The Department of Toxic Substances Control (DTSC), the State Water Board, and the San Francisco Bay Regional Water Quality Control Board (SF Bay Regional Water Board) are currently developing a supplemental vapor intrusion guidance document for conducting uniform vapor intrusion evaluations in California. This guidance document, when finalized, will serve as a supplement to existing guidance (see below). The new guidance will provide detailed information on the following topics:
- Soil gas, subslab, indoor air, and outdoor air sampling recommendations that are focused on understanding spatial and temporal variability
- Recommendations for use of USEPA 2015 attenuation factors
- Risk management framework for vapor intrusion
- California-specific vapor intrusion database
For more information on VI, please contact Karen.Baker@dtsc.ca.gov.
Vapor Intrusion Guidance Documents
- Flow Diagram of DTSC Documents
- Advisory – Active Soil Gas Investigations (July 2015)
- Frequently Asked Questions (FAQ’s) (August 2015)
- Summary of Advisory Changes (2015)
- Final Guidance for the Evaluation & Mitigation of Subsurface Vapor Intrusion to Indoor Air (October 2011; also known as the Vapor Intrusion Guidance)
DTSC’s Vapor Intrusion Guidance provides a stepwise and sometimes iterative process for the investigation of vapor intrusion and describes procedures for screening and site-specific evaluation of potential risks associated with this exposure pathway. The DTSC Screening-Level Model spreadsheets that used the Johnson & Ettinger (J&E) model to predict theoretical indoor air concentrations of contaminants from soil gas and groundwater data have been removed because they were not updated and are not based on the most current J&E model spreadsheet tool from USEPA.
- Summary of Changes Between Interim Final and Final Guidance
- Human Health Risk
- Archived Screening-Level Model for Soil Gas Contamination
- Archived Screening-Level Model for Groundwater Contamination
- Vapor Intrusion Public Participation Advisory (March 2012)
DTSC developed this Advisory to help determine and implement appropriate public participation coordination and activities at sites where a potential vapor intrusion risk has been identified. The Advisory is a companion document to DTSC’s Vapor Intrusion Guidance and Vapor Intrusion Mitigation Advisory. In addition, the Advisory supplements DTSC’s Public Participation and Procedures Manual.
- Vapor Intrusion: Decision Framework for Testing Indoor Air & Overview of Sampling Procedures Presented at the February 2012 CUPA Conference
- Vapor Intrusion Mitigation Advisory, Revision 1 (October 2011)
Provides a framework that guides the reader through the decision process for 1) determining if mitigation is appropriate for the project site, 2) selecting a mitigation system that is protective of human health, and 3) ensuring that implementation is sustainable for the duration of mitigation. Emphasizes public participation and implementation considerations. Identifies likely technologies for vapor intrusion mitigation, but does not identify proven technologies.
- Summary of Changes Reflected in Revision 1