Significance of the effect
  1. For all IEFs, the magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate significance. Given the low footprint of hard substrates to be installed that could be colonised by INNS (2.25% of the Array benthic subtidal ecology study area), and the designed in mitigation measure of an INNSMP, the effect is concluded to be of minor adverse significance, which is not significant in EIA terms.
                        Secondary mitigation and residual effect
  1. No secondary benthic subtidal ecology mitigation is considered necessary because the likely effect in the absence of mitigation is not significant in EIA terms.

                        Operation and maintenance phase

                        Magnitude of impact
  1. The MDS for this impact accounts for up to 17,780 vessel round trips over the 35 year lifecycle of the Array, or 508 round trips per year ( Table 8.12   Open ▸ ). There may be up to 31 vessels on site at any one time. As for the construction phase, these vessels provide vectors for the potential introduction of INNS into the habitats within the Array benthic subtidal ecology study area. In addition, the installation of artificial hard substrate on the seabed and in the water column in the construction phase could provide new habitat for INNS to colonise throughout the lifecycle of the Array.
  2. As above for the construction phase, many of the vessels within the operation and maintenance phase are likely to come to and from the vicinity of the Array benthic subtidal ecology study area. Therefore, the risk of introduction of INNS from outside this region is reduced.  
  3. As above for the construction phase, the implementation of an INNSMP is a designed in measure which aims to manage and reduce the potential risk of introduction and spread of INNS as far as reasonably practicable ( Table 8.17   Open ▸ ). As above, all vessels will be required to comply with the IMO ballast water management guidelines, which will help reduce the risk of potential introduction and spread of INNS as far as practicable.
  4. Overall, for all IEFs, the impact is predicted to be of local spatial extent (with hard structures installed in up to 2.25% of the Array benthic subtidal ecology study area), long term duration, intermittent (in terms of invasions), and of low reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore considered to be low.
                        Sensitivity of the receptor
  1. The sensitivities of all IEFs are considered to be as previously described for the site preparation and construction phase (see Table 8.21   Open ▸ and paragraphs 188 to 191) and have not been repeated here.
                        Significance of the effect
  1. For all IEFs, the magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate significance. Given the low footprint of hard substrates to be installed that could be colonised by INNS (2.25% of the Array benthic subtidal ecology study area), and the designed in mitigation measure of an INNSMP, the effect is concluded to be of minor adverse significance, which is not significant in EIA terms.
                        Secondary mitigation and residual effect
  1. No secondary benthic subtidal ecology mitigation is considered necessary because the likely effect in the absence of mitigation is not significant in EIA terms.

                        Decommissioning phase

                        Magnitude of impact
  1. Information on ballasting and vessel movements in the decommissioning phase are not yet defined at this stage. However, the MDS for this impact assumes that vessel return trips and presence within the Array benthic subtidal ecology study area will be similar to that of the construction phase ( Table 8.12   Open ▸ ). In addition, up to 6.79 km2 of infrastructure is proposed to be left in situ during the decommissioning phase (0.79% of the Array benthic subtidal ecology study area). As per ‘Long term subtidal habitat loss and disturbance’ above, this comprises all cable protection (5.83 km2), cable crossing protection (24,000 m2), and scour protection (928,562 m2) ( Table 8.12   Open ▸ ). It is assumed that any anchors left in-situ would be cut at or just below the seabed and so would not increase the risk of spread of INNS.
  2. As above for the construction phase, many of the vessels engaged in decommissioning activities will utilise ports and harbour on the east coast of Scotland and the UK. Therefore, the potential for introduction of INNS from outside this region is reduced.  Where vessels originate and depart to international ports and harbours operators will be required to comply with any controls set out in the INNSMP.
  3. As above for the construction phase, the implementation of an INNSMP is a designed in measure which aims to manage and reduce the potential risk of introduction and spread of INNS as far as reasonably practicable ( Table 8.17   Open ▸ ). As above, all vessels will be required to comply with the IMO ballast water management guidelines, which will help reduce the risk of potential introduction and spread of INNS as far as practicable.
  4. Overall, for all IEFs, the impact is predicted to be of local spatial extent (with hard structures remaining in up to 0.79% of the Array benthic subtidal ecology study area), long term duration, intermittent (in terms of invasions), and of low reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore considered to be low.
                        Sensitivity of the receptor
  1. The sensitivities of all IEFs are considered to be as previously described for the site preparation and construction phase (see Table 8.21   Open ▸ and paragraphs 188 to 191) and have not been repeated here.
                        Significance of the effect
  1. For all IEFs, the magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate significance. Given the low footprint of hard substrates to be installed that could be colonised by INNS (2.25% of the Array benthic subtidal ecology study area), and the designed in mitigation measure of an INNSMP, the effect is concluded to be of minor adverse significance, which is not significant in EIA terms.
                        Secondary mitigation and residual effect
  1. No secondary benthic subtidal ecology mitigation is considered necessary because the likely effect in the absence of mitigation is not significant in EIA terms.

