Green drainage must accompany Thames Tunnel, say environmental groups

Posted: Wednesday 14th November 2012

Opponents of Thames Supersewer urged to embrace both solutions after US presentation.

A US wastewater expert has urged London to embrace the Thames Tunnel as the only solution to end the scandal of millions of tonnes of untreated sewage that enters the Thames each year through the city’s combined sewers.

Members of the Thames Tunnel Now coalition, an expanding collective of environmental and amenity groups committed to cleaning up London's river, have called upon opponents of the project to acknowledge that green infrastructure cannot be an alternative to the Thames Tunnel, but an important addition.

This was the message from America following a presentation this week to water industry experts by Virgil Adderley, CSO programme manager for the city of Portland in Oregon. He explained how Portland had initially sought to solve the pollution of the Willamette River system from Oregon's 50 plus Combined Sewer Overflows (CSOs) by introducing a comprehensive system of Sustainable Urban Drainage (SuDs) without resorting to building a separate tunnel to capture the discharges. After more than 20 years of work and studies, the city of Portland concluded that while green drainage had an important role to play in less built up areas, it was no substitute for a tunnel.

In his presentation at Glaziers Hall in Southwark, Virgil Adderley said: “Whatever we tried, we found that a large tunnel is needed to achieve acceptable levels of CSO control. Green infrastructure is important but only as a complimentary measure...”

Recently opponents of the Thames Tunnel have claimed it would be possible to retrofit London's entire 150 year old drainage system to achieve total separation of sewage and rainwater. The Portland Study shows beyond any doubt that even in a much less densely populated environment, green infrastructure solutions alone cannot solve the problems of the Thames Tideway.

Chief Executive of London’s leading waterway charity, Thames 21, Debbie Leach said: “Decades of study have made it crystal clear that nothing other than the Thames Tunnel would meet the standards set by the Environment Agency in the timescale set by the Government to end the scandalous pollution of the tidal Thames, which is now the subject of European Court action. Londoners deserve their river back and some of these groups now need to accept that the science is not on their side. Everyone who cares about having a clean river should get behind the Thames Tunnel, which needs to be built now”

The RSPB’s senior water policy officer, Phil Burston, said: “Portland shows that tackling urban drainage problems with green infrastructure (SuDs) can substantially reduce river pollution by up to 35% – but to eliminate the sewer overflows stifling the Thames and doing so much harm to its wildlife, tunnels and pumping stations combined with these green measures are the only real and practicable solution.”

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