Attachment 6 - Odour Impact Assessment - Katestone · 132005.638.06

4. ASSESSMENT METHODOLOGY

4.1       Existing environment

The assessment includes an analysis of the characteristics of the existing environment (Section 5) that are
important for the dispersion of air pollutants. Characteristics include terrain features, regional land uses, existing
sources of emissions, and the locations of sensitive receptors relative to the sources.


4.2       Operational emissions

The following subsections describe the methods used to determine representative, conservative odour emission
rates from the composting and landfill operations that have been assessed. No odour sampling has historically
been conducted at the Noosa Resource Recovery Centre and, given that the composting facility does not yet exist,
it is necessary to rely on the scientific literature for representative odour emission rates. Emission rates have been
identified from a literature review considering assessments of similar facilities, many of which incorporated odour
sampling. 15 odour assessments of composting facilities have been reviewed, alongside 18 assessments of
landfills.

Odour emission rates (ou/s), provided in full in Section 6, were calculated by multiplying the odour emission rate
(ou/m2/s) by the area of emission of the corresponding source.

Modelled emission rates have been chosen to be conservatively representative of the activities occurring at the
site, and to be consistent with previous assessments of composting and landfill facilities within Queensland. The
emission rates used are considered high for the types of waste proposed (noting that the proposed composting
operation will only accept Low and Medium odour risk wastes, whereas most composting facilities accept higher
odour risk waste) and therefore the predictions of the dispersion modelling exercise can be considered worst-case,
and likely an over-prediction of actual impacts.


4.2.1     Composting operation

The modelled sources of odour produced by the composting operations (and their identified odour emission rates)
are detailed in Table 1. The locations of the odour sources as modelled are presented in Figure 2. The emission
rates were sourced as follows:

      •   The odour emission rate of 2.4 ou/m2/s used for green waste is based on sampling of green waste at a
          composting facility in Swanbank, QLD. It is by far the highest odour emission rate for green waste
          identified in the literature review – in most cases emission rates for green waste are well below 1 ou/m2/s.
          It is, therefore, highly conservative.

      •   The odour emission rate of 4.0 ou/m2/s used for freshly mixed waste is based on the emission rate for
          food organics and garden organics (FOGO) from the EAQ Consulting report for Red Hill Waste
          Management Facility in Western Australia (2020). This emission rate is considered highly conservative
          for the proposed composting operation, given that it will not accept FOGO, rather mixing some Low and
          Medium odour risk food wastes with green waste.

      •   The odour emission rate of 1.85 ou/m2/s used for the biofilter was taken from an assessment of a proposed
          in-vessel composting facility in Swanbank, QLD. This facility accepts solid and liquid waste with High and
          Very High odour risk ratings and would, therefore, be expected to have significantly higher odour
          emissions treated by its biofilter, as compared to the proposed composting operation. Well-maintained
          biofilters are typically at least 90% efficient at removing odour and given that the proposed composting
          operation will only accept Low and Medium odour risk wastes, it can reasonably be expected that
          emissions from the biofilter will be well below 1.85 ou/m2/s. Therefore, the use of this emission rate is
          conservative.


 Katestone Environmental Australia Pty Ltd                                                       17 September 2026
 D25072-8 Noosa Council - Noosa Composting Odour Assessment - Final                                        Page 8