Approach to assessment of significance

  1. Within the Array EIA Report, effects will be assessed as ‘significant’ or ‘non-significant’. A significant effect is defined as a level of effect of equal to or greater than ‘moderate’. A non-significant effect is considered as a level of effect of ‘minor’ or less. In the decision-making process, effects of moderate significance or above are considered important, whereas effects of minor significance or less are considered to have little, if any, importance.
  2. The general approach described in the Design Manual for Roads and Bridges (DMRB) (Highways England et al., 2019) and Environmental Impact Assessment for Offshore Renewable Energy Projects – Guide (BSI, 2015) has been considered as part of this matrix approach. However, several modifications have been made with regard to proportionality, including:
  • where a magnitude of impact is determined as ‘no change’ no assessment will be undertaken since it will always lead to a non-significant effect;
  • where a magnitude of impact is determined as ‘negligible’, this will not be considered further as it will always lead to a non-significant effect, even if more than one negligible magnitude impact was being considered cumulatively; and
  • where it is determined that a receptor or receptor group has negligible importance, value or sensitivity, this will not be considered further as it will always lead to a non-significant effect.
  1. The Array EIA Report will follow a “feedback loop” methodology, as shown in Figure 4.3   Open ▸ . Using this methodology, an impact is initially assessed to determine the significance of the environmental effect. If the effect of an impact is initially determined to have a major significant adverse outcome, primary and tertiary mitigation will be applied in order to reduce or offset the magnitude of impact, for example, through changes to the Array design parameters. Secondary mitigation such as engineering controls or construction methods will be employed, where possible, if the effect of an impact is initially determined to have a moderately significant adverse outcome, again, to reduce or offset the magnitude of the impact.
  2. As illustrated within Figure 4.3   Open ▸ , the EIA practitioner will repeat this process until they are content that:
  • the effect is reduced to a level that is not significant in EIA terms; or
  • no further changes can be made to the Array design parameters to reduce the magnitude of impact and the significance of the effect. An overall effect that is still significant in EIA terms may be presented in these instances.
  1. Using this iterative approach, it can be presumed that the significance of effect presented for each identified impact is representative of the maximum residual adverse effect the Array may have on the receiving environment.
  2. Appendix 2 presents all designed in measures considered in this Scoping Report. The development of mitigation measures will continue as the EIA progresses and in response to stakeholder engagement. An iterative process will be used for any additional measures and the dSEP will be updated (Appendix 1).

4.3.6. Inter-Related EffectsInter-Related Effects

  1. Where there are relationships between EIA topics which may lead to environmental effects, these are referred to as inter-related effects. There are two categories of inter-related effects:
  • project lifetime effects: additive effect of individual impacts on each of the key receptor groups across the three Array phases (construction, operation and maintenance and decommissioning); and
  • receptor-led effects: additive effect of multiple effects of the Array on the same receptor. For example, multiple effects on a given receptor such as benthic habitats (e.g. direct habitat loss or disturbance, sediment plumes, scour, jack-up vessel use etc.) may interact to produce a different or greater effect on this receptor than when the effects are considered in isolation. Receptor-led effects might be short term, temporary or transient effects, or incorporate longer term effects.
  1. The proposed approach to the inter-related effects assessment is that this will not assess every individual receptor assessed at the EIA stage, but instead, potentially sensitive groups of receptors, therefore, the term ‘receptor groups’ has been used to refer to this. It is anticipated that three main receptor groups will be assessed which can be categorised as the physical environment, biological environment and the human environment. The biological environment, for example, would encompass and assess the inter-related effects associated with benthic subtidal ecology, fish and shellfish ecology, marine mammals and offshore ornithology.
  2. Inter-related effects on each receptor or receptor group will be assessed as follows:
  • the topic chapters of the Array EIA Report will be reviewed to identify receptors or receptor groups which will require assessment, as well as the likely effects on each receptor or receptor group; and
  • an assessment will be undertaken into how the combination of individual effects may create inter-related effects on each receptor or receptor group for both project lifetime effects and receptor-led effects. A conclusion will then be determined on likely significant inter-related effects.
  1. If the significance of an effect has been identified as negligible across all stages of the project within the topic-specific assessment, it is assumed that these effects can not contribute to any lifetime inter-related effects. Therefore, these will not be included in the inter-related effects assessment as it is predicted that the effect will be negligible over the lifetime of the project.
  2. It should be noted that the inter-related effects assessment only considers the effects from the Array, with effects from other projects considered within the CEA (see section 4.3.7).

