PFAS in Groundwater Workshop: The Professional's Challenge: Alphabetical Content Listing
Panel: How States/Governments Are Addressing PFAS
Shalene Thomas
Session 1: Due Diligence/Legal and Regulatory
Assessing the Liabilities of PFAS at a Site, and Prioritising your Resources
Douglas Smith
Over the past few years, organisations, consultants, and regulators across Australia and internationally have been working in a similar environment of uncertainty and adapting our traditional approach for site investigations to this emerging contaminant of concern. How these approaches have been adapted vary greatly based on the regulatory status where the organization operates.
Critical to making informed decisions is the need to understand the potential magnitude of the issue including broader appreciation of not only where PFAS maybe present across a site or portfolio of sites, but also the individual site characteristics and potential risk exposure pathways through PFAS may be introduced to the environment.
From the perspective of a project and client manager who completes environmental site assessments, this presentation will discuss the importance of understanding where the risks of PFAS contamination are high, and how to prioritise resources to better understand these risks and potential liabilities. Supported by case studies, this presentation will review the need to understand the potential sources-pathway-receptor linkages for PFAS contamination in prioritising resources.
Expanding the Network: Considering More than just PFOA and PFOS & Adding Treatment to Existing Water Districts
Scott A. Grieco, Ph.D., PE
substances (PFAS) into Unregulated Contaminant Monitoring Rule 3 (UCMR3) and lowering of the Lifetime Health Advisory (LHA) values in 2016 have increased the focus on treating PFAS-impacted ground water. Moreover, some states are developing screening values or promulgated drinking water values that are lower or more inclusive than the EPA LFH for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Lastly, the recent press release in March by the EPA stating that LHA values are expected to be developed for perfluorobutane sulfonate (PFBS) and 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (GenX) this year demonstrates the evolving regulatory landscape of PFAS.
Currently, activated carbon adsorption is the primary technology being used for PFOA and PFOS
removal in Point of Entry Treatment (POET), municipal water supply, and groundwater pump-and-treat systems. This presentation will provide recent pilot and full-scale operating data from several ground water sources showing the system performance with respect to the wider PFAS concerns. This presentation will also discuss recent advances of emerging (anion exchange resin) and developing water treatment technologies (advanced adsorbents, reduction, and oxidation) that show promise as the need for wider PFAS treatment capabilities become reality.
Lastly, regardless of the technology selected, incorporating a new technology into an existing public
water supply requires both technical and logistical concerns. These will be discussed in case study form based on a recent ground water well system upgraded for PFAS treatment. Aspects include:
• Technology incorporation: hydraulics and space constraints
• Incorporating treatment with disinfection requirements
• Developing and communicating a plan for flushing the existing system for existing users
• Training for operators not familiar with advanced water treatment equipment.
Legal and Regulatory Framework Challenges in Consideration of Multiple Types of Uncertainties
Francois Lauzon, PE
facilitie that has resulted in the presence of per- and polyfluoroalkyl substances (PFAS) in a complex
fractured bedrock potable groundwater aquifer. Downgradient residential properties which rely on
groundwater as a potable water source (private wells) have initiated a class-action lawsuit.
As an emerging contaminant, the long-term effects of PFAS exposure to receptors is still being studied, which leads to challenges in communicating information to affected residents and other stakeholders that include local politicians, Public Health officials, environmental departmental representatives, the media, and ultimately, lawyers involved in the Class Action suit. How are evolving regulatory levels and complex uncertainties affecting decisions and trust?
The presentation will examine the three main types of uncertainties (1. Natural variability; 2. Model and Parameter uncertainty; and 3. Deep Uncertainty) and sources of uncertainty to assess, characterize, reduce, communicate, and tie into decision-making and support the legal aspects of decisions. Discussion on considerations for the reductions of modeled uncertainties from a fractured bedrock environment as well as asking how much effort (merits vs costs) to put into reducing the uncertainty – and accept that deep uncertainties are unlikely to be able to be reduced during a project timeframe, will be examined. Given the rapidly evolving PFAS regulatory environment, the presence of detectable concentrations can trigger continued sampling and long-term treatment of the potable water supply, possibly below Applicable or Relevant and Appropriate Requirements (ARARs). Challenges have included (1) complex sampling, (2) evolving analytical techniques, (3) development of new ARARs in multiple jurisdictions with diverging levels and approaches.
The presentation will conclude on lessons learned in communicating risks, with the added complexity of a complex fractured bedrock aquifer.
Session 2: Characterization
Conceptual Geochemical Model for Sorption and Desorption of PFAS
Peter Beck, Ph.D.
This is an important consideration in Australia, where soils are old and well leached, with low OC and carbonate content and enriched in iron and aluminium minerals. Consequently pH can play a significant role in the sorption and desorption of PFAS compounds as unlike of OC, iron and aluminium mineral sorption properties are affected by pH, with these minerals having a point of zero charge at specific pH, below which they are anion attracting, while they attract cations above the point of zero charge. Given that most PFAS compounds are anions in solution this aspect has particular significance in the Australian spoil context.
