bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relation Between Topography and Well Yield in Boreholes in Crystalline Rocks, Sogn og Fjordane, Norway
Authors: Henriksen Helge 
Published: August 2005

AbstractWell data from about 760 wells drilled in lower Paleozoic and Precambrian hard rocks have been integrated in a database with topographic and lithologic data thought to be of importance for well yield. The database is mainly based on already existing well records supplemented by desk studies of maps. The wells were initially assigned to nine hydrogeological settings determined by rock type, and into five hydrogeological settings according to their topographic position. Statistical tests were performed to determine whether the median well yields of these groups were significantly different. Boreholes in valley bottoms and flatlands had higher well yields. The data analysis suggests that the lithologic effect on well yield may be of less importance than topography.
Analysis of Temporal Environmental Isotopic Variation in Ground Water of the Georgia Piedmont
Authors: Rose Seth 
Published: August 2005

AbstractTime‐series analyses were made of environmental tritium (3H) concentrations, the stable oxygen isotopic (δ18O) and major‐ion composition of natural waters from the southeastern Piedmont Province of Georgia. The sampling network consisted of four fractured rock production wells (utilized at variable rates), one regolith monitoring well, two streams, and rainfall. Although the isotopic composition of rainfall was highly variable (−11.8‰≤δ18O ≤−l.l‰ and 2.3 ≤ TU ≤ 125), only minor isotopic variation (δl8O generally ≤ 1.0‰ and 3H generally ≤ 2 TU) was observed during the sampling period (∼ 1 year) within ground water at a given well site. The coefficients of isotopic variation for ground water within the bedrock aquifers (δ18Ocv and 3H cv < 10%) were similar to those of ground water within the shallow regolith (δ18Ocv= 5.6% and 3Hcv= 3.3%).Ground water from the most extensively used production well was nearly isotopically and geochemically invariant throughout most of the year. Other than a 0.3–0.5‰δ18O depletion observed during the late spring and early summer, there were few temporal trends and little to suggest the presence of a seasonal component of recharge within ground water extracted from the fractured bedrock aquifers. This is consistent with the 3H‐modeled mean residence time of this ground water which is ∼ 20–40 years. The isotopic composition becomes well‐homogenized by the time ground water infiltrates a few meters below the water table, and ground‐water pumping does little to alter these mixing processes.
Pump‐and‐Treat Remediation of Heterogeneous Aquifers: Effects of Rate‐Limited Mass Transfer
Authors: Berglund Sten , Cvetkovic Vladimir 
Published: August 2005

AbstractAn analytical solution for the radial mass flux in a stratified aquifer is presented. The solution refers to a simple case of aquifer remediation by the pump‐and‐treat method using one extraction well. Initially, the contaminant mass is distributed between the mobile phase and “subsurface sources,” from which mass is transferred to the ground water by a rate‐limited process. The transport of the dissolved contaminants is assumed to be by advection only. The results show that both the heterogeneity in hydraulic conductivity and the mass transfer process have impact on the predicted cleanup times. The rate of mass transfer and the mass distribution are concluded to be the most important parameters and, therefore, the mass transfer process should be the prime subject of further investigations.
Optimization of Remedial Pumping Schemes for a Ground‐Water Site with Multiple Contaminants
Authors: Xiang Yanyong , Sykes Jon F. , Thomson Neil R. 
Published: August 2005

AbstractThis paper presents an optimization analysis of the remedial pumping design for a contaminated aquifer located in Elmira, Ontario, Canada. The remediation task presented in the paper is to remove two ground‐water contaminant species, NDMA (N‐nitrosodimethylamine) and chlorobenzene, to such extent that the specified ground‐water quality standards are met. The contaminants, NDMA and chlorobenzene, have different initial plume configurations and retardation characteristics. The required quality standard for NDMA is five orders of magnitude smaller than the initial peak concentration. The objective is to minimize total pumping, and the constraints incorporate ground‐water quality requirements on the maximum and the spatially averaged residual concentrations, with contaminant source control being considered. On the combination of simulation and optimization, the results of this study indicate that the performance of an optimization algorithm based on gradient search is controlled by the specified cleanup levels, and that contaminant concentrations can be nonconvex and nonsmooth for some pumping schemes.
Geochemical Reactions During Biodegradation/Vapor‐Extraction Remediation of Petroleum Contamination in the Vadose Zone
Authors: Capuano Regina M. , Johnson Mark A. 
Published: August 2005

