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Biogas Systems Australia


Regional Closed Landfills

October 29, 2018

Risk Assessment and Continuous Monitoring 


A number of closed landfills in close proximity to sensitive receptors were required to be assessed to ensure that the risks, to site users and members of the public, associated with uncontrolled release of landfill gas were at acceptable levels. The landfill gas risk assessment (LFGRA) was undertaken across three main sites in a regional setting.


The project was carried out in a staged approach. Firstly, desktop based studies were undertaken to characterise the various sites and carry out an initial risk screening to ascertain the immediate (acute) risk to site workers, users and occupants in nearby residential dwellings.


Site investigations and risk assessments were then carried out in accordance with best practice guidance used to assess acute risks associated with chronic health impacts from trace gases typically present in the LFG mix and acute risk associated with accumulation of methane and carbon dioxide. This involved installation of a number of LFG monitoring bores, installation of AmbiSense GasfluxTM continuous monitors, test pitting, indoor air monitoring, nitrogen injection trials and the full array of LFG investigation techniques.


The outcome of the risk assessments was integrated with the desktop studies, investigations and lithology assessment to develop a comprehensive, as well as a human health risk assessment Conceptual Site Model (CSM). The risk assessment was then used to provide recommendations for improvements to mitigate risks from LFG, which were incorporated into a practical action plan.