10.8. Key Parameters for Assessment

10.8.1. Maximum Design Scenario

  1. The maximum design scenarios identified in Table 10.17   Open ▸ are those expected to have the potential to result in the greatest effect on an identified receptor or receptor group. These scenarios have been selected from the details provided in volume 1, chapter 3. Effects of greater adverse significance are not predicted to arise should any other development scenario, based on details within the Project Description (e.g. different infrastructure layout), to that assessed here, be taken forward in the final design scheme (volume 1, chapter 3).
  2. The maximum design scenario informing the assessment of potential impacts on marine mammals from ‘effects on marine mammals due to altered prey availability’ is based on the maximum design scenario embedded in volume 2, chapter 9.
Table 10.17:
Maximum Design Scenario Considered for Each Potential Impact as Part of the Assessment of LSE1 on Marine Mammals

Table 10.17: Maximum Design Scenario Considered for Each Potential Impact as Part of the Assessment of LSE1 on Marine Mammals

 

10.8.2. Impacts Scoped Out of the Assessment

  1. The marine mammal pre-Scoping workshop (see Table 10.10   Open ▸ ) was used to facilitate stakeholder engagement on topics to be scoped out of the assessment.
  2. On the basis of the baseline environment and the Project Description outlined in volume 1, chapter 3 of the Array EIA Report, a number of impacts are proposed to be scoped out of the assessment for marine mammals. This was either agreed with key stakeholders through consultation as discussed in volume 1, chapter 5, or otherwise, the impact was proposed to be scoped out in the Array EIA Scoping Report (Ossian OWFL, 2023) and no concerns were raised by key consultees within the Scoping Opinion.
  3. The impact of disturbance due to site-investigation surveys (including geophysical surveys), effect of EMFs on marine mammal receptors from subsea electrical cabling in the water column, and injury and disturbance from underwater noise generated during the operation of floating wind turbines and anchor mooring lines were initially suggested to be scoped out in the Array EIA Scoping Report (Ossian OWFL, 2023) however following consultation with key stakeholders ( Table 10.10   Open ▸ ), they have been included in the assessment and included in the MDS ( Table 10.17   Open ▸ ).
  4. Each impact is outlined, together with a justification for scoping it out of the assessment, in Table 10.18   Open ▸ .

 

Table 10.18:
Impact Scoped Out of the Assessment for Marine Mammals (Tick Confirms the Impact is Scoped Out)

Table 10.18: Impact Scoped Out of the Assessment for Marine Mammals (Tick Confirms the Impact is Scoped Out)

10.9. Methodology for Assessment of Effects

10.9.1. Overview

  1. The marine mammal assessment of effects has followed the methodology set out in volume 1, chapter 6 of the Array EIA Report. Specific to the marine mammal EIA, the following guidance documents have also been considered:
  • Guidance for Ecological Impact Assessment in the UK and Ireland (CIEEM, 2018);
  • Guidelines for data acquisition to support marine environmental assessments of offshore renewable energy projects (Judd, 2012);
  • Guidelines on the information to be contained in Environmental Impact Assessment Reports, Environmental Protection Agency (EPA, 2022); and
  • Good Practice Guide for Underwater Noise Measurement (National Measurement Office et al., 2014).
  1. In addition, the marine mammal assessment of effects has considered the legislative framework as set out in volume 1, chapter 2 of the Array EIA Report.

10.9.2. Criteria for Assessment of Effects

  1. When determining the significance of effects, a two stage process is used which involves defining the magnitude of the potential impacts and the sensitivity of the receptors. This section describes the criteria applied in this chapter to assign values to the magnitude of potential impacts and the sensitivity of the receptors. The terms used to define magnitude and sensitivity are based on those which are described in further detail in volume 1, chapter 6.
  2. The criteria for defining magnitude in this chapter are outlined in Table 10.19   Open ▸ . Each assessment considered the spatial extent with respect to the relevant MU and species ecology, duration in the context of species-specific lifespan and reproductive cycle, frequency and reversibility of impact as well as the potential for long term population consequences when determining magnitude which are outlined within the magnitude section of each impact assessment.
Table 10.19:
Definition of Terms Relating to the Magnitude of an Impact Within a Defined Geographic Frame of Reference

