PFAS, PFOA, and PFOS Investigation: Groundwater Transport and Human Health Risk Assessment
Project Overview
This environmental forensic investigation evaluated historical per- and polyfluoroalkyl substances (PFAS) contamination associated with the use of aqueous film-forming foam (AFFF) using accepted principles of environmental chemistry, hydrogeology, groundwater science, contaminant fate and transport, exposure assessment, and environmental forensics. The investigation integrated historical operational information, environmental sampling, groundwater investigations, hydrogeologic evaluations, water supply records, environmental chemistry, regulatory documentation, and published scientific literature to characterize PFAS migration, drinking water contamination, and potential human exposure. Rather than relying upon a single category of technical information, the investigation evaluated multiple independent datasets collected over several decades to develop a scientifically supported understanding of historical PFAS releases and contaminant migration within groundwater resources serving surrounding communities.
The investigation focused on evaluating historical PFAS releases associated with firefighting foam usage, the environmental behavior of persistent fluorinated compounds, groundwater migration, municipal and private drinking water contamination, and resulting community exposures. Particular emphasis was placed on identifying historical release areas, reconstructing contaminant migration pathways, evaluating groundwater flow, assessing public water system operations, reviewing historical water quality monitoring data, and integrating hydrogeologic information with environmental sampling to characterize the timing, magnitude, and extent of PFAS contamination. Multiple technical investigations, environmental monitoring programs, engineering reports, and peer-reviewed scientific literature were reviewed to develop a comprehensive understanding of contaminant transport from source areas to affected drinking water supplies.
The investigation was performed using accepted principles of environmental forensics, environmental chemistry, hydrogeology, groundwater modeling, contaminant fate and transport, toxicology, and quantitative exposure assessment. Available technical documentation, environmental investigations, groundwater monitoring data, water system operational records, hydrogeologic evaluations, engineering analyses, exposure information, and published scientific literature were collectively evaluated to characterize PFAS sources, environmental transport, groundwater migration, drinking water contamination, and potential human exposure. Particular emphasis was placed on evaluating historical contaminant releases, groundwater flow pathways, municipal water system operations, and the relationship between measured PFAS concentrations within environmental media and documented drinking water exposures.
Because PFAS contamination frequently develops over many years through repeated environmental releases and subsequent groundwater migration, environmental conditions were evaluated within the broader context of historical facility operations, hydrogeologic conditions, groundwater flow, contaminant persistence, water supply infrastructure, and long-term environmental monitoring rather than isolated sampling events alone. Evaluation of contaminant occurrence incorporated accepted scientific principles governing PFAS chemistry, groundwater transport, sorption, environmental persistence, groundwater recharge, drinking water distribution, and human exposure. This multidisciplinary approach provides a scientifically reliable framework for reconstructing historical PFAS contamination while remaining consistent with accepted principles of environmental forensics, environmental chemistry, hydrogeology, groundwater investigation, and exposure assessment.
Chemicals of Concern
The primary chemicals of concern evaluated during this investigation included perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and other per- and polyfluoroalkyl substances (PFAS) associated with historical use of aqueous film-forming foam (AFFF). These synthetic fluorinated compounds have been widely used for firefighting because of their exceptional surfactant properties but are also recognized for their environmental persistence, mobility, and tendency to contaminate groundwater and drinking water supplies. Evaluation of these compounds required integration of environmental chemistry, hydrogeology, groundwater science, toxicology, exposure assessment, and environmental forensics to characterize historical contaminant releases and long-term migration within environmental media. The investigation incorporated historical environmental monitoring data, groundwater investigations, water supply records, and published scientific literature to characterize PFAS occurrence and potential community exposure.
