The PFAS Management, Mitigation, and Remediation Conference: Alphabetical Content Listing

PFAS Management I

Challenges Old and New for an Established Superfund-to-Drinking Water Program in Tucson, AZ

Jeff Biggs

The Tucson International Airport Area Groundwater Remediation Project (TARP) is a Federal Superfund groundwater remediation program that has produced municipal drinking water for the City of Tucson, Arizona’s water customers since 1994. Throughout TARP’s 25-year history, Tucson Water has operated two remediation wellfields and a water treatment plant (WTP) to treat volatile organic chemicals (VOCs), primarily trichloroethene (TCE). In 2002, a second water quality challenge surfaced when 1,4‑dioxane was first detected in TARP groundwater. Tucson Water initially managed 1,4-dioxane concentrations by blending TARP treated water with other potable water sources while studying effectiveness of advanced oxidation processes (AOPs). When EPA reduced the Drinking Water Health Advisory levels for 1,4-dioxane by nearly an order of magnitude in 2011, the blending approach was no longer viable, and Tucson Water completed design and construction of a UV-hydrogen peroxide AOP facility in early 2014. Having solved the TCE and 1,4-dioxane challenges, Tucson Water is now faced with its third water quality challenge at TARP due to PFOA/PFOS levels above EPA’s Drinking Water Health Advisory published in May 2016, along with ongoing operation, maintenance, and replacement challenges for aging wells. This presentation reviews TARP’s history and details its challenges and evolving innovative solutions.

H2Ohio: Governor DeWine's Water Quality Initiative

Anne Vogel

The H2Ohio Initiative created by Governor DeWine represents a significant step in securing Ohio's water quality. It also contains aspects pertinent to investment in science, research, and data management.

Identification and Characterization of the Air Deposition Pathway to PFAS Groundwater Contamination

Adam Janzen, PE

Groundwater contamination is often the result of concentrated releases of hazardous substances to the land surface or the shallow subsurface. However, even highly dispersed releases of PFAS at the land surface, such as deposition of air emissions from industrial facilities, can result in groundwater contamination above the current part-per-trillion-level screening values and health advisory limits. Only very small quantities of PFAS are necessary to contaminate water to such low levels.

Barr has modeled transport of PFOA through air, soil, and water in settings in which the primary sources of PFOA were determined to be air emissions of PFOA from industrial facilities. PFOA was deposited on the surrounding land surface over hundreds of square kilometers and then leached through the unsaturated zone to the water table. A complex modeling sequence involving AERMOD (air deposition), SWB (infiltration rate), MODFLOW-UZF (unsaturated zone flow), MODFLOW-NWT (saturated zone flow), and MT3D-USGS (unsaturated and saturated transport) was used to simulate the complete pathway from the facility stacks to groundwater receptors. This integrated multi-media modeling approach for PFAS fate and transport can provide significant value in assessing potential for contamination, predicting future concentration trends, designing remedies, and estimating cleanup times.

Implications of Using Literature Values in Modeling PFAS Fate and Transport

Neven Kresic, Ph.D., P.G.

Common question when modeling contaminant fate and transport (F&T) is acceptable use of literature vs. site-specific values for key input parameters. This question is accentuated in the case of PFAS, arguably the hottest emerging group of contaminants about which little is still known in terms of their long-term F&T in groundwater including related quantitative parameters. A typical example is the use of sorption (adsoprtion-desorption) derived from the organic carbon partitioning coefficient (K_oc). The reported literature values of K_oc vary greatly for individual PFAS and there is also a significant overlap between reported ranges for PFAS generally considered to be of different mobility (e.g., PFOA, and PFOS). Most of the common PFAS of concern are anionic and tend to sorb better at lower pH. This relationship has yet to be quantified, but the spatial distribution of groundwater pH at a site, and other factors may play an important role in creating defensible sorption in a model and more accurately matching PFAS concentrations observed in the field. It is therefore preferred to develop a site-specific partitioning coefficient by collecting co-located aqueous phase and saturated soil samples from the saturated zone in the source area.

