Abstract
An enhanced pseudo-3D framework for seepage modelling through mine waste facilities has been developed, incorporating the dynamic evolution of hydraulic properties driven by consolidation. The methodology couples HYDRUS-1D column simulations with Python automation, enabling sequential lift stacking, time-varying boundary conditions, and dynamic updating of hydraulic properties as consolidation progresses. At each stacking stage, void ratio is recalculated from effective stress using a power-law relationship, and the soil-water characteristic curve (SWCC) and saturated hydraulic conductivity are updated via van Genuchten and Kozeny–Carman formulations, respectively.
The framework was applied to a theoretical heap leach facility, comparing scenarios with and without consolidation-driven property evolution. The effect of consolidation on predicted seepage was found to depend strongly on the applied irrigation rate. Under gravity-only drainage, representative of post-closure conditions, consolidation-driven changes produced observable differences in effective saturation and drainage between the static-property and evolving-property scenarios, with neglecting consolidation leading to a significant underestimation of saturation buildup as reduced porosity and permeability altered moisture retention. Under active irrigation at rates typical of heap leach operations, cumulative drainage volumes were similar across scenarios, since saturated hydraulic conductivity remained above the applied flux; nevertheless, the full-consolidation scenario developed full saturation (Se = 1) due to fluid accumulation within the heap. This change in saturation has direct implications for leaching efficiency, irrigation rate design, and structural stability.
The tool provides practitioners with an accessible, automated approach for seepage evaluation through time-dependent stacked mine waste structures, supporting liner design and closure assessments. It applies to heap leach pads and dry stack facilities as well as tailings storage facilities. The framework also supports time-varying atmospheric boundary conditions, incorporating precipitation and potential evapotranspiration inputs, enabling the assessment of climatic effects on seepage and moisture redistribution throughout the facility lifecycle, an important consideration for water balance studies and long-term closure planning.
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