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At least 37 records · Page 2Linked to original sources

USGS2010

Reducing Uncertainty in the Distribution of Hydrogeologic Units within Volcanic Composite Units of Pahute Mesa Using High-Resolution 3-D Resistivity Methods, Nevada Test Site, Nevada

The U.S. Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing groundwater contamination resulting from historical underground nuclear testing through the Environmental Management program and, in particular, the Underground Test Area (UGTA) project. From 1951 to 1992, 828 underground nuclear tests were conducted at the Nevada Test Site (NTS) northwest of Las Vegas (DOE UGTA, 2003). Most of these tests were conducted hundreds of feet above the groundwater table; however, more than 200 of the tests were near, or within, the water table. This underground testing was limited to specific areas of the NTS including Pahute Mesa, Rainier Mesa/Shoshone Mountain, Frenchman Flat, and Yucca Flat. Volcanic composite units make up much of the area within the Pahute Mesa Corrective Action Unit (CAU) at the NTS, Nevada. The extent of many of these volcanic composite units extends throughout and south of the primary areas of past underground testing at Pahute and Rainier Mesas. As situated, these units likely influence the rate and direction of groundwater flow and radionuclide transport. Currently, these units are poorly resolved in terms of their hydrologic properties introducing large uncertainties into current CAU-scale flow and transport models. In 2007, the U.S. Geological Survey (USGS), in cooperation with DOE and NNSA-NSO acquired three-dimensional (3-D) tensor magnetotelluric data at the NTS in Area 20 of Pahute Mesa CAU. A total of 20 magnetotelluric recording stations were established at about 600-m spacing on a 3-D array and were tied to ER20-6 well and other nearby well control (fig. 1). The purpose of this survey was to determine if closely spaced 3-D resistivity measurements can be used to characterize the distribution of shallow (600- to 1,500-m-depth range) devitrified rhyolite lava-flow aquifers (LFA) and zeolitic tuff confining units (TCU) in areas of limited drill hole control on Pahute Mesa within the Calico Hills zeolitic volcanic composite unit (VCU), an important hydrostratigraphic unit in Area 20. The resistivity response was evaluated and compared with existing well data and hydrogeologic unit tops from the current Pahute Mesa framework model. In 2008, the USGS processed and inverted the magnetotelluric data into a 3-D resistivity model. We interpreted nine depth slices and four west-east profile cross sections of the 3-D resistivity inversion model. This report documents the geologic interpretation of the 3-D resistivity model. Expectations are that spatial variations in the electrical properties of the Calico Hills zeolitic VCU can be detected and mapped with 3-D resistivity, and that these changes correlate to differences in rock permeability. With regard to LFA and TCU, electrical resistivity and permeability are typically related. Tuff confining units will typically have low electrical resistivity and low permeability, whereas LFA will have higher electrical resistivity and zones of higher fracture-related permeability. If expectations are shown to be correct, the method can be utilized by the UGTA scientists to refine the hydrostratigraphic unit (HSU) framework in an effort to more accurately predict radionuclide transport away from test areas on Pahute and Rainier Mesas.

Nevada↗

USGS2009

Hydrologic Conditions that Influence Streamflow Losses in a Karst Region of the Upper Peace River, Polk County, Florida

The upper Peace River from Bartow to Fort Meade, Florida, is described as a groundwater recharge area, reflecting a reversal from historical groundwater discharge patterns that existed prior to the 1950s. The upper Peace River channel and floodplain are characterized by extensive karst development, with numerous fractures, crevasses, and sinks that have been eroded in the near-surface and underlying carbonate bedrock. With the reversal in groundwater head gradients, river water is lost to the underlying groundwater system through these karst features. An investigation was conducted to evaluate the hydrologic conditions that influence streamflow losses in the karst region of the upper Peace River. The upper Peace River is located in a basin that has been altered substantially by phosphate mining and increases in groundwater use. These alterations have changed groundwater flow patterns and caused streamflow declines through time. Hydrologic factors that have had the greatest influence on streamflow declines in the upper Peace River include the lowering of the potentiometric surfaces of the intermediate aquifer system and Upper Floridan aquifer beneath the riverbed elevation due to below-average rainfall (droughts), increases in groundwater use, and the presence of numerous karst features in the low-water channel and floodplain that enhance the loss of streamflow. Seepage runs conducted along the upper Peace River, from Bartow to Fort Meade, indicate that the greatest streamflow losses occurred along an approximate 2-mile section of the river beginning about 1 mile south of the Peace River at Bartow gaging station. Along the low-water and floodplain channel of this 2-mile section, there are about 10 prominent karst features that influence streamflow losses. Losses from the individual karst features ranged from 0.22 to 16 cubic feet per second based on measurements made between 2002 and 2007. The largest measured flow loss for all the karst features was about 50 cubic feet per second, or about 32 million gallons per day, on June 28, 2002. Streamflow losses varied throughout the year, and were related to seasonal fluctuations in groundwater levels. When groundwater levels were at their lowest level at the end of the dry season (May and June), there was an increased potential for streamflow losses. During this study, the largest streamflow losses occurred at the beginning of the summer rainy season when discharge in the river increased and large volumes of water were needed to replenish unfilled cavities and void spaces in the underlying aquifers. The underlying geology along the upper Peace River and floodplain is highly karstified, and aids in the movement and amount of streamflow that is lost to the groundwater system in this region. Numerous karst features and fractured carbonates and cavernous zones observed in geologic cores and geophysical logs indicate an active, well-connected, groundwater flow system. Aquifer and dye tests conducted along the upper Peace River indicate the presence of cavernous and highly transmissive layers within the floodplain area that can store and transport large volumes of water in underground cavities. A discharge measurement made during this study indicates that the cavernous system associated with Dover Sink can accept over 10 million gallons per day (16 cubic feet per second) of streamflow before the localized aquifer storage volume is replenished and the level of the sink is stabilized.

