- Updated Thames Tunnel proposals feature reduced use of greenfield sites.
- Plan for 90 per cent of soil from main tunnel ‘drive sites’ to be transported away by barge or rail.
- Project set to boost economy, directly creating an estimated 4,000 jobs.
A 14-week consultation starts today on Thames Water’s revised plans for the proposed Thames Tunnel, needed to help tackle the 39 million tonnes of untreated sewage that overflows annually into the River Thames from London’s Victorian sewerage network. Full details are available at www.thamestunnelconsultation.co.uk.
Following a statement to Parliament by Richard Benyon, Parliamentary Under-Secretary for Natural Environment and Fisheries (3 November 2011), confirming the Government’s support for the project, Thames Water has announced its updated list of preferred sites for the tunnel’s construction and operation. These reflect the feedback received during the first phase of consultation (September 2010 – January 2011) and ongoing work to minimise overall disruption and cost.
The Environment Agency identified the 34 most polluting ‘Combined Sewer Overflow’ points (CSOs), built into the existing sewerage network, that the proposed tunnel needs to tackle. Running beneath all other infrastructure under the capital, the tunnel would transfer the discharges to Beckton Sewage Treatment Works in east London, linking up with the Lee Tunnel, already under construction.
Thames Water’s site selection process, developed in consultation with the potentially directly affected local authorities and others, has identified three ‘main drive shaft’ sites, needed to launch the machines that will burrow the 7.2 metre diameter wide tunnel, broadly following the route of the river bed, from Acton to Abbey Mills, near Stratford. Different types of machines are needed, as the tunnel will have to cut through a variety of soil conditions, ranging from clay in the west, through sands and gravels in the centre, to chalk in the east.
The new proposed locations for the main tunnel drive sites are:
Carnwath Road Riverside in Fulham. Whiffin Wharf, Hurlingham Wharf and Carnwath Road Industrial Estate have together replaced Barn Elms Playing Fields, the previously preferred site on the Richmond/Wandsworth border. This change has the benefit of using brownfield land rather than greenfield. Other factors influencing the switch include the need to reduce potentially serious health and safety risks to river users during the construction phase. The location of the Carnwath Road sites, downstream of Putney Bridge, also means fewer, larger barges could be used to transport materials from the site. A further benefit would be bringing the safeguarded Hurlingham Wharf back into use, in line with the aims of the London Plan. Using the Carnwath Road sites would also: avoid the need to divert a busy section of the Thames Path, prevent the temporary loss of a number of well-used sports pitches, and still allow the local council’s proposals for new development to regenerate the South Fulham Riverside area.
Kirtling Street in Battersea. The proposed site covers land currently occupied by warehouses (some of which are vacant), offices and a ready-mix concrete works. It replaces Tideway Walk, the previously preferred site. In March 2011 a developer received planning permission to develop the Tideway Walk site, mainly for housing. Work then started on site, requiring the Thames Tunnel team to find an alternative location.
Chambers Wharf, a riverside brownfield development site in Bermondsey, replacing King’s Stairs Gardens, a park in nearby Rotherhithe. This site was not proposed at phase one consultation, because at that time its owners were taking forward housing development on site, having secured planning permission. A decision by the owners November 2010 to sell the site meant that, in partnership with a housing developer, Thames Water was able to buy it so that it could be considered in detail as a possible alternative to King’s Stairs Gardens. The site is now proposed to be used to launch a tunnelling boring machine travelling to Abbey Mills, a Thames Water operational site near Stratford. The proposal for King’s Stairs Gardens at phase one consultation was for the machine to travel in the opposite direction (from Abbey Mills). The project team has concluded that transporting excavated materials away from Abbey Mills by river would pose major logistical difficulties. Tidal and navigational impacts, for example, would seriously constrain the ability of barges to remove the materials in sufficient volumes.
The Chambers Wharf site is also needed to receive a smaller tunnelling machine, departing from Thames Water’s sewage pumping station in Greenwich High Road. This would create a connection tunnel feeding discharges from south east London CSOs into the main Thames Tunnel.
Excluding minor works, 22 sites are needed to construct the Thames Tunnel, compared to the 23 envisaged a year ago.
In addition to the three main tunnel drive sites, and two main tunnel reception sites a total of 17 other, smaller construction sites are also proposed to intercept or control the flows from the 34 CSOs into the main tunnel: The CSO interception site originally proposed at Jews Row in Wandsworth is no longer needed. Instead this is to be tackled by adapting the configuration of flows within the existing network. Much reduced construction work at alternative nearby sites is also proposed to replace the activity previously proposed at Butcher Row (Limehouse) and a children’s playground in Druid Steet (Bermondsey).
Phil Stride, Head of London Tideway Tunnels at Thames Water, said: “We have been working hard to refine our original plans, where possible, in the light of the concerns people have raised with us. This has resulted in some significant changes, also reflecting our absolute determination to balance overall disruption with the equally important need to ensure that the price tag remains affordable for our customers.
“There are no easy choices when it comes to selecting construction sites, but our focus during this latest phase of consultation will be to work with communities around our revised list of preferred sites to ensure we understand and address their concerns effectively. It is particularly important that we listen to local people’s views on what individual sites should look and feel like after construction work has finished.”
The changes to Thames Water’s original plans mean that main construction work for the tunnel is now provisionally scheduled to begin in 2016 and expected to last six years. The company’s revised estimate for the total capital cost of the project is £4.1bn at 2011 prices, excluding inflation. This reflects changing factors, such as the increased use of brownfield land and the plans to use the river to transport excavated soil from main shaft sites, where it makes practical and economic sense to do so.
Phil Stride added: ‘It’s clear to us that, where viable solutions can be implemented at a reasonable cost, we should make good use of the river to transport construction materials to and fro, particularly soil excavated during the construction of the main tunnel. This is generally more expensive, but we are acutely aware of the need to avoid unnecessarily adding to congestion on London’s busy streets. The potential to use rail is also one we are actively pursuing.”
The project’s construction would not have any impact on bills before 2013 at the earliest. The maximum impact is likely to come a few years later and is estimated to be in a central range of £70-80 per year, again expressed in 2011 prices. The uncertainty reflects the difficulty in estimating the financing costs for a project of this scale and duration. This means that Thames Water’s average wastewater charges, which have for many years been among the lowest in the country, would rise to around the national average. Ofwat, the water industry’s independent economic regulator, will scrutinise all aspects of the project to ensure costs are kept as low as possible.
A series of local drop-ins, starting on 17 November, will give all interested parties an opportunity to discuss the details of the proposals with the Thames Tunnel project team.
The closing date for comments is 10 February 2012 at 5pm.