8.12. Cumulative Effects Assessment

8.12.1. Methodology

  1. The CEA assesses the LSE1 associated with the Array together with other relevant plans, projects and activities. Cumulative effects are 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. Further details on CEA methodology are provided in volume 1, chapter 6.
  2. The plans and projects selected as relevant to the CEA presented within this chapter are based upon the results of a screening exercise (see volume 3, appendix 6.4 of the Array EIA Report). Volume 3, appendix 6.4 further provides information regarding how information pertaining to other plans and projects is gained and applied to the assessment. Each project or plan has been considered on a case-by-case basis for screening in or out of this chapter's assessment based upon data confidence, impact-receptor pathways and the spatial/temporal scales involved.
  3. In undertaking the CEA for the Array, it should be noted that other plans and projects under consideration will have differing potential for proceeding to an operational stage and hence a differing potential to ultimately contribute to a cumulative impact alongside the Array. Therefore, a tiered approach has be adopted which provides a framework for placing relative weight upon the potential for each project/plan to be included in the CEA to ultimately be realised, based upon the project/plan’s current stage of maturity and certainty in the projects’ parameters. The tiered approach which will be utilised within the Array CEA 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 CEA for benthic subtidal ecology are outlined in Table 8.22   Open ▸ and presented in Figure 8.6   Open ▸ . Given that there is no potential pathway for impact to benthic subtidal ecology due to the Proposed onshore transmission infrastructure, this project has not been considered further within the CEA. The Proposed offshore export cable corridor(s), however, remains as part of the Tier 1 assessment, due to a potential receptor impact pathway.
  2. The range of potential cumulative impacts that are identified and included in Table 8.23   Open ▸ is a subset of those considered for the Array alone assessment. Most of the impacts included for the alone assessment (see Table 8.12   Open ▸ ) are brought forward to the CEA, with the exception of ‘Increased SSCs and associated deposition’ This is because this impact is regarded to be highly localised and temporary in nature. Therefore, it is considered that this impact has limited or no potential to interact with the other plans or projects identified. This impact has therefore not been taken forward for detailed cumulative assessment.
  3. Similarly, some of the potential impacts considered within the Array alone assessment are specific to a particular phase of development (e.g. construction, operation and maintenance or decommissioning). The potential for cumulative effects with other plans or projects requires spatial or temporal overlap with the Array during certain phases of development, therefore impacts associated with a certain phase may be omitted from further consideration where no plans or projects have been identified that have the potential for cumulative effects during this phase of development.
  4. For the purposes of this Array EIA Report, a 50 km screening buffer around the Array was used to identify other plans and projects to be included within the CEA. This buffer is considered appropriate and precautionary as all impacts considered within the CEA will be localised within its extent. 

 

Figure 8.6:
Other Projects/Plans Screened into the CEA for Benthic Subtidal Ecology


Figure 8.6: Other Projects/Plans Screened into the CEA for Benthic Subtidal Ecology

Table 8.22:
List of Other Plans and Projects Considered within the CEA for Benthic Subtidal Ecology

Table 8.22: List of Other Plans and Projects Considered within the CEA for Benthic Subtidal Ecology

 

8.12.2. Maximum Design Scenario

  1. The MDSs identified in Table 8.12   Open ▸ have been selected as those having the potential to result in the greatest effect on an identified receptor or receptor group. The cumulative effects presented in Table 8.23   Open ▸ and assessed in this section have been selected from the details provided in volume 1, chapter 3 of the Array EIA Report as well as the information available on other plans and projects (see volume 3, appendix 6.4), to inform a ‘MDS’. Effects of greater adverse significance are not predicted to arise should any other development scenario, based on details within the Project Description (volume 1, chapter 3), (e.g. different wind turbine layout), to that assessed here, be taken forward in the final design scheme.

