13.12. Cumulative Effects Assessment

13.12.1. Methodology

330. The Cumulative Effects Assessment (CEA) assesses the impact associated with the Array together with other relevant plans, projects and activities. Cumulative effects are defined as the combined effect of the Array in combination with the effects from a number of different projects, on the same receptor or resource. Further details on CEA methodology are provided in volume 1, chapter 6.
331. The projects and plans selected as relevant to the CEA presented within this chapter are based upon the results of a screening exercise (see volume 3, appendix 6.4 of the Array EIA Report). Volume 3, appendix 6.4 further provides information regarding how information pertaining to other plans and projects is gained and applied to the assessment. Each project or plan has been considered on a case-by-case basis for screening in or out of this chapter's assessment based upon data confidence, impact-receptor pathways and the spatial/temporal scales involved.
332. In undertaking the CEA for the Array, it should be noted that other projects and plans under consideration will have differing potential for proceeding to an operational stage and hence a differing potential to ultimately contribute to a cumulative impact alongside the Array. Therefore, a tiered approach has be adopted which provides a framework for placing relative weight upon the potential for each project/plan to be included in the CEA to ultimately be realised, based upon the project/plan’s current stage of maturity and certainty in the projects’ parameters. The tiered approach which will be utilised within the overarching Array CEA employs the following tiers:

• tier 1 assessment – Array and Proposed offshore export cable corridor(s) and Proposed onshore transmission infrastructure and all plans/projects which became operational since baseline characterisation, those under construction and those with consent and submitted but not yet determined;
• tier 2 assessment – All plans/projects assessed under Tier 1, plus those projects with a Scoping Report; and
• tier 3 assessment – All plans/projects assessed under Tier 2, which are reasonably foreseeable, plus those projects likely to come forward where an Agreement for Lease (AfL) has been granted.

333. It is noted that the cumulative routeing assessment in the NRA uses its own tiering system based on development status, distance from the Array, level of interaction with baseline traffic of relevance to the Array, level of concern raised during consultation, and data confidence. Full details are provided in the NRA (volume 3, appendix 13.1). This chapter considers the cumulative routeing outputs, but applies the tiering shown in Table 13.12   Open ▸ . The NRA also considers a 50 nm buffer for cumulative routeing.
334. The specific projects scoped into the CEA for shipping and navigation for the purposes of the Array EIA Report chapter are outlined in Table 13.12   Open ▸ .
335. The range of potential cumulative impacts that are identified and included in Table 13.13   Open ▸ , is a subset of those considered for the Array alone CEA assessment. This is because some of the potential impacts identified and assessed for the Array alone, are localised and temporary in nature. It is considered therefore, that these potential impacts have limited or no potential to interact with similar changes associated with other plans or projects. These have therefore not been taken forward for detailed assessment. The scoped out impacts are:

• loss of station;
•  reduction of under keel clearance as a result of subsea infrastructure;
• anchor interaction with subsea cables (including dynamic cabling); and
• anchor interaction with mooring lines.

336. Similarly, some of the potential impacts considered within the Array alone assessment are specific to a particular phase of development (e.g. construction, operation and maintenance or decommissioning). Where the potential for cumulative effects with other plans or projects only have potential to occur where there is spatial or temporal overlap with the Array during certain phases of development, impacts associated with a certain phase may be omitted from further consideration where no plans or projects have been identified that have the potential for cumulative effects during this period.
337. It should be noted that there are no impact pathways in respect of the Proposed onshore transmission infrastructure that could result in a cumulative impact on shipping and navigation receptors scoped into the CEA. Therefore, the Proposed onshore transmission infrastructure has not been considered further within this CEA.

Figure 13.5: Other Projects/Plans Screened into the CEA for Shipping and Navigation

Table 13.12: List of Other Projects and Plans Considered within the CEA for Shipping and Navigation

13.12.2. Maximum Design Scenario

338. The MDSs identified in Table 13.13   Open ▸ have been selected as those having the potential to result in the greatest effect on an identified receptor or receptor group. The cumulative effects presented and assessed in this section have been selected from the details provided in volume 1, chapter 3 of the Array EIA Report as well as the information available on other projects and plans (see volume 3, appendix 6.4), to inform an MDS. Effects of greater significance are not predicted to arise should any other development scenario, based on details within the Project Description (volume 1, chapter 3) (e.g. different wind turbine layout), to that assessed here, be taken forward in the final design scheme.

