Mechanistic models supporting uncertainty quantification of water quality predictions in heterogeneous mining waste rocks: a review

Abstract

Polluted drainage from weathering of sulfide-rich waste rock deposits can cause long-term impairment to waterways and biodiversity near mining sites. Mechanistic models represent established tools to support the predictions of the quantity and quality of waste rock drainage, and their associated risks. Yet, model-based predictions in typical waste rock systems are ubiquitously uncertain because of the strongly heterogeneous nature of these waste deposits. Embedding heterogeneity within predictive modeling is complicated by the magnitude and level of knowledge of the waste rock heterogeneity, and the large number of scale-dependent parameters feeding the model equations. This review encompasses deterministic and stochastic modeling approaches that emphasize consolidated tools and emerging modeling solutions to deal with heterogeneity for the modeling of waste rocks. Physical (e.g., variability of texture, hydraulic and pneumatic properties), geochemical (e.g., variability of mineralogy and kinetic parameters), and thermal heterogeneities are evaluated. The review points out the importance of stochastic modeling as a fundamental approach to embed uncertainty in long-term model-based decisions. Regulators and decision makers must be convinced of the benefit of using stochastic modeling, which is still considered to belong mainly to the academic sphere.

Stochastic analysis of spatial variability in two-dimensional steady-state confined groundwater flow

“…Solute transport in aquifers is controlled by the spatial variability of flow velocity (e.g., Rubin et al 1994;Fiori et al 2003;Darvini 2013). Stochastic environmental risk assessment considers the effects of variability (uncertainty) in flow fields on contaminated groundwater (e.g., Maxwell and Kastenberg 1999;Guadagnini and Tartakovsky 2010;Pedretti et al 2019;Muniruzzaman and Pedretti, 2021). The characteristics of specific discharge variation, such as the covariance function of integrated discharge (Eq.…”

Hydrogeochemical Response of a Variably Saturated Sulfide‐Bearing Mine Waste‐Rock Pile to Precipitation: A Field‐Scale Study in the Discontinuous Permafrost Region of Northern Canada

“…To mitigate detrimental impacts of contaminated drainage to receiving water bodies and environmental receptors, site‐specific characterization, reclamation efforts and long‐term monitoring of waste‐rock piles require integrated approaches that consider waste‐rock heterogeneity, climate conditions, and interior (bio)geochemical and mineralogical reactions. Waste‐rock heterogeneity is attributed to the physical, chemical, lithological, and mineralogical characteristics of waste rock, variations in the topography of the waste‐rock pile and its foundation, and waste‐rock pile construction techniques (Amos et al., 2015; Anterrieu et al., 2010; Lahmira et al., 2017; Muniruzzaman and Pedretti, 2020; Raymond et al., 2021; Vriens, Plante, et al., 2020). Waste‐rock characteristics and site‐specific climate conditions, including extreme climatic events, have a strong influence on hydrological processes (Smith et al., 1995) and subsequently, on the design of reclamation efforts (Aubertin et al., 2016; Hotton et al., 2020) and supporting geotechnical infrastructure (Labonté‐Raymond et al., 2020) and on the long‐term performance of the remediation approaches (Zhan et al., 2014, 2019) at mine sites.…”

Impact of diffuse layer processes on contaminant forward and back diffusion in heterogeneous sandy-clayey domains

“…In fact, the impact of such Coulombic interactions was shown to be significant not only in diffusion-dominated systems or under laboratory conditions (e.g., Appelo and Wersin, 2007;Felmy and Weare, 1991;Giambalvo et al, 2002;Liu et al, 2011) but also under advectiondominated flow regimes and/or at field-scales (e.g., Appelo et al, 2008;Rolle et al, 2013;Muniruzzaman et al, 2014;Muniruzzaman and Rolle, 2015;2017). Furthermore, groundwater flow systems comprising both high-and low-permeability materials may also entail inhomogeneous J o u r n a l P r e -p r o o f distribution of chemical properties, which can further influence degradation, retardation, and chemical transformation of subsurface solute plumes (e.g., Marble et al, 2010;Rasa et al, 2011;Yang et al, 2016;Muskus and Falta, 2018;Lari et al, 2019;Muniruzzaman and Pedretti, 2020).…”