 

Table 8.23:
Maximum Design Scenario Considered for Each Impact as part of the Assessment of Likely Significant Cumulative Effects on Benthic Subtidal Ecology

Table 8.23: Maximum Design Scenario Considered for Each Impact as part of the Assessment of Likely Significant Cumulative Effects on Benthic Subtidal Ecology

 

8.12.3. Cumulative Effects Assessment

  1. An assessment of the likely significance of the cumulative effects of the Array upon benthic subtidal ecology receptors arising from each identified impact is given below.

Temporary Habitat Loss and Disturbance

  1. There is potential for cumulative temporary habitat loss and disturbance as a result of activities associated with the Array and other plans and projects. Activities include sand wave and boulder clearance and relocation, UXO clearance, cable installation, jack up vessel use, and cable repair and reburial. For the purposes of this Array EIA Report, this effect has been assessed using the tiered approach outlined in section 8.12.1. The plans and projects screened into the CEA for this impact and their respective tiers are outlined in Table 8.23   Open ▸ .

                        Tier 1

                        Construction phase
Magnitude of impact
  1. There were two Tier 1 projects identified with potential for cumulative effects associated with this impact:
  • the construction and operation and maintenance phases of the Proposed offshore export cable corridor(s);
  • the operation and maintenance phase of the Eastern Green Link 2 ( Table 8.23   Open ▸ ).
  1. Site preparation and construction activities at the Eastern Green Link 2 project are planned to occur between 2024 to 2029, so will not overlap with this phase of the Array ( Table 8.22   Open ▸ ). For clarity, and to give an indication in the difference in scale between the Eastern Green Link 2 and the Array, values of temporary habitat loss and disturbance in the site preparation and construction phase of the Eastern Green Link 2 are presented in Table 8.24   Open ▸ (National Grid Electricity Transmission and Scottish Hydro Electric Transmission plc, 2022). Within the Environmental Appraisal Report for the Eastern Green Link 2, no values were provided for temporary habitat loss and disturbance during its operation and maintenance phase (which coincides with the site preparation and construction phase of the Array). However, it was noted that it would be significantly lower than the value of 15.20 km2 provided for the site preparation and construction phase ( Table 8.24   Open ▸ ) (National Grid Electricity Transmission and Scottish Hydro Electric Transmission plc, 2022). At the time of writing this Array EIA Report, there was no Offshore EIA Report available for the Proposed offshore export cable corridor(s), but the activities and footprints of disturbance associated with its site preparation and construction phase are expected to be similar to those of the Eastern Green Link 2, given that both projects are both High Voltage Direct Current (HVDC) subsea power cables.
  2. Further, activities associated with the site preparation and construction phase for the Proposed offshore export cable corridor(s) are expected to be of an equal or lesser extent than those represented by the MDS for the Array alone, which represented up to 49.95 km2 of temporary habitat loss and disturbance ( Table 8.24   Open ▸ ). As outlined in paragraphs 58 to 60 for the Array alone, the impacts of cable installation and seabed preparation are likely to be reversible. Other activities associated with the Array during this phase are not likely to occur within the Tier 1 projects, such as jack up vessel use and temporary wet storage. The cumulative magnitude of impact of the Array with the Tier 1 projects is therefore not expected to represent a material additional impact to that defined for the assessment of the Array alone (section 8.11).

Table 8.24:
Cumulative Footprint of Temporary Habitat Loss and Disturbance (km2) for the Tier 1 Projects’ Site Preparation and Construction Phases

Table 8.24: Cumulative Footprint of Temporary Habitat Loss and Disturbance (km2) for the Tier 1 Projects’ Site Preparation and Construction Phases

 