PFOA and PFOS represented the principal contaminants evaluated because they were historically used in legacy AFFF formulations and have been extensively studied due to their persistence in the environment and potential human health effects. These compounds exhibit exceptional chemical stability because of their strong carbon-fluorine bonds, allowing them to resist degradation under typical environmental conditions. Once released into soil and groundwater, PFOA and PFOS may migrate considerable distances while remaining detectable for decades, making them valuable indicators for reconstructing historical contaminant releases and evaluating long-term environmental impacts. The investigation reviewed historical groundwater monitoring data, drinking water sampling results, and published toxicological information to characterize the occurrence and distribution of these compounds within affected water supplies.
The investigation also considered additional PFAS compounds commonly associated with historical AFFF formulations and environmental degradation processes. Numerous fluorinated sulfonates and carboxylates have been identified within environmental investigations of AFFF release areas, reflecting differences in manufacturing processes, product formulations, and environmental transformation pathways. Because groundwater contamination frequently consists of complex mixtures of PFAS compounds rather than isolated chemicals, the investigation evaluated the occurrence of multiple PFAS analytes together with historical product information and environmental monitoring data to develop a more comprehensive understanding of contaminant distribution and migration.
An important component of the investigation involved evaluation of the environmental fate and transport characteristics of PFAS compounds. Unlike many conventional organic contaminants, PFAS exhibit relatively high water solubility, limited natural degradation, and complex interactions with soils, sediments, and groundwater. Migration is influenced by groundwater flow, aquifer properties, recharge conditions, soil characteristics, and historical release patterns. Because these compounds remain chemically stable while moving through groundwater systems, hydrogeologic evaluations and groundwater flow analyses formed an essential component of reconstructing contaminant migration from historical release areas to municipal and private drinking water supplies.
The principal exposure pathway evaluated during the investigation was ingestion of PFAS-contaminated drinking water supplied by municipal water systems and private groundwater wells. Historical groundwater investigations and water supply evaluations demonstrated that groundwater contamination may affect public water systems for extended periods before treatment or operational modifications reduce contaminant concentrations. The investigation therefore evaluated historical water supply operations, groundwater well usage, water distribution practices, and environmental monitoring records to characterize potential long-term community exposure through drinking water consumption. Consideration was also given to the persistence of PFAS within the human body and their tendency to bioaccumulate following repeated exposure over many years.
Finally, the investigation recognized that reliable evaluation of PFAS contamination requires integration of environmental chemistry, hydrogeology, groundwater science, environmental sampling, exposure assessment, and environmental forensics into a unified scientific framework. Published investigations consistently demonstrate that reconstruction of historical PFAS contamination depends upon combining environmental monitoring data, hydrogeologic analyses, groundwater investigations, historical operational information, water system evaluations, and accepted contaminant fate and transport principles rather than relying upon individual sampling events alone. Accordingly, this environmental forensic investigation integrated multiple independent sources of scientific information to characterize historical PFAS releases, groundwater migration, and community drinking water exposure while remaining consistent with accepted principles of environmental chemistry, hydrogeology, groundwater investigation, and quantitative exposure assessment.
Methods
The investigation was conducted using accepted principles of environmental forensics, environmental chemistry, hydrogeology, groundwater science, contaminant fate and transport, exposure assessment, and quantitative risk assessment. Because historical PFAS contamination develops over extended periods through repeated releases, groundwater migration, and complex water system operations, the evaluation integrated multiple independent sources of technical information to characterize contaminant sources, migration pathways, groundwater transport, and community exposure. Rather than relying upon a single category of evidence, the investigation incorporated historical environmental investigations, groundwater monitoring data, hydrogeologic evaluations, water system operational records, engineering analyses, regulatory documentation, environmental sampling, and peer-reviewed scientific literature to develop a scientifically supported assessment of historical drinking water contamination. This multidisciplinary approach is consistent with accepted environmental consulting practices for evaluating groundwater contamination and reconstructing historical PFAS exposure.
