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Ground-Water Contamination at Wurtsmith Air Force Base, Michigan

Description: From introduction: The U.S. Geological Survey, at the request of the U.S. Air Force, began an investigation of geologic and hydrologic conditions at Wurtsmith Air Force Base in September 1979. The investigation was prompted by the discovery that an underground storage tank containing trichloroethylene (TCE) had leaked, contaminating Base water-supply wells. Subsequent information suggested that the trichloroethylene had moved off-Base.
Date: 1983
Creator: Stark, J. R.; Cummings, T. R. & Twenter, F. R.
Partner: UNT Libraries Government Documents Department

Geology and Ground-Water Resources of Camden County, New Jersey

Description: From introduction: The purpose of this investigation is to collect and interpret the basic hydrologic and geologic data and to appraise and report on the ground-water resources of Camden County. The objectives were to define the thickness and areal extent of the hydrologic units, evaluate the hydraulic characteristics of the aquifers, determine the effect of pumpage on the water levels of the area, define the source of recharge of the aquifers, and to evaluate the chemical quality of the ground water.
Date: June 1976
Creator: Farlekas, George M.; Nemickas, Bronius & Gill, Harold E.
Partner: UNT Libraries Government Documents Department

Hydrogeology of the Buffalo Aquifer, Clay and Wilkin Counties, West-Central Minnesota

Description: From introduction: The objective of this study are to (1) determine the areal extent and thickness of the Buffalo aquifer and the general occurrence of deeply buried aquifers, (2) determine the potential for development of water supplies from wells in the Buffalo aquifer, (3) investigate and discuss annual recharge to the Buffalo aquifer and the potential for artificially recharging the aquifer, (4) determine the chemical quality of water in the aquifer and in area streams, (5) establish a network of observation wells for monitoring water levels and water quality in the aquifer, (6) determine the relationship between the aquifer and the adjacent streams, and (7) update the information on the flow characteristics of the streams. The main focus of this study is on water in the Buffalo aquifer and on flow characteristics of streams.
Date: February 1981
Creator: Wolf, Ronald J.
Partner: UNT Libraries Government Documents Department

Mathematical and geological approaches to minimizing the data requirements for statistical analysis of hydraulic conductivity distribution. Annual report

Description: The following research was completed: refinement of air-pereameter design, calibration; collection of air-flow-rate data at the facies scale; mapping of depositional facies at an outcrop west of Belen, New Mexico; delineation of permeability facies from mapped depositional facies and geostatitistical analysis of air-flow-rate data observed at the facies scale (Sierra Ladrones formation); and evaluation of threshold-crossing theory.
Date: August 1, 1990
Creator: Phillips, F.M. & Wilson, J.L.
Partner: UNT Libraries Government Documents Department

Visualization of micro-scale phase displacement processes in retention and outflow experiments: Non-uniqueness of unsaturated flow properties

Description: Methods to determine unsaturated hydraulic properties can exhibit random and non-unique behavior. The authors assess the causes for these behaviors by visualizing micro-scale phase displacement processes during equilibrium retention and transient outflow experiments. They observe that the drainage process is composed of a fast fingering followed by a slower backfilling. The influence of each these processes is controlled by the size and the speed of the applied boundary step, the initial saturation and its structure and by small-scale heterogeneities. Because the mixture of these micro-scale processes yields macro-scale effective behavior, measured unsaturated flow properties are also a function of these controls. These results suggest limitations on the current definitions and uniqueness of unsaturated hydraulic properties.
Date: March 9, 2000
Partner: UNT Libraries Government Documents Department

A Self-Consistent Approach for Calculating the Effective Hydraulic Conductivity of a Bimodal, Heterogeneous Medium

Description: In this paper, we consider an approach for estimating the effective hydraulic conductivity of a 3D medium with a binary distribution of local hydraulic conductivities. The medium heterogeneity is represented by a combination of matrix medium conductivity with spatially distributed sets of inclusions. Estimation of effective conductivity is based on a self-consistent approach introduced by Shvidler (1985). The tensor of effective hydraulic conductivity is calculated numerically by using a simple system of equations for the main diagonal elements. Verification of the method is done by comparison with theoretical results for special cases and numerical results of Desbarats (1987) and our own numerical modeling. The method was applied to estimating the effective hydraulic conductivity of a 2D and 3D fractured porous medium. The medium heterogeneity is represented by a combination of matrix conductivity and a spatially distributed set of highly conductive fractures. The tensor of effective hydraulic conductivity is calculated for parallel- and random-oriented sets of fractures. The obtained effective conductivity values coincide with Romm's (1966) and Snow's (1969) theories for infinite fracture length. These values are also physically acceptable for the sparsely-fractured-medium case with low fracture spatial density and finite fracture length. Verification of the effective hydraulic conductivity obtained for a fractured porous medium is done by comparison with our own numerical modeling for a 3D case and with Malkovsky and Pek's (1995) results for a 2D case.
Date: January 2, 2004
Creator: Pozdniakov, Sergey & Tsang, Chin-Fu
Partner: UNT Libraries Government Documents Department

