Summary

Monitoring of contaminants, from uranium mine waste management facilities, is primarily done by drilling test holes and installing piezometers to sample the subsurface soil and the groundwater. Protocols using geophysical methods of monitoring the migration of acidic leachate from uranium mine waste rock piles and tailings facilities need to be developed. Shallow surface geophysics that include methods such as Electromagnetic (conductivity) and DC Resistivity surveys are less expensive, can locate contaminant plumes both laterally and with depth, providing an areal "snapshot" of the site at any given time.

Cluff Lake Mine, a wholly owned project of Cogema Resources Inc. of Saskatoon was selected as the research demonstration site. To study the effects of acidic mine drainage a multi-year program is envisioned. The first phase, the subject of this report, involved the testing of various off-the-shelf electromagnetic and resistivity equipment over several site locations. Additional phases are required to monitor temporal changes by carrying out repeat surveys to verify the first phase results. Other methods such as ground penetrating radar may be used to supplement the conductivity and resistivity surveys.

Electromagnetic instrumentation from two manufacturers, Geonics Limited of Mississauga, Ontario and Apex Parametrics of Uxbridge, Ontario was selected to carry out conductivity surveys to detect and trace acidic leachate from the Cluff Lake sites. The equipment manufactured by Geonics and utilized for the surveys was the EM-31 and EM-34 terrain conductivity meters. The Apex Parametrics unit was the Max Min 1-8S. The Geopulse resistivity receiver, combined with a central switching unit and a multicore take-out cable, a system manufactured and marketed by Campus Geophysical Instruments Ltd., enabled the rapid measurement of resistivity profiling and sounding data under the control of a "lap-top" computer.

Electromagnetic surveys identified three conductive zones in the vicinity of the Claude waste rock pile. These anomalies appear to be confined to within 100-150 metres of the pile. A significant area of high conductivity was identified adjacent to the liquid tailings pond on the EV-TDAM-1 grid. Conductive zones were not detected on grids in the vicinity of the OP waste rock pile and the STS ponds site.

The imaged pseudosections of apparent resistivity not only correlate well with the apparent conductivity data at the same locations, but supply information about the anomalies in the third (depth) dimension. On Line 25W of EV-TDAM-1 site the resistivity survey indicates that the main anomaly A (45ON) has a depth extent > 6 metres. Computer assisted inversion and interpretation of sounding data was able to determine resistivities and thicknesses of layers in the subsurface that were meaningful with respect to the known logs from access monitoring wells.

Positive results, obtained from phase one of the multi-year program, justifies continuation with phase two of the systematic surface electromagnetic conductivity surveys over all test sites with some modifications. Detailed resistivity imaging/sounding, ground penetrating radar (GPR), and electromagnetic soundings should be carried out to compare their effectiveness to resolve the resistivities and thicknesses of the layered earth. In addition, modelling of the resistivity data obtained during phase one should be completed for entire lines instead of short individual spreads.

Last Modified: 2003-11-26		Important Notices

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