Preferential Groundwater Flow And Aquifers
Groundwater flow paths are important criteria in terms of the design of landfill sites, waste dumps, chemical factories and other sources of potential groundwater pollution. These structures need to be located in optimum areas in terms of minimizing potential groundwater contamination and it is therefore important to understand the various groundwater aquifers and groundwater flow patterns. Geophysical methods such as EM-34 and resistivity can effectively be used to map and characterize groundwater flow and to allow for the optimum positioning of groundwater exploration and monitoring boreholes. Geological structures such as dykes are important in terms of groundwater flow and can be mapped using a combination of magnetic, electromagnetic and resistivity surveys.
Landfill And Waste Dump Investigations
Geophysical methods are routine used to map the extent of old landfill sites and quarries which were used as landfill sites. The thickness of the waste material and the composition of the waste material can be mapped using resistivity and/or seismic refraction while the extent of the landfill site can be mapped using a technique such as gravity.
Inorganic contamination of groundwater lower the electrical resistivity of the groundwater and surrounding soils and can be mapped using electromagnetic and/or resistivity methods. The movement of pollution plumes from the source can be traced by a series of parallel traverses downstream of the source positions, and the optimum position for groundwater monitoring boreholes can be determined. The depth and possible lateral extent of contamination can also be sometimes extracted from the geophysical results.