Process-based erosion modelling for shoreline rehabilitation design of a coal mine pit lake
|
Authors: McCullough, CD; van Rooijen, A; van Maren, DS Open access courtesy of:
|
DOI https://doi.org/10.36487/ACG_rep/1915_07_McCullough
Cite As:
McCullough, CD, van Rooijen, A & van Maren, DS 2019, 'Process-based erosion modelling for shoreline rehabilitation design of a coal mine pit lake', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 75-88, https://doi.org/10.36487/ACG_rep/1915_07_McCullough
Abstract:
Mine pit lakes are a common feature of open cut mine closures that extend below the local groundwater levels. Due to the relatively steep lake bottom profiles compared to natural lakes, shoreline stability remains a significant limitation for the long-term sustainability of many pit lakes, potentially impacting upon highwall geotechnical stability, revegetation success, water quality and proposed end uses including wildlife habitat, aesthetics and recreation. However, although a potential issue for long-term pit lake closure planning and management, there is currently very little information available on pit lakeshore erosion, including potential erosion rates and extent. The ENGIE Hazelwood Coal Mine project is located in the Latrobe Valley, Victoria. The site has ceased operations and is currently in closure work phase. With approximately 16 km of pit lake perimeter, the effect of the final pit lake shoreline design on wave-induced shoreline erosion was identified as a key area requiring further study. This innovative study used the process-based hydro-morphodynamic models Delft3D to predict final pit lake shoreline erosion at the Eastern Batter (EB) domain region of the pit void. Shoreline erosion modelling was undertaken for three erosion treatments over a total of 10 scenarios. 2. Effect of shore slope angle (design angle of 17° from horizontal, to a lower 12° and steeper 22°). 3. The effect of prevailing winds compared to episodic storm winds. Pit lake shoreline erosion modelling was found to be a useful design tool for to study pit lake shoreline developments. Further model findings were that relatively gentle (12°) slopes did not show substantially decreased erosion rates compared to design (17°) slopes. However, relatively steep (22°) slopes showed substantially greater erosion. Erosion rates were strongly influenced by sediment properties, which constituted the biggest uncertainty in the modelling. Lowest erosion rates were for cohesive grey clays, highest erosion rates for sands and erosion rates of mixed sediments were in-between. Eroded sands were also deposited nearby at slightly deeper water, thereby reducing shoreline slopes over longer timescales. However, eroded clays were dispersed throughout the lake, preventing an erosion/deposition equilibrium being reached. Short-term storm events simply mimicked erosion patterns of longer duration prevailing wind events. Consequently, slope and sediment characteristic choices to mitigate prevailing wind effects may be similar to those used for mitigating event-driven erosion.
Keywords: mine closure, pit lakes, waves, erosion, numerical modelling, Delft3D
References:
Bureau of Meteorology (BOM) 2018, Morwell (La Trobe Valley Airport) climate averages, viewed 24 August 2018,
Castendyk, D & Eary, T 2009, ‘The nature and global distribution of pit lakes’, in D Castendyk & T Eary (eds), Mine Pit Lakes: Characteristics, Predictive Modeling, and Sustainability, Society for Mining, Metallurgy, and Exploration, Colorado.
de Lange, WJ, Genthe, B, Hill, L & Oberholster, PJ 2018, ‘Towards a rapid assessment protocol for identifying pit lakes worthy of restoration’, Journal of Environmental Management, vol. 206, pp. 949–961.
Deltares 2014, Delft3D Hydro-Morphodynamics, User Manual – Simulation of Multi-dimensional Hydrodynamic Flows and Transport Phenomena, Including Sediments, Deltares, Delft, 710 p.
Doupé, RG & Lymbery, AJ 2005, ‘Environmental risks associated with beneficial end uses of mine lakes in southwestern Australia’, Mine Water and the Environment, vol. 24, pp. 134–138.
Gourlay, T 2011, Notes on shoreline erosion due to boat wakes and wind waves, CMST research report 2011-16, 10 p.
