Support comes before Thames Water reveal tunnel entry points

Environment Secretary Caroline Spelman has given her support to Thames Water’s plans for the Thames Tunnel - nicknamed the Super Sewer - to reduce the amount of raw sewage discharged into the River Thames.

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 waste water treatment regulations.

On March 22, 2007, the then Minister for Climate Change and the Environment announced his support for tunnels as a solution to the problems in the Thames and asked Thames Water to take forward the design process for the Thames Tideway Project.

This included the Lee Tunnel (a smaller tunnel on which construction work has begun), upgrades to sewage treatment works and the larger Thames Tunnel. In the intervening years Thames Water, the Environment Agency and Ofwat have worked together researching and analysing different options.

Thames Water estimates that the proposed Tunnel will cost £3.6 billion which could result in bill increases of around £60-65 per year for Thames Water customers.

Caroline Spelman said: " '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. 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'."

This statement of support comes ahead of an announcement expected from Thames Water on Monday. September 13 about the proposed entry points for the tunnel, and the launch of a public consultation on the plans.

The proposed tunnel will run for approximately 20 miles through London, and up to 75 metres beneath the River Thames, broadly following the path of the river. Along the way it will capture the flows of storm sewage from 34 sewer overflow points along the River Thames.

Construction is provisionally scheduled to start in 2012 and finish in 2020.

September 10, 2010