1. Introduction

1.1. Overview

SSE Renewables Developments (UK) Limited (“SSE Renewables” (SSER)) is proposing the development of the Berwick Bank Wind Farm (hereafter referred to as ‘the Project’). The Project includes both offshore and onshore infrastructure required to generate and transmit electricity from the Array Area to a landfall point on the East Lothian and Scottish Borders coast (at either Thorntonloch or Skateraw Harbour) and a Scottish Power Transmission (SPT) 400kV Grid Substation located at Branxton, southeast of Torness Power station. SSER is also considering an additional offshore export cable corridor (ECC), which is under development. The additional ECC does not form part of the Proposed Development for this LSE Screening Report. The Array Area is located in the outer Firth of Forth and Firth of Tay, 33.5 km east of the East Lothian and the Scottish Borders coastline (St Abb’s Head) from the nearest boundary and is the second project to be developed in the former Firth of Forth Zone (see Figure 1.1).
The initial Berwick Bank Wind Farm Proposal would have been one of two projects to be developed via Phase 2 of the former Firth of Forth Zone which included the initial Berwick Bank Wind Farm and Marr Bank Wind Farm. The initial Berwick Bank Wind Farm Proposal was proposed with a potential generating capacity of 2,300 MW and Marr Bank was due to have an approximate installed capacity of 1,850 MW. Marr Bank was to be located to the west of the initial Berwick Bank Wind Farm Proposal.
In October 2020, SSER consulted on a Habitats Regulations Appraisal (HRA) Screening Report for the initial Berwick Bank Wind Farm Proposal which was to be located approximately 39.2 km east of the East Lothian and Scottish Borders coastline from the nearest boundary with an array area of approximately 775 km2. Advice on LSE Screening (as it pertained to the initial Berwick Bank Wind Farm Proposal) was received by SSER on 11 May 2021 (hereafter, this consultation process is referred to as the ‘initial consultation’.
SSER subsequently undertook a detailed review of both the initial Berwick Bank and Marr Bank Wind Farm Proposal site environmental constraints and SSER has adjusted the consenting approach for the two Proposals and is now seeking consent for one Wind Farm Project: Berwick Bank Wind Farm. The offshore components seaward of mean high water springs (MHWS) of the Project are hereafter referred to as the Proposed Development. The boundary of the Proposed Development is a reduction of the combined boundaries of the initial Berwick Bank Proposed Development and Marr Bank Wind Farms. This revised Offshore HRA Screening Report has been developed for the Proposed Development and considers the new Proposed Development boundaries and updated Project Design Envelope (see section 3).
SSER will submit separate consents, licences and permissions for the offshore (seaward of Mean High Water Springs (MHWS) and onshore (landward of Mean Low Water Springs (MLWS)) infrastructure of the Project. A new Offshore EIA Scoping Report (SSE, 2021) has considered the Proposed Development.
The consents, licences and permissions that will be sought by SSER for the Proposed Development include:

a Section 36 consent under the Electricity Act 1989;
a marine licence under the Marine and Coastal Access Act (MCAA) 2009 for the generating assets located within the Array Area; and
a marine licence under the Marine and Coastal Access Act 2009 and the Marine (Scotland) Act 2010 for the transmission assets.

