Environmental Forensic Investigation of PFAS Migration from a Municipal Solid Waste Landfill
Groundwater Assessment, Leachate Characterization, Hydrogeologic Evaluation, and Environmental Fate and Transport
Project Overview
Municipal solid waste landfills have become an increasing focus of environmental forensic investigations because they can serve as long-term reservoirs for per- and polyfluoroalkyl substances (PFAS) originating from a wide variety of consumer, commercial, and industrial waste streams. Unlike many legacy contaminants that degrade over time, PFAS are highly resistant to biological, chemical, and thermal degradation, allowing them to persist within landfill waste for decades. As precipitation infiltrates landfill cells, these compounds may partition into landfill leachate, migrate through engineered containment systems if deficiencies exist, or ultimately enter groundwater and nearby surface waters. Understanding these complex environmental processes requires a multidisciplinary investigation integrating hydrogeology, environmental chemistry, engineering, contaminant fate and transport, landfill design, groundwater modeling, and human health exposure assessment (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
RoseyFields conducted a comprehensive environmental forensic investigation involving a large municipal solid waste disposal facility to evaluate the occurrence, migration, and long-term environmental behavior of PFAS associated with landfill operations. The investigation focused on determining potential sources of PFAS entering the waste stream, evaluating the effectiveness of engineered containment systems, assessing groundwater and surface water migration pathways, and reconstructing the complete source-to-receptor pathway using multiple independent lines of scientific evidence. Rather than relying solely on environmental monitoring results, the investigation integrated landfill engineering documentation, groundwater monitoring records, construction quality assurance information, hydrogeologic evaluations, leachate management practices, regulatory guidance, and peer-reviewed scientific literature to develop a scientifically supported assessment of PFAS transport within the surrounding environment (Brusseau, 2018; EPA, 2024).
A significant component of the investigation involved evaluating how engineered landfill systems influence the environmental fate and transport of persistent contaminants. Modern landfill designs utilize composite liner systems, leachate collection infrastructure, groundwater monitoring networks, and landfill gas management systems to reduce the potential for contaminant migration. However, environmental forensic investigations must evaluate not only the original design of these systems but also their long-term performance, operational history, groundwater flow conditions, contaminant persistence, and the potential for continued environmental loading over decades of landfill operation. Integrating engineering evaluations with hydrogeologic analyses provides a more complete understanding of contaminant migration than either discipline alone (Koerner & Koerner, 2018; Christensen et al., 2001).
The investigation also evaluated the evolving regulatory landscape surrounding PFAS and its implications for municipal waste management. As federal and state agencies continue to establish increasingly stringent drinking water standards, groundwater criteria, and hazardous substance designations for certain PFAS compounds, landfill operators face growing technical and regulatory challenges associated with monitoring, managing, and mitigating these persistent contaminants. By integrating environmental chemistry, hydrogeology, landfill engineering, exposure science, and environmental forensics within a weight-of-evidence framework, RoseyFields developed a comprehensive scientific assessment of PFAS migration that demonstrates the importance of multidisciplinary environmental investigations when evaluating emerging contaminants in complex landfill environments (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. Environmental Protection Agency [EPA], 2024).
Chemicals of Concern
The primary chemicals of concern evaluated during this environmental forensic investigation were per- and polyfluoroalkyl substances (PFAS), a large class of synthetic fluorinated compounds widely recognized for their exceptional environmental persistence, chemical stability, and resistance to natural degradation. Because the carbon-fluorine bond is among the strongest in organic chemistry, PFAS remain in landfill waste, leachate, soils, groundwater, surface water, sediments, and biological systems for decades after disposal. Municipal solid waste landfills receive PFAS from numerous waste streams, including consumer products, industrial materials, textiles, food packaging, biosolids, construction debris, and other discarded materials, making landfills important long-term reservoirs for these contaminants (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
Particular emphasis was placed on perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), two of the most extensively studied PFAS compounds due to their widespread historical use, environmental persistence, bioaccumulative properties, and documented human health effects. These compounds have been detected in landfill leachate throughout the United States and are frequently identified in groundwater and surface water near municipal solid waste disposal facilities. Numerous toxicological and epidemiological studies have associated long-term exposure to PFOA and PFOS with adverse health outcomes, including developmental effects, immune system suppression, elevated cholesterol, thyroid dysfunction, kidney disease, and certain cancers. As a result, these compounds have become the focus of increasingly stringent federal and state drinking water regulations and environmental cleanup initiatives (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. EPA, 2024).