While most perfluoroalkyl acids (such as PFOA and PFOS) are highly persistent due to the strength of the C-F bond, many polyfluoroalkyl substances (currently not routinely analyzed for at contaminated sites) can be degraded via different biological and abiotic mechanisms and act as precursors to PFAAs (perfluoroalkyl acids). These precursors, which are currently not routinely analyzed for at contaminated sites, occur in different environmental media and can result in complicated spatial and temporal distribution of PFAAs.

A case study illustrates these concepts by showing modeled development of a PFAS plume using various values of model input parameters, including site-specific, and their combinations.

Interim compliance to updated PFAS regulation

Ryan Capelle, PE

Spreading PFAS contamination and increasingly stringent health recommendations are continuously, and often abruptly, sending municipal drinking water supplies out of compliance. To meet the needs of these communities in time critical situations, streamlined solutions to PFAS treatment are necessary. Stantec’s innovative problem solving delivered emergency interim treatment plants to Cottage Grove, MN. This allowed the City to continue to supply compliant water to its residents while buying time to develop a permanent solution for compliance..

In 2017 the Minnesota Department of Health lowered recommendations for PFAS compounds, resulting in eight of eleven municipal wells in Cottage Grove out of compliance. In order to return two critical wells to compliance, the City turned to Stantec to create a streamlined design and construction schedule. This unique plan allowed Stantec and other shareholders to design, construct, and commission successful granular activated coal (GAC) treatment processes at one of the most critical wells almost exactly two months after learning about the problem. Concurrent design and construction allowed commissioning of treatment at the second well two weeks later. The design and construction of these PFAS treatment systems, which were the second and third of their kind in Minnesota, provided insight to keeping municipalities in compliance throughout development of wholistic PFAS response plans.

PFAS: Sources and Source Identification

Gregory Schnaar, Ph.D., P.G.

Regulatory activity related to per- and poly-fluoroalkyl substances (PFAS) has increased substantially in the last several years. PFAS are persistent and widespread in the environment due to usage in myriad industries and products, low degradation and sorption rates, and low environmental regulatory standards (in the parts per trillion range). However, PFAS differ from other recalcitrant contaminants in that the term encompasses thousands of chemicals, many of which degrade to one of dozens of “terminal compounds” (such as PFOS and PFOA) that are the focus of recent regulatory attention. Recognized PFAS sources include fire-fighting foams, industrial and manufacturing facilities (e.g., electronics, semi-conductors, metal plating), oil and gas production, pesticides/herbicides, and mining. PFAS are present in ski wax, and studies have even indicated PFAS impacts in ski-area snowmelt. Due to the use of PFAS in consumer products, PFAS sources also include landfills, wastewater treatment discharge, biosolids associated with wastewater treatment, and septic systems. This talk will present the relative concentration of PFAS in each of these various sources and the “fingerprint” associated with each (i.e., the relative contribution of various perfluorocarboxylates, perfluorosulfantes, and PFAS precursors). The presence of PFAS from so many potential sources must be accounted for in site investigations, and this talk will explore forensic techniques used to differentiate releases from different sources including one case-study example. In addition, the talk will compare the extent of PFAS occurrence in soils, sediments and groundwater from an environmental release as compared to potential co-contaminants as impacted by contaminant transport processes including interfacial partitioning.

PFAS Management II

PFAS Regulation – Implications of States Taking the Lead

Dylan Eberle, Ph.D.

The existing framework of Federal environmental laws work in concert to prevent and remediate environmental contamination. This cradle to grave approach provides preventative mechanisms to spread the responsibility and cost of pollution prevention across all producers and users of hazardous materials. With the current lack of federal leadership on PFAS regulation, some states are implementing regulations focused on point of use, leaving drinking water utilities and their rate payers with the majority of the financial burden of addressing PFAS contamination. This regulatory approach also exposes private well owners to additional costs of characterization and treatment. This presentation will discuss the implication of the patchwork of state regulations and their varied regulatory approaches on the effectiveness of addressing the public health risks from PFAS and the potential implications of shifting to states leading on regulation of emerging contaminants.