  1. Within this phase of development of the Array, site preparation and construction activities are anticipated to occur intermittently. They will be spread out across the full allotted timeframe with only a small proportion of the MDS footprint for this impact being affected at any one time. There will be no spatial overlap between the Array and the Eastern Green Link 2, however, there may be some spatial overlap between the Array and the Proposed offshore export cable corridor(s), given their proximity.
  2. The cumulative impact is predicted to be of local spatial extent, medium term duration (between 2030 and 2038), intermittent, and of high reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore considered to be low.
Sensitivity of the receptor
  1. The sensitivities of the benthic subtidal ecology IEFs are as previously described above for the assessment of the Array alone (see Table 8.18   Open ▸ and its paragraphs 66 to 70).
  2. Overall, the ocean quahog IEF is deemed to be of high vulnerability, low recoverability, and national value. The sensitivity of the receptor is, therefore, considered to be high.
  3. Overall, all other IEFs are deemed to be of medium to high vulnerability, high recoverability, and regional value. The sensitivities of the receptors are, therefore, considered to be medium.
Significance of effect
  1. Overall, for the ocean quahog IEF, the cumulative magnitude of impact is deemed to be low, and the sensitivity of the receptor is considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate adverse significance. There will be a low footprint of temporary habitat loss and disturbance with respect to the Tier 1 projects and the 50 km screening area used for the CEA and regional benthic subtidal ecology study area as a whole. Due to the widespread availability of alternative suitable habitat, the cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
  2. For all other IEFs, the cumulative magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
Further mitigation and residual effect
  1. No benthic subtidal ecology mitigation is considered necessary because the likely cumulative effect in the absence of further mitigation (beyond the designed in measures outlined in section 8.10) is not significant in EIA terms.
                        Operation and maintenance phase
Magnitude of impact
  1. There were two Tier 1 projects identified with potential for cumulative effects associated with this impact:
  • the operation and maintenance and decommissioning phases of the Proposed offshore export cable corridor(s); and
  • the operation and maintenance and decommissioning phases of the Eastern Green Link 2 ( Table 8.23   Open ▸ ).
  1. At the time of writing this Array EIA Report, there was no Offshore EIA Report available for the Proposed offshore export cable corridor(s). However, given that the two Tier 1 projects are both HVDC subsea power cables, activities associated with their operation and maintenance phase are expected to be of an equal or lesser extent than those represented by the MDS for the Array alone, which were up to 51.41 km2 of temporary habitat loss and disturbance ( Table 8.12   Open ▸ ). The cumulative magnitude of impact of the Array with the Tier 1 projects is therefore not expected to represent a material additional impact to that defined for the assessment of the Array alone (section 8.11).
  2. Within the Environmental Appraisal Report for the Eastern Green Link 2, no values were provided for temporary habitat loss and disturbance during the operation and maintenance phase, however it was noted that they would be significantly lower than the value of 15.20 km2 provided for the site preparation and construction phase (National Grid Electricity Transmission and Scottish Hydro Electric Transmission plc, 2022).
  3. The cumulative spatial extent of this impact in the operation and maintenance phase therefore likely to be small in relation to the whole Array benthic subtidal ecology study area, although there is the potential for repeated disturbance to the habitats in the immediate vicinity infrastructure and cables. There will be no spatial overlap between the Array and the Eastern Green Link 2, however, there may be some spatial overlap between the Array and the Proposed offshore export cable corridor(s), given their proximity.
  4. The cumulative impact is predicted to be of local spatial extent, long term duration, intermittent and high reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore, considered to be low.
Sensitivity of the receptor
  1. The sensitivities of the benthic subtidal ecology IEFs are as previously described above for the assessment of the Array alone (see Table 8.18   Open ▸ and paragraphs 66 to 70).
  2. Overall, the ocean quahog IEF is deemed to be of high vulnerability, low recoverability and national value. The sensitivity of the receptor is, therefore, considered to be high.
  3. Overall, all other IEFs are deemed to be of medium to high vulnerability, high recoverability, and regional value. The sensitivities of the receptors are, therefore, considered to be medium.
Significance of effect
  1. Overall, for the ocean quahog IEF, the cumulative magnitude of impact is deemed to be low, and the sensitivity of the receptor is considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate adverse significance. Given the low footprint of temporary habitat loss and disturbance with respect to the Tier 1 projects and the North Sea as a whole, and the widespread availability of alternative suitable habitat, the cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
  2. For all other IEFs, the cumulative magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
Further mitigation and residual effect
  1. No benthic subtidal ecology mitigation is considered necessary because the likely cumulative effect in the absence of further mitigation (beyond the designed in measures outlined in section 8.10) is not significant in EIA terms.