AbstractHydrocarbon concentrations in soil water and vapor are generally used to evaluate the progress of biodegradation and vapor extraction of petroleum contamination in the unsaturated zone. This study shows that changes in the inorganic composition of vadose zone water samples can be used to evaluate the reactions that occur in the unsaturated zone during such a remediation effort. Chemical analyses were completed on water samples collected from alluvial sediments contaminated with diesel fuel and gasoline at the Gallatin Farmers Cenex, Belgrade, Montana. The samples were collected from 7 suction lysimeters for 3 months after fertilization, but before vapor extraction, and then for 6 months following the start of vapor extraction. The geochemical reaction progress code SOLMINEQ.88 is used to calculate the aqueous equilibria in the samples and to simulate possible reaction pathways.Reduction in TPH and BTEX concentrations indicated that biodegradation of the petroleum began after fertilization, prior to vapor extraction, and continued after the start of vapor extraction. SO4=, HCO3‐, pH, and PCO2 show large systematic variations with both time and depth. These variations are independent of evaporation, mixing, sample extraction time, and soil moisture content and thus appear to be a direct consequence of bioremediation and vapor extraction. PCO2 is found to be a measure of the effectiveness of vapor extraction. The chemical mass transfer calculations also show that if vapor extraction occurs alone removing CO2 from solution without coupling of a process to buffer the solution pH, large amounts of carbonate minerals could precipitate, significantly reducing sediment permeability. These data suggest that analyses of inorganic compounds in lysimeter samples can be used to evaluate geochemical changes during vadose zone remediation and can be used to improve remediation design.
A Ground‐Water Flow Mathematica Tool Package
Authors: Cheng Alexander H‐D. , Sidauruk Paston 
Published: August 2005

Abstract Mathematica, a symbolic computer mathematics program, is used to construct a tool package for ground‐water flow and contaminant transport simulations. High level, mnemonic functions are designed that allow users to plot type curves, to animate ground‐water flow fields, to perform parameter determination, and to visualize the movement of contaminant cloud.
Integrated Optimal Management of Ground‐Water Pollution and Withdrawal
Authors: Keshari Ashok K. , Datta Bithin 
Published: August 2005

AbstractAn integrated ground‐water management model is formulated as a multivariable constrained nonlinear optimization problem. To simulate the physical and chemical processes occurring within a leaky confined aquifer system, the finite‐difference forms of the flow and transport equations are embedded in the management model. The Hooke‐Jeeves method, a nonlinear programming technique, in conjunction with the exterior penalty function method is used to solve this management model. The suitability and capability of this method to solve the management problems for study areas of different sizes and different numbers of management periods are demonstrated. The performance evaluation of this proposed methodology establishes its potential applicability for the solutions of different kinds of ground‐water management problems. The developed methodology also demonstrates the suitability of the embedding technique to solve a dimensionally large nonlinear ground‐water management problem. The proposed methodology does not require the linking of simulation and optimization models externally. It is shown that global optimality of obtained solutions is dependent on the extensive identification of local optimal solutions and the accuracy in prescribed aquifer characteristics.
Evaluation of the Variations in Borehole Yield From a Fractured Karoo Aquifer, South Africa
Authors: Sami K. 
Published: August 2005

