environmental statement - Rotherham's Online Application for ...

MITIGATION
Receptor Quiet Daytime LA90, 10 min Night-time LA90, 10 min
Brampton Villa (H6) 28.0 – 67.6 24.9 – 57.1
Aston (H7) 26.9 – 52.9 21.1 – 49.5
Hardwick (H8) 28.4 – 60.3 25.0 – 54.9
9.26 The exact model of turbine to be used at the site will be the result of a
future tendering process. Achievement of the noise limits determined by
this assessment will be a key determining factor in the final choice of
turbines for the site. Predictions of wind turbine noise have been made,
based upon sound power level data for the REpower 3.3M wind turbine
and a noise prediction model procedure that can be considered to be
worst-case. Full noise data for the REpower 3.3M is not yet available so it
has been assumed for the purposes of this assessment that octave data
for another REpower turbine, the MM92 2.0MW is comparable. The octave
data has been increased uniformly for each band so that the total sound
power level is equal to that stated for the REpower 3.3M. For
completeness the MM92 has also been modelled and it has been shown
that the REpower 3.3M is louder at all windspeeds (as shown in Appendix
5, Figures 5.1-5.8). All results tables have therefore been based on the
REpower 3.3M noise data.
PREDICTED EFFECTS
9.27 Noise levels arising from the operation of the proposed wind farm were
calculated using the propagation model contained within Part 2 of
“International Standard ISO 9613-2, Acoustics – Attenuation of Sound
during Propagation Outdoors”. The model uses as its acoustic input data
the octave band sound power output of a turbine suitable for this
development (in this case the Repower 3.3M 3.3MW machine) and
calculates, on an octave band basis, attenuation due to geometric
spreading, atmospheric absorption and ground effects. The noise model
was set up to provide worst case noise predictions, including hard ground
attenuation, no barrier effects, and low levels of atmospheric attenuation.
Changes in wind shear between daytime and night-time periods were also
included in the predictions.
9.28 The assessment of the proposed wind farm noise is contained within
Section 5 of the Noise Assessment (Appendix 5). This provides an
assessment of the wind farm in accordance with the requirements of
ETSU-R-97. The assessment is summarised in Tables 9.3 and 9.4.
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Penny Hill Wind Farm
Environmental Statement