crossrail line 1 assessment of contaminated land impacts technical report volume 1 of...

Assessment of Contaminated Land Impacts Technical Report

Mott MacDonald Ltd Cross London Rail Links Limited

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Crossrail Line 1 Assessment of Contaminated Land Impacts Technical Report Volume 1 of 2

February 2005

Crossrail Reference 1E0322-C1E00-00013



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Crossrail Line 1 Assessment of Contaminated Land Impacts Technical Report - Volume 1 of 2 February 2005 Crossrail Reference 1E0322-C1E00-00013

Mott MacDonald Limited

REVISION HISTORY

Rev Date Prepared Review Approved Accepted Description

Final 14/02/05 SA

MD

FS

FS JB TH Final Report

Cross London Rail Links Limited 1, Butler Place LONDON SW1H 0PT Tel: 020 7941 7600 Fax: 020 7941 7703 www.crossrail.co.uk



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Assessment of Contaminated Land Impacts Document Number 1E0322-C1E00-00013

Technical Report Volume 1 of 2

February 2005

This document has been prepared for the titled project or named part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Mott MacDonald being obtained. Mott MacDonald accepts no responsibility or liability for the consequence of this document being used for a purpose other than the purposes for which it was commissioned. Any person using or relying on the document for such other purpose agrees, and will by such use or reliance be taken to confirm his agreement to indemnify Mott MacDonald for all loss or damage resulting there from. Mott MacDonald accepts no responsibility or liability for this document to any party other than the person by whom it was commissioned.



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Contents and List of Figures 1 Introduction..................................................................................................................5 2 Scope and methodology..............................................................................................7 2.1 Introduction .........................................................................................................7 2.2 Legislative framework and guidance...................................................................7 2.3 Establishment of baseline condition....................................................................7 2.4 Prediction of impacts...........................................................................................9 3 Environmental baseline and assessment of impacts - route wide.............................11 3.1 Introduction .......................................................................................................11 3.2 Disposal to landfill .............................................................................................11 3.3 Remediation alternatives...................................................................................12 3.4 Summary of contaminated material disposal ....................................................12 4 Environmental baseline and assessment of impacts -

Maidenhead to Westbourne Park......................................................................14 4.1 Summary of Western Section Impacts..............................................................15 4.2 Route window W25 ...........................................................................................19 4.3 Route window W24 ...........................................................................................21 4.4 Route window W23 ...........................................................................................22 4.5 Route window W22 ...........................................................................................24 4.6 Route window W21 ...........................................................................................25 4.7 Route window W20 ...........................................................................................27 4.8 Route window W19 ...........................................................................................28 4.9 Route window W18 ...........................................................................................29 4.10 Route window W17 ...........................................................................................31 4.11 Route window W16 ...........................................................................................33 4.12 Route window W15 ...........................................................................................35 4.13 Route window W14 ...........................................................................................37 4.14 Route window W13 ...........................................................................................39 4.15 Route window W12 ...........................................................................................41 4.16 Route Window W11 ..........................................................................................42 4.17 Route window W10 ...........................................................................................44 4.18 Route window W9 .............................................................................................46 4.19 Route window W8 .............................................................................................47 4.20 Route window W7 .............................................................................................49 4.21 Route window W6 .............................................................................................51 4.22 Route window W5 .............................................................................................53 4.23 Route window W4 .............................................................................................55 4.24 Route window W3 .............................................................................................57 4.25 Route window W2 .............................................................................................59 4.26 Route window W1 .............................................................................................60 5 Environmental baseline & assessment of impacts-

Westbourne Park to Stratford/Isle of Dogs........................................................61 5.1 Summary of Central Section Impacts................................................................62 5.2 Route window C1 ..............................................................................................66 5.3 Route window C2 ..............................................................................................68 5.4 Route window C3 ..............................................................................................71 5.5 Route window C4 ..............................................................................................72 5.6 Route window C5 ..............................................................................................74 5.7 Route window C6 ..............................................................................................76 5.8 Route window C7 ..............................................................................................78 5.9 Route window C8 ..............................................................................................80 5.10 Route window C8a ............................................................................................83 5.11 Route window C9 ..............................................................................................84 5.12 Route window C10 ............................................................................................86 5.13 Route window C11 ............................................................................................87 5.14 Route window C12 ............................................................................................90 5.15 Route window C13 ............................................................................................92 5.16 Route window C13a ..........................................................................................95



