Characterization of an old municipal landfill (Grindsted,Denmark) as a groundwater pollution source: landfill history and leachate composition

Investigations into the pollution of groundwater from old landfills have, in most cases, focused on delineating the pol lution plume rather than on the landfill as a source of ground water pollution. Landfills often cover large areas and spatial variations in leachate composition within the landfill may have great impact on the location of the main pollution plume in the downstream aquifer. The history of the Grind sted Landfill in Denmark was investigated using aerial photo graphs and interviews. On the basis of the aerial photographs, waste volume and age of the different areas of the landfill were evaluated. A pronounced variability in leachate compo sition was observed in the 31 leachate wells installed through the waste. The spatial variability was analysed by statistical methods, and a semivariogram model was able to describe the variability both on small and large scale. The spatial varia tions in leachate composition are very important for locating the main source of the groundwater pollution and for selec tion of cost-effective remedial action activities.