Vapor Intrusion Assessment and Innovative Technologies Help Reduce Long-Term Liabilities
The Raritan Arsenal was used by the U.S. Army from World War I until the 1960s as an ammunition storage and renovation facility. It has since been redeveloped and reoccupied for multi-unit commercial use. There are chlorinated solvents in groundwater at the Site, which are being monitored and remediated. The New Jersey Department of Environmental Protection (NJDEP) requested an assessment of subsurface vapor intrusion into indoor air and required the U.S. Army Corps of Engineers (Corps), now responsible for Site cleanup actions, to conduct extensive sub-slab and indoor air monitoring. Three years of monitoring data repeatedly showed detectable concentrations of volatile organic compounds (VOCs) in groundwater, soil gas and indoor air samples, interpreted by the NJDEP as a complete exposure pathway despite indications of interior sources for both tetrachloroethene (PCE) and trichloroethene (TCE). Repeat sampling of groundwater, sub-slab soil gas and indoor air by the previous consultant simply confirmed detections of PCE and TCE in all three media. Prior to the NJDEP issuing an Order for expensive mitigation, the Corps retained Geosyntec through Shaw Environmental (Shaw) to review historic data, provide an independent interpretation, and conduct a single phase of data collection to resolve once and for all the relative contributions of vapors from sources inside the building versus any contribution of vapors from the subsurface, and refine the mitigation program to an appropriate level.
