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8.66 Slurry Tunnel Boring Machine (TBM) and Treatment Plant: Environmental Appraisal

T010021

January 2017

Silvertown Tunnel

Slurry Tunnel Boring Machine (TBM) and Treatment Plant: Environmental Appraisal

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Silvertown Tunnel

Slurry Tunnel Boring Machine (TBM) and

Treatment Plant: Environmental Appraisal

Document Reference: XXXXXXXX-XXX-XXX-XX-XX-XX-XXXX

Author: Transport for London

Rev. Date Approved By Signature Description

0 27/01/2016 David Rowe (TfL Lead Sponsor)

For Deadline 3

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Contents List of Abbreviations ................................................................................................ 6

Glossary of Terms .................................................................................................... 8

1. INTRODUCTION ......................................................................................... 13

1.1 Introduction ................................................................................................. 13

1.2 TBM Selection Process ............................................................................... 14

2. Detailed Description of the Slurry TBM Methodology ............................ 15

2.1 Slurry TBM Principles .................................................................................. 15

2.2 Underground Operations ............................................................................. 15

2.3 Above Ground Operations .......................................................................... 15

2.4 Slurry Treatment Plant Processes ............................................................... 19

2.5 Slurry Treatment Plant Layout ..................................................................... 20

2.6 Construction, Operation, and Decommissioning ......................................... 22

3. Environmental Appraisal .......................................................................... 28

3.1 Scoping ....................................................................................................... 28

3.2 Air Quality.................................................................................................... 34

3.3 Noise and Vibration ..................................................................................... 36

3.4 Townscape and Visual Amenity .................................................................. 52

4. Conclusions ............................................................................................... 54

Appendix A. Silvertown Works Area Worksite Layout Stage 1 STP & PCC Segment Plant Option [STWTN-ATK-GEN-XXXX-SK-Z-0273] ............................. 55

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List of Tables

Table 2-1 The required material resources for the Scheme, STP and PCC segment manufacturing plant .................................................................................................. 23

Table 2-2 The waste arsing for the Scheme, and additional waste arising from proposed STP and PCC segment manufacturing plant ............................................ 25

Table 2-3 Envisaged additional HGV movements required for construction, operation and decommissioning of the STP ............................................................................. 27

Table 3-1 ES Chapters unaffected by the introduction of Slurry TBM and STP to the Scheme Description ................................................................................................. 29

Table 3-2 Noise and vibration sensitive receptors .................................................... 38

Table 3-3 External Plant used during STP Operation............................................... 41

Table 3-4 Predicted Construction Noise Levels with STP During - Daytime Period . 42

Table 3-5 Predicted Construction Noise Levels with STP – Night time period ......... 44

Table 3-6 Predicted Construction HGV Noise Levels with the proposed STP .......... 45

Table 3-7 Predicted Construction Noise Levels with Proposed STP and the Segment Manufacturing Plant - Daytime ................................................................................. 47

Table 3-8 Predicted Construction Noise Levels with Proposed STP and the Segment Manufacturing Plant – Night time ............................................................................. 48

Table 3-9 Predicted Construction HGV Noise Levels with Proposed STP and PCC Segment Manufacturing Plant .................................................................................. 50

List of Figures Figure 2-1 Excerpt of the layout of Silvertown Worksite inclusive of Slurry Treatment Plant and on-site Segment Manufacturing ............................................................... 18

Figure 2-2 Typical Schematic of a Slurry Treatment Plant ....................................... 21

Figure 3-1 Noise and vibration sensitive receptors locations ................................... 39

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List of Abbreviations

AADT Annual Average Daily Traffic

AQMP Air Quality Management Plan

CMS Construction Method Statement

CoCP Code of Construction Practice

DLR Docklands Light Railway

DMRB Design Manual for Roads and Bridges

EPB Earth Pressure Balance

ES Environmental Statement

GLA Greater London Authority

HGV Heavy Goods Vehicle

NRMM Non-Road Mobile Machinery

PCC Precast Concrete

SPG Supplementary Planning Guidance

SR Sensitive Receptor

STP Slurry Treatment Plant

TBM Tunnel Boring Machine

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TfL Transport for London

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Glossary of Terms

Annual Average Daily Traffic The total volume of vehicle traffic of a road for a year divided by 365 days.

Bentonite Bentonite is a highly expansive and naturally occurring clay material. Used during the tunnelling both as transport medium for excavated material in the slurry circuit and as a support medium for the tunnel face.

Code of Construction Practice The Code of Construction Practice contains a series of measures and standards of work to be applied to the construction of a project ensuring a consistent approach to the management of construction activities.

Construction Method Statement A document used to describe the envisaged construction processes, programme, arrangements of temporary worksites and logistics considerations associated with construction of the proposed Silvertown Tunnel Scheme.

Contractor The Contractor will be the construction entity through which the Project Company would deliver the design and construction of the Scheme and includes anyone who directly employs or engages construction workers or manages construction work, including sub-contractors, or any individual self-employed worker or business that carries out, manages or controls construction work.

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Cutter Head The rotating front face of a Tunnel Boring Machine (TBM) which physically mines the ground during TBM advancement.

Design Manual for Roads and Bridges The Design Manual for Roads and Bridges is a series of 15 volumes that provide standards, advice notes and other documents relating to the design, assessment, and operation of trunk roads, including motorways in the UK. This includes Volume 11 – Environmental Assessment.

Development Consent Order A Development Consent Order is the means of obtaining permission for developments categorised as Nationally Significant Infrastructure Projects.

Earth Pressure Balance (EPB) Tunnel Boring Machine

A type of tunnel boring machine used in soft ground. The machine uses the excavated material to balance the pressure at the tunnel face. Pressure is maintained in the cutter head by controlling the rate of extraction of spoil through the removal Archimedes screw and the advance rate of the machine.

Environmental Impact Assessment Environmental Impact Assessment is a key aspect of many large scale planning applications which identifies the potential environmental effects of a development project.

Environmental Statement An Environmental Statement is the written material submitted to the Secretary of State in fulfilment of the EIA regulations.

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Heavy Goods Vehicle (HGV) European Union term for any vehicle with a gross combination mass of over 3500kg.

Lime Milk A mixture of hydrated lime and water.

Non-Road Mobile Machinery Any mobile machine, item of transportable industrial equipment, or vehicle (with or without bodywork) that is: not intended for carrying passenger or goods on the road and is installed with a combustion engine, either an internal spark ignition petrol engine or a compression ignition diesel engine.

Pollution Prevention Guidelines Best practice guidelines set out by the Environment Agency to advise industry and public on legal responsibilities and good environmental practice.

Silvertown Tunnel Proposed new twin-bore road tunnels under the River Thames from the A1020 in Silvertown to the A102 on Greenwich Peninsula, East London.

Slurry A suspension of water, a clay mineral (called bentonite) and other additives which is used in a variety of ground-related construction purposes including ground support for bored pile and TBM tunnel construction.

Slurry Tunnel Boring Machine A form of soft ground closed face tunnel boring machine which is selected in certain types of ground containing sands and gravels, and where high groundwater pressures exists.

The chamber containing the TBM

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cutter head is filled with pressurised slurry which applies pressure to the excavation face. The slurry acts as a ground support and transport medium for the excavated material, which is continuously circulated between the TBM and a slurry treatment plant, where the excavated material is separated out for disposal or reuse.

Sulphuric Acid A strong acid made by oxidising solutions of sulphur dioxide and used in large quantities as an industrial reagent.

The Scheme The construction of a new bored tunnel with cut and cover sections at either end under the River Thames (the Silvertown Tunnel) between the Greenwich peninsula and Silvertown, as well as necessary alterations to the connecting road network and the introduction of user charging at both Silvertown and Blackwall tunnels.

Transport for London Transport for London is a local government body responsible for most aspects of the transport system in Greater London. Its role is to implement the transport strategy and to manage transport services across London.

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SUMMARY

S.1.1 This report presents an environmental appraisal to confirm that, should the Contractor of the Scheme elect to use a Slurry Tunnel Boring Machine (TBM) rather than an Earth Pressure Balance (EPB) TBM, as envisaged as most likely in the Construction Method Statement (APP-046), the environmental effects would fall within the parameters of the assessment reported in the Environmental Statement (APP-031).

