251. Alternatively, a combination of the onshore and offshore O&M options described above may be employed.
252. Given the design life of the offshore components some refurbishment or replacement would be required during this time. Relevant consents or licences required would be applied for if required.
253. Typical maintenance activities would include -general wind turbine service; oil sampling / change; UPS (uninterruptible power supply)-battery change; service and inspections of wind turbine safety equipment, nacelle crane, service lift, HV system, blades; major overhauls (years 5, 7, 10), wind turbine repairs and restarts.
254. During the life of the project, it is not the intention to repair or replace the sub-sea cables, however repairs may be required and periodic inspection will be undertaken. Periodic surveys would also be required to ensure the cables remain buried and if they do become exposed, re-burial works would be undertaken.
5.4.12.2 Vessel and Helicopter Operations 255. A number of vessel and / or helicopter visits to each turbine would be required each year to allow for scheduled and unscheduled maintenance. The predicted worst case is 365 helicopter visits to the East Anglia site per year and a maximum of approximately 4,000 windfarm support vessel trips which includes all scheduled and unscheduled maintenance. If the onshore operation option is chosen, this would mean small crew vessels sailing to and from the windfarm on a daily basis from shore, possibly supported by helicopters. If the offshore operation option is preferred, the majority of small crew vessels would be operated on a daily basis from the offshore accommodation vessel or platform, although further support vessels are also still likely to transit to and from shore each day and helicopter operations may still be utilised. Collector and converter stations would require one visit a week maximum.
256. Although it is not anticipated that large components (e.g. wind turbine blades or substation transformers) would require replacement during the operational phase, it is a possibility. Should this be required large jack-up vessels may need to operate continuously for significant periods to carry out these major maintenance activities.
257. During O&M activities EATL would seek to agree appropriate safety zones around wind turbines and work areas to be applied. Safety zones are described above in Table 5.23.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 5 Description of the Development Page 57
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