Environmental Forensic Investigation of Petroleum Hydrocarbon Contamination in a Drinking Water Distribution System Following a Major Fuel Release
Project Overview
Environmental forensic investigations involving petroleum contamination of public drinking water systems require the integration of environmental chemistry, contaminant fate and transport, hydraulic engineering, exposure assessment, environmental data analysis, and historical reconstruction. Unlike conventional groundwater investigations, contamination within a potable water distribution system must account for groundwater production wells, storage reservoirs, booster pumps, pressure zones, water distribution infrastructure, operational flushing, and changing hydraulic conditions that influence contaminant transport. These investigations are conducted to reconstruct historical releases, identify contaminant migration pathways, evaluate human exposure, and determine whether environmental monitoring data remain scientifically consistent with the documented release history.
This environmental forensic investigation evaluated a large petroleum fuel release associated with a fuel storage and distribution facility that contaminated an interconnected potable water distribution system. According to the investigative record, an initial fuel transfer incident released thousands of gallons of JP-5 aviation fuel into a fire suppression system. Months later, damage to the fire suppression piping released the remaining fuel into the environment, allowing petroleum hydrocarbons to migrate into a groundwater production well supplying the drinking water system. Before the contaminated well was removed from service, fuel-impacted water was distributed throughout multiple service areas within the potable water network.
The investigation documented that residents began reporting petroleum odors, chemical tastes, and fuel sheens in their household water shortly after contaminated groundwater entered the distribution system. Emergency response activities included shutting down the affected groundwater source, issuing public health advisories, providing alternative drinking water supplies, and implementing an extensive flushing program designed to remove petroleum hydrocarbons from the distribution network. Despite these corrective actions, analytical monitoring demonstrated continued detections of petroleum hydrocarbons throughout portions of the distribution system for well over one year following the release, raising important scientific questions regarding contaminant persistence, source attribution, and historical exposure.
The principal objective of the environmental forensic investigation was not simply to document contamination, but to determine why measurable petroleum hydrocarbons continued to be detected during long-term monitoring. To answer this question, investigators integrated historical operational records, engineering evaluations of the water distribution system, long-term analytical monitoring data, petroleum fingerprinting, contaminant fate and transport principles, exposure assessment, and published technical literature regarding jet fuel degradation and drinking water biofilms. Rather than relying upon a single dataset, each independent line of evidence was evaluated collectively to determine whether observed monitoring results remained scientifically consistent with the documented release and expected environmental behavior of JP-5 aviation fuel.
Long-term monitoring data formed one of the most important components of the investigation. The analytical database documented approximately 1,355 detections of diesel-range petroleum hydrocarbons (TPH-d) throughout the affected distribution system between March 2022 and May 2023. Monitoring results demonstrated petroleum hydrocarbon detections throughout essentially every flushing zone, with average concentrations generally ranging from approximately 55 to 63 µg/L. Perhaps most significantly, TPH-d remained detectable approximately 450 to 500 days following the original release, including multiple residential sampling locations within one of the most heavily impacted service areas. These observations became a central focus of the forensic evaluation because they required scientific explanation beyond the immediate emergency response period.
To explain these long-term detections, the investigation evaluated several competing hypotheses, including residual petroleum remaining within the distribution system, laboratory analytical artifacts, hydraulic redistribution, contaminant weathering, and microbial biofilm activity capable of retaining and subsequently releasing petroleum hydrocarbons. Each hypothesis was systematically compared against analytical chemistry, contaminant fingerprinting, engineering data, and published scientific literature to determine which mechanisms were most consistent with the observed environmental evidence. This multiple-lines-of-evidence approach represents the cornerstone of modern environmental forensic investigations because it allows complex contamination events to be reconstructed using independent scientific disciplines that collectively strengthen source attribution and historical exposure assessment.
