Colonisation of foundations, scour protection and cable protection
564 The introduction of hard substrate into areas of predominantly soft sediments has the potential to alter community composition and biodiversity. This impact is only relevant to the operation and maintenance phase as it takes time for colonisation to establish post construction. The presence of the following projects has the potential to lead to in-combination effects arising from the colonisation of hard structures:
- Tier 2:
– Inch Cape Offshore Wind Farm;
– Neart na Gaoithe Offshore Wind Farm;
– Seagreen 1;
– Seagreen 1A Project;
– Seagreen 1A Export Cable Corridor;
– Eastern Link 1; and
– Eastern Link 2.
- Tier 3:
– Cambois connection.
565 The assessment of effects on diadromous fish from the Proposed Development alone concluded that Annex II diadromous fish species have low vulnerability, high recoverability, and therefore low sensitivity to colonisation of foundations, scour protection and cable protection. This is because, diadromous fish are only likely to interact with the Proposed Development when passing through the area during migrations to and from rivers located on the east coast of Scotland. In most cases, it is expected that diadromous fish are unlikely to utilise the increase in hard substrate from the Proposed Development for feeding or shelter opportunities. Whilst there is potential for increased predation of diadromous fish by marine mammal species attracted to offshore wind farm structures, again impacts on diadromous fish are not anticipated to be significant given diadromous fish spend little time in coastal waters and are unlikely to spend time foraging around wind turbines foundations and therefore are at low risk from increased predation.
566 Whilst the in-combination effect is predicted to be of long-term duration and continuous, it is predicted to be of local spatial extent, of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect.
567 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tweed SAC as a result of colonisation of foundations, scour protection and cable protection impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.
Site conclusion
568 In conclusion, with reference to the conservation objectives set for the Annex II diadromous fish features of this site, and dependant qualifying features (i.e. freshwater pearl mussel) and the information presented in sections 12.3, 12.4 and 12.5.3, it can be concluded beyond all reasonable scientific doubt that there will be no Adverse Effect on Integrity on the River South Esk SAC in respect of the Atlantic salmon and freshwater pearl mussel qualifying interests,.
569 This finding is in relation to potential impacts associated with the Proposed Development during construction, decommissioning and operation and maintenance, acting alone and or in-combination.
12.5.4 River Tay SAC
European site information
570 At its closest point, the River Tay SAC is located 87.15 km from the Proposed Development array area and 102.67 km from the Proposed Development export cable corridor. The site comprises the longest river in Scotland, originating in western Scotland, flowing easterly across the Highlands before becoming tidal at the Firth of Tay. The site covers an area of 9461.63 ha. The site is designated for Annex I habitats and Annex II species including three diadromous fish species: sea lamprey, river lamprey and Atlantic salmon.
571 Further information on this European site is presented in appendix A.
Conservation objectives
572 Conservation objectives for the River Tay SAC have been developed by NatureScot as part of a Conservation Advice Package (NatureScot, 2020). Conservation objectives for all qualifying species features are:
- to ensure that the qualifying features of River Tay SAC are in favourable condition; and
- to ensure that the integrity of the River Tay is maintained by meeting objectives 2a, 2b and 2c for each qualifying feature and make an appropriate contribution to achieving favourable conservation status.
573 Conservation objectives for sea lamprey and river lamprey are as follows:
- 2a. Maintain the population of the lamprey species’ as viable components of the site;
- 2b. Maintain the distribution of the lamprey species throughout the site; and
- 2c. Maintain the habitats supporting the lamprey species within the site, and availability of food.
574 Conservation objectives for Atlantic salmon are as follows:
- 2a. Maintain the population of Atlantic salmon, including range of genetic types, as a viable component of the site;
- 2b. Maintain the distribution of Atlantic salmon throughout the site; and
- 2c. Maintain the habitats supporting Atlantic salmon within the site and availability of food.
575 The condition of sea and river lamprey was assessed in 2007 and Atlantic salmon condition was assessed in 2011. The outcomes of these feature condition assessments were as follows:
- Sea lamprey: favourable maintained;
- River lamprey: favourable maintained; and
- Atlantic salmon: favourable maintained.
