Peir Nts Sections 1-5

8/3/2019 Peir Nts Sections 1-5

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Preliminary environmentalinformation report

Non-technical summary

Regulations 2 and 10 of the Infrastructure Planning(Environmental Impact Assessment) Regulations 2009


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Phase two consultation documentation

Project informationpapers

Build

Changes

Consultation

Design

Environment

Funding

Managing construction

Odour

Options

Overow

Regulatoryframework

Route and tunnel alignment

Route to consent

Settlement

Site selection

Timing Transport

Technical documents

Air management plan

Bookofplans

Code of construction practicePart A: General requirements

Consultation strategy and statement ofcommunity consultation

Design development report

Draftwastestrategy

Interim engagement report

Needs Report Phasetwoschemedevelopmentreport

Preliminary environmental information report

Report on phase one consultation

Siteselectionbackgroundtechnicalpaper

Site selection methodology paper

Site information papers Abbey Mills Pumping

Station

ActonStormTanks

AlbertEmbankmentForeshore

Barn Elms

BecktonSewageTreatmentWorks

BekesbourneStreet

BlackfriarsBridgeForeshore

CarnwarthRoadRiverside

Chambers Wharf

ChelseaEmbankmentForeshore

Cremorne Wharf Depot

Deptford Chrurch Street

Dormay Street Earl Pumping Station

FalconbrookPumpingStation

GreenwichPumpingStation

Hammersmith PumpingStation

HeathwallPumpingStation

JewsRow

KingEdwardMemorialParkForehore

KingGeorgesPark

Kirtling Street

Otherworks

Putney Bridge Foreshore

Shad Thames PumpingStation

VictoriaEmbankment

Foreshore

General

Yourguidetophasetwoconsultation

Why does London need theThames Tunnel?

Feedbackform

Equalities form

Customeroverviewleaet


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i

Thames Tunnel

Non technical summary

List of contents

Page number

1 Introduction ...................................................................................................... 12 The Thames Tunnel project ............................................................................. 23 Alternatives....................................................................................................... 54 Approach to the assessment ........................................................................ 105 Project wide effects ....................................................................................... 226 Acton Storm Tanks ........................................................................................ 357 Hammersmith Pumping Station .................................................................... 498 Barn Elms ....................................................................................................... 639 Putney Bridge Foreshore .............................................................................. 7710 Dormay Street ................................................................................................. 9311 King Georges Park ...................................................................................... 10712 Carnwath Road Riverside ............................................................................ 12113 Falconbrook Pumping Station .................................................................... 13614 Cremorne Wharf Depot ................................................................................ 14915 Chelsea Embankment Foreshore ............................................................... 16216 Kirtling Street ............................................................................................... 17617 Heathwall Pumping Station ......................................................................... 19018 Albert Embankment Foreshore ................................................................... 20419 Victoria Embankment Foreshore ................................................................ 22120 Blackfriars Bridge Foreshore ...................................................................... 23521 Chambers Wharf .......................................................................................... 25022 King Edward Memorial Park Foreshore ..................................................... 26423 Earl Pumping Station ................................................................................... 27824 Deptford Church Street ............................................................................... 29025 Greenwich Pumping Station ....................................................................... 30326 Abbey Mills Pumping Station ...................................................................... 31727 Beckton Sewage Treatment Works ............................................................ 33028 Thames Tunnel site overview ..................................................................... 341


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Section 1: Introduction

Preliminary environmental information report Page 1 Non technical summary

1 Introduction

1.1.1 This report is a non-technical summary of the Preliminary EnvironmentalInformation Report which has been prepared for the Thames Tunnelproject.

1.1.2 The purpose of the Thames Tunnel project is to reduce and limit pollutionfrom storm water overflows to the tidal River Thames. The project isproposed to capture, store and transport for treatment the discharges fromcombined sewer overflows which have been identified by the EnvironmentAgency as unsatisfactory. The project is necessary to enable compliancewith the European Unions Urban Waste Water Treatment Directive. Itwould also help achieve the objectives of the Water Framework Directiveconcerning surface water quality.

1.1.3 Thames Water intends that an application would be submitted to theInfrastructure Planning Commission, or its successor, for development

consent to construct and operate the project.

1.1.4 The Preliminary Environmental Information Report, including this non-technical summary, has been prepared in accordance with therequirements of the 2009 Infrastructure Planning Environmental ImpactAssessment Regulations1

1.1.5 The structure of this non-technical summary reflects that of the PreliminaryEnvironmental Information Report. A description of the Thames Tunnel isincluded in Section

. It provides information at a point in time duringthe assessment process to facilitate effective consultation.

2, and the alternatives which have been consideredare described in Section 3. Section 4 summarises the approach to the

assessment and includes the topic specific methodologies used toundertake the assessments. The summary of the project wideassessment is provided in Section 5 with a summary of the preliminaryassessment findings set out for each of the twenty two sites in Sections 6to 27. Figure 28.1 gives an overview of the location of the sites andtunnel route.

1.1.6 Phase two consultation on the Thames Tunnel project includesconsultation on the Preliminary Environmental Information Report. Theoutcome of this consultation and the ongoing technical engagement withstakeholders as well as environmental data gathering and ongoing

assessment will be presented in the Environmental Statement.

1 The Infrastructure Planning (Environmental Impact Assessment) Regulations 2009


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Section 2: The Thames Tunnel Project


2 The Thames Tunnel project

2.1 Background to the project

2.1.1 Londons sewer system was designed in the 1800s to handle wastewaterand run-off rainwater through a combined collecting system. Combinedsewer overflows were incorporated into the sewer system as reliefstructures to prevent flooding caused by sewer overloading, especiallyduring periods of heavy rainfall.

2.1.2 The capacities originally allowed for in the interceptor and combined sewersystems designed by Sir Joseph Bazalgette in the 1850s andsubsequently extended, have now been substantially exceeded. Thisresults in frequent and substantial discharges into the River Thames.Currently, overflows from the sewers to the Thames Tideway (being thetidal reaches of the River Thames) occur more than fifty times per year atthe most frequently overflowing combined sewer overflows.

2.1.3 There is a need to reduce these incidents in order to comply with the EUUrban Waste Water Treatment Directive and the related UK Urban WasteWater Treatment Regulations and for Thames Water to implement the UKGovernments request for a solution.

2.1.4 The Thames Tunnel project, in conjunction with the Lee Tunnel andupgrades to Londons sewage treatment works, has been determined (byindependent studies and confirmed by Thames Water) to be the besttechnological solution and most cost-effective means to deal with thedischarges and to meet the regulatory requirements.

2.2 Summary description of the project2.2.1 The Thames Tunnel project is a linear infrastructure scheme whose

primary objective is to capture discharges from 34 of the mostunsatisfactory combined sewer overflows into the River Thames, in orderto meet EU and UK Government legal requirements.

2.2.2 The combined sewage (which is sewage combined with rainwater) thatcurrently flows directly into the River Thames from combined seweroverflows would be captured and stored in the main tunnel and connectiontunnels. The flows would then be transported along the tunnel, from westLondon to Abbey Mills in east London. The Lee Tunnel would then transfer

flows to Beckton Sewage Treatment Works, where it would be treatedwhen capacity exists.

2.2.3 The preferred route of the main tunnel would be approximately 25km longand would pass under the administrative areas of 14 London localauthorities in order to intercept the identified combined sewer overflows.