Scientific Investigations Report↗

USGS2003

Reconnaissance of acid drainage sources and preliminary evaluation of remedial alternatives at the Copper Bluff mine, Hoopa Valley Reservation, California

Acidic drainage from the inactive Copper Bluff mine cascades down a steep embankment into the Trinity River, on the Hoopa Valley Reservation in northern California. The Copper Bluff mine produced about 100,000 tons of sulfide-bearing copper-zinc-gold-silver ore during 1957–1962. This report summarizes the results of a water-resources investigation begun by the U.S. Geological Survey in 1994 with the overall objective of gathering sufficient geochemical, hydrologic, and geologic information so that a sound remediation strategy for the Copper Bluff mine could be selected and implemented by the Hoopa Valley Tribe. This study had the following specific objectives: (1) monitor the quality and quantity of the mine discharge, (2) determine seasonal variability of metal concentrations and loads, (3) map and sample the underground mine workings to determine sources of flow and suitability of mine plugging options, and (4) analyze the likely consequences of various remediation and treatment options. Analysis of weekly water samples of adit discharge over parts of two wet seasons (January to July 1995 and October 1995 to May 1996) shows that dissolved copper (Cu) and zinc (Zn) concentrations (in samples filtered with 0.20-micrometer membranes) varied systematically in a seasonal pattern. Metal concentrations increased dramatically in response to the first increase in discharge, or first flush, early in the wet season. The value of Zn/Cu in the adit discharge exhibited systematic seasonal variations; an annual Zn/Cu cycle was observed, beginning with values between 3 and 5 during the main part of the wet season, rising to values between 6 and 10 during the period of lowest discharge late in the dry season, and then dropping dramatically to values less than 3 during the first-flush period. Values of pH were fairly constant in the range of 3.1 to 3.8 throughout the wet season and into the beginning of the dry season, but rose to values between 4.5 and 5.6 during the period of lowest discharge, from October to early December 1995. Underground reconnaissance was conducted once during dry-season conditions (September 1995) and twice during wet-season conditions (March 1995 and March 1996). The main tunnel was accessed to a distance of about 600 feet from the portal entrance. Water samples were collected at nine locations along the floor of the main tunnel and from several ore shoots to evaluate the contributions of water and dissolved constituents from different portions of the mine. Values of pH ranged from 2.5 to 6.4 at different underground locations, concentrations of copper ranged from 0.020 to 44 mg/L (milligram per liter), zinc from 6.3 to 160 mg/L, and cadmium from 0.010 to 0.47 mg/L. Discharge from the ore shoots ranged from less than 1 gallon per minute to more than 30 gallons per minute and was always a small component of the total mine flow compared with the tunnel floor drainage. During March 1996, the main flow originated in the northernmost portion of the underground workings (inaccessible) and mixed with an unknown quantity of water upwelling from flooded lower workings. High-water marks observed on the tunnel walls indicate that past blockages impounded more than 100,000 gallons of water. Sudden release of a large volume of metal-rich water could have serious effects on fish and other aquatic resources in the Trinity River. Because of the hydrogeologic setting, mine plugging is not likely to offer an effective long-term solution to the problem of acid mine drainage at the Copper Bluff mine. The underground workings are close to a state highway and underlie a 500-foot-high bluff with highly fractured rocks that seep during the wet season. Total plugging likely would result in additional uncontrolled seepage and could potentially destabilize the highway. Partial plugging to restrict flow during periods of highest discharge may provide benefits in terms of reduced risk of catastrophic release without the additional risks associated with total plugging. Passive water treatment methods such as wetlands or anoxic limestone drains are unlikely to succeed at the Copper Bluff mine because of the lack of available space. A covered conveyance for the discharge directly from the mine portal to the Trinity River is a low-cost remedial alternative that would not reduce metal loadings to the Trinity River, but would reduce pathways of metal exposure to humans and wildlife. Lime neutralization or innovative, active water treatment methods such as bioreactors represent high-cost remedial alternatives that likely would be successful if sufficient resources were available for adequate design, testing, construction, long-term maintenance, and sludge disposal.

California↗

USGS2022

Stormwater reduction and water budget for a rain garden on sandy soil, Gary, Indiana, 2016–18

Stormwater reduction measures, or green infrastructure, were implemented in the parking area at Gary City Hall, Gary, Indiana, with the intention of reducing stormwater discharge to the sewers. A study area, including a centrally located rain garden and the surrounding paved surfaces and green space, was instrumented during both a preconstruction and a postconstruction period to (1) develop water budgets to improve understanding of the rain garden hydrology and (2) determine the quantity of stormwater runoff that was diverted and retained by the green infrastructure instead of reaching the combined storm and sanitary sewer. The study was focused on warm-season precipitation and was monitored during spring, summer, and fall of 2016, 2017 and 2018. Before construction of the rain garden in the parking lot of Gary City Hall in 2017, nearly all precipitation was conveyed away from the parking lot by underground drains, discharged to the sewer, and treated as sanitary waste at the Gary Sanitary District’s treatment plant or discharged directly to local waterways if stormflow exceeded capabilities of the sewage treatment plant. A goal of the Great Lakes Restoration Initiative is the reduction of sewer overflows to local waterways to improve the quality of water entering the Great Lakes. Cities such as Gary benefit financially and environmentally by reducing discharges of stormwater runoff to the sewer system, eliminating the need for treatment. Before implementation of green infrastructure at Gary City Hall, approximately 25 percent of precipitation (approximately 10,200 cubic feet) discharged as stormwater to the sewers through the parking lot drain. After implementation, 2 percent of precipitation discharged to the sewers. For the spring, summer, and fall seasons of 2017 and 2018, 21–24 percent (about 10,700–19,700 cubic feet) of precipitation was captured by the newly installed rain garden. Stormwater discharged to the rain garden infiltrated the sandy soil and was later evaporated from the soil surface, was transpired by plants, or recharged the underlying groundwater aquifer. The percent reduction in stormwater discharged to the storm sewer after the construction of the rain garden was 80.3 percent, equating to approximately 21,400 and 39,300 gallons of stormwater in 2017 and 2018, respectively.

