes and grout with as little embodied carbon as possible.
During the early contractor involvement, Bachy Soletanche’s in-house design team was responsible for proposing the rotation chamber’s diaphragm wall – an alternative solution to the initially specified secant piled wall. Working with the Riverlinx CJV, Bachy Soletanche’s design team also produced the geometric layouts for the ground treatment, plus the soft concrete and grout mixes.
Once completed in 2025, the Silvertown Tunnel will be a 1.4km twin-bore road tunnel operating under the River Thames, linking Silvertown to the Greenwich Peninsula.
