Centrifuge tests were carried out to confirm anddetermine the effect of different pure alcohols, methyl t-butyl ether (MTBE) and mixtures of alcohols with gasoline and diesel on a thin disc of consolidated clay. The evolution of changes in the clay hydraulic conductivity with time was investigated and other structural changes due to chemical attack were monitored. The findings presented here demonstrate that the hydraulic conductivity of the clay appear to be generally related to the polarity of the chemicals and the dielectric constant. The cracking effect of butanol and MTBE on consolidated clay at low flow rate and low stress level was observed. The addition of ethanol or MTBE to diesel increased the clay permeability and the migration of organic chemical. The addition of ethanol to gasoline also caused an increase in the clay hydraulic conductivity. The effect of the association of alcohols with gasoline or diesel on the clay hydraulic conductivity is discussed, with a view to improving current pollution remediation techniques.