Minimum Thickness of Compacted Soil Liners: II. Analysis and Case Histories

Abstract

The stochastic models described in a companion paper were used to analyze compacted soil liners with a variable number of 15 cm (6 in.) thick lifts. No optimum number of lifts could be defined based on first‐passage time; first‐passage time increased as the thickness increased. Both models showed that the flux through the liner and the equivalent hydraulic conductivity decreased and the mean hydraulic conductivity (modeled as a lognormally distributed random variable) of lifts decreased. There was little benefit to increasing the number of lifts beyond four to six lifts. An analysis of case histories of in situ hydraulic conductivity also showed little reduction in hydraulic conductivity when the number of lifts was increased beyond four to six. Based upon hydraulic conductivity considerations, the recommended minimum thickness of compacted soil liners is four to six lifts, or 60 cm to 90 cm (2 ft to 3 ft).