Attachment 5 - Environmental Noise Assessment

4 Noise Modelling

4.1      Methodology
Computer modelling has been used to calculate the noise levels at nearby residences. Noise
modelling is used as it is not affected by background noise sources and can provide the noise level
for various weather conditions.
The software incorporates the CONCAWE algorithms enabling the modelling to include the
influence of wind and atmospheric stability. Input data required in the model are:
      ➢ Topographical data;
      ➢ Ground Absorption; and
      ➢ Source sound power levels.


4.1.1       Topographical Data
Topographical data was based on information provided by the client, and obtained from Intramaps.


4.1.2       Ground Absorption
Ground absorption varies from a value of 0 to 1, with 0 being for an acoustically reflective ground
(e.g. water or bitumen) and 1 for acoustically absorbent ground (e.g. grass). In this instance value of
0.6 has been used for the surrounding area, and 0 has been used for the site.


4.1.3       Source Sound Levels
Table 4.2 shows the sound power levels used in the modelling. The sound power levels have been
determined based on file data and manufacturer’s data provided by the client, along with the
measurements of the existing site.




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