Evaluation of Air Quality in Buildings Located Above TCE and Chloroform Contaminated Plume - A Field Study

Vapor intrusion (VI) has been recognized since the 1990s as a potential pathway of concern at contaminated sites. VI is the migration of volatile organic compounds (VOCs) from the subsurface soils into overlying buildings. The major sources of organic vapors are waste disposal sites (landfills), contaminated old industrial sites, contaminated subsurface soils, and contaminated groundwater. The volatile organic compounds of concern in vapor intrusion are usually divided into two categories: chlorinated VOCs and petroleum hydrocarbons. Several residential and commercial buildings were built on a closed old industrial site in the 1990s. Due to the presence of TCE and chloroform in a groundwater plume located under the site, VI investigation was conducted at the commercial and residential buildings located on and around the site. Sub-slab soil gas and indoor air samples were collected to determine the indoor air quality in these buildings using Summa canisters equipped with flow controls. All samples were analyzed for volatile organic compounds using the USEPA Method TO-15. The analytical data were compared with background ambient air data and the New Jersey Department of Environmental Protection (NJDEP) soil gas and indoor air screening levels. The results indicated that chlorinated volatile organic compound including TCE and chloroform were present above the NJDEP screening levels in the sub-slab soil gas and indoor air samples collected from several buildings. To remediate the existing condition, a sub-slab depressurization system (SDS) was installed under the slab of each building with elevated levels of TCE and chloroform. After installation of the SDS, indoor air sampling was performed to determine the indoor air quality in these buildings. It was recommended that yearly inspection of the SDS and indoor air sampling be conducted.