                        Tier 2

                        Construction phase
Magnitude of impact
  1. In addition to the Tier 1 projects, there was one Tier 2 project identified with potential for cumulative effects associated with this impact: Morven Offshore Wind Farm ( Table 8.23   Open ▸ ). As with the Array, site preparation and construction activities applicable to this impact for the Morven Offshore Wind Farm are:
  • site preparation (sand wave clearance and boulder clearance and relocation);
  • cable installation; and
  • jack up vessel use for infrastructure installation (Morven Offshore Wind Limited, 2023).
  1. However, it should be noted that no offshore temporary wet storage was included within the Scoping Report for Morven Offshore Wind Farm (Morven Offshore Wind Limited, 2023). Given the higher number of wind turbines and energy generation capacity of the Array in comparison to Morven Offshore Wind Farm ( Table 8.22   Open ▸ ) it is likely that the maximum footprints of temporary habitat loss and disturbance of the Array will be larger than those for Morven Offshore Wind Farm (49.95 km2 for the Array; Table 8.12   Open ▸ ). As outlined in paragraphs 58 to 61 for the Array alone, the impacts of cable installation, seabed preparation, and jack up vessel use are likely to be reversible. The cumulative magnitude of the Tier 2 assessment is therefore not expected to a represent material additional impact to that defined for the assessment of the Array alone (section 8.11).
  2. The maximum duration of the offshore construction phase for the Array is up to eight years between 2031 to 2038, and between 2031 to 2038 for Morven Offshore Wind Farm ( Table 8.22   Open ▸ ). Therefore, there may be full temporal overlap between the site preparation and construction activities of the Array and Morven Offshore Wind Farm. Given the reversibility and short temporal overlap in the Tier 2 assessment, cumulative impacts will be low.
  3. The cumulative impact is predicted to be of local spatial extent, medium term duration, intermittent, and of high reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore considered to be low.
Sensitivity of the receptor
  1. The sensitivities of the benthic subtidal ecology IEFs are as previously described above for the assessment of the Array alone (see Table 8.18   Open ▸ and paragraphs 66 to 70).
  2. Overall, the ocean quahog IEF is deemed to be of high vulnerability, low recoverability and national value. The sensitivity of the receptor is, therefore, considered to be high.
  3. Overall, all other IEFs are deemed to be of medium to high vulnerability, high recoverability, and regional value. The sensitivities of the receptors are, therefore, considered to be medium.
Significance of effect
  1. Overall, for the ocean quahog IEF, the cumulative magnitude of impact is deemed to be low, and the sensitivity of the receptor is considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate adverse significance. Given the low footprint of temporary habitat loss and disturbance with respect to the Tier 2 projects and the North Sea as a whole, and the widespread availability of alternative suitable habitat, the cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
  2. For all other IEFs, the cumulative magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
Further mitigation and residual effect
  1. No benthic subtidal ecology mitigation is considered necessary because the likely cumulative effect in the absence of further mitigation (beyond the designed in measures outlined in section 8.10) is not significant in EIA terms.
                        Operation and maintenance phase
Magnitude of impact
  1. In addition to the Tier 1 projects, there was one Tier 2 project identified with potential for cumulative effects associated with this impact: Morven Offshore Wind Farm ( Table 8.23   Open ▸ ). As with the Array, operation and maintenance activities applicable to this impact for the Morven Offshore Wind Farm are cable repair and reburial and the use of jack up vessels for operation and maintenance activities (Morven Offshore Wind Limited, 2023). Within the Scoping Report for Morven Offshore Wind Farm, the extent of these activities is expected to be lower than that of the site preparation and construction phase (Morven Offshore Wind Limited, 2023).
  2. For the Array, up to 51.41 km2 of temporary habitat loss and disturbance may occur due to operation and maintenance activities ( Table 8.12   Open ▸ ). Given the higher number of wind turbines and energy generation capacity of the Array in comparison to Morven Offshore Wind Farm ( Table 8.22   Open ▸ ) it is likely that the maximum footprints of temporary habitat loss and disturbance of the Array will be larger than those for Morven Offshore Wind Farm.
  3. The cumulative spatial extent of this impact in the operation and maintenance phase therefore likely to be small in relation to the whole Array benthic subtidal ecology study area, although there is the potential for repeated disturbance to the habitats in the immediate vicinity infrastructure and cables. The cumulative magnitude of impact of the Tier 2 assessment is not expected to represent a material additional impact to that defined for the assessment of the Array alone (section 8.11).
  4. The cumulative impact is predicted to be of local spatial extent, long term duration, intermittent and high reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore, considered to be low.
Sensitivity of the receptor
  1. The sensitivities of the benthic subtidal ecology IEFs are as previously described above for the assessment of the Array alone (see Table 8.18   Open ▸ and paragraphs 66 to 70).
  2. Overall, the ocean quahog IEF is deemed to be of high vulnerability, low recoverability and national value. The sensitivity of the receptor is, therefore, considered to be high.
  3. Overall, all other IEFs are deemed to be of medium to high vulnerability, high recoverability, and regional value. The sensitivities of the receptors are, therefore, considered to be medium.
Significance of effect
  1. Overall, for the ocean quahog IEF, the cumulative magnitude of impact is deemed to be low, and the sensitivity of the receptor is considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate adverse significance. Given the low footprint of temporary habitat loss and disturbance with respect to the Tier 2 projects and the North Sea as a whole, and the widespread availability of alternative suitable habitat, the cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
  2. For all other IEFs, the cumulative magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
Further mitigation and residual effect
  1. No benthic subtidal ecology mitigation is considered necessary because the likely cumulative effect in the absence of further mitigation (beyond the designed in measures outlined in section 8.10) is not significant in EIA terms.

