Assessment and Mitigation: Defining and Addressing Vapor Pathways in a Mixed Use Area

Additional Info

  • Practice Areas: Groundwater Assessment and Remediation
  • Event or Publication: US EPA CLU-IN Newsletter Technology News and Trends
  • Title: Assessment and Mitigation: Defining and Addressing Vapor Pathways in a Mixed Use Area
  • All Authors: Vickie Meredith (WYDEQ), Jeff Kurtz, and Coleman Hoyt
  • Geosyntec Authors: Jeff Kurtz, Coleman Hoyt
  • Date: 2013
  • Type: Publication (Online)

In 2010 and 2011, the Wyoming Department of Environmental Quality (WYDEQ) installed mitigation systems in 24 residences and one commercial building to prevent intrusion of trichloroethene (TCE) and tetrachloroethene (PCE) vapors from an orphan site in downtown Cheyenne.

The source had been previously identified as a 20-acre groundwater PCE plume. A three-phase investigation conducted between 2009 and 2011 included the collection of groundwater, soil gas, indoor air, and sub-slab vapor samples to evaluate the potential for vapor intrusion (VI) in area buildings. Residential buildings in areas of high soil vapor PCE concentrations (above 810 micrograms per cubic meter [?g/m3]) were offered pre-emptive mitigation systems, while buildings in the surrounding areas were investigated further before potentially being selected for mitigation.

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