Flow channeling and analysis of tracer tests in heterogeneous porous media

Description: Flow and solute transport through porous medium with strongly varying hydraulic conductivity are studied by numerical simulations. The heterogeneity of the porous medium is defined by {sigma} and {lambda}{prime}, which are, respectively, the standard deviation of natural log of permeability values and its correlation range {lambda} divided by transport distance L. The development of flow channeling as a function of these two parameters is demonstrated. The results show that for large heterogeneities, the flow is highly channelized and solute is transported through a few fast paths, and the corresponding breakthrough curves show a high peak at very early times, much shorter than the mean residence time. This effect was studied for a converging radial flow, to simulate tracer tests in a fracture zone or contact-thickness aquifer. It is shown that {sigma}{sup 2}{lambda}{prime} is an appropriate parameter to characterize the tracer dispersion and breakthrough curves. These results are used to study tracer breakthrough data from field experiments performed with nonsorbing tracers. A new procedure is proposed to analyze the results. From the moments of the residence-time distribution represented by the breakthrough curves, the heterogeneity of the porous medium, as characterized by {sigma}{sup 2}{lambda}{prime} and the mean residence time t{sub o}, may be determined.
Date: November 3, 2001
Creator: Moreno, Luis & Tsang, Chin-Fu
Partner: UNT Libraries Government Documents Department

A Conductivity Relationship for Steady-state Unsaturated Flow Processes under Optimal Flow Conditions

Description: Optimality principles have been used for investigating physical processes in different areas. This work attempts to apply an optimal principle (that water flow resistance is minimized on global scale) to steady-state unsaturated flow processes. Based on the calculus of variations, we show that under optimal conditions, hydraulic conductivity for steady-state unsaturated flow is proportional to a power function of the magnitude of water flux. This relationship is consistent with an intuitive expectation that for an optimal water flow system, locations where relatively large water fluxes occur should correspond to relatively small resistance (or large conductance). Similar results were also obtained for hydraulic structures in river basins and tree leaves, as reported in other studies. Consistence of this theoretical result with observed fingering-flow behavior in unsaturated soils and an existing model is also demonstrated.
Date: September 15, 2010
Creator: Liu, H. H.
Partner: UNT Libraries Government Documents Department


Description: The proposed Saltstone Disposal Unit 6 (SDU6) is a larger structure than the SDU4 cells and larger than the disposal units (SDU2, SDU3, and SDU5) currently in use or under construction. The additional capacity provided by SDU6 is desired to reduce life cycle costs and support site accelerated closure goals. The larger size of the planned SDU6 could result in saltstone being placed in thinner lifts as the unit is filled. This study was performed to determine whether thinner layers of saltstone negatively impact the performance of the waste form. A larger number of cold joints could potentially result in increased drying, salt deposition, and surface oxidation. A matrix of samples was prepared to simulate thin pours ranging from 0.5 to 6 inches thick. Each sample was cured for at least 28 days prior to further characterization. Leachability results showed that there is no obvious impact of the number of grout layers on the Leachability Index values for Na and NO{sub 3}. The concentrations of Cr, NO{sub 2}, and C{sub 2}O{sub 4} were below detection limits for all of the leachates. No attempt was made to evaluate the oxidation of these samples since no measureable Cr was leached, although this would appear to indicate that Cr in the samples remained reduced for cold joints with surfaces exposed for approximately four days. The results of hydraulic conductivity measurements showed that the number of cold joints in the samples did not have a significant impact on the measured values for the vertical lift orientation (i.e., when the flow path is perpendicular to the cold joints). For the horizontal lift orientation (i.e., when the flow path is parallel to the cold joints), the number of cold joints in the samples also did not appear to have a significant impact on hydraulic conductivity. The ...
Date: October 2, 2012
Creator: Cozzi, A.; Langton, C. & Fox, K.
Partner: UNT Libraries Government Documents Department

Geologic Controls of Hydraulic Conductivity in the Snake River Plain Aquifer At and Near the Idaho National Engineering and Environmental Laboratory, Idaho

