3-TT Case Leaflet AW FINAL for Web

8/6/2019 3-TT Case Leaflet AW FINAL for Web

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Why does

London need theThames Tunnel?

TheRiverThamesisnot

ascleanasyoumight

think.Sewagefromouroverstretchedsewernetworkispollutingthecapitalsriver.

JULY 2011


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Ten reasons whyLondonneeds

theThames Tunnel

The River Thames has become an

environmental and public health hazard.

Sewage regularly overfows into theriver rom Londons Victorian

sewerage system.

The current network o major sewers,

ounded 150 years ago, was designed

or a city o our million people and is no

longer big enough to meet the needs

o modern day London. The citys

population is now approaching

eight million.

In a typical year, the citys sewers

discharge 39 million cubic metres* o

untreated sewage into the River Thames

enough to ll the Royal Albert Hall

450 times.

The discharges are the last

signicant source o pollutionin the tidal River Thames. Mixed with

rainwater, the sewage content o the

discharges ranges rom 10 to 90 percent,

depending on conditions.

This pollution kills sh, damages wildlie

and carries pathogens such as hepatitis

A and aecal streptococci, which threaten

human health. Its a serious problem

and getting worse.

More requent and intense storms,

especially in summer, are adding to the

problem, as is the loss o permeablesuraces able to soak up rainall. As little

as 2mm o rainall can now trigger a

sewage discharge.

Years o independent study have

concluded that the Thames Tunnel is a

timely and cost-eective part o the

solution. Alternative options would cost

more, be more disruptive and would

not achieve the environmentalstandards required.

British taxpayers would be at risk o

having to und hety nes rom the EU i

the UK is conrmed to be in breach o

the Urban Waste Water Treatment

Directive.

Other world-leading cities, includingParis, Stockholm, Helsinki and

Washington DC, are orging ahead with

similar schemes.

A clean, healthy River Thames is

essential or the prosperity and global

reputation o Britains capital city.

Future generations would never

orgive us or ailing to tackle this

unacceptable problem.

*one cubic metre o sewage equals 1,000 litres and weighs around one tonne


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SOUTH

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NORTHERN

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Like many older cities around the

world, the vast majority o Londonis served by a combined sewerage

system, collecting sewage (rom

toilets, sinks and washing

machines etc) together with

rainwater run-o rom roads,

roos and pavements.

The magnicent interceptor

sewers, constructed by Sir Joseph

Bazalgette ollowing the GreatStink o 1858, are still the

backbone o Londons sewer

network today. Rebuilding this

system, using modern methods,

would cost 50-60 billion today.

The citys natural drainage

system, which is a network o

waterways (the so-called Lost

Rivers o London, such as the

Fleet and the Tyburn), had been

built over and was already

conveying sewage when Sir

Joseph Bazalgette incorporated it

into his impressive design. The

system was designed so that

overfows would go into the River

Thames, preventing the back up

o sewage fooding peoples

homes and streets. The system

does this through a network o

CSOs, stretching along the

River Thames.

A brie history

While they are still in excellent

condition, Londons Victoriansewers now lack the capacity to

meet the demands o the vastly

increased population and 21st

century development o the

capital. As one o the worlds

busiest cities, Londons CSOs

discharge more and more

requently into a river which, in

every other respect, is

much cleaner and morevaluable to Londoners.


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THAMES

SOUT

HERN OUTFA

LL SE

WER

NORTHERNOUTFALLSEWER

EWER

Its time to updatethe capitalssewer network

Case study0n 6 June 2011, ater 30mm orainall, more than 250,000 cubic

metres o sewage rom CSOs at thewestern end o the River Thamesdischarged into the river. This isequivalent to over 40,000 buildersskips ull o sewage. Mogdensewage treatment works alsodischarged around 230,000 cubicmetres. The CSO at HammersmithPumping Station discharged about80,000 cubic metres o sewageover a period o about eight hours.This is equivalent to one builders

skip every two seconds.

