Development and use of an electrical resistivity cone for groundwater contamination studies

Abstract

The evaluation of groundwater quality has become increasingly important as more industrial waste and solid domestic refuse come into contact with groundwater. One method of detecting contaminated groundwater is by noting the electrical resistivity of the contaminated soil. This method has been applied at the University of British Columbia by the development and use of a new resistivity cone. The resistivity cone consists of four circumferential surface electrodes contained in a separate module behind a 15 cm2 piezocone. The cone has a capability of providing a continuous record of resistivity with depth.Initially, a laboratory testing program was carried out using a simplified probe design to ensure the feasibility of the project. On the basis of favourable laboratory results the module was constructed, calibrated in the laboratory, and then field tested. The paper describes the design and operation of the resistivity cone, theory and laboratory calibration, and test results from three sites in the lower mainland of British Columbia. The results of the testing program provided evidence of the reliability of the instrument and illustrated its application in determining changes in groundwater quality. Factors affecting results and applications of the resistivity cone in contaminant site investigations are discussed. Key words: electrical, resistivity, cone, groundwater, contamination, plumes, mapping, in-situ testing, soil.