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6 Environmental baseline & assessment of impacts – Stratford to Shenfield ..............96 6.1 Summary of North Eastern Section impacts .....................................................97 6.2 Route window NE1............................................................................................99 6.3 Route window NE2..........................................................................................101 6.4 Route window NE3..........................................................................................103 6.5 Route window NE4..........................................................................................105 6.6 Route window NE5..........................................................................................107 6.7 Route window NE6..........................................................................................109 6.8 Route window NE7..........................................................................................111 6.9 Route window NE8..........................................................................................113 6.10 Route window NE9..........................................................................................115 6.11 Route Window NE10.......................................................................................118 6.12 Route window NE11........................................................................................120 6.13 Route window NE12........................................................................................122 6.14 Route window NE13........................................................................................124 6.15 Route window NE14........................................................................................125 6.16 Route window NE15........................................................................................126 6.17 Route window NE16........................................................................................128 6.18 Route window NE17........................................................................................129 6.19 Route window R1 ............................................................................................131 7 Environmental baseline & assessment of impacts – Isle of Dogs to Abbey Wood .133 7.1 Summary of South Eastern section impacts ...................................................134 7.2 Route window SE1..........................................................................................137 7.3 Route window SE2..........................................................................................140 7.4 Route window SE3..........................................................................................142 7.5 Route window SE4..........................................................................................145 7.6 Route window SE5..........................................................................................149 7.7 Route window SE6..........................................................................................152 7.8 Route window SE6a........................................................................................154 7.9 Route window SE7..........................................................................................155 7.10 Route Window SE8 .........................................................................................156 8 Cumulative impacts and mitigation measures.........................................................158 8.1 Cumulative impacts.........................................................................................158 8.2 Mitigation measures ........................................................................................158 9 Principal Findings and Summary.............................................................................161 Appendices .................................................................................................................164 Appendix A: Site Contamination Matrices...................................................................165 Appendix B:Generic Mitigation Measures...................................................................508 Appendix C:Analytical Results – North Dock ..............................................................515 Appendix D:Assumptions and Limitations...................................................................517 D.1 Generic Assumptions ......................................................................................518 D.2 Site Specific Assumptions...............................................................................521 D.3 Limitations .......................................................................................................523 Appendix E:Glossary ..................................................................................................524 Appendix F:References ..............................................................................................526



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1 Introduction Crossrail is a major new cross-London rail link project that has been developed to serve London and the southeast of England. Crossrail will support and maintain the status of London as a world city by providing a world class transport system. The project includes the construction of a twin-bore tunnel on an east-west alignment under central London and the upgrading of existing National Rail lines to the east and west of central London. The project will enable the introduction of a range of new and improved rail journeys into and through London. It includes the construction of seven central area stations, providing interchange with London Underground, National Rail and London bus services, and the upgrading or renewal of existing stations outside central London. Crossrail will provide fast, efficient and convenient rail access to the West End and the City by linking existing routes from Shenfield and Abbey Wood in the east with Maidenhead and Heathrow in the west. Crossrail’s route has four distinct sections: a central section within central London and, outside central London, western, northeastern and southeastern sections. In the west, Crossrail will use the Great Western Main Line between Maidenhead and Westbourne Park. The existing 25 kV overhead electrification between Paddington and Airport Junction will be extended to Maidenhead and bridge alterations will be undertaken as necessary. The main infrastructure changes are the construction of a flyover structure (the Stockley flyover) to allow Crossrail trains to access the existing tunnelled spur to Heathrow and the provision of a rail underpass (a dive-under) west of Acton Yard. A new line, within the existing railway corridor, will be provided between Langley and West Drayton. Enhancements will also be made to stations, with the most significant works being at Ealing Broadway, Southall, Hayes and Harlington, West Drayton, Slough and Maidenhead. New stabling sidings are also proposed at Old Oak Common, West Drayton and west of Maidenhead station. The central route section will consist largely of a twin-bore tunnel beneath central London with portals at Royal Oak in the west, Pudding Mill Lane in the northeast and Victoria Dock Road in the southeast. The central route section extends from a point around 200m west of the A40 Westway to a point around 500m to the east of the portal at Pudding Mill Lane in the northeast and a point just to the east of Poplar Dock and the A1206 Prestons Road in the Isle of Dogs in the southeast. New stations and associated structures, such as ventilation shafts, will be provided along this part of the route. On the northeast route section, Crossrail will use the existing Great Eastern Main Line between Pudding Mill Lane and Shenfield. The main infrastructure changes are a new train maintenance depot west of Romford station and the reinstatement of a track between Goodmayes and Chadwell Heath. Enhancements will also be made to stations, with the most significant works being proposed at Ilford and Romford. This route has existing 25kV overhead electrification. New stabling facilities will be provided at Gidea Park. The southeast route section runs between a point to the east of the Isle of Dogs station and the eastern terminus at Abbey Wood, where Crossrail will serve a reconstructed station. Crossrail will operate in a twin-bore tunnel to Victoria Dock portal where it will serve a reconstructed station at Custom House. The route will then follow the existing alignment currently used by the North London Line through the Connaught Tunnel to Silvertown. At North Woolwich, a new twin-bore tunnel to Plumstead, referred to as the Thames Tunnel, will pass beneath the River Thames. Two new tracks will be provided between Plumstead and a point east of Abbey Wood station to accommodate Crossrail services on the North Kent Line corridor. This route will be provided with 25kV overhead electrification on the Crossrail lines. Crossrail will be a significant addition to the transport infrastructure of London and the southeast of England. It will deliver improved services for rail users through the relief of crowding, faster journeys and the provision of a range of new direct journey opportunities. The




project will also have wider social and economic benefits for London and the southeast of England. Mott MacDonald were appointed by Crossrail to undertake a contaminated land study of the four sections of the Crossrail route to assess the ground conditions and impacts which may arise from the Crossrail project. The study was one of a number of individual specialist assessments, which together provided the primary information to the Environmental Statement. This document should be viewed in conjunction with Assessment of Contaminated Land Impacts - Volume 2, Technical Report Figures.




