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The Yorkshire and Humber (CCS Cross Country Pipeline) DCO
Application Reference: EN070001
January 2015
Offshore Scheme Shadow Appropriate Assessment Report
The Yorkshire and Humber (CCS Cross Country
Pipeline) Development Consent Order
11.9 D
O C
U M
E N
T
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1 Introduction 1
1.1 Introduction 1
1.2 The Project 2
1.3 Need for the Project 3
1.4 Requirement for a Habitat Regulations Assessment 5
Legislative Context 5
1.5 Consultation On the information Required for the SAA 6
2 HRA Process 10
2.1 Introduction 10
3 Offshore Scheme Description 12
3.1 Introduction 12
3.2 Components of the Offshore Scheme 12
3.3 Location of the offshore scheme 12
3.4 Pipeline Installation 14
Nearshore Pipeline 16
Offshore Pipeline 17 Crossings 18
Duration of the installation 19
3.5 The Normally Unmanned Installation (NUI) 19
Installation of the NUI 19
3.6 Operation of the Offshore Scheme 20
Pipeline 20 NUI 20 Storage Site Monitoring 20
3.7 Decommissioning of the Offshore Scheme 22
4 Baseline Conditions 24
4.1 Introduction 24
4.2 Review of coastal processes 24
4.3 Marine Mammals 28
4.4 Seabirds 31
5 Screening (Stage 1) 36
5.1 Introduction 36
5.2 Screening 36
TABLE OF CONTENTS
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Sources of effect 36 Receptors / Pathways 36 Mechanism for effect 37
6 Site Descriptions 42
6.1 Introduction 42
6.2 Humber Estuary Protected Sites 42
Qualifying features and conservation objectives 42
6.3 Flamborough Head and Bempton Cliffs SPA 47
Qualifying Features and Conservation Objectives 47
6.4 Flamborough Head and Filey Coast pSPA 48
Qualifying Features and Conservation Objectives 48
6.5 Flamborough Head SAC 49
Qualifying Features and Conservation Objectives 50
6.6 The Wash and North Norfolk Coast SAC 51
Qualifying Features and Conservation Objectives 52
7 Potential for Adverse Effect on Site Integrity (Stage 2) 54
7.1 Introduction 54
7.2 Installation of the pipeline 54
Nearshore Pipeline 54
Offshore Pipeline 56
Anchor Mounds 58
Rock Cover 58
7.3 Disturbance from installation & vessels 59
Marine Mammals 59 Seabirds 60
7.4 Disturbance from Underwater Noise during Installation 62
Pipeline Installation 62
Drilling activities 63 NUI Installation 64
7.5 Operation of the Offshore Scheme 66
Underwater noise from NUI operation 66 Storage Site Monitoring 67
Vessel activity 70 Lighting 70
8 In combination Assessment 86
8.1 Introduction 86
8.2 Relevant Developments 86
Dogger Bank Creyke Beck Offshore Wind Farm 86 Hornsea Offshore Wind Farm – Project One 86 Hornsea Offshore Wind Farm – Project Two 87
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Hornsea Offshore Wind Farm – Project Three 87
8.3 Potential for in-combination effects 87
9 Conclusion 94
10 References 95
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1.1 INTRODUCTION
1.1.1 National Grid plc owns and operates the national high-pressure gas
transmission pipeline network in the UK and operates the national electricity
grid in the UK. National Grid Carbon (referred to in this report as “National
Grid”) is a non-regulated, independent subsidiary of National Grid plc, created
to develop Carbon Dioxide transportation and storage infrastructure in the UK.
1.1.2 National Grid is developing a project to support the provision of CCS
technology in the Yorkshire and Humber Region. The Project, in its entirety, is
known as The Yorkshire and Humber CCS Transportation and Storage Project
(“the Project”). It would comprise the construction of a Cross Country Pipeline
and sub-sea Pipeline for transporting Carbon Dioxide captured from power
projects in the region to a permanent geological storage site beneath the North
Sea.
1.1.3 For the purposes of consenting, the project is split into two schemes, named
the Onshore Scheme and the Offshore Scheme. The Offshore Scheme
application is being submitted after that for the Onshore Scheme; however for
the purposes of assessment under the Habitats Regulations National Grid has
been advised that both the Onshore and Offshore Schemes should be
considered together as one project. Therefore, although the Planning
Inspectorate (PINS) is not the Competent Authority for the Offshore Scheme,
information is being provided for both the Onshore Scheme (in the form of the
No Significant Effects Report – Document 5.4) and the Offshore Scheme (in the
form of this ‘Shadow’ Appropriate Assessment Report (SAAR This SAAR is
being submitted to Natural England, so that Natural England can confirm to the
Examining Authority that there is sufficient information before them to enable
the Examining Authority to report on Habitat Regulations Assessment issues
and, accordingly, for the Secretary of State to carry out the Appropriate
Assessment, as the Competent Authority. This is because, when taking both
reports into consideration it is possible to understand the implications of the
project as a whole for Natura 2000 sites, during the consenting period for the
Onshore Scheme.
1.1.4 This SAAR for the Offshore Scheme has been prepared under The
Conservation of Habitats and Species Regulations 2010 (the ‘Habitats
Regulations) which transposes the requirements of Article 6(3) of the Habitats
1 Introduction
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Directive 92/43/EEC. The Offshore Scheme will be subject to the Marine
Conservation (Natural Habitats + c) (amendment) Regulations 2007 which
transpose the Directives for the offshore marine areas beyond 12 nm.
1.2 THE PROJECT
1.2.1 The Project proposed is a Carbon Dioxide transportation and storage system to
support the provision of carbon capture and storage (CCS) technology in the
Yorkshire and Humber Region. The Project, in its entirety known as The
Yorkshire and Humber CCS Transportation and Storage Project (“the Project”),
would comprise the construction of a Cross Country Pipeline and sub-sea
pipeline for transporting Carbon Dioxide captured from power projects in the
region to a permanent geological storage site beneath the North Sea. The
Project includes both onshore and offshore elements which are subject to
separate consenting regimes (the “Onshore Scheme” and the “Offshore
Scheme”).
1.2.2 The onshore elements of the Project are collectively termed the Yorkshire and
Humber CCS Cross Country Pipeline (shortened to the “Onshore Scheme”)
and are proposed to comprise the construction of a Cross Country Pipeline and
associated infrastructure including Pipeline Internal Gauge (PIG) Traps, a Multi-
junction, three Block Valves, a Pumping Station (collectively termed “Above
Ground Installations” or “AGIs”) and any necessary interconnecting local
pipelines and associated works.
1.2.3 The offshore elements of the Project are collectively termed the Yorkshire and
Humber CCS Sub-Sea Pipeline and Geological Storage Site (shortened to the
“Offshore Scheme”) and are proposed to comprise the construction of a 90 km
sub-sea pipeline to a geological storage site. This is subject to a separate
consenting regime requiring authorisation by the Secretary of State for Energy
and Climate Change in accordance with the Petroleum Act 1998 (for the
pipeline) and the Energy Act 2008 (for the geological storage site).
1.2.4 The Onshore and Offshore Schemes would be joined at Mean Low Water
Spring (MLWS) using appropriate landfall techniques; this is also the juncture
of the Onshore and Offshore consenting regimes.
1.2.5 Certain elements of the Offshore Scheme are subject to ongoing options
appraisal, and the Project in its entirety is at a Front End Engineering Design
(FEED) stage. The description of the Offshore Scheme that is presented within
this document is a “likely case” development scenario given the facts available
at the time of writing, for instance the footprint of the final Offshore Scheme is
unlikely to be larger than that presented.
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1.2.6 A separate Environmental Impact Assessment is being undertaken, and an
Environmental Statement is being prepared for the Offshore Scheme, which will
accompany the application to DECC.
1.2.7 The indicative offshore pipeline route and platform location are shown in Figure
1.1, in addition to the two-dimensional extent of the geological storage
structure. A final pipeline approach to the platform is yet to be selected, and an
extensive area over the storage structure has been surveyed to provide
flexibility in deciding this final approach.
Figure 1.1 Overview of the Offshore Scheme
1.3 NEED FOR THE PROJECT
1.3.1 The full need case is presented in Document 7.4 a summary is provided below.
1.3.2 The burning of fossil fuels, such as coal and gas, to generate electricity is a
major source of carbon dioxide emissions into the atmosphere, accounting for
40 per cent of global energy related carbon dioxide emissions – a greenhouse
gas and major contributor to global climate change.
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1.3.3 Significant steps are now being taken to reduce global carbon dioxide
emissions and a number of countries and international bodies have policies
and initiatives in place to address this issue.
1.3.4 Carbon Capture and Storage (CCS) has been identified as one initiative with
potential to create large reductions in carbon dioxide emissions. The
International Energy Agency (IEA) has described CCS as “a critical greenhouse
gas reduction solution.”
1.3.5 The UK Government has a policy to increase the use of low carbon
technologies including CCS. The Government has stated that:
“CCS is the only way we can reduce carbon dioxide emissions and keep fossil
fuels (coal and gas) in the UK’s electricity supply mix. Fossil fuels are an
important part of the electricity mix (and will remain so for some time to come)
because they let us balance the intermittency of wind and the inflexibility of
nuclear.”
1.3.6 Whilst much is known about the respective methods of capturing, transporting
and storing carbon dioxide, CCS has yet to be demonstrated in the UK on a
commercial scale. In the Government’s over arching energy policy statement,
known as EN-1, it states:
”The Government is leading the international efforts to develop CCS. This
includes supporting the cost of four commercial scale demonstration projects at
UK power stations. The intention is that each of the projects will demonstrate
the full chain of CCS involving the capture, transportation and storage of
carbon dioxide in the UK. These demonstration projects are therefore a priority
for UK energy policy. The demonstration programme will also require the
construction of essential infrastructure (such as pipelines and storage sites)
that are sized and located both for the purpose of the demonstration
programme and to take account of future demand beyond the demonstration
phase.”
1.3.7 Yorkshire and Humber is the most energy-intensive region in the UK. Its
concentration of fossil fuel power stations provides around 18 per cent of the
nation’s electricity generation and the region is also the location for a significant
amount of heavy industry.
1.3.8 This concentration of power stations and industrial plants produces about 60
million tonnes of carbon dioxide every year, equivalent to about half of the total
emissions from domestic homes in the UK. Most of these facilities are located
relatively close together and are also located within approximately 100
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kilometres of the East Yorkshire coast, providing good access to offshore
storage locations beneath the North Sea seabed.
1.3.9 Because of these factors, the Yorkshire and Humber region is considered to be
the ideal location to demonstrate CCS as a technology on a commercial scale,
with a view to promoting the development of a shared regional CCS
transportation network. Allowing multiple emitters to connect to shared CCS
infrastructure over time would enable the capture and storage of tens of
millions of tonnes of carbon dioxide that ordinarily would have been emitted to
the atmosphere.
1.4 REQUIREMENT FOR A HABITAT REGULATIONS ASSESSMENT
Legislative Context
1.4.1 European Directive 92/43/EEC on the ‘Conservation of Natural Habitats and
Wild Fauna and Flora’, referred to as the ‘Habitats Directive’, and Directive
2009/147/EC of the European Parliament and of the Council of 30 November
2009 on the conservation of wild birds (the codified version of Council Directive
79/409/EEC on the conservation of wild birds), referred to as the ‘Birds
Directive’ provide legal protection for habitats and species of European
importance. Article 2 of the Habitats Directive requires the maintenance or
restoration of habitats and species of European Community interest, at a
favourable conservation status. Articles 3 - 9 provide the legislative means to
protect habitats and species of Community interest. In particular, Article 6 (3) of
the Directive states:
“Any plan or project not directly connected with, or necessary to, the
management of the [European] site, but likely to have a significant effect
thereon, either individually or in combination with other plans or projects, shall
be subject to appropriate assessment of its implications for the site in view of
the site's conservation objectives”.
1.4.2 These directives are transposed into domestic law by the Conservation of
Habitats and Species Regulations 2010 (England and Wales) (as
amended).The Regulations enable the protection of sites that host habitats and
species of European Importance. These sites are listed below and are
collectively referred to as Natura 2000 Sites or ‘European Sites’.
Special Areas of Conservation (SAC);
Special Protection Areas (SPA); and
Ramsar Sites
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Special Areas of Conservation
1.4.3 Special Areas of Conservation (SAC) are high quality conservation sites that
have been given protection under the European Habitats Directive
(92/43/EEC). These important sites are selected to conserve rare and
vulnerable animals, plants and habitats (excluding birds) that are listed in
Annexes I and II of the Directive (as amended).
Special Protection Areas
1.4.4 Special Protection Areas (SPA) are protected sites that have been
implemented to protect rare and vulnerable bird species and their habitats.
They are classified in accordance with the Council Directive 2009/147/EC
(Birds Directive) the Conservation of Wild Birds (the codified version of Council
Directive 79/409/EEC on the conservation of wild birds) and aim to safeguard
bird species and populations that are listed in Annexes I and II of the Directive.
1.4.5 Part II, Paragraph 10 of The Conservation of Habitats and Species Regulations
2010 (England and Wales) provides a definition of the term “European Site”
which it identifies as including SAC and SPA sites, as well as candidate /
proposed sites (cSAC and pSPA) which are being consulted on or are pending
a European Commission decision. However, the Habitats Regulations do not
provide statutory protection for pSPAs or to cSACs before they are agreed with
the European Commission. For the purpose of considering development
proposals and their likely impacts on such sites, as a matter of policy, the UK
Government wishes those pSPAs and cSACs that have been included in a list
sent to the European Commission, to be considered in the same way as if they
have already been classified or designated.
Ramsar Sites
1.4.6 Ramsar sites are wetlands of international importance that have been
designated under the Ramsar Convention (1971). Sites are selected for their
international significance relating to all ecology, botany, zoology, limnology or
hydrology wetland components. The designation recognises the importance of
wetlands as economic, social and environmental entities and the need to
conserve them.
1.5 CONSULTATION ON THE INFORMATION REQUIRED FOR THE SAA
1.5.1 As a result of consultation with Natural England, National Grid was advised that
effects on Natura 2000 sites, as a result of some of the elements of the
Offshore Scheme, could not be ruled out and that the Habitats Regulations
Assessment (HRA) therefore needed to move to the Stage 2 - Appropriate
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Assessment. This Shadow Appropriate Assessment Report has been provided
to enable Natural England to confirm to the Examining Authority that there is
sufficient information available for the competent authority to carry out an
appropriate assessment and for the Examining Authority to report to the
Secretary of State on that basis.
1.5.2 Table 1.1 highlights those aspects of the Offshore Scheme which, in
consultation with Natural England, have been identified as potentially being a
source of effects on Natura 2000 sites. The table also identifies the specific
information about each of the sources that is considered necessary in order to
inform the assessment.
Table 1.1: Roadmap for the SAA of the Offshore Scheme.
Potential source of
likely significant
effect
Information Required
Coastal Processes and Sediment Transport
The installation of the
intertidal pipeline and
the use of rock
armouring may impact
on sediment transport
and physical coastal
processes, with
potential impacts on
habitats and
associated impacts on
bird species which are
interest features of the
Humber Estuary SAC,
SPA and Ramsar site.
A comprehensive desk-based review to show what
components of the Offshore Scheme may cause
changes to sediment transport, physical coastal
processes and potential impacts to designated sites.
In particular attention should be paid to the potential
effects of any use of rock armouring. The review
should scope the potential need for coastal processes
modelling if required.
The ideal burial depth of pipeline (subsea geology
permitting) with particular focus on the nearshore and
intertidal zones.
Confirmation of intertidal pipeline installation methods
and duration of works.
A preliminary estimate or worst case scenario of the
need for rock armouring should be provided, as a
remedial measure for pipeline scour and subsequent
exposure
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Table 1.1: Roadmap for the SAA of the Offshore Scheme.
Potential source of
likely significant
effect
Information Required
An assessment of the suitability of limiting rock
armouring to seabed level only.
The material to be used for any rock armouring, and
method of deployment.
Disturbance to Marine Mammals
Installation, operation
and decommissioning
of the normally
unmanned installation
may impact on marine
mammals, specifically
grey seals which are a
qualifying feature of the
Humber Estuary SAC
and Ramsar site, and
harbour seals which
are a qualifying feature
of The Wash and North
Norfolk Coast SAC.
Further information is therefore required on noise
levels and any other potential effects upon marine
mammals during installation, operation and
decommissioning of the NUI, and the need for a
marine mammal observer and suspension of works.
Disturbance to seabirds
Elements of the
Offshore Scheme may
also impact on bird
species which are
qualifying features of
the Flamborough Head
and Bempton Cliffs
SPA and Flamborough
Head and Filey Coast
pSPA.
The information in Table 5.4 and Appendix 5.4.12 of
the No Significant Effects Report refers to foraging
activity of the interest features of the pSPA. However,
potential impacts will also need to be considered on
young guillemot and razorbill which are flightless and
therefore sensitive to disturbance during the
anticipated pipeline installation period in June/July.
The source of the data presented in Table 1 and the
figures in Appendix 5.4.12 should also be clarified.
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Table 1.1: Roadmap for the SAA of the Offshore Scheme.
Potential source of
likely significant
effect
Information Required
-
Further information is also required to enable the
following to be included as part of the Appropriate
Assessment:
Construction, operation and decommissioning
of the Offshore Scheme may have effects on
the qualifying features of European sites, in
combination with other plans and projects.
Details of monitoring, control measures and
safeguards to ensure impacts are as predicted.
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2.1 INTRODUCTION
2.1.1 The methodology for HRA takes cognisance of the EU guidance document
‘Assessment of plans and projects significantly affecting Natura 2000 sites,
Methodological guidance on the provisions of Article 6(3) and (4) of the
Habitats Directive 92/43/EEC’.
2.1.2 It has become generally accepted that a staged approach should be followed
for a HRA as proposed by the latest European Commission guidance and as
set out in the Planning Inspectorate’s Advice Note Ten: Habitat Regulations
Assessment relevant to Nationally Significant Infrastructure Projects. These
stages are:
Stage 1 Screening — the process which identifies whether there are likely to
be any effects upon a Natura 2000 site as a result of the Onshore Scheme,
either alone or in combination with other projects, and considers whether these
effects are likely to be significant.
Stage 2 Appropriate Assessment — the consideration of the effect on the
integrity of the Natura 2000 site, with respect to the site’s structure and function
and its conservation objectives. Additionally, where significant adverse effects
on site integrity exist, an assessment of potential mitigation will be made.
Stage 3 Assessment of Alternative Solutions — the process which
examines alternative ways of achieving the objectives of the Onshore Scheme
that avoids significant adverse effects on the integrity of the Natura 2000 site
identified at Stage 2.
Stage 4 Assessment of IROPI – where no alternative solutions exist, and
where significant adverse effects remain, an assessment of compensatory
measures where, in the light of an assessment of imperative reasons of
overriding public interest (IROPI), it is deemed that the Onshore Scheme
should proceed.
2.1.3 Each stage determines whether a further stage in the process is required. If, for
example, the conclusions at the end of Stage 1 are that there are no likely
significant effects on a European Site, there is no requirement to proceed to
Stage 2 or any subsequent stages. This process is illustrated in Figure 2.1
below, with each stage being broken down into a number of steps.
