bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural Buffers for Sludge Leachate Stabilization
Authors: Makeig Kathryn S. 
Published: March 2006

ABSTRACTLarge quantities of sludge can be disposed of safely by burial in narrow trenches. This paper describes a study to quantify the amount of buffer area around a trenching operation that would allow for the natural soils to stabilize sludge leachate without threatening the ground‐water supplies of surrounding communities. A vertical buffer consists of a thickness of unsaturated soil below the base of the trench. Its thickness is calculated by comparing the cation exchange capacity of the soil with the exchangeable cations in the sludge leachate. Data from metropolitan Washington, D.C. consistently require a vertical buffer of less than 3 feet thick. A minimum of 3 feet of unsaturated soil is recommended as a margin of safety, although no specific studies were performed to reach this value. The horizontal buffer is a strip of land that must be maintained between the trenching operations and the site boundary. Its width can be more than two orders of magnitude greater than the vertical buffer. Its width is based on the nitrogen loading of the soil from the sludge and the mobility of nitrate in the upper aquifer based primarily on hydraulic conductivity and the characteristics of the sludge/soil interaction. An advection‐dispersion model predicts nitrate concentrations for various buffer widths, and is used in conjunction with a specified maximum allowable nitrate concentration to determine a minimum horizontal buffer under certain ground‐water flow conditions.
Advection‐Dispersion Interpretation of Tracer Observations in an Aquifer
Authors: Hoehn Eduard , Roberts Paul V. 
Published: March 2006

ABSTRACTData from field tracer experiments are interpreted to evaluate the adequacy of an advection‐dispersion model for simulating field conditions. A stimulus‐response approach based on chemical reactor theory was applied. Two different pulse stimuli at an injection well resulted in responses in two observation wells located at distances of 8 and 17 m, respectively, from the injection well. The wells are perforated over the entire aquifer thickness of 1–2 m. The behavior of the two conservative tracers agreed closely with each other. Breakthrough response curves revealed extended trailing edges (tailing), especially at the nearer well. A two‐domain model is employed to extend the simple advection‐dispersion equation to account for the observed tailing. Response curves of concentrations were fitted with finite‐difference simulations using the two‐domain model. The simulations using the two‐domain model agreed well with the field observations. The responses at the more distant well were characterized by values of dispersivity equal to or slightly smaller than those at the nearer well.
Statistical Identification of Hydraulic Connections Between the Surface of a Mountain and Internal Mineralized Sources
Authors: Williams Roy E. 
Published: March 2006

ABSTRACTMount Emmons is located near Crested Butte, Colorado. It is the site of a proposed molybdenum mine that would extract ore from within the core of the 12,000‐foot plus peak. AMAX Inc. is proposing to extract the ore body by utilizing a block caving technique that requires a thorough understanding of the hydrology of the mountain.This study was conducted to test the hypothesis that water quality data from various sources can be clustered and grouped into distinct populations that can be correlated with hydrogeologic features mapped on the mountain. Cluster analysis and canonical analysis are applied to mine water quality data, drillhole water quality data, spring‐water quality data and surface‐water quality data. Identified subpopulations indicate the presence or absence of mineralized sources in recharge areas, along flow paths or in discharge areas for the different water quality groups. The statistical analyses in combination with fault‐vein mapping and debris slide mapping facilitate identification of preferential hydraulic connections between the surface of Mount Emmons and internal mineralized zones. The majority of the springs on Mount Emmons were shown to be derived from debris slides. These springs discharge water that meets drinking‐water standards. The statistical analyses in combination with the hydrogeologic mapping indicate that these springs should not be affected significantly by mining. The analyses and hydrogeologic mapping also delineate those ground‐water discharge areas that can be expected to be affected by mining. The delineation of the latter zones is essential to the mining plan; preventative and corrective measures can be implemented in the identified areas in order to assure that negative impacts of mining are avoided.
CULTURE METHODS FOR THE ENUMERATION OF IRON BACTERIA FROM WATER WELL SAMPLES – A CRITICAL LITERATURE REVIEW
Authors: Smith Stuart 
Published: March 2006

