Appendix 6. Odour Buffer Assessment [As Published] · 132007.2399

                                                                                              [23]
              Odour Buffer Assessment
              StarCo Developments


interest is the model’s ability to provide an assessment of the times of day when potential odour
issues may occur. Figure 6.2 shows that the highest impacts of odour from the STP can be
expected to occur at night (i.e. during times of the most stable atmospheric conditions). The time
series analysis for the Precinct G development indicates that the highest odour impacts (being at or
below the guideline level) can be expected to occur between the hours of 8 pm and 6 am when
people are most often indoors where odour levels are less noticeable, especially in cooler weather
when windows and doors are less likely to be open.

Finally, comparison of the modelled and observed odour levels shown in Table 8.4 is significant.
The upper end of the range of predicted odour levels for each observation is indicative of the
‘plume centreline’ concentration’, which is predicted to occur somewhere in the vicinity of the
observation site. In field situations where odour is being observed, it is difficult to ensure that the
observation set is performed at the plume centreline, because this needs to be estimated prior to
the observations being made under conditions of (almost invariably) fluctuating wind direction.
Taking observation ’2’ in Table 8.4 as an example, the estimated concentration from observation is
approximately 0.8 ou (in the range 0.75 - 0.91 ou). The corresponding CALPUFF prediction is in the
range <0.1 to 1.0 ou, where 1.0 ou is the model prediction of the centreline concentration. In
other words, CALPUFF predicts that somewhere near the observation point the odour concentration
was as high as 1.0 ou. This is therefore consistent with the observed odour levels, since we cannot
be sure where the centreline was in relation to the observation point.

The other two observations indicate that the model may have somewhat underpredicted in the case
of observation ‘4’ and overpredicted in the case of ‘5’. Overall, given the small data set it is
apparent that there is a general, broad agreement between the observed and modelled results.




10 CONCLUSION

An evaluation of the potential for development of Noosa Springs within the current buffer zone
around the Noosa STP has been undertaken using a combination of assessment techniques. The
current buffer zone was established some years ago and the Noosa STP has since had a major
upgrade that includes a high level of odour control.

After assessing the combined results of dispersion modelling, odour complaints records and a small
community survey we conclude that the odour impacts at the area of interest within the Precinct G
development are not expected to result in significant annoyance to future residents. Any odour
impacts are predicted to occur at night and would be infrequent. As such, PAE concludes that the
limited development within the existing 600 m buffer proposed by StarCo should not be refused on
the grounds of possible adverse odour impacts.




1898a report final.doc                                                      PAE Job Number 1898a