PFAS Source Attribution: Challenges and Opportunities

Scott Bell, PE

During the second half of the twentieth century, per- and polyfluoroalkyl substances (PFAS) were used in a very large number of consumer and industrial products, in a wide range of business sectors. The current legacy of that widespread use is that PFAS compounds of concern are being found almost ubiquitously in the environment. As more sites are investigated for PFAS impacts and the widespread presence of these compounds becomes evident, environmental professionals investigating PFAS impacts are commonly being asked source attribution questions like “is the PFAS in groundwater from the airport or the nearby landfill?” or “how do I know the PFAS in that well came from my plant?”. Over the past few years, some practitioners and researchers have taken stabs at trying to answer these difficult questions, with mixed success. Variability in the chemical compositions of original products, environmental transformation and analytical limitations all present obstacles to defensible source attribution. Drawing on the professional literature and experience from several recent and ongoing PFAS investigations in Michigan, this presentation will explain the challenges associated with source attribution and differentiation of environmental PFAS impacts and present some analytical methods and approaches for potentially overcoming these challenges.

PFAS Mitigation I

Installation, Operation and Startup of World’s First Regenerable Resin System for PFAS Removal

Rob Singer

The USAF Civil Engineering Center (AFCEC) is conducting on-going response activities to remove and remediate groundwater impacted by poly- and perfluoroalkyl substances (PFAS) at the former Pease Air Force Base in New Hampshire. The two primary PFAS compounds found at the Site are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at combined concentrations (PFOA+PFOS) above the United States Environmental Protection Agency’s (USEPA) Health Advisory Level (HAL) of 0.07 micrograms per liter (µg/l).

AFCEC contracted with Wood Group PLC to conduct a side-by-side pilot test in 2016, comparing the performance of Emerging Compound Treatment Technology’s (ECT) regenerable ion exchange (IX) resin and bituminous granular activated carbon (GAC). The regenerable resin system was selected for full-scale application, based on system performance and a lower overall lifecycle cost than GAC.

A 200-gpm system was provided to meet the primary project objective of producing treated water with combined PFOS plus PFOA concentrations below the 70 ng/l HAL.

The PFAS removal system includes bag filters to remove suspended solids, back-washable GAC pretreatment filtration to remove iron, two parallel trains of lead-lag regenerable IX resin vessels for PFAS removal, an in-vessel regeneration system to strip PFAS from the IX resin, a distillation system to recover and reuse the regenerant solution, a PFAS super-loading system to further reduce PFAS waste volume, and two parallel, single-use IX resin vessels for PFAS polishing. The polish vessels contain a blend of IX resins, tailored to the general water chemistry and PFAS species and their relative concentrations.

The PFAS remediation system has treated more than 9 million gallons of groundwater having a total influent average PFAS concentration of 70 µg/l. The effluent quality from the IX resin system has been consistently non-detect for all 13 monitored PFAS compounds, including the short-chain species, readily achieving compliance with the 70 ng/l HAL target.

System Design for Reducing PFAS to Non-Detect with PFAS-Selective Resin

Francis Boodoo

Since the issuance by US EPA of a health guideline of 70 ng/L for PFOS and PFOA in drinking water in 2016, individual states such as New Jersey, Vermont and Michigan, have issued their own, many times more restrictive, guidelines for a growing number of such PFAS. Technologies that can simultaneously and effectively remove a suite of PFAS to non-detect levels are highly desirable. But the current methods of operating field pilots or running accelerated column testing to evaluate the effectiveness of competing removal technologies is inefficient and can significantly delay the implementation of viable full-scale treatment systems. This paper provides some early insights in the development of a desktop modeling tool for PFAS-selective resin that has been field-proven to effectively remove a suite of PFAS to non-detect levels. Inputs to the model includes individual PFAS concentrations, background chemistry and reduction targets such as non-detect or higher. The paper compares predicted and actual results for removal of common PFAS such as PFOS, PFOA, PFHxS, PFHpA and PFNA. Included is a discussion on system design and operating guidelines that can be useful to both consultants and end-users.