Chemicals of Concern
The primary chemical of concern evaluated during this environmental forensic investigation was JP-5 aviation turbine fuel, a kerosene-based petroleum product composed predominantly of C9 through C16 hydrocarbons. Unlike individual hazardous substances, JP-5 is a complex mixture containing hundreds of aliphatic and aromatic hydrocarbons, including branched and linear paraffins, cycloalkanes (naphthenes), alkylbenzenes, and naphthalene compounds. The investigation noted that analytical techniques cannot identify every individual constituent within JP-5 because the fuel contains more than 1,000 separate molecular species. Instead, environmental investigations evaluate hydrocarbon distributions, chromatographic fingerprints, and petroleum hydrocarbon fractions to determine whether environmental samples remain consistent with weathered jet fuel.
Because JP-5 is a complex petroleum mixture, the investigation focused on total petroleum hydrocarbons (TPH), particularly diesel-range petroleum hydrocarbons (TPH-d), as one of the principal indicators of contamination. Review of the long-term monitoring database documented approximately 1,355 TPH-d detections throughout the drinking water distribution system between March 2022 and May 2023. Petroleum hydrocarbons were detected throughout essentially every flushing zone, with average concentrations generally ranging between approximately 55 and 63 µg/L. More importantly, TPH-d detections continued approximately 450 to 500 days after the original release, including numerous residential sampling locations, demonstrating that measurable petroleum hydrocarbons remained within portions of the drinking water system well beyond the emergency response period.
The investigation also reviewed additional petroleum-related analytes detected during routine drinking water monitoring, including gasoline-range hydrocarbons, oil-range hydrocarbons, benzo(a)pyrene, bis(2-ethylhexyl)phthalate, bromodichloromethane, 1,2-dichloroethene, 1,4-dichlorobenzene, and naphthalene. Rather than interpreting these compounds independently, investigators evaluated their occurrence collectively to understand contaminant distribution, environmental weathering, and potential human exposure. Summary tables prepared during the investigation documented hundreds of detections of petroleum hydrocarbons across the affected service area while also identifying recurring detections of several volatile and semivolatile organic compounds that contributed to the overall understanding of contaminant occurrence within the distribution system.
A critical component of the investigation involved understanding how JP-5 changes after entering a drinking water system. The technical review explained that certain petroleum constituents, particularly aromatic hydrocarbons such as benzene, toluene, and xylenes, are relatively soluble in water and may remain dissolved for extended periods under turbulent hydraulic conditions. Other hydrocarbons preferentially adsorb to pipe materials, partition into sediments or biofilms, volatilize, or undergo microbial degradation. Consequently, environmental samples collected months after a release are not expected to exhibit chromatograms identical to fresh fuel. Instead, investigators evaluated whether long-term analytical results remained consistent with the expected environmental weathering of JP-5, recognizing that degradation continuously alters hydrocarbon composition while preserving recognizable forensic fingerprint characteristics.
One of the central scientific questions addressed by the investigation was why low-level petroleum hydrocarbon detections continued after extensive flushing operations. The technical assessment systematically evaluated several competing explanations, including analytical laboratory challenges, residual fuel remaining within the distribution system, hydraulic redistribution, premise plumbing, pipe scale sloughing, source water changes, and microbial biofilm activity. After reviewing available monitoring data, engineering information, and published scientific literature, the investigation concluded that biofilm proliferation following the introduction of JP-5 represented one of the most scientifically plausible mechanisms capable of contributing to continued low-level TPH detections. The presentation notes that petroleum hydrocarbons provide an organic carbon source capable of supporting microbial growth and discusses how biofilms readily develop on the interior surfaces of drinking water pipes even in chlorinated systems.
Published literature reviewed during the investigation further explains that biofilms consist of microorganisms embedded within extracellular polymeric substances that adhere to pipe surfaces after formation of a conditioning film composed of proteins, carbohydrates, and other organic and inorganic molecules. These biofilms may retain petroleum hydrocarbons, support hydrocarbon-degrading microorganisms, and intermittently release hydrocarbons back into flowing water during hydraulic disturbances. Although the investigation acknowledged that additional bacteriological data would strengthen this hypothesis, the observed persistence of low-level TPH-d detections, together with published research describing hydrocarbon-degrading bacteria and biofilm development within potable water infrastructure, supported continued evaluation of biofilm-mediated contaminant persistence as part of the overall environmental forensic investigation.
