P2 Chelsea Embankment SIP

8/3/2019 P2 Chelsea Embankment SIP

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Introd

uction

Introd

uction

Chelsea Embankment

Foreshore

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 Chelsea Embankment Foreshore.

Thames Tunnel

Siteinformationpaper

1

Key facts

Local authority: Royal Borough of Kensington and Chelsea

CSO name: RanelaghCSO spill volume in an average year: 280,000m (equivalent to approximately

112 Olympic swimming pools)

Site type: CSO site

Duration of main construction works: Approximately four years.


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Chelsea Embankment Foreshore

2

We are proposing to use the foreshore of the River

Thames, opposite the Bull Ring Gates of the RoyalHospital Chelsea, a section of Chelsea Embankment

(A3212) and part of the grounds of the Royal

Hospital Chelsea for this construction work and to

accommodate permanent structures required to

operate the main tunnel.

The sites would be used to intercept the existing local

CSO, known as the Ranelagh CSO and to construct a

connection to the northern Low Level Sewer No.1 todivert flows to the main tunnel.

These works, along with our works at Blackfriars Bridge

Foreshore and Victoria Embankment Foreshore mean

that we do not need additional sites to 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 Streetand Essex Street.

The two construction sites required for the works at

Chelsea Embankment Foreshore are shown in Figure1A. The main site is located in the foreshore of the River

Thames, with part of the site extending north onto the

Chelsea Embankment (A3212), along which the Thames

Path is located and the south eastern part of the

grounds of the Royal Hospital Chelsea. The site is also

within the Thames Conservation Area. To the east of the

main site is Chelsea Bridge. Ranelagh Gardens and the

Royal Hospital Chelsea, (together a Grade II registered

park and garden), lie to the north of the main site,

separated from it by Chelsea Embankment (A3212).

The smaller site, which is required to connect the

northern Low Level Sewer No.1 to the main tunnel, is

located within the eastbound carriageway and footpath

of the Chelsea Embankment (A3212) and the southern

part of Ranelagh Gardens.

This site information paper sets out our proposals atChelsea Embankment Foreshore. We have also produced

project information papers, which cover overarching

topics relating to the project. Where we consider that

a project 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.

Section 1: Introduction and site information

Related documents:

Build


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Introduction

3

Figure 1A: Chelsea Embankment Foreshore location plan

ChelseaBridge

Low LevelSewer No.1

Royal Hospital Chelsea(South Grounds)

Ranelagh CSO

RanelaghGardens

Chelsea

Embankm

ent

Che

lseaBridgeRoad

GrosvenorBridge

N

KENSINGTON &CHELSEA

CITY OFWESTMINSTER

WANDSWORTH

Local authority boundary

Draft limit of land to beacquired or used

Proposed tunnelroute centreline

Existing sewer

Existing CSO

Tite Street


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4

How we chose this site

What we proposed at phase one consultationAt phase on consultation, which was held between

September 2010 and January 2011, we presented

Chelsea Embankment Foreshore (west of Chelsea Bridge)

as our preferred site to intercept the Ranelagh CSO and to

connect the northern Low Level Sewer No.1 to the main

tunnel. Due to the constrained nature of the area, no

other suitable sites were identified.

Why we have amended our proposals

Since January 2011 we have considered the comments

from phase one consultation, feedback from ongoing

engagement and new information; and undertaken

further technical work. This has resulted in us re-assessing

potential sites to intercept the Ranelagh CSO and to

connect the northern Low Level Sewer No.1 to the

main tunnel.

Our findings have confirmed that the best location to

connect to the northern Low Level Sewer No.1 to the main

tunnel is within the existing eastbound carriageway of

Chelsea Embankment (A3212).

Engagement with Crossrail has revealed that a smaller

site located within the safeguarded zone for Crossrail 2

would be acceptable. Therefore, Chelsea Embankment

Foreshore (opposite to Bull Ring Gate) is a possible site.

Discussions have also been held with English Heritage,

who raised issues about the effect of the permanent

structures on views of the river wall along the River

Thames. As a result we have re-assessed sites inland and

concluded that Ranelagh Gardens could potentially meet

our requirements.

