Project Example: Vapor Intrusion Investigation & Mitigation

Solvent Plume, St. Louis Park, MN

The EPA Superfund Technical Assessment & Response Team (START) program provides technical support to EPA’s site assessment, response, prevention, and preparedness activities. Bay West was a subcontractor to Weston Solutions as an EPA Region 5 START contractor assisting with EPA activities in Minnesota. Since 2006, Bay West has worked on approximately 90 projects in Minnesota under this contract, one of which is the St. Louis Park Solvent Plume Project.

After solvents (primarily PCE and TCE) were detected in soil samples in a residential area of St. Louis Park, the MPCA and EPA jointly developed a plan for additional soil and vapor testing.

  • Bay West, Weston Solutions, and Home Safety Solutions (HSS [an Indoor Air Quality Consultant]) worked together to develop the scope and work plan to assess the extent and magnitude of the vapor issue (sampling and analysis) and mitigate the problem (residential vapor mitigation).
  • Bay West, under Weston’s EPA START Contract, conducted sub-slab and air sampling with basements and crawl spaces in approximately 270 residential homes. If solvents were detected at concentrations exceeding regulatory thresholds, Bay West inspected slabs, basements, and crawl spaces, then sampled indoor and outdoor air.
  • Bay West eventually provided support while the EPA equipped 41 homes with vapor mitigation systems, then conducted follow-up indoor air monitoring in these homes to provide evidence of the vapor mitigation systems’ effectiveness.
  • Bay West coordinated and attended two public meetings to present information to concerned home owners, obtain access agreements, and schedule access to home for assessment work and system installations.
  • Bay West also worked closely with the City of St. Louis Park to address home owner concerns and obtain access on residential properties throughout the project.