2 HRA Process
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Figure 2.1: HRA Process
Step 1 Management Test: Is the onshore scheme directly connected with or
necessary to the management of the site(s) for nature conservation?
Step 2 LSE Test: Is the Onshore Scheme likely to have a significant effect on
the internationally important interest features of the site, along or in combination
with other plans and projects. Sta
ge 1
Scre
en
ing
Step 3 Appropriate Assessment: Are there implications on the site’s
conservation objectives?
Sta
ge 2
Ap
pro
pri
ate
Asse
ssm
en
t
Step 4 Integrity Test: Can it be ascertained that the proposal will not adversely
affect the integrity of the site?
Would compliance with conditions / other restrictions enable it to be ascertained
the Onshore Scheme would not adversely affect the integrity of the site.
Step 5: Are there alternative solutions that would have a lesser effect, or avoid
an adverse effect, on the integrity of the site?
Sta
ge
3
Asse
ssm
en
t o
f
Alt
ern
ati
ves
Step 6: Might a priority habitat or species on the site be adversely effected by
the proposal?
Sta
ge
4
Asse
ssm
en
t o
f
IRO
PI
Step 7: are there IROPI which
could be of a social or economic
nature?
Step 8: Are there IROPI relating
to human health, public safety or
important environmental
benefits?
Permission must not
be granted Step 9: Permission may be
granted subject to the
Secretary of State securing
the necessary compensatory
measures
Step10: Authorisation
may be granted following
consultation between the
Government and
European Commission,
subject to securing
compensation measures
Permission
may be
granted
No
Yes
No / Uncertain
No / Uncertain
Yes
No
No Yes
Yes Yes
No No
No
No
Yes
Yes
Yes
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3.1 INTRODUCTION
3.1.1 This Chapter sets out a description of the Offshore Scheme. Certain elements
of the Offshore Scheme are subject to ongoing options appraisal, and the
Project in its entirety is at a Front End Engineering Design (FEED) stage. The
description below is a the most likely development scenario given the facts
available at the time of writing, for instance the footprint of the final Offshore
Scheme is unlikely to be any larger than that presented below.
3.2 COMPONENTS OF THE OFFSHORE SCHEME
3.2.1 The Offshore Scheme comprises a Pipeline approximately 90km in length
linking the landfall to a Normally Unmanned Installation (NUI) for the purpose of
transporting and storing carbon dioxide in a geological storage site (a Triassic
Bunter Sandstone Formation saline aquifer).
3.3 LOCATION OF THE OFFSHORE SCHEME
3.3.1 The location of the Offshore Scheme is illustrated in Figure 3.1 below.
3 Offshore Scheme Description
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Figure 3.1 Location of the Offshore Scheme
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3.4 PIPELINE INSTALLATION
3.4.1 The Pipeline will comprise approximately 90 km of 610 mm concrete coated
carbon steel pipeline; the coating to provide stability and protection.
3.4.2 The proposed Pipeline route has been selected on the basis of desk-based
options appraisal and subsequent offshore survey, and has been optimised
based on, for instance, the occurrence and orientation of large sand ridges, the
avoidance of outcropping bedrock, and the avoidance of conservation sites,
including Natura 2000 sites and Marine Conservation Zones.
3.4.3 From the landfall the offshore pipeline will be laid in a pre-dredged trench for
approximately 16 km with an additional 11 km comprising of post-lay trenching.
The offshore pipeline will be surface laid for the remaining 63 km; though some
of this length will require ‘pre-sweeping’ of sand waves. Please refer to Figure
3.2 below.
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Figure 3.2: Spatial extent of pipeline installation seabed works
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3.4.4 A geophysical survey and subsequent geotechnical survey of the proposed
pipeline route indicates that there are no obstructions that would prevent such
an approach to installation, and similar techniques have been employed for
existing pipelines associated with the Easington gas terminal, such as York
(RPS 2011) and Langeled (Metoc 2004).
3.4.5 In the following sections, and subsequently within the report, distances along
the pipeline route are referred to by ‘kilometre point’ (KP), which is the seaward
distance along the route, commencing at the tie-in location.
Nearshore Pipeline
3.4.6 The nearshore pipeline comprises of the section of pipeline illustrated by pre-
lay trenching on Figure 3.2.
3.4.7 The pipeline will be buried at a minimum depth of 4 m from the tie in location for
approximately 3.7 km. This depth has been designed to allow for predicted
future coastal erosion rates, to ensure the pipeline does not become exposed
within the lifetime of the project. Table 3.1 sets out the dimensions of the
trench for the nearshore pipeline up to KP16.3.
Table 3.1 – Dimensions of nearshore access channel and pipeline trench
Nearshore pre-lay trench
KP0-3.7
Nearshore pre-lay trench KP3.7-9.2
Nearshore pre-lay trench KP9.2-16.3
Width at base 5m 5m 5m
Depth 4m 5m 2m
Length 3,700m 5,500m 7,050m
Side angle of trench 30˚ 30˚ 30˚
Estimated volume of material sidecast
170,900m3 396,900m3 81,400m3
Estimated loss of material
17,090m3 39,690m3 8,140m3
Estimated total volume of material sidecast 649,230m3
Estimated total loss of material 64,923m3
3.4.8 With the exception of two sections of the route between KP2.267 and 2.426,
and at KP10.19, where sand and boulder clay sediments thin to 0.6m and 1m
respectively with shallow subcropping chalk present, the entire route has
sufficient depth of soft seabed sediments to achieve the desired trench depth.
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3.4.9 The nearshore trench will be constructed with a backhoe dredger (shallow
draught vessel equipped with a hydraulically operated mechanical arm with
excavator bucket) for the first 1 km of trench to the 5m depth contour (the
closest the lay barge can get to shore ) and thereafter a cutter suction dredger
vessel will be used to construct the trench. The material excavated from the
trench will be side cast and will then be backfilled on top of the pipeline to the
former seabed level.
3.4.10 Some rock cover may be required to provide nearshore pipeline stability on
installation and prior to backfilling. It is estimated that a maximum of 6,000m3
of rock, with an average diameter of 400 mm, may be required, extending from
the tie-in location to 1 km offshore. This material would be buried during
pipeline backfilling, avoiding rock presence or a reduction in water depths in the
nearshore area.
3.4.11 As this part of the pipeline is to be trenched and buried, no rock armouring is
proposed in this area, with the exception of the crossings of the cables
associated with the Dogger Bank Creyke Beck A and B wind farms. These are
described and considered in Section 3.4.18; of necessity rock armouring used
in the construction of the crossings will extend above the seabed level.
Offshore Pipeline
3.4.12 The section of pipeline from KP16.25 to 27.25 will initially be surface laid and
will then be subject to post-lay trenching. The section of pipeline between
KP27.25 and the NUI at KP90 will be surface laid and, though a section
between KP47 and the NUI will be subject to pre-sweeping. The installation
may take place using the same s-lay vessel used to install the pipeline in the
nearshore section, but alternatively a separate dynamically positioned vessel
could be used.
3.4.13 The pre-sweeping of sandwaves between KP47 and the NUI, and the pipeline
concrete coating, should avoid any need to immediately remediate freespans,
or provide additional protection measures for the offshore pipeline.
3.4.14 In order to reduce the possibility of freespans occurring on installation, and
subsequently from interaction with mobile bedforms, pre-sweeping will take
place, possibly in combination with remedial rock placement where necessary
(rock cover will be required should freespans occur and exceed 0.5m depth).
The need for future remedial work to be undertaken, to ensure safe operation
of the pipeline, will be assessed through routine (on average annual) inspection
surveys.
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3.4.15 Initial estimates, based on the required reduction in pipeline stress from
freespans, are that large sandwaves between KP47 and the storage site will
need to be truncated by between 2m and 5m to a trench bottom width of 10 m
with 30˚ sides. Depending on the final selection for the steel pipeline wall and
concrete coating thickness, between 150,000 and 550,000 m3 of material
would need to be removed (see Figure 3.2 for an indication of the area to be
pre-swept). The sediment is primarily slightly gravelly sand, and will most likely
be removed using a trailing suction hopper dredger, in a worst case affecting
an area of seabed 410,000 m2. Material will be temporarily stored on the
vessel and deposited at a licensed disposal site.
Crossings
3.4.16 The carbon dioxide export pipeline route crosses the 44” Langeled pipeline and
possibly four power cables (two lain in tandem in separate trenches) associated
with the Dogger Bank Creyke Beck A and B wind farms.
3.4.17 The nature and timing of the cable crossings will depend on project phasing,
however, it has been assumed for the purposes of assessment that the wind
farm cables are crossed by the pipeline. The precise location of the crossing is
uncertain as the cable export agreement area has a width of 7 km, with
crossing locations therefore possible along the pipeline route between
approximately KP8 and KP17 in corresponding water depths of between 10
and 40 m – it is anticipated that for navigational safety reasons the crossings
will be made in the deeper water area. The pipeline will exit the trench at 100
m before and after the cable crossing, with the crossing also having a width of
100 m and length of 50 m resulting in overall crossing dimensions of 300 m x
50 m for each of the cable sets. Each crossing will require a number of
concrete mattresses of typical dimensions 6 m x 3 m x 0.15 m to cover the
buried cable route prior to the laying of the offshore pipeline. There will be a
post-lay rock cover of 0.5 m over the pipeline comprising 1,600 m3 (2,655
tonnes) of rock per crossing.
3.4.18 The Langeled crossing method is analogous to that for the cable crossings,
however as it will take place on the surface laid section of pipeline (at
approximately KP38) there will be no requirement for protection associated with
the pipeline transitioning to and from the trench and therefore the crossing is
substantially shorter (up to 100 m wide). A number of concrete mattresses of
typical dimensions 6 m x 3 m x 0.15 m will be used to achieve a minimum
separation distance between the two pipelines, and four concrete pre-lay
supports at between 19 m and 26 m distance apart along the crossing. Around
1,350 m3 (2,220 tonnes) of rock cover will be placed over the crossing and
have a minimum rock cover height of 0.5 m.
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Duration of the installation
3.4.19 The pipelay activities are transient, the lay rate of the nearshore installation out
to the 30 m depth contour (approximately 15 km) is approximately 500 m a day
in the nearshore area and 4 km a day for the Offshore Pipeline. The Offshore
Pipeline installation is not expected to exceed 4 months in duration in total.
3.5 THE NORMALLY UNMANNED INSTALLATION (NUI)
3.5.1 The NUI is located approximately 65 km from the coast and will comprise of a
steel jacket platform secured to the seabed using six piles. The NUI will have a
control system, refuge and life support facilities, a helideck, boat landing deck,
diesel power generation and facilities for diesel, chemical and hydraulic fluid
storage. There will also be facilities for chemical injection and hydraulic control.
There will be no drilling facilities on the platform and drilling will be undertaken
by a jack-up rig.
Installation of the NUI
3.5.2 The NUI structure consists of a conventional steel jacket with four legs. The
direct physical footprint of the platform will comprise the area of the jacket in
contact with the seabed and the pile footprint. The jacket will be fixed to the
seabed with pin piles (6 piles each with a diameter of 1,829 mm) which will be
driven to a depth of approximately 55 m using either percussive piling methods
or drill and grout piling. Drill and grout piling involves pre-drilling where hard
seabed substrates are present (e.g. subcropping chalk), into which the piles are
driven and the annular space between the pile and rock is subsequently filled
with grout.
3.5.3 The jacket and topsides will be transported to their final location in a series of
barge and vessel transits.
3.5.4 A number of carbon dioxide injection wells (initially 3) will be drilled at the NUI
location using a jack-up rig which will be towed to site. The wells may be pre-
drilled using a seabed template prior to the installation of the NUI or drilled
following its installation.
3.5.5 Drilling will be undertaken by a jack-up rig, with each of the rig’s three legs
terminating in a spud can (base plate) of approximately 17 m in diameter, with
spud can centres spaced equidistant at approximately 75 m. Each would form
a seabed depression of approximately 185 m2 as a result of sinking into the
seabed during the process of jacking the rig legs to support the drilling deck.
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3.5.6 Stabilisation material may be required for scour protection around the rig spud
cans. The worst case estimated use of rock is 600 tonnes of 12-15 cm stones
if all three legs require stabilising. Assuming an average depth of cover of 30
cm this would cover a total of some 1,000 m2 of seabed. If used, these stones
will be left in situ following completion of drilling operations. It should be noted
that this contingency was not required for appraisal well drilling over the
storage site, and a rig site survey will be undertaken prior to rig siting to inform
whether this is required. There may be a requirement for the drilling rig to
return for well intervention works during first Phase operations. Any
incremental physical disturbance is minimised as the rig will be sited in the
same position as when the wells were first drilled.
3.5.7 A seabed template may be pre-installed to allow for injection wells to be drilled
prior to siting the platform. If required, installation of the template would result
in a small area of seabed disturbance, though this would be placed immediately
beneath the intended platform location and so would not result in appreciably
enhanced seabed disturbance.
3.6 OPERATION OF THE OFFSHORE SCHEME
Pipeline
3.6.1 An as-laid Pipeline survey will be undertaken following Pipeline installation.
During operation it is standard practice for a Pipeline inspection survey to be
undertaken at 1-2 yearly intervals as part of routine maintenance activity. This
is undertaken for safety reasons to minimise any snagging hazards.
NUI
3.6.2 The platform will be operated from a control room onshore. Regular supply
trips are not envisaged and the platform is expected to be unmanned for 6-7
weeks at a time. In keeping with other Project elements, the platform is
expected to have a 40 year lifespan.
3.6.3 Power will be provided to the NUI via three diesel turbine generators, however
during normal operation only one will be required. Diesel and any other
chemicals required will be bunkered via supply vessel and maintenance crews
will visit the NUI via helicopter.
Storage Site Monitoring
3.6.4 In accordance with the CCS Directive (2009/31/EC) monitoring of the site will
be undertaken to both confirm and augment the modelled carbon dioxide plume
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formation and also to assist in detecting any irregularities. An aspect of the
monitoring will involve time-lapse seismic survey.
3.6.5 Criteria for establishing a monitoring plan are contained in Annex II of the CCS
Directive (and transposed through Schedule 2 of the Storage of Carbon Dioxide
(Licensing etc.) Regulations 2010), and a provisional Monitoring Plan (MP) will
be submitted along with the Carbon Storage Permit application which the ES
for the Offshore Scheme will support. This plan must be updated within 5 years
of approval, to take account of changes to the assessed risk of leakage,
changes to the assessed risks to the environment and human health, new
scientific knowledge and improvements in best available technology.
3.6.6 A report must be submitted annually detailing the results of the monitoring, the
quantities, properties and composition of the carbon dioxide streams injected,
proof of continued financial security, and any other information that the
authority considers relevant (e.g. to assess compliance or to increase
knowledge of the behaviour of stored carbon dioxide).
3.6.7 Models have been constructed to simulate the carbon dioxide plume formation
within the storage site as required by Annex I of the CCS Directive
(2009/31/EC), and these would be updated as knowledge of behaviour of the
carbon dioxide plume improves through monitoring. The simulations have used
appraisal well results (e.g. porosity and permeability), have informed potential
platform locations and well trajectories, and also assisted in the further
understanding of overall site storage capacity.
3.6.8 The modelling indicates that the carbon dioxide plume saturation would be
seismically detectable and therefore time-lapse (i.e. 4D) seismic survey
techniques are applicable to monitoring of plume formation.
3.6.9 It is proposed that monitoring of the carbon dioxide plume will be undertaken
using three methods:
Swath seismic methods will be routinely deployed to monitor plume
migration and calibrate the reservoir model. Swath seismic acquisition
uses a relatively small number of sail lines of repeated 2D streamer
seismic over a limited area. Vessels are equipped with multiple
streamers and the data is subject to 3D seismic imaging algorithms to
reduce noise from out-of-plane reflections arising from geologically
dipping interfaces.
Full 3D seismic data acquisition will be undertaken once during the
injection phase, once during the post-closure period prior to transfer of
the site to the Competent Authority, and should unexpected carbon
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dioxide migration be observed in swath seismic data – swath bathymetry
data interpretation will be used to trigger such surveys.
Gravity surveying is being considered as a contingency method of plume
monitoring. A feasibility study of in-well and seabed gravity sensors
indicated the resulting data lacked the required resolution and that the
technology is not suitably mature for current deployment. Developments
in this technology will be monitored as it could be of potential use should
seismic techniques be precluded by future development.
3.7 DECOMMISSIONING OF THE OFFSHORE SCHEME
3.7.1 The project has an expected life of 40 years, following which it is anticipated
that the facilities will be decommissioned and the offshore storage site
monitored in accordance with the post-closure monitoring plan prepared
consistent with the provisions of the CCS Directive.
3.7.2 At the end of project life, which is expected to be 40 years, the NUI, drilling
template, pipeline and wells will be decommissioned consistent with regulator
guidance and Part IV of the Petroleum Act 1998 (as amended), and any
amendments or other prevailing legislation/guidance relevant at that time.
Under the current decommissioning regime, the NUI and drilling template would
need to be removed and returned to shore for reuse or disposal, and the
pipeline would need to be subject to a comparative assessment as to whether
all or part of the pipeline would need to be removed or could be left in situ.
3.7.3 The removal of the facilities and pipeline would be subject to options appraisal
and at the time of decommissioning, and therefore a meaningful assessment of
these cannot be made at this time, and they would be subject to EIA during
preparation and update of relevant decommissioning programmes/post-closure
plan for the facilities.
3.7.4 The wells would be abandoned following cessation of injection, and this would
require a mobile drilling rig. The impacts from this activity would be analogous
to any other drilling campaign during Phase 1 operations (e.g. any required well
workovers), and would not represent a significant increment to physical
disturbance as the rig would be sited in the same position as when the wells
were first drilled.
3.7.5 Whilst specific techniques will be developed and assessed at the time of
decommissioning and can be more properly assessed at the time of
decommissioning against more appropriate and relevant baseline conditions
mechanisms for effect will be similar to those assessed for the installation of
the Offshore Scheme.
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4.1 INTRODUCTION
4.1.1 This section sets out the baseline conditions for coastal processes, marine
mammals and seabirds in the vicinity of the Offshore Scheme. This baseline
relates to the interest features of the Natura 2000 Sites screened into the
integrity assessment. Please refer to Table 5.1 for a list of the sites and
associated interest features.
4.2 REVIEW OF COASTAL PROCESSES
4.2.1 The total quantity of available material to be transported as bedload by
longshore drift is estimated to be approximately 11% of that eroded from
Holderness annually (D’Olier 2002). Longshore drift rates along the
Holderness coast are estimated to vary from between 50,000m3/year and
250,000m3/year (Sutherland et al. 2002). At Barmston, tidal sand transport
was estimated to be negligible by Halcrow (1988), and the area to the north of
Barmston was estimated to have a drift rate in the region of 50,000m3/year.
The predominant longshore drift direction at Holderness is to the south,
however, a sediment parting zone may be present near Barmston, with net drift
to the north under moderate conditions (see HR Wallingford 2002, Halcrow
2002 as cited in Scott Wilson 2009).
