Sand–bentonite liners: field control methods

Abstract

Soil–bentonite mixes are frequently used as impervious liners for waste disposal projects. These mixes can be controlled in the field by local permeability tests or by their global performance. The accuracy of in situ local tests is found to be limited after the thermal dilation of infiltrometers is considered. A method is developed to analyze the total leakage rate and to detect hydraulically induced damage and deterioration of hydraulic defects. Finally, the use of coupled hydrometer tests or X-ray diffraction tests is recommended to determine local values of bentonite content and to verify whether the in situ variability in bentonite content is similar to that provided for in the design. Key words: impervious liner, soil, bentonite, permeability, field control.