A substantial component of the investigation involved identifying and characterizing historical PFAS release areas associated with aqueous film-forming foam (AFFF) use. Historical operational records, engineering documents, environmental investigations, and published information describing historical firefighting activities were reviewed to identify likely release locations and evaluate the timing and magnitude of PFAS discharges. These source evaluations provided the technical foundation for subsequent hydrogeologic analyses and groundwater transport evaluations by establishing the origin of contamination and the environmental conditions influencing long-term contaminant migration.
Hydrogeologic evaluation represented a central component of the investigation. Available geologic mapping, groundwater investigations, aquifer characterizations, monitoring well data, groundwater elevations, recharge conditions, and groundwater flow analyses were reviewed to characterize contaminant migration from historical release areas to downgradient drinking water supplies. Evaluation of groundwater flow patterns, aquifer connectivity, and hydrogeologic conditions provided a scientific basis for reconstructing contaminant transport while identifying pathways capable of conveying PFAS to municipal and private water supply wells. Integration of hydrogeologic information with environmental monitoring data strengthened the overall environmental forensic evaluation by providing multiple independent lines of scientific evidence regarding contaminant migration.
The investigation also incorporated extensive review of historical groundwater monitoring and drinking water sampling data. Available analytical results collected during multiple environmental investigations were evaluated to characterize PFAS occurrence within groundwater, public water supply wells, and drinking water distribution systems. Historical sampling records were compared over time to evaluate changes in contaminant concentrations, identify the first documented occurrence of PFAS within drinking water supplies, and assess long-term trends associated with groundwater contamination. Comparison of independently collected environmental monitoring data from multiple investigations provided important scientific support for evaluating contaminant migration and community exposure.
Evaluation of municipal water system operations also formed an important component of the investigation. Historical water supply infrastructure, groundwater well operation, seasonal pumping practices, blending of groundwater sources, water distribution systems, and service areas were reviewed to characterize how contaminated groundwater entered drinking water supplies over time. Operational evaluations were integrated with groundwater monitoring data and hydrogeologic information to better understand historical exposure conditions and the distribution of PFAS within affected water systems. This systems-based approach provided additional scientific support for reconstructing historical community exposure using accepted principles of environmental engineering and groundwater resource management.
The investigation further incorporated accepted principles of exposure assessment and environmental health evaluation. Historical PFAS concentrations measured within groundwater and drinking water supplies were evaluated together with water consumption patterns, duration of exposure, and published toxicological information to characterize potential long-term human exposure. Consideration was given to historical contaminant occurrence, changes in water system operations, and the persistence of PFAS compounds within the environment and the human body. Evaluation of these multiple factors provided a comprehensive assessment of drinking water exposure while remaining consistent with accepted human health risk assessment methodologies.
Finally, the investigation employed accepted principles of uncertainty evaluation that are fundamental to environmental forensic science. Historical groundwater contamination investigations inherently involve uncertainty because contaminant releases, groundwater flow conditions, water system operations, and environmental monitoring programs evolve over time. Rather than relying upon any single dataset, the investigation addressed these uncertainties through integration of historical operational records, hydrogeologic analyses, groundwater monitoring, environmental sampling, water system evaluations, exposure assessment, and published scientific literature into a comprehensive weight-of-evidence framework. This multidisciplinary approach provides a scientifically reliable basis for reconstructing historical PFAS contamination while remaining consistent with accepted principles of environmental forensics, environmental chemistry, hydrogeology, groundwater investigation, and quantitative exposure assessment.
Results
Review of the available technical documentation demonstrated that historical PFAS contamination could be evaluated using a scientifically defensible combination of source-term reconstruction, hydrogeologic evaluation, groundwater monitoring, environmental sampling, water system analysis, exposure assessment, and environmental forensics. Although individual groundwater samples represent conditions at a specific location and time, the investigation integrated multiple independent datasets collected over several decades to characterize contaminant releases, groundwater migration, drinking water contamination, and potential human exposure. Collectively, these complementary sources of scientific information provided a comprehensive framework for reconstructing historical environmental conditions using accepted principles of environmental chemistry, hydrogeology, and contaminant fate and transport.
