appendix 1a - cover sheet · the local councils and railtrack (now nr). hertfordshire county...

Croxley Rail Link Environmental Statement

Appendix 1A © Mouchel 2011

Appendix 1A Introduction - Request for Screening Decision and Scoping Opinion

http://dmportal/clients/HH/31541/Matters_00000_00099/00001/120511130555.DOC

Croxley Rail Link

Request for an Environmental

Impact Assessment Screening

Decision and Scoping Opinion

11 May 2011

Produced for

Secretary of State for Transport

Prepared by

Mouchel Limited

Export House

Cawsey Way

Woking

Surrey

GU21 6QX

UK

T +44 (0) 1483 731372

F +44 (0) 1483 731003

www.mouchel.com

© Mouchel 2011

1020783http://dmportal/clients/HH/31541/Matters_00000_00099/00001/120511130555.DOC

i

Document Control Sheet

Project Title Croxley Rail Link

Report Title Request for an Environmental Impact Assessment Screening

Decision and Scoping Opinion

Revision Final

Status Issue

Control Date 11 May 2011

Record of Issue

Issue Status Author Date Check Date Authorised Date

1 Draft D Wright 22.03.11 P Reid 24.03.11 P Reid 25.03.11

2 Final D Wright 14.04.11 P Reid 15.04.11 P Reid 15.04.11

3 Final D Wright 14.04.11 R Beaumont 27.04.11 A Dawes 7.05.11

Final D Wright 14.04.11 R Beaumont 11.05.11 A Dawes 11.05.11

Distribution

Organisation Contact Copies

Winckworth Sherwood Paul Irving 1e

Winckworth Sherwood Hazel Anderson 1e

Secretary of State

© Mouchel 2011


ii

Disclaimer: This report is presented to the Secretary of State for Transport in

respect of the proposed Croxley Rail Link and may not be used or relied on by any

other person or by the client, Hertfordshire County Council, in relation to any other

matters not covered specifically by the scope of this report.

Notwithstanding anything to the contrary contained in the report, Mouchel is obliged

to exercise reasonable skill, care and diligence in the performance of the services

required by the client, Hertfordshire County Council, and Mouchel shall not be liable

except to the extent that it has failed to exercise reasonable skill, care and diligence,

and this report shall be read and construed accordingly.

This report has been prepared by Mouchel. No individual is personally liable in

connection with the preparation of this report. By receiving this report and acting on

it, the client or any other person accepts that no individual is personally liable

whether in contract, tort, for breach of statutory duty or otherwise.

© Mouchel 2011


iii

Contents

Document Control Sheet ............................................................................................. i

Contents ..................................................................................................................... iii

Figures ......................................................................................................................... v

Tables .......................................................................................................................... vi

Abbreviations ............................................................................................................ vii

1 Introduction ........................................................................................................ 9

2 Description of the Proposed Development .................................................... 11

2.1 The Purpose of the Scheme ............................................................................... 11

2.2 The Nature of the Scheme ................................................................................. 11

2.3 Assessment Area ............................................................................................... 13

3 Potential Environmental Impacts and Proposed Assessments .................... 15

3.1 Legislative Context ............................................................................................. 15

3.2 Previous Studies ................................................................................................ 15

3.3 Air Quality .......................................................................................................... 18

3.4 Cultural Resources and Heritage ....................................................................... 22

3.5 Ecology and Nature Conservation ...................................................................... 23

3.6 Geology, Soils and Contaminated Land ............................................................. 27

3.7 Landscape Character and Visual Context .......................................................... 29

3.8 Noise and Vibration ............................................................................................ 32

3.9 Surface Waters, Groundwater, Flood Risk and Drainage ................................... 35

© Mouchel 2011


iv

3.10 Traffic and Transport .......................................................................................... 39

3.11 Community and Socio-Economic Effects ............................................................ 39

3.12 Cumulative Effects ............................................................................................. 39

3.13 Policies and Plans .............................................................................................. 41

4 Proposed Environmental Statement Structure .............................................. 42

5 References ........................................................................................................ 44

© Mouchel 2011


v

Figures

Figure 1 - Croxley Rail Link Route Plan…………………………………………………47

Figure 2 - Croxley Rail link Cultural Heritage and Archaeological Sites……………..48

Figure 3 - Croxley Rail Link Flood Map………………………………………………….49

© Mouchel 2011


vi

Tables

Table 3.1 - Potential Interactions between Environmental Resources and Receptors ........... 16

© Mouchel 2011


vii

Abbreviations

ADM Advanced Dispersion Modelling

AQMA Air Quality Management Area

BAFB Best and Final Offer Bid

BRE Building Research Establishment

BTO British Trust for Ornithology

CIRIA Construction Industry Research and Information Association

CRN Calculation of Railway Noise

Defra Department of Environment, Food and Rural Affairs

DMRB Design Manual for Roads and Bridges

DoE Department of Environment

EHO Environmental Health Officer

EIA Environmental Impact Assessment

EOI Expression of Interest

ES Environmental Statement

FAQ Frequently Asked Questions

GCN Great Crested Newts

GLVIA Guidelines for Landscape and Visual Impact Assessment

HCC Hertfordshire County Council

IEMA Institute of Environmental Management and Assessment

LAQM Local Air Quality Management

LUL London Underground Limited

MAGIC Multi-Agency Geographic Information for the Countryside

NAQIA National Air Quality Information Archive

© Mouchel 2011


viii

NBN National Biodiversity Network

NO2 Nitrogen Dioxide

NOx Nitrogen Oxides

NR Network Rail

PM10 Particulate Matter

PPS Planning Policy Statement

PRA Preliminary Risk Assessment

QUARG Quality of Urban Air Review Group

SSSI Site of Special Scientific Interest

TfL Transport for London

TRDC Three Rivers District Council

TWA Transport and Works Act 1992

WBC Watford Borough Council

© Mouchel 2011


9

1 Introduction

The Croxley Rail Link was first proposed more than 30 years ago to link the Watford

Branch of the London Underground Limited (LUL) Metropolitan Line with Watford

Junction Railway station via the disused Network Rail (NR) Croxley Green Branch

Line. The scheme has for many years been embodied within the relevant structure

and local plans.

The development of the scheme was formerly led by LUL who aimed to promote the

construction of the rail link and operate the resulting service. Preliminary design and

assessment work was undertaken in the late 1990s and early 2000s. However, for a

number of reasons the scheme development did not proceed. In spring 1997 LUL

announced that, although it remained committed to the project, it was unable to

proceed with the scheme on its own and would require funding and assistance from

the local councils and Railtrack (now NR).

Hertfordshire County Council (HCC) subsequently took over the lead in promoting

the proposed scheme with support from LUL, NR, Watford Borough Council (WBC)

and Three Rivers District Council (TRDC).

A decision was taken in July 2009 to re-examine the scheme and design and

assessment work was subsequently commissioned by HCC. HCC is leading the

development of the scheme in its current form and is responsible for managing the

project with the involvement of LUL and NR. Steer Davis Gleave are assisting HCC

to develop the business case and are undertaking a traffic assessment. Mouchel

have been appointed to undertake the engineering design, land referencing,

geotechnical investigation, stakeholder consultation, environmental assessment and

equality impact assessment. Acanthus LW Architects are undertaking the station

outline designs and Winckworth Sherwood are the parliamentary agents.

Work on the various streams progressed until the announcement of the

Comprehensive Spending Review (CSR) in October 2010 when efforts were scaled

back. Following the CSR, the Department for Transport (DfT) invited Expressions of

Interest (EOI) from major scheme promoters to evaluate proposals for schemes

seeking further development support. HCC submitted an EOI in December 2010

and was informed in February 2011 that the scheme had been selected for

advancement to the Development Pool. This pool includes schemes that the DfT will

take forward for further analysis. In association with this, the DfT is seeking

improved funding bids (referred to as a „Best and Final Bid‟ (BAFB)) from Local

Authorities to assist in the selection of schemes that will receive further DfT support.

BAFBs are to be submitted to the DfT by 9 September 2011 and decisions will be

made by the DfT by the end of 2011 on those schemes that will receive a reactivated

„Programme Entry‟ approval.

In conjunction with the funding support initiatives, HCC is also seeking an order

under Part 1 of the Transport and Works Act 1992 (TWA)i to authorise the

© Mouchel 2011


10

construction of the proposed scheme. Under rule 7 of the Transport and Works

(Applications and Objections Procedure) (England and Wales) Rules 2006 (SI 2006

No. 1466)ii, it is stated that an Environmental Statement (ES) must be provided with

all TWA orders unless the order would: i) not authorise a project of a type mentioned

in Annex I or Annex II of EU Directive 85/337. The Assessment of the Effects of

Certain Public and Private Projects on the Environment as amended by Directive

97/11/EC; or ii) authorise a project covered by Annex II to the Directive but which the

Secretary of State has decided (by means of a „Screening Decision‟) would not have

a significant environmental impact; or iii) authorise a project serving national defence

purposes.

It is understood that at any time prior to the making of a TWA application, a request

may be made to the Secretary of State for a Screening Decision as to whether or not

an Environmental Impact Assessment (EIA) is required. In addition, it is understood

that, under rule 8, an applicant may request that the Secretary of State give a

Scoping Opinion as to the information to be provided in an ES should the scheme be

deemed to require an EIA. This report has therefore been prepared in support of a

combined request for a Screening Decision and a Scoping Opinion in accordance

with TWA rule 8(7).

