on the methodology provided in BS4142, which states that an exceedance of background noise levels by 5dBA is of “marginal significance” (Medium) and an exceedance of 10dBA is “likely to cause complaints” (High).
70.
The use of the 65dB LAeq 12hr as a threshold level is further supported by the working hours for construction activities predicted for East Anglia THREE daytime works falling within daytime hours. The exceptions to this would be HDD drilling operations which require 24 hour working during the drilling process (Scenario 2 only) and some limited activities during construction at the converter station.
Table 26.10 <64dB
65 – 69dB 70 – 74dB > 75dB
Construction noise impact magnitude criteria
Construction noise level at receptor (dB LAeq,12h)
Negligible Low
Medium High
Impact magnitude – construction related traffic noise 71.
Table 26.11 shows noise impact criteria for the assessment of changes in road traffic noise due to the addition of project related construction traffic. This table has been derived from Table 3.1 of DMRB.
72.
It is important to note that the magnitude of construction noise impacts are derived from changes to the baseline level rather than the trigger or threshold level approach used with respect to onsite construction noise impacts on receptors. This approach affords better protection from noise impacts of the development for receptors in relatively quiet existing environments
Table 26.11
0.0 – 0.9dB 1.0 – 2.9dB 3.0 – 4.9dB >= 5.0dB
Increase in traffic noise level (dB LAeq,12h)
Changes in construction traffic noise - impact magnitude criteria Impact magnitude
Negligible Low
Medium High
Impact magnitude – converter stations operational noise 73.
Under construction Scenario 1, it is proposed that the East Anglia THREE cable connection will feed into a separate converter station, located alongside the East Anglia ONE converter station. It is considered appropriate to use the converter station modelling results obtained in the East Anglia ONE ES as an accurate
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 26 Noise and Vibration Page 22
Impact magnitude
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