Description: The effective hydraulic conductivity of basalt and interbedded sediment that compose the Snake River Plain aquifer at and near the Idaho National Engineering and Environmental Laboratory (INEEL) ranges from about 1.0x10 -2 to 3.2x10 4 feet per day (ft/d). This six-order-of-magnitude range of hydraulic conductivity was estimated from single-well aquifer tests in 114 wells, and is attributed mainly to the physical characteristics and distribution of basalt flows and dikes. Hydraulic conductivity is greatest in thin pahoehoe flows and near-vent volcanic deposits. Hydraulic conductivity is least in flows and deposits cut by dikes. Estimates of hydraulic conductivity at and near the INEEL are similar to those measured in similar volcanic settings in Hawaii. The largest variety of rock types and the greatest range of hydraulic conductivity are in volcanic rift zones, which are characterized by numerous aligned volcanic vents and fissures related to underlying dikes. Three broad categories of hydraulic conductivity corresponding to six general types of geologic controls can be inferred from the distribution of wells and vent corridors. Hydraulic conductivity of basalt flows probably is increased by localized fissures and coarse mixtures of interbedded sediment, scoria, and basalt rubble. Hydraulic conductivity of basalt flows is decreased locally by abundant alteration minerals of probable hydrothermal origin. Hydraulic conductivity varies as much as six orders of magnitude in a single vent corridor and varies from three to five orders of magnitude within distances of 500 to 1,000 feet. Abrupt changes in hydraulic conductivity over short distances suggest the presence of preferential pathways and local barriers that may greatly affect the movement of ground water and the dispersion of radioactive and chemical wastes downgradient from points of waste disposal.
Date: February 1, 1999
Creator: Anderson, S. R.; Kuntz, M. A. & Davis, L. C.
Partner: UNT Libraries Government Documents Department

Hydraulic Property and Soil Textural Classification Measurements for Rainier Mesa, Nevada Test Site, Nevada

Description: This report presents particle size analysis, field-saturated hydraulic conductivity measurements, and qualitative descriptions of surficial materials at selected locations at Rainier Mesa, Nevada. Measurements and sample collection were conducted in the Rainier Mesa area, including unconsolidated sediments on top of the mesa, an ephemeral wash channel near the mesa edge, and dry U12n tunnel pond sediments below the mesa. Particle size analysis used a combination of sieving and optical diffraction techniques. Field-saturated hydraulic conductivity measurements employed a single-ring infiltrometer with analytical formulas that correct for falling head and spreading outside the ring domain. These measurements may prove useful to current and future efforts at Rainier Mesa aimed at understanding infiltration and its effect on water fluxes and radionuclide transport in the unsaturated zone.
Date: December 29, 2009
Creator: Ebel, Brian A. & Nimmo, John R.
Partner: UNT Libraries Government Documents Department

Predictive Modeling of MIU3-MIU2 Interference Tests

Description: The goal of this project is to predict the drawdown that will be observed in specific piezometers placed in the MIU-2 borehole due to pumping at a single location in the MIU-3 borehole. These predictions will be in the form of distributions obtained through multiple forward runs of a well-test model. Specifically, two distributions will be created for each pumping location--piezometer location pair: (1) the distribution of the times to 1.0 meter of drawdown and (2) the distribution of the drawdown predicted after 12 days of pumping at a discharge rates of 25, 50, 75 and 100 l/hr. Each of the steps in the pumping rate lasts for 3 days (259,200 seconds). This report is based on results that were presented at the Tono Geoscience Center on January 27th, 2000, which was approximately one week prior to the beginning of the interference tests. Hydraulic conductivity (K), specific storage (S{sub s}) and the length of the pathway (L{sub p}) are the input parameters to the well-test analysis model. Specific values of these input parameters are uncertain. This parameter uncertainty is accounted for in the modeling by drawing individual parameter values from distributions defined for each input parameter. For the initial set of runs, the fracture system is assumed to behave as an infinite, homogeneous, isotropic aquifer. These assumptions correspond to conceptualizing the aquifer as having Theis behavior and producing radial flow to the pumping well. A second conceptual model is also used in the drawdown calculations. This conceptual model considers that the fracture system may cause groundwater to move to the pumping well in a more linear (non-radial) manner. The effects of this conceptual model on the drawdown values are examined by casting the flow dimension (F{sub d}) of the fracture pathways as an uncertain variable between 1.0 (purely linear flow) ...
Date: February 1, 2001
Partner: UNT Libraries Government Documents Department

Analysis of Hydraulic Conductivity Calculations

Description: Equations by Marshall and by Millington and Quirk for calculating hydraulic conductivity from pore-size distribution data are dependent on an arbitrary choice of the exponent on the porosity term and a correct estimate of residual water. This study showed that a revised equation, based on the pore-interaction model of Marshall, accurately predicts hydraulic conductivity for glass beads and a loam soil from the pressure-water content relationships of these porous materials.
Date: January 6, 2003
Creator: Green, R.E.
Partner: UNT Libraries Government Documents Department

