4. Information To Support the Appropriate Assessment

4.1. Introduction

  1. As described in Part 1 of this RIAA, a European site is progressed to the Appropriate Assessment stage (Stage Two of the HRA process) where it is not possible to exclude an LSE2 on one or more of its qualifying interest features with regards to the site’s conservation objectives. European sites and potential impacts of the Array that require an Appropriate Assessment are therefore those for which LSE2 could not be ruled out during the HRA Stage One LSE2 Screening exercise and following consultation.
  2. Information to help inform the Appropriate Assessment for SACs is provided in sections 4.2 to 4.6. The information provided includes a description of the SACs under consideration, their qualifying interest features, and an assessment of the implications of the Array for the site in view  of the conservation objectives of each site and considering any adverse effect on site integrity. A cross-referencing approach has been adopted to aide readability and reduce repetition where relevant, but this has been carefully carried out to ensure that all information required for a robust HRA of each site is presented. 

4.2. Maximum Design Scenarios

  1. All SAC assessment presented in this Part of the RIAA have been based on a realistic Maximum Design Scenario (MDS), which was derived from the Project Design Envelope (PDE). The final design will be no greater than the parameters set out in the MDS, and in some instances, may be less. An overview of the MDS considered for the assessment of potential impacts on Annex II diadromous fish and Annex II marine mammals is presented per potential impact (see sections 5.3 and 6.3 respectively). This MDS is consistent with that used for the fish and shellfish and marine mammal assessments in the Array EIA Report (Ossian OWFL, 2024).

4.3. Designed in Measures

  1. As part of the project design process, a number of designed in measures have been included in the Array and are committed to be delivered by the Applicant as part of the Array. These designed in measures are integrated into the project description for the Array and are not considered as mitigation measures intended to specifically avoid or reduce effects on European sites.
  2. Measures intended specifically to avoid or reduce effects on European sites were not considered during the HRA Stage One LSE2 Screening exercise but are included within the HRA Stage Two Appropriate Assessment for determination of Adverse Effects on Integrity. Where relevant, this Part of the RIAA indicates whether adverse impacts on European sites are likely and if so, whether those effects can be avoided through the introduction of mitigation measures that avoid or reduce the impact. These measures are referred to as secondary mitigation and may be taken from the relevant chapters of the Array EIA Report (Ossian OWFL, 2024) or, where necessary, may have been developed specifically to comply with HRA requirements. Where the latter is the case, this has been made clear throughout.

4.4. Baseline Information

  1. Baseline information on the SACs identified for further assessment within the HRA Stage Two Appropriate Assessment has been collated through a comprehensive review of existing desktop studies and datasets. Key desktop data sources are presented in sections 5.2 and 6.2 for Annex II diadromous fish and marine mammals, respectively. Further baseline information is presented within the respective topic chapters in the Array EIA Report and accompanying technical reports for fish and shellfish and marine mammals (Ossian OWFL, 2024).

4.5. Conservation Objectives and Conservation Advice

  1. The Statutory Nature Conservation Bodies (SNCBs) have produced conservation advice for European sites under their statutory remit. Their conservation advice provides supplementary information on European sites and their features, and although the content provided is similar, the format of the advice provided varies between the different SNCBs.
  2. Given the location and scale of the Array, European sites with the potential to be impacted fall under the remit of the Joint Nature Conservation Committee (JNCC), NatureScot, and/or Natural England. For example, the conservation advice for the Berwickshire and North Northumberland Coast SAC was developed jointly by NatureScot and Natural England but is hosted on Natural England’s Designated Site System as an interactive Conservation Advice Package (CAP). Further, the CAP for the Southern North Sea SAC has been jointly developed by Natural England and the JNCC but is hosted on JNCC’s website in the form of a ‘Conservation Objectives and Advice on Operations’ document. The Tweed Estuary SAC is under Natural England’s remit and therefore conservation advice is hosted on Natural England’s Designated Site System. However, the River Tweed SAC is located within the remit of both the Scottish Borders and Northumberland local authorities, and the CAP was produced by NatureScot and is hosted on the NatureScot sitelink system.
  3. For those European sites under the statutory remit of NatureScot, CAP documents have been produced for all terrestrial SACs (many of the river SACs screened in for Annex II diadromous are considered terrestrial), while Conservation and Management Advice (CMA) documents cover marine SACs. These documents contain revised and updated conservation objectives for the features of each European site, site-specific clarifications, advice for the conservation objectives to be achieved, and advice on management required to achieve said conservation objectives. At the time of writing, the River Teith SAC was the only site which does not have a CAP, CMA document, or conservation advice documents such as those detailed in paragraph 36.
  4. Conservation objectives of European sites set the framework for establishing appropriate conservation measures for each feature and provide a framework against which plans or projects can be assessed. The conservation objectives present the essential elements needed to ensure that the Favourable Conservation Status (FCS) of a qualifying habitat or species is maintained or restored at the site. The integrity of the site will be maintained if all the conservation objectives are met.
  5. Within the NatureScot CAPs and CMAs, the conservation objectives comprise overarching objectives (objectives 1 and 2) that apply to all features of the site, and additional objectives (2a, 2b and 2c) that have been written for each feature. Site-specific supplementary advice is provided for each objective.
  6. It is recognised in the conservation advice that if any feature of the European site is in unfavourable condition, the integrity of the site is deemed to be compromised and the overarching objective is therefore to restore site integrity. NatureScot guidance, however, states that with the ‘new style’ conservation objectives it is not expected that plans or projects must include measures that lead to restoration of features (where restore objectives are in place) in order to gain approval from a competent authority. Instead, a plan or project should not prevent site integrity from being able to be restored where necessary. This means that a plan or project should not prevent a feature from being able to be restored. HRAs should, therefore, focus on and consider if the plan or project is likely to undermine the conservation objectives of the site.

