The Stability of the Oxford Clay as a Mineral Liner for Landfill

The paper discusses the mineralogical and chemical stability of the Oxford Clay as a landfill liner for the containment of domestic waste. The results from a series of batch equilibrium experiments with the mudrock and a synthetic leachate are compared with samples of a liner cored from a 15-year-old site in the Formation. The effects of leachate on the Clay include mineral dissolution, exchange of cations, particle-size reduction and collapse of illite-smectite. In situ mixed-assemblage mineral liners, such as the Oxford Clay, are capable of attenuating leachate components and buffering acid leachates whilst the predominant clay minerals, i.e. illite and kaolinite, remain stable. Alterations to the mineralogy and chemistry of the samples resulting from both short-term and long-term exposure to leachate are discussed with reference to the implications to landfill practice.