Airborne Geophysical Studies around Landfill Areas – Case Histories from Finland

Geological Survey of Finland (GTK) had completed an airborne low altitude geophysical mapping survey covering the whole Finland. In recent years airborne data have been used in environmental applications related to landfill, groundwater and soil contamination. In this paper we present aerogeophysical studies of landfill areas in Finland. The first examples are from closed landfills, Mantyvaara in north Finland and three landfills in Helsinki region. Mantyvaara landfill was the first case in Finland, where AEM data were used for mapping contaminated areas. The other examples are monitoring cases. The airborne measurements have been conducted four times over the Ammassuo and twice over the Metsa-Sairila landfills. Using GTK's three-in-one airborne system to locate possible leakages is a useful method. The AEM out-of-phase component is sensitive to detect small changes in conductivity. AEM modelling and inversion are useful tools for estimating detailed conductivity changes. Magnetic data can be used to interpret linear features of bedrock to detect possible path of leakages. Radiometric data can estimate soil thicknesses and the changes of moisture. The changes in the environment can be observed more reliably from natural condition if repeated measurements are carried out.