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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
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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.
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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
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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.
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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:
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• 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.
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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.
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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.
-
Assessment of Contaminated Land Impacts Technical Report
Mott MacDonald Ltd Cross London Rail Links Limited
13 P:\Croydon\MMH\WEM\PROJ\211152 Crossrail Conland
Assessment\final reports\1E0322-C1E00-00013.doc
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.
-
Assessment of Contaminated Land Impacts Technical Report
Mott MacDonald Ltd Cross London Rail Links Limited
14 P:\Croydon\MMH\WEM\PROJ\211152 Crossrail Conland
Assessment\final reports\1E0322-C1E00-00013.doc
4 Environmental baseline and assessment of impacts - Maidenhead
to Westbourne Park
This section comprises a review of route windows W25 to W1
-
Asse
ssm
ent o
f Con
tam
inat
ed L
and
Impa
cts
Tech
nica
l Rep
ort
Mot
t Mac
Don
ald
Ltd
C
ross
Lon
don
Rai
l Lin
ks L
imite
d
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oc
4.1
Sum
mar
y of
Wes
tern
Sec
tion
Impa
cts
R
oute
W
indo
w
Rou
te W
indo
w
Nam
e M
ain
Wor
ks
Sign
ifica
nt S
ites
His
toric
al U
se
Tem
pora
ry
Impa
cts
Perm
anen
t Im
pact
s
W25
M
aide
nhea
d S
tatio
n •
Sta
blin
g an
d tu
rnba
ck
faci
lity
• N
ew ti
cket
hal
l •
New
bay
pla
tform
and
pl
atfo
rm e
xten
sion
•
Ext
ensi
on to
exi
stin
g su
bway
•
Ove
rhea
d lin
e eq
uipm
ent
Mai
denh
ead
Sta
tion
(W
25-0
1)
Indu
stria
l Est
ate
off B
oyn
Val
ley
Roa
d (W
25-0
3 an
d W
25-0
4)
Pre
sent
sin
ce 1
876
Form
er s
idin
gs. I
ndus
trial
E
stat
e pr
esen
t sin
ce th
e m
id 1
950’
s.
• H
uman
Im
pact
•
Gro
undw
ater
•
Sur
face
wat
er
No
W23
Ta
plow
Sta
tion
• P
latfo
rm e
xten
sion
s •
Ove
rhea
d lin
e eq
uipm
ent
• Fo
otbr
idge
wor
ks
Tapl
ow S
tatio
n (W
23-0
1)
In e
xist
ence
sin
ce 1
875
• H
uman
Hea
lth
• G
roun
dwat
er
No
W21
B
urnh
am S
tatio
n •
Pla
tform
ext
ensi
ons
• O
verh
ead
line
equi
pmen
t
Bur
nham
Sta
tion
(W21
-05)
In
exi
sten
ce s
ince
192
4 •
Hum
an H
ealth
•
Gro
undw
ater
•
Sur
face
wat
er
No
W18
S
loug
h S
tatio
n •
Cha
nges
to th
e tic
ket
hall,
a n
ew fo
otbr
idge
an
d pr
ovis
ion
of li
ft ac
cess
•
Pla
tform
ext
ensi
ons
and
a ne
w b
ay p
latfo
rm
• O
verh
ead
line
equi
pmen
t •
Wor
ks to
thre
e ro
ad
brid
ges
•
Slo
ugh
Sta
tion
(W18
-06)
In
exi
sten
ce s
ince
187
6 •
Hum
an H
ealth
•
Sur
face
wat
er
• G
roun
dwat
er
No
W17
M
iddl
egre
en
Roa
d, S
t Mar
y’s
Roa
d an
d Tr
ench
es
brid
ges
• O
verh
ead
line
equi
pmen
t •
Rep
lace
men
t of
Mid
dleg
reen
Roa
d br
idge
, St.
Mar
y’s
Roa
d
Mid
dleg
reen
Tra
ding
E
stat
e –
Sta
dex
Wor
ks
(W17
-04)
Pre
sent
sin
ce 1
956
• H
uman
Hea
lth
• S
urfa
ce w
ater
•
Gro
undw
ater
No
-
Asse
ssm
ent o
f Con
tam
inat
ed L
and
Impa
cts
Tech
nica
l Rep
ort
Mot
t Mac
Don
ald
Ltd
C
ross
Lon
don
Rai
l Lin
ks L
imite
d
16
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on\M
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ross
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essm
ent\f
inal
repo
rts\1
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13.d
oc
Rou
te
Win
dow
R
oute
Win
dow
N
ame
Mai
n W
orks
Si
gnifi
cant
Site
s H
isto
rical
Use
Te
mpo
rary
Im
pact
s Pe
rman
ent I
mpa
cts
(Chu
rch
Lane
) brid
ge,
and
Tren
ches
fo
otbr
idge
La
ngle
y O
il S
tora
ge D
epot
(W
16-0
6)
Pre
sent
sin
ce 1
970,
re
cent
ly d
ecom
mis
sion
ed
W16
La
ngle
y S
tatio
n •
Ove
rhea
d lin
e eq
uipm
ent
• P
latfo
rm e
xten
sion
•
Rei
nsta
tem
ent a
nd
exte
nsio
n of
trac
k at
La
ngle
y E
ast J
unct
ion
Lang
ley
Rai
lway
Sta
tion
(W16
-03)
In
exi
sten
ce s
ince
188
1
• H
uman
Hea
lth
• S
urfa
ce w
ater
•
Gro
undw
ater
No
W15
D
og K
enne
l B
ridge
•
Ove
rhea
d lin
e eq
uipm
ent
• 1.
