Electrical resistivity tomography, electromagnetic induction, and ultraviolet optical scanning tool data collected at Malmstrom Air Force Base, Great Falls, Montana, August 28–August 31, 2023

The U.S. Geological Survey (USGS), in cooperation with the U.S. Air Force Civil Engineer Center (USAF/CEC), conducted a pilot study at Malmstrom Air Force Base (MAFB) to evaluate the utility of two non-invasive geophysical techniques for detecting hydrocarbons in subsurface materials. Electrical resistivity tomography (ERT) and electromagnetic induction (EMI) surveys were completed August 28–29, 2023, along 7 transects overtop contaminated and uncontaminated sites for comparison. Additionally, the USGS completed ultraviolet optical scanning tool (UVOST) soundings and collected soil samples from temporary boreholes to validate geophysical survey results. A total of 11 UVOST soundings and 7 boreholes were completed August 28–31, 2023. Two soil samples from various depths were collected from each borehole for a total of 14 samples. Ten quality assurance/quality control samples consisting of 2 field equipment blanks (1 per day), 4 replicate soil samples (2 per day), and 4 trip blanks (2 per day). Soils were tested for volatile organic compounds, semi-volatile organic compounds, gasoline range organics, diesel range organics, metals, and per- and polyfluorinated substances (PFAS/PFOA).