Indiana↗

USGS1976

A model for calculating effects of liquid waste disposal in deep saline aquifer

Injection of liquid industrial wastes into confined underground saline aquifers can offer a good disposal alternative from both environmental and economic considerations. One of the needs in choosing from among several disposal alternatives is a means of evaluating the influence such an injection will have on the aquifer system. This report describes a mathematical model to accomplish this purpose. The objective of the contract was to develop a three-dimensional transient mathematical model which would accurately simulate behavior of waste injection into deep saline aquifers. Fluid properties, density and viscosity are functions of pressure, temperature and composition to provide a comprehensive assessment tool. The model is a finite-difference numerical solution of the partial differential equations describing single phase flow in the aquifer, energy transport by convection and conduction, and compositional changes in the aquifer fluid. The model is not restricted to examining waste disposal operations. It can be used effectively to evaluate fresh water storage in saline aquifers, hot water storage in underground aquifers, salt water intrusion into groundwater flow systems and other similar applications. The primary advantages of the present model can be summarized as: The model is user-oriented for easy application to full-scale evaluation needs. The model is fully three-dimensional and transient. The model is comprehensive accounting for density and viscosity variations in the aquifer due to temperature or compositional changes. The model includes the effects of hydrodynamic dispersion in both the temperature and compositional mixing between resident and injected fluids. The model energy balance includes the effects of pressure. This can be important in deep aquifer systems where the viscous pressure gradient is significant. The model uses second-order correct space and time approximations to the convective terms. This minimizes the numerical dispersion problem. The model is extremely flexible in providing a wide choice of boundary conditions. These include natural flow in the aquifer, aquifer influence functions around the perimeter of the grid in recognition that the gridded region does not have no-flow boundaries, heat losses into the overlying or underlying impermeable strata, and the wellbore heat and pressure drop calculations coupled to the aquifer flow equations. The limitations of the present techniques are: The use of the second-order correct finite-difference approximations introduces block size and time step restrictions. These restrictions, though considerably less stringent than explicit methods cause, depend upon the magnitude of the dispersivity. The comprehensive nature of the model makes the computer time and storage requirements significant. The model, because of its complexity, is not as efficient in reducing down to solve simpler problems as a specially written model would be. Included in the report are detailed descriptions of the approach used in the model, validation tests of the model, and a typical application of the model. A comparison volume documents the input data requirements, program structure, and an example problem for the model. '

Water-Resources Investigations Report↗

USGS2025

Reservoir thermal energy storage pre-assessment for the United States

Storing thermal energy underground for later use in electricity production or direct-use heating/cooling is a promising, viable, and economical green energy option. Reservoir thermal energy storage (RTES) is one such option, which stores energy in underutilized permeable strata with low ambient groundwater flow rates and more geochemically evolved (e.g. brackish/saline) waters relative to overlying principal aquifer systems. The U.S. Geological Survey has begun assessing RTES potential nationally by focusing on five generalized geologic regions (Basin and Range, Coastal Plain, Illinois Basin, Michigan Basin, Pacific Northwest) across the United States. Hydrogeologic reservoir models are developed for the following eight metropolitan area cities within those regions to evaluate RTES performance across different climates and subsurface conditions: Albuquerque, New Mexico; Charleston, South Carolina; Chicago and Decatur, Illinois; Lansing, Michigan; Memphis, Tennessee; Phoenix, Arizona; and Portland, Oregon. Evaluated metrics include estimated required well spacing, thermal storage capacity, and thermal recovery efficiency through time. Also considered for each reservoir are potential complicating factors, including reservoir depth, thermally driven free convection, and groundwater salinity. This work focuses on direct-use cooling because the need for cooling modern office buildings greatly exceeds that for heating in most parts of the country (Falta and others, 2016); however, the evaluated metrics are also relevant to heating and electricity applications. Results indicate that favorable RTES conditions exist in each region, with the Coastal Plain and Basin and Range being especially favorable for thermal storage capacity, while the Pacific Northwest and Michigan Basin excel at energy recovery for the evaluated cooling application. The results underscore the utility of developing maps of thermal storage capacity, subsurface temperature models, and volumetric estimates of thermal storage capacity to serve as key RTES resource classification standards. Overall, this pre-assessment provides a basic understanding of RTES potential in several cities and geologic regions throughout the country and will aid ongoing thermal energy storage assessment efforts.

