Groundwater impact of open cut coal mine and an assessment methodology: A case study in NSW
01 Sep 2017-International journal of mining science and technology (Elsevier)-Vol. 27, Iss: 5, pp 861-866
TL;DR: In this article, a methodology of groundwater impact assessment for an open cut mine in NSW with a three-dimensional groundwater flow model Modflow Surfact demonstrated its functions in simulating the project's impacts on the groundwater regime.
Abstract: Large scale open cut coal mining operations have significant impacts to groundwater in surrounding areas in both active and post-mining phases. The prediction of water inflows into a surface mine excavation is one of the many components involved in mine design phase. Groundwater performance also reacts to mining activities from the operational, economic and safety implications perspective. Under NSW planning legislation, as part of the comprehensive risk assessment, a groundwater impact assessment has to be conducted for a coal project to predict and mitigate the impacts in consideration of the government requirements. In this paper, the groundwater assessment modelling of mine pits was discussed in predicting of groundwater inflows and reviewing analytical and numerical approaches. A methodology of groundwater impact assessment for an open cut mine in NSW with a three-dimensional groundwater flow model Modflow Surfact demonstrated its functions in simulating the project’s impacts on the groundwater regime. The key findings with mitigations are discussed and recommended in the paper to reduce impacts on groundwater and fulfil regulation requirements in NSW.
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TL;DR: Groundwater chemistry of mining region of East Singhbhum district having complex contaminant sources were investigated based on heavy metals loads and other hydrochemical constituents and showed that Na+, K+, and Ca2+ ions are the dominant cations in the groundwater, while HCO3-, F- and Cl- ions dominate the anionic part of the groundwater.
120 citations
TL;DR: In this paper, the authors provide an overview of recent studies using remote sensing (RS) and geographical information systems (GIS) to assess mining impacts on water, land, and society.
70 citations
TL;DR: In this article, the authors used hierarchical cluster analysis (HCA) and principal component analysis (PCA) to classify and identify water sources responsible for possible groundwater mixing within rock layers, and applied Geochemist's Workbench to estimate the mixing fractions to clarify sensitive zones that may affect rock slope stability.
Abstract: Water-rock interaction and groundwater mixing are important phenomena in understanding hydrogeological systems and the stability of rock slopes especially those consisting largely of moderately water-soluble minerals like calcite. In this study, the hydrogeological and geochemical evolutions of groundwater in a limestone quarry composed of three strata: limestone layer (covering), interbedded layer under the covering layer, and slaty greenstone layer (basement) were investigated. Water-rock interaction in the open-pit limestone quarry was evaluated using PHREEQC, while hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to classify and identify water sources responsible for possible groundwater mixing within rock layers. In addition, Geochemist’s Workbench was applied to estimate the mixing fractions to clarify sensitive zones that may affect rock slope stability. The results showed that the changes in Ca2+ and HCO3− concentrations of several groundwater samples along the interbedded layer could be attributed to mixing groundwater from the limestone layer and that from slaty greenstone layer. Based on the HCA and PCA results, groundwaters were classified into several types depending on their origin: (1) groundwater from the limestone layer (LO), (2) mixed groundwater flowing along the interbedded layer (e.g., groundwater samples L-7, L-11, S-3 and S-4), and (3) groundwater originating from the slaty greenstone layer (SO). The mixing fractions of 41% LO: 59% SO, 64% LO: 36% SO, 43% LO: 57% SO and 25% LO: 75% SO on the normal days corresponded to groundwaters L-7, L-11, S-3 and S-4, respectively, while the mixing fractions of groundwaters L-7 and L-11 (61% LO: 39% SO and 93% LO: 7% SO, respectively) on rainy days became the majority of groundwater originating from the limestone layer. These indicate that groundwater along the interbedded layer significantly affected the stability of rock slopes by enlarging multi-breaking zones in the layer through calcite dissolution and inducing high water pressure, tension cracks and potential sliding plane along this layer particularly during intense rainfall episodes.
40 citations
Cites background from "Groundwater impact of open cut coal..."
...Existence of groundwater in mine sites potentially causes slope stability problems [12]....
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TL;DR: Zhang et al. as discussed by the authors proposed a concept of phreatic water resource conservation coefficient (PWRCC) for underground coal mining in arid and semi-arid areas.
28 citations
References
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TL;DR: In this article, three different coupling schemes are identified, namely, uncoupled, iteratively coupled, and fully coupled, with the degenerated coupled scheme being a special case of the uncoupling scheme.
Abstract: Surface and subsurface flow systems are inherently unified systems that are often broken into sections for logical (e.g., time scales) and technical (e.g., analytical and computational solvability) reasons. While the basic physical laws are common to surface and subsurface systems, spatial and temporal dimensions as well as the continuum approach used for the subsurface lead to different formulations of the governing partial differential equations. While in most applications such decoupling of the systems works well and allows a very accurate and efficient description of the individual system by treating the adjacent system as a boundary condition, in the case of water flow over a porous medium, it does not. Therefore coupled models are in increasing use in this field, led mostly by watershed and surface irrigation modelers. The governing equations of each component of the coupled system and the coupling physics and mathematics are reviewed first. Three different coupling schemes are identified, namely the uncoupled (with the degenerated uncoupled scheme being a special case of the uncoupled), the iteratively coupled, and the fully coupled. Next, the different applications of the different coupling schemes, sorted by field of application, are reviewed. Finally, some research gaps are discussed, led by the need to include vertical momentum transfer and to expand the use of fully coupled models toward surface irrigation applications.
