p2 blackfriars bridge sip
TRANSCRIPT
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Introd
uction
Introd
uction
Thames Tunnel
Blackfriars BridgeForeshore
Currently, untreated sewage regularly overows into the River Thames from Londons Victorian sewerage systemvia combined sewer overows (CSOs). The proposed Thames Tunnel would intercept these overows through theuse of a new storage and transfer tunnel, which would link west London and Abbey Mills Pumping Station. Thesewage ow would then be transferred to Beckton Sewage Treatment Works via the Lee Tunnel. The reduction
in untreated sewage entering the River Thames would bring long-term benets for the environment and users ofthe River Thames. In order to deliver the project we need a number of sites along the route and this documentidenties our current preferred sites at Blackfriars Bridge Foreshore.
Siteinformationpaper
1
Key facts
Local authority: City of London
CSO name: Fleet MainCSO spill volume in an average year: 520,000m (equivalent to approximately
208 Olympic swimming pools)
Site type: CSO site
Duration of main construction works: Approximately ve years.
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The location of the site is shown in Figure 1A. The site
extends into the River Thames, directly under and to thewest of Blackfriars Bridge. Part of the site extends north
onto the Victoria Embankment (A3211), along which the
Thames Path is located. To the north and across Victoria
Embankment (A3211) is a mix of offices and hotels. The
President ship is moored beyond Blackfriars Millennium
Pier to the west. The site is within the Whitefriars
Conservation Area.
The permanent site area would include the structuresassociated with the Blackfriars Millennium Pier, which
would be removed and permanently reinstated to the
east of the railway bridge on Pauls Walk, as illustrated on
Figure 1A.
This site information paper sets out our proposals at
Blackfriars Bridge Foreshore. We have also produced
project information papers, which cover overarching
topics relating to the project. Where we consider that aproject information paper is particularly relevant, we have
highlighted this in a related documents box. At the end
of this site information paper is a list of other documents,
which may be of interest and a glossary of terms.
We are proposing to reclaim an area of the River Thames,
adjacent to Blackfriars Bridge for this construction workand to accommodate permanent structures required
to operate the main tunnel. The site would be used to
intercept the existing local CSO, known as the Fleet Main
CSO, and connect to the northern Low Level Sewer No.1 to
divert flows to the main tunnel.
These works, along with our works at Victoria
Embankment Foreshore and Chelsea Embankment
Foreshore mean that we do not need additional sitesto intercept the following CSOs along the northern
embankment: Smith Street, Queen Street, Church Street,
Grosvenor Ditch, Kings Scholars Pond, Western Pumping
Station, Northumberland Street, Savoy Street, Norfolk
Street and Essex Street.
Section 1: Introduction and site information
Related documents:
Build
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Introduction
3
Figure 1A: Blackfriars Bridge Foreshore location plan
N
Low LevelSewer No.1
Fleet Main CSO
Inner TempleGarden
Temple Place
Blackfriars
Rail Bridge
BlackfriarsStation
Blackfriars
Bridge
Blackfriars
Millennium Pier
VictoriaEmbankment
SOUTHWARKLAMBETH
CITY OF LONDON
Local authority boundary
Draft limit of land to beacquired or used
Proposed tunnelroute centreline
Existing sewer
Existing CSO
Tem
ple
Avenue
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Blackfriars Bridge Foreshore
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How we chose this site
What we proposed at phase one consultationThrough our site selection process, we identified
Blackfriars Bridge Foreshore to intercept the Fleet Main
CSO and connect the northern Low Level Sewer No.1
to the main tunnel. At phase one consultation, which
was held between September 2010 and January 2011,
Blackfriars Bridge Foreshore was presented as our
preferred site. We assessed other sites but none made it
through to the shortlist stage of the site selection process.
What we are proposing at phase two consultationWe have considered the comments from phase one
consultation, feedback from ongoing engagement and
new information; and undertaken further technical work.
We still consider that Blackfriars Bridge Foreshore should
be our preferred site because Blackfriars Bridge Foreshoreis the only location where we can both intercept the Fleet
Main CSO and connect the northern Low Level Sewer No.1
to the main tunnel.
Related documents:
Q&A Consultation
Site selection
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Construction
Construction
5
Section 2: Construction
Construction activitiesConstruction activities are required to intercept the CSO
and connect the northern Low Level Sewer No.1 to the
main tunnel. We would construct an interception chamber
to intercept the CSO. A connection culvert would link the
interception chamber to a drop shaft (approximately
53m deep), through which flows would drop into the
main tunnel. We would also construct an overflow weir
chamber which would allow flows to be transferred from
the northern Low Level Sewer No.1 down the same
drop shaft.