AbstractBoreholes in an interbedded and fractured sandstone/mudstone Karoo aquifer were classified according to their position relative to structural features identified on a photogeologic map. The yields of boreholes located adjacent to dolerite intrusions, or on the limbs of folds where changes in bedding dip occur, were found to be significantly higher than the yields of boreholes located where no structural deformation could be observed. No statistical difference was found between the yields of boreholes located adjacent to faults or along fold axes and those in undeformed sections. No significant correlation exists between yield and saturated depth penetrated, suggesting that borehole productivity is primarily dependent on the permeability of intercepted fractures rather than on borehole depth. Yields from boreholes located in higher order catchments were also considerably greater than yields in first and second order catchments. Yield probability curves have been derived for the different structural features identified. These show that locating boreholes adjacent to dolerite intrusions or changes in bedding dip significantly increases the probability of obtaining a high yielding borehole. The identification of these features from air photos, therefore, provides an economical means of locating boreholes without expensive geophysical surveys.
The In Situ Permeable Flow Sensor: A Ground‐Water Flow Velocity Meter
Authors: Ballard Sanford 
Published: August 2005

AbstractA new technology called the In Situ Permeable Flow Sensor has been developed at Sandia National Laboratories. These sensors use a thermal perturbation technique to directly measure the direction and magnitude of the full three‐dimensional ground‐water flow velocity vector in unconsolidated, saturated, porous media. The velocity measured is an average value characteristic of an approximately 1 cubic meter volume of the subsurface. The sensors are permanently buried in direct contact with the formation at the point where the velocity measurement is to be made. While this deployment strategy means that the approximately $2500 instruments are not recovered, borehole effects which can negatively influence the quality of the measurement are avoided. The sensors can be connected to a data acquisition system which can be monitored remotely, via modem and telephone connection, for extended periods of time. The technology is able to measure flow velocities in the range of 5 × 10‐6 to 1 × 10‐3 cm/s, depending on the thermal properties of the medium in which it is buried.
Modeling Cationic Surfactant Transport in Porous Media
Authors: Hayworth Joel S. , Burris David R. 
Published: August 2005

AbstractLaboratory and field experiments have shown that cationic surfactants can be used to modify aquifer materials, and thereby form zones of enhanced sorption for hydrophobic organic contaminants (HOC's) migrating in ground water. Coupled to a contaminant degradation or removal process, this concept has potential as a remediation technology. In order to apply enhanced sorption in a remediation scheme, an ability to predict the transport and partitioning behavior of cationic surfactants in the subsurface is necessary. In this paper we present the results of a numerical modeling study in which the transport and partitioning behavior of the cationic surfactant hexadecyltrimethylammonium chloride (HDTMA) in porous media is investigated. Modeling of previously published batch and column HDTMA sorption experimental results for Columbus Air Force Base aquifer material indicates that, under certain conditions, kinetic effects will dominate the transport process with slow desorption of HDTMA being the likely rate‐controlling step. The results suggest that a significant departure from equilibrium will exist under natural gradient conditions for the Columbus aquifer material. Low aqueous surfactant concentrations can be expected to persist within a surfactant‐enhanced sorption zone, even after considerable flushing with surfactant‐free ground water. The low aqueous concentration may have implications in terms oftoxicityto microorganisms.
Bench‐Scale Evaluation of Bioaugmentation to Remediate Carbon Tetrachloride‐Contaminated Aquifer Materials
Authors: Mayotte Timothy J. , Dybas Michael J. , Criddle Craig S. 
Published: August 2005