Table 13.13: Maximum Design Scenario Considered for Each Impact as part of the Assessment of Likely Significant Cumulative Effects on Shipping and Navigation

13.12.3. Cumulative Effects Assessment

339. An assessment of the likely significance of the cumulative effects of the Array upon shipping and navigation receptors arising from each identified impact is given below.

Increased vessel to vessel collision risk resulting from displacement (third‑party to third‑party)

                        Tier 1

                        Construction phase

340. Any displacement associated with the installation of the offshore export cable(s) required for the Array will be spatially limited to the area immediately around the installation vessel activities and temporary in nature. Details of the installation would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be maximised and facilitating passage planning.
341. Based on the cumulative routeing assessment in the NRA (volume 3, appendix 13.1), it is not anticipated that Inch Cape Offshore Wind Farm, Berwick Bank Offshore Wind Farm, or the Seagreen 1A Project will impact main routes also interacting with the Array. As such, deviations on a cumulative basis are likely to be similar to the deviations assuming only the buoyed construction area is in place.

Frequency of occurrence

342. The frequency of occurrence is considered to be negligible based on the available sea room around Tier 1 developments and the temporary nature of the cable installation impact.

Severity of consequence

343. The severity of consequence is considered to be serious.

Significance of the effect

344. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

345. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Operation and maintenance phase

346. Any displacement associated with the offshore export cable(s) required for the Array during the operation and maintenance phase will be limited to any maintenance activity requiring the presence of a vessel. This displacement would be spatially limited to the area immediately around the vessel activities and temporary in nature. Details of the operation would be promulgated in advance via the usual means including Notices to Mariners and Kingfisher bulletins ensuring awareness will be maximised, and facilitating passage planning.
347. As for the construction phase, it is not anticipated that Inch Cape Offshore Wind Farm, Berwick Bank Offshore Wind Farm or the Seagreen 1A Project will impact main routes also interacting with the Array, as per the cumulative routeing assessment in the NRA (volume 3, appendix 13.1). As such, deviations on a cumulative basis are likely to be similar to the deviations assuming the Array alone case.

Frequency of occurrence

348. The frequency of occurrence is considered to be negligible based on the available sea room around Tier 1 developments.

Severity of consequence

349. The severity of consequence is considered to be serious.

Significance of the effect

350. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

351. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Decommissioning phase

352. Any displacement associated with the decommissioning of the offshore export cable(s) required for the Array will be spatially limited to the area immediately around the associated vessel activities and temporary in nature. Details of the decommissioning would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be maximised and facilitating passage planning.
353. As for the construction and operation and maintenance phases, it is not anticipated that Inch Cape Offshore Wind Farm, Berwick Bank Offshore Wind Farm or the Seagreen 1A Project will impact main routes also interacting with the Array, as per the cumulative routeing assessment in the NRA (volume 3, appendix 13.1).

Frequency of occurrence

354. The frequency of occurrence is considered to be negligible based on the available sea room around Tier 1 developments.

Severity of consequence

355. The severity of consequence is considered to be serious.

Significance of the effect

356. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

357. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Tier 2

                        All phases

358. Based on the cumulative routeing assessment in the NRA (volume 3, appendix 13.1), it is anticipated that the majority of vessels will choose to pass inshore of the Array, between Seagreen 1 Offshore Wind Farm (screened out as part of the baseline) and Morven Offshore Wind Farm on the basis that:

• Consultation input including at the Hazard Workshop indicates that commercial vessels are likely to prefer to pass in open sea room rather than between or in proximity to wind farm arrays.
• The open sea room means that vessels will be able to passage plan with minimal waypoints on their transits.
• Overall percentage increases in deviations associated with this routeing option are low are low when compared to the route lengths as a whole (the busiest route [Route 2] is approximately 700 nm in total length, with the inshore deviation leading to an estimated increase of less than 1%).