Main tunnel
Drop shaft
Valve chamber
Existingoverfow to
River ThamesInterception
chamber
Existing overfow sewerExisting LowLevel Sewer No.1
Overfow weir chamber
Figure 2A: Illustration showing typical elements of below ground infrastructure
As the construction works would take place within the
foreshore of the River Thames, permanent structures
extending into the foreshore are required. Figure 2A
illustrates the below ground infrastructure proposed.
These activities would take place within the area
indicated by the red line in Figure 1A, in four main phases,
lasting approximately five years in total. The main
construction activities associated with these phases are
set out in Table 2.1.
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Advance works
Phase 1
Site setup
Figure reference Figure 2C Figure 2C
Typical working hours Varies Standard
Mainconstructionactivities
Utilities connected
Utilities diverted or protected
Pier relocated
Site cleared
Temporary works in the River Thames constructed
Site facilities and access set up
Drop shaft excavated and built
Above and below ground structures constructed
Mechanical and electrical equipment installed
Temporary works in the River Thames removed
Site restored and landscaped
Temporary site facilities removed
Table 2.1: Main activities during construction phases
Our typical working hours are expected to be:
Standard: 8am-6pm weekdays, 8am-1pm Saturday*
Extended standard: 6pm-10pm weekdays, 1pm-5pm Saturdays
Continuous: 24 hours a day, seven days a week**
Varies: Working hours for advanced works will depend on the nature of the works and will be
agreed with the local authority
* Standard working hours would also include, subject to agreement with the local authority:
a short period (up to one hour) before works start and after they have finished to allow our workers to prepare for work and check the site.
equipment and machinery maintenance could also take place 1pm-5pm Saturday and 10am-4pm Sunday.
** The main activities taking place 24 hours a day are below ground or within an enclosure.
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Construction
7
Phase 2
Drop shaft
construction
Phase 3
Construction of
other structures
Phase 4
Completion of works
and site restoration
Figure 2D Figure 2E
Standard with
occasional extended
standard
Standard Standard
Related documents:
Build
Managing construction
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Blackfriars Bridge Foreshore
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Site layout and construction phasesFigures 2C, 2D and 2E show how the site might be laid
out during the construction phases, which are set outin Table 2.1 and Figure 2B. These layouts have been
informed by the size of the infrastructure proposed,
the construction methods required and the location
of neighbouring buildings and structures. They have
also been developed to minimise effects on the local
community and environment. Particular factors at this site
that have influenced the layout are as follows:
Since our phase one consultation we have increasedthe drop shaft in size from approximately 20m to 24m
in internal diameter as a result of further physical
modelling of the shaft.
Part of the site would be constructed on piles to
minimise the effects on river ecology compared to other
construction options.
The layout of the site has been designed to reduce
effects on the navigation of the River Thames.
The connection to the northern Low Level Sewer No.1
has moved to beneath the existing Blackfriars Bridge
ramp to minimise the effects on existing utilities
running within the Victoria Embankment (A3211).
P1 P3
P2 P4
Year 1 Year 2 Year 3 Year 4 Year 5
Advance
works
The site layouts are indicative only, and the contractor
may arrange the site in a different way, depending onthe chosen construction methods, provided that any
environmental effects are appropriately managed, and
that the main construction activities are undertake within
the red line shown in Figure 1A.
