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In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology petroleum extraction, carbon sequestration, etc.),scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency, Department of Energy Nuclear Regulatory Commission, Department of Agriculture, and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically...
We simulate three types of forced-gradient tracer tests (converging radial flow, unequal strength two well, and equal strength two well) and natural-gradient tracer tests in multiple realizations of heterogeneous two-dimensional aquifers with a hydraulic conductivity distribution characterized by a spherical variogram. We determine longitudinal dispersivities (αL) by analysis of forced-gradient test breakthrough curves at the pumped well and by spatial moment analysis of tracer concentrations during the natural-gradient tests. Results show that among the forced-gradient tests, a converging radial-flow test tends to yield the smallest αL, an equal strength two-well test tends to yield the largest αL, and an unequal...
In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology petroleum extraction, carbon sequestration, etc.),scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency, Department of Energy Nuclear Regulatory Commission, Department of Agriculture, and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically...
Flowmeter-measured hydraulic conductivities from the heterogeneous MADE site have been used predictively in advection-dispersion models. Resulting simulated concentrations failed to reproduce even major plume characteristics and some have concluded that other mechanisms, such as dual porosity, are important. Here an alternative possibility is investigated: that the small-scale flowmeter measurements are too noisy and possibly too biased to use so directly in site-scale models and that the hydraulic head and transport data are more suitable for site-scale characterization. Using a calibrated finite element model of the site and a new framework to evaluate random and systematic model and measurement errors, the following...
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Data presented here were collected in support of analyzing the analytical model PAT (Purge Analyzer Tool). There are manual measurements of well construction, hydraulic, and chemical data for several wells from the Stringfellow Superfund site, Jurupa Valley, California. The hydraulic data includes hydraulic head. Chemical data includes physiocochemical data. Physiocochemical profiles of the well water column were done under ambient and post pumped conditions. There are also continuous measurements of hydraulic head, and the monitoring of the presence of tracers (rhodamine, fluorescein, and brilliant blue dye).
We interpret new chemical and isotopic data from samples collected between October 1998 and March 2002 from the NSF well (also called the Keller well), the only deep well on the summit of Kilauea Volcano, Hawaii. Sample collection followed cleaning of the well, which renewed access to the hydrothermal system very close to the loci of magmatic and fumarolic activity. The chemical and isotopic compositions of the new samples differ remarkably from data published previously. On the basis of the S/Cl ratio and carbon and helium isotopes we conclude that the thermal fluids formed by condensation of magmatic gas into shallow meteoric groundwater. Gas condensation was followed by a complex pattern of basalt dissolution...
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This USGS Data Release represents the synthetic and real data from hydrologically diverse streams used to test the performance and limitations of the Two-tracer Ratio-based Mixing Model (TRaMM) which uses high-frequency measures of two tracers (A and B) and streamflow to separate total streamflow into water from slowflow and fastflow sources. The ratio between the concentrations of the two tracers is used to create a time-variable estimate of the concentration of each tracer in the fastflow end-member. Synthetic data from a groundwater dominated stream and an overland flow dominated stream were used to test the sensitivity of the model to various conditions and tracer concentrations. The sensitivity analysis provides...
We interpret new chemical and isotopic data from samples collected between October 1998 and March 2002 from the NSF well (also called the Keller well), the only deep well on the summit of Kilauea Volcano, Hawaii. Sample collection followed cleaning of the well, which renewed access to the hydrothermal system very close to the loci of magmatic and fumarolic activity. The chemical and isotopic compositions of the new samples differ remarkably from data published previously. On the basis of the S/Cl ratio and carbon and helium isotopes we conclude that the thermal fluids formed by condensation of magmatic gas into shallow meteoric groundwater. Gas condensation was followed by a complex pattern of basalt dissolution...
Fractures that begin and end in the unsaturated zone, or isolated fractures, have been ignored in previous studies because they were generally assumed to behave as capillary barriers and remain nonconductive. We conducted a series of experiments using Berea sandstone samples to examine the physical mechanisms controlling flow in a rock containing a single isolated fracture. The input fluxes and fracture orientation were varied in these experiments. Visualization experiments using dyed water in a thin vertical slab of rock were conducted to identify flow mechanisms occurring due to the presence of the isolated fracture. Two mechanisms occurred: (1) localized flow through the rock matrix in the vicinity of the isolated...


    map background search result map search result map Real and synthetic data used to test the Two-tracer Ratio-based Mixing Model (TRaMM) Data associated with the evaluation of the PAT (Purge Analyzer Tool), Stringfellow Superfund site, Jurupa Valley, California, 2017 Data associated with the evaluation of the PAT (Purge Analyzer Tool), Stringfellow Superfund site, Jurupa Valley, California, 2017 Real and synthetic data used to test the Two-tracer Ratio-based Mixing Model (TRaMM)