4.2.2 Not all cross-shore sediment transport occurs in the intertidal zone as the
active beach profile extends further offshore to a “depth of closure”, which can
be defined as the seaward limit to significant cross-shore sediment transport
(Nicholls et al. 1998). Based on data collected from the Hornsea waverider
buoy for 2013, the depth of closure in the Bridlington Bay area is estimated1 to
be at the 7 m contour (see Figure 4.1), and therefore cross-shore sediment
transport takes place over a considerable area, though it should be noted that
during summer months when the installation is expected to take place, cross-
shore transport and sediment movement is likely to be more limited in extent.
Considering summer (July) wave conditions, the limiting depth for cross-shore
transport by waves can still be expected to occur to approximately 4.5 m depth
1 Based on:
, (after Hallermeier 1981) where He is “effective” wave height, being the
significant wave height exceeded only 12 hours per year, and Te is its associated wave period. g is equal to
acceleration due to gravity.
4 Baseline Conditions
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(effectively the wave base at this time) for medium to fine sand2. Wingfield &
Evans (1998) previously estimated that approximately half of the erosional
contribution from Holderness came from sediment movement within a strip
extending about 2 km from the coast, which is also consistent with a decline in
suspended sediment concentrations further offshore observed by Prandle et al.
(2000). While the calculated closure depth can be seen to be consistent with
this estimate to the south of the pipeline area, it extends further immediately
offshore and to the north of the pipeline, coinciding with the outer edge of the
Smithic Sands (see Figures 4.1 and 4.2 below), a shallow banner bank which
shoals to approximately 4m water depth. This feature is evident from survey
results along the nearshore section of pipeline, suggesting that an area of sand
overlies the boulder clay sediments out to approximately KP10.
4.2.3 Of material which is naturally eroded from Holderness, the coarser sand
fractions and gravel (~5-11% of material) comprise bed-load which is
transported south in the longshore direction, contributing to the surface veneer
of beach sediments, including ords (Sutherland et al. 2002, Balson & Philpott
2004) and the maintenance of Spurn Head. Ciavola (1997) indicates that 6%
of the Holderness longshore transport occurs along Spurn Head, and Valentin
(1971) estimated that ~3% of material eroded from the cliffs is accreted there.
The remaining approximate three quarters of bed-load material is moved
offshore to the south (e.g. to sinks such as The Binks, New Sand Hole, Humber
Estuary and Donna Nook – see D’Olier 2002). Cox (2002) also notes that,
through a study of mineralogical tracers, that the sand fraction of modern
estuary sediments of the Humber are composed predominantly of material
derived from the Holderness tills (98%) with a small fluvial source contribution
(2%). Moreover, Montreuil & Bullard (2012) suggest that up to 29% of the
material eroded from Holderness is temporarily deposited in the nearshore and
offshore environment prior to being redistributed by cross-shore currents
towards the Lincolnshire coast which are accreting.
4.2.4 In addition to the rates of longshore drift at the landfall, HR Wallingford (2002)
modelled the net tidal flux of sediment (including direction) which showed a
clockwise circulation of material around the Smithic Bank confirmed by the
asymmetry of megaripples on the flanks of the bank (D’Olier 2002). The
northwards moving residual tidal current during spring tides on the seaward
section of the Smithic Bank provides a means for sand translocation from
Bridlington Bay northwards past Flamborough Head into Filey Bay (Pethick
1994). Pethick notes that the volume of sediment moved is small, largely
2 Based on
, (after Hallermeier 1981) where Hs is the mean significant wave
height, Te is the mean significant wave period and D50 is the median grain size.
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balancing the removal of material from Filey Bay expected from a 50-year
storm event. Tidally driven movement northwards is probably due to the
influence of Flamborough Head which generates circulation in its lee during the
southwards flowing tide (Sutherland et al. 2002, HR Wallingford 2002).
Figure 4.1: Estimated Closure Depth and location of Smithic Sands
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Figure 4.2: Nearshore Bathymetry and average/storm surge transport
pathways (after HR Wallingford 2002)
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4.3 MARINE MAMMALS
4.3.1 The seal density maps for grey and harbour seals (Figures 4.3 and 4.4
respectively) indicate that defined areas of the southern North Sea may be
important for both species. Radiating out from Donna Nook in the Humber
Estuary, grey seals appear to use areas along the north Yorkshire coast, out to
the Dogger Bank area and from the Humber Estuary to an offshore area to the
east. Harbour seals use a more restricted area radiating out from the Wash.
4.3.2 Since 2008, a number of dead seals (>76 animals) displaying corkscrew
injuries (Bexton et al. 2012) have been found, primarily on beaches in eastern
Scotland, North Norfolk coast and Strangford Lough (Thompson et al. 2010).
The injuries are consistent with those that might be expected if the seals had
been drawn through a ducted propeller or some types of Azimuth thruster
(widely used in marine industry vessels), although there is presently no
definitive evidence to confirm this (SNCB 2012). Onoufriou & Thompson
(2014) reported on whether animal size, propeller speed and propeller type
affected the incidence of seal-propeller interactions. By passing scale models
of seals through different propulsion systems, they concluded that ducted
propulsion systems were the only mechanism which produced spiral
lacerations under the test conditions. Observations on candidate vessels are
vital to gain a better understanding of the circumstances under which these
interactions can occur in coastal regions (Onoufriou & Thompson 2014). The
hypothesis that seals are acoustically attracted to certain propellers is being
tested in the Sea Mammal Research Unit (SMRU) captive seal facility and in
the wild through behavioural sound playback studies. No clear responses were
observed in initial trials and additional trials were planned with both wild and
captive seals (SCOS 2013).
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Figure 4.3: Grey Seal total sea usage
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Figure 4.4: Harbour Seal at sea usage
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4.4 SEABIRDS
4.4.1 The southern North Sea including the area covered by the Offshore Scheme
supports important numbers of seabirds year round, including the kittiwake,
gannet, guillemot, razorbill and northern fulmar features of the Flamborough &
Filey Coast pSPA, in addition to passerine and other breeding seabirds (e.g.
Atlantic puffin) and migratory birds (e.g. swans, geese, ducks) en route to
estuarine or soft coastal habitats including the Humber Estuary, the Wash and
North Norfolk Coast. A series of seasonal (breeding and winter) seabird
density surface maps with a 6x6km grid were produced using modified
European Seabirds at Sea (ESAS) data, to complement work undertaken by
Kober et al. (2010) which sought to try and identify seabird aggregations within
the British Fishery Limit that might qualify as SPAs. “Hotspots” in the data were
tested against SPA selection criteria and a number of regions, primarily in
Scottish waters, were identified as being particularly important (Kober et al.
2010, 2012). Though the work did not result in the identification of further
important offshore seabird aggregations in English waters, and more
specifically in areas relevant to the Offshore Scheme, the density maps provide
an overview of possible seasonal seabird densities for a range of relevant
seabird species in the southern North Sea including those of relevance to the
Flamborough & Filey Coast pSPA (reproduced in Figure 4.5).
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Figure 4.5 – Seabird density surface maps using Poisson kriging (Kober et al.
2010)
Kittiwake
Northern Gannet
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Figure 4.5 – Seabird density surface maps using Poisson kriging (Kober et al.
2010)
Guillemot
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Figure 4.5 – Seabird density surface maps using Poisson kriging (Kober et al.
2010)
Razorbill
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Figure 4.5 – Seabird density surface maps using Poisson kriging (Kober et al.
2010)
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5.1 INTRODUCTION
5.1.1 This section screens the Offshore Scheme for the potential to result in a Likely
Significant Effect (LSE) on a Natura 2000 site.
5.2 SCREENING
5.2.1 Screening considers the sources, pathways, and receptors. The process
commences with the identification of possible sources or causes of effects
relating to the Offshore Scheme.
Sources of effect
5.2.2 The following sources of effect have been identified:
Installation of the pipeline (including excavation, trenching, backfilling and
pre-sweeping) potentially altering coastal processes.
Use of rock armouring and stabilisation materials, including at crossings.
Disturbance from the physical presence of pipeline and NUI installation
vessels.
Underwater noise from pipeline and NUI installation activities including
drilling.
Activities associated with the operation of the Offshore Scheme including
noise.
Receptors / Pathways
5.2.3 There are no Natura 2000 sites within the parameters of the Offshore Scheme.
Therefore the Offshore Scheme will not result in the direct loss, temporary or
permanent, of any habitat within the boundary of a Natura 2000 site.
5.2.4 A review of Natura 2000 sites in proximity of the Offshore Scheme has been
undertaken and those sites that meet the following criteria have been identified
as potential receptors:
Sites that are in proximity;
Sites that are up or down coast and could realistically be affected by any
change in coastal processes resulting from the Offshore Scheme; and
5 Screening (Stage 1)
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any sites that are designated for mobile interest features that could
potentially be disturbed by activities associated with the Offshore
Scheme.
5.2.5 Sites meeting these criteria are listed below, and site descriptions are presented
in Section 5:
Humber Estuary SAC
Humber Estuary SPA
Humber Estuary Ramsar
Flamborough Head and Bempton Cliffs SPA
Flamborough Head and Filey Coast pSPA
Flamborough Head SAC
The Wash and North Norfolk Coast SAC
Mechanism for effect
5.2.6 A mechanism is identified where there is a source of effect, a pathway
identified, and a receptor present which is sensitive to the potential effects.
The following table (Table 5.1) identifies the potential mechanisms resulting
from the Offshore Scheme and the site and the interest features that could be
affected.
Table 5.1: Potential effects of the Offshore Scheme on Natura 2000 sites.
Sources of
effect
Mechanism for
effect
Natura 2000
sites
Interest features screened in
Installation of
the pipeline
(including
excavation,
trenching,
backfilling
and pre-
sweeping)
potentially
altering
coastal
processes.
Installation of the
pipeline
potentially
resulting in an
increase or
decrease of the
down drift
sediment supply.
Humber
Estuary SAC
Estuaries
Mudflats and sandflats not
covered by seawater at
low tide
Sandbanks which are
slightly covered by sea
water all of the time
Coastal lagoons
Salicornia and other
annuals colonising mud
and sand
Atlantic salt meadows
(Glauco-Puccinellietalia
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Table 5.1: Potential effects of the Offshore Scheme on Natura 2000 sites.
Sources of
effect
Mechanism for
effect
Natura 2000
sites
Interest features screened in
maritimae)
Embryonic shifting dunes
Shifting dunes along the
shoreline with Ammophila
arenaria (‘white dunes’)
Fixed dunes with
herbaceous vegetation
(‘grey dunes’)
Dunes with Hippophae
rhamnoides
Associated effects on the Humber Estuary
SPA / Ramsar resulting from changes in
coastal processes.
Flamborough
Head SAC
Reefs
Vegetated sea cliffs of the
Atlantic and Baltic Coats
Submerged or partially
submerged sea caves
Use of rock
armouring
and
stabilisation
materials,
including at
crossings.
Use of rock
armouring
potentially
interfering with
coastal process
resulting in an
increase or
decrease of the
down drift
sediment supply.
Humber
Estuary SAC
Estuaries
Mudflats and sandflats not
covered by seawater at
low tide
Sandbanks which are
slightly covered by sea
water all of the time
Coastal lagoons
Salicornia and other
annuals colonising mud
and sand
Atlantic salt meadows
(Glauco-Puccinellietalia
maritimae)
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Table 5.1: Potential effects of the Offshore Scheme on Natura 2000 sites.
Sources of
effect
Mechanism for
effect
Natura 2000
sites
Interest features screened in
Embryonic shifting dunes
Shifting dunes along the
shoreline with Ammophila
arenaria (‘white dunes’)
Fixed dunes with
herbaceous vegetation
(‘grey dunes’)
Dunes with Hippophae
rhamnoides
Associated effects on the Humber Estuary
SPA / Ramsar resulting from changes in
coastal processes.
Flamborough
Head SAC
Reefs
Vegetated sea cliffs of the
Atlantic and Baltic Coats
Submerged or partially
submerged sea caves
Installation
vessels.
Disturbance from
the physical
presence of
pipeline and NUI
installation
vessels.
Humber
Estuary SAC
& Ramsar
Grey seal halichoerus
grypus
Ramsar Criterion2 Grey
seal halichoerus grypus
The Wash
and North
Norfolk Coast
SAC
Harbour seal phoca
vitulina
Flamborough
Head and
Bempton
Cliffs SPA
Kittiwake rissa tridactyla
Assemblage features
(puffin fratercula arctica,
razorbill alca torda,
guillemot uria aalge,
herring gull larcus
argentatus, northern
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Table 5.1: Potential effects of the Offshore Scheme on Natura 2000 sites.
Sources of
effect
Mechanism for
effect
Natura 2000
sites
Interest features screened in
gannet morus bassanus,
kittiwake rissa tridactyla)
Flamborough
Head and
Filey Coast
pSPA
Black-legged kittiwake
rissa tridactyla
Northern gannet morus
bassanus
Common guillemot uria
aalge
Razorbill alca torda
Assemblage features
(black-legged kittiwake,
northern gannet, common
guillemot, razorbill,
northern fulmar fulmarus
glacialis)
Underwater
noise from
pipeline and
NUI
installation
activities
including
drilling
Disturbance to
marine mammals
Humber
Estuary SAC
& Ramsar
Grey seal halichoerus
grypus
Ramsar Criterion2 Grey
seal halichoerus grypus
The Wash
and North
Norfolk Coast
SAC
Harbour seal phoca
vitulina
Operational
vessels and
activities
including
noise from
long-term
storage site
Disturbance from
vessels and
activities
associated with
the operation of
the Offshore
Scheme.
Humber
Estuary SAC
& Ramsar
Grey seal halichoerus
grypus
Ramsar Criterion2 Grey
seal halichoerus grypus
The Wash
and North
Norfolk Coast
SAC
Harbour seal phoca
vitulina
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Table 5.1: Potential effects of the Offshore Scheme on Natura 2000 sites.
Sources of
effect
Mechanism for
effect
Natura 2000
sites
Interest features screened in
monitoring. Flamborough
Head and
Bempton
Cliffs SPA
Kittiwake rissa tridactyla
Assemblage features
(puffin fratercula arctica,
razorbill alca torda,
guillemot uria aalge,
herring gull larcus
argentatus, northern
gannet morus bassanus,
kittiwake rissa tridactyla)
Flamborough
Head and
Filey Coast
pSPA
Black-legged kittiwake
rissa tridactyla
Northern gannet morus
bassanus
Common guillemot uria
aalge
Razorbill alca torda
Assemblage features
(black-legged kittiwake,
northern gannet, common
guillemot, razorbill,
northern fulmar fulmarus
glacialis)
5.2.7 Whilst the mechanisms identified in Table 5.1 are not certain, the precautionary
principle has been applied as the design for the Offshore Scheme has not yet
been finalised. Therefore likely significant effects of the Offshore Scheme
cannot be ruled out and all interest features screened in have been taken
through to the next stage (Stage 2) of the HRA process, testing for Adverse
Effect on Site Integrity (AEOSI).
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6.1 INTRODUCTION
6.1.1 The following sets out a description of the sites taken through to Stage 2 of the
HRA process. Please note that not all of the interest features are necessarily
considered in the assessment, as many were screened out at Stage 1 as there
was no mechanism for the Offshore Scheme to affect them,
6.2 HUMBER ESTUARY PROTECTED SITES
6.2.1 The Humber Estuary is located in the east of England and comprises extensive
wetland and coastal habitats. The estuary drains a catchment of some 24,240
square kilometres and provides the largest single input of freshwater from
Britain into the North Sea. It has the second-highest tidal range in Britain (7.2
m) and approximately one-third of the estuary is exposed as mud- or sand-flats
at low tide. The inner estuary supports extensive areas of reedbed with areas
of mature and developing saltmarsh backed by grazing marsh in the middle
and outer estuary. On the north Lincolnshire coast, the saltmarsh is backed by
low sand dunes with marshy slacks and brackish pools. The estuary supports
important numbers of waterbirds (especially geese, ducks and waders) during
the migration periods and in winter. It also supports important breeding
populations of terns and raptors in summer3.
Qualifying features and conservation objectives
6.2.2 Table 6.1 below sets out the Qualifying Species and Conservation Objectives
of the Humber Estuary SAC.
Table 6.1 Qualifying Species and Conservation Objectives of the Humber
Estuary SAC
Qualifying Features Conservation Objectives
Annex I habitats that are a primary
reason for selection of this site:
Estuaries
Mudflats and sandflats not covered
by seawater at low tide
Avoid the deterioration of the
qualifying natural habitats and
the habitats of qualifying
species, and the significant
disturbance of those qualifying
species, ensuring the integrity
of the site is maintained and
3 http://jncc.defra.gov.uk/default.aspx?page=1996
6 Site Descriptions
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Table 6.1 Qualifying Species and Conservation Objectives of the Humber
Estuary SAC
Qualifying Features Conservation Objectives
Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site:
Sandbanks which are slightly
covered by sea water all the time
Coastal lagoons * Priority feature
Salicornia and other annuals
colonising mud and sand
Atlantic salt meadows (Glauco-
Puccinellietalia maritimae)
Embryonic shifting dunes
Shifting dunes along the shoreline
with Ammophila arenaria (`white
dunes`)
Fixed dunes with herbaceous
vegetation (`grey dunes`) * Priority
feature
Dunes with Hippophae rhamnoides
Annex II species present as a qualifying feature, but not a primary reason for site selection
Sea lamprey Petromyzon marinus
River lamprey Lampetra fluviatilis
Grey seal Halichoerus grypus
the site makes a full
contribution to achieving
Favourable Conservation
Status of each of the qualifying
features.
Subject to natural change, to
maintain or restore:
The extent and distribution
of qualifying natural
habitats and habitats of
qualifying species;
The structure and function
(including typical species)
of qualifying natural
habitats and habitats of
qualifying species;
The supporting processes
on which qualifying natural
habitats and habitats of
qualifying species rely;
The populations of
qualifying species;
The distribution of
qualifying species within
the site.
6.2.3 Table 6.2 below sets out the Qualifying Species and Conservation Objectives
of the Humber Estuary SPA.
Table 6.2 Qualifying Species and Conservation Objectives of the Humber
Estuary SPA
Qualifying Features Conservation Objectives
Article 4.1 Qualification (79/409/EEC)
during the breeding season the area
regularly supports:
Avoid the deterioration of the
habitats of the qualifying
features, and the significant
disturbance of the qualifying
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Table 6.2 Qualifying Species and Conservation Objectives of the Humber
Estuary SPA
Qualifying Features Conservation Objectives
Great bittern Botaurus stellaris
Eurasian marsh harrier Circus
aeruginosus
Pied avocet Recurvirostra avosetta
Little tern Sterna albifrons
Over winter the area regularly
supports:
Great bittern Botaurus stellaris
Hen harrier Circus cyaneus
Bar-tailed godwit Limosa lapponica
European golden plover Pluvialis
apricaria
Pied avocet Recurvirostra avosetta
On passage the area regularly
supports:
Ruff Philomachus pugnax
Article 4.2 Qualification (79/409/EEC)
Over winter the area regularly
supports:
Dunlin Calidris alpina alpina
Red knot Calidris canutus
Black-tailed godwit Limosa limosa
islandica
Common shelduck Tadorna tadorna
Common redshank Tringa totanus
On passage the area regularly
supports:
Dunlin Calidris alpina alpina
Red knot Calidris canutus
Black-tailed godwit Limosa limosa
islandica
Common redshank Tringa totanus
features, ensuring the integrity
of the site is maintained and
the site makes a full
contribution to achieving the
aims of the Birds Directive.
