Environmental Forensic Investigation of PFAS Migration from an Engineered Municipal Solid Waste Landfill
Hydrogeologic Evaluation, Landfill Engineering, Groundwater Monitoring, and Environmental Fate and Transport
Project Overview
Municipal solid waste landfills are complex engineered systems designed to isolate waste from the surrounding environment through the use of composite liner systems, leachate collection infrastructure, groundwater monitoring networks, stormwater controls, and long-term environmental management practices. Despite these engineering safeguards, modern environmental forensic investigations increasingly focus on understanding the long-term behavior of persistent contaminants, particularly per- and polyfluoroalkyl substances (PFAS), within landfill environments. Because PFAS are resistant to biological, chemical, and thermal degradation, they may remain within disposed waste for decades and migrate through leachate, groundwater, surface water, or other environmental pathways under certain hydrogeologic conditions. Evaluating these processes requires a multidisciplinary understanding of landfill engineering, hydrogeology, environmental chemistry, contaminant fate and transport, groundwater monitoring, and 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 engineered municipal solid waste landfill to evaluate the occurrence, migration, and long-term environmental behavior of PFAS and other landfill-related constituents. The investigation examined the effectiveness of engineered containment systems, groundwater monitoring data, construction quality assurance documentation, hydrogeologic conditions, and long-term environmental monitoring records to determine whether available scientific evidence supported contaminant migration beyond the engineered waste management system. Rather than relying solely on analytical data, the investigation integrated landfill engineering, environmental monitoring, hydrogeologic analyses, regulatory documentation, and peer-reviewed scientific literature to develop a scientifically supported conceptual model describing contaminant movement within the landfill environment.
A significant component of the investigation involved evaluating the design, construction, and long-term performance of engineered containment systems. Construction quality assurance documentation describing composite liner installation, geosynthetic materials, leachate collection systems, and engineered barrier verification was reviewed alongside groundwater monitoring reports and long-term hydrogeologic evaluations to assess whether the landfill’s environmental protection systems functioned as intended. The investigation also considered how groundwater flow conditions, leachate generation, natural geologic variability, and evolving landfill operations influence the environmental fate and transport of persistent contaminants over extended operational periods.
By integrating environmental chemistry, hydrogeology, landfill engineering, groundwater monitoring, environmental statistics, and contaminant fate and transport within a multidisciplinary weight-of-evidence framework, RoseyFields developed a comprehensive environmental forensic assessment of landfill performance and potential contaminant migration. This investigation demonstrates how combining engineering evaluations with long-term environmental monitoring provides a scientifically rigorous approach for assessing emerging contaminants, supporting regulatory investigations, environmental due diligence, remediation planning, and complex environmental litigation involving engineered waste management facilities (National Academies of Sciences, Engineering, and Medicine, 2022; ASTM International, 2021).
Chemicals of Concern
The primary chemicals of concern evaluated during this environmental forensic investigation were per- and polyfluoroalkyl substances (PFAS), a diverse class of synthetic fluorinated compounds recognized for their exceptional chemical stability, resistance to degradation, and long-term environmental persistence. Because the carbon-fluorine bond is one of the strongest in organic chemistry, PFAS remain in landfill waste, leachate, groundwater, surface water, sediments, and biological systems long after disposal. Municipal solid waste landfills receive PFAS from numerous consumer, commercial, institutional, and industrial waste streams, making them important long-term reservoirs for these contaminants. Understanding the occurrence and movement of PFAS within engineered landfill systems is therefore an increasingly important component of modern environmental forensic investigations (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
Particular attention was given to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), two of the most extensively studied PFAS compounds because of their widespread historical use, persistence, mobility, and documented human health effects. Numerous toxicological and epidemiological investigations have associated chronic exposure to these compounds with developmental effects, immune system suppression, altered lipid metabolism, thyroid dysfunction, kidney disease, and certain cancers. These health concerns have led to increasingly stringent drinking water standards and environmental regulations, making evaluation of potential PFAS migration an essential component of landfill monitoring and environmental risk assessment (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. EPA, 2024).