2km
of n
ew tr
ack
on
the
north
sid
e of
the
line
with
ass
ocia
ted
emba
nkm
ent w
iden
ing
• D
emol
ition
of D
og
Ken
nel B
ridge
•
Con
stru
ctio
n of
new
br
idge
spa
n ov
er ro
ad
adja
cent
to e
xist
ing
Che
quer
s br
idge
Hol
low
Hill
land
fill (
W15
-04)
Land
fill i
n op
erat
ion
durin
g th
e 19
60’s
•
Hum
an H
ealth
•
Sur
face
wat
er
• G
roun
dwat
er
No
W14
Iv
er S
tatio
n •
Ove
rhea
d lin
e eq
uipm
ent
• R
epla
cem
ent o
f tic
ket
offic
e •
Pla
tform
ext
ensi
on a
nd
prov
isio
n of
new
pl
atfo
rm fa
ce
• D
emol
ition
and
re
plac
emen
t of T
horn
ey
Lane
brid
ge in
clud
ing
road
real
ignm
ent
Land
fill/F
arm
land
to th
e no
rth o
f the
railw
ay *W
14-
05
Iver
Rai
lway
Sta
tion
(W
14-0
6)
Site
was
use
d as
a la
ndfil
l du
ring
the
1970
’s.
In e
xist
ence
sin
ce 1
924
• H
uman
Hea
lth
• S
urfa
ce w
ater
•
Gro
undw
ater
No
-
Asse
ssm
ent o
f Con
tam
inat
ed L
and
Impa
cts
Tech
nica
l Rep
ort
Mot
t Mac
Don
ald
Ltd
C
ross
Lon
don
Rai
l Lin
ks L
imite
d
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essm
ent\f
inal
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rts\1
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13.d
oc
Rou
te
Win
dow
R
oute
Win
dow
N
ame
Mai
n W
orks
Si
gnifi
cant
Site
s H
isto
rical
Use
Te
mpo
rary
Im
pact
s Pe
rman
ent I
mpa
cts
The
Coa
l Yar
d (W
13-1
1)
Sou
ther
n se
ctio
n oc
cupi
ed
by ra
ilway
sid
ings
from
19
34
Nor
ther
n se
ctio
n co
al y
ard
sinc
e 19
70
W13
W
est D
rayt
on
stat
ion
and
stab
ling
• N
ew s
tabl
ing
faci
lity
on
the
site
of f
orm
er W
est
Dra
yton
coa
l dep
ot
• R
ebui
lt st
atio
n at
Wes
t D
rayt
on
• P
latfo
rm e
xten
sion
s an
d tra
ck re
alig
nmen
t •
Ove
rhea
d lin
e eq
uipm
ent
Wes
t Dra
yton
Sta
tion
(W13
-01)
B
een
in e
xist
ence
sin
ce
1885
• H
uman
Hea
lth
• S
urfa
ce w
ater
•
Gro
undw
ater
No
W11
S
tock
ley
flyov
er
• N
ew v
iadu
ct a
long
the
north
sid
e of
the
railw
ay
and
new
tran
sfer
st
ruct
ures
at e
ither
end
, w
ith a
ssoc
iate
d w
orks
•
Ove
rhea
d lin
e eq
uipm
ent t
o th
e w
est
Rig
by L
ane
Indu
stria
l E
stat
e (W
11-0
2 an
d W
11-
03)
Pre
sent
sin
ce th
e ea
rly 2
0th
cent
ury.
