Vapor Intrusion Assesment and Mitigation for Redevelopment of a Large Manufacturing Facility

In a town of 7,300, the largest employer, an automotive parts manufacturer, closes its 250,000 square-foot plant.  Several years later a local manufacturer has the opportunity to expand and needs a larger facility.  The abandoned facility suits the need, but the subsurface is heavily contaminated with chlorinated solvents from extensive historical degreasing operations.  The previous owner is already remediating groundwater contamination, and initial investigation results reveal chlorinated solvent contamination in soil beneath much of the building.  To bring jobs and taxes back into the community, the town and local manufacturer must identify and mitigate threats to workers that will be employed on the site in the future.  However, the redevelopment project economics cannot support these extraordinary brownfield costs.

This presentation describes how the town, in a public-private partnership with the local manufacturer, used EPA Assessment Grant funds to identify and delineate a vapor intrusion risk affecting over 80% of the building, conduct testing needed to support design of mitigation systems, and complete the systems’ designs.  Subslab vapor sampling techniques and results, risk evaluation techniques, and the results of a program to evaluate lower-cost subslab vapor screening techniques, will be described, as will be the pressure extension testing performed to support mitigation system design.

The acquisition of $1,000,000 in state brownfield funding allowed the struggling community to then pay for the design, installation, commissioning, and initial monitoring of an active subslab vapor intrusion mitigation system.  These components of the redevelopment project will be described in detail.