2 Scope and methodology

2.1 Introduction The contaminated land study is different to most other specialist studies in that sites with potentially contaminative histories are not conventional resources or receptors but a type of ground which may be affected by the Crossrail project and in turn may subsequently impact a sensitive receptor (e.g. site workers or ground or surface water receptors). Impacts in respect of contaminated land for the Crossrail project will principally arise where the works break ground (e.g. construction of portals, vent shafts or stations) or where the ground is disturbed (e.g. through removal of existing railway and ballast) or exposed (e.g. through demolition works). Contaminated land may be present as a result of historical activities at a particular location or as a result of current operations. This technical report (Assessment of Contaminated Land Impact Technical Report) describes collation and assessment of information in relation to contaminated land and to impacts to the Crossrail project. The technical report is intended to provide a picture as to how the assessment process has been undertaken and describe the anticipated range of impacts. Information obtained during this report will inform the Environmental Statement. The Environmental Statement is a separate document which will address only the significant environmental impacts arising from all elements of the project of which contaminated land is one of the specialisms. The methods used to carry out the assessment for the technical report were originally described in the “Crossrail Line 1: Scoping and Methodology Report- March 2003 (Cross London Rail Links Ltd/Environmental Resources Management). Since the publication of this document modifications have been made to the methodology and alterations have been highlighted in Appendix D, Assumptions and Limitations.

2.2 Legislative framework and guidance The following legislation is applicable to contaminated land and has been used to assist in the identification of potentially significant sites:

• Environmental Protection Act, 1990 Part IIA • Contaminated Land Regulations 2000 (SI 2000/227) • Environmental Protection (Duty of Care) Regulations 1991 • Waste Management Licensing Regulations 1994 • EC Landfill Directive 1999 • Special Waste Regulations 1996 • Landfill Tax (Contaminated Land) Order 1996 • Landfill (England and Wales) Regulations 2002 • Construction (Design and Management Regulations) 1994 • Water Resources Act 1991(WRA 1991) • Groundwater Regulations 1998 (GR 1998) • Animal Health Act 1981 Notifiable Disease Burial Sites

2.3 Establishment of baseline condition The presence of contaminated land is assessed against the principle of a ‘pollution linkage’. A pollution linkage involves consideration of three elements – a source, a pathway and a receptor. All three elements must be present for a pollution linkage to exist and for land to fall




within the definition of ‘contaminated land’ under Part IIA of the Environmental Protection Act 1990. The initial phase of the study was to identify all potential ‘sources’ of contaminated land within 250m of the route alignment and establish general conditions. General conditions were established by conducting and/or reviewing the following documentation where available:

• Project environmental features mapping; • Landmark Envirocheck information along a 250m wide route corridor either side of the

proposed route alignment; • Aerial photographs; • Local Authority Unitary Development Plans (UDP’s); • Department of Environment Industry Profiles; • Data collected by specialist study teams, i.e. water specialists with regard to

groundwater vulnerability and surface water bodies; • Relevant data obtained from any previous environmental intrusive investigations where

the data is held by the project; • British Geological Survey (BGS) data; and • Outputs from the ongoing site investigation programme.

Issues relating to contaminated land are significantly influenced by geology, hydrogeology and surface water. A separate technical report covering these issues has been prepared by Mott MacDonald water specialists and additional consultation with these specialists was undertaken where appropriate to assist in the assessment of contaminated land issues. Using the above, this initial information was collated and compared to scheme plans to identify areas where the Crossrail project would involve significant areas of ground break including where new stations, entry and exit facilities, ticket halls or car parking areas will be constructed, locations of tunnel vent shafts and positions of any buildings which will need to be demolished in order for the project to proceed. Once these areas were established a screening exercise was conducted in order to identify sources, pathways and receptors and remove sites which were considered to be ‘non-significant’. Sites were considered to be ‘non-significant’ in contaminated land terms based on an assessment of the following screening parameters: Absence of sources due to:

• Distance from areas of ground break (i.e. greater than 100m); • Site contaminants unlikely to have impacted ground conditions (i.e. only small scale

use of contaminants likely or site was hard surfaced); or • The site has been substantially redeveloped and the likelihood of contaminants

remaining is considered to be low. Absence of pathways:

• Underlying ground conditions would not facilitate migration of contaminants; • No groundwater or surface water resources in close proximity: • No ground break (e.g. for stations or vent shafts) in close proximity and therefore

pathways for human receptors not feasible (e.g. inhalation, dermal contact or ingestion); or

• No man made pathways known or identified by the project. Absence of receptors at identified locations:

• Crossrail associated personnel would not be present at these locations; or • Off- site contamination unlikely to migrate to area of ground break where receptors will

be present.




These sites were removed from the study and no further assessment was undertaken at these locations. For the remaining sites, a ‘walk past’ assessment was carried out. These inspections were undertaken from public rights of way to establish the current use and general site setting. No internal inspections of sites were undertaken nor were site personnel interviewed regarding site operations or processes. The information obtained from the walk past survey of each site included, where possible, the following:

• General features – site description and size, site occupants; • Tanks and chemical storage – presence of underground and above ground storage

tanks, fuel pumps, general; • Presence of transformers and substations; • Waste – type, storage, housekeeping; • Water supply and drainage; and • Surrounding land uses and sensitive receptors.

The output of this phase of the study mapped the remaining potentially contaminated land along the route and comprised the contaminated land ‘baseline conditions’ for the scheme. For the purposes of mapping, the sites were colour coded to reflect possible contaminative status given their current operations and historical land uses:

• Gas works sites (light brown); • Oil related sites (light green); • Hazardous sites (blue); • Manufacturing sites of a contaminative nature (purple); • Utilities sites (yellow); • Biologically affected sites (dark green); and • Other contaminated sites (orange).