The investigation also considered the behavior of other PFAS compounds and precursor chemicals that may be present within landfill waste. Many precursor compounds gradually transform through biological, chemical, or environmental processes into terminal degradation products such as PFOA and PFOS, extending the duration of contaminant releases long after waste disposal has occurred. Consequently, evaluating only a limited number of individual PFAS compounds may underestimate the long-term environmental loading associated with landfill operations. A comprehensive environmental forensic investigation therefore considers both persistent end products and the potential contribution of precursor compounds capable of generating additional PFAS over time (Cousins et al., 2020; ITRC, 2024).
Landfill leachate represents one of the primary mechanisms through which PFAS migrate from waste materials into the surrounding environment. As precipitation infiltrates waste, PFAS dissolve into the leachate and may be transported through collection systems for treatment or disposal. Where engineered containment systems become compromised or where historical disposal occurred before modern liner requirements, PFAS may migrate into surrounding soils, groundwater, and nearby surface waters. Because many PFAS compounds exhibit relatively high mobility in groundwater and limited natural attenuation, these releases may persist for decades and extend considerable distances from their original source, depending upon hydrogeologic conditions and groundwater flow characteristics (Brusseau, 2018; Christensen et al., 2001).
In addition to groundwater transport, the investigation evaluated the potential for PFAS movement through landfill gas and atmospheric pathways. Although groundwater and leachate remain the dominant transport mechanisms for most PFAS compounds, recent research has demonstrated that certain fluorinated compounds may partition into landfill gas or become associated with airborne particles, allowing atmospheric transport and subsequent deposition to surrounding soils and surface waters. Evaluating these multiple environmental pathways is essential for developing a complete conceptual site model and accurately characterizing the long-term environmental fate and transport of PFAS released from municipal solid waste landfills (Sha et al., 2025; U.S. EPA, 2024).
Methods
A multidisciplinary environmental forensic investigation was conducted to evaluate the occurrence, migration, and long-term environmental behavior of PFAS associated with municipal solid waste disposal operations. The investigation integrated landfill engineering, hydrogeology, environmental chemistry, contaminant fate and transport, groundwater monitoring, environmental statistics, regulatory analysis, and exposure assessment to develop a scientifically supported understanding of potential PFAS migration within and beyond the landfill boundary. Rather than relying on a single dataset, multiple independent lines of scientific evidence were evaluated using a weight-of-evidence approach to characterize contaminant sources, assess engineered containment systems, reconstruct migration pathways, and evaluate potential environmental exposures (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
The investigation began with a comprehensive review of engineering documentation describing landfill design, construction, expansion, and operational history. Construction quality assurance records, liner system specifications, leachate collection infrastructure, landfill gas management systems, and groundwater monitoring network designs were evaluated to determine how engineered containment systems were intended to control contaminant migration throughout the operational life of the facility. Particular attention was given to the evolution of landfill construction practices, recognizing that containment technologies have changed substantially over time as environmental regulations and engineering standards have advanced (Koerner & Koerner, 2018; U.S. EPA, 2004).
Hydrogeologic conditions were evaluated to characterize groundwater flow directions, hydraulic gradients, aquifer characteristics, recharge conditions, and potential contaminant migration pathways. Historical groundwater monitoring data from multiple monitoring locations were reviewed to identify long-term trends, evaluate groundwater flow patterns, distinguish background conditions from site-related influences, and assess whether contaminant distributions were consistent with expected groundwater transport mechanisms. Surface water information was also evaluated where appropriate to determine potential hydraulic connections between groundwater and nearby receiving waters and to assess potential off-site migration through interconnected hydrologic systems (Freeze & Cherry, 1979; Fetter, 2018).
Environmental monitoring data were reviewed to evaluate groundwater quality, leachate chemistry, and other available environmental media for the presence and distribution of PFAS. Historical analytical results were examined to identify concentration trends, compare detections among monitoring locations, and evaluate temporal changes in groundwater quality over multiple monitoring events. Statistical evaluations were incorporated where appropriate to distinguish natural variability from meaningful changes in groundwater chemistry and to determine whether observed contaminant distributions were consistent with expected landfill-related migration patterns. Integrating historical monitoring information with hydrogeologic analyses provided a robust framework for evaluating contaminant fate and transport over extended periods of landfill operation (ASTM International, 2021; U.S. EPA, 2024).