1.2. Habitats Regulations Appraisal

This document has been produced to inform the HRA process for the Proposed Development. It provides information to enable the screening of the Proposed Development with respect to its potential to have a likely significant effect (LSE) on designated nature conservation sites (hereafter ‘European sites’). The scope of this document covers all relevant European sites and relevant qualifying interest features seaward of MHWS, and potential impacts of offshore and intertidal infrastructure seaward of MHWS on onshore sites landward of MLWS. European sites are proposed to be “screened out” where no LSE from the Proposed Development is predicted. Where LSE cannot be ruled out at this stage the European sites will be “screened in” and assessed further.
The requirement and process for the consideration of potential impacts of plans and projects on European sites have followed the European Union’s (EU) Habitats Directive.[1] In Scottish territorial waters, the Habitats Directive was initially translated into specific legal obligations by the Conservation (Natural Habitats, &c.) Regulations 1994 (as amended) and the Conservation of Habitats and Species Regulations 2017 in respect of reserved matters. The Conservation of Offshore Marine Habitats and Species Regulations 2017 are also relevant in Scottish waters more than 12 nautical miles (nm) from land. These regulations are together referred to as the Habitats Regulations.
Following the United Kingdom’s (UK) departure from the EU on 31 December 2020 (EU-Exit), the UK is no longer an EU Member State. However, through the Conservation of Habitats and Species Amendment (EU Exit) Regulations 2019 (the “EU Exit Regulations”) the HRA process implemented under the Habitats Regulations continues to apply, subject only to minor changes. EU Exit-related changes to the Habitats Regulations are discussed in more detail in section 2. However, these changes are considered to have no material implications on the requirement or process for a HRA for the Berwick Bank Wind Farm. This report will hereafter refer to the ‘Habitats Regulations’ as including any changes enacted by the EU Exit Regulations.
The Habitats Regulations require that an HRA must be carried out on all plans and projects that are likely to have significant effects on European sites, which include Special Areas of Conservation (SACs), candidate SACs (cSACs), Sites of Community Importance (SCI), Special Protection Areas (SPAs) and as a matter of policy, possible SACs (pSACs), potential SPAs (pSPAs) and Ramsar Sites (listed under the Ramsar Convention on Wetlands of International Importance – where also designated as a European site).
In this report, and in accordance with EU Exit guidance issued by the Scottish Government the term “European site” has been retained to refer to the above sites protected in European Member States, Scotland and the rest of the UK (Scottish Government, 2020). However, where these sites are located in the UK, they now form part of the National Site Network. European sites are defined in full in section 2.1.36.
The European Commission’s (2018) guidance, identifies a staged process to the assessment of the effects of plans or projects on European sites:

Screening;
Appropriate Assessment;
Mitigation and alternatives; and
Imperative Reasons of Overriding Public Interest (IROPI).
1. The guidance on conducting HRAs in Scotland (SNH, 2015) states that the requirements for assessments of the effects of plans or projects on European sites can be broken down into nine stages as follows:

Deciding whether a plan should be subject to Habitats Regulations Appraisal
Identifying the European sites that should be considered in the appraisal
Gathering information about the European sites
Discretionary discussions on the method and scope of the appraisal
Screening the draft / proposed plan for likely significant effects
Applying mitigation measures at screening stage to avoid likely significant effects
Rescreen the plan and decide on the need for appropriate assessment
The ‘appropriate assessment’ - site integrity, conservation objectives, consideration of in-combination effects and the precautionary principle
Amending the plan until there would be no adverse effects on site integrity
Preparing a draft of the Habitats Regulations Appraisal Record
Consultation
Proposed modifications
Modifying and completing the appraisal record.

1.3. Habitats Regulations Appraisal to date

Advice on LSE Screening (as it pertained to the initial Berwick Bank Wind Farm Proposal) was received on 11 May 2021. The outcomes of this consultation are presented in section 1.7. This account of Screening for the Proposed Development builds upon the HRA Screening exercise completed in 2020 for the initial Berwick Bank Wind Farm Proposal and considers all responses received during consultation.
The Proposed Development is, however, considered afresh in this report as a proposal in its own right and information is provided herein to support the assessment of the specific proposals for the Berwick Bank Wind Farm as now proposed. The previous Advice on LSE Screening is only referred to where it is relevant to the details of the now proposed Berwick Bank Wind Farm. Where conclusions happen to be consistent with those made with respect to the initial Berwick Bank Wind Farm Proposals, these have been reached with detailed consideration to the Proposed Development, as well as relevant feedback. All distances informing connectivity (effect pathways) to HRA receptors have been taken from the edge of the revised boundary.
Further, this HRA Screening Report has been developed alongside the Proposed Development’s Scoping Report as part of the Environmental Impact Assessment (EIA) process. Where design or supporting information or stakeholder feedback is common to both assessments this has been used, as referenced. The Offshore EIA Scoping Report for Berwick Bank Offshore Wind Farm was submitted to Marine Scotland and shared with consultees in the October 2021 (SSE, 2021) ahead of this report.
A HRA ‘Change Report’ highlighting the material changes to Berwick Bank Wind Farm since the last HRA Screening information was provided in October 2020 can be made available on request but is not considered a material consideration to this HRA Screening report.