•
Hum
an H
ealth
•
Sur
face
Wat
er
• G
roun
dwat
er
No
W10
H
ayes
and
H
arlin
gton
st
atio
n
• N
ew tr
ack
on n
orth
sid
e of
rail
corr
idor
and
ex
tens
ion
of S
tatio
n R
oad
brid
ge
• N
ew ti
cket
hal
l, fo
otbr
idge
and
lifts
•
New
pla
tform
and
pl
atfo
rm e
xten
sion
s
Hay
es &
Har
lingt
on S
tatio
n (W
10-0
2)
Pre
sent
sin
ce a
t lea
st 1
867
• H
uman
Hea
lth
• S
urfa
ce W
ater
•
Gro
undw
ater
No
W8
Sou
thal
l Sta
tion
• R
econ
stru
ctio
n of
S
outh
all s
tatio
n •
Ext
ende
d pl
atfo
rms
and
new
lifts
•
Trac
k w
orks
incl
udin
g ne
w tr
ack
Han
wel
l Sta
tion
(W8-
01)
Rai
l Sid
ings
to th
e no
rth o
f th
e ra
ilway
trac
k (W
8-02
)
Bee
n in
exi
sten
ce s
ince
18
68.
Pre
sent
sin
ce a
t lea
st
1880
.
• H
uman
Hea
lth
• G
roun
dwat
er
No
W7
Han
wel
l Sta
tion
• P
latfo
rm e
xten
sion
s W
est E
alin
g S
tatio
n
(W7-
01)
Bee
n in
exi
sten
ce s
ince
18
97
• H
uman
Hea
lth
• G
roun
dwat
er
No
-
Asse
ssm
ent o
f Con
tam
inat
ed L
and
Impa
cts
Tech
nica
l Rep
ort
Mot
t Mac
Don
ald
Ltd
C
ross
Lon
don
Rai
l Lin
ks L
imite
d
18
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royd
on\M
MH
\WEM
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OJ\
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ross
rail
Con
land
Ass
essm
ent\f
inal
repo
rts\1
E03
22-C
1E00
-000
13.d
oc
Rou
te
Win
dow
R
oute
Win
dow
N
ame
Mai
n W
orks
Si
gnifi
cant
Site
s H
isto
rical
Use
Te
mpo
rary
Im
pact
s Pe
rman
ent I
mpa
cts
W6
Wes
t Eal
ing
Sta
tion
• R
epla
cem
ent o
f the
tic
ket h
all n
ew
over
brid
ge a
nd li
fts
• N
ew b
ay p
latfo
rm
• P
latfo
rm e
xten
sion
s
Eal
ing
Bro
adw
ay S
tatio
n (W
6-01
) B
een
in e
xist
ing
loca
tion
sinc
e 18
75.
• H
uman
Hea
lth
• G
roun
dwat
er
No
W5
Eal
ing
Bro
adw
ay
Sta
tion
• R
epla
cem
ent o
f the
tic
ket h
all
• P
latfo
rm e
xten
sion
s
Rai
lway
Sid
ings
alo
ng
Act
on m
ain
Line
(W5-
02)
Rai
lway
sid
ings
sin
ce a
t le
ast 1
896.
•
Hum
an H
ealth
•
Gro
undw
ater
N
o
W4
Act
on M
ain
Line
st
atio
n an
d ya
rd
• N
ew ra
il un
derp
ass
wes
t of A
cton
Yar
d •
New
tick
et h
all
• N
ew fo
otbr
idge
•
Pla
tform
ext
ensi
ons
and
new
lifts
Act
on Y
ard
(W4-
02)
Act
on S
tatio
n (W
4-06
)
Rai
lway
sid
ings
reco
rded
in
exis
tenc
e si
nce
at le
ast
1896
. P
rese
nt s
ince
at l
east
189
6
• H
uman
Hea
lth
No
W3
Old
Oak
C
omm
on d
epot
•
Fifte
en n
ew s
tabl
ing
sidi
ngs
• C
arria
ge w
ashi
ng
faci
lity
and
crew
ac
com
mod
atio
n
Old
Oak
Com
mon
(W3-
05)
Rai
lway
dep
ot a
nd s
idin
gs
sinc
e 18
70
• H
uman
Hea
lth
• S
urfa
ce w
ater
N
o
-
Assessment of Contaminated Land Impacts Technical Report
Mott MacDonald Ltd Cross London Rail Links Limited
19 P:\Croydon\MMH\WEM\PROJ\211152 Crossrail Conland
Assessment\final reports\1E0322-C1E00-00013.doc
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
-
Assessment of Contaminated Land Impacts Technical Report
Mott MacDonald Ltd Cross London Rail Links Limited
20 P:\Croydon\MMH\WEM\PROJ\211152 Crossrail Conland
Assessment\final reports\1E0322-C1E00-00013.doc
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.
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Assessment of Contaminated Land Impacts Technical Report
Mott MacDonald Ltd Cross London Rail Links Limited
21 P:\Croydon\MMH\WEM\PROJ\211152 Crossrail Conland
Assessment\final reports\1E0322-C1E00-00013.doc
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.
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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
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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