                        Tier 3

                        Construction phase
Magnitude of impact
  1. In addition to the Tier 1 and Tier 2 projects, there were six Tier 3 projects identified with potential for cumulative effects associated with this impact:
  • Morven Offshore Export Cable Corridor(s);
  • Bellrock Offshore Wind Farm;
  • Bowdun Offshore Wind Farm;
  • Campion Offshore Wind Farm;
  • Eastern Green Link 3; and
  • Eastern Green Link 4 ( Table 8.23   Open ▸ ).
  1. As these are Tier 3 projects, there are no Scoping Reports or EIA documents available in the public domain. Therefore, there is no information available on the impact that these Tier 3 projects will have on benthic subtidal ecology. The site preparation and construction activities associated with the Bowdun Offshore Wind Farm are likely to be similar to those of the Array, and those associated with Morven Offshore Export Cable Corridor(s) and Eastern Green Link 3 and 4 are likely to be similar to those discussed above for the Eastern Green Link 2 in the Tier 1 assessment (paragraphs 218 to 222). Given the higher number of wind turbines and energy generation capacity of the Array in comparison to the Bellrock, Bowdun, and Campion Offshore Wind Farms ( Table 8.22   Open ▸ ) it is likely that the maximum footprints of temporary habitat loss and disturbance of the Array will be larger than those of the latter (49.95 km2 for the Array; Table 8.12   Open ▸ ). As outlined in paragraphs 58 to 61 for the Array alone, the impacts of cable installation, seabed preparation, and jack up vessel use are likely to be reversible. The cumulative magnitude of impact of the Tier 3 assessment is therefore not expected to represent material additional impact to that defined for the assessment of the Array alone (section 8.11).
  2. The maximum duration of the offshore construction phase for the Array is between 2031 to 2038, but there are currently no dates available for the construction phases of any of the Tier 3 projects ( Table 8.22   Open ▸ ). Therefore, there may be minimal overlap between the site preparation and construction activities of the Array and that of the Tier 3 projects, but this cannot be confirmed at this stage.
  3. The cumulative impact is predicted to be of local spatial extent, medium term duration, intermittent, and of high reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore considered to be low.
Sensitivity of the receptor
  1. The sensitivities of the benthic subtidal ecology IEFs are as previously described above for the assessment of the Array alone (see Table 8.18   Open ▸ and paragraphs 66 to 70).
  2. Overall, the ocean quahog IEF is deemed to be of high vulnerability, low recoverability and national value. The sensitivity of the receptor is, therefore, considered to be high.
  3. Overall, all other IEFs are deemed to be of medium to high vulnerability, high recoverability, and regional value. The sensitivities of the receptors are, therefore, considered to be medium.
Significance of effect
  1. Overall, for the ocean quahog IEF, the cumulative magnitude of impact is deemed to be low, and the sensitivity of the receptor is considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate adverse significance. Given the low footprint of temporary habitat loss and disturbance with respect to the Tier 3 projects and the North Sea as a whole, and the widespread availability of alternative suitable habitat, the cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
  2. For all other IEFs, the cumulative magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
Further mitigation and residual effect
  1. No benthic subtidal ecology mitigation is considered necessary because the likely cumulative effect in the absence of further mitigation (beyond the designed in measures outlined in section 8.10) is not significant in EIA terms.
                        Operation and maintenance phase
Magnitude of impact
  1. In addition to the Tier 1 and Tier 2 projects, there were six Tier 3 projects identified with potential for cumulative effects associated with this impact:
  • Morven Offshore Export Cable Corridor(s);
  • Bellrock Offshore Wind Farm;
  • Bowdun Offshore Wind Farm;
  • Campion Offshore Wind Farm;
  • Eastern Green Link 3; and
  • Eastern Green Link 4 ( Table 8.23   Open ▸ ).