Figure 2B: Construction timeline showing approximate duration of works in phases (P)
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Construction
9
Jack up bargeservicing pilingoperations
Working area for pierrelocation (advance
works only)
NSOUTHWARK
CITY OF LONDON
LAMBETH
Diversion rejoins
Thames Path atTemple Place
Possible locationof President duringconstruction
Existing mooringfor President
Barge
Figure 2C: Illustrative advance works and phase 1 construction plan
Maximum extent ofconstruction site foradvance works and phase 1
Site hoarding/traffic barrier
Cofferdam
Local authority boundary
Site support/welfare
Traffic lane coned off for site access
Site access
Existing Thames Path
Thames Path diversion
BlackfriarsBridge
BlackfriarsRail Bridge
BlackfriarsStationVictoria Embankment
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Figure 2D: Illustrative phase 2 construction plan
Option for contractorto transport materialsusing barges
Piling rig Cranes
Drop shaft
N
Maximum extent ofconstruction site for phase 2
Site hoarding/traffic barrier
Cofferdam
Local authority boundary
Site support/welfare
Excavated materialstorage and processing
Maintenance workshopand storage
Construction support
Internal site road
SOUTHWARK
CITY OF LONDON
LAMBETH
Diversion rejoins
Thames Path atTemple Place
Possible locationof President duringconstruction
Traffic lane coned offfor site access
Site access
Existing Thames Path
Thames Path diversion
BlackfriarsStation
BlackfriarsBridge
BlackfriarsRail Bridge
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Construction
11
Figure 2E: Illustrative phase 3 construction plan
Option for contractorto transport materialsusing barges
Cranes
CraneDrop shaft
N
Maximum extent ofconstruction site for phase 3
Site hoarding/traffic barrier
Cofferdam
Local authority boundary
Site support/welfare
Maintenance workshop and storage
Internal site road
Site access
Existing Thames Path
Thames Path diversion
CITY OF LONDON
SOUTHWARKLAMBETH
Possible locationof President duringconstruction
BlackfriarsStation
BlackfriarsBridge
BlackfriarsRail Bridge
Diversion rejoins
Thames Path atTemple Place
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Additional works and activitiesThe main construction activities at this site are set out in
Table 2.1. We would also need to undertake additionalworks and activities, some of which may be located
outside of the area indicated by the red line in Figure 1A.
The anticipated additional works and activities are set
out in Table 2.2.
When Type of works What we would do
Required for
construction
phase
Installation of equipment to monitorenvironmental matters such as noise,
vibration and dust.
The locations of monitoring equipment would be agreedwith the local authority and relevant landowners.
Protection works to third party structures
(such as buildings, bridges and tunnels).
We would undertake studies to identify any effects our
construction work may have on third party structures.
The studies may recommend particular construction
methods or, in very limited instances, protection works.
If protection works are required to the existing sewer,
we would access the sewer network through existingmanholes.
Temporary connection to utilities (such as
water, sewer, phone and electricity supply).
We expect to connect to utilities in Victoria
Embankment (A3211).
Traffic management works.
These would need to extend beyond our site and could
include relocating kerb lines, repainting road lines and
modifying traffic signals.
Dredging.
There is a possibility that as the detailed design isdeveloped we may need to undertake dredging to allow
barges to get to and from our site and for the relocated
Millennium Pier.
Protection of the river.We may need to carry out works to strengthen the river
bed to avoid scour.
Required for
operational
phase
Permanent connection to utilities (such as
water, phone and electricity supply) for the
operational tunnel.
We expect to connect to utilities in Victoria
Embankment (A3211).
Table 2.2: Additional works and activities
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Construction
13
Construction transport and accessWe propose to use barges to bring in and take away the
material used to fill the cofferdam. Each barge wouldremove approximately 55 lorries from the road. Using
barges at this site would reduce the number of lorry visits
to/from this site by approximately 45% (saving 14,500
lorry visits over the construction period of approximately
five years). Table 2.3 sets out the anticipated average
daily number of lorries and barges visiting (ie travelling to
and from) the site during the peak months of each phase,
based on moving cofferdam fill material by barge.
During phases 1 and 2 of construction, construction
traffic would access the site travelling across Blackfriars
Bridge and turning left into the site through a new
entrance from the westbound ramp leading down from
Blackfriars Bridge. Traffic leaving the site would turn left
from a second new entrance then merge onto Victoria
Embankment (A3211) and continue westbound.
During construction phase 3, the westbound ramp fromBlackfriars Bridge would be closed. Construction traffic
would access the site by turning left from the Blackfriars
underpass, and would leave the site by the same route
as for the other construction phases. Beyond this,
construction traffic would use the major road network to
get to and from its final destination. Site access points
are shown on Figures 2C, 2D and 2E.
During construction phase 3, general traffic that would
normally use the westbound ramp from Blackfriars Bridgewould be diverted as shown in Figure 2F.
We would need to suspend some coach parking bays on
the westbound ramp from Blackfriars Bridge and some
loading bays on Victoria Embankment (A3211) during
construction.
The Thames Path runs through our construction site. We
would create a temporary diversion for the duration of
our works, as shown in Figures 2C, 2D and 2E. Based on
our current design we do not anticipate that any other
footpath or bus stop relocations would be required.
