WJ’s extensive site experience was called to the fore once again in April 2021. For this project, WJ undertook a series of pumping tests at the northern site of the Silvertown Crossing Tunnel in East London. Connecting the Greenwich Peninsula to the London Docklands beneath the River Thames, the structures are being constructed by some of the largest tunnel boring machines (TBM) (11.9 metres diameter) ever used in the UK to date. The contract for this project was secured with Riverlinx (a joint venture between Bam Nuttall, Ferrovial, and SK Ecoplant).
Despite the complex ground conditions on the north side of the Thames, exacerbated by obstructions from previous excavations and subterranean structures on-site, WJ successfully installed over 50 wells and piezometers to target separate geological layers. Drawdown was achieved to allow the TBM access the following September. An independent dewatering system was installed for a TBM inspection chamber and due to the quality of WJ’s drilling, the boreholes performed much better than the site investigation had indicated was possible. Our accomplishments saved the contractor considerable time and costs during the construction of another cross passage at the same location.
As a result of our successes on the north side of the river, WJ won the tender to dewater the southern portal and TBM rotation chamber at Greenwich and have subsequently installed numerous additional groundwater instrumentation boreholes for monitoring of the structure. The second job was complicated by the project being divided into distinct worksites, separated by open and public roads, but success was achieved by working collaboratively with Riverlinx’s design team to determine the final scope and layout for the Greenwich site as the propping scheme was developed.
WJ’s personnel were on-site during the tunnelling phase to maintain the dewatering at sites on both sides of the river. WJ is pleased to add the Silvertown Crossing Tunnel to a list of successful London tunnelling projects. Previous river tunnelling projects have included High Speed 1 Thurrock Rail Tunnel, Docklands Light Railway Woolwich Tunnel, Crossrail Woolwich Tunnel, Docklands Light Railway Greenwich Tunnel, Jubilee Line Tunnel at Canary Wharf, and the Thames Tideway super sewer tunnels. WJ is proud of it’s contributions to London’s infrastructure and quality of life.
For even more information on WJ Groundwater’s pumping tests in the Silvertown Crossing Tunnel, visit our blog.
Join the conversation