VLF MAPPING AND RESISTIVITY IMAGING OF CONTAMINATED QUATERNARY FORMATIONS NEAR TO "PANEWNIKI" COAL WASTE DISPOSAL (SOUTHERN POLAND)

The purpose of this work was to detect groundwater pollution and to identify the conditions of soil and groundwater near the coal waste disposal "Panewniki" Halemba-Wirek Coal Mine using geoelectrical measurements. The first applied method was the VLF (Very Low Frequency) technique. This method, using military signals, allowed to perform the in-phase and the quadrature maps. Data were collected from four study areas located near the coal waste dump. Observed anomalies on both maps for each area showed places with different conductivity allowed to detect the contaminated and uncontaminated zones. The VLF survey indicated that the contamination occurs in the eastern part of study area and is characterized by positive values of both measured electrical fields (the in-phase and the quadrature components). After preliminary contaminated zones were recognized using VLF method, an electrical imaging method was applied. Two electrical imaging profiles were carried out near the waste dump. The measurements allowed to create the geoelectrical model of surrounding area and to investigate the leachate plume. The electrical imaging showed that the greatest pollution occur in the area immediately adjacent to the coal waste what is confirmed by VLF survey. Based on the geological and geophysical knowledge from archives and on present researches, the contaminated aquifer with electrical resistivity of 5 to 15 Omega m deposited at depths of 3 to 7 m was found.