Residents of Kalgoorlie-Boulder have been grappling with a persistent unpleasant odour since 2023, prompting local authorities to hire OPAM Consulting’s Philippe Najean to investigate its source. Najean’s report, released earlier this year, identified multiple nearby sources of the foul smell, notably the local wastewater treatment plant.
Initially, the council dismissed claims that the wastewater facility was the origin of the odour. However, following Najean’s findings, they began implementing measures to lessen the unpleasant impact on the community, particularly by managing the treatment lagoons.
As winter progresses, the council is now employing lime treatment in the lagoons to maintain stable pH levels and minimise odour. Kalgoorlie-Boulder’s Chief Executive, Andrew Brien, noted that lower temperatures and reduced sunlight during winter can lead to decreased pH levels, which in turn heightens the likelihood of odour release. The council closely monitors pH levels daily, administering lime as necessary to prevent the system from falling out of balance and further diminishing odour emissions.
Brien also reported a significant improvement in odour levels this winter compared to the previous year, attributing this to more stable pH levels and reduced lime application frequency, which has aided effective odour control. Furthermore, the council is testing mechanical aeration techniques in the lagoons to enhance oxygen levels and plans to upgrade its long-standing Intermittent Decanted Extended Aeration plant.
Adjacent businesses identified in Najean’s report as potential contributors to the odour have been provided with relevant information to encourage their own corrective measures. With nearly 24 years of experience in odour management, Najean relies primarily on his sense of smell, which he calibrates regularly at an olfactometry lab to ensure accuracy in detecting odours.
The council continues to explore various strategies to further reduce odour emissions, working not only within its facilities but also coordinating efforts with local industries to tackle the issue collaboratively.