Abstract: A method of geologically confining toxic industrial waste, the method consisting of: using a cavity (1) previously leached from a mass of rock salt (2), the cavity being initially filled with brine (5); incorporating the waste in a pumpable waste-containing mixture (10) of density greater than the density of the brine and suitable for setting once put into place; inserting a predetermined quantity of a buffer liquid (7) into the bottom of the cavity by means of a dip tube (8) positioned in a well (4) and in communication with the surface (3), the buffer liquid being immiscible both with the brine and with the waste-containing mixture, the density of the buffer liquid lying between the density of the brine and the density of the waste-containing mixture, and the buffer liquid including one or more halogen-containing solvents; inserting the waste-containing mixture into the cavity by the means of the dip tube while the bottom end of the dip tube is maintained within the previously inserted buffer liquid; and re