A Complex sheet piling project on Transport for London’s £1 billion Silvertown Tunnel is benefiting from specialist contractor Sheet Piling UK’s expertise and Kobelco Cranes’ CKE900G-3’s versatility.
At just over 346 km (215-mile) long, the River Thames is the second-longest river in the United Kingdom. Currently crossed by over 200 bridges, 27 tunnels, six public ferries, one cable car link, and one ford along its course.
All that is set to change, however, with the opening of Transport for London’s (TfL) £1 billion, 1.4km-long, Silvertown Tunnel in 2025. Designed to reduce congestion in and around the Blackwall Tunnel, something that’s estimated to cost the UK’s economy over £10 million per year, it will be the first underground crossing of the River Thames in over 40 years.
Delivering the project is the responsibility of the Riverlinx JV (Ferrovial Construction, BAM Nuttall and SK E&C), with specialist contractor Sheet Piling UK (SBUK) tasked with delivering a “complex sheet pile installation” across the closed entrance to Royal Victoria Docks, close to Silvertown, on the river’s north side and south-east of Canning Town, according to managing director Andrew Cotton.
This will create retaining earthworks and a stronger stretch of Thames-river wall enabling construction of the 1.4km-long, twin-bore tunnel under the river. To facilitate this, SPUK is installing around 350 linear metres of steel sheet piles – ZZ38700 x 15.2m - to install a new river wall in a location where the existing one is “highly distressed”.
“Being required to use conventional piling methods because of the wall’s poor condition, but unable to install spud piles into the riverbank, due to Environment Agency (EA) restrictions, our in-house sheet piling design team had to devise a different solution,” explains Andrew.
The solution was to design a bespoke cantilever piling gate, located on the existing quay side, to provide the required stability for sheet pile installation. Using this method, says Andrew, means SBUK can ensure the temporary sheet piles form a secure flood defence wall until the permanent flood defence wall can be constructed and the temporary steel sheet piles cut down to the final desired level.
New ‘Free Issue’ Z-section sheet piles are being driven into the Thames 1m in from the existing wall, to avoid excess land-take and environmental impacts, using a PVE38M vibratory hammer, which weighs 8 tonnes, supported by a Tier 5/Stage V Final Kobelco CKE900G-3 lattice-boom crawler crane, which was supplied with a 44.7m boom.
To facilitate the works, the CKE900G-3 is using a 36.6m main boom with lifting duties ranging from 6 tonnes at 32m, up to 27.7 tonnes at 10m. Besides the 15.2m-long ZZ38700 piles, the CKE900G-3 is also being used to move SPUK’s welding set and diesel bower, the main frame and Kentbridge Block, and 8 tonne PVE38M vibratory hammer.
“The small operating footprint and excellent manoeuvrability of the CKE900G-3 have been invaluable at the site,” says Andrew. “Added to which, it has good duties at a large radius – ie exceptional outside duties – while the KCross system allows information on performance and operation to be easily communicated to our client.
The CKE900G-3 is the first Kobelco crawler crane SPUK has added to its fleet and Andrew has also been impressed with the heavy-duty lattice boom jib for extraction works and the fact it can be transported in full ballast configuration.
“Besides that,” adds Andrew, “the CKE900G-3’s environmental credentials – a Non-Road Mobile Machinery (NRMM) compliant Tier V/Stage 5 engine, ease-of-use, backed with excellent reliability and after sale’s support mean this is a great package for us and our clients.”