The investigation also considered additional PFAS compounds and precursor substances commonly encountered in municipal waste streams. Many fluorinated precursor compounds gradually transform through biological, chemical, or environmental processes into terminal degradation products such as PFOA and PFOS, extending contaminant loading long after waste placement has occurred. Because landfill waste contains a complex mixture of consumer products, textiles, food-contact materials, industrial wastes, biosolids, and construction debris, environmental forensic investigations must evaluate the broader class of PFAS rather than focusing exclusively on a small number of regulated compounds. This comprehensive approach provides a more representative assessment of long-term contaminant behavior and environmental risk (Cousins et al., 2020; ITRC, 2024).
In addition to PFAS, the investigation evaluated traditional groundwater indicator parameters and inorganic constituents commonly monitored at municipal solid waste landfills to assess overall landfill performance and groundwater quality. Parameters including major ions, dissolved metals, volatile organic compounds, ammonia, total dissolved solids, alkalinity, and other groundwater quality indicators provide important information regarding leachate migration, geochemical conditions, and the effectiveness of engineered containment systems. Long-term evaluation of these constituents, combined with statistical trend analysis and hydrogeologic interpretation, allows environmental professionals to distinguish naturally occurring groundwater variability from conditions that may indicate potential releases from landfill operations (U.S. EPA, 2009; ASTM International, 2021).
The environmental behavior of PFAS differs substantially from many conventional landfill contaminants because these compounds exhibit both exceptional persistence and, for many species, relatively high groundwater mobility. Once released into landfill leachate, PFAS may migrate through engineered collection systems or, where containment is compromised, infiltrate surrounding soils and groundwater. The extent of migration depends on compound-specific chemistry, sorption characteristics, groundwater flow conditions, aquifer properties, and long-term hydrologic processes. Consequently, evaluating PFAS requires integrating landfill engineering, hydrogeology, environmental chemistry, and contaminant fate and transport to characterize the complete source-to-receptor pathway and develop a scientifically supported understanding of long-term environmental behavior (Brusseau, 2018; Anderson et al., 2019).
Methods
A multidisciplinary environmental forensic investigation was conducted to evaluate the long-term environmental performance of an engineered municipal solid waste landfill and to assess the occurrence, migration, and potential transport of PFAS and other landfill-related constituents within the surrounding hydrogeologic system. The investigation integrated landfill engineering, construction quality assurance, hydrogeology, groundwater monitoring, environmental chemistry, contaminant fate and transport, statistical analysis, and regulatory evaluation to develop a scientifically supported understanding of contaminant behavior over the operational life of the facility. Rather than relying on a single source of information, multiple independent lines of scientific evidence were synthesized using a weight-of-evidence approach to characterize landfill performance and evaluate potential environmental impacts (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 planning, design, construction, expansion, and operational history. Construction Quality Assurance (CQA) documentation was evaluated to verify that engineered containment systems were constructed in accordance with applicable design specifications and regulatory requirements. Particular emphasis was placed on the installation and verification of composite liner systems, geosynthetic materials, leachate collection infrastructure, protective cover systems, and associated quality assurance testing. Laboratory testing, field density testing, seam integrity verification, permeability testing, and material conformance evaluations were reviewed to assess the integrity and long-term performance of engineered environmental controls (Koerner & Koerner, 2018; U.S. EPA, 2004).
Hydrogeologic evaluations were performed to characterize groundwater flow direction, hydraulic gradients, aquifer characteristics, recharge conditions, and potential contaminant migration pathways. Historical groundwater elevation measurements and potentiometric surface maps were reviewed to evaluate groundwater movement beneath and surrounding the landfill. Groundwater flow velocities were assessed using accepted hydrogeologic principles, incorporating hydraulic conductivity, effective porosity, and measured hydraulic gradients to better understand the potential movement of dissolved constituents within the subsurface. These evaluations were integrated with site geology and groundwater monitoring data to develop a conceptual hydrogeologic model describing contaminant transport processes (Freeze & Cherry, 1979; Fetter, 2018).
Long-term groundwater and surface water monitoring records were reviewed to evaluate environmental conditions surrounding the landfill. Historical analytical data from monitoring wells, surface water locations, and engineered drainage systems were assessed for regulated constituents, groundwater quality indicators, volatile organic compounds, metals, and other parameters commonly associated with municipal solid waste facilities. Statistical evaluations, including background comparisons and trend analyses, were incorporated to distinguish naturally occurring groundwater variability from statistically significant changes potentially associated with landfill operations. Where appropriate, data quality indicators, duplicate samples, laboratory qualifiers, and analytical uncertainty were also evaluated to ensure that observed trends reflected actual environmental conditions rather than sampling or laboratory variability (ASTM International, 2021; U.S. EPA, 2009).
