Prompted by a 2012 decrease in the toxicity values for trichloroethene (TCE) exposure that was adopted by the U.S. EPA and the Ohio EPA, GZA was requested to return to a site it had helped a client close more than a decade prior. Ohio EPA now requested sampling at an active industrial warehouse for the potential presence of TCE in ambient air from vapor intrusion associated with a historical subsurface release beneath the building caused by a former owner. The site had been cleaned up under Ohio EPA’s Voluntary Action Program (VAP) and received a No Further Action Letter with a Covenant Not to Sue over a decade earlier; during the previous VAP assessment, the vapor intrusion exposure pathway was successfully evaluated with modeling to meet applicable standards in effect at the time.


GZA’s VAP-Certified Professional associated with the original VAP cleanup developed a sampling approach and led GZA’s experienced vapor intrusion team which performed the investigation. Sampling locations were selected to avoid potential background interferences created by the current workers and active warehouse operations. Vapor samples were collected using Vapor Pin® sampling ports installed through the warehouse floor slab at two locations. Four indoor air and two sub-slab vapor samples were collected. VAP certified laboratory results indicated TCE was not detected at concentrations greater than the reporting limits in either the indoor air samples or the sub-slab vapor samples.


With demonstrated high quality vapor intrusion sampling and analysis results, GZA provided the client with the necessary information to satisfy the Ohio EPA’s request. No further site investigation for vapor intrusion was required.