Principal Environmental Scientist
Principal Environmental Scientist
Many per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment, highly mobile, persistent and bioaccumulative – and, as such, PFAS remain a universal and complex challenge.
In Australia, the guideline for the National Environmental Management Plan for PFAS (NEMP) has been updated and endorsed by the Commonwealth and some states for implementation. NEMP 2.0, compiled by representatives of state environment protection authorities and published in May 2020, is the second step towards greater environmental management of PFAS and integration of PFAS into existing regulatory frameworks and policies.
If you work with PFAS or have responsibility for environments that are known to be or could potentially be affected by PFAS, you need to follow endorsed guidelines for investigating, assessing, managing and remediating PFAS-contaminated land and water, and dealing with PFAS-containing waste materials.
Here, we discuss some of the updates and priorities in NEMP 2.0 and what they might mean for you.
Assessments and sampling design
In NEMP 2.0, there is a strong emphasis on prevention of contamination, such as strategies to limit PFAS from migrating into off-site areas, reduce PFAS source mass and appropriately maintain PFAS containing materials (e.g. products and wastes). Hence, NEMP 2.0 highlights and reiterates the central tenet of traditional contaminated land assessments: the importance of building a robust conceptual site model and the need to consider all pathways for PFAS contamination. Assessing sensitive pathways and receptors off site in the early stages of an investigation remains an important priority. NEMP 2.0 includes a collection of conceptual site models that you might be able to adapt to your site’s sources, pathways, and sensitive receptors.
Of course, it is challenging to understand environmental fate and transport when we’re dealing with something as highly mobile, highly bioaccumulative and highly persistent in the environment as some PFAS. Adding to the complexity is the precautionary approach and the evolving scientific understanding of PFAS impacts on human health and the environment. In this context, sampling may need to extend beyond routine soil, groundwater, sediment, and surface water to also include biota (e.g., livestock serum and seafood tissues) to better assess the potential risk based on site-specific data.
You might need to consider novel or innovative sampling programs that specifically address the challenges faced. To better target your sampling, carefully consider what the question is that you are hoping to answer by collecting PFAS samples. What remediation, mitigation or management decisions will your sampling data inform? NEMP 2.0 includes an updated decision tree to assist with your sampling design.
NEMP 2.0 also adds ‘passive sampling’ as an additional tool for assessments and includes ‘mass load and flux’ as key risk considerations. These complex surface water and groundwater assessments require careful consideration and use of validated sampling techniques and methods to provide useful information. When done well, they inform how to best target and prioritise strategies for mitigating PFAS exposure for your site.
NEMP 2.0 includes a minor update to the soil guideline for residential locations. However, this soil guideline is not applicable where people are growing and consuming large amounts of home-grown produce such as eggs, meat (e.g. lamb or beef), vegetables or milk. In such situations, the environment protection regulatory authorities will require a site-specific risk assessment if the residential or rural land has been affected by PFAS contamination.
For ecological assessments, the soil guidelines remain unchanged and they are still interim. However, all sites and locations, whether residential or industrial, must now be assessed against the same guideline – wildlife is not selective about where it forages for food. However, for industrial sites, where there is likely to be less wildlife, a new process for soil assessment is available. There is now a requirement to satisfy site-specific characteristics for the higher ecological guideline to be applicable. For example, intensive development for more than 80% coverage of hard surfaces.
NEMP 2.0 now includes clear instruction to apply the biota guideline values to perfluorooctane sulfonate (PFOS) plus perfluorohexane sulfonate (PFHxS), not just PFOS. This has been adapted to allow for uncertainties and “potentially similar toxicities” of PFHxS with PFOS within mammals and birds. When considering the ecological health of birds, the NEMP 2.0 guideline for PFAS in (wild) bird eggs suggests birds may be more sensitive to PFAS and the guideline has been lowered by 10 times. This may be particularly important for consideration of migratory bird species which frequent coastal wetlands.
Beneficial soil reuse and on-site materials handling
All soil reuse principles are based on the desire to protect human health and the environment. NEMP 2.0 has not formulated a single national criterion for beneficial soil reuse; however, it recommends using multiple lines of evidence to support decisions to reuse soil where the intention is for the material to remain in place over the long term. For beneficial reuse, a detailed understanding of the PFAS contamination risk is required. NEMP 2.0 sets out several different methods for considering reusing soil on or off site and the soil reuse flowchart has been further developed to present options for navigating the process.
To assist your project planning and decision-making, NEMP 2.0 now provides more guidance about materials handling on site, including a risk-based matrix on duration of storage and detailed design requirements for containment. There is also a useful checklist (Appendix E) for storage of unused chemicals containing PFAS. As advised by the checklist, chemical storage controls should be validated by specialists to ensure that your methods are compliant with NEMP 2.0. This will lower the potential risk of environmental harm from leaks or spills.
Recognising that more research is still needed to better understand the fate and transport of PFAS in the environment, especially considering discharges from wastewater treatment systems, NEMP 2.0 recommends that the precautionary approach to handle wastewater is maintained to minimise risk.
Water managers (i.e., potable water and wastewater utilities, and landfill operators) are provided with further context and advice on wastewater management in NEMP 2.0; however, it does not provide discharge criteria. A priority for a future NEMP update will be to establish PFAS management criteria and advice through further collaboration with the water industry. In the interim, water utility managers are to develop their own risk based PFAS Management Framework.
NEMP 2.0 provides a PFAS Management Framework template that considers the specific needs and circumstances of wastewater utilities (e.g., treatment capability and capacity), inputs (e.g., trade waste agreements with industry), discharge (e.g., environment protection licence conditions and facility consent conditions) and receiving environments (e.g., community acceptance, ecological values). NEMP 2.0 reinforces that the key hazard control strategy is minimising PFAS sources entering wastewater.
There is an opportunity to transition through changes to PFAS management in a collaborative manner as leaders at water utilities and other industries review their trade waste agreements and all parties involved negotiate.
NEMP 2.0 recognises that PFAS are a highly complex matter with challenging technical aspects, and recommends that environmental duty stakeholders ‘seek expert advice’, particularly on matters such as PFAS precursors and transformation products, drafting a robust sampling and analysis quality plan, biota sampling, trade wastes containing PFAS, and risk mitigation strategies for managing a wastewater contamination event.
The challenge of PFAS contamination can be overcome, but it often requires specialists with experience in developing and applying risk-based cost-effective methods. Depending on your situation, you may need to draw on the expertise of specialists in fields including toxicology, health risk assessment, environmental remediation, hydraulic modelling, and civil and geotechnical design.
With NEMP 2.0 and the right advice, you can navigate a path through the complexities and uncertainties posed by this class of contaminants and reach a practical solution that not only satisfies current regulatory and compliance requirements and limits future liabilities, but also ensures a safer and healthier environment for future generations.
- Golder’s “Where can PFAS be found?”
- Updated sampling design decision tree (NEMP 2.0 – Section 12.1.2)
- Checklist for storage of unused chemicals containing PFAS (NEMP 2.0 – Appendix E)
- Risk-based matrix on duration of storage and detailed design requirements (NEMP 2.0 – Table 6. Section 10.1)
- PFAS Management Framework template for Water Utilities (NEMP 2.0 – Appendix D)