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At least 1,423 records · Page 79Linked to original sources
USGS1977

Borehole geophysical investigations in the south Texas uranium district

Contrasts of electrical properties between uranium deposits and their host rocks in South Texas are subtle. In places where deposits are small or deep, conventional geophysical well-logging techniques and hole-to-hole measurements may be the only practical method to detect changes in rock properties associated with the occurrence of uranium ore deposits. Two separate ore-producing areas in South Texas were chosen for studying borehole geophysical techniques applied to uranium-exploration problems. Extensive measurements of physical properties were made on cores and taken from holes where electrical-resistivity, induced-polarization and gamam-ray logs were run. These analyses show that: (1) induced-polarization anomalies are caused by a change in pyrite content and clay-sized material content and (2) resistivity anomalies are associated with a change in clay-sized material content and cementation. In addition to conventional borehole techniques, hole-to-hole induced-polarization and resistivity tests were made in South Texas. These measurements were made by placing a current source down one hole and a receiver cable down an adjacent hole whose separation ranged from 30 to 300 m and hole depths varied from 80 to 270 m. These tests show that hole-to-hole measurements can be used to detect changes in physical properties, associated with uranium ore, that occur between boreholes. Hole-to-hole measurements provide a link between surface measurements and well logs and can minimize the amount of drilling needed to locate an ore deposit. Accordingly, borehole geophysics will become an increasingly important evaluation tool as mineral exploration goes deeper.

Texas↗
USGS2002

Evaluation of borehole geophysical logging, aquifer-isolation tests, distribution of contaminants, and water-level measurements at the North Penn Area 5 Superfund Site, Bucks and Montgomery Counties, Pennsylvania

Borehole geophysical logging and aquifer-isolation (packer) tests were conducted at the North Penn Area 5 Superfund site in Bucks and Montgomery Counties, Pa. Caliper, naturalgamma, single-point-resistance, fluid-temperature, fluid-resistivity, heatpulse-flowmeter, and digital acoustic-televiewer logs and borehole television surveys were collected in 32 new and previously drilled wells that ranged in depth from 68 to 302 feet. Vertical borehole-fluid movement direction and rate were measured with a high-resolution heatpulse flowmeter under nonpumping conditions. The suite of logs was used to locate water-bearing fractures, determine zones of vertical borehole-fluid movement, select depths to set packers, and locate appropriate screen intervals for reconstructing new wells as monitoring wells. Aquifer-isolation tests were conducted in four wells to sample discrete intervals and to determine specific capacities of discrete water-bearing zones. Specific capacities of isolated zones during packer testing ranged from 0.12 to 15.30 gallons per minute per foot. Most fractures identified by borehole geophysical methods as water-producing or water-receiving zones produced water when isolated and pumped. The acoustic-televiewer logs define two basic fracture sets, bedding-plane partings with a mean strike of N. 62° E. and a mean dip of 27° NW., and high-angle fractures with a mean strike of N. 58° E. and a mean dip of 72° SE. Correlation of heatpulse-flowmeter data and acoustic-televiewer logs showed 83 percent of identified water-bearing fractures were high-angle fractures.

Pennsylvania↗
USGS1990

Oil-shale data, cores, and samples collected by the U.S. geological survey through 1989

The U.S. Geological Survey has acquired a large collection of geotechnical data, drill cores, and crushed samples of oil shale from the Eocene Green River Formation in Colorado, Wyoming, and Utah. The data include about 250,000 shale-oil analyses from about 600 core holes. Most of the data is from Colorado where the thickest and highest-grade oil shales of the Green River Formation are found in the Piceance Creek basin. Other data on file but not yet in the computer database include hundreds of lithologic core descriptions, geophysical well logs, and mineralogical and geochemical analyses. The shale-oil analyses are being prepared for release on floppy disks for use on microcomputers. About 173,000 lineal feet of drill core of oil shale and associated rocks, as well as 100,000 crushed samples of oil shale, are stored at the Core Research Center, U.S. Geological Survey, Lakewood, Colo. These materials are available to the public for research.

