Sensitivity of receptor

727. The sensitivities of marine mammals to cumulative auditory injury from UXO are as previously described above for the assessment of the Array alone (paragraphs 293 to 300) for the construction phase and therefore is not repeated here.
728. All marine mammals are deemed to have limited resilience to auditory injury (PTS), low recoverability and are of high international value. The sensitivity of the receptor is therefore, considered to be high.
729. The sensitivities of marine mammals to cumulative disturbance from UXO are as previously described above for the assessment of the Array alone (paragraphs 301 to 312) for the construction phase and therefore is not repeated here.
730. All marine mammals are deemed to have some resilience to behavioural disturbance, high recoverability, and high international value. The sensitivity of the receptor to cumulative TTS is therefore, considered to be low.

Significance of effect

Auditory injury

731. Overall, for bottlenose dolphin, white-beaked dolphin, minke whale, humpback whale and grey seal, the magnitude of the cumulative effect (auditory injury) is deemed to be negligible and the sensitivity of all receptors is considered to be high. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.
732. For harbour porpoise only, overall, the magnitude of the cumulative effect is deemed to be low and the sensitivity of all receptors is considered to be high. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.

Behavioural disturbance (TTS as a proxy)

733. Overall, for all species, the magnitude of the cumulative effect (behavioural disturbance) is deemed to be low and the sensitivity of all receptors is considered to be low. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.

Further mitigation and residual effect

Auditory injury

734. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Behavioural disturbance (TTS as a proxy)

735. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Disturbance due to site-investigation surveys (including geophysical surveys)

736. The risk of injury in terms of PTS to marine mammal receptors as a result of underwater due to site-investigation surveys would be expected to be localised to within the boundaries of the respective projects. The assessment for the Array found that the maximum impact range was 310 m for geophysical surveys and 45 m for geotechnical surveys (based on harbour porpoise) and this highly localised, with numbers of animals impacted will be extremely low and the magnitude of the impact with respect to auditory injury occurring in marine mammals has been assessed as negligible. Furthermore, any risk of injury will be mitigated via the outline MMMP (volume 4, appendix 22) and no potential for cumulative impacts for injury and is not considered further in cumulative assessment. The cumulative assessment provided in paragraph 737 et seq. focuses on disturbance only.

                        Tier 1

Construction phase

Magnitude of impact

737. One Tier 1 project was identified with potential for cumulative effects associated with this impact within the 50 km buffer, within in the regional marine mammal study area:

• Proposed offshore export cable corridor(s) (construction phase and operation and maintenance phase).

738. As discussed in paragraph 592, there is uncertainty of the final design and location details of the Proposed offshore export cable corridor(s) and therefore it is not possible to provide a quantitative assessment of the impact from site-investigation surveys. It can be reasonably assumed the extent of the impacts for the Proposed offshore export cable corridor(s) are expected to be similar to those of the Array (see paragraph 251 et seq.), as, whilst the geographical location of the geophysical survey areas of other projects will differ, the extent of the disturbance per survey equipment at any one point will likely be very similar. The construction phase (and associated pre-construction surveys) of the Proposed offshore export cable corridor(s) (2029 to 2036) overlaps with that of the Array and therefore there is the potential for temporal overlap in site-investigation surveys. However, it should be noted that site-investigation survey equipment will not be operating continuously, it will be used when required for investigations of particular areas of the seabed where additional information is required to inform the construction. Site-investigation surveys for Proposed offshore export cable corridor(s) are likely to be carried out at the start of the construction phase (2030) and therefore direct overlap with the site-investigation surveys for the Array is unlikely (particularly given the need for limited resource to undertake site-investigation surveys).
739. For the Array, the maximum disturbance range across all geophysical surveys was estimated as 1,340 m (SBP activity) and the maximum range across geotechnical activities was 9,101 m (vibrocoring) for harbour porpoise. Given that the distance between the Array and Proposed offshore export cable corridor(s) is less than the estimated disturbance ranges from geophysical surveys there is potential for spatial overlap. However, the likelihood of temporal overlap of site investigation surveys at these projects is very low, and it is therefore unlikely, due to the temporal separation, that site-investigation surveys at the Array and Proposed offshore export cable corridor(s) will spatially overlap at any one time given the small disturbance ranges and no application of dose-response (see paragraph 349 for detail).
740. Surveys are anticipated to be short term in nature (weeks to a few months) and occur intermittently over the construction phase. For example, the site-investigation surveys for the Array will be carried out over 5 months within a 3 year period.
741. The cumulative impact is predicted to be of local to regional spatial extent in context of the relevant geographic frame of reference, short term duration, intermittent and the effect of behavioural disturbance is of reversible (with animals returning to baseline levels soon after surveys have ceased). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The cumulative magnitude was therefore considered to be low.