1.4. Purpose of this Report

This document provides the information to support screening for LSE required by the Habitats Regulations. It comprises the screening stage and therefore provides information to enable the screening of the Proposed Development with respect to its potential to have an LSE on European sites.
Potential impacts of onshore components of the Project on onshore sites landward of MHWS, are outside the scope of this LSE Screening report. However, any potential impacts from offshore effects that could impact receptors onshore will be considered in this report. Any impacts from effect-sources onshore on offshore receptors (such as seabirds utilising intertidal or coastal resources) will be considered in the onshore LSE Screening report. The onshore components of the Project will also be considered as part of an in-combination assessment where relevant, and is considered to be a reasonably foreseeable project. This assessment will account for both concurrent and additive effects of the Project on receptors that traverse on and offshore areas.
The screening exercise presented in this report is based on the current understanding of the baseline environment and proposed activities associated with the Proposed Development and is based on the project and site-specific information currently available. Any changes which may arise as a result of further environmental surveys, assessment work, consultee responses, Road Map process for the Proposed Development, and/or refinements to the design of the Proposed Development will be reflected in the RIAA, and/or subsequent HRA reporting.
In summary, the purpose of this report is:

to identify the relevant European sites which may include features (Annex I habitats, Annex I birds and Annex II species [2]) which may be sensitive or vulnerable to potential impacts arising from the construction, operation and maintenance and decommissioning of the Proposed Development;
to consider the features of the relevant European sites and to identify those which are not considered likely to be at risk of significant effects arising from the Proposed Development, either alone or in combination with other plans or projects, so that they can be eliminated from further consideration within the HRA process;
to consider the features of the relevant European sites and to identify those which are considered likely to be at risk of significant effects arising from the Proposed Development, either alone or in combination with other plans or projects, so that they can be taken forward for appropriate assessment; and
to consider which of the potential impacts arising from the Proposed Development are considered likely to result in LSEs to features of European sites and which impacts can be eliminated from consideration in further stages of the HRA [3].

1.5. Structure of this Report

This LSE screening report is set out in the following stages:

section 2 – a brief summary of the HRA process and legislative context including implications of the UK’s departure from the EU;
section 3 – a description of the key elements of the Proposed Development;
section 4 – the initial identification of sites and features which may potentially be affected by the Proposed Development;
section 5 – LSE screening tables and the determination of the potential for LSEs to arise with regard to the designated features of the European sites under consideration; and
section 6 – a summary of the European sites and features for which the screening process has identified potential for LSEs.

1.6. Project Overview

1.6.1. Firth of Forth Zone

The Round 3 offshore wind development programme was instigated by The Crown Estate (TCE) in 2008. Suitable areas for the development of offshore wind were assessed through a statutory process of Strategic Environmental Assessment (SEA) undertaken by Department of Energy and Climate Change (DECC), now Department for Business, Energy and Industrial Strategy (BEIS). As part of a competitive tender, Seagreen Wind Energy Limited (SWEL) was awarded the exclusive rights to the development of the Firth of Forth Zone by TCE in 2010. The subsequent Zone Development Agreement (ZDA) between Seagreen Wind Energy Ltd and TCE provides the potential for the development of several offshore wind farms. Subsequently in 2019, the Firth of Forth ZDA was terminated, with Agreement for Leases (AfLs) now agreed with Crown Estate Scotland (CES) for Seagreen (consisting of Seagreen Alpha and Seagreen Bravo), Berwick Bank and Marr Bank (now being development as a single project known as Berwick Bank Wind Farm).

