Green drainage must accompany Thames Tunnel, say angling groups 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. 

Mr Adderley 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, 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. 

Martin Salter, National Campaigns Coordinator for the Angling Trust, said: "If you want a clean river and thriving fish life in our capital city, there is no alternative to building the Thames Tunnel."

Dave Harvey from the Thames Anglers Conservancy said "Portland shows that addressing urban drainage problems with (SuDs) can substantially reduce river pollution but after years of studies was no substitute for a tunnel. Londoners deserve their river back."