Sensitivity of the receptors

742. The sensitivities of marine mammals to cumulative disturbance from site-investigation surveys are as previously described above for the assessment of the array alone (paragraphs 355 to 365) for the construction phase and therefore is not repeated here. It is expected that, to some extent, marine mammals will be able to withstand temporary elevated levels of underwater sound during site-investigation surveys and behavioural responses are highly species and context specific.
743. All receptors are deemed to have some resilience to cumulative behavioural disturbance, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

744. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

745. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Operation and maintenance phase

Magnitude of impact

746. The operation and maintenance activities of the Array will overlap with Tier 1 projects identified in Table 10.55 and may lead to disturbance to marine mammals from site-investigation surveys:

• Proposed offshore export cable corridor(s) (construction and operation and maintenance phases).

747. For the Array, routine geophysical surveys will take place once every 24 months for wind turbines and OSP foundations as well as wind turbines interior and exterior. For inter-array cables and interconnector cables routine geophysical surveys will be undertaken annually for the first three years, then every 24 months. The duration of routine geophysical survey campaign is up to three months.
748. The Proposed offshore export cable corridor(s) is currently at planned status and therefore there is no information in the public domain in which to determine the impact from site-investigation surveys. However, it can be reasonably assumed the extent of the impacts for the Proposed offshore export cable corridor(s) are expected to be similar to those of the Array (see paragraph 251 et seq.), as (as detailed in paragraph 738) the extent of disturbance per survey equipment is likely to be similar even if in a different location. It is possible that routine geophysical surveys for the Proposed offshore export cable corridor(s) will be similar to those of the inter-array cables and interconnector cables for the Array and therefore, there is potential for geophysical surveys during the operation phase to temporally overlap with the Proposed offshore export cable corridor(s). Surveys are anticipated to be short term in nature (weeks to a few months) and occur intermittently over the operation and maintenance phase.
749. With measures adopted as part of the Array implemented for the geophysical surveys, the cumulative impact is predicted to be of local to regional spatial extent in context of the relevant geographic frame of reference, short term duration, intermittent and the effect of behavioural disturbance is reversible (with animals returning to baseline levels soon after surveys have ceased). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The cumulative magnitude was therefore considered to be low.

Sensitivity of the receptors

750. The sensitivity of marine mammals to elevated underwater noise due to site-investigation surveys is as described in paragraphs 355 et seq.
751. All receptors are deemed to have some resilience and adaptability to cumulative behavioural disturbance, high recoverability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

752. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is considered to be medium. Cumulatively the effect will therefore be of minor adverse significance, which is not significant in EIA terms.

Further mitigation and residual effect

753. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms. Therefore, the residual effect is considered to be of minor adverse significance which is not significant in EIA terms.

                        Tier 2

Construction phase

Magnitude of impact

754. One Tier 2 project was identified (in addition to Tier 1 projects) with potential for cumulative effects associated with this impact, which lies within the 50 km buffer used for site-investigation surveys:

• Morven BP-EnBW.

755. Disturbance to marine mammals from pre-construction site-investigation surveys is scoped in for Morven Offshore Wind Project (Morven Offshore Wind Limited, 2023). The Scoping Report details comparative sound modelling for geophysical activities will be undertaken to inform an assessment of possible effects from elevated levels of underwater sound. At this point in time, there is not quantitative information upon which to take a more detailed assessment of site-investigation surveys. The Array lies, at the closest point, 5.5 km from the Morven Array and based on the maximum disturbance range predicted for the Array (1,340 m for SBP and 9,101 m for vibrocoring) there is likely to be spatial overlap between these two projects. However, the likelihood of temporal overlap of site investigation surveys at the Array and Morven Offshore Wind Project is very low (e.g. there are limitations on the number of survey vessels that could carry out such surveys at one time) and it is therefore unlikely, due to the temporal separation, that site-investigation surveys at Morven Offshore Wind Project would overlap with the area disturbed during site-investigation surveys at the other Tier 1 project, Proposed offshore export cable corridor(s) (see paragraph 349 for detail).
756. The cumulative impact is predicted to be of local to regional spatial extent in context of the relevant geographic frame of reference, short term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after surveys have ceased). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The cumulative magnitude was therefore considered to be low.