1.6.2. Phase 1

Phase 1 within the former Firth of Forth Zone includes the development of two offshore wind farms: Seagreen Alpha and Seagreen Bravo (hereafter collectively referred to as Seagreen 1), located around 27 km from the Angus coastline (Figure 1.1), which have the potential combined capacity of up to 1,500 MWs. The offshore export cable for Seagreen 1 will make landfall at Carnoustie and connects to a substation at Tealing.
Offshore consent for Seagreen 1 was received in October 2014 from Scottish Ministers and was confirmed in November 2017 following a legal challenge by the Royal Society for the Protection of Birds (RSPB). A 15-year Contract for Difference (CfD) was awarded in September 2019 for 42% of the total project capacity (454 MW) and Seagreen 1 reached financial close in June 2020.

1.6.3. Phase 2

Phase 2 of the former Firth of Forth Zone included the Initial Berwick Bank Wind Farm Proposal and the superseded Marr Bank Wind Farm Proposal.

1.6.4. The Proposed Development

Introduction

The Proposed Development could include up to 307 wind turbines and all associated offshore and onshore infrastructure, although as outlined in section 1.1, this LSE Screening information considers only the offshore components (up to MHWS) of the Proposed Development (including onshore impacts of offshore infrastructure).
The Proposed Development Array Area (i.e. the area in which the wind turbines will be located) is approximately 1,314 km2 and is located approximately 33.5 km east of the East Lothian and Scottish Borders coastline from the nearest boundary (Figure 1.1). The Proposed Development Array Area is situated to the east of the large-scale morphological banks ‘Marr Bank’ and overlapping the ‘Berwick Bank’ in the south.
A maximum of 307 wind turbines will be installed in the Proposed Development Array Area, with either suction caisson jacket or piled jacket foundations proposed for the wind turbine foundations. There will be up to ten offshore substation platforms (OSPs) installed with piled jackets for the platform foundations. The wind turbines will connect to each other and to the OSP(s) via subsea inter-array cables, and the OSP(s) will be connected to other OSP(s) via interconnector cables.
Up to 12 offshore export cables will connect the OSP(s) to a landfall location on the East Lothian and Scottish Borders coast, either at Thorntonloch (hereafter referred to as ‘Thorntonloch Landfall’) or Skateraw Harbour (hereafter referred to as the ‘Skateraw Landfall’)’; see Figure 1.1. Once the cables make landfall, they will connect to the grid connection point at a new 400 kV Branxton substation, southwest of Torness Power station under an existing grid connection agreement.
The decommissioning process is likely to follow a similar programme to construction, in a reverse manner. SSER is seeking a 35-year consent period for operation of the Proposed Development.

Key Components of the Proposed Development

The key offshore components of the Proposed Development include:

wind turbines;
wind turbine foundations;
array cables;
interconnector cables;
offshore substation(s) platform(s); and
offshore export cable(s).
1. Further description of the key elements of the Proposed Development is provided in section 3.

Figure 11: Location of the Proposed Development within the Former Firth of Forth Zone

1.7. Relevant Consultations

The Initial consultation was undertaken with Marine Scotland Licensing Operations Team (MS-LOT), Marine Scotland Science (MSS) and Scottish Natural Heritage (SNH), acting under its operating name NatureScot (hereinafter referred to as NatureScot (NS)). Comments applicable to the LSE Screening for the Proposed Development have been taken into consideration in this LSE Screening Report. A summary of the details of the consultation undertaken to date is presented in Table 1.1 Open ▸ ; where consultees raised similar points, these have been grouped.

