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Subsurface Investigation at a Proposed School Site, Oakland, CA

Funded by a U.S. EPA Brownfield Assessment grant, the Department of Toxic Substances Control retained Accord Engineering to perform a subsurface investigation at a 3.5 acre proposed school site. The site consisted of 21 parcels with various commercial, residential, and manufacturing businesses which were still active at the time of investigation. An active gas station occupied a parcel with known groundwater contamination.

Our engineers planned and coordinated the sampling activities at the site under a tight 3-day schedule. The following tasks were successfully completed:

  • Prepared a Preliminary Endangerment Assessment (PEA) Work Plan, including a Sampling Analysis Plan, a Health and Safety Plan, and a Quality Assurance Plan
  • Conducted field soil gas and soil sampling, including a flux chamber testing of soil gas emissions from soil surface
  • Data validation of laboratory analysis report
  • Obtained well drilling permit
  • Reviewed laboratory report, conducted a risk assessment, and prepared a PEA Report

A total of 44 soil gas probes were installed using direct-push technology. Soil gas samples were collected and analyzed from various depths and locations of the subsurface. A series of flux chamber testing was conducted to assess gas emissions from the subsurface of possible contamination. The PEA Work Plan and Report were reviewed by the DTSC and U.S. EPA. The entire PEA process was completed in less than 6 months, including a 30-day public review and comment period.

More pictures from this very important project