Over six months later than it was hoped to be released, a report by the Thames Tideway Strategic Study was worth waiting for as it said its preferred remedy to pollution from London’s combined storm overflows (CSOs) into the river Thames was a 35km long, 7.2m diameter, storage and transfer tunnel under the city (T&TI, May 2004, pg 8).
Formed in 2000, the Thames Tideway Strategic Study had a remit to assess the environmental impact of 57 CSOs. The study identified its preferred option after carrying out a full cost-benefit analysis, the same process used as an aid by the government to select viable projects. The tunnel would run beneath the river from Hammersmith in west London, collecting discharges from 36 CSOs, to a treatment plant at Crossness sewage works in east London. A link tunnel to Beckton treatment works is also planned.
Chairman of the independent steering group for the report, Chirs Binnie, said that a 15 year timescale was likely for the US$2.8bn scheme. The report described five years of planning, promotion and land acquisition. It was felt that construction could take up to eight years depending upon the final design selected.
Smaller scale interim measures may be required and a report on these is due later in the year. Binnie said: “The remit of the study does not include the promotion or delivery of the preferred solution; that is for others to undertake once Ministers and Ofwat [water regulator] have decided on a way forward.”