359. There is in excess of 10 nm of navigable sea area between Seagreen 1 Offshore Wind Farm and Morven Offshore Wind Farm, and therefore there is considered to be sufficient sea space to accommodate any additional transits form vessels choosing to deviate through this inshore area.
360. Some vessels may also choose to pass offshore of the Array, noting that the presence of Salamander Offshore Wind Farm and Muir Mhor Offshore Wind Farm to the north may mean this will lead to a larger deviation than passing inshore.
361. The Cenos Offshore Wind Farm is located approximately 50 nm from the Array, and is unlikely to contribute notably to cumulative deviations to the routes also interacting with the Array, other than for oil and gas vessels from Montrose. These vessels will be able to pass either north or south of the Cenos Offshore Wind Farm, or through at the master’s discretion.
362. The proximity of the Morven Offshore Wind Farm means that lighting and marking and also charting will need to be considered cumulatively. This will ensure vessels are aware of the projects and are able to passage plan accordingly.

Frequency of occurrence

363. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, the outputs of the modelling, and consideration of historical incident data.

Severity of consequence

364. The severity of consequence is considered to be serious.

Significance of the effect

365. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will, therefore, be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

366. Assuming consultation with the MCA and NLB on the cumulative lighting and marking and charting of the Array and other Tier 2 developments, the effect is considered to be of tolerable significance and ALARP, which is not significant in EIA terms.

                        Tier 3

                        All phases

367. Based on the cumulative routeing assessment in the NRA (volume 3, appendix 13.1) which considers all Tier 3 developments, it is anticipated that the majority of vessels will choose to pass inshore of the Array, between Seagreen 1 Offshore Wind Farm (screened out as part of the baseline) and Morven Offshore Wind Farm (Tier 2) as described in the equivalent Tier 2 assessment. The inclusion of other Tier 3 developments is considered as making it more likely that vessels will choose to pass inshore of the Array given the generally offshore locations of the other proposed Tier 3 arrays, in particular the location of the Bowdun Offshore Wind Farm. The addition of Tier 3 developments does not reduce the available sea room between Seagreen 1 Offshore Wind Farm and Morven Offshore Wind Farm. Further north, the Flora Floating Offshore Wind Farm may mean that vessels are more likely to pass inshore of the Hywind Offshore Wind Farm (screened out as part of the baseline), however passing between the Flora Floating Offshore Wind Farm and the Muir Mhor Offshore Wind Farm will also be an option.
368. Vessels choosing to pass further offshore may use the sea area between the Array and Bellrock Offshore Wind Farm, noting that general consensus during consultation including the hazard workshop was that there was sufficient sea space to accommodate likely users. There is also the option to pass further offshore, between the Campion Offshore Wind Farm and Bellrock Offshore Wind Farm. Any vessels choosing such passage would need to pass either north or south of the Cedar array.
369. The location of the Aspen array is considered as being unlikely to significantly contribute to cumulative deviations, given that as discussed above most vessels on north/south are likely to pass inshore. 
370. In addition to the Morven Offshore Wind Farm (Tier 2), the proximity of the Bellrock Offshore Wind Farm means that lighting and marking and also charting will need to be considered cumulatively. This will ensure vessels are aware of the projects and are able to passage plan accordingly.

Frequency of occurrence

371. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, the outputs of the modelling, and consideration of historical incident data.

Severity of consequence

372. The severity of consequence is considered to be serious.

Significance of the effect

373. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will, therefore, be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

374. Assuming consultation with the MCA and NLB on the cumulative lighting and marking and charting of the Array and other Tier 2 and Tier 3 developments, the effect is considered to be of tolerable significance and ALARP, which is not significant in EIA terms.

Displacement from adverse weather routeing

                        Tier 1

                        Construction phase

375. Any displacement associated with the installation of the offshore export cable(s) required for the Array will be spatially limited to the area immediately around the installation vessel activities and temporary in nature. Details of the installation would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be maximised and facilitating passage planning. As such no notable cumulative impact on adverse weather routeing is anticipated.
376. Based on the cumulative routeing assessment in the NRA (volume 3, appendix 13.1), it is not anticipated that the Inch Cape Offshore Wind Farm, Berwick Bank Offshore Wind Farm or the Seagreen 1A Project will impact main routes also interacting with the Array, and therefore only irregular transits are likely to be impacted. There is in excess of 30 nm between the Array and the Tier 1 projects, facilitating inshore routeing to the west of the buoyed construction area if this is vessel preference during adverse conditions.