Laboratory Investigation of Electro-Osmotic Remediation of Fine-Grained Sediments

Description: Electro-osmosis, a coupled-flow phenomenon in which an applied electrical potential gradient drives water flow, may be used to induce water flow through fine-grained sediments. We plan to use this technology to remediate chlorinated solvent-contaminated clayey zones at the LLNL site. The electro-osmotic conductivity (k{sub e}) determined from bench-top studies for a core extracted from a sediment zone 36.4-36.6 m below surface was initially 7.37 x 10{sup -10} m{sup 2}/s-V, decreasing to 3.44 x 10{sup -10} m{sup 2}/s-V, after electro-osmotically transporting 0.70 pore volumes of water through it (195 ml). Hydraulic conductivity (k{sub h}) of the same core was initially measured to be 5.00 x 10{sup -10} m/s, decreasing to 4.08 x 10{sup -10} m/s at the end of processing. This decline in permeability is likely due to formation of a chemical precipitation zone within the core. Water splitting products and ions electromigrate and precipitate within the core; H{sup +} and metal cations migrate toward the cathode, and OH{sup -} from the cathode moves toward the anode. We are now exploring how to minimize this effect using pH control. The significance of this technology is that for this core, a 3 V/cm voltage gradient produced an initial effective hydraulic conductivity of 2.21 x 10{sup -7} m/s, >400x greater than the initial hydraulic conductivity.
Date: February 23, 2000
Creator: Cherepy, N.; Wildenschild, D. & Elsholz, A.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Relative Permeability Upscaling from the Micro-Scale to the Macro-Scale

Description: During this reporting period, shown experimentally that the optical coherence imaging system can acquire information on grain interfaces and void shape for a maximum depth of half a millimeter into sandstone. The measurement of interfacial area per volume (IAV), capillary pressure and saturation in two dimensional micro-models structures has shown the existence of a unique relationship among these hydraulic parameters for different pore geometry. The measurement of interfacial area per volume on a three-dimensional natural sample, i.e., sandstone, has shown the homogeneity of IAV with depth in a sample when the fluids are in equilibrium.
Date: January 29, 2003
Creator: Pyrak-Nolte, Laura J.; Cheng, JiangTao; Yu, Ping; Giordano, Nicholas; Mustata, Mirela; Chen, Diaquam et al.
Partner: UNT Libraries Government Documents Department

Electro-Osmotic Remediation of Fine-Grained Sediments

Description: The coupled-flow phenomenon, electro-osmosis, whereby water flow results from an applied electrical potential gradient, is being used at Lawrence Livermore National Laboratory to induce water flow through deep (25-40 meters below surface) fine-grained sediments. The scoping work described here lays the groundwork for implementation of this technology to remediate solvent-contaminated clayey zones at the LLNL site. The electro-osmotic conductivity (k{sub e}) measured in-situ between two 37 m deep wells, 3 m apart of 2.3 x 10{sup -9} m{sup 2}/s-V is in good agreement with the value determined from bench-top studies on the core extracted from one of the wells of 0.94 {+-} 0.29 x 10{sup -9} m{sup 2}/s-V. Hydraulic conductivity (k{sub h}) of the same core is measured to be 2.03 {+-} 0.36 x 10{sup -10} m/s. Thus, a voltage gradient of 1 V/cm produces an effective hydraulic conductivity of {approx}1 x 10{sup -7} m/s; an increase in conductivity of nearly three orders of magnitude.
Date: November 22, 1999
Creator: Cherepy, N.J.; McNab, W.W.; Wildenschild, D.; Ruiz, R. & Elsholz, A.
Partner: UNT Libraries Government Documents Department

Laboratory and Pilot Scale Evaluation of a Permeable Reactive Barrier Technology for Use at Rocky Flats Environmental Technology Site (RFETS)

Description: Three reactive materials were evaluated to identify the optimum treatment reagent for use in a Permeable Reactive Barrier Treatment System at Rocky Flats Environmental Technology Site (RFETS). The three reactive media evaluated included high carbon steel iron filings, an iron-silica alloy in the form of a foam aggregate, and a pellicular humic acid based sorbent (Humasorb from Arctech) mixed with sand. Each material was tested in the laboratory at column scale using simulated site water. All three materials showed promise for the 903 Mound Site; however, the iron filings were determined to be the most cost effective media. In order to validate the laboratory results, the iron filings were further tested at a pilot scale (field columns) using actual site water. Pilot test results were similar to laboratory results; consequently, the iron filings were chosen for the full scale demonstration of this reactive barrier technology. Design parameters including saturated hydraulic conductivity, treatment residence time, and head loss across the media were provided to the design team in support of the final design.
Date: February 1, 1999
Creator: Dwyer, B.P. & Hankins, M.G.
Partner: UNT Libraries Government Documents Department

