In October 2016 and May 2017 frequency domain electromagnetic (FDEM) methods were used to image the electrical conductivity of the shallow subsurface. Electrical conductivity can be caused by changes in the soil, overburden, saturation, and water quality. Two multi-frequency tools were used at the site. One of the tools has a 1.6-meter (m) long antenna that was used in the vertical-dipole mode to collect data in stepped-frequency mode at seven user-selected frequencies ranging from 1530 to 47,970 Hertz (Hz). The GEM2HG has an antenna that is 2.1 m long, and it was used in vertical dipole mode with five stepped frequencies ranging from 90 to 24,000 Hz. In general, the lower frequencies penetrate to deeper depths, but the data are an average over a larger volume; whereas higher frequencies penetrate only to shallow depths but provide a smaller volume-averaged measurement. Data were collected at walking speeds of 3 kilometers per hour (km/hr), with a full suite of seven frequencies measured every 0.5 seconds (s), which translates to a complete measurement suite about every 0.4 m along the profile. All measurements were georeferenced with a global positioning system (GPS). Both the primary and secondary fields were measured at the receiver coil, and the ratio of the secondary to primary magnetic fields was recorded as in-phase and quadrature. The in-phase part of the EM field relates to the magnetic susceptibility, and the quadrature component relates to apparent conductivity (aEC) . Raw data for each frequency and Q Sum (a summation of quadrature values) were recorded in parts per million (ppm). In post processing, EM data were converted to magnetic susceptibility and aEC, which can be inverted to get the actual depth of the electrical conductivity value. This data release provides the raw ppm values, the magnetic susceptibility, and the apparent electrical conductivity values.

In October 2016 and May 2017 frequency domain electromagnetic (FDEM) methods were used to image the electrical conductivity of the shallow subsurface. Electrical conductivity can be caused by changes in the soil, overburden, saturation, and water quality. Two multi-frequency tools were used at the site. One of the tools has a 1.6-meter (m) long antenna that was used in the vertical-dipole mode to collect data in stepped-frequency mode at seven user-selected frequencies ranging from 1530 to 47,970 Hertz (Hz). The GEM2HG tool has an antenna that is 2.1 m long, and it was used in vertical dipole mode with five stepped frequencies ranging from 90 to 24,000 Hz. In general, the lower frequencies penetrate to deeper depths, but the data are an average over a larger volume; whereas higher frequencies penetrate only to shallow depths but provide a smaller volume-averaged measurement. A plastic-pipe frame was used to keep the antenna at a fixed distance of 1.0 m above water surface to minimize noise induced by variation in tool position. Profiling data were collected at walking speeds of approximately 3 kilometer per hour(km/hr), with a full suite of seven frequencies measured every 0.5 seconds (s), which translates to a complete measurement suite about every 0.4 m along the profile. All measurement positions were mapped with a global positioning system (GPS). Both the primary and secondary fields were measured at the receiver coil, and the ratio of the secondary to primary magnetic fields was recorded as in-phase and quadrature. The in-phase part of the EM field relates to the magnetic susceptibility, and the quadrature component relates to apparent conductivity (aEC) . Raw data for each frequency and Q Sum (a summation of quadrature values) were recorded in parts per million (ppm). In post processing, EM data were converted to magnetic susceptibility and aEC, which can be inverted to get the actual depth of the electrical conductivity value. This data release provides the raw ppm values, the magnetic susceptibility, and the apparent electrical conductivity values.

In October 2016 and May 2017 frequency domain electromagnetic (FDEM) methods were used to image the electrical conductivity of the shallow subsurface. Electrical conductivity can be caused by changes in the soil, overburden, saturation, and water quality. Two multi-frequency tools were used at the site. One of the tools has a 1.6-meter (m) long antenna that was used in the vertical-dipole mode to collect data in stepped-frequency mode at seven user-selected frequencies ranging from 1530 to 47,970 Hertz (Hz). The GEM2HG tool has an antenna that is 2.1 m long, and it was used in vertical dipole mode with five stepped frequencies ranging from 90 to 24,000 Hz. In general, the lower frequencies penetrate to deeper depths, but the data are an average over a larger volume; whereas higher frequencies penetrate only to shallow depths but provide a smaller volume-averaged measurement. A plastic-pipe frame was used to keep the antenna at a fixed distance of 1.0 m above water surface to minimize noise induced by variation in tool position. Profiling data were collected at walking speeds of approximately 3 kilometer per hour(km/hr), with a full suite of seven frequencies measured every 0.5 seconds (s), which translates to a complete measurement suite about every 0.4 m along the profile. All measurement positions were mapped with a global positioning system (GPS). Both the primary and secondary fields were measured at the receiver coil, and the ratio of the secondary to primary magnetic fields was recorded as in-phase and quadrature. The in-phase part of the EM field relates to the magnetic susceptibility, and the quadrature component relates to apparent conductivity (aEC) . Raw data for each frequency and Q Sum (a summation of quadrature values) were recorded in parts per million (ppm). In post processing, EM data were converted to magnetic susceptibility and aEC, which can be inverted to get the actual depth of the electrical conductivity value. This data release provides the raw ppm values, the magnetic susceptibility, and the apparent electrical conductivity values.