Conference Paper↗
USGS2011

Physical properties of sediment from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

This study characterizes cored and logged sedimentary strata from the February 2007 BP Exploration Alaska, Department of Energy, U.S. Geological Survey (BPXA-DOE-USGS) Mount Elbert Gas Hydrate Stratigraphic Test Well on the Alaska North Slope (ANS). The physical-properties program analyzed core samples recovered from the well, and in conjunction with downhole geophysical logs, produced an extensive dataset including grain size, water content, porosity, grain density, bulk density, permeability, X-ray diffraction (XRD) mineralogy, nuclear magnetic resonance (NMR), and petrography. This study documents the physical property interrelationships in the well and demonstrates their correlation with the occurrence of gas hydrate. Gas hydrate (GH) occurs in three unconsolidated, coarse silt to fine sand intervals within the Paleocene and Eocene beds of the Sagavanirktok Formation: Unit D-GH (614.4 m-627.9 m); unit C-GH1 (649.8 m-660.8 m); and unit C-GH2 (663.2 m-666.3 m). These intervals are overlain by fine to coarse silt intervals with greater clay content. A deeper interval (unit B) is similar lithologically to the gas-hydrate-bearing strata; however, it is water-saturated and contains no hydrate. In this system it appears that high sediment permeability (k) is critical to the formation of concentrated hydrate deposits. Intervals D-GH and C-GH1 have average "plug" intrinsic permeability to nitrogen values of 1700 mD and 675 mD, respectively. These values are in strong contrast with those of the overlying, gas-hydrate-free sediments, which have k values of 5.7 mD and 49 mD, respectively, and thus would have provided effective seals to trap free gas. The relation between permeability and porosity critically influences the occurrence of GH. For example, an average increase of 4% in porosity increases permeability by an order of magnitude, but the presence of a second fluid (e.g., methane from dissociating gas hydrate) in the reservoir reduces permeability by more than an order of magnitude.

Alaska↗
USGS2006

Two-dimensional magnetotelluric model of deep resistivity structure in the Bodie-Aurora district of California

Introduction: Magnetotelluric data were acquired during October 2001 by the U.S. Geological Survey (USGS) as part of a study to examine the structural nature of basins in the transition zone between the Sierra Nevada Mountains of California and the Basin and Range province of Nevada. Magnetotelluric (MT) geophysical studies assist the mapping of geologic structure and the inference of lithologic packages that are concealed beneath the Earth's surface. The Basin and Range province has a complicated geologic history, which includes extension and compression of the Earth's crust to form the basins and ranges that blanket much of Nevada. The basins and ranges in the vicinity of this study trend northeastward and are bounded by steeply dipping strike slip faults. Interestingly, deep east-west magnetic trends occur in the aeromagnetic data of this study area indicating that the northeast-trending basins and ranges represent only thin-skinned deformation at the surface with an underlying east-west structure. To investigate this issue, MT data were acquired at seven stations in eastern California, 20 km east of Mono Lake. The purpose of this report is to present a two-dimensional apparent resistivity model of the MT data acquired for this study.

Open-File Report↗
USGS2006

Gravity, magnetic, and physical property data in the Smoke Creek Desert area, northwest Nevada

The Smoke Creek Desert, located approximately 100 km (60 mi) north of Reno near the California-Nevada border, is a large basin situated along the northernmost parts of the Walker Lane Belt (Stewart, 1988), a physiographic province defined by northwest-striking topographic features and strike-slip faulting. Because geologic framework studies play an important role in understanding the hydrology of the Smoke Creek Desert, a geologic and geophysical effort was begun to help determine basin geometry, infer structural features, and estimate depth to Pre-Cenozoic rocks, or basement. In May and June of 2004, and June of 2005, the U.S. Geological Survey (USGS) collected 587 new gravity stations, more than 160 line-kilometers (100 line-miles) of truck-towed magnetometer data, and 111 rock property samples in the Smoke Creek Desert and vicinity in northwest Nevada, as part of an effort to characterize its hydrogeologic framework. In the Smoke Creek Desert area, gravity highs occur over rocks of the Skedaddle Mountains, Fox Range, Granite Range, and over portions of Tertiary volcanic rocks in the Buffalo Hills. These gravity highs likely reflect basement rocks, either exposed at the surface or buried at shallow depths. The southern Smoke Creek Desert corresponds to a 25-mGal isostatic gravity low, which corresponds with a basin depth of approximately 2 km. Magnetic highs are likely due to granitic, andesitic, and metavolcanic rocks, whereas magnetic lows are probably associated with less magnetic gneiss and metasedimentary rocks in the region. Three distinctive patterns of magnetic anomalies occur throughout the Smoke Creek Desert and Squaw Creek Valley, likely reflecting three different geological and structural settings.

