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Life Cycle Assessment: Tideway East

Continuing on our theme of guest blogs, Dr Noemi Arena has been innovating with CVB Tideway East (thanks to a collaboration with Costain as part of The Great Think), to demonstrate the latest environmental thinking and scientific assessments….

It’s not only about Climate Change; there are several different emissions associated to the construction of a project. These have impact on the human health, ecosystem quality and resource of our Earth.

A technical way to evaluate also these different environmental impacts is by means a Life Cycle Assessment (LCA) study, a tool which evaluates all the interactions within the environment across all stages of the life cycle of the project. It’s in fact called “cradle to grave” because it takes into account all the emissions associated from the raw extraction of the materials to the final disposal of the system/project.

For the East side of the Tunnel I have selected some of the main processes included in the construction of the tunnel. These processes include: fuel for all the operation machines, steel for marine, geotechnical and civil works, lime, concrete for the diaphragm wall and segment factory.

The study was developed from “cradle to gate”, i.e. including processes and transportations from raw material acquisition to the assembly of the tunnel.

The results showed that the overall environmental performance of the production of the tunnel is dominated by the production of the concrete for the segment factory and the steel for the geotechnical works. In particular, there is a high contribution to the impact on human health mostly related to the emission of chloroethylene and PM2.5 during the production of steel and the segment factory.

Apart from the impact on the climate change which is overall caused by the CO2 emission from the segment factory production, also the resource consumption is very high due to non-renewable resources used like sand for the concrete.

By analysing different alternative scenarios specifically based on the production of the segment factory, we have seen that the sustainability of the concrete for the segment factory and consequently of the whole Tunnel could be improved greatly, reducing the contribution to climate change by 39%, human health by 12% and resource by 16%, by increasing the percentage of GGBS in the composition.

The information obtained by this LCA have been disseminated to the key stakeholders engaged on Tideway. This engagement has highlighted the key impact areas before developing a series of potential mitigation interventions for consideration ahead of following design gates engaging also a collaboration with the suppliers in order to provide alternative solutions. This will lead to some further reductions in overall impacts of key activities and ensure suppliers are fully engaged and helping deliver targeted innovation into the project. This will demonstrate the value of interventions across key impact categories and associated variance in costs.

Thanks to Noemi, Damien Canning & Tim Embley @ Costain for their support, and Darren White (Tideway) for showcasing this cutting edge environmental appraisal technique with CVB Tideway East.

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