MINIMUM THICKNESS OF COMPACTED SOIL LINERS .2. ANALYSIS AND CASE-HISTORIES

The stochastic models described in a companion paper were used to anal yze compacted soil liners with a variable number of 15 cm (6 in.) thic k lifts. No optimum number of lifts could be defined based on first-pa ssage time; first-passage time increased as the thickness increased. B oth models showed that the flux through the liner and the equivalent h ydraulic conductivity decreased and the mean hydraulic conductivity (m odeled as a lognormally distributed random variable) of lifts decrease d. There was little benefit to increasing the number of lifts beyond f our to six lifts. An analysis of case histories of in situ hydraulic c onductivity also showed little reduction in hydraulic conductivity whe n the number of lifts was increased beyond four to six. Based upon hyd raulic 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).