Phase 1Site setup
Phase 2Drop shaft
construction
Phase 3Construction ofother structures
Phase 4Completion ofworks and site
restoration
Average daily lorry visits 21 lorries 35 lorries 29 lorries 6 lorries
Average daily barge visits 2 barges none none 3 barges
Table 2.3: Average daily lorry and barge visits during the peak months
Related documents:
Transport
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Figure 2F: Proposed diversion for westbound ramp from Blackfriars Bridge
SOUTHWARKLAMBETH
CITY OF LONDONWESTMINSTER
N
Diversion route
Local authority
boundary
WestminsterBridge
WaterlooBridge
BlackfriarsBridge
BlackfriarsRail Bridge London
BridgeMillenium
Bridge
Golden JubileeFootbridges
Hungerford
Bridge
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Construction
15
Related documents:
Environment
Managing construction
Transport
Management of construction worksOur construction works would be managed in accordance
with an agreed Code of construction practice (CoCP).For phase two consultation, we have produced a draft
CoCP Part A: General requirements, informed by CoCPsfrom other major construction projects in London and
consultation with the local authorities. Through the
environmental impact assessment process, scheme-
wide principles to address potential effects on the local
environment have been identified and integrated into
the design. The CoCP Part A sets out scheme-wide control
measures that would be used to minimise potentialeffects during the construction process.
Table 2.4 sets out what we consider to be the key issues
for this site during construction, and how we are currently
proposing to address them.
Bl kf i B id F h
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Table 2.4: Key issues relating to construction
Issue Our response
Construction activities would
require the temporary relocation
of the President ship and
the permanent relocation of
Blackfriars Millennium Pier.
The President ship would be temporarily moved west to the formerChrysanthemum Pier moorings. Blackfriars Millennium Pier would be relocated to
the east of Blackfriars Bridge.
Possible effect of construction
vehicles on the volume of traffic
on Victoria Embankment (A3211).
We have sought to minimise disruption to the local road network through our
site layout, design and phasing of our construction works. We would manage
the effects of road transport through our traffic management plans, which will
seek to limit the number of vehicle movements and hours of operation, identify
the most suitable site access points and any necessary highway management
arrangements. As already set out, we also propose to use barges to bring in and
take away the material used to fill the cofferdam, which would reduce the number
of lorry movements from this site by approximately 45% over the construction
period.
Temporary diversion of the
Thames Path.
The Thames Path would be temporarily diverted via a safe alternative route along
the northern footpath to Victoria Embankment (A3211), and back to the Thames
Path via steps and a temporary lift to the east of Blackfriars Bridge.
Possible effect of foreshore
construction activities on river
navigation and river users.
We have undertaken modelling to test the effect that the structure has on the flow
of the river. The modelling has shown the proposed structure to be satisfactory
and the Port of London Authority and other key stakeholders are satisfied the
permanent works have a minimum effect on river navigation. A full navigational
risk assessment will be undertaken for the temporary and permanent works.
Possible effect of noise and
vibration from construction
activities on neighbouring areas.
The contractor would be required to implement noise and vibration control
measures at the worksite, which will be set out in the CoCP.
Possible effects on local air
quality and dust nuisance in
neighbouring areas.
Preliminary findings indicate that while there is the potential for dust nuisance
effects, there are unlikely to be any significant local air quality effects at any of
the sites. The contractor would put in place air and dust control measures at the
worksite, which will be set out in the CoCP.
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Future
use
Future use
17
Section 3: Future use
This section describes the site after the completion of the
construction work, ie when the main tunnel is in use the
operational phase.
Design
Since our phase one consultation we have progressed
the design for the permanent use and appearance of
the structures at Blackfriars Bridge Foreshore. The design
of the permanent proposals follows our scheme-wideprinciples and takes into account comments made and
ongoing engagement with the City of London and other
technical consultees.
Our permanent works which are formed within a structure
extending into the foreshore of the River Thames need to
incorporate functional elements, which are required for
the operation of the tunnel. These include:
Underground structures with ground level access covers
including: a CSO drop shaft with an internal diameter
of approximately 24m, connection culverts, interception
chamber, valve chamber, passive filter chamber and an
overflow weir chamber to divert flow from the northern
Low Level Sewer No.1.
Five main ventilation columns up to 6m high.
A small diameter ventilation column to the interception
chamber up to 6m high.
Maintenance vehicle access.
Electrical and control kiosks.
Table 3.1 sets out the site specific issues that haveinfluenced our permanent design proposals and how we
have addressed them in our proposed design.
Blackfriars Bridge Foreshore
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Issue Our response
Effect on the historic setting of
the site including views alongthe River Thames towards St
Pauls Cathedral.
