Environmental Forensic Investigation and Technical Evaluation of Historical Municipal Waste Incineration, Air Dispersion Modeling, Contaminant Transport, and Human Exposure Assessment
Project Overview
This investigation involved a comprehensive environmental forensic evaluation of historical municipal waste incineration operations and the potential environmental transport of combustion byproducts into nearby residential areas. The review incorporated historical operational records, engineering analyses, technical reports, environmental sampling data, air dispersion modeling, contaminant transport evaluations, exposure calculations, geographic analyses, and supporting scientific literature to reconstruct historical environmental conditions and evaluate potential pathways through which combustion-derived contaminants may have affected surrounding communities. The investigation emphasized integration of multiple independent technical data sources to develop a scientifically defensible reconstruction of historical emissions and environmental conditions.
Rather than relying on any single dataset, the investigation evaluated historical facility operations, emissions generation, contaminant deposition, environmental sampling results, toxicological information, and environmental modeling collectively. This multidisciplinary approach allowed historical operational practices, contaminant fate and transport, and environmental exposures to be evaluated using accepted principles of environmental engineering, atmospheric science, contaminant transport, and environmental forensics. Review of multiple independent technical records also provided opportunities to compare assumptions, identify consistencies among datasets, and evaluate uncertainties inherent in reconstructing historical environmental conditions several decades after facility operations had ceased.
The investigation further evaluated the relationship between historical emissions, airborne particulate transport, environmental deposition, soil contamination, and long-term human exposure. Air dispersion modeling, geographic information system (GIS) analyses, contaminant concentration data, historical meteorological information, environmental sampling results, and exposure assessment methodologies were integrated to develop a technically supported understanding of historical contaminant migration and potential environmental impacts associated with municipal waste combustion activities.
Chemicals of Concern
The investigation focused on contaminants commonly associated with historical municipal solid waste incineration, particularly those capable of partitioning onto airborne fly ash particles and persisting within environmental media following deposition. Primary chemicals evaluated included dioxins and furans, arsenic, lead, and other combustion-related constituents historically identified within municipal waste incinerator emissions. These contaminants were selected because of their documented occurrence within fly ash, environmental persistence, toxicological significance, and potential to accumulate within soils following long-term atmospheric deposition.
Evaluation of contaminant concentrations incorporated published field investigations characterizing fly ash generated by municipal solid waste incinerators. Literature describing measured concentrations of arsenic, lead, and dioxins within fly ash was reviewed to establish representative contaminant ranges and conservative modeling inputs. Because many available field studies evaluated more modern municipal waste incinerators equipped with improved combustion controls and emissions technologies, conservative concentration assumptions were considered appropriate for evaluating historical operations that occurred before implementation of many modern air pollution control practices.
The investigation also considered the formation mechanisms of chlorinated organic compounds during combustion. Scientific literature describing precursor formation pathways, de novo synthesis mechanisms, combustion chemistry, and historical waste composition was reviewed to evaluate the environmental significance of dioxin formation during municipal waste incineration. Consideration was also given to historical changes in municipal waste composition, including increased use of chlorinated materials and plastics during portions of the operational period, as well as the potential contribution of other chlorine-containing wastes to combustion-generated contaminants.
In addition to chemical-specific evaluations, the investigation considered the physical behavior of particulate matter generated during combustion. Fly ash serves as an effective transport medium for metals and semi-volatile organic contaminants, allowing contaminants adsorbed to particle surfaces to remain suspended in the atmosphere before depositing onto surrounding soils. Understanding this relationship between particulate emissions and contaminant transport was an important component of reconstructing historical environmental conditions.
Methods
The investigation was conducted using established principles of environmental forensics, environmental engineering, atmospheric dispersion modeling, contaminant fate and transport, geographic information systems, and historical records reconstruction. Multiple categories of historical documentation—including engineering reports, technical presentations, environmental sampling results, deposition testimony, historical aerial imagery, emissions calculations, contaminant concentration datasets, and supporting scientific literature—were evaluated as an integrated body of evidence rather than as isolated documents.
Historical facility operations were reconstructed through review of operational documentation describing waste acceptance practices, combustion operations, facility configuration, historical engineering information, and available operational assumptions. Where complete historical operating records were unavailable, accepted engineering assumptions supported by historical documentation and published literature were utilized to reconstruct representative operating conditions. This methodology reflects common environmental forensic practice when evaluating historical industrial activities that predate modern environmental recordkeeping.
Atmospheric transport of combustion emissions was evaluated using AERMOD, the regulatory air dispersion model recommended by the U.S. Environmental Protection Agency for estimating atmospheric transport from stationary emission sources. Air modeling incorporated representative source parameters, historical meteorological information, terrain data, receptor networks, and emissions estimates to characterize potential airborne transport and long-term deposition of fly ash over surrounding residential areas. Geographic analyses were subsequently used to visualize modeled deposition patterns and evaluate the spatial distribution of contaminants over the modeled study area.
Environmental sampling information was reviewed alongside modeled deposition results to compare predicted contaminant distributions with measured soil concentrations. This comparison provided an independent line of evidence supporting evaluation of historical contaminant migration and long-term environmental persistence. Contaminant concentration data for arsenic, lead, and dioxins were incorporated into exposure calculations using multiple conservative exposure scenarios to evaluate potential variability associated with ingestion assumptions and environmental concentrations.
