Derek Tomlinson PE, LSRP, PEng has specialized experience since 1994 in development of strategies for managing sites with dense and light non-aqueous phase liquids (DNAPL and LNAPL) and vapor intrusion (VI) concerns. Derek works for Geosyntec Consultants in Plymouth Meeting, Pennsylvania. He is an environmental engineer with graduate training in contaminant hydrogeology including the characterization and remediation of sites contaminated with chlorinated solvents and migration of vapors within the subsurface. Derek has worked at refineries, waste sites, and other industrial facilities under USEPA CERCLA and RCRA programs; state and regional programs in California, Connecticut, Delaware, Georgia, Maryland, Massachusetts, New Jersey, Ohio, Pennsylvania, Rhode Island, Texas, Virginia, and West Virginia; and internationally in Australia, Brazil, Canada, China, and France. Technical expertise includes the design, implementation, and operation of a range of in situ remediation technologies within both porous media and fractured bedrock geologic settings. He was active with the ITRC LNAPL team and a contributing author for the LNAPL technical guidance and training documents. He is also active with ASTM and is contributing member that developed standard guides for LNAPL conceptual site models, LNAPL transmissivity calculation methods, and vapor intrusion assessments and mitigation strategies for real estate transactions. Derek earned a Bachelor degree in Civil Engineering in 1994 and a Master degree in 1999, both from the University of Waterloo in Waterloo, Ontario, Canada. He is a professional engineer in Pennsylvania and Canada and a Licensed Site Remediation Professional (LSRP) in New Jersey. .