Dr. Andrew J.B. Cohen, PhD, PH, is a contaminant hydrogeologist and expert witness with more than 30 years of consulting, research, and teaching experience. He evaluates the sources, movement, and extent of contamination involving PFAS and AFFF, chlorinated solvents, 1,4-dioxane, petroleum hydrocarbons, and other chemicals in groundwater, soil, rock, sediment, and surface water.

Dr. Cohen supports environmental litigation involving causation, source attribution, potentially responsible party identification, liability allocation, class certification, remediation costs, and critiques of opposing expert opinions. He is known for integrating complex hydrogeologic, chemical, and historical data into clear, technically defensible conclusions and effective visual presentations.

He earned his PhD from the University of California, Berkeley, conducted research at Lawrence Berkeley National Laboratory, has taught university courses in contaminant and environmental hydrogeology, and is a Certified Professional Hydrologist. He is also co-author of an internationally used groundwater book downloaded more than 17,000 times.

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.