2.4 Prediction of impacts Using the data collated a qualitative risk assessment using the accepted source-pathway-receptor model (advocated by Part IIA of the Environmental Protection Act 1990) was carried out for all remaining sites in order to further assess the sites and their potential impact magnitude. The approach for the qualitative risk assessment method used was as follows:

• Source and hazard identification - the contaminant source was characterised in terms of the likely nature of the hazard which could be expected;

• Pathway and exposure assessment – the exposure pathway was characterised and potentially affected resources were identified; and

• The risk was characterised on the basis of the potential harm to the receptor within the given source-pathway-receptor combination (or pollution linkage) taking into consideration factors such as contaminant mobility, geology and engineering features of the Crossrail scheme.

Locations identified as having a potential for contamination were classified as either ‘low’, ‘medium’ or ‘high’ in terms of potential impact magnitude on the basis of the potential risk a particular site has, based on current or historical use, to cause harm either to humans or other environmental receptors. Sites were classified into ‘low’, ‘medium’ and ‘high’ based on the following criteria:




• Low: A risk rating of low has been applied where there is potential for low level contamination to be present but which is unlikely to significantly affect future construction/operational issues. This would be restricted to sites which are unlikely to have significant concentrations of contaminants and have minimum potential for impact upon sensitive receptors.

• Medium: A risk rating of medium has been given to sites where contamination is

suspected to be present although the potential for impact upon main receptors is likely to be limited. Further intrusive investigation will be needed to clarify the nature and extent of contamination present.

• High: A classification of high has been applied to sites where levels of contamination

are suspected to be elevated and/or the potential for impact upon main receptors could be significant. It is likely that remedial measures will be necessary to mitigate impacts.

Where there is ambiguity regarding the risk classification of a site it has been given a medium or high classification to ensure that it is properly addressed in the decision making process. A summary of the conceptual risk assessment undertaken for each site is given in the site contamination matrices presented in Appendix A. For the purposes of the environmental assessment sites which are identified as medium or high risk have been classified as ‘significant sites’. These are discussed in the appropriate route window and are considered to be sites likely to require protective practises during construction and/or site investigations to refine the design of necessary remedial measures. Appendix B describes typical mitigation measures which may be appropriate with respect to the main resources and receptors affected by contamination. Theses significant sites have been carried forward to the Environmental Statement key features mapping and are reported in the Environmental Statement.

2.5 Layout of the Technical Report The information relating to contaminated land in the following chapters is laid out in four route sections (Western, Central, North-eastern and South-eastern). Each route section is divided into a number route windows and the information relating to contaminated land is laid out in the following manner:

• Anticipated groundworks

Provides a brief summary of the main construction works to be carried out in each route window. Full details are provided in the Environmental Statement.

• Route window description

Provides a brief description regarding the general character of each route window.

• Route window setting Describes the geological, groundwater and surface water features of each route window. Further detailed information can be obtained from the Crossrail water specialists report.

• Significant sites Describes the land uses and potential associated contamination sources of sites which have been classified as medium or high risk.

• Temporary impacts Describes the likely impacts which will occur from disturbance of contaminated land during construction works, prior to mitigation.

• Permanent impacts Describes the likely impacts which will occur during the operational phase of the project.

• Mapping References Provides reference to the drawing numbers in Volume 2 which show the baseline and significant site for each route window.




3 Environmental baseline and assessment of impacts - route wide

3.1 Introduction The impacts which arise may result from disturbance of contaminated land (e.g. impacts to human health or water quality prior to the incorporation of mitigation measures), are predicted to be site specific and as such will not give rise to route wide impacts. However, given the scale of the scheme, there is likely to be a small volume of contaminated material (in relation to the total volume of excavated material) which may require treatment and or disposal across the entire route. A proportion of the materials excavated during the tunnelling and construction works will have been contaminated by historical activities or events along the route alignment. These materials will require particular attention in handling, from the perspective of potential environmental impacts, health and safety and treatment and disposal. It will be necessary to make provision in the construction programme for intrusive investigations to be carried out at those sites identified as potentially contaminated. This will include site investigations and the retrieval of soil and water samples for laboratory analysis. The results of the site investigations will determine more precisely the nature and extent of the contamination and will aid the development of appropriate mitigation measures in accordance with the construction design and programme and the regulatory requirements.

3.2 Disposal to landfill The direct disposal of contaminated materials to appropriately licensed landfill sites is the least preferable option. It has been common industry practice in the UK for many years to place contaminated soils in landfill sites, very often in conjunction with inert or non-hazardous putrescible materials. This form of co-disposal has been banned in the UK under the Landfill Regulations 2002. These regulations required the operators of all landfill sites to register their sites to take materials in one of three categories: inert, non-hazardous and hazardous. The co-disposal of hazardous wastes with other wastes is no longer permitted and wastes can only be accepted at a particular landfill if they meet the relevant waste acceptance criteria for that class of landfill. The full waste acceptance criteria are scheduled to apply from July 2005 and so will be applicable to the Crossrail project. For hazardous waste landfills there will be a Hazardous Waste List (part of the Consolidated European Waste Catalogue (EWC)) and if the materials for disposal are on the list, they will need to be assessed against leaching limit values and other criteria prior to acceptance. The EWC lists those wastes that are ‘absolute entries’ (hazardous waste regardless of their concentration) and ‘mirror entries’ (hazardous waste only if ‘dangerous substances’ are present above threshold concentrations). Contaminated soils are ‘mirror entries’ in the EWC. This means that contaminated soils may be classified as either hazardous or non-hazardous depending on the concentrations of ‘dangerous substances’ in the soil. An assessment of the composition of the waste soil via sampling and laboratory analysis should therefore be undertaken to determine if the waste is classifiable hazardous. At the same time that changes to the regulation of landfills are being introduced, the UK government has announced proposals to replace the Special Waste Regulations 1996 with new Hazardous Waste Regulations. The new regulations will replace the current definition of ‘special waste’ with the European law term ‘hazardous waste’. Consultation on the proposed new regulations came to a close late in 2004 and further announcements on the final details of the legislation are awaited.




