HS2 Phase 1 – Draft Environmental Statement Consultation
16th May to 11th July 2013
Herts &
Middlesex
Herts & Middlesex Wildlife Trust response, 4th July 2013
Herts and Middlesex Wildlife Trust (HMWT) is a local charity supported by
people who care about protecting wildlife, including over 21,000 members.
With the help of volunteers, we take practical action everyday to protect
wildlife, restore biodiversity and connect people with the natural world in
Hertfordshire and Middlesex. Our vision is of a living landscape, where we
work with others to restore, recreate and reconnect wildlife-rich places in the
town and country, to create a dynamic and functioning ecological network for
the benefit of people and wildlife. Herts and Middlesex Wildlife Trust is one
of 47 Wildlife Trusts nationwide: we are the only charities working to protect
the full range of UK wildlife and habitats at a local level.
Grebe House
St Michael’s Street
St Albans
Hertfordshire
AL3 4SN
Tel: (01727) 858901
Fax: (01727) 854542
Email: info@hmwt.org
www.hertswildlifetrust.org.uk
Chief Executive: Jane Durney
The proposed HS2 Phase 1 route will cut through one of HMWT’s key Living
Landscape focus areas: the Colne Valley. The Colne Valley is the first
significant area of countryside to the west of London. The Colne Valley’s
network of lakes, river, canal, woodland, meadows and farmland, provides a
haven for wildlife, an important habitat corridor and a significant recreational
resource accessible to millions of people - benefits fostered through the
existence of the Colne Valley Regional Park. Nationally significant
populations of breeding and overwintering wetland birds and a regionally
significant population of Daubenton’s bats depend on the valuable and
sensitive habitats of the Colne Valley. The proposed Colne Valley viaduct will
slice through a Site of Special Scientific Interest and HMWT’s Broadwater
Lake Nature Reserve.
Focus and scope of comments
Our comments focus on the ecological elements of the draft Environmental
Statement (dES). Due to the geographic extent of the project and scope of
impacts, our comments focus on the ecological impacts and implications of
the project within the Colne Valley (covered by CFAR7). Some general
comments, relating to the dES as a whole and route-wide considerations
(based on Non-Technical Summary, Volume 1 and Vol.2 Report 27), have
nevertheless been set out briefly in Section 1 – General Comments.
HMWT supports comments that have been made in the Wildlife Trusts’ group
response on the route-wide issues.
We also support the Principles and comments that have been presented in
the HS2 Ecological Technical Group response to the draft Environmental
Statement. The Wildlife Trusts affected by HS2 Phase 1 are represented
within this group.
Hertfordshire & Middlesex
Wildlife Trust Limited is registered
in England No 816710 at the
above address and is registered
as a charity under Registration No
239863. VAT No 366 9276 06
President
Sir Simon A Bowes Lyon, KCVO
Protecting Wildlife for the Future
HMWT understands that HS2 Ltd has taken the decision to publish a draft Environmental
Statement, although there is no statutory requirement to do so. Due to its incomplete nature,
however, it is not necessarily helpful to consider the document as a draft Environmental Statement.
As it stands, it is not possible for HMWT to make firm conclusions or judgments on the suitability,
sufficiency or soundness of the surveys, baseline evidence, impact assessments, or mitigation and
compensation proposals. Our comments instead aim to highlight points of concern that must be
addressed as work continues on the formal Environment Statement (fES), and principles with
which the dES and project as a whole should adhere in order to be sound and harmonise with
legislation and policy.
Section 1 - General Comments
1) HMWT believes that as the first project of its scale coming forward since the publication of
the Natural Environment White Paper and the National Planning Policy Framework, HS2
should seek to set a solid precedent for future nationally significant infrastructure projects.
