The main aim of this work was to assess different suitable strategies for the remediation of groundwater contaminated with the leachate from an old, not functional landfill located next to Hořkovec open cast mine, in the Czech Republic. The leachate consisted of mainly chlorinated aliphatic compounds and aromatic volatile compounds. The site, that had already been treated, was observed to show rebounding effects after the first remediation treatment. This article analyses the possibilities of using different types of remediation technologies that include in-situ chemical oxidation (ISCO) with different oxidants (potassium permanganate, sodium permanganate and sodium persulfate), as well as in-situ bioremediation (ISB), and the combination of both types of treatment. From the results of the analysis it was concluded that the best option for this case was to carry out a pre-treatment of the area by ISCO with sodium persulfate as the oxidant agent and then a further biological treatment.