The objective of this report is firstly to establish whether an EIA is required for the

proposed Croxley Rail Link scheme. Based on a review of the legislative

requirements and the nature of the proposed development, it is the applicant‟s view

that an EIA will be required. If this view is confirmed by the Secretary of State

following a Screening Decision, a further objective of this report is to seek a Scoping

Opinion. To assist in this process, the assessments which the applicant considers

should be undertaken and reported in an ES have been described in Section 3.

These have been identified from a review of known data and, in some cases, site

surveys relating to the existing environment associated with the site and the wider

area, as well as a review of anticipated construction activities and the future

operation of the scheme.

This report includes the following information as required under the TWA rules 7(5)

for a screening request and 8(2) for a scoping request:

a plan identifying the land affected by the proposed scheme (see Figure 1 in

Appendix A);

a brief description of the nature and purpose of the scheme (see Section 2);

and

a brief description of the possible effects on the environment of the works (see

Section 3).

© Mouchel 2011


11

2 Description of the Proposed Development

2.1 The Purpose of the Scheme

The overall objective of the proposed scheme is to improve the transport

connections from the surrounding areas to Watford Junction, Central London and the

NR network and to reduce the adverse effects of traffic congestion in Watford. With

regard to rail services, passengers to the west of the proposed scheme area are

required to travel south to Central London to access the NR network and passengers

to the east do not currently have ready access to the LUL network. There is currently

no main road network leading directly south from West Watford. This results in road

traffic having to enter Central Watford in order to access southbound routes. In

addition, insufficient east-west public transport services result in greater car

journeys.

The three primary objectives of the scheme are:

To enhance sustainable links to and between residents and employment,

business, education, health and leisure opportunities within Watford and

across Hertfordshire, and to key external attractors, notably North West and

Central London and the National Rail Network, thus reinforcing Watford‟s role

as a key transport hub of London;

To promote economic and housing development by improving public transport

linkages between current and potential employees, Watford town centre and

key development areas of Watford Junction, Watford Business Park/Ascot

Road and the Watford Health Campus; and

To provide a credible alternative to car travel, with inherently lower

environmental impacts per trip, including reduced noise and greenhouse gas

emissions.

2.2 The Nature of the Scheme

The proposed scheme would be constructed in south west Hertfordshire within the

administrative boundaries of Watford Borough Council (WBC) and Three Rivers

District Council (TRDC). Figure 1 in Appendix A shows the route of the proposed

scheme.

The proposed development area is situated in an urban setting, comprising mainly

Victorian and early-Edwardian dwellings with some light industry. The surrounding

area contains several commercial properties and small industrial estates (including

Cinnamond Contracts Limited and the industrial estate to the east of Wiggenhall

Road, ) Watford General Hospital, nine schools (Watford Grammar School for Boys,

St Anthony‟s Roman Catholic Primary School, Westfield Community Technology

College, Chessbrook Education Support Centre, Haines Laurance School, Field

Infant School and Nursery, Field Junior School, Watford Grammar School for Girls

and Central Primary), Watford Football Club at Vicarage Stadium, business park,

recreation grounds (playground next to Watford Road, Riverside Park, Harwoods

© Mouchel 2011


12

Recreation Ground and Waterfields Recreation Ground), a care home for the elderly

(Chase Care Centre) and allotments.

The Grand Union Canal, the River Gade and the River Colne pass under the

proposed alignment. Hertfordshire Metropolitan Green Belt lies to the western edge

of the proposed scheme and continues along a narrow corridor which follows the

River Gade and the Grand Union Canal. Lairage Land Local Nature Reserve is

adjacent to the proposed scheme to the east of Vicarage Road. The Colne Valley

Linear Park, located to the south of Watford High Street station, is adjacent to the

functional Network Rail line. The Croxley Common Moor Site of Special Scientific

Interest (SSSI), notified under Section 28 of the Wildlife and Countryside Act 1981, is

located approximately 900m to the south west of the proposed scheme.

As shown on Figure 1, the proposed scheme would involve the extension of the LUL

Metropolitan Line to Watford Junction station via the disused Croxley Branch Line

which is currently owned by NR. In order to connect the Metropolitan Line and the

Croxley Branch Line, the construction of a new viaduct would be required south of

the existing Watford station, which is known as Watford Met station. The reinstated

Croxley Branch Line would connect into the existing London Overground DC line to

the south of the existing Watford High Street station and Metropolitan Line trains

would share the line to Watford Junction station.

Key aspects of the scheme include the following:

A new embankment and viaduct of approximately 0.4km in length and ranging

from 9m to 13m in height would connect the existing Metropolitan Line to the

disused Croxley Branch Line.

Two new stations would be constructed: one at Ascot Road with park and ride

facilities which would replace the former Croxley Green station and the second

at Vicarage Road, referred to as Watford General Hospital station which would

replace the former Branch Line Watford West and Watford Stadium stations.

The service would also be served by the existing operational rail stations at

Watford High Street and Watford Junction.

Watford Met station would be closed.

The extended Metropolitan Line service would share the track and station

access with the existing London Overground line services which operate

between Watford Junction and London Euston.

The length of new dual-track railway added to the existing Metropolitan Line

would be approximately 4.5km. If the closure of Watford Met station is

considered, there would, however, be a loss of approximately 1.3km. This

would result in a net increase of operating track length of approximately 3.2km.

Most of the land required for the scheme is already in the ownership of scheme

supporters: NR, TRDC or WBC or HCC itself and only land for the new viaduct

would require acquisition of a limited amount of third party land.

© Mouchel 2011


13

An additional rolling stock unit would be brought into operation deliver the

extended services.

2.3 Assessment Area

The proposed development area can be divided into four sections, as follows:

Proposed viaduct to link the new scheme with the existing LUL Metropolitan

Line and a new station at Ascot Road to the west of the development area;

Closure of Watford Met station with the line likely to remain open for LUL

operational requirements (e.g. for access to signalling and communications

equipment);

Reinstatement and development of the disused Croxley Branch Line, new

Watford General Hospital station to the west of Vicarage Road and a link to the

existing London Overground DC line to the east of Wiggenhall Road; and

Dual running on the current London Overground DC line through Watford High

Street station to Watford Junction station to the east of the development area.

References to the scheme / development area within this report are made in relation

to the scheme footprint and include the land which will be disturbed during

construction and / or used as a part of the operational scheme. References to the

study area are made in relation to the land surveyed as part of the wider area study,

with specific boundaries set by each specialist discipline assessment team based

upon experience and given the nature of the scheme and thus the potential extent of

impacts.

2.3.1 Viaduct Link with London Underground Limited Metropolitan Line and Ascot Road

Development

To the west, the proposed viaduct to link the existing Metropolitan Line with the

proposed new development and the new station at Ascot Road would require the

acquisition of approximately 0.7ha of land, plus additional temporary land take for

construction. A bridge and embankment structural arrangement would link the

viaduct to the disused rail corridor.

The HCC-owned former waste transfer station on Ascot Road is proposed to be

developed as a car park and is likely to serve as the main construction site

compound for the scheme. Further temporary site compounds may be required to

erect the foundations and/or piling for the viaduct.

Desk-based assessments and site surveys in this area have been or will be

conducted along the scheme development boundary area and, where indicated in

Section 3, beyond the scheme boundary in certain instances where wider

information is required (e.g. ecological surveys, air quality assessments,

archaeological assessments, etc.).

© Mouchel 2011


14

2.3.2 Watford Met Station Closure

As mentioned in the previous section Watford Met station would be closed to

passenger services. The line is likely, however, to remain open to for operational

purposes to access signalling and communications equipment located next to the

station.

2.3.3 Reinstatement of Disused Croxley Branch Line and New Watford Health Campus

Station

The central development area would be confined to the disused rail corridor owned

by NR. Construction in this area is likely to be confined to the rail corridor and would

be serviced by the proposed site compound at Ascot Road. Desk-based

assessments and site surveys in this area have been or will be conducted along the

disused rail corridor and, where indicated in Section 3, beyond the corridor in certain

instances where wider information is required.

2.3.4 Dual Running with Existing London Overground DC Line

The development area to the east of the scheme through Watford High Street station

through to Watford Junction station would be primarily confined to the existing

London Overground rail corridor with the possibility of a requirement for temporary

site compounds during construction. Desk-based assessments and site surveys in

this area have been or will be conducted along the existing rail corridor and, where

indicated in Section 3, beyond the scheme boundary in certain instances where

wider information is required.

© Mouchel 2011


15

3 Potential Environmental Impacts and Proposed Assessments

3.1 Legislative Context

EU Directive 85/337iii on the Assessment of the Effects of Certain Public and Private

Projects on the Environment, as amended by Directive 97/11/EC, sets out the

requirement for environmental impact assessment to be carried out, before

development consent is granted, for certain types of major project which are judged

likely to have significant environmental effects. Under the Directive, projects are

listed under Annex I and Annex II according to the development activities. Projects

listed in Annex I are subject to an assessment in accordance with Articles 5 to 10 in

all cases and those listed in Annex II are to be determined by the Member States

through a case-by-case examination or thresholds or criteria set by the Member

State. The relevant selection criteria are set out in Annex III of the Directive.

The Transport and Works Act 1992 (TWA) enables orders to be made authorising

the construction and operation of railways, tramways, other guided transport systems

and inland waterways; and works interfering with rights of navigation. The

procedures for making applications for orders under Part 1 of the TWA are contained

in the Transport and Works (Applications and Objections Procedure) (England and

Wales) Rules 2006 (SI 2006 No. 1466) (the Applications Rules) which also

implement the EIA Directive through rule 11 and Schedule 1.

