Table 19.2 Worst Case Assumptions Impact


Construction All impacts


Key design parameters forming realistic worst case scenario


Scenario 1 o Footprint = working width where haul road (16.1km, maximum 60 x joint pits outside haul road area, 15 laydown areas outside of haul road area, converter station compound and 9 CCS) = 101.8ha


o Depth of trench excavations = 1.5m o Depth of jointing pits = 2.5m o Maximum depth of HDD = 25m at River Deben (pre-installed)


o Permanent habitat loss at converter station compound = 2.61ha


o Total spoil = 38,888m3 from jointing pits


o Total residual spoil for removal offsite = 732m3


o Duration of works = 10 weeks at landfall, 44 weeks along onshore cable route and 55 weeks at Converter Station


Scenario 2 o Footprint = working width x 32.84km (includes haul road, HDD, laydown andmaximum 192 jointing pits), converter station compound and 9 CCS) = 193.2ha


o Depth of trench excavations = 1.5m o Depth of jointing pits = 2.5m o Maximum depth of HDD = 25m at River Deben


o Permanent habitat loss at converter station compound = 2.61ha


o Total spoil = 188986m3 from trenches, jointing pits and HDD


o Total residual spoil for removal offsite= 40580 m3


o number of HDD activities = 8


o Duration of works = 10 weeks at landfall, 44 weeks along Onshore Cable Route and 55 weeks at Converter Station


Operation All impacts


Both Scenarios


Maximum total operational land take =2.61ha (at converter station compound)


Preliminary Environmental Information May 2014


East Anglia THREE Offshore Windfarm


Maximum ranges provided within project details.


Chapter 19 Soils, Geology and Ground Condition Page 10


Rationale


Maximum values provided within the project description


For Scenario 1, as stated above, access is being refined and therefore the worst case footprint may change.


Note that the haul road does not take up the entire 37km route due to the HDD crossings at waterbodies, roads etc.


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