S.1.2 The works to commission and decommission a Slurry TBM and Slurry Treatment Plant (STP), and the processes involved in the operation of a Slurry TBM and STP have been reviewed and appraised in the context of each environmental topic previously assessed in the Silvertown Tunnel Environmental Statement (APP-031).

S.1.3 Having carried out the appraisal, the Applicant has concluded that the use of a Slurry TBM and STP, falls within the parameters of the assessment reported in the Environmental Statement (APP-031).

S.1.4 The flexibility that TfL and its construction contractor require, as documented in this report, does not present such a wide range of materially different options such that each option in itself might constitute a different project for which consent (and an accompanying EIA) is required nor will it allow a scheme to be implemented which is materially different from that assessed in the EIA supporting the application.

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1. INTRODUCTION

1.1 Introduction

1.1.1 Transport for London (TfL) (‘The Applicant’) has submitted an application for Development Consent to the Planning Inspectorate for a new road tunnel linking the areas north and south of the River Thames between the Greenwich Peninsula and Silvertown, hereafter referred to as the Silvertown Tunnel (“the Scheme”). The Application is currently in the Examination Phase.

1.1.2 The Construction Method Statement (CMS) (APP-046) of the Silvertown Tunnel Scheme, on which the Environmental Impact Assessment was based, identified that the most likely methodology to be selected by the Contractor for construction of the bored tunnels would utilise an Earth Pressure Balance Tunnel Boring Machine (EPB TBM). However, as set out at paragraphs 4.4.36 and 5.1.9 of the CMS (APP-046), selection of the Tunnel Boring Machine (TBM) would depend on the Contactor’s views on how to best to overcome the variable ground conditions and meet programme requirements. This could result in an alternative choice to that of the envisaged EPB method, and, although unlikely, a Slurry TBM or multi-mode TBM may be selected.

1.1.3 A multi-mode TBM can operate at the tunnelling face in either slurry or EPB mode. Excavated material arisings conveyance for this type of TBM is by either the method envisaged in the Construction Method Statement (APP-046) or as is outlined in this report for a slurry TBM. As such, the mechanical differences between a multi-mode TBM and slurry TBM are not considered to change the environmental compliance statements made within this report. Hence, for clarity, there are no further specific references to a multi-mode TBM in this report.

1.1.4 Many aspects of constructing the bored tunnels using a Slurry TBM are similar to those of an EPB TBM. It is only the way in which tunnelling spoil is handled, conveyed, and prepared for removal from site that significantly differs, in that a Slurry Treatment Plant (STP) would be required. This plant and its processes are described in further detail in Section 2 of this report.

1.1.5 This report is intended to provide an environmental appraisal to demonstrate that the environmental impacts arising from the use of a Slurry TBM methodology would fall within the parameters of the assessment reported in the Environmental Statement (ES) (APP-031).

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1.2 TBM Selection Process

1.2.1 A description of the Scheme’s envisaged construction methodology is provided in the CMS, Section 1.3 page 19 (APP-046).

1.2.2 The process of selecting the TBM for construction of the Silvertown Tunnel Scheme would commence during the selection of contractors to undertake the construction of the project, with an order for the chosen TBM placed typically a year to eighteen months prior to commencement of bored tunnelling construction. The TBM selection process would be informed by the existing information about the ground conditions within the Order Limits as well as information obtained from further pre-construction surveys. These activities are described in Sections 3.6 and 3.7, page 39-40 of the CMS (APP-046), and would be controlled through the CoCP.

1.2.3 The principal consideration affecting the type of TBM selected is the nature of ground and groundwater conditions. Based on the baseline information gathered to date, as set out in Chapter 12 of the ES, the Silvertown Tunnel bored tunnel drives, in their locations in the CMS (APP-046), are anticipated to comprise variable ground conditions. Fully granular ground conditions (River Terrace deposits), mixed ground conditions (Woolwich Formation – Lambeth Beds), and over-consolidated stiff clay (London Clay) are all anticipated to be experienced during the bored tunnel construction.

1.2.4 The Contractor’s experience and expertise will inform the choice of TBM in this context. Whilst on balance an EPB TBM is thought by the Applicant to be most likely to be selected, it may be the case that a Slurry TBM is chosen.

1.2.5 An important process associated with the use of a Slurry TBM is the means by which the slurry, used to convey excavated material arisings away from the tunnel face, is produced, treated and managed. This report first provides an overview of how a Slurry TBM operates together with a description of the slurry treatment process and the activities likely to take place within a Slurry Treatment Plant (STP). The report then considers the environmental effects of these activities and whether these would fall within the parameters of the assessment reported in the ES (APP-031).

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2. Detailed Description of the Slurry TBM Methodology

2.1 Slurry TBM Principles

2.1.1 A Slurry TBM works on the principle that the ground to be tunnelled through in front of the cutter head is supported by bentonite slurry. Bentonite is a naturally occurring clay mineral used extensively in the construction industry. The mineral is mixed with water to form a slurry, which is supplied to the TBM by a delivery pipeline. The slurry is contained in the head of the TBM in a pressurised chamber that also contains the cutter head which is used to excavate the ground.

2.1.2 The slurry is further utilised to remove excavated material in suspension. The slurry is mixed with the excavated material by the rotating cutter head within the pressurised chamber and is then removed from the tunnel via a return pipeline in a closed piped network.

2.1.3 At the surface, the excavated material is removed from the slurry by a STP to prevent the slurry becoming too thick and losing its ability to hold material in suspension. The slurry is then conditioned and topped-up as necessary with fresh bentonite before being returned to the tunnel.

2.1.4 The principal differences between the above ground and below ground processes and activities associated with a Slurry TBM and an EPB TBM, are described below.

2.2 Underground Operations

2.2.1 The conveyor system in the tunnel and shaft used with an EPB TBM is replaced by a delivery and return pipeline system with a Slurry TBM.

2.3 Above Ground Operations

2.3.1 The principal differences between a Slurry and EPB TBM regime centre on the handling of excavated tunnel material and the need for a STP.

2.3.2 In order to assess the potential effects of selecting a Slurry TBM, a concept STP arrangement has been developed, on which this appraisal has been based.

2.3.3 The maximum anticipated ‘instantaneous’ advance rate of the TBM, is calculated to be 2.2m per hour which would generate about 600t/hr of

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excavated material. To accommodate this rate of advance, it is estimated that a slurry transfer and treatment plant of 2,200m3/hr capacity would be required. The overall area required for the plant and associated facilities is estimated at 3,750m2.

Site Layout

2.3.4 Figure 2-1 below provides an extract of the indicative site layout should the Contractor of the Scheme elect to use a Slurry TBM and STP. The site layout also includes a Precast Concrete (PCC) segment manufacturing plant which is considered fully in a standalone report (8.65 Environmental Appraisal of PCC Segment Manufacturing Plant). The full layout drawing is provided in Appendix A (STWTN-ATK-GEN-XXXX-SK-Z-0285 - Silvertown Works Area Highlight TBM STP Plant). This has modified the envisaged ‘Silvertown Worksite Layout’ Drawings (ST150030-ATK-ZZZ-ZZ-DR-CE-3141) presented in Appendix B of the CMS (APP-046).

2.3.5 The site layout currently envisaged in the CMS would be reconfigured to move the segment storage area east of the drive shaft and to locate the site batching plant and the new STP to the west of the drive shaft. The STP included in the original DCO submission would remain in its original location as it is still required to service the Scheme’s bored piling works.

2.3.6 The establishment of a STP to support a Slurry TBM would take up more space within the worksite in comparison to an EPB TBM. This would require the Contractor to adopt a different approach to management of the site storage space and would form one consideration in the overall TBM selection process.

2.3.7 It can be seen from Figure 2-1 and the description of the process below that, if the contractor chooses to use Slurry TBM and STP, either by itself or with a PCC Segment Manufacturing Plant, the revised site layout will reduce the space available for temporary storage on the site. However, it does not impact on the area available for spoil storage and although it would limit the contractor’s flexibility when materials are delivered to and from site, it is not considered to impact on the Scheme’s HGV movements

2.3.8 The quantity of surface conveyors required on the site would be reduced as the excavated material would be transferred from the tunnelling face to the treatment plant via the closed piped network as described in paragraph 2.1.2. Excavated material from the treatment plant would be transported to the various stockpiling areas as described in the CMS (APP-046).