The form of the proposed structure in the foreshore of the River Thames is
contemporary and seeks to resolve the level differences created by the Thames Path
and the Blackfriars Bridge approach ramp.
The structure is designed to allow unhindered views of the listed buildings located
along Victoria Embankment (A3211) and views towards St Pauls Cathedral. In
addition, new views of the River Thames would be offered from the viewing platforms
created on the new structure.
The proposed materials would complement those of the Embankment and the listed
buildings located close to the site while making it clear that we have created a newextension into the River Thames.
The historic line of trees (London Planes) along the Embankment would be extended
onto the new structure to help create areas of shade.
As a result in the change to the ventilation strategy we no longer need a large
ventilation building on the site as was indicated at phase one consultation.
Ventilation of the tunnel is still required, and in this location we have designed a
series of five smaller columns that form a feature on the proposed landscape whilstmeeting our operational requirements to manage the air in the main tunnel.
Effects on river navigation and
hydraulics.
Preliminary modelling has indicated that the proposed design is acceptable in terms
of river flow. The proposals have been discussed with the Port of London Authority
and other key stakeholders to develop a layout that has a minimal effect on river
navigation.
Effect on the Thames Path.
The Thames Path would be restored after our works are complete and would be
central to the proposed new landscaped public area, where people can stop to enjoy
the River Thames.
The proposals would enhance the Thames Path which is currently characterised by a
number of narrow ramps and stairs in this location.
Our design allows a flat and fairly direct pedestrian route from the western access
point on Victoria Embankment (A3211) to the eastern access on Pauls Walk beneath
the road bridge, while offering opportunities to step to the side and ascend ramps or
stairs to rest, enjoy the views or walk up to Blackfriars Bridge or Blackfriars Station.
Future use
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Future use
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Issue Our response
Effect on river based business
and passenger services from
Blackfriars Millennium Pier.
It is proposed to permanently relocate Blackfriars Millennium Pier to the east of theBlackfriars Railway Bridge.
The shape of the structure to intercept the Fleet CSO has been designed to ensure
that it does not impede the navigational channel of the River Thames in this
location.
Following completion of the works the President ship would be restored from its
temporary location during the construction works to its current mooring to the west
of the new structure.
An alternative location onshore would be found for Crown River Cruises, who are
currently located on Blackfriars Millennium Pier.
Loss of foreshore habitat andeffects on ecology.
Our proposals for the permanent layout and design of the site have sought to reduce
the extent of the permanent works within the river to minimise effects on water
ecology as far as possible.
Ecological surveys of the River Thames are being undertaken to identify possibleeffects, and design measures would be incorporated where required.
Construction of the tunnel would also deliver river wide improvements to local water
quality, which would result in positive effects on river ecology, including habitat
improvements and reduced fish kills.
Table 3.1: Site specific elements and issues that have influenced our permanent design
Blackfriars Bridge Foreshore
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Figure 3A: Photo of the site before the works
Figures 3A, 3B, 3C and 3D show the current site and
provide illustrations of our design proposals. Further
information on the development of our design can be
found in the Design development report.
Related documents:
Design
Future use
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Future use
21
Figure 3B: Artists impression of the site after the works are completed
Blackfriars Bridge Foreshore
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Figure 3C: Aerial view of the completed works
Future use
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Figure 3D: Layout of site once construction works complete
President reinstatedin current positionat the end of
construction period
Ventilationcolumns
Provision
for smallretail kiosk
Access for
maintenancevehicles
Stepped platformand seating area
Level Thames Path
over new foreshorestructure
Raised viewingplatform
VictoriaEmbankment
BlackfriarsBridge
Ramp providesstep free access toviewing platform
New water featurein paving surfacein the shape of the
River Thames
Widened
pedestrian routeunder bridge
Stairs from
BlackfriarsBridge reinstated
Foreshore structureto extend underbridge deck
N
Electrical and control kioskunder vehicle ramp fromBlackfriars Bridge
New entrance topublic WCs and privatesporting facility
New FleetCSO outlet
Refer to detail below
Millennium pierpermanently relocated
Blackfriars Bridge Foreshore
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Blackfriars Bridge Foreshore
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Operation and maintenanceOnce the tunnel is operational, we would need access
to the site occasionally for inspection and maintenance
purposes. We expect to visit the site approximately
once every three to six months to carry out inspections
and maintenance of the ventilation and below ground
equipment. This is likely to involve a visit by staff in a
small van, and may take several hours.
