Stringent regulations have tightened the design standards for mining residue stockpiles and deposits, but there is still scope to apply a risk-based approach to meet requirements, while potentially saving on costs, says SRK Consulting senior environmental economist and management consultant Matthew Law.
He explains that the regulations, promulgated in July 2015 under the National Environmental Management: Waste Act, specify 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, with, of course, financial implications,” Law says.
He believes that 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,” Law states. “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.”
He highlights that the regulations could limit the financial or technical viability of certain operations by inadvertently precluding a range of appropriate design alternatives that could equally mitigate environmental impacts.
As an example, Law notes that the installation of liners in tailings facilities – often a relatively high-cost option – is not necessarily the only effective solution available to mitigate groundwater impacts.
Tried and Tested Route
The intention of the regulations – which highlight the importance of protecting groundwater resources – needs to be respected and observed by all stakeholders, but innovative design and management approaches can accomplish environmental protection without excessive and unanticipated costs, Law says.
“During environmental-impact assessment (EIA) processes, SRK hydrogeologists investigate the potential groundwater impacts of design alternatives – including liner installation – for proposed new disposal facilities,” Law explains.
He notes that the outcome of these studies enables the EIA consultant and client to evaluate the impacts and risks of alternatives against financial costs and, if appropriate, 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 socioeconomic and environmental impacts of the premature mine closure,” he says.
Law states that effective application of a risk-based assessment requires practitioners from various key disciplines to work closely together to integrate their findings and recommendations.
“The team needs a firm understanding of the environmental regulations, detailed technical knowledge of groundwater conditions on site and the hydrogeological impact of design alternatives, as well as an engineering strategy and design that align to these issues.”
When effectively managed, the EIA process is an excellent mechanism to integrate these disciplines, he concludes.