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16.9 Anchor Interaction with Mooring Lines

16.9.1 Construction Phase

Noting water depths in the vicinity of the site boundary, the visible presence and display on charts of the buoyed construction area and promulgation of information, it is considered unlikely that vessels would attempt to anchor in the vicinity of the mooring lines (which may be wet stored during the construction phase). It is noted that this aligns with the baseline anchoring assessment undertaken on the 12 months of vessel traffic data (see Appendix E) which did not identify any anchoring activity based on the information broadcast via AIS.
As for vessel anchors, there is a risk that fishing gear may interact with any mooring lines. It is the responsibility of the fishers to dynamically risk assess whether it is safe to undertake fishing activities within the Array and to make a decision as to whether or not to fish. This decision will be informed by a number of factors, which will include the charted locations of infrastructure within the Array, e.g. on UKHO charts, and other electronic charts as appropriate. Further assessment of impacts associated with fishing gear is provided in volume 2, chapter 12.
There is limited data available with regard to anchor and gear interaction with mooring lines and floating substructures due to lack of precedent of large scale floating wind farms, however, consequences are likely to be similar to that of the cables.

The frequency of occurrence is considered to be negligible given very low frequency of baseline anchoring and charting of infrastructure.

Overall, the severity of consequence is deemed to be moderate and the frequency of occurrence is considered to be negligible. The risk will, therefore, be of broadly acceptable significance.

No additional shipping and navigation mitigation is considered necessary because the likely risk in the absence of further mitigation (beyond the embedded mitigation measures outlined in section 18.1) is ALARP and not significant in EIA terms.

During the operation and maintenance phase, vessels may be more likely to enter into the Array following removal of the buoyed construction area, however consultation input indicates entry may be less frequent than at fixed foundation offshore wind farm developments (see section 4).
Noting water depths in the vicinity of the Array, the visible presence of the surface aspects of the floating substructures and display on charts of the infrastructure, it is considered unlikely that vessels would attempt to anchor in the vicinity of the mooring lines.
As for vessel anchors, there is a risk that fishing gear may interact with any mooring lines. It is the responsibility of the fishers to dynamically risk assess whether it is safe to undertake fishing activities within the Array and to make a decision as to whether or not to fish. This decision will be informed by a number of factors, which will include the charted locations of infrastructure within the Array, e.g. on UKHO charts, and other electronic charts as appropriate.
As noted during the equivalent construction phase impact, there are limited data available with regards to anchor interaction with mooring lines and floating substructures, however, consequences are likely to be similar to that of the cables.

The frequency of occurrence is considered to be negligible given very low frequency of baseline anchoring and charting of infrastructure.

Overall, the severity of consequence is deemed to be moderate and the frequency of occurrence is considered to be negligible. The risk will, therefore, be of broadly acceptable significance.

No additional shipping and navigation mitigation is considered necessary because the likely risk in the absence of further mitigation (beyond the embedded mitigation measures outlined in section 18.1) is ALARP and not significant in EIA terms.

Since the methods used to remove infrastructure are expected to be similar to those used for installation, this impact is expected to be similar in nature to the equivalent construction phase impact. In particular, a buoyed decommissioning area analogous to the buoyed construction area will be in place and it is anticipated that third-party vessels will not enter. It is also noted that it is intended that all mooring lines will be removed as part of the decommissioning process.

The frequency of occurrence is considered to be negligible given very low frequency of baseline anchoring and charting of infrastructure.

Overall, the severity of consequence is deemed to be moderate and the frequency of occurrence is considered to be negligible. The risk will, therefore, be of broadly acceptable significance.

No additional shipping and navigation mitigation is considered necessary because the likely risk in the absence of further mitigation (beyond the embedded mitigation measures outlined in section 18.1) is ALARP and not significant in EIA terms.