ABSTRACT
Sanitary landfills have been, and continue to be, the most economical method for solid waste disposal. In New Zealand, until very recently, few municipal landfills were lined. The older landfills typically have no lining and great reliance is placed upon the natural attenuation of contaminants in the underlying unsaturated soils and the groundwater aquifer. Leakage of inorganic and organic pollutants from unlined landfills over a period of time can influence the groundwater quality and may pose a threat to drinking water resources. The transport of landfill leachate in soils is subject to various physical, chemical and biological processes that affect the eventual concentration of pollutants in soils and groundwater. Understanding the movement of leachate in the soil is essential for predicting the potential for groundwater pollution from landfills. In order to estimate the environmental risk and develop strategies for groundwater protection against contamination by landfills, an understanding of the chemical transport and behaviour of pollutants in soil-groundwater systems is required.