Frequency of occurrence

377. The frequency of occurrence is considered to be negligible based on the available sea room and the temporary nature of cable installation.

Severity of consequence

378. The severity of consequence is considered to be serious.

Significance of the effect

379. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

380. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Operation and maintenance phase

381. Any displacement associated with the offshore export cable(s) required for the Array during the operation and maintenance phase will be limited to any maintenance activity requiring the presence of a vessel. This displacement would be spatially limited to the area immediately around the vessel activities and temporary in nature. Details of the operation would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be maximised and facilitating passage planning. As such no notable cumulative impact on adverse weather routeing is anticipated.
382. As noted for the construction phase, when accounting for the presence of the Inch Cape Offshore Wind Farm, the Berwick Bank Offshore Wind Farm and the Seagreen 1A Project there is sea room available inshore of the Array to accommodate inshore routeing if this is vessel preference during adverse weather conditions (there is in excess of 30 nm between the Array and the Tier 1).

Frequency of occurrence

383. The frequency of occurrence is considered to be negligible based on the available sea room around Tier 1 developments.

Severity of consequence

384. The severity of consequence is considered to be serious.

                        Significance of the effect

385. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

386. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Decommissioning phase

387. Any displacement associated with the decommissioning of the offshore export cable(s) required for the Array will be spatially limited to the area immediately around the associated vessel activities and temporary in nature. Details of the decommissioning would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be maximised and facilitating passage planning.
388. As for the construction and operation and maintenance phases, when accounting for the presence of the Inch Cape Offshore Wind Farm, Berwick Bank Offshore Wind Farm and the Seagreen 1A Project there is considered to be sea room available to allow for any inshore routeing preference during adverse weather (there is in excess of 30 nm between the Array and the closest Tier 1 project).

Frequency of occurrence

389. The frequency of occurrence is considered to be negligible based on the available sea room around Tier 1 developments.

Severity of consequence

390. The severity of consequence is considered to be serious.

Significance of the effect

391. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

392. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Tier 2

                        All phases

393. There is in excess of 10nm of navigable sea area between Seagreen 1 Offshore Wind Farm (screened out as part of the baseline) and Morven Offshore Wind Farm, and therefore there is considered to be sufficient sea room to accommodate any additional transits from vessels choosing an inshore passage as a result of adverse weather. It is considered likely based on the cumulative routeing assessment in the NRA (volume 3, appendix 13.1), that most vessels will choose this routeing option for deviation, passing inshore of both the Morven Offshore Wind Farm and the Salamander Offshore Wind Farm. There is open sea room to the east for any vessels choosing to pass further offshore, with other Tier 2 developments in excess of 25nm from the Array.
394. The proximity of the Morven Offshore Wind Farm means that lighting and marking and also charting will need to be considered cumulatively. This will ensure vessels are aware of the projects and are able to passage plan accordingly including during adverse weather.

Frequency of occurrence

395. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, the outputs of the modelling, and consideration of historical incident data.

Severity of consequence

396. The severity of consequence is considered to be serious.

Significance of the effect

397. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will, therefore, be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

398. Assuming consultation with the MCA and NLB on the cumulative lighting and marking and charting of the Array and other Tier 2 developments, the effect is considered to be of tolerable significance and ALARP, which is not significant in EIA terms.

                        Tier 3

                        All phases

399. The inclusion of Tier 3 developments is considered as increasing the likelihood that vessels will pass inshore (including during adverse weather), noting that no Tier 3 developments result in reduced sea room between Seagreen 1 Offshore Wind Farm (screened out as part of the baseline) and Morven Offshore Wind Farm (Tier 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. Any vessels choosing such passage would need to pass either north or south of the Cedar array.
400. The location of the Aspen array is considered as being unlikely to significantly contribute to cumulative deviations, given that as discussed above most vessels on north/south are likely to pass inshore, including during adverse weather. 
401. In addition to the Morven Offshore Wind Farm (Tier 2), the proximity of the Bellrock Offshore Wind Farm means that lighting and marking and also charting will need to be considered cumulatively. This will ensure vessels are aware of the projects and are able to passage plan accordingly including during adverse weather.

Frequency of occurrence

402. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, the outputs of the modelling, and consideration of historical incident data.