One of the principal findings of the investigation was the strong agreement between historical release information, hydrogeologic evaluations, groundwater monitoring data, and public water system records. Historical investigations identified multiple locations where PFAS-containing firefighting foams had been repeatedly released over many years. Hydrogeologic analyses demonstrated that groundwater flow pathways were capable of transporting these persistent contaminants toward downgradient drinking water supplies, while environmental monitoring confirmed the occurrence of PFAS within groundwater and municipal water systems. Independent agreement among source evaluations, groundwater investigations, and environmental sampling provided multiple lines of scientific evidence supporting reconstruction of historical contaminant migration and community drinking water exposure.
The investigation further demonstrated the importance of integrating hydrogeologic analyses with historical water system operations when evaluating long-term drinking water contamination. Groundwater investigations identified contaminant occurrence within aquifers supplying public water systems, while operational records describing groundwater production, seasonal pumping, well usage, blending practices, and distribution system operations provided important context for interpreting historical exposure conditions. Evaluation of these complementary datasets demonstrated that groundwater contamination and water system operations together govern the timing, magnitude, and distribution of PFAS exposure experienced by affected communities. Integration of these independent sources of information substantially strengthened the environmental forensic evaluation.
Evaluation of environmental monitoring data also demonstrated the persistence of PFAS compounds within groundwater systems and drinking water supplies. Historical groundwater investigations documented PFAS occurrence over extended periods, illustrating the exceptional environmental stability of these fluorinated compounds and their ability to migrate through groundwater while remaining detectable for many years following initial release. Comparison of historical sampling results collected during multiple investigations provided a scientifically supported understanding of contaminant occurrence, migration trends, and long-term exposure potential while confirming the importance of continued environmental monitoring during PFAS investigations.
The investigation additionally demonstrated that reconstruction of historical PFAS contamination requires consideration of groundwater flow, aquifer characteristics, recharge conditions, contaminant persistence, and environmental transport processes rather than isolated analytical results alone. Hydrogeologic investigations provided the scientific framework for interpreting contaminant migration, while groundwater monitoring confirmed the occurrence and distribution of PFAS within environmental media. Integration of groundwater science with environmental chemistry and historical operational information resulted in a more technically reliable evaluation of contaminant pathways than reliance upon environmental sampling alone. These findings illustrate the importance of combining hydrogeology, groundwater investigations, and environmental forensics when evaluating complex PFAS contamination cases.
The quantitative exposure assessment further demonstrated the value of integrating environmental monitoring, groundwater investigations, and historical water system evaluations when characterizing potential human exposure. Historical PFAS concentrations measured within groundwater and drinking water systems were evaluated together with published toxicological information and accepted exposure assessment methodologies to characterize long-term ingestion exposure. Consideration of historical contaminant occurrence, municipal water operations, and groundwater migration provided a comprehensive assessment of drinking water exposure while remaining consistent with accepted human health risk assessment principles.
Another important finding involved the successful integration of environmental chemistry, hydrogeology, groundwater science, engineering evaluation, environmental sampling, water system analysis, and quantitative exposure assessment into a unified environmental forensic framework. No individual dataset independently characterized the complexity of historical PFAS contamination or resulting community exposure. However, when historical operational information, groundwater investigations, environmental monitoring, hydrogeologic analyses, water system evaluations, and exposure assessment were considered collectively, they provided a scientifically supported reconstruction of historical PFAS releases and their environmental consequences. This multidisciplinary, weight-of-evidence approach represents a fundamental principle of modern environmental forensic investigations and provides a technically reliable framework for evaluating historical PFAS contamination affecting drinking water resources.