Exposure assessment methods incorporated accepted U.S. Environmental Protection Agency exposure assumptions, residential exposure durations, ingestion rates, contaminant concentrations, and toxicity-based screening concepts. Multiple scenarios were evaluated to characterize a range of potential lifetime exposures while accounting for uncertainties associated with historical environmental reconstruction. Conservative assumptions were intentionally selected where appropriate to minimize the likelihood of underestimating potential historical exposures.
Published toxicological literature, environmental chemistry references, regulatory guidance, and peer-reviewed scientific publications were also reviewed to evaluate contaminant persistence, transport mechanisms, degradation processes, and potential exposure pathways. Integration of engineering analyses, environmental sampling, modeling, and toxicological evaluation provided a comprehensive framework for environmental forensic interpretation.
Results
The collective body of historical documentation demonstrates that reconstruction of historical emissions is achievable through integration of engineering analyses, environmental records, environmental sampling, and atmospheric dispersion modeling. While individual records each contain inherent limitations, collectively they provide complementary lines of technical evidence that strengthen interpretation of historical environmental conditions and contaminant transport.
Review of the available information indicates that combustion-generated fly ash represents an important transport mechanism for combustion-related contaminants. Metals and chlorinated organic compounds associated with fly ash have the potential to remain airborne before depositing onto surrounding environmental surfaces, thereby creating long-term reservoirs of contaminants within surface soils. Historical deposition modeling, combined with environmental sampling information, provides a technically reasonable framework for evaluating cumulative contaminant accumulation over extended operational periods.
Evaluation of published fly ash concentration data further demonstrates that contaminant concentrations within combustion-derived particulate matter may vary considerably depending upon waste composition, combustion conditions, pollution control technologies, and operational practices. Review of the literature supports the conclusion that conservative contaminant concentration assumptions are appropriate when reconstructing historical emissions from older municipal waste incinerators that operated prior to implementation of modern emissions controls.
The investigation also demonstrates the value of integrating environmental sampling with atmospheric dispersion modeling. Air modeling identifies potential areas of long-term deposition based upon source characteristics and meteorological conditions, whereas environmental sampling provides independent observational evidence regarding contaminant distributions that may persist following decades of environmental weathering. Consideration of both modeled and measured information provides substantially greater confidence than either approach considered independently.
Exposure assessment results demonstrate that evaluation of historical environmental conditions benefits from consideration of multiple exposure scenarios reflecting different environmental concentrations and human exposure assumptions. Use of several independent scenarios allows uncertainty associated with historical reconstruction to be characterized while avoiding reliance upon any single assumption regarding contaminant concentrations or exposure behaviors.
More broadly, the reviewed materials illustrate the multidisciplinary nature of environmental forensic investigations. Historical aerial imagery, engineering analyses, environmental chemistry, contaminant transport modeling, GIS analyses, toxicology, environmental sampling, exposure assessment, and scientific literature each contribute unique information regarding historical environmental conditions. Integration of these disciplines provides a technically robust basis for evaluating historical emissions and their potential environmental significance.
Conclusions
The materials reviewed during this investigation demonstrate that historical municipal waste incineration can be evaluated using a multidisciplinary environmental forensic approach that integrates engineering analyses, atmospheric dispersion modeling, environmental sampling, contaminant fate and transport, historical documentation, and exposure assessment. Collectively, these independent technical disciplines provide a scientifically defensible framework for reconstructing historical environmental conditions and evaluating potential contaminant migration.
The investigation further illustrates the importance of evaluating contaminants within the broader context of particulate transport, historical operational practices, environmental persistence, and long-term deposition. Consideration of multiple independent sources of information reduces uncertainty associated with historical reconstruction while providing a more comprehensive understanding of historical environmental conditions than reliance upon any single dataset.
Environmental forensic investigations involving historical industrial operations frequently require synthesis of incomplete historical records, modern scientific understanding, environmental measurements, engineering calculations, and accepted modeling methodologies. When these independent sources are evaluated collectively, they provide a technically appropriate basis for reconstructing historical environmental conditions and assessing contaminant fate and transport over extended periods.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and environmental forensic expert with experience in environmental contamination assessment, contaminant fate and transport, atmospheric dispersion modeling, historical site reconstruction, exposure evaluation, regulatory review, and technical causation analysis. Through RoseyFields LLC, Dr. Rosenfeld provides environmental forensic investigations, contaminant source evaluations, historical records analysis, environmental compliance assessments, regulatory review, and expert consulting services involving complex environmental conditions and historical industrial operations.
References
Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Arsenic.
Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Lead.
Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Chlorinated Dibenzo-p-Dioxins.
Fiedler, H. (2003). Dioxins and Furans (PCDD/PCDF). In The Handbook of Environmental Chemistry.
Thompson, R. C., Swan, S. H., Moore, C. J., & Vom Saal, F. S. (2009). Our Plastic Age. Philosophical Transactions of the Royal Society B.
U.S. Environmental Protection Agency. AERMOD Implementation Guide.
U.S. Environmental Protection Agency. Exposure Factors Handbook (2011 Edition).
U.S. Environmental Protection Agency. (2006). An Inventory of Sources and Environmental Releases of Dioxin-Like Compounds in the United States.
Werther, J., & Ogada, T. (1999). Sewage Sludge Combustion. Progress in Energy and Combustion Science, 25(1), 55–116.