2.2.4 To determine the preferred scheme, a site selection process has beenundertaken, using a methodology which was adopted after consultation onthe proposed methods with the relevant local authorities and pan-Londonstakeholders. The Site selection methodology paper describes this indetail and is available on the Thames Tunnel consultation website2

2

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http://www.thamestunnelconsultation.co.uk/consultation-documents.aspx
http://www.thamestunnelconsultation.co.uk/consultation-documents.aspxhttp://www.thamestunnelconsultation.co.uk/consultation-documents.aspxhttp://www.thamestunnelconsultation.co.uk/consultation-documents.aspxhttp://www.thamestunnelconsultation.co.uk/consultation-documents.aspx


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2.3 Main tunnel route

2.3.1 In broad terms the main tunnel route starts in west London and generallyfollows the route of the River Thames eastwards, intercepting thosecombined sewer overflows identified for interception and ensuring flowscan be transferred to the connection with the Lee Tunnel at Abbey Mills,and onwards to Beckton Sewage Treatment Works. A range of routeshave been considered for the main tunnel, and three routes were putforward at the phase one consultation stage. These were the RiverThames route, the Rotherhithe route, and the Abbey Mills route (seeFigure 3.1). In all options considered, the horizontal alignment of the maintunnel generally followed the River Thames where possible.

2.3.2 The Abbey Mills route was identified as the preferred route at the phaseone consultation stage. The Report on phase one consultation2detailsthe feedback received and concluded that the Abbey Mills route remainsthe preferred route. Therefore only the Abbey Mills route was taken

forward for further scheme development, and this is the preferred routeproposed for phase two consultation.

2.3.3 The alignment of this route follows the River Thames between westLondon and Rotherhithe, but then moves away from the River Thamesfollowing the Limehouse cut north-eastwards to terminate at Abbey MillsPumping Station. This reduces the length of the main tunnel byapproximately 9km as compared to the two alternative routes previouslyconsidered.

2.4 Main and connection tunnels

2.4.1 The internal diameter of the majority of the main tunnel is up to 7.2m,whilst the western end (to Acton) would be up to 6.5m. A range ofconnection tunnels would also be required to join the combined seweroverflows to the main tunnel. The longest connector tunnel fromGreenwich Pumping Station to Chambers Wharf is proposed to be up to5m in diameter.

2.4.2 The depth of the main tunnel would be between approximately 30m inwest London and up to 70m at Abbey Mills Pumping Station. Theconnection tunnels are expected to be shallower.

2.5 Site types

2.5.1 Two main categories of sites are required to construct and operate theThames Tunnel project:

a. The works for interception and control at existing combined seweroverflows and connection to the main tunnel would require a series ofsites (combined sewer overflow sites).

b. A series of sites are required for the construction and operation of themain tunnel (main tunnel sites).

2.5.2 Each combined sewer overflows site must accommodate the permanentstructures required for the operation and control of the combined seweroverflows and, on a temporary basis, the construction equipment and


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activities required to create the combined sewer overflow interception andcontrol facilities.

2.5.3 Main tunnel sites are needed as the start or end point for a tunnel boringmachine, which would build the main tunnel. A series of main tunnelconstruction sites are required to allow the tunnel boring machine to startthe tunnelling, and to be taken out when digging is complete.

2.5.4 The location of preferred combined sewer overflows sites and main tunnelsites at phase two consultation stage are indicated in Figure 28.1.

2.5.5 Other works are also needed to make modifications to the existing sewersystem, including modifications to Beckton Sewage Treatment Works.

2.6 Stages and timing of the project

2.6.1 The project is subject to many external influences, notably the outcome ofpublic consultations and the planning process, but also government

direction, regulatory approval and funding will dictate the pace of anyimplementation.

2.6.2 The main development and implementation steps required for the projectto be delivered are all linked together and include:

a. design

b. planning and consenting

c. communication and consultation

d. field investigations

e. land acquisition

f. procurement

g. enabling works

h. construction

i. commissioning

j. operation

2.6.3 For the purposes of the preliminary assessment the working assumption isthat construction would start in early 2015, and be completed by 2022.This assumption will be reviewed and any changes included in the

Environmental Statement.


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Section 3: Alternatives


3 Alternatives

3.1 Background

3.1.1 Under the Infrastructure Planning (Environmental Impact Assessment)Regulations 2009, the Preliminary Environmental Information Report mustcontain an outline of the main alternatives studied by the applicant andan indication of the main reasons for the applicants choice, taking intoaccount the environmental effects.

3.1.2 The Preliminary Environmental Information Report provides an outline ofthe following categories of alternatives which have been considered:

a. Strategic (ie tunnel and non tunnel) alternatives to address theproblem of the combined sewer overflow discharges into the Tideway

b. Alternative tunnel routes

c. Alternative drive strategies and alternatives to the preferred main driveand reception sites, and

d. Alternatives to each of the preferred combined sewer overflow sites forinterception works.

3.2 Strategic alternatives

3.2.1 Various tunnel and non tunnel alternatives have been assessed in aprogramme of studies stretching back over ten years. These alternativesincluded: widespread application of Sustainable Urban Drainage Systems(to capture rainfall); changing the combined sewer system into separatedfoul sewers and surface water drains; and also consideration of separate

western and eastern tunnels. Both the Sustainable Urban DrainageSystems approach and the sewer separation approach would be muchmore expensive than a storage and transfer tunnel. It is also unlikely thatthe former would be viable given the extensive areas needed whilst thelatter would cause unacceptable levels of disruption to London. Theseparate tunnels approach would not meet the requirements of the UrbanWaste Water Treatment Directive.

3.2.2 All of the studies undertaken by Thames Water have concluded that asingle storage and transfer tunnel between west London and treatmentfacilities in East London is the most cost effective way of achieving the

required water quality objectives within the required timeframe. Theseconclusions have been supported by recent Governments and ThamesWater has been directed to develop the tunnel solution.

3.3 Alternative tunnel routes

3.3.1 Two alternative tunnel routes to the preferred Abbey Mills route have beenconsidered, these being the River Thames Route and the RotherhitheRoute (Figure 3.1). The alternatives are similar in that the tunnel wouldgo to Beckton directly rather than Abbey Mills.

3.3.2 It has been concluded that the Abbey Mills route has several considerable

advantages and was selected as the preferred route for phase oneconsultation. The substantial reduction in construction scope associated


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with the shortest tunnel length and fewest main construction sites, coupledwith tunnelling through less difficult ground, results in the Abbey Mills routebeing the safest and least cost construction choice. In cumulative terms, itwould have the least environmental impact, slightly fewer communityimpacts, fewest property issues and lower planning risks.

3.3.3 The outcome of phase one consultation supported the conclusion that theAbbey Mills route was the most appropriate route. The Abbey Mills routehas therefore been retained as the preferred route for phase twoconsultation.

3.4 Drive strategy and main drive and reception sites

3.4.1 The selection of a tunnel drive strategy and selection of main drive andreception sites has been undertaken in accordance with the published siteselection methodology. This methodology used a filtering process toidentify a long list of possible sites which was then refined to a short list

and eventually a preferred list.3.4.2 In order to identify a preferred site, each of the short-listed sites was

assessed across five disciplines: engineering, property, planning,environment and community. The results were then used in multi-disciplinary workshops to identify preferences.

3.4.3 In order to identify a preferred drive strategy, sites were identified withinzones (of which there were nine for the Abbey Mills tunnel route). Theapproach enabled an extensive series of comparisons to be made oftunnelling from one zone to another using the information collected oneach of the short-listed sites.

3.4.4 With each comparison made, it was possible to eliminate a number ofdrive options until the list was finally reduced to one: the preferred tunneldrive option. The comparisons that had to be made to arrive at thepreferred option included:

a. Comparison 1: Comparing the use of Chambers Wharf with the use ofKing Edward Memorial Park for a main tunnel site.

b. Comparison 2: Comparing the use of Barn Elms with the use ofCarnwath Road Riverside for a main tunnel drive site.

c. Comparison 3: Comparing the use of Abbey Mills Pumping Station as

main tunnel drive site or main tunnel reception site.3.4.5 For comparison 1, the preference is to use Chambers Wharf as a main

tunnel drive site, eliminating options that use King Edward Memorial Parkfor this purpose. The main reasons include the brownfield nature ofChambers Wharf and the reduced impacts on park users at King EdwardMemorial Park. As a result of this comparison, the drive options that useda main tunnel drive site at King Edward Memorial Park were eliminated. Itis noted that prior to this comparison, Chambers Wharf had already beenidentified as a preferred site in Southwark (in comparison with KingsStairs Gardens, see below).