Features and effects for assessment
576 Table 12.19 Open ▸ summarises the LSEs that were identified for the Annex II diadromous fish species features of the River Tay SAC and the features and effects which have been considered in the assessment of Adverse Effects on Integrity for this site.
Table 12.19: Summary of Features and Effects Considered in the Assessment of Adverse Effects on Integrity for the River Tay SAC
Construction and decommissioning
Injury and/or disturbance from underwater noise and vibration
Atlantic salmon
577 Atlantic salmon which are a Group 2 fish in terms of hearing sensitivity have relatively low sensitivity to underwater noise. The results of project specific modelling, as discussed in paragraphs 283 to 287, indicates that injury and/or mortality to Atlantic salmon can be expected for individuals within approximately 228 m of the piling.
578 A temporary hearing impairment (i.e. TTS), from which animals will recover, was predicted to occur out to a maximum range of 4,161 m for Group 2 fish from piling operations. For concurrent piling, whilst mortality and recoverable injury ranges were unchanged (i.e. 228 m for Group 2 fish) TTS ranges for Group 2 fish may be increased to up to 7.1 km from the piling location for the maximum energy scenario. However, as discussed in paragraph 286, the risk of fish injury will be considerably lower due to hammer energies being considerably lower than the absolute maximum modelled. Additionally, the expected fleeing behaviour of fish from the area affected when exposed to high levels of noise and the soft start procedure, which will be employed for all piling, mean that fish will have sufficient time to vacate the areas where injury may occur prior to noise levels reaching that level.
579 As discussed in paragraph 268, pre-construction UXO clearance may also lead to injury and/or disturbance to Atlantic salmon. Detonation of UXO would represent a short term (i.e. seconds) increase in underwater noise which will be elevated to levels which may result in injury or behavioural effects on fish. The results of project specific modelling, discussed in paragraphs 288 to 289 indicate that mortality/mortal injury for all fish would occur within a range of 30-45 m from the source following low order detonation (the dominant method of UXO detonation). Higher order detonations may also occur if low order is not successful or unintentionally as part of the low order process. In this case mortality would occur within 410-680 m of the noise source.
580 However, due to the nature of diadromous fish species such as Atlantic salmon being highly mobile and tending to only utilise the environment within the Proposed Development fish and shellfish ecology study area to pass through during migration, significant mortality of Atlantic salmon is not expected.
581 Additionally, available evidence on Atlantic salmon migration patterns from and to Scottish rivers (detailed in section 12.2.5) suggests that Atlantic salmon smolts migrating from rivers take advantage of east flowing currents and cross the North Sea relatively rapidly. Therefore, it is likely that whilst migrating salmon moving to and from the River Tay Estuary will pass through the Proposed Development fish and shellfish ecology study area, either in their outward or inward migration, this migration will be rapid, reducing the potential for interaction with the Proposed Development.
582 In contrast, behavioural effects (including startle response, disruption of feeding or avoidance of an area) in response to piling are expected over much larger ranges of 10 km to 20 km, as discussed in paragraphs 296 to 300. Due to the distance between the Proposed Development array area and the coast, these behavioural impacts are unlikely to cause barrier effects between the Proposed Development and the migration routes of Atlantic salmon along the east coast of Scotland, due to the relatively small area around piling events where noise levels are high enough to cause behavioural responses (as shown in Figure 12.1 Open ▸ and Figure 12.2 Open ▸ ).
583 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced. The Proposed Development does not overlap with the River Tay SAC, so the extent and distribution and the structure and function of Atlantic salmon habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Tay SAC as a result of underwater noise impacts during the construction and decommissioning phases.
Sea lamprey
584 As discussed in section 12.3.1, sea lamprey, which are considered to be a Group 1 fish in terms of hearing sensitivity have relatively low sensitivity to underwater noise. The results of project specific modelling, as discussed in paragraphs 283 to 287, indicates that injury and/or mortality to sea lamprey can be expected for individuals within approximately 138 m of the piling.