Abstract. “Iron bacteria” which are known to occur in water wells are briefly described, along with a history and description of their economic significance. The main concerns of this monograph are the laboratory and culture methods described by the various authors and those currently in practice. A bibliography of the limited valuable literature is provided and commented upon.Species of concern are Gallionella ferruginea and those species of the Leptothrix Sphaerotilus group. Emphasis is on the rapid and reliable identification of these organisms.
A Numerical Model Study of Ground‐Water Contamination from Price's Landfill, New Jersey— I. Data Base and Flow Simulation
Authors: Gray William G. , Hoffman Jeffrey L. 
Published: March 2006

ABSTRACTToxic waste contamination is currently threatening the Atlantic City, New Jersey public water‐supply wells. The geohydrologic data for this region are presented and organized into a format suitable for a numerical model study of the contamination problem. Presentation of the data in light of numerical work reveals the importance of good estimates of boundary conditions, historical pumping records, reliable water‐quality data, accurate well logs, and reasonable parameter estimates. One set of measured head data is simulated.
A Numerical Model Study of Ground‐Water Contamination from Price's Landfill, New Jersey — II. Sensitivity Analysis and Contaminant Plume Simulation
Authors: Gray William G. , Hoffman Jeffrey L. 
Published: March 2006

ABSTRACTA numerical model of flow and transport in the vicinity of Price's Landfill and the Atlantic City public water‐supply wells is used to estimate the extent of the existing contamination problem. Model parameters such as boundary conditions, pumping rates, permeability, and dispersivity are varied to demonstrate the sensitivity of the model to these quantities. A historical simulation of the past ten years of contamination is obtained and two schemes for remediation of the contamination problem are compared. In the light of this work, additional data requirements are revealed.
Field Determination of Aquifer Thermal Energy Storage Parametersa
Authors: Parr A. David , Molz Fred J. , Melville Joel G. 
Published: March 2006

ABSTRACTDetermination of the potential of a specific confined aquifer as an effective thermal energy storage medium requires thorough knowledge of the geochemical, thermodynamic, and hydraulic properties of the aquifer and its confining layers. A series of laboratory and field studies must be performed in order to determine the fundamental parameters. Procedures and analyses of a series of tests for a confined aquifer near Mobile, Alabama were completed prior to an aquifer thermal energy storage experiment. Parameters determined were: the regional gradient; vertical and horizontal permeabilities of the storage aquifer; horizontal dispersivity of the storage aquifer; vertical permeability of the confining layers; and thermal conductivities, heat capacities, and chemical characteristics of the aquifer matrix and native ground water.
Application of Resistivity Surveys to Regional Hydrogeologic Reconnaissance
Authors: Stewart Mark , Layton Michael , Lizanec Theodore 
Published: March 2006

ABSTRACTVertical electrical soundings using DC resistivity methods have been completed along over 60 miles of survey lines in southwest Florida. The resistivity soundings were obtained in order to outline major hydrogeologic features as part of a regional hydrogeologic investigation covering approximately 400 square miles. The two significant hydrogeologic features which can be effectively mapped on a regional scale by DC methods are the presence of shallow, high resistivity limestones associated with late Tertiary reef complexes, and the approximate depth to waters with TDS concentrations well above the potable water limits. The reef limestones commonly exhibit very high transmissivities and are potential sites for ground‐water development. The approximate thickness of potable waters allows resource investigations to be limited to the most promising areas and a rough assessment of the total resource to be made for long‐term planning. The interpretation and mapping of the resistivity section is accomplished through published resistivity inversion and computer graphics programs. This automated data processing produces resistivity maps and sections without requiring extensive geophysical training of the interpreter. The automatic interpretations compare well with more traditional master curve interpretation procedures, and have the same limitations with equivalence of solutions and geologic correlation, but are produced with considerably less effort.
The Rainfall/Water‐Table Level Relationship of an Unconfined Aquifer
Authors: Viswanathan M. N. 
Published: March 2006