What we are proposing at phase two consultationWe have identified three shortlisted sites to intercept the

CSO, as shown on Figure 1B. The sites are:


(west of Chelsea Bridge) (site 1)

Ranelagh Gardens (site 2)


(opposite to Bull Ring Gate) (our preferred site).


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Introduction

5

Figure 1B: Preferred and shortlisted sites

CITY OFWESTMINSTER

KENSINGTON &CHELSEA

WANDSWORTH

Chelsea

Embankmen

t

ChelseaBridgeRoadRanelagh

GardensRoyal Hospital

Chelsea(South Grounds)

Site 1

Site 2

N

Preferred site Chelsea Embankment

Foreshore (oppositeBull Ring Gate)

Other shortlistedsite locations

Local authorityboundary


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6

Chelsea Embankment Foreshore (opposite to Bull RingGate) is our preferred site to intercept the RanelaghCSO. The site would have less effect on the foreshore of

the River Thames because it is only necessary to buildone structure. There is also likely to be less effect on local

residential areas. The location of the site also offers the

opportunity to create a new area of public space that

complements the setting of the historic environment and

views along the River Thames.

The northern Low Level Sewer No.1 connection would be

constructed within the existing eastbound carriageway of

Chelsea Embankment (A3212). These works would be inthe same location for each of the shortlisted sites.

Site 1 Chelsea Embankment Foreshore (west ofChelsea Bridge) is a shortlisted site. We consider thissite to be less suitable than our preferred site because it

requires two structures to be built within the foreshore of

the River Thames to accommodate the drop shaft and

interception chamber. This would require a larger working

area, and the permanent structures would have a greatereffect on the historic environment, foreshore and views

along the River Thames.

Site 2 Ranelagh Gardens is a shortlisted site that isconsidered to be less suitable than our preferred site

because it is closer to the Lister Hospital and residential

areas; it would result in a loss of open space, disrupt

visitors to Ranelagh Gardens and would potentially affect

events such as the Chelsea Flower Show. Whilst thepermanent works would be less visible within the Gardens

than in our preferred foreshore site, we do not consider

that this benefit outweighs the issues set out above.

Related documents:

Q&A Consultation

Site selection


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Construction

Construction

7

Section 2: Construction

Construction activitiesConstruction activities are required to intercept the CSOand to link 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

45m deep) through which flows would pass down to a

short connection tunnel. This would then join to the main

tunnel. We would also construct an overflow weir chamber

which would allow flows to be transferred from thenorthern Low Level Sewer No.1 down the same drop shaft

and short connection tunnel to the main tunnel. Figure

2A illustrates the below ground infrastructure proposed.

As the construction works would take place within the

foreshore of the River Thames, a permanent structure

extending into the foreshore is required. These activities

would take place within the area indicated by the red line

in Figure 1A, in five main phases, lasting approximately

four years in total. The main construction activities

associated with these phases are set out in Table 2.1.

Main tunnel

Drop shaft

Shortconnection

tunnel

Valve chamber

Existingoverfowto

River Thames

Interceptionchamber

Existingoverfowsewer

Existing Low LevelSewer No.1

Overfowweirchamber

Figure 2A: Illustration showing typical elements of below ground infrastructure


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Advance works

Phase 1

Site setup

Figure reference Figure 2C

Typical working hours Varies Standard

Mainconstructionactivities

Utilities connected

Utilities diverted or protected

Site cleared

Temporary works in the River Thames constructed

Site facilities and access set up

Drop shaft excavated and built

Short connection tunnel 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

9

Phase 2

Drop shaft

construction

Phase 3

Tunnelling

Phase 4

Construction of

other structures

Phase 5

Completion of

works and siterestoration

Figure 2D Figure 2D Figure 2E

Standard Continuous Standard Standard

Related documents:

Build

Managing construction


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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 phase one consultation, the number of structuresin the River Thames at this location has been reduced

from two to one. This has been achieved because we

can now intercept the Ranelagh CSO directly following

further discussions with the Crossrail 2 project team

regarding their safeguarded area. This reduces the

potential effects on river ecology, river flows and river

navigation.

The proposed construction access arrangements

maintain two-way traffic along Chelsea Embankment(A3212) by reducing road lane widths. This minimises

the effects on traffic congestion.

The access route to the site has been selected to

minimise tree loss by using an existing gap in the line

of trees for one of the accesses. This minimises the

potential effects on local ecology and landscape.

