Innovative mine closure schemes have resulted in the development of the Eden Project in the UK, the world’s largest greenhouse in a former china clay quarry, and a mushroom growing business in underground drainage tunnels of a former South African diamond mine.
Both generate income, and in the case of the Eden Project, more than offsets the economic loss following closure in the quarry. In the first five years of opening, the Eden Project has generated almost US$1500 million for a local economy that was previously severely depressed.
The costs of mine closure and the reclamation of mine sites can vary considerably due to factors such as location and environmental vulnerability, the age of the mine, mining method, labour costs and so on, and particular challenges arise when dealing with acidic wastes and mine-water, which can take many years to remediate.
In addition to the environmental aspects of mine closure, significant social consequences can arise, especially in mono-industry situations where the economy and both direct and indirect employment opportunities are wholly dependent upon the continuance of mining. Examples of severe social distress followed mine closure in the coal sectors of the former Soviet Union countries and China, and in the metalliferous sector in Bolivia, Peru and Zambia. The effects of job losses are often further exacerbated due to the loss of public services previously funded and maintained by the mining company, such as energy and water supply, health provision and education facilities.
Dealing with the social and economic consequences of closure can be more intractable than residual environmental problems. The former coalfield areas of the UK are a case in point where hundreds of coal mines were closed during the 1980’s and 1990’s, bringing to a virtual halt a sector that had once driven development in the birthplace of the industrial revolution. The effects of the closures are still felt in parts of the UK and have required significant and ongoing investment to resolve.
However, almost two-thirds of former coal mine sites are now back in beneficial re-use having been redeveloped for commercial, industrial or residential use. Many of the remainder are constrained by planning conditions as they are located in “greenbelt” areas where hard development is not permitted. Even here, beneficial re-use occurs in the form of use for agriculture or amenity purposes.
The study of historic mine closure practices is useful in identifying the lessons learned and how they can inform current mine closure planning.
These show that there are also opportunities to reduce closure costs and liabilities by turning liabilities into assets.
Old waste dumps often contain high levels of metals, coal or other materials due to past inefficient recovery systems. Modern processing, especially when combined with high commodity prices, can make such recovery economically viable and offset costs of rehabilitation.
Similarly, the recovery of methane from abandoned coal mines, particularly from longwall mines, can be used to produce energy, generate income, remove a hazard and reduce greenhouse gas emissions.
According to British Coal research, coal seams up to 150-200m above and 40-70m below the worked seam may emit gas into the working longwall.
Commercial extraction schemes are operating in the UK, Europe and the USA and offer opportunities for other major coal producing countries. The UK Coal Authority (successor to British Coal) cites six different companies exploiting methane from eighteen operating and closed mines generating 44MWe and with proposals to generate a further 33-83MWe.
The re-use of mine sites subsequent to closure will be driven by local/national needs and pressure. In the UK, the re-use of mine sites for housing, commercial development, leisure or open space and highly innovative schemes such as the Eden Project have been driven by the need to make beneficial re-use of a scarce resource, land. The re-use of mines in remote and sparsely populated parts of the world may be very different and driven by other needs.
Importantly, it is essential to incorporate closure into mine design and management, with regular updates during operations, in order to improve the accuracy of cost forecasting and lessen the impacts.
Stakeholder involvement throughout mine closure planning is also essential to ensure support for the plan and minimise social impacts after closure.
Finally, beneficial re-use of mine sites and/or facilities should be considered in order to provide benefits in the form of employment, income or provision of infrastructure, open space or leisure facilities to local communities or for ecological benefit.
© Sinclair Knight Merz
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Who does this affect?
Anyone involved in mine closure
What do I need to do?
Be aware of historical mine closure practices and how they can inform current mine closure planning, particularly in relation to decreasing costs and turning liabilities into assets.
Author: Larraine Wilde
Larraine is a Principal Environmental Scientist with SKM, based in Sheffield, UK. During her 20 year career in environmental management, Larraine has directed or managed major projects in central and eastern Europe, Africa, Asia, Scandinavia and South America for organisations such as the World Bank, the UN, commercial banks and private clients. At SKM, Larraine provides a high level of environmental leadership, management, assessment and training.
© Sinclair Knight Merz
Requests to re-publish achieve articles should be made here