PFAS Mitigation II

Complex PFAS Sampling at Two Industrial Sites

Jack Sheldon

Background. Two industrial facilities in the Northeast and Midwest were the sites of unique risk determinations for per/polyfluoroalkyl substances (PFAS) through complex sampling programs. The Northeast site was an asphalt batching plant where suppression of a petroleum tanker fire was accomplished through the application of Aqueous Film Forming Foam (AFFF). The Midwest site was a chemical manufacturing facility using fluorosurfactants to formulate demisting products for the chrome plating industry. In both cases, site owners were concerned of potential PFAS impacts from their site to drinking water or public stormwater treatment.

Approach. At the Northeast site, understanding distribution of the AFFF and the risks associated with it both on-site and in an adjacent river were critical to developing the conceptual site model and mitigation plan. A “rinse-based” sampling program was established to sample site infrastructure and pointed to specific sources of PFAS that were leaching to stormwater and discharging to the river.

At the Midwest site, legacy use of exempted long chain PFAS-containing raw materials and more recent transition to short chain PFAS-containing raw materials sparked a sampling program focused on raw material and wastewater. Discharge to a public wastewater treatment plant was of chief concern.

Results/Lessons Learned. Details of the sampling programs will be described and the challenges of sampling under complex scenarios will be discussed. Careful review of sampling procedures and regular communication with the analytical laboratories is essential to achieving accurate results. These are key lessons learned from the projects. The analytical results for each site will be presented and put in context to the site scenarios. For the Northeast site, options considered and the strategic approach taken to remedy the PFAS issue will be detailed leading to a No Further Action (NFA) declaration. PFAS mitigation steps for the Midwest facility will also be described.

Effectiveness of Colloidal Activated Carbon as an in-situ Treatment to Mitigate PFAS

Scott Wilson

The Michigan Department of Military and Veteran Affairs (DMVA) have been remediating chlorinated solvents impact in the site groundwater from historical operations at the Grayling Army Airfield facility since the 1990’s. In 2016, the DMVA became aware of the potential contamination of PFAS from historical operations. PFAS was found commingled with a chlorinated solvent plume that was migrating towards the property boundary. The DMVA reviewed potential remedial options to test in the field, but ultimately decided to test an in-situ reactive barrier application of colloidal activated carbon, an approach that is first of its kind in the State of Michigan.

Colloidal activated carbon was selected because of the expected rapid reductions of PFAS by removal from the dissolved mobile phase and its expected lower total project costs. Colloidal activated carbon effectively increases the retardation factor of PFAS migration contaminants by multiple orders of magnitude and eliminates the exposure to down-gradient receptors.

This presentation will review the project design considerations, field activities, and post- application data. Additionally, the presentation will answer questions related to the distribution of the colloidal activated carbon in the subsurface and expected long-term efficacy at the site.

Filtration – THE Solution to the PFOA/PFOS Crisis

Danny Bauer

Water filtration technology is highly effective at removing emerging contaminants PFOA/PFOS from drinking water at the POE (Point-of-Entry) and POU(Point-of-Use). Filtration systems that are independently certified to the NSF/ANSI Standard P473 and parts of NSF/ANSI Standard 53, meet minimum standards of filtration for these contaminants, including flow rates, pressure drop and other requirements of system design. A POE water treatment system installed on the consumer side of the meter with the express purpose of treating all the incoming water before it goes into the individual supply lines, perhaps is the solution.

The water treatment industry has developed Standards and specifically designed POE & POU devices that filter all the water as it enters a home, business, school, etc…with nearly immediate implementation and preventative exposure for more than 15 million (up to 110 million) Americans across 27 states, for years to come, to these chemicals.

POE filters can be effective at reducing PFOA/PFOS and consistent with a primary prevention approach to childhood exposure and would fill the regulatory gap that necessarily results in dealing with these chemicals at the tap. Filtration technology implements a primary prevention approach because removing PFOA/PFOS from water at the tap prevents exposure. Understanding the technologies required, the certification process, the NSF/ANSI Standards for product certification, along with filtration systems that could be implemented nationally is the topic of this presentation and discussion.