As stated previously in Section 1, as provided in rule 7 of the Applications Rules, an

ES must be provided with all TWA orders unless the order would: i) not authorise a

project of a type mentioned in Annex I or Annex II of EU Directive; or ii) authorise a

project covered by Annex II to the Directive but which the Secretary of State has

decided (by means of a „Screening Decision‟) would not have a significant

environmental impact; or iii) authorise a project serving national defence purposes.

Schedule 1 of the TWA Application rules sets out the type of information to be

included in an ES.

Should the proposed Croxley Rail Link scheme be deemed to fall under the projects

listed in the EIA Annex I or Annex II of the Directive, the objective of this report is to

request a Screening Decision to confirm that an EIA is required and if so, to request

that the Secretary of State give a Scoping Opinion as to the particular information to

be provided in the ES.

3.2 Previous Studies

An EIA was undertaken in 1995 for a rail scheme that was very similar in terms of

alignment to the Croxley Rail Link scheme that is currently being proposed. The

results were presented in an Environmental Statement (ES) entitled Croxley Rail

Link Environmental Statement - Volume 1 - Aspinwall & Company Limitediv. A

further EIA was completed by Mouchel in 2001 and an ES was produced entitled

Croxley Rail Link Environmental Impact Statement - Mouchel Consulting Limitedv.

Some sections of the ES were subsequently revised in 2004. However, for a

© Mouchel 2011


16

number of reasons the scheme did not proceed and a revised ES was not

completed.

As part of the current assessment, the findings of the previous EIAs that relate to the

current scheme, as well as an evaluation of current data and recent site surveys

have been reviewed to identify potential impacts. Table 3.1 provides an initial

indication of potential interactions between components and activities associated

with the construction and future use of the proposed scheme.

The star ratings of 1-3 provide an initial indication of the potential for interaction that

could result in impact. A rating of one star is indicative of potentially low interaction

and a rating of three of potentially high interaction.

The table is followed by a description of the potential impacts associated with the

various aspects. Areas where assessment is considered to be required are

identified with an outline of the proposed scope of the assessments proposed should

it be confirmed that an EIA is required following the Screening Decision.

Table 3.1 - Potential Interactions between Environmental Resources and Receptors

Environmental Aspects

Air

Qua

lity

Cultu

ral H

eri

tag

e a

nd

Arc

ha

eo

log

ica

l R

eso

urc

es

Eco

log

y a

nd

Natu

re

Con

se

rva

tio

n

Ge

olo

gy,

Soils

an

d

Con

tam

ina

tio

n

La

ndscap

e C

ha

racte

r an

d

Vis

ual C

on

text

Nois

e a

nd

Vib

ratio

n

Su

rfa

ce

Wa

ters

, F

loo

d

Ris

k a

nd

Dra

inag

e

Po

pu

lation

and

Co

mm

unity

Eff

ects

La

nd

Use

Use

of R

esou

rce

s

Cum

ula

tive

Im

pacts

Po

licie

s a

nd

Pla

n

Construction Phase Geotechnical

and

topographical

site

investigations

* ** ** * * * ** *

Site

clearance

including

demolition of

existing rail

infrastructure

(eg.

platforms),

advanced

works and re-

profiling

**

**

***

**

***

***

*

**

*

***

**

*

Earthworks,

ground ** ** *** ** * *** * * * *** *** *

© Mouchel 2011


17


Air

Qu

alit

y

Cu

ltu

ral H

eri

tag

e a

nd

Arc

ha

eo

log

ica

l R

eso

urc

es

Eco

log

y a

nd

Natu

re

Co

nse

rva

tio

n

Ge

olo

gy,

Soils

an

d

Co

nta

min

atio

n

La

ndscap

e C

ha

racte

r an

d

Vis

ual C

on

text

No

ise

an

d V

ibra

tio

n

Su

rfa

ce

Wa

ters

, F

loo

d

Ris

k a

nd

Dra

inag

e

Po

pu

lation

and

Co

mm

unity

Eff

ects

La

nd

Use

Use

of R

esou

rce

s

Cu

mu

lative

Im

pacts

Po

licie

s a

nd

Pla

n

excavations,

laying of

foundations

and

stockpiling

Establishment

of site

compound

and

associated

construction

infrastructure

** * ** * *** ** ** * * * ** *

Strengthening

and widening

of existing

infrastructure

(bridges &

culverts)

* ** ** ** * *** * * * *

Development

of viaduct

infrastructure * * ** ** *** ** * ** * * * *

Movement of

plant and

vehicles ** * * * * *** * * * * *

Landscaping

and

temporary

lighting

* ** * ** * * * * * * *

Operational Phase Rail traffic

operating on

the line * * **

Closure of

Watford Met

station ** ** ***

Disturbance

to local

population * *

© Mouchel 2011


18


Air

Qu

alit

y

Cu

ltu

ral H

eri

tag

e a

nd

Arc

ha

eo

log

ica

l R

eso

urc

es

Eco

log

y a

nd

Natu

re

Co

nse

rva

tio

n

Ge

olo

gy,

Soils

an

d

Co

nta

min

atio

n

La

ndscap

e C

ha

racte

r an

d

Vis

ual C

on

text

No

ise

an

d V

ibra

tio

n

Su

rfa

ce

Wa

ters

, F

loo

d

Ris

k a

nd

Dra

inag

e

Po

pu

lation

and

Co

mm

unity

Eff

ects

La

nd

Use

Use

of R

esou

rce

s

Cu

mu

lative

Im

pacts

Po

licie

s a

nd

Pla

n

during

Watford

Football Club

and Saracens

events at

Vicarage

Road

Stadium

Onsite and

catchment

flooding * *** * *

3.3 Air Quality

Emissions to the atmosphere would be generated from a number of construction and

operational aspects of the scheme. During construction, dust and emissions from

construction plant and vehicles would be emitted. During the operational phase,

local emissions would be generated from traffic movements.

3.3.1 Existing Environment

Background concentrations of the key indicator pollutants nitrogen dioxide (NO2) and

particulates in the form of PM10 in the vicinity of the scheme1 are 22.3 µg/m3 and

20.4 µg/m3, respectively, and are well within current National Air Quality human-

health based annual objective limits of 40 µg/m3 for the opening year (2016). There

are six Air Quality Management Areas (AQMAs) within WBC, three of which have

been identified by the Environmental Health Officer at WBC as being located within

close proximity to the scheme. The AQMAs along Vicarage Road, Pinner Road and

Aldenham Road are within approximately 280, 850 and 900m to the north west and

south east of the proposed scheme, respectively.

WBC‟s Air Quality Progress Report (2008)vi highlights that local air quality monitoring

trends between 1999 and 2007 were static or decreasing and, other than two sites

that are already within an existing Air Quality Management Area, the national

1 Based on data derived from the National Air Quality Information Archive (NAQIA) 2004

estimates at grid reference (X 059500, Y 195500).

© Mouchel 2011


19

objectives are not being exceeded. The Progress Report also highlighted that there

were no new Part A12 or Part A23 processes authorised in the Borough of Watford

since the 2005 Progress Report. Ten new Part B4 processes were authorised.

However, these were small scale and operating within their permit conditions and

therefore would not have any significant effect on air quality.

3.3.2 Potential Impacts

The proposed scheme is predicted to have a potential impact on the following:

Concentrations of NO2, PM10 and levels of dust deposition/soiling from

construction activities and construction plant in the vicinity of the proposed

development site;

Concentrations of NO2 and PM10 during the operational phase in the vicinity of

the proposed development site due primarily to traffic;

Air quality within the nearby Air Quality Management Area (AQMA); and

Regional emissions of oxides of nitrogen (NOX), PM10 and total carbon (C).

Potential sensitive receptors include residential properties, particularly those located

along Vicarage Road, Pinner Road and Aldenham Road and also within the vicinity

of the new proposed Ascot Road station and car park development, as well as

Watford General Hospital and nearby schools.

3.3.3 Surveys and Assessment

The most significant local impacts of the scheme are likely to be associated with

traffic and as such the Design Manual for Roads and Bridges (DMRB) Volume 11,

Section 3, Part 1 HA207/07 Air Qualityvii would apply. In accordance with this

guidance, a „staged‟ approach to air quality assessment is proposed. This involves

three levels of assessment: Scoping; Simple and Detailed.

The Scoping Level assessment will determine whether changes in traffic associated

with the proposed development are significant in terms of their potential influence on

air quality. It is anticipated that this will be the case (either locally beneficial or

adverse) during construction and operation.

The proximity of the three AQMAs, particularly along Vicarage Road, and the

existence of complex junctions within the study area mean that the minimum work

required is likely to be a Scoping and Detailed Level Assessment.

2 The A1 system is controlled by the Environment Agency under the Pollution Prevention and

Control Regulations

3 The A2 system is Local Authority Integrated Pollution Prevention and Control (LA-IPPC)

4 The Part B system is known as Local Authority Pollution Prevention and Control (LAPPC)

© Mouchel 2011


20

Local monitoring data is required to verify ADMS Roads dispersion modelling

calculations at the Simple Level as well as at the Detailed Level if this stage of

assessment is required. Based on previous assessments in the area, it is known that

there is insufficient local monitoring data available to conduct model verification. As

such, a six month NO2 diffusion tube monitoring programme was undertaken from

August 2009 to January 2010 in consultation with the Environmental Health Officers

(EHO) at WBC and TRDC.