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2.3.9 The principal units in the STP would be housed in a portal frame building of approximately 750m2 and up to 16m in height. In addition to this enclosed facility, there is an additional area of 3,000m2 in which various storage tanks and silos for the STP would be located as shown in Figure 2-2.

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Figure 2-1 Extract of the layout of Silvertown Worksite inclusive of Slurry Treatment Plant and PCC Segment Manufacturing

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2.4 Slurry Treatment Plant Processes

2.4.1 The STP can be considered as a series of six processes that will take place within the 3750m2 area described above:

• Separation of tunnel spoil from the slurry;

• Dewatering;

• Preparation of fresh slurry;

• Storage of cleaned slurry;

• Slurry conditioning; and

• Water management.

Separation

2.4.2 The tunnel excavated material is removed from the slurry in the STP through a sequential series of processes:

Scalping

2.4.3 The slurry holding the tunnel excavated material is delivered to a scalping unit. This unit removes all material greater than 6mm in size. This is done by using a rotating screen. The material larger than 6mm is transferred to the spoil classification and storage areas shown in Figure 2-1 by conveyor. The remaining slurry is pumped to the de-sanding unit.

Desanding

2.4.4 The de-sanding unit comprises a number of 650mm diameter cyclones. These remove material in the 70μm to 6mm size range. The separated material is transferred to the dewatering unit and the remaining slurry is pumped to the de-silting unit.

Desilting

2.4.5 The de-silting unit consists of a number of 250mm cyclones. These remove material in the 40μm to 70μm size range. The separated material is transferred to the dewatering unit and the remaining slurry is stored in tanks for reconditioning/reuse in the continuing tunnel boring drive.

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Dewatering

2.4.6 The dewatering unit removes excess water from the material arising from the de-sanding and de-silting processes, allowing it to be efficiently transported for disposal. The unit comprises a number of vibrating screens. The screens have grids with 0.5mm or 0.6mm openings. The screens also have filtering sides for larger material, up to 1.5mm openings. Excess water will be recycled within the STP processes.

Preparation of Fresh Slurry

2.4.7 The slurry preparation unit, which forms part of the overall STP, comprises bentonite silos, weighing equipment, mixing equipment, controls, and a preparation tank.

Storage of Slurry

2.4.8 The cleaned slurry and the fresh slurry are stored within the plant and then mixed in proportions depending on the properties (density and viscosity) required at the tunnel face.

Slurry Conditioning

2.4.9 The condition of the residual slurry (after spoil separation) is monitored. The build-up of sub-silt size material (mud) in the slurry means that it requires supplementing with fresh slurry on a regular basis. The slurry with this excess mud is treated within the STP through the use of filter presses. This presses are located in the portal frame building with the separated dried cake sent to spoil storage area. The filtrate water is reused. The process involves silos, pumps, presses and control systems. Prior to treatment slurry would be dosed with lime milk to aid the process.

Water Management

2.4.10 Storage tanks of 400m3 capacity are required for both fresh water and filtrate water. As lime milk is used to dose the filtrate water, the plant would have a facility to neutralise this by injecting sulphuric acid. Storage, dosing and monitoring equipment within the STP is required for this purpose.

2.5 Slurry Treatment Plant Layout

2.5.1 An indicative layout of a STP is included in Figure 2-2 overleaf.

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Figure 2-2 Typical Schematic of a Slurry Treatment Plant

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2.6 Construction, Operation, and Decommissioning

Construction of STP

2.6.1 If the Contractor elects to operate a Slurry TBM, the associated construction of the supporting infrastructure, namely the STP, would require a small number of additional transport movements on the road network, in addition to those assessed in the Environmental Statement (ES) as described in Table 2-3.

2.6.2 Similar construction plant to that which has already been assessed in the ES (APP-031) is envisaged to be required for the construction of the STP. The processes involved in the plants’ construction (site clearance, foundation construction, steel erection etc.) are already required for the construction of the previously assessed works.

2.6.3 The materials required to construct the STP are described in Table 2-1. They have also been combined with the materials required to construct the PCC segment manufacturing plant which is considered fully in the separate PCC segment manufacturing plant report (8.5: Environmental Appraisal of PCC Segment Manufacturing Plant) and compared to the overall materials forecast of the Scheme as presented in Chapter 13 (REP1-107).

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Table 2-1 The required material resources for the Scheme, STP and PCC segment manufacturing plant

Material Resources

Estimated Quantities (tonnes) STP PCC Segment

Manufacturing Plant1

The Scheme Total

Concrete materials 114 180 398,000 398,294 Fill materials including

granular fill 0 0 172,000 172,000

Tunnel segments 0 0 80,000 80,000 Highway / pavement material 0 0 30,000 30,000

Steel 120 440 17,000 17,560 Treatment Works

(silo/tanks/mechanical equipment)

220 0 0 220

Miscellaneous, highway concrete including kerbs

60 180 1,000 1,240

Total 698,000 699,314 % of additional construction material required for

proposed STP and PCC Segment Manufacturing Plant 0.19

Operation of STP

2.6.5 The purpose of the proposed STP process is to remove suspended/conveyed particles in the slurry, so that it can be recycled and reused within the excavation chamber of the TBM.

2.6.6 Bentonite and other environmentally acceptable additives would be used to assist in the formation of a stable slurry with the required specific gravity and viscosity. As described in paragraph 9.3.6 of the CoCP (REP2-046) ‘Polymers used for the TBM operation will be bio-degradable and non-hazardous to the water environment. Agreement with the Environment Agency will be sought prior to their use and any licences obtained (where necessary). Discharges which contain polymers will be tested to show that they are bio-degradable and low risk to the water environment’.

2.6.7 During the operation of the Slurry TBM and STP, additional offsite transport movements would be required to transport bentonite and other consumables (approximately 5,000 tonnes) to and from the worksite.

1 Inclusive of the materials required to enlarge the CMS Concrete Batching Plant.

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2.6.8 The volume of excavated material generated by the tunnelling process would not be significantly more in volume to the EPB TBM methodology (i.e. less than 1%) and would be transported offsite by the same means as assessed in the ES (APP-031).

2.6.9 Additional HGV movements are described in Table 2-3 below.

2.6.10 In the event of the TBM encountering contaminated land, the spoil arising from the slurry treatment process will be captured in the spoil classification area as set out in the CMS (APP-046). This spoil will be dealt with in the same manner as proposed in the CMS with no change in the number of HGV movements as a result.

2.6.11 At the end of the tunnel drive, the remaining waste water (in order of 1000m3 once all of the suspended spoil has been removed from the slurry), would managed in the same manner as envisaged in the CMS for the Scheme. This would not require transport off site, and thus, no additional HGV movements would be required. As stated in paragraph 9.3.6 of the CoCP (REP2- 027), the Contractor will adhere to the Environment Agency Pollution Prevention Guidelines and any remaining waste water will be filtered and tested prior to its disposal. If required, the Contractor will also apply for a Discharge Licence from the Environment Agency as stated in paragraph 9.3.7 of the CoCP (REP2- 027).

2.6.12 Where waste water is discharged to the existing drainage system the Contractor would ensure that the site drainage meets the effluent standards required by the sewerage undertaker, or Environment Agency, as appropriate, and would provide any other measures as may be required by the relevant person pursuant to the DCO. The relevant sections of BS 6031:2009 Code of Practice for Earthworks for the general control of site drainage would be followed, as described in paragraph 15.2.1 of the CoCP (REP2-027).

Decommissioning

2.6.13 If the Contractor elects to operate a Slurry TBM, the associated deconstruction and decommissioning of the supporting infrastructure, namely the STP, would require a small number of additional transport movements on the road network (Refer to Table 2-3).

2.6.14 The waste arisings from the proposed STP are described in Table 2-2. They have also been combined with the waste arisings from the PCC segment

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manufacturing plant and compared to the overall waste forecast of the Scheme as presented in Chapter 13 (REP1-107).