Table 1.1: Summary of Key Consultation on LSE Screening for the Proposed Development (Including Relevant Information from the Initial Berwick Bank Wind Farm Proposal LSE Screening Response)

2. Habitat Regulations Process

2.1. Legislative Context

The Habitats Directive (92/43/EEC), on the conservation of natural habitats and of wild fauna and flora, protects habitats and species of European nature conservation importance. Together with Council Directive (2009/147/EC) on the conservation of wild birds (the ‘Birds Directive’), the Directive provides the European Union’s legal framework for the protection of wild fauna and flora and birds.
The UK is no longer an EU Member State. Notwithstanding, the Habitats Directive (and transposing Habitats Regulations, as set out in section 1.2) continue to provide the legislative backdrop for HRA in the UK through the EU Exit Regulations. The HRA process implemented under the Habitats Regulations continues to apply (subject to minor changes effected by the EU Exit Regulations) and the UK is bound by HRA judgments handed down by The Court of Justice of the European Union (CJEU) prior 31 to December 2020 [4]. This document has therefore been drafted on the basis that all relevant HRA-related legislation remains in place and in accordance with Habitats Regulations that transposed the European requirements for HRA into UK law (see section 1.2) and as effected by the EU Exit Regulations (2019). The objective of the Habitats Regulations is to conserve, at a favourable conservation status (FCS), those habitats and species listed in Annexes I and II of the Habitats Directive and Annex I of the Wild Birds Directive. Post EU-Exit, the Habitats Regulations continue to refer to Annexes I and II of the Habitats Directive and Annex I of the Birds Directive and as such, reference is made to the annexes of the Habitats and Birds Directives in this report.

2.2. European sites Post EU Exit

The Europe-wide network of nature conservation areas that are the subject of the HRA process was established under the Habitats Directive. The Habitats Directive establishes a network of internationally important sites, designated for their ecological status. For EU member states (and traditionally for the UK), SACs are designated under the Habitats Directive and promote the protection of flora, fauna and habitats. SPAs are designated under the Birds Directive to protect rare, vulnerable and migratory birds. European sites located within an EU Member State combine to create a Europe-wide network of designated sites (the Natura 2000 network) and may be referred to as Natura 2000 Sites.
Following EU-Exit, European sites located within the UK are no longer part of the Natura 2000 network (nor Natura Sites) but instead combine to form the UK’s “National Site Network”. Hereafter, sites within the UK and the EU are both referred to as European sites. The National Site Network comprises of European sites in the UK that already existed (i.e., were established under the Nature Directives) on 31 December 2020 (or proposed to the EC before that date) and any new sites designated under the Habitats Regulations under an amended designation process.

2.3. The Process

Although the UK no longer has any obligations under the Nature Directives, the wording of Article 6(3) and 6(4) of the Habitats Directive underlies the sequential decision-making tests applied under the HRA process to plans or projects likely to affect European sites.
Neither the Habitats Directive, or the Habitats Regulations explicitly define the assessment process to be followed to test the potential effects of plans and projects on European sites. However. HRA is generally recognised as a progressive, four stage process built around the wording of Article 6(3) of the Habitats Directive, with the outcome at each stage defining the requirement for and scope of the next. Compliance with the requirements of the Directive can be demonstrated if the stages are followed in the correct and particular sequence. These stages are summarised in Figure 2.1.
This report considers the first ‘screening for LSE’ step in the HRA process which encompasses stages 1 to 3 in Figure 2.1.
The Habitat Regulations make it clear that the person applying for the consent of the plan or project must provide such information as the Competent Authority may reasonably require for the purposes of the assessment. It is intended that this report and the subsequent HRA reporting including the RIAA provides this information.
To determine whether an appropriate assessment is required it must first be ascertained whether or not the plan/project, directly connected with or necessary to the management of the site. As this is not the case for the Proposed Development, it must therefore be determined whether the plan or project, either alone or in-combination with other plans and projects, is likely to have a significant effect on a European site(s). This constitutes the LSE screening stage which removes from the assessment protected features of European sites which have no connectivity to the Proposed Development or those where the impacts are immaterial or inconsequential and the conservation objectives for the site’s qualifying interests would not be undermined (i.e. they are non-significant). All other European sites, including those where there is reasonable doubt as to the magnitude and nature of the relevant impact(s), are passed through to the next stage (appropriate assessment).
The 2019 Regulations establish management objectives for the national site network. These are called the network objectives [5]. The objectives in relation to the National Site Network are to:

i) maintain or restore certain habitats and species listed in the Habitats Directive to favourable conservation status (FCS); and
ii) contribute to ensuring the survival and reproduction of certain species of wild bird in their area of distribution and to maintaining their populations at levels which correspond to ecological, scientific and cultural requirements, while taking account of economic and recreational requirements.