585 A temporary hearing impairment (i.e. TTS), from which animals will recover, was predicted to occur out to a maximum range of 4,161 m for Group 1 species from piling operations. For concurrent piling, whilst mortality and recoverable injury ranges were unchanged (i.e. 138 m for Group 1 species) TTS ranges for Group 1 fish (sea lamprey) may increase up to 7.1 km from the piling location for the maximum energy scenario ( Table 12.7 Open ▸ ).
586 However, as discussed in paragraph 286, the risk of fish injury will be considerably lower due to hammer energies being considerably lower than the absolute maximum modelled. Additionally, the expected fleeing behaviour of fish from the area affected when exposed to high levels of noise and the soft start procedure, which will be employed for all piling, mean that fish will have sufficient time to vacate the areas where injury may occur prior to noise levels reaching that level.
587 As discussed in paragraph 268, pre-construction UXO clearance may also lead to injury and/or disturbance to sea lamprey. Detonation of UXO would represent a short term (i.e. seconds) increase in underwater noise which will be elevated to levels which may result in injury or behavioural effects on fish species. The results of project specific modelling, discussed in paragraphs 288 to 289, indicate that mortality/mortal injury for all fish would occur within a range of 30-45 m from the source following low order detonation. Higher order detonations may also occur if low order is not successful or unintentionally as part of the low order process. In this case mortality would occur within 410-680 m of the noise source.
588 However, due to the nature of diadromous fish species such as sea lamprey being highly mobile and tending to only utilise the environment within the Proposed Development fish and shellfish ecology study area to pass through during migration, significant mortality of sea lamprey is not expected. Sea lamprey spend most of their adult life at sea and it has been suggested that they are widely dispersed at sea, possibly feeding in deeper offshore waters (OSPAR Commission, 2009). They are rarely captured in coastal and estuarine waters, suggesting that they are solitary hunters and widely dispersed at sea as opposed to remaining in coastal waters (Marine Scotland Directorate, 2019).
589 In contrast, behavioural effects (including startle response, disruption of feeding or avoidance of an area) in response to piling are expected over much larger ranges of 10 km to 20 km, as discussed in paragraphs 296 to 300. Due to the distance between the Proposed Development array area and the coast, these behavioural impacts are unlikely to cause barrier effects between the Proposed Development fish and shellfish ecology study area and the migration routes of sea lamprey along the east coast of Scotland, due to the relatively small area around piling events where noise levels are high enough to cause behavioural responses (as shown in Figure 12.1 Open ▸ and Figure 12.2 Open ▸ ).
River lamprey
591 River lamprey, like sea lamprey, is classified as a Group 1 fish for the purposes of hearing sensitivity and as such the assessment for sea lamprey presented above in paragraphs 584 to 590 also applies to river lamprey. In addition, due to river lamprey’s preference for estuarine waters, it is unlikely that river lamprey will interact with Proposed Development.
592 The population of river lamprey will be maintained as a viable component of the site and the extent and distribution of river lamprey will not be reduced. The Proposed Development does not overlap with the River Tay SAC so the extent and distribution and the structure and function of river lamprey habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, river lamprey of the River Tay SAC as a result of underwater noise impacts during construction/decommissioning.
Conclusion
593 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Tay SAC, so the extent and distribution and structure and function of supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given the relatively low sensitivity of the qualifying species to underwater noise impacts, the low probability of individuals being present within the ZoI of underwater noise impacts at the time of piling and UXO activities, and the use of soft start procedures allowing individuals to flee areas where they may be exposed to noise levels that would lead to injury, the populations and the distribution of the qualifying species will be maintained.
594 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC as a result of underwater noise impacts with respect to construction and decommissioning of the Proposed Development acting alone.
Increased suspended sediment concentrations and associated sediment deposition
Atlantic salmon
595 As detailed in section 12.3.2, increases in SSC and associated sediment deposition during construction and decommissioning have the potential to cause behavioural responses (avoidance) in migratory fish. This in turn has the potential to result in barriers to migration.