Sensitivity of the receptors

757. The sensitivity of marine mammals to elevated underwater noise due to site-investigation surveys is as described in paragraphs 355 et seq.
758. All receptors are deemed to have some resilience to cumulative behavioural disturbance, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

759. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is considered to be medium. Cumulatively the effect will therefore be of minor adverse significance, which is not significant in EIA terms.

Further mitigation and residual effect

760. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

                        Tier 3

Construction phase

Magnitude of impact

761. Three Tier 3 projects were identified with potential for cumulative effects associated with this impact, which lies within the 50 km buffer used for site-investigation surveys:

• Bellrock Offshore Wind Farm;
• Bowdun Offshore Wind Farm;
• Campion Offshore Wind Farm; and
• Morven BP-EnBW Offshore Export Cable Corridor.

762. Tier 3 projects are in a pre-application phase and no EIA Scoping Report or EIA Report is available to inform a quantitative assessment. Therefore, a qualitative assessment is provided below.
763. Whilst there is no information on the timeline for construction at Bellrock Offshore Wind Farm and therefore it cannot be excluded from the CEA, the likelihood of direct temporal overlap with site-investigation surveys at Bellrock Offshore Wind Farm and the Array is unlikely given the different stages of status of development. Furthermore, surveys are likely to be short term and intermittent and disturbance ranges associated with these projects would be highly localised. Bellrock Offshore Wind Farm is located 8.57 km north-west from the Array and therefore site-investigation surveys will have no spatial overlap given the small disturbance ranges presented for the Array assessment (paragraph 347).
764. Whilst there is no information on the timeline for construction at Bowdun Offshore Wind Farm and therefore it cannot be excluded from the CEA, the likelihood of direct temporal overlap with site-investigation surveys at Bowdun Offshore Wind Farm and the Array is unlikely given the different stages of status of development. Furthermore, surveys are likely to be short term and intermittent and disturbance ranges associated with these projects would be highly localised. Bowdun Offshore Wind Farm is located 25.35 km north-west from the Array and therefore site-investigation surveys will have no spatial overlap given the small disturbance ranges presented for the Array assessment (paragraph 347).
765. The likelihood of direct temporal overlap with site-investigation surveys at Campion Offshore Wind and the Array is unlikely given the different stages of status of development. Furthermore, surveys are likely to be short term and intermittent and disturbance ranges associated with these projects would be highly localised. Campion Offshore Wind Farm is located 44.15 km north-east from the Array and therefore site-investigation surveys will have no spatial overlap given the small disturbance ranges presented for the Array assessment (paragraph 347).
766. The cumulative impact is predicted to be of local to regional spatial extent, short term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after surveys have ceased). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The cumulative magnitude was therefore considered to be low.

Sensitivity of the receptors

767. The sensitivity of marine mammals to elevated underwater noise due to site-investigation surveys is as described in paragraphs 355 et seq.
768. All receptors are deemed to have some resilience to cumulative behavioural disturbance, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

769. Overall, the magnitude of the cumulative effect is deemed to be low and the sensitivity of the receptor is 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

770. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Injury And Disturbance From Underwater noise Generated During Vessel Use And Other Noise Producing Activities

771. The risk of injury in terms of PTS to marine mammal receptors as a result of underwater due to vessel use and other activities would be expected to be localised to within the boundaries of the respective projects. The assessment for the Array found that the impact ranges for PTS were extremely small (maximum at 15 m for harbour porpoise) and the number of animals impacted was less than one for all species, as discussed in paragraph 384 et seq., and the magnitude of the impact with respect to auditory injury occurring in marine mammals has been assessed as low. Furthermore, it is expected that all projects will adhere to project-specific mitigation plans to reduce the potential risk of auditory injury.
772. Therefore, there is no potential for cumulative impacts for injury from elevated underwater noise due to vessel use and the cumulative assessment provided in paragraph 737 et seq. focuses on disturbance only.

