19.6.1.1.1 Landfall
Scenario 1: Pre-installed ducts 71. One statutory designated site, Bawdsey Cliffs, lies within the landfall footprint. The sensitivity of the geological receptor at the landfall would be considered to be high, given its status as a designated site. Within Scenario 1 no trenching or HDD works are required but should the East Anglia ONE HDD works be forced to create a jointing pit in the intertidal zone a temporary ramp and haul road down to the base of the sea cliffs will be needed to secure access and construction of the East Anglia THREE jointing pit. If required, a temporary access ramp will be constructed over the top of the cliff and will be removable once works are completed. This temporary ramp will be located to the north east of an existing bridleway, where the Red Crag (for which the area is designated a SSSI) does not outcrop. Mitigation through design will mean that there will be no direct impact to the integrity of the SSSI feature. Given that the geological feature will be avoided, the potential to degrade the cliff face by trafficking, uneven loading and destabilisation during construction of the access ramp is considered to equate to a low magnitude of effect and the significance of the impact is considered to be moderate adverse. Additional mitigation is described in Table 19.17 below.
72.
The presence of a mechanical excavator brings with it the hazard of spills and leaks, although these are considered to be temporary (limited to construction period), of low magnitude (given limited volume of potentially contaminating materials) and reversible (as the temporary ramp/ haul road will be removed following completion of works). Beyond these works the need for excavation and interaction with the geology at the landfall is minimal and considered to be of low magnitude.
Table 19.17Mitigation measures for both scenarios Mitigation measures
In order to reduce the impacts to the underlying geology from haul roads, trenching, drilling and general construction activities including leaks and spills, the following mitigation would be undertaken: Design and construct free standing ramp to minimise loading and destabilisation of cliff face; Check and maintain equipment to ensure leaks and spills do not occur; and Have spill kits available at all times and an incident response plan in place.
73.
Following implementation of the mitigation measures described above the magnitude of impact would be reduced to negligible, the overall significance of the impacts to designated geological receptors is considered to be minor adverse.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 19 Soils, Geology and Ground Condition Page 35
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