Subject to natural change, to
maintain or restore:
The extent and distribution
of the habitats of the
qualifying features;
The structure and function
of the habitats of the
qualifying features;
The supporting processes
on which the habitats of
the qualifying features rely;
The populations of the
qualifying features;
The distribution of the
qualifying features within
the site.
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Table 6.2 Qualifying Species and Conservation Objectives of the Humber
Estuary SPA
Qualifying Features Conservation Objectives
Article 4.2 Qualification (79/409/EEC)
An Internationally Important
Assemblage of Birds
In the non-breeding season the area
regularly supports 153,934 waterfowl (5
year peak mean 1996/7 to 2000/1)
Including: Anas crecca, Anas penelope,
Anas platyrhynchos, Arenaria interpres,
Aythya ferina, Aythya marila, Botaurus
stellaris, Branta bernicla bernicla,
Bucephala clangula, Calidris alba,
Calidris alpina alpina,Calidris canutus,
Charadrius hiaticula, Haematopus
ostralegus, Limosa lapponica, Limosa
limosa islandica, Numenius arquata,
Numenius phaeopus, Philomachus
pugnax, Pluvialis apricaria, Pluvialis
squatarola, Recurvirostra avosetta,
Tadorna tadorna, Tringa nebularia,
Tringa totanus, Vanellus vanellus
6.2.4 Table 6.3 below sets out the Criterion for the Humber Estuary Ramsar.
Table 6.3: Humber Estuary Ramsar
Site Name Humber Estuary
6.2.5 Area (ha) 6.2.6 37,987.8
6.2.7 Criterion 1 6.2.8 The site contains a representative, rare, or unique example of
natural or near-natural wetland types found within the
appropriate biogeographic region:
6.2.9 The site is a representative example of a near-natural estuary
with the following component habitats: dune systems and
humid dune slacks, estuarine waters, intertidal mud and sand
flats, saltmarshes, and coastal brackish/saline lagoons.
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Table 6.3: Humber Estuary Ramsar
Site Name Humber Estuary
Criterion 2 6.2.10 The site supports populations of animal species important for
maintaining the biological diversity of a particular
biogeographic region:
The Humber Estuary Ramsar site supports a breeding colony
of grey seals Halichoerus grypus at Donna Nook. It is the
second largest grey seal colony in England and the furthest
south regular breeding site on the east coast. The dune
slacks at Saltfleetby-Theddlethorpe on the southern extremity
of the Ramsar site are the most north-easterly breeding site in
Great Britain of the natterjack toad Bufo calamita.
Criterion 5 The site regularly supports 20,000 or more waterbirds:
In the non-breeding season, the area regularly supports
153,934 individual waterbirds (5 year peak mean 1996/97 –
2000/01).
Criterion 6 The site regularly supports 1% of the individuals in a
population of one species or subspecies of waterbird in any
season:
Shelduck Tadorna tadorna – wintering
Golden plover Pluvialis apricaria - wintering
Knot Calidris canutus – wintering
Dunlin Calidris alpina – wintering
Black-tailed godwit Limosa limosa – wintering
Bar-tailed godwit Limosa lapponica – wintering
Redshank Tringa totanus – wintering
Golden plover Pluvialis apricaria - passage
Knot Calidris canutus – passage
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Table 6.3: Humber Estuary Ramsar
Site Name Humber Estuary
Dunlin Calidris alpina – passage
Black-tailed godwit Limosa limosa – passage
Redshank Tringa totanus - passage
6.3 FLAMBOROUGH HEAD AND BEMPTON CLIFFS SPA
6.3.1 Flamborough Head is located on the central Yorkshire coast of eastern
England. The cliffs project into the North Sea, rising to 135 m at Bempton Cliffs,
and exposing a wide section of chalk strata. The cliff-top vegetation comprises
maritime grassland vegetation growing alongside species more typical of chalk
grassland. The site supports large numbers of breeding seabirds including
Kittiwake Rissa tridactyla, as well as the only mainland-breeding colony of
Gannet Morus bassanus in the UK. The seabirds feed and raft in the waters
around the cliffs, outside the SPA, as well as feeding more distantly in the
North Sea. The intertidal chalk platforms are also used as roosting sites,
particularly at low water and notably by juvenile Kittiwakes4.
Qualifying Features and Conservation Objectives
6.3.2 Table 6.4 below sets out the Qualifying Species and Conservation Objectives
of Flamborough Head and Bempton Cliffs SPA.
Table 6.4 Qualifying Species and Conservation Objectives of
Flamborough Head and Bempton Cliffs SPA.
Qualifying Features Conservation Objectives
This site qualifies under Article 4.2 of
the Directive (79/409/EEC) by
supporting populations of European
importance of the following
migratory species: During the
breeding season:
Kittiwake Rissa tridactyla
A seabird assemblage of
international importance
Avoid the deterioration of the
habitats of the qualifying
features, and the significant
disturbance of the qualifying
features, ensuring the integrity of
the site is maintained and the site
makes a full contribution to
achieving the aims of the Birds
Directive.
Subject to natural change, to
4 http://jncc.defra.gov.uk/default.aspx?page=1995
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Table 6.4 Qualifying Species and Conservation Objectives of
Flamborough Head and Bempton Cliffs SPA.
Qualifying Features Conservation Objectives
The area qualifies under Article 4.2 of
the Directive (79/409/EEC) by regularly
supporting at least 20,000 seabirds.
During the breeding season, the area
regularly supports 305,784 individual
seabirds including: Puffin Fratercula
arctica, Razorbill Alca torda, Guillemot
Uria aalge, Herring Gull Larus
argentatus, Northern gannet Morus
bassanus, Kittiwake Rissa tridactyla.
maintain or restore:
The extent and distribution of
the habitats of the qualifying
features;
The structure and function of
the habitats of the qualifying
features;
The supporting processes on
which the habitats of the
qualifying features rely;
The populations of the
qualifying features;
The distribution of the
qualifying features within the
site.
6.4 FLAMBOROUGH HEAD AND FILEY COAST PSPA
6.4.1 Flamborough Head and Filey Coast pSPA is an extension of the existing
Flamborough Head and Bempton Cliffs SPA described above. Data recently
collected has revealed that the area covered by the SPA extension as well as
the existing SPA supports internationally important numbers of several
regularly occurring migratory bird species during the breeding season. As a
consequence the SPA extension is being recommended for classification as an
SPA. The pSPA is one of the most important sites for breeding sea birds in
England.
Qualifying Features and Conservation Objectives
6.4.2 Table 6.5 below sets out the Qualifying Species and Conservation Objectives.
Table 6.5 Qualifying Species and Conservation Objectives of
Flamborough Head and Filey Coast pSPA
Qualifying Features Conservation Objectives
This site qualifies under Article 4.2 of
the Directive (79/409/EEC) for
supporting over 1% of the
Avoid the deterioration of the
habitats of the qualifying
features, and the significant
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Table 6.5 Qualifying Species and Conservation Objectives of
Flamborough Head and Filey Coast pSPA
Qualifying Features Conservation Objectives
biogeogrpahical population of four
regulary occurring migratory
species:
Black-legged kittiwake Rissa
tridactyla
Northern gannet Morus bassanus
Common guillemot Uria aalge
Razorbill Alca torda
This site qualifies under Article 4.2 of
the Directive 2009/147/EC as it is used
by over 20,000 seabirds in any season:
during the breeding season, the area
regulary supports 215,750 individual
seabirds including: black-legged
kittiwake, northern gannet, common
guillemot, razorbill, northern fulmar
Fulmarus glacialis
disturbance of the qualifying
features, ensuring the integrity of
the site is maintained and the site
makes a full contribution to
achieving the aims of the Birds
Directive.
Subject to natural change, to
maintain or restore:
The extent and distribution of
the habitats of the qualifying
features;
The structure and function of
the habitats of the qualifying
features;
The supporting processes on
which the habitats of the
qualifying features rely;
The populations of the
qualifying features;
The distribution of the
qualifying features within the
site.
6.5 FLAMBOROUGH HEAD SAC
6.5.1 The site lies close to the boundary between two North Sea waterbodies and
encompasses a large area of hard and soft chalk cliffs which extend seaward
as bedrock, boulder and cobble reefs further than at other site in the UK.
6.5.2 The reefs at Flamborough are important due to their substrate type,
biogeographic position and the influences of hydrodynamic processes on reef
topography and community structure. The reefs and cliffs on the north side of
the headland are harder and more exposed than those of the south side of the
headland and as a result they support different ranges of species. The site
supports an unusual range of marine species, rich animal communities and
some species that are at the southern limit of their North Sea distribution, e.g.
the northern alga Ptilota plumosa. More than 110 species of seaweed and over
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270 species of invertebrates have been recorded on the rocky shores. In the
shallow waters the hard nature of the chalk have enabled kelp Laminaria
hyperborea forests to become established. These are important as they are
considered to be a key structural and functional component of the reefs at
Flamborough. In the deeper waters the reefs become dominated by faunal turfs
which are made up of sea mats and sponges, soft corals and sea fans.
6.5.3 The site contains caves cut into soft rock exposures and is important for its
specialised cave- algal communities, which contain abundant Hildenbrandia
rubra, Pseudendoclonium submarinum, Sphacelaria nana and Waerniella
lucifuga. There are more than 200 caves within the site. Some are partially
submerged at all stages of the tide, others dry out at low tide, and some lie
above the high water mark but are heavily influenced by wave splash and salt
spray. The largest extend for more than 50 m from their entrance.
6.5.4 The vegetated sea cliffs are characterised by both a maritime influence, and by
the chalk underlying the boulder clay. Thrift Armeria maritima and sea plantain
Plantago maritima grow alongside herbaceous species more typical of chalk
grassland such as kidney vetch Anthyllis vulneraria. Where the undercliff has
slipped and is flushed by calcareous runoff, northern marsh orchid Dactylorhiza
purpurella may be found with saltmarsh species, including sea arrowgrass
Triglochin palustris and sea-milkwort Glaux maritima. Towards the northern and
southern end of the site the chalk is masked by drift deposits, which support
mesotrophic and acidic grassland communities.
Qualifying Features and Conservation Objectives
6.5.5 Table 6.6 below sets out the Qualifying Species and Conservation Objectives.
Table 6.6 Qualifying Species and Conservation Objectives of
Flamborough Head SAC
Qualifying Features Conservation Objectives
Annex I habitats that are a primary
reason for selection of this site:
Reefs
Vegetated sea cliffs of the Atlantic and
Baltic coasts
Submerged or partially submerged sea
caves
Ensure that the integrity of the
site is maintained or restored as
appropriate, and ensure that the
site contributes to achieving the
Favourable Conservation Status
of its Qualifying Features, by
maintaining or restoring;
The extent and distribution of
qualifying natural habitats
The structure and function
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Table 6.6 Qualifying Species and Conservation Objectives of
Flamborough Head SAC
Qualifying Features Conservation Objectives
(including typical species) of
qualifying natural habitats,
and
The supporting processes on
which qualifying natural
habitats rely
6.6 THE WASH AND NORTH NORFOLK COAST SAC
6.6.1 The Wash is the largest embayment in the UK. It is connected via sediment
transfer systems to the north Norfolk coast. Together, the Wash and North
Norfolk Coast form one of the most important marine areas in the UK and
European North Sea coast, and include extensive areas of varying, but
predominantly sandy, sediments subject to a range of conditions. Communities
in the intertidal include those characterised by large numbers of polychaetes,
bivalve and crustaceans. Subtidal communities cover a diverse range from the
shallow to the deeper parts of the embayments and include dense brittlestar
beds and areas of an abundant reef-building worm (‘ross worm’) Sabellaria
spinulosa. The embayment supports a variety of mobile species, including a
range of fish, otter Lutra lutra and common seal Phoca vitulina. The extensive
intertidal flats provide ideal conditions for common seal breeding and hauling-
out.
6.6.2 Sandy sediments occupy most of the subtidal area, resulting in one of the
largest expanses of subtidal sandbanks in the UK. The subtidal sandbanks vary
in composition and include coarse sand through to mixed sediment at the
mouth of the embayment. Communities present include large dense beds of
brittlestars Ophiothrix fragilis. Species include the sand-mason worm Lanice
conchilega and the tellin Angulus tenuis. Benthic communities on sandflats in
the deeper, central part of the Wash are particularly diverse. The subtidal
sandbanks provide important nursery grounds for young commercial fish
species, including plaice Pleuronectes platessa, cod Gadus morhua and sole
Solea solea.
6.6.3 The site contains the largest single area of saltmarsh in the UK and is one of
the few areas in the UK where saltmarshes are generally accreting. The
proportion of the total saltmarsh vegetation represented by glasswort Salicornia
and other colonising annuals is high because of the extensive enclosure of
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marsh in this site and is also unusual in that it forms a pioneer community with
common cord-grass Spartina anglica. There are large ungrazed saltmarshes on
the North Norfolk Coast and traditionally grazed saltmarshes around the Wash.
Saltmarsh swards dominated by sea-lavenders Limonium spp. are particularly
well-represented. In North Norfolk, in addition to typical lower and middle
saltmarsh communities, there are transitions from upper marsh to tidal
reedswamp, sand dunes (which are largely within the adjacent North Norfolk
Coast SAC), shingle beaches and mud/sandflats. Mediterranean saltmarsh
scrub vegetation is dominated by a shrubby cover up to 1 metre high of bushes
of shrubby sea-blite Suaeda vera and sea-purslane Atriplex portulacoides, with
a patchy cover of herbaceous plants and bryophytes. This scrub vegetation
often forms an important feature of the upper saltmarshes, and extensive
examples occur where the drift-line slopes gradually and provides a transition
to dune, shingle or reclaimed sections of the coast. At a number of locations on
this coast perennial glasswort Sarcocornia perennis forms an open mosaic with
other species at the lower limit of the sea-purslane community.
Qualifying Features and Conservation Objectives
6.6.4 Table 6.7 below sets out the Qualifying Species and Conservation Objectives.
Table 6.7 Qualifying Species and Conservation Objectives of the Wash
and North Norfolk Coast SAC
Qualifying Features Conservation Objectives
Annex I habitats that are a primary
reason for selection of this site:
Sandbanks which are slightly covered
by sea water all the time; Subtidal
sandbanks
Mudflats and sandflats not covered by
seawater at low tide; Intertidal mudflats
and sandflats
Coastal lagoons
Large shallow inlets and bays
Reefs
Salicornia and other annuals colonising
mud and sand; Glasswort and other
annuals colonising mud and sand
Atlantic salt meadows (Glauco-
Ensure that the integrity of the
site is maintained or restored as
appropriate, and ensure that the
site contributes to achieving the
Favourable Conservation Status
of its Qualifying Features, by
maintaining or restoring;
The extent and distribution of
qualifying natural habitats
and habitats of qualifying
species
The structure and function
(including typical species) of
qualifying natural habitats
The structure and function of
the habitats of qualifying
species
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Table 6.7 Qualifying Species and Conservation Objectives of the Wash
and North Norfolk Coast SAC
Qualifying Features Conservation Objectives
Puccinellietalia maritimae)
Mediterranean and thermo-Atlantic
halophilous scrubs (Sarcocornetea
fruticosi); Mediterranean saltmarsh
scrub
Annex II species present as a qualifying feature, but not a primary reason for site selection
Otter Lutra lutra
Common seal Phoca vitulina
The supporting processes on
which qualifying natural
habitats and the habitats of
qualifying species rely
The populations of qualifying
species, and,
The distribution of qualifying
species within the site.
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7.1 INTRODUCTION
7.1.1 The following mechanisms for effect have been identified
Installation of the pipeline potentially resulting in an increase or decrease
of down drift sediment supply.
Use of rock armouring potentially interfering with coastal processes
resulting in an increase or decrease in down drift sediment supply.
Disturbance from the physical presence of pipeline and NUI installation
vessels.
Disturbance from underwater noise
Disturbance from activities associated with the operation of the Offshore
Scheme.
7.1.2 The following sections provide analysis of the mechanisms for effect and
Tables 7.2 to 7.6 provide an assessment as to the potential for the Offshore
Scheme to result in an adverse effect on site integrity.
7.2 INSTALLATION OF THE PIPELINE
Nearshore Pipeline
7.2.1 The majority of cross-shore sediment transport takes place within the nearhore
pipeline from KP0 to KP16 as the active beach profile extends to the “depth of
closure” which in Bridlington Bay is estimated5 to be at the 7 m contour, please
refer to Section 4.2.
7.2.2 Analysis of Particle Size Distribution (PSD) patterns from grab samples
collected during the entire proposed pipeline route survey indicates that the
dominant textural groups are gravelly sand, to sand with muddy sandy gravel
present in some nearshore samples (Folk RL 1954). Geotechnical cores reveal
that the material to be excavated during trenching would be a combination of
such surficial sands and underlying boulder clay, the latter being part of the
Bolders Bank Formation, the offshore extension of the tills found to comprise
much of the cliffs and beach of Holderness. 5 Based on:
, (after Hallermeier 1981) where He is “effective” wave height, being the
significant wave height exceeded only 12 hours per year, and Te is its associated wave period. g is equal to
acceleration due to gravity.
7 Potential for Adverse Effect on Site
Integrity (Stage 2)
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7.2.3 In the nearshore area the likely depth of the surficial sediment (sand) cover
over the length of the trench is thin, and nearshore survey results indicate that
the underlying boulder clay is often exposed from the shore out to
approximately 8-9 km where there is a layer of sand up to approximately 8 m
thick. Further offshore from this point, the seabed surface has numerous
boulders and surface undulations interpreted to reflect sub-cropping or
outcropping boulder clay to 15 km offshore, confirmed through the collection of
clay material from surface grab samples the majority of excavated material is
likely to be of this sediment type.
7.2.4 Nearshore trenching operations will be controlled to avoid large variations in
trench depth, and excavated material will be sidecast. Trenched material will
be a combination of surficial sands and underlying boulder clay, though this is
likely to be predominantly sand within the nearshore area between KP1.9 and
9.7. Any boulder clay is likely to be cohesive and persistent and therefore not
be readily eroded, however a temporary increase in suspended sediment
concentrations is likely. Considering the closure depth, please refer to Section
4.2 both wave and tidal current interaction with the trench and sidecast material
will occur over much of the nearshore area, with shallow (<10m) water depths
extending ~9km offshore (see Figure 4.2).
