a method and apparatus for cleaning layers of earth that contain noxious material via a cleaning medium that takes up the noxious material and is introduced into the layers of earth via a drilling tube . the cleaning medium is extracted by suction from the layers of earth and is subsequently processed . to achieve a precise cleaning on the spot in a continuous manner without the necessity for excavating the earth , the cleaning is effected within a chamber that surrounds the drilling tube . the chamber can be lowered into the ground either together with or separately from the drilling tube . after termination of the cleaning process , at least parts of chambers used therefor are removed from the ground and shifted to a region that has not yet been cleaned , resulting in an advancement of the cleaning process in a horizontal direction . a sludge mixture can also be pumped from the chamber into a cleaning unit , with the clean , recovered earth again being introduced into the chamber .