The proposed approach to assessment has been divided into three distinct tasks as

follows:

3.3.3.1 Scoping Level Assessment

Formal consultation with EHOs at WBC and TRDC to discuss the methodology

for the assessment;

Review of estimated background pollutant concentrations available online at

the National Air Quality Information Archive (NAQIA) to determine existing air

quality in and around the proposed development site;

Desk study to establish the location of any receptors that may be sensitive to

changes in air quality (e.g. schools, hospitals, homes for the elderly, residential

property, etc.);

Review of local industrial sources of air pollution and industrial sensitive

receptors;

Screening of traffic data to identify „affected roads‟ and other locations most

likely to experience a change in air quality; and

Quantification (non-verified) of the proposed development‟s potential road

traffic impacts on local air quality at worst-case receptors, using the DMRB

Screening Assessment methodology and ADMS Roads dispersion model.

3.3.3.2 Simple Level Assessment

Qualitative assessment of the effects of construction impacts on local air

quality based on a review of relevant publications and guidance from the

Building Research Establishment (BRE), the Quality of Urban Air Review

Group (QUARG), Department of Environment (DoE), and the Local Authorities

bordering the area to provide a generic assessment of the effects during

demolition, site clearance and landscaping on levels of dust deposition/soiling

and PM10 concentrations at local sensitive locations;

Verification of the initial ADMS Roads scoping calculations and calculations at

additional „representative‟ locations;

Where necessary, assessment of significance of any potential adverse or

beneficial air quality impacts of the proposed development during the

construction and operation phase and recommendation of suitable

mitigation/enhancement measures that could be applied; and

© Mouchel 2011


21

Where necessary, assessment of the significance of any predicted residual

impacts which could exist post the implementation of recommended

mitigation/enhancement measures.

It is not anticipated that this assessment will require an evaluation of air quality

impacts on sensitive ecosystems. However, this is currently being reviewed as part

of the initial desk-based study and data gathering exercise.

3.3.3.3 Detailed Level Assessment

This level of assessment is required where:

The Scoping Level assessment indicates that the scheme is within, or will

affect an AQMA; or

The Scoping Level assessment shows Affected Roads, but the situation is too

complex to model with the DMRB empirical spreadsheet model; or

The Scoping Level Assessment calculations (non-verified) indicate an

exceedance of the annual mean National Air Quality Objective5 for NO2 or

PM10; or

The Simple Level assessment calculations (verified) indicate an exceedance of

the annual mean National Air Quality Objective for NO2 or PM10

The tasks required for a Detailed Level Assessment include:

A quantitative assessment of the proposed scheme‟s potential road traffic

impacts on local air quality using Advanced Dispersion Modelling (ADMS-

Roads);

Assessment of significance of any potential adverse or beneficial air quality

impacts of the proposed scheme during the construction and operational

phases and recommendation of suitable mitigation/enhancement measures

that could be applied; and

Assessment of the significance of any predicted residual impacts which could

exist post the implementation of recommended mitigation/enhancement

measures.

It should be noted that the level of assessment required (and outlined above in terms

of „Scoping‟, „Simple‟ or „Detailed‟) will not be determined until traffic data are

received and initial assessment is underway. However, as noted above, due to the

close proximity to AQMAs within the Borough, it is likely that a Detailed Level of

assessment will be required.

5 Policy targets often expressed as a maximum ambient concentration not to be exceeded,

either without exception or with a permitted number of exceedences, within a specified

timescale.

© Mouchel 2011


22

3.3.4 Guidance on Assessing Emissions from Locomotives

According to the 2009 air quality guidance document „Local Air Quality Management‟

(LAQM.TG.09)viii and the FAQ (2009) „Guidance on Assessing Emissions from

Diesel Locomotives Railway Emissions‟ix, emissions from moving and stationary

rolling stock are not required to be assessed as part of this air quality assessment for

the proposed scheme. This is due to the fact that Watford does not have

background concentrations greater than 25 µg/m3 across the Borough, which has

been deemed as the threshold for which an assessment of emissions is required6. In

addition, since the LUL trains are electric rather than diesel powered, the specific

trigger for assessment defined by the Department of Environment, Food and Rural

Affairs (Defra) as „a high number of diesel locomotives stationary for more than 15

minutes, three times a day‟ is not expected to be an issue.

3.4 Cultural Resources and Heritage

Potential significant effects on the cultural heritage resource relate to possible

disturbance of unknown buried archaeology, scheduled monuments or listed

buildings during construction works, and the potential impact on the setting of listed

buildings and conservation areas during construction and operation.


The study area encompasses a 200m corridor either side of the scheme

development boundary. The study area was selected to reflect the area over which

the historic environment may change as a result of the proposed scheme and,

although data collection focused on this area, relevant sites outside of this corridor

have also been included (see Figure 2 in Appendix A). Within the study area there

are 27 listed buildings, three conservation areas, 72 known archaeological

monuments and 19 records of archaeological interventions.


There is potential for impacts on any below-ground archaeological remains in areas

where it is proposed to undertake intrusive construction activities such as piling.

These include the area surrounding the proposed viaduct and locations along the

length of the disused rail corridor where cuttings or extensive groundworks are

proposed. Piling activities may impact upon archaeological and paleo-environmental

remains located within peat and river terrace gravel deposits. A number of railway

bridges recorded in the Hertfordshire Historic Environment Record such as Ascot

Road and Beggars Bush Lane bridges will be demolished as part of the scheme

proposals.

6 Watford is not included within Table 2 of FAQ (2009) „Guidance on Assessing Emissions

from Railway Locomotives‟ - „Authorities with rail lines with a heavy traffic of diesel passenger

trains where the estimated annual mean background nitrogen dioxide concentration (in 2008)

is greater than 25 µg/m3‟.

© Mouchel 2011


23

Possible adverse impacts may be caused in relation to listed buildings, existing

stations, bridges, Roman roads, former tracks, a parish boundary, and prehistoric

and/or palaeo-environmental deposits within the River Gade valley, with possible

beneficial impacts upon the setting of Cassiobury Park.


In order to complete the cultural heritage assessment of the proposed development,

the following key tasks have been or are currently being undertaken:

Review of relevant work on cultural heritage from the previous EIAs and a

report entitled Croxley Rail Link – Archaeological Desk-Based Assessment,

Report No. 268, 2002‟x produced by Network Archaeology Limited Croxley

Archaeological Desk Based Assessment report prepared by Network

Archaeology;

Initial consultation with the County Archaeologist and Conservation Officer to

confirm the scope of the assessment and to obtain any relevant information

they may have concerning the development area;

Collection of baseline data from the following sources:

Local records/museums

Historic Environment Records

National Monument Records

Historic maps and relevant cartographic sources

Relevant documentary records

Rail archives from NR, LUL, Railway Heritage Trust and others

Site walkover of the proposed development area in order to determine if there

are any visible archaeological remains and areas of previous impacts and to

assess if there are any built heritage assets/conservation areas; and

Examine borehole data available for the site and study area to establish

whether there is any archaeological and paleo-environmental evidence.

Further surveys or assessment will be contingent on the findings of the preliminary

desk-based studies and the site walkover. This may include archaeological

monitoring of geotechnical investigations; an archaeological evaluation including

environmental sampling prior to construction; the recording of historic railway

infrastructure/bridges/stations before and/or during development; and the

archaeological monitoring of groundworks.

3.5 Ecology and Nature Conservation

Potential sources of impact on ecology and nature conservation relate to damage or

disturbance to statutory and non-statutory designated sites and habitats, and

damage or disturbance to floral and faunal species populations during construction

and operation of the proposed scheme.

© Mouchel 2011


24


The disused rail corridor is currently largely overgrown with dense scrub (albeit with

some open areas incorporated within its length) and provides a „green corridor‟

within the suburban context of Watford. Other areas of semi-natural habitat within

the scheme footprint, but currently residing outside of Network Rail ownership, are

likely to further contribute to this effect.

The rail corridor directly abuts the Lairage Land Local Nature Reserve (LNR) to the

west of Riverside Park and also exhibits potential to support a range of legally

protected and/or ecologically significant faunal species; with the presence of badger

Meles meles, common reptile species, and foraging bats already confirmed from

surveys undertaken in the summer of 2009. The Croxley Common Moor Site of

Special Scientific Interest (SSSI) is located outside the proposed scheme area;

however it is within the 1km corridor study area. It is not currently expected that

there will be any impacts on the SSSI as a result of the proposed scheme.


Potential impacts could result from:

Damage/destruction of vegetation within and adjacent to the site (including

within the adjacent LNR), with potential associated impacts on flora and fauna;

and

Impacts upon legally protected and/or ecologically significant species,

including; invertebrates, great crested newts Triturus cristatus, common reptile

species, breeding birds, bats and badgers during construction and operation.

These potential impacts will vary in type and severity between taxa, but may

include loss or degradation of habitat via vegetation clearance or landtake,

severance to commuting or foraging routes, and increased disturbance from

site personnel, and increased noise, dust and light levels.


A series of desk-based and field surveys were undertaken as part of a detailed

Ecological Impact Assessment based on the Guidelines for Ecological Impact

Assessment in the UK (IEEM, 2006)xi and are described below. Further studies are

proposed to be undertaken to update some information and these are also described

below under the relevant species headings.

