Falconbrook completes excavation of interception chamber

At the Falconbrook Pumping Station site for London’s super sewer, the team has marked another milestone by finishing the excavation of the 17m-deep interception chamber.

This concrete structure will combine and redirect intercepted sewage towards the 41m-deep shaft constructed on site which will safely transport flows deep below ground before it moves into the main super sewer.

The interception chamber was constructed from the top down meaning the team could construct a cascade structure allowing the existing Low Level 1 Sewer to remain operational.

This mitigated the need for a complex temporary flume installation to hold the sewer above the excavation, saving the project time, money and personnel exposure to health and safety risk.

The top-down construction meant the team had to carefully excavate around four bearing piles that hold up the cascade structure like a table. Once under the cascade, they installed four levels of timber headings to support the ground under the sewer.

The next phase involved breaking into the connection culvert, which links the interception chamber with the site’s shaft, and casting the base slab.

This 250m-long tunnel connects the shaft to the main super sewer tunnel and was constructed using a sprayed concrete lining method.

The Falconbrook site in the London Borough of Wandsworth is located next to York Gardens. It is part of an existing pumping station where more than 700,000 cubic metres of untreated sewage flows into the River Thames on average each year.

Our work to intercept these overflows into the new super sewer will reduce this amount by around 94 per cent.