Arizona, Illinois, Michigan, New Mexico, Oregon, S↗

USGS2005

Coal-mining seismicity and ground-shaking hazard: A case study in the Trail Mountain area, Emery County, Utah

We describe a multipart study to quantify the potential ground-shaking hazard to Joes Valley Dam, a 58-m-high earthfill dam, posed by mining-induced seismicity (MIS) from future underground coal mining, which could approach as close as ???1 km to the dam. To characterize future MIS close to the dam, we studied MIS located ???3-7 km from the dam at the Trail Mountain coal mine. A 12-station local seismic network (11 stations above ground, one below, combining eight triaxial accelerometers and varied velocity sensors) was operated in the Trail Mountain area from late 2000 through mid-2001 for the dual purpose of (1) continuously monitoring and locating MIS associated with longwall mining at a depth of 0.5-0.6 km and (2) recording high-quality data to develop ground-motion prediction equations for the shallow MIS. (Ground-motion attenuation relationships and moment-tensor results are reported in companion articles.) Utilizing a data set of 1913 earthquakes (M ??? 2.2), we describe space-time-magnitude distributions of the observed MIS and source-mechanism information. The MIS was highly correlated with mining activity both in space and time. Most of the better-located events have depths constrained within ??0.6 km of mine level. For the preponderance (98%) of the 1913 located events, only dilatational P-wave first motions were observed, consistent with other evidence for implosive or collapse-type mechanisms associated with coal mining in this region. We assess a probable maximum magnitude of M 3.9 (84th percentile of a cumulative distribution) for potential MIS close to Joes Valley Dam based on both the worldwide and regional record of coal-mining-related MIS and the local geology and future mining scenarios.

Bulletin of the Seismological Society of America↗

USGS2008

Use of Superposition Models to Simulate Possible Depletion of Colorado River Water by Ground-Water Withdrawal

According to the 'Law of the River', wells that draw water from the Colorado River by underground pumping need an entitlement for the diversion of water from the Colorado River. Consumptive use can occur through direct diversions of surface water, as well as through withdrawal of water from the river by underground pumping. To develop methods for evaluating the need for entitlements for Colorado River water, an assessment of possible depletion of water in the Colorado River by pumping wells is needed. Possible methods include simple analytical models and complex numerical ground-water flow models. For this study, an intermediate approach was taken that uses numerical superposition models with complex horizontal geometry, simple vertical geometry, and constant aquifer properties. The six areas modeled include larger extents of the previously defined river aquifer from the Lake Mead area to the Yuma area. For the modeled areas, a low estimate of transmissivity and an average estimate of transmissivity were derived from statistical analyses of transmissivity data. Aquifer storage coefficient, or specific yield, was selected on the basis of results of a previous study in the Yuma area. The USGS program MODFLOW-2000 (Harbaugh and others, 2000) was used with uniform 0.25-mile grid spacing along rows and columns. Calculations of depletion of river water by wells were made for a time of 100 years since the onset of pumping. A computer program was set up to run the models repeatedly, each time with a well in a different location. Maps were constructed for at least two transmissivity values for each of the modeled areas. The modeling results, based on the selected transmissivities, indicate that low values of depletion in 100 years occur mainly in parts of side valleys that are more than a few tens of miles from the Colorado River.

Scientific Investigations Report↗

USGS2007

Geochemical interpretations of groundwater flow systems

Interest in the geochemistry of groundwater is increasing owing to the great number of current projects involving underground liquid waste storage, artificial recharge of potable water, accidental contamination of groundwater bodies, sanitary landfills, and pollution monitoring. Geochemical techniques used to facilitate the understanding of a groundwater system range from extremely simple to those requiring sophisticated theories, equipment, and procedures. An interpretation of the simple trilinear diagram for samples collected from the Yucatan Peninsula of Mexico provided evidence that the fresh-water body was only a few tens of meters thick and was underlain everywhere by an extensive body of salt water. A geochemical technique that has been used effectively to identify the source of salt water in coastal aquifers is measurement of the carbon-14 concentrations. Carbon-14 has been used in a regional carbonate aquifer to determine the velocity of groundwater movement, rates of chemical reactions, and distribution of hydraulic conductivity. The application of principles of irreversible thermodynamics to groundwater systems provides a basis for constructing models which permit prediction, over both time and space, of changes in head distribution and chemical character of the water resulting from imposed stresses on the system. In essence, proper application of irreversible thermodynamics combines the potential theory of Hubbert with principles of reversible chemical thermodynamics, such as solution of carbonate minerals, to describe and explain controlling chemical reactions and processes of groundwater systems.

