Table 26.2.Worst Case Assumptions Impact


Construction Impacts


Impact 1: Increased noise on residential receptors at landfall during construction


Scenario 1


 Construction of up to 4 transition pits


 Pulling of up to 4 cables through pre-installed ducts


 Short HDD approach will require construction plant to access beach to enable cable landing, beach trench and installation through pre-installed ducts


 Likely to require up to 10 weeks working


Scenario 2


 Installation of up to 4 cables and 4 ducts


 Construction of up to 4 transition pits


 Use of HDD to install ducts  Likely to require up to 10 weeks working


Two landfall scenarios Scenario 1 assumes East Anglia ONE has been installed with ducts into the beach.


Two ducting options are considered. A long HDD and duct option where the duct extends into the subtidal and cable installation happens at sea with a pull through from the shore end.


A short HDD and duct is considered the worst case option as the duct ends in the intertidal and cable connection is made on the beach with cable trenching from the mid shore into the subtidal.


Sensitive receptors which fall within the noise impact buffer zone.


Impact 2: Increased noise on residential receptors along the onshore cable route during construction


Scenario 1


 Pulling of up to 4 cables through pre-installed ducts


 Creation of 9 CCS  Likely to require up to 44 weeks working


Scenario 2


 Installation of up to 4 cables and 4 ducts


 8 HDD crossings of water courses of sensitive areas


 Likely to require up to 44 weeks working


Impact 3: Increased noise on residential receptors at converter station during construction


 Construction of converter station  Potential use of piling to create foundation suitable for heavy equipment.


Sensitive receptors which fall within the noise impact buffer zone.


Sensitive receptors which fall within the noise impact buffer zone.


Key design parameters forming worst case scenario


Rationale


Preliminary Environmental Information May 2014


East Anglia THREE Offshore Windfarm


Chapter 26 Noise and Vibration Page 4


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