Open-File Report↗
USGS2026

Shallow hydrogeologic framework of the Tully Valley mudboil area, Onondaga County, New York

Mudboils have been documented in the Tully Valley in southern Onondaga County, New York, since the late 1890s. Sediment-laden water from the mudboils flows into Onondaga Creek, which empties into Onondaga Lake at Syracuse 15 miles to the north. Turbidity from the mudboils has degraded the water quality of Onondaga Creek despite a series of mitigation efforts that began in the early 1990s. Turbidity mitigation actions presently (2025) being considered include creek relocation and offline sediment settling. In support of these proposed actions during 2021–23, the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, U.S. Environmental Protection Agency, Onondaga Nation, Onondaga Environmental Institute, and Central New York Regional Planning and Development Board, collected and analyzed geologic, hydrologic, geophysical, and geotechnical data to characterize the shallow hydrogeology along four proposed creek-relocation paths and in the proposed offline settling basin area. The investigation indicated that the four proposed creek-relocation paths, two east of Onondaga Creek and two west of Onondaga Creek, are underlain by sediments including muck, alluvium, mudboil deposits, alluvial-fan sand and gravel, and lacustrine fines. The proposed excavations would penetrate partially to fully saturated conditions: generally, the water table is shallow near the creek and deep on the alluvial fans. The shallowest excavation, about 5 feet below land surface, would be near the creek and primarily in alluvium, and the deepest excavation, as much as 30 feet below land surface, would be in the alluvial-fan deposits. Brackish waters would be penetrated by proposed channel excavations on the eastern side of Onondaga Creek in an area downgradient from a potentially leaking historical salt-exploration borehole and near the main mudboil area. Excavation in these areas likely would provide a continuous source of brackish groundwater to the relocated creek. Proposed channel excavations of muck, soft to very soft lacustrine fines, and mudboil-type sediments in mudboil and suspected mudboil areas would pose an excavation and slope stability challenge and would have the greatest potential to create new mudboils. Proposed channel excavations below the water table on the Rattlesnake Gulf and Rainbow Creek alluvial fans would intercept groundwater and make the constructed streambank susceptible to seepage-induced slope instability. The substantial water-level fluctuation in the sediments of both alluvial fans would aggravate the stability condition. In addition, excavation on the Rattlesnake Gulf alluvial fan would have the potential to affect water-supply springs at the toe of the fan. The proposed offline settling basin area is in the northern part of the Rattlesnake Gulf alluvial fan. Natural and man-made diversions of Rattlesnake Gulf have resulted in saturated conditions in the general area of the proposed basin. The proposed offline settling basin would be excavated in, and berms would be constructed on, alluvial-fan deposits and lacustrine fines. In the proposed basin area, the alluvial deposits overlying the lacustrine fines are less than 10 feet thick. Excavation, berm construction, and loading of the saturated, soft to very soft lacustrine fines may be problematic and require soil strengthening.

New York↗
USGS2010

Geology, geochemistry, and geophysics of the Fry Canyon uranium/copper project site, southeastern Utah: Indications of contaminant migration

