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

                                                                                              [6]
              Odour Buffer Assessment
              StarCo Developments


Averaging times for odour criteria are generally either 1 hour or 3 minutes, or in the case of NSW
the ‘nose response time’, taken to be approximately 1 second. Dispersion models that are used for
predicting or simulating odour concentrations utilise a basic time interval of one hour for individual
calculations. For smaller averaging times, the 1-hour result is converted using a statistical
relationship between concentration and averaging time.

The percentile value refers to the percentage of time (usually over a full year) during which the
actual odour concentration must be within the criterion concentration.

The shorthand notation incorporating these parameters is written in the form Cp,t where C is the
concentration and the subscripts p and t refer to the percentile value and the averaging time,
respectively. For example, C99.5 1-hr refers to the 99.5th percentile 1-hour average concentration.



3.3 Queensland Odour Guideline

In July 2004, the Queensland EPA released the final form of its Guideline on ‘Odour Impact
Assessment from Developments’. This document had been in development for some years, a fact
reflecting the challenges in developing a comprehensive odour policy.

For the modification or expansion of existing facilities, relevant to this application, the Guideline
states:

        “For proposed modifications to an existing facility, proponents should review its complaints
        data to assist in determining the likely impacts of the modifications on complaint
        frequency. The experience of industries with similar discharges should also be drawn upon
        to identify proven odour management practices. Proponents are also encouraged to
        consult with local community members to ascertain if there are any chronic odour impacts
        in the community. Techniques such as odour annoyance surveys and odour diaries may
        also be of assistance in determining likely impacts from the modifications. Further details
        are provided in Appendix A [of the Guideline].

        “Atmospheric dispersion modelling may assist in predicting potential impacts from
        modifications to an existing facility, however community feedback on existing operations
        should be given greater weight than modelling estimates of the same. In particular
        modelling should not be used to explain away adverse community feedback. Dispersion
        modelling may be used to identify sources of odours at a facility and to estimate relevant
        contributions of the sources. This information may be used to develop cost effective odour
        source control strategies.”

For the assessment of odours caused by complex mixtures of odorous compounds, such as odours
from wastewater treatment plants or intensive livestock operations, the Guideline sets out three
possible approaches to establishing criteria for assessing acceptable levels of impact based on
odour dispersion modelling:

        Odour annoyance threshold (concentration) guidelines;

        Odour intensity guideline; and

        Alternative assessment tools for odour assessment for the expansion of existing activities.

These are explained below.



1898a report final.doc                                                     PAE Job Number 1898a