Draft National Wind Farm Development Guidelines - July 2010

If a significant amount of time has passed between the planning assessment for a wind
farm development and the subsequent assessment for a second wind farm in the area,
in the order of 5-10 years or more, and it is considered that the background noise in the
area may have changed over this time, how are noise level limits to be established for
the second wind farm
If the background noise levels are expected to be lower than when the initial noise impact
assessment occurred, they will be hard to measure in the presence of operational noise
from the existing wind farm. In this case, the second wind farm should comply with the
minimum noise level limit across the assessable wind speed range and not increase the
combined level of wind farm noise emission above the established noise level limits.
If background noise levels are expected to be higher, monitoring may be carried out
where this is not influenced by emission from the original wind farm. If this is not possible, the
second wind farm should comply with the minimum noise level limit across the assessable
wind speed range and not increase the combined level of wind farm noise emission
above the established noise level limits.
How should cumulative noise limits be considered where other industrial activity such as
mining, which changes the character of the background noise environment in the area,
commences during the period between wind farm developments
Issues such as this should be thoroughly examined on a case-by-case basis, in close liaison
with the relevant authority. There are likely to be a range of noise emission controls which
may be applicable to the various sound sources and consultation with the relevant
authority will be critical in achieving a satisfactory outcome.
Where another significant sound source commences in an area after the development of
the first wind farm and prior to the second, and this sound source is expected to continue
through the lifetime of both wind farms, it is generally expected that new background
noise level monitoring would not be conducted. However, if new background noise
monitoring was conducted it would be important to ensure that noise emission from the
first wind farm does not significantly contribute to the background noise level at the
monitoring location, and that the noise limits for the new wind farm do not permit
‘creeping noise’.
Where the new sound source is not expected to carry on in the long term, beyond the
lifetime of both wind farms, it is unlikely that any new noise level limits would be established
at relevant receivers.
How should cumulative noise limits be applied to a group of dwellings where the ‘worst
case’ affected dwelling is different for each proposed wind farm
The ‘worst case’ relevant receiver determined for the noise impact assessment of the first
wind farm will likely be exposed to the greatest level of wind farm noise emission from the
first wind farm as well as experiencing the largest change in the ambient noise
environment.
Where an alternative property from the same cluster of receivers is determined to be the
‘worst case’ receiver for the second wind farm the conservative approach, which is
recommended here, is to assume that the second property is exposed to the same noise
emission from the first wind farm as the first worst case receiver. The contribution from the
second wind farm should comply with noise criteria as outlined in Section B.5.2.
Draft National Wind Farm Development Guidelines – 2 July 2010 Page 63