Competency assessment of two clay soils from South Wales for landfill liner contaminant attenuation

This study focuses on the basic test and evaluation requirements necessary for a successful competency assessment of the contaminant attenuation capab ility of clay soils. Two clay soils from South Wales were chosen for study. Of particular interest is the problem of specification of 'necessary and s ufficient tests' for proper assessments of competency. The teals and evalua tion protocols leading towards confident competency assessment of the candi date clay soils are developed. Soil column leaching studies, together with results from analyses of the physicochemical and mineralogical characterist ics of the soils, are used to determine clay soil contaminant attenuation c apability. The results demonstrate that reliance on a limited amount of inf ormation can lead to some inappropriate premature interpretations that can prove to be harmful. In a situation where attenuation of dissolved metals i s important, only one of the soils tested is considered to be an adequate c lay soil for a clay engineered barrier.