ASSESSMENT AND MITIGATION OF VAPOR INTRUSION FROM DRY CLEANERS - CASE STUDIES AND LESSONS LEARNED

Dry cleaners have historically used tetrachloroethene (PCE), a chlorinated volatile organic compound (VOC), as the primary dry cleaning solvent. These dry cleaners are often found to have subsurface environmental media, soil and groundwater, impacted with PCE and associated degradation products, including trichloroethene (TCE), dichloroethene (DCE), and vinyl chloride (VC). Volatilization of these VOCs from impacted environmental media contributes to an increased risk for vapor intrusion into the overlying dry cleaner space as well as surrounding tenant spaces and buildings. Environmental assessment of properties that have historically or are currently occupied by dry cleaner tenants and evaluation of the associated risk of vapor intrusion into indoor spaces has become a common due diligence practice in commercial real estate transactions. The geology underlying these properties often determines how building foundations and utility conduits are designed and constructed and can contribute to the ease with which VOC vapors migrate into overlying and surrounding buildings. Several case studies will be presented, each including a discussion of the environmental assessment of each property, evaluation of the vapor intrusion risk, influence of the subsurface geology on vapor intrusion, and resulting risk mitigation strategies.