Severity of consequence

403. The severity of consequence is considered to be serious.

Significance of the effect

404. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will, therefore, be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

405. Assuming consultation with the MCA and NLB on the cumulative lighting and marking and charting of the Array and other Tier 2 and Tier 3 developments, the effect is considered to be of tolerable significance and ALARP, which is not significant in EIA terms.

Increased vessel to vessel collision risk (third‑party to Array vessels)

                        Tier 1

                        Construction phase

406. Any collision risk associated with the installation of the offshore export cable(s) required for the Array will be spatially limited to the area immediately around the installation vessel activities and temporary in nature. Details of the installation 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, thus reducing any collision risk associated with the installation. Any encounters that did occur between a third‑party vessel and the cable installation vessel would be managed via COLREGS.
407. It is anticipated that Inch Cape Offshore Wind Farm and the Seagreen 1A Project will be operational prior to commencement of construction of the Array. Timelines are less certain for Berwick Bank Offshore Wind Farm, however based on current understanding of timelines there is unlikely to be a large overlap between the end of the Berwick Bank Offshore Wind Farm construction and construction of the Array. Therefore, it is likely that the only additional project vessels on a cumulative basis will be those associated with the operation and maintenance of Tier 1 projects (i.e. likely less than during the construction phases), up until decommissioning.
408. Inch Cape Offshore Wind Farm is likely to be utilising similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are conditions of the Inch Cape Offshore Wind Farm consent, and that all vessels associated with Inch Cape Offshore Wind Farm will be required to comply with COLREGS and SOLAS. The same applies for the Seagreen 1A Project. It is likely that similar procedures will be implemented by Berwick Bank Offshore Wind Farm, noting that the implementation of a VMP and NSP is a standard condition of consent.

Frequency of occurrence

409. The frequency of occurrence is considered to be negligible based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

410. The severity of consequence is considered to be serious.

Significance of the effect

411. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

412. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Operation and maintenance phase

413. Any collision risk associated with the offshore export cable(s) required for the Array during the operation and maintenance phase will be limited to any maintenance activity requiring the presence of a surface vessel. This risk would be spatially limited to the area immediately around the vessel activities and temporary in nature. Details of the operation 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, and thus reduce collision risk.
414. As for the construction phase impact, the Inch Cape Offshore Wind, Seagreen 1A Project and the Berwick Bank Offshore Wind Farm are likely to be implementing similar vessel management procedures and mitigations as will be the case for the Array (e.g. VMP, NSP, safety zones).

Frequency of occurrence

415. The frequency of occurrence is considered to be negligible based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

416. The severity of consequence is considered to be serious.

Significance of the effect

417. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

418. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Decommissioning phase

419. Any collision risk associated with the decommissioning of the offshore export cable(s) required for the Array will be spatially limited to the area immediately around the associated vessel activities and temporary in nature. Details of the decommissioning would be promulgated in advance via the usual means including Notice to Mariners and Kingfisher bulletins ensuring awareness will be maximised and facilitating passage planning, thus minimising collision risk.
420. As for the construction phase and operation and maintenance phase impacts, the Inch Cape Offshore Wind, the Seagreen 1A Project and the Berwick Bank Offshore Wind Farm are likely to be implementing similar vessel management procedures and mitigations as will be the case for the Array (e.g. VMP, NSP, safety zones).

Frequency of occurrence

421. The frequency of occurrence is considered to be negligible based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

422. The severity of consequence is considered to be serious.

Significance of the effect

423. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be negligible. The effect will therefore be of broadly acceptable significance, which is not significant in EIA terms.

Further mitigation and residual effect

424. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of broadly acceptable significance, which is not significant in EIA terms.

                        Tier 2

                        Construction phase

425. All Tier 2 projects are anticipated to implement similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are standard conditions of consent, and that all vessels associated with Tier 2 projects will be required to comply with COLREGS and SOLAS.
426. During the construction phase, there will be elevated levels of vessels on site and in the general area (noting ports are still to be decided). There may be overlap between the construction phase, and the construction phases of other Tier 2 developments. Ports to be used for other developments are also unknown, however, as above vessel movements will all be managed.

Frequency of occurrence

427. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

428. The severity of consequence is considered to be serious.

Significance of the effect

429. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

430. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of tolerable significance and ALARP, which is not significant in EIA terms.