Table 10.19: Definition of Terms Relating to the Magnitude of an Impact Within a Defined Geographic Frame of Reference

 

  1. The criteria for defining sensitivity in this chapter are outlined in Table 10.20   Open ▸ . The sensitivity of marine mammal IEFs has been defined by an assessment of the ability of a receptor to adapt to a given impact (resilience and adaptability), and its ability to recover back to pre-impact conditions (recoverability).
  • Resilience is the ability to withstand a perturbation or disturbance by resisting damage.
  • Adaptability is the ability of an individual to adapt its behaviour to sustain ecological functioning and allow survival.
  • Recoverability is the ability of the same species to return to a state close to that which existed before the activity or event which caused change. Recoverability is dependent on the ability of the individuals to recover following cessation of the activity that causes the impact and is defined as the susceptibility of a species to disturbance, damage or death, from a specific external factor.
  1. Information on these aspects of sensitivity of the marine mammal IEFs to given impacts has been informed by the best available robust evidence from scientific research and published literature on marine mammals (studies on captive animals as well as observations from field studies). In particular, evidence from field studies of marine mammals during the construction and operation of offshore wind farms (and analogous activities such oil and gas surveys) has been used to inform this assessment. The review of resilience and recoverability of marine mammal IEFs has been combined to provide an overall evaluation of the sensitivity of a receptor to an impact as outlined in  Table 10.20   Open ▸ .

 

Table 10.20:
Definition of Terms Relating to the Sensitivity of Individuals to Effects

Table 10.20: Definition of Terms Relating to the Sensitivity of Individuals to Effects

 

  1. The magnitude of the impact and the sensitivity of the receptor are combined when determining the significance of the effect upon marine mammals. The particular method employed for this assessment is presented in Table 10.21   Open ▸ .
  2. Where a range is suggested for the significance of effect, for example, minor to moderate, it is possible that this may span the significance outcome (i.e. the range is given as minor to moderate). The technical specialist’s professional judgement was applied to determine which outcome defines the most likely effect, which takes in to account the sensitivity of the receptor and the magnitude of impact. Where professional judgement is applied to quantify final significance from a range, the assessment has set out the factors that result in the final assessment of significance. These factors may include the likelihood that an effect will occur, data certainty and relevant information about the wider environmental context.
  3. For the purposes of this assessment:
  • a level of residual effect of moderate or more will be considered a ‘significant’ effect in terms of the EIA Regulations; and
  • a level of residual effect of minor or less will be considered ‘not significant’ in terms of the EIA Regulations.
  1. Effects of moderate significance or above are therefore considered important in the decision-making process, whilst effects of minor significance or less warrant little, if any, weight in the decision-making process.

 

Table 10.21:
Matrix Used for the Assessment of the Significance of the Effect

Table 10.21: Matrix Used for the Assessment of the Significance of the Effect

 

10.9.3. Designated Sites

  1. This marine mammal chapter assesses the LSE1 on the qualifying interest feature(s) of Natura 2000 sites (i.e. nature conservation sites in Europe designated under the Habitats or Birds Directives[5]) and/or sites in the UK that comprise the National Site Network (collectively termed ‘European sites’) as described within section 10.7.2 of this chapter. The RIAA for the Array includes the assessment of the potential impacts on the site itself. A summary of the outcomes reported in the RIAA is provided in Ossian OWFL (2024).
  2. Where locally designated sites and national designations (other than European sites) fall within the boundaries of a European site and where qualifying interest features are the same, only the European site has been taken forward for assessment. Potential impacts on the integrity and conservation status of the locally or nationally designated site are assumed to be inherent within the assessment of the European site so a separate assessment for the local or national site is not undertaken.
  3. However, assessment of the LSE1 on a local or nationally designated site which falls outside the boundaries of a European site, but within the regional marine mammal study area, has been undertaken within this chapter using the EIA methodology described in section 10.9.2.