High Resolution Resistivity Mapping of Subsurface Controls on Acid Rock Drainage at an Active Mine Site

Abstract

Two dimensional and quasi‐ three dimensional high resolution resistivity (HRR) imaging of a refractory ore stockpile area at an active mine identified several distinct electrically conductive features. A residual potential mapping (RPM) survey delineated the possible flow pathway between two known acid rock drainage (ARD) seeps. Subsequent drilling shows a strong correlation between the resistivity imaging results and the pre‐development drainage patterns, the associated clay base fill, and the seeps. In addition, the drilling indicated no pooling of ARD and strongly suggested lateral movement of the ARD along the top of the clay fill layer. This initial interpretation confirms that the clay fill base prevented vertical permeation of the ARD into the bedrock and suggests that the ARD pooling to the east and up gradient of the investigation area is most likely due to a malfunctioning French drain.