The effect of the ban on co-disposal of hazardous and non-hazardous wastes and the requirement to classify landfill sites, coupled with the uncertainty surrounding waste acceptance criteria and the definition of hazardous wastes, has been a drastic reduction in the number of commercial landfill sites in the UK permitted to accept hazardous wastes. In answer to a parliamentary question in September 2004, the Secretary of State for the Environment submitted tables showing that applications had been submitted for eighteen commercial hazardous waste landfills of which only six had been granted, nine were to be determined and three had been refused. An initial assessment indicates that none of the sites that had received permits would provide suitable outlets for contaminated materials from the Crossrail project (Excavated material and waste management strategy technical report, Volume 1, Mott MacDonald, February 2005). Discussions have been held with landfill site operators during the assessment of available landfill sites for surplus materials from the Crossrail project and, although none of the operators is currently able to offer landfill disposal space for contaminated materials, several are considering making applications to establish stable non-reactive hazardous waste disposal cells within existing non-hazardous waste sites and to establish treatment facilities for hazardous wastes at such sites. The decision of the landfill operators on whether to proceed with these proposals is likely to be influenced by developments in clarification of the waste acceptance criteria and the proposed hazardous waste regulations. The decision of the landfill operators will also be driven by the commercial viability of their proposals and this will include a guaranteed supply of waste for treatment or disposal. The landfill operators have indicated that the Crossrail project could be a potential provider of such material but the commercial viability will depend on the volumes of materials and the nature of the contamination, neither of which will be precisely determined before the project is approved.

3.3 Remediation alternatives There are a wide range of remedial techniques which can be used to reduce or contain contamination in soils and waters. Details of a selection of techniques available are provided in Appendix B. The extent to which remediation techniques can be carried out within the construction sites will be determined by the nature of the contamination, the available space and the amount of time available within the construction programme. There are commercial treatment facilities at off-site locations which may have to be used. Remediation and beneficial re-use of contaminated materials is in accordance with the principles of best practicable environmental option. Discussions with the Environment Agency have established that the Agency is in favour of this approach rather than direct disposal to landfill. There are potential constraints on the use of remediation techniques associated with space and time in a project where continuous removal of excavated materials is vital to the progress of tunnelling activities. Crossrail will, therefore, explore and promote the application of remediation to contaminated excavated materials, both on-site and off-site, in preference to direct disposal wherever the actual best practicable environmental option can be achieved.

3.4 Summary of contaminated material disposal The effect of recently introduced and currently proposed regulatory changes has drastically reduced the available landfill disposal outlets for hazardous materials. The commercial response to this situation is only now developing and it is necessary that Crossrail:

a) investigates and maximises the opportunities for on-site remediation and re-use of contaminated materials;

b) investigates and maximises the opportunities for off-site remediation and beneficial re-use elsewhere of contaminated materials;

c) engages in continuous dialogue with the operators of treatment facilities and landfill sites to secure suitable outlets for contaminated materials.




It is considered that, despite the current position of uncertainty which arises from circumstances outside the control of Crossrail, the actions identified above will provide acceptable solutions which will not be a barrier to the progress of the project or cause impacts to the environment or harm to human health.




4 Environmental baseline and assessment of impacts - Maidenhead to Westbourne Park

This section comprises a review of route windows W25 to W1

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4.2 Route window W25 Anticipated groundworks Within this route window the main Crossrail works will involve: • Construction of stabling and turnback facilities west of Maidenhead station; • Upgrading of Maidenhead station including a new ticket hall, lifts, a new platform for

Marlow branch services and platform extensions; • An extension to the existing subway; and • Introduction of overhead line equipment. Route window description Route window W25 is located between York Stream (western bank) to the east and Welbeck Road to the west of the route window along the route of the existing Great Western Railway (GWR) corridor. The window is located within Maidenhead Town Centre. The rail corridor is bordered to the north by modern office developments to the east of the window and industrial units for the remaining section, with some housing to the far west of the window. To the south is found primarily housing along the length of the route window with the exception of the eastern end where modern offices, a multi storey car park and an industrial depot border the tracks. Route window setting The geology of route window W25 comprises Chalk overlain to the east of Maidenhead Station by superficial deposits (Alluvium, Taplow Terrace gravels and Floodplain Terrace Gravels). There is a small area of Boyn Hill Terrace gravels in the north of the route window. At Maidenhead Station, there are no superficial deposits; the Chalk outcrops at the surface. There is one Chalk groundwater abstraction within the route window. This is licensed to Maidenhead Golf Club Ltd for spray irrigation purposes. The route window lies on a Source Protection Zone (SPZ) associated with two large South East potable water supply boreholes abstracting from the Chalk. Maidenhead Ditch (and associated fluvial floodplain) crosses the route alignment in the east of the window. There are no surface water abstractions. Significant sites Three sites have been given a medium risk classification for contamination according to the methodology, due to their previous historical use, site visit observations and the necessity for physical groundworks during construction. Maidenhead Station (W25-01) has been recorded in its present location since 1876. It has remained in this location up until the present day with little change to the site layout. Typical contaminants associated with the station are likely to include ash, clinker, coal, fuel oils (above and below ground storage tanks), lubricants, general hydrocarbons and solvents, heavy metals, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, phenols, herbicides and pesticides, creosote and timber treatment products and asbestos. The remaining sites (W25-03 and W25-04) comprise an industrial estate situated adjacent to Boyn Valley Road. This is the location of the proposed stabling site. This site has previously been occupied by sidings, goods sheds and cattle pens up until the 1930s. Around 1955, the area was developed as an industrial estate, with paint works and several engineering works along with allotment gardens. Since this time the industrial estate has expanded and now occupies the area where previously the allotments were found. Potential contaminants