                        Tier 1

Construction phase

Magnitude of impact

773. One Tier 1 project was identified with potential for cumulative effects associated with this impact within the 50 km buffer, in the regional marine mammal study area:

• Proposed offshore export cable corridor(s) (construction and operation and maintenance phases).

774. As discussed in paragraph 592, there is uncertainty of the final design and location details of the Proposed offshore export cable corridor(s) and therefore it is not possible to provide a quantitative assessment but it can be reasonably assumed vessel noise will be assessed in the EIA.
775. The Proposed offshore export cable corridor(s) (2030 to 2037) and operation and maintenance phase (2037 onwards) overlaps with the construction phase of the Array, by seven years (2031 to 2036). The highest number of vessels movements was predicted during the construction phase of the Array, and it is likely this would be the case for the Proposed offshore export cable corridor(s) construction also, leading to an uplift in the number of vessels from the baseline. Whilst there is no quantitative information available for noise disturbance ranges for offshore wind farms included in this CEA, it is anticipated that there will be a similar scale of effects with respect to noise effects as those described for Array alone (paragraph 387 et seq.).
776. Whilst the Proposed offshore export cable corridor(s) will overlap directly spatially with the Array at the closest point, the cable route will extend further from the Array with vessels following existing routes or confined cable routes and therefore cumulative effects of disturbance are minimal and reduce with further distance from the array. Based upon the results of the Array assessment, disturbance could occur over larger ranges compared to PTS, with underwater noise modelling predicted a range of 3,259 m disturbance range for vessels such as CTVs, Service Operation Vessels, support vessels, CSVs, trenching support vessels, UXO clearance vessel, PLGR Vessel, DSVs, SOV vessels and support vessels (described in Table 10.49   Open ▸ ) and therefore, only disturbance effects (rather than PTS) are likely to occur cumulatively (see paragraph 772).
777. Given that construction activities for other offshore wind projects in the region will have been well underway by 2031 when the Array construction phase begins, and that this is already an area of high vessel traffic (see paragraph 387 et seq. for more details), it can be anticipated that marine mammals present in the vicinity of the Array demonstrate some degree of habituation to vessel noise.
778. Vessel movements will be confined to the Ossian Array and Proposed offshore export cable corridor(s) and will follow existing shipping routes to/from port. In the longer-term, there may be increases in wind farm related traffic associated with the ScotWind developments north and east of the Array. However, given the lack of publicly available data associated with these developments it was not possible to make any quantitative assumptions. It has been assumed that future case traffic growth is likely to fluctuate depending on seasonality and cargo and industry trends.
779. Given the minor temporal overlap (in the scheme of the total project lifetime) in construction activities associated with the relevant projects will not add substantially to the total number of vessel round trips associated with the Array, the magnitude of the impact will not be substantially greater than that assumed for the project alone.
780. The cumulative impact is predicted to be of local to regional spatial extent in the context of the geographic frame of reference, medium-term duration, intermittent and the effects of behavioural disturbance are reversible (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly. The magnitude is therefore, considered to be low.

Sensitivity of the receptors

781. The sensitivities of marine mammals to cumulative disturbance from elevated underwater noise during vessel activity and other noise producing activities are as previously described for the assessment of the Array alone (paragraph 396) for the construction phase and therefore is not repeated here.
782. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

783. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

784. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Operation and maintenance phase

Magnitude of impact

785. One Tier 1 project was identified with potential for cumulative effects associated with this impact within the 50 km buffer, in the regional marine mammal study area:

• Proposed offshore export cable corridor(s) (construction and operation and maintenance phases).