Objectives of the Natural Environment White Paper include moving from net biodiversity
loss to net gain; supporting healthy, functioning ecosystems; and establishing coherent,
resilient ecological networks. Paragraph 109 of the NPPF sets out that the planning system
should “contribute to and enhance the natural and local environment by… minimising
impacts on biodiversity and providing net gains in biodiversity where possible… including
by establishing coherent ecological networks that are more resilient to current and future
pressures.” HS2 Ltd must commit to the HS2 project achieving a net gain for nature.
It must be ensured that the project makes a positive contribution to establishing a
coherent and resilient ecological network.
2) The dES is incomplete at present, therefore it is not possible for HMWT to consider or
comment on the validity of HS2 Ltd’s conclusions in respect of impacts and necessary
mitigation and compensation, or on the soundness of the dES/EIA.
3) We would hope to see in the fES full details of the methodologies that have been followed
for the EIA, including details of the baseline ecological survey methodologies. The details
of individual site surveys must also be published (including specific locations, dates and
times of visit, weather conditions, repeat visits etc), in order that the suitability and
sufficiency of survey effort can be assessed. Any gaps in coverage or inadequacies that
are revealed before publication of the formal ES should be filled. Having insufficient survey
data to establish a robust baseline would not be an acceptable outcome.
The dES states that the Ecological Impact Assessment (EcIA) is “guided by” CIEEM
guidelines1. We consider that the EcIA should follow these guidelines, unless there is a
clearly justified reason for not doing so, which would make the ES stronger.
The EIA should also adhere to relevant British, European and international standards and
guidelines for EIA, including:
 European Commission (2013) Guidance on Integrating Climate Change and
Biodiversity in Environmental Impact Assessment
1
Chartered Institute for Ecology and Environmental Management (2006) Guidelines for Ecological Impact
Assessment in the UK.
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European Commission (1999) Guidelines for the Assessment of Indirect and
Cumulative Impacts as well as Impact Interactions
4) HMWT would prefer that a clear and accurate differentiation be made between ‘mitigation’
and ‘compensation’; the draft ES appears to confuse and conflate the two, which puts it in
conflict with guidance and policy. Various definitions exist, including within the CIEEM EcIA
guidelines and EC (2013) guidance on integrating biodiversity into EIA. ‘Mitigation’ relates
to measures and actions to reduce the adverse impacts, including through scheme design.
‘Compensation’ refers to actions taken outside of the scheme boundary to ‘offset’ any
residual adverse impacts resulting from the scheme. Examples of compensation include
habitat creation off site, or restoration work outside of the development site to improve
habitat quality. Compensation should only be used as a last resort, to compensate for
residual adverse ecological impacts that can be neither avoided nor mitigated.
HS2 Ltd should furthermore ensure that the formal Environmental Statement and the HS2
project as a whole adheres to the mitigation hierarchy, set out in CIEEM (2006) EcIA
guidelines, EC (2013) guidance on integrating biodiversity into EIA, and the National
Planning Policy Framework. Adverse impacts must be avoided as far as possible. Any
unavoidable adverse impacts should be mitigated as far as is possible. Compensatory
measures should be put in place as a last resort to offset any residual adverse impacts that
cannot be avoided or mitigated.
CIEEM Guidelines for Ecological Impact Assessment, paragraph 1.16
“IEEM endorses the following principles, recommended by the Royal Town Planning Institute
(RTPI 2000 Planning for Biodiversity), for optimising the biodiversity outcomes of planning
decisions:
 Information: Obtain sufficient information on the environmental resources and natural
processes to assess the impacts of the project.
 Avoidance: Consider options that avoid harm to environmental resources or natural
processes.
 Reduction: Where adverse effects are unavoidable then these should be mitigated
either through the design of the project or through measures that can be subsequently
guaranteed – for example, through a condition or planning obligation.
 Compensation: Where, despite the mitigation proposed, there are significant residual
adverse environmental effects these must be offset by appropriate compensatory
measures nearby/elsewhere.
 New Benefits: Seek to provide net benefits for biodiversity over and above requirements
for mitigation or compensation.”