The investigation also evaluated landfill leachate management because leachate represents one of the principal transport mechanisms for PFAS released from municipal solid waste facilities. Engineering evaluations considered how leachate is generated, collected, managed, treated, and ultimately discharged, while environmental chemistry principles were applied to understand the behavior of persistent fluorinated compounds throughout these processes. Current scientific literature describing PFAS occurrence in landfill leachate, treatment limitations, contaminant persistence, and potential recycling of PFAS through wastewater treatment systems was incorporated into the overall environmental forensic evaluation (Lang et al., 2017; ITRC, 2024).
Finally, engineering evaluations, groundwater monitoring records, hydrogeologic analyses, environmental chemistry, statistical assessments, regulatory guidance, and peer-reviewed scientific literature were synthesized into a comprehensive conceptual site model describing the complete source-to-receptor pathway. By integrating multiple scientific disciplines, the investigation evaluated how PFAS may migrate from disposed waste through landfill systems, groundwater, and other environmental media over long periods of operation. This multidisciplinary methodology provides a scientifically rigorous framework for environmental consulting, regulatory investigations, remediation planning, environmental due diligence, and complex environmental litigation involving persistent contaminants in landfill environments (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. Environmental Protection Agency [EPA], 2024).
Results
The environmental forensic investigation demonstrated that multiple independent lines of scientific evidence were consistent with municipal solid waste landfills serving as long-term reservoirs and potential sources of PFAS to surrounding environmental media. Review of landfill engineering documentation, groundwater monitoring data, hydrogeologic evaluations, environmental chemistry, and published scientific literature supported the conclusion that PFAS released from disposed waste can migrate through landfill leachate, groundwater, and, under certain conditions, additional environmental pathways. Rather than relying upon individual monitoring results, the investigation integrated complementary engineering and environmental datasets to evaluate the complete contaminant transport pathway from waste disposal to potential environmental receptors (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
Evaluation of the groundwater monitoring network demonstrated the importance of long-term environmental monitoring for identifying contaminant trends and characterizing groundwater flow conditions surrounding engineered waste disposal facilities. Historical monitoring data provided valuable information regarding groundwater elevations, flow directions, hydraulic gradients, and temporal changes in groundwater quality. When interpreted together with hydrogeologic conditions and landfill engineering information, these data allowed the investigation to distinguish expected groundwater movement from localized variability while providing a scientifically supported understanding of contaminant migration within the subsurface environment (Freeze & Cherry, 1979; Fetter, 2018).
Engineering evaluations demonstrated that modern landfill containment systems substantially reduce the potential for contaminant migration when properly designed, constructed, operated, and maintained. Composite liner systems, leachate collection infrastructure, groundwater monitoring networks, and landfill gas management systems represent multiple layers of environmental protection intended to minimize releases to surrounding environmental media. However, the investigation also demonstrated that environmental forensic evaluations must consider the operational history of landfill facilities, recognizing that engineering practices, regulatory standards, and containment technologies have evolved considerably over time. Consequently, long-term environmental performance should be evaluated using historical operating conditions, construction practices, and monitoring information rather than relying solely on current engineering design (Koerner & Koerner, 2018; Christensen et al., 2001).
The investigation further demonstrated that landfill leachate represents one of the principal mechanisms by which PFAS may migrate from disposed waste into the surrounding environment. Published scientific literature consistently shows that landfill leachate frequently contains measurable concentrations of multiple PFAS compounds because these contaminants are released from numerous consumer, commercial, and industrial products disposed throughout the operational life of municipal landfills. Once generated, leachate management practices become a critical component of environmental protection because they influence the movement, treatment, and ultimate disposition of persistent fluorinated compounds. Evaluating leachate generation, collection efficiency, treatment processes, and discharge pathways therefore provided an essential component of the overall environmental forensic assessment (Lang et al., 2017; U.S. EPA, 2024).
