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Silvertown Tunnel

The client:Riverlinx
Services:Demolition, enabling works, pre excavations, service installations, highway works, remediation, materials management and processing, complex and major civils, coach park construction

The Challenge:

The Silvertown Tunnel scheme (STT), when completed, will link North East and South West London from the North Greenwich area to the Royal Victoria Doc area (Silvertown) and will serve to reduce the current congestion at the Blackwall Tunnel.
The project involves the construction of a 1.6km long, twin-bore road tunnel, accommodating large vehicles including double-decker buses. It will include a dedicated bus, coach and goods vehicle lane, enabling TfL to provide additional cross-river bus routes. As a result, each bore is 12m in diameter and the largest bore tunnel conducted using TBMs in the UK to date.
The £1 Billion tunnel construction project was awarded to our client Riverlinx. A Joint Venture (JV) body created by BAM Nuttall, Ferrovial Agroman and SK E&C.

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The Approach

Demolition – Silvertown and parts of Greenwich where sites of industrial land prior to the works commencing. Cognition were employed to undertake site clearance, asbestos removal and demolition in the early preparation of the site for the main works.
Enabling Works
Cognition carried out major earth moving and cut and fill operations across the site. We also installed many crane and pile working platforms to facilitate the civil works.
Coach Park Construction
Due to the portal of the tunnel at the Greenwich end emerging in what was historically the car parking and coach parking for the O2 Arena. One of the first packages of works on the Greenwich side of the site was to create a new Coach park complete with 65 coach parking bays and all the supporting M&E infrastructure required. The Coach park was constructed by Cognition to TFL and Highway standards.
Highway Works
In addition to the coach park construction, Cognition also completed other diversionary road works and created new access roads to accommodate the new proposed site set up and facilitate access for both local stakeholders and STT tunnel works.
M&E and Service Infrastructure Installation – Cognition supported the project by carrying out many investigatory and diversion service works. Including installing the power ducting required for the future tunnel and TBM at the Silvertown side of site. Street Lighting and car parking infrastructure (barriers and ticket machines etc).
Complex & Major Civils – We undertook the creation of the Launch chamber for the TBM. The shaft was nicknamed “the peanut” due to its unique shape. These works entailed seriously impressive reinforced concrete works, mass digging of the shaft 22m deep, complex Installation of props, Remedial works to piled structures installed by others not meeting the design and QA specification, complex lifting, complex temporary works and logistics. Due to the programme constraints and issues encountered by the third-party pile works, we accelerated the works at the request of the JV. This acceleration resulted in the works being conducted 24/7. We would accumulate in excess of 25,000 working hours a month during the project and we delivered the project with no major incidents or accident.
As both Greenwich and Silvertown are on historic industrial and Brownfield sites, the made grounds were impacted by contamination of; Heavy metals, Asbestos in soils, Total Petroleum Hydrocarbons (TPH) and Poly Aromatic Hydrocarbons (PAHs). Cognition were employed with their mobile treatment licences to conduct the earthworks, segregation and treatment of soils encountered across the project.
Cognition assisted RLX with their arisings. The treatments and segregation tactics employed by Cognition offered both savings on disposal and facilitated the maximum re-use of materials. This helped the project not just by offering cost savings but also by ensuring it maximised its potential from a sustainability and re-use perspective.
Materials Management and Processing
Cognition were employed to manage the arisings generated across the site and undertake materials management in accordance with current legislation, Dowcop and Claire MMPs etc. We were also employed to dispose of deleterious and surplus materials. We also undertook asbestos picking of soils to facilitate re-sue of made grounds were possible, provide the pre-treatment required ahead of disposal as normal when dealing with non hazardous and hazardous materials, and lastly, reduce disposal costs for the client.

The Outcome

Cognition has successfully supported the JV in delivering key elements of the project to date culminating in our last project to construct the launch chamber for the Tunnel Boring Machine on the behalf of the JV. The total value of works conducted by Cognition at the STT is £20 Million.

See full case study here.

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