                        Operation and maintenance phase

431. During the operation and maintenance phase, all Tier 2 projects are anticipated to implement similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are standard conditions of consent, and that all vessels associated with Tier 2 projects will be required to comply with COLREGS and SOLAS.
432. During the operation and maintenance phase, there are likely to be lower levels of vessels on site and in the general area, noting ports are still to be decided. Ports to be used for other developments are also unknown, however, as above vessel movements will all be managed.

Frequency of occurrence

433. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

434. The severity of consequence is considered to be serious.

Significance of the effect

435. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

436. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of tolerable significance and ALARP, which is not significant in EIA terms.

                        Decommissioning phase

437. During the decommissioning phase, all Tier 2 projects are anticipated to implement similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are standard conditions of consent (outlines provided in volume 4, appendix 26), and that all vessels associated with Tier 2 projects will be required to comply with COLREGS and SOLAS.

Frequency of occurrence

438. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

439. The severity of consequence is considered to be serious.

Significance of the effect

440. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

441. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of tolerable significance and ALARP, which is not significant in EIA terms.

                        Tier 3

                        Construction phase

442. All Tier 3 projects are anticipated to implement similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are standard conditions of consent, and that all vessels associated with Tier 3 projects will be required to comply with COLREGS and SOLAS.
443. During the construction phase, there will be elevated levels of vessels on site and in the general area (noting ports are still to be decided). There may be overlap between the construction phase, and the construction phases of other Tier 3 developments. Ports to be used for other developments are also unknown, however, as above vessel movements will all be managed.

Frequency of occurrence

444. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

445. The severity of consequence is considered to be serious.

Significance of the effect

446. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

447. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of tolerable significance and ALARP, which is not significant in EIA terms.

                        Operation and maintenance phase

448. During the operation and maintenance phase, all Tier 3 projects are anticipated to implement similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are standard conditions of consent and that all vessels associated with Tier 3 projects will be required to comply with COLREGS and SOLAS.
449. During the operation and maintenance phase, there are likely to be lower levels of vessels on site and in the general area, noting ports are still to be decided. Ports to be used for other developments are also unknown, however, as above vessel movements will all be managed.

Frequency of occurrence

450. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

451. The severity of consequence is considered to be serious.

Significance of the effect

452. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

453. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of tolerable significance and ALARP, which is not significant in EIA terms.

                        Decommissioning phase

454. During the decommissioning phase, all Tier 3 projects are anticipated to implement similar vessel management mitigations to those discussed in section 13.10, in particular marine coordination and use of safety zones. It is also noted that the production of a VMP and NSP are standard conditions of consent, and that all vessels associated with Tier 3 projects will be required to comply with COLREGS and SOLAS.

Frequency of occurrence

455. The frequency of occurrence is considered to be extremely unlikely based on the available sea room, consideration of historical incident data, and the designed in measures in place to manage project vessel movements and activities.

Severity of consequence

456. The severity of consequence is considered to be serious.

Significance of the effect

457. Overall, the severity of consequence is deemed to be serious and the frequency of occurrence is considered to be extremely unlikely. The effect will therefore be of tolerable significance and ALARP, which is not significant in EIA terms.

Further mitigation and residual effect

458. No shipping and navigation mitigation is considered necessary because the likely effect in the absence of further mitigation (beyond the designed in measures outlined in section 13.10) is of tolerable significance and ALARP, which is not significant in EIA terms.

Vessel to structure allision risk

                        Tier 1

459. There will be no allision impact associated with the offshore export cable(s) required for the Array during any phase.

                        Construction phase

460. It is anticipated that Inch Cape Offshore Wind Farm will be operational prior to commencement of construction of the Array, with this also likely being the case for Berwick Bank Offshore Wind Farm noting timelines are less certain. Both would therefore have operational mitigations active, in particular lighting and marking in agreement with NLB (a LMP is a condition of the Inch Cape Offshore Wind Farm consent and is a standard condition).
461. Other Tier 1 offshore wind developments are in excess of 30 nm from the Array, and therefore given the localised nature of allision risk, any notable additional cumulative risk is unlikely, noting that the NRA cumulative routeing assessment (volume 3, appendix 13.1) indicated likely limited interaction with Inch Cape Offshore Wind Farm and Berwick Bank Offshore Wind Farm to vessels also passing the Array.