South Africa stands once more at a fork in the road. on the one hand we see lurking the shadows of infrastructural decay - power supply, sewerage, water supply and other infrastructure failures are upon us, or imminent, and experienced engineers are leaving the country. on the other hand we strive for the vision of the rainbow nation - a united country that has turned its back on racial hatred and grasped prosperity for all its people in a never before seen peaceful regime change that captured the hearts and minds of the entire globe. But the dream has faded and acrimonious debate, blackouts and violence seem to be winning after all.
This year, the International Year of Planet Earth (IYPE), offers an ideal opportunity for civil engineering professionals to position themselves in terms of green engineering, and to go public with these principles.
South Africa proudly flies Blue Flags on many of its popular beaches. From Clifton 4th beach to Umhlanga Rocks beach in KwaZulu-Natal, sun seekers in their hundreds of thousands descend onto these beaches every year.
Before dealing with the engineering side of this issue, I believe it is important to first examine the science behind the decision taken by Blue Flag to withdraw status from certain of Durban's beaches. The quality of sea water is impacted primarily by storm events which have the effect of washing pollution from the land into the sea. For a short period after these storm events, the quality of sea water can be impacted negatively in areas immediately adjacent to river or storm water drain discharge points. The impact of this pollution is short-lived because of the ability of sea water to destroy pathogens within a few days.
With places of natural beauty in high demand for both residential and commercial reasons, and following an environmental impact study, IMESA (Institute of Municipal Engineers of Southern Africa), in conjunction with the municipality of Saldanha Bay, has established the Saldanha Bay Forum. This body was created to preserve Saldanha Bay, the Langebaan Lagoon and the immediate inland surrounds, and also to promote sustainable development for the bay and coastal areas.
Increasing pressure is being placed on mining companies to improve their environmental performance. The abundance of abandoned mine sites and large tracts of unrehabilitated mine land on the Witwatersrand and the Natal and Mpumalanga coalfields testify to the fact that mining companies have in the past failed to apply sustainable closure principles, particularly regarding tailings deposits. To be successful in an increasingly competitive global market, it is vital that mining companies subscribe to the principles of sustainable development. The very finite nature of mining requires responsible planning and effective management to meet sustainable closure objectives. The prevailing legislation specific to the lifecycle of a mine tailings dam is summarised here.
South African mining and construction companies have become subject to international standards for the planning, design, construction, operation and closure of mine residue storage facilities. With the increasing consciousness worldwide of sustainability, environmental, health and safety issues, the international standards themselves are becoming far more onerous on the owner, designer and operator of these facilities than has previously been the case. In this article some of the aspects of where South African mining companies and their designers and operators have had to modify their previous approaches in order to comply with the standards commonly enforced in the USA, Canada, Australia and the European Union are discussed.
It is very important to consider the social impacts of mining activities on the surrounding socioeconomic environment, and to incorporate Social Impact Assessment (SIA) into the operational activities of a mine as a management tool. However, the practice of SIA by mining companies is often largely lacking, especially in the developing nations of the world. To avoid such socioeconomic marginalisation by mining companies, the government of South Africa requires mining companies to develop and implement Social and Labour Plans (SLPs), which focus on promoting the long-term development of their workforces, employee households, communities and regions.
The four fundamental environmental aspects that are important in the mining industry are aesthetics, air quality, water quality and soil quality. There are various designs and management options that could contribute to a greener and better-stabilised tailings residue dam and its surroundings after mine closure. In the case of gold tailings residue dams, slope geometry, acidification and other environmental factors must be considered and these aspects require further investigation.
The optimal tailings disposal solution for a mine is not always straightforward or necessarily what has been done before. After completion of a feasibility study based on past practice, a comparative study of alternative tailings disposal systems was done for a proposed medium-sized platinum mine considering uniquely developed spigot, cyclone and paste disposal options. The comparative study dictated the consideration of total tailings disposal costing over the proposed life of the mine, revealing the real costs. In this instance, make-up water costs were found to be the most significant, and consequently the paste option was favoured. The lesson learnt from the study is that the right choice is not obvious and that relatively detailed studies are needed.
Many companies have become aware of the need for early environmental input, often beginning in a meaningful way at the pre-feasibility stage and continuing throughout the construction process. This has been the experience of SRK Consulting who are becoming more and more involved in projects from the outset, at the request of the client, in assessing environmental risks and identifying fatal flaws as opposed to simply conducting Environmental Impact Assessments (EIAs) for the purposes of obtaining environmental authorization, often once the detailed design stage of the project has been completed. At times, this involvement then continues throughout the construction phase. Two specific examples of this involve the world's largest producer of cement, French-based Lafarge, and Petroline, a company planning the transportation of petroleum products from Matolo in Mozambique, to Kendal in Mpumalanga, with a view to connecting with an existing pipeline to Gauteng.
The city of Cape Town is developing the first integrated waste management facility in South Africa, comprising a refuse transfer station, a compaction hall, container handling operations, garden refuse chipping facilities, materials recovery facility, workshop, wash bay, diesel storage, domestic recycling centre and a public drop-off, security building, entrance building, weigh bridges, with provision for a future 'resource park' and accommodation for future 'alternative technologies'.
Dam construction engineering technology is harnessed to ameliorate the socio-economic conditions of a people, while their natural and cultural heritage is respected through the implementation of best practice environmental principles.
The Gautrain Tunnel Boring Machine (TBM) is a colossal moving factory that is boring a 3 km section of tunnel from Rosebank Station southwards, while at the same time lining the tunnel behind it with pre-cast concrete segments that are installed within the protection of the tail shield of the TBM.
The construction of the Berg River Dam entered its final phase with the successful release of 200 m3/s. On 12 June 2008, 1,4 Mm3 of water was released in the build-up to the 200 m3/s designed capacity of the 5,5 m diameter conduit conveying the water from the intake tower through the dam wall to the outlet works. This flow is equivalent to a natural 1:2 year flood event.