*Daily Telegraph 8 June 2011

4

In Bazalgettes day, just over two

and a hal million people lived in

London. Sir Joseph had the

oresight to design his system to

serve our million, but today the

citys population is near to eight

million and continues to grow.

Back in the 1850s, not only werethere ewer people living in

London, but they also used less

water per head and there was

considerably more green space

available to soak up rainall. This

meant that overfows occurred

only very occasionally, and when

they did they went into a river

that was almost entirely

biologically dead.

In 2001, Greater Londons

population density was

18,457 people per square

kilometre, compared to just

6,825 per square kilometre in

Bazalgettes day.

As the population o London

has grown, so has the

development o the capital,

involving the building on and

paving over o large areas. This

has altered the natural drainage

o the area so that now most

rainall and surace water run-o

goes directly into Londons

sewers, rather than being

naturally absorbed into

permeable ground. An area twice

the size o Hyde Park has been

lost to hard suracing every year*.

CSO discharges now happenmore than once a week on

average and as little as 2mm o

rainall can trigger a discharge.

Climate change adds to the need

or action. Rises in average

temperatures will make the river

water warmer and thereore able

to hold less dissolved oxygen,

which in turn will make its

aquatic lie more sensitive to

any pollution.


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Acton

Mogden

The big pictureWithout the London TidewayImprovements, the annual CSOdischarges would reach 70 millioncubic metres in a typical yearby 2020.


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just serving a ew CSOs in the

west would have even more

limited volume and thereore

provide less overall CSO control.

The enhanced primary treatment

plant at Abbey Mills would only

remove a small proportion o the

polluting load. Thereore theenvironmental objectives would

not be met. The deployment o

skimmer crat to remove sewage-

derived litter in the river rom the

remaining unconnected and

uncontrolled CSOs would not

reduce the polluting load in

the river. It would also not be

compliant with the UWWTD.

More recentdevelopments

In March 2007, the Governmenttasked us with taking orward a

tunnel solution to substantially

reduce discharges o untreated

sewage into the River Thames and

its tributary, the River Lee.

In September 2010, the incoming

Coalition Government conrmed

its support or the Thames Tunnel,

subject to a strict review o costs,

and instructed us to continue

developing the project.

A Thames Tunnel continues to offer by far the

lowest cost solution to the problem. Caroline Spelman Secretary o State or the Environment,Food and Rural Aairs, September 2010.

Case studyThe 30mm o rainall on 6 June

would have completely lled the

west tunnel o the Jacobs Babtie

option and overfowed more than

50,000 cubic metres o sewage to

the river. The CSOs betweenVauxhall Bridge and the Thames

Barrier, which would not have been

intercepted by this option, would

have discharged approximately

500,000 cubic metres o sewage

into the river.

It would have taken over our days

to empty the west tunnel via the

existing sewage system, meaning

that the tunnel would not havebeen completely empty or the

next signicant rainall, which

arrived on 10 June. The west tunnel,

thereore, would not have been

ully empty or over 16 days,

resulting in septic sewage and

odorous conditions. By comparison,

the Thames Tunnel would have

intercepted all the CSO fows or

treatment, with no discharge into

the river, and have been emptiedwithin 48 hours.


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Reasons

to act nowA personal view from Olympic goldmedal rower Andy Triggs HodgeI regularly row on the River Thames, which means paddlingthrough human aeces, tampons, condoms and other such

nasties. It is no un at all and the volumes involved are

rightening.

Its a problem that risks the health not just o rowers but o

river-users o all kinds, not to mention the devastation it

causes to sh and other wildlie.

I do have a personal interest. But theres more to it than that.

This is about protecting Londons river, not just or today but

or uture generations, making it something we can all beproud o rather than a great big overspill sewer or a 21st

century city that should know better.


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Human

The human and domestic waste

content o the discharges, along

with waste rom businesses andcommercial properties, is mixed

with rainwater in varying

proportions, but the discharges

are unmistakably sewage and

must be treated as such.

