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 inenvironmental distribution, dispersion and exposure models. Whilst recent focushas been on the development of regulatory exposure assessment models forlandfills, risk analysts are keenly aware of the need for improved source termmodels in order to improve confidence in risk assessments and allow bettertargeting of risk management actions. This research sought to reconcile measuredconcentrations of selected priority trace components in landfill gas withpotential source term loadings that could be generated within landfilled waste.A fugacity approach estimated the loadings of four priority trace componentsrequired 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 anevaluative landfill environment, developed using data from the Brogborough (UK)test cells. Modelled concentrations were within the range of those observed inthe field.