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 undertaken

within the red line shown in Figure 1A.

Figure 2B: Construction timeline showing approximate duration ofworks in phases (P)

P1

P2

P3

P4

P5

Year 1 Year 2 Year 3 Year 4

Advance

works


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Construction

11

Figure 2C: Illustrative phase 1 construction plan

Barge

Two-way

traffic flow

Two-waytraffic flow

Jack up barge servicingpiling operations

Diversion rejoinsThames Path atpedestrian crossingat Tite Street

KENSINGTON &CHELSEA

WANDSWORTH

Maximum extent ofconstruction sites for phase 1

Site hoarding/traffic barrier

Cofferdam


Traffic lane coned off forsite access

Site access

Existing Thames Path

Thames Path diversion N


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12

Figure 2D: Illustrative phases 2 and 3 construction plan

Option for contractorto transport materialsusing barges

Cranes

Drop shaft

N

Maximum extent ofconstruction site for phases2 and 3


Cofferdam


Site support/welfare

Excavated material storageand processing

Maintenance workshopand storage

Construction support

Internal site road


Site access


Thames Path diversion

Diversion rejoins ThamesPath at pedestriancrossing at Tite Street

Two-waytraffic flow

KENSINGTON &CHELSEA

WANDSWORTH


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Construction

13

Figure 2E: Illustrative phase 4 construction plan

Option for contractorto transport materialsusing barges

Cranes

Crane

Drop shaft

Piling rig

N

Diversion rejoinsThames Path at

pedestrian crossingat Tite Street

Maximum extent ofconstruction sites for phase 4


Cofferdam


Site support/welfare

Excavated materialstorage and processing

Maintenance workshopand storage


Site access


Thames Path diversion

Two-waytraffic flow

Two-waytraffic flow

KENSINGTON &CHELSEA

WANDSWORTH


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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 monitor

environmental matters

such as noise, vibration

and dust.

The locations of monitoring equipment would be agreed with 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 existing manholes.

Diversion of utilities.

The works to connect to the northern Low Level Sewer No.1 would require

the diversion of a gas main, electricity and telecoms cables from Chelsea

Embankment (A3212) into the edge of Ranelagh Gardens. These diversion

works would require the dismantling of a section of the Ranelagh Gardens

boundary wall/fence. The diversions would have to be carried out ahead ofthe main works, and would require lane closures and traffic management

along Chelsea Embankment (A3212). The wall/fence and associated

planting would be reinstated on completion of construction works.


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Construction

15

Table 2.2: Additional works and activities

When Type of works What we would do

Required for

construction

phase

Temporary connection

to utilities (such as

water, sewer, phone

and electricity supply).

We expect to connect to utilities in Chelsea Embankment (A3212) or

Chelsea Bridge Road (A3216).

Traffic management

works.

These may 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 is developed we may needto undertake dredging to allow barges to get to and from our site.

Protection of river bed. 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 Chelsea Embankment (A3212) or

Chelsea Bridge Road (A3216).

Ch l E b k t F h


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Construction transport and accessWe propose to use barges to bring in and take away

material used to fill the cofferdam. It is not generally

practical and cost effective to transport all materials

to and from the site by barge so we would still need to

transport some materials by road. We would however

give the contractor the flexibility to determine the most

practical and cost-effective means of transporting other

materials and equipment.

Each barge would remove 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 7,000 lorry visits over the construction period

of approximately four years).

Phase 1

Site setup

Phase 2

Drop shaftconstruction

Phase 3

Tunnelling

Phase 4

Constructionof other

structures

Phase 5

Completion ofworks and site

restoration

Average dailylorry visits

16 lorries 17 lorries 7 lorries 33 lorries 12 lorries

Average daily

barge visits2 barges none none none 2 barges

Table 2.3: Average daily lorry and barge visits during the peak months

Related documents:

Transport

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.


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Construction

17

Construction traffic would access the site by travelling

west along Chelsea Embankment (A3212) and turning

left into the site through a new entrance. The site access

points are shown on Figures 2C, 2D, and 2E. Traffic

leaving the site would turn left from the new entrance

onto Chelsea Embankment (A3212) and continue

westbound. Beyond this, construction traffic would use

the major road network to get to and from its final

destination.