Novel Tools for PFAS Site Characterization

Kavitha Dasu

Per- and polyfluoroalkyl substances (PFAS) are widely used for many commercial and industrial applications. Most PFAS-containing products use a proprietary, technical grade mixture of PFAS designed to impart specific performance-based characteristics to the products (e.g., heat resistance, surfactant properties). PFAS ground water and soil contamination at aqueous film forming foams (AFFF) impacted sites often cover large areas and may include multiple source areas. As the number of PFAS contaminated sites are on the rise. There is a need for novel site characterization tools to quantify PFAS near contaminated sites and investigate the sources of contamination. There are more than 3000 PFAS chemicals in the global market, the known quantifiable PFAS account for very small fraction and only limited number of analytes can be quantified using the known analytical procedures. Battelle is developing novel site characterization tools to measure the total PFAS and identify the sources of PFAS contamination. The presentation will discuss the results of the following techniques: (a) a PFAS passive sampler to obtain time-integrated concentrations and provide better long-term site characterization by capturing a realistic understanding of how hydrological conditions influence concentrations at the point of discharge, (b) a rapid potentiometric method to measure the free fluoride generated by the quick reductive defluorination of PFAS in the environmental samples, and (c) a forensic approach for better understanding of PFAS profiles in differentiating sources of contamination at PFAS contaminated sites.

Regeneration of Granular Activated Carbon used for Polyfluorinated Substance (PFAS) Remediation

Ryan James

With the emerging evidence of PFAS toxicity, federal and state agencies have been issuing drinking water advisories. Recent EPA guidelines (2016) establish the advisory level for combined perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) concentration in drinking water at 70 parts per trillion (ppt). The most commonly used treatment for PFAS contaminated water relies on the use of granular activated carbon, GAC; however, there are currently no efficient regeneration options for spent GAC. This research investigates GAC regeneration and performance of regenerated GAC in adsorbing PFOA and PFOS. The objective of this project is to develop a regeneration method for GAC that has been used for removal of PFAS from groundwater such that the GAC maintains its sorption capacity for PFOA and PFOS.

All the experiments were conducted in polypropylene centrifuge tubes. Initially, virgin (uncontaminated) GAC was exposed to aqueous PFOA and PFOS solution in a batch reactor and develop sorption kinetics. Contaminated GAC was eluted with various solvent combinations. Eluents were collected for analyses at a few time intervals to assess the desorption efficiency and kinetics. Followed by desorption of the PFOA and PFOS contaminated GAC, sorption isotherm batch reactor experiments were conducted. The GAC was again exposed to aqueous PFOA and PFOS solution to evaluate the sorption capacity of the regenerated GAC. The PFOA and PFOS was analyzed using liquid chromatography tandem mass spectrometry, LC-MS/MS.

The solid to liquid ratio was determined to be 5mg/50 mL. The laboratory batch sorption kinetics data showed 99 – 100% removal of PFOA and PFOS to GAC in 10 days. Increasing hydrophobicity and basicity showed to have better desorption capacity. The presentation discusses the sorption and desorption kinetics of GAC and development of the regeneration method for the spent GAC.

PFAS Remediation

Advanced Oxidation/Reduction for PFAS in Co-Contaminated Groundwater

Scott A. Grieco, Ph.D., PE

Background/Objectives. Per and polyfluoroalkyl substances (PFAS) are increasingly being identified in groundwater and potable water supplies at concentrations exceeding State and Federal guidance values and standards. Currently, only transfer technologies such as adsorption or reverse osmosis are being utilized for treatment. As a pre-treatment or full replacement to adsorption, destructive technologies for PFAS need to be demonstrated at scale.

Previous work has shown significant rates of degradation of PFOA and PFOS (>85%) via ozonation under alkaline conditions and catalyzed with hydrogen peroxide (Lin, et. al, 2012). This work was recently replicated using ozone only with commercially scalable equipment with excellent replication of results (>95%) (Piper, 2016). The confirmational work supports the benefit of alkaline conditions. For this current work, methods similar to those employed previously were evaluated using a commercially available system.