Hazelwood Mine Fire Inquiry 2016, Hazelwood Mine Fire Inquiry Report, Melbourne, 252 p.
Kalin, M & Geller, W 1998, ‘Limnological fundamentals of acid mining lakes’, in W Geller, H Klapper & W Salomons (eds), Acidic Mining Lakes, Springer, Berlin.
Lund, MA & McCullough, CD 2011, ‘Meeting environmental goals for pit lake restoration – factoring in the biology’, in CD McCullough (ed.), Mine Pit Lakes: Closure and Management, Australian Centre for Geomechanics, Perth, pp. 83–90.
McCullough, CD, Hunt, D & Evans, LH 2009, ‘Sustainable development of open pit mines: creating beneficial end uses for pit lakes’, in D Castendyk & T Eary (eds), Mine Pit Lakes: Characteristics, Predictive Modeling, and Sustainability, Society for Mining, Metallurgy, and Exploration, Colorado.
McCullough, CD & Lund, MA 2006, ‘Opportunities for sustainable mining pit lakes in Australia’, Mine Water and the Environment, vol. 25, pp. 220–226.
McCullough, CD, Lund, MA & Zhao, LYL 2010, Mine Voids Management Strategy (I): Pit Lake Resources of the Collie Basin, Department of Water Project Report MiWER/Centre for Ecosystem Management Report 2009-14, Edith Cowan University, Perth, 250 p.
McCullough, CD, Schultze, M & Vandenberg, J 2018, ‘Realising beneficial end uses for pit lakes’, in C Drebenstedt, F von Bismarck, AB Fourie & M Tibbett (eds), Proceedings of the 12th International Conference on Mine Closure, Technical University Bergakademie Freiberg, Freiberg, pp. 487–494.
McCullough, CD & van Etten, EJB 2011, ‘Ecological restoration of novel lake districts: new approaches for new landscapes’, Mine Water and the Environment, vol. 30, pp. 312–319.
McPhail, G & Rye, C 2008, ‘Comparison of the erosional performance of alternative slope geometries’, in AB Fourie (ed.), Rock Dumps 2008: Proceedings of the Fifth International Seminar on the Management of Rock Dumps, Stockpiles and Heap Leach Pads, Australian Centre for Geomechanics, Perth, pp. 277–288.
Read, J & Stacey, P 2009, Guidelines for Open Pit Slope Design, CRC Press, 510 p.
Ross, T & McCullough, CD 2011, ‘Working near pit lakes – health and safety considerations’, in CD McCullough (ed.), Mine Pit Lakes: Closure and Management, Australian Centre for Geomechanics, Perth, pp. 167–182.
Schultze, M, Castendyk, D, Wendt-Potthoff, K, Sanchez-Espana, J & Boehrer, B 2016, ‘On the relevance of meromixis in pit lakes – an update’, in C Drebenstedt & M Paul (eds), Proceedings of the IMWA Conference 2016, International Mine Water Association, Freiberg, pp. 199–200.
van Etten, EJB 2011, ‘The role and value of riparian vegetation for mine pit lakes’, in CD McCullough (ed.), Mine Pit Lakes: Closure and Management, Australian Centre for Geomechanics, Perth, pp. 91–106.
van Rijn, LC 2007a, ‘A unified view of sediment transport by currents and waves, part I: initiation of motion, bed roughness and bed load transport’, Journal of Hydraulic Engineering, ASCE, vol. 33, pp. 649–667.
van Rijn, LC 2007b, ‘A unified view of sediment transport by currents and waves, part II: suspended transport’, Journal of Hydraulic Engineering, vol. 33, pp. 668–689.
Vandenberg, J & McCullough, CD 2017, ‘Key issues in mine closure planning for pit lakes’, in N Nanthi Bolan, Y Ok & M Kirkham (eds), Spoil to Soil: Mine Site Rehabilitation and Revegetation, CRC Press, Australia.
© Copyright 2024, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
View copyright/legal information
Please direct any queries or error reports to repository-acg@uwa.edu.au
View copyright/legal information
Please direct any queries or error reports to repository-acg@uwa.edu.au