Figure 21: Stages in the Habitats Regulations Appraisal Process (taken from SNH, 2015)

2.4. Process for Identifying European Sites and Features

To facilitate the identification of the European sites and features to be considered in the LSE screening for the Proposed Development, a pre-screening of sites has been undertaken. This is considered to be appropriate due to the large spatial scale of the Proposed Development, the wide ranging nature of many of the features of European sites which may be affected (i.e. birds and marine mammals) and therefore the number of European sites which could potentially be affected.
The criteria adopted for the initial identification of European sites are outlined in Table 2.1 Open ▸ . This approach takes account of the location of the European sites (including Ramsar Sites) in relation to the Proposed Development, the anticipated zone of influence (ZOI) of potential impacts associated with the Proposed Development, and the ecology and distribution of qualifying interest features.
Table 2.1 Open ▸ outlines the order of consideration given to the criteria used for the identification of the list of sites to be taken forward for determination of LSE. Initial consideration is given to whether there is a physical overlap between the Proposed Development and any European sites; all sites with an overlapping boundary are screened in to be taken forward for determination of LSE.
Pre-screening criterion 2 next identifies any European sites, not already screened in using criterion 1, where there is an overlap between the Proposed Development and the range of any qualifying mobile species of the site. All sites where the Proposed Development boundary overlaps with the range of one (or more) of its features, are taken forward for determination of LSE.
Criterion 3 identifies any European sites, not already screened in by criterion 1 or 2, where the potential ZOI of the Proposed Development overlaps with a European site and/or qualifying interests of the site (as per section 4). For ornithology receptors, consideration is also given to a range of factors that inform the likely extent to which the different qualifying features will occur on the Proposed Development site (e.g. scarcity of records of the relevant species during the baseline surveys (see section 4.4).

Table 2.1: Criteria for Initial Identification of Relevant European Sites

The outcome of this initial screening will be that sites where there is no potential for LSEs due to lack of potential overlap of receptor-impact pathway to occur are excluded from further consideration in this report. Sites not excluded on the basis of any of the criteria outlined in Table 2.1 Open ▸ (i.e. where there is a potential for a receptor-impact pathway to occur) will be taken forward for determination of LSE in section 5.

3. Project description

3.1. Introduction

This section of the Berwick Bank LSE Screening Report provides an outline description of the Proposed Development and describes the activities likely to be associated with the construction, operation, and maintenance, and decommissioning of the Proposed Development. It summarises the design and components of the Proposed Development infrastructure, based on conceptual design information and refinement of the Proposed Development parameters following receipt of the Offshore EIA Scoping Opinion for the initial Berwick Bank Wind Farm Proposal, and understanding of the environment from site specific survey and desk-top analysis.
The Project Design Envelope (PDE) approach (also known as the Rochdale Envelope approach) will be adopted for the assessment of the Proposed Development, in accordance with current good practice and the “Rochdale Envelope Principle”. The PDE concept allows for some flexibility in project design options, particularly for foundations and wind turbine type, where the full details of a project are not known at application submission.
The Proposed Development is located 33.5 km offshore of the East Lothian and Scottish Borders coastline and within the south eastern extent the former Firth of Forth Zone. The Proposed Development array area comprises an area of approximately 1,341 km2.
Up to twelve offshore export cables will connect the OSP(s) to landfall at one selected landfall location on the East Lothian. Two are being considered, one at Thorntonloch (hereafter referred to as ‘Thorntonloch Landfall’) and one at Skateraw Harbour (hereafter referred to as the ‘Skateraw Landfall’)’. Once the cables make landfall, they will connect to the grid connection point at a new 400 kV Branxton substation, southwest of Torness Power station under an existing grid connection agreement. A potential offshore Export Cable Corridor (ECC) has also been identified as shown in Figure 1.1.

