19.6 Cable Monitoring

The subsea cable routes (inter-array and interconnector cables) will be subject to periodic inspection post-construction to monitor the cable protection, including burial depths. Maintenance of the protection will be undertaken as necessary.
If exposed cables or ineffective protection measures are identified during post-construction monitoring, these would be promulgated to relevant sea users including via Notice to Mariners and Kingfisher Bulletins. Where immediate risk was observed, the Applicant would also employ additional temporary measures (such as a guard vessel or temporary buoyage) until such time as the risk was permanently mitigated in liaison with MCA and NLB.
Details will be included in full within the assessment of cable burial and protection document, to be produced post-consent.

19.7 Hydrographic Surveys

As required by Annex 4 of MGN 654 (MCA, 2021) detailed and accurate hydrographic surveys will be undertaken to required MCA periodicity and standards.

A Decommissioning Programme will be developed post-consent. With regards to hazards to shipping and navigation, this will also include consideration of the scenario where upon decommissioning and completion of removal operations, an obstruction is left on site (attributable to the Array) which is considered to be a danger to navigation and which it has not proved possible to remove. Such an obstruction may require marking until such time as it is either removed or no longer considered a danger to navigation, the continuing cost of which would need to be met by the Applicant.

Using baseline data, collision and allision risk modelling and the outputs of consultation, hazards relating to shipping and navigation have been identified for the Array for all phases of the development (construction, operation and maintenance and decommissioning).

Throughout the NRA process, consultation has been undertaken directly with key shipping and navigation stakeholders. A Hazard Workshop and Regular Operator outreach has also been undertaken. Further details on consultation can be found in section 4.

Navigational features in the shipping and navigation study area are limited noting the offshore location of the Array.
Three buoys are located within the site boundary. Charted wrecks and obstructions are located in the vicinity, more commonly inshore of the site boundary. The closest is 3 nm from the north-western corner of the site boundary. Seagreen 1 Offshore Wind Farm is approximately 27 nm inshore of the site boundary. It comprises 114 wind turbines.
Further details on navigational features can be found in section 7.

The maritime incident baseline is presented and detailed in section 9.
A total of two helicopter taskings occurred within the shipping and navigation study area between April 2015 and March 2023, corresponding to an average of one every four years.
A total of three incidents of documented by the RNLI as occurring within the shipping and navigation study area between 2013 and 2022, corresponding to one every three to four years. One of these occurred within the site boundary in 2016.
From MAIB incident data recorded between 2012 and 2021, a total of four incidents occurred within the shipping and navigation study area, corresponding to an average of one incident every two to three years. Two of these incidents occurred within the site boundary itself, in 2015 and 2018.
A review of older MAIB incident data spanning the previous ten years (2002 to 2011) indicated that the frequency of incidents has seen a minor decline over time in this area. There was a total of nine incidents, corresponding to one per year, with one within the site boundary in 2011.

The vessel traffic baseline is presented and detailed in section 10.
Within the shipping and navigation study area, there was an average of nine vessels per day during the winter vessel traffic survey period and 11 vessels per day during the summer vessel traffic survey period. Within the site boundary itself, there was an average of two to three vessels per day during the winter vessel traffic survey period and three to four vessels per day during the summer vessel traffic survey period.
Oil and gas vessels and cargo vessels were the most common vessel types during both survey periods within the shipping and navigation study area, with cargo vessels being the most common vessel type intersecting the site boundary during both survey periods.

A total of 11 main commercial routes were identified from 12 months of AIS data recorded during 2022. The highest-use main commercial route was a route used by oil and gas vessels between Aberdeen and various oil and gas infrastructure, with an average of 16 to 17 unique vessels per week. Seven of these routes are anticipated to require deviation as a result of the presence of the Array, with the amount of deviation within the shipping and navigation study area ranging from less than 0.1 nm to 5.7 nm.