17.4 Vessel to Structure Allision Risk

  1. Based on the cumulative routeing assessment (section 14.2) it is likely that most vessels currently transiting within or near the Array will choose to pass inshore between Seagreen 1 Offshore Wind Farm and Morven Offshore Wind Farm, where there is in excess of 10 nm of width of sea room available for transit (which is considered sufficient to safely accommodate additional vessel transits without unduly increasing allision risk given allision risk is localised to each development).
  2. Any vessels choosing to pass further offshore will likely use either the sea space between the Array and Bellrock Offshore Wind Farm, or between Campion Offshore Wind Farm and Bellrock Offshore Wind Farm. There is in excess of 10 nm of sea room between Campion Offshore Wind Farm and Bellrock Offshore Wind Farm, and consensus during consultation including at the Hazard Workshop was that the space available between Bellrock Offshore Wind Farm and the Array was also sufficient to manage any associated risk.
  3. All screened in developments will be required to agree lighting and marking with the NLB to ensure navigational safety including managing allision risk. Similarly, layouts must also be agreed with the MCA and NLB, with these discussions including consideration of internal allision risk. In addition to the Morven Offshore Wind Farm, the proximity of the Bellrock Offshore Wind Farm means that lighting and marking and also charting will need to be considered cumulatively.
  4. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, outputs of the modelling, and consideration of historical incident data. The severity of consequence is considered to be serious. The risk will, therefore, be of tolerable significance. Assuming consultation with the MCA and NLB on the cumulative lighting and marking and charting of the Array and other relevant developments, the risk is considered to be ALARP.

17.5 Reduced Access to Local Ports and Harbours

  1. Any displacement associated with the installation or maintenance of the Proposed offshore export cable(s) cumulatively with the Array will be spatially limited to the area immediately around the vessel activities and temporary in nature. Details of the installation or maintenance would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be increased and facilitating passage planning. Any cumulative impact on port access is therefore unlikely.
  2. Given the distance offshore of screened in offshore wind farm developments, there is unlikely to be any direct impact on port access from the structures outside of the cumulative deviations that have already been assessed.
  3. All screened in developments are likely to be utilising similar vessel management mitigations to those deployed fort the Array, in particular marine coordination. It is also noted that the production of a VMP and NSP are standard conditions of consent. These measures will seek to ensure vessel movements including in and out of port are managed.
  4. The frequency of occurrence is considered to be negligible considering the extent of the cumulative study area and based on the available sea room. The severity of consequence is considered to be minor. The risk will therefore be of broadly acceptable significance, which is not significant in EIA terms.

17.6 Reduction in SAR Capability

  1. Given the low baseline incident rates, there is not considered likely to be a notable effect on emergency response resources on a cumulative level. This takes account of historical data showing that allisions and collisions caused by offshore wind farms do not occur at a high frequency (section 9.6) in combination with there being unlikely to be a notable rise in incidents associated with the installation of the Proposed offshore export cable(s) cumulatively with the Array.
  2. All screened in projects will be required to produce an ERCoP and agree a SAR checklist with the MCA, meaning that each individual project will have appropriate liaison measures with the MCA in place, and implement suitable SAR mitigations. The relevant MCA guidance (MCA, 2021) also requires that individual ERCoPs consider SAR procedures and liaison on a cumulative basis.
  3. MCA guidance in the form of MGN 654 (MCA, 2021) also dictates SAR design requirements for offshore wind farms. All screened in projects will need to discuss and agree their layouts with the MCA, and these discussions will include consideration of other local offshore wind farms in proximity. This will ensure SAR operations can continue within the area, with SAR assets being able to access and search individual offshore wind farm layouts.
  4. The frequency of occurrence is considered to be remote based on consideration of the historical incident data and the embedded mitigation in place including compliance with MGN 654. The severity of consequence is considered to be serious. The risk will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

18 Risk Control Log

18.1 Embedded Mitigation

  1. The embedded mitigation measures assumed within the FSA are detailed in Table 18.1.

Table 18.1: Embedded Mitigation

Designed In Measures Adopted as Part of the Array

Justification

Apply for and implement safety zones during major construction and operation and maintenance activities. Similar approach likely during decommissioning noting this will be a separate application.

Application for safety zones up to 500 m around structures where vessels are undertaking construction work during construction and periods of major operation and maintenance and 50 m around partially completed or completed but not yet fully commissioned surface piercing structures during construction.

Advisory temporary safe passing distances to be promulgated to mariners, including fishermen, around installation/maintenance vessels actively engaged in works

Deployment of a buoyed construction area in agreement with the NLB.

Protects third-party vessels from project vessels involved in construction activities which may be RAM, and partially completed structures.

Completion of, and adherence to a CBRA.

The CBRA will consider relevant activities in the vicinity of inter-array and interconnector cables and confirm appropriate means of protection taking account of the final inter-array and interconnector cable. The CBRA will identify the appropriate target burial depth to ensure the cable remain buried, or appropriately protected, where target burial depths cannot be achieved, for the duration of Ossian, to minimise the risk of interaction with other sea users or cable exposure.