Methods
The environmental forensic investigation employed a multidisciplinary methodology designed to reconstruct the petroleum release, evaluate contaminant migration throughout the drinking water distribution system, assess historical human exposure, and determine the most scientifically plausible explanation for persistent petroleum hydrocarbon detections observed during long-term monitoring. Rather than relying upon a single line of evidence, the investigation integrated historical operational records, environmental monitoring data, engineering analyses, contaminant fingerprinting, toxicological literature, laboratory analytical methods, exposure reconstruction, and environmental microbiology into a comprehensive multiple-lines-of-evidence evaluation. This approach allowed independent scientific disciplines to be compared for consistency while minimizing uncertainty associated with interpretation of any single dataset.
The investigation began with a detailed historical reconstruction of the release using operational records, incident reports, engineering documentation, and water system operating information. These records established the chronology of the release, identified the mechanism by which JP-5 entered the drinking water system, documented emergency response actions, and described the subsequent flushing operations implemented to restore water quality. Historical complaint records describing petroleum odors, tastes, and visible sheens were reviewed alongside distribution system operations to evaluate the timing and geographic progression of contamination throughout the affected service area.
Analytical chemistry represented another major component of the investigation. Thousands of drinking water analytical results were evaluated to characterize the occurrence, distribution, and persistence of petroleum hydrocarbons throughout the potable water system. Particular emphasis was placed on diesel-range petroleum hydrocarbons (TPH-d), gasoline-range hydrocarbons, oil-range hydrocarbons, and associated volatile and semivolatile organic compounds identified during routine monitoring. Rather than evaluating isolated analytical results, investigators examined long-term concentration trends, detection frequencies, geographic distribution, and recurring detections approximately 450 to 500 days following the release. Summary tables, distribution maps, and monitoring dashboards were used to identify contaminant patterns throughout multiple service zones and to compare observed concentrations following system flushing.
Petroleum fingerprinting formed one of the principal environmental forensic tools used during the investigation. The technical evaluation recognized that JP-5 is composed of more than one thousand individual hydrocarbons that weather continuously following environmental release. Rather than expecting environmental samples to match fresh fuel exactly, investigators evaluated chromatographic distributions, hydrocarbon carbon-number ranges, unresolved complex mixtures, and expected weathering patterns to determine whether long-term analytical results remained chemically consistent with the original fuel release. The investigation further reviewed published examples demonstrating chromatographic changes following petroleum degradation to evaluate whether observed analytical patterns reflected expected environmental transformation rather than an unrelated contaminant source.
Engineering analyses focused on contaminant fate and transport within the drinking water distribution system. Hydraulic conditions, groundwater production, system flushing, storage reservoirs, pressure zones, and water movement through interconnected distribution infrastructure were evaluated to determine how petroleum hydrocarbons migrated following the release. Because contamination occurred within an engineered water system rather than a natural groundwater aquifer, contaminant occurrence was interpreted within the context of distribution system hydraulics, mixing processes, and operational changes occurring throughout the response period. These engineering evaluations were integrated with environmental monitoring results to reconstruct contaminant migration and identify factors capable of influencing long-term contaminant persistence.
Finally, the investigation systematically evaluated competing scientific hypotheses capable of explaining continued low-level petroleum hydrocarbon detections during long-term monitoring. The technical assessment compared laboratory analytical challenges, residual fuel remaining within the distribution system, hydraulic redistribution, premise plumbing, pipe-scale sloughing, source water changes, water main disturbances, and microbial biofilm activity. Each hypothesis was assessed against the available analytical data, engineering information, published scientific literature, and environmental monitoring results. Rather than assuming a single explanation, investigators ranked each hypothesis according to its scientific plausibility and consistency with the available evidence, ultimately identifying biofilm proliferation following the introduction of petroleum hydrocarbons as one of the most scientifically plausible mechanisms warranting further evaluation. This structured, evidence-based approach exemplifies modern environmental forensic investigations by integrating environmental chemistry, engineering, microbiology, analytical chemistry, and historical reconstruction into a single scientifically defensible framework.
