1887

Abstract

Nickel concentrations occasionally above the allowed norm have been measured in water samples in the vicinity of the Petitpas waste rock pile at the Tio mine, Québec, Canada. In order to understand the chemical and hydrodynamic mechanisms responsible for the nickel dissolution and release in the environment a large hydrogeological/geotechnical/geophysical study was undertaken on the very large rock pile (600 m x 300 m x 150 m). Geotechnical and physical properties were measured in the laboratory on samples of waste with various moisture content and salinity. Induced polarization allowed the determination of electrical resistivities and chargeabilities that were to be used to interpret time-domain IP tomography surveys carried out on the waste rock pile. IP survey data were inverted in 2-D. The resistivity models for all survey lines show common features. From surfae to 25-30 m depth, the subsurface is resistive and show lateral changes which suggests large grain size heterogeneities and low water content; below and up to 50 m, a quasi uniform layer with resistivities in the range 50-250 ohm.m suggests fine-grained material with increased saturation. Finally below a depth of 50 m, the subsurface becomes very resistive again, indicative of coarse low-moisture content material. The chargeability model shows no structural correlation with the resistivity model. In general, chargeabilities are very large (up to 100 mV/V) and show no layering. From the laboratory and the survey results, we interpret the resistivity to be sensitive to water content and salinity while chargeability is sensitive to the metal concentration. The geoelectrical model and the interpreted hydrogeotechnical model will be useful for modeling water flow and reactive transport through the waste rock pile.

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/content/papers/10.3997/2214-4609-pdb.175.SAGEEP047
2010-04-11
2024-03-29
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609-pdb.175.SAGEEP047
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