Appendix 5 - Air quality assessment report

predicted vs 16.3% measured). However, overall source-to-receiver winds towards the northern two-
storey buildings are predicted to occur as a similar frequency to the measured data (i.e. predicted
southerly flows (SSW,S,SSE) are noted to be similar compared to the measured data (28.1%
measured and 25.1% predicted)).

Calm conditions are noted to be well represented by the model with calm conditions occurring at the
BOM station 13.7% of the time vs 13.6% predicted. CALM conditions are slightly lower at the subject
site which is likely due to the site’s close proximity to the coast line (10.7% predicted). Low wind
speeds are over-represented by the model with wind speeds less than 2 m/s (measured 17.5% and
predicted 22.6%).

Overall, based on the above comparison, the predicted wind conditions are considered suitable for
the assessment of potential air quality impacts.

4.3.2      Predicted Atmospheric Stability
The amount of turbulence in the ambient air has a major effect upon the rise and dispersion of
emissions. The amount of turbulence in the atmosphere is often described using series of six Pasquill
stability classes A, B, C, D, E and F. Of these, Class A denotes the most unstable or most turbulent
conditions and Class F denotes the most stable or least turbulent conditions. Table 4.2 provides a
summary of the predicted atmospheric stability conditions (derived by CALMET) for the area.

Table 4.2 - Summary of Predicted Stability Classes by Hour

                                        Predicted Pasquill Stability Class
    Hour
                     A             B               C                         D                        E                       F
      0              0              0               0                      139                       28                      196
      1              0              0               0                      150                       23                      190
      2              0              0               0                      164                       17                      182
      3              0              0               0                      177                       16                      170
      4              0              0               0                      181                       19                      163
      5              0              0              38                      207                        8                      110
      6              0             11              96                      212                        2                       42
      7              0             29              105                     229                        0                        0
      8              1             59              69                      234                        0                        0
      9              2             69              63                      229                        0                        0
      10            14             82              60                      207                        0                        0
      11             6             90              60                      207                        0                        0
      12             2             88              83                      190                        0                        0
      13             0             66              94                      203                        0                        0
      14             0             26              97                      240                        0                        0
      15             0             12              104                     247                        0                        0
      16             0              1              72                      290                        0                        0
      17             0              0               8                      259                       21                       75
      18             0              0               2                      150                       74                      137


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                                                        Belo Developments- Air Quality Assessment - Proposed Service Station, Noosaville
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