London Tideway Tunnels
Thames Tunnel - response to concerns raised by LB Hammersmith & Fulham
In a letter to other London local authorities (December 2009), Cllr Paul Bristow (LB
Hammersmith & Fulham) questioned the need for the Thames Tunnel. Here is our
response to the concerns he raised:
1: The needs case
The proposed tunnel is not simply a matter of ensuring compliance with the Urban
Wastewater Treatment Directive (UWWTD), extremely important though that is.
London’s largely Victorian sewerage system urgently needs additional capacity, not just to
protect the River Thames, but to ensure the capital has a robust sewerage system able to
cope with the impact of population growth, more intense rainfall patterns and the reduction
of green space available to soak up rainfall.
The situation is already serious. As London’s sewers capture rainwater ‘run off’ from roads,
pavements and roofs, as well as sewage from customers’ properties, the overflows are
currently far from occasional. They occur more than once a week on average. Annually they
now discharge an estimated 32 million cubic metres of untreated sewage into the river,
enough to fill the 02 Arena 15 times.
Huge improvements have been made over the last 150 years in improving the quality of the
River Thames, but we will lose ground if we don't do more, in the face of population growth
and climate change. Since privatisation in 1989, major investment at our sewage treatment
works has greatly accelerated the clean up of the River Thames. Biologically dead for many
years, there is now a much greater diversity of wildlife in the river that needs to be protected
from the increasingly frequent overflows of sewage into the river. The Thames Tunnel will
play a key role in ensuring that the excellent progress we have made in recent years is not
reversed.
It cannot be stressed enough that we are also planning to continue major investment to
tackle the separate but equally important problem of sewage flooding customers’ properties.
For example, Ofwat has recently given the green light for us to develop a major scheme
addressing this issue in the area around the Counters Creek, affecting both the boroughs of
Hammersmith & Fulham and Kensington & Chelsea.
2: Alternatives considered
The Thames Tunnel and the Lee Tunnel have already been subject to many years’ detailed,
independent evaluation.
A wide variety of parties, such as the Environment Agency, the Greater London Authority
and Defra were involved in the Thames Tideway Strategic Study (TTSS), chaired by
Professor Chris Binnie, which published its findings in 2005.
Prior to making its decision to progress a tunnel-based solution, the Government also
considered a review of the TTSS by consultants Jacobs Babtie, commissioned by Ofwat on
behalf of customers.
Appendix 3 - Thames Tunnel
London Councils' TEC - 18 March 2010
The key reasons why the other suggested approaches have been discounted are set out
below:
•
‘Re-plumbing’ London with a new sewerage network that separates out sewage
from rainwater. Aside from the extraordinary disruption this would cause, the cost (at
least £12bn) would be prohibitive. Such a huge investment programme could only be
implemented over an extended period and would have an unacceptable impact on
customers’ bills. It is no exaggeration to say this approach would grind London to a halt.
The likely impact would dwarf that of our on-going work to replace the capital’s Victorian
water mains. The requirement to install many new pumping stations would also
contribute to a carbon footprint much greater than the one likely for the Thames Tunnel.
•
Implementation of Sustainable Drainage System (SUDS). Retrofitting these types of
systems at the size required in London, an already densely urbanised environment is
impractical. There is simply not enough open space available. Any limited
implementation would be very disruptive and costly, but not very effective at reducing
Combined Sewer Overflow (CSO) discharges. The clay sub soils in London also make
SUDS a less suitable option.
•
Installation of screens at CSOs to reduce the volume of litter reaching the river.
This approach would not tackle the underlying problem of sewage polluting the river. At
most of the CSO locations installing screening plant would also be prohibitively
disruptive and technically unfeasible, due to physical constraints. The location of many
of the outfalls close to bridges, major roads, buildings and tube lines would render the
exercise all but impossible. It would also be incapable of dealing with the growing
volumes of excess flows – the screens would rapidly become blocked and risk sewage
backing up into buildings and streets across the capital.
