Geoenvironmental Characterization Of Mine Tailings Using Piezocone Technology And Surface Electromagnetic Geophysics

The electronic cone penetration test with pore pressure measurement, commonly referred to as the piezocone test or<br>CPTU, has been established by the worldwide geotechnical community as the premier stratigraphic logging tool for<br>most soil conditions. Besides stratigraphic information, the piezocone also provides accurate estimates of key<br>geotechnical parameters and yields extensive information on the physical groundwater regime. Groundwater<br>parameters assessed include accurate location of the phreatic surface, determination of in-situ gradients, and<br>estimates of hydraulic conductivity.<br>The addition of a resistivity module to the piezocone (RCP’I’U) brings a tool to the industry that provides<br>geoenvironmental characterization which is accurate, rapid, and economical. for most natural and man-made soil<br>deposits. However, in a consulting engineering environment, new techniques that allow for more expedient yet<br>accurate site characterization are constantly sought. One such new technique, the use of non-invasive and portable<br>electromagnetic instruments such as the GeonicsTM EM3 1 as screening tools to guide more thorough investigations<br>(RCPTU, soil sampling, monitoring wells) shows promise and is the focus of this study.<br>Two large sulphide tailings impoundments in Western Canada were sites for comparing the ability of the RCPTU<br>and EM3 1 to geoenvironmentally characterize the tailings. Given the layered geometry of mine tailings, a forward<br>modeling of the RCPTU conductivity, to yield a predicted EM31 value, is possible. A consistent correlation<br>between the predicted and obtained data would support and promote the use of the EM31 as a viable tool for use<br>where an invasive investigation is not possible, cost effective, or where conductive zones need to be targeted for<br>RCPTU investigation.