Environmental Forensic Investigation of PFAS Contamination, Environmental Remediation, and CERCLA Cost Evaluation at an Industrial Facility
Project Overview
Per- and polyfluoroalkyl substances (PFAS) have become one of the most significant environmental contaminants facing regulators, property owners, and environmental professionals. Historically, aqueous film-forming foam (AFFF) used for firefighting and emergency response was widely deployed at airports, military installations, aviation facilities, and industrial fire-training areas. Repeated use, equipment testing, storage, and accidental releases have resulted in persistent contamination of soil, groundwater, and, in some cases, nearby surface waters. Because PFAS are highly resistant to chemical and biological degradation, these compounds can remain in the environment for decades, creating complex environmental challenges that require multidisciplinary forensic investigation, human health risk assessment, and remediation planning.
This environmental forensic investigation evaluated historical PFAS contamination at a large aviation support facility where AFFF had been used during routine firefighting operations and emergency response activities over several decades. Rather than focusing solely on identifying contamination, the investigation sought to determine the nature and extent of PFAS impacts, evaluate contaminant migration within soil and groundwater, assess remediation alternatives, and develop scientifically defensible cost estimates for potential cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The investigation integrated environmental sampling data, historical operational records, regulatory guidance, engineering analyses, aerial imagery, geographic information systems (GIS), remediation technologies, and published scientific literature to develop a comprehensive understanding of site conditions.
A principal objective was to determine how historical AFFF use influenced the distribution of PFAS within multiple environmental media and how evolving regulatory standards affected remediation planning. The investigation compared historical and current risk-based screening criteria, evaluated soil and groundwater sampling results, reconstructed likely release areas, and identified portions of the facility requiring additional investigation or potential remediation. Engineering analyses were then used to estimate the technical feasibility, advantages, limitations, and costs of several remedial approaches, including excavation, thermal destruction, landfill disposal, and long-term groundwater treatment.
Because PFAS investigations frequently involve both environmental science and engineering, this project integrated environmental chemistry, contaminant fate and transport, hydrogeology, remediation engineering, regulatory compliance, and environmental data analysis into a unified environmental forensic evaluation. By combining historical site reconstruction with quantitative remediation planning and risk-based decision making, the investigation illustrates how modern environmental consulting supports CERCLA investigations, environmental due diligence, remediation cost estimation, regulatory negotiations, and environmental litigation while maintaining a rigorous, evidence-based scientific approach.
Chemicals of Concern
The primary chemicals evaluated during this environmental forensic investigation were per- and polyfluoroalkyl substances (PFAS) associated with historical use of aqueous film-forming foam (AFFF) at aviation facilities. PFAS comprise a large family of synthetic fluorinated compounds that have been widely used because of their resistance to heat, water, oils, and chemical degradation. While these properties make PFAS highly effective in firefighting foams, they also result in exceptional environmental persistence. Many PFAS do not readily degrade under natural environmental conditions, allowing them to remain in soil, groundwater, sediments, and surface water for decades while migrating considerable distances from their original release locations. Their persistence, combined with increasing evidence of human health effects, has made PFAS one of the highest-priority contaminant groups addressed under modern environmental investigation and remediation programs.
The investigation primarily focused on perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), the two PFAS compounds historically associated with legacy AFFF formulations. These compounds were repeatedly identified in soil and groundwater sampling data and served as the principal contaminants used to evaluate the extent of environmental impacts. Because PFOS and PFOA are highly mobile in groundwater and resistant to natural degradation, they are commonly used as indicator compounds when investigating historical AFFF releases. Toxicological research has linked long-term exposure to PFOS and PFOA with adverse health outcomes, including developmental effects, immune system suppression, elevated cholesterol, thyroid disease, kidney cancer, and testicular cancer, prompting increasingly stringent federal drinking water standards and risk-based screening levels.
Additional PFAS compounds identified during the investigation included perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), and perfluorononanoic acid (PFNA). Although these compounds generally occurred at lower concentrations than PFOS and PFOA, they provided important information regarding the composition of historical AFFF releases and the environmental distribution of PFAS across the facility. Their detection in both soil and groundwater demonstrated that contamination involved a mixture of fluorinated compounds rather than a single chemical, requiring a comprehensive evaluation of contaminant fate, transport, and cumulative exposure pathways.
The investigation also evaluated the influence of evolving regulatory standards on environmental interpretation. During the review period, federal risk-based screening levels for several PFAS compounds became substantially more protective, resulting in a greater number of sampling locations exceeding current residential and industrial screening criteria. This demonstrated that environmental investigations involving PFAS must account for changing toxicological science and regulatory guidance, as contaminant concentrations previously considered acceptable may warrant additional investigation or remediation under updated standards. (Regional Screening Level Comparison; DoD Cleanup Guidance).