5) No description has been provided of ecological monitoring that will be implemented
throughout project life – from pre-commencement to post-construction onwards, including
monitoring of the effectiveness and fitness for purpose of mitigation and compensation
actions. There is a need for a commitment to and clarity on monitoring programme that will
be followed in order to ensure delivery of ecological aims and objectives and suitable
responses if aims and objectives are not being achieved.
6) Interacting and cumulative impacts and effects are a key part of the assessment, given the
complexity and interdependence of natural systems and processes and the substantial
zone of influence of the route. To be clear, ‘cumulative impacts/effects’ includes
cumulative/combined effect on a particular “receptor” (eg. species or habitat types) due to
repeated impacts along the route (eg. combined loss of ancient woodland); combined effect
on one particular receptor of different, interdependent impacts (eg. hydrology and ecology,
noise/vibration and ecology); cumulative effect on ecosystem resilience and functioning
resulting from impacts on different components and agents in that ecosystem; cumulative
effects resulting from other projects alongside HS2. Assessment of this important aspect
is not yet complete, but the dES suggests cumulative effects will be analysed in the ES. As
this analysis has not yet been done, and no indication yet provided on how it will be treated,
we cannot provide comment on its suitability, sufficiency or soundness. It is imperative that
this aspect is done correctly, in view of the scale and nature of the project and complexity of
its likely environmental and ecological impacts.
7) Impacts on ecological networks and their functioning need to be properly assessed,
including from barrier, fragmentation and disturbance effects. This is an area typically
overlooked in EIA, but the sheer size of this project means the need to address these
effects is even more critical. The Lawton Review, National Ecosystem Assessment and
Natural Environment White Paper all emphasise the importance of connected, functioning,
landscape-scale ecological networks in sustaining biodiversity, ecosystem services and the
communities and economies which depend on them.
8) Meetings with HS2 Ltd have made it clear that a biodiversity offsetting approach and metric
will be used, based on the Defra pilot metric. A detailed description of the biodiversity
offsetting approach and methodology is needed in the formal ES, including how and why it
diverges from the Defra metric. HS2 Ltd needs to ensure that the approach has been
reviewed and found sound in the context of this project by experts in this field.
9) The dES does not include complete descriptions of what mitigation and compensation is
proposed. HS2 Ltd should work closely with organisations and local experts along the
route to decide on mitigation along the railway corridor and ‘off-site’ compensation actions
(eg. habitat creation, restoration and enhancement), to ensure that these are locally
appropriate and that the best opportunities for biodiversity and ecological gain are taken.
Section 2 - Comments relating to Colne Valley section
The Colne Valley is a valuable and sensitive ecological asset, comprising a network of water
bodies and wetland habitats in historic gravel extraction sites, which support notable populations of
overwintering wildfowl and breeding woodland and wetland birds. This includes sites of national
ecological significance (Mid Colne Valley SSSI), Sites of Metropolitan Importance for Nature
Conservation (SMINC) and HMWT’s Broadwater Lake Nature Reserve. The Colne Valley also
supports a significant population of Daubenton’s bats, which are protected under European law.
The Colne Valley will be severely impacted by the HS2 project:
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A viaduct will be constructed over the Grand Union Canal, River Colne and numerous
Colne Valley lakes, including Korda Lake and HMWT’s Broadwater Lake Nature Reserve
within the Mid Colne Valley SSSI, and Savay Lake in the Mid Colne Valley Site of
Metropolitan Importance for Nature Conservation. The viaduct will be supported by piers
across the valley, including in the lakes and one in the River Colne. A section of the River
Colne may be diverted to avoid and reduce impacts on the river system.
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Significant earthworks will be undertaken to carry the line from the end of the London tunnel
at West Ruislip to the start of the Chilterns Tunnel, opening with a porous portal near West
Hyde.
A number of national grid and autotransformer feeder stations will be constructed, and
power lines redirected, requiring substantial vegetation clearance.
Some road realignments are required.