786. The maximum design scenario for the operation and maintenance phase of the Array is presented in Table 10.17   Open ▸ with up to 352 return trips per year over the operational lifetime (35 years). Vessel use during the operation phase of the Array is described in more detail in paragraph 416 et seq. The impacts due to disturbance to marine mammals from vessel use and other activities for the Array alone during the operation and maintenance phase were assessed as negligible to minor. The uplift in vessel activity during the operation and maintenance phase is considered to be relatively small in the context of the baseline levels of vessel traffic in the vicinity and within the site boundary (see paragraph 381).
787. Vessels involved in the operation and maintenance of other projects will include a similar suite of vessels as those described for the Array alone (see paragraph 384 et seq.), such as vessels used during routine inspections, repairs and replacement of equipment, major component replacement, painting or other coatings, removal of marine growth and replacement of access ladders. Given that the number of vessel round trips and their frequency is much lower for the operation and maintenance phases compared to construction phases of the respective projects, the magnitude of the impact for disturbance as a result of elevated underwater noise due to vessel use and other activities, for all marine mammal receptors, is expected to be less than that assessed for the construction phase. However, the duration of the effect will be longer (over the 35-year operating lifetime of the Array) and therefore a precautionary approach has been taken in assessing the magnitude.
788. There is the potential for the operation and maintenance phase of the Array to temporally overlap with the operation and maintenance phase and decommissioning phase of the Proposed offshore export cable corridor(s). The operational lifetime of the Proposed offshore export cable corridor(s) is expected to run from 2037 to 2066. Vessel numbers for decommissioning are likely to be at worst, similar to those for construction phases, and it is expected animals will have some degree of habituation to vessel traffic that has been present throughout the operation and maintenance phases of CEA projects. Additionally, it can be expected that after more than ten years of construction activities taking place in the wider vicinity of the Array (within the regional marine mammal study area), marine mammals may have further habituated to higher vessel numbers.
789. Therefore, the cumulative magnitude of the impact of the operation and maintenance phase as a result of elevated underwater noise due to vessel use, for all marine mammal receptors, is considered to be equivalent to and potentially lower than the maximum design scenario effects assessed for the construction phase.
790. The cumulative effect is predicted to be of local to regional spatial extent in the context of the geographic frame of reference, long term duration, intermittent and the effects of behavioural disturbance are of high reversibility (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly. The magnitude is therefore, considered to be low.

Sensitivity of the receptors

791. The sensitivity of marine mammals to cumulative disturbance from elevated underwater noise due to vessel use and other activities is as described in paragraph 781 et seq. for the construction phase.
792. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

793. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

794. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Decommissioning phase

Magnitude of impact

795. During the decommissioning phase there will be a range of vessels used for decommissioning activities such as removal of foundations, cables and cable protection. Noise from vessels is assumed to be as per vessel activity described for construction phase.
796. All Tier 1 projects screened into the CEA and within the 50 km buffer for vessel noise are expected to have undergone or commenced decommissioning by the commencement of the decommissioning phase of the Array and therefore the impact is not expected to differ or be substantially greater than that assessed for the decommissioning phase of project alone (paragraph 434). Additionally, it can be expected that after several decades of construction and operation and maintenance activities taking place in the wider vicinity of the Array (i.e. within the regional marine mammal study area), marine mammals may have further habituated to higher vessel numbers.
797. The cumulative impact (elevated underwater noise during vessel use and other noise producing activities) is predicted to be of local to regional spatial extent in the context of the geographic frame of reference, medium-term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly. The magnitude was therefore considered to be low.

Sensitivity of the receptors

798. The sensitivities of marine mammals to cumulative disturbance from elevated underwater noise during vessel activity and other noise producing activities are as previously described above for the assessment of the array alone (paragraph 396) for the construction phase and therefore is not repeated here.
799. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

800. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

801. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

                        Tier 2

Construction phase

Magnitude of impact

802. There was one Tier 2 project identified within the 50 km buffer considered for potential for cumulative effects associated with this impact:

• Morven BP-EnBW.

