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Dale Werkema

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This child item contains ground penetrating radar (GPR) data collected over a small alpine wetland between Mogul Mine and Cement Creek located near Silverton, Colorado. Mine-impacted water is transported to Cement Creek via surface channels and groundwater through this wetland. The GPR method transmits radar pulses into the ground and measures the returned amplitude from these pulses over time. Variations in subsurface electromagnetic (EM) properties (dielectric permittivity, electrical conductivity, and magnetic susceptibility) affect the timing and amplitude of returned radar energy. For example, variation in water or mineral content are physical properties that often influence the EM properties that are observed...
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This child item contains frequency domain electromagnetic induction (FDEM) data collected along and around Cement Creek and California Gulch near Silverton, Colorado in support of other data collected at the site. The FDEM tool generates an EM field and measures eddy currents generated by conductive and/or magnetic materials in the subsurface in response to the applied field. A Geophex GEM-2 instrument with GPS was used with 5 frequencies ranging from 450 Hz to 18330 Hz. Additional details are contained in the ‘readme.txt’ files within each zip data directory.
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In June 2018, U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency (EPA) collected geophysical measurements to help evaluate the suitability of a proposed landfill site for disposing mine-waste materials in Fredericktown, MO. Frequency domain electromagnetic (FDEM) induction data were collected along the edge of the water. The antenna was placed on a plastic frame and held approximately 1 m above the water surface. The antenna was mounted on a raft that was towed behind a canoe. All unprocessed and processed data including the in-phase and quadrature components in parts per million, electrical conductivity (EC) in milliSiemens per meter (mS/m), and magnetic susceptibility in...
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This child item contains fiber-optic distributed temperature sensing (FO-DTS) data collected along the streambed interface of two streams named Cement Creek and California Gulch Creek located near Silverton Colorado. The FO-DTS method utilizes the temperature-dependent backscatter of light pulses emitted along armored fiber-optic cables to evaluate temperature at discrete linear sampling locations. For these deployments a Salixa XT-DTS control unit (Salixa Ltd, Hertfordshire, UK) was used, and measurements were made over several day increments at 0.508 m linear resolution along the streambed interface. Specific locations for collected data are located within the data files, and additional details are contained in...
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This child item contains ground penetrating radar (GPR) data collected over a small alpine wetland between Mogul Mine and Cement Creek located near Silverton, Colorado. Mine-impacted water is transported to Cement Creek via surface channels and groundwater through this wetland. The GPR method transmits radar pulses into the ground and measures the returned amplitude from these pulses over time. Variations in subsurface electromagnetic (EM) properties (dielectric permittivity, electrical conductivity, and magnetic susceptibility) affect the timing and amplitude of returned radar energy. For example, variation in water or mineral content are physical properties that often influence the EM properties that are observed...
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