The paper presents the results of model tests carried out in a semi-technical scale. Author have been trying to answer the question, how the embankment lifting water made of the ash-slag mixture would behave and what kind of the possible filtration damages would occur in particular parts of the structure. It was verified in the conducted tests whether the applied kind and method of building up the geo-synthetic polymer barrier /GBR-P/ and the draining elements would ensure the safe working conditions of the structure. There were determined in laboratory tests the changes of the filtration curve location in the body of the hydraulic embankment without sealing elements and with the GBR-P screen. The tests revealed, that the furnace waste such as the ash-slag, cannot be used in hydraulic engineering without proper procedures. It may be building in geosynthetic sealing elements and drainage preventing from suffusion and liquefaction.