This new method makes it possible to decide whether the ground can cause problems such as settlement of buildings or leakage of hazardous gases from the soil.
- In addition, landfill sites can also be used for the recovery of metals, since many are rich in valuable metalliferous scrap, says Torleif Dahlin, Professor of Engineering Geology at Lund University who, together with the consultancy firm Tyréns and NSR, North-West Skåne Waste Handling Company, is engaged on this project.
- Using resistivity measurements, which are based on the principle that the conductivity of different metals varies, in combination with other methods, it is possible to trace landfill gases, says Virginie Leroux, researcher in engineering geology at Lund University. She is from France which, together with Sweden, is a leader in this field.
In order to enhance reliability in interpretation, they will also measure variations in moisture and temperature, and take gas samples.
In Sweden alone, there are around 200 active landfill sites and several thousand old ones, mostly containing rubbish such as food, wood and plant material. When such organic matter decomposes in anoxic environments, methane is formed – a greenhouse gas that is 21 times as active as carbon dioxide. But if methane is instead collected it can be used to produce electricity and heat. Another objective is to trace pollutants and in this way reduce the risk of the pollutants being removed along with the leachate.