3.5.3.1 Desk Studies

The following organisations were contacted to update the previous desk studies prior

to the commencement of field surveys, in order to collate historical biological records

from within the scheme development boundary and a 1km corridor beyond this on

either side:

Local Biological Records Centre (Hertfordshire);

© Mouchel 2011


25

Records from web-based sources, including those held on the National

Biodiversity Network (NBN) Gateway and Natural England‟s „Nature on the

Map‟ website; and

County/local Biodiversity Action Plans (BAP) where available.

3.5.3.2 Field Surveys

A range of field surveys were undertaken from July 2009 to October 2010 in the

vicinity of the proposed viaduct and along the disused rail corridor following minimal

vegetation clearance to allow further access to this area. These included:

i) Habitats/Floral Communities

An updated Phase 1 Habitat Survey was undertaken along the length of the disused

rail corridors in the optimal survey month of July 2009 (with some additional areas

surveyed in September 2009), following standard methods (Joint Nature

Conservation Committee JNCC, 2007xii). The survey noted the BAP habitats wet

woodland and running water at the site. These are not constraints to development. In

addition, the survey identified the presence of invasive species Japanese knotweed,

Himalayan balsam and Virginia creeper. Specific control or removal measures will be

required for these species in order to prevent their spread.

ii) Invertebrates

All the terrestrial and arboreal habitat types present within the Network Rail holdings

were sampled in August 2009 with additional surveys undertaken in the spring of

2010) using a variety of sampling methods, in reasonable accordance with Drake et

al. (2007)xiii. Methods employed included the standard techniques of sweeping

grasses, rushes, sedges, herbs and foliage, and beating the foliage and branches of

trees and bushes over a beating tray (Kirby, 1992)xiv. Dead wood was examined by

hand and bark removed to reveal bark dwelling species. The site was shown to have

low intrinsic value for invertebrates and effects of the proposals on this group are not

likely to be significant.

iii) Great Crested Newt

Update Habitat Suitability Indices (HSI) were calculated for all accessible

waterbodies lying within 500m of the survey area during July 2009, following the

methodology detailed in Oldham et al. (2000)xv. An assessment of any connective

terrestrial habitat between these waterbodies and the survey site boundary was also

made. HSI values and/or visual assessments of ten such waterbodies were made in

summer 2009, with a single (accessible) waterbody scoring highly and thus requiring

great crested newt population (GCN) surveys were undertaken in spring of 2010

following standard methodology (English Nature, 2001xvi). These surveys showed

that great crested newts were not present.

iv) Common Reptile Species

© Mouchel 2011


26

Surveys to identify the presence/likely absence of reptile species and to enable

subsequent relative population class size estimations to be made were undertaken

between July and September 2009 in all areas of suitable reptile habitat identified

within the Network Rail holdings. These comprised of both artificial refugia surveys

(following Froglife (1999)xvii and Gent & Gibson (1998xviii)) and incidental visual

inspections. During the refugia surveys, a total of twenty visits were made in order to

accurately assess the reptile population on site (Froglife 1999, Reading 1996xix). The

central area of the proposed scheme, close to the River Colne, supports populations

of slow worms and grass snake. Because of the loss of habitat in this area, a

mitigation scheme for reptiles would be considered within the ES. This may take the

form of a description of a programme for the translocation of reptiles to a suitable

receptor site.

v) Breeding Birds

A field survey was undertaken using the territory mapping technique described in

Bibby et al. (2000)xx during April, May and June 2010 (including three dawn visits to

the site). Field maps were be used to record all bird activity observed using standard

British Trust for Ornithology bird activity codes. Breeding birds are only likely to pose

a constraint to works undertaken during the period March to July inclusive. Should

works need to be undertaken during this time, appropriate measures would be

implemented within a code of construction practice to prevent adverse effects

occurring.

vi) Bat Species

Two dusk bat activity surveys were undertaken in August 2009, following the

standard methodologies described by the Bat Conservation Trust (2007)xxi and

Mitchell-Jones (2004)xxii. In situ Anabat recorders were used between surveys to

further inform the utilisation of the survey area by bat species. Suitability

assessments of any potential roost sites were also undertaken. These surveys

confirmed that bat roosts are not currently present at the site. However, additional

surveys will be undertaken prior to the submission of the ES to confirm that this

remains the case.

vii) Badgers

Field surveys for badgers were undertaken within the within the disused rail corridor

in July 2009 in reasonable accordance with Harris et al. (1989). The survey area was

systematically searched for setts and other signs of badger activity. No badger setts

were found within the disused rail corridor. However, two badger setts were

identified in areas that are likely to be affected by the works: one next to the River

Gade and the other to the west of the River Colne. Further surveys would be

undertaken prior to the submission of the ES to determine sett status and activity to

inform the level of mitigation required.

© Mouchel 2011


27

3.6 Geology, Soils and Contaminated Land

Potential sources of impact on geology and soils relate to former potentially

contaminative uses within or surrounding the proposed site and their associated risk

to health and safety during the operation and construction of the proposed scheme.


A Preliminary Risk Assessment (PRA) of the contamination risk was undertaken in

March 2010. In addition, reports commissioned by Mouchel on behalf of HCC

entitled „Supplementary Contaminated Land Investigation, Ascot Road, Croxley‟,

September 2008xxiii by STATS geotechnical consultants and „Ground Investigation –

The Croxley Rail Link – Stage One – Factual Report – Contract No. 936/3256‟, July

2003xxiv by Costain Geotechnical Services were produced.

Based on the preliminary findings of the reviews, a number of areas of concern have

been identified, including:

Made ground is likely to be present at the scheme, associated with both the

active railway line and the now disused Croxley Green Branch Line. Therefore,

there is the potential that contamination may be present which may pose a risk

to human health and controlled waters; and

Two former landfill sites are located adjacent to the proposed scheme at

Riverside Park to the south of the disused railway and at Waterfields

Recreation Ground to the east of the operational DC line. There is a further

area next to the proposed new station at Ascot Road that was a former waste

transfer station. This has been assessed as part of the STATS study. These

are shown on Figure 1.


Potential impacts on certain receptor types (human health and controlled waters,

including groundwater) have been identified by conducting a PRA. The PRA was

undertaken to assess the potential for a Source-Pathway-Receptor linkage and the

risk of potential impacts for certain linkages being present.

The PRA identified that the most significant potential impacts to human health would

be from the potential exposure of on-site workers to potentially contaminated made

ground and fly-tipped material.

The PRA also identified the most significant potential impacts to controlled waters

(the underlying major aquifer) from piling and construction works through potentially

contaminated made ground and contaminants associated with the former land use

i.e. former railway land and the disused section of the Croxley Green Branch Line.

As well as the quality of groundwater, surface watercourses may also be affected by

disturbances to these areas.

© Mouchel 2011


28

3.6.3 Survey and Assessment

The following tasks will be or are currently being undertaken to establish the

presence or likely presence of the above pollutant linkages as well as the risk for

potential impacts and effects as a result of development of the scheme:

Review of previous work including earlier EIAs, STATS and Costain reports;

Collection of baseline data including a review of the following:

o Environment Agency “What‟s in my Back Yard” website;

o Envirocheck/GroundSure Environmental Data and historical maps;

o DoE Industry Profiles;

o MAGIC website;

o Geological maps;

o OS/Landranger maps; and

o Hydrogeological/groundwater vulnerability map (where available).

Review site activities in terms of physical aspects such as topography and

surface cover;

Determination of the geology of the site and surrounding area;

Assessment of hydrogeology of the site and surrounding area including

groundwater; abstractions, pollution incidents relating to groundwater, source

protection zones, etc;

Assessment of hydrology of the site and surrounding area including river

quality, surface water abstractions, discharge consents, pollution incidents

relating to surface water;

Review of history of the site and surrounding area (specifically with regard to

former and present potentially contaminative uses);

Development of a conceptual site model based on the requirements of CLR11

Model Procedures for the Management of Land Contamination, 2006 to identify

potential sources, receptors and pathways of contamination in terms of future

end users, controlled waters, and also to liability and project programme;

Assessment of each source-pathway-receptor pollutant linkage in terms of the

risk that each pollutant linkage poses to the receptor/project in general

accordance with CIRIA guidance document „CIRIA/DETR C552, 2001,

Contaminated Land Risk Assessment, A Guide to Good Practicexxv;

Development of recommendations for ground investigation work if potentially

contaminated sites are located to establish the extent and nature of these; and

Development of guidelines for the handling and disposal of any contaminated

materials.

In addition, contaminated land assessment works will be undertaken in

accordance with Planning Policy Statement 23 Annex 2 Development on Land

© Mouchel 2011


29

Affected by Contamination. In particular, the level of investigation and detail of

investigation.

3.7 Landscape Character and Visual Context

Potential sources of impact on landscape/townscape character and visual context

relate to new built elements, alterations to the existing urban fabric and use,

vegetation clearance, the operation of trains, and the use of machinery and plant

during construction.


The townscape of the study area is characterised predominately by the linear

residential streets and light industrial and commercial development, with open green

spaces of the urban fringe landscape associated with the Grand Union Canal and

the River Colne extending into the periphery of the study area.

Development within the residential areas range in date and density but consists

predominantly of Victorian and Edwardian two-storey properties with gardens;

however there more recent blocks of flats and multi-storey apartment developments

as well as new commercial buildings. Along the disused Croxley Green Branch

urban open spaces are located either side of the line and feature a mix of playing

fields, community gardens and infrequently managed areas of scrub or woodland.