3.4.6 For comparison 2, the preference is to use Carnwath Road Riverside as amain tunnel drive site, eliminating options that use Barn Elms for this


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purpose. The main reasons include the brownfield nature of CarnwathRoad Riverside, which also has much better river access via an existingwharf. As a result of this comparison, the six options that use a maintunnel site at Barn Elms were eliminated.

3.4.7 For comparison 3, it was concluded that driving the main tunnel fromChambers Wharf to Abbey Mills (and using Abbey Mills to receive thetunnel boring machine used to build the connection tunnel from GreenwichPumping Station), should be selected. One of the main factors thatinfluenced this decision was that further technical work and discussionswith the Lee Tunnel project team and Olympic Delivery Authority on theirexperience with the Olympic Park has shown that transporting substantialmaterial volumes to and from the site by the River Lee is not desirable.Therefore, the use of Chambers Wharf as a main tunnel drive site, with theability to transport material by barge, was considered more acceptablethan the use of Abbey Mills as a drive site with possible reliance on road

transport to remove material.3.4.8 Based on the above comparisons and conclusions reached by all

disciplines, the preferred drive option for connecting the main tunnel siteswas identified as follows:

a. Main drive from Carnwath Road Riverside to Acton Storm Tanks.

b. Main drive from Kirtling Street to Carnwath Road Riverside

c. Main drive from Kirtling Street to Chambers Wharf

d. Main drive from Chambers Wharf to Abbey Mills

e. Long connection tunnel drive from Greenwich Pumping Station toChambers Wharf

3.4.9 Whilst the above comparisons describe the main steps taken to identifythe preferred drive strategy, it is also necessary to consider the main drivesites and the alternatives to them. The main alternatives are representedby the other short-listed sites in each area.

3.4.10 Carnwarth Road Riverside was chosen as a main drive site in the westbecause the site is brownfield, the presence of wharfs and width ofThames would allow use of barges to remove material during constructionand the site has good access to major road network. Other short-listedsites considered in this area were Barn Elms, Feathers Wharf and FulhamDepot.

3.4.11 Kirtling Street was chosen as a main double drive site in the central part ofthe route because the site is brownfield in a mainly industrial area, hasdirect river access with potential to allow use of barges to remove materialduring construction and has good access from Nine Elms Lane (A3025).In addition it would cause less disruption to residents than some othershort-listed sites and would not affect early stages of Battersea PowerStation Redevelopment. Other short-listed sites considered wereBattersea Park, Battersea Power Station, Part of Battersea Power Station,Heathwall Pumping Station and Midddle Wharf, Post Office site on Nine

Elms Lane, a site on Post Office Way, Depots on Ponton Road, an Open


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Space off Grosvenor Road and the Foreshore at Riverside House nearVauxhall Bridge

3.4.12 Chambers Wharf was chosen as a main drive site in the eastern part ofthe route because the site is brownfield, has direct river access withpotential allow use of barges to remove material during construction andthere would be no need to divert Thames Path. King Stairs Gardens wasthe only other short-listed site in this area.

3.5 Alternative combined sewer overflow interception sites

3.5.1 The site selection methodology was used to compare alternativecombined sewer overflow sites. As for the main tunnel drive sitesdescribed above, this methodology used a filtering process to identify along list of possible interception sites. This was then refined to a short listand eventually a preferred list.

3.5.2 For most of the combined sewer overflow interceptions, between two and

five short-listed sites were considered in order to identify the preferred sitealthough in a few cases there was only one viable short listed site. Ineach case, the preferred site was identified through an integrated multi-disciplinary approach.

3.6 More information

3.6.1 Volume 3 of the Preliminary Environmental Information Report providesmore extensive information, most notably in respect of the alternative drivestrategies, main tunnel drive sites and alternative combined seweroverflow interceptions.


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Figure 3.1 Thames Tunnel preferred route (Abbey Mills) and alternative routes


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Section 4: Approach to the assessment


4 Approach to the assessment

4.1 Introduction

4.1.1 This section summarises the general assessment methodology and the

specific methodologies for assessing each environmental topic included inthe non-technical summary. Work which has not been completed will beundertaken in the coming months and reported in the EnvironmentalStatement. It is noted that the assessment presented in this reportrepresents preliminary findings.

4.1.2 The environmental impact assessment (EIA) methodology has beendeveloped in accordance with the requirements of the 2011 EIARegulations (Town and Country Planning Act 1990) and the 2009 EIARegulations.

4.1.3 The assessment has involved a process of interaction between

engineering design, planning and environmental considerations to ensurethat mitigation measures are considered and wherever possibleincorporated in the project. Throughout the design process, attention hasbeen and will continue to be paid to minimising adverse effects on theenvironment during construction and operation. Where possible, theproject will incorporate measures to prevent, reduce and offset anysignificant adverse effects arising and seek to promote beneficial effects.

4.2 Scoping and technical engagement

4.2.1 A Scoping Report (March 2011) was prepared prior to the findings of theformal phase one consultation being collated and reviewed. It scoped the

potential environmental effects associated with the preferred schemepresented for the phase one consultation process. Scoping opinionshave been considered and addressed where appropriate in theassessment process to date.

4.2.2 Consultees have the opportunity to comment on the PreliminaryEnvironmental Information Report as part of the phase two consultationprocess.

4.2.3 Engagement with statutory and non-statutory consultees has beenundertaken since the start of the environmental assessment processthrough an extensive programme of briefing meetings and presentations,technical working groups and workshops. This will continue through to thecompletion of Environmental Statement.

4.3 Baseline

4.3.1 Prior to undertaking the impact assessments for each topic, existingenvironmental conditions (baseline) have been identified.

4.3.2 Information has been obtained from observations made on-site, fieldsurveys, information provided by consultees and desk based sources.This allows the existing environmental resources present to be identifiedand evaluated.


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4.3.3 Baseline data collection is still underway and this varies from topic to topic.Details of desk based data review, supported by site visits undertakenwhere appropriate, and survey data collection that has been completed todate are described in the Preliminary Environmental Information Report.

4.3.4 Additional data arising from the completion of the ongoing surveys will betaken into account in the ongoing assessment and presented in theEnvironmental Statement.

4.3.5 The environmental baseline is likely to change irrespective of the ThamesTunnel project, for example as a result of new residential developmentbuilt in proximity to some of the sites. For each site, the assessmentidentifies where such changes are likely.

4.4 Methodology

Effects

4.4.1 The assessment considers all types of effects as required by the 2009 EIARegulations, comprising:

a. direct and indirect (including secondary) effects

b. short term (less than 12 months), medium term (1 to 5 years) andlong-term (+ 5 years) effects

c. permanent and temporary effects

d. cumulative effects

e. beneficial and adverse effects

4.4.2 Two main categories of effects are assessed, namely construction effectsand operational effects. Effects during the construction and operation ofthe Thames Tunnel have been considered at individual sites and whererelevant at a project wide level.

4.4.3 The construction assessment considers temporary, construction activitiesand works such as construction traffic and temporary haul roads. It alsoincludes an assessment of effects which although arising during theconstruction phase, would result in permanent works, such as theconstruction of shafts, the tunnel, and ventilation structures. Constructionphase effects will be managed through the implementation of a Code ofConstruction Practice.