Florida, South Carolina↗

USGS2007

Geology of the Yucca Mountain site area, southwestern Nevada

Yucca Mountain in southwestern Nevada is a prominent, irregularly shaped upland formed by a thick apron of Miocene pyroclastic-flow and fallout tephra deposits, with minor lava flows, that was segmented by through-going, large-displacement normal faults into a series of north-trending, eastwardly tilted structural blocks. The principal volcanic-rock units are the Tiva Canyon and Topopah Spring Tuffs of the Paintbrush Group, which consist of volumetrically large eruptive sequences derived from compositionally distinct magma bodies in the nearby southwestern Nevada volcanic field, and are classic examples of a magmatic zonation characterized by an upper crystal-rich (>10% crystal fragments) member, a more voluminous lower crystal-poor (<5% crystal fragments) member, and an intervening thin transition zone. Rocks within the crystal-poor member of the Topopah Spring Tuff, lying some 280 m below the crest of Yucca Mountain, constitute the proposed host rock to be excavated for the storage of high-level radioactive wastes. Separation of the tuffaceous rock formations into subunits that allow for detailed mapping and structural interpretations is based on macroscopic features, most importantly the relative abundance of lithophysae and the degree of welding. The latter feature, varying from nonwelded through partly and moderately welded to densely welded, exerts a strong control on matrix porosities and other rock properties that provide essential criteria for distinguishing hydrogeologic and thermal mechanical units, which are of major interest in evaluating the suitability of Yucca Mountain to host a safe and permanent geologic repository for waste storage. A thick and varied sequence of surficial deposits mantle large parts of the Yucca Mountain site area. Mapping of these deposits and associated soils in exposures and in the walls of trenches excavated across buried faults provides evidence for multiple surface-rupturing events along all of the major faults during Pleistocene and Holocene times; these paleoseismic studies form the basis for evaluating the potential for future earthquakes and fault displacements. Thermoluminescence and U-series analyses were used to date the surficial materials involved in the Quaternary faulting events. The rate of erosional downcutting of bedrock on the ridge crests and hillslopes of Yucca Mountain, being of particular concern with respect to the potential for breaching of the proposed underground storage facility, was studied by using rock varnish cation-ratio and 10 Be and 36 Cl cosmogenic dating methods to determine the length of time bedrock outcrops and hillslope boulder deposits were exposed to cosmic rays, which then served as a basis for calculating long-term erosion rates. The results indicate rates ranging from 0.04 to 0.27 cm/k.y., which represent the maximum downcutting along the summit of Yucca Mountain under all climatic conditions that existed there during most of Quaternary time. Associated studies include the stratigraphy of surficial deposits in Fortymile Wash, the major drainage course in the area, which record a complex history of four to five cut-and-fill cycles within the channel during middle to late Quaternary time. The last 2-4 m of incision probably occurred during the last pluvial climatic period, 22-18 ka, followed by aggradation to the present time. Major faults at Yucca Mountain-from east to west, the Paintbrush Canyon, Bow Ridge, Stagecoach Road, Solitario Canyon, Fatigue Wash, Windy Wash, and Northern and Southern Crater Flat Faults-trend predominantly north, are spaced 1-5 km apart, have bedrock displacements ranging from 125 m to as much as 500 m, and exhibit Quaternary movements of several centimeters to a few meters. Displacements are predominantly down to the west, and bedrock/alluvium contacts commonly are marked by fault-line scarps. The predominant northerly fault trend changes to a more northeasterly trend in adjacent areas south

Nevada↗

USGS2023

Predicting methane emissions and developing reduction strategies for a Central Appalachian Basin, USA, longwall mine through analysis and modeling of geology and degasification system performance

Coal mine methane is a safety concern in active mines due to explosion risk and an environmental concern due to the greenhouse gas (GHG) properties of methane emissions to the atmosphere. Depending on the mine design and operation, structural and stratigraphic characteristics of the geology, and the properties of coal beds affected by mining, a significant amount of methane can be released during coal extraction. These emissions may be low and uniform, but they also can be high and abrupt, if not captured by using pre- and post-mining methods of degasification or not controlled by ventilation during mining. Therefore, emissions should be monitored and predicted accurately for underground safety and GHG reduction. Ventilation and degasification systems should be designed accordingly by taking into account the mine geological properties and the degasification system's performance. This paper presents a comprehensive study to predict emissions and proposes alternatives to reduce emissions in a longwall mine extracting metallurgical coal from the Pocahontas No. 3 coal bed in Virginia (Central Appalachian Basin), USA. The work focused on mining activity in four adjacent panels through analysis and modeling of geology and evaluation of the performance of the methane control system. Results showed that the mine geology contained a significant amount of gas within and around the panel areas, which was controlled by utilizing different degasification methods besides ventilation during mining. The study showed that after pre-mining degasification using fractured vertical wells and in-seam horizontal wells, each panel potentially contained ∼19 MMscf and ∼ 2 MMscf of gas remaining to be handled by the gob gas ventholes (GGVs) and the ventilation, respectively, per acre of mining. It was shown that extending the pre-mining degasification duration of vertical wells by as much as 4 years or drilling more horizontal wells with closer spacing could significantly reduce ventilation and gob emissions during the mining of coal.

Kentucky, Virginia, West Virginia↗

USGS2023

City-scale geothermal energy everywhere to support renewable resilience – A transcontinental cooperation

Cities have important and varying incentives to transform their energy sector to all-electric with low carbon emissions. However, they often encounter a number of impediments when attempting to implement such a change. For example, while urban areas have the highest energy demand-density, cities often lack the space for installing additional energy generation and/or long-duration energy storage systems. Cities also have existing environmental issues from energy sources (e.g., pollution from dust, waste heat or noise) that make residents sensitive to energy infrastructure development. Utilizing power from conventional sources, such as natural gas, biomass and hydropower, which usually are distanced from the urban areas, also make cities more vulnerable to supply disruptions. One promising de-carbonizing energy option for cities focuses on their heating and cooling needs, which constitutes around 1/3 of U.S. and 1/2 of European energy consumption (including industrial processes like drying, pasteurization, etc.; Jadun and others, 2017; EU Commission 2022). If heating and cooling loads can be met by geothermal direct-use technologies, then the need for new electric sources can be greatly lessened. Despite the proven efficacy of geothermal energy as a city/community-scale heating and cooling resource, it is currently only a niche resource in the heating and cooling sector, though has significant potential for future growth. Historically, emphasis has been placed on geothermal electricity generation potential that requires higher temperature (greater than 90 °C) resources at drillable depths, but potentially viable areas are geographically limited and typically well removed from urban centers. Key drivers for investments were represented by greater political interest in renewable electricity production, higher revenues and less effort in distributing the produced energy via grids. In contrast, low-temperature (less than 90 °C) geothermal resources can be used directly for heating and cooling almost everywhere and are cost-effective in urban/suburban settings. In addition, the increased prominence of renewable electricity sources, such as wind and solar onto city-scale electric grids, has led to new urgency around questions of energy storage. Underground thermal energy storage (UTES), wherein surplus or waste heat is stored underground for later use, could present a long-duration energy storage solution. From October 2022 through September 2024, a transcontinental consortium consisting of geological surveys, geoscience organizations, industry representatives and universities aims to develop an understanding of the global potential for city-scale geothermal, proposing guidelines to aid in promoting the economic utilization of low temperature geothermal resources. Efforts will focus on providing city managers and other decision makers with the information needed to evaluate and implement suitable city/community-scale geothermal technologies. Funded by the U.S. Geological Survey’s John Wesley Powell Center for Analysis and Synthesis, this interdisciplinary consortium will showcase tools, datasets, and scientific recommendations to accelerate the broader understanding and adoption of renewable energy systems that access geothermal resources. The collaborative research activities include standardization of nomenclatures, resource description and characterization strategies globally. The results from these activities will be combined with a preliminary climate-driven, city-based energy needs related analysis to perform energy supply/demand matching analysis. The identification of city-specific applications that would benefit from the geothermal technologies provides the basis to up-scale city-specific determinations to regional and national assessments of resource estimates. The city-scale geothermal energy research initiative will ultimately provide the synergies and management analysis that can address benefits, environmental impacts, regulatory frameworks, sustainability, and suitability in retrofitted buildings or new as well as existing heating networks.