Figure 4.3:
Proposed Iterative Approach to Mitigation Within the Array EIA Report

Figure 4.3: Proposed Iterative Approach to Mitigation Within the Array EIA Report

 

4.3.7. Cumulative Effects AssessmentCumulative Effects Assessment

                        Overview

  1. Under the EIA Regulations, a CEA is legally required. The CEA considers the impacts arising from the Array alone as well as cumulatively with other relevant plans, projects and activities, and can be defined as the combined effect of the Array in combination with the effects from a number of different projects, on the same receptor or resource.
  2. The CEA is essential to identify foreseeable developments or activities with which the Array may interact, resulting in cumulative impact. Cumulative impacts may arise from all phases (construction, operation and maintenance, and decommissioning) of the Array.
  3. The Marine Scotland (2018) Consenting and Licensing Guidance: For Offshore Wind, Wave and Tidal energy Applications states that “Engagement with MS-LOT is required to identify which plans/projects/on-going activities should be included in the in-combination element of the cumulative effects assessment (CEA)”’. The CEA will consider offshore wind projects in the east of Scotland region, and other developments including those which are:
  • already constructed;
  • under construction;
  • permitted application(s) not yet determined; and
  • plans and projects which are “reasonably foreseeable” (i.e. developments that are being planned, including, for example, offshore renewable energy project which have a CES Option to Lease Agreement or Crown Estate equivalent, offshore renewable energy projects that have been scoped).
  1. In addition, the Proposed offshore export cable corridor(s) and Proposed onshore export cable corridor(s) (including the onshore substation at the Proposed landfall location(s)) will be considered within the CEA, as well as other ScotWind projects located in the vicinity of the Array which fall into the criteria listed above.
Screening stage
  1. An initial ‘long list’ of projects within a defined Zone of Influence (ZoI) will be developed based on the criteria listed in paragraph 201 to identify all potential projects to be considered in the CEA. The ZoI will encompass all regional study areas as defined in the technical assessments in the Array EIA Report.
  2. The following staged process will be used for each impact-receptor pathway to reduce the initial long list:
  • conceptual overlap – an impact-receptor pathway (in EIA terms) describes an impact which has the potential to directly or indirectly affect the receptor(s) in question. This is defined here as a conceptual overlap;
  • physical overlap – ability for impacts arising from the Array to overlap with those from other projects/plans on a receptor basis. An overlap of the physical extents of the impacts arising from the two (or more) projects/plans must be established for a cumulative effect to arise. There are exceptions to this for certain mobile receptors that may move between, and are subject to, two or more separate physical extents of impact from two or more projects; and
  • temporal overlap – for a cumulative effect to arise from two or more projects, a temporal overlap of impacts arising from each must be established. Some impacts are active only during certain phases of development (e.g. piling noise during construction). However, the absence of a strict overlap may not necessarily mean there is no potential for cumulative effect, as receptors may become further affected by additional, non-temporally overlapping projects.
  1. Experienced and knowledgeable technical specialists will carry out this screening stage based upon the current guidance and regulations. After review of the long list, the remaining projects or plans are taken forward to the assessment stage. This refined short list of projects will be agreed with stakeholders and Scottish Ministers via MS-LOT.
Assessment stage
  1. At the assessment stage, information is gathered on the projects, plans or activities, to be taken forward into the CEA. Where the likely significant effects (as defined by the EIA Regulations) for the Array alone are assessed as negligible, or where an impact is predicted to be highly localised, these will not be considered within the Array CEA, as it is considered that there would be no potential for cumulative effects with other plans, projects or activities.
  2. A tiered approach will be used when undertaking the CEA of the Array, which provides a framework for placing relative weight upon the potential for each project/plan to be included in the CEA, based upon the project/plan’s current stage of maturity and certainty in the projects’ parameters. Projects or plans will be assessed using the following tiers:
  • tier 1 assessment – Array with Proposed offshore export cable corridor(s), Proposed onshore export cable corridor(s), and Proposed landfall location(s) (NB: tiers will be assigned to these projects in the Array EIA Report based upon the information available prior to the cut-offs presented in paragraph 207);
  • tier 2 assessment – all plans/projects assessed under Tier 1, plus projects which are operational, under construction, those with consent and submitted but not yet determined;
  • tier 3 assessment – all plans/projects assessed under Tier 2, plus those projects with a Scoping Report and/or Scoping Opinion; and
  • tier 4 assessment – all plans/projects assessed under Tier 3, plus those projects likely to come forward where a CES Option to Lease Agreement or Crown Estate equivalent has been granted.
  1. The tiered approach above will be applied to all projects/plans that have been screened into the CEA via the screening process for assessment in the CEA. All other relevant plans, projects and activities that are publicly available six months prior to submission of the Array application will be considered in the CEA where quantitative assessment is required. A qualitative CEA will consider all other relevant plans, projects and activities that are publicly available three months prior to submission of the Array application.
  2. The CEA methodology will follow the methodology described in section 4.3.5, where possible, for consistency throughout the EIA.
  3. It is expected that the following activity types will be considered in the CEA of the Array based on maximum ZoIs identified from the relevant technical assessments detailed within this Scoping Report:
  • marine aggregates and disposal –200 km from the Array;
  • energy (including offshore wind, wave and tidal projects (including Innovation and Targeted Oil and Gas (INTOG) projects), cables, Carbon Capture and Storage (CCS) and Underground Coal Gasification (UCG)) – proposed ZoI subject to further assessment of offshore ornithology aerial survey study area);
  • oil and gas infrastructure –200 km from the Array;
  • cables and pipelines –100 km from the Array;
  • ports and harbours, 200 km from the Array; and
  • military, aviation and radar –50 km from the Array.
  1. The Applicant will seek agreement on the list of projects and/or plans to be included in the CEA as part of the post-Scoping consultation (see Appendix 1).