•
Deploying more vessels on the river to inject oxygen into the river and skim off
sewer-related litter. Given the growing frequency of the overflows, a bigger fleet of
‘Bubbler’ and ‘Skimmer’ boats would be a sticking plaster solution, treating only the
symptoms of the problem, not the cause. This would not be sufficient to meet the
requirements of the UWWTD and would require a large fleet of vessels.
In decades to come the tunnel will be an extra safety net capturing flows generated during
dry weather, not just those generated by storm conditions.
3: Construction impacts
It is crucial to point out that we have taken no decisions on the route the proposed tunnel
needs to take from west London over to Beckton Sewage Treatment Works, where the flows
will be treated and returned to the river. We are currently working to identify the locations
we will need to construct and operate the tunnel.
At this stage speculation about the likely construction impacts remains exactly that –
speculation.
We are determined, where possible, to do all we can to reduce the Thames Tunnel’s impact
on local communities. For example, where practicable we intend to use the river itself to
transport materials. In considering the options as they emerge, we are keen to fully
understand the aspirations of stakeholders potentially directly affected by the tunnel’s lasting
physical legacy at ground level.
Appendix 3 - Thames Tunnel
London Councils' TEC - 18 March 2010
4: Cost
It is undeniable that our 13 million wastewater customers will face higher bills to pay for the
London Tideway Tunnels, just as people in south west England, for example, have paid for
improvements to sewage treatment works in the interests of cleaner beaches, at a much
higher cost per head.
Updated projections in December 2006 suggested the Lee and Thames tunnels would
together cost approximately £2.2 bn. That remains the latest public figure, but a lot of
planning work has still to be completed for the Thames Tunnel before we can be in a
position to issue a more robust estimate.
The 2006 estimate was published by the Government, when they instructed us to take
forward the tunnels solution. At the time only two per cent of design work for the Thames
Tunnel was in place. We are now in the process of working up a much more detailed
scheme. We will announce an updated cost estimate later in 2010 when we launch our
public consultation on our preferred sites for the Thames Tunnel’s construction and
operation. It would be an unacceptable hostage to fortune for us to commit ourselves to a
cost figure before we have completed all our preliminary assessments.
It important to stress that the need to keep costs down is in itself a reason why the Thames
Tunnel is planned to control or intercept the 34 CSOs that the Environment Agency (EA) has
identified as the most polluting. Devising a scheme capable of capturing all flows from all the
57 CSOs would be financially imprudent, even if technically possible. As part of our
preliminary work to design the tunnel we have installed monitors to verify the EA’s data.
The tunnels will bring economic benefits too, for example creating an estimated 4000 jobs.
The financial implications for the UK of not complying with EU directives are potentially
substantial. Penalty fines can be very significant, particularly because of the ‘daily fines’
element, which continue until a member state is compliant with a European Court
judgement.
On top of this there would be the continuing cost to the environment and increasing potential
health risks for people who come into phyiscal contact with the river, either for work or
recreation.
5: Carbon footprint
We are determined to ensure that the construction and operation of the Thames Tunnel
minimises carbon emissions as far as possible. For example, where practicable, we intend
to use the river itself to transport materials.
For the Lee Tunnel we prepared an Environmental Impact Assessment (EIA) and an energy
assessment. When we have a preferred scheme in place we will do the same for the
Thames Tunnel.
6: Consultation
The route for determining planning approval for the Thames Tunnel will be a matter for
politicians to decide, not Thames Water.
Appendix 3 - Thames Tunnel
London Councils' TEC - 18 March 2010
Just like members of the public, we are bound by decisions made by the democratically
elected Government of the day.
Irrespective of who considers our application(s), due to be submitted in late 2011, we are
committed to a full and proper consultation process. We want to work in partnership with
local authorities, communities and other stakeholders to mitigate any impacts. This is why
we have begun our consultation and engagement work at a very early stage.
The statutory planning process will quite properly allow the general public to examine the
detail of our proposals, when fully evolved.
January 2010
Appendix 3 - Thames Tunnel
London Councils' TEC - 18 March 2010