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Surface And Downhole Em Investigations At Potash Mine Sites In Saskatchewan, Canada: Case Histories
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 10th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, Mar 1997, cp-204-00011
Abstract
Waste products from the potash industry in Saskatchewan are stored in surface tailings<br>management areas (TMA) which commonly consist of a salt tailings pile and a brine pond,<br>surrounded by dykes. Because the fluid level within the TMA is higher than its surrounding, and<br>because of density effects, surface brine migration occurs in varying degrees.<br>The high electrical conductivity of the brine compared to normal groundwater make geo-electrical<br>methods well suited to measure and monitor both lateral and vertical brine migration originating<br>from TMA’s. Historically, shallow lateral brine migration was measured by monitor wells or soil extract<br>analyses, but in recent years surface EM measurements increasingly have been used for mapping,<br>and for monitoring of the rate of migration and impact of remedial measures.<br>Vertical brine migration occurs both within the TMA as well as outside the perimeter dykes, in<br>areas affected by shallow lateral brine migration. In the past, detailed data on vertical brine<br>migration could only be obtained by means of soil extract data. Downhole EM measurements<br>have shown that vertical brine migration occurs typically to depths of 5 to 10 m. The transition<br>zone from full brine concentration to background values commonly is in the order of 2 to 3 rn,<br>consistent with diffusion-controlled vertical brine migration.