Integration of clayey materials in the engineered covers and improvement of their performance evaluation techniques

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The extraction of mineral resources plays an important role in the Canadian economy. However, while removing these valuable commodities, large volumes of waste are often generated. These wastes have the potential to adversely impact the environment if not properly managed. Special attention is required when the wastes contain iron sulfide minerals. The oxidation of sulfides by atmospheric oxygen tends to lead to the acidification of meteoric waters; this phenomenon is known as acid mine drainage (AMD). In these situations, actions must be taken at the mine site to prevent environmental impacts caused by AMD. Different management options and rehabilitation strategies are available to inhibit AMD production. Despite the development of these techniques, there is still work that must be performed to improve their performance both technically and economically.****The proposed research program seeks to develop effective and economical reclamation strategies for tailings storage facilities. Two distinct projects will be investigated: 1) integration of clayey materials in engineered covers, and 2) improving methods used to evaluate engineered covers' performances.****In Project 1, clayey materials sampled near active mine sites will be characterized using different technics. Lab tests will be performed including evaluation of hydraulic permeability, freeze Thaw effect, pore-size distributionetc. Then, numerical modelling will be performed with the objectives to assess the ability of covers to block water and oxygen from reaching the underlying reactive tailings. Also, field instrumented experimental cells will be used to test different cover configurations using clayey materials. The results allow for an evaluation of cover performance and verification of whether or not a cover including a clay layer could be used in mine site reclamation.****In the project 2, equipments for volumetric water content measurement will be tested under different conditions using experimental column tests with the objective to evaluate the impact of sulfur contents, interstitial mineralization and temperature on the measurements' accuracies. Also, at field mine site, components of water cover budget will be evaluated using measured parameters: evapo-transpiration (using eddy covariance method), water storage, runoff, precipitation and infiltration. Finally, a detailed analysis of results will be performed to compare evapotranspiration parameter indirectly assessed using the various components of the water balance to that measured with the eddy covariance system.****The work will be performed by PHQ students. These students will be trained and will acquire skills in managing complex problems related to unsaturated water movement as well as cover design and performance evaluation. These HQP will be well equipped to design effective covers that meet industrial, governmental, and community requirements.******