178 citations
"Groundwater impact of open cut coal..." refers methods in this paper
...There are lots of computational tools and applications available in the market with Modflow and HECRAS as the most widely used codes [6]....
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Book•
20 Apr 2006
TL;DR: In this paper, the authors present a survey of the problems associated with mining and related industries, including deformation, contamination, and mine effluents and acid mine drainage, as well as other related problems.
Abstract: 1. Introduction 2. Subsidence Due to the Partial Extraction of Stratiform Mineral Deposits 3. Longwall Mining and Subsidence 4. Metalliferous Mining and Subsidence 5. Subsidence Associated with the Abstraction of Fluids 6. Quarrying and Surface Mining 7. Waste Materials from Mining and Their Disposal 8. Mine Effluents and Acid Mine Drainage 9. Dereliction and Contamination Associated with Mining and Related Industries 10. Other Problems Associated with Mining
132 citations
TL;DR: A hydrogeological assessment of the Irankuh Zn-Pb mine at 20 km south of Esfahan and 1 km northeast of Abnil in west-Central Iran and a comparison between numerical modelling using a finite element software called SEEP/W and actual data related to inflow are made to extend the applicability of the numerical model.
Abstract: The groundwater inflow into a mine during its life and after ceasing operations is one of the most important concerns of the mining industry This paper presents a hydrogeological assessment of the Irankuh Zn-Pb mine at 20 km south of Esfahan and 1 km northeast of Abnil in west-Central Iran During mine excavation, the upper impervious bed of a confined aquifer was broken and water at high-pressure flowed into an open pit mine associated with the Kolahdarvazeh deposit The inflow rates were 67 and 14 m3/s at the maximum and minimum quantities, respectively Permeability, storage coefficient, thickness and initial head of the fully saturated confined aquifer were 35 × 10−4 m/s, 02, 30 m and 60 m, respectively The hydraulic heads as a function of time were monitored at four observation wells in the vicinity of the pit over 19 weeks and at an observation well near a test well over 21 h In addition, by measuring the rate of pumping out from the pit sump, at a constant head (usually equal to height of the pit floor), the real inflow rates to the pit were monitored The main innovations of this work were to make comparison between numerical modelling using a finite element software called SEEP/W and actual data related to inflow and extend the applicability of the numerical model This model was further used to estimate the hydraulic heads at the observation wells around the pit over 19 weeks during mining operations Data from a pump-out test and observation wells were used for model calibration and verification In order to evaluate the model efficiency, the modelling results of inflow quantity and hydraulic heads were compared to those from analytical solutions, as well as the field data The mean percent error in relation to field data for the inflow quantity was 0108 It varied between 116 and 146 for hydraulic head predictions, which are much lower values than the mean percent errors resulted from the analytical solutions (from 18 to 53 for inflow and from 216 to 35 for hydraulic head predictions) The analytical solutions underestimated the inflow compared to the numerical model for the time period of 2–19 weeks The results presented in this paper can be used for developing an effective dewatering program
22 citations
"Groundwater impact of open cut coal..." refers background in this paper
...These impacts can be considered as either hydrophysical loss of aquifer pressures and consequential leakage from remote aquifers or hydrochemical mixing of ground waters, salinity from waste rock spoils [3]....
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01 Sep 1988
TL;DR: In this article, the hydrological cycle of a mining catchment together with the technique of estimating inflow from a surface source is described, together with a detailed description of the mining catchments.
Abstract: Estimation of water i nflow to a surface mining operation is a necessary requirement for mine drainage design. The water in a shallow surface mine may originate solely from a surface source and from the atmosphere in the form of precipitation. Water in deep mining excavations below the groundwater table may originate from a surface source or as atmospheric precipitation as well as from the groundwater system. Inflow of surface water to a mining excavation can be predicted by hydrological balance investigations of a mining catchment. The paper briefly describes the hydrological cycle of a mining catchment together w ith the technique of estimating inflow from a surface source.
9 citations
"Groundwater impact of open cut coal..." refers background or methods in this paper
...This approach assumes that dewatering of the surface mine is carried out by use of an imaginary pumping-out borehole (fully penetrating the entire saturated thickness of the aquifer) from which water is pumped out at a uniform discharge rate in order to lower the piezometric level of the aquifer to below the mining horizon at the mine boundary [2]....
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...Near the excavation, there is invariably, a vertical component of flow and high hydraulic gradient which often leads to turbulent flow and negates analysis by Darcy’s Law [2]....
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...where B is the leakage factor, m; Q the total flow rate from both excavation faces, m(3)/d; Y the length of the cut or high wall, m; T the transmissivity of aquifer, m(2)/d; Dw the drawdown at excavation face, m; L the thickness of aquifer being dewatered; and K the hydraulic conductivity of the geologic formation, m/d [2]....
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...Inflow of surface water to a mining excavation can be predicted by hydrological balance investigations of a mining catchment [2]....
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