The Fry Canyon uranium/copper project site in San Juan County, southeastern Utah, was affected by the historical (1957–68) processing of uranium and copper-uranium ores. Relict uranium tailings and related ponds, and a large copper heap-leach pile at the site represent point sources of uranium and copper to local soils, surface water, and groundwater. This study was designed to establish the nature, extent, and pathways of contaminant dispersion. The methods used in this study are applicable at other sites of uranium mining, milling, or processing. The uranium tailings and associated ponds sit on a bench that is as much as 4.25 meters above the level of the adjacent modern channel of Fry Creek. The copper heap leach pile sits on bedrock just south of this bench. Contaminated groundwater from the ponds and other nearby sites moves downvalley and enters the modern alluvium of adjacent Fry Creek, its surface water, and also a broader, deeper paleochannel that underlies the modern creek channel and adjacent benches and stream terraces. The northern extent of contaminated groundwater is uncertain from geochemical data beyond an area of monitoring wells about 300 meters north of the site. Contaminated surface water extends to the State highway bridge. Some uranium-contaminated groundwater may also enter underlying bedrock of the Permian Cedar Mesa Sandstone along fracture zones. Four dc-resistivity surveys perpendicular to the valley trend were run across the channel and its adjacent stream terraces north of the heap-leach pile and ponds. Two surveys were done in a small field of monitoring wells and two in areas untested by borings to the north of the well field. Bedrock intercepts, salt distribution, and lithologic information from the wells and surface observations in the well field aided interpretation of the geophysical profiles there and allowed interpretation of the two profiles not tested by wells. The geophysical data for the two profiles to the north of the well field suggest that the paleochannel persists at least 900 m to the north of the heap leach and pond sites. Contamination of groundwater beneath the stream terraces may extend at least that far. Fry Creek surface water (six samples), seeps and springs (six samples), and wells (eight samples) were collected during a dry period of April 16–19, 2007. The most uranium-rich (18.7 milligrams per liter) well water on the site displays distinctive Ca-Mg-SO 4 -dominant chemistry indicating the legacy of heap leaching copper-uranium ores with sulfuric acid. This same water has strongly negative δ 34 S of sulfate (–13.3 per mil) compared to most local waters of –2.4 to –5.4 per mil. Dissolved uranium species in all sampled waters are dominantly U(VI)-carbonate complexes. All waters are undersaturated with respect to U(VI) minerals. The average 234 U/ 238 U activity ratio (AR) in four well waters from the site (0.939±0.011) is different from that of seven upstream waters (1.235±0.069). This isotopic contrast permits quantitative estimates of mixing of site-derived uranium with natural uranium in waters collected downstream. At the time of sampling, uranium in downstream surface water was mostly (about 67 percent) site-derived and subject to further concentration by evaporation. Three monitoring wells located approximately 0.4 kilometer downstream contained dominantly (78–87 percent) site-derived uranium. Distinctive particles of chalcopyrite (CuFeS) and variably weathered pyrite (FeS 2 ) are present in tailings at the stream edge on the site and are identified in stream sediments 1.3 kilometers downstream, based on inspection of polished grain mounts of magnetic mineral separates.

Utah↗
USGS2017

Water-resources and land-surface deformation evaluation studies at Fort Irwin National Training Center, Mojave Desert, California

The U.S. Army Fort Irwin National Training Center (NTC), in the Mojave Desert, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle) within the NTC boundaries (fig. 1; California Department of Water Resources, 2003). Because of increasing water demands at the NTC, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army, completed several studies to evaluate water resources in the developed and undeveloped groundwater basins underlying the NTC. In all of the developed basins, groundwater withdrawals exceed natural recharge, resulting in water-level declines. However, artificial recharge of treated wastewater has had some success in offsetting water-level declines in Irwin Basin. Additionally, localized water-quality changes have occurred in some parts of Irwin Basin as a result of human activities (i.e., wastewater disposal practices, landscape irrigation, and/or leaking pipes). As part of the multi-faceted NTC-wide studies, traditional datacollection methods were used and include lithological and geophysical logging at newly drilled boreholes, hydrologic data collection (i.e. water-level, water-quality, aquifer tests, wellbore flow). Because these data cover a small portion of the 1,177 square-mile (mi2 ) NTC, regional mapping, including geologic, gravity, aeromagnetic, and InSAR, also were done. In addition, ground and airborne electromagnetic surveys were completed and analyzed to provide more detailed subsurface information on a regional, base-wide scale. The traditional and regional ground and airborne data are being analyzed and will be used to help develop preliminary hydrogeologic framework and groundwater-flow models in all basins. This report is intended to provide an overview of recent water-resources and land-surface deformation studies at the NTC.

California↗
USGS2014

The destructive 1946 Unimak near-field tsunami: New evidence for a submarine slide source from reprocessed marine geophysical data

The M w 8.6 earthquake in 1946 off the Pacific shore of Unimak Island at the end of the Alaska Peninsula generated a far-field tsunami that crossed the Pacific to Antarctica. Its tsunami magnitude, 9.3, is comparable to the 9.1 magnitude of the 2011 Tohoku tsunami. On Unimak Island's Pacific shore, a runup of 42 m destroyed the lighthouse at Scotch Cap. Elsewhere, localized tsunamis with such high runups have been interpreted as caused by large submarine landslides. However, previous to this study, no landslide large enough to generate this runup was found in the area that is limited by the time interval between earthquake shaking and tsunami inundation at Scotch Cap. Reworking of a seismic reflection transect and colocated multibeam bathymetric surveys reveal a landslide block that may explain the 1946 high runup. It is seaward of Scotch Cap on the midslope terrace and within the time-limited area.

