EIRA Methodology

Celtic Sea Floating Offshore Wind

Introduction

1. This section describes how the mitigation categories relevant for each Designated Site and its features are determined. It involves an evaluation of the vulnerability of each qualifying feature to the pressures likely to arise from the installation and operation of export cables and pipelines and their associated infrastructure (“Feature Vulnerability”) together with consideration of the vulnerability of the site as a whole (“Designated Site Vulnerability”). The process is illustrated below and has been used for both the HRA and the MCZ assessments.

Feature Vulnerability

2. The determination of Feature Vulnerability comprises an evaluation of each feature’s sensitivity (“Feature Sensitivity”) to the pressures screened in as well as the nature of a feature’s potential interaction (“Feature Distribution”) with the Export Infrastructure Region.

Feature Sensitivity

3. A feature’s sensitivity is determined based on its sensitivity to specific pressures (as listed in the Principle report  NIRAS, 2022 b) including consideration of its ability to recover from an impact. Sensitivity can mostly be derived from the scientific literature. In some cases, where feature specific information is unavailable, species and habitats with similar characteristics can be used as a proxy. For each pressure screened in, a score of high, medium or low is assigned. A single, overall score for a feature’s sensitivity should be based on the pressure that merits the highest sensitivity score.

Feature Distribution

4. The nature of a feature’s interaction with the Export Infrastructure Region has also been scored as low, medium or high, based on the receptor specific criteria set out in table below.

Criteria applied for feature distribution in relation to the export infrastructure region and designated site. NB All MCZ features follow the same criteria as habitats.

5. The final step is to combine the scores for a feature’s distribution with the scores for a feature’s sensitivity in a matrix to obtain an overall score for the feature’s vulnerability to export cables and pipelines.

Matrix used to define feature vulnerability. Note: any features categorised as VL are not considered further in the assessment

Designated Site Vulnerability

6. For SACs, SPAs, Ramsars and MCZs, Designated Site Vulnerability has been determined on the basis of the condition of the designated sites (“Designated Site Condition”) and any other impacting activities (e.g. from different marine industries) present at each designated site that have the potential to interact in-combination (“Designated Site In-combination”).

Designated Site Condition

7. A review of publicly available designated site information documents has been undertaken to determine the condition of each feature at each designated site. The review identified that the condition of the qualifying features had been inconsistently monitored and that this information was unavailable for many designated sites (i.e. for all SPAs in England and Wales, and all Ramsar sites).

8. In order to assign consistent scores, the following criteria were applied:

  • Low – Designated Sites containing features categorised by the SNCBs as being in Favourable Condition
  • Medium – Information unavailable or ambiguous
  • High – Features clearly categorised by the SNCBs as being in Unfavourable Condition

Designated Site Threats & Pressures

9. A score for Designated Site in-combination risk has been established by interrogating JNCC’s ‘ Natura 2000 Site Summary Spreadsheet ’ for SAC and SPAs. This dataset contains information on the impacts already present at these Designated Sites, and these have already been categorised by JNCC as either low, medium or high. Not all impacts listed were applicable, so they were filtered to include only the following types of activity, which have the potential to cause negative pressures:

  • Mining and quarrying
  • Exploration and extraction of oil and gas
  • Utility and service lines
  • Shipping lanes, ports and marine constructions
  • Discharges
  • Marine Water pollution
  • Wind 

10. A single score (high, medium or low) was assigned to each designated site based on the highest impacting activity present at that site. Ramsar and MCZ In-combination scores have been assigned on the basis of the scores found for overlapping (or closest) SAC or SPA in JNCC’s ‘ Natura2000 Site Summary Spreadsheet  ’. Where there is no overlap, MCZs have been scored as high on a precautionary basis.

11. Designated Site Vulnerability score was established by combining the Designated Site Condition score with the Designated Site In-combination score, as shown in the figure below.

Matrix applied to determine Designated Site Vulnerability

Overall Mitigation Score

12. To determine the overall risk of an AEOSI for each feature/site and thus appropriate mitigation Score, the Feature Vulnerability score and the Designated Site Vulnerability score, were combined as shown below. Here, the Feature Vulnerability score is the most important criterion, however it is noted that features within Protected Sites of high vulnerability will be under more pressure than the same feature found in a healthy, less vulnerable site. In these instances feature vulnerability was used to escalate to a higher mitigation score. For example a feature with a medium vulnerability will be at more risk in a site in poor condition than that in a site of favourable condition and little external pressure. Therefore the Medium risk score for feature vulnerability is increased to High (3) when the site vulnerability is high.

Matrix used to define Mitigation categories 1-3


V2.0 6th March 2023

Criteria applied for feature distribution in relation to the export infrastructure region and designated site. NB All MCZ features follow the same criteria as habitats.

Matrix used to define feature vulnerability. Note: any features categorised as VL are not considered further in the assessment

Matrix applied to determine Designated Site Vulnerability

Matrix used to define Mitigation categories 1-3