Many seemingly innovative materials and chemicals have been developed and adopted in industries only to later have been found to produce unintended environmental and health consequences. Wherever health and environmental risks arise, they are closely followed by reputational damage, litigation, extensive clean-up costs and increased regulation
An emerging concern worldwide is a group of substances known as PFAS (per- and poly-fluoroalkyl substances), which were developed over 50 years ago and incorporated into a host of industrial processes and products such as firefighting foams and all manner of other non-stick, water-repellent or stain-resistant goods.
PFAS don’t readily break down, so they can persist in soils and water over long periods of time. As well, PFAS leach through soils and easily enter and travel through surface and groundwater, potentially contaminating drinking water or entering the food chain by being taken up by aquatic organisms. A source of PFAS contamination can, therefore, have long-term impacts over a wide area. While the health effects of low concentrations of PFAS on humans and animals are not certain, the substances are known to bioaccumulate, and are considered toxins.
To date, mines have not been a major focus for assessment of potential PFAS impacts. However, PFAS have long been used in mining, as part of both processing and firefighting activities. PFAS may be present due to the use of aqueous film-forming foams (AFFFs) for firefighting, but also through inclusion in surfactants, ore-floating processes and other performance chemicals such as hydraulic fluids and fuel additives. This means that PFAS contamination is a risk for the mining sector and should be assessed and managed appropriately.
Who and what is at risk?
Each situation is unique, but the risks of PFAS contamination typically depend on key factors related to the site conditions and the use and value of water resources, such as the extraction and use of groundwater, and the ecological value of surface water bodies.
On and around mine sites, the risks from PFAS include the exposure of mine workers who have used or maintained fire-fighting equipment or used contaminated surface or groundwater, for instance as process make-up water or for dust control. Drinking water is a major concern too: Do mine workers, site visitors or off-site residents use the surface or groundwater as drinking water or for washing? Has livestock been exposed via surface water, groundwater or irrigation? If so, people consuming that livestock may have been exposed. Similarly, with PFAS being so easily transported through water, they may have been taken up by aquatic organisms, as well as by the birds and other animals that consume them. Local communities such as traditional owners may, in turn, be exposed via their consumption.
Assessing your potential PFAS liabilities
Where multiple sites (or even multiple areas or activities on a single site) are affected, a risk-ranking approach will facilitate the prioritisation of further activity. To rank the risks, several activities are needed. First, before any testing begins, a review should be conducted including interviews with site personnel (historical and current), review of site activities, chemical manifests, chemical management and containment systems, and assessment of the frequency of use and locations of use of PFAS products. In combination with information on site (hydro)geological and geochemical conditions, a conceptual site model (CSM) can be developed, identifying sources of PFAS, potential receptors exposed to PFAS, and the pathways linking sources and receptors. This model informs targeted sampling of soil, groundwater, surface water, sediment and, potentially, aquatic organisms.
Once all information has been gathered, the risk assessment can identify areas considered to pose low and acceptable risks (where further investigation may not be needed) from areas where risks are uncertain or considered likely to be unacceptable (where further assessment is required).
Tackling the problem
For activities or areas where risks have been ranked as unacceptable, management measures and/or controls should be implemented. This could mean providing alternative sources of drinking water or water for stock. It could mean closing fisheries or aquatic harvesting areas or recommending limits on the quantity of aquatic organisms eaten from a particular location.
Another important management measure is to ensure that risks relating to health and the environment are communicated to stakeholders in a manner that is clear, timely, accurate and sensitively handled. Much of the information about PFAS is technical and complex. There is a risk that if information is released without adequate plain-language explanations and context, the meaning may be misunderstood and lead to unnecessary anxiety.
Where practicable and warranted, source areas may require remediation and management. (For example, several sites around Australia are currently remediating PFAS-contaminated water to provide clean water to communities.) In collaboration with industry and academia, we have been focusing on identifying innovative ways to destroy and treat PFAS.
Ultimately, there will be some sites and circumstances where remediation of PFAS contamination is not feasible, or where further detailed assessment is unlikely to add value. In these instances, practical solutions may include minimising/eliminating PFAS releases and implementing management measures to limit exposure on and off a site.
Although we are still learning about the complexities of PFAS risks, management and remediation, there is no need for any sector to be complacent on the issue. There are sensible measures that can be taken now to understand the impacts that an operation is having on the environment, to minimise future release of these compounds from a site, and to mitigate potential risks to workers, wildlife and the local community.
ABOUT THE AUTHOR
Keely Mundle is a Principal Environment Engineer, based in Perth, Australia. She has more than 17 years’ experience in environmental, contaminated site and hydrogeological projects. Keely is experienced in leading technically complex multidisciplinary teams for contaminated site assessment and remediation projects. Her specialty is in groundwater investigations and is skilled in site characterisation, contamination assessments including groundwater modelling and the management and remediation of contaminated sites.