Results and Conclusions
The environmental forensic investigation demonstrated that the release of JP-5 aviation fuel resulted in measurable petroleum hydrocarbon contamination throughout multiple portions of the drinking water distribution system. Historical operational records, resident complaints, environmental monitoring data, and engineering evaluations consistently documented that petroleum-contaminated groundwater entered the potable water network prior to shutdown of the affected production well. Following distribution throughout the interconnected system, emergency response activities included source isolation, extensive flushing operations, and long-term environmental monitoring designed to evaluate the effectiveness of remediation and determine whether petroleum hydrocarbons persisted within the distribution infrastructure.
Long-term monitoring results became one of the most significant findings of the investigation. The analytical database documented approximately 1,355 detections of diesel-range petroleum hydrocarbons (TPH-d) collected between March 2022 and May 2023, with measurable concentrations identified throughout nearly every flushing zone. Average TPH-d concentrations remained relatively consistent, generally ranging between approximately 55 and 63 µg/L, indicating that contamination was broadly distributed throughout the hydraulic network rather than confined to isolated locations. Perhaps most notably, petroleum hydrocarbons remained detectable approximately 450 to 500 days after the original release, demonstrating that measurable petroleum constituents persisted well beyond the initial emergency response and flushing operations.
Petroleum fingerprinting and environmental chemistry further demonstrated that long-term analytical results remained consistent with the expected environmental behavior of weathered JP-5 aviation fuel. Rather than maintaining the chemical composition of fresh fuel, petroleum hydrocarbons were expected to undergo dissolution, volatilization, biodegradation, and other weathering processes that progressively altered chromatographic patterns over time. The investigation therefore interpreted analytical results within the context of these well-established environmental transformation processes, concluding that changes in hydrocarbon composition were scientifically consistent with weathered petroleum rather than evidence of a different contaminant source. Published examples of degraded jet fuel chromatograms reviewed during the investigation provided additional support for this interpretation.
A major focus of the investigation involved evaluating competing hypotheses to explain the persistence of low-level petroleum hydrocarbon detections following system flushing. Laboratory analytical artifacts, residual fuel remaining within the distribution system, premise plumbing, pipe-scale sloughing, source water changes, operational changes, water main disturbances, and microbial biofilm activity were each systematically evaluated against the available monitoring data and engineering information. Based on this comparative evaluation, the investigation concluded that several proposed explanations exhibited low or extremely low scientific likelihood, while laboratory analytical considerations and biofilm-related processes warranted the greatest continued technical evaluation. In particular, the investigation recognized that petroleum hydrocarbons could provide an organic carbon source capable of promoting microbial biofilm growth and that biofilms within potable water systems are capable of retaining and subsequently releasing hydrocarbons under changing hydraulic conditions.
Although the investigation acknowledged that additional microbiological characterization of the drinking water system would improve understanding of biofilm composition and hydrocarbon-degrading microorganisms, the available evidence demonstrated that contaminant persistence could not be explained solely by isolated analytical variability. Instead, the investigation emphasized that continued low-level petroleum detections should be interpreted using multiple independent lines of evidence, including analytical chemistry, petroleum fingerprinting, hydraulic engineering, environmental microbiology, and contaminant fate and transport. Integrating these scientific disciplines provided a more comprehensive and technically defensible interpretation than reliance upon any individual dataset alone.
Overall, this investigation illustrates the complexity of environmental forensic investigations involving petroleum contamination of public drinking water systems. Reconstructing historical exposure required considerably more than documenting analytical detections; it required integrating historical operations, engineering analyses, environmental chemistry, contaminant fingerprinting, exposure assessment, and environmental data analysis into a unified scientific framework. The resulting evaluation provided an objective assessment of contaminant migration, persistence, and potential exposure while demonstrating how multiple independent lines of evidence can be combined to support scientifically defensible source attribution and environmental decision-making. This multidisciplinary approach represents the foundation of modern environmental consulting and environmental forensic investigations involving complex petroleum contamination events.
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.