11 - abode group

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

Shadow Appropriate Assessment:

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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


6.5 Flamborough Head SAC 49


6.6 The Wash and North Norfolk Coast SAC 51


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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Potential source of

likely significant

effect


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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Potential source of

likely significant

effect


-

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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2010)

Guillemot


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2010)

Razorbill


Document 11.9

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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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Sources of

effect

Mechanism for

effect

Natura 2000

sites


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


Coastal lagoons

Salicornia and other

annuals colonising mud

and sand

Atlantic salt meadows

(Glauco-Puccinellietalia

maritimae)


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Sources of

effect

Mechanism for

effect

Natura 2000

sites



Shifting dunes along the

shoreline with Ammophila


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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Sources of

effect

Mechanism for

effect

Natura 2000

sites


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


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


grypus



The Wash

and North

Norfolk Coast

SAC

Harbour seal phoca

vitulina


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Sources of

effect

Mechanism for

effect

Natura 2000

sites


monitoring. Flamborough

Head and

Bempton

Cliffs SPA


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


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

http://jncc.defra.gov.uk/protectedsites/sacselection/habitat.asp?FeatureIntCode=H1140


http://jncc.defra.gov.uk/default.aspx?page=1996


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Estuary SAC


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)


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


qualifying species;

The supporting processes

on which qualifying natural


qualifying species rely;

The populations of

qualifying species;

The distribution of

qualifying species within

the site.


of the Humber Estuary SPA.


Estuary SPA


Article 4.1 Qualification (79/409/EEC)

during the breeding season the area

regularly supports:


habitats of the qualifying

features, and the significant

disturbance of the qualifying















http://jncc.defra.gov.uk/protectedsites/sacselection/species.asp?FeatureIntCode=S1095




Document 11.9

44



Estuary SPA


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


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.



The extent and distribution

of the habitats of the

qualifying features;


of the habitats of the


The supporting processes

on which the habitats of

the qualifying features rely;

The populations of the


The distribution of the

qualifying features within

the site.


Document 11.9

45



Estuary SPA



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.


Document 11.9

46




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


Document 11.9

47




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


of Flamborough Head and Bempton Cliffs SPA.

Table 6.4 Qualifying Species and Conservation Objectives of

Flamborough Head and Bempton Cliffs SPA.


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





features, ensuring the integrity of

the site is maintained and the site

makes a full contribution to

achieving the aims of the Birds

Directive.


4 http://jncc.defra.gov.uk/default.aspx?page=1995


Document 11.9

48



Flamborough Head and Bempton Cliffs SPA.


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.


The extent and distribution of

the habitats of the qualifying

features;

The structure and function of


features;

The supporting processes on

which the habitats of the

qualifying features rely;




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.


6.4.2 Table 6.5 below sets out the Qualifying Species and Conservation Objectives.





the Directive (79/409/EEC) for

supporting over 1% of the





Document 11.9

49





biogeogrpahical population of four

regulary occurring migratory

species:

Black-legged kittiwake Rissa

tridactyla

Northern gannet Morus bassanus

Common guillemot Uria aalge

Razorbill Alca torda


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


features, ensuring the integrity of

the site is maintained and the site

makes a full contribution to

achieving the aims of the Birds

Directive.





features;



features;


which the habitats of the

qualifying features rely;




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


Document 11.9

50


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.








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;


qualifying natural habitats



Document 11.9

51





(including typical species) of

qualifying natural habitats,

and


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


Document 11.9

52


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.



Table 6.7 Qualifying Species and Conservation Objectives of the Wash

and North Norfolk Coast SAC




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;



and habitats of qualifying

species


(including typical species) of



the habitats of qualifying

species


Document 11.9

53


Table 6.7 Qualifying Species and Conservation Objectives of the Wash

and North Norfolk Coast SAC


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


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.


Document 11.9

54


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)


Document 11.9

55


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).


Document 11.9

56


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


Document 11.9

57


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


Document 11.9

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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


Document 11.9

59


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


Document 11.9

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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


Coastal lagoons

Salicornia and other annuals colonising mud and

sand

Atlantic salt meadows (Glauco-Puccinellietalia

maritimae)


Shifting dunes along the shoreline with Ammophila


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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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




Estuaries

Mudflats and sandflats not covered by seawater at

low tide

Sandbanks which are slightly covered by sea


Coastal lagoons

Salicornia and other annuals colonising mud and

sand

Atlantic salt meadows (Glauco-Puccinellietalia

maritimae)


Shifting dunes along the shoreline with Ammophila


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


integrity.


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74




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


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


Document 11.9

75




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


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


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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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


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




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


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


Use of rock armouring

potentially interfering

with coastal process




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


integrity.


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Table 7.4: Flamborough Head and Bempton Cliffs SPA Potential for Adverse Effect on Site 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.


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.



pipeline and NUI



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


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


associated with the

operation of the

Offshore Scheme.


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


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


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


integrity.


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Table 7.5: Flamborough Head and Filey Coast pSPA Potential for Adverse Effect on Site 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.


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.



pipeline and NUI


Black-legged kittiwake rissa tridactyla

Northern gannet morus bassanus

Common guillemot uria aalge


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



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Table 7.5: Flamborough Head and Filey Coast pSPA Potential for Adverse Effect on Site 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


associated with the

operation of the

Offshore Scheme.

Black-legged kittiwake rissa tridactyla

Northern gannet morus bassanus

Common guillemot uria aalge


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



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


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


integrity.


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Table 7.6: The Wash and North Norfolk Coast SAC Potential for Adverse Effect on Site 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.



pipeline and NUI


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


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


With regards to drilling activities, available measurements indicate that drilling


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84




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


Disturbance from


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


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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85




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



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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


Document 11.9

89



Mechanism

for effect


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.


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


adverse effects

on the integrity of

the Humber

Estuary SAC.


Document 11.9

90



Mechanism

for effect


(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


adverse effects

on the integrity of

the Humber

Estuary SAC.

There is no

potential for the

in-combination


adverse effects

on the integrity of


Document 11.9

91



Mechanism

for effect


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


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


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


Document 11.9

92



Mechanism

for effect


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


adverse effects

on the integrity of

the Humber

Estuary SAC.

There is no

potential for the

in-combination


adverse effects

on the integrity of

the Wash and

North Norfolk

Coast SAC.


Document 11.9

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Mechanism

for effect


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


adverse effects

on the integrity of

Flamborough

Head and

Bempton Cliffs

SPA and

Flamborough

Head and Filey

Coast pSPA.


Document 11.9

94


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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