Installation of foundations (See section 5.4.4); Installation of transition pieces; Installation of offshore collector and converter stations; Installation of inter-array transmission cables; Installation of wind turbine generators; and Installation of monitoring meteorological masts.
135. The offshore export cables would either be installed separately or in parallel with other elements of the offshore windfarm (see section 5.4.11). Prior to installation of the cables some ground preparation may be required along the route.
5.4.10.1 Pre-construction site investigations 136. Pre-construction site investigations would be completed prior to construction and are likely to include:
Geotechnical survey; Pre-lay grapnel run; and ROV survey.
137. Geophysical survey data would inform the micro siting of wind turbine foundations, cables and collector and converter stations. The geophysical data would also serve to identify the location of sand waves along the offshore cable corridor so that an assessment could be made as to whether such features could be avoided or, if not, what level of sea bed preparation (pre-lay sweeping) is required, and what the appropriate burial depth would be in stable (i.e. non mobile) sea bed conditions.
138. Targeted geotechnical surveys would take place these would take a number of boreholes, cone penetration tests (CPT) and vibrocores within the East Anglia THREE site and offshore cable corridor up to the landfall site.
139. A pre-lay grapnel run (PLGR) and ROV survey would take place to identify any obstacles that may be in the path of the proposed cable routes. If an obstacle is detected it would either be removed or the cable would be installed in such a way as to avoid it. Where the obstacle is suspected to be UXO, specialist mitigation would be employed to either avoid or make the obstruction safe.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 5 Description of the Development Page 32
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