Table 2-2 The waste arsing for the Scheme, and additional waste arising from proposed STP and PCC segment manufacturing plant

Waste

Estimated Quantities (tonnes)

STP PCC Segment Manufacturing

Plant 2 The Scheme Total

Bricks 0 0 9,444 9,444 Mixed waste 0 0 24 24

Wood 0 0 255 255 Gypsum 0 0 330 330 Metals 120 180 12,914 13,214 Glass 0 0 30 30

Concrete 114 440 44,904 45,458 Mix concrete,

bricks and tiles

0 0 5,293 5,293

Hazardous demolition

waste 0 0 524 524

Inert soils and stones

0 0 56,319 56,319

Grout 0 0 1,274 1,274 Soils and

stones containing dangerous

substances*

0 0 194,965 194,965

Bituminous mixtures

0 0 508 508

Packaging 0 0 126 126 Plastic 0 0 52 52

Topsoil (non-hazardous) 0 0 740,005 740,005

Other segregated C&D waste (including

vegetation)

2803 180 13,584 14,044

Dredgings 0 0 94,500 94,500 Total 514 800 1,175,051 1,176,365

2 Inclusive of the materials required to enlarge the CMS Concrete Batching Plant 3 Figure inclusive of Treatment Works plant (see Table 2-1)

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Waste

Estimated Quantities (tonnes)

STP PCC Segment Manufacturing

Plant 2 The Scheme Total

% of additional waste arisings generated from the proposed STP and PCC Segment

Manufacturing Plant 0.1

2.6.15 No additional construction plant is envisaged to be required for the decommissioning of the STP that has not already been assessed in the ES (APP-031).

Transport Commitments

2.6.16 The envisaged additional HGV movements are listed in Table 2-3 and would not impact the river transport commitments of the Scheme as per the CMS (APP-046). They have also been combined with the additional HGV movements required for the PCC Segment Manufacturing Plant to show the overall percentage increase of 3.2%.

2.6.17 The Construction Site River Strategy (CSRS) will demonstrate how the Contractor would meet the commitments set out in paragraph 3.2.3 of the CoCP (REP2-027). This includes transporting at least 55% (following Mayoral review) by weight of all materials associated with the Scheme by River, and 100% of suitable excavated material out by River.

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Table 2-3 Envisaged additional HGV movements required for construction, operation and decommissioning of the STP

Works Description

HGV movements Envisaged Point of

access/egress to highway network4

Start Date End Date

Works duration

(Calendar Days)

Transport by River

Transport by Road

SUBTOTAL

Establishment of the STP facility - 60 60 Access Point 3 12/05/2020 03/12/2020 205

Operation of the STP facility

- 750 750 Access Point 3 04/12/2020 18/11/2021 350

Decommissioning of the facility

- 60 60 Access Point 3 19/11/2021 19/02/2022 92

TOTAL 870

% Additional HGV Movements for the construction and operation of the proposed

slurry plant compared to CMS 1.5

TOTAL (including PCC Segment Manufacturing Plant) 1890

% Additional HGV Movements compared to CMS (including PCC Segment Manufacturing

Plant) 3.2

4 See Drawing STWTN-ATK-GEN-XXXX-SK-Z-0273 in Appendix A of this report.

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3. Environmental Appraisal

3.1 Scoping

3.1.1 Table 3-1 sets out the chapter topics that would be unaffected if the Contractor were to select a Slurry TBM and STP. These topics have therefore been scoped out of further detailed appraisal, i.e. there are considered to be no potential likely significant environmental effects beyond those assessed in the ES (APP-031).

3.1.2 A more detailed environmental appraisal has been undertaken for the Air Quality, Noise and Vibration and Townscape and Visual topics in Sections 3.2 to 3.5 of this report.

3.1.3 Where appropriate the combined effects of both the Slurry TBM and STP and the PCC Segment Manufacturing Plant have also been considered to demonstrate that if both options were selected they would still fall within the parameters of the assessment in the ES (APP-031).

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Table 3-1 ES Chapters unaffected by the introduction of Slurry TBM and STP to the Scheme Description

ES Chapter Number PINS Reference ES Chapter Heading Likely effect of the Slurry TBM and STP

7 APP-031 Community and Private Assets The proposed Slurry TBM and STP and the proposed PCC Segment Manufacturing Plant would be within the Order Limit boundary as assessed in the ES (APP-031) and as such there would be no change in construction impacts in relation to land take, severance, amenity and socio-economic issues.

8 REP1-101 Cultural Heritage and Archaeology

The envisaged construction footprint would not differ if the Contractor elects to utilise a Slurry TBM and STP or to operate a PCC Segment Manufacturing Plant, all works would take place within the Order Limits. In any case, if unknown archaeological remains of national importance are identified during any works associated with the Scheme (including the proposed STP), appropriate procedures are in place for the identification and treatment of such assets as set out in the CoCP.

On this basis, it can be concluded that the findings of Chapter 8 would remain as reported and the use of a Slurry TBM and STP in isolation or in combination with the PCC Segment Manufacturing Plant would fall within the parameters of the assessment in the ES (REP1-101).

9 APP-031 Terrestrial Ecology The proposed STP and PCC Segment Manufacturing Plant would be constructed, operated, and decommissioned within the temporary land take already considered for ecological purposes within the Order Limits.

Noise and Vibration levels associated with the Slurry TBM and STP are assessed in Section 3.2 of this report and are not considered to be significant either in isolation or when combined with the operation of the PCC Segment Manufacturing Plant. Therefore, noise disturbance impacts of using a Slurry TBM and STP together with the operation of the PCC Segment Manufacturing Plant upon ecological receptors would fall within the parameters of those

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ES Chapter

Number PINS Reference ES Chapter Heading Likely effect of the Slurry TBM and STP

presented in Chapter 9 the ES (APP-031).

10 REP1-103 Marine Ecology There would be no impact on the marine environment as a result of the use of the Slurry TBM and STP and the operation of the PCC Segment Manufacturing Plant. The construction footprint would be on land, and there would be no changes to barge movements compared to the CMS. There is not intended to be any uncontrolled discharge to the river.

As stated in paragraph 9.3.6 of the CoCP (REP2- 027), the Contractor will adhere to the Environment Agency Pollution Prevention Guidelines and any remaining waste water will be filtered and tested prior to its disposal. If required, the Contractor will also apply for a Discharge Licence from the Environment Agency as stated in paragraph 9.3.7 of the CoCP (REP2- 027).

On this basis, it can be concluded that the findings of Chapter 10 would remain as reported and the use of a Slurry TBM and STP both in isolation or when combined with the PCC Segment Manufacturing Plant would fall within the parameters of the assessment in the ES (REP1-103).

11 APP-031 Effects on all Travellers There would be a minor increase in HGV movements during construction and decommissioning compared to the CMS as shown in Table 2-3. However, the increase would be insignificant compared to the HGV movements already assessed in the CMS. The largest potential increase in Annual Average Daily Traffic movements (AADT) associated with the construction of the proposed STP would be less than 2 additional AADT HGV movements at the peak of construction in 2021 and less than 5 additional AADT HGV movements when combined with the PCC Segment Manufacturing Plant HGV movements.

On this basis, it can be concluded that the findings of Chapter 11 would remain as reported and the use of a Slurry TBM and STP both in isolation or when combined with the PCC Segment Manufacturing Plant would fall within

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the parameters of the ES (APP-031).

12 REP1-105 Geology, Soils, and Hydrogeology

The footprint of the proposed STP and PCC Segment Manufacturing Plant would be within the Order Limits as assessed in the ES (REP1-105). Approaches and mitigation to avoid and limit potentially adverse contamination impacts are discussed in Section 12.5 of Chapter 12 of the ES, and in Section 9.2 of the CoCP. They apply to the Scheme in general terms, and would also apply to the use of the Slurry TBM and STP and PCC Segment Manufacturing Plant.

Slurry TBMs are used in sensitive aquifers where groundwater resource is an important factor, as such, existing groundwater controls measures already in place for the EPB method during Scheme construction would suffice for the Slurry TBM. These are described in Section 9.3 of the CoCP.

On this basis, it can be concluded that the findings of Chapter 12 would remain as reported and the use of a slurry TBM and STP in isolation or when combined with the PCC Segment Manufacturing Plant would fall within the parameters of the assessment in the ES (REP1-105).

13 REP1-107 Material Resources and Waste As stated in Section 2.7, if the Contractor chooses to operate a Slurry TBM, an additional 5000 tonnes of bentonite would be required to refresh the slurry circulating around the closed system, compared to the volume of bentonite assumed in the CMS for the EPB TBM.