During phases 1, 2 and 3 of the construction we would

need to close part of the westbound carriageway of

Chelsea Embankment (A3212) to establish the main

shaft construction site and during phases 1 and 4

we would also need to close part of the eastbound

carriageway of Chelsea Embankment (A3212) to

undertake utility diversions (phase 1) and construct the

interception chamber (phase 4). We would in each case

reduce the width of the traffic lanes so that one lane

in each direction would remain open. The Thames Pathruns through our construction site; we would create a

temporary signposted diversion for the duration of our

works by using existing pedestrian crossings as indicated

on Figures 2C, 2D and 2E. Based on our current design we

do not anticipate that any bus stop relocations, parking

bay suspensions or junction changes would be required.

Ch l E b k t F h


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Issue Our response

Potential loss of and damage to trees

along Chelsea Embankment (A3212) to

facilitate site access and construction.

Since phase one consultation, the construction site access has been moved

further west. This minimises tree loss by using an existing gap in the line of

trees for one of the accesses. Potential damage to trees during construction

would be further minimised through careful root protection, pollarding and

trimming methods.

Possible effect of construction vehicles

on the volume of traffic on Chelsea

Embankment (A3212) and ChelseaBridge Road (A3216), particularly when

they coincide with events such as the

Chelsea Flower Show. During phases 1

and 4 of construction, we would need to

close part of the eastbound carriageway

of Chelsea Embankment (A3212).

We have sought to minimise disruption to the local road network through

our site layout and design. During construction phases 1 and 4, two-way

traffic along Chelsea Embankment (A3212) would be maintained by

reducing the width of the traffic lanes.

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 including

during Chelsea Flower show and other events.

Temporary diversion of the Thames Pathand cycleway.

The Thames Path would be temporarily diverted a short distance via a safe

alternative route along the side of Chelsea Embankment (A3212). Existingpedestrian crossings would be used.

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.

Construction


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Construction

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Table 2.4: Key issues relating to construction

Issue Our response

Possible effect of noise and vibration 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. Continuous

tunnelling would only be undertaken for a short period of time to construct

a connection tunnel from the drop shaft to the main tunnel.

The effects of air pollution and dust 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.

Possible effects of construction activities

on local wildlife, including Ranelagh

Gardens, foreshore habitat and river

wildlife.

Since phase one consultation, we have reduced the size of the cofferdam

structure to limit encroachment into the River Thames and effects on

Ranelagh Gardens. Ecological surveys are also being undertaken to identify

possible effects arising from construction activities. The contractor would

put in place various control measures at the worksite to minimise these

effects as far as possible. These will be set out in the CoCP.



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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.

DesignSince our phase one consultation we have progressed

the design for the permanent use and appearance of

the structures at Chelsea Embankment Foreshore. The

design of the permanent proposals follows our scheme-wide principles and takes into account comments made

and ongoing engagement with the Royal Borough of

Kensington and Chelsea 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 12m, connection tunnel to the main

tunnel, connection culvert, interception chamber, valve

chamber, passive filter chamber and an overflow weir

chamber to divert flow from the northern Low Level

Sewer No.1 under Chelsea Embankment (A3212).

Two main ventilation columns up to 6m high.

Two small diameter ventilation columns to theinterception chamber up to 6m high.

Maintenance vehicle access.

Two electrical and control kiosks.

Table 3.1 sets out the site specific issues that have

influenced our permanent design proposals and how we

have addressed them in our proposed design.

Issue Our response

Loss of foreshore

habitat and effects on

ecology within the River

Thames.

The footprint of the structures we are placing in the River Thames is determined by their

functional requirements. The drop shaft has reduced in diameter since our phase one

consultation as a result of more detailed design.

Our proposals for the permanent layout and design of the site have sought to reduce the

extent of the permanent works within the foreshore of the River Thames to minimise effectson water ecology as far as possible.

Ecological surveys of the River Thames and foreshore are being undertaken to identify

possible effects, 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.

Future use


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Future

use

Future use

21

Table 3.1: Site specific issues that have influenced our permanent design

Issue Our response

Effect on the setting of

Ranelagh Gardens.

A suitable landscape design is being developed to restore the site following completion of

the works and reflect the setting of the Embankment and Ranelagh Gardens.

