Helen Dawson is a Principal Civil and Environmental Engineer based in Washington, D.C. with more than 30 years of experience focused on private practice, academia, and public service. Her practice spans a wide range of technical disciplines including vapor intrusion, groundwater characterization, and contaminant fate and transport modeling related to the spread of dense non-aqueous phase liquids, chlorinated solvents, and metals in the environment.
Sought out for regulatory analysis and forensic evaluation of complex environmental systems, Helen has had responsibility for characterizing contaminated sites, developing decision frameworks designed to responsibly manage risk, and providing litigation support in environmental pollution cases throughout her career. She also has experience in applied research, overseeing projects designed to increase understanding of complex environmental systems and improve characterization and cleanup of contaminated sites.
A recognized leader in vapor intrusion, Helen was the primary author of the U.S. EPA's Office of Solid Waste Emergency Response (OSWER) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils in 2002. She also was the primary investigator and author on two key technical documents that support vapor intrusion assessment: one on background indoor air concentrations in residences, and another on the subsurface-to-indoor air attenuation at vapor intrusion sites. She continues to advance the state of the practice though specialized presentations for clients, invited talks at national conferences, and participation in expert panels advising regulatory agencies.
She also has extensive experience in the characterization and monitoring of groundwater contamination in complex hydrogeological systems. She has successfully documented monitored natural attenuation of groundwater contaminants at numerous sites and supported technical impracticability waiver applications. Helen has provided technical support and guidance for sites regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the Resource Conservation and Recovery Act (RCRA), the National Environmental Policy Act (NEPA), and the Toxic Substances Control Act (TSCA) as well as the U.S. EPA's Underground Injection Control program and various brownfield redevelopment programs throughout the nation.