However, it should be noted that the additional bentonite required for the slurry TBM technique would be combined with the excavated waste material from the bored tunnel construction, and would represent an increase in arisings of less than 1% which is not considered significant.

All material uses and waste arisings as a result of the slurry TBM and STP and

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ES Chapter

Number PINS Reference ES Chapter Heading Likely effect of the Slurry TBM and STP

the PCC Segment Manufacturing Plant are considered in Tables 2-1 and 2-2. They represent a combined increase of less than 1% of the Scheme totals included in the CMS.

On this basis, it can be concluded that the findings of Chapter 13 would remain as reported and the use of a slurry TBM and STP would fall within the parameters of the ES (REP1-107).

16 REP1-109 Surface Water and Flood Risk As set out in paragraph 9.3.6 the CoCP (REP2- 027), prior to commencement of construction, the Contractor will put in place pollution and prevention control measures across the Scheme and adhere to the Environment Agency Pollution Prevention Guidelines. These measures would apply equally to the proposed use of a slurry TBM and STP and the operation of the PCC Segment Manufacturing Plant.

Where waste water is discharged from either the proposed STP or PCC Segment Manufacturing Plant into the existing drainage system the Contractor would ensure that the site drainage meets the effluent standards required by the sewerage undertaker, or Environment Agency, as appropriate, and would provide any other measures as may be required by the relevant person pursuant to the DCO.

Where required the Contactor would also apply for a Discharge Licence from the Environment Agency as stated in paragraph 9.3.7 of the CoCP (REP2- 027).

With these controls in place, the construction, operation, and decommissioning of the proposed STP and use of a slurry TBM or combined with the PCC Segment Manufacturing Plant would not give rise to surface water quality impacts significantly in excess of that produced by the Scheme. Therefore, the findings of Chapter 16 would remain as reported and the use of a slurry TBM

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and STP would fall within the parameters of the assessment in the ES (REP1-109).

17 APP-031 Cumulative and Synergistic Effects

The nature and scale of the proposed STP, or use of the slurry TBM are such that it is unlikely that it would have any cumulative or synergistic effects not already assessed in Chapter 17 of the ES (APP-031).

On this basis, it can be concluded that the findings of Chapter 17 would remain as reported and the combined use of a STP and segment manufacturing plant would fall within the parameters of the ES (APP-031).

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3.1.4 A more detailed environmental appraisal has been undertaken for the Air Quality, Noise and Vibration, and Townscape and Visual Amenity topics in the Sections below.

3.2 Air Quality

3.2.1 As described in Chapter 6 of the ES (AS-022), construction impacts of the Scheme are focused on construction dust, emissions from non-road mobile machinery (NRMM), and emissions from construction vehicles (road and barge).

3.2.2 Potential effects would be associated with:

• dust nuisance from the construction of the STP;

• potential fugitive dust emissions from excavated material that is extracted from the slurry and transferred to stock piles/hoppers, dust may be created as material dries or is transferred to HGVs and barges for disposal or reuse; and

• increased airborne emissions as a result of construction and decommissioning vehicles associated with the STP, i.e. additional HGVs movements.

Dust

3.2.3 The full construction dust assessment is presented in Appendix 6A Construction Dust Assessment of the ES (APP-049) and has been conducted in line with Greater London Authority (GLA) Supplementary Planning Guidance (SPG) on the Control of Dust and Emissions from Construction and Demolition. The assessment concludes that after Scheme-specific mitigation has been implemented, the residual effects of all construction dust activities would not be significant, in accordance with the GLA SPG guidance.

3.2.4 It should be noted that, if the Slurry TBM and STP option is selected by the Contractor, potential dust impacts would be less than the EPB option due to the closed piping system reducing the extent of conveyors. The operation of the slurry TBM and the construction and decommissioning of the proposed STP has also been considered in relation to the GLA SPG guidance and would not give rise to significant construction dust effects due to the extensive mitigation measures already included in Chapter 5 of the CoCP (REP2- 027) to control dust emissions. Mitigation measures which would limit any potential dust from the STP operations, include, for example:

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• Fully enclosing the site or for specific operations where there is a high potential for dust production and the site is active for an extensive period;

• Use water as dust suppressant where applicable; and

• Cover, seed or fence stockpiles to prevent wind whipping.

3.2.5 As outlined in the CoCP (REP2-027), the Contractor’s Air Quality Management Plan (AQMP), would, where appropriate, include provision for buildings to be soft stripped before demolition (retaining walls and windows in the rest of the building where possible, to provide a screen against dust), demolished using water suppression and deconstructed using manual or mechanical means rather than explosive blasting. These measures, and others outlined in the AQMP, would be able to be implemented during the demolition of the STP following the completion of the tunnelling works.

Emissions from non-road mobile machinery (NRMM)

3.2.6 Paragraph 6.6.9 of the ES (AS-022) states that although NRMM emissions are inevitable during construction, implementing GLA SPG guidance and the measures included in the CoCP, the impacts at sensitive receptors would not be significant.

3.2.7 Similar construction plant to that already been assessed in the ES (APP-031) is envisaged to be required for the construction of the STP. The processes involved in the plants construction (site clearance, foundation construction, steel erection etc.) are already required for the construction of the previously assessed works.

3.2.8 In any case, any NRMM associated with the STP would be subject to the same mitigation as outlined in Table 5-1, Section 5.3 of the CoCP (REP2-027), therefore, it is considered that there would be no material difference from the results presented in the ES (AS-022) arising from the construction of the STP.

Emissions from construction vehicles (road and barge)

3.2.9 The STP works (and operation thereof) would coincide with the peak construction year (2021). Additional HGV movements are presented in Table 2-3 of this report.

3.2.10 The estimated number of movements has been converted to Annual Average Daily Traffic (AADT) movements and added to the number of HGV

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movements associated with the Scheme to determine the daily traffic flows on a given link resulting from the use of Slurry TBM and STP with the Scheme. As the additional maximum AADT movements are approximately 2 for the Slurry TBM option and 5 when combined with the increased HGV movements from the PCC segment manufacturing plant, the overall maximum AADT HDV movements would still be below the DMRB threshold of a change of 200 AADT HDV movements which trigger the requirement for further assessment.

3.2.11 The additional HGVs required for the STP would not trigger an assessment of airborne emissions as a result of construction vehicles. Therefore, the impacts can be considered to be within the parameters of those presented in the ES (AS-022).

3.2.12 The number of barge movements and size of the barges for a slurry TBM and associated activities would also be the same as those using the EPB methodology.

3.2.13 On this basis, it can be concluded that the findings of Chapter 6 (AS-022) remain as reported and the use of the Slurry TBM and STP would fall within the parameters of the assessment in the ES (AS-022), i.e. HGV and barge movement have been screened out of further assessment as insignificant.

3.3 Noise and Vibration

3.3.1 The Slurry TBM and STP would necessitate the following noise generating activities to be considered within the scope of the construction phase assessment of the Scheme:

• STP; and,

• Additional HGV movements associated with the inclusion of the STP.

3.3.2 There is also a requirement to consider noise associated with a proposed PCC segment manufacturing plant within the Silvertown construction site. Whilst the specifics of the PCC segment manufacturing are considered in a separate report (8.65 Environmental Appraisal of PCC Segment Manufacturing Plant) is a potential for a combined effect to occur with the slurry treatment plant that requires consideration with regards to noise and vibration within this report.

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3.3.3 As such, in addition to the consideration of the Slurry TBM and STP noise, the following scenarios also require to be considered to conclude envisaged noise impacts:

• Impacts of both the STP and the PPC Segment Manufacturing Plant being used concurrently; and,

• Impacts of additional HGV movements associated with the inclusion of the proposed STP and the PPC Segment Manufacturing Plant.

3.3.4 It is envisaged that the Slurry TBM and STP would be required to operate on a 24hour basis and as such an assessment during both the daytime (07:00 to 19:00) and night-time periods (23:00 to 07:00) has been undertaken within the scope of this report. HGV movements associated with the additional plant would only occur during the daytime period (07:00 to 19:00) and have been assessed accordingly.