Abstract Pseudomonas sp. strain KG is a denitrifying bacterium that, under iron‐limited conditions and in the presence of sufficient quantities of growth substrate, rapidly transforms carbon tetrachloride (CCl4) to carbon dioxide and nonvolatile products without production of chloroform. Bench‐scale laboratory methods were used to evaluate the feasibility of bioaugmentation with strain KC to remediate aquifer materials from an aquifer of documented CCl4 contamination at Schoolcraft, Michigan. Nine glass columns packed with uncontaminated aquifer materials from the site were used to simulate aquifer conditions. Columns were alternately exchanged with ground water from the site in a rapid (20–30 minute) displacement of the pore fluid, then incubated under static conditions for a period of days to weeks. The exchange and incubation procedure continued until CCl4 removal began to plateau, indicating equilibration of the sorbed CCl4 with CCl4 in the pore fluid. Information obtained during this period was used to evaluate porosity (total and effective) and CCU sorption. In subsequent exchanges, base, acetate, and phosphorus were added to the exchange fluids to create conditions favorable for growth of strain KC and expression of its CCU transformation activity (niche adjustment). Three columns were inoculated with strain KC; three were not inoculated; and three were chemically disinfected with thimersol. Strain KC was transported more rapidly than the average linear velocity of the exchange fluids in the inoculated columns. Protein levels measured in the effluent of the inoculated columns during subsequent exchanges indicated that niche adjustment enabled rapid growth and colonization of the aquifer solids by strain KC. Little or no protein was detected in the effluent of uninoculated columns. CCl4 mass balances on the inoculated, noninoculated, and chemically disinfected columns indicated that niche adjustment and inoculation with strain KC created conditions favorable for CCl4 removal from the aquifer solids. Up to 70% removal of soluble CCl4 (30–50 μg/l) occurred in inoculated columns over a period of seven to nine days.
Using Thermal‐Infrared Imagery to Delineate Ground‐Water Discharged
Authors: Banks William S. L. , Paylor Randall L. , Hughes W. Brian 
Published: August 2005

AbstractOn March 8 and 9, 1992, a thermal‐infrared‐multispectral scanner (TIMS) was flown over two military ordnance disposal facilities at the Edgewood Area of Aberdeen Proving Ground, Maryland. The data, collected by the National Aeronautics and Space Administration, in cooperation with the U.S. Army and the U.S. Geological Survey, were used to locate ground‐water discharge zones in surface water. The images from the flight show areas where ground‐water discharge is concentrated, as well as areas of diffuse discharge. Concentrated discharge is predominant in isolated or nearly isolated ponds and creeks in the study area. Diffuse discharge is found near parts of the shoreline where the study area meets the surrounding estuaries of the Chesapeake Bay and the Gunpowder River. The average temperature for surface water, measured directly in the field, and the average temperature, calculated from atmospherically corrected TIMS images, was 10.6° C (Celsius) at the first of two sites.Potentiometric surface maps of both field sites show discharge toward the nontidal marshes, the estuaries which surround the field sites, and creeks which drain into the estuaries. The average measured temperature of ground water at both sites was 10.7° C. The calculated temperature from the TIMS imagery at both sites where ground‐water discharge is concentrated within a surface‐water body is 10.4° C. In the estuaries which surround the field sites, field measurements of temperature were made resulting in an average temperature of 9.0° C. The average calculated TIMS temperature from the estuaries was 9.3° C. Along the shoreline at the first site and within 40 to 80 meters of the western and southern shores of the second site, water was 1° to 2° C warmer than water more than 80 meters away. This pattern of warmer water grading to cooler water in an offshore direction could result from diffuse ground‐water discharge. Tonal differences in the TIMS imagery could indicate changes in surface‐water temperatures. These tonal differences can be interpreted to delineate the location and extent of ground‐water discharge to bodies of surface water.
A Semianalytical Solution of One‐Dimensional Advective‐Dispersive Solute Transport Under an Arbitrary Concentration Boundary Condition
Authors: Ge Shemin , Lu Ning 
Published: August 2005

AbstractBy employing the principle of superposition, we offer a semianalytical solution for a one‐dimensional advective‐dispersive solute transport equation under an arbitrary concentration boundary condition. The technique is applicable to many other existing analytical solutions of solute transport problems.
Monitoring Networks in Fractured Rocks: A Decision Analysis Approach
Authors: Jardine Karen , Smith Leslie , Clemo Tom 
Published: August 2005