Many construction compounds (2 main, 7 satellite compounds), extensive materials
stockpiles, laydown areas and construction access roads will be required. As well as the
numerous construction compounds needed for the viaduct, the Colne Valley will also
include the main compound for the construction of the Chilterns Tunnel, which will be bored
from the Colne Valley end. All of the spoil from the Chilterns Tunnel will be extracted into
the Colne Valley, to prevent adverse environmental and landscape impacts within the
Chilterns AONB.
As part of the Phase 1 construction, passive provision (“earthworks and turnouts”) will be
made on both sides of the valley for a potential future high-speed link to Heathrow.
The Environmental Baseline described in section 7.4 of Area Report 7 includes the plethora of
nationally significant protected sites (SSSI), non-statutory Local Sites and Local Nature Reserves
in the vicinity of the proposed route. The Colne Valley also supports a range of protected and
priority species, including otter and Daubenton’s and noctule bats, which have been included in the
baseline. The dES does not include the raw ecological survey reports, therefore HMWT is
unable to comment on the suitability or adequacy of the surveys that have been
undertaken, or the accuracy, representativeness or robustness of the baseline described.
Mitigation strategy
Recognising the value and sensitivity of ecology in the Colne Valley, section 7.5.2 states that an
‘integrated wildlife mitigation strategy’ has been developed. This is welcome, and we would hope
to see more details of the strategy in the fES.
Code of Construction Practice
Various measures will be implemented as part of the Construction Code of Practice to reduce and
manage environmental impacts and risks to ecological interests arising from construction. This
appears to provide a suitable framework, although the local effectiveness will depend on the quality
of the Local Environment Management Plan and stringency of implementation. Monitoring surveys
must be undertaken prior to commencement to ensure wildlife mitigation measures are
appropriate. Robust supervision and monitoring of effectiveness during construction and
subsequent works (eg. landscape remediation) is important. The CoCP includes reasonable
measures for control of noise, dust, water quality, and artificial lighting, which have ecological
implications. The approaches described in relation to controlling construction impacts on protected
sites, priority habitats and protected and priority species are considered generally appropriate. We
trust that precautionary and mitigation measures will comply with and reflect ecological best
practice. We would welcome consultation on detailed plans (Draft CoCP para 9.2.6).
Woodland compensation
The dES proposes new woodland creation on current agricultural land west of the A412, within
Denham Park Farm land holding. We would point out that the proposed planting of new woodland
would constitute compensation for loss of woodland in the SSSI, not mitigation as it is described in
the report (please refer to Section 1 - General Comments). That point notwithstanding, HMWT
would support the principle of this compensatory woodland planting (as shown in plan CT-06-02203), which would help to link up existing ancient woodland at Juniper Wood, Great Halings Wood
and Little Halings Wood. Production of a landcover or habitat map (existing and proposed), to put
the proposed new woodland in context could be beneficial (the current plan CT-06-022-03 shows
the existing land as white space). Suitable compensation for the resulting economic and viability
loss to Denham Park Farm would be needed if this option is pursued.
Paragraph 7.5.6 elaborates that the woodland creation would include the translocation of soils,
coppice stools and woodland herbs from the SSSI. HMWT is pleased that HS2 Ltd accepts that
this would not replicate the lost ancient woodland. There is a lack of evidence on how ‘successful’
translocation of the elements of an ancient woodland can be2. It is possible that more ecological
benefit can be achieved through creating larger areas of new semi-natural woodland than through
creating a smaller area on salvaged ancient woodland soil, for instance.
Hydrology and water quality impacts
As described in Chapter 13, significant impacts could result on water quality and flow in the SSSI
and River Colne during construction, including construction of the viaduct piers, which will have
knock-on effects on ecology. Paragraph 13.5.5 indicates that the severity of impacts will be
covered in the fES, when viaduct design has been developed further. We look forward to seeing
details of the analysis and mitigation proposals. We also look forward to seeing further details on
proposed measures to reduce impacts on the river and lakes from surface water discharge from
the viaduct (13.6.5).
