4 Assessment Information (Stage 8)
4.1.1 Acknowledging case-law judgements that took place in 2018, it was recommended that Stages 6 and 7 of the plan-level HRA process were not formally considered (see Section 1.3). Instead the process (as shown in Figure 1) moves from Stage 5 directly to Stage 8 (assessment), followed by consideration of mitigation (Stage 9). Stage 10 encompasses the provision of the draft HRA record (this document) (see Section 1.3).
4.1.2 The following sections of the report (Sections 4 to 10) encompass the assessment of the screened in European/Ramsar sites and the relevant interest features (see Table C1) (Stage 8). This includes consideration of in-combination effects (Section 10) before discussing mitigation and the application of suitable measures at a plan-level (Section 11).
4.1.3 The assessment methodology is detailed within the pre-screening report (Section 4.9, Appendix A). A summary of the key steps is outlined below:
- Step 1: Impact pathways review - Identification of the impact pathways that are relevant for offshore wind development;
- Step 2: Identify activities to which features are sensitive - A review of the activities involved in offshore wind development, and the environmental changes arising, which could have an impact on European/Ramsar sites or interest features via the identified impact pathways;
- Step 3: Activity-based screening of European/Ramsar Sites – Identification (screening) of those European/Ramsar sites and their relevant interest features for which there is a LSE, or for which a LSE cannot be excluded, from the activities and impact pathways;
- Step 4: Detailed pathway-feature sensitivity review - A review of the sensitivities of the relevant interest features to the identified impact pathways and activities; and
- Step 5: Assessment of the potential effects on European/Ramsar sites - Assessment of impacts via each of the activities associated with offshore wind development both alone and in-combination with other extant plans or projects. This is followed by the identification of available plan-level mitigation measures which ensure that the Sectoral Offshore Wind Plan activities have no AEOI.
4.1.4 Steps 1-3 were carried out during the pre-screening (steps 1 and 2) (Appendix A) and screening (step 3) stages (see Sections 2 and 3; and Appendices C and D). The relevant generic impact pathways are as identified in the pre-screening (see Table A1 in Appendix A), as are the individual activities to which features are sensitive (see Table A2 in Appendix A). These tables have been referred to during subsequent steps; however, to facilitate cross-referral the generic impact pathways identified are provided below (Table 2).
Table 2. Generic impact pathways associated with the Draft Plan
|Pathway Ref No.||Potential Issue/Sensitivity Category||Impact Pathway||Impact Summary|
|Categories to Deterioration or Disturbance||Code||Impacts arising from Plan Activity (Summary Impact Pathway Description)|
|1||Physical Loss/Gain of habitat (loss of habitat in development footprint)||PLG||Loss of coastal and offshore habitat due to installation of devices, cables and cable armouring from the installation, operation and decommissioning of these structures.||Loss of coastal/offshore seabed within development footprint|
|2||Physical Loss/Gain of habitat (direct change to habitat around the development footprint)||PLG||Loss of foraging areas from reduction in coastal and offshore habitat due to installation of devices and cable armouring both at the development footprint and outside these areas from associated scour and indirectly from changes to the hydrodynamic regime, as well as from chains anchoring devices disturbing seabed habitat during operation.||Loss of coastal/offshore foraging areas within development footprint|
|3||Physical Loss/Gain of habitat (direct change to habitat around the development footprint)||PLG||Presence of structures on or above seabed for the duration of the project resulting in changes to prey and species behaviour (e.g. acting as FAD (Fish Aggregating Device), artificial reef or bird roost).||Loss or gain of habitat from introduced structures causing species change|
|4||Physical Damage to habitat (indirect and temporary damage to marine habitat)||PD||Changes to coastal and offshore habitat as result of damage from baseline surveys (e.g. boreholes/trawls); from equipment use causing abrasion, damage or smothering during installation and from maintenance and removal of cables/devices (e.g. jack-up legs, vessels, anchors, mooring chain).||Damage to coastal/offshore seabed during all project phases|
|5||Physical Damage to habitat (indirect and longer-term damage to habitat)||PD||Changes to coastal and offshore habitat as a result of alterations to the wave climate or hydrodynamic regime from the presence of devices, power cables or cable armouring causing physical changes (including changes to sediment transport and/or sediment scour.||Damage to coastal/offshore seabed from hydrodynamic changes|
|6||Physical Damage to habitat (indirect and temporary damage to habitat)||PD||Reduction in quality of foraging areas as result of damage to coastal and offshore habitat from baseline surveys (e.g. boreholes and trawls); from equipment use causing abrasion, damage or smothering during installation; from maintenance and removal of cables/devices or from scour, sediment transport and hydrodynamic change, and damage from chains anchoring devices during operation.||Damage to coastal/offshore foraging areas during all project phases|