3.3.5 The STP and PCC segment manufacturing plant and activities would not be envisaged to give rise to any additional vibration effects at the closest sensitive receptors above those assessed and considered within Chapter 14 of the ES (APP-031). However, the nature of the segment mould equipment requires the controlled use of vibration generating plant to compact the concrete in the segment moulds. The practicalities of this activity require this vibration to be locally controlled by use of such measures as robust vibration isolation mounts/inertia blocks to reduce transfer of vibration on to the floor and surrounding processes. As such ground borne vibration effects of the PCC segment manufacturing plant would be mitigated by design measures inherent within the processes and therefore have not been deemed necessary to be assessed within the scope of this appraisal report.

3.3.6 For the reasons given below, it is also considered that the noise and vibration effects of a Slurry TBM would not differ from those of the EPB TBM and would not give rise to any additional noise and vibration effects to those assessed with Chapter 14 of the ES (APP-031). Therefore, the requirement for any further assessment of the Slurry TBM has been scoped out of this environmental appraisal.

Study Area

3.3.7 The sensitive receptors which may be affected by noise associated with the proposed STP are presented in Table 3-2 below, and also in Figure 3-1. It is noted that as the STP is proposed to be located within the Silvertown construction Site within the London Borough of Newham, sensitive receptors

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considered within the scope of this study have been limited to those presented within Figure 3-1 based upon distances from the construction site.

3.3.8 These sensitive receptors are the same as identified within the ES (APP-031) for the Scheme construction works assessment. For consistency between this report and the ES (APP-031), the same receptor ID numbers have been maintained.

Table 3-2 Noise and vibration sensitive receptors

Sensitive receptor Receptor ID OS coordinates

Ardennes House SR1 539840, 180867

120 Victoria Dock Road SR2 539885, 180848

Foster Court SR3 539917, 180845

Hoola Development SR4 539932, 180736

Alaska Apartments SR5 540107, 180744

Western Beach Apartments SR6 540086, 180453

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Figure 3-1 Noise and vibration sensitive receptors locations

Methodology

3.3.9 The method of assessing and calculating construction noise impacts has been maintained from the ES (APP-031), referencing the guidance contained in:

• British Standard 5228: 2009+A1: 2014 ‘Code of Practice for Noise and Vibration Control on Construction and Open Sites’ Part 1; and,

• International Standard ISO 9613, ‘Acoustics – Attenuation of Sound during Propagation Outdoors’.

3.3.10 As this is maintained from the ES, further elaboration of the methodology employed should be referenced therein, within section 14.3 of the Chapter 14 of the ES (APP-031).

3.3.11 Noise propagation calculations have been conducted in accordance with the identified methodologies using a proprietary computer based prediction

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program IMMI (produced by Wölfel Meßsysteme). The software package follows the procedures given in BS 5228 and ISO9613, and is widely used in the UK to predict noise for various types of environmental assessment.

3.3.12 All predicted noise levels are presented as façade levels and as such are inclusive of the appropriate 3dB correction from free field.

3.3.13 The following assumptions have been utilised in the noise model and assessment of the proposed STP:

• Internal reverberant sound pressure level of the plant would be no greater than 90 dB(A) as measured at an equivalent STP at Shieldhall Strategic Tunnel Site Slurry treatment works;

• The proposed plant building envelope sound reduction of 25 Rw has been assumed on both building structures. This is consistent with the lowest value of attenuation attributable to unlined industrial façade cladding systems;

• The principal noise generating plant would be housed in two buildings, each 25m x 15m in plan and some 16m high;

• All prediction assumptions embodied within the original ES (Appendix 14A Construction Noise (APP-071)) have been maintained;

• Concurrent operations (not directly related to the proposed STP within the Silvertown construction site have been considered as presented and discussed within Appendix 14 A Construction Noise of Chapter 14 of the ES (APP-071); and

• The external plant (outside of the main buildings) which would be used during the operation of the proposed STP and input into the noise model as external point sources is based on field measurements from the Shieldhall Strategic Tunnel Site Slurry treatment works, taken 7th December 2016.

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Table 3-3 External Plant used during STP Operation

Construction Plant Noise Source Reference

Sound Pressure Level dB LAeq (T) @1 metre

Bentonite mixer

Measurement at the Shieldhall Strategic Tunnel. Site Survey date: 7th December 2016

90.4

Pump units x4 90.8

Control and electrical building 60.5

Cyclone 89.3

Dosing pump 75.2

Lime milk emptying screw 89.8

Lime milk mixer/pump unit 91.9

Silos 70.9

Water/Slurry tanks 91.5

3.3.14 Changes in construction traffic noise impacts from those reported in the ES on the surrounding road network as a result of the proposed STP have also been considered within the scope of this report. Furthermore, a combined scenario has also been considered including HGVs associated with the PPC Segment Manufacturing Plant outlined.

3.3.15 Traffic noise during the construction phase of the Scheme has been calculated in accordance with the methodology for mobile plant along a defined haulage route, contained within BS5228. This is maintained from the main ES as detailed within Appendix 14 A Construction Noise (APP-071). For each considered link the predicted construction HGV noise levels (combined with the PPC Segment Manufacturing Plant) have been logarithmically combined with the prevailing baseline traffic noise levels calculated in the same way derived from the 2021 opening year traffic model.

3.3.16 Additional numbers of average daily HGV movements associated with both the proposed STP and the PCC segment manufacturing plant have been modelled along the same assumed HGV routes as presented in the CMS (APP-046).

3.3.17 Based upon this information, the inclusion of the proposed STP and the PPC Segment Manufacturing Plant would be expected to generate the following hourly flows:

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• An additional 3-4 Annual Average Week Day Traffic (AAWT) HGV movements per day for the STP; and

• An additional 3-4 AAWT HGV movements per day for the PCC segment manufacturing plant.

3.3.18 It has been assumed within the BS5228 calculations that the sound power level of a HGV under acceleration is 105.5 dB(A) as stipulated as a maximum permitted value in EC Directive 92/97/EC. This level has been corrected in accordance with BS 5228 to account for number of vehicles per hour and speed. This methodology was used within the off-site HGV construction noise assessment presented within Chapter 14 of the ES (APP-031).

3.3.19 The predicted construction HGV noise levels have then been logarithmically added to the predicted construction noise levels presented in the ES (APP-031) to consider the total construction noise that would occur in the initial stages of the Silvertown Scheme construction programme.

Proposed STP Construction Noise Impacts - Daytime

3.3.20 This section of the report presents the noise predicted for the following operations on the Silvertown construction site:

• Proposed STP activities; and

• All other construction activities presented and discussed within the ES (APP-031).

3.3.21 The range of construction noise levels with the inclusion of the proposed STP in operation during the daytime period of the construction phase is presented in Table 3-4.

Table 3-4 Predicted Construction Noise Levels with STP During - Daytime Period

Receptor Receptor ID Construction noise level Range dB

LAeq

BS 5228-ABC Threshold dB

LAeq Exceed ABC Threshold

Ardennes House SR1 41.0 - 65.0 70 NO

120 Victoria Dock Road SR2 41.0 - 64.7 70 NO

Foster Court SR3 40.9 - 64.0 70 NO

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LAeq



Hoola Development SR4 41.6 - 67.8 81 NO

Alaska Apartments SR5 40.9 - 64.0 70 NO

Western Beach Apartments SR6 42.7 - 68.9 70 NO

3.3.22 It can be seen from the predicted construction noise levels (STP and other construction activities) presented in Table 3-4 that daytime construction noise levels remain below the relevant ABC category at all assessed receptors throughout the construction period.

3.3.23 Therefore, in accordance with BS 5228, and the significance criteria outlined within Section 14.3 of Chapter 14 of the ES (APP-031) daytime construction noise levels would still be concluded as Neutral significance of effect with the inclusion of the additional noise associated with the proposed STP.

3.3.24 This significance of effect remains the same as that concluded for the daytime period in Chapter 14 of the ES (APP-031), and as such the findings of Chapter 14 would remain as reported and the use of a slurry TBM and STP would fall within the parameters of the assessment in the ES (APP-031).

Proposed STP Construction Noise Impacts – Night-time

3.3.25 This section of the report presents the noise predicted for the following operations on the Silvertown construction site:

• Proposed STP activities at night; and

• All other construction activities presented and discussed within the ES (APP-031) at night.

