Instructors: Steve Harris & Dr. Krista Barfoot (Conestoga-Rovers & Associates)
Audio: Recorded from a live Internet Seminar
Duration: 1 Hour
Price: $149
Abstract: Vapor intrusion into building indoor air has emerged as a key potential human exposure pathway that is the focus of heightened regulatory and public concerns at contaminated sites. At historical contaminated sites, vapor intrusion is causing the evaluation of health risks to be re-evaluated even when potential risks previously had been considered adequately addressed. At newly identified contaminated sites, vapor intrusion often is one of the critical exposure pathways generating health concerns.
Vapor intrusion is defined as the migration of volatile chemicals from the subsurface into overlying buildings. Volatile chemicals present in either soil or shallow groundwater can emit vapors that may migrate through unsaturated zone soils and into overlying buildings where the chemicals become mixed with indoor air. Although the resulting indoor air concentrations are low and typically undetectable without specialized sampling equipment, they may still pose an unacceptable health risk through the chronic effects associated with long-term inhalation exposure. A complicating factor in evaluating potential health risks due to vapor intrusion is the potential presence of volatile chemicals in indoor air emitted from indoor sources within a building (e.g., household cleaning products, dry-cleaned clothes, hobby supplies, paint, carpets, etc.). As a result, moving directly to indoor air quality sampling typically is not a recommended first step.
The goal of this seminar present is to present an overview of the current practices applied in evaluating the vapor intrusion pathway at contaminated sites and to introduce potential methods to mitigate vapor intrusion. Methods for evaluating whether the vapor intrusion pathway is potentially complete at a site and assessing potential health risks have rapidly evolved in the last several years. The seminar is focused on providing project coordinators and managers with guidance to determine whether vapor intrusion is a pathway of potential concern at a site (i.e., through a screening assessment), and whether a more detailed site-specific evaluation of the pathway is required. The seminar will review the potential data requirements needed to conduct a site-specific vapor intrusion assessment, such as the collection of data pertaining to groundwater and soil quality, unsaturated zone geology, and building configuration to develop a conceptual site model for the vapor intrusion pathway. Soil gas quality sampling may also be required to determine the chemical concentrations actually present in soil gas. A brief discussion regarding indoor air quality sampling, and associated potential complications, is also presented. A description is provided of the modeling approaches applied to quantify exposure levels and human health risks/hazards through indoor air inhalation. Finally, an overview is provided of available potential mitigation strategies that can be implemented at buildings where vapor intrusion is shown to pose potential health risks above acceptable levels.
In summary, participants in this seminar will be able to:
- Determine whether the vapor intrusion pathway is of potential concern at a site through conducting a soil and/or groundwater quality screening assessment;
- Evaluate data needs to conduct a site-specific vapor intrusion assessment, and develop suitable field investigations work plans (likely including soil gas quality sampling);
- Understand the modeling approaches taken to assess human health risks posed by vapor intrusion; and
- Consider available mitigation strategies for situations where vapor intrusion is shown to pose potential health risks above acceptable levels.
