Simulating groundwater contaminant migration at Villa Farm lagoons

Lagoons at Villa Farm near Coventry, UK were used for the disposal of indus trial liquid waste after 1967. The lagoons were unlined and a leachate plum e developed in the underlying thin sand aquifer. As part of a research prog ramme into controls on the migration of landfill leachate, a two-dimensiona l areal model describing the regional scale movement of chloride and phenol in the aquifer has been developed. Parameter ranges for advection, dispers ion, degradation and adsorption have been established through model calibra tion, constrained by the results from previous laboratory studies. Linear r epresentations of the adsorption and degradation processes are found to yie ld satisfactory results on the time and space scales adopted for the simula tions. The model development has highlighted some important issues that hav e to be confronted when analysing the evolution of a plume based on short-t erm, fate-time data. The uncertainty in the geometry of the aquifer on the simulated flow system has been examined using geostatistical methods.