ASSESSING ODOUR IMPACTS OF AN ALUMINA REFINERY BY SOURCE MEASUREMENT, DISPERSION MODELLING AND FIELD ODOUR SURVEYING

Concern about the impact of odour emissions from a range of industrial land uses on neighbouring amenity has significantly increased in Australia in recent years. Government response has been to introduce odour standards or guidelines such as in WA. Alumina refineries are characterised by an odour often described as a ‘wet cement’ smell. The introduction of new processes to enhance production efficiency can create stronger odour emissions. In Western Australia odour from Alcoa’s Wagerup alumina refinery has become the subject of growing community concern, resulting in concerted attention by the company and regulatory authorities. Traditional methods of odour impact assessment have relied on source measurement by dynamic olfactometry combined with dispersion modelling. Many debates continue on how real the modelled impacts are and how accurate the predictions can be regarded. Using Wagerup Refinery as a case study of a plant emitting industrial odours within a rural community, this paper discusses the use of field odour surveys as a technique for ‘validating’ model assumptions and predictions. It also looks at the relative efficacy of three common dispersion models to the challenge of ‘reasonably’ representing actual odour impacts for a complex industrial source in a rural setting. It is concluded that a combined approach utilising all techniques is necessary to gain a realistic assessment of odour impacts on local communities.