Conference Paper↗

USGS1955

Water resources of the Indianapolis area, Indiana

Water used in the Indianapolis area comes from two sources: the White River and tributary streams and the underground reservoirs formed by the underlying glacial drift and limestone. Surface-water sources provide about 60 mgd (million gallons per day) for public supply and an additional 300 mgd is used by private industries and is returned directly to the streams. About 60 mgd is taken from ground-water sources by public water supplies and industries. The total use of water, therefore, is about 420 mgd. The city of Indianapolis and several adjacent urban communities are supplied through the surface-water sources by a private water company, the Indianapolis Water Co. Water is impounded in the Geist Reservoir on Fall Creek. At Broad Ripple, on White River, a low dam is used to divert river water into a feeder canal to a treatment plant. Expansion of the present facilities of this company is in progress. A new reservoir with a capacity about equal to that of Geist Reservoir is being constructed on Cicero Creek, a tributary of the White River. These combined river sources will provide an abundant supply of good water in excess of present demands. This will permit expansion of surface-water use for public, commercial, and industrial supply in the service area of this water company. Industry is the heaviest user of ground water in the area. Of the 56 mgd of ground water pumped in 1952 about 70 percent was used by industry. Agriculture was next with a pumpage of about 15 percent and the remainder or 15· percent was for public and private water supply. The ground water is of relatively uniform composition and temperature. Difficulties in supplying water have occurred and will continue to occur from time to time when demands on ground-water sources are excessively heavy for long periods of time and locally where pumped wells are too closely spaced. Under such conditions ground-water levels decline rapidly and remain depressed for some time. Such a condition may constitute what could be called a water shortage. As the demand for water increases there is need for conservation and wise use of available surface and ground-water supplies.

Indiana↗

USGS1982

An alternative hypothesis for sink development above salt cavities in the Detroit area

Subsidence and sink formation resulting from brining operations in the Windsor-Detroit area include the 1954 sink at the Canadian Salt Company brine field near Windsor, Ontario, and the 1971 sinks at the BASF Wyandotte Corporation brine field at Grosse Ile, Mich. Earlier investigations into both occurrences concluded that the mechanism of sink development consisted of the gradual stoping of poorly supported brine-gallery roof rock to the near surface with subsequent surface collapse. A more recent study attempted to describe the mechanism of sink development in terms of the geometry of a cylindrical chimney formed by stoping of roof rock, the height of a cavity at depth, the depth of overlying rock, and the bulking ratio of the rubble formed during stoping. Persons with extensive experience in solution mining in the Windsor-Detroit area have expressed doubt that the stoping mechanism could fully explain the development of these sinks. Further, they have proposed that the relatively shallow (300-ft-deep) Sylvania Sandstone, in this case, may be responsible for the sinks by a secondary undermining mechanism to be examined in this paper. The mechanism involves downwarping of the beds overlying the salt cavity and development of a shallower cavity in the Sylvania Sandstone by downward migration of cohesionless sand grains from the Sylvania through openings in the disturbed rock to the lower cavity. This study indicates that under natural conditions the Sylvania will not migrate, even in the presence of large underground water flows because the sandstone possesses some cohesion throughout its depth. However, further investigation has formulated a mechanism that could allow the Sylvania Sandstone to loose its cohesion in response to high horizontal stresses. These stresses could be the result of deformation that accompanies general subsidence and (or) of past geologic processes. Included in this study were experimental and analytical investigations. As determined by uniaxial and triaxial testing, the Sylvania Sandstone in the Detroit area has been shown to have low compressive strength. In addition, it exhibits an explosive type failure whereby over 50 percent of the sample is reduced to loose granular sand. As a result of these characteristics, the Sylvania Sandstone can loose its cohesion when subjected to high horizontal stresses. Efforts at mechanically modeling the Sylvania were made to account for the measurements and observations. Linear arch theory was used for an elastic analysis. Linear arch theory predicts two modes of failure: (1) arch crushing, a compressive failure of the upper portion of the arch due to compressive stresses exceeding the compressive strength of the material, and (2) arch collapse, a sagging of the beds due to compressive strains which reduce the arch line to a length less than the original arch length. The arch crushing mode of failure would then yield the loose granular sand as observed in laboratory testing. Arch collapse would simply result in bed sagging without granulation of the sandstone. Arch collapse is favored by thin-bedded material while arch crushing is favored by thick-bedded material. Arch crushing seems to be a likely mode of failure for the Windsor-Detroit sinks. It is believed that after a crushing failure the sand-water slurry (specific gravity 1.2) which exceeds the density of the cavity brine will migrate downward through cracks and open joints eventually reaching the practically limitless open spaces of the rubble column and salt cavity. As the extent of the cavity within the Sylvania increases in depth and width because of sand migration, a critical span will be reached where the immediately overlying upper Sylvania and the overlying Detroit River Dolomite will fail. The collapse will allow a path for the approximately 100 ft of clay to collapse, resulting in a sink as the surface manifestation.

