Final EIAR - Aurecon AME Environmental | Environmental Projects

Proposed Wind and Solar (Photovoltaic) Energy Facilities on Kangnas Farm near Springbok in the Northern Cape: Final EIR 105
lesser noise sources, such as the substations themselves, traffic (maintenance) as well as
transmission line noise emitted from the proposed wind energy facility.
The exact make and model of wind turbine to be used at this facility is not yet known. It was
indicated by the developer that the proposed wind energy facility would likely use 1.5 – 4.0 MW
wind turbines. For the purpose of the modelling the sound emission levels of a worst-case
conceptual noise source was considered. Typical day time activities would include the operation
of the various wind turbines and maintenance activities (relative insignificant noise source).
However, the day time period (working day) was not considered for this EIA because noise
generated during the day by a wind energy facility is generally masked by other noises from a
variety of sources surrounding potentially noise-sensitive developments.
Times when a quiet environment is desired (at night for sleeping, weekends etc.) ambient sound
levels are more critical. The time period investigated therefore would be a quieter period,
normally associated with the 22:00 – 06:00 timeslot. Maintenance activities were also not
considered for the night time period. Ambient sound levels created due to the operation of the
various Wind Turbine Generators (WTGs) at night were considered. Because of little vegetation,
ground attenuation is minimal, and due to the very quiet ambient sound levels measured, the
extent of the area where the ambient sound levels can be changed is quite extensive. As wind
speeds increase, wind induced noise levels also increase, and the associated ambient sound
levels due to this were also considered at all times together with acoustic energy in the low
frequency range due to wind speed. The magnitude of the sound will depend on a multitude of
variables and will vary from day to day and from place to place with environmental and
operational conditions.
Figure 4.21 illustrates the projected change in ambient sound levels (as modelled with the ISO
model) with a wind blowing at 5 m/s. It considers the likely ambient sound levels (in LA90
statistical sound level descriptor) as well as the projected total noise levels, and calculates how
the operational phase may influence the ambient sound levels at night in similar conditions. The
Noise Control Regulations refers to the 35 dBA level as the acceptable rating for rural areas. As
can be seen the total noise levels however are far below the 35 dBA level and there are few
nearby receptors. As such the possibility of complaints are highly unlikely.
Based on the above considerations, the significance of the noise impact for the revised layout is
considered to be of low intensity, local extent and long term and therefore of low (-) significance
for the proposed wind energy facility. No additional mitigation measures are required and
recommended for the wind energy facility. No operational noise impacts would result from the
proposed solar facility. No difference in significance would result from the proposed wind
alternatives.
c) Mitigation measures
Wind Energy Facility Potential Impacts
• Educate surrounding receptors with respect to the sound generated by the wind energy
facility. Community involvement must continue throughout the lifespan of the proposed
facility.
© Aurecon (2012) No unauthorised reproduction, copy
or adaptation, in whole or in part, may be made.
P:\Projects\108495 Kangnas WEF & PV EIA's\3 Project Delivery\4 Reports\FEIR\FEIR 210213 Final.doc