as shown schematically in fig1 the lower region of a waste dumping ground body 1 is located over an impervious layer 2 of a mineral sealing material , such as clay . a water level 4 of trapped water is located in the body 1 spaced upwardly from the impervious layer 2 . the water level 4 acts with a certain dynamic pressure or head , note arrow 5 , on the surface of the impervious layer 2 . the water level 4 is present due to water formed in the body of the waste dumping ground or due to precipitation as indicated by the arrows 3 . precipitation 3 can be loaded by harmful substances indicated by the symbols &# 34 ; x &# 34 ; and &# 34 ; o &# 34 ;, causing additional harmful substances to be released from the waste dumping ground body 1 . below the impervious layer 2 is an adsorption layer 6 . adsorption layer 6 is made up of two layers , that is , an upper layer 6 &# 39 ; and a lower layer 6 &# 34 ;. below the adsorption layer 6 is the natural soil formation 7 containing a ground water table 8 , spaced below the adsorption layer . in fig1 seepage water indicated by the arrows 9 loaded with harmful substances , initially slowly penetrates into the impervious layer 2 and seeps through the layer as a result of the head indicated by arrow 5 acting on the impervious layer . the quantity and speed of penetration can be regulated by the controlled permeability of the impervious layer 2 . the seepage water then penetrates into the upper layer 6 &# 39 ; of the adsorption layer 6 where a portion &# 34 ; x &# 34 ; of the harmful substances is retained , and then flows downwardly into the lower layer 6 &# 34 ; of the adsorption layer 6 where additional and possibly different harmful substances &# 34 ; o &# 34 ; are retained . the seepage water indicated by the arrows 10 now contains only small harmless concentrations of the harmful substances and flows into the soil 7 below the adsorption layer 6 and adds to the ground water indicated by the water table 8 . the type , thickness and arrangement of the impervious layer 2 and the adsorption layer 6 , which may consist of multiple layers , are dependent on the types and quantity of the expected harmful substances . the number of layers of absorption layer 6 depends on the types of expected harmful substances if various absorption materials are used in the individual layers . the thickness of the layers is based on an estimation of the amount of harmful substances occurring for a given time . moreover , it must be taken into consideration that the absolute impermeability of the layers is considerably increased due to additions and inclusions occurring in the absorption processes . accordingly , the known undesirable increase in permeability due to internal erosion or chemical aging such as in foil material , can not take place in the present invention , on the contrary , an impervious layer formed according to the present invention will become increasingly watertight in the course of time . the composition of the adsorption layer 6 and the individual layers 6 &# 39 ; and 6 &# 34 ; forming the adsorption layer is determined based on the type of harmful substances developed . mineral sealing materials in particular clay , to which adsorbing materials are mixed , are used as the basic material . accordingly , the layer containing a mixture of clay , for instance bentonite and calcium hydroxide , can be used for adsorbing heavy metals . for adsorbing organic substances , a mixture of mineral material can be used in which determined microorganisms can be added by mixing for enabling the adsorption of organic material such as oils , pcb ( polychlorinated biphenyls ) and other materials . in fig2 another arrangement of layers embodying the present invention is shown in cross - section similar to that in fig1 . in this arrangement , the impervious layer 2 made up of mineral sealing material , such as clay , is positioned between two filter layers 13 constructed of filter matting and located beneath the adsorption layer 6 separated from the waste dumping ground body 1 by an intermediate layer 11 of noncohesive material , such as sand . in a manner similar to that described with regard to fig1 arrows 12 indicate the seepage water passing out of the waste dumping ground body 1 and containing high amounts of harmful substances which flows downwardly through the sand layer 11 directly into the adsorption layer 6 made up of the two layers 6 &# 39 ; and 6 &# 34 ; for retaining the harmful substances by adsorption . since , in this arrangement the actual impervious layer 2 has a permeability less than that of the adsorption layer 6 , a head of water indicated by the arrow 5 is located in the adsorption layer acting on the upper filter layer 13 . it is possible that the head 5 of water may extend above the adsorption layers 6 . as shown by the arrow 9 , seepage water within the impervious layer 2 , having passed through the adsorption layers 6 , is only slightly loaded with harmless concentrations which flow through the impervious layer 2 and , as indicated by the arrows 10 , passes through the lower filter layer 13 and enters into the ground water having a water table level 8 shown spaced downwardly from the impervious layer 2 . fig3 displays a section through a waste dumping ground with a covering formed of a succession of layers , in accordance with the present invention , enclosing the dumping ground . in the waste dumping ground in fig3 covering 21 consists first of an impervious layer 23 formed of a mineral sealing material such as clay , which completely encloses the body 22 of the waste dumping ground . in the region of the bottom 24 and the upwardly extending sloping sides 25 , a first adsorption layer 26 &# 39 ; and a second adsorption layer 26 &# 34 ; are located contiguously and along the outer surface of the impervious layer 23 . the adsorption layers 26 &# 39 ;, 26 &# 34 ; are deposited on the available prepared earth 27 in which the waste dumping ground body is located . absorption layers 26 &# 39 ;, 26 &# 34 ; are made and constructed in the manner described above with regard to fig1 . impervious layer 23 has parts 28 extending laterally outwardly over the upper end of the upwardly inclined adsorption layers 26 &# 39 ;, 26 &# 34 ; to provide a cover for them . another feature of the present invention is displayed in fig3 where a drainage layer 29 is located below the base portion 24 of the impervious layer 23 and is connected with a special adsorption unit 31 by a line 30 . adsorption unit 31 is shown only schematically , it is formed of impervious layers and adsorption layers in the same manner as described with regard to fig1 and 2 . adsorption unit 31 is located alongside and / or slightly below the waste dumping ground and may include a number of chambers , such as a chamber 31 &# 39 ; containing adsorbers for specific harmful substances , such as heavy metals , and another chamber 31 &# 34 ;, for providing a biological purification of the seepage water . external adsorption unit 31 can be active in the initial state if a greater amount of liquid containing harmful substances is expected from the waste dumping ground body 22 . further it can be active in case of a disturbance if , at a later point in time , precipitation is retained by the covering impervious layer 23 which is greater than possible runoff , or in the upwardly extending adsorption layers 26 &# 39 ;, 26 &# 34 ; located adjacent the covering 21 , added by means of adsorption . in a waste dumping ground formed in this manner , a plurality of adsorber units can be provided and additional units can be added later . with the aid of fig4 the manner of constructing a section 56 of a vertical impervious wall within a channel 42 filled with a thixotropic supporting liquid , such as a bentonite suspension , can be explained . a device including a telescoping pipe 43 is supported on a guide car 45 located at the ground surface 44 . a funnel - shaped housing 46 is located at the lower end of the pipe 43 . a filling hose 47 is connected to and extends upwardly from the telescoping pipe 43 and receives a dry sealing material from a portable pump 48 . telescoping pipe 43 with the housing 46 , which forms a laterally closed passageway can be raised and lowered by a hoisting cable 49 connected to a boom 50 of a crane 51 . crane 51 is also connected to the guide car 45 and the pump 48 via a pull rope 52 , whereby the telescoping pipe 43 with the housing can be moved not only in the vertical direction but can be moved in the horizontal direction by the crane 51 . after the telescoping pipe 43 with the housing 46 at its lower end is lowered into the base 53 of the channel 42 , the dry sealing material is introduced into the channel 42 through the filling hose 47 by means of the pump 48 . to assure that the inner surface of the telescoping pipe 43 and the housing 46 remain dry when lowered into the thixotropic fluid , the lower opening in the housing 46 can be closed , by means of a flap , a slide or the like , not shown . after opening the closure , the sealing material can flow out . as the sealing material is introduced , the housing 46 is raised and the telescoping pipe 43 is correspondingly shortened , while at the same time the portion of the supporting fluid corresponding to the volume of the inserted sealing material is displaced . compression of the dry sealing material does not seem to be necessary . at 1 . 8 to 2 . 0 , its density is significantly greater than that of the supporting fluid which is approximately 1 . 08 , whereby the dry powder is deposited in a compact manner . build - up of the mixture can be counteracted by installing a worm conveyor or the like . housing 46 has impervious blankets 55 on two opposite sides for guiding the previously constructed section 56 and to separate cleanly the upper region of the formed section 57 against the supporting fluid 41 . as long as the wall pressure in the last section produced is smaller than the hydrostatic pressure of the supporting fluid , the section remains stable as indicated by the pairs of arrows 58 in fig4 . these conditions are generally met if the angle of the internal friction of the dry mixture is greater than 15 °. if the angle of internal friction drops below 15 °, such as in the instance of a very high bentonite content , vertically extending sections are not stable and they must be produced with a certain inclination or slope to guarantee stability . in such an instance , the telescoping pipe 43 with its housing 46 is guided in an upwardly sloping manner . while specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles , it will be understood that the invention may be embodied otherwise without departing from such principles .