Per- and polyfluoroalkyl Substances in Select Domestic Wells in the Middle Chickahominy River Watershed, Virginia

Samples for per- and polyfluoroalkyl substances (PFAS) were collected from 10 domestic wells to assess the extent to which PFAS is coming from the groundwater aquifer or from another source within the home.
 
 Specific objectives included:

Collect well construction information;
Collect samples for analysis of PFAS directly from the aquifer at domestic  wells; 
Collect samples for analysis of PFAS from two locations within the home to compare with samples collected directly from the aquifer;
Quality Assure all data in accordance with USGS policies; and
Release data to the public as a citable USGS Data Release.

 
Description of Available Datasets:

These data are available in Excel (.xlsx) files that contain water-quality and quality-assurance results. The Excel files are duplicated as tab-delimited text files to increase accessibility to nonproprietary formats. The files titled VDH_PFAS_Results contain analytical results and field measurements for samples collected from 10 locations in Virginia. 

The files titled VDH_PFAS_Quality_Assurance contain associated equipment blanks, field blanks, lab blanks, and replicates used for quality control. Lab blanks are used to assess contamination imparted by the analytical process. Equipment blanks were used to assess possible contamination from sampling equipment. Field blanks were collected using certified analyte-free water at each environmental sample and used to assess possible cross contamination from sampling materials and sampling technique in the field. Field replicates were collected concurrently with the environmental sample and used to understand the variability of results.  

The attached XML file titled VDH_PFAS_Metadata contains metadata explaining the provenance of the data and should be thoroughly read to understand data structure and limitations. The files titled VDH_PFAS_Data_Dictionary may be used as a reference to explain codes, terms, and abbreviations used in these datasets. The files titled VDH_PFAS_Ongoing_Precision_and_Recovery contain quality assurance samples reported by the laboratory which establishes additional confidence in results over time.

Sample Collection, Data Validation, and Quality Assurance:
 
Ten homes were sampled as part of this project and at each location domestic wells were the main source of water. At each home, one sample was collected directly from the aquifer by accessing the well and using pre-cleaned, PFAS-free sampling equipment. Field measurements (pH, specific conductance, temperature, dissolved oxygen, turbidity) were collected in a flow-through cell and recorded with the well sample, before contact with in-house plumbing and before treatment. One sample was collected at the main point of use within the home (typically the kitchen faucet). One sample was collected at an intermediate location within the homes plumbing system located between the well and kitchen faucet. Analyte concentrations were compared between sampling locations within the homes plumbing system to assess the contribution of PFAS from the aquifer and understand possible contribution of PFAS from the homes pluming system.   
 
U.S. Environmental Protection Agency (EPA) Method 533 (Rosenblum and Wendelken, 2019) was used to determine PFAS concentrations in all samples. Samples were analyzed at SGS Wilmington in North Carolina. Reporting and detection levels for PFAS results are specific to the analyte, sample matrix, instrumentation, and laboratory performance. Results throughout this dataset that are reported with a “<” (less than) qualifier represent values that were not detected above the reporting level for that sample and specific analyte. The reporting levels shown in this dataset are synonymous with the minimum reporting level as defined by Rosenblum and Wendelken (2019).   
 
A combination of field blanks, laboratory method blanks, isotopically labeled compound recoveries, and ongoing precision and recovery samples were used to assess field techniques and validity of the reported results. Results recorded in the file titled VDH_PFAS_Results met all quality assurance criteria, and no additional qualification was required.

References:

Rosenblum, L., and Wendelken, S.C., 2019, Method 533: Determination of per- and polyfluoroalkyl substances in drinking water by isotope dilution anion exchange solid phase extraction and liquid chromatography/tandem mass spectrometry: U.S. Environmental Protection Agency Document EPA 815-B-19-020, 52 p., accessed February 14, 2023, at https://www.epa.gov/sites/default/files/2019-12/documents/method-533-81….