4.4.4 Operational effects refer to those effects which arise once the ThamesTunnel is built and operational such as improvements to water quality andthe effects on aquatic ecology.

4.4.5 Cumulative effects arise from the interaction of the project with otherdevelopments. Where significant projects are under development, theremay be elevated effects on the environment which exceed the effects ofeach project in isolation. At this preliminary stage of the assessment,cumulative effects have not been considered. However planned majordevelopments in the vicinity of each site have been incorporated into thefuture baselines that have been used in the assessments (paragraph4.3.5). An assessment of cumulative effects will be included in theEnvironmental Statement.


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Assessment years

4.4.6 For the purposes of the preliminary assessment, it has been assumed thatthe overall construction programme would last from 2015 to 2022(enabling construction works would start in 2015, with main constructionstarting in 2016). However, the assessment year (or years) for theassessment of construction impacts at any one site varies since the peakin construction activities varies from site to site. The appropriateassessment year for each site has been identified utilising relevant bestpractice guidance and professional judgement.

4.4.7 The assessment of project wide effects has identified the overall peak inconstruction activities across all sites.

4.4.8 The assessment year of operation has been assumed as being 2023.This is the first full normal 12 months of operation (excluding anycommissioning period).

Assessment areas

4.4.9 The extent of the assessment area varies from topic to topic. For sometopics, the focus of the assessment is on and adjacent to the site, such asland quality. For other topics such as transport the assessment area ismore extensive.

Significance criteria

4.4.10 The table below is a generic significance criteria matrix that has beenused, or adapted for individual topic assessments, in order to determinethe significance of effects:

Table 4.1 Generic significance matrix

Sensitivity of receptor

High Medium Low

Scale ofImpact

High Major adverse Major adverse Moderateadverse

Medium Major adverse Moderate adverse Minor adverse

Low Moderate adverse Minor adverse Negligible effect

Negligible Minor adverse Negligible effect Negligible effect

Approach to mitigation

4.4.11 Mitigation opportunities can be identified at any stage in the evolution of ascheme. The assessment process feeds into an iterative design processthat has been, and continues to be, used to help refine the project, withthe objectives of avoiding and reducing adverse environmental effects.Mitigation measures are being incorporated into the design so far aspossible. A Code of Construction Practice is also being developed. Bothform the environmental design measures integrated into the project.


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4.4.12 Mitigation measures have generally been identified by regularly reviewingthe emerging preliminary assessment of the likely significantenvironmental effects of the project. Where practicable and economic,design adjustments have been made to the project.

4.4.13 Likely significant effects and associated potential environmental responsemeasures that have not been addressed in the project to date areoutstanding mitigation measures. As the design is refined through theongoing environmental assessment process, it is intended thatoutstanding mitigation measures will be incorporated into the project.

4.4.14 Where residual effects remain after the proposed mitigation has beenapplied to date, these are identified.

4.4.15 Given the preliminary stage of the assessments, the PreliminaryEnvironmental Information Report focuses on the approach to mitigation.Where necessary, detailed mitigation proposals will be developed andincluded within the Environmental Statement.

4.5 Air quality and odour

4.5.1 The local air quality assessment follows the methodologies outlined in theDepartment for environment, food and rural affairs (Defra) Local AirQuality Management Technical Guidance and the London Councils BestPractice Guidance. The odour assessment has been undertaken withreference to the relevant Defra and Environment Agency benchmarks.

4.5.2 Existing conditions have been established through a review of air qualitymonitoring data collected from local authorities. In addition to thismonitoring, baseline monitoring has been established at all the proposed

sites using diffusion tubes. Background data have also been collectedfrom the Defra website. Odour complaint data have been collected todetermine whether there are any existing odour issues at the sites; this willbe supported by baseline monitoring currently being undertaken.

4.5.3 The methodologies proposed for the assessment are described in thePreliminary Environmental Information Report. While thesemethodologies have been followed for the Preliminary EnvironmentalInformation Report for the assessment of construction dust and odour(during operation), a qualitative assessment based on professionaljudgement has been undertaken for the assessment of emissions from

road traffic, river barges and plant during construction, as data required forthe quantitative assessment is being confirmed. A full assessment usingdispersion modelling will be undertaken for the Environmental Statement.This will include consideration of cumulative effects arising from otherprojects, mitigation measures and residual effects. It is noted that theodour assessment results presented in the Preliminary EnvironmentalInformation Report provide a conservative assessment of the odour effectsof the Thames Tunnel project.

4.6 Ecology aquatic

4.6.1 The assessment has been guided by the Institute for Ecology andEnvironmental Managements Guidelines for Ecological Impact


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Assessment in the UK (2006) supplemented by their specific guidance formarine and coastal assessment (2010).

4.6.2 The aquatic ecology assessment examines the effects of the project onwater based ecology, including river habitats, marine mammals,invertebrates and fish (Figure 4.1). Data and assessment of algae will bereported in the Environmental Statement. Water birds are considered inthe terrestrial ecology assessment.

4.6.3 The assessment is based on field survey data for fish, invertebrates andhabitats collected for the project, and background data obtained from deskstudies. Data from autumn 2010 surveys is presented in the PreliminaryEnvironmental Information Report. Data from surveys in 2011 will bereported in the Environmental Statement. The scope and methodologiesadopted for the field surveys has been agreed with the EnvironmentAgency. Where possible, survey methodologies are based on publishedgood practice.

4.6.4 The assessment describes the likely nature and magnitude of changes toaquatic ecology receptors arising from the project. Determination of thesignificance of an effect is based on professional judgement whencomparing the sensitivity of the receptor with the magnitude of an impact.

4.6.5 The Environmental Statement will present all baseline data obtained andwill provide an updated site by site assessment including cumulativeeffects with other projects as well as a project wide assessment.Mitigation measures will be described and residual effects identified.

Figure 4.1 A juvenile flounder

4.7 Ecology terrestrial

4.7.1 The assessment has been guided by the Guidelines for Ecological ImpactAssessment in the United Kingdom (2006). The assessment examinesthe effects of the project on land based ecology, including habitats,badgers, birds, plants, invertebrates, reptiles, otter, water vole and bats(Figure 4.2). Existing conditions have been established through desk-

based research and on-site habitat and species surveys. The assessmentdescribes the likely nature and magnitude of changes to ecological


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features arising from the project. Determination of the significance of aneffect is based on the magnitude of the effect and the value and responseof the ecological feature to that effect, using recognised guidance andprofessional judgement. Due to seasonal requirements of the surveys,much of the baseline survey data was not available for the Preliminary

Environmental Information Report.4.7.2 The value of ecological features on site and the significance of effects,

including cumulative effects with other projects, will be assessed andreported in the Environmental Statement. The Environmental Statementwill also present mitigation measures and the residual effects anticipatedto arise from the project.

Figure 4.2 A juvenile common pipistrelle bat

4.8 Historic environment

4.8.1 Assessment of effects on the historic environment has been guided bynational policy (Planning Policy Statement 5), Greater London Authoritypolicy and Local Authority planning policy.

4.8.2 Data held by the Historic Environment Record, English Heritage, and theMuseum of London, and a range of documentary and cartographicsources has been reviewed. A walkover inspection of sites has also been

carried out. Known above ground and buried heritage assets within andaround each site are described. The potential of each site to containadditional, previously unrecorded heritage assets is also detailed. Foreach heritage asset, its value is described based on whether it is protectedby any form of statutory designation and by drawing on professionaljudgement.

4.8.3 The magnitude of the likely construction and operational impacts uponeach heritage asset and the resulting environmental effects are assessed.For example, construction works might lead to the removal of buriedheritage assets as below ground construction works are carried out. The

magnitude and significance of effects is measured using a set of clearcriteria and professional judgement. Measures that might be required to


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mitigate significant adverse effects are identified, and the resulting residualeffects described.

