Title:

PFAS in Vermont Background Soils

To determine background concentrations of per- and polyfluoroalkyl substances (PFAS) in Vermont soils, Sanborn Head issued a Request for Proposals. In response to the request, the Project Team prepared a Sampling and Analysis Plan (SAP) outlined in the Preliminary Design Report dated December 17, 2021. The SAP included PFAS sampling guidelines, sampling locations, analyte list, and analytical procedures. After submitting the SAP to Sanborn Head, the project team was provided with field and analytical data from a background sampling event that was completed in June through August 2018 (the 2018 Study). The 2018 Study composed of a total of 68 samples from 66 locations, with duplicate samples from two of the sites. At each sample location, the completed field form and compound values were provided. The full data table displays the percent solids, TOC, and values of 17 different PFAS compounds. At the University of New Hampshire (UNH), a preliminary sample was collected by the Project Team to practice the process of soil sampling for PFAS analysis. The sample was sent to Alpha Analytical for the PFAS and moisture content analysis while grain size distribution and pH were measured by the project team. Perfluoroheptanoic acid (PFHpA), perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) were detected in the UNH sample and concentrations ranged from 0.324 – 0.861 parts per billion (ppb) of PFAS in the soil. Data collected from the 2018 Study was provided and the Project Team prepared a Final Report that includes a statistical analysis of the data using ProUCL. The statistical analysis involved determining if there were any outliers present in the data and a background threshold value (BTV) for each compound detected. The data was analyzed with and without outliers to determine upper prediction limits (UPL) and upper tolerance limits (UTL) that were used to determine the BTVs.

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