Appendix 5 - Air quality assessment report

samples were then analysed for total VOCs and odour concentrations for use in determining a
correlation factor. This correlation factor has then been applied to VOC emission factors for various
activities to derive odour emission rates. Odour sampling was completed and analysed in accordance
with AS 4323.3:2001 Station source emissions – Determination of odour concentration by dynamic
olfactometry.

Based on the sampling, an odour-to-Total VOC ratio of 439 (OU:g/m3) was established. Total VOC
emission data was factored by 439 to establish odour emission data.

3.1.4          VOC Composition
The types of pollutants emitted from service stations include a range of VOCs. Air Noise Environment
has obtained VOC composition data from the analysis of head space vapour in a fuel storage
container containing unleaded petrol. Duplicate samples were collected on charcoal sorbent tubes
and analysed for total VOCs and speciated VOCs. The sampling identified benzene, toluene, xylene,
ethylbenzene and cumene as being above the detection limits.

Cyclohexane and n-hexane was not included in the speciated VOC analysis. For the purpose of the
assessment, reference has been made to Equation 2 of the NPI Emissions Estimation Technique
Manual for Aggregated Emissions from Service Stations (1999). The equation provides a means for
estimating vapour weight % of a compound based on the liquid weight % and associated boiling
point. Based on a review of various Australian Safety Data Sheets for petrol, n-hexane composition in
petrol is up to 5%. Information on cyclohexane was not provided in any Australian Safety Data
Sheets (possibly due to very low weight % values). Nevertheless, as a conservative approach, a
weight % value of 5 has been considered based on a review of international safety data sheets for
petrol.

Table 3.3 presents a summary of the VOC composition data considered in this assessment.

Table 3.3 - Composition of Unleaded Petrol
                 Species                   VOC Vapour Composition %                                           Source
                 Benzene                                0.838%                                    ULP head space sample
               Cyclohexane                              1.58%                        Equation 2 of NPI Service Station Manual
              Ethylbenzene                              0.267%                                    ULP head space sample
                n-Hexane                                2.47%                        Equation 2 of NPI Service Station Manual
                                                                  a
                 Styrene                             < 0.00190%                                   ULP head space sample
                 Toluene                                3.24%                                     ULP head space sample
                 Xylenes                                1.45%                                     ULP head space sample
                 Cumene                                0.0134%                                    ULP head space sample
a
    Styrene was below the detection limit. Styrene has been considered in the assessment as this compound is specifically
      referred to in the BCC Service Station Code.




3.1.5          Fuel Throughput
In order to convert mass per volume of fuel emission factors, it is necessary to determine the likely


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