Because PFAS contamination often affects multiple environmental media simultaneously, investigators evaluated soil contamination, groundwater migration, contaminant persistence, and potential human exposure as interconnected components of a single environmental system. Integrating environmental chemistry with hydrogeology, contaminant fate and transport, and current toxicological knowledge provided the scientific framework necessary to support remediation planning, CERCLA investigations, environmental due diligence, regulatory compliance, and environmental forensic source attribution.
Methods
This environmental forensic investigation employed a multidisciplinary methodology integrating historical document review, environmental chemistry, regulatory analysis, site characterization, geographic information systems (GIS), environmental sampling review, contaminant fate and transport evaluation, remediation engineering, cost estimation, and human health risk assessment. Because historical PFAS releases occurred over several decades, investigators synthesized operational records, environmental investigations, regulatory guidance, engineering literature, and published scientific research to reconstruct site history, characterize contaminant distribution, and evaluate practical remediation alternatives. This multiple-lines-of-evidence approach provided a technically robust framework for assessing both environmental impacts and potential cleanup strategies.
The investigation began with a review of historical facility operations, firefighting practices, environmental reports, and publicly available regulatory records to identify areas where AFFF had been stored, tested, or discharged. Historical site plans, aerial imagery, engineering drawings, and GIS mapping were used to delineate areas of potential environmental concern and estimate the extent of impacted properties. This historical reconstruction established the basis for evaluating contaminant migration and prioritizing areas for additional investigation or remediation.
Environmental sampling data were reviewed to evaluate PFAS occurrence within both soil and groundwater. Investigators compared reported analytical results with applicable U.S. Environmental Protection Agency and Department of Defense risk-based screening criteria, including recently updated residential and industrial screening levels. Evaluating sampling results under both historical and current regulatory thresholds allowed investigators to assess how evolving toxicological guidance influenced the interpretation of site conditions and potential remedial needs.
Engineering analyses focused on identifying practical remediation strategies for PFAS-impacted media. Published EPA guidance and engineering literature were reviewed to evaluate technologies including excavation, off-site disposal, ex-situ thermal treatment, hazardous waste combustion, groundwater pump-and-treat systems using granular activated carbon (GAC), and long-term containment approaches. Each technology was evaluated with respect to treatment effectiveness, implementation requirements, regulatory considerations, operational limitations, and anticipated long-term performance.
A remediation cost analysis was then performed by combining mapped treatment areas, estimated excavation depths, published unit costs, and anticipated disposal or treatment requirements. Multiple remediation scenarios were developed to evaluate alternatives ranging from targeted excavation of localized source areas to broader site-wide remediation. Estimating costs under several engineering assumptions provided a practical framework for understanding the potential magnitude of remediation while recognizing that final cleanup designs would require additional site-specific investigation and regulatory review.
Finally, the investigation integrated environmental chemistry, site characterization, contaminant fate and transport, remediation engineering, regulatory guidance, and cost evaluation into a comprehensive environmental forensic assessment. By combining historical reconstruction with current environmental data and accepted engineering methodologies, the investigation developed a scientifically defensible framework capable of supporting CERCLA response planning, environmental due diligence, remediation design, regulatory decision-making, and expert witness evaluations involving historical PFAS contamination at aviation and firefighting facilities.
Results
The environmental forensic investigation demonstrated that historical use of aqueous film-forming foam (AFFF) represented the primary mechanism for PFAS releases at the aviation support facility. Review of historical operational records, environmental investigations, and site characterization reports identified multiple areas where firefighting foam had been stored, tested, handled, or discharged during routine operations. Soil and groundwater investigations consistently detected PFAS within these operational areas, indicating that repeated releases over several decades contributed to long-term environmental contamination rather than a single isolated event. This historical reconstruction established a logical relationship between documented facility activities and the observed distribution of PFAS in environmental media.
Environmental sampling demonstrated that PFOS and PFOA were the predominant contaminants detected within both soil and groundwater, with additional detections of PFHxS, PFBS, and PFNA. Surface soils generally exhibited the greatest concentrations, consistent with repeated AFFF application and infiltration from historical operational areas. Groundwater monitoring further demonstrated that PFAS had migrated beneath portions of the facility, confirming that contaminant transport extended beyond surface soils. The investigation also found that application of updated EPA Regional Screening Levels substantially increased the number of locations exceeding residential and industrial risk-based criteria, illustrating how evolving toxicological guidance can significantly influence site characterization and remediation priorities.