AbstractHydrogeological decision analysis is applied to the design of a performance monitoring network at a waste management facility overlying fractured bedrock. The objective of the monitoring system is to detect contaminants before they reach a regulatory compliance boundary in order to enable early and less costly on‐site remediation, and avoid the potentially more costly consequences of failure. Features in the design of the monitoring network include the number of monitoring wells to be installed and their locations, where in each borehole to position discrete monitoring zones, and how often to take water samples. The decision model identifies the preferred monitoring strategy as the design alternative, among all those considered, that minimizes the sum of the monitoring costs and the expected costs of failure and on‐site remediation. At a given distance from the facility, the highest probabilities of plume detection are obtained when the fractures intersecting the borehole wall that carry the largest flows are monitored. Monitoring intervals centered on fractures with highest aperture, or regions of highest fracture density, yield intermediate values, while intervals located at predetermined depths yield the lowest probabilities of detection. The monitoring scheme with the highest probability of detection is not necessarily the preferred monitoring strategy. For monitoring options that have a higher probability of detection than the preferred monitoring strategy, the higher expected cost of on‐site remediation, when combined with the increased cost of monitoring required to provide the higher probability of detection, can outweigh the reduction in the expected cost of failure brought about by a higher probability of detection. When the probability of contaminants migrating to the compliance boundary is small during the compliance period, changes in the probability of detection brought about by a more intense monitoring effort do not affect the expected cost of failure much; in these instances, the decision model may point to a reduced effort in performance monitoring.
Type‐Curve Matching Using a Computer Spreadsheet
Authors: Cleveland Theodore G. 
Published: August 2005

AbstractThis note shows how to construct and perform a graphical type‐curve analysis using a computer spreadsheet. Formulas are provided to generate the axis shifting behavior that is required for the graphical fit. Arbitrary match points are obtained by trial‐and‐error (or by closed form solution) for use in the calculation of aquifer hydraulic parameters. The analysis is illustrated using a leaky aquifer type curve and a confined aquifer type curve. Macro programming is not required, only data entry and the ability to use plotting features of a computer spreadsheet. The approach can be adapted for parameter estimation using any tabulated type curve.
Analysis of the Deformation of Homogeneous Electrical Fields Over Some Two‐Dimensional Structures
Authors: Srinivas M. , Sundararajan N. 
Published: August 2005

AbstractAn analysis of the deformation of a homogeneous electrical field caused by a long, thin inclined bed, which is of considerable importance in the exploration of ground water and minerals, is presented using the Hilbert transform. The thickness of the bed and the inclination are expressed as a function of the abscissae of the points of intersection of the horizontal and vertical derivatives of the field. The procedure is illustrated with a theoretical example and substantiated with field examples from the fractured Crystalline Basement Complex in Burkina Faso, Africa, and Pre‐Cambrian limestones of the Cuddappah Basin in Andhra Pradesh, India. The results derived from the analytical method are shown to agree well with the ground truth.
Interpretation of Sorption Studies for Compound Isomers or Mixtures
Authors: Soerens Thomas S. , Sabatini David A. 
Published: August 2005

AbstractFor compound mixtures or compounds with two or more differently sorbing isomers which are not analytically distinguished, combined sorption parameters determined in the laboratory are dependent upon the ratio of different compounds or isomers and upon experimental methods and conditions. The purpose of this paper is to mathematically examine the effects of these factors on sorption parameters calculated from batch (shake‐flask) and continuous flow column sorption studies of compound or isomer mixtures. The analysis in this paper helps explain the apparent anomalies between batch and column sorption results in previously published studies of Rhodamine WT (RWT). In batch reactors, the solid: liquid ratio, Rs, has a major effect on batch sorption results. As Rs decreases, partitioning coefficients determined from batch results approach those determined from column results, which is contrary to the trend that may be anticipated for single component analytes. A single column sorption coefficient or retardation factor for multiple constituents does not accurately describe the transport of the individual compounds. The implications of the effects of experimental methods suggest that sorption parameters determined from batch studies for compound or isomer mixtures (e.g., BTEX, combined xylenes, and others) should be interpreted with care. Significant errors in prediction and description of contaminant transport can result if the presence of multiple compounds or isomers is not recognized or if batch or column data for compound or isomer mixtures are misinterpreted.