4.8.4 The Environmental Statement will present the final assessment findingsfor historic environment, including an assessment of setting on historicassets. An assessment of project wide effects will be undertaken as wellas an assessment of cumulative effects which may arise from otherprojects. Mitigation measures and residual effects will be presented.

4.9 Land quality

4.9.1 The assessment of land quality has been carried out using EnvironmentAgency and Defra guidance CLR11: Model Procedures for theManagement of Land Contamination, British Standard 10175: Code ofPractice for the Investigation of Potentially Contaminated Sites andPlanning Policy Guidance 23 Development and Pollution Control. Thesethree documents are used to assist assessing the degree to which land is

contaminated within the definition under Part IIA of the EnvironmentalProtection Act 1990 (as amended by the Water Act 2003).

4.9.2 Site baselines have been established by undertaking site visits andthrough the collation of environmental data obtained for the site andsurrounding areas; this includes the geological setting, chemical orphysical make up of soils and groundwater (from boreholes), site history,and the presence of contaminating industries/infrastructure. An exampleof borehole drilling undertaken to collect information about groundconditions is shown in Figure 4.3. The site baseline is used to develop asite conceptual model that describes the environmental features of the sitetogether with the expected interaction of potential contamination sourceswith the environment (using a Source-Pathway-Receptor approach).

4.9.3 The qualitative Source-Pathway-Receptor analysis is then assessed usingclearly defined criteria and professional judgement to obtain the likelysignificance of impacts and the sensitivity of each receptor affected. Amatrix is then used to give an overall significance of effect on a five pointscale which is designed to categorise the effects as significant or not-significant.

4.9.4 The assessment will be finalised and reported in the EnvironmentalStatement including an assessment of cumulative effects. Mitigationmeasures which may be required will be described and residual effectsidentified.


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Figure 4.3 Thames Water land borehole drilling

4.10 Noise and vibration

4.10.1 The prediction and assessment of construction noise and vibration hasbeen carried out using British Standard 5228:2009 Code of Practice forNoise and Vibration Control on Open Construction Sites. Theassessment of vibration disturbance on people in buildings also usesBritish Standard 6472-1:2009 Guide to evaluation of human exposure tovibration in buildings.

4.10.2 Existing noise conditions have been established through a review ofmonitoring data collected at some of the sites and background data

collected from the Defra website for sites where monitoring is yet to becarried out. Where surveys have been carried out, monitoring has takenplace at a range of locations in the vicinity of the site to represent locationsthat could be sensitive to noise, including residential dwellings, communityfacilities and businesses.

4.10.3 The assessment of noise effects is made by comparing predicted noiselevels during construction or operation against predicted noise levels in thefuture without the project. The impact associated with change in noiselevel is evaluated along with other parameters, such as the number ofsensitive locations and their level of sensitivity, to assess the significance

of the effect. In the case of vibration, the effects are assessed in terms ofwhether vibration levels might exceed threshold levels associated withdisturbance or building damage.


4.11 Socio-economics

4.11.1 The assessment of socio-economic effects follows best practice guidance

including the English Partnerships Additionality Guide and HM TreasuryGreen Book. Regional and local planning policy standards are also


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considered in the assessments where applicable. Where there is anabsence of best practice guidance or standards, professional judgement isused.

4.11.2 Existing site conditions have been established through the collection ofdata in relation to three broad socio-economic themes: the economy;social infrastructure, facilities and services; and amenity; both at a site-specific and project wide level. Data have been collected primarily frompublished information and on-line sources. Site visits were undertakenwhere further investigation was required and data collected from otherenvironmental disciplines has been used where available and relevant.On the basis of these data, a description of places and groups that havethe potential to be affected by the project is given. A judgement is thenmade regarding their sensitivity to potential changes in theircircumstances.

4.11.3 The assessment of the magnitude of an impact reflects consideration of:

the extent, duration, permanency and likelihood of the impact; thenumbers of people affected; conformity with standards of provision of openspace; and/or the value of the resource. The significance of an effect isbased on professional judgement used to weigh sensitivity against themagnitude of an effect.


4.12 Townscape and visual

4.12.1 The assessment has been guided by the Landscape Institutes Guidelinesfor Landscape and Visual Impact Assessment, the Design Manual forRoads and Bridges (Landscape Effects) and Mayor of Londons LondonView Management Framework (2010).

4.12.2 Existing conditions have been established through desk-based researchand on-site surveys. The townscape character baseline describes thecharacteristics of the assessment area, in terms of zones or characterareas, and the sensitivity of each of these to change. Similarly, the visualbaseline describes a number of agreed viewpoints to illustrate existingvisual amenity and sensitivity of views to change.

4.12.3 The assessment describes the likely nature and magnitude of changes toindividual townscape character areas and viewpoints arising from theproposals. The significance of effects on townscape character areas andviewpoints is determined through the application of professional judgmentto weigh the magnitude of an impact against the sensitivity of thetownscape or visual receptor.

4.12.4 The assessment will be finalised and reported in the EnvironmentalStatement including an assessment of cumulative effects. Mitigationmeasures which may be required will be described and residual effects

identified.


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4.13 Transport

4.13.1 The assessment of transport effects is based on Transport for LondonsTransport Assessment Best Practice Guidance, Transport for Londonguidance on specific technical issues, the Guidelines for theEnvironmental Assessment of Road Traffic (Institute of EnvironmentalManagement and Assessment) and the Design Manual for Roads andBridges (Environmental Assessment, Volume 11).

4.13.2 Existing transport conditions are being established through acomprehensive programme of transport survey work, supplemented bydata gathered from Transport for London, local highway authorities andother sources.

4.13.3 The assessment examines the likely changes to the pedestrian, cycle,public transport, highway and river transport networks that would occur asa result of the project. It takes account of other planned development and

infrastructure changes. For the Preliminary Environmental InformationReport professional judgement has been used to determine thesignificance of transport effects on residents, businesses and transportnetwork users at each site and across the transport network project wide.


4.14 Water resources groundwater

4.14.1 The effects on groundwater have been assessed in the context of theWater Framework Directive and the Environment Agencys LondonGroundwater Licensing Policy (2006), which is designed to manageabstraction from the Chalk aquifer in London.

4.14.2 Information on the existing groundwater conditions (quantity and quality)have been collected through a review of information from public domainsources including the Environment Agency, Thames Water, LocalAuthorities as well as site specific site investigation and monitoring data(Figure 4.4). Ongoing groundwater monitoring data will be utilised in theassessment for the Environmental Statement.

4.14.3 The construction activities around the individual shaft sites and the tunnelhave the potential to affect groundwater by creation of pathways,obstruction to groundwater flows and dewatering effects. Theidentification and determination of potential effects has been undertakenon a preliminary basis through a qualitative assessment of the impactsand construction of receptor value.



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Figure 4.4 Thames Water groundwater monitoring borehole

4.15 Water resources surface water

4.15.1 The assessment methodology has been derived specifically for the projectin order to assess the effect of the proposed Thames Tunnel project onsurface water. The process is broken down into six-stages, which combinethe Environment Agency Water Framework Directive assessmentguidance and the Water Environment Sub-Objective WebTAG Unit 3.3.11methodology.

4.15.2 For the purposes of the site-specific assessments, the existing waterquality data has been sourced from the Environment Agencys ThamesRiver Basin Management Plan. For the project wide assessment, thebiggest summer rainfall events over a period of 40 years have beenmodelled and each scenario subsequently tested for compliance. Thismodelling allowed for a comparison of Tideway water quality with theThames Tunnel against the predicted Tideway water quality without theThames Tunnel project.