Evaluation of contaminant fate and transport indicated that PFAS migration was controlled by the compounds’ high water solubility, environmental persistence, and resistance to natural degradation. Unlike many petroleum hydrocarbons or chlorinated solvents, PFAS do not readily degrade through biological or chemical processes, allowing contaminants to migrate through soil and groundwater while remaining chemically stable for extended periods. The investigation therefore concluded that both soil and groundwater required consideration during remediation planning because untreated source areas could continue contributing contaminants to underlying groundwater over time.
Engineering evaluation demonstrated that no single remediation technology was universally applicable across the entire facility. Ex-situ thermal treatment offered the advantage of destroying PFAS compounds, whereas excavation and secure disposal provided rapid removal of contaminated source materials but transferred contaminants to long-term waste management facilities. Groundwater remediation using granular activated carbon (GAC) pump-and-treat systems was identified as an effective long-term management strategy for dissolved PFAS but would likely require extended operational periods because of the persistence and mobility of these compounds. Consequently, investigators concluded that successful remediation would likely require a combination of technologies tailored to site-specific conditions rather than reliance upon a single remedial approach.
The remediation cost evaluation further demonstrated that cleanup costs varied substantially depending upon the extent of impacted soil, selected treatment technology, and disposal strategy. Engineering analyses compared several remediation scenarios ranging from targeted treatment of localized source areas to more comprehensive excavation of affected portions of the facility. These comparisons illustrated that remediation planning must balance technical effectiveness, regulatory objectives, long-term environmental protection, and overall project cost. Developing multiple remediation scenarios provided decision-makers with a practical framework for evaluating cleanup alternatives under CERCLA and related environmental programs.
Overall, the investigation demonstrated the value of integrating historical reconstruction, environmental sampling, regulatory evaluation, engineering analysis, and remediation planning into a single environmental forensic assessment. Rather than relying solely on contaminant concentrations, investigators synthesized operational history, environmental chemistry, contaminant fate and transport, updated screening criteria, and engineering cost analyses to objectively characterize site conditions and evaluate feasible remediation strategies. This multidisciplinary approach provides a scientifically defensible framework for environmental consulting, CERCLA investigations, remediation planning, regulatory negotiations, and expert witness testimony involving historical PFAS contamination at aviation facilities.
Conclusions
This environmental forensic investigation demonstrates that evaluating historical PFAS contamination associated with firefighting activities requires a multidisciplinary scientific approach integrating environmental chemistry, site characterization, contaminant fate and transport, remediation engineering, and regulatory risk assessment. Because PFAS are highly persistent and readily migrate through soil and groundwater, understanding both historical release mechanisms and long-term environmental behavior is essential for accurately characterizing contamination and developing effective remediation strategies. By combining historical operational information with environmental sampling, engineering analyses, and current regulatory guidance, the investigation provided an objective scientific framework for evaluating the extent of contamination and supporting future environmental decision-making.
The investigation also demonstrated the importance of integrating historical site reconstruction with contemporary regulatory criteria. Updated federal screening levels for PFAS significantly changed the interpretation of environmental sampling results, increasing the number of areas requiring further evaluation or potential remediation. This finding highlights the rapidly evolving regulatory landscape surrounding PFAS and illustrates why environmental investigations should be periodically reevaluated as toxicological research and risk assessment methodologies continue to advance.
Another important finding was that remediation planning must address both source materials and groundwater impacts. Soil excavation or treatment alone may not fully address long-term environmental risks where PFAS have migrated into groundwater, while groundwater treatment without addressing contaminated source areas may allow continued contaminant loading. Evaluating multiple remedial technologies—including excavation, thermal destruction, engineered disposal, and groundwater treatment—demonstrated that successful cleanup strategies are often most effective when implemented as integrated remediation programs tailored to site-specific conditions.
More broadly, this investigation illustrates how modern environmental forensic investigations combine environmental consulting, environmental chemistry, contaminant fate and transport, remediation engineering, regulatory compliance, GIS analysis, cost estimation, and human health risk assessment to evaluate complex PFAS contamination. Integrating environmental data with engineering analyses and current scientific guidance provides a technically rigorous framework for supporting CERCLA investigations, environmental due diligence, remediation planning, regulatory negotiations, and expert witness testimony. As PFAS regulations continue to evolve and additional contaminated sites are identified, multidisciplinary environmental forensic investigations will remain critical for developing scientifically defensible, cost-effective, and protective remediation strategies.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and environmental forensic expert with extensive experience in environmental exposure assessment, toxicology, air quality, environmental fate and transport, risk assessment, and environmental forensics. Through RoseyFields LLC, Dr. Rosenfeld provides scientific consulting, environmental forensic analysis, regulatory support, and expert witness services involving environmental contamination, human exposure, and public health. His technical oversight helped ensure that the methodologies, scientific interpretations, and conclusions presented in this case study are consistent with accepted scientific principles and current best practices.