The authors of the paper describe the way in which the longitudinal working Gussmann was mined in level V and the longitudinal working Kosocice in level VI, which in both cases resulted in a water flux from behind the northern boundary of the salt deposit. Only after concrete dams were seated on both levels, the brine flux was stopped leaving a direct contact of the dams with the pressurized water around the mine. For the sake of controlling water beyond the dams, steel pipelines were conducted through both dams and equipped with gauges before the dams. Their use in a saline environment, the developing corrosion increased the possibility that the tightness of the pipelines would be damaged. For this reason a decision was made to protect the mine by making a tight reconstruction of the safety pillar in both levels along the longitudinal working for about 600 m from the dams eastwards. For this purpose the pipeline injection method was applied. As the volume of voids to be tightly filled equaled to about 3800 m3, the task had to be divided into stages. Because of considerable distances of the liquidated workings from the closest shaft, the sealing slurries were prepared in a special injection center on the surface from where they were transported to the destination with a pumping pipeline through the Kościuszko shaft. The most important aspect of liquidating the end parts of the longitudinal working was to properly select the sealing slurries in view of their best cooperation with the rock mass, and such parameters as tightness, durability and cost. At the end stage of works, both longitudinal workings were equipped with dams, which were sealed up with the hole injection method. The innovative technology was implemented in the Wieliczka Salt Mine to reconstruct the safety pillar in levels VI and V in the most westward workings, the mine was shortened by about 600 m, the length of the ventilation system was reduced, systematic observations and pressure read-outs in dams 3 and 4 were systematically eliminated in dams 3 and 4. In this way the costs were lowered and safety of the mine improved.