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 above the land surface along the cleared paths through the proposed disposal cell locations. The data were collected with a hand-held, multi-frequency antenna carried approximately 1 meter (m) above the land surface at walking speeds using a multi-frequency tool. 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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below land surface. These output data are also served in this data release.

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 above the land surface along the cleared paths through the proposed disposal cell locations. The data were collected with a hand-held, multi-frequency antenna carried approximately 1 meter (m) above the land surface at walking speeds using a multi-frequency tool. 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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below land surface. These output data are also served in this data release.

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 above the land surface along the cleared paths through the proposed disposal cell locations. The data were collected with a hand-held, multi-frequency antenna carried approximately 1 meter (m) above the land surface at walking speeds using a multi-frequency tool. 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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below land surface. These output data are also served in this data release.

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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below the water surface. These output data are also served in this data release. 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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth-dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below water surface. These output data are also served in this data release.

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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below the water surface. These output data are also served in this data release. 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 parts per thousand are served in this data release. In addition, the data were inverted to generate depth-dependent estimates of conductivity along the profiles. An analysis of the depth of investigation indicated the FDEM reliably estimated conductivity values to depths of about 3 m below water surface. These output data are also served in this data release.

From October 2016 to July 2018, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers and Maine Department of Transportation, collected surface, marine and borehole geophysical surveys to characterize the subsurface materials on land and under the water at a former mine facility in Brooksville, Maine. Three water-based geophysical methods were used to evaluate the geometry and composition of subsurface materials. Continuous seismic profiling (CSP) methods provide the depth to water bottom, and, when sufficient signal penetration can be achieved, delineate the depth to bedrock and subbottom materials. Continuous resistivity profiling (CRP) and frequency domain electromagnetics (FDEM) methods were used to define the electrical properties of the shallow subbottom. All data points were located using global positioning systems (GPS), and the GPS data were used for real-time navigation. The stage of Goose pond was monitored with pressure transducers during the water-borne geophysical surveys. On land, electrical resistivity tomography (ERT), FDEM, shear-wave velocity (Vs) seismic refraction and horizontal-to-vertical spectral ratio (HVSR) seismic methods were used to characterize the subbottom materials and to evaluate the surveys collected on the water. Borehole geophysical logs were collected in five boreholes to identify fluid and electrical properties as well as natural gamma emissions.

From October 2016 to July 2018, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers and Maine Department of Transportation, collected surface, marine and borehole geophysical surveys to characterize the subsurface materials on land and under the water at a former mine facility in Brooksville, Maine. Three water-based geophysical methods were used to evaluate the geometry and composition of subsurface materials. Continuous seismic profiling (CSP) methods provide the depth to water bottom, and, when sufficient signal penetration can be achieved, delineate the depth to bedrock and subbottom materials. Continuous resistivity profiling (CRP) and frequency domain electromagnetics (FDEM) methods were used to define the electrical properties of the shallow subbottom. All data points were located using global positioning systems (GPS), and the GPS data were used for real-time navigation. The stage of Goose pond was monitored with pressure transducers during the water-borne geophysical surveys. On land, electrical resistivity tomography (ERT), FDEM, shear-wave velocity (Vs) seismic refraction and horizontal-to-vertical spectral ratio (HVSR) seismic methods were used to characterize the subbottom materials and to evaluate the surveys collected on the water. Borehole geophysical logs were collected in five boreholes to identify fluid and electrical properties as well as natural gamma emissions.