Raw sewage entering the River

Thames contains urine and

aeces, as well as sewage-derived

litter such as toilet paper, wipes,

sanitary products and other

fushable items, including

hypodermic needles. Such raw

sewage typically contains

health-harming pathogens,

viruses and bacteria such as

E coli, hepatitis A and aecal

streptococci.

The requency o CSO discharges

is thereore a hazard to all whouse the river. There are over 30

canoeing, rowing and sailing

clubs using the tidal Thames, the

oreshore is used by thousands o

people every day and the river is

a draw or hundreds o thousands

o tourists every year.

It cannot be acceptable to

allow the River Thames to beused as an open sewer.

Environmental

The Thames Tideway is an

important habitat or a wide

variety o sh. It is an importantbreeding and nursery ground or

many species, including smelt

and others. Some o these, such

as sole, are commercially

important.

Improving water quality in the

River Thames will improve the

conditions to sustain healthy sh

populations and permit the

upstream migration o species,

such as salmon, bass and

founder, which use the tidal

Thames as an important part o

their liecycle.

The River Thames is particularly

vulnerable to pollution because

o its limited dilution capacity.

The tidal eect moves water up

to 15km up and down the RiverThames on each fow and ebb

tide. The net movement, during

neap tides and low river fow, is

as little as one kilometre per day

towards the sea, with very little

mixing. Larger rainall events

create slicks o polluted water

that move with the tide and it

can take up to three months*

or sewage that has enteredthe uppermost reaches o the

Thames Tideway to reach the

sea. Furthermore, solid material

such as sewage-derived litter

will tend to be deposited on the

oreshore during the ebb tide.In act, much o the ne silty

mud ound on the rivers

oreshore and slipways is derived

rom sewage.

It can take up to threemonths* or sewage that has

entered the uppermostreaches o the ThamesTideway to reach the sea.

Expected increases in

temperatures linked to climate

change will make the River

Thames more sensitive to

pollution. The CSO discharges

to the river will deplete dissolved

oxygen at a aster rate,

endangering the number and

variety o species o wildlie

able to survive in its waters.

*Figures supplied by the Environment Agency.


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Legal

The EU Urban Waste Water

Treatment Directive (UWWTD)

requires that urban wastewater

(sewage) should be properly

collected and treated, other than

under exceptional conditions.

The Water Framework Directive

(WFD) also aims to maintain and

improve the aquatic environment

in the EU by 2027.

The European Commission

initiated so-called inraction

proceedings against the UK in

relation to the Thames Tideway

as long ago as 2004 and hasrepeatedly made clear its

intention to enorce the UWWTD.

Any delay in compliance makes

inraction proceedings more

likely. The case has now been

reerred to the European Court

o Justice.

I the court nds against the UK,

the Government is at risk o

substantial nes i the Thames

Tunnel is not completed quickly.

Fines are calculated using

equations that consider the

duration and seriousness

o the inringement and the

individual Member States

capacity to pay. The maximum

daily penalty payment that could

currently be imposed on the UK

is 620,000 per day. Theminimum size o a lump sum

payment that could currently be

imposed on the UK is 8,500,000

and there is no maximum lump

sum payment. All UK tax payers

may have to help oot the bill.

Case study

Ater heavy rainall during the rst weekend o June 2011, more than250,000 cubic metres o sewage was released into the river rom CSOs

and at least 230,000 cubic metres o sewage rom the Mogden Sewage

Treatment Works in Isleworth. These discharges, exacerbated by the

warm, dry weather and subsequent low river fows, resulted in very low

oxygen levels and sh deaths in a two kilometre stretch o water. This

moved with the tide, depositing dead sh onto the oreshore over a wider

area. More than 26,000 sh were killed between Barnes and Chiswick.

Species aected included founder, bream, roach, eel and dace. In

addition, signicant amounts o other aquatic lie, such as water shrimps,

were also killed. The Environment Agency conrmed it was the second

largest sewage pollution incident along the River Thames in the pastten years.

Even if the Directives did not exist,London still needs the Thames Tunnel.Without it, the pollution of the riverwill get worse and improvements madewill be lost, given the increasingpopulation, new development and theimpact of climate change.


