Dr. Sarah Richards is a preeminent leader in per-and poly-fluoroalkyl substances (PFAS) chemical contamination, helping Australian Department of Defence (Defence) clients find solutions to address their contamination problems. Sarah has been with Tetra Tech since 2002, and has been in the contaminated land consulting and research industry since 1994. She has led feasibility assessments, contaminant transport assessments, human health risk assessments, contaminated land, and groundwater assessments (including acid sulfate, gas, and emerging contaminants), and has provided expert advice for environmental audits and liability management projects.

Sarah frequently gives technical presentations for client groups at local and international conferences and for in-house training sessions. She is committed to innovation and research and currently is involved in developing remedial techniques as an industry partner on an Australian Research Council linkage project, which promotes public-private sector research partnerships. Sarah has appeared as an expert witness in Victorian Civil and Administrative Tribunal and Planning Panel Victoria hearings, and provided expert input in an arbitration case submitted to the Supreme Court. She has also held Victorian committee positions for the Australasian Land and Groundwater Association (ALGA) and Australian Contaminated Land Consultants Association, maintains professional networks across the industry, and is a current Director of ALGA.

Recently, Sarah’s focus has been on emerging contaminants. Sarah adds value to risk mitigation services by providing an understanding of contaminant migration mechanisms, regulatory frameworks, and risk assessment. Sarah’s work is sought after within Tetra Tech, and she provides high-quality leadership and advice on any project with which she is involved. She is very accountable and always delivers.

Sarah has recent experience leading large projects for the Defence and has played an active role in stakeholder engagement and as an advisor on environmental assessment projects. Sarah led the scoping and delivery of a detailed site investigation (in accordance with the National Environment Protection Measure 1999) for Defence in relation to legacy PFAS contamination associated with the historic use of AFFF products at Royal Australian Air Force Base Darwin.

Sarah holds a bachelor’s in Civil and Environmental Engineering from the University of Adelaide and a doctorate in Geoenvironmental Engineering from Monash University.

What are some of the challenges the Defence faces in managing legacy contamination on its bases?

The needs at a Defence site, and even the forces themselves, change over time. These changes can result in modifications to the types and locations of facilities at bases. Decisions are made at the time of need about which products and equipment best meet the capability needs given the environmental constraints or policies in force at a particular time. If a product or material is later classified as hazardous, then a process of investigating the extent and risk associated with the legacy contamination begins. Documentation regarding the volumes and usage of a product sometimes is no longer available, which complicates the process of assessing the contamination. In addition, over time, changes in the layout of a base occur, structures are demolished, and changes occur to standard procedures.

The appropriate assessment of legacy contamination requires reviewing historical information, cross-referencing that information with anecdotal information, and then verifying the accuracy of the information using a well-designed sampling regime. In performing these tasks, consultants must keep in mind that operational activities at Defence bases are continuing, and mission-critical exercises or estate redevelopment/refurbishment may be occurring in parallel with the environmental assessment activities.

How is Defence different from commercial clients?

Defence provides almost every service that a whole city would. In addition to Defence-related actions, other activities on base include making clothes, cooking food, operating hospitals, providing training, servicing complex machinery, distributing fuel, and maintaining a very large facility. To keep the machine running, Defence has sets of common standards, processes, and procedures that control everything from procurement and access to disposal. 

Defence clients have a lot of projects and objectives, all happening simultaneously. Sometimes, the projects are complementary or cascading, and other times they are competing for resources.

Defence clients rely on our sound technical advice to help them identify effective approaches to get the projects to completion. By proactively identifying risks to the project and developing assessment and mitigation strategies, we can become a valuable extension of the Defence delivery team and smooth the path to completion.

As many Defence projects continue for years, or even decades, and the team on the project will inevitably change along the way, organizational knowledge and knowledge of the history of a project is at risk of getting lost. Maintaining communication and confidence in a shared objective is critical.