The report states that options are being explored with EA for avoiding and mitigating impacts on
the river, including rechanneling the river to avoid supporting piers in advance of the viaduct
construction starting. If the River Colne is diverted to avoid and reduce impacts from the viaduct
supporting piers, HMWT would expect that the new channel is routed and profiled in a sensitive
and naturalistic manner to improve its ecological value and maintain connectivity through the
landscape. Effective monitoring and remedial action as needed must be implemented over the
course of and after the river diversion. We agree that additional mitigation should be developed for
ecological and hydrological impacts on the Colne river and lakes (para 13.5.14). Opportunities to
undertake restoration work along the affected and adjacent sections of the River Colne to improve
it ecologically should be pursued as part of this mitigation. Any work on the river should reflect and
contribute to the visions, objectives and action plans of the Colne Catchment Action Network. We
would disagree that the diversion of the River Colne is a ‘temporary effect’ (para 7.5.7), as the
diversion will be permanent. It is possible however that the new channel will gradually naturalise
and recover so that there are no significant, permanent adverse effects on the river’s ecological
and hydrological functioning, or on the SSSI.
Air quality impacts
Measures within the CoCP are anticipated to control risks to the SSSI associated with dust
generated during construction of the viaduct, embankments, cuttings and Chilterns tunnel. No
residual effects are expected. The report also indicates that no significant impacts on air quality at
ecological receptors are expected relating to construction traffic. It should be ensured that best
2
Ryan, L. (2013) Translocation and Ancient Woodland. The Woodland Trust.
available methods and technologies are adopted and implemented through the CoCP to minimise
risks to air quality.
Ecology impacts
We note the impacts presented in paragraphs 7.5.9 to 7.5.24, and the summary Table 7. It is not
possible to assess the validity of these conclusions and impact assessments without
having the formal Environmental Statement and all supporting surveys.
Our primary concern relates to disturbance impacts on the wintering and breeding birds in the
Colne Valley. Although the report accepts that disturbance will occur to breeding woodland and
wintering wetland birds from construction in both the SSSI and SMINC, the reasoning given is that
the impacts on breeding woodland birds are temporary (three years) and other parts of the lake will
remain undisturbed. Therefore construction disturbance is considered unlikely to affect viability of
the breeding and wintering bird populations of the SSSI or SMINC. HMWT remains concerned
about the disturbance impacts from construction on the use of the lakes by birds, and their patterns
of movement through the wetland complex of the Colne Valley. It must be accepted also that three
years (or more if construction overruns) is quite a significant length of time. We would like to see
further details and supporting evidence behind the assertions and reasoning of HS2 Ltd in respect
of disturbance impacts on birds.
HS2 Ltd considers that the primary impacts of concern for the SSSI and SMINC relate to loss of
woodland habitat. Although ancient woodland is by its nature irreplaceable, we accept that
appropriate woodland creation alongside enhancement of existing ancient woodland in the area via
ongoing management could help compensate for the ecological impact. As explained before, we
do not consider that new woodland creation offsite qualifies as ‘mitigation’. We would hope to see
a more extensive package of mitigation and compensation options put forward in the fES, as
suggested in paragraph 7.5.26, to compensate for habitat loss and degradation in the SSSI and
SMINC. Provision of nesting boxes and tern rafts (paragraph 7.5.26) is inadequate.
It is considered that mitigation for disturbance impacts on the wetland birds will be required, for
instance through habitat improvements within unaffected parts of the lakes in advance of
construction to improve their suitability for key wetland bird species. HMWT considers there is
significant potential to improve the quality of the wetland and marginal habitats at Broadwater Lake
and other lakes within the Colne Valley complex, which should be explored as part of a mitigation
and compensation package.