Once every ten years, we expect to carry out a major
internal inspection of the tunnel and underground. This is
likely to involve a small team of inspection staff, a small
team of support crew and two mobile cranes to lower
the team and inspection vehicle into the shaft. This is
likely to take several weeks, and would require temporary
fencing around the shaft for safety and security while the
inspection takes place.
We may also need to make visits to the site for unplanned
maintenance or repairs, for example, if there is a blockage
or equipment failure. This may require the use of mobile
cranes and vans.
Permanent vehicular access would be from Victoria
Embankment (A3211).
Management of operational effectsWe have undertaken technical work, including stakeholder
engagement, to assess and identify the key issues
associated with this site once it is operational. Table
3.2 summarises these issues and how we are currently
proposing to address them.
Future use
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Issue Our response
Possible odour effects during the
operation of the tunnel.
Odour effects at this site are expected to be negligible because we have developedanAir management plan to minimise possible odour and air quality effects arisingfrom the operation of the tunnel. The technology we are proposing to use at
this site includes the use of passive below ground carbon filters that will remove
possible odour before air leaves the ventilation equipment.
Disturbance from future
maintenance access.
Permanent access would be required for maintenance and servicing purposes to
the shaft and ventilation equipment. Any planned maintenance visits would be
undertaken during normal working hours and all visits managed to avoid disruption
to local residents, businesses and users of affected public areas as far as possible.
Table 3.2: Key issues relating to site operation
Related documents:
Odour
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Phase two public consultation material
Icon Title Details
OverflowSets out how Londons sewerage system works and why the capital has an overflow
problem.
Route and
tunnel
alignment
Sets out the preferred route of the main tunnel and the reasons for our preference.
Site selection Sets out the process we followed to find and select our preferred sites.
Transport Contains information on the different transport options we have considered fordelivering and removing materials from our sites.
Further information
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Technical reports
Theme Icon Title Details
Phase one
consultation1
SUMMARY
Report on phase one
consultation:
summary report
Provides a summary of the comments made at phase one
consultation and our responses.
Phase two
construction
information
Code of construction
practice Part A:
General requirements
(CoCP)
Sets out control measures to be adopted during the project
construction period.
Phase two
environmental
information
Air management
plan
Outlines the methods which we will use to manage odour
from the main tunnel at all our preferred sites.
Preliminary
environmental
information report
(PEIR)
Contains initial assessments on the environmental effects of
the Thames Tunnel project based on information collected
to date. Please refer to volume 21 of the non-technical
summary and volume 21 of the PEIR for more informationon this site.
Phase two scheme
development
Design development
report
Provides a general overview of how the scheme design at
each site has evolved to date. Please refer to chapter 18 for
more information on this site.
2Phase two schemedevelopment report
Provides an overview of the development of the Thames
Tunnel project and how each site was chosen. Please refer toAppendix Q for more information on this site.
Site glossary
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Term Definition
Carbon filters Filters that remove odours before the air is released from the tunnel.
CofferdamA wall that is constructed within the river around the outside of the working area and then
pumped dry. The inside of the cofferdam can then be filled to create a safe working area.
Combined sewer A single sewer system that takes both rainwater and domestic and industrial wastewater.
Combined sewer
overflow (CSO)
A structure, or series of structures, that allows sewers to overflow into the river when they
are full as a result of increased rainfall. Without the overflows, the sewers would back up
and cause flooding in streets or houses.
Connection tunnel A tunnel connecting a drop shaft to the main tunnel.
Conservation areaAn area designated by the local authority or English Heritage as having special
architectural or historical interest.
Draft limit of land to be
acquired or used
The extent of land that we may need to use or acquire, or over which rights may be needed
to carry out works that are essential to the project.
Drop shaft
A vertical circular concrete structure, used to drop flows from the high level of the CSO to
the low level of the main tunnel. It would also be used to provide access to construct the
connection tunnels.
Foreshore Ground uncovered by the river when the tide is low.
Interception chamberA structure, built on an existing combined sewer, which diverts stormwater overflow into the
main tunnel.
Main tunnel The tunnel from Acton Storm Tanks to Abbey Mills Pumping Station.
Operational phase After the completion of the construction work, when the main tunnel is in use.
Scour Movement of the riverbed materials due to the force of the water.
Thames Tunnel project
The Thames Tunnel project comprises a storage and transfer tunnel, from west London to
Beckton Sewage Treatment Works in east London, and the control of 34 CSOs along the
Thames Tideway.
Transport for London
Road Network (TLRN)
The network of roads managed by Transport for London. These are the major or strategic
roads, which have high capacity.
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