4.6. Approach to the In-Combination Assessment

  1. The approach taken for the assessment of in-combination impacts has been partly informed by the Cumulative Effects Assessment (CEA) carried out for relevant topics in the Array EIA Report (Ossian OWFL, 2024). The methodology for the in-combination assessment is compliant with HRA guidance and is summarised in the following paragraphs.
  2. The in-combination assessment has assessed potential impacts associated with the Array together with other relevant plans, projects and activities. In-combination effects are defined as the combined effect of the Array with the effects from a number of different plans or projects, on the same receptor or resource.
  3. The screening undertaken for the CEA in the Array EIA Report has been used to inform the list of projects and plans relevant to the in-combination assessment. This involved a staged process that considered the level of detail available for projects, plans and activities, as well as the potential for interactions on a conceptual, physical and temporal basis. See volume 3, appendix 6.4 of the Array EIA Report for further details on the screening process).
  4. The in-combination assessment presents relevant in-combination impacts of projects according to a tiered approach. This approach provides a framework for placing relative weight upon the potential for each project/plan to be included to ultimately be realised, based upon the project/plan’s current stage of maturity and certainty in the projects’ parameters. All projects/plans screened in via the previously described screening process have been allocated into one of the three Tiers for the in-combination assessment. It is worth noting that data collection is assessed against the source of this data (i.e. data confidence) to verify its accuracy and reliability. Where quantitative assessment has not been practicable, a mix of qualitative and quantitative or wholly qualitative assessment has been undertaken.
  5. The tiered approach which has been utilised within the in-combination assessment employs the following tiers:
  • Tier 1 assessment – Array with Proposed offshore export cable corridor(s) and Proposed onshore transmission infrastructure and all plans/projects which became operational since baseline characterisation, those under construction, and those with consent and submitted but not yet determined;
  • Tier 2 assessment – All plans/projects assessed under Tier 1, plus projects with a Scoping Report; and
  • Tier 3 assessment – All plans/projects assessed under Tier 2, which are reasonably foreseeable, plus those projects likely to come forward when an Agreement for Lease (AfL) has been granted.
  1. The specific projects scoped into the in-combination assessment for Annex II diadromous fish and Annex II marine mammals are presented in sections 5.4 and 6.4, respectively. There will be no in-combination effects with the Proposed onshore transmission infrastructure for Annex II diadromous fish and marine mammals, as all onshore works are above MHWS. Therefore, there is no receptor-impact pathway, and the Proposed onshore transmission infrastructure component of Ossian has not been considered further within the in-combination assessment. However, the Proposed offshore export cable corridor(s) is included in the Tier 1 assessment, due to a potential receptor impact pathway for both Annex II diadromous fish and marine mammals.
  2. To note, whilst the Proposed offshore export cable corridor(s) is in Tier 1 for the in-combination assessment, due to uncertainty in the final grid connection design and location details of the Proposed offshore export cable corridor(s), it was not possible to undertake a full detailed quantitative assessment at the time of writing.
  3. All of the potential impacts included for the alone assessment (see Table 3.1   Open ▸ ) were brought forward to the in-combination assessment. Some of the potential impacts considered within the Array alone assessment are specific to a particular phase of development. The potential for in-combination effects with other plans or projects requires spatial or temporal overlap with the Array during certain phases of development, therefore potential impacts associated with a certain phase have been omitted from further consideration where no plans or projects were identified to have the potential for in-combination effects during that phase.
  4. The in-combination assessment for each Tier generally follows the same methodology for each impact as the alone assessment, in order to conclude the potential for an adverse effect of integrity of the SACs.