ABSTRACTThe soil parameters that determine the infiltration rates of a shallow unconfined coastal aquifer due to rainfall were obtained using the recursive least squares method. The parameters were predicted by minimizing the mean square error between the estimated and measured water‐table levels in a bore hole. The parameters λt, a drainage factor, βt, a parameter which accounts for external disturbances, and αt, a set of parameters which determine the infiltration rates due to rainfall, were all treated as time‐dependent variables. Their variation is traced by introducing a “forgetting factor” in the algorithm used to determine the parameters. The parameters were determined using rainfall and water‐table levels for the year 1979 at a bore hole. The parameters βt and αt varied considerably over the period of time and λt remained constant. From the parameters obtained, it appears that most of the recharge due to rainfall takes place within the first two days of the event. After two days there is very little variation in the water‐table level due to rainfall although there is a slight drop on the third, fourth and fifth day, presumably due to the escape of entrapped air beneath the water‐table level.
THE APPLICATION OF A MICROCOMPUTER IN THE ANALYSIS OF PUMPING TEST DATA IN CONFINED AQUIFERS
Authors: Dumble Peter , Cullen Kevin T. 
Published: March 2006

Abstract.With an Apple II microcomputer it is possible to rapidly generate and graphically compare theoretical time‐drawdown curves with field data from pumping tests in confined aquifers. This technique has the advantage over standard curve‐matching methods in that any solution can be tested over the complete range of field data.
AQUIFER MODELING WITH A HANDHELD CALCULATOR — AQMODL
Authors: Rayner Frank A. 
Published: March 2006

AbstractAQMODL is an analytical mathematical aquifer modeling program for the HP‐41C handheld programmable calculator. It does not require any written instructions for its use. It guides the operator through its use and prevents operator error. It is designed so that it can be used by anyone only basically familiar with the operation of the HP‐41C calculator, and with aquifer modeling.There are no special key assignments, and no special data preparation or storage operations or any other prior preparation necessary before running AQMODL, simply XEQ AQMODL and follow the calculator’guidance.AQMODL can be used to model simple or complex single aquifer situations. It considers any regional change (rising or falling) in water level not necessarily associated with the development being modeled. It also models the aquifer's water‐level gradient.Sixty pumping and/or recharge wells can be entered into the model, and the resultant change in water level and water‐level elevation determined at an unlimited number of observation points in the aquifer.
GROUND‐WATER MODELING WITH AN INTERACTIVE COMPUTER
Authors: Bloomsburg G. L. , Rinker R. E. 
Published: March 2006

Abstract. A large finite element program has been adapted to a PDP‐11/23 minicomputer to obtain the advantages of an interactive computer system. The program used is UNSAT2, a code for unsteady, saturated and/or unsaturated flow of ground water. The advantages and disadvantages of this type of system in terms of the potential for its use in mine hydrology and related areas are considered. Some of the advantages of this interactive system are: (1) ease of data input by the use of a digitizer; (2) the opportunity to review all output files and to select for printing only those of interest; and (3) the opportunity to change the physical boundaries of a problem at any desired time to make use of new information as a project progresses. This feature is particularly useful in mine‐related water inflow predictions. This characteristic facilitates the simulation of flow into a vertical mine shaft as the shaft is being developed. A problem presented to demonstrate this feature illustrates some of the above advantages. The major disadvantage is increased computational time. However, the authors believe that this disadvantage may not be particularly great because many organizations are not required to cost‐account time on a minicomputer whereas this may not be the case for large machines.
HP41C AND TI59 PROGRAMS FOR ANISOTROPIC CONFINED AQUIFERS
Authors: Parr A. David , Melville Joel G. , Molz Fred J. 
Published: March 2006

Abstract. Programs are presented for the HP41C and TI59 programmable calculators for determining the ratio of horizontal to vertical hydraulic conductivity in anisotropic confined aquifers from pumping test data or for calculating drawdown given the aquifer parameters. The programs, based on Hantush's drawdown equations (1961), eliminate the need to perform triple interpolation in obtaining the drawdown correction factor given in tabular form by Weeks (1969). The programs are illustrated by example.
Experiments to Assess the Hydraulic Efficiency of Well Screens
Authors: Clark L. , Turner P. A. 
Published: March 2006

