A fugacity approach for generating a landfill gas trace component source term.

The quality of risk assessment output is determined by the input data used in environmental distribution, dispersion and exposure models. Whilst recent focus has been on the development of regulatory exposure assessment models for landfills, risk analysts are keenly aware of the need for improved source term models in order to improve confidence in risk assessments and allow better targeting of risk management actions. This research sought to reconcile measured concentrations of selected priority trace components in landfill gas with potential source term loadings that could be generated within landfilled waste. A fugacity approach estimated the loadings of four priority trace components required to generate the source-term for landfill gas risk assessment models; vinyl chloride (chloroethene), benzene, 1,3- butadiene and trichloroethylene. Three fugacity models, coded originally for soils, were adapted for an evaluative landfill environment, developed using data from the Brogborough (UK) test cells. Modelled concentrations were within the range of those observed in the field.