803. The construction of the Array, together with construction phase of Tier 1 and Tier 2 projects ( Table 10.52   Open ▸ ) may lead to cumulative underwater noise generated during vessel use and other noise producing activities. Morven BP-EnBW is located within 50 km of the Array (5.5 km), all other Tier 2 Projects are located over 50 km away. The other Tier 2 Projects which are located >50 km from the Array are considered to be located at a distance great enough that cumulative impacts are highly unlikely.
804. The Morven Offshore Scoping Report scopes in disturbance to marine mammals from vessel use and other (non-piling) sound producing activities for all phases of the Morven Offshore Wind Project (Morven Offshore Wind Limited, 2023). There is however no information on the numbers and types of vessels which will be associated with the construction phase of the Morven Offshore Wind Project. Based upon what the Array assessment presented, disturbance could occur over larger ranges compared to PTS, with underwater noise modelling predicted a range of 3,259 m disturbance range for vessels and therefore given Morven Offshore Wind Project is located 5.5 km from the Array it is unlikely disturbance ranges will significantly overlap. As outlined in paragraph 778 vessel movements will be confined to the array areas and/or offshore export cable corridor routes and will follow existing shipping routes to/from port. In the longer-term, there may be increases in wind farm related traffic associated with the ScotWind developments north and east of the Array. However, given the low data confidence associated with these developments it was not possible to make any quantitative assumptions. It has been assumed that future case traffic growth is likely to fluctuate depending on seasonality and cargo and industry trends.
805. The cumulative impact (elevated underwater noise during vessel use and other noise producing activities) is predicted to be of local to regional spatial extent in the context of the geographic frame of reference, medium-term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The magnitude was therefore considered to be low.

Sensitivity of the receptors

806. The sensitivities of marine mammals to cumulative disturbance from elevated underwater noise during vessel activity and other noise producing activities are as previously described above for the assessment of the Array alone (paragraph 396) for the construction phase and therefore is not repeated here.
807. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

808. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

809. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Operation and maintenance phase

Magnitude of impact

810. There was one Tier 2 project identified within the 50 km buffer considered for potential for cumulative effects associated with this impact:

• Morven BP-EnBW.

811. The construction of the Array, together with construction phase of Tier 1 and Tier 2 projects ( Table 10.52   Open ▸ ) may lead to cumulative underwater noise generated during vessel use and other noise producing activities. Morven BP-EnBW is located within 50 km of the Array, all other Tier 2 Projects are located over 50 km away. The other Tier 2 Projects which are located >50 km from the Array are considered to be located at a distance great enough that cumulative impacts are highly unlikely.
812. There is the potential for the construction phase of Morven BP-EnBW to overlap with the operation and maintenance phase of the Array. However, as described in paragraph 786, maintenance of cables or turbines typically involves considerably smaller numbers of vessels and round trips compared to construction. Considering the vessel activity within the North Sea, it is anticipated that these will not add substantially to the number of vessels present within the site boundary during the operation and maintenance phases of the Array, Tier 1 and Tier 2 projects and that the potential for cumulative effects is unlikely.
813. It should also be considered that during the operation and maintenance phase of the Array some of the Tier 2 projects may be decommissioned. There may be an increase in vessel numbers associated with the decommissioning phases of the Tier 2 projects outlined above. However, as outlined in paragraph 839, considering the vessel activity within the North Sea, it is anticipated that these will not add substantially to the number of vessels present within the site boundary during the operation and maintenance phases of the Array and will consist of considerably less vessels than the construction phases.
814. The cumulative impact (elevated underwater noise during vessel use and other noise producing activities) is predicted to be of local to regional spatial extent in the context of the geographic frame of reference, long term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The magnitude was therefore considered to be low.

Sensitivity of the receptors

815. The sensitivities of marine mammals to cumulative disturbance from elevated underwater noise during vessel activity and other noise producing activities are as previously described for the assessment of the Array alone (paragraph 396) for the construction phase and therefore is not repeated here.
816. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

817. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

818. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

Decommissioning phase

Magnitude of impact

819. There was one Tier 2 project identified within the 50 km buffer considered for potential for cumulative effects associated with this impact:

• Morven BP-EnBW.

820. Decommissioning at Morven is likely to occur at a similar time to that of the Array. On the basis of a 35 year operational lifetime, decommissioning will not occur at the Array until 2074. There will therefore be no temporal overlap between construction activities at Tier 2 projects and decommissioning at the Array. Cumulative effects from underwater noise generated during vessel use and other noise producing activities are not anticipated.
821. The cumulative impact (elevated underwater noise during vessel use and other noise producing activities) is predicted to be of local to regional spatial extent, medium-term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly. Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The magnitude was therefore considered to be low.

