Applications of Surface Geophysical Methods to Ground Water Pollution Investigations

Abstract

Several surface geophysical survey methods are presented and the principles of operation for each technique discussed. These methods include seismic refraction, resistivity, electromagnetic conductivity, ground penetrating radar and magnetometry. Applications of these geophysical methods to groundwater contamination investigations include; determining lateral and vertical variations in soil, rock and groundwater characteristics; mapping the extent of groundwater contaminants present within aquifers; and locating buried objects. The suitability and potential application of surface geophysical surveys to monitor the migration of field-applied pesticides, and pesticides from waste disposal sites within the unsaturated and saturated zones is also discussed. An example to illustrate the use of geophysical techniques at a hypothetical pesticide field-application site is outlined. The example details the application of seismic refraction and electromagnetic conductivity techniques to define erratic subsurface conditions at a site where groundwater contamination is suspected. The site is underlain by an unconsolidated deposit of varying thickness and composition which is underlain by cavernous limestone. A groundwater monitoring system is designed based upon interpretation of the geophysical data obtained. By utilizing surface geophysical methods, extensive site coverage can be completed cost effectively and groundwater monitoring systems designed efficiently, thereby increasing the quality and success of site groundwater investigations.