Closure Planning and Estimating Within the Southern Africa Division of a Global Gold Miner

Authors: Sutton, MW; Pretorius, H; Nel, JH; Julyan, F; Rex, HG

DOI https://doi.org/10.36487/ACG_repo/852_14

Cite As:
Sutton, MW, Pretorius, H, Nel, JH, Julyan, F & Rex, HG 2008, 'Closure Planning and Estimating Within the Southern Africa Division of a Global Gold Miner', in AB Fourie, M Tibbett, I Weiersbye & P Dye (eds), Mine Closure 2008: Proceedings of the Third International Seminar on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 145-159, https://doi.org/10.36487/ACG_repo/852_14

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Abstract:
South Africa’s principal minerals legislation, the Mineral and Petroleum Resources Development Act (No. 28 of 2002) and Regulations (R527 of GG26275 23 April 2004) require, inter alia, that environmental management programmes include a description of the environmental objectives and specific goals for mine closure and that mining land “is rehabilitated, as far as practicable, to its natural state, or to a predetermined and agreed standard or land use, which conforms to the concept of sustainable development”. Furthermore, these regulations stipulate that the quantum of financial provision required to achieve this is estimated and provided in a prescribed manner, not only for planned closure but also for premature closure, and for post-closure management of residual and latent environmental impacts. The authors describe how the closure estimate for AngloGold Ashanti’s South Africa mines was improved in 2007 through a review, the setting of appropriate objectives and a market-related reassessment of costs. The main findings of the review were that there existed a comprehensive database of quantities and demolition costs for buildings and infrastructure. However, there was an inadequacy in the objectives and specific goals for mine closure and future land use, a lack of provision for premature closure as well as methods and estimates for tailings storage facility (TSF) and waste rock dump rehabilitation which were out-of-date and did not address the prevention of seepage and groundwater pollution. To update the estimates for TSF and waste rock dump rehabilitation, comparisons were made between the Department of Minerals and Energy (DME) Master Rates and estimates from independent contractors of the costs of implementing ecological engineering approaches recommended by the University of the Witwatersrand, Johannesburg. There was an increase in the quantum (R 644 million; US$1 = R 7.50) to provide for the unlikely event of premature closure. Conversely, the amounts that needed to be accounted for in the company’s balance sheet and income statement were reduced (R 137 million) because of a greatly-extended life-of-mine (LOM) and favorable discount and inflation rates. Further research is required into future decanting of mine water, treating groundwater, identifying off-site impacts and offsetting costs through the conversion of mine waste to carbon sinks or other resources.

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