Finally, engineering documentation, hydrogeologic analyses, groundwater monitoring results, environmental chemistry, statistical evaluations, landfill operational information, and peer-reviewed scientific literature were integrated into a comprehensive conceptual site model describing contaminant fate and transport throughout the engineered landfill system. By combining multiple scientific disciplines, the investigation evaluated landfill performance, contaminant migration, groundwater protection, and long-term environmental stewardship using accepted environmental forensic methodologies. This multidisciplinary approach provides a scientifically rigorous framework for evaluating landfill-related contamination, supporting environmental consulting, regulatory compliance, environmental due diligence, remediation planning, and expert witness investigations involving complex waste management facilities (National Academies of Sciences, Engineering, and Medicine, 2022; ASTM International, 2021).
Results
The environmental forensic investigation demonstrated that multiple independent lines of scientific evidence supported the conclusion that the engineered landfill containment systems were functioning as intended while providing long-term protection of surrounding groundwater resources. Evaluation of construction quality assurance documentation, groundwater monitoring records, hydrogeologic analyses, statistical evaluations, and environmental chemistry data indicated that the landfill’s engineered barriers, leachate management infrastructure, and groundwater monitoring program collectively provided a comprehensive system for identifying and controlling potential contaminant migration. Rather than relying on individual monitoring results, the investigation integrated engineering and environmental datasets to evaluate the long-term environmental performance of the facility using a weight-of-evidence approach (U.S. Environmental Protection Agency [EPA], 2024; ASTM International, 2021).
Review of construction quality assurance documentation demonstrated that critical components of the landfill containment system—including composite liner systems, geosynthetic materials, leachate collection infrastructure, and protective cover systems—were subjected to extensive laboratory testing, field verification, and quality assurance inspections during construction. Material conformance testing, seam integrity evaluations, permeability testing, and construction verification procedures provided multiple independent measures of quality control designed to ensure that the engineered containment systems satisfied applicable performance specifications. These engineering evaluations provide an important foundation for environmental forensic investigations because the long-term environmental behavior of landfill-related contaminants depends heavily upon the integrity of these engineered barriers (Koerner & Koerner, 2018; U.S. EPA, 2004).
Hydrogeologic evaluations demonstrated that groundwater flow conditions remained consistent with historical monitoring data and established site hydrogeology. Groundwater elevations, hydraulic gradients, and potentiometric surface interpretations indicated stable groundwater flow patterns, allowing the monitoring network to effectively evaluate both background water quality and potential downgradient changes over time. The investigation found that integrating groundwater elevation data with long-term monitoring records substantially improved interpretation of groundwater quality trends by placing analytical results within an appropriate hydrogeologic framework rather than evaluating individual sample results in isolation (Freeze & Cherry, 1979; Fetter, 2018).
Long-term groundwater monitoring results indicated that the majority of monitored constituents remained consistent with historical conditions and expected natural variability. Statistical evaluations identified isolated groundwater parameters requiring additional review; however, evaluation of historical trends, background concentrations, laboratory quality assurance information, duplicate sample results, and hydrogeologic conditions demonstrated the importance of distinguishing naturally occurring geochemical variability and analytical uncertainty from meaningful evidence of contaminant migration. This investigation highlighted that statistically significant changes do not necessarily indicate environmental releases and must always be interpreted within the broader context of groundwater chemistry, sampling quality, historical monitoring records, and site-specific hydrogeologic conditions (U.S. EPA, 2009; ASTM International, 2021).
The investigation further demonstrated the importance of integrating landfill engineering with long-term environmental monitoring when evaluating persistent contaminants such as PFAS. While PFAS have become an increasing focus of environmental investigations because of their persistence and mobility, evaluating potential migration requires consideration of engineered containment systems, leachate management, groundwater flow characteristics, environmental chemistry, and contaminant fate and transport as interconnected processes rather than isolated disciplines. By combining engineering documentation, groundwater monitoring data, statistical analyses, hydrogeologic evaluations, and environmental chemistry within a multidisciplinary environmental forensic framework, the investigation developed a scientifically robust assessment of landfill performance and long-term groundwater protection. This integrated approach provides a reliable scientific foundation for environmental consulting, regulatory investigations, environmental due diligence, remediation planning, and expert witness evaluations involving engineered waste management facilities (National Academies of Sciences, Engineering, and Medicine, 2022; Interstate Technology & Regulatory Council [ITRC], 2024).