Finally, the investigation illustrated the importance of integrating engineering, hydrogeology, environmental chemistry, statistical analysis, and regulatory science when evaluating PFAS contamination associated with landfill operations. No individual dataset alone fully characterized the environmental behavior of PFAS or the effectiveness of landfill containment systems. Instead, combining engineering documentation, groundwater monitoring records, contaminant fate and transport principles, historical operational information, and environmental monitoring results produced a comprehensive conceptual site model that explained the observed environmental conditions using accepted scientific methodologies. This multidisciplinary approach provides a robust environmental forensic framework for evaluating landfill-related PFAS contamination, source attribution, regulatory compliance, and long-term environmental risk associated with persistent contaminants (National Academies of Sciences, Engineering, and Medicine, 2022; ASTM International, 2021).
Conclusions
This environmental forensic investigation demonstrated the importance of evaluating PFAS contamination at municipal solid waste landfills using a comprehensive, multidisciplinary approach that integrates landfill engineering, hydrogeology, environmental chemistry, contaminant fate and transport, groundwater monitoring, and exposure science. Because PFAS persist within disposed waste for decades and migrate through multiple environmental media, understanding their environmental behavior requires evaluation of the complete source-to-receptor pathway rather than focusing exclusively on isolated groundwater or leachate measurements. By integrating engineering documentation, environmental monitoring data, hydrogeologic evaluations, and current scientific literature, the investigation developed a scientifically supported conceptual model describing the long-term movement of PFAS within the landfill environment (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
The investigation demonstrated that landfill engineering systems—including composite liners, leachate collection infrastructure, groundwater monitoring networks, and landfill gas management systems—play a critical role in limiting contaminant migration and protecting surrounding environmental resources. However, the long-term effectiveness of these systems depends not only on their original design but also on construction quality, operational practices, maintenance, regulatory oversight, and changing environmental conditions throughout the life of the facility. Consequently, environmental forensic investigations must evaluate historical engineering practices alongside current environmental monitoring results to fully characterize contaminant behavior and potential migration pathways (Koerner & Koerner, 2018; Christensen et al., 2001).
The investigation further illustrated that groundwater monitoring alone provides only part of the environmental picture. Understanding PFAS migration requires integrating groundwater data with hydrogeologic conditions, leachate management practices, contaminant chemistry, landfill engineering, and environmental fate and transport principles. This holistic approach allows investigators to distinguish naturally occurring variability from landfill-related influences while improving confidence in source attribution and long-term environmental assessments. As regulatory standards for PFAS continue to evolve, comprehensive investigations that incorporate multiple scientific disciplines will become increasingly important for evaluating environmental compliance, prioritizing remediation strategies, and managing long-term environmental liabilities (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. EPA, 2024).
This case study highlights the growing role of environmental forensic science in addressing emerging contaminants associated with modern waste management systems. By combining engineering evaluations, groundwater investigations, environmental chemistry, hydrogeologic analysis, statistical interpretation, and contaminant fate and transport modeling, RoseyFields provides scientifically rigorous assessments capable of evaluating complex environmental contamination scenarios involving PFAS and other persistent chemicals. These multidisciplinary investigations support environmental consulting, regulatory investigations, remediation planning, environmental due diligence, and expert witness services by providing objective, evidence-based evaluations of contaminant migration, source attribution, and potential human and ecological exposure using accepted scientific methodologies.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and environmental forensic expert with extensive experience in PFAS investigations, landfill contamination assessments, groundwater and leachate evaluations, hydrogeologic analysis, contaminant fate and transport, and human health exposure assessment. Dr. Rosenfeld’s work focuses on complex environmental contamination matters involving municipal solid waste landfills, emerging contaminants, PFAS in leachate and groundwater, source attribution, landfill engineering performance, subsurface migration, and long-term environmental impacts to soil, groundwater, surface water, and surrounding communities. His expertise includes evaluating complete source-to-receptor pathways through the integration of landfill engineering, hydrogeology, environmental chemistry, groundwater monitoring, statistical analysis, exposure assessment, toxicology, and regulatory science to determine whether waste disposal operations and engineered containment systems are consistent with observed environmental conditions. Through RoseyFields LLC, Dr. Rosenfeld provides environmental forensic analysis, environmental due diligence, regulatory and compliance support, remediation evaluation, toxic tort and personal injury case assessment, and expert witness testimony involving PFAS contamination, landfill leachate migration, groundwater impacts, and long-term environmental and human health risks associated with persistent contaminants.
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