This is entry number 164, first published on 14 September 2010, of a blog on the implementation of the Planning Act 2008. Click here for a link to the whole blog.

Today's entry reports on the disclosure of the preferred Thames Tunnel route and the launch of consultation on it.

Thames Water has been working on a major project to provide additional sewage capacity in London. Yesterday, it launched the first round of public consultation on its proposed 'Thames Tunnel', which also revealed its preferred route and proposed land take for shafts to build and access the tunnel.

The Thames Tunnel is to be a 32km tunnel tracking the Thames but 70 metres below ground that will carry sewage, particularly during heavy rain conditions. At the moment the so-called 'combined sewer outflows' (CSOs) discharge into the Thames when there is so much rainwater that the existing system cannot cope. In other words, do not swim in or fall into the river during or after heavy rain!

Last week the government announced that this would be deemed a nationally significant infrastructure project (NSIP), which continued the policy of the previous government, and so it will use the Planning Act regime. A sewer is not actually listed in the Act as an NSIP, only a sewage works, but for the first and so far only time the government will use its powers to declare a project outside the definitions in the Act to fall within it.

As previously mentioned, the declaration cannot happen until an application is actually made for the project. Thames Water ought therefore to prepare and make 14 separate planning applications to the boroughs (and the City) along the route. It will be interesting to see if they do go through the full charade or just put one or two applications in. The forthcoming Localism Bill may also amend the Planning Act in time to allow an earlier declaration by the government.

The route

The proposed route is shown below in brown (!) (image reproduced with kind permission of Thames Water) - to see a legible version visit the Thames Water consultation website and click on 'Tunnel route' on the left.

Please click here to see the route map.

The favoured route is shorter than had previously been suggested, because rather than tracking the river all the way from Hammersmith to Beckton, the tunnel is to leave the river at Bermondsey and travel underground to Abbey Mills, where it can join the Lee Tunnel (already under construction) to Beckton. The western end of the route had also not been fixed, but is now to be at Hammersmith Pumping Station with a connecting tunnel to storm tanks in Acton.

Not only is this the first off-piste NSIP, it is the first and to date only project proposed in London, and will no doubt receive a disproportionate amount of media attention as a result. It probably has the most 'host' authorities of all current IPC projects to boot. The authorities that will contain parts of the project are a long enough list: Ealing, Hounslow, Richmond, Hammersmith and Fulham, Wandsworth, Kensington and Chelsea, Westminster, Lambeth, City of London,Southwark, Tower Hamlets, Lewisham, Greenwich and Newham. Adding their neighbours, who will also have a role in the authorisation process, means that every London borough except Sutton, Havering, Haringey, Enfield and Barnet joins the list, as well as three outside London: Elmbridge, Spelthorne and Surrey.

Land taken

Thames Water have sought to reduce the land to be taken for the project, and if their favoured proposal is adopted will only construct 17 CSO shafts instead of 34. There will also be three instead of six larger shafts where the tunnel boring machines used to dig the tunnel will be launched. These are at Barn Elms Sports Ground in the Borough of Richmond, Tideway Walk, Nine Elms in Wandsworth and next to the Lee Tunnel shaft at Abbey Mills in Newham. The tunnel shafts will involve temporary occupation of a fairly large site each and some permanent land take. The smaller sites will also involve some small-scale land take.

The tunnel will be 7.2 metres in diameter, making it larger than the Crossrail tunnels, which are a mere 6.2 metres.

The consultation

The consultation website is here and has quite a nifty interface with google maps that allows you to pan and zoom in on the surface sites proposed and link to documents about them.

The consultation will run until 5 p.m. on 20 December. As the project is not yet an NSIP, this is not officially a pre-application consultation under the Planning Act, but Thames Water will no doubt be seeking to use as much of it as it can in its Planning Act preparations when the time comes.

If you register you will get updates - today I received the first edition of 'Tideway Times' (the project used to be called the Thames Tideway Tunnel), that gives more details about the project and also 14 public meetings being held on the subject in September and October.