associated with this site include ash, clinker, coal, metals, including lead paints, creosote, hydrocarbons including diesel, oils, aromatic and chlorinated, pesticides and asbestos. Temporary impacts During the groundworks, construction workers and site visitors may inhale, ingest or have dermal contact with concentrations of contamination which have the potential to cause detrimental impacts to human health. Groundworks in these areas may facilitate the migration of contaminants into the major aquifer which could impact on groundwater quality and abstraction water quality. As a result of the construction works there is a potential for the mobilisation and migration of contaminants and the production of dusts and contaminated run-off which could result in impacts to surface water courses within the vicinity of the site. However, these impacts can be mitigated through good practice during construction, soil disposal or remediation as necessary. Site investigations and quantitative risk assessments would provide further information on the level of contamination in order to refine mitigation measures, as set out in Appendix B. With such mitigation in place, the impact of these sites on the project would be reduced to non-significant levels. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00049. The sites which are considered to have a potentially significant impact (before mitigation) are shown on drawing number 1E0322-W1E00-E00-F-00050.




4.3 Route window W24 Anticipated groundworks

Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment. This will generally employ portal frames,

although masts with cantilevers will be used over Maidenhead Bridge. Route window description Route window W24 is located between Jubilee River Bridge (western end) to the east and York Stream (western bank) to the west of the route window along the route of the existing GWR corridor. With the exception of a centrally located industrial estate to the north and an industrial estate to the south west, housing borders the rail lines along the length of the route window. Route window setting The geology of route window W24 comprises Chalk, overlain by superficial deposits including Floodplain Terrace Gravels, Alluvium and Taplow Terrace Gravels. The superficial deposits are approximately 5 to 8m thick. There are no groundwater abstractions within the route window. There are five surface water crossings within the window: Jubilee River, Amerdon Grove Ditch, the River Thames and two branches of Maidenhead Ditch. The entire route window is located on the fluvial floodplain to the Thames. There are no surface water abstractions within the route window. Significant sites None of the sites within this route have been assessed as having a significant impact for the Crossrail project. Temporary impacts There are no significant temporary impacts identified for this route window. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00047.




4.4 Route window W23 Anticipated groundworks Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment throughout the alignment in this route window; • At Taplow station, the safety implications of this electrification will require that the parapets

of the station footbridge be modified; and • An extension of the platforms at Taplow Station by about 26m to accommodate Crossrail

trains. Route window description Route window W23 is located between Hitcham Road in the east and Jubilee River Bridge (western end) to the west of the route window, along the route of the existing GWR corridor. Playing fields border the rail tracks to the east of the window, north of the rail tracks, with housing found towards the west of the window. To the south of the rail tracks, a lake is found with the remaining land being predominantly undeveloped. Route window setting The geology of route window W23 comprises superficial deposits (Taplow Terrace Gravels and Floodplain Terrace Gravels). The superficial deposits are up to 8m thick. Taplow Station itself lies on the boundary between the Reading Beds and the underlying Chalk. The Thanet Sands are not present. The Chalk is exposed at the surface in the west of the route window in a small area of lower ground where no superficial deposits are present. The area is classified as a major aquifer by the Environment Agency. There are no groundwater abstractions in the route window. Three outer SPZs extend into the route window but do not cross the route alignment. There are several surface water features within the window. The Roundmoor Ditch and associated floodplain is present in the south-east of the window. The route alignment crosses Amerden Grove Ditch and the Jubilee River which are within culverts approximately 900m west of Taplow Station. Amerden Ponds are located immediately to the south of the route alignment. The south-west side of the route window lies on the fluvial floodplain of the Thames. Significant sites One site has been given a medium risk classification according to the methodology, due to its previous historical usage, site visit observations and the necessity for physical groundworks during construction. Taplow Station (W23-01) has been recorded in existence since 1875. It has remained at this location up until the present day, with minor changes having taken place to the station buildings along with some expansion of the railway sidings. Typical contaminants associated with the station are likely to include ash, clinker, coal, fuel oils (above and below ground storage tanks), lubricants, general hydrocarbons and solvents, heavy metals, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), phenols, herbicides and pesticides, creosote and timber treatment products and asbestos. Temporary impacts During the groundworks, construction workers and site visitors may inhale, ingest or have dermal contact with concentrations of contamination which have the potential to cause detrimental impacts to human health. There is also the potential for construction workers to




come into contact with shallow groundwater which may contain elevated concentrations of contaminants. Groundworks in these areas may facilitate the migration of contaminants into the major aquifer which could impact on groundwater quality and abstraction water quality. However, these impacts can be mitigated through good practice during construction, soil disposal or remediation as necessary. Site investigations and quantitative risk assessments would provide further information on the level of contamination in order to refine mitigation measures, as set out in Appendix B. With such mitigation in place, the impact of these sites on the project would be reduced to non-significant levels. Permanent impacts There are no significant permanent impacts identified for this route window Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00045. The site which is considered to have a potentially significant impact (before mitigation) is shown on drawing number 1E0322-W1E00-E00-F-00046.




