Abstract
A new risk assessment method intended for comparing long-term environmental performance of different types of sanitary landfills was customized. Processes occurring within the hydrogeological environment were excluded from modeling, because they can be addressed separately. Only parameters directly related to leachate composition at the bottom of the landfill and leachate losses into the subsoil after landfill closure which can be reliably determined by evaluating already available information from the scientific literature were considered as necessary inputs for quantitative modeling. Once the simulated outcomes for a primary output ‘’fugitive emissions of a reference pollutant into the subsoil’’ are acquired, more complex outputs can be derived, too. Commercially available risk assessment software which operates within an Excel environment was used to fulfill the task.•Uncertainty of data as well as heterogeneity and complexity of landfill systems was considered by attributing the selected input parameters with adequate probability density functions•Probability density functions attributed to the inputs differ considerably between the antagonistic landfill types•Risk assessments related outputs were defined as probabilities that an aquifer would be polluted due to landfill derived emissions into the subsoil
Highlights
The article is closely related to a research article ‘’Long-term risk assessments comparing environmental performance of different types of sanitary landfills” [1] and Data in Brief article “Longterm groundwater protection efficiency of different types of sanitary landfills: data description” [2]
Vice versa, when comparing environmental performance of different types of landfills, it would be factitious to ignore the fact that hydraulic conductivity is an essential property of clayey barriers just to show that equal probabilistic method was used to calculate long-term leakages considering both, clay-only-lined landfills and landfills equipped with composite liner systems
4) Based on reasonings specifyed above, relations between leakages and input variables required to calculate these leakages can be deterministic in some settings (Darcy law can be applied in situations where hydraulic conductivity and thickness of the clayey barrier at the bottom of the landfill are approximately known) while stochastic in other settings
Summary
Calculation of long-term leachate losses into the subsoil As opposed to the parameter ‘Ct’, calculation of leachate losses ’Qt’ into the underground cannot be applied in a common manner when referring to different landfill types, landfill designs, etc., because the related hydraulical settings appear to be inherently diverse, as contemplated below: 1) Fugitive flow of leachate needs to be evaluated at an annual level for modeling purposes, quasy steady-state flow situations occuring at the bottom of already closed claylined landfills can be hardly assessed in the same way as transient flow situations occuring sporadically at the bottom of inadequately capped above ground dump sites.
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