Geophysical Research Letters↗
USGS2012

Electrical properties of granite with implications for the lower crust

The electrical properties of granite appear to be dominantly controlled by the amount of free water in the granite and by temperature. Minor contributions to the electrical properties are provided by hydrostatic and lithostatic pressure, structurally bound water, oxygen fugacity, and other parameters. The effect of sulfur fugacity may be important but is experimentally unconfirmed. In addition to changing the magnitude of electrical properties, the amount and chemistry of water in granite significantly changes the temperature dependence of the electrical properties. With increasing temperature, changes in water content retain large, but lessened, effects on electrical properties. Near room temperature, a monolayer of water will decrease the electrical resistivity by an order of magnitude. Several weight-percent water may decrease the electrical resistivity by as much as 9 orders of magnitude and decrease the thermal activation energy by a factor of 5. At elevated temperatures just below granitic melting, a few weight-percent water may still decrease the resistivity by as much as 3 orders of magnitude and the activation energy by a factor of 2. Above the melting temperature (650° to 1100°C depending upon water pressure), a few weight-percent water will decrease the resistivity by less than an order of magnitude and will barely change the activation energy. Remarkably, the few weight-percent water must be present as free water. Experiments with hydrated hornblende schist (with structural water) indicate an electrical resistivity very similar to that for dry granite. The implications of these results, together with the findings of deep magnetic sounding and magnetotelluric surveys, suggest much more free water than is commonly associated with the lower crust and possibly into the upper mantle.

Journal of Geophysical Research Solid Earth↗
USGS2014

Annual rainfall and runoff in New England

This paper presents the results of studies of average rainfall and runoff, developed in the Office of the Division Engineer, New England Division, United States Corps of Engineers, in cooperation with the District Engineer, United States Geological Survey, and prepared in connection with flood‐control studies of the Connecticut and Merrimack River basins.

Connecticut, Maine, Massachusetts, New Hampshire, ↗
USGS2018

Inversion of data from electrical resistivity imaging surveys in water-covered areas

Electrical resistivity imaging surveys widely used in many environmental and engineering studies have also been conducted in water-covered areas. Surveys in water-covered areas include conventional surveys using multi-electrode resistivity systems where part of the survey line crosses a river or stream, and surveys conducted entirely within a water-covered environment. Surveys that are located entirely within a water-covered environment utilise electrodes mounted on a streamer, towed behind a boat. The streamer can be dragged along the water bottom, or float on the water surface. In this paper, the smoothness-constrained least-squares inversion method commonly used to interpret electrical resistivity imaging data from land surveys is adapted for underwater surveys. To accommodate the water bottom topography, a distorted finite-element grid is used to calculate the apparent resistivity values for the inversion model. The first few rows of elements are used to model the water layer, while the lower part of the grid is used for the sub-bottom resistivity distribution. For robust inversion, the water column resistivity and geometry must be known accurately as a large proportion of the current flows through the water layer. The section of the Earth below the bottom surface is subdivided into a large number of rectangular cells. The water column resistivity and geometry in the earth model is fixed, and the inversion program attempts to determine the resistivity of the cells that would most accurately reproduce the observed resistivity measurements. Implementation of water column resistivity and geometric constraints is demonstrated using numerical simulations and field data. Examples of electrical resistivity imaging surveys conducted on and across water bodies including rivers and near-shore marine environments are shown.

Exploration Geophysics↗
USGS1940

Additional evidence on the relation of temperature to structure in the Salt Creek Oil field, Natrona County, Wyoming

Observations of bottom hole temperatures in approximately 100 deep wells in the Salt Creek field have been made during the past few years by the Stanolind Oil and Gas Company. These recent observations confirm and extend in a remarkable manner the results obtained in the summers of 1922 and 1923 when it was found from temperature surveys in 21 wells that the temperatures over a considerable portion of the field were definitely related to the structure.