3.3.26 Night time construction noise levels with the inclusion of the proposed STP in operation are presented in Table 3-5.

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Table 3-5 Predicted Construction Noise Levels with STP – Night time period

Receptor Receptor ID

Construction noise level dB LAeq, 8-hour

BS 5228-ABC

Threshold dB LAeq

Exceed ABC

Threshold Level

Ardennes House SR1 47.7 63 NO

120 Victoria Dock Road SR2 48.2 63 NO

Foster Court SR3 48.2 63 NO

Hoola development SR4 50.7 78 NO

Alaska Apartments SR5 49.2 59 NO

Western Beach Apartments SR6 56.0 61 NO

3.3.27 With reference to Table 3-5 above, it can be seen that the envisaged overnight construction activities with the inclusion of the proposed STP would not be in breach of the appropriate BS 5228 criteria and as such would still remain Neutral when considered in accordance with the significance criteria presented with Chapter 14 of the ES (APP-031).

3.3.28 This significance of effect remains the same as that concluded for the night-time period in Chapter 14 of the ES (APP-031), and as such the findings of Chapter 14 would remain as reported and the use of a slurry TBM and STP would fall within the parameters of the assessment in the ES (APP-031).

Proposed STP Construction Noise Impacts – Off site HGV

3.3.29 Table 3-6 presents the predicted noise levels along the identified construction phase HGV routing plan road links. The calculations include HGV movements associated with:

• STP additional HGV movements; and

• All other construction HGV movements as presented and assumed within the ES (APP-031).

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Table 3-6 Predicted Construction HGV Noise Levels with the proposed STP

Road

Predicted Traffic Noise Level dB LAeq 12 Hour

Change in Traffic Noise Resulting from Construction HGVs including Proposed STP

(Construction year minus Do minimum 2021) DM

2021 Year 1 Year 2 Year 3 Year 4 Year 5 Year 1 Year 2 Year 3 Year 4 Year 5

A12 73.1 73.2 73.2 73.2 73.2 73.2 0.1 0.1 0.1 0.1 0.1

A13 East 72.8 72.9 72.9 73 72.9 72.8 0.1 0.1 0.2 0.1 0.0

A13 West 74.4 74.4 74.5 74.5 74.4 74.4 0.0 0.1 0.1 0.0 0.0

Lower Lea Crossing/Leamouth

Road 66.9 67.2 67.4 67.6 67.3 67 0.3 0.5 0.7 0.4 0.1

North Woolwich Road/Connaught Bridge 60.6 61 61.2 61.4 61.2 60.8 0.4 0.6 0.8 0.6 0.2

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3.3.30 The predicted change in noise level with the inclusion of the proposed STP along each identified construction HGV route link in Table 3-6 indicates that there would be no change in noise of greater than 1dB.

3.3.31 In the short term, a change of 1dB is the smallest that is considered perceptible, and as such the magnitude of impact from HGV movements during the construction phase would not materially change from that presented and concluded in Chapter 14 of the ES (APP-031), which identified Neutral significance of effect from this activity.

3.3.32 Thus, the significance of effect remains the same as that concluded in Chapter 14 of the ES (APP-031), and as such the findings of Chapter 14 would remain as reported and the use of a slurry TBM and STP would fall within the parameters of the assessment in the ES (APP-031).

Combined Construction Noise Impacts

3.3.33 An additional appraisal has been undertaken to consider the noise implications of a PPC Segment Manufacturing Plant within the Silvertown construction site. This has been submitted as a separate report (8.65 Environmental Appraisal of PCC Segment Manufacturing Plant). However, a combined assessment considering the following activities has been undertaken in this report:

• Proposed STP activities;

• All other construction activities presented and discussed within the ES (APP-031); and

• PCC segment manufacturing plant activities.

3.3.34 The following assumptions have been embodied within the study relative to the PPC Segment Manufacturing Plant. The assumptions embodied within the consideration of proposed STP activities remain the same as detailed above.

• Concurrent operations (not directly related to either the STP or the PPC Segment Manufacturing Plant) within the Silvertown construction site have been considered as presented and discussed within Appendix 14A Construction Noise of Chapter 14 of the ES (APP-071);

• Assumptions relating to the noise generation and specifics of the PPC Segment Manufacturing Plant are as outlined within

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a separate report (Ref 8.65 Environmental Appraisal of PCC Segment Manufacturing Plant). However, these are summarised below for ease of reference:

o Internal reverberant sound pressure level of the PPC Segment Manufacturing Plant would be no greater than 75 dB(A);

o The proposed plant building envelope sound reduction of 25 Rw has been assumed for the PPC Segment Manufacturing Plant building. This is consistent with the lowest value of attenuation attributable to unlined industrial façade cladding systems;

o The PPC Segment Manufacturing Plant building has been assumed to be 15m high; and

o All prediction assumptions embodied within the original ES (Appendix 14A Construction Noise (APP-071)) have been maintained.

3.3.35 Table 3-7 and Table 3-8 below present the results of the combined assessment scenario as set out above. Table 3-7 considers the daytime impacts and Table 3-8 the night-time respectively.

Table 3-7 Predicted Construction Noise Levels with Proposed STP and the Segment Manufacturing Plant - Daytime


LAeq



Ardennes House SR1 41.0 - 65.0 70 NO

120 Victoria Dock Road SR2 41.0 - 64.8 70 NO

Foster Court SR3 40.9 - 64.1 70 NO Hoola

Development SR4 41.6 - 67.9 81 NO

Alaska Apartments SR5 40.9 - 64.1 70 NO

Western Beach Apartments SR6 42.7 - 69.1 70 NO

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Table 3-8 Predicted Construction Noise Levels with Proposed STP and the Segment Manufacturing Plant – Night time

Receptor Receptor ID

Construction noise level dB LAeq, 8-hour

BS 5228-ABC

Threshold dB LAeq

Exceed ABC

Threshold Level

Ardennes House SR1 47.7 63 NO

120 Victoria Dock Road SR2 48.2 63 NO

Foster Court SR3 48.2 63 NO

Hoola development SR4 50.7 78 NO

Alaska Apartments SR5 49.2 59 NO

Western Beach Apartments SR6 56.0 61 NO

3.3.36 With reference to Table 3-7 and Table 3-8 above, it can be seen that the combined assessment of the envisaged daytime and overnight construction activities with the inclusion of the PPC Segment Manufacturing Plant and the proposed STP would not be in breach of the appropriate BS 5228 criteria and as such would remain Neutral when considered in accordance with the significance criteria presented with Chapter 14 of the ES (APP-031).

3.3.37 These significances of effect remain the same as concluded in Chapter 14 of the ES (APP-031), and as such the findings of Chapter 14 would remain as reported and the use of a slurry TBM and STP together with PCC Segment Manufacturing Plant would fall within the parameters of the assessment in the ES (APP-031).

3.3.38 Levels for construction noise LOAEL (Lowest Observed Adverse Effect Level) and SOAEL (Significant Observed Adverse Effect Level) are defined within Table 14-12 of Chapter 14 of the ES (APP-031). The predicted construction noise levels presented in Table 3-7 and Table 3-8 demonstrate that for the options considered within this report the predicted construction noise levels would in all cases be above LOAEL but remain below SOAEL. This situation is maintained for both the daytime and night-time periods considered, and would not differ from the conclusions presented within

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Chapter 14 of the ES (APP-031). As such it is considered that the use of these construction methodology options would not be in breach of the NPSE or the NN NPS as predicted construction noise levels would remain below SOAEL.

3.3.39 Table 3-9 presents the predicted off site noise changes along links identified within the construction vehicle routing plan for the combined assessment scenario.