Open-File Report↗

USGS2023

Using DC resistivity ring array surveys to resolve conductive structures around tunnels or mine-workings

In underground environments, conventional direct current (DC) resistivity surveys with a single linear array of electrodes produce fundamentally non-unique inversions. These non-uniqueness and model resolution issues stem from limitations placed on the location of transmitters (TXs) and receivers (RXs) by the geometry of existing tunnels and boreholes. Poor excitation and/or sampling of the region of interest (ROI) can create artifacts and reduce the resolution of the recovered model. To address these problems we propose the use of an ensemble of ring arrays, which are created by placing one or more electrodes in each face (sidewalls, floor, and ceiling) of the tunnel to form a ring of electrodes at each along-tunnel location. Using a series of increasingly complex synthetic models, we assess the benefits of ring arrays and show that they can be used to better constrain the location and shape of anomalous bodies around the tunnel. Although ring arrays significantly improve the resolution of the recovered model, the size of the comprehensive ring array survey increases rapidly with the number of electrodes used. To balance model resolution and survey size, we developed a physics-based survey design methodology. In this methodology, TXs are selected based upon secondary charge accumulations on a test block that is moved throughout the ROI. Although this survey design methodology does not produce a strictly optimal survey, it balances model resolution and survey size in a practical and computationally efficient manner. Since the ring array more accurately estimates the around-tunnel location of targets and ensures that targets on all sides of the tunnel are detected, it is ideally suited to tunnel-based environments. Our results show that only about 6 % "> 6% of the possible TXs and 0.5 % "> 0.5% of the RXs in the comprehensive ring array survey are needed to retain the improvements in resolution. Therefore, economical ring array surveys can be designed for both reconnaissance and target characterization. Following the inversion of the reconnaissance dataset, additional rings can be added to reduce the inter-ring spacing or off-tunnel boreholes can be added to the region around identified anomalies to increase resolution as required.

Journal of Applied Geophysics↗

USGS2002

Results of Hydraulic Tests in Miocene Tuffaceous Rocks at the C-Hole Complex, 1995 to 1997, Yucca Mountain, Nye County, Nevada

Four hydraulic tests were conducted by the U.S. Geological Survey at the C-hole complex at Yucca Mountain, Nevada, between May 1995 and November 1997. These tests were conducted as part of ongoing investigations to determine the hydrologic and geologic suitability of Yucca Mountain as a potential site for permanent underground storage of high-level nuclear waste. The C-hole complex consists of three 900-meter-deep boreholes that are 30.4 to 76.6 meters apart. The C-holes are completed in fractured, variably welded tuffaceous rocks of Miocene age. Six hydrogeologic intervals occur within the saturated zone in these boreholes - the Calico Hills, Prow Pass, Upper Bullfrog, Lower Bullfrog, Upper Tram, and Lower Tram intervals. The Lower Bullfrog and Upper Tram intervals contributed about 90 percent of the flow during hydraulic tests. The four hydraulic tests conducted from 1995 to 1997 lasted 4 to 553 days. Discharge from the pumping well, UE-25 c #3, ranged from 8.49 to 22.5 liters per second in different tests. Two to seven observation wells, 30 to 3,526 meters from the pumping well, were used in different tests. Observation wells included UE-25 c #1, UE-25 c #2, UE-25 ONC-1, USW H-4, UE-25 WT #14, and UE-25 WT #3 in the tuffaceous rocks and UE-25 p #1 in Paleozoic carbonate rocks. In all hydraulic tests, drawdown in the pumping well was rapid and large (2.9-11 meters). Attributable mostly to frictional head loss and borehole-skin effects, this drawdown could not be used to analyze hydraulic properties. Drawdown and recovery in intervals of UE-25 c #1 and UE-25 c #2 and in other observation wells typically was less than 51 centimeters. These data were analyzed. Hydrogeologic intervals in the C-holes have layered heterogeneity related to faults and fracture zones. Transmissivity, hydraulic conductivity, and storativity generally increase downhole. Transmissivity ranges from 4 to 1,600 meters squared per day; hydraulic conductivity ranges from 0.1 to 50 meters per day; and storativity ranges from 0.00002 to 0.002. Transmissivity in the Miocene tuffaceous rocks decreases from 2,600 to 700 meters squared per day northwesterly across the 21-square-kilometer area affected by hydraulic tests at the C-hole complex. The average transmissivity of the tuffaceous rocks in this area, as determined from plots of drawdown in most or all observation wells as functions of time or distance from the pumping well, is 2,100 to 2,600 meters squared per day. Average storativity determined from these plot ranges is 0.0005 to 0.002. Hydraulic conductivity ranges from less than 2 to more than 10 meters per day; it is largest where prominent northerly trending faults are closely spaced or intersected by northwesterly trending faults. During hydraulic tests, the Miocene tuffaceous rocks functioned as a single aquifer. Drawdown occurred in all monitored intervals of the C-holes and other observation wells, regardless of the hydrogeologic interval being pumped. This hydraulic connection across geologic and lithostratigraphic contacts is believed to result from interconnected faults, fractures, and intervals with large matrix permeability. Samples of UE-25 c #3 water, analyzed from 1995 to 1997, seem to indicate that changes in the quality of the water pumped from that well are probably due solely to lateral variations in water quality within the tuffaceous rocks.