Sensitivity of the receptors

822. The sensitivities of marine mammals to cumulative disturbance from elevated underwater noise during vessel activity and other noise producing activities are as previously described for the assessment of the Array alone (paragraph 396) for the construction phase and therefore is not repeated here.
823. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

824. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is 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

825. No marine mammal mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 10.10) is not significant in EIA terms.

                        Tier 3

Construction phase

Magnitude of impact

826. There were three Tier 3 projects identified within the 50 km buffer considered for potential for cumulative effects associated with this impact:

• Bellrock Offshore Wind Farm;
• Bowdun Offshore Wind Farm;
• Campion Offshore Wind Farm; and
• Morven BP-EnBW Offshore Export Cable Corridor.

827. Tier 3 projects are in a pre-application phase and no EIA Scoping Report or EIA Report is available to inform a quantitative assessment. Therefore, a qualitative assessment is provided below.
828. The construction of the Array, together with construction phase of Tier 1, Tier 2 and Tier 3 projects ( Table 10.52   Open ▸ ) may lead to cumulative underwater noise generated during vessel use and other noise producing activities. Bellrock Offshore Wind Farm, Bowdun Offshore Wind Farm, Campion Offshore Wind Farm and Morven BP-EnBW Offshore Export Cable Corridor are all located within 50 km of the Array, all other Tier 3 projects are located over 50 km away. The other Tier 3 projects which are located >50 km from the Array are considered to be located at a distance great enough that cumulative impacts are highly unlikely.
829. There is no information in the public domain on potential numbers of vessels associated with the construction phase of Bellrock Offshore Wind Farm. If any overlap of the construction phases were to occur, the uplift in vessels would be primarily restricted to within the relevant discrete project footprints, with the implementation of standard industry measures such as PAM and MMOs2 the potential for cumulative effects is very low. Therefore, it is anticipated that these will not add substantially to the number of vessels present within the site boundary during the construction of the Array and that the potential for cumulative effects is unlikely.
830. There is no information in the public domain on potential numbers of vessels associated with the construction phase of Campion Offshore Wind Farm. If any overlap of the construction phases were to occur, the uplift in vessels would be primarily restricted to within the relevant discrete project footprints, with the implementation of standard industry measures such as PAM and MMOs2 the potential for cumulative effects is very low. Therefore, it is anticipated that these will not add substantially to the number of vessels present within the site boundary during the construction of the Array and that the potential for cumulative effects is unlikely.
831. The construction phase of Bowdun Offshore Wind Farm may overlap with the construction phase of the Array. There is no information in the public domain on potential numbers of vessels associated with the construction phase of Bowdun Offshore Wind Farm, however the uplift in vessels would be primarily restricted to within the relevant discrete project footprints, with the implementation of standard industry measures such as PAM and MMOs2 the potential for cumulative effects is very low. Therefore, it is anticipated that these will not add substantially to the number of vessels present within the site boundary during the construction of the Array and that the potential for cumulative effects is unlikely.
832. There is no information in the public domain on potential numbers of vessels associated with the construction phase of Morven BP-EnBW Offshore Export Cable Corridor. If any overlap of the construction phases were to occur, the uplift in vessels would be primarily restricted to within the relevant discrete project footprints, with the implementation of standard industry measures such as PAM and MMOs2 the potential for cumulative effects is very low. Therefore, it is anticipated that these will not add substantially to the number of vessels present within the site boundary during the construction of the Array and that the potential for cumulative effects is unlikely.
833. The cumulative impact (elevated underwater noise during vessel use and other noise producing activities) is predicted to be of local to regional spatial extent in the context of the geographic frame of reference, medium-term duration, intermittent and the effect of behavioural disturbance is of high reversibility (with animals returning to baseline levels soon after they moved from the impact zone). It is predicted that the impact will affect the receptor directly Whilst there may be effects at an individual level, these are not predicted to be at a scale that would lead to any population-level effects. The magnitude was therefore considered to be low.

Sensitivity of the receptors

834. The sensitivities of marine mammals to cumulative disturbance from elevated underwater noise during vessel activity and other noise producing activities are as previously described above for the assessment of the array alone (paragraph 396) for the construction phase and therefore is not repeated here.
835. All marine mammals are deemed to have some resilience to cumulative behavioural disturbance from vessel noise, high recoverability and adaptability and high international value. The sensitivity of the receptor is therefore, considered to be medium.

Significance of effect

836. Overall, the magnitude of the cumulative impact is deemed to be low and the sensitivity of the receptor is considered to be medium. The cumulative effect will, therefore, be of minor adverse significance, which is not significant in EIA terms.