Authors: Perotti, DA; Gitirana Jr, GFN; Fredlund, MD

Open access courtesy of:


Cite As:
Perotti, DA, Gitirana Jr, GFN & Fredlund, MD 2019, 'Analysis of dry cover systems composed of tropical soils for mining waste', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 579-592,

Download citation as:   ris   bibtex   endnote   text   Zotero

The flow of water in mining tailings and waste rock may cause serious environmental impacts associated with acid rock drainage. Soil cover systems have been used to control or minimise such damages. In relatively dry climates, ‘store-and-release’ covers, also known as dry covers, have been considered as feasible alternatives. The objective of this paper is to evaluate the influence of atmospheric conditions and soil type in the performance of dry cover systems, considering conditions typical of tropical climates found in Brazil’s centralwest region. Numerical analyses using the finite element method were performed considering four different systems composed of tropical soils. Among the proposed arrangements, three use a soil that presents a bimodal soil–water characteristic curve and the fourth cover employs a unimodal soil. The thicknesses of intermediate materials were varied, and different representative precipitation parameters were considered for a period of one year. The results obtained were compared in terms of the internal flow and the capacity of the system to store water. The results indicate that bimodal soils may not be ideal cover materials and require specific compaction conditions that would reduce their macropores. Unimodal tropical soils presented adequate response as store-and-release materials. The use of an intermediate layer acting as a capillary barrier did not offer significant improvement to the cover systems evaluated.

Keywords: cover systems, dry covers, tropical soils, finite element method

Adu-Wusu, C & Yanful, EK 2006, ‘Performance of engineered test covers on acid-generating waste rock at Whistle mine, Ontario,’ Canadian Geotechnical Journal, vol. 43, no. 1, pp. 1–18.
Amorim, NR 2008, Evaluation of the Performance of Cover Systems in the Rio Paracatu Mining Mine (RPM), PhD thesis, Federal University of Viçosa, Viçosa.
Angelim, RR 2011, Pressiometric Test Performance in Compacted Embankments of Earth Dams in the Estimation of Geotechnical Parameters, PhD thesis, University of Brasília, Brasília.
Camargo, AP & Camargo, MBP 2000, ‘An analytic revision of the potential evapotranspiration’, Brangantia, vol. 50, no. 2, pp. 125–137.
Collischonn, W & Tassi, R 2008, Introduction to Hydrology, 5th edn, Federal University of Rio Grande do Sul, Rio Grande do Sul.
Duarte, LB 2012, Numerical evaluation of the design of cover systems for the closure of reservoirs for disposal of mining waste, Masters thesis, University of Minas Gerais, Belo Horizonte.
Fredlund, DG 2002, ‘Use of soil–water characteristic curves in the implementation of unsaturated soil mechanics’, in JFT Jucà, TMP de Campos & FAM Marinho (eds), Proceedings of the Third International Conference on Unsaturated Soils, vol. 3, A.A. Balkema, Rotterdam.
Fredlund, DG & Rahardjo, H 1993, Soil Mechanics for Unsaturated Soils, John Wiley & Sons, New York.
Fredlund, DG & Gitirana Jr, GFN 2005, ‘Unsaturated soil mechanics as a series of partial differential equations’, Proceedings of the International Conference on Problematic Soils, Eastern Mediterranean University, Famagusta, pp. 3–30.
Fredlund, DG, Xing, A & Huang, S 1994, ‘Predicting the permeability function for unsaturated soils using the soil–water characteristic curve’, Canadian Geotechnical Journal, vol. 31, pp. 533–546.
Gitirana Jr, GFN, Carvalho, ETL, Nascimento, BB & Cordão Neto, MP 2012, ‘Modeling the flow of water and air in unsaturated soils’ in JC Carvalho, GFN Gitirana Jr & ETL Carvalho (eds), Topics on Infiltration: Theory and Practice Applied to Tropical Soils, Technology College, Brasília.
Gitirana Jr, GFN & Fredlund, DG 2004, ‘Soil-water characteristic curve equation with independent properties’, Journal of Geotechnical and Geoenvironmental Engineering, vol. 130, no. 2, pp. 209–212,
Gitirana Jr, GFN, Fredlund, DG & Lima, MCG 2006, ‘Fluxo em solos não saturados e o processo erosivo’, in JC Carvalho, MM Sales, NM Souza & MTS Melo (eds), Erosive Processes in the Brazilian Midwest, FINATEC, Brasília.
Interstate Technology & Regulatory Council (ITRC) 2003, Technical and Regulatory Guidance for Design, Installation, and Monitoring of Alternative Final Landfill Covers, ALT-2, Washington, D.C., Interstate Technology & Regulatory Council, Alternative Landfill Technologies Team.
Kühn, VO 2014, Shear Resistance of a Tropical Unsaturated Soil Considering High Suctions, master thesis, Federal University of Goiás, Goiânia.
Leão Carvalho, ET 2013, Geotechnical Evaluation of Stormwater Infiltration Wells, PhD thesis, University of Brasília, Brasília.
Matos, THC 2011, Hydro-Mechanical Characterization of Fosfogesso and Soil-Phosfogesso Mixtures, Masters thesis, University of Brasília, Brasília.
MEND 2004, Design, Construction and Performance Monitoring of Cover Systems for Waste Rock and Tailings, Ottawa.
O’Kane, MA, Ayres, B, Christensen, D & Meiers, G 2002, CETEM Manual on Cover System Design for Reactive Mine Waste, O’Kane Consultants Inc., Saskatoon.
PDE Solutions Inc. 2008, FlexPDE, version 5.0, computer software, Antioch.
Silva Júnior, AC 2015, Probabilistic Rhythmic Approach Applied in Flow Analysis and Stability of Slopes, PhD thesis, University of Brasília, Brasília.
Silva, PAD 2011, Study of the Capillary Barrier Phenomenon: Numerical Modeling and Physical Experimentation, PhD thesis, University of Minas Gerais, Belo Horizonte.
Wilson, GW 1990, Soil Evaporative Fluxes for Geotechnical Engineering Problems, PhD thesis, University of Saskatchewan, Saskatoon, 464 p.

© Copyright 2021, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to