596 The results of project specific modelling summarised in section 12.3.2, indicate that increases in SSC are predicted to be temporary, short-lived and at levels well below those naturally experienced in estuarine environments. Atlantic salmon are expected to have some tolerance to naturally high SSC, given their migration routes typically pass through estuarine habitats which have background SSC which are considerably higher than those expected in the offshore areas of the Proposed Development northern North Sea fish and shellfish ecology study area. As such, no barriers to the migratory patterns of Atlantic salmon are expected.
597 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced. The Proposed Development does not overlap with the River Tay SAC so the extent and distribution and the structure and function of Atlantic salmon habitat will be unaffected. Therefore. There will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Tay SAC as a result of increased SSC and sediment deposition impacts during the construction and decommissioning phases.
Sea lamprey
598 As detailed in section 12.3.2, increases in SSC and associated sediment deposition during construction and decommissioning have the potential to cause behavioural responses (avoidance) in migratory fish. This in turn has the potential to result in barriers to migration.
599 The results of project specific modelling summarised in section 12.3.2, indicate that increases in SSC are predicted to be temporary, short-lived and at levels well below those naturally experienced in estuarine environments. Sea lamprey are expected to have some tolerance to naturally high SSC, given their migration routes typically pass through estuarine habitats which have background SSC which are considerably higher than those expected in the offshore areas of the Proposed Development northern North Sea fish and shellfish ecology study area. As such, no barriers to the migratory patterns of sea lamprey are expected.
600 The population of sea lamprey will be maintained as a viable component of the site and the extent and distribution of sea lamprey will not be reduced. The Proposed Development does not overlap with the River Tay SAC so the extent and distribution and the structure and function of sea lamprey habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, sea lamprey of the River Tay SAC as a result of increased SSC and sediment deposition impacts during the construction and decommissioning phases.
River lamprey
601 River lamprey will have a similar sensitivity to increased SSC as sea lamprey therefore the assessment for sea lamprey, presented in paragraphs 370 to 371, will also apply to river lamprey. In addition, due to river lamprey’s preference for estuarine waters, it is unlikely that river lamprey will interact with elevated SSC arising from the construction or decommissioning of the Proposed Development.
602 The population of river lamprey will be maintained as a viable component of the site and the extent and distribution of river lamprey will not be reduced. The Proposed Development does not overlap with the River Tay SAC so the extent and distribution and the structure and function of river lamprey habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying species of the River Tay SAC as a result of increased SSC and sediment deposition impacts during the construction and decommissioning phases.
Conclusion
603 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the Tay SAC, and so the extent and distribution and structure and function of the supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given that any increases in SSC are predicted to be temporary, short lived and lower than estuarine levels, there will be no barriers to the migration of the qualifying species. As such, the population and the distribution of the qualifying species will be maintained.
604 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC as a result of increased SSC and sediment deposition impacts with respect to construction and decommissioning of the Proposed Development acting alone.
Operation and maintenance
EMF from subsea electrical cabling
Atlantic salmon
605 As discussed in section 12.4.1, the emission of localised EMFs from the operation of inter-array, interconnector and offshore export cables could potentially interfere with the navigation of Atlantic salmon. However, impacts related to EMF are predicted to be of local spatial extent (i.e. within a few metres of buried cables). Given that salmon is a pelagic species, it is unlikely to swim at depths sufficient to detect levels of EMF that would cause behavioural changes during migration. Whilst research shows that undersea power cables can result in altered patterns of salmonid behaviour, these changes are temporary and do not interfere with migration success or population health. Atlantic salmon is therefore deemed to have low sensitivity to, and high recoverability from, EMF.
606 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced. The Proposed Development does not overlap with the River Tay SAC so the extent and distribution and the structure and function of Atlantic salmon habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Tay SAC as a result of EMF from subsea electrical cabling impacts during the operation and maintenance phase.
