Benefits

When indoor air testing is conducted, VOCs are commonly detected at concentrations above the applicable indoor air screening criteria. Such results often require extensive follow-up testing programs to definitively identify the source of the detected VOCs (i.e., vapor intrusion versus indoor sources). At Hill Air Force Base, for example, more than 25% of the TCE detections above action levels in indoor air have subsequently been attributed to indoor sources of VOCs rather than vapor intrusion. For PCE and 1,2-dichloroethane (1,2-DCA), indoor sources have resulted in even higher percentages of action level exceedances. However, identification of the indoor VOC source has typically required multiple rounds of sampling and analysis, and in many cases an indoor source is identified only after a vapor intrusion mitigation system has been installed and has failed to improve indoor air quality. Validation of CSIA as a method to distinguish between vapor intrusion and indoor sources of VOCs will significantly reduce the effort and cost of testing indoor air at vapor intrusion sites. The development of a validated procedure for use of CSIA to distinguish between vapor intrusion and indoor sources of VOCs could reduce vapor intrusion investigation costs 25% to 50% by significantly reducing the need for follow-up investigation at buildings with exceedances of indoor air screening levels attributable to indoor sources of VOCs. (Anticipated Project Completion - 2013)