4.3.8. Transboundary EffectsTransboundary Effects

  1. Where impacts from the Array affects the environment of an EEA state(s), this is defined as a transboundary effect. The United Nations Economic Commission for Europe Convention on EIA in a Transboundary Context (the ‘Espoo Convention’) presents the need to consider transboundary effects and requires assessments to be extended across borders between Parties of the Convention when a planned activity may cause significant adverse transboundary impacts.
  2. The EIA Regulations state that the Scottish Ministers are required to send information about the development to the Government of the affected country for any project that is likely to cause significant transboundary effects and invite them to participate in consultation procedures. Appendix 3 presents the screening of potential transboundary impacts to assist with this process.
  3. The following receptors may experience transboundary impacts from the Array as identified in Appendix 3:
  • offshore ornithology;
  • commercial fisheries;
  • shipping and navigation; and
  • offshore socio-economics.

 

5.1. Physical ProcessesPhysical Processes

5.1.1. IntroductionIntroduction

  1. This section of this Scoping Report presents the relevant physical processes aspects to the Array and considers the scope of assessment on physical processes from the construction, operation and maintenance, and decommissioning of the Array.
  2. Physical processes are defined as encompassing the following elements for the purposes of this Scoping Report and subsequent Array EIA Report:
  • bathymetry;
  • wind and waves;
  • tidal currents and elevation;
  • seabed substrate and geology;
  • suspended sediments; and
  • sediment transport (which is influenced by the elements listed above).
  1. Throughout the remainder of this Scoping Report, the elements listed above are collectively referred to as ‘physical processes’.

