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

                                                                                               [7]
              Odour Buffer Assessment
              StarCo Developments


3.3.1       Odour Annoyance Threshold (Concentration) Guidelines

The Guideline sets out the following advice in relation to odour concentration guidelines:

        Proponents of new facilities may undertake an impact assessment with relevant inputs of
        emissions and local meteorology to an air dispersion model to provide estimates of the
        likely odour impacts in the surrounding environment. The inputs should be as detailed as
        possible, reflecting any variation of emissions with time and including at least a full year of
        representative hourly meteorological data. The modelled odour concentrations at the
        “most exposed existing or likely future off-site sensitive receptors” should be compared
        with the following guideline values.

                0.5 ou, 1-hour average, 99.5th percentile for tall stacks

                2.5 ou, 1-hour average, 99.5th percentile for ground-level sources and down-
                washed plumes from short stacks, and

                for facilities that do not operate continuously, the 99.5th percentile must be applied
                to the actual hours of operation.

Further details are contained in section 5.1 of the Guideline.

In the application of this type of guideline, the appropriate criterion for the Noosa STP would be
C99.5 1hr = 2.5 ou, since it is not a ‘tall stack’ source type.



3.3.2       Odour Intensity Guideline

The Guideline states:

        EPA will accept an assessment of odour impacts from the sources using an odour intensity
        guideline value. This approach recognises the fact that the same concentration (stimulus)
        of different odorants does not elicit the same perception of intensity (response) in human
        observers..., and

        …the proponent should conduct computer modelling and compare the results with the
        following criterion:

                odour concentration equivalent to an intensity level of “weak” multiplied by
                the relevant default peak to mean factor, averaged over 1-hour, 99.5th
                percentile, applicable at the “most exposed existing or likely future off-site
                sensitive receptors”, and

                for facilities that do not operate continuously, the 99.5th percentile must be
                applied to the actual hours of operation.

The application of this criterion requires an odour intensity relationship to be determined for the
odour sources under investigation. No such relationship has been determined for this study.
However, based on our knowledge of unpublished data from various interstate STP sources it is
likely that this approach would yield a value slightly higher than the 2.5 ou criterion noted above.




1898a report final.doc                                                      PAE Job Number 1898a