A giant tunnelling machine called “Beckton Becky” was lowered 20 metres below the ground on Thursday [Feb 2] to complete the extension of Beckton Sewage Works.

The treatment centre, one of the largest in Europe, is being upgraded so it can effectively treat increased flows during heavy rainfall to stop sewage overflowing into the River Thames.

The lowering of “Beckton Becky” marks the halfway point of the �190 million expansion which started in 2010 and is due to be completed in 2014.

It will now spend two months tunnelling for 750 metres while a 350-strong workforce remains onsite to finish creating the water tanks and building foundations.

Nick Fawcett, Thames Water’s Head of Delivery, said: “As well as expanding the site, we’re also erecting odour-blocking covers over all 16 primary settlement tanks at the plant - an area the size of ten football pitches, and installing ‘odour-control units’ at the site to clean ongoing air, so we can substantially reduce odour emissions.”

The mechanical and electrical installation begins in March to get the tanks up and running.

The project is being managed by Thames Water as part of the London Tideway Improvements programme which also includes the �635 million Lee Tunnel, currently under construction, and the proposed Thames Tunnel.