5.1.2. Study AreaStudy Area

  1. The physical processes study area encompasses the site boundary (i.e. the area within which the Array will be located), including the seabed that may be influenced by changes to physical processes due to the Array to the extent of one spring tidal excursion. One spring tidal excursion is defined as the distance suspended sediment is transported prior to being carried back on the returning tide, this will be identified using numerical modelling techniques. This modelled tidal excursion will also be used to inform other chapters of the Array EIA Report (e.g. benthic subtidal ecology, fish and shellfish ecology, marine mammals, etc.).
  2. From published Admiralty data and preliminary modelling results, a tidal excursion of 8 km has been determined, which will not extend to the nearest designated area which is over 25 km away.

5.1.3. Baseline EnvironmentBaseline Environment

  1. The physical processes baseline has been compiled through a thorough review of desktop sources and site-specific survey data. A concise summary of the baseline environment is presented here, reference should be made to Appendix 5 for further detail.

Bathymetry

  1. Geophysical data collected in 2022 suggests that the water depth within the site boundary ranges between 63.82 m and 88.66 m relative to LAT. The seafloor consists of gentle slopes and generally deepens towards the east (Appendix 5, Apx Figure 5.1   Open ▸ ). These gentle seafloor gradients range from 0 to 5, with numerous localised steeper areas observed within ripple areas and flanks of rippled scour depressions. Larger sediment features generally run in a direction from north to south, while smaller sediment features run in a more east to west direction.

                        Wind and waves

  1. Metocean and Light Detection and Ranging (LiDAR) buoys were deployed within the site boundary in August 2022. The Metocean buoy will and the LiDAR buoys  will collect physical processes data until autumn 2023 and Autumn 2024 respectively. In the absence of site-specific data, metocean data collected from the Round 3 Firth of Forth Zone, in the vicinity of the site boundary, has been used to characterise the physical processes baseline for the wave regime and tidal currents and elevation. These eight metocean buoys were deployed within the Round 3 Firth of Forth Zone, with the nearest buoys approximately 57 km from the site boundary, with others further inshore towards the Firth of Forth. In the Round 3 Firth of Forth Zone during the stormiest event over the 18-month wave buoy deployment, in January 2012, a significant wave height of 6.7 m was recorded which correlates with a 1 in 1 year sea wave climate return period event (Fugro, 2012). Peak spectral wave periods of up to 20 s were recorded, both associated with strong winds and storms that are characteristic of the North Sea, (Royal Haskoning DHV, 2012). Although this data is now somewhat dated, it is considered sufficient at characterising the wind and wave regime across the Array due to the absence of more recent data and the site-specific data. It is unlikely that the site-specific data will vary significantly in the intervening period. Similarly, the Marine Scotland National Marine Plan Interactive (NMPi) maps presented annual mean wave power ranges from 14 kW/m to 19 kW/m and annual mean significant wave height ranges from 1.81 m to 2.10 m within the site boundary (Marine Scotland, 2022a).

                        Tidal currents and elevation

  1. Metocean surveys conducted across the nearby Round 3 Firth of Forth zone provided an overview of tidal current flows in the vicinity of the site boundary, in the absence of site-specific data, which was unavailable at the time of writing. A maximum current of 0.91 m/s was recorded in April 2011 within the Seagreen 1 (formerly known as Segreen Alpha and Bravo) Offshore Wind Farm (50.72 km from the site boundary). Elsewhere in the Round 3 Firth of Forth Zone, the current speed ranged from 0.68 m/s to 0.88 m/s (Fugro, 2012, Royal Haskoning DHV, 2012).
  2. The Marine Scotland NMPi maps provided an overview of the tidal flows within the site boundary, illustrating that the mean spring tidal range varies from 1.1 m to 3 m (Marine Scotland, 2022a).

