Dr. Andrew J.B. Cohen, PhD, PH, is an internationally recognized expert in groundwater hydrology with over 30 years of experience in forensic hydrogeology, contaminant fate and transport, site characterization, and litigation support. He specializes in groundwater contamination involving PFAS (including AFFF), 1,4-dioxane, petroleum hydrocarbons, and chlorinated solvents such as TCE and vinyl chloride. Dr. Cohen holds a PhD from UC Berkeley, served as a Research Associate at Lawrence Berkeley National Laboratory, and has taught university courses in Contaminant Hydrogeology and Environmental Hydrogeology. He supports legal teams with expert analysis, technical critiques, PRP identification, and causation evaluation across groundwater, soil, sediment, and surface water systems. Known for translating complex science into clear, defensible findings, Dr. Cohen also advises attorneys and responsible parties as a third-party reviewer to ensure environmental investigations are scientifically sound and legally strategic.

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Dr. Andrew J.B. Cohen, PhD, PH, is a Contaminant Hydrogeologist with over 30 years of experience in consulting, teaching, and research focused on the characterization, analysis, and remediation of contaminated groundwater. He holds a PhD in hydrogeology from the University of California, Berkeley, where he also served as a Research Associate at Lawrence Berkeley National Laboratory. Dr. Cohen has taught university courses in Contaminant Hydrogeology and Environmental Hydrogeology, and is the lead author of an internationally recognized peer-reviewed publication about groundwater fundamentals.

He is recognized as a groundwater contamination expert and provides litigation-focused technical support to law firms, companies, and regulatory stakeholders involved in complex environmental disputes. His expertise spans a wide range of contaminant classes, including per- and polyfluoroalkyl substances (PFAS) such as PFOA, PFOS, PFHxA, PFHxS, 6:2 fluorotelomer sulfonate (6:2 FTS), and AFFF (aqueous film-forming foam)—a significant PFAS source at airports, military facilities, and industrial sites due to its historical use in firefighting and fuel-based fire suppression. He also works extensively on cases involving other emerging contaminants such as 1,4-dioxane, as well as petroleum-related hydrocarbons and solvent-related compounds, including benzene, toluene, ethylbenzene, xylene (BTEX), trichloroethylene (TCE), tetrachloroethylene (PCE), and vinyl chloride.

Dr. Cohen provides forensic hydrogeology services to determine the source, timing, and extent of contamination in groundwater, soil, sediment, and surface water. He is particularly experienced in evaluating impacts to drinking water supplies—including private wells and public water supply systems—and in developing conceptual site models that accurately reflect contaminant behavior in both unconsolidated and fractured rock environments. In addition to human health exposure pathways, Dr. Cohen also evaluates ecological exposure pathways and potential risks to environmental receptors, including sediment-dwelling organisms and aquatic ecosystems impacted by contaminated surface water and sediment.

As an expert witness, Dr. Cohen prepares detailed expert reports, critiques of opposing expert opinions, and provides deposition and trial testimony. He supports legal teams with class certification analysis, identification of potentially responsible parties (PRPs), and apportionment of responsibility in multi-party groundwater pollution cases. His analysis includes the integration of geologic, hydraulic, chemical, and historical site-use data to uncover flaws in outdated or incorrect conceptual site models that often drive remedial or legal strategies.

In addition to direct expert witness services, Dr. Cohen acts as a third-party technical advisor to legal teams and to responsible parties. He guides and reviews the work of environmental consultants to ensure scientific rigor, cost-effective investigation, and alignment with strategic objectives. His collaborative approach ensures that site investigations are interpreted correctly, unnecessary sampling is avoided, and the true nature and extent of groundwater contamination is fully understood.

Dr. Cohen is known for his ability to clearly and persuasively communicate complex hydrogeologic findings. Through the use of technical graphics, animations, and plain-language summaries, he helps attorneys, judges, regulators, and juries understand environmental conditions and their implications. His work emphasizes both scientific accuracy and strategic clarity in support of litigation, regulatory response, and long-term environmental liability management.