Water-Resources Investigations Report↗

USGS2020

Modified GIC estimation using 3-D Earth conductivity

Geomagnetically induced currents (GICs) are quasi-direct current (DC) electric currents that flow in technological conductors during geomagnetic storms. Extreme GICs are hazardous to man-made infrastructure. GICs enter and exit the technological systems, such as the electric power grid, at grounding points, and their magnitudes depend on the currents that flow underground. They are, therefore, a function of the Earth's electrical conductivity, represented at ground level as Earth impedances, as well as the resistance parameters of the power network. Traditional GIC estimation practices are based on Earth impedances obtained from laterally homogeneous or piecewise layered-Earth models. We refer to these methods, collectively, as the 1-D approximation. However, GIC hazard mitigation can be improved with more accurate GIC modeling that takes the spatially heterogeneous Earth's conductivity into account. Here, we propose a modified approximation for GIC estimation that is very similar to the 1-D approximation but is instead derived from empirical 3-D Earth impedances. Our formulation sets up the computation of static, frequency-dependent power line telluric response functions, which, once computed, may be considered part of the power grid system model. These response functions may then be used for historical scenario analysis of GIC hazards and for simplified real-time, albeit approximate, GIC estimation in a power grid. This modest modification to the simpler local field formulation approach avoids real-time integration of geoelectric fields along power lines while taking the realistic 3-D Earth into account in a rigorous manner. Once implemented, the method provides a power grid operator with the benefits of convenience and computational speed for a first look real-time operational GIC hazard assessment. We estimate that the proposed modified 3-D GIC modeling approach produces GIC values that are well within 50% of those obtained with the full-scale power line integration of spatially variable geoelectric fields, for storms comparable in scale to the 2003 Halloween storm, all geological structures, and power lines located in the contiguous United States and other low- to middle-latitude regions.

Space Weather↗

USGS2002

Geologic map of the Yucca Mountain region, Nye County, Nevada

Yucca Mountain, Nye County, Nev., has been identified as a potential site for underground storage of high-level radioactive waste. This geologic map compilation, including all of Yucca Mountain and Crater Flat, most of the Calico Hills, western Jackass Flats, Little Skull Mountain, the Striped Hills, the Skeleton Hills, and the northeastern Amargosa Desert, portrays the geologic framework for a saturated-zone hydrologic flow model of the Yucca Mountain site. Key geologic features shown on the geologic map and accompanying cross sections include: (1) exposures of Proterozoic through Devonian strata inferred to have been deformed by regional thrust faulting and folding, in the Skeleton Hills, Striped Hills, and Amargosa Desert near Big Dune; (2) folded and thrust-faulted Devonian and Mississippian strata, unconformably overlain by Miocene tuffs and lavas and cut by complex Neogene fault patterns, in the Calico Hills; (3) the Claim Canyon caldera, a segment of which is exposed north of Yucca Mountain and Crater Flat; (4) thick densely welded to nonwelded ash-flow sheets of the Miocene southwest Nevada volcanic field exposed in normal-fault-bounded blocks at Yucca Mountain; (5) upper Tertiary and Quaternary basaltic cinder cones and lava flows in Crater Flat and at southernmost Yucca Mountain; and (6) broad basins covered by Quaternary and upper Tertiary surficial deposits in Jackass Flats, Crater Flat, and the northeastern Amargosa Desert, beneath which Neogene normal and strike-slip faults are inferred to be present on the basis of geophysical data and geologic map patterns. A regional thrust belt of late Paleozoic or Mesozoic age affected all pre-Tertiary rocks in the region; main thrust faults, not exposed in the map area, are interpreted to underlie the map area in an arcuate pattern, striking north, northeast, and east. The predominant vergence of thrust faults exposed elsewhere in the region, including the Belted Range and Specter Range thrusts, was to the east, southeast, and south. The vertical to overturned strata of the Striped Hills are hypothesized to result from successive stacking of three south-vergent thrust ramps, the lowest of which is the Specter Range thrust. The CP thrust is interpreted as a north-vergent backthrust that may have been roughly contemporaneous with the Belted Range and Specter Range thrusts. The southwest Nevada volcanic field consists predominantly of a series of silicic tuffs and lava flows ranging in age from 15 to 8 Ma. The map area is in the southwestern quadrant of the southwest Nevada volcanic field, just south of the Timber Mountain caldera complex. The Claim Canyon caldera, exposed in the northern part of the map area, contains thick deposits of the 12.7-Ma Tiva Canyon Tuff, along with widespread megabreccia deposits of similar age, and subordinate thick exposures of other 12.8- to 12.7-Ma Paintbrush Group rocks. An irregular, blocky fault array, which affects parts of the caldera and much of the nearby area, includes several large-displacement, steeply dipping faults that strike radially to the caldera and bound south-dipping blocks of volcanic rock. South and southeast of the Claim Canyon caldera, in the area that includes Yucca Mountain, the Neogene fault pattern is dominated by closely spaced, north-northwest- to north-northeast-striking normal faults that lie within a north-trending graben. This 20- to 25-km-wide graben includes Crater Flat, Yucca Mountain, and Fortymile Wash, and is bounded on the east by the 'gravity fault' and on the west by the Bare Mountain fault. Both of these faults separate Proterozoic and Paleozoic sedimentary rocks in their footwalls from Miocene volcanic rocks in their hanging walls. Stratigraphic and structural relations at Yucca Mountain demonstrate that block-bounding faults were active before and during eruption of the 12.8- to 12.7-Ma Paintbrush Group, and significant motion on these faults continued unt

IMAP↗