Store and release cover water balance for the south waste rock dump at Century mine

Authors: Rohde, TK; Defferrard, PL; Lord, M

DOI https://doi.org/10.36487/ACG_rep/1608_0.6_Rohde

Cite As:
Rohde, TK, Defferrard, PL & Lord, M 2016, 'Store and release cover water balance for the south waste rock dump at Century mine', in AB Fourie & M Tibbett (eds), Mine Closure 2016: Proceedings of the 11th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 47-59, https://doi.org/10.36487/ACG_rep/1608_0.6_Rohde

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Abstract:
In 2010 a store and release cover (the cover) was constructed on the south waste rock dump (SWRD) at Century mine (the mine). The purpose of the cover is to reduce seepage (percolation) into the potentially acid forming (PAF) waste rock by maintaining a compacted reduced permeability layer (RPL) at near saturated conditions. This is achieved by overlaying the RPL with a 1.5 to 2 m thickness of dolomite rock and soil-mulch (the soil-mulch). The RPL is the trafficked surface of the SWRD. The soil-mulch has a hummocky final surface that captures rainfall so it does not runoff, allowing it in part to infiltrate, with excess water removed by evaporation and transpiration. The unsaturated behaviour of the cover is being monitored by instrumentation including volumetric water content sensors and a weather station capable of estimating potential evapotranspiration. The instrumentation allows for the calculation of storage of rainfall in the cover, seepage (or percolation) through the base of the cover and in situ soil water characteristic curves (SWCC). The paper presents the results of three years of monitoring. It shows that seepage is about 6% of the total rainfall over the monitoring period and that the majority of the infiltration is going into storage within the cover before being removed by evapotranspiration. The paper presents a preliminary water balance for the cover by calibrating a Vadose/w model (the model) using in situ SWCCs and calculating actual evapotranspiration.

Keywords: store and release cover, water balance, modelling, instrumentation

References:
Allen, R, Jensen, M, Wright, J & Burman, R 1989, ‘Operational estimates of reference evapotranspiration’, Agronomy Journal, vol. 81, pp. 650–662.
Ayres, B, Silveria, C, Ellice, C, Christenson, D & O’Kane, M 2003, ‘Development of a Cover System Design for Potentially Acid Forming Tailings at Peak Gold Mine’, in AB Fourie & M Tibbett (eds), Proceedings of the Sixth International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 957–963.
Campbell Scientific Inc 2000, On-Line Estimation of Grass Reference Evapotranspiration with the Campbell Scientific Automated Weather Station, viewed 12 October 2015, ftp://ftp.campbellsci.com/pub/outgoing/apnotes/evap.pdf
Cook, PG, Leaney, FW & Miles, M 2004, ‘Groundwater recharge in the north-east Mallee Region, South Australia’, CSIRO land and water Technical report no. 25/04.
Defferrard, PL, Rohde, TK & Lord, M 2015, ‘Instrumentation and early monitoring results of the South Waste Rock Dump at Century mine’, in AB Fourie, M Tibbett, L Sawatsky & D. van Zyl (eds), Proceedings of the Tenth International Conference on Mine Closure, InfoMine, pp. 917–928.
Durham, A 2002, Design and Optimization of Waste Rock Cover Systems For Arid Environments, in Department of Civil Engineering, Master of Science, University of Saskatchewan, Saskatoon.
GARD Guide 2009, Global Acid Rock Drainage Guide, viewed 12 October 2015, www.gardguide.com
Geoslope 2012, Vadose Zone Modelling with VADOSE/W, viewed 12 October 2015,
O’Kane, M & Walters, P 2003, ‘Dry Trial covers at Mt Whaleback - A Summary of Overburden Storage Area Cover System Performance’, in AB Fourie & M Tibbett (eds), Proceedings of the Sixth International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 147–153.
O’Kane, M, Porterfield, D & Weir, A 2000, ‘Cover System Performance in a Semi-Arid Climate on Horizontal and Sloped Waste Rock Surfaces’, in unknown (eds), Proceedings of Fifth International Conference on Acid Rock Drainage, pp. 1309–1317.
Rohde, TK 2012, Century Mine – As Built Cover Instrumentation, SKM consulting report for MMG Century Mine.
Rohde, TK & Williams, DJ 2009, ‘Early Hydrological Monitoring of Cadia’s Instrumented Trial Waste Rock Dump’, in Proceedings of Eighth International Conference on Acid Rock Drainage, Skellefteå, CD Publication.
Rohde, TK, Williams, DJ & Burton, J 2011, ‘Store and release cover performance at Cadia Hill gold mine, Australia’, in AB Fourie & M Tibbett (eds), Proceedings of the Sixth International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 333–343.
Russell, J & Greacen, E 1977, Soil Factors in Crop Production in a Semi-arid Environment, University of Queensland Press, St Lucia.
Scott, P & Defferrard, PL 2013, ‘Quantifying Reactive Waste Rock Distribution In a Constructed Rock Storage Facility for Effective Closure’, in L Kerr (ed.), Proceedings of the 2013 Workshop on Australian Mine Rehabilitation, Adelaide, JKTech Pty Ltd, pp. 9–13.
Williams, DJ 2008a, As-Built Report – South Dump Stage 1 Cover, Uniquest consulting report for MMG Century Mine.
Williams, DJ 2008b, Field and Laboratory Testing of Trafficed Shale, Uniquest consulting report for MMG Century Mine.
Williams, DJ, Stolberg, DJ & Currey, NA 2006, ‘Long-term performance of Kidston’s “store/release” cover system over potentially acid forming waste rock dumps’, in RI Barnhisel (ed.), Proceedings of Seventh International Conference on Acid Rock Drainage, American Society of Mining and Reclamation, pp. 2385–2396.
Williams, DJ, Wilson, G & Currey, N 1997, ‘A cover system for potentially acid forming waste rock dump in a dry climate’, in unknown (eds), Proceedings of the Fourth International Conference on Tailings and Mine Waste, pp. 231–235.
Wilson, G 2000, ‘Appropriate concepts and Criteria for the Design and Construction of Mine Waste Cover Systems’, in NK Grundon & LC Bell (eds), Proceedings of Fourth Australian Workshop on Acid Mine Drainage.




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