7.2.5 Enhanced suspended sediment concentrations may be comparable to that of a
winter storm event, with the release of fine sediment (i.e. below 63µm) from the
excavated boulder clay likely to settle out over an extended period – for
instance Blewett & Huntley (1999) indicated a settling velocity in the range 1.8-
2.8 x 10-4 ms-1 for sediment re-suspended by storms in this area. Due to the
low settling velocities, wave and tidal currents will interact with such fine
sediments which will be carried away from the immediate location of the works
towards local and regional sinks including the Humber and Wash. In the area
of sand between KP1.9 and 9.7, any sediment released will settle more rapidly
(a settling velocity of between 0.01-0.04 ms-1 may be assumed6) and local
deposition can be expected.
7.2.6 The material excavated from the trench will be backfilled on top of the pipeline
to the former seabed level. Previous studies undertaken for similar pipeline
installations at Easington (e.g. Langeled, York) approximately 45 km to the
south of Barmston have suggested a conservative 10% loss of sediment
excavated and sidecast during pipeline installation. This would equate to a loss
of 64,923m3 of sediments for the total excavated area including the access
channel, please refer to Table 3.1. In the context of erosional losses from
Holderness (~3 million m3 per year) and the wider sediment flux in this area,
6 Based on D50 sediment sizes collected from grab samples for this area (after Soulsby 1998).
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this volume is considered to represent only a small addition to annual sediment
loads.
7.2.7 The nearshore pipeline will be buried and will therefore not interfere with the
sediment supply along the Holderness Coast in the long term.
Offshore Pipeline
7.2.8 Following installation, the surface laid section of pipeline will interact with wave
and tidal generated currents and bedload transport taking place in the offshore
area, which is evidenced by the large number of mobile bedforms between
KP47 and the platform location. The surface laid pipeline will be placed largely
perpendicular to the dominant current and wave directions (and associated
sediment transport directions) in the area (HR Wallingford 2002, see Figure
4.2, above). The installation of a surface laid pipeline on the seabed will cause
local changes to the bed shear stress which can enhance the likelihood of
scour taking place (Whitehouse 1998), and therefore pipeline freespans, which
can be a navigational hazard and pipeline integrity hazard. Freespans are
known to occur on some southern North Sea pipelines, mainly associated with
shallow water depths and higher bed shear stresses, and can be transient
features developing and disappearing over 2-3 years (Metoc 2004). Freespans
are initially generated by “piping”, a process where pressure differences at
either side of the pipeline cause the onset of scour such that “seepage flow” of
non-cohesive sediment and eventually both sediment and water break through
beneath the pipe (Sumer & Fredsøe 1993), which can be accentuated where
sediment supply is limited (Zhang et al. 2013). This can progress to “tunnel
erosion”, which develops rapidly with an initial fourfold amplification in bed
shear stress below the pipeline (the square of enhanced flow speed due to the
obstruction, taken as a factor of 2 for a pipeline), and the development of a
scour pit (Sumer & Fredsøe 1991, 1993 as cited in Whitehouse 1998). The
onset of scour and freespanning in the field typically occur where the pipeline
has been laid on an area of seabed which is not completely flat, for instance
due to local changes in bedform generated in soft sediment (e.g. sandwaves)
or hard ground conditions, and possibly also local changes in pipeline diameter
and roughness associated with field joints (Draper et al. 2015).
7.2.9 Freespans are most likely to occur in areas of sandwaves which are present
along the pipeline route in the offshore section from approximately KP47 to the
platform location, with crest heights of up to 7 m above the seabed. Historic
freespan and subsea protection data has been reviewed to understand the size
and location of reported spans in relation to the proposed pipeline route (see
Figure 7.1). The presence of these is mainly in the area of the North Norfolk
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sandbanks which also corresponds to an area of high tidal power and bed
shear stress, with only isolated spans occurring elsewhere.
Figure 7.1 – Southern North Sea pipelines, freespans and subsea
protection in relation to seabed energy levels and bathymetry
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7.2.10 Pre-sweeping has been undertaken for other southern North Sea surface laid
and trenched pipelines including for the York (RPS 2011), Langeled (Metoc
2004) and Tors (ATP Oil & Gas 2005) developments. Little information is
available on the recovery and sandwaves following pre-sweeping activity
(though this has been common practice in other southern North Sea
developments including York, Langeled, Tors). A study undertaken on the pre-
sweeping and trenching of two flowlines in the Dutch sector of the southern
North Sea revealed that megaripples had reformed within 5 months of work
being completed (Small & Baan 2012), with larger sandwaves expected to have
a recovery time in the order of four years (Van den Berg 2007, cited in Small &
Baan 2012). The sandwaves within the area of the Offshore Scheme are
considered mobile and thus likely to show similar recovery rates to those
shown by Small & Baan (2012).
Anchor Mounds
7.2.11 An anchored lay barge, if used, will result in the generation of anchor mounds
and possibly also interaction with the seabed with anchor chains through
catenary action. The nature of these mounds is dependent on local geological
conditions, which range from shallow subcropping boulder clay from the landfall
to KP2.27 and from KP9.69 to the end of the inshore pipeline section at KP15,
and sand between KP1.89 and 9.69. Sand mounds or anchor cable scarring of
surficial sediments are likely to be readily reworked by wave and tidal influence
in this area. However, any mounds of boulder clay are likely to be more
persistent.
7.2.12 The effects of lay barge anchors are similar for the offshore section of pipeline
as those described for the nearshore section, if this type of vessel is used.
Boulder clay continues to subcrop at the seabed beyond KP15 out to KP30,
and further offshore there is more subcropping chalk to KP47 interspersed with
boulder clay. The seabed is sand to the proposed platform location with
sandwaves and sand ridges. Analogous to the inshore section, those anchor
scars in surficial sands are likely to be readily reworked by currents and, to a
lesser extent, wave action, with any clay mounds likely to persist for longer.
Rock Cover
7.2.13 A summary of the proposed rock cover requirements is set out in Table 7.1. For
the nearshore pipeline it is estimated that a maximum of 6000 m3 of rock will
be required, however this will be buried below bed level. The export cables
and pipeline crossings will require rock cover with a minimum cover height of
1.5 m which will be above the bed surface. The two export cable crossings will
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be on the nearshore pipeline between KP8 and KP17 and the Langeled
pipeline crossing on the surface laid section at KP38.
Table 7.1: Summary of Rock Cover Requirments
Nearshore Offshore Crossings NUI
Rock
Cover
6000m3
(below bed
level)
None proposed,
however
remedial rock
placement may
be required
should
freespans occur
and exceed
0.5m this will be
assessed
through routine
surveys.
3200m3
(1600m3 per
crossing) for the
Dogger Bank
Creyke Beck
export cables.
1350m3 for the
Langeled
pipeline
crossing.
600 tonnes
7.3 DISTURBANCE FROM INSTALLATION & VESSELS
Marine Mammals
7.3.1 Sections of the pipeline route and storage area are located within or close to
areas of low to moderate (grey seal only) seal usage. The presence and/or
movement of vessels within the pipeline and storage area could potentially
disturb foraging marine mammals in this area. However, the Offshore Scheme
is remote from relevant haulout sites and only low numbers of marine mammals
are likely to be present over the area of the scheme at any one time.
7.3.2 Interim advice by the statutory nature conservation bodies (SNCB) sets out
recommendations for regulators and industry with regards to understanding
and minimising the risk of corkscrew injury to seals (SNCB 2012). For high risk
areas (defined as within 4nm of a harbour seal SAC and areas where the
harbour seal population is in significant decline), current SNCB advice is to
consider alternatives to using ducted propellers or avoid the breeding season
(1st June-31st August). If these measures are not possible then a Seal
Corkscrew Injury Monitoring Scheme should be considered. Guidance for
medium risk areas (activity proposed to take place between 4 and 30 nautical
miles of a harbour seal SAC or within 4 nautical miles of a grey seal SAC) is
similar with the grey seal breeding season identified as 1st October-31st
December. Activities proposed to take place beyond 30 nm from a harbour
seal SAC and 4 nm from a grey seal SAC are regarded as having a low risk
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and no mitigation measures are proposed. The SNCB advice will be reviewed
as understanding of the issue improves.
7.3.3 No aspect of the Offshore Scheme (pipeline or NUI) corresponds with high or
medium risk areas as identified above, being at least 30 nm and 56 nm from
the Humber Estuary SAC (grey seal) and Wash and North Norfolk Coast SAC
(harbour seal) respectively, and therefore it is not proposed to prepare a Seal
Corkscrew Injury Monitoring Scheme, and there are considered to be a low risk
of mortality due to the presence of construction vessels.
Seabirds
7.3.4 The presence and/or movement of vessels during pipelay and NUI installation
activities could potentially disturb seabirds foraging from Flamborough Head
during the breeding season and into the post-breeding season as activities are
proposed to take place in the summer months. Behaviours such as preening,
bathing and displaying, tend to occur in close proximity to colonies, being the
basis for 1-2 km seaward extensions to UK SPAs (McSorley et al. 2003, 2006),
including for the Flamborough Head and Bempton Cliffs SPA. Interactions with
such activities from installation vessels are not considered likely due to the
distance between installation activities and the boundary extension
encapsulating the Flamborough & Filey Coast pSPA (approximately 4 km from
the nearshore pipeline).
7.3.5 The foraging ranges of the designated features of the Flambrough Head and
Bempton Cliffs SPA and the Flamborough & Filey Coast pSPA (after Thaxter et
al. 2012) suggest the potential feeding area available is large for some species,
e.g. guillemot (mean 37.8 km ± 32.3), gannet (mean 92.5 km ± 59.9) and
fulmar (mean 47.5 km – a component of the breeding seabird assemblage) and
that this flexibility may limit their sensitivity to the proposed installation activities
(e.g. see Garthe & Hüppop 2004), particularly due to the transient nature of the
installation. These ranges also indicate that there is the potential for interaction
with these species some distance from seabird colonies and potentially out to
as far as the storage site if mean maximum foraging ranges are considered
(also see Figure 4.5), though fewer individuals are likely to be present further
offshore in the breeding season. Kittiwake (mean 24.8 km ± 12.1), and razorbill
(mean 23.7 km ± 7.5) may be more sensitive due to a smaller foraging area,
and also to specific prey requirements (e.g. sandeel, see Furness & Tasker
2000), spawning and nursery grounds, which coincide with the offshore section
of the pipeline route.
7.3.6 Puffins are also recorded at Flamborough Head as an interest feature of the
existing SPA (mean foraging range 30 km) and their sensitivity may be
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considered similar to that of razorbill. Puffins disperse widely from colonies
from July to August, but the timing of their moult may occur between
September and March (with peaks in October and March), during which time
they are flightless (Harris et al. 2014). Given the timing of this moult, and that
puffins generally disperse and overwinter outside of inshore waters (e.g. see
Harris et al. 2010), interactions with flightless birds from installation activities
are not regarded to be a likely source of effect for this species. Razorbill and
guillemot disperse from their colonies in July to August, and are flightless
during this period. Though disturbance of individual birds may occur along the
pipeline route and at the storage area at this time, in the context of the wider
pSPA populations of these birds (razorbill: 21,140 breeding adults, guillemot
83,214 breeding adults – count period 2008-2011) and the localised and
transient nature of the construction activities, population level effects are not
considered to be likely.
7.3.7 The species discussed above have been judged to have a low to moderate
sensitivity to disturbance by shipping traffic (Garthe & Hüppop 2004). Pipeline
installation activities are expected to be comparable to shipping in terms of
magnitude for bird disturbance effects due to physical presence, and
disturbance effects for alcids from shipping tends to be in the range of
hundreds of metres, unlike divers which show avoidance behaviour at more
than 1 km (Furness et al. 2013) and shy species such as common scoter which
have shown flight responses in large flocks at 2 km from a 35 m vessel, or 1 km
for smaller flocks, with likely greater disturbance effects from larger vessels
(Kaiser et al. 2006) – no SPAs designated for such sensitive species are
located within those distances which could give rise to disturbance behaviour,
or are considered relevant to this assessment. Any disturbance to alcids,
including those from the Flamborough & Filey Coast pSPA can therefore be
expected to take place within several hundred metres of the installation vessels
and are unlikely to generate bird mortality or affect the bird colonies at the
population level.
7.3.8 The potential effects on seabirds of sediment plumes in relation to aggregates
extraction reported in Cook & Burton (2010) – primarily relating to prey
disturbance – are not expected as sediment will be sidecast from the trench at
the seabed rather than being collected and returned to the seabed (e.g. as in
the case trailing suction hopper dredgers). The sidecast material from the
trench and direct effects from the trenching will cover a relatively small area of
seabed, and effects (e.g. smothering) on benthic ecology related to seabird
prey are also likely to be limited in scale and magnitude. Any plume associated
with the access channel and nearshore trench will be minimised through
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efficient vessel use, is likely to be short lived, and would tend to be carried to
the south and offshore under average sediment transport conditions.
7.4 DISTURBANCE FROM UNDERWATER NOISE DURING INSTALLATION
7.4.1 The sources, measurement, propagation, ecological effects and potential
mitigation of underwater noise have been extensively reviewed and assessed
(Richardson et al. 1995, McCauley et al. 2000, DTI 2004, MMS 2004, Weilgert
2007). Nowacek et al. (2007) provide a systematic update of quantitative
studies of cetacean responses to anthropogenic noise, published since
Richardson et al. (1995). In general, assessments of acoustic disturbance have
involved:
quantification of source noise levels (as Source Level, SL) estimation of
threshold noise levels for various categories of effect (ranging from acute
trauma to behavioural responses) estimation of likely horizontal range of
noise propagation to specified threshold level;
assessment of population density and sensitivity of marine mammals and
other receptors within affected areas; and
Using this approach, concentric “zones of effect” may be identified,
corresponding to increasing sound pressures and severity of effect.
7.4.2 A general distinction may be drawn – in terms of propagation and mechanisms
of effect – between sources of noise and vibration which are continuous
(“chronic”), such as machinery noise and propeller cavitation; and transient or
impulse sources such as seismic airguns and pile driving. These distinctions
are also significant in terms of defining source levels (Madsen 2005). The
various sources of significant noise associated with the Offshore Scheme are
described and considered below.
Pipeline Installation
7.4.3 A review by Hannay et al. (2004) of pipelay noise indicted that anchored lay
barges produced lower sound levels than their associated vessels used for
anchor handling due to their use of thrusters, in each case noise was produced
with source levels of between 180-190 dB re 1μPa in the frequency range 10-
1,000Hz.
7.4.4 For trenching and pre-sweeping operations, noise sources may be equivalent
to those for marine dredging (DECC 2011), though slow operating speeds can
negate noise effects from propeller cavitation. Robinson et al. (2011) found
that on transit dredging vessels were no different to other shipping activities
(broadband source levels of 170-180 dB re 1 μPa for cutter and suction hopper
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dredgers), but that during dredging operations when the draghead was
lowered, there is the potential for a high level of broadband noise to be radiated
in the frequency range 1 kHz to high tens of kilohertz, though these are likely to
have a shorter range of effect than lower frequency sounds.
7.4.5 Measurements made by Nedwell & Edwards (2004) from a fall pipe vessel
indicated that there was no discernible difference between normal vessel
operating conditions and those during rock placement, suggesting that noise
levels from this activity were dominated by vessel propellers and thrusters
rather than the rock placement.
7.4.6 The above noise is generally equivalent to that generated by large merchant
vessels (e.g. McCauley 1994), and would be a temporary incremental source of
noise in an area already subject to low (nearshore) to moderate and high
(offshore) shipping density.
Drilling activities
7.4.7 Available measurements indicate that drilling activities produce mainly low-
frequency continuous noise from several separate sources on the drilling unit
(Richardson et al. 1995, Lawson et al. 2001). The primary sources of noise are
various types of rotating machinery, with noise transmitted from a semi-
submersible rig to the water column through submerged parts of the drilling unit
legs and risers, and (to a much smaller extent) across the air-water interface.
7.4.8 Sound pressure levels of between 120 dB re 1 μPa in the frequency range 2-
1,400 Hz (Todd & White 2012) and 170 dB re 1 μPa in the frequency range 10-
2,000 Hz (Davis et al. 1991) are probably typical of drilling from jack-up and
semi-submersible rigs respectively, and is of the same order and dominant
frequency range as that from large merchant vessels (e.g. McCauley 1994). It
is reasonable to expect drilling noise associated with the injection wells to be
comparable in source characteristics. Drilling noise has also been monitored
west of Shetland, in the vicinity of the Foinaven and Schiehallion developments
(Swift & Thompson 2000). High and variable levels of noise in three noise
bands (1-10 Hz, 10-30 Hz and 30-10 0Hz) were initially believed to result from
drilling related activity on two semi-submersible rigs operating in the area.
However, subsequent analysis showed that noise events and drilling activity did
not coincide. In contrast, a direct correlation between the use of thrusters and
anchor handlers, during rig moves, and high levels of noise in all three bands
was found (Swift & Thompson 2000).
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7.4.9 As the above noise would be a temporary incremental source of noise there is
limited potential for interactions with individual harbour and grey seals at the
storage site.
NUI Installation
7.4.10 The NUI jacket will be fixed to the seabed with six 55 m long piles, 1,829 mm in
diameter (two at the base of each leg at the drilling side of the jacket, and one
at each leg on the other side). The piles will be driven into the seabed using
either a hydraulic hammer, or installed using a drill and grout piling technique if
hard ground conditions are encountered (e.g. chalk). FEED studies to confirm
which piling technique is likely have not been completed therefore the
assessment is based on hydraulic hammer pile driving since this will generate
the loudest sounds. The piles would be driven into the seabed using a
hydraulic hydro hammer with an estimated weight of ca. 20 tonnes, and all are
expected to penetrate the seabed to the entire length of the pile. Percussive
piling operations would be expected to have a total duration of around 4.5 days
with piling occurring for some 96 hours over that period; all piling operations
would incorporate a “soft start” procedure.
7.4.11 Source level and frequency content are related to pile diameter and soil
characteristics, both of which are key influences over the impact energy
required to drive the pile (Rodkin & Reyff 2004, cited in Madsen et al. 2006).
Based on a best-fit model, the relationship between the diameter (D) of a
hollow pile and the source level from its piling has been approximately
described as: SL = 24.3D + 179 dB re 1 μPa @ 1m (Nedwell et al. 2005, cited
in Bailey et al. 2010). Using the relationship (where D = diameter of pile), the
source level associated with piling operations is 222.7 dB re 1μPa @ 1 m (p-p)
for 1.8 m diameter piles. The frequency profile for piling noise generally shows
a fairly shallow gradient, with maximum pressure levels observed between
approximately 200-1,000 Hz (Nedwell et al. 2007).
7.4.12 As with underwater noise source characterisation, quantitative aspects of noise
propagation are complex (see review by Richardson et al. 1995). A simplified
assessment can be made by assuming that in deep water, sound pressure will
propagate spherically, with received Sound Pressure Level, SPL = SL –
20log(R), where SL = source level (dB), R = source-receiver range (m). For
piling, a transmission loss (TL) of -20log(R) is representative of those observed
in the studies cited above.
7.4.13 Additional signal attenuation may result from a combination of reflection from
sub-surface geological boundaries, sub-surface transmission loss due to
frictional dissipation and heat; and scattering within the water column and sub-
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surface due to reflection, refraction and diffraction in the propagating medium.