Conclusions
This environmental forensic investigation demonstrated the importance of evaluating engineered municipal solid waste landfills using a multidisciplinary scientific framework that integrates landfill engineering, hydrogeology, environmental chemistry, groundwater monitoring, construction quality assurance, statistical analysis, and contaminant fate and transport. Long-term environmental performance cannot be accurately assessed using groundwater monitoring data alone. Instead, a scientifically defensible evaluation requires consideration of engineered containment systems, hydrogeologic conditions, environmental monitoring trends, construction documentation, and regulatory requirements to understand how contaminants may behave throughout the operational life of a landfill. By integrating these independent lines of evidence, the investigation developed a comprehensive conceptual model describing landfill performance and long-term groundwater protection (U.S. Environmental Protection Agency [EPA], 2024; ASTM International, 2021).
The investigation demonstrated that properly designed and constructed engineered containment systems—including composite liner systems, geosynthetic barriers, leachate collection infrastructure, protective cover systems, and groundwater monitoring networks—provide multiple layers of environmental protection that substantially reduce the potential for contaminant migration. Equally important, the investigation illustrated that Construction Quality Assurance (CQA) documentation serves as a critical component of environmental forensic investigations because it verifies that these engineered systems were installed in accordance with applicable design specifications and performance requirements. Evaluating both engineering performance and long-term environmental monitoring provides greater confidence in assessing landfill integrity than relying upon either discipline independently (Koerner & Koerner, 2018; U.S. EPA, 2004).
The investigation further demonstrated that interpretation of groundwater monitoring data requires careful consideration of natural hydrogeologic variability, groundwater flow conditions, historical analytical trends, and data quality. Statistical exceedances or isolated analytical detections should not automatically be interpreted as evidence of contaminant migration without evaluating background groundwater chemistry, laboratory quality assurance, sampling variability, and site-specific hydrogeologic conditions. Integrating statistical analyses with environmental chemistry and hydrogeologic interpretation allows environmental professionals to distinguish naturally occurring groundwater conditions from meaningful environmental changes while improving confidence in source attribution and long-term environmental assessments (Freeze & Cherry, 1979; U.S. EPA, 2009).
This case study highlights the growing importance of multidisciplinary environmental forensic investigations in evaluating engineered waste management facilities and emerging contaminants such as PFAS. By combining landfill engineering, hydrogeology, groundwater monitoring, environmental chemistry, contaminant fate and transport, statistical evaluation, and exposure science, RoseyFields provides scientifically rigorous assessments that support environmental consulting, regulatory investigations, remediation planning, environmental due diligence, and expert witness services. Integrating engineering documentation with long-term environmental monitoring produces a comprehensive understanding of landfill performance and environmental protection while providing objective, evidence-based evaluations consistent with accepted scientific principles and current environmental regulations (National Academies of Sciences, Engineering, and Medicine, 2022; Interstate Technology & Regulatory Council [ITRC], 2024).
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and environmental forensic expert with extensive experience in landfill contamination investigations, PFAS assessments, groundwater monitoring interpretation, hydrogeologic analysis, contaminant fate and transport, and long-term environmental performance evaluation of engineered waste management facilities. Dr. Rosenfeld’s work focuses on complex environmental contamination matters involving municipal solid waste landfills, PFAS in groundwater and leachate, construction quality assurance (CQA), landfill engineering performance, source attribution, statistical interpretation of environmental monitoring data, and the evaluation of complete source-to-receptor pathways affecting soil, groundwater, surface water, and surrounding communities. His expertise includes integrating landfill engineering, hydrogeology, environmental chemistry, groundwater monitoring, statistical analysis, exposure assessment, toxicology, and regulatory science to determine whether engineered containment systems and long-term environmental data are consistent with contaminant migration, landfill integrity, and environmental protection objectives. 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, landfill engineering performance, and long-term environmental and human health risks associated with persistent contaminants and complex waste disposal operations.
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