ABSTRACTThe hydraulic properties of commercial well screens were investigated to determine which screen design features affected head loss. The test program began with laboratory experiments and continued as a field‐scale experiment with the installation of a well field in the Thames Valley Gravel Aquifer.The laboratory experiments indicated that, for all practical purposes, the head loss attributable to all of the screens tested was negligible. The experimental head loss, however, did vary from screen to screen, particularly at high intake velocities, and the screens could be ranked on the basis of their hydraulic efficiencies. This efficiency hierarchy is explained tentatively in terms of the screen construction methods and slot geometry. The field experiments showed that the hydraulic performance of all well screens is independent of screen design provided that the open area of the screen is above about 10%. The field experiments also indicated that the development capacity of a screen in a gravel aquifer is not wholly dependent on screen design, but that progressive development does increase the hydraulic efficiency of a well.
Aquifer Tests and Well Field Performance, Scioto River Valley, Ohio: Part Ia
Authors: Norris Stanley E. 
Published: March 2006

ABSTRACTBased on 13 aquifer infiltration tests at 11 sites, aquifer transmissivity ranged from 17,000 to 40,000 square feet per day, and the streambed infiltration rate ranged from 0·06 to 0·19 million gallons per day per acre along a seven‐mile reach of the Scioto River in south‐central Ohio. Despite these wide ranges, the sand and gravel aquifer, 40 to 65 feet thick, underlying 10–20 feet of river alluvium south of the glacial boundary, is fairly homogeneous due largely to the absence of till interbeds.Performance of a major well field designed on the basis of the tests has been about as predicted, validating the techniques of data collection and analysis.At each site, a well for pumping was drilled on the floodplain, 150 to 750 feet from the river, and an array of observation wells was installed on lines extending through the pumped well, one line perpendicular to the river and the other parallel.Values of drawdown measured in the observation wells at the end of constant‐rate pumping periods, usually of three days duration, were used to determine line‐source distance and aquifer transmissivity. The rate of streambed infiltration and the streambed‐leakage factor, the latter term relating the infiltration rate to drawdown beneath the stream, also were determined at all but one site. Drive‐point wells installed in the riverbed, or along the near bank, in the vicinity of the pumped well were used to determine drawdown beneath the river due to pumping.
Ground‐Water Model for a Thick Fresh‐Water Lens
Authors: Liu Clark C. K. , Lau L. Stephen , Mink John F. 
Published: March 2006

ABSTRACTThe Pearl Harbor aquifer, an important ground‐water resource for southern Oahu, Hawaii, contains an enormous fresh‐water lens, up to 300 m (1,000 ft) thick, floating above saline water. The upper boundary of the fresh‐water lens is confined near the coast and phreatic inland, whereas its lower boundary is not confined. A finite‐difference flow model was used to simulate the Pearl Harbor aquifer system. The location of the fresh‐water/salt‐water interface, which constitutes the lower boundary of the flow system model, was estimated by Hubbert's formula. Known geohydrologic boundaries and aquifer parameters were also simulated. First, formation of the lens by filling the aquifer with fresh water from natural recharge was simulated to reconstruct the initial conditions before exploitation of the lens and to partially calibrate the model against the hydraulic‐head distribution in 1879. The model then was calibrated fully by simulating the lens’reponse to actual historical pumping patterns covering a time span of 100 years (1880 to 1980). Simulated heads compared favorably with the observed heads over time and space. The calibrated flow model may serve as a useful tool in the management of the Pearl Harbor aquifer.
Ground‐Water Systems Simulation by Time‐Series Techniques
Authors: Houston J.F.T. 
Published: March 2006