The precise rate at which loss will occur is variable, depending upon such
factors as frequency spectrum and seabed type. Long-range absorption losses
are particularly frequency-dependent and have been empirically described
(Jensen et al. 1994) by an absorption coefficient α (dB/km).
7.4.14 Using – 20 log(R) transmission losses, the extent of predicted sound pressure
level propagation contours from piling at the NUI location are 160 dB re 1 µPa
at 1.5 km, 150 dB re 1 µPa at 4.5 km, and 140 dB re 1 µPa at 19.9 km.
7.4.15 In a comprehensive and widely accepted assessment, Southall et al. (2007)
proposed injury criteria composed both of unweighted peak sound pressure
levels (maximum absolute value of the instantaneous sound pressure) and M-
weighted sound exposure levels (an expression for the total energy of a sound
wave). The M-weighted function also takes the known or derived species-
specific audiogram into account. For three functional hearing categories of
cetaceans, proposed injury criteria are an unweighted Sound Pressure Level of
230 dB re 1 μPa (peak) for all types of sounds and an M-weighted sound
exposure level of 198 or 215 dB re 1 μPa2 s for pulsed and non-pulsed sounds
respectively. For pinnipeds the respective criteria are 218 dB 1 μPa (peak)
and 186 (multiple pulse) or 203 (non-pulse) re 1 μPa2 s (M-weighted). The
threshold to be used (SPL or SEL), is the first one to be exceeded. These
proposals are based on the level at which onset of permanent hearing loss
(parameterised as Permanent Threshold Shift, PTS) is estimated to occur by
extrapolating from available data for Temporary Threshold Shift (TTS).
7.4.16 Southall et al. (2007) recommended caution when applying the injury threshold
to harbour porpoises because a preliminary study had provided evidence to
suggest that this species is more sensitive to sound that those previously
tested. Further studies (e.g. Lucke et al. 2009, Kastelein et al. 2014) have
corroborated the result. Applying the procedure of Southall et al. (2007), it is
possible to extrapolate from results obtained by Lucke et al. (2009) and
estimate PTS onset for harbour porpoises at thresholds of SPL 200 dB re:
1μPa (peak) and SEL 179 dB re:1 μPa2s as calculated by Lepper et al. (2014).
7.4.17 In relation to the criteria proposed by Southall et al. (2007), injury criteria, if
exceeded at all, will be within very close proximity to the source and therefore
normal mitigation measures (as per JNCC guidelines) will be effective. The
odontocete behavioural lower threshold of 150 SPL (dB) occurs at 9,400 m
from the piling whilst the upper threshold for odontocete behavioural of 170
SPL (dB) occurs at <500 m.
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7.4.18 The storage site and survey area lies within the SCANS-II survey block ‘U’
(southern North Sea; SCANS, 2008). Density estimates for cetacean species
in this block are for harbour porpoise (0.562 animals per km2), white-beaked
dolphin (0.003 animals per km2), Lagenorhynchus spp. (0.003 animals per
km2), common dolphin (0.056 animals per km2) and minke whale (0.022
animals per km2). Consequently the number of any cetacean species
potentially present within the area where SPLs are above the upper and lower
behavioural thresholds are low, and would not lead to population level
consequences.
7.4.19 The storage site is a considerable distance from important seal pupping and
haul out sites; both common and grey seals are likely to be present in only
limited numbers around the NUI location and for fairly short durations.
7.4.20 The piling operations would be subject to soft start and Marine Mammal
Observer requirements in line with JNCC Guidelines.
7.5 OPERATION OF THE OFFSHORE SCHEME
Underwater noise from NUI operation
7.5.1 Although there is little published data, noise emission from production platforms
is qualitatively similar to that from ships, and is produced mainly by rotating
machinery (turbines, generators, compressors), and noise resulting from the
operation of the NUI is expected to be similar to this. The only such machinery
present on the NUI are three diesel turbine generators, though during normal
operation a single generator at 40% load will be adequate for the required
power supply to platform facilities.
7.5.2 A further source of noise associated with all stages of the offshore oil industry
is helicopter overflights – anticipated incremental helicopter traffic associated
with the operation of the NUI is one trip every 6-7 weeks. There is relatively
little quantitative information on the transmission of helicopter airborne noise to
the marine environment (Richardson et al. 1995). Measurements of an air-sea
rescue helicopter over the Shannon estuary (Berrow et al. 2002) indicated that
due to the large impedance mismatch when sound travels from air to water, the
penetration of airborne sound energy from the rotor blades was largely
reflected from the surface of the water with only a small fraction of the sound
energy coupled into the water.
7.5.3 The operation of NUI will provide a continuous but low level source of noise,
and will not create significant additional shipping or helicopter traffic, and these
will use established routes.
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Storage Site Monitoring
7.5.4 The expected airgun source size for the monitoring seismic surveys is 470
cubic inch which has been used as the basis on which noise modelling and this
assessment has been undertaken.
7.5.5 Airgun arrays used for seismic surveys are one of the highest energy
anthropogenic sound sources in the sea; broadband source levels of 248-259
db re 1μPa are typical of large arrays (Richardson et al. 1995). Airgun noise is
impulsive (i.e. non-continuous), with a typical duty cycle of 0.3% and slow rise
time (in comparison to explosive noise). Most of the energy produced by
airguns is below 200Hz, although some high frequency noise may be emitted.
Peak frequencies of seismic arrays are generally around 100Hz; source levels
at higher frequencies are low relative to that at the peak frequency but are still
loud in absolute terms and relative to background levels.
7.5.6 In deep water, sound pressure can be assumed to propagate spherically (e.g.
Richardson et al. 1995), with received Sound Pressure Level, SPL = SL –
20log(R), where SL = source level (dB), R = source-receiver range (m).
7.5.7 Airgun arrays are directional and the design, dimensions and orientation of
arrays have a substantial influence on received noise pressure in the farfield
(i.e. at distances where individual gun sources are not distinguished). A
correction factor of 20dB has been suggested as “conservative”, to compensate
for horizontal array effects (i.e. reduction of effective source levels in the
horizontal plane relative to the vertical plane: MMS 2004).
7.5.8 Sound Exposure Level (SEL) is recommended by Southall et al. (2007) as an
indicator of exposure to multiple pulse noise; the derivation of SEL includes two
elements: integration of received sound energy over time (i.e. in units of dB re 1
μPa2s); and the use of M-weighting to simulate sensitivity of different function
hearing groups in marine mammals (low, mid, high frequency etc). Using the
equation for SEL given by Southall et al. (2007, Appendix A equation 5) and
representative amplitude time series, unweighted SEL for a 470 in 3 array
derived by summing sound pressure in 2 ms intervals approximates to 217 dB
re 1 μPa2 s. M-weighted SEL using estimated frequency cutoffs for functional
marine mammal hearing groups (Southall et al. 2007, Table 2 and Appendix A
equations 7 and 8) for the array are 217.0 dB for low frequency cetaceans,
203.1 dB for high frequency cetaceans and 213.2 dB for pinnipeds in water.
7.5.9 Noise propagation associated with an indicative monitoring survey has been
modelled for a source location at the NUI. SPL for an effective 241.6 dB re 1
μPa @ 1 m 0-p source has been calculated for a 100x100 model grid, at grid
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spacing 1.5 km, using spherical spreading at ranges <1.5 x water depth and
modified cylindrical spreading at ranges > 1.5 x water depth. Frequency-
dependent absorption losses were included, based on a dominant frequency of
50Hz.
7.5.10 The highest SPL mapped is 180 dB as levels only exceed this value at
distances <1.2 km from the source location. The 1.5 km grid spacing limits
fine-scale modelling of sound propagation in close proximity to the source.
However, various monitoring studies of seismic sources suggest that rapid
horizontal attenuation of SPL occurs close to the source array, with levels of ca.
180 dB not experienced beyond approximately 1 km horizontal distance of the
source, and ca. 200 dB only to 100 m from the source (Richardson et al. 1995,
MMS 2004).
7.5.11 The model predicts near-circular SPL contours at ranges within 50 km (to
approximately the 165 dB contour), within which variations in propagation
associated with bathymetry are not significant. The distances and areas
covered by SPL contours predicted by simple geometric propagation are
tabulated in Table 7.2.
Table 7.2 – Extent of predicted seismic sound pressure level propagation
contours from airgun array
SPL contour (dB re 1
µPa)
20logR radius from
source (km)
20logR area within
contour (km2)
200 0.1 0.05
195 0.2 0.14
190 0.4 0.45
185 0.7 1.4
180 1.2 5
175 2.1 14
170 3.8 45
165 6.7 143
160 12.0 452
155 21.3 1,431
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Table 7.2 – Extent of predicted seismic sound pressure level propagation
contours from airgun array
150 37.9 4,524
145 67.5 14,306
140 120.0 45,239
7.5.12 The above figures correlate well with the appropriate assessment undertaken
by DECC (DECC 2011) into the Seismic survey programme, Braemore, Forse,
Berriedale and Helmsdale Prospects and Burrigill site survey, which considered
the impact on the Dornoch Firth and Morrich More SAC harbour seal
population. Results from noise modelling studies indicated that there could be
a potential zone of auditory impact up to 200 m away but permanent effects
would only occur within 11 m of the survey vessel. DECC (2011) noted the
potential for the disturbance and displacement of seals in the vicinity of the
operating airguns with the most precautionary noise model indicating that this
may extend up to approximately 5km from the airguns.
7.5.13 From the above, together with the source characteristics and prediction of
propagation from the proposed survey presented above, the following
conclusions may be drawn:
SPLs known to cause acute auditory damage and PTS will be very
localised to directly below, and in the immediate horizontal vicinity (ca. 5
m for cetaceans; 25m for seals), of the source array. In view of soft start
and other mitigation measures, exposure of any marine mammals to a
SPL of this magnitude is very unlikely.
The affected area with a high probability of physiological effect, i.e. TTS,
is also localised, to approximately 130m of the source array. Other than
bow-riding dolphins, which would be observed by the Marine Mammal
Observer under the normal mitigation programme, the probability of
significant numbers of animals within this area is low.
There is a large range of potential audibility (>ca. 135 dB), and possible
behavioural effect (>ca. 160 dB), experienced up to approximately 12 km
from the source. Behavioural responses range from simply reacting to
the noise through to avoidance behaviours, however given the very low
densities of marine mammals in the area, effects are highly unlikely to be
significant.
7.5.14 The seismic surveys for monitoring the carbon dioxide plume movement in the
saline aquifer store will generate episodic (a few days, approximately once
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every 8 years) impulsive noise of relatively high intensity. There are relatively
low densities of marine mammals (in particular pinnipeds) present over the
storage site and standard mitigation measures will be applied to such surveys
(such as soft start).
7.5.15 Underwater noise effects of monitoring of relevance to seabirds include any
effects on prey, and the possibility of direct effects from noise. The physical
vulnerability of seabirds to sound pressure is unknown, although McCauley
(1994) inferred from vocalisation ranges that the threshold of perception for low
frequency seismic in some species (e.g. penguins, considered as a possible
proxy for auk species) would be high, hence only at short ranges would
individuals be adversely affected. Mortality of seabirds has not been observed
during extensive seismic operations in the North Sea and elsewhere. A study
investigated seabird abundance in Hudson Strait (Atlantic seaboard of Canada)
during seismic surveys over three years (Stemp 1985). Comparing periods of
shooting and non-shooting, no significant difference was observed in
abundance of fulmar, kittiwake and thick-billed murre (Brünnich’s guillemot).
Vessel activity
7.5.16 Vessels will be required to make regular, though infrequent (1 vessel every 6-7
weeks), trips to the NUI for chemical and diesel supply. These vessels will use
established routes and ports, and represent a very minor increment to existing
vessel traffic in the area.
7.5.17 In addition to supply visits, pipeline maintenance surveys will be undertaken,
initially on an annual basis. The vessel transits required to undertake this work
are not considered to represent a significant increment to existing fishing and
other shipping uses of Bridlington Bay and the wider area offshore out to the
storage site location.
Lighting
7.5.18 Both bird attraction and displacement effects have been noted for offshore
installations (see review in Ronconi et al. 2015). The potential effects of light
on birds have been raised in connection with offshore oil and gas activities and
specifically platforms over a number of years (e.g. Wiese et al. 2001). As part
of navigation and worker safety, oilfield installations and associated vessels are
lit at night and the lights will be visible at distance (some 10-12nm in good
visibility, also see Bruinzeel & van Belle (2010) for a consideration of platform
visibility under different meteorological conditions). The NUI will not have a
flare burning hydrocarbon gases. Platform illumination has been shown to
have an attractive effect on many species of migratory birds, with attraction
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enhanced in conditions of poor visibility such as fog, haze and drizzle (Wiese et
al. 2001 and references therein). Responses to a recent OSPAR questionnaire
seemed to indicate that the main cause of death was dehydration, starvation
and exhaustion, although some birds had physical damage resulting from
collisions with the infrastructure, and an even smaller number had interacted
with the flare or turbine exhausts. Birds which are attracted to these light
sources at night typically circle around the illuminated platform for extended
periods of time (sometimes many hours) and it has been suggested that the
circling increases the risk of collision (OSPAR 2012). It was concluded that
there was evidence that conventional lighting of offshore structures had an
impact on birds, but it could not be concluded that the effect was significant at
the population level (OSPAR 2012). Lighting on installation vessels will be
transient, with the only light sources to be continuous through project life being
from the NUI.
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Table 7.2: Humber Estuary SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
Humber Estuary SAC Conservation Objectives
Avoid the deterioration of the qualifying natural habitats and the habitats of qualifying species, and the significant disturbance of those qualifying species,
ensuring the integrity of the site is maintained and the site makes a full contribution to achieving Favourable Conservation Status of each of the qualifying
features.
Subject to natural change, to maintain or restore:
The extent and distribution of qualifying natural habitats and habitats of qualifying species;
The structure and function (including typical species) of qualifying natural habitats and habitats of qualifying species;
The supporting processes on which qualifying natural habitats and habitats of qualifying species rely;
The populations of qualifying species;
The distribution of qualifying species within the site.
Installation of the
pipeline potentially
resulting in an increase
or decrease of the down
drift sediment supply.
Estuaries
Mudflats and sandflats not covered by seawater at
low tide
Sandbanks which are slightly covered by sea
water all of the time
Coastal lagoons
Salicornia and other annuals colonising mud and
sand
Atlantic salt meadows (Glauco-Puccinellietalia
maritimae)
Embryonic shifting dunes
Shifting dunes along the shoreline with Ammophila
arenaria (‘white dunes’)
Fixed dunes with herbaceous vegetation (‘grey
dunes’)
Dunes with Hippophae rhamnoides
The nearhore pipeline will be buried and will therefore not interfere with the sediment
supply along the Holderness Coast in the long term.
The majority of cross-shore sediment transport takes place within the nearhore pipeline
from KP0 to KP16 as the active beach profile extends to the “depth of closure” which in
Bridlington Bay is estimated7 to be at the 7 m contour, please refer to Section 4.2.
However it should be noted that during summer months when the installation is
expected to take place, cross-shore transport and sediment movement is likely to be
more limited in extent. Considering summer (July) wave conditions, the limiting depth
for cross-shore transport by waves can still be expected to occur to approximately 4.5
m depth (effectively the wave base at this time) for medium to fine sand8.
Nearshore trenching operations will be controlled to avoid large variations in trench
depth, and excavated material will be sidecast. Enhanced suspended sediment
concentrations as a result of the trenching operations may be comparable to that of a
winter storm event.
The material excavated from the trench will be backfilled on top of the pipeline to the
former seabed level. Previous studies undertaken for similar pipeline installations at
Easington (e.g. Langeled, York) approximately 45 km to the south of Barmston have
suggested a conservative 10% loss of sediment excavated and sidecast during pipeline
installation. This would equate to a loss of 64,923 m3 of sediments for the total
excavated area including the access channel, please refer to Table 3.1. In the context
7 Based on:
, (after Hallermeier 1981) where He is “effective” wave height, being the significant wave height exceeded only 12 hours per year, and Te is its associated wave period. g is equal to acceleration due to gravity.
8 Based on
, (after Hallermeier 1981) where Hs is the mean significant wave height, Te is the mean significant wave period and D50 is the median grain size.
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Table 7.2: Humber Estuary SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
of erosional losses from Holderness (~3 million m3 per year) and the wider sediment
flux in this area, this volume is considered to represent a very small addition to annual
sediment loads and negligible in relation to that which is subsequently deposited at
Spurn Head and the Humber Estuary.
The maintenance of Spurn Head and wider sediment inputs to the Humber Estuary
reply on continued erosional input from the Holderness Coast and ongoing coastal
processes. As discussed in Section 4.2 the majority of this transport takes place within
the “depth of closure” therefore the surface laid pipeline from KP27.25 is unlikely to
have any interaction with sediment transport to regional sediment sinks including Spurn
Head and the Humber Estuary.
The installation of the pipeline is temporary and will not impede the availability of
sediment from the Holderness Coast reaching Spurn Head and the Humber Estuary.
There is however the potential for 10% (64,923 m3) of the sediment excavated and
sidecast during the pipeline installation to be lost. This volume is considered to
represent a small addition to annual sediment loads and negligible in relation to that
which is subsequently deposited at Spurn Head and the Humber Estuary. Therefore
the installation of the pipeline will not result in any implication on the conservation
objectives or an adverse effect on integrity.
Use of rock armouring
potentially interfering
with coastal process
resulting in an increase
or decrease of the down
drift sediment supply.
Estuaries
Mudflats and sandflats not covered by seawater at
low tide
Sandbanks which are slightly covered by sea
water all of the time
Coastal lagoons
Salicornia and other annuals colonising mud and
sand
Atlantic salt meadows (Glauco-Puccinellietalia
maritimae)
Embryonic shifting dunes
Shifting dunes along the shoreline with Ammophila
arenaria (‘white dunes’)
Fixed dunes with herbaceous vegetation (‘grey
dunes’)
The rock cover required for the nearshore pipeline stability will be buried below bed
level and will not result in any implication on the conservation objectives or an adverse
effect on integrity.
There are three crossings proposed two (Dogger Bank Creyke Beck export cables) on
the nearshore pipeline section and one (Langeled Pipeline) on the surface laid pipeline
section. As discussed in Section 4.2 the majority of both longshore drift and cross
shore transport takes place within the “depth of closure” therefore the rock cover for
the Langeled crossing is unlikely to have any interaction with sediment transport to
regional sediment sinks including Spurn Head and the Humber Estuary and therefore
will not result in any implication on the conservation objectives or an adverse effect on
integrity. The crossing locations for the export cables will be between KP8 and KP17 in
corresponding water depths of between 10 and 40m. These are both outside of the
“depth of closure”, please refer to Section 4.2 and Figure 4.2. Therefore rock cover for
these crossings is also unlikely to have any interaction with sediment transport to
regional sediment sinks including Spurn Head and the Humber Estuary and therefore
will not result in any implication on the conservation objectives or an adverse effect on
integrity.
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Table 7.2: Humber Estuary SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
Dunes with Hippophae rhamnoides A worst case estimate of 600 tonnes of rock for scour protection around the rig spud
cans at the NUI. This rock protection is unlikely to have any interaction with sediment
transport to regional sediment sinks including Spurn Head and the Humber Estuary
and therefore will not result in any implication on the conservation objectives or an
adverse effect on integrity.