                        Geology

  1. The site boundary is part of a complex glacial system, in which the subsequent sedimentary depositions in the Quaternary sediments are affected by the alternating glacial and interglacial stages that affected the northern hemisphere. The ground model was defined from 2D Ultra High Resolution Seismic (UHRS) and Sub-Bottom Profiler (SBP) data integrated with bathymetric, backscatter and Sidescan Sonar (SSS) data that was collected in 2022. Ocean Infinity (2022a) states that “A total of five geological units were identified, with a total of five interpreted horizons, aided interpretation through the delineation of localised geological features”.
  2. Within the site boundary, the published British Geological Survey (BGS) mapping (Stoker and Bent, 1985; Gatliff et al., 1994) indicates that the Quaternary geology will comprise of the Forth Formation (late Weichselian to Holocene, fluviomarine mud and sand), cutting into the Marr Bank Formation (Pleistocene, glaciomarine sandy silty clay) and the Aberdeen Ground Formation (Pleistocene, hard clay).
  3. The geological morphology within the site boundary is varied and includes recent marine soft sediment deposits and deep channel structures (down to 60 m) with sedimentary infill.

                        Seabed substrate

  1. The recent geophysical surveys identified that the seabed within the site boundary consists primarily of sand, with some areas of gravel and occasional diamicton (poorly sorted mixed sediments; Appendix 5, Apx Figure 5.2   Open ▸ ). Gravel areas are more frequent in the north-west, with occasional diamicton also observed in this area. The seabed within the site boundary is relatively flat, with a general slope towards the east. The presence of megaripples and sand waves across the site boundary indicates mobile sediments. The presence of furrows indicates sedimental erosion ( Figure 5.1   Open ▸ ).
  2. Occasional boulder fields (5 to 20 boulders within a maximum area of 2,500 m2) and numerous boulder fields (≥ 20 boulders within a maximum area of 2,500 m2) are distributed across the site boundary, most frequently in the west, within areas of gravel and diamicton (Appendix 5, Apx Figure 5.2   Open ▸ ). Manmade seafloor features are present across the site boundary, with linear debris (such as wire and rope) observed most frequently, and occasional linear scars or trawl marks are present (due to anthropogenic activity, such as trawling) as illustrated in Figure 5.1   Open ▸ .
  3. Due to the presence of large homogenous areas of sand, and the absence of rapid variation between substrates and pockets of sand, the substrate within the site boundary is not classified as a sensitive receptor. Receptor in this Scoping Report refers to physical features that are sensitive to potential impacts of the Array and/or are qualifying features of designated sites. The closest physical processes receptor to the Array is the Firth of Forth Banks Complex Marine Protected Area (MPA), which is detailed further in paragraph 234 below.

                        Suspended sediment and sediment transport

  1. The spatial distribution of average non-algal Suspended Particulate Matter (SPM) for the majority of the UK continental shelf is presented in the Cefas Climatology Report (Cefas, 2016). Based on the data provided within this study, the average SPM associated with the site boundary area has been estimated at between 0 mg/l and 1 mg/l between 1998 and 2015. SPM levels are generally higher in the winter months (up to 3 mg/l in January and December) than the remainder of the year (Cefas, 2016).
  2. There was no site-specific sampling undertaken for the Array, however site-specific surveys were conducted for the Seagreen 1 Offshore Wind Farm in March and June 2011, albeit at least 50.72 km away from the site boundary, and situated within shallower water (39.77 m to 64.82 m). Nonetheless, these samples suggested Total Suspended Sediments (TSSs) to be low (<5 mg/l) with a maximum value of 10 mg/l recorded in March 2011 (Fugro, 2012).
  3. Suspended Sediment Concentrations (SSCs) are primarily influenced by tidal currents, with fluctuations occurring across the spring-neap cycle and the different tidal stages (high water, peak ebb, low water, peak flood) observed throughout the March and June datasets. Wave-driven currents during storms can temporarily elevate SSCs and can cause levels to rise significantly, which then gradually decrease to baseline conditions following storm events. Due to the seasonal nature and frequency of storms, SSC levels demonstrate a broadly seasonal pattern. These effects on SSCs during storm events are less significant in deeper waters, which have a lower degree of wave penetration than in shallower waters. Therefore, it can be inferred that the TSSs will be lower at the Array site than at the Seagreen 1 Offshore Wind Farm and therefore likely below a maximum value of 10 mg/l for a winter storm.
  4. Based on the physical processes modelling undertaken for the Berwick Bank Offshore Wind Farm, within the site boundary the tide moves in an approximate north to south direction, with the flood tide going to 190o and the ebb tide to 15o, and peak spring currents of around 0.5 m/s. Residual currents are minimal in the order of 0.008 m/s in a south south-west direction of approximately 190o. Therefore, the net sediment transport in the region is limited to below 0.003 m3/d/m. The seabed material at the site boundary is primarily gravelly sand (paragraph 227), therefore using the Wentworth scale, movement would only occur for a small proportion of the tidal cycle (typically less than half). Sediment transport would increase during storm conditions, with the largest and most frequent waves approaching from the northerly sector, therefore, net sediment transport under storm conditions would be in a southerly direction.

