Mahsa Shayan

Principal Civil and Environmental Engineer
Geosyntec Consultants

Dr. Mahsa Shayan is a Principal at Geosyntec Consultant. With over 16 years of combined academic and consulting experience, she specializes in the fate and transport of subsurface contaminants and the remediation of PFAS, chlorinated solvents, and petroleum hydrocarbons. Dr. Shayan earned her Ph.D. in Civil and Environmental Engineering from the University of Waterloo and completed a postdoctoral fellowship at the University of Toronto. Her work bridges laboratory research, field investigation, and advanced numerical modeling to support effective site investigation and remediation. Dr. Shayan has extensive experience with molecular diagnostic tools, including compound-specific isotope analysis (CSIA) and molecular biology techniques, to enhance conceptual site models and assess treatment system performance. She has also applied data science and machine learning methods to improve data interpretation, support source differentiation, and optimize remediation strategies. She is a licensed Professional Engineer in both the U.S. (Nevada) and Canada (Ontario) and is listed on Engineers Canada’s Mobility Register as an International Professional Engineer (IntPE).

Her contributions have been recognized with several awards, including Le Prix Józef Toth Award for Best Student Paper in Canadian Hydrogeology and the Katherine Hadley Memorial Scholarship in Environmental Studies. She has worked on major projects for the federal clients (the U.S. Air Force, NAVFAC, and the U.S. Army Corps of Engineers) and industrial clients (Shell, Chevron, DOW, Dupont/Chemours, CN), and remains active with the ITRC PFAS Team and SAME PFAS Industry-Government Engagement (IGE) initiative, and has served on technical committees and as session chair for conferences such as Battelle, RemTEC, and JETC. She is a reviewer for the Journal of Groundwater Monitoring & Remediation, a board member of the Applied NAPL Science Review e-Journal, and the director of the SAME Orange County Post Golf Tournament. She also mentors engineering students at California State University, Fullerton.