Disturbance from the
physical presence of
pipeline and NUI
installation vessels.
Grey seal halichoerus grypus Sections of the offshore pipeline route and storage area are located within or close to
areas of low to moderate grey seal usage. Please refer to Figure 4.3. Both the pipeline
and NUI installation is temporary and the pipelay activities are transient, the lay rate of
the nearshore installation out to the 30 m depth contour (approximately 15 km) is
approximately 500 m a day in the nearshore area and 4 km a day for the Pipeline. The
Pipeline installation is not expected to exceed 4 months in duration in total. In addition
the Offshore Scheme is remote from relevant haulout sites and low to medium
numbers of grey seal are likely to be present over the area of the Offshore Scheme at
any one time. Therefore the presence of installation vessels will not result in any
implication on the conservation objectives or an adverse effect on integrity.
With regards to corkscrew injuries interim advice by the statutory nature conservation
bodies (SNCB) advises that activities proposed to take place beyond 4nm from a grey
seal SAC are regarded as having a low risk. The Offshore Scheme is at least 30nm
from the Humber Estuary SAC and therefore this interest feature is considered to be at
low risk of mortality due to the presence of construction vessels. Therefore the
presence of installation vessels will not result in any implication for the conservation
objectives or for adverse effect on integrity.
Disturbance to marine
mammals from
underwater noise.
Grey seal halichoerus grypus The noise from pipeline installation vessels is generally equivalent to that generated by
large merchant vessels (e.g. McCauley 1994), please refer to Section 7.4.3-7.4.6. This
would be a temporary incremental source of noise in an area already subject to low
(nearshore) to moderate and high (offshore) shipping density. There is also limited
potential interactions with individual grey seals from pipeline installation and rock
placement (no discernible difference between normal vessel operating conditions and
those during rock placement, Section 7.4.5) therefore noise from pipeline installation
will not result in any implication on the conservation objectives or an adverse effect on
integrity.
With regards to drilling activities, available measurements indicate that drilling activities
produce mainly low-frequency continuous noise from several separate sources on the
drilling unit (Richardson et al. 1995, Lawson et al. 2001). Sound pressure levels are
probably typical of drilling from jack-up and semi-submersible rigs respectively, and are
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Table 7.2: Humber Estuary SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
of the same order and dominant frequency range as that from large merchant vessels
(e.g. McCauley 1994), please refer to Section 7.4.7 -7.4.9. It is reasonable to expect
drilling noise associated with the injection wells to be comparable in source
characteristics. The noise from drilling activities would be temporary, enduring for
around one month per well; however the rig noise is lower than that from a medium
sized cargo ship. and in the context of limited potential interactions with individual grey
seals in the vicinity of the storage site. Therefore noise from drilling will not result in any
implication on the conservation objectives or an adverse effect on integrity.
The NUI installation will be temporary and percussive piling operations would be
expected to have a total duration of around 4.5 days with piling occurring for some 96
hours over that period; all piling operations would incorporate a “soft start” procedure. A
review of underwater noise from piling operations and the associated risk to marine
mammals is discussed in Section 7.4.10 – 7.4.20. The storage site is a considerable
distance from important seal pupping and haulout sites. In addition, grey seals are
likely to be present in only limited numbers around the NUI location and for fairly short
durations. The piling operations would be subject to soft start and Marine Mammal
Observer requirements (in line with JNCC Guidelines), therefore with regards to the
above underwater noise from installation of the NUI wil not result in any implication on
the conservation objectives or an adverse effect on integrity.
Disturbance from
vessels and activities
associated with the
operation of the
Offshore Scheme.
Grey seal halichoerus grypus With regards to the operation of the NUI, the only such machinery present on the NUI
are three diesel turbine generators, though during normal operation a single generator
at 40% load will be adequate for the required power supply to platform facilities. The
noise from these generators will be small compared to a standard gas or oil platform
and only a small amount of the noise has the potential to couple into the water.
The anticipated incremental helicopter traffic associated with the operation of the NUI is
one trip every 6-7 weeks. There is relatively little quantitative information on the
transmission of helicopter airborne noise to the marine environment, please refer to
Section 7.5.2, however evidence suggests that sound energy from the rotor blades is
largely reflected from the surface of the water with only a small fraction of the sound
energy coupled into the water. Therefore with regards to the above underwater noise
from operation of the NUI will not result in any implication on the conservation
objectives or an adverse effect on integrity.
With regards to monitoring of the storage site, seismic surveys will be undertaken to
monitor the carbon dioxide plume. An assessment of underwater noise associated with
these surveys is presented in Sections 7.5.4 to 7.5.15. The seismic surveys for
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Table 7.2: Humber Estuary SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
monitoring the carbon dioxide plume movement in the saline aquifer store will generate
episodic (a few days, approximately once every 8 years) impulsive noise of relatively
high intensity. There are relatively low densities of marine mammals (in particular
pinnipeds) present over the storage site and standard mitigation measures will be
applied to such surveys (such as soft start). Therefore with regards to the above and
Sections 7.5.4 to 7.5.15 underwater noise from monitoring of the storage site will not
result in any implication on the conservation objectives or an adverse effect on
integrity.
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Table 7.3Flamborough HHead SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
Flamborough Head SAC Conservation Objectives
Ensure that the integrity of the site is maintained or restored as appropriate, and ensure that the site contributes to achieving the Favourable Conservation
Status of its Qualifying Features, by maintaining or restoring;
The extent and distribution of qualifying natural habitats
The structure and function (including typical species) of qualifying natural habitats, and
The supporting processes on which qualifying natural habitats rely
Installation of the
pipeline potentially
resulting in an increase
or decrease of the down
drift sediment supply.
Reefs
Vegetated sea cliffs of the Atlantic and Baltic
Coats
Submerged or partially submerged sea caves
The nearhore pipeline will be buried and will therefore not interfere with the sediment
supply along the Holderness Coast in the long term.
The majority of cross-shore sediment transport takes place within the nearhore pipeline
from KP0 to KP16 as the active beach profile extends to the “depth of closure” which in
Bridlington Bay is estimated9 to be at the 7m contour, please refer to Section 4.2.
However it should be noted that during summer months when the installation is
expected to take place, cross-shore transport and sediment movement is likely to be
more limited in extent. Considering summer (July) wave conditions, the limiting depth
for cross-shore transport by waves can still be expected to occur to approximately 4.5m
depth (effectively the wave base at this time) for medium to fine sand10.
Nearshore trenching operations will be controlled to avoid large variations in trench
depth, and excavated material will be sidecast. Enhanced suspended sediment
concentrations as a result of the trenching operations may be comparable to that of a
winter storm event.
The material excavated from the trench will be backfilled on top of the pipeline to the
former seabed level. Previous studies undertaken for similar pipeline installations at
Easington (e.g. Langeled, York) approximately 45 km to the south of Barmston have
suggested a conservative 10% loss of sediment excavated and sidecast during pipeline
installation. This would equate to a loss of 64,923m3 of sediments for the total
excavated area including the access channel, please refer to Table 3.1. In the context
of erosional losses from Holderness (~3 million m3 per year) and the wider sediment
flux in this area, this volume is considered to represent a small addition to annual
sediment loads.
Any sediment lost during trenching is likely to be carried south and away from the site
9 Based on:
, (after Hallermeier 1981) where He is “effective” wave height, being the significant wave height exceeded only 12 hours per year, and Te is its associated wave period. g is equal to acceleration due to gravity.
10 Based on
, (after Hallermeier 1981) where Hs is the mean significant wave height, Te is the mean significant wave period and D50 is the median grain size.
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Table 7.3Flamborough HHead SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
under average sediment transport conditions. Though there is the potential for
northerly sediment movement under spring tides (Pethick 1994), these movements are
regarded to be small in the context of natural southerly sediment movement. In the
context of predictions in terms of the interactions between the coastal processes,
sediment regime and the installation of the Pipeline set out in Section 4.2 and 7.2. The
installation of the pipeline will not result in any implication on the conservation
objectives or an adverse effect on integrity.
Use of rock armouring
potentially interfering
with coastal process
resulting in an increase
or decrease of the down
drift sediment supply.
Reefs
Vegetated sea cliffs of the Atlantic and Baltic
Coats
Submerged or partially submerged sea caves
The rock cover required for the nearshore pipeline stability will be buried below bed
level and will not interfere with coastal process or result in any implication on the
conservation objectives or an adverse effect on integrity.
There are three crossings proposed two (Dogger Bank Creyke Beck export cables) on
the nearshore pipeline section and one (Langeled Pipeline) on the surface laid pipeline
section. As discussed in Section 4.2 the majority of this transport takes place within
the “depth of closure” therefore the rock cover for the Langeled crossing is unlikely to
have any interaction with sediment transport to regional sediment sinks. The crossing
locations for the export cables will be between KP8 and KP17 in corresponding water
depths of between 10 and 40m. These are both outside of the “depth of closure”,
please refer to Section 4.2 and Figure 4.2. Therefore rock cover for these crossings is
unlikely to have any interaction with sediment transport to regional sediment sinks.
A worst case estimate of 600 tonnes of rock for scour protection around the rig spud
cans at the NUI has been assumed. This rock protection is unlikely to have any
interaction with sediment transport to regional sediment sinks.
Based on the above and that the natural movement of sediment is to the south away
from the site under average sediment transport conditions, the use of rock cover is site
will not result in any implication on the conservation objectives or an adverse effect on
integrity.
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Table 7.4: Flamborough Head and Bempton Cliffs SPA Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
Flamborough Head and Bempton Cliffs SPA
Avoid the deterioration of the habitats of the qualifying features, and the significant disturbance of the qualifying features, ensuring the integrity of the site is
maintained and the site makes a full contribution to achieving the aims of the Birds Directive.
Subject to natural change, to maintain or restore:
The extent and distribution of the habitats of the qualifying features;
The structure and function of the habitats of the qualifying features;
The supporting processes on which the habitats of the qualifying features rely;
The populations of the qualifying features;
The distribution of the qualifying features within the site.
Disturbance from the
physical presence of
pipeline and NUI
installation vessels.
Kittiwake rissa tridactyla
Assemblage features (puffin fratercula arctica,
razorbill alca torda, guillemot uria aalge, herring gull
larcus argentatus, northern gannet morus
bassanus, kittiwake rissa tridactyla)
Behaviours such as preening, bathing and displaying, tend to occur in close proximity
(1-2km) to colonies, please refer to Section 7.3.4. Due to the distance between
installation activities (approximately 4km from the nearshore pipeline) the installation
of the pipeline will not result in any implication on the conservation objectives or an
adverse effect on integrity in relation to these behaviours.
The foraging ranges suggest the potential feeding area available is large for guillemot
and gannet, please refer to Section 7.3.5. Whilst these large ranges indicate that
given the transient nature of the installation work and the wide availability of foraging
habitat, their sensitivity to disturbance is limited they could forage out to as far as the
storage site. However, the number of individuals likely to be foraging as far out as the
NUI is limited. Given the temporary nature of the installation activities and the above,
the installation of the Offshore Scheme will not result in any implication on the
conservation objectives or an adverse effect on integrity in relation to these interest
features.
Kittiwake and razorbill have a smaller foraging area and are also limited to specific
prey requirements (e.g. sandeel, see Furness & Tasker 2000), spawning and nursery
grounds, which coincide with the offshore section of the pipeline route. The sensitivity
of Puffins may be considered similar to that of razorbill. These species have been
judged to have a low to moderate sensitivity to disturbance by shipping traffic (Garthe
& Hüppop 2004). Pipeline installation activities are expected to be comparable to
shipping in terms of magnitude of bird disturbance effects due to physical presence,
and disturbance effects for alcids from shipping tends to be in the range of hundreds
of metres. Therefore, whilst disturbance of individual birds may occur along the
pipeline route any disturbance can therefore be expected to take place within several
hundred metres of the installation vessels and are unlikely to generate bird mortality
or affect the bird colonies at the population level. Given the temporary nature of the
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Table 7.4: Flamborough Head and Bempton Cliffs SPA Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
installation activities, and the limited spatial extent of potential effects and the above,
the installation of the Offshore Scheme will not result in any implication on the
conservation objectives or an adverse effect on integrity in relation to these interest
features.
The sidecast material from the trenching operations and direct effects from the
trenching will cover a relatively small area of seabed in proportion to the total area
available, and effects (e.g. smothering) on benthic ecology related to seabird prey are
also likely to be limited in scale and magnitude. Any sediment plume associated with
the access channel and nearshore trench will be minimised through efficient vessel
use, is likely to be short lived, and would tend to be carried to the south away from
Flamborough Head and offshore under average sediment transport conditions. Given
the temporary nature of the installation activities and the above points, the installation
of the Offshore Scheme is will not result in any implication for the conservation
objectives or have an adverse effect on integrity in relation to sediment plumes.
Disturbance from
vessels and activities
associated with the
operation of the
Offshore Scheme.
Kittiwake rissa tridactyla
Assemblage features (puffin fratercula arctica,
razorbill alca torda, guillemot uria aalge, herring gull
larcus argentatus, northern gannet morus
bassanus, kittiwake rissa tridactyla)
Supply vessels to the NUI will be regular but infrequent (1 vessel every 6-7 weeks). In
addition pipeline maintenance surveys will be undertaken, initially on an annual basis.
These vessels are not considered to represent a significant increment to existing
fishing and other shipping uses of Bridlington Bay and the wider area offshore out to
the storage site location. Therefore vessel activities during the operation of the
Offshore Scheme will not result in any implication on the conservation objectives or an
adverse effect on integrity.
Helicopter overflights associated with the operation of the NUI is one trip every 6-7
weeks these will be from established airports and will not result in any implication on
the conservation objectives or an adverse effect on integrity.
Based on a review of lighting from offshore installations (please refer to Section
7.5.18) it was concluded that there was evidence that conventional lighting of offshore
structures had an impact on birds, but it could not be concluded that the effect was
significant at the population level (OSPAR 2012). The NUI will not have a flare
burning hydrocarbon gases and, as highlighted in Section 7.3.5 & 7.3.6 the foraging
ranges during the breeding season are limited. Taking all of these factors into account
lighting of the NUI will not result in any implication on the conservation objectives or
an adverse effect on integrity.
With regards to underwater noise effects of monitoring of the storage site, mortality of
seabirds has not been observed during extensive seismic operations in the North Sea
and elsewhere. Based on Section 7.3.15 and the above monitoring of the storage site
will not result in any implication on the conservation objectives or an adverse effect on
integrity.
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Table 7.5: Flamborough Head and Filey Coast pSPA Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
Conservation Objectives of Flamborough Head and Filey Coast pSPA
Avoid the deterioration of the habitats of the qualifying features, and the significant disturbance of the qualifying features, ensuring the integrity of the site is
maintained and the site makes a full contribution to achieving the aims of the Birds Directive.
Subject to natural change, to maintain or restore:
The extent and distribution of the habitats of the qualifying features;
The structure and function of the habitats of the qualifying features;
The supporting processes on which the habitats of the qualifying features rely;
The populations of the qualifying features;
The distribution of the qualifying features within the site.
Disturbance from the
physical presence of
pipeline and NUI
installation vessels.
Black-legged kittiwake rissa tridactyla
Northern gannet morus bassanus
Common guillemot uria aalge
Razorbill alca torda
Assemblage features (black-legged kittiwake,
northern gannet, common guillemot, razorbill,
northern fulmar fulmarus glacialis)
Behaviours such as preening, bathing and displaying, tend to occur in close proximity
(1-2km) to colonies, please refer to Section 7.3.4. Due to the distance between
installation activities (approximately 4km from the nearshore pipeline) the installation
of the pipeline will not result in any implication on the conservation objectives or an
adverse effect on integrity in relation to these behaviours.
The foraging ranges suggest the potential feeding area available is large for guillemot
gannet and fulmar, please refer to Section 7.3.5. Whilst these large ranges indicate
that, given the transient nature of the installation work and the wide availability of
foraging habitat their sensitivity to disturbance is limited, they could forage out to as
far as the storage site. However, the number of individuals likely to be foraging as far
out as the NUI is limited. Given the temporary nature of the installation activities and
the above, the installation of the Offshore Scheme will not result in any implication on
the conservation objectives or an adverse effect on integrity in relation to these
interest features.
Kittiwake and razorbill and fulmar have a smaller foraging area and are also limited to
specific prey requirements (e.g. sandeel, see Furness & Tasker 2000), spawning and
nursery grounds, which coincide with the offshore section of the pipeline route. These
species have been judged to have a low to moderate sensitivity to disturbance by
shipping traffic (Garthe & Hüppop 2004). Pipeline installation activities are expected
to be comparable to shipping in terms of magnitude of bird disturbance effects due to
physical presence, and disturbance effects for alcids from shipping tends to be in the
range of hundreds of metres. Therefore, whilst disturbance of individual birds may
occur along the pipeline route any disturbance can therefore be expected to take
place within several hundred metres of the installation vessels and are unlikely to
generate bird mortality or affect the bird colonies at the population level. Given the
temporary nature of the installation activities and the above, the installation of the
Offshore Scheme will not result in any implication on the conservation objectives or an
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Table 7.5: Flamborough Head and Filey Coast pSPA Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
adverse effect on integrity in relation to these interest features.
The sidecast material from the trenching operations and direct effects from the
trenching will cover a relatively small area of seabed in proportion to the total area
available, and effects (e.g. smothering) on benthic ecology related to seabird prey are
also likely to be limited in scale and magnitude. Any sediment plume associated with
the access channel and nearshore trench will be minimised through efficient vessel
use, is likely to be short lived, and would tend to be carried to the south away from
Flamborough Head and offshore under average sediment transport conditions. Given
the temporary nature of the installation activities and the above points, the installation
of the Offshore Scheme will not result in any implication for the conservation
objectives or have an adverse effect on integrity in relation to sediment plumes.
Disturbance from
vessels and activities
associated with the
operation of the
Offshore Scheme.
Black-legged kittiwake rissa tridactyla
Northern gannet morus bassanus
Common guillemot uria aalge
Razorbill alca torda
Assemblage features (black-legged kittiwake,
northern gannet, common guillemot, razorbill,
northern fulmar fulmarus glacialis)
Supply vessels to the NUI will be regular but infrequent (1 vessel every 6-7 weeks). In
addition pipeline maintenance surveys will be undertaken, initially on an annual basis.
These vessels are not considered to represent a significant increment to existing
fishing and other shipping uses of Bridlington Bay and the wider area offshore out to
the storage site location. Therefore vessel activities during the operation of the
Offshore Scheme will not result in any implication on the conservation objectives or an
adverse effect on integrity.
Helicopter overflights associated with the operation of the NUI is one trip every 6-7
weeks these will be from established airports and will not result in any implication on
the conservation objectives or an adverse effect on integrity.
Based on a review of lighting from offshore installations (please refer to Section
7.5.18) it was concluded that there was evidence that conventional lighting of offshore
structures had an impact on birds, but it could not be concluded that the effect was
significant at the population level (OSPAR 2012). The NUI will not have a flare
burning hydrocarbon gases and, as highlighted in Section 7.3.5 & 7.3.6 the foraging
ranges during the breeding season are limited. Taking all of these factors into account
lighting of the NUI will not result in any implication on the conservation objectives or
an adverse effect on integrity.
