To increase the withdrawal of groundwater and place wells in the most efficient place, an esker area in Southern Sweden was investigated to get an estimation of the available aquifer volume. GPR was used to get a quick overview of the ground conditions and based on that information geotechnical drilling investigations were made to complete the investigation.
As it was estimated that the bedrock should be found rather deep, more than 10 meters, the GPR measurements were carried out with the MALÅ GX80 system, which in non-conductive conditions can reach 30-40 meters into the ground. The field measurement was done with the pulling kit for easy work in forested terrain, but the antenna was also pulled behind a car along small gravel roads. The measurements were done with a 5 cm trace interval and a time window of 740 ns. The investigation comprised approximately 7700 meters and were carried out during 2 field days.
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Result & Conclusion
The GPR investigation, could give a quick initial indication of the bedrock level in large parts of the investigated area. The results show rather undulating bedrock topography, reaching from 0 to 15 meters depth. The GPR results also pointed at a rather coarse-grained material on top of the bedrock and a few spots with clayey, silty material which should be avoided for groundwater withdrawal. The MALÅ GX80 system from Guideline Geo enabled a fast process, from data gathering to usable results, which gave a good foundation for further investigation planning.