Thames Water starts work this spring on a £40million upgrade at Long Reach sewage works in Dartford, Kent, as part of a major scheme to help improve water quality in the River Thames.

Additional treatment processes will be provided at the works to improve the quality of treated effluent returned to the River Thames and to meet new Environment Agency standards. The improvements will also enable the plant to generate more renewable energy from the sewage treatment process - enough to power over half the site.

Steve Shine, Thames Water's Chief Operating Officer, said:

"These improvements will help clean up the River Thames for all those who use and enjoy it, as well as improving conditions for fish by increasing oxygen levels.

"We will reduce odour at Long Reach by installing new technology and covering up the smelliest parts of the plant. We'll also recycle excavated soil to create a new landscape, and plant trees to help screen the site.

"This upgrade is part of a £675million programme to modernise and extend London's five major sewage treatment works to increase the amount of sewage each site can treat, and improve the standards to which we treat it."

Major upgrades will take place at Mogden in Isleworth, Crossness and Beckton in east London and Riverside sewage works in Havering, Essex. The work is part of Thames Water's wider London Tideway Improvements programme, which includes the £600 million Lee Tunnel project and the proposed Thames Tunnel.

Graham Harris, Managing Director of Dartford Council, said:

"We are delighted that Thames Water is upgrading the Long Reach Sewage Works and fully support measures to reduce odour, to increase the use of renewable energy and to improve water quality."

The Long Reach project is due for completion in 2012, and the improvements will enable the site to deal increased sewage resulting from population growth until 2021. Thames Water has awarded the contract for the works to Galliford Try, a joint venture with Biwater and Mott MacDonald.