22.6.2.7 Impact 7: Impacts to Existing Utilities
22.6.2.7.1 Landfall, onshore cable route and converter station 166. The potential exists for maintenance activities to affect utilities, since these activities may require access to the buried cables. Utilities are considered to be highly sensitive, in particular electricity, gas and water, due to the potential disruption that could be caused should the services be disrupted. As described in section 22.6.2, potentially affected utility providers would be contacted and the location of existing services would be identified prior to maintenance works to ensure there would be no impact.
22.6.2.8 Impact 8: Impacts to Open Access and Common Land
22.6.2.8.1 Landfall, onshore cable route and converter station 167. There would be no impact to open access or common land during operation. 22.6.2.9 Impact 9: Impacts fromElectro Magnetic Fields
22.6.2.9.1 Landfall and onshore cable route 168. Underground DC cables include a metal sheath which screens the electric field, however magnetic fields emanate beyond the cable itself.
169. For the types of underground cable being considered for the proposed East Anglia THREE project, the maximum magnetic field that would be produced at 1m above ground is not expected to exceed 50μT (the Earth’s natural magnetic field). A peak would occur above each cable and as there are four cables there would be four peaks in the magnetic field strength across the onshore cable route.
170. The DC fields from the cables can either add to or subtract from the earth’s magnetic field depending on the relative directions. A north-south cable would add to the earth’s magnetic field and therefore the maximum field strength of the combined field would be up to 100μT. At distances beyond about 15m, the field from the cable would be below 1μT.
171. In 2010, ICNIRP produced new guidelines; however these do not automatically take effect in the UK. The UK policy on exposure to AC electromagnetic fields remains based on 1998 ICNIRP. The exposure limits (from the 1998 guidelines) are currently:
Public exposure (magnetic): 360μT; Public exposure (electric): 9kV/m; Occupational exposure (magnetic): 1800μT; and
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 22 Land Use Page 48
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