In this EU-Life-funded project we demonstrate the feasibility of MNA as a remediation technique for oil-contaminated sites in southern Finland. The study site, Trollberget, is an abandoned dumpsite outside the City of Hanko. ERT was used to map the hydrogeological and geological properties of the study site. The ERT measurements revealed clearly conductive zones near and at the place of the oil dump site. Also automatic monitoring stations were installed for monitoring the ground water. The ground water was at the highest level in wintertime and at the lowest in late summer. Ground water EC was anomalous high in monitoring site. Still, the ground water EC showed clear decreasing trend during the monitoring time. On-line monitoring of soil and groundwater conductivity together with electrical resistivity soundings seem to be promising monitoring tools for addressing biological activity.