Clay Liner Permeability: Evaluation and Variation

Abstract

The primary criterion used in evaluating the suitability of hazardous waste landfills for containing hazardous wastes is permeability, and many regulatory agencies have adopted regulations requiring clay‐lined hazardous waste landfills to have a coefficient of permeability no greater than a fixed value. However, the measurement of in‐situ permeability of compacted clay is time consuming and difficult. If used to monitor construction, it slows the construction rate. Another equally important problem is that clay‐liner permeability is extremely variable. Solutions to both of these problems are presented. Firstly, a relationship is developed between permeability and easily measured dry unit Weight and moisture content. This would allow for the immediate monitoring of clay liners during construction. Secondly, an alternative is provided to the conventional approach in which permeability is treated as a single‐valued quantity. A probabilistic description of the permeability of clay liners is developed from considerations of the heterogeneity of the soil. This would improve the design of clay liners by establishing confidence levels associated with possible ranges of the permeability.