Mapping old landfill areas or industrial sites, becomes more and more important with a growing need of land for development. Resistivity and IP have proved to be an efficient combination to look at the extents of such sites in plan and also in depth.
The demand on land for development is increasing as populations and urbanization expand. This
sometimes means it is necessary to avoid, or even re-occupy, areas
previously used for both landfill and industrial sites. For older facilities, knowledge may be limited on both the extent and the content of the site. To map larger land areas with only traditional geotechnical techniques (for example coring and test-pitting) can be both expensive and result in only point-wise information on what is, most probably, an extremely heterogeneous medium.
Measurements from the MaLaGa-project provided several clear examples of being able to map the physical extent of landfill areas, both in plan and in depth.
The results also demonstrate that measurements undertaken for mapping landfills may also be used to:
More to read on the internal structure of landfills can be found here:
We would like to thank MaLaGa (malagageophysics.com) and Dr. Mats Svensson, Tyréns AB and Dr. Torleif Dahlin, Engineering Geology, Lund Universty for sharing this case.
Method: Resistivity and induced polarization
Solution: ABEM Terrameter LS
Measurement: Parallel profiles, measurement, and processing design in 3D, monitored remote. The electrode configuration was pole-dipole with 100 m to remote electrode. Measurements have also been made with gradient configurations.
Inversion & Visualization SW: Res2dInv and Res3dInv.
The MaLaGa-project (Mapping Landfill Gas) has been a collaborative research project between universities, public and private sector mainly between 2012 and 2015, but which is still ongoing. The main participating organizations in the project are the Department of Engineering Geology, Lund University, and Tyréns AB. The MaLaGa-project’s main aim was to develop techniques for monitoring and characterization of solid waste landfills, based on geophysical measurements.
Resistivity and IP investigations can be made in combination, at the same time, and the results often show a clear contrast between the fill material and the natural geological formations surrounding the landfill.
Resistivity and IP measurements can cover larger areas relatively easily and thus find the lateral extent as well as the thickness of older landfill or industrial sites.
Resistivity and IP measurements can be performed in both 2D and 3D depending upon the project requirements. In the MaLaGa-project both investigation techniques were used.
3D-model where the higher normalized IP-values show the extent of a former landfill area.