Considering these unique Australian soil properties a Conceptual Geochemical Model (CGM) was developed that considered the effects that soil mineralogy, pH and recharge on the fate and transport of PFAS compounds through the unsaturated zone to the saturated zone and the subsequent transport in the groundwater system to the a receptors. The CGM considers the geochemical dynamics in the unsaturated zone in the context of desorption, while consideration is given to the equilibrium behaviour in the saturated zone.
The conceptual mode was applied and verified using data from a coastal zone airport where PFAS impacts migrated from a former fire training ground through a freshwater groundwater system to a marine receptor. The study found that PFAS fate and transport was more akin to inorganic solute transport than organic compounds.
The Importance of Understanding Mass Distribution and Flux in Developing Remedial Strategies for PFAS Contamination
Peter Nadebaum, Ph.D.
PFAS contamination in source areas can leach out slowly, resulting in PFAS in groundwater that travels far distances. While the resulting mass of PFAS in groundwater can be much less (perhaps 1000 fold) that in the soil source area, the resulting groundwater concentrations can far exceed (one hundred to one million fold) the guideline levels for protection of human health and aquatic ecosystems.
The preferred remedial strategy in such cases may involve a combination of management and remediation methods to destroy or contain most of the contaminant mass in the source area, to intercept contamination that is leaching off site, and to manage the contamination that is off site.
With the information now at hand it is possible to estimate the aggregated cost to achieve various outcomes that would correspond to particular regulatory policy settings and guideline levels, with the resulting cost potentially ranging from hundreds of millions to billions of dollars. A typical case example is used to illustrate the issues.
Because of this, it is important to adopt a risk-based sustainable management and remediation framework for decision making that provides the best balance to outcomes and stakeholder concerns.
Session 3: Remediation
Accelerated Deployment and Startup of Ion Exchange Groundwater Treatment System Addresses PFAS Contamination at Australian Air Base
Steven Woodard, Ph.D., PE
This paper describes Defence’s phased approach to manage the PFAS contamination at RAAF Williamtown, including the accelerated design, fabrication, overseas transport, startup and operation of a successful Phase 1 water treatment system. The project was complicated by the moving target of evolving PFAS regulations in Australia.
Phase 1 began in March 2017 and involved supplying and operating a 50-gpm treatment system to demonstrate the effectiveness of the ion exchange resin-based technology. The modular treatment system was installed in a 40-foot shipping container for ease of transport and installation. PFAS removal is performed by a set of lead and lag vessels that contain Sorbix A3F regenerable anion exchange resin. The entire design/fabrication/shipping/installation process was expedited to minimize the time required to initiate PFAS remediation. A RAAF C-17 cargo plane was used to transport the modular system from the United States to Australia, shaving a month off the transport time. The unit arrived at the Williamtown base on May 28, 2017 and was fully operational in less than a month.
The system has been operating continuously and successfully since startup in June 2017. There have been no detections of any of the 34 PFAS compounds in the treated effluent, and no resin regeneration or change-out has been required.
Eliminating Risk of PFAS Contamination: Low Cost In Situ Remediation with Colloidal Activated Carbon
Scott Wilson
PFAS as a group are not ameable to destructive biodegradation. The retardation of migrating species by colloidal activated carbon is therefore finite – albeit variable with carbon dose, placement dimensions, and the concentration, nature and mix of the PFAS species. Retardation factors in the order of thousands may nevertheless be secured using colloidal activated carbon placements representing a fraction of soil mass in the order of 0.001 to 0.01 (a similar range to natural foc.) Impact on groundwater flow is therefore negligible, whereas capture / retardation is significant.
Colloidal carbon isotherm data and sorption test data are presented for specific PFAS compounds indicating excellent sorption capability and increased performance with decreasing carbon particle size. The potential for competitive sorption/elution is discussed. Plume modeling is presented indicating longevity of in situ colloidal carbon treatment for PFAS to be on the order of multiple decades before reapplication is required.
Data are presented from an actual field case site where a single application of colloidal activated carbon resulted in orders of magnitude reduction in PFAS groundwater concentrations to below USEPA health advisory levels. Design considerations for plume management are discussed including amending existing pump & treat systems to reduce project cost and to eliminate down-gradient risk to public health.
Lessons Learned from Three Years of Full-Scale PFAS Plume Management and Liquid GAC Groundwater Treatment
Dirk Pohlmann, PE
Results/Lessons Learned. At the time of the FT-02 treatment system design and installation, much was unknown about PFOA and PFOS plume behavior, and/or the LGAC treatment of these compounds, and the contaminants remain classified as an emerging contaminate. Further delineation of the plume characteristics have shown that the PFOA/PFOS plume is concentrated near the water table surface. Passive Flux meters (PFM) have been deployed to evaluate their applicability to PFOA/PFOS measurement as well as their correlation to groundwater concentrations. Groundwater samples have recently been analyzed by the total oxidable precursor (TOP) assay, with results indicating that PFOA/PFOS account for only about ~30% of total PFAS impact to the LGAC system. To date there have been eleven LGAC exchanges, with seven occurring since Bay West took over management of the FT-02 treatment system on 01 Sept. 2016. Results of the LGAC treatment effectiveness have indicated that full scale performance is significantly less than performance estimated by the initial accelerated column testing