Vapor Intrusion Services
The migration of volatile organic vapors into existing and future structures (vapor intrusion or “VI”) from contaminated soil and groundwater can lead to exposures of building occupants to potentially harmful levels of chemicals. Consequently, VI has emerged as a critical driver for investigating and remediating contaminated sites and is increasingly an avenue of inquiry during due diligence assessments for property transfers (Phase I and II environmental assessments). State regulatory agencies, including the Indiana Department of Environmental Management (IDEM), have placed a high priority on VI as a potentially significant exposure pathway, and the U.S. EPA’s pending VI guidance update adds substantial weight to this topic.
In response to this market and regulatory impetus, Wilcox Environmental Engineering has assembled a VI Practice Team whose members have combined their experience, expertise, and specialized VI training to develop innovative approaches for establishing “off-ramps” or strategies to exit the VI regulatory process and improving conceptual site models when VI is a potential exposure pathway, as well as reducing VI assessment and mitigation/ remediation costs and VI-related liabilities for Wilcox clients.
The behavior of organic vapors in the subsurface and their interaction with man-made structures are not fully understood, which can lead to incomplete characterization of the VI exposure pathway. The VI Practice Team is actively researching subsurface vapor migration and attenuation to improve our understanding of vapor/structure interaction and to develop better conceptual site models that lead to more effective and economical risk assessment, risk management, and remediation.
The VI Practice Team is continuously evaluating and developing new methods and approaches for assessing this critical exposure pathway in order to reduce site investigation costs and timeframes. Recent advances by Wilcox include:
- Developing an innovative groundwater sampling method to improve characterization of groundwater vapor source areas and to reduce or eliminate VI investigations at off-site properties.
- Utilization of alternative sampling techniques and/or laboratory analyses to reduce cost and increase field reliability and sample representativeness.
- Developing methods for economically integrating site-specific meteorological data into VI evaluations to supplement analytical samples and provide more robust VI assessments with fewer samples.
- Strategies for minimizing or modifying air sampling efforts to reduce potential litigation risks for clients.
- Standard operating procedures for consistent application of emerging field and data-analysis methods.
Our VI Practice Team is also developing Expedited Site Characterization (ESC) approaches for VI and other types of site investigation to maximize client value and reduce costs. The foundations of ESC are:
- More efficient and less expensive site characterizations that generate a high density of high-quality data.
- Higher quality and more accurate conceptual site models that lead to better decisions about exposure pathways and exposure risks.
- Improved remediation, risk-management, and monitoring decisions that translates into more effective, shorter-term mitigation and remediation, and reduced time to site closure.