Laboratory analysis of soil hydraulic properties of CDBM 2 and CDBM 3 samples

Description: Daniel B. Stephens & Associates, Inc. (DBS&A) was requested by Dr. Alan Stoker of Los Alamos National Laboratory to perform laboratory analysis for properties of CDBM 2 and CDBM 3 samples, as outlined in Subcontract No. 9-XTI-027EE-1. The scope of work included conducting tests for the following properties: Initial moisture content, dry bulk density, and calculated porosity; Saturated hydraulic conductivity; Moisture characteristics; Unsaturated hydraulic properties (calculated); and Transient outflow.
Date: December 1, 1992
Partner: UNT Libraries Government Documents Department

Mathematical and geological approaches to minimizing the data requirements for statistical analysis of heterogeneity: summary technical progress report

Description: This relates to hydraulic conductivity distributions and to aquifer characterization. The following was completed: air permeameter calibration, ``architectural element`` mapping, lithofacies mapping, air permeability measurements at ``architectural element`` scale, depositional environment characterization of Bosque site, quantification of ``architectural element`` scale geometries, and Markovian simulation techniques.
Date: December 31, 1991
Partner: UNT Libraries Government Documents Department

MPDATA: A positive definite solver for geophysical flows

Description: This article is a review of MPDATA, a class of methods for the numerical simulation of advection based on the sign-preserving properties of upstream differencing. MPDATA was designed originally as an inexpensive alternative to flux-limited schemes for evaluating the transport of nonnegative thermodynamic variables (such as liquid water or water vapour) in atmospheric models. During the last decade, MPDATA has evolved from a simple advection scheme to a general approach for integrating the conservation laws of geophysical fluids on micro-to-planetary scales. The purpose of this paper is to summarize the basic concepts leading to a family of MPDATA schemes, review the existing MPDATA options, as well as to demonstrate the efficacy of the approach using diverse examples of complex geophysical flows.
Date: March 1, 1997
Creator: Smolarkiewicz, P.K. & Margolin, L.G.
Partner: UNT Libraries Government Documents Department

A semianalytical approach to spatial averaging of hydraulic conductivity in heterogeneous aquifers

Description: Numerical models of groundwater flow require hydraulic conductivity values to be assigned to the grid blocks covering the flow domain. However, field-measured conductivities tend to be measured at a different scale (usually smaller) than that of the grid blocks. The present paper describes a novel approach for upscaling field values to block-scale, which combines the rigorous result of small-value perturbation analysis with a plausible generalization of the first-order results to large variance. Also the correlation lengths are assumed to be comparable to block size. Steady-state flow through a block of stochastically heterogeneous medium with constant hydraulic head values at the two opposite sides is analyzed. An upscaling rule and relationship is obtained between the local-scale hydraulic conductivity and the expected mean and variance of block-scale conductivity, where the block size is comparable with the correlation scale of the local conductivity field. The rather simple expressions obtained are validated using data from numerical experiments. Furthermore, a generalized spatial power-averaging method to calculate the block-scale conductivity from values of local-scale conductivity is developed, in which the exponent value is given as a function of the ratios of flow domain dimensions to the respective correlation lengths.
Date: October 1, 1997
Creator: Pozdniakov, S.P. & Tsang, C.F.
Partner: UNT Libraries Government Documents Department

On the continuum-scale simulation of gravity-driven fingers with hysteretic Richards equation: Trucation error induced numerical artifacts

Description: The authors consider the ability of the numerical solution of Richards equation to model gravity-driven fingers. Although gravity-driven fingers can be easily simulated using a partial downwind averaging method, they find the fingers are purely artificial, generated by the combined effects of truncation error induced oscillations and capillary hysteresis. Since Richards equation can only yield a monotonic solution for standard constitutive relations and constant flux boundary conditions, it is not the valid governing equation to model gravity-driven fingers, and therefore is also suspect for unsaturated flow in initially dry, highly nonlinear, and hysteretic media where these fingers occur. However, analysis of truncation error at the wetting front for the partial downwind method suggests the required mathematical behavior of a more comprehensive and physically based modeling approach for this region of parameter space.
Date: March 8, 2000
Partner: UNT Libraries Government Documents Department