The report predicts a temporary adverse effect on the conservation status of Daubenton’s bats due
to fragmentation of an important movement corridor. The fES must include proposals for mitigation
to reduce the significance of this impact. Although some bat roosts will be lost, HMWT is satisfied
that adequate provision of alternative bat roost sites in suitable, undisturbed locations will provide
suitable mitigation.
It is agreed that adverse impacts on movement of otters along the Colne can be avoided and
mitigated through maintaining undisturbed areas of suitable and connected habitat. Further details
on how this will be achieved are required, and this should be integrated into the local environment
management plans.
Floating pennywort and Japanese knotweed are present along the River Colne. It must be
ensured that these invasive species are suitably managed during construction and works in the
area in order to prevent their spread. Invasive species management plans should be incorporated
into the CEMP and local environment management plans.
The dES is very brief in its coverage of operational impacts. The conclusions assume that
operation of the line will not have adverse impacts on birds in the Colne Valley, as they are
expected to habituate to the noise disturbance. HMWT considers that more evidence must be
provided in the fES to support this assertion. Advice should be sought from leading experts
nationally on noise and light disturbance impacts on wetland bird behaviour, and the precautionary
priniciple should be maintained where evidence is uncertain. We would encourage measures to
reduce impacts on wetland bird populations in the Colne Valley, through for instance habitat
enhancement and management in undisturbed areas away from the line to increase the availability
and attractiveness of alternative habitat for birds.
The report indicates that barriers will be put along the viaduct to mitigate noise and visual
disturbance. Although barriers would be welcome, the landscape importance of the Colne Valley
requires due regard to be taken as to its visual impact as well as functionality in reducing noise
pollution. HMWT would also like options for ‘greening’ the viaduct to be explored, such as
installing bat and bird boxes.
Collisions of bats and birds with trains, the viaduct and overhead line structure are a cause for
concern, as the River Colne and the Colne Valley are a movement corridor for Daubenton’s bats
and migrating birds. More detail must be provided on the expected impacts on birds and bats from
collision, and mitigation measures to reduce frequency of collision.
No mention is made of potential artificial lighting impacts from lighting along the line, viaduct and
ancillary structures. Lighting may result in disturbance of bats and birds, modify collision risks and
exacerbate the barrier effect of the viaduct to wildlife movement along the Colne Valley.
Further work needed
Significant work will be required by HS2 Ltd and its contractors in order to gather the required
outstanding ecological survey data and undertake further analyses in advance of the publication of
the Hybrid Bill and formal ES. HS2 Ltd should make every effort to work with statutory agencies
and organisations including affected Wildlife Trusts to ensure that the surveys and analyses are
robust and meet accepted ecological best practice standards.
The mitigation and compensation proposed in the dES is incomplete. Significantly more detail will
be needed for the fES. Although the suggestions put forward (woodland planting and bird boxes,
bat boxes and tern rafts) could be part of a suite of measures, this alone would be weak and
inadequate.
HMWT considers that there is significant potential for the wetland habitats at Broadwater Lake and
other parts of the Colne Valley complex to be significantly improved to the benefit of the important
wetland bird populations and other wildlife. This should be explored alongside other options for
habitat management, restoration and enhancement in the Colne Valley and Colne Valley Regional
Park in advance of the Hybrid Bill.
HS2 Ltd should consult and work with HMWT and other local environmental interest groups to
ensure that the proposed mitigation and compensatory habitat creation is suitable for the area and
fits in with local ambitions and opportunities for ecological enhancement and restoration.
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Herts & Middlesex Wildlife Trust
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Colne Valley Community Interest Company
London Wildlife Trust
Colne Catchment Action Network (ColneCAN)
Odette Carter
Planning and Policy Officer
Herts and Middlesex Wildlife Trust
Grebe House
St Michael’s Street
St Albans AL3 4SN
01727 858901
odette.carter@hmwt.org
www.hertswildlifetrust.org.uk
Protecting Wildlife for the Future
Registered in England No 816710 Registered Charity No 239863