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Isnt the River Thames the cleanest its ever been forwildlife? Why do we need to do anything?Since the privatisation o the water industry in 1989, major investment at our sewage treatment

works throughout the Thames Valley, paid or by customers, has greatly accelerated the clean up o

the River Thames. But we will lose ground i we do not tackle the CSOs in London. Once the sewage

treatment works upgrades are complete, the CSO discharges will be the tidal rivers last remainingsignicant source o pollution.

Biologically dead or many years, there is now a much greater diversity o wildlie in the river that

needs to be protected rom the increasingly requent overfows o sewage into the river. The proposed

Thames Tunnel will ensure that the excellent progress in cleaning up the river is not reversed.

Effects of raw sewage on thefish population are bothimmediate and long term.Bacteria feeding on the sewagediminishes oxygen levels whichcan have a devastating effect,especially on juvenile fish, as

they are less likely to swimaway from the affected areas.This leads to large numbers offish fry being killed and asignificant reduction in futurefish stocks.


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ChallengesEnsuring valueor money

Owat sets limits on water bills

in line with the work that water

companies need to do, and will

continue to scrutinise the

Thames Tunnel costs to ensure

they are kept as low as possible.

As a result o Sir Joseph

Bazalgettes oresight and

previous low levels o investment,

Thames Water sewerage bills are

almost the lowest in the country.

Building the Thames Tunnel will

require a signicant increase to

bills. This is a necessity i we are

to carry on Sir Joseph

Bazalgettes legacy and invest in

a sewerage system that will last

or uture generations.

Why should allThames Watercustomers have topay or the ThamesTunnel when it will

only be Londonerswho will beneftrom it?

The costs o serving the

Thames Water region are spread

out over a very large number

o customers, including all those

in London. Those outside London

are beneting, and will continue

to benet rom this act.

It is only air that bill increases

are shared across our region.

Customers outside London have

seen big improvements rom

investment in sewage treatment

locally, while paying the lowest

water and sewerage bills in the

country or most o the past

20 years.

While the Thames Tunnel is a

very prominent example o a

project taking place in one part

o the region we serve, there are

numerous examples o

investment beneting towns,

villages and hamlets throughout

the area we supply outside the

capital. These are oten projectscosting several millions o pounds

to improve pieces o

inrastructure that serve tens o

thousands or even just a ew

thousand people.

For instance, we are upgrading

Crawley and nearby Merstham

sewage works, which includes

increasing their capacity to meetpopulation growth, at a total

cost o 36.5m. These sewage

works serve a combined

estimated population o just

169,000 people.

As the diagram shows, in the

more rural areas that

neighbouring water and

sewerage companies supply, billsare signicantly higher.

Average waste water charges 2011/12

147

Severn

Trent

Wessex

Anglian

Southern

221

255210

123


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Minimisingdisruption

A key ocus or us has been to

optimise the route o the Thames

Tunnel, to ensure we can deliver

the most cost-eective solution

and minimise disruption.

The number o construction sites

now required or the preerred

route is less than hal that we

outlined in our initial plans, and

we are working hard to try and

reduce this number urther.

We will use modern tunnel boring

machines (TBMs) to build our

main tunnel rom Hammersmith

to Abbey Mills and many o the

smaller connection tunnels to

our CSOs.

The CSOs tend to be located

where the sewers enter the River

Thames, which is also where the

original natural drainage

channels o the land entered the

river. These channels were

generally at right angles to the

river and were incorporated into

the trunk sewers in Sir JosephBazalgettes design.

These sewers need to be

connected to the Thames Tunnel

via drop shats and smaller

tunnels. Each drop shat needs a

construction site near the river.

The diculty is nding a suitable

location close to the river or the

drop shat construction site.

The urther away the drop shat

is rom the sewer, the longer the

new sewer connecting the old

sewer to the drop shat will need

to be, which means moredisruption to streets and houses.