3.2. Proposed Boundary

An AfL allows SSER to carry out investigations, such as survey activities, to identify the potential design within the Proposed Development Array Area for the wind farm by understanding environmental sensitivities that may exist, in advance of submitting the consent application. The Proposed Development Array Area includes the majority of the previous Marr Bank Wind Farm and initial Berwick Bank Wind Farm AfL areas.
The Proposed Development Array Area is the area within which the offshore infrastructure, such as the wind turbines, offshore substation(s), array cables and the start of the proposed ECC will be located.
The Proposed Development offshore ECC has been identified and will connect the Proposed Development Array Area to the Thorntonloch Landfall or Skateraw Landfall.
The Proposed Development boundary is illustrated within Figure 1.1. This area encompasses the:

Array Area: This is where the offshore wind farm will be located, which will include the wind turbines, wind turbine foundations, array cables, and a range of offshore substations and offshore interconnector cables; and
ECC: This is where the offshore electrical infrastructure, such as the offshore export cable(s), will be located.

3.3. Offshore Infrastructure

The key offshore components of the Proposed Development are likely to include:

up to 307 wind turbines (each comprising a tower section, nacelle and three rotor blades) and associated support structures and foundations);
up to ten OSPs and associated support structures and foundations;
estimated scour protection of 2 km2);
a network of inter-array cabling linking the individual wind turbines to each other and to the OSPs, plus inter-connections between substations (approximately 1,225 km of array cabling and 94 km of interconnector cabling); and
up to twelve offshore export cables connecting the offshore substation(s) to the onshore substation.

3.3.2. Wind Turbines

The Proposed Development will be comprised of up to 307 wind turbines, and the final number of wind turbines will be dependent on the capacity of individual wind turbines used and also environmental and engineering survey results. There is the potential for a reduced number of wind turbines to be used if an increased output of wind turbine model is selected when the final project design is developed.
The maximum rotor blade diameter is expected to be no greater than 310 m, with a maximum blade tip height of 355 m above Lowest Astronomical Tide (LAT) and a minimum blade tip height of 37 m above LAT. The top of the wind turbines (the nacelle) will be approximately 200 m above LAT. A scheme for wind turbine lighting and navigation marking will be agreed with consultees post-application. The minimum distance between the bottom of the blade and the water surface will be 37 m.
The layout of the wind turbines will be developed to best utilise both the available wind resource and suitability of seabed conditions, while ensuring environmental effects and impacts on other marine users (such as fisheries and shipping routes) are minimised. The final layout of the wind turbine array will be confirmed at the final design stage (post-application).
The maximum design scenario for wind turbines is presented in Table 3.1 Open ▸ .

Table 3.1: Design Envelope for Wind Turbines

3.3.3. Wind Turbine Foundations and Support Structures

The wind turbines will be fixed to the seabed by foundation structures. To allow for flexibility in foundation choice, two wind turbine support structures and foundations are being considered for the Proposed Development - piled jacket and suction caisson jacket.
There is the potential for seabed preparation to be required for each foundation type, which may include seabed levelling and removing surface and subsurface debris such as (for example) boulders, fishing nets, unexploded ordnance or lost anchors. Excavation may be required to access and remove any debris which is present below the seabed surface.
Foundations will be fabricated off-site, stored at a suitable port facility (if required) and transported to site as needed. Specialist vessels will be needed to transport and install foundations. Scour protection (typically rock) may be required on the seabed and will be installed either before and/or after foundation installation.
All foundation types and maximum parameters stated in the following section are for wind turbines only; foundation structures for OSPs are discussed in section 3.3.5.

Piled Jacket Foundations

Piled jacket foundations are formed of a steel lattice construction (comprising tubular steel members and welded joints) secured to the seabed by driven and/or drilled pin piles attached to the jacket feet. The hollow steel pin piles are typically driven or drilled into the seabed relying on the frictional and end bearing properties of the seabed for support.
The maximum design scenario for piled jacket foundations with pin piles is shown in Table 3.2 Open ▸ .

