This research was conducted to study the changes in permeability of a sand/bentonite liner made under standard compaction conditions and permeated with solutions containing the heavy metals Pb+2, Zn+2 and/or Cr+3. The fine particle size distribution and the free swelling capacity of the bentonite were taken as indicators of the impact of contaminants on the liner's properties.
Generally, particles of bentonite were coarser when in contact with solution ontaining heavy metals. Its free swelling capacity decreased when heavy metal concentrations increased. It is shown that with heavy metal solutions the permeability of a sand/bentonite liner increased by three orders of magnitude. The ion Cr+3 which had a greater impact on the free swelling capacity may have led to a rapid change in permeability. When permeability increased rapidly, heavy metals were present earlier and in higher concentration at the outlet of the liner.