4.15.3 The assessment describes the effects in the context of the WaterFramework Directive environmental objectives. To do this the impact ofthe project as a whole and each proposed site is considered against thesensitivity of the receptor for both the construction and operational phaseof each site.



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4.16 Water resources - flood risk

4.16.1 The assessment has been guided by the requirements of Planning PolicyStatement 25: Development and Flood Risk (2010), The London Plan(2009) and The Mayors Draft Water Strategy (2009).

4.16.2 Existing conditions have been established through on-site surveys anddesk-based studies including review of flood defence information providedby the Environment Agency and available hydraulic modelling data for theRiver Thames and its tributaries.

4.16.3 The assessment describes the potential change in flood risk which couldresult from the development proposals and utilises additional rivermodelling work to draw conclusions on the likely significance of effects(Figure 4.5). The assessment for the Environmental Statement willdetermine which mitigation measures are appropriate to ensure that theproposals do not increase the risk of flooding to the surrounding area.

Figure 4.5 Physical river model of the River Thames being used toassess flood risk


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Section 5: Project wide effects


5 Project wide effects

5.1 Introduction

5.1.1 The purpose of the Thames Tunnel is to address discharges of untreatedwastewater from combined sewer overflows and thereby improve thewater quality of the tidal River Thames and its tidal tributaries (known asthe Thames Tideway).

5.1.2 There are likely to be significant environmental effects from the project onthe wider geographic area within the Thames Tideway than thoseidentified at individual sites. There are also likely to be effects along theroute of the main tunnel and connection tunnels. As with site specificenvironmental effects they can be both adverse and beneficial and canoccur during construction and operation.

5.1.3 The approach and preliminary findings of those topics that are consideredlikely to have significant project wide effects are given below.

5.2 Air quality

5.2.1 Existing conditions have been established using air quality monitoring datafrom local authorities. Additional air quality monitoring has also beenestablished using diffusion tubes at survey locations agreed with the localauthorities. These surveys are ongoing. Weather data, backgroundpollutant maps, local planning policy details and technical guidancedocuments have also been collated to inform the assessment.

5.2.2 A detailed assessment of the project wide air quality effects usingcomputer modeling will be undertaken using the outputs from the strategic

traffic modeling which is currently underway. For the purposes of thePreliminary Environmental Information Report a preliminary assessmentusing professional judgement has been undertaken.

5.2.3 Once the traffic model data are available, and following the governmentsDesign Manual for Roads and Bridges (DMRB) guidance, strategic roadswhich are predicted to experience an increase in annual average dailytraffic flows of 200 heavy goods vehicles as a result of the project will bemodelled as part of the project wide assessment.

5.2.4 Construction works at the individual project sites may give rise totemporary local traffic management measures including lane closures.Any lane closures are likely to lead to diversions and/or congestion, whichmay affect local air quality. There may also be project wide interactions ofconstruction traffic along major road corridors to and from depots whichcould have air quality effects. Other potential project wide air qualityeffects may arise from the emissions from tugs moving river barges andthe movement of construction personnel by car.

5.2.5 In terms of potential effects, guidance indicates that that any roadcorridors predicted to experience an increase of over 200 heavy goodsvehicles movements per day due to the project are likely to experience aminor adverse effect on air quality, while any predicted to experience an

increase of more than 500 heavy goods vehicles movements per day arelikely to experience a moderate adverse effect on air quality. The air


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quality effects of construction vehicles on all other road corridors areexpected to be negligible.

5.2.6 As part of this modelling and assessment exercise there is the opportunityto examine the construction programme and phasing at each site in orderto seek to minimise the daily cumulative number of heavy goods vehiclesusing specific strategic roads.

5.2.7 In the context of air pollutant emissions in the vicinity of the River Thamesand considering the distance of the barges from sensitive receptors andthe low numbers of barge movements, the effects of emissions from tugspulling river barges are assessed to be negligible.

5.2.8 In the context of air pollutant emissions due to traffic on roads thatconstruction workers may use to access construction sites and the smallnumber of car movements, the effects of emissions from constructionworker car journeys are assessed to be negligible.

5.2.9 It is considered unlikely that there would be any significant project wideeffects on air quality due to odour during operation of the project.

5.3 Ecology - aquatic

5.3.1 The Thames Tideway includes eleven wholly or partly aquatic designatedsites, which range from being of very high (International) to low-medium(Borough) value. During project aquatic ecology surveys a range of riverhabitats were recorded at the individual project sites. Broadly, habitats arefound to be more diverse upstream of Chelsea, with large gravelforeshores below the river walls, which are exposed at low tide in sitesbetween Hammersmith and Wandsworth. Habitats are considered to be

of medium (Metropolitan) value due to the presence of species andhabitats listed on national and regional Biodiversity Action Plans.

5.3.2 Marine mammal information has been obtained from three sources;Zoological Society of London, British Divers Marine Life Rescue andEssex Biodiversity Partnership. Mammal sightings are spread along theentire length of the Tidal Thames from Richmond to Rainham with agreater density of sightings between Westminster and Greenwich.Mammals are considered to be of a high-medium (Regional) value due tothe diversity of marine mammals species represented in the Tideway.

5.3.3 Long-term spring and autumn Environment Agency fisheries samplingdata from a range of Tideway sites has been collated. Fish data has alsobeen collected specifically for the project during autumn 2010. Figure 5.1shows the survey team preparing for one of these surveys. Furthersurveys have been undertaken during 2011 and the results will bereported in the Environmental Statement. There are approximately 125species of fish in the Thames Tideway, many of which are only occasionalvisitors, with the resident core including uncommon or threatened speciessuch as smelt, eel, salmon, sea trout, sea lamprey and river lamprey.Some of these are permanently resident in sections of the Tideway whileothers migrate through to move from freshwater to the sea.

5.3.4 The fish populations of the Tideway are sensitive to dissolved oxygen(which is influenced by organic pollution) and their distribution is


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particularly affected by salinity with some species being confined tofreshwater stretches, others to saline stretches and a relatively smallnumber able to tolerate intermediate brackish conditions. Populations ofsome uncommon species such as sea trout and both lamprey specieshave recovered somewhat in recent years while others such as eel have

declined dramatically (although not necessarily as a result of pollution).Fish are considered to be of high-medium (Regional) value due to therange of protected species (seven in total), the function of the fishcommunity within the Tideway ecosystem and recreational value of theresource.

5.3.5 Invertebrate data from the Environment Agencys sampling programme(mainly from 1989 onwards) and data collected specifically for the projectduring autumn 2010 has been collated. Further surveys have beenundertaken in 2011 and the results will be reported in the EnvironmentalStatement.

5.3.6 Generally, invertebrate communities in the Tideway are dominated byspecies tolerant to changes in salinity. The community is characterised bya larger proportion of worms, crustaceans (for example, crabs) and snails,compared with the freshwater environment, where insects tend todominate in terms of species diversity and abundance. The majority ofspecies present are relatively tolerant of polluted conditions, with fewclean water species indicators present. Several uncommon invertebratesare found in the Thames Tideway such as tentacled lagoon worm, amayfly, a river beetle and large-mouthed valve snail. However, the onlyspecies recorded in the project surveys during 2010 is a species of mudshrimp; although regarded as nationally uncommon, it is relatively

common in the Thames Tideway and was found at numerous sites.Invertebrates are considered to be of medium (Metropolitan) value in theThames Tideway due to the range of protected and notable species, setagainst the relative impoverishment of the community as a whole.

5.3.7 During the construction there are a range of potential cumulative impactsof in river construction that are likely to have significant effects on aquaticecology. These include temporary landtake, noise and vibration, lightspillage into the river, increase in suspended sediment in the river, riverchannel constriction and sediment disturbance and compaction.Operational impacts that are likely to cause significant aquatic ecology

effects are permanent in-river landtake and the water quality improvementassociated with the interception of the combined sewer overflowdischarges throughout the study area. The magnitude of these impactsand the assessment of the effects on aquatic ecology will be reported inthe Environmental Statement.


