[en] In the framework of the European Community Management and storage of radioactive waste programme and its Pagis project (Performance assessment of geological isolation systems), a study of the groundwater flow system in the permeable strata overlaying the Gorleben salt-dome in the Federal Republic of Germany has been carried out. The main purpose of this study was to compare the results obtained previously with the finite difference Swift computer code and the results obtained with the finite element Metropol computer code, developed at RIVM. Such a direct comparison was hampered by the fact that no standard is available for the results obtained. As a follow-up, Metropol was used for simulations that included the variations in the liquid density due to variations in the salt concentration. Some conclusions could be drawn: the travelling times of a particle through a single high permeable block increases by approximately two orders of magnitude compared to the constant density calculations due to the effect of high concentration gradients. However, the complexity of the problem considered has not yet made it possible to formulate conclusions for the complete model in a general way