The scheme is located within this mostly urban residential context with the majority

of the scheme following the existing disused railway, much of which is within densely

vegetated cutting. This existing section is surrounded by schools, public space,

commercial and industrial development as well as the residential properties.

The western section of the scheme includes a proposed new viaduct passing

through an area of residential and commercial development, crossing over highways,

a children‟s play space, the Grand Union Canal and the River Gade. The eastern

section of the proposed scheme will run on the shared existing track leading into

Watford town centre.

Sensitive elements of the wider surrounding character include the Colne Valley

Linear Park and Cassiobury Park - designated as a Grade II Registered Park and

Garden.


The proposed scheme has the potential to alter the existing surrounding

townscape/landscape character and visual context, and to introduce visual impacts

for the surrounding receptors.

The surrounding urban character will be sensitive to change as a result of the

proposed scheme which will have implications on the existing use, appearance,

perception and scale of the area.

While the proposed scheme will re-use the rail line and will not result in major

alterations to the urban fabric, there will be some new elements added. The most

© Mouchel 2011


30

significant of these new features include a new embankment and viaduct over the

Grand Union Canal and the A412, further urbanising this area and affecting existing

features below including a playground and the canal setting, two new stations at

Ascot Road and Vicarage Road with potential to alter the existing use, access and

appearance of the local neighbourhoods and a new car park facility at Ascot Road.

In general the potential impacts to the local character may be either positive or

negative and will result from:

The scale and form of new built structures, such as the viaduct and new

stations, which may have the potential to prove inappropriate and intrusive in

the context of existing landform, settlement pattern and overall character.

Introduction of new public realm facilities which can contribute to the

regeneration of environments, changes in use or perception and the

establishment of new townscape or landscape characteristics.

Changes in lighting conditions due to new facilities and lighting requirements.

Direct or indirect impacts to landscape and townscape elements, including the

loss or fragmentation of important and distinctive features, such as public

space or existing mature vegetation resulting in changes to available views and

settings, or alterations to the settings of historic / important features or

characteristics.

Introduction of new activity associated with increased pedestrians at new

stations and the associated facilities, such as the station car park at Ascot

Road, which have the potential to contribute to, or detract from, local

townscape character.

Construction activities which have the potential to create temporary additions

to the skyline such as cranes and scaffolding, erection of screens and fences,

clearance or pruning of vegetation, movement of heavy plant on and off site,

provision of lighting and potential night works which can directly change

peoples‟ perception and experience of the landscape or townscape.

Potential visual receptors within the study area range from residential

receptors, users of the public rights of way and public spaces, schools,

employees in the commercial and industrial areas and commuters.

In general, the scheme has the potential to create visual impacts for receptors both

alongside the proposed route and in the wider area as a result of:

New significant structures or buildings introduced within views, for example the

new viaduct within the skyline;

The operation of trains introducing new moving elements within views;

Vegetation clearances opening views of the operational rail line or new

stations;

© Mouchel 2011


31

New lighting associated with the proposed stations and car parking facilities

resulting in light intrusion or increased light pollution; and

Construction activities introducing temporary visual detractions resulting from

additions to the skyline such as cranes and scaffolding, erection of screens

and fences, clearance or pruning of vegetation, movement of heavy plant on

and off site, provision of lighting and potential night works.

In accordance with the proposed methodology the most sensitive of these visual

receptors are likely to include:

The large number of residential properties overlooking the existing vegetated

disused track, ranging from semi-detached housing to multi-storey apartment

blocks, along Cardiff Road, Stripling Way, Kelmscott Close, Hagden Lane,

Franklin Avenue, Himalayan and Pioneer Ways, Tolpits Close, Sydney Road

and the Gateway, where existing views will be affected by vegetation

clearances, new built and lit elements and the operation of the train line;

The residential properties in the west of the scheme on Watford Road,

Dorrofields Close, Baldwins Lane, Sycamore Road, and Mayfare which will

have partial and direct views of the proposed operational viaduct within the

skyline;

The commercial properties including the pub on Rickmansworth Road and

Cinnamond Contract Limited.

The users of the Grand Union Canal and the national trail alongside it, over

which the new viaduct will pass; and

The users of public recreation space including the children‟s play area

alongside the canal, the Colne Valley Linear Park, and potentially visitors to

Cassiobury Park.


Further assessment will be undertaken in accordance with nationally recognised

guidance provided within the Guidelines for Landscape and Visual Impact

Assessment (GLVIA), and in accordance with the methodology in DMRB Volume 11,

Section 3, Part 5 Landscape Effectsvii, and the Interim Advice Note 135/10

Landscape and Visual Effects Assessment.

3.7.3.1 Townscape/Landscape Character Effects

There are five key stages to the assessment process:

Recording and analysis of the existing character and visual context of the

receiving environment (the baseline environment);

An appreciation of the nature, forms and features of the outline proposals;

Identification of design and mitigation measures appropriate to the proposed

development and character of the receiving local area;

© Mouchel 2011


32

An assessment of the magnitude of change likely to result from the

development and the sensitivity of the existing landscape/townscape to

change; and

Evaluation of the significance of the changes identified based on the above

assessment.

The nature and status of physical townscape/landscape characteristics will be

established through a review of existing data sources and consultation with statutory

agencies and relevant local authority departments. Data gathered will be checked

and verified through site surveys, allowing distinctive local character zones to be

refined and the characteristics of these landscape or townscapes to be recorded.

The zones would then be assessed in terms of their quality, value and capacity to

accommodate change as a basis for determining their sensitivity to the form of

development proposed. The evaluation of impacts on the local character zones

would take account of the scheme design proposals including specific mitigation

measures.

3.7.3.2 Visual Effects

The visual impact assessment would involve the adoption of the five stages of

assessment described in above.

Establishment of the existing visual context for the proposed scheme would involve

consideration of the information relating to the existing landscape character

established during the associated baseline assessment, the definition of a zone of

visual influence for the proposed scheme and the identification of receptors and key

views within this visual envelope.

In common with the assessment of townscape/landscape character, the key criteria

used to evaluate visual impacts would involve the identification of the sensitivity of

the receptor and the magnitude of change. In assessing the visual impacts the

location and scale of the proposed development will be considered in individual

views and key viewpoints.

The evaluation of impacts for both townscape/landscape character and visual effects

would take account of the construction and operational phases of the scheme, and

design proposals including specific mitigation measures.

3.8 Noise and Vibration

Potential sources of impact due to noise and vibration relate to the operation of

trains, new stations, associated passenger movements, additional traffic, and the

use of machinery and plant during construction.


Existing sources of noise and vibration within the area comprise road traffic, limited

industrial activities and trains running on the existing London Overground DC line

route and LUL Metropolitan Line.

© Mouchel 2011


33


Potential sources of noise and vibration associated with the construction and

operation of the proposed scheme would comprise the following:

Construction activities and construction plant;

Additional trains running on the existing track;

Trains running on new track within the disused rail corridor;

Trains running along the new embankments and viaduct that would link the

disused rail corridor with the current LUL Metropolitan Line;

Additional traffic associated with the new station car park at Ascot Road; and

Additional passengers at the new stations, particularly the new Watford Health

Campus Station which would serve Watford Stadium and the new proposed

Watford Health Campus at Watford Hospital.

A number of potentially sensitive sites are located within close proximity of the

proposed scheme including:

Residential properties including those with gardens backing on to the disused

rail corridor (along Hagden Lane and Cardiff Road), in the vicinity of the

proposed viaduct (along Watford Road, Mayfare, Sycamore Road, The

Gateway, Sydney Road) and along to current London Overground DC Line

(along Neal Street, new flats adjacent to Watford High Street station, Queens

Road, Gladstone Road and Woodford Road);

Houseboats, and permanent and temporary housing along Grand Union Canal;

Commercial properties including the industrial estate to the east of Wiggenhall

Road, the pub on Rickmansworth Road, Cinnamond Contract Limited on

Watford Road and Watford General Hospital;

Watford Football Club at Vicarage Road Stadium;

Chase Care Centre on the Gateway;

Schools and nurseries including Central Primary, Chessbrook Education

Support Centre, Laurance Haines , St Anthony‟s Roman Catholic Primary,

Watford Field (Infant & Nursery and Junior), Westfield Community Technology

College and Watford Grammar School for Girls;

Recreation grounds including the playground off Watford Road, Harewoods

Recreation Ground, Riverside Park and Waterfields Recreation Ground; and

Allotments to the west of Vicarage Road


An assessment following the procedures set out in the Calculation of Rail Noise

(CRN) will be conducted. CRN is the method used to assess eligibility for insulation

of residential property from railway noise under the conditions specified in the Noise

Insulation (Railways and other Guided Transport Systems) Regulations 1996xxvi

© Mouchel 2011


34

(NIR). These regulations apply to new or improved railways. The assessment will

be undertaken using in-house modelling software, NoiseMap Server Edition, which

implements the CRN procedures.

A review of traffic data pertaining to changes in traffic movements as a result of the

scheme will be undertaken. This will determine the need for any further assessment

following the guidance set out in the DMRB Volume 11, Section 3, part 7 Noise and

Vibrationvii and would reference the Calculation of Road Traffic Noise (CRTN) 1988

as and where appropriate.

Data relating the new anticipated noise emissions from the new stations will be

reviewed and where appropriate potential noise impacts will be assessed using BS

4142 Method for rating industrial noise affecting mixed residential and industrial

noise areas.

The potential impacts of noise and vibration during the construction phase will also

be considered using data available at the time of assessment and in accordance with

BS 5228 Parts 1 and 2xxvii.

