Datasets Used to Create Maps of Pierre Shale Elevation and Surficial Deposit Thickness within and near Ellsworth Air Force Base, South Dakota, 2021

This data release contains borehole geophysical data collected within and near Ellsworth Air Force Base, South Dakota, from September 2020 to August 2021. The data accompanies a USGS scientific investigations map from Medler and others (2022). The U.S. Geological Survey, in cooperation with the U.S. Air Force Civil Engineer Center, collected borehole geophysical data and performed simple aquifer tests to estimate the thickness and hydraulic properties of surficial deposits. The purpose of data collection was to create generalized contour maps of Pierre Shale elevation and surficial deposit thickness within and near Ellsworth Air Force Base (study area). Natural gamma and electromagnetic induction (EMI) data were collected to refine or determine surficial deposit thickness at selected wells. Additionally, data from previous geophysical studies and drillers logs were compiled and combined with results from natural gamma and EMI data to delineate the Cretaceous Pierre Shale in the study area. Borehole nuclear magnetic (bNMR) resonance data were collected to estimate hydraulic conductivity and water content of surficial deposits overlying Pierre Shale. Simple aquifer tests using water slugs (slug tests) were performed to estimate hydraulic conductivity of surficial deposits and results were compared to hydraulic conductivity estimates from bNMR data. Also included in this data release are colloidal borescope flowmeter (CBFM) data collected from November to December 2020 at 24 wells. CBFM data were analyzed using Python programming language to obtain the mean horizontal flow direction and mean horizontal flow velocity of groundwater through the wellbore.