Sea lamprey
607 As discussed in section 12.4.1, the emission of localised EMFs from the operation of inter-array, interconnector and offshore export cables could potentially interfere with the navigation of sea lamprey. However, the limited available evidence suggests that disturbance to sea lamprey from EMF occurs at intensities considerably higher than those expected from AC subsea cables (see Table 12.14 Open ▸ ). Due to sea lamprey's parasitic nature at sea, attaching to the body of larger, highly mobile species, well above the seafloor also means that they can be expected to rarely be exposed to the EMF at the lowest levels from AC undersea power cables buried in the seafloor. Therefore, any impacts would be localised and transient. Sea lamprey is therefore deemed to have low sensitivity to, and high recoverability from, EMF.
River lamprey
609 River lamprey will have a similar sensitivity to EMF as sea lamprey therefore the assessment for sea lamprey presented in paragraphs 607 and 608 is also applicable to river lamprey. In addition, due to river lamprey's preference for estuarine waters, it is unlikely that river lamprey will interact with Proposed Development fish and shellfish ecology study area.
610 The population of river lamprey will be maintained as a viable component of the site and the extent and distribution of river lamprey and will not be reduced, and the structure and function of river lamprey habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, river lamprey of the River Tay SAC as a result of EMF from subsea electrical cabling impacts during the operation and maintenance phase.
Conclusion
611 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Tay SAC, and so the extent and distribution and structure and function of the supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given any impacts from EMF will be localised and transient and the predicted low sensitivity of the qualifying species to this impact, the population and distribution of the qualifying species will be maintained.
612 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC as a result of EMF impacts with respect to operation and maintenance of the Proposed Development acting alone.
Colonisation of foundations, scour protection and cable protection
Atlantic salmon
613 As discussed in section 12.4.2, colonisation of foundations, scour protection and cable protection, has the potential to result in increased predation on diadromous fish species by marine mammal species within offshore wind farms. It is not certain exactly to what extent seals utilise offshore wind developments (as discussed in paragraph 346) and therefore effects may be site specific. Assuming that seals do utilise offshore wind developments as foraging areas, Atlantic salmon may be impacted by the increased predation in an area where predation was lower prior to development.
614 It is, however, unlikely that this would result in significant predation on Atlantic salmon, as research has shown that Atlantic salmon smolts spend little time in the coastal waters and instead quickly make their way to feeding grounds in the north (as discussed in paragraph 347). Due to the evidence that Atlantic salmon tend not to forage in the coastal waters of Scotland (see paragraph 347), it is unlikely that they will spend time foraging around wind turbine foundations and therefore are at low risk of impact from increased predation from seals and other predators.
615 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced. and the structure and function of Atlantic salmon habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Tay SAC as a result of colonisation of foundation, scour protection and cable protection impacts during the operation and maintenance phase.
Sea lamprey
616 As discussed in section 12.4.2, colonisation of foundation, scour protection and cable protection, has the potential to result in increased predation by marine mammal species within offshore wind farms. Assuming that seals do utilise offshore wind developments as foraging areas, sea lamprey may be impacted by the increased predation in an area where predation was lower prior to development.
617 There is limited available information on the utilisation of the marine environment by sea lamprey, however, as they are parasitic in their marine phase, feeding off larger fish and marine mammals (Hume, 2017), it is not expected that they will be particularly attracted to structures associated with offshore wind developments. Sea lamprey that are likely to interact with the Proposed Development are only likely to do so whilst passing through the area during migrations to and from rivers located on the east coast of Scotland. As such significant predation on sea lamprey is not expected.
River lamprey
619 River lamprey will have a similar sensitivity to colonisation of foundations, scour protection and cable protection impacts as sea lamprey therefore the assessment presented in paragraphs 616 to 618 for sea lamprey is also applicable to river lamprey. In addition, due to river lamprey's preference for estuarine waters, it is unlikely that river lamprey will interact with structures associated with the Proposed Development.
620 The population of river lamprey will be maintained as a viable component of the site and the extent and distribution of river lamprey will not be reduced. and the structure and function of river lamprey habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, river lamprey of the River Tay SAC as a result of colonisation of foundations, scour protection and cable protection impacts during the operation and maintenance phase.
