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Limpitlaw D.,University of Witwatersrand | Briel A.,Knight Piesold Pty Ltd
Journal of the Southern African Institute of Mining and Metallurgy | Year: 2014

The origins of mine closure practice have influenced the way in which it is implemented by companies and regulators. Mine closure practices essentially started developing in the 1970s in countries with advanced economies and mature mining industries. In these settings, the emphasis was justifiably placed on restoration of the landscape and an attempt was made to return to the 'natural' pre-mining land cover. These practices continued to evolve and incorporated socio-economic and cultural aspects, especially after the Brundtland Report in 1987 and the subsequent Earth Summit in 1992. Today mining is increasingly occurring in remote parts of developing countries where there may be significant need for infrastructure such as roads, clinics, and schools. The costs of returning land to low (economic) value pre-mining use may be far greater than establishing a viable postmining land use that could potentially add value to the community and take pressure off sites for greenfield development elsewhere. Furthermore, natural resource limitations (such as topsoil availability) may limit the degree to which the historical land cover can be re-established. Establishing post-mining land uses may aid in mitigating the loss of employment that is inevitable when mines close. Stakeholder participation in establishing post-mining land cover and land use options is critical for long-term success. Similarly, third parties must be identified to support the development of the post-mining land use This paper draws on the experience of the authors in several developing countries and presents a case for maximizing re-use of mining infrastructure. The paper does not advocate the adoption of poor rehabilitation standards, nor or the wholesale destruction of land capability, but rather leaving key infrastructure in place for post-mining use that may support sustainable development. © The Southern African Institute of Mining and Metallurgy, 2014.

Granger J.E.,SAEON | Granger J.E.,Knight Piesold Pty Ltd | O'Connor T.G.,SAEON | O'Connor T.G.,University of Witwatersrand
African Journal of Range and Forage Science | Year: 2015

Mining for copper and cobalt generates extensive mounds of removed topsoil and subsoil, and tailings with toxic levels of copper and cobalt. The threat of soil erosion in a high rainfall regime can be countered with rapid establishment of a sod-forming grass, such as Cynodon dactylon, that covers and binds the soil. An experiment was initiated in early 2013 to investigate whether planting vegetative material (plugs) was more effective than sowing of seed, and whether soil amelioration (fertilisation) was necessary on a substrate-specific basis. The experiment was assessed at the end of May 2013. Aerial vegetative cover was correlated with above-ground dry mass. Planting of plugs in combination with fertilisation was overall the most effective. On tailings, seed without fertilisation was a complete failure and fertilisation was essential for growth of plugs. Fertilised plugs resulted in a high density of stolons but fertilised seeds did not, although the response was delayed on tailings. Once phyto-stabilisation has been achieved, C. dactylon might serve as a nursery bed for establishing locally adapted cuprophytes of conservation significance. © 2015 NISC (Pty) Ltd.

Steyn G.P.,Knight Piesold Pty Ltd. | Mouton D.J.,Knight Piesold Pty Ltd.
Geotechnical Special Publication | Year: 2012

The grout curtain is an essential feature of dam foundations. The GIN method has become very popular as the preferred method for the installation of the grout curtain. However, where variable geological conditions prevail, the GIN method is not the optimal method to install a grout curtain. Two case studies of variable geological conditions are presented where the conventional grouting method was the best method to install an effective grout curtain. In such geological conditions, grouting is more of an art driven by experienced grouting technicians combined with constant site observation and evaluation of the grouting results to adjust the grout pressures and grout mix proportions. © 2012 American Society of Civil Engineers.

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