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Table 3-9 Predicted Construction HGV Noise Levels with Proposed STP and PCC Segment Manufacturing Plant

Road

Predicted Traffic Noise Level dB LAeq 12 Hour

Change in Traffic Noise Resulting from Construction HGV’s

(Construction year minus Do minimum 2021) DM

2021 Year 1 Year 2 Year 3 Year 4 Year 5 Year 1 Year 2 Year 3 Year 4 Year 5

A12 73.1 73.2 73.2 73.2 73.2 73.2 0.1 0.1 0.1 0.1 0.1

A13 East 72.8 72.9 72.9 73.0 72.9 72.8 0.1 0.1 0.2 0.1 0.0

A13 West 74.4 74.4 74.5 74.5 74.4 74.4 0.0 0.1 0.1 0.0 0.0

Lower Lea Crossing/Leamouth

Road 66.9 67.2 67.4 67.6 67.3 67 0.3 0.5 0.7 0.4 0.1

North Woolwich Road/Connaught Bridge 60.6 61.1 61.3 61.5 61.3 60.9 0.5 0.7 0.9 0.7 0.3

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3.3.40 The predicted change in noise level for the combined assessment scenario along each identified construction HGV route link in Table 3-9 indicates that there would be no change in noise of greater than 1dB.

3.3.41 It is therefore concluded that the magnitude of impacts from HGV movements during the construction phase would not materially change from that presented and concluded in Chapter 14 of the ES (APP-031), which identified a Neutral significance of effect from this activity.

Summary

3.3.42 Within the scope of this report noise impacts have been considered associated with the following additional plant requirements within the construction phase of the Scheme.

• A STP on the Silvertown construction site; and,

• the combined assessment scenario which consists of the STP and the PPC Segment Manufacturing Plant, both of which would be within the Silvertown construction site.

3.3.43 The results of the assessments indicate that construction noise levels would not differ significantly from that reported within Chapter 14 of the ES (APP-031). In all cases for the receptors considered:

• Predicted noise levels would remain below the levels presented within Chapter 14 of the ES (APP-031) considered to be a significant effect. This is maintained for both the on-site noise assessment and the off-site HGV movement assessment; and,

• Predicted significance of effects associated with noise during both the daytime and overnight periods would fall within the parameters previously assessed in the ES (APP-031) without the inclusion of the additional plant items.

3.3.44 Therefore, the conclusions drawn in the ES (APP-031) of a Neutral significance of effect from construction activities associated with the Scheme would remain as reported and the use of a slurry TBM and STP together with PCC Segment Manufacturing Plant would fall within the parameters of the assessment in the ES (APP-031).

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3.4 Townscape and Visual Amenity

3.4.1 Chapter 15 of the ES (APP-031) assesses the potential impacts of the Scheme on townscape and visual amenity.

3.4.2 The construction site, with reference to the ES (paragraph 15.4.4) (APP-031) and Drawing 15.2 (Sheets 1, 2 and 4) (APP-040) falls within a low sensitivity townscape which is presently occupied by a concrete batching plant comprising of three tall silos, mixer, aggregate hoppers and conveyor.

3.4.3 Adjacent to the batching plant is a large industrial work shed with associated material storage areas and two storey high porta cabins surrounded by land in industrial use. These industrial uses include, material recycling, processing and/or storage with associated office buildings, tall sheds and warehousing along with a number of other tall structures that fall within the immediate site vicinity such as the elevated DLR, and the A1020 Silvertown Way, which restrict views to the construction site. The EAL towers, within the site, the large scale tall buildings at Royal Dock Gateway to the east, the roof and structural supports of the O2 with Canary Wharf beyond, to the west, create the main skyline elements of the view.

3.4.4 The Slurry TBM and STP operations include a slurry plant building with a maximum roof pitch height of 16m and silos of a similar height to the plant building. Other much lower features include circular storage tanks of various sizes, a transformer, a conveyor and storage area. With reference to the ES (paragraph 15.6.1) and Drawing 15.2 (Sheets 1, 2 and 4) the appearance, form and scale of the Slurry TBM and STP, as one of a number of construction activities within the Silvertown worksite, is considered to be similar to those currently being used for existing industrial purposes at the site and within the immediate site context. With reference to the ES (paragraph 15.6.2), the existing tall and elevated structures within the site locality would restrict views to the Slurry TBM so that they are only perceived in close proximity. Whilst the STP and silos are discernible, they would be perceived as being similar to the existing features in the view, leaving the main components of the existing view composition unaffected.

3.4.5 As a result, the use of Slurry TBM and STP would, as a worst case scenario, have a slight change in townscape character when compared to the EPB option, and view composition from nearby visual receptors due to the localised intensification of large scale industrial features. However, given the existing baseline, the overall magnitude of change is considered to be the same as assessed in the ES (APP-031). In addition, construction best practice, including a lighting management plan, would be employed to

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minimise any townscape and visual disruption, as set out in the CoCP (REP2-027).

3.4.6 Therefore, the conclusions drawn in the ES (APP-031) of a Slight Adverse significance of effect from construction activities associated with the Scheme would remain as reported and the use of a slurry TBM and STP would fall within the parameters of the assessment in the ES (APP-031).

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4. Conclusions

4.1.1 The option to use of the Slurry TBM and STP has been reviewed and appraised in the context of each environmental topic previously assessed in the Silvertown Tunnel ES (APP-031) to confirm that such methodology would fall within the parameters of the assessment of these topics reported in the ES.

4.1.2 Having carried out the appraisal, the Applicant has concluded that the use of a Slurry TBM and STP and would fall within these parameters.

4.1.3 Should the Contractor decide to use the Slurry TBM and STP, and the PCC Segment Manufacturing Unit (8.65 Environmental Appraisal of PCC Segment Manufacturing Plant), the Applicant has concluded the combined options would also fall within the parameters of the assessment of the topic areas of the ES.

4.1.4 The flexibility TfL and its construction contractor require, as documented in this report, does not present such a wide range of materially different options such that each option in itself might constitute a different project for which consent (and an accompanying EIA) is required, nor will it allow a scheme to be implemented which is materially different from that assessed in the EIA supporting the application.

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Appendix A. Silvertown Works Area Highlight TBM STP Plant [STWTN-ATK-GEN-XXXX-SK-Z-0285]

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PLAN

SCALE 1:1000

WORKSITE BOUNDARY

WORKS AREA

INTERNAL SITE ROADS ONE WAY

ORDER LIMITS

INTERNAL SITE ROADS TWO WAY

SITE ACCESS/EGRESS No. X

C:\programdata\bentley\projectwise\brow3184\dms14411\STWTN-ATK-GEN-XXXX-SK-Z-0285.dwg: Plotted by: brow3184 Date: Jan 24, 2017 - 4:21pm

Drawing Status

DO

N

OT

S

CA

LE

Client

Suitability

Millim

etres

10

010

0

Date

Designed / Drawn

Revision

Scale

Project Drawing Number

Drawing Title

Project Title

Date Date Date

Checked Approved

Original Size

A1

Authorised

Drawn / Des DateCheckedRev Approved

Description

Atkins R

ef.

KEY:

THIS MAP IS REPRODUCED FROM ORDNANCE SURVEY MATERIAL WITH

THE PERMISSION OF ORDNANCE SURVEY ON BEHALF OF THE

CONTROLLER OF HER MAJESTY'S STATIONERY OFFICE. © CROWN

COPYRIGHT. UNAUTHORISED REPRODUCTION INFRINGES CROWN

COPYRIGHT AND MAY LEAD TO PROSECUTION OR CIVIL PROCEEDINGS.

Licence No. 100018928, 2014

SILVERTOWN TUNNEL

SILVERTOWN WORKS AREA

HIGHLIGHT TBM STP PLANT

ST

WT

N-A

TK

-G

EN

-X

XX

X-S

K-Z

-0

28

5

P01.1

S0WORK IN PROGRESS

1:1000 ---

---

---

---

---

---

---

---

P01.1 --- --- --- ---

First Issue

STWTN-ATK-GEN-XXXX-SK-Z-0285

Scale 1:1000

10m 10m0m 20m 60m40m30m 50m 70m

NOTES:

1. THE WORKSITE ARRANGEMENT AND USE, WILL BE IN ACCORDANCE WITH

THE DESCRIPTION PROVIDED IN THE CONSTRUCTION METHOD STATEMENT.

2. THESE DRAWINGS SHOULD BE READ IN CONJUNCTION WITH THE

CONSTRUCTION PHASE DRAWINGS.

3. STAGE 1 RUNS FROM MARCH 2019 TO NOVEMBER 2021 (APPROXIMATELY 32

MONTHS).

4. ACCESS TO THE AREA AROUND THE EMIRATES AIRLINE NORTH MAIN TOWER

WILL BE MAINTAINED THROUGHOUT DURATION OF THE WORKS.

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