the soils, any exposure is likely to be short term and temporary. Embedded mitigation within the CoCP would ensure that contractors working on site will be instructed to wear appropriate PPE to prevent coming into with contaminants. The magnitude of the impact prior to mitigation is considered to be medium. Therefore the significance of the impact is considered to be minor adverse. No additional mitigation is considered necessary.
19.6.2 Potential Impacts during Operation 92.
This section describes the potential impacts arising during the operational phase of East Anglia THREE. Reference should also be made to Chapter 5 Description of the Development for full details of the operational phase.
93.
The differences between Scenarios 1 and 2 of cable installation are related to the construction phase only, and therefore the impact assessment for operation is the same regardless of installation methodology. The only difference would be the number of jointing locations, with 61 locations in Scenario 1 and 48 under Scenario 2.
19.6.2.1 Impact 1: Impact to soils, geology and ground condition 94.
There is the potential for some operational activities to impact the soils, geology and ground conditions mainly at the converter station through general site activities such as routine monitoring and maintenance. In addition along the onshore cable route three potential landfills were identified which could lead to gas build up in confined spaces such as jointing pits.
95. Where maintenance is required below ground there is the potential for hazardous gas to migrate via permeable strata and accumulate in confined spaces and / or buildings on site. Considering the localised nature of this hazard the magnitude of the impact is likely to be low in most cases. In addition, as noted above under Scenario 1, where possible jointing pits will be located in areas which are not sensitive or contaminated to avoid impacts in accordance with embedded mitigation. However, from a precautionary basis, in the areas surrounding the landfills at Culpho and Bramford and at Tuddenham St Martin, the magnitude and likelihood of encountering ground gas is increased the effect is considered to be medium. No confined spaces will remain during operation; therefore, the likelihood for the build-up of gas will be low to negligible, leading to a minor adverse impact for the entire onshore electrical transmission works. Mitigation measures in relation to gas risk at the converter station are detailed in Table 19.18 below.
96.
Routine maintenance works would be required during the operational phase; however, this access would be via jointing pits or kiosks. Maintenance may include
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 19 Soils, Geology and Ground Condition Page 40
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