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Rhodes Remediation Odour impacts. Dr Kerry Holmes Holmes Air Sciences. Background. Holmes Air Sciences undertook dispersion modelling for the Lednez and Allied Feeds sites Modelled stack emissions, dust emissions and volatiles from excavation
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Rhodes RemediationOdour impacts Dr Kerry Holmes Holmes Air Sciences
Background • Holmes Air Sciences undertook dispersion modelling for the Lednez and Allied Feeds sites • Modelled stack emissions, dust emissions and volatiles from excavation • Egis Consulting (now GHD) undertook detailed health risk assessment (HRA) and some odour assessment for Lednez • Holmes Air Sciences assessed health risk from stack and dust emissions for Allied Feeds
Challenges for assessment of remediation sites • Stack modelling is relatively straightforward and emissions can be measured • Dust modelling is based on worst-case: controls and reactive strategies reduce the impacts. Influenced by meteorology • Odour and other volatile modelling is more complicated as the source varies across the site and emissions and impacts are very dependent on meteorology
Environmental challenges to our bodies and responses • Temperature - shiver/sweat • Smoke – cough/sneeze • Foul odour – cough/gag • Pungent odour – eye, nose throat irritation • Viruses, bacteria – immune response • Sun – burn/tan
Level of risk is crucial • The remediation process is controlled so that there is no high level risk to any workers or residents
Two components • Loss of amenity from odours • Exposure to toxic volatile components • Two aspects are correlated but not completely
Examples • The most toxic compounds are not necessarily the most odorous and vice versa • There are many compounds such as hydrogen sulfide or styrene where the DEC set goals based on odour rather than toxicity. The threshold of odour detection is well below the toxicity threshold • Similarly there are compounds which have long-term health effects such as benzene which are not highly odorous • Covering stockpiles to reduce volatile components will reduce both toxicity and odour • Masking agents or odour suppressants will reduce odour impacts but won’t affect the toxicity
Monitoring the emissions • Odour monitoring with nasal ranger • Monitoring in exclusion zone for volatiles • Monitoring at boundary for volatiles • Monitoring in the community
Comparison of odour and toxicity(WHO) • Hydrogen sulfide 5 ppb – odour detectable 10 ppm – eye irritation 1000 ppm – dangerous • Styrene 27 ppb – odour detectable 40 ppm – respiratory tract irritation 100 ppm –severe irritation of mucous membranes in eyes
Conclusions • It is important to maintain the boundary monitoring campaign for odour and total volatiles • Whenever high levels of specific compounds are detected at active areas on site, boundary monitoring should also be carried out • Monitoring so far indicates that levels at boundaries are not toxic but on occasions are odorous