Bachy Soletanche completes Silvertown piling

Working on behalf of the Riverlinx CJV, Bachy Soletanche delivered the £25m geotechnical works for the Greenwich side of the River Thames, which took just under two years to complete.

For the tunnel’s South Portal, Bachy Soletanche installed rotary bored piles to form a secant wall, soldier piles and jet grouted columns. The company installed further secant piles for the open cut and overbridge.

Another major section of the contract involved the construction of a diaphragm wall shaft to form the Greenwich rotation chamber, which enabled the reception and rotation of the TBM after it completed its southbound drive. To facilitate the safe manoeuvring of the TBM, Bachy Soletanche installed unreinforced CFA piles outside the shaft to strengthen and reduce the permeability of the river terrace deposits.

The company also installed CFA piles for the Millennium Way temporary bridge, the control building, a new footbridge and several gantries, as well as cased CFA piles for the open cut temporary utilities bridge.

At its peak, the programme required 24-hour working and five rigs operated simultaneously.

Bachy Soletanche’s operations manager, Martin Stanley, 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.

The site team received support from Bachy Soletanche’s Plant Department, which 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 won the Special Jury Prize in the Vinci Environment Awards.

Bachy Soletanche also helped to reduce the environmental impact of the scheme by monitoring fuel use during the project and integrating electric pumps and equipment into its bentonite farms. The company also worked with its suppliers to procure grout and concrete mixes with as little embodied carbon as possible.

During a period of 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 originally specified secant piled wall. Working with the Riverlinx CJV, Bachy Soletanche’s design team also produced the geometric layouts for the ground treatment, as well as the soft concrete and grout mixes.

Due for completion in 2025, the Silvertown Tunnel will be a 1.4km twin-bore road tunnel running under the River Thames, connecting Silvertown to the Greenwich Peninsula.