Case Studies

BEACON PASSIVE SOIL-GAS SYSTEM

Chlorinated Plume Investigation

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OBJECTIVE

Phase I: Determine if any source areas are present at an area of concern (AOC) on a U.S. Air Force Base.

Phase II: Delineate the lateral extent of the plume.

FINDINGS

Taking a  Sample

The initial survey of the AOC identified a source area of Trichloroethene (TCE) and the direction the plume was migrating in the groundwater. Three subsequent surveys were performed to identify additional source areas and to delineate the lateral extent of the plume, which was much greater than the client expected. The client's overall project costs were reduced significantly by effectively characterizing the site and the down-gradient property before collecting one soil or groundwater sample.

After defining the extent of the plume, the passive soil gas data from the four surveys were combined on one color isopleth map to graphically show the results from all four surveys. In order to correlate data from each survey, a few locations were re-sampled in subsequent surveys to establish a correlation factor from one survey to another. Findings from the surveys were confirmed with follow-on intrusive sampling.