Approach/Activities. Groundwater samples were collected from the most impacted portion of the PFAS groundwater plume at the subject sites. A screening matrix was developed to evaluate performance variables. Based on this screening matrix, bench-scale testing was conducted to assess application methodology (with and without peroxide catalyzation), pH, and oxidant dosage on the destruction efficiency of PFAS using site groundwater impacted by a co-mingled plume containing high concentrations of both PFAS and other organic compounds (VOCs and TPH). The results of the screening matrix were used to select optimum conditions to establish destruction dose-response curves for targeted contaminants and identify the optimal conditions needed to translate the bench-scale results into a field-scale pilot study.

Results/Lessons Learned. This study supports previous academic testing into a potentially field-worthy application using commercially available advanced oxidation equipment. Previous results will be presented to be compared to data from the current testing program. Impacts of process variables will be analyzed and discussed. The field pilot implementation plan will also be presented.

PFAS Wellhead Treatment Considerations - Intersection of Water Supply with Plume Remediation

Avram Frankel, PE

Emerging contaminants present a unique challenge to municipal drinking water supplies due to evolving regulations, permitting challenges, and participation of multiple and diverse stakeholders. An engineering case study shows how some of these concerns were addressed during the implementation of a potable water wellhead treatment system for a long chain perfluoroalkyl acid. Initial feasibility studies evaluated alternatives, including relocating municipal wells, blending impacted water with water from non-impacted wells, well modifications, and wellhead treatment. Ultimately, wellhead treatment was selected and implemented. Challenges included adapting to evolving performance targets, addressing uncertainty in handling waste streams, and balancing competing interests from participating parties. Cooperation of all parties resulted in the installation and acceptance of an optimized system that is providing potable water meeting all regulatory criteria. Moving beyond this case study, the evaluation, design and installation of GAC and ion exchange PFAS potable water treatment systems will be discussed, including operations lessons-learned. Other topics will include increasing regulation of a broader suite of PFAS compounds and implications for treatment system design from a water supply perspective, and combined wellhead potable water treatment and PFAS groundwater remediation strategies to address PFAS plumes from a responsible party perspective.

Removal of PFOA by Carbon Treatment in a Public Water System: A Ten-Year Case Study

Linda Aller, CPG

When the Little Hocking Water Association, a rural public water supply in southeastern Ohio, first learned about contamination of their wellfield by perfluorooctanoic acid (PFOA) in 2002, little was known about the chemical. Even less was known about potential treatment methods. Field investigations revealed that production wells in the wellfield had concentrations of PFOA as high as 22,000 ppt and that monitoring wells had concentrations as high as 78,000 ppt. In addition, soil concentrations were measured to be as high as 52,800 ppt.

A pilot study indicated that food grade activated carbon would remove these levels of PFOA. In November 2007, a treatment system using two vessels in series containing 20,000 pounds of food grade carbon was placed online and has been successfully operated since that time. This presentation will review the concentrations of influent PFOA over time, the effectiveness and replacement frequency of the carbon, and the long-term implications for treatment cessation.

Risk Assessment of Per- and Polyfluoroalkyl Substances in Support of Brownfield Redevelopment

Krista Barfoot, Ph.D., C.Chem., QPRA

Investigation of per- and polyfluoroalkyl substances (PFAS) to date has largely focused on manufacturing sites and fire training areas (due to use of aqueous film-forming foam [AFFF]); however, consideration of the presence and potential risks associated with PFAS is now expanding to waste management (e.g., landfill leachate and biosolids) and brownfield redevelopment. The potential presence of PFAS at brownfield sites has implications for their redevelopment as evaluating the associated risks, and processing the sites through applicable regulatory frameworks, is largely undefined. While research, data, and information are evolving quickly on PFAS toxicology and the fate and transport of these parameters in the environment, regulatory screening values and risk assessment (RA) approaches are lagging.

This presentation will examine the approach by which human health and ecological risk assessment can be completed for a brownfield site where AFFF was applied during a fire. The review will outline the screening levels and toxicity values that may be applied to support the RA, as well as the conceptual human health and ecological exposure models needed to complete risk evaluations. By stepping through the RA process for a site, a viable framework for assessing and addressing PFAS at brownfield sites can be established.