Compliance with MGN 654 and its annexes (in particular SAR annex 5 and completion of a SAR checklist) where applicable.

Ensures the final Array layout is suitable for SAR operations and that reductions in underkeel clearance are acceptable.

Use of guard vessel(s) as required by risk assessment.

Maximises awareness of temporary hazards, and ensures vessel presence where necessary to alert passing mariners to a hazard.

Layout finalised through the DSLP via consultation with the MCA and NLB.

Ensures the final Array layout is suitable for both surface and air based (for SAR purposes) navigation and is compliant with MGN 654.

Will also confirm adherence to key project design conditions including ensuring a safe underkeel clearance is maintained around mooring line arrangements and dynamic cables.

Development of, and adherence to an LMP.

The LMP will confirm compliance with legal requirements including IALA G1162 (IALA, 2021), with regards to shipping, navigation and aviation marking and lighting to increases awareness of the Array in both day and night conditions for vessel and aviation operators including in restricted visibility and assists with SAR operations.

Consideration of UK MGN 654 with respect to wind turbine design and construction, so that recognised safe standards are met with regards to navigational safety and emergency response (search and rescue, salvage and towing, counter pollution).

Establishment of a Marine Coordinator and communication procedures to manage project vessel movements.

Ensure project vessels are suitably managed to minimise the likelihood of involvement in incidents and ensure the safe operation during all phases of project development. Increases the ability to assist in the event of a third-party incident.

Production and implementation of a MPCP.

To reduce the potential for release of pollutants from construction, operation and maintenance and decommissioning plant is reduced so far as reasonably practicable. These will likely include designated areas for refuelling where spillages can be easily contained, storage of chemicals in secure designated areas in line with appropriate regulations and guidelines, double skinning of pipes containing hazardous substances, and storage of these substances in impenetrable bunds. All vessels associated with the Array will be required to comply with the standards set out by MARPOL. Measures will be in place to reduce the risk that accidental pollution poses to personnel, third party vessels and the environment.

An outline MPCP is provided in volume 4, appendix 21, annex A.

Appropriate marking of structures including mooring lines on UKHO Admiralty Charts and other electronic charts as appropriate.

Ensure the appropriate marking of structures on UKHO Admiralty Charts to maximise the awareness of the Array allowing vessels to plan their passage in advance.

Minimum blade tip clearance height of 36 m above LAT

This minimises the risk of blade allision particularly for sailing vessels with a mast and surpasses the requirements set by the RYA policy (RYA, 2019) and MGN 654 (MCA, 2021).

Development of, and adherence to a Navigational Safety and Vessel Management Plan (NSVMP).

The NSVMP will confirm the types and numbers of vessels that will be engaged in activities associated with the Array and consider vessel coordination including indicative transit route planning (Marine Coordination).

All contractors undertaking works to be contractually obliged to ensure compliance with standard offshore policies, including those that prohibit the discarding of objects or materials overboard and that require the rapid recovery of accidentally dropped objects where feasible.

Development and issue of a Code of Conduct to all project vessel operators to advise on how to avoid impacts on marine megafauna and interference with fishing activities.

Compliance of all project vessels with maritime regulations as adopted by the relevant flag state including the COLREGs IMO, 1974a) and the SOLAS (IMO, 1974b). Promulgation of information for vessel routes, timings and locations, safety zones and advisory safe passing distances as required via Kingfisher Bulletins.

Compliance with the Regulatory Expectations on Moorings for Floating Wind and Marine Devices, in particular independent TPV and monitoring/tracking.

Development and implementation of an ERCoP.

In line with MGN 654 (MCA, 2021) Annex 5 SAR requirements.

Promulgation of information through timely and efficient posting of NtM, Kingfisher Bulletins and navigational warnings, as appropriate. Information will include but not be limited to vessel routes, timings and locations, safety zones and advisory safe passing distances as required.

Maximises awareness of the Array allowing vessels to passage plan in advance.

Compliance with the Regulatory Expectations on Moorings for Floating Wind and Marine Devices (HSE and MCA, 2017).

Ensure that the final design is appropriately designed, constructed to an appropriate standard and structural integrity maintained during the operation and maintenance phase of the project.

MGN 654 requirement, to manage risk of loss of station and to ensure procedures are in place in the event of loss of station.

Ossian Array infrastructure will be subject to TPV, where applicable.

Ensure that the final design is appropriately designed, constructed to an appropriate standard and structural integrity maintained during the operation and maintenance phase of the project.

Installation of remote discrete condition monitoring equipment

Installation of appropriate system, such as sensors, cameras, dataloggers, etc. to ensure the safe and efficient operation of the Array infrastructure.

Construction Method Statement (CMS)

The CMS will confirm certain construction activities and how these will be managed. This will include plans on wet storage within the Array including available underkeel clearance.