In summary the following tasks will be or are being undertaken as part of the

assessment:

Review of documents produced during previous EIAs, including a report

entitled Noise and Vibration Assessment for the Proposed Croxley Rail Linkxxviii

produced by Metro Consulting Limited;

Consultation has been undertaken with the Environmental Health Officers

(EHOS) for both WBC and TRDC to discuss noise complaints, monitoring

locations, noise policies and to agree the methodology for the assessment;

A site walkover to establish suitable locations for day-time (0600-2400 hrs) and

night-time (0000-0600 hrs) noise monitoring in order to establish the existing

noise level has been completed. Twelve monitoring locations were identified

and agreed with the EHOs (including four long term locations and eight short

term locations);

The need for a baseline vibration survey will be determined and undertaken if

necessary;

Review of available traffic data to determine the need for further assessment of

potential traffic-related noise and vibration using the DMRB;

An assessment of noise from new station buildings will be undertaken in

accordance with BS 4142. This is to include noise associated with public

address system and audible warning systems;

Development of a noise model to predict the operational noise levels at nearby

noise-sensitive receptors within 300m from the proposed scheme. Baseline

noise data for the proposed rolling stock (S-class trains) has been obtained

© Mouchel 2011


35

from LUL and reviewed. The results of the model will allow the significance of

any impact to be determined;

Design of suitable mitigation measures to reduce the predicted noise level to

an acceptable level where required;

Determination of the operational residual impacts of the scheme

Identification of the likelihood of potential qualification for insulation under the

NIR at residential receptors; and

Assessment of construction noise and vibration.

3.9 Surface Waters, Groundwater, Flood Risk and Drainage

Potential sources of impact on surface waters, groundwater sources, flood risk and

drainage relate to changes in the water regime caused by the scheme design,

construction and operational activities.


The Grand Union Canal, River Gade and River Colne all pass under the proposed

alignment. Two existing rail bridges (part of the disused Croxley Green Branch Line)

span across the River Colne along the eastern segment of the proposed rail track.

The proposed viaduct would span across River Gade and the GUC. The various

components of the existing environment which will define the baseline conditions for

the flood risk, surface water, groundwater and drainage assessments are described

in more detail below.

3.9.1.1 Fluvial Flood Risk

The study area would encompass the extents of the three watercourse catchment

areas, namely for the River Colne, River Gade and the Grand Union Canal that have

the potential to be affected by the proposed development (see Figure 3 in Appendix

A). River Colne falls within the Environment Agency (EA) designated Flood Zone 2

(medium probability, having between a 1 in 100 and 1 in 1000 annual probability of

river flooding (1%-0.1%) or between a 1 in 200 and 1 in 1000 annual probability of

sea flooding (0.5%-0.1%) in any year). River Gade and the Grand Union Canal

(GUC) also fall within EA Flood Zone 2 but the flood plains are restricted to the river

channels. It is to be noted that the flood models for River Gade and the GUC do not

exist.

Flood zone areas without defences have been identified in the region of the

proposed viaduct and in the vicinity of the link between the disused rail corridor and

the existing London Overground DC line.

3.9.1.2 River Water Quality

The EA publishes General Quality Assessment (GQA) data on their website listing

the chemical and biological quality of rivers and canals in England, and chemical

quality data for the River Colne, River Gade and the GUC is available. Each of these

watercourses has Grade A (very good) river quality which indicates that the rivers

© Mouchel 2011


36

have natural ecosystems and make very good salmonid and cyprinid fisheries. They

may be used for any type of water abstraction including potable water supply.

3.9.1.3 Groundwater Quality

A major portion of the proposed rail route lies on a principal aquifer within Source

Protection Zone (SPZ) I around a public water abstraction. It has very shallow depth

to groundwater ranging between 0 and 18m.

3.9.1.4 Drainage

During a site walk-over survey undertaken in April 2011, few drainage ditches were

noted at the site discharging into River Colne. The walk-over survey did not reveal

any discharge points into River Gade or the GUC. A few disconnected segments of

perforated pipes were also noted across the disused railway line. However, details

on the utility or connectivity of these pipes are not available. A brief look at the

existing utility services in the study area indicates that there is no connectivity

between track drainage system and the surrounding residential/ commercial/

industrial developments.

Consultation with the EA is underway to obtain further clarity on the use of existing

outfall points and the potential location of for new outfalls points..


There is potential for increased surface water runoff due to the introduction of track

bed and additional hardstanding at new stations and the car park at Ascot Road.

This has the potential to affect the flowrates and water quality of receiving

watercourses and/or the drainage system. In addition, earthworks could potentially

affect groundwater recharge and storage, and alter groundwater quality and flow

patterns. These changes could potentially increase flood risk both onsite and in the

surrounding catchment area. Each of these potential impacts is discussed in more

detail below.

3.9.2.1 Flood Risk

The proposed widening of the railway track and increased hard standing from the

proposed stations and associated infrastructure (platforms, car park, etc.) will result

in increased runoff and pose a risk of increased runoff into the watercourses. A Level

2 Flood Risk Assessment (FRA) is being undertaken for the entire route in

accordance with PPS25 on Development and Flood Risk to assess the flood risks

from various sources such as rivers, surface water, groundwater, sewers and

artificial sources such as reservoirs and lakes in the vicinity of the site. The

assessment will cover all the components of the proposed scheme including

earthworks (permanent, embankments, cuttings, etc.), bridges, viaduct and stations.

Suitable flood risk mitigation measures will be investigated in conjunction with the

drainage system for the proposed rail route. The results will inform the EIA process.

© Mouchel 2011


37

3.9.2.2 River Water Quality

The operation of the proposed railway may result in release of grease and/or other

oily substances, metal wear from track and train wheels, and brake dust being

discharged into the watercourses through surface water runoff if not intercepted.

3.9.2.3 Groundwater Quality

There is a highly sensitive principal aquifer in the vicinity of the scheme and as such

surface water discharges into the ground will not be acceptable. Mitigation will be

identified in the EIA to this effect.

The proposed earthworks are largely around the new viaduct, the tie-in at Baldwins

Lane and the existing earthworks along the disused section of line which require

widening / modification to accommodate the proposed twin track. These may

potentially affect groundwater recharge and storage and alter groundwater flow

patterns. In addition, due to relatively high groundwater levels, there is a potential

risk of interaction between the surface water and groundwater sources in the study

area which may impact the flood risk and existing water quality. Release of oily

substances, metals, brake dust, etc have the potential to reach groundwater if not

intercepted. Mitigation will be identified in the EIA to control these potential adverse

impacts.

3.9.2.4 Drainage

There would be increased surface water runoff due to the proposed construction of

the viaduct, widening of the railway to dual track and additional hardstanding area at

the proposed new stations at Watford Health Campus and the new station and can

park at Ascot Road.


A water quality and drainage desk-based assessment is currently being undertaken

which involves a review of water quality monitoring data from statutory agencies and

information from topographic and geotechnical databases (related to groundwater

and hydrogeology) to establish the existing baseline conditions with respect to the

water environment. A site walkover survey was undertaken in April 2011 to assess

the general conditions at the site, understand the site topography and identify

potential outfall points along the proposed rail route. The assessment will also

involve a review of further data received from the EA, Network Rail and LUL.

The process of impact assessment will cover:

Baseline conditions of water environment – the existing conditions of the water

environment will be evaluated using desk-based studies, data collection from

statutory agencies and site investigations undertaken as part of the scheme

development;

Assessment of impacts – the potential impacts on each of the baseline

conditions for flood risk, water quality (surface water and groundwater) and

© Mouchel 2011


38

drainage will be assessed for various aspects of the proposed scheme –

earthworks, stations and associated infrastructure, viaduct and bridges;

Mitigation measures – suitable mitigation measures during the construction

and operation phases will be proposed; and

Residual impacts – the potential impacts arising after implementing the

mitigation measures will be evaluated.

Surface water impacts (including surface water runoff, flood risk and surface water

quality) as well as groundwater impacts (including water supply (presence of source

protection zones), water table depths, ground permeability and groundwater quality)

will all be considered.

The following tasks will be or are currently being undertaken:

Review of documents produced during previous EIAs;

Collection of baseline data, including a review of the following:

o Existing water quality data

o Ordnance Survey data

o Existing drainage details

o Proposed drainage design details

o Flood maps

Site walkover to examine the location of surface watercourses and the state

of the current drainage system along the length of the disused railway;

Assessment of the proposed drainage network with particular regard to final

discharge destinations and discharge rates for the runoff;

Assessment of the potential climate change impacts in terms of predicted

future rainfall and flooding will be considered during the design process;

Consultation with the Environment Agency (EA) regarding the requirement for

attenuation measures to maintain the existing discharge rates in the outfalls

and to develop any such mitigation measures to ensure compliance with their

policies;

Assessment of the proposed pollution control measures to ensure that no

water body receives a greater pollutant load than that which occurs under

current conditions;

Development of sustainable methods in the drainage designs;

Review of local drainage ditches on a case by case basis and the

development of appropriate mitigation measures where necessary as the

scheme design evolves; and

© Mouchel 2011


39

A Flood Risk Assessment has been commissioned as part of the scheme

development and the results will be used to inform the environmental

assessment process.

3.10 Traffic and Transport

A study of the effects on traffic and transport will be undertaken as part of the

assessment.

