The second consultation on plans to build a “super sewer” under the Thames in London was launched last week (November 4) by Thames Water, which has now revised its earlier construction plans in response to opposition and feedback gained from its first consultation.

Under the latest proposals, the tunnel would run beneath existing infrastructure to transfer sewage that currently spills into the tidal Thames, to Beckton Sewage Treatment Works in east London, this would link with the Lee Tunnel, which is already under construction.

The project has been the subject of much controversy, despite the initial plans being approved by the London Assembly in December last year. Thames Water says the revised plans have taken public concerns over environment issues and long-term disruption into account.

As a result, alternatives to the two greenfield sites at Barn Elm playing fields and King’s Stairs Garden have been found, along with the implementation of measures to minimise the overall disruption caused during construction.

However, the use of brownfield alternatives, as well as other factors, is estimated to increase costs by about half a billion pounds, with the overall cost for the project calculated to be £4.1bn at 2011 prices. This is estimated to add around £70 – £80 a year to the average bill from 2013.

New proposed locations for the tunnel’s drive sites includes Carnwath Road Riverside in Fulham, Kirtling Street in Battersea and Chambers Wharf, a riverside brownfield development site in Bermondsey. Excluding minor works, the revised plans will involve the use of 22 sites for the tunnel’s construction, compared to the 23 proposed a year ago.

In addition, the proposal suggests the increased use of river transport to carry construction materials in a bid to avoid further congest to London’s roads, however again this will cost more.

As a result of the changes, the main construction work on the tunnel is now provisionally scheduled to begin in 2016 and is expected to last six years.

Prior to the initial consultation, the Environment Agency (EA) identified 34 “unsatisfactory” combined sewer overflow points built into the existing network, which it says the tunnel to address and has now offered its support of the project.

EA chairman Lord Chris Smith said: “London’s sewerage network has nearly reached its capacity. In future due to increased population and volume of sewage it will exceed its capacity. This will steadily worsen the impact of the overflows as they will spill sewage more frequently into the river.

“Doing nothing is not an option. We consider the Thames Tunnel the best solution available to limit pollution from sewage in the Thames. We will continue to work closely with both the Government and Thames Water as the second phase of consultation progresses over the next 14-weeks.”

Meanwhile, a group of London borough councils chaired by Lord Selborne published a report of the Thames Tunnel commission last Monday (October 31), in which a cheaper shorter tunnel option was called for.

However, Thames Water said the commission failed to provide a credible alternative to the super sewer and insisted that the new plans are necessary to meet EA river quality standards.

Thames Water head of Thames Tunnel project Phil Stride, said: “Nothing in the report begins to suggest a workable alternative to the Thames Tunnel, capable of meeting the objectives for the health of the river, set by the Environment Agency, in the timescale required by the Government.”

Consultation on the revised plans will last 14-weeks, ending on February 10 2012.

Carys Matthews

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