Vapor Intrusion Forensic Analysis

Environmental Forensics
Oral Presentation

Prepared by J. Knight
Geosyntec Consultants, 1255 Roberts Blvd, Suite 200, Kennesaw, Georgia, 30144, United States

Contact Information:; 678-202-9580


Geosyntec performed site specific forensic analyses to determine the potential for subsurface-to-indoor air vapor intrusion (VI) at several buildings related to a groundwater plume containing volatile organic compounds (VOCs). In order to address the VI concern, a forensic analysis was conducted utilizing a HAPSITEĀ® portable gas chromatograph and mass spectrometer (GC/MS) coupled with building pressure cycling (BPC) and active air sampling. These methods were used in order to provide multiple lines of evidence for or against the likelihood of VI from the migrating VOC plume.

An initial forensic analysis of dozens of buildings provided confounding results for several locations. The data showed conflicting information about the origin of VOCs detected in indoor air, since there is potential for indoor air detections from a variety of sources: consumer products stored or used indoor or near the building, other outdoor air sources, or VI. This presentation will present both field and table-top techniques to differentiate VOCs sourced from background contributors from VOCs sourced from subsurface-to-indoor air VI.