Acton storm drain could link to 'super sewer'

Sep 15 2010 By Dan Hodges

STORM tanks in Acton could be used for a construction site linking local drains to a giant new 'super sewer' running the length of London.

Thames Water hopes to use its existing site in Warple Way to build a connecting pipeline for the Tideway Tunnel project, which it plans to construct over the next decade to stop raw sewage being discharged into the Thames.

Building work in Acton would last for around two years, and residents are now being asked for their their views on how the water operator might mitigate the local impact of the scheme.

Thames Water revealed this week that its preferred site for the entrance shaft to the main new sewer is at the Barn Elms sports ground in Barnes, with at least 20 smaller construction sites required along the length of the river.

Two other sites in Chiswick were rejected in favour of the Acton storm tank site, although work cannot begin until residents have been consulted and planning permission has been granted.

A document detailing the Acton proposals said: "It is a significant distance from the proposed route of the main tunnel so we would need to build a connection tunnel of approximately 2.6km in length, requiring additional construction works. The site is also near to residential properties.

"Specific measures may be necessary to reduce the environmental effects of construction and we would welcome your views on the issues we should consider when developing our proposals.

"We propose that construction traffic would enter and leave the site from temporary construction accesses off Warple Way.

"We are likely to require some above-ground structures on this site after the construction work has finished.
A ventilation column (approximately 10m high and 1m diameter) would be needed, along with a rectangular kiosk (approximately 1.5m high, 1m wide and 3.5m long) housing electrical and control equipment. We may also need a ventilation building on this site, similar to the one shown on the project information paper Greenwich Pumping Station.

"If this is the case we would not need the ventilation column and kiosk as they could be housed within one structure. We would leave the area around these structures as hard-standing to allow access for maintenance vehicles, but we could soften this with appropriate planting. The rest of the site would be returned to its original condition."

The £3.6bn project is expected to last at least seven years, with Thames Water admitting it will have an ‘adverse impact on the local community’.

Thames Water says the super sewer is essential, because London’s Victorian sewage system is unable to cope.
As little as 2mm of rain can cause untreated sewage to flow into the Thames through 57 overflow points across the city. If this did not happen, the sewage would back up and flood the streets.

The entrance to the sewer is planned be built at Barns Elms in Richmond.

A pipe the size of a Channel Tunnel bore will run up to 20 miles, broadly following the route of the river at a depth of up to 245ft, to Beckton Sewage Works in Newham.

Thames Water chief executive Martin Baggs said: "Allowing sewage to continue to overflow into the river at the current frequency is unacceptable.

"This causes significant environmental damage, killing fish and polluting the river for those who wish to use and enjoy it and affecting the well-being of our capital.

"We have done extensive studies to develop options for the tunnel route, which includes a solution that minimises the number of construction sites needed to build it, reducing the disruption for London.

"We haven't got all the answers, but through this consultation and speaking to people with local knowledge, we aim to get them."

Thames Water has now started a 14-week public consultation on the plans. It aims to submit a planning application in mid-2012, starting work 12 months later and finishing by 2020.

Several public exhibitions will be held between September 27 and October 22, leading to a second public consultation next year.

For a list of the exhibitions or to view the super sewer plans and comment on them, visit www.thamestunnelconsultation.co.uk.