The design also includes new trees on the Embankment to replace trees lost during

construction. These would be located to allow views through the south grounds to the Royal

Hospital Chelsea.

Effects on the setting

of the Grade I listed

Royal Hospital Chelsea,

Grade II listed Chelsea

Bridge and Thames

Conservation Area and

historic views along the

River Thames.

At phase one consultation, our design showed an interception chamber located opposite the

Bull Ring Gates to the Royal Hospital Chelsea which was connected by a connection culvert

to a drop shaft located close to Chelsea Bridge. The design has been amended to provide a

single structure in the River Thames located in front of the Bull Ring Gates.

Our permanent design proposals take into account historic views along the River Thames,

including the setting of the Grade I listed Royal Hospital Chelsea and Grade II listed

Chelsea Bridge.

The location of the foreshore structure would be aligned with Monument Walk which marks

the central axis of the Royal Hospital Chelsea when viewed from the south. One of the

existing trees along Chelsea Embankment (A3212) would be removed during our works and

not replaced in order to open up views between the River Thames and the Royal HospitalChelsea. The proposed control kiosks would be aligned either side of the structure to further

frame the view.

The structure has been designed to provide a smooth curved frontage which would blend

into the existing river wall in order to minimise the effect on the long sweeping view

along the River Thames in this location. The proposed materials of the new wall would

complement those of the embankment.

The overall landscape design would seek to provide a visual and a pedestrian link betweenthe new structure and the historic access to the Royal Hospital Chelsea from the River

Thames. In addition, landscaping including replacement wall/fencing to Ranelagh Gardens,

planting and paving would be provided to ensure the restoration of the site required to

intercept the northern Low Level Sewer No.1 within the west bound carriageway and the

border of Ranelagh Gardens.



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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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Figure 3B: Artists impression of the site after the works are completed



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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

DRAFT IMAGE, PLACEHOLDER ONLYimage to follow

New RanelaghCSO outlet

Stonebench

Stone inlaymarkinghistoric axis

Reedterrace

Ventilationcolumns

Reed terraceBrick river wall withstone parapet

Electrical andcontrol kiosks

New pavingto Bull Ring

Chelsea

Embankmen

t

Ventilation column

N

Royal Hospital Chelsea(South Grounds)

New pedestriancentral refuge



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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 approximatelyonce 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

structures. This is likely to involve a small team of

inspection staff, a small team of support crew and twomobile cranes to lower the team into the shaft. This is

likely to take several days 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 Chelsea

Embankment (A3212).

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. Table3.2 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

developed anAir management plan to minimise possible odour and air qualityeffects arising from 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 faras possible.

Table 3.2: Key issues relating to site operation

Related documents:

Odour

Further information


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This section sets out documents which may be of particular interest. Further information on our proposals can be

found on our website (www.thamestunnelconsultation.co.uk) or is available upon request (call our customer centre

on 0800 0721 086).

Phase two public consultation material

Project information papers include general information about the Thames Tunnel project. There are 17 project

information papers, which cover various aspects of the project. Those project information papers that may be of

particular interest are set out below.

Icon Title Details

Build

Provides information on the different types of sites required for the Thames Tunnel

project and the typical construction activities that will be undertaken at each site.

Q&A ConsultationSets out the consultation we have undertaken to date on the project, the scope

of this phase two consultation and how interested parties can respond to this

consultation.

Design

Contains the design principles which have influenced the permanent appearance of

our sites once construction work is complete.

EnvironmentSets out the process the project is following to assess potential environmental effects

of the Thames Tunnel project.

Managing

construction

Includes information on what measures our contractors will put in place at our sites

during construction.

Odour Sets out ourAir management plan and how it will work.

Options Outlines the various ways to deal with sewage overflows.


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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 16 of the non-technical

summary and volume 16 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 15 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 K 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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Phase two consultation: Chelsea Embankment Foreshore

110-ED-PNC-00000-000076

For further information or to comment on our

proposals see our website:

www.thamestunnelconsultation.co.uk

Autumn 2011

It is very important that you understand theinformation we have provided. If you needfurther information in another language,

braille, large print or audio format pleasecontact us on 0800 0721 086.

Documents

P2 Chelsea Embankment SIP