                        Designated sites

  1. The closest site designated with physical processes qualifying interest features is the Firth of Forth Banks Complex MPA, which is located a minimum of 25 km from the site boundary. This site includes the Berwick, Scalp, and Montrose Banks, and the Wee Bankie shelf banks and mounds. Although also designated for ocean quahog Arctica islandica aggregations, this MPA is designated for offshore subtidal sands, shelf banks and mounds and moraines representative of the Wee Bankie Key Geodiversity Area (Joint Nature Conservation Committee (JNCC), 2021a).
  2. Due to the distance of this designated site to the Array (at least 25 km) and the tidal excursion of 8 km (see paragraph 218), it is concluded that there are no designated sites with the potential to be impacted by the Array.

Figure 5.1:
Seabed Features within the Site Boundary

Figure 5.1: Seabed Features within the Site Boundary

 

5.1.4. Potential Array ImpactsPotential Array Impacts

  1. A list of all potential impacts on physical processes which may occur during the construction, operation and maintenance, and decommissioning phases of the Array in the absence of designed in measures is included in Table 5.1   Open ▸ .

 

Table 5.1:
Potential Impacts Identified for Physical Processes in the Absence of Designed in Measures

Table 5.1: Potential Impacts Identified for Physical Processes in the Absence of Designed in Measures

 

5.1.5. Designed in MeasuresDesigned in Measures

  1. The following designed in measures have been considered in the identification of potential impacts that have been scoped out of the Array assessment, including how these can reduce potential for impact ( Table 5.3   Open ▸ ):
  • spacing between wind turbines within the Array will be sufficiently distant (at least 1,000 m) that wake effects or changes to the wave field will be mitigated;
  • scour protection around Array structures and foundations will be deployed if required and may consist of concrete mattresses, rock placement or artificial fronds);
  • cable protection around Array cables (which is not yet finalised, and will be refined in the Project Description section of the Array EIA Report);
  • implementation of monitoring Array cable protection in the operation and maintenance phase; and
  • development and adherence to a Cable Plan (CaP, which is not yet finalised).
  1. The significance of the effects of the Array on physical processes will determine the requirement for any further mitigation requirements to be adopted and will be consulted upon with statutory consultees throughout the EIA process.

5.1.6. Relevant ConsultationsRelevant Consultations

  1. A summary of the details of the consultations with relevant stakeholders and Statutory Nature Conservation Bodies (SNCBs) undertaken to date is presented in Table 5.2   Open ▸ .

 

Table 5.2:
Summary of Key Consultations on the Scoping Assessment for the Array

Table 5.2: Summary of Key Consultations on the Scoping Assessment for the Array

 

5.1.7. Potential Impacts After the Implementation of Designed in MeasuresPotential Impacts After the Implementation of Designed in Measures

  1. Table 5.3   Open ▸ describes the potential impacts to physical processes that have been scoped out of the assessment presently.

 

Table 5.3:
Impacts Proposed to be Scoped Out of the Array Environmental Impact Assessment for Physical Processes

Table 5.3: Impacts Proposed to be Scoped Out of the Array Environmental Impact Assessment for Physical Processes