Tideway connects old sewers with new

Work has begun to connect existing sewer networks with the Tideway super sewer at Greenwich and Vauxhall.

As part of the enormous infrastructure project to upgrade London’s sewer system to meet the needs of the expanding population, a 30-metre tunnel under Vauxhall Bridge was broken through.

The tunnel, which is 2.5 metres in diameter, will move sewage from an outfall at Clapham to an interception chamber and ultimately to the main tunnel of Tideway.

It is formed of 14 concrete pipes reinforced with stainless steel, pushed hydraulically into the ground, and took around two months to build.

Lee Fisher, project manager at Albert Embankment, said: “This was a challenging pipejacking operation, taking place at a shallow depth under a busy part of London. The huge amount of preparation by the team included stabilising the ground and providing protection from the Thames’ tides, which allowed us to make good progress.”

Slightly to the west, work began on a 50-metre shaft at the Earl Pumping Station to connect the existing sewer to the connection tunnel at Greenwich, which will move the waste to the main sewer at Chambers Wharf.

In readiness for the tunnel boring machine (TBM) starting work at the site in the coming weeks, the shaft has been fully excavated, a base inserted, then partially backfilled with a temporary cement material. The shaft above was then flooded to match external water pressure.

Project manager Brooke Knight explained: “This is part of our preparation to welcome TBM Annie to Earl Pumping Station, as she digs the Greenwich Connection Tunnel. The 40 metre-deep pool of water will balance the ground pressure when TBM Annie tunnels underneath, allowing us to tunnel straight into the shaft.”

The pumping station will remain operational during the work.

Throughout the work the teams have transported supplies on the river to minimise the number of extra vehicles used on the roads.

Tideway, the company delivering the tunnel, is financed by Bazalgette Tunnel Limited, which in turn is owned by a consortium of investors. The cost will be spread across water bills.

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