Abstract: An apparatus for the decontamination of a subsoil formations, whereas groundwater is produced over long periods of time to remove especially the highly volatile halogenated hydrocarbons, causing contaminants to be flushed out and contaminants separated from the groundwater at the surface. In order to also be able to remove contaminants having higher specific gravities and contaminants with a low solubility in water, it is proposed to vibrate the water saturated soil/rock zone by means of an acoustic transmitter. The acoustic transmitter consists of two plate-like elements as membranes between which there is a coil.