ABSTRACTTime‐series techniques have been widely used in economic and environmental contexts. This paper explores their use in ground‐water systems. The basic techniques are considered in relation to hydrogeology and two case histories show their application to real systems. Water level fluctuations in a well field are shown to be dependent upon pumping rates and prior rainfall and can be simulated by a multiple linear regression model. The rate of dewatering of a mine is shown to be dependent upon pumping rates and prior rainfall and can be simulated by a multiple linear regression model. The rate of dewatering of a mine is shown to be dependent upon antecedent mine size and rainfall, and can also be simulated by a multiple linear regression model. Such models can be used for forecasting and control of the ground‐water systems, and once formulated are ideally suited to the management of ground‐water systems where more costly and complex methods cannot be used.
Geophysical Logging in Carbonate Aquifersa
Authors: MacCary L. M. 
Published: March 2006

ABSTRACTSome logging methods are inherently superior to others for the analysis of limestone and dolomite aquifers. Three such systems are the density, neutron, and acousticvelocity logs.Relative percentages of limestone and dolomite, average matrix (grain) densities of the rock mixtures, and porosity of the rock mass can be calculated from density, neutron, and acoustic‐velocity logs. Wells drilled before the 1960's generally were logged with an uncalibrated neutron tool. In some instances, the resultant curve can be empirically calibrated.With supporting data from resistivity logs, apparent water resistivity (Rwa) can be estimated. Depending on rock and mud resistivities, the two most useful resistivity curves for water‐quality studies are the deeply‐focused laterolog and the induction log. For older wells, the standard electric log may be used, if the drilling mud is not salt‐saturated.Rwa contour maps derived from geophysical data are useful to outline areas of recharge, direction of probable ground‐water flow, and location and salinity of brine areas. Another useful application of well logs is estimation of ground‐water temperature. These temperatures are obtained from maximum‐reading thermometer data that generally are recorded on each logging run. Maps of porosity can be used to outline potential areas for completing large‐yield wells.
Aquifer Tests and Well Field Performance, Scioto River Valley, Ohio: Part IIa
Authors: Norris Stanley E. 
Published: March 2006

ABSTRACTThe streambed‐leakage factor ranged from 0.11 to 1.68 million gallons per day per acre per foot of head loss. Most values for the streambed infiltration rate and the streambed‐leakage factor for six tests before 1970 were higher than for six tests in 1976–79, suggesting a change in streambed permeability in the intervening time.A well field to serve a government‐owned uranium enrichment facility, consisting initially of 4 wells, later increased to 15 wells, was designed to yield up to 20 million gallons per day. The wells are on a line parallel to the river at distances from the stream ranging from 122 to 330 feet. Distance between wells ranges from 190 to 303 feet. Specific capacities of the wells, based on 24‐hour acceptance tests, ranged from 63 to 147 gallons per minute per foot of drawdown and averaged 100 gallons per minute per foot of drawdown. By late Summer of 1976, pumpage from all 15 wells ranged from 12 to 15 million gallons per day. Drawdown was about as expected, based on design criteria developed from the aquifer tests, except that pumping levels were lower than expected in the Fall and Winter of 1976–77, resulting from low streamflow and low river temperature.
LET THE MATTER DROP!: THE ROOTS OF WASTE DISPOSAL PROBLEMS
Authors: Donovan R. Nowell , Pettyjohn Wayne A. 
Published: March 2006

Abstract. Observations on the collapse of a medieval castle built on an artificial mound testify that contemporary slippage was adroitly accommodated by building adjustments. However, 300 years of continuous usage without an effective waste disposal system eventually caused the latrine tower to collapse.
Ground‐Water Flow Model Determinations of Areal Hydrogeology and Geology
Authors: Pennequin Didier F. E. 
Published: March 2006

ABSTRACTThe two‐dimensional ground‐water flow model developed by Trescott et al. (1976) was used to determine several important parameters needed to compute the ground‐water flow component to and from Lake Wingra, Madison, Wisconsin; these include horizontal hydraulic conductivity (Kh), ratio of horizontal hydraulic conductivities between two layers (Kh1/Kh2), average anisotropy of the sediments in each layer (Kh/Kv), and average depth of interaction between a lake and an aquifer. In addition to gaining hydrogeologic information, the model was used successfully to estimate general geologic relationships (i.e., location and configuration of geologic contacts) in part of the northeast shore area of Lake Wingra.