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Figure 5.1 Preparing for sampling during the aquatic ecology surveysautumn 2010

5.4 Historic environment

5.4.1 Project wide effects may arise through the cumulation of impacts onindividual heritage assets at each Thames Tunnel site, with theseindividual assets being associated with the key heritage route widethemes. These themes include; the influence of the River Thames on thelandscape (such as the formation of the floodplain); past industryassociated with the river; historic river management, transport andbridges; London as a world port; and Londons Victorian water systemsand public health. Bazalgettes plan for intercepting the Victorian sewer

system is shown in Figure 5.2.5.4.2 Historic environment information has been compiled at each Thames

Tunnel site from a broad range of archaeological and documentarysources, and using historic maps. Information will also be collated within astudy corridor along the line of the main tunnel and connecting tunnels inorder to define the key heritage themes.

5.4.3 Project wide construction phase effects could include individual site-specific impacts on heritage assets which, when combined, constitute agreater collective effect on a given class of asset. For example, at anumber of sites evidence of prehistoric land surfaces and river use may be

removed during construction, and the effect of removing such remains at anumber of foreshore locations across the project could result in a moresignificant environment effect.

5.4.4 Project wide operational phase effects could include changes to publicappreciation of the historic character and setting of heritage assets, forexample, changes to public appreciation of Bazalgettes Embankment, itsuniformity of architectural features. It might include possible changes toriverine deposition or scouring, affecting groups of heritage assets alongcertain stretches of the river and its foreshore, such as prehistoriclandscapes and post-medieval industrial wharves, jetties and barge beds.

5.4.5 Project wide effects will be assessed and presented in the EnvironmentalStatement, when baseline data on past dredging, along with existing


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riverine deposition and scour, is available. The effects from groundsettlement (lowering) on listed buildings and scheduled monuments, dueto tunnel construction, will also be considered.

Figure 5.2 Bazalgettes plan for intercepting sewers

5.5 Noise and vibration

5.5.1 Groundborne vibration is caused by below ground construction activitieswhich travel through the ground to surrounding buildings. This results invibration of floors, walls and ceilings which can also sometimes be heardas a low frequency rumbling noise (called groundborne noise).

5.5.2 The project wide assessment presents a preliminary assessment of thepredicted groundborne noise and vibration impacts arising from theoperation of tunnel boring machines and the temporary constructionrailway serving the tunnel boring machines during construction of the mainThames Tunnel (Figure 28.1), Frogmore Connection Tunnel, andGreenwich Connection Tunnel.

5.5.3 The groundborne noise and vibration potentially generated by the TunnelBoring Machines has been calculated using the established guidanceused in the United Kingdom for tunnelling works. The impact of thetemporary construction railway serving the tunnelling activities has beencalculated using a calculation method compliant with internationalstandards. An example of a Tunnel Construction Railway at the bottom ofa shaft is shown in Figure 5.3.

5.5.4 The significance of noise effects is based on the predicted impact andother factors, such as the total noise level, the numbers and types ofreceptors affected and the duration of impact. The significance of

vibration effects is assessed on the magnitude of exposure relative to


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guidance thresholds for disturbance as well as other factors, including thenumber of affected receptors and their uses.

5.5.5 The preliminary assessment suggests that at some locations the tunnelboring machine noise would be predicted to meet the noise level thresholdat which noise would be noticeable and some disturbance might beexpected. However, it is considered that the duration of the impact wouldnot be sufficient to cause appreciable, sustained disturbance to occupants.Hence it is anticipated that the overall effect (the resulting disturbance tooccupants in this case) would not be classified as significant.

5.5.6 Unlike the moving tunnel boring machine noise passing a given receptor,the temporary construction railway noise impact would be present for aperiod of a year or more during tunnel construction at some locations. It isconsidered that this could be significant if no mitigation measures wereimplemented, however the provision of appropriate mitigation wouldreduce the level of groundborne noise from the temporary construction

railway such that no residual significant effects are anticipated.

5.5.7 Using the appropriate guidance standard, the preliminary assessment forvibration from the tunnel boring machine predicts a low probability ofadverse comment impact at a proportion of the residences along theroute. Therefore, it is not considered that these impacts would result in asignificant effect.

5.5.8 Similarly, the vibration levels predicted for the temporary constructionrailway are considered to be below the threshold of low probability ofadverse comment and therefore no groundborne vibration effects havebeen identified from the operation of the temporary construction railway.

Figure 5.3 An example of a temporary construction railway at thebottom of a shaft


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5.6 Socio-economics

5.6.1 Significant socio-economics effects could potentially arise at a project widelevel from both construction related activities and the projects operation.Likely effects would broadly relate to employment generation and othereconomic effects, and general amenity and public health effects.

5.6.2 The preliminary findings of the assessment of project wide effects arereported in the Preliminary Environmental Information Report. Thisassessment has been undertaken using publicly available baseline datasources where possible, such as construction industry regionalemployment figures, barge operator numbers and data regardingrecreational river use. The scheme design continues to evolve, andtherefore preliminary findings on effects (including employment andeconomic effects) have been estimated based on project information, bestpractice guidance, including English Partnerships Additionality Guidancefor calculating downstream economic effects, as well as professional

judgement. The completed assessment, including economic modelling, ofeffects will be reported in the Environmental Statement.

5.6.3 During construction, the preliminarily findings are that there could besignificant beneficial economic effects arising from generation of direct,indirect and induced construction related employment. Beneficial effectsmay also arise from potential barge operation employment and stimulationof the freight by water industry (depending on the number of river bargetrips that may be required; and which is still subject to confirmation).There may potentially be beneficial effects arising from tunnel segmentmanufacturing related employment and improvement in construction and

manufacturing skills workforce skill levels, though it is considered unlikelythat these effects would be significant at a project wide level. Finally,adverse effects in relation to recreation and leisure may occur as a resultof construction activities at a number of specific sites, though it isconcluded that these are unlikely to be significant at a project wide level.

5.6.4 For the operational phase of the project, the preliminarily findings are thatthere could be a significant beneficial effect on river-related recreationalopportunities as a result of improvement in river water quality. There mayalso be potential beneficial effects arising from the generation ofoperational employment opportunities and a net increase in public amenityspace, although it is also considered unlikely that these effects would besignificant at a project wide level.

5.6.5 Consideration of public health-related project wide socio-economic effectswill be incorporated within a detailed Health Impact Assessment, andconsideration of these findings will be presented in the EnvironmentalStatement.

5.6.6 The preliminary findings of the assessment conclude that there areunlikely to be significant adverse socio-economic effects at a project widelevel which would require mitigation.


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5.7 Transport (road and river transport)

5.7.1 Baseline data has been surveyed for traffic and pedestrian movements,highway operation and parking usage during 2011.

5.7.2 Additional data encompassing accident, traffic flow, pedestrian flow, river

usage and highway operation has been obtained from sources such asTransport for London.

5.7.3 Initial construction related vehicle routing has been carried out todetermine volume of vehicles on proposed construction routes and routesfor workers to site. The routes have been determined based onprofessional judgement and through borough and Transport for Londonconsultation.

5.7.4 At this stage the assessment of effects has been made using preliminaryinformation and professional judgement. Further modelling andassessment will be undertaken and reported in the Environmental

Statement. During construction, it is considered that the number of heavygoods vehicle movements would be low compared to existing Londonwide transport levels and overall is expected to have negligible to minoradverse effect on road network operation and delay. Figure 5.4 showsone of the strategic vehicle routes through London. Similarly it isconsidered that the numbers of construction workers using the publictransport network would be low compared to existing London wide publictransport usage and it is thus expected to have a negligible effect on thewider public transport network. Effects on the pedestrian and cyclistamenity and safety overall are expected to be negligible. The overalleffect on river passenger services is expected to be negligible.

