such, impact significance for this scenario is therefore considered negligible. No mitigation is considered necessary.
Scenario 2: Trenching and installing ducts 87. During the construction phase, excavation of trenches and hand dug pits through potentially contaminated soil or waste could impact upon the health and safety of construction workers via direct contact, ingestion or physical contact with contaminants that are present at or near the surface or inhalation of airborne particles, ground gases and vapours which may be present on site.
88.
There are potentially one active (Bamford Dairy, Bramford) and two historical landfills (Culpho Hall, Playford, and former sandpit at Tuddenham St. Martin) that encroach onto the onshore cable route. The precise nature of the material used to infill at these locations is not known. Therefore as above, this Made Ground may contain a variety of contaminants depending on the nature of the material and waste previously deposited.
89.
Landfill sites also have the potential to produce landfill leachate and landfill gases (depending upon the types of waste that were deposited), with the potential to migrate and impact nearby receptors, where pathways exist. Where pits are left open near to landfill sites there is the potential for hazardous gas to accumulate. Considering that the localised nature of this hazard the magnitude of the impact is likely to be low in most cases rising to mediumnear the landfills. A minor adverse significance is anticipated due to the low probability of man entry required into the excavations.
90.
In accordance with the example Outline CoCP (OCoCP) in Appendix 5.1, final mitigation measures for routeing through these areas will be agreed with the local authorities through a Specific Contamination Assessment and Mitigation Scheme. Furthermore, prior to the final ES further details from the Environment Agency and local authorities will be reviewed to inform the impact assessment and as outlined in the OCoCP, a site investigation would be undertaken to determine the type and depth of fill material, the presence and quality of any groundwater and the presence of a lining system. On the basis of these data, a risk assessment will be undertaken followed by appropriate mitigation to be included within the design.
91. Despite the presence of the three landfills, potentially contaminative sites along the onshore cable route are infrequent and it is not expected that soils would be contaminated, with the exception of the site at Tuddenham St Martin. Construction workers are, following embedded mitigation, considered to be a receptor of low sensitivity. Although construction workers would be working in close proximity to
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 19 Soils, Geology and Ground Condition Page 39
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