The use of hydraulic conductivity (k) of soil material as the sole basis for sanitary landfill liner design is reviewed. On one hand, k measurements obtained in the laboratory often vary by several orders of magnitude. On the other, laboratory-measured k values fail to address field behavior, where crack formation before and (or) during landfill operation may control the bulk permeability.A synaerisis shrinkage test (SST) to study the soil shrinkage caused by municipal solid waste (MSW) leachates is introduced. Leachates cause soil shrinkage by reducing interparticle repulsive stresses thereby increasing effective stress. The effective stress concept and double layer theory adequately describe the synaerisis shrinkage phenomenon. A strong correlation was obtained between percent strain, the soil–liquid parameter determined from SST results, and a volume change parameter (free swell difference, FSD) from sedimentation test results. The results provide a basis for a broader approach to landfill liner design. The SST, which supplies information on both volume shrinkage and permeability changes caused by leachate, provides a useful laboratory procedure for evaluating liner materials. Key words: clay liners, shrinkage, leachate, synaerisis, hydraulic conductivity.
On the Utilization of Fly Ash and Cement Mixtures as a Landfill Liner Material