Wyoming↗
USGS2006

Seismoelectric numerical modeling on a grid

Our finite-difference algorithm provides a new method for simulating how seismic waves in arbitrarily heterogeneous porous media generate electric fields through an electrokinetic mechanism called seismoelectric coupling. As the first step in our simulations, we calculate relative pore-fluid/grain-matrix displacement by using existing poroelastic theory. We then calculate the electric current resulting from the grain/fluid displacement by using seismoelectric coupling theory. This electrofiltration current acts as a source term in Poisson's equation, which then allows us to calculate the electric potential distribution. We can safely neglect induction effects in our simulations because the model area is within the electrostatic near field for the depth of investigation (tens to hundreds of meters) and the frequency ranges (10 Hz to 1 kHz) of interest for shallow seismoelectric surveys.We can independently calculate the electric-potential distribution for each time step in the poroelastic simulation without loss of accuracy because electro-osmotic feedback (fluid flow that is perturbed by generated electric fields) is at least 105 times smaller than flow that is driven by fluid-pressure gradients and matrix acceleration, and is therefore negligible. Our simulations demonstrate that, distinct from seismic reflections, the seismoelectric interface response from a thin layer (at least as thin as one-twentieth of the seismic wavelength) is considerably stronger than the response from a single interface. We find that the interface response amplitude decreases as the lateral extent of a layer decreases below the width of the first Fresnel zone. We conclude, on the basis of our modeling results and of field results published elsewhere, that downhole and/or crosswell survey geometries and time-lapse applications are particularly well suited to the seismoelectric method. ?? 2006 Society of Exploration Geophysicists.

Geophysics↗
USGS2006

A note on the correlation between geophysical observations and seismicity in the Arava/(Araba) Valley at the southern part of the Dead Sea fault

The spatial distribution of the earthquakes in the Arava Valley, a 150-km section of the Dead Sea Transform, is compared for the first time with the local subsurface geological features derived from geophysical and geological data. Gravity data suggested that the Gharandal, Timna, and Elat basins were filled by low-density young sediments. These features were confirmed by seismic reflection profiles and high-resolution aeromagnetic (HRAM) survey. The HRAM survey delineated the trace of the Dead Sea Transform (DST), which separates magnetic anomalies in the eastern and western parts of the valley, and revealed the occurrence of the unknown deep magmatics. Overall, the earthquake activity appears to be strongly related to the Dead Sea Transform. However, on a local scale, there is no apparent correlation between the seismicity and the mapped fault segments comprising the DST fault system. Absence of the correlation may be a result of insufficient accuracy of the earthquake localization and/or the inclined fault plane. However, in spite of such inaccuracy, it is clearly observed that the large clusters of the low-magnitude earthquakes coincide well with the sedimentary basins. Two pronounced clusters appear to coincide with the subsurface magmatics. We assume that the subsurface geology predetermines areas of stress accumulation and earthquakes. These areas can be the end of faults, or fault jogs, which sometimes create basins. Magmatism can also be affected by the stress field and predetermine the stress and earthquakes' allocation. ?? 2007 Science From Israel/LPPLtd.

Israel Journal of Earth Sciences↗
USGS2016

Characterization of fractures and flow zones in a contaminated crystalline-rock aquifer in the Tylerville section of Haddam, Connecticut

The U.S. Geological Survey, in cooperation with the Connecticut Department of Energy and Environmental Protection, investigated the characteristics of the bedrock aquifer in the Tylerville section of Haddam, Connecticut, from June to August 2014. As part of this investigation, geophysical logs were collected from six water-supply wells and were analyzed to (1) identify well construction, (2) determine the rock type and orientation of the foliation and layering of the rock, (3) characterize the depth and orientation of fractures, (4) evaluate fluid properties of the water in the well, and (5) determine the relative transmissivity and head of discrete fractures or fracture zones. The logs included the following: caliper, electromagnetic induction, gamma, acoustic and (or) optical televiewer, heat-pulse flowmeter under ambient and pumped conditions, hydraulic head data, fluid electrical conductivity and temperature under postpumping conditions, and borehole-radar reflection collected in single-hole mode. In a seventh borehole, a former water-supply well, only caliper, fluid electrical conductivty, and temperature logs were collected, because of a constriction in the borehole. This report includes a description of the methods used to collect and process the borehole geophysical data, the description of the data collected in each of the wells, and a comparison of the results collected in all of the wells. The data are presented in plots of the borehole geophysical logs, tables, and figures. Collectively these data provide valuable characterizations that can be used to improve or inform site conceptual models of groundwater flow in the study area.

Connecticut↗