Also, to build our tunnels, we

need dierent types o

construction sites. The main

tunnel drive shat sites are at the

start o a tunnel drive and are

where most o the tunneling

activity will take place. At these

sites, we will construct a shatand assemble the TBM at the

bottom o it. The TBM will then

be used to construct the tunnel

by boring through the ground

and then lining the hole with

precast segments. As these sites

are where the TBMs are launched

and received, they require much

larger construction sites, or

which there are very ew areasthat can be considered.

We plan to remove the material

excavated to create the main

tunnel at the three main drive

sites by river, unless there are

good reasons not to do so at a

particular site. We will also be

investigating the ways in which

we can incorporate sources orenewable energy into the

operational energy supply or

the project.


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In the UK

People living in other cities

around the UK, such as

Blackpool, Brighton and Cardi,

have already unded solutions to

CSOs through charges rom their

local water companies.

Cleaning up the Mersey in

Liverpool, which has a populationo 480,000, cost 170m, while

a similar scheme, estimated at

110m, is under way in Preston,

where the population totals

132,000.

Across Europeand beyond

Cities including Helsinki, Naples,

Stockholm and Vienna have

already implemented tunnel

solutions to tackle CSO discharges.

Major schemes involving tunnels

are also under way in other parts

o the continent to ensure clean

rivers and compliance with the

UWWTD.

Major storage and transport

tunnels are also the backbone o

solutions put in place to tackle

CSOs across North America, in

cities including Milwaukee,

Wisconsin; Portland, Oregon;

and Washington DC.

The scale and cost o the

solutions being implemented

in Paris and the Rhine-Ruhr

conurbation are comparable with

those o the Thames Tunnel

proposed or London.

Paris has a similar CSO problem

to London and is in the nal

stages o investing 3.4 billion on

additional storage and transercapacity, including large-scale

tunnels, to keep sewage out o

the River Seine.

Germany is investing

3.8 billion on a solution or the

Rhine-Ruhr area.

How othercities

are tacklingCSO discharges


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People living in other cities around the UK, such asBlackpool, Brighton and Cardiff, have already funded solutionsto CSOs through charges from their local water companies.


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Alternative

options considered


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Separating thesewerage system

Separate systems or rainwater and

oul sewage are now required or allnew developments.

Retrotting such systems across

densely developed London already

congested with inrastructure, both

above and below ground, would be

hugely expensive and impractical.

A sewer separation easibility study

looked at ve study areas and the

cost o building a separate storm or

oul sewer in each. The costs were

then extrapolated across the whole

London catchment. The study

calculated it would cost 40bn to

individually separate the local

sewerage collection system in each

catchment. The study thereore

concluded that, rather than try and

separate the sewerage system in

individual areas, it would be more

cost-eective to construct a whole

new local oul sewer network, rom

scratch, throughout London. This

was estimated to cost 13bn.

Separating the network would

require the construction o a new

sewerage system over 5000km

long; deep pipes would need to be

constructed in almost every street;

the drainage system o virtually

every property would need to bemodied; and new oul pumping

stations would need to be built to

compensate or low gradients.

Constructing a new separate

sewerage system would be three

times the cost o the tunnel and

would cause disruption to

nearly every street in London.

It would take ar longer than the

construction o the Thames Tunnel

and could not be completed within

any reasonable timescale.

Case study on separate systemsIn the Putney Bridge area, nine kilometres o oul sewer network

would need to be constructed under streets and roads at a cost o 27m. In

West Putney, 16km o sewer network would need to be constructed at a costo 34m. A total o our pumping stations would also need to be built in these

two areas to pump the oul sewage through the network. This work would

cause massive disruption.

Other options considered have been assessed

as costing more, being more disruptive and notachieving the required environmental standards.


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Sustainable urbandrainage systems(SUDS)

SUDS involve a variety o

measures to reduce the amount

o rainwater entering the

sewerage system, and to slowdown the rainwater that does

enter the sewerage system.

These include green roos (such

as grassed living roos) and

soakaways. They require a lot

o space and are generally both

costly and disruptive to retrot.