Reference will be made to a parallel Traffic Impact Assessment which will be

appended to the ES and assessment made of relevant environmental considerations

not covered elsewhere in the EIA (e.g. impacts on air quality and noise). Such

impacts could include access and severance.

3.11 Community and Socio-Economic Effects

The effects of the proposed scheme on local population, community facilities, areas

of interest, and pedestrian and cycle routes will be assessed following the appraisal

of maps and published data and consultation and discussions with stakeholders.

All land uses and community facilities within 250m of the proposed scheme will be

identified. Consideration will also be given to effects of the scheme on Watford

General Hospital, Watford Football Club at Vicarage Stadium, local schools and

recreation grounds.

An Equality Impact Assessment has been commissioned as part of the scheme

development to ensure that the stakeholder consultation process is comprehensive

and inclusive. The results of this assessment will be used to inform the EIA. The

following factors will considered be in the assessment:

Location and usage of public rights of way, community and recreational

facilities;

Nature of the population using or crossing the area with particular emphasis on

vulnerable groups such as children and the elderly;

Severance effects created or relieved by the scheme;

Effects on journey times and distances;

Effects of disturbance, such as noise, on vulnerable receptors, such as schools

and the care home for the elderly (Chase Care Centre); and

Effects of the closure of Watford Met station on the local population.

Details of the community effects will be assessed and the results will be presented in

a chapter for inclusion in the ES. Mitigation measures and residual impacts will also

be identified and details of these will be included in the ES.

3.12 Cumulative Effects

For the purposes of this EIA it is proposed that the following definitions will be

adopted:

© Mouchel 2011


40

Indirect Impacts: Impacts on the environment, which are not a direct result of

the project, often produced away from or as a result of a complex pathway.

Sometimes referred to as second or third level impacts, or secondary impacts.

For example, visual impact from the use of noise attenuation barriers as a

mitigation measure;

Cumulative Impacts: Impacts that result from incremental changes caused by

other past, present or reasonably foreseeable actions together with the project.

For example: combined effect of individual impacts, e.g. noise, dust and visual

from one development on a particular receptor; and

Impact Interactions: The reactions between impacts whether between the

impacts of just one project or between the impacts of other projects in the area

for which planning permission has been granted. For example: emissions to

air from one project reacting with emissions from an existing development or

overlapping time periods will have many interactive impacts, from land use

issues to construction and operational noise.

The environmental effects from indirect and cumulative impacts and impact

interactions can be significant. The objective of this element of the EIA will be to

identify and focus on the significant impacts. It will be important to ensure that these

impacts are taken into consideration in the decision-making process. Particular

attention will be paid to the Health Campus development at Watford General

Hospital which has been granted planning permission.

There is no agreed or accepted methodology to evaluate indirect and cumulative

impacts and impact interactions. Guidance is provided in ‘European Commission

Guidelines for the Assessment of Indirect and Cumulative Impacts as well as Impact

Interactions, EC DG XI Environment, Nuclear, Safety and Civil Protection, 1999‟.

Based on the guidelines, it is proposed that matrices be developed to evaluate the

impacts and impact interactions.

The matrices will be organised to cross reference the construction and operational

phases of the scheme against environmental elements and sensitive receptors. The

development of the matrices will be dependant upon a number of activities, including

the following:

Consideration and development of a list the activities associated with project;

Identification and development of a list the sensitive resources; and

Identification of cumulative impacts by identifying if a number of different

activities (including those from other developments) impact on a single

resource or receptors.

The most significant development that has been granted planning permission within

the vicinity of the proposed development scheme is the Watford General Hospital

Health Campus development which would extend to the south of the current hospital

and over the railway with an access road over the railway and Cardiff Road. The

© Mouchel 2011


41

findings of the assessment of the implications of the Health Campus development

programme and any further indirect and cumulative impacts and impact interactions

from other developments that have been granted planning permission will be

presented as a chapter in the ES.

3.13 Policies and Plans

A review of the current environmental policies and plans for HCC, WBC, TRDC, LUL

and NR is being undertaken in light of the potential impacts that are identified and

will inform the EIA along with other relevant local, regional and national planning

policies.

© Mouchel 2011


42

4 Proposed Environmental Statement Structure

The guidance set out in a Guide to Transport and Works Act Procedures 2006xxix will

has been reviewed to ensure that all environmental aspects are given due

consideration during the assessment and an Environmental Statement (ES) would

be produced in accordance in Annexes 6 and 7 which set out the information to be

included within an ES.

A proposed structure for the ES is shown below. This would include consideration of

the construction and operation of the scheme, as well as a description of mitigating

measures. This structure will be reviewed following receipt of the Screening Decision

and Scoping Opinion.

1. Introduction

1.1 Background

1.2 The Statutory Context

2. Need for the Scheme

3. Project Alternatives

4. The Existing Environment

5. Description of the Proposed Scheme

5.1 Key Components

5.2 Site Access and Traffic Movements

5.3 Design Components

5.4 The Construction Phase

6. Scoping and Introduction to Environmental Assessments

6.1 Scope of the Environmental Impact Assessment

6.2 Format to the Assessment Chapters

7. Air Quality

8. Cultural Heritage and Archaeological Resources

9. Ecology and Nature Conservation

10. Geology, Soils and Contaminated Lands

11. Landscape Character and Visual Context

12. Noise and Vibration

© Mouchel 2011


43

13. Surface Waters, Flood Risk and Drainage

14. Use of Resources

15. Community Effects

16. Cumulative Effects

17. Policies and Plans

© Mouchel 2011


44

5 References

i Her Majesty’s Stationary Office (HMSO) (1992). Transport and Works Act. Office of

Public Sector Information (OPSI).

ii Transport and Works (Applications and Objections Procedure) (England and Wales) Rules

2006 (SI 2006 No. 1466). Legislation.gov.uk: The National Archives.

iii Annex I or Annex II of EU Directive 85/337 The Assessment of the Effects of

Certain Public and Private Projects on the Environment.

iv Croxley Rail Link Environmental Statement, Volume 1 (1995). Aspinwall &

Company Limited.

v Croxley Rail Link Environmental Impact Statement (2004). Mouchel Consulting

Limited.

vi Watford Borough Council Air Quality Progress Report (2008).

vii Design Manual for Roads and Bridges (DMRB) Volume 11, Section 3.

viii Air quality guidance document Local Air Quality Management’ (LAQM.TG.09)

(2009).

ix Air quality guidance document ‘Local Air Quality Management’ FAQ (2009)

‘Guidance on Assessing Emissions from Diesel Locomotives Railway Emissions.

x Network Archaeology (2002). Croxley Rail Link – Archaeological Desk-Based

Assessment, Report No. 268.

xi Institute of Ecology and Environmental Management (IEEM) (2006). Guidelines for

Ecological Impact Assessment in the UK (published version 7 July 2006).

xii Joint Nature Conservancy Council (JNCC) (2007). Handbook for Phase 1 Habitat

Survey - A Technique for Environmental Audit. Revised reprint 2003. Peterborough,

UK.

xiii Drake, C.M., Lott, D.A., Alexander, K.N.A. & Webb, J. (2007). Surveying

Terrestrial and Freshwater Invertebrates for Conservation Evaluation. Natural

England Research Report 005.

xiv Kirby, P. (1992). Habitat Management for Invertebrates: A Practical Handbook.

RSPB/JNCC.

© Mouchel 2011


45

xv Oldham, R.S., Keeble, J., Swann, M.J.S. & Jeffcote, M. (2000). Evaluating the

Suitability of Habitat for the Great Crested Newt (Triturus cristatus). Herpetological

Journal 10 (4), 143-155.

xvi English Nature (2001). Great Crested Newt Mitigation Guidelines. Version: August

2001.

xvii Froglife (1999). Reptile Survey: An Introduction to planning, conducting and

interpreting surveys for snake and lizard conservation. Froglife advice sheet 10.

Froglife, Halesworth.

xviii Gent, T. & Gibson, S. (1998). Herpetofauna Worker’s Manual. JNCC,

Peterborough.

xix Reading, C.J. (1996). Evaluation of Reptile Survey Methodologies. English Nature

Research Report No.200.

xx Bibby, C.J., Burgess, N.D., Hill, D.A. and Mustoe, S.H. (2000). Bird Census

Techniques. 2nd Edition. Academic Press, London.

xxi Bat Conservation Trust (2007). Bat Surveys - Good Practice Guidelines. Bat

Conservation Trust. London.

xxii Mitchell-Jones, A. J. (2004). Bat Mitigation Guidelines. English Nature,

Peterborough.

xxiii Supplementary Contaminated Land Investigation, Ascot Road, Croxley (2008).

xxiv Supplementary Contaminated Land Investigation, Ascot Road, Croxley,

September 2008’ by STATS and Ground Investigation – The Croxley Rail Link –

Stage One – Factual Report – Contract No. 936/3256, July 2003.

xxv CIRIA/DETR C552, (2001), contaminated Land Risk Assessment, A guide to good

practice.

xxvi Her Majesty’s Stationary Office (HMSO), (1996). Noise Insulation (Railways and

other Guided Transport Systems) Regulations. Office of Public Sector Information

(OPSI).

xxvii Her Majesty’s Stationary Office (HMSO), (1996). Noise Insulation (Railways and

other Guided Transport Systems) Regulations. Office of Public Sector Information

(OPSI).

xxviii Consulting Limited ‘Noise and Vibration Assessment for the Proposed Croxley

Rail Link (2009).

appendix 1a - cover sheet · the local councils and railtrack (now nr). hertfordshire county...

Documents