Six geosynthetic clay liner (GCL) samples were excavated from the cover of a landfill site in the Nord Department in France. The objective of this sampling was to analyse if an evolution of the chemical and hydraulic properties of the GCL had occurred after maximum 6 years. This question arised in relation with an important leachate production. The GCL used was a needle punched GCL containing granular sodium activated calcium bentonite, with a minimum mass per unit area equal to 3.5kg/m². Tests performed on the GCL samples consisted in permeability tests according to the French standard NF P 84-705, swell index tests, calcium carbonate content, cation exchange capacity and exchangeable cations determinations. Results obtained on the GCL show a poor hydraulic behaviour in relation with a low confining stress, cation exchange and the presence of cracks in the bentonite. Those results are consistent with previous results from the literature.