Details revealed in plans for massive Thames Tunnel Project

The multi-billion project to reduce sewage overflow into the Thames will involved the construction of an expanded sewage tunnel under parts of Chiswick including Bedford Park and Chiswick Mall.

In consultation documents released on Monday 13th September by Thames Water more details of the scheme have been released showing that the Acton Storm Relief site on Warple Way will be the main construction site for local work in relation to the massive project.

Part of the £3.6 billion project involves connecting the local combined sewer overflow (CSO) at the Warple Way site, to the main tunnel of the proposed Thames Tunnel project. This will involve the building of a 2.6km tunnel which maps on the consultation document suggest will pass under Abinger Road, Welstead Way, Netheravon Road and Chiswick Mall. When completed the sewer overflow at Chiswick Eyot will be closed improving water quality in the river significantly.

A spokesperson for Ealing council said, "While the preferred site and proposed route will affect a small proportion of residents, the financial implications will affect everyone in the borough and we encourage all residents to take the opportunity to have their say about these proposals."

Thames Water is proposing to use land within their existing site on Warple Way near the Factory Quarter development for this construction work and to accommodate permanent structures required to operate the tunnel.

The site of the former Chiswick Maternity Hospital on Netheravon Road South was identified as a potential site when the project was initially conceived as it was vacant but since then planning permission has been given for the development of residential properties. It is no longer considered a viable option. Although not the preferred site, the car park on Welstead Way (which runs Southbound from Bath Road parallel to Prebend Gardens) remains in the running. The site is surrounded by residential properties on three sides so any construction
works would be close to residents' homes.

It is from CSOs like the Acton Storm Relief that untreated sewage is discharged directly into the river. Thames Water claim that London’s mainly Victorian sewerage system, which was designed to transport both sewage and storm water is at or near capacity. Some CSOs discharge untreated sewage into the River Thames on average more than once a week and after only 2mm of rainfall. This situation is likely to become worse in the future, due to population growth and increased urbanisation.

Starting in west London and broadly following the path of the River Thames through the centre of the capital, the main tunnel would transfer the flows from the most polluting CSOs to Beckton Sewage Treatment Works in the east of the city. The main construction site at this end of the tunnel is reported to be at Barn Elms near the Barnes Wetlands Centre. The construction site will be the size of six football pitches.

Thames need a significant number of sites to construct the Thames Tunnel project. Large ‘shaft sites’ are required at certain points along the route to allow the construction of the main tunnel. Smaller ‘CSO sites’ are also required near each of the most polluting CSOs to connect them to the main tunnel.

The publication of more details about the project represents the first round of public consultation on the project. Public exhibitions will be held in Acton and Hammersmith in September but not Chiswick where the proposed tunnel may have the most significant impact.

A spokesman for Thames Water told ChiswickW4.com, "Whilst we remain flexible, and will consider all suggestions made on the need for further exhibition venues, we currently feel the list we have proposed is sufficient."

He added, "Our consultation strategy has been developed in liaison with all the potentially directly affected local authorities, including Hounslow and Ealing."

We have asked both Councils for comment and await their response.

Thames Water hope to have planning approval by 2012 and aim to start work in 2013 with completion in 2020.

September 24, 2010