Assessment of Two Automated Electrical Resistivity Data Acquisition Systems for Landfill Location Surveys: Two Case Studies

Two types of automatic DC resistivity data acquisition systems, the Aarhus PA-CEP system and the ABEM Lund Imaging System, are assessed in connection with surveys for characterization of future landfill sites. In the first case, the extent of a natural clay layer in connection to an enlargement area of the Filborna landfill was mapped, and in the second case the soil cover at a proposed new landfill at Fläskebo was examined. At Filborna both resistivity systems and seismic refraction were used, whereas at Fläskebo the Lund system was used together with a VLF survey. At both locations 5 km of resistivity profiling were achieved. The resistivity datasets were interpreted with a smoothest constrained inversion. At Filborna a layer of thick clay till was identified in the southwest part of the investigation area, and thin clay tills were found in other parts. It was clear from the PA-CEP resistivity models that the underlying sedimentary rock possesses an undulating surface, which has an important implication regarding the soil cover barrier properties. At Fläskebo the resistivity survey successfully delineated the bedrock surface and effectively mapped the soil cover. Both resistivity systems worked well acquiring data suitable for data inversion. The seismic refraction model and resistivity models corresponded reasonably well. The p_ulled a_rray c_ontinuous e_lectrical p_rofiling (PA-CEP) is fast, but has limitations on the traversability of the site conditions. When fourteen different electrode spacings are used the Lund Imaging System is four to five times slower than the PA-CEP system in an open terrain. However, using fourteen different electrode spacings the Lund system has a much higher vertical resolution. Furthermore, as experienced in Fläskebo, the Lund system works well in very rough terrain.