Conclusion
621 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Tay SAC, and so the extent and distribution and structure and function of the supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given the limited interaction between the qualifying species and the Proposed Development significant predation in relation the colonisation of foundations, scour protection and cable protection impact are not expected therefore the population and distribution of the qualifying species will be maintained.
622 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC from colonisation of foundations, scour protection and cable protection impacts with respect to operation and maintenance of the Proposed Development acting alone.
Effects in-combination
623 An assessment of in-combination effects upon the qualifying Annex II diadromous fish species of the Tweed Estuary SAC arising from each identified impact is presented in section 12.5.1. Since the results are generic to diadromous fish species and therefore the results of the assessments for each impact apply to the other SACs, full details of the in-combination assessments are not repeated here for the River Tay SAC. The in-combination effects conclusions for the River Tay SAC are summarised below.
Assessment of in-combination effects during construction and decommissioning
Injury and/or disturbance from underwater noise and vibration
624 There is potential for in-combination effects from injury and/or disturbance from underwater noise and vibration to Annex II diadromous fish during the construction phase of the Proposed Development with activities associated with the following projects:
- Tier 2:
– Inch Cape Offshore Wind Farm; and
– Seagreen 1A Project.
- Tier 3:
– There is no information provided regarding UXO clearance for the Cambois connection therefore no meaningful assessment can be made at this time.
625 As discussed in section 12.5.1, effects in-combination, these projects include similar construction activities as those described for the Proposed Development alone in section 12.3.1, including piling to install wind turbine and OSP/Offshore convertor station platform foundations.
626 Neither Inch Cape Offshore Wind Farm nor Seagreen Alpha/Bravo Offshore Wind Farm EIA Reports predicted significant effects on fish and shellfish receptors. Any effects were predicted to be temporary and reversible following cessation of piling activities. Additionally, the injury ranges reported are likely to be conservative as soft start measures will be implemented as part of the Inch Cape Offshore Wind Farm and Seagreen 1A Project construction programmes, which will reduce the risk of injury considerably. Due to the limited range over which injury effects may occur due to piling activities (i.e. tens to hundreds of metres), mitigation to minimise the potential for injury and the minor overlap in construction phases of the Proposed Development and Inch Cape Offshore Wind Farm and Seagreen 1A Project, in-combination effects are not predicted to result in effects of greater significance than as assessed for the Proposed Development alone.
627 The in-combination effect is predicted to be of regional spatial extent, short term duration and intermittent and of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect.
628 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC as a result of injury and/or disturbance from underwater noise and vibration with respect to the Proposed Development acting in-combination with Tier 2 projects.
Increased suspended sediment concentrations and associated sediment deposition
629 There is potential for in-combination effects from increased SSC and associated sediment deposition impacts to Annex II diadromous fish during the construction phase of the Proposed Development with activities associated with the following projects:
- Tier 2:
– Inch Cape Offshore Wind Farm (construction phase);
– Seagreen 1A Project (construction phase);
– Seagreen 1 (operation and maintenance phase);
– Seagreen 1A Export Cable (operation and maintenance phase);
– Neart na Gaoithe Offshore Wind Farm (operation and maintenance phase);
– Eastern Link 1 (construction phase);
– Eastern Link 2 (construction phase); and
– Eyemouth disposal site.
- Tier 3:
– Cambois connection (construction and operation and maintenance phases).
630 Any increases in SSC and associated sediment deposition for the Proposed Development alone has been assessed as being of local spatial extent, short term duration with high reversibility of any changes to the baseline. Whilst there may be some temporal overlap between the construction phase of the Proposed Development and the projects listed above, any impacts from increased SSC and associated sediment deposition from these projects will also be of limited spatial extent, short-term duration and they are unlikely to interact with the sediment plumes of the Proposed Development.
631 The in-combination effect is predicted to be of local spatial extent, short term duration and intermittent and of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect. As such, there will be no effect on the ability of diadromous fish to migrate to and from the relevant SACs considered within this RIAA.
632 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC as a result of increased SSC and associated sediment deposition impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.