Thames sewage tunnels take shape

Plans to redirect London's overflowing sewage away from the River Thames began to take shape as the Government identified two concrete solutions. The remaining question is whether there will be one tunnel or two.

As the capital’s rainwater is evacuated by the same pipes as its sewage, heavy rain and storms can lead to untreated effluent overflowing into the rivers Thames.

The long-debated problem led the Government to commission the <a href="

“>Thames Tideway Strategic Study, which pointed to a large-scale tunnel underneath the tidal Thames to intercept overflowing sewage as the best solution (see related story).

Now two concrete proposals of how this is to be done are on the table: a single 30km-long tunnel intercepting sewage along the length of the tidal Thames, or two shorter tunnels in West and East London that would tackle overflow discharges in these areas only. The tunnels would then send the overflowing sewage mixed with rainwater for treatment in East London.

Environment minister Ian Pearson said: “I am genuinely delighted we have reached this point today. I know this has been a painstaking and at times frustrating process for everyone, given both the urgent need to address the problem of sewage overflows, and the sheer scale and complexity of the issues and potential solutions.”

“The work between now and the end of the year will identify the solution that offers the right result for the quality of the River Thames, and for our capital city,” he said.

The tunnel or tunnels should improve water quality in the Thames and bring it in line with European norms. The upcoming 2012 London Olympics introduced a further element of urgency.

Thames Water, London’s sewerage systems provider, will be assessing the two options between now and the end of the year in partnership with the Environment Agency, Ofwat, Defra and the GLA, with a final decision expected in early 2007.

Goska Romanowicz

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