Understanding where water is occurring and its movement in mine rock waste dumps (MRWD’s) and below tailings storage facilities (TSF’s) is critical to the management of the waste rock dumps and tailings storage facilities during operation and closure.
Design and Methodology
A combination of frequency domain electromagnetic geophysics (FDEM-8B) developed in 2018 and statistical interpretation using a newly developed program, Vlex4D, has allowed the definition of flow paths through TSF’s and MRWD’s in Northern Queensland, Western Australia and Egypt.
Although ground electromagnetic geophysical systems are well known in the geophysical industry namely the EM34, the FDEM-8B system, is unique as eight frequencies are read at each station. This allows faster traverses and quicker data capture. Files can be generated for pseudo sections as well as frequency specific grid contour maps. Using the Vlex-4D software platform, three dimensional iso-surfaces are generated from the ground geophysical data and "wrap" the similar conductivities.
Data and results
The FDEM system used in conjunction with Vlex 4D has been effective in determining flow paths and acid metalliferous drainage areas (AMD) within the waste rock dumps and TSF’s. This was confirmed through drilling and monitoring of groundwater bores drilled on the MRWD’s and below TSF’s.
Applications define in which areas and what relative depths AMD generation is occurring within rock waste dumps, understanding flow paths below TSF’s into groundwater and allowing a more focussed approach to investigation of groundwater through drilling and sampling. This methodology has been shown to be repeatable and allows the targeting of AMD generating areas in waste rock dumps and leakage areas in TSF’s for priority rehabilitation.