Stringent regulations published in 2015 have tightened the design standards for mining residue stockpiles and deposits, but there is still scope to apply a risk-based approach to meet legal and environmental requirements while potentially saving on capital expenditure.
According to SRK Consulting South Africa senior environmental economist and management consultant, Matthew Law, the regulations promulgated in July 2015 specified design standards for mining waste disposal facilities based on the character of waste.
“These regulations are applied to new infrastructure at existing mining operations, and could require that new tailings disposal facilities be developed according to more stringent design specifications – and of course with financial implications,” said Law.
A risk-based approach to the design of disposal facilities and their management can identify cost effective alternatives to waste containment with commensurate standards of environmental protection, and should therefore be considered.
“For decades, SRK has used risk-based methods to guide its technical studies and professional recommendations to clients,” he said. “There is no doubt that this approach can be applied to the design of the new facilities in ways that, firstly, will not result in unsustainable ecological impacts and, secondly, could reduce capital expenditure.”
Law highlighted that the new regulations had the potential to limit the financial or technical viability of certain operations by inadvertently precluding a range of appropriate design alternatives that could equally mitigate environmental impacts. He said, as an example, that the installation of liners in tailings facilities – often a relatively high-cost option – was not necessarily the only effective solution available to mitigate groundwater impacts.
He said the intention of the regulations – which highlighted the importance of protecting groundwater resources – needed to be respected and observed by all stakeholders, but that innovative design and management approaches could accomplish environmental protection without entailing excessive and unanticipated costs.
“During Environmental Impact Assessment (EIA) processes, SRK hydrogeologists investigate the potential groundwater impacts of design alternatives – including liner installation – for proposed new disposal facilities” said Law. “The outcome of these studies allows the EIA consultant and client to evaluate the impacts and risks of alternatives, against their financial cost, and if appropriate, to successfully motivate through the EIA process for exemption from full compliance with stringent design regulations, as provided for in terms of the Waste Act and associated regulations. The EIA process also provides an excellent mechanism to consider, and compare, the potential socio-economic and environmental impacts of the premature mine closure,” he said.
For a risk-based assessment to be effectively applied, practitioners from various key disciplines must work closely to integrate their findings and recommendations, he commented. The team need a firm understanding of the environmental regulations, detailed technical knowledge of groundwater conditions at site and the hydrogeological impact of design alternatives, and an engineering strategy and design that align to these issues. “The EIA process, when effectively managed, is an excellent mechanism to integrate these disciplines,” said Law.