Table 3.2: Design Envelope for Jacket Foundation with Pin Piles

Suction Caisson Jacket Foundations

Suction caisson jacket foundations are formed with a steel lattice construction (comprising tubular steel members and welded joints) fixed to the seabed by suction caissons installed below each leg of the jacket. The suction caissons are typically hollow steel cylinders, capped at the upper end, which are fitted underneath the legs of the jacket structure. They do not require a hammer or drill for installation.
The foundations will be transported to site via sea. Once at site, the jacket foundation will be lifted by the installation vessel using a crane and lowered towards the seabed in a controlled manner. When the steel caisson reaches the seabed, a pipe running up through the stem above each caisson will suck water out of each bucket. The buckets are pressed down into the seabed by the resulting suction force. When the bucket has penetrated the seabed to the desired depth, the pump is turned off. A thin layer of grout is then injected under the bucket to fill the air gap and ensure contact between the soil within the bucket, and the top of the bucket itself.
The maximum design scenario for jacket foundations with suction caissons is provided in Table 3.3 Open ▸ .

Table 3.3: Design Envelope for Suction Caisson Jacket Foundations

3.3.4. Scour Protection for Foundations

Foundation structures for wind turbines and substations are at risk of seabed erosion and ‘scour hole’ formation due to natural hydrodynamic and sedimentary processes. The development of scour holes is influenced by the shape of the foundation structure, seabed sedimentology and site specific metocean conditions such as waves, currents and storms. Scour protection may be employed to mitigate scour around foundations. There are several commonly used scour protection types, such as:

concrete mattresses: several metres wide and long, cast of articulated concrete blocks which are linked by a polypropylene rope lattice which are placed on and/or around structures to stabilise the seabed and inhibit erosion;
rock placement: either layers of graded stones placed on and/or around structures to inhibit erosion or rock filled mesh fibre bags which adopt the shape of the seabed/structure as they are lowered on to it; or
artificial fronds: mats typically several metres wide and long, composed of continuous lines of overlapping buoyant polypropylene fronds that create a drag barrier which prevents sediment in their vicinity being transported away. The frond lines are secured to a polyester webbing mesh base that is itself secured to the seabed by a weighted perimeter or anchors pre-attached to the mesh base.
1. The most frequently used scour protection method is ‘rock placement’, which entails the placement of large quantities of crushed rock around the base of the foundation structure.
2. The amount of scour protection required will vary for the different foundation types being considered for the Proposed Development. The final choice of scour protection will be made after design of the foundation structure, taking into account a range of aspects including geotechnical data, meteorological and oceanographical data, water depth, foundation type, maintenance strategy and cost.

3.3.5. Offshore Platforms

The Proposed Development may require up to a total of ten offshore platforms. These offshore platforms will be utilised as OSPs which transform electricity generated by the wind turbines to a higher voltage, thereby allowing the power to be efficiently transmitted to shore. The size of the platform topsides will depend on the final electrical set up for the wind farm but could range between 35 – 100 m (length) by 27 – 80 m (width), and approximately 45 – 80 m in height (above LAT), excluding the helideck or lightning protection.
The platform locations have not yet been selected and will be identified through detailed design consideration. The offshore platforms will be installed with piled jacket foundations.
The maximum design scenario for the offshore platforms is described in Table 3.4 Open ▸ .

Table 3.4: Design Envelope for Offshore Platforms

Offshore Platform Foundations: Piled Jacket

A description of piled jacket foundations, such as those which will be used for offshore platforms, is provided earlier in this section for wind turbines (see section 3.3.3). The maximum design scenario for jacket foundations with pin piles for offshore platforms is shown in Table 3.5 Open ▸ .

Table 3.5: Design Envelope for Jacket Foundations with Pin Piles for Offshore Platforms

Previous part

Next part

Tables ▼