UK Environment Secretary Caroline Spelman yesterday gave her full support to the Thames Tideway Project planned to reduce the amount of raw sewage discharged into the River Thames. The US$5.8bn project being undertaken by Thames Water, includes the construction of the 6.4km long, 7m diameter Lee Tunnel and the 32km long, 7.2m diameter Thames Tunnel.
‘A tunnel continues to offer by far the most cost effective solution to the unacceptable problem of raw sewage being regularly discharged into the Thames,” said Spelman, “This is a large and complex project and I recognise that it comes at a significant cost. I will ensure that Defra and Ofwat continue to scrutinise the costs and options to ensure that Thames Water’s proposals represent proper value for money.’
The Lea Tunnel is currently under construction and runs from Abbey Mills pumping station to Beckton STW and will be completed in 2014. The Lee Tunnel and Beckton STW upgrade will reduce the total volume of discharges to the tideway by around two thirds.
The Thames Tunnel is expected to be completed in 2020. Thames Water will shortly launch a consultation exercise on the need for the tunnel, and the route and the sites needed to construct and operate the project.
Further information on the Tunnel can be found on the Defra website at:
The core of London’s sewage network was designed in the late 19th Century and was designed to overflow at times of heavy rainfall to ensure that sewage did not back up into houses and streets. Combined Sewer Overflows (CSOs) were intended to discharge the raw sewage into the Thames in the event of extremely heavy rain.
Increasing populations and changes to land use in London have lead to this occurring around 50 times per year. With further population growth and projected climate change, this figure is expected to increase in coming decades and spills could occur when there is very little rain. This also creates problems for the UK’s continued compliance with EU wastewater treatment regulations.