Due to the scale of Defence operations and the close proximity to communities, public, and media, attention can escalate quickly and be sustained for a long period as multiple communities become engaged across a country or region. The same expectation of transparency and regional action is less often applied to commercial companies. To work with Defence on issues of contamination, consultants need to be sensitive to long-standing community relationships and work within the relevant Defence procedures. There simply isn’t the option to modify procedures at a local level that may be available in private companies. In many communities, Defence is a key part of the community, and there is a high expectation of transparency and care.

What are the challenges in managing PFAS?

For the most part, PFAS goes where the water goes, and as a persistent chemical—one that doesn’t degrade to component elements or harmless compounds—the product that was used and discharged 20 years ago is likely still present somewhere in the environment. This means that the PFAS contaminating a waterway today may have started its journey through soil leaching and groundwater flow decades ago, or it may be the result of a recent movement of contaminated soil to the waterway. Within a catchment, there may also be dozens of other sources of PFAS contamination from firefighting foams, manufacturing processes, landfills, or wastewater treatment plants.

To effectively manage such a persistent and widespread chemical, we need to know the distribution of contamination in the environment and understand how water moves through soil, groundwater, creeks, and drains. Developing environmental remediation targets is complex, as the extent of contamination after 20 years of migration and dispersion means zero tolerance is not a plausible option. However, data from a robust risk assessment can be used to identify priority exposure pathways and a good site model can be used to evaluate the relative contributions of different areas of contamination and provide some basis to establish proportionate actions.

What are the best approaches when trying to develop a management strategy?

Perhaps fittingly, I think the approaches for management of PFAS have strong parallels to self-defense actions.

  • Mitigate the attack. Following risk assessment, the key human exposure pathways can be identified and addressed. In most cases, globally, that has meant providing alternative water supplies where drinking water is contaminated. Immediate actions might also include stopping a primary source (e.g., changing the product use, repairing leaking tanks).
  • Improve your position. Depending on the site situation, geology, and climate, there may be many potential actions that could be taken to reduce leaching from soils and infrastructure, divert contaminated drain water away from rivers, or reduce groundwater migration. Each action will improve the isolated position but may not be effective enough to have measurable improvement in overall risk of exposure. Understanding the site model and which areas are contributing by what mechanism is the only way to direct efforts toward actions that have the best chance of success.
  • Maintain safety. The state of knowledge regarding PFAS is continually evolving in relation to the criteria and analyses chosen to address the contamination issue. The physical conditions on sites being investigated also change with severe weather patterns or modifications to drainage. Ongoing monitoring programs provide confidence that changes to risk profile will be identified.

I can envision a future where there is no need to deploy a terrestrial network, because it is already there.

What are some of the innovations being used to manage PFAS in the environment? 

There are so many areas in PFAS remediation that are being developed and refined. Proven techniques generally relate to immobilization or separation, and suppliers are able to provide more selective and efficient products each year. Destruction techniques, such as thermal destruction, plasma, sonolysis (the breakup of material by means of sound, typically ultrasound), and electrochemical oxidation are also evolving, although due to its commercial availability and treatment rates, high-temperature thermal destruction is dominant for now. Tetra Tech is supporting research into the development of several innovative approaches, including enhanced biodegradation for destruction and removal of PFAS from contaminated concrete to support recycling.

The biggest improvement that we can help our clients achieve right now is to recognize where PFAS is present in the environment and develop proportionate mitigation measures using the most appropriate range of technologies currently available to reduce the future risk and liability.

What do you think the outlook is in this field?

I think PFAS has reawakened the public interest and concern about contaminants in the environment. Due to the persistence and widespread use of PFAS, detectable concentrations can be found almost anywhere and professionals in the environmental science and engineering field are challenged every day with defining the difference between pollution that can be meaningfully addressed, and low-level contamination as a result of multiple diffuse sources.

I think in the next few years, as the body of information about ambient and regional concentrations is shared, we will get better as an industry at focusing our efforts on the areas where valuable reduction in impact can be achieved, and hopefully, we can engage with the public and help bring them along. Beyond issues relevant to Defence, I think we will see a similar increase in public awareness of domestic products that cause widespread environmental contamination, such as microplastics and flame retardants.