London Tideway Tunnels: tackling London’s Victorian legacy of combined sewer overflows

摘要

It takes a few millimetres of rainfall to cause the 34 most polluting combined sewer overflowsn(CSOs) to discharge into the River Thames. Currently, in a typical year, spillages to the tidalnreaches of the River Thames occur about 60 times, with an estimated spill volume of 39 millionncubic metres. Both the UK Government and the European Union have determined that the CSOndischarges have an adverse environmental impact on fish species, introduce unacceptablenaesthetics and elevate the health risks for recreational users of the Thames, with a frequency ofndischarge which is in breach of the Urban Wastewater Treatment Directive. Studies havenestablished that the environmental objectives can be fully met on the most cost-effective basis byncompleting both quality improvements to treatment works and by the provision of a storage andntransfer tunnel to intercept unsatisfactory CSOs. Extensive modelling has been undertaken tondevelop an optimised solution. In parallel with the design development a rigorous andncomprehensive site selection methodology has been established to select sites and consultnstakeholders and the public on the preferred sites and scheme, with the first stage of publicnconsultation planned for later in 2010. The London Tideway Tunnels are an essential part of thendelivery of improvements to the water quality of the tidal River Thames, and this ambitious,nhistoric scheme represents a vital strategic investment in London’s infrastructure.