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Construction of chalk cake factory begins at Plumstead

By Ana-Cristina Johnston

Construction of chalk cake factory begins at Plumstead

Work has just started at Plumstead in east London to construct Crossrail’s new slurry treatment plant.

To build the new Crossrail tunnels between Plumstead and North Woolwich, tunnel boring machines will travel through chalk and flint beneath the River Thames.

To tunnel through chalk, Crossrail will need to use a different type of tunnelling machine known as a Slurry TBM. As part of the tunnelling process, the chalk soils are mixed with bentonite (a mixture of clay and water) in the excavation chamber to form a liquid.This slurry liquid is removed from the tunnel through a system of slurry tubes.

The slurry treatment plant will be used throughout the tunnelling process to treat the slurry material excavated by the Thames Tunnel TBM by reducing the water content to create a chalk cake. These chalk cakes will then be transported off site to extract the bentonite for beneficial re-use.

Crossrail’s two slurry TBMs, Mary and Sophia, will start construction of the Thames Tunnel this winter.

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