Conclusions
The available technical documentation provides a comprehensive scientific foundation for evaluating historical PFAS contamination using accepted principles of environmental forensics, environmental chemistry, hydrogeology, groundwater science, contaminant fate and transport, and quantitative exposure assessment. Although investigations involving PFAS frequently require reconstruction of environmental releases that occurred over many decades, the integration of historical operational information, groundwater investigations, environmental sampling, hydrogeologic analyses, water system evaluations, and exposure assessment provides a scientifically reliable framework for characterizing contaminant migration and evaluating long-term drinking water impacts. This multidisciplinary approach allows environmental professionals to reconstruct historical contamination using methodologies that are consistent with accepted scientific practice and widely recognized within the environmental consulting profession.
The investigation demonstrated that PFAS contamination is most reliably characterized when source evaluations, hydrogeologic analyses, groundwater monitoring, environmental sampling, water system operations, and exposure assessments are evaluated collectively rather than independently. This weight-of-evidence approach reduces uncertainty by integrating complementary sources of technical information and allows environmental scientists to reconstruct historical contaminant releases using methodologies that are both scientifically rigorous and consistent with accepted environmental forensic practice. Independent agreement among historical release information, groundwater investigations, water supply records, and environmental monitoring data provides a technically supported basis for evaluating contaminant migration while recognizing the inherent complexity of long-term groundwater contamination.
Review of the supporting documentation also illustrates the importance of evaluating PFAS contamination within the broader context of groundwater flow, aquifer characteristics, environmental persistence, and drinking water system operations. PFAS compounds possess exceptional chemical stability and mobility within groundwater systems, allowing contamination to migrate considerable distances while remaining detectable for many years following initial release. Environmental forensic investigations that integrate hydrogeologic analyses, groundwater monitoring, environmental chemistry, engineering evaluations, and water system operations provide a more technically accurate understanding of contaminant transport than evaluations based solely upon isolated groundwater samples. Consideration of these multiple lines of evidence is therefore essential for developing scientifically defensible interpretations of historical environmental conditions and community drinking water exposure.
The investigation further demonstrated the value of integrating groundwater investigations with quantitative exposure assessment methodologies. Historical groundwater monitoring, municipal water system evaluations, hydrogeologic analyses, environmental sampling, and published toxicological information each contributed complementary scientific information regarding contaminant occurrence and potential human exposure. Evaluation of these independent datasets allowed historical environmental conditions to be reconstructed using accepted environmental forensic methodologies while providing a comprehensive understanding of contaminant release, groundwater migration, drinking water distribution, and long-term exposure. This integrated scientific approach strengthens confidence in the overall environmental evaluation while remaining consistent with accepted principles of groundwater investigation and environmental health assessment.
More broadly, this investigation demonstrates how modern environmental consulting integrates environmental chemistry, hydrogeology, groundwater science, environmental engineering, contaminant fate and transport, quantitative exposure assessment, and environmental forensics to address complex PFAS contamination investigations. These multidisciplinary evaluations provide scientifically supported assessments of historical environmental conditions while remaining grounded in accepted hydrogeologic principles, peer-reviewed scientific literature, environmental monitoring data, and objective technical analysis. By combining historical source reconstruction, groundwater investigations, environmental sampling, water system evaluations, and quantitative exposure assessment, environmental forensic investigations are able to develop reliable evaluations of PFAS contamination that are consistent with recognized scientific practice and contemporary environmental investigation methodologies.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist, environmental forensic expert, and exposure assessment specialist with more than twenty-five years of experience evaluating PFAS contamination, groundwater quality, hydrogeology, environmental chemistry, contaminant fate and transport, drinking water systems, and human health risk. Throughout his career, Dr. Rosenfeld has conducted investigations involving PFAS, groundwater contamination, air emissions, heavy metals, petroleum hydrocarbons, volatile organic compounds, polycyclic aromatic hydrocarbons (PAHs), asbestos, dioxins, and numerous other environmental contaminants affecting drinking water supplies, residential communities, occupational settings, and ambient environmental media. His professional experience includes source-term reconstruction, groundwater investigations, environmental site assessments, quantitative exposure assessment, human health risk assessment, regulatory review, and expert witness testimony involving complex environmental contamination matters.
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