4.5 Route window W22 Anticipated groundworks Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment throughout the alignment. Route window description Route window W22 is located between Clare Road to the east and Hitcham Road in the west of the route window, along the existing GWR corridor. The route window is primarily occupied by residential premises with the exception of a small number of industrial estates bordering the railway to the east of the route window. Route window setting Route window W22 is underlain by superficial deposits (Brickearth, Taplow Terrace Gravels and Floodplain Terraces) overlying the Reading Beds and Chalk. The superficial deposits are expected to be approximately 5 to 8m thick. According to the groundwater vulnerability map the route window lies above a major aquifer although there are no groundwater abstractions. The Roundmoor Ditch and associated fluvial floodplain is present in the south-west corner of the route window. Roundmoor Ditch has a poor quality with a General Quality Assessment (GQA) of Grade F (bad), and a Grade 5 River Quality Objective (RQO). There are no surface water abstractions within the route window. Significant sites None of the sites within this route have been assessed as having a significant impact for the Crossrail project. Temporary impacts There are no significant temporary impacts identified for this route window. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00043.




4.6 Route window W21 Anticipated groundworks Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment throughout the alignment; and • An extension of the island platform at Burnham station westwards by about 26 m to

accommodate Crossrail trains. Route window description Route window W21 is located between Henley Road in the east and Clare Road to the west of the route window, along the existing GWR corridor. The route window is primarily occupied by residential premises with the exception of a small number of industrial estates bordering the railway to the east of the route window. Route window setting Route window W21 is underlain by superficial deposits (Brickearth, Taplow Terrace Gravels and Floodplain Terraces) directly overlying solid deposits of the Reading Beds and Chalk. The superficial deposits are approximately 7 to 8 m thick. The groundwater vulnerability map of the area shows the route window lies on a major aquifer. There are no groundwater abstractions within the route window. The alignment crosses Chalvey Ditch and the associated fluvial floodplain between Burnham Station and Dover Road Bridge. The Chalvey ditch has a chemical GQA of C (fairly good), and the RQO is Grade 2. There are no surface water abstractions within the route window. Significant sites One site has been given a medium risk classification according to the methodology, due to its previous historical usage, site visit observations and the necessity for physical groundworks during construction. Burnham Station (W21-05) has been recorded in existence since 1924 and has remained at this location up until the present day. Minor alterations have been undertaken to the station and platform configuration during this period. Potential contaminants associated with this site include ash, clinker, coal, fuel oils (above and below ground storage tanks), lubricants, general hydrocarbons and solvents, heavy metals, PCBs, PAHs, phenols, herbicides and pesticides, creosote and timber treatment products and asbestos. Temporary impacts During the groundworks, construction workers and site visitors may inhale, ingest or have dermal contact with concentrations of contamination which have the potential to cause detrimental impacts to human health. There is also the potential for construction workers to come into contact with groundwater within the superficial deposits which may contain elevated concentrations of contaminants. There is potential for contaminants to be mobilised during construction works which may impact on the major aquifer which lies directly beneath the site and on Chalvey Ditch which crosses the route alignment at the eastern end of Burnham Station. However, these impacts can be mitigated through good practice during construction, soil disposal or remediation as necessary. Site investigations and quantitative risk assessments




would provide further information on the level of contamination in order to refine mitigation measures, as set out in Appendix B. With such mitigation in place, the impact of these sites on the project would be reduced to non-significant levels. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00041. The site which is considered to have a potentially significant impact (before mitigation) is shown on drawing number 1E0322-W1E00-E00-F-00042.




4.7 Route window W20 Anticipated groundworks Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment throughout the alignment; and • Parapet works to Dover Road Bridge and the replacement of Leigh Road Bridge with a

new steel 25m span bridge to accommodate the OHLE.

Route window description Route Window W20 comprises the area between Yarmouth Road and Henley Road with the railway lines and its associated sidings occupying the area through the middle. Since the early 20th century this route window has been predominantly occupied by industrial and commercial premises. It has undergone significant development and expansion throughout the years with more industries and trades moving into the area. It now forms part of the Slough Trading Estate and includes major road and rail infrastructure. The wider current land uses comprise residential and retail premises. Route window setting The geology of route window W20 comprises superficial deposits (including Taplow Terrace Gravels and Brickearth) overlying the Reading Beds and Chalk. The superficial deposits in this area are likely to be between 5 and 8m thick. The route window lies within three outer SPZs. There is one groundwater abstraction from the Chalk within the route window used for general cooling processes by Sara Lee Household. Chalvey Ditch and the associated floodplain runs across the south west corner of the route window. There are no surface water abstractions within this route window. Significant sites None of the sites within this route have been assessed as having a significant impact for the Crossrail project. Temporary impacts There are no significant temporary impacts identified for this route window. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00039.




4.8 Route window W19 Anticipated groundworks Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment throughout the alignment; • The raising of Stoke Poges Lane Road Bridge and footbridge to provide sufficient

clearance for OHLE; and • Parapets work and track lowering beneath Farnham Road Bridge to accommodate the

OHLE.

