Vapor Intrusion Sampling and Mitigation at a Former Dry Cleaner Facility

GES conducted a site investigation at a former dry cleaner facility to delineate the source area, evaluated receptors, and initiated a vapor intrusion (VI) investigation of the site and five surrounding residential properties. VI sampling required sub-slab sampling-point installation, sub-slab and near-slab sampling using SUMMA canisters with flow restrictors, and indoor air sampling using SUMMA canisters with 24-hour flow restrictors. The VI investigation revealed immediate environmental concern (IEC) conditions within the site building due to PCE concentrations in indoor air, which exceeded the New Jersey Department of Environmental Protection (NJDEP) Rapid Action Level (RAL). The IEC conditions were mitigated with a sub-slab depressurization system (SSDS). An air sparge (AS)/soil vapor extraction (SVE) system was installed to remediate the PCE source area. The SSDS successfully mitigated the IEC within the building and removed the VI risk, limiting the exposure of tenants and customers to chlorinated volatile organic compounds (CVOCs). Use of the AS/SVE system to treat CVOCs in the source area resulted in a significant cost savings, as excavation of CVOC-impacted soils would have required disposal of the material as hazardous waste due to presence of spent halogenated solvents. The sandy soils at the site provided ideal conditions for a large radius of influence for the AS/SVE system, which contributed to a more rapid reduction in source-area CVOC concentrations.