With regards to underwater noise effects of monitoring of the storage site, mortality of
seabirds has not been observed during extensive seismic operations in the North Sea
and elsewhere. Based on Section 7.5.15 and the above monitoring of the storage site
will not result in any implication on the conservation objectives or an adverse effect on
integrity.
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Table 7.6: The Wash and North Norfolk Coast SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
Conservation Objectives of the Wash and North Norfolk Coast SAC
Ensure that the integrity of the site is maintained or restored as appropriate, and ensure that the site contributes to achieving the Favourable Conservation
Status of its Qualifying Features, by maintaining or restoring;
The extent and distribution of qualifying natural habitats and habitats of qualifying species
The structure and function (including typical species) of qualifying natural habitats
The structure and function of the habitats of qualifying species
The supporting processes on which qualifying natural habitats and the habitats of qualifying species rely
The populations of qualifying species, and,
The distribution of qualifying species within the site.
Disturbance from the
physical presence of
pipeline and NUI
installation vessels.
Common seal phoca vitulina Sections of the offshore pipeline route and storage area are located within or close to
areas of low harbour seal usage (please refer to Figure 4.4). Both the pipeline and
NUI installation is temporary and the pipelay activities are transient, the lay rate of the
nearshore installation out to the 30 m depth contour (approximately 15 km) is
approximately 500 m a day in the nearshore area and 4 km a day for the Pipeline.
The Pipeline installation is not expected to exceed 4 months in duration in total. In
addition the Offshore Scheme is remote from relevant haulout sites and low numbers
of marine mammals are likely to be present over the area of the Offshore Scheme at
any one time. Therefore the presence of installation vessels will not result in any
implication on the conservation objectives or an adverse effect on integrity.
With regards to corkscrew injuries interim advice by the statutory nature conservation
bodies (SNCB) advises that activities proposed to take place beyond 30nm from a
harbour seal SAC are regarded as having a low risk. The Offshore Scheme is at least
107km from the Wash and North Norfolk Coast SAC and therefore this interest feature
is considered to be at low risk of mortality due to the presence of construction vessels.
Therefore the presence of installation vessels will not result in any implication on the
conservation objectives or an adverse effect on integrity.
Disturbance to marine
mammals from
underwater noise
Common seal phoca vitulina The noise from pipeline installation vessels is generally equivalent to that generated
by large merchant vessels (e.g. McCauley 1994), please refer to Section 7.4.3 – 7.4.6.
This would be a temporary incremental source of noise in an area already subject to
low (nearshore) to moderate and high (offshore) shipping density. There is also
limited potential interactions with individual harbour seals, pipeline installation and
rock placement therefore noise from pipeline installation will not result in any
implication on the conservation objectives or an adverse effect on integrity.
With regards to drilling activities, available measurements indicate that drilling
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Table 7.6: The Wash and North Norfolk Coast SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
activities produce mainly low-frequency continuous noise from several separate
sources on the drilling unit (Richardson et al. 1995, Lawson et al. 2001). Sound
pressure levels are probably typical of drilling from jack-up and semi-submersible rigs
respectively, and are of the same order and dominant frequency range as that from
large merchant vessels (e.g. McCauley 1994), please refer to Section 7.4.7 – 7.4.9. It
is reasonable to expect drilling noise associated with the injection wells to be
comparable in source characteristics. The noise from drilling activities would be
temporary and in the context of limited potential interactions with individual harbour
seals in the vicinity of the storage site. Therefore noise from drilling will not result in
any implication on the conservation objectives or an adverse effect on integrity.
The NUI installation will be temporary and percussive piling operations would be
expected to have a total duration of around 4.5 days with piling occurring for some 96
hours over that period; all piling operations would incorporate a “soft start” procedure.
A review of underwater noise from piling operations and the associated risk to marine
mammals is discussed in Section 7.4.10 – 7.4.20. The storage site is a considerable
distance from important seal pupping and haulout sites. In addition for harbour seals
are likely to be present in only limited numbers around the NUI location and for fairly
short durations. The piling operations would be subject to soft start and Marine
Mammal Observer requirements (in line with JNCC Guidelines), therefore with regards
to the above underwater noise from installation of the NUI will not result in any
implication on the conservation objectives or an adverse effect on integrity.
Disturbance from
vessels and activities
associated with the
operation of the
Offshore Scheme.
Common seal phoca vitulina With regards to the operation of the NUI, the only such machinery present on the NUI
are three diesel turbine generators, though during normal operation a single generator
at 40% load will be adequate for the required power supply to platform facilities. The
anticipated incremental helicopter traffic associated with the operation of the NUI is
one trip every 6-7 weeks. There is relatively little quantitative information on the
transmission of helicopter airborne noise to the marine environment, please refer to
Section 7.5.2, however evidence suggests that sound energy from the rotor blades is
largely reflected from the surface of the water with only a small fraction of the sound
energy coupled into the water. Therefore with regards to the above underwater noise
from installation of the NUI will not result in any implication on the conservation
objectives or an adverse effect on integrity.
With regards to monitoring of the storage site, seismic surveys will be undertaken to
monitor the carbon dioxide plume. An assessment of underwater noise associated
with these surveys is presented in Sections 7.5.4 to 7.5.15. The seismic surveys for
monitoring the carbon dioxide plume movement in the saline aquifer store will
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Table 7.6: The Wash and North Norfolk Coast SAC Potential for Adverse Effect on Site Integrity
Mechanism for effect Interest features Potential for Adverse Effect on Integrity
generate episodic (a few days, approximately once every 8 years) impulsive noise of
relatively high intensity. There are relatively low densities of marine mammals (in
particular pinnipeds) present over the storage site and standard mitigation measures
will be applied to such surveys (such as soft start). Therefore with regards to the
above and Sections 7.5.4 to 7.5.15 underwater noise from monitoring of the storage
site will not result in any implication on the conservation objectives or an adverse
effect on integrity.
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8.1 INTRODUCTION
8.1.1 This section looks at the potential for the Offshore Scheme to result in in-
combination effects with other developments, which when aggregated together
could result in an adverse effect on site integrity.
8.2 RELEVANT DEVELOPMENTS
8.2.1 The following developments are considered relevant to the assessment of in-
combination effects:
Dogger Bank Creyke Beck Offshore Wind Farm
Hornsea Round 3 developments
Dogger Bank Creyke Beck Offshore Wind Farm
8.2.2 This is the first stage of development in the Dogger Bank Zone. It will have an
installed capacity of up to 2.4 gigawatts (GW) and will connect into the existing
Creyke Beck substation near Cottingham, in the East Riding of Yorkshire. It will
comprise of two offshore wind farms with an installed capacity of up to 1.2 GW
each:
Dogger Bank Creyke Beck A located in the southern part of Tranche A,
with a size of 515 square kilometre (km2) and 131 kilometres (km) from
shore at its closest point; and
Dogger Bank Creyke Beck B located in the western part of Tranche A,
the largest in area with a size of 599 km2 and also 131 km
8.2.3 The DCO was submitted to PINS in September 2013 and it is due to be
constructed between 2016 and 2021.
Hornsea Offshore Wind Farm – Project One
8.2.4 Project One, within the Hornsea Zone, is the first of a number of wind farm
projects planned for the Hornsea Zone. Hornsea Zone is located in the
southern North Sea, off the coast of The East Riding of Yorkshire.
8.2.5 Project One will comprises wind turbine generators with a combined capacity of
up to 1.2 GW and all infrastructure up to the point of connection with the
National Grid via the existing North Killingholme substation.
8 In combination Assessment
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8.2.6 The wind turbine generators will be located in the centre of the Hornsea Zone,
covering an area of approximately 407 km², with the nearest turbine at least
103 km from the East Riding of Yorkshire coast.
8.2.7 From the proposed landfall point at Horseshoe Point, cables will connect the
offshore wind farms to the North Killingholme substation (approximately 40 km),
a new HVDC converter station or HVAC substation will be required in the
vicinity of the substation.
8.2.8 The DCO was submitted to PINS in July 2013 and was granted in December
2014. Construction is likely to commence in 2015.
Hornsea Offshore Wind Farm – Project Two
8.2.9 Project Two is the second of a number of wind farm projects planned for the
Hornsea Zone to meet a target zone capacity of 4 GW by the year 2020.
8.2.10 Project Two will comprise a proposed wind farm of up to 1,800 MW in
maximum installed generating capacity. The project may comprise one or
several wind farm arrays when constructed and will include all necessary
offshore and onshore infrastructure required to connect to the existing National
Grid substation located at North Killingholme. The site will be situated within
‘Subzone 2’.
8.2.11 The project is at pre application stage.
8.2.12 A DCO application is expected to be submitted to PINS in late 2014.
Construction is likely to commence in 2016/2017 with a five year construction
programme.
Hornsea Offshore Wind Farm – Project Three
8.2.13 This is the closest of the three projects to the Offshore Scheme. This project is
at pre-application stage and details are currently unknown.
8.3 POTENTIAL FOR IN-COMBINATION EFFECTS
8.3.1 The predicted effects as outlined in the Environmental Statements and other
relevant submissions made for these developments have been reviewed and
considered in the context of the Offshore Scheme. The potential for in-
combination effects with the Offshore Scheme that could result in an adverse
effect on site integrity is discussed in Table8.1 below.
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Table 8.1: Potential for In-combination effects
Mechanism
for effect
Projects Potential In-combination effect Sites
Installation
of the
pipeline
potentially
resulting in
an increase
or decrease
of down drift
sediment
supply.
Dogger
Bank
Creyke
Beck
project
The landfall for the Forewind
Dogger Bank Creyke Beck A & B
projects is located to the north of
Ulrome, approximately 2.5 km to
the south of the proposed landfall
for the Offshore Scheme. The
preferred landfall method involves
directionally drilling to a location
in the subtidal area and the
installation of cable ducts through
which the cables would then be
pulled ashore (Forewind 2014a).
This method negates the need for
an intertidal cofferdam, although
a cofferdam may be used if
geotechnical issues arise.
Should cofferdams be required,
their maximum dimensions are 10
m wide, 15 m long and 3 m deep
(Forewind 2013a), with a
separate cofferdam being
required for each cable (i.e. up to
4), which would be in place for 2
months per cable. This would
result in the removal of 450 m3 of
sediment per cable installation
(1,800 m3 for all four cables) and
result in some sediment trapping.
No impact on natural erosion
processes is predicted by
Forewind (2013b) for the landfall
construction and in-combination
with the Offshore Scheme will not
result in changes to the sediment
transport which could affect the
integrity of regional sinks.
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
the Humber
Estuary SAC.
Hornsea
Round 3
developm
The assessment has concluded
that an adverse effect on integrity
from the installation of the
There is no
potential for the
in-combination
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Table 8.1: Potential for In-combination effects
Mechanism
for effect
Projects Potential In-combination effect Sites
ents offshore scheme is unlikely as
there will be no reduction in
sediment supply to the regional
sinks and once constructed there
will be no effect on coastal
processes, therefore even if
constructed at the same time it is
unlikely in-combination effects on
regional sinks would result.
effects to result in
adverse effects
on the integrity of
the Humber
Estuary SAC.
Use of rock
armouring
potentially
interfering
with coastal
processes
resulting in
an increase
or decrease
in down drift
sediment
supply.
Dogger
Bank
Creyke
Beck
project
Immediately offshore, and along
the route to the wind farm
location, the offshore export cable
is to be buried by one of a
number of techniques (e.g.
jetting, ploughing, trenching,
cutting, mass flow excavation,
potentially with some pre-
sweeping) to be confirmed
following final geotechnical
investigations. Initial findings
indicated that remedial cable
protection in the form of
mattresses or rock dump may be
required where hard seabed
substrates prevent sufficient
cable burial (Forewind 2013b).
Such conditions are particularly
evident in the inshore area out to
32.5 km offshore and particularly
in the first 7.5 km, and therefore
protection measures may be
required in this area (Forewind
2013b). It is likely that only 10%
of each cable would require
protection in this area with a
worst case width of 15 m and a
height above seabed of 1.5 m
(equating to an overall seabed
footprint of 48,000 m2). Forewind
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
the Humber
Estuary SAC.
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Table 8.1: Potential for In-combination effects
Mechanism
for effect
Projects Potential In-combination effect Sites
(2013b) predict that there will be
no interruption in bedload
sediment supply either as
longshore or nearshore bedload
transport resulting from the
imposition of cable protection
measures in the shallow subtidal
area.
The pipeline for the Offshore
Scheme will be buried within the
nearshore area and any rock
cover required in this section will
be below bed level, therefore
there is no potential for an in-
combination effect with the
Dogger Bank Creyke Beck
project. Rock cover above the
bed surface will be required in the
nearshore section at the
crossings with the Dogger Bank
Creyke Beck export cables but
this has already been taken into
account within the assessment
and therefore will not result in an
in-combination effect.
Disturbance
from the
physical
presence of
pipeline and
NUI
installation
vessels
Dogger
Bank
Creyke
Beck
project
Hornsea
Round 3
developm
ents
Marine Mammals
With regards to the specific issue
of corkscrew injuries to seals,
Forewind (2013e) indicate that
the distance between the
proposed Creyke Beck
development and harbour and
grey seal SACs is such that the
risk of injury is considered low in
each case following SNCB
(2012). Similar considerations for
the Hornsea Project One
Development (SMartWind 2013a)
indicate that the risk of injury is
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
the Humber
Estuary SAC.
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
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Table 8.1: Potential for In-combination effects
Mechanism
for effect
Projects Potential In-combination effect Sites
considered low for the
development area, though
activities associated with cable
export route represent a medium
risk to both harbour and grey
seals such that alternative vessel
choice and/or a Seal Corkscrew
Injury Monitoring Scheme would
need to be considered. As the
risk of injury for the Offshore
Scheme is regarded to be low,
that the construction of these
projects may not be coincident,
and in the context of the transient
and low incremental level of
shipping that the Offshore
Scheme represents, Offshore
Scheme installation activities are
not considered to be a source of
in-combination effects that are
likely to result in an adverse
effect on integrity.
Seabirds
No effects were predicted on
seabirds (including species which
are qualifying features of
designated sites such as razorbill,
puffin and guillemot) from
disturbance arising from the
installation activities associated
with the Dogger Bank Creyke
Beck A & B projects. Due to the
low potential for disturbance to
seabirds during the installation of
the Offshore Scheme in-
combination an adverse effect on
integrity is not predicted.
the Wash and
North Norfolk
Coast SAC.
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
Flamborough
Head and
Bempton Cliffs
SPA and
Flamborough
Head and Filey
Coast pSPA.
Disturbance
from
Dogger
Bank
Information provided for
Appropriate Assessment in
There is no
potential for the
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Table 8.1: Potential for In-combination effects
Mechanism
for effect
Projects Potential In-combination effect Sites
underwater
noise
Creyke
Beck
project
Hornsea
Round 3
developm
ents
relation to both the Dogger Bank
Creyke Beck A & B (Forewind
2013e) and Hornsea Project One
(SMartWind 2013b) indicate that
construction (e.g. piling, cable
lay), operation or
decommissioning would not result
in adverse effects for the Humber
Estuary SAC and The Wash and
North Norfolk Coast SAC for grey
and harbour seals respectively,
including when considering the
potential for in-combination
effects with other relevant
projects.
In the context of piling activities
and related noise that could be
generated by the installation of
wind turbine foundations at the
Creyke Beck and Hornsea
Project One sites (a worst case of
1,200 and 1,420 pin piles
respectively, assuming jacket-
type foundations are used), and
the conclusion that grey and
harbour seals had a low
sensitivity to the installation of
these developments (with no
adverse effects predicted for the
Humber Estuary SAC and The
Wash and North Norfolk Coast.
With regards to the construction
of these projects potentially not
being coincident, the temporary
nature of the works and the low
usage of the area by grey and
harbour seals, even if the
construction was to coincide it is
unlikely an in-combination effect
in-combination
effects to result in
adverse effects
on the integrity of
the Humber
Estuary SAC.
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
the Wash and
North Norfolk
Coast SAC.
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Table 8.1: Potential for In-combination effects
Mechanism
for effect
Projects Potential In-combination effect Sites
resulting in adverse effect on
integrity would result.
Disturbance
from
activities
associated
with the
operation of
the
Offshore
Scheme.
Dogger
Bank
Creyke
Beck
project
Hornsea
Round 3
developm
ents
Operational effects (e.g. bird
collision and barrier effects) of the
Dogger Bank Creyke Beck and
the Hornsea Project One
developments were not regarded
to be significant at the population
level for species including
qualifying seabird species of the
Flamborough & Filey Coast pSPA
(Forewind 2013g, SMartWind
2013b). Analogous to the above
consideration, in view of the scale
of the NUI during its operation
and the above consideration in
relation to effects experienced in
relation to North Sea oil and gas
platforms, it is not regarded to
represent a significant
incremental source of effects for
seabirds such that population
level effects could occur.
There is no
potential for the
in-combination
effects to result in
adverse effects
on the integrity of
Flamborough
Head and
Bempton Cliffs
SPA and
Flamborough
Head and Filey
Coast pSPA.
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9.1.1 No adverse effects on the integrity of the Humber Estuary SAC (and associated
effects on the Humber Estuary SPA & Ramsar), Flamborough Head SAC,
Flamborugh Head and Bempton Cliffs SPA, Flamborough Head and Filey Coast
pSPA and the Wash and North Norfolk Coast SAC have been identified as a
result of the Offshore Scheme alone, or in-combination with other
developments.
9.1.2 With regards to coastal process this conclusion is based on the timing and
temporary nature of the works and the coastal and wider sediment dynamics
interpreted through a comprehensive review of relevant literature, informed by
previous experience of buried and surface laid pipelines in this region of the
southern North Sea which has been subject to considerable historic and recent
academic and development-led research, into which the Offshore Scheme has
been placed.
9.1.3 With regards to marine mammals this conclusion has been reached based on
the at sea usage of grey and harbour seals associated with the areas of
concern for installation and operation noise (i.e. NUI piling and seismic
monitoring at the storage site) are low, the mitigation to be employed in order to
avoid or minimise the potential residual effect on any seals (or other marine
mammals) which may be located within storage site area during the timing of
the works (e.g. soft-start, use of Passive Acoustic Monitoring (PAM) to augment
(for cetaceans) marine mammal observer information). For piling and seismic
activities, JNCC (2010a, b) guidelines will be followed to ensure “best practice”
for these activities. Additionally, individual geological survey consent will be
required and consulted upon, including with JNCC, prior to any such works
being undertaken.
9.1.4 With regards to seabirds this conclusion has been reach based on the localised
and transient nature of the works, the level of incremental activity taken in the
context of wider vessel traffic in the area, and the relative sensitivity of the
features to disturbance by the physical presence of vessels involved in the
activities is not considered to represent a significant source of effects on their
own, or in combination with the other relevant projects.
9.1.5 Integrity matrices which summarise the findings of this assessment are
presented in Appendix 11.9.1.
9 Conclusion
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