Route window description Route window W19 comprises the area between Yarmouth Road and Grays Road, along the route of the current railway lines and associated sidings. Since the early 20th century this route window has been predominantly occupied by industrial and commercial premises such as workshops, garages and factories. It has undergone significant development and expansion throughout the years with more industries and trades moving into the area, to become known as Slough Trading Estate. The wider current land uses comprise university buildings, residential and retail premises. Route window setting The geology of route window W19 comprises superficial deposits (including Taplow Terrace Gravels and Brickearth) overlying the Reading Beds and Chalk. The superficial deposits in this area are likely to be between 4 and 8m thick and are classified by the Environment Agency as a major aquifer. There are two groundwater abstractions within the route window both operated by GlaxoSmithKline for industrial non-evaporative cooling processes. One abstracts from the river gravels and the other from Lower Greensand. Salt Hill Stream and the associated minor fluvial floodplain cross the route alignment 1000m to the west of Slough Station. There are no surface water abstractions within this route window. Significant sites None of the sites within this route have been assessed as having a significant impact for the Crossrail project. Temporary impacts There are no significant temporary impacts identified for this route window. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00037.




4.9 Route window W18 Anticipated groundworks

Within this route window the main Crossrail works will involve: • Upgrading of Slough station including a new bay platform, platform extensions and

modifications to the ticket halls; • A new footbridge at the western end of the station with lift access to all platforms; • Provision of a Slough goods loop; and • Introduction of overhead line equipment throughout, and changes to three road bridges to

accommodate this. Route window description Route window W18 is located between Eastbridge in the east and Grays Road to the west of the route window, along the existing GWR corridor. Bordering the rail tracks to the north of the site are various industrial units and factories with the exception of the west of the window where Slough Bus Station is located. To the south of the tracks, housing borders the rail tracks with the exception of the west of the window where a retail centre and car parks are found. Route window setting The geology of route window W18 comprises superficial deposits (Brickearth and Taplow Gravels) underlain by London Clay in the east. The dip of the strata results in the Reading Beds underlying the superficial deposits at Slough Station and to the west of the station. Four boreholes in the vicinity of Slough record the thickness of the superficial deposits as between 2 and 8 m thick. One of these boreholes is located at an engine shed at Slough Station. Here the thickness of the superficial deposits is 4.4 m and the London Clay is not present. The route alignment crosses Datchet Common Brook and the associated floodplain at the Uxbridge Road (A412). There are two groundwater abstractions within the route window. Both are licensed to GlaxoSmithKline for non-evaporative cooling. Significant sites One site has been given a medium risk classification according to the methodology, due to its previous historical usage, site visit observations and the necessity for physical groundworks during construction. Slough Station (W18-06) has been recorded in existence since 1876. It has remained at this location up until the present day, with changes having taken place to the station buildings along with expansion of the railway sidings. Potential contaminants associated with this site include ash, clinker, coal, fuel oils (above and below ground storage tanks), lubricants, general hydrocarbons and solvents, heavy metals, PCBs, PAHs, phenols, herbicides and pesticides, creosote and timber treatment products and asbestos. Temporary impacts During the groundworks, construction workers and site visitors may inhale, ingest or have dermal contact with concentrations of contamination which have the potential to cause detrimental impacts to human health. There is also the potential for construction workers to come into contact with groundwater within the superficial deposits which may contain elevated concentrations of contaminants.




Construction works have the potential to mobilise contaminants which may impact nearby surface water courses and the underlying major aquifer. However, these impacts can be mitigated through good practice during construction, soil disposal or remediation as necessary. Site investigations and quantitative risk assessments would provide further information on the level of contamination in order to refine mitigation measures, as set out in Appendix B. With such mitigation in place, the impact of these sites on the project would be reduced to non-significant levels. Permanent impacts There are no significant permanent impacts identified for this route window. Mapping All the sites assessed in this route window are shown on drawing number 1E0322-W1E00-E00-F-00035. The site which is considered to have a potentially significant impact (before mitigation) is shown on drawing number 1E0322-W1E00-E00-F-00036.




4.10 Route window W17 Anticipated groundworks Within this route window the main Crossrail works will involve: • The introduction of overhead line equipment throughout the alignment. • Bridge modifications to accommodate the OHLE. The brick arches of both Middlegreen

Road (Langley Down) bridge and St. Mary’s Road (Church Lane) bridge will be demolished and replaced with new bridge decks. Trenches footbridge will be partially demolished and a new two-span steel superstructure erected.

Route window description Route window W17 lies between the Darwin Road to the east and Eastbridge to the west, following the route of the existing GWR corridor. The railway lines are bordered to the north by various industrial parks with the exception of the far west where housing is found. To the south, the railway lines are bordered by housing along the length of the window. Route window setting The geology of the window comprises Brickearth and Gravels overlying London Clay. There are no groundwater abstractions within the route window, however almost the entire window lies on an outer SPZ associated with a Thames Water Utilities public water supply. The groundwater vulnerability map for the area shows that the route window overlies a major aquifer. The Grand Union Canal (Slough Arm) passes through the route window, running north of the route alignment. The route alignment also crosses Datchet Common Brook at the western edge of the window. Horton Brook passes through the north-east of the route window. There are no groundwater or surface water abstractions within the route window. Significant sites One site has been given a medium risk classification according to the methodology

crossrail line 1 assessment of contaminated land impacts technical report volume 1 of...

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