We ully support the use o

SUDS, as they can enhance theenvironment, can eectively

manage surace water fooding

and have a low carbon ootprint,

not to mention very low whole-

lie operating costs. However,

there are limitations to

sustainable drainage, particularly

in the Greater London area,

where the drainage systems are

complex, most o the land isalready developed and there is

huge potential or fooding.

There is not enough space

in London to retrot sucient

SUDS to control the CSO

discharges and meet

environmental objectives

within the required timescale.

London is also built mainly on

clay and saturated gravels so

that surace water will not soak

away quickly.

Retrotting SUDS in the densely

populated, urban environment

o London would have a

detrimental impact on virtually

every household, driveway,

road and open space in

every borough.

The maximum practicallevel o retrot SUDS wouldtake over 30 years to

implement and cost severaltimes as much as theThames Tunnel. The cost is

estimated to be at least13bn, and would not solvethe problem.

The implementation o SUDS innew developments is essential to

help stop the situation getting

worse. This will play an

important part in ensuring the

uture-proong o the Thames

Tunnel, by helping to reduce the

amount o surace water

entering the system. We are

thereore playing a ull part in

promoting the use o SUDSthrough the London Plan.

However, SUDS cannot resolve

the massive problem o CSO

discharges that already exists,

and certainly not in any realistic

timescale.

The TTSS concluded that,

because Londons catchments

are densely urbanised,

widespread retrotting o SUDS

techniques would be disruptive,

costly and technically dicult, as

insucient land is available.

As an example, in thesmall catchment area o

West Putney, retrotting

SUDS would:

impactonabout2,500

houses or roo drainage

require22hectares

the size o 44 ootball

pitches o open space

or detention basins

requireeighthectaresof

roadways, driveways and

parking areas (equivalent

to 11.5km o roadway) to

be reconstructed.

Pooled capacityRain storms across London historically do not have equal intensity,

creating varied amounts and volumes o surace water run-o. The

major advantage o the Thames Tunnel is the pooled capacity it will

provide. It will be able to take massive volumes o surace water

run-o rom all areas o London something SUDS could never do,

as they are only eective in the areas they are located.


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Doing nothing

is not an option

The current sewerage system is

ull to capacity, with simply

nowhere or excess fows to go,

apart rom into the River

Thames. As the population

increases and urther permeable

suraces are lost, CSO discharges

will continue to rise. It is no

exaggeration to say that, in the

uture, we are likely to see CSO

discharges during dry weather

and not just ater rainall.

Doing nothing will simply

result in:

more requent overfows

more requent

environmental damage

continued increased health

risks to recreational users

worse litter blight

an adverse impact on the

attractiveness o the

water rontage

the risk o heavy nes being

imposed on the UK.

The Thames Tunnel willprovide greater robustnessand fexibility or the uture

impacts o populationgrowth and changes inthe pattern o rainall.

The recommended ull-length

storage tunnel (Abbey Mills

route) achieves compliancewith the UWWTD and

environmental objectives. It is

the most cost-eective scheme,

involving the least disruption to

residents, businesses and

transportation when compared

to alternatives. It also has the

shortest implementation time,

which will acilitate Deras target

date or completion.

At the same time the Thames

Tunnel, which will last or at least

100 years, will ensure our sewerage

system is modernised and ready to

meet the needs o a growing

population and the demands o

uture generations.

Our generation has reaped the

benets o visionary 19th century

planning and construction by Sir

Joseph Bazalgette and his

contemporaries. The needs and

expectations o uture

generations o Londoners will

surely be no less than our own.

With the Thames Tunnel, we can

create our own legacy or them,

which will still be unctioning in

the 22nd century.


23/24

Weneedtobevisionaryandactnowforthebene

fitoffu

turegenerations.


24/24

For urther inormation see our website:

Summer 2010First round o public consultation

Early 2011Analysis o responses and tunnel

design amendments

Autumn 2011Second round o public consultation

Mid-2012Planning Submission

2013Start o construction

2020*Completion o the Thames Tunnel

*Subject to review

Date post:	07-Apr-2018
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