|7||Physical Damage to species (direct and temporary damage to habitat)||PD||Damage to seal haul out locations during the installation, decommissioning and operation of the cables and cable armouring.||Damage to seal haul out from cables or pipelines|
|8||Physical Damage to species (direct damage to species from collision risk)||PD||Collision risk and possible mortality of species due to the presence of devices or from vessels travelling to and from the site (including above and below water collision risk and the influence of lighting); risk of entanglement following a collision with power cables or mooring elements.||Damage to species from collision, entanglement or disorientation|
|9||Non-Physical disturbance (barrier to species movement)||NPD||Presence of structures or disturbance (noise or visual) resulting in a barrier to movement, migratory pathways and/or access to feeding grounds depending on array design.||Disturbance from introduced structures causing barrier to mobile species movement|
|10||Non-Physical disturbance (disturbance to species)||NPD||Visual disturbance and exclusion from areas as a result of surveying, cable and device installation/operation and decommissioning activities and movements of vessels.||Disturbance (visual) from activities during all project phases|
|11||Non-Physical disturbance (disturbance to species)||NPD||Noise/vibration disturbance and exclusion from areas as a result of vessels and other activities during survey work (e.g. seismic exploration and geophysical surveys), construction (e.g. piling, drilling, cable laying), operation (e.g. device noise), maintenance or decommissioning.||Disturbance (noise) from activities during all project phases|
|12||Non-Physical disturbance (disturbance to species)||NPD||Impacts from Electromagnetic Fields (EMF) and thermal emissions on benthic invertebrates and electromagnetically sensitive fish and cetaceans interfering with prey location and mate detection in some species and creating barriers to migration.||Disturbance (EMF and thermal emissions) from activities during all project phases|
|13||Non-Physical disturbance (exclusion/ displacement of species)||NPD||Presence of structures resulting in an exclusion/displacement of a species from the area.||Disturbance from introduced structures causing exclusion/ displacement of species|
|14||Toxic Contamination (reduction in water quality)||TC||Spillage of fluids, fuels and/or construction materials during installation or removal of structures (devices and cables) or during survey/maintenance.||Contamination during surveys or maintenance activities|
|15||Toxic Contamination (reduction in water quality)||TC||Release of contaminants associated with the dispersion of suspended sediments during installation or removal of structures (devices and cables).||Contamination during installations/removal of structures|
|16||Non-Toxic Contamination (elevated turbidity)||NTC||Increase in turbidity (and possibly reduced dissolved oxygen) associated with the release of suspended sediments during installation or removal of structures (devices and cables).||Non-toxic contamination from increases in turbidity|
|17||Biological Disturbance (introduction of non-native species)||BD||Introduction of new structures on the seabed providing new substratum that facilitates the colonisation and ingress of invasive non-native species.||Biological disturbance from non-native species on substratum|
|18||Biological Disturbance (introduction of non-native species)||BD||Introduction and ingress of invasive non-native species as biofouling species on the surfaces of vessels or construction plant.||Biological disturbance from non-native species on vessels|
4.1.5 Step 4 considers those relevant project-level activities associated with the Draft Plan that have been screened into the assessment (see Section 4.13, Appendix A). The results are presented in a series of ‘pathway-sensitivity’ tables, within the main body of this document, for each key interest feature group. During this process, acknowledgement is given to the latest scientific evidence to understand the likely sensitivity of a feature to a specific impact pathway.
4.1.6 The ‘pathway-sensitivity’ tables are structured according to the standard Natura 2000 sensitivity categories (see Section 3.2.3, Appendix A):
- Physical Loss/Gain of habitats from removal or smothering;
- Physical Damage of habitats and species from siltation, erosion or physical injury/death;
- Non-Physical (Indirect) Disturbance from noise or visual presence and reduced availability or exclusion/displacement of species, including prey;
- Toxic Contamination from the introduction of synthetic compounds, introduction of non-synthetic contaminants;
- Non-Toxic Contamination from nutrient enrichment, organic enrichment, changes in suspended sediment and turbidity, changes in salinity or changes to the thermal regime; and
- Biological Disturbance from introduction of microbial pathogens, the introduction of invasive non-native species and translocation, or from selective extraction of selected species.
