The Thames Tideway project will run a 32km tunnel up to 80m below the ground between Hammersmith and Beckton in East London and a second, Lee Tunnel, from Abbey Mills in Stratford to Beckton. The tunnels will capture and transfer sewer discharges for treatment, keeping sewage outfalls out of the Thames during high rainfall.
Steve Walker, Major Projects Director for Thames Water, said: "The Tideway Tunnel scheme is Thames Water's biggest single investment project by far. These exceptional tunnels will have enough capacity to store millions of litres of diluted sewage and transfer it to our Beckton sewage treatment works. This scheme is essential if we are to improve the quality of the river and reduce the environmental impact of sewage overflows.
"To successfully implement this massive and challenging engineering project we need the full support of our stakeholders and a world-class team with the appropriate knowledge and experience to take it from planning to construction. We are delighted to have CH2M Hill on board to help us deliver a sewer system fit for the 21st Century and beyond."
Both 7m tunnels need to be supplemented by numerous collection and diversion facilities, a large high-head underground pumping station, and a major upgrade at Beckton sewage treatment works.
Lee McIntire, President and COO for CH2M HILL, said: "We look forward to working with the Thames Water team to deliver this landmark engineering programme. Together we will help the city meet current and future wastewater requirements, and leave a lasting legacy that will improve the quality of the Rivers Thames and Lee for future generations."
Work on the smaller Lee Tunnel is expected to start in 2009, once the relevant regulatory and planning approvals have been obtained, for completion by 2014.
The larger Thames Tunnel will not start until around 2012, to complete in 2020.
CH2M Hill will oversee planning consents, preliminary and final design, construction, stakeholder communication, commissioning and start-up of new facilities. Subcontractors on the CH2M HILL team include Halcrow and Tunnelling Limited.