Robert Ettinger is a Senior Principal in Geosyntec’s Santa Barbara office, and provides technical and litigation support on risk-based decision making, corrective action implementation, and subsurface fate and transport modeling for contaminated land sites. He has been studying subsurface vapor transport phenomena for environmental corrective action planning for almost 30 years. Mr. Ettinger has authored key papers discussing modeling vapor migration to indoor air, including the Johnson and Ettinger 1991 model that is currently used in many regulatory programs. Additionally, he has consulted on various investigation and modeling studies for gasoline retail, refinery, manufacturing, Superfund, and Brownfield redevelopment sites.
SESSION KEYNOTE PRESENTATION
Three Decades of Vapor Intrusion Assessments – From J&E Modeling to the Current Array of Tools
In the 1990’s, the vapor intrusion pathway was commonly evaluated through the collection of subsurface data and application of screening-level models (e.g., the 1991 Johnson and Ettinger [J&E] Model) to assess potential exposures and estimate risk/hazard. Indoor air sampling was considered for locations where model-predicted exposures were above target levels, but typically was not conducted early in the investigation process due to the concern of potential interference of background sources on indoor air quality measurements. Advancements over the past three decades have identified several site-specific characteristics that influence vapor intrusion (e.g., temporal variability, spatial variability, atypical preferential pathways, building-specific factors), and new tools have been developed to better assess these factors. Consideration of the benefits and limitations of the various tools in the array of investigation techniques, along with the development of a defensible vapor intrusion site conceptual model and risk management decisions will improve our capabilities to implement protective and cost-effective vapor intrusion assessments.