  1. As these are Tier 3 projects, there are no Scoping Reports or EIA documents available in the public domain. Therefore, there is no information available on the impact that these Tier 3 projects will have on benthic subtidal ecology. The activities associated with Bellrock, Bowdun, and Campion Offshore Wind Farms are likely to be similar to those of the Array, and those associated with Morven Offshore Export Cable Corridor(s) and Eastern Green Link 3 and 4 are likely to be similar to those discussed above for the Eastern Green Link 2 in the Tier 1 assessment (paragraphs 229 to 233). These activities include cable repair and reburial and use of jack up vessels for infrastructure maintenance.
  2. For the Array, up to 51.41 km2 of temporary habitat loss and disturbance may occur due to operation and maintenance activities ( Table 8.12   Open ▸ ). Given the higher number of wind turbines and energy generation capacity of the Array in comparison to the Tier 3 offshore wind farms ( Table 8.22   Open ▸ ) it is likely that the maximum footprints of temporary habitat loss and disturbance of the Array will be larger than those of the Tier 3 projects.
  3. The cumulative spatial extent of this impact in the operation and maintenance phase likely to be small in relation to the whole Array benthic subtidal ecology study area, although there is the potential for repeated disturbance to the habitats in the immediate vicinity infrastructure and cables. The cumulative magnitude of impact for Tier 3 assessment is not expected to represent material additional impact to that defined for the assessment of the Array alone (section 8.11).
  4. The cumulative impact is predicted to be of local spatial extent, long term duration, intermittent and high reversibility. It is predicted that the impact will affect the receptors directly. The magnitude is therefore, considered to be low.
Sensitivity of the receptor
  1. The sensitivities of the benthic subtidal ecology IEFs are as previously described above for the assessment of the Array alone (see Table 8.18   Open ▸ and paragraphs 66 to 70).
  2. Overall, the ocean quahog IEF is deemed to be of high vulnerability, low recoverability and national value. The sensitivity of the receptor is, therefore, considered to be high.
  3. Overall, all other IEFs are deemed to be of medium to high vulnerability, high recoverability, and regional value. The sensitivities of the receptors are, therefore, considered to be medium.
Significance of effect
  1. Overall, for the ocean quahog IEF, the cumulative magnitude of impact is deemed to be low, and the sensitivity of the receptor is considered to be high. As per Table 8.16   Open ▸ , the effect will, therefore, be of minor to moderate adverse significance. Given the low footprint of temporary habitat loss and disturbance with respect to the Tier 3 projects and the North Sea as a whole, and the widespread availability of alternative suitable habitat, the cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
  2. For all other IEFs, the cumulative magnitude of the impact is deemed to be low, and the sensitivities of the receptors are considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
Further mitigation and residual effect
  1. No benthic subtidal ecology mitigation is considered necessary because the likely cumulative effect in the absence of further mitigation (beyond the designed in measures outlined in section 8.10) is not significant in EIA terms.

Long Term Habitat Loss and Disturbance

  1. There is potential for cumulative long term habitat loss and disturbance due to infrastructure installed during the construction of the Array and the other plans and projects. This long term habitat loss will persist into the operation and maintenance phase as infrastructure is installed, and as such, the construction and operation and maintenance phases have been assessed together. Infrastructure installed includes: foundations, scour protection, cable protection, cable crossing protection, junction boxes, mooring lines, and anchors. For the purposes of this Array EIA Report, this effect has been assessed using the tiered approach outlined in section 8.12.1. The plans and projects screened into the CEA for this impact and their respective Tiers are outlined in Table 8.23   Open ▸ .