4.1.7 The tables indicate which project phases the impact pathways are relevant to (i.e. survey, construction, operation or decommissioning) and the sensitivity levels (high, medium or low) associated with each of these phases. The impact pathway reference numbers are included within each pathway-sensitivity table, these numbers relating to the generic impact pathways identified in Step 1 (see Table 2).
4.1.8 The determination of the sensitivity of a feature to a given impact pathway has considered both the function of the sensitivity to the pressure and also the likely level of exposure. In the case of mobile features an individual may have a high sensitivity to a pressure but exposure to the pressure may be minimal, especially at the population level.
4.1.9 Impact pathways arising as a result of the development footprint are considered to occur in the operational rather than construction phase, reflecting the longer-term nature of the impact.
4.1.10 Step 5 assessed the impacts that could occur via each of the identified pathways against the European/Ramsar site’s conservation objectives. However, given the large number of sites screened into the assessment, a series of generic conservation objectives were applied across all sites (see Section 4.14.2, Appendix A).
4.1.11 Based on these generic conservation objectives, the potential effects on the European/Ramsar sites via each of the relevant impact pathways were reviewed. An initial view was then taken about the effect on site integrity of the Sectoral Offshore Wind Plan both alone and in-combination (Section 10) with other extant plans or projects.
4.1.12 It has already been agreed through discussion with the PSG (Section 2.2.3, Appendix B) that because of the uncertainties associated with the Draft Plan (including the scale and location of future developments within the DPOs and the nature of the future technologies that will be used), it will not be possible to definitively conclude that there will be no AEOI from the Plan. Therefore, there will be a need for appropriate and meaningful mitigation measures to accompany the Draft Plan.
4.1.13 Accordingly, plan-level mitigation measures were identified to avoid an AEOI (Section 11), in fulfilment of Stage 9 of the HRA process (Figure 1). The Draft Plan was then re-assessed following the application of these mitigation measures and the conclusions provided (Section 12).
4.2 Key Issues
4.2.1 For plan-level assessments, it is recognised that there is often limited information on the precise location and scale of development or about the relevant construction methods and associated activities. This is typically the case at a plan-level and while the 17 DPOs have been agreed and their locations are indicated (e.g. see Figure 3), no project-level details are currently available for these DPOs. The uncertainty about project level details has duly been recognised throughout the screening and assessment stages.
4.2.2 The assessment has, therefore, taken account of the likely range of development options and activities based on previous wind energy projects that have been carried out or are proposed. It also acknowledges the potential for floating turbine structures to allow exploitation of deep-water sites.
4.2.3 The Sectoral Marine Plan for Offshore Wind has a relatively broad spatial scope and a long-term temporal component which can each influence the range of potential impacts. The temporal aspects of the Draft Plan’s implementation, and the scale of the impacts associated, will also be influenced by technological advances that take place over time with respect to wind energy developments. These will influence the scale of potential impacts as well as the distances offshore that developments can be undertaken while remaining commercially viable. It will also influence the needs for future upgrading of wind generating technologies in established areas. In this context, therefore, it has been essential for these assessments that no specific assumptions about project-level activities (e.g. device type or generation capacity) are made in the absence of available information and that the potential impacts that are identified encompass the full envelope of potential change (through the application of a precautionary approach).
4.2.4 This potential envelope of change has therefore been determined to identify the potential effects on features. On this basis, screening matrices and maps for the individual DPOs (see Appendices D and E) have identified where features within individual sites are at risk of LSE (or where the risk of LSE cannot be excluded). The detailed assessment presented in this report has built on this screening process by considering the particular environmental pressures/changes that give rise to these risks and then providing a generic assessment of the impact having regard to the typical conservation objectives (see Section 4.14.2, Appendix A).
4.2.5 Based on the approaches adopted for previous plan-level HRA work, the results of this phased assessment work have been presented in a series of tables/matrices throughout the following sections (Section 5 to 9).