5.7.5 During the operational phase there would be very occasional vehicle tripsto and from the sites for maintenance activities but these would have anegligible effect on the London wide transport network.


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Figure 5.4 View along Victoria Embankment (A3211), part of thestrategic vehicle route through London

5.8 Water resources groundwater

5.8.1 Information about groundwater conditions has been gathered from existinginformation sources and ground investigation surveys undertaken for theproject. Figure 5.5 shows an overwater borehole rig in the River Thamesfrom one the project surveys. The Thames Tunnel would pass through

different layers of geology from London Clay in the west, through theLambeth Group in the centre and into Thanet Sand/Chalk in the east ofthe proposed tunnel route. Each layer of geology has a different ability tohold water. Layers of geology which can hold water are known as aquifers.The Thanet Sand/Chalk is known as the lower aquifer. The lower aquiferis a high value receptor and sites licensed to remove water (licensedabstractions) from this aquifer are very high value receptors. Thesignificance of project wide tunnelling construction and operational effectsare considered as part of this preliminary assessment.

5.8.2 Four potential construction effects on the lower aquifer and licensedabstractions have been identified in the preliminary assessment. Theseare the: movement and mixing of groundwater (by the creation of apathway along the tunnel route); deterioration in groundwater quality;physical disturbance; and physical obstruction to groundwater flow. Thesensitivity of the effects at this stage have been assessed as ranging fromminor adverse to major adverse effects. Major adverse effects are mostlikely to occur in the eastern part of the tunnel route where the tunnelwould be in the lower aquifer.


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5.8.3 The preliminary assessment has identified that obstruction to groundwaterflow, seepage to and from the tunnel and the movement and mixing ofcontaminated groundwater along the tunnel route are the potential effectswhich could occur once the Thames Tunnel is operational. The effects ongroundwater flow and seepage are considered to be negligible. However,

the creation of a pathway for contaminated groundwater formed by thetunnel could have minor to major effects on groundwater quality,depending on the section of the Thames Tunnel.

5.8.4 Further assessment work is being undertaken for the EnvironmentalStatement, so that effects identified by the Preliminary EnvironmentalInformation Report can be better understood and minimised throughongoing design and mitigation.

5.8.5 Monitoring of groundwater levels and quality will be continuing throughoutthe construction and operational phases of the tunnel.

Figure 5.5 An overwater borehole rig in the River Thames

5.9 Water resources surface water

5.9.1 The primary objective of the Thames Tunnel is to capture discharges fromcombined sewer overflows into the River Thames. This would in turn meetthe requirements of the European Urban Waste Water Treatment Directiveand the related UK Regulations. The assessment considers the effects

that the operation of the Thames Tunnel would have on the water qualityof the River Thames as a whole and has been guided by the requirementsof the Water Framework Directive, which sets standards for water quality.

5.9.2 Existing water quality within the River Thames has been establishedthrough a review of monitoring data from the Environment Agency. Thevolume of sewage discharged into the whole of the River Thames fromcombined sewer overflows has been calculated using computer modelling.Modelling has also been used to assess the effects that discharges haveon dissolved oxygen.


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5.9.3 The River Thames is categorised into three geographical sections by theEnvironment Agency; the Thames Upper, Thames Middle, and ThamesLower. The modelling used to assess water quality covers the ThamesUpper and Thames Middle. Water quality in the Thames Upper andThames Middle sections are currently classified under the Water

Framework Directive as moderate potential with a target to reach goodpotential by 2027. The levels of dissolved oxygen in the River Thamescurrently fail the dissolved oxygen standards developed for the whole ofthe River Thames. This means the Thames is unable to meet the targetfor good status set by the Water Framework Directive for 2027 in theabsence of measures to improve water quality.

5.9.4 Currently, a total volume of 39,667,000 m3 of sewage is discharged intothe River Thames every year through the combined sewer overflows. Thisis discharged over a duration of 5,567 hours a year and includesapproximately 10,000 tonnes of sewage derived litter. River users are at

risk of being exposed to pathogens for up to two thirds of a year as aresult of the discharges. The river is used by a range of users, such asthe canoeists shown in Figure 5.6.

5.9.5 It is considered that there would be no project wide effects on the qualityof the Thames during the construction of the Thames Tunnel. Site specificeffects during construction are considered in the site sections of the non-technical summary.

5.9.6 Modelling has shown that the volume of sewage being discharged fromthe combined sewer overflows into the River Thames would be reduced byapproximately 55% with the operation of the Lee Tunnel and upgrades to

sewage treatment works that are underway. Although this is a largereduction, the volume of sewage that would still be discharged fromcombined sewer overflows (without the Thames Tunnel) would mean thatwater would still fail standards for dissolved oxygen and water quality. Thiswould continue to present a significant health risk to river users and meansewage derived litter is still discharged.

5.9.7 The assessment has taken into consideration these reductions incombined sewer overflows discharges from the Lee Tunnel and sewagetreatment work upgrades. Once the Thames Tunnel is in operation thescheme would further reduce the number of discharges from combinedsewer overflows by 87%. This reduction would be a major beneficial effect

on water quality and would allow compliance with the Urban Waste WaterTreatment Directive and contribute to compliance with the WaterFramework Directive objectives. The number of risk days for river usersbeing exposed to pathogens would be reduced by approximately 90%. Inaddition, the tonnage of sewage derived litter can be expected to bereduced by 87% from 4,500 tonnes (the volume that would still bedischarged with the Lee Tunnel and sewage treatment works upgrades) to585 tonnes per year.

5.9.8 Further water quality modelling is underway to determine the beneficialeffects from the Thames Tunnel and the effects climate change. These

results will be reported in the Environmental Statement.


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Figure 5.6 Canoeists on the River Thames

5.10 Water resources flood risk

5.10.1 The potential impact on flood risk throughout the Thames Tideway is beingassessed using all available data from the Environment Agency and LocalAuthorities. Additional computer modelling is also being completed todetermine any changes in extreme water levels due to the cumulativevolume of proposed development within the Tideway. Site specificphysical modelling is also being completed in areas where impacts couldbe more significant.

5.10.2 The modelling work will provide full details of any changes to extreme tidalwater levels, sediment movement patterns, and localised scour anddeposition trends throughout the Tideway. Further assessments are beingcompleted to assess flooding from watercourses, groundwater sourcesand drainage systems.

5.10.3 The initial modelling results suggest that the projects impact on extremeflood levels in the Tideway is likely to be minimal. The results show thatminor changes in peak water levels are likely to be experiencedthroughout the Tideway; minor increases in level typically occur in thelower reaches of the Tideway and minor reductions typically occur in theupper reaches. Further modelling work is being undertaken to confirm thatflood risk impacts are negligible.

5.10.4 If necessary, appropriate mitigation measures would be included within thedetailed site design to provide mitigation for any adverse impactsidentified. The foreshore sites would provide an equivalent level of flooddefence to the existing situation, but the design would include provision forthe defences to be raised in the future, if required. The new flooddefences which are constructed would reduce the risk of a defence breachor failure occurring at that specific location.

5.10.5 Surface water run-off would be restricted to ensure there is no increase inflood risk to the surrounding area, in line with national planning policystatement requirements.


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5.11 Further information

5.11.1 Further information regarding preliminary findings of the project wideassessment can be found in Volume 6 of the Preliminary EnvironmentalInformation Report.

Peir Nts Sections 1-5

Documents

Transcript of Peir Nts Sections 1-5