Responding to odour complaints is fraught with difficulties. Not only is it time-consuming for both operators and regulators but it also involves dealing with a range of human emotions and behaviours—some positive and some negative. Sometimes the odour that is the source of the complaint is only very weak (of borderline intensity) and is generated by a facility that may be operating within the conditions of its resource consent (e.g. no offensive or objectionable odour at or beyond the site boundary). Often, the reliance on field odour investigations, which are subjective as they involve human assessors (odour scouts), can lead to uncertainty and conflict between operators, the public and regulators, particularly for sites where the odour intensity (strength) is weak, where the odour is transient, where the source of odour is unclear or where inconsistent methods are used. In these situations, different investigation and assessment techniques are useful to investigate to source of nuisance odour and to assess the impact on the local community.
The focus of this webinar, presented by Dr Doug Boddy, is on the investigation and assessment of odour at an existing municipal solid waste landfill with a history of odour complaints. The project sought to investigate and assess the odour effects at the nearest identified sensitive receptors (e.g. residential properties) to the landfill and to make recommendations regarding the control of odour, where required.
In order to determine the potential for odour nuisance effects in the community due to odour emissions at the landfill, the following assessment techniques were employed:
- Review of the complaints record for the site;
- Field odour investigation at the landfill to identify the principal sources of odour and to record the odour intensity, character, frequency and duration downwind of the principal odour emission sources;
- Instantaneous surface monitoring for methane (as a surrogate for odour) at the landfill to identify emission hotspot locations (areas of peak landfill gas concentration);
- Surface odour emissions monitoring at the landfill and analysis by dynamic dilution olfactometry (DDO);
- A detailed assessment for odour emissions at the landfill involving atmospheric dispersion modelling using CALPUFF. The results of the dispersion modelling assessment were used to evaluate a number of mitigation options (odour control measures) for the site; and,
- Continuous ambient air quality monitoring for hydrogen sulphide at the landfill (two separate monitoring campaigns).
The assessment methodologies and techniques, and the recommended odour measures for the landfill are discussed. Each of these techniques enabled the principal emission sources or activities undertaken at the landfill to be identified and assessed. Employing the mitigation measures recommended in this study has the potential to reduce the likelihood of further odour nuisance effects occurring in the local community.
Independent commissioners were appointed by the consent authority to hear and decide a Notice of Review and application to change some of the conditions of the existing resource consents for the landfill, including the consent relating to the discharge of contaminants to air (namely odour). The independent commissioners granted the review and variation to the consent conditions, as per the approved consent conditions (decision version).
About the presenter: Dr Doug Boddy is a Senior Air Quality Consultant at Pattle Delamore Partners, based in Auckland.
Doug has over 15 years’ experience working in the air quality sector, the majority of which has been in multi-disciplinary environmental consultancies in New Zealand, Australia and the UK.
He is experienced in managing complex, multi-disciplinary projects and has undertaken air quality impact assessments, atmospheric dispersion modelling, ambient air quality monitoring, environmental management plans, and odour and dust assessments for a wide range of emission sources for public and private sector clients.