In characterizing the estuarine clay at Bothkennar, Scotland, the hydraulic conductivity (permeability) was studied. In situ the hydraulic conductivity was determined using pushed-in-place piezometers, self-boring permeameters and the BAT system; in the laboratory oedometer cells, triaxial cells and a radial flow cell were used to determine the vertical and horizontal hydraulic conductivities and their variation with vertical compression. The results show a size effect and an anisotropy ratio varying with the fabric of the soil, but typically between 1·5 and 2. They also indicate that the pushed-in-place piezometers and the BAT system underestimate the hydraulic conductivity. The most representative profile seems to be given by the self-boring permeameter. The variation with compression of the hydraulic conductivity can be characterized by Ck=0·5 e0. Pour caracteriser l'argile d'estuaire a Bothkennar, Ecosse, la conductivite hydraulique (permeabilite) a ete etudiee. In situ la conductivite hydraulique a e...