bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of a Ground‐Water Sampler for Collecting Volatile Organics and Dissolved Gases in Small‐Diameter Wellsa
Authors: Johnson Richard L. , Pankow James F. , Cherry John A. 
Published: March 2006

ABSTRACTA sampling device is described which collects ground‐water samples containing volatile organic compounds and dissolved gases. The device protects the samples from volatilization losses from the time of collection until the time of analysis. It can be produced in a wide range of sizes and allows access to wells with inside diameters as small as one centimeter. The sampler is designed to be lowered in a well to the desired depth, depressurized to slightly below the in situ pressure to allow entry of the sample, and then repressurized prior to being returned to the surface. During collection and storage, the sample is exposed only to copper and stainless steel. An optional quartz prefilter can also be used. Crimping sections at either end of the sample reservoir seal the pressurized sample during its return to the laboratory. The sampler is designed to be interfaced to analytical instruments for the direct, quantitative transfer of all analytes.
Seismic Reflection Study of a Shallow Aquifer During a Pumping Test
Authors: Birkelo Bradley A. , Steeples Don W. , Miller Richard D. , Sophocleous Marios 
Published: March 2006

ABSTRACTSeismic reflection surveys were used to follow the drawdown in a shallow aquifer during a pumping test. Using severe analog low‐cut filters and 1/4‐m geophone spacings, 335 Hz reflections were obtained from the top of the saturated zone 2.7 m deep. The reflections moved down in time as the saturated zone dropped in response to pumping. The dominant frequency and bandwidth both dropped during pumping indicating a more diffuse reflecting boundary. Slight pullups of reflectors at specific locations on the CDP sections may indicate a higher elevation of the capillary fringe and therefore finer sediments in those locations. Other potential applications of this technique include mapping cones of depression and detecting and delineating perched‐water tables.
An Analysis of Hillside Seepage
Authors: Melville Joel G. , Sims Paul N. 
Published: March 2006

ABSTRACTA steady‐state hillside seepage problem is solved analytically. Subject to the Dupuit‐Forchheimer assumption, one‐dimensional seepage with uniform recharge over an inclined impervious bed is analyzed. Results are presented graphically showing the profile dependence on a single parameter. Properties of the profiles arc investigated. Profiles are also calculated numerically and plotted to improve the physical interpretation.
The Use of Marine Electromagnetic Conductivity as a Tool in Hydrogeologic Investigations
Authors: Duran Philip B. 
Published: March 2006

ABSTRACTField procedures for collecting marine electromagnetic (EM) conductivity data were developed by the U.S. Geological Survey as part of a hydrogeologic investigation of the Delaware River shipping channel. Eighty miles of marine EM data collected along the border between Pennsylvania and New Jersey were used to help interpret results from high‐resolution, continuous seismic‐reflection surveys done in the Summer of 1984.Comparison of EM data with lithologic logs from river borings showed a direct relationship. EM conductivity of sand or bedrock ranged from 4 to 10 millimhos per meter (mmhos/m). Extensive clay beneath the shipping channel generally gave readings exceeding 20 mmhos/m. Conductivity readings over silts were almost always between these values (11 to 20 mmhos/m). This relation was used to help interpret the continuous seismic‐reflection data.
Gravity Modeling of the Brimfield Township Buried Valley and Associated Aquifer, Portage County, Ohio
Authors: Culek Thomas E. , Palmer Donald F. 
Published: March 2006

ABSTRACTA detailed gravity survey of 295 points was conducted in Brimfield Township, Ohio to map buried bedrock topography with a higher degree of resolution than was possible by well data alone. The survey included a subset of 40 stations where both gravity and bedrock depth were determined. Partial correlation analysis allowed identification of a regional gravity trend, and multiple linear regression led to quantitative estimates of depth to bedrock throughout the surveyed area in a manner different from the standard method of gravity interpretation that employs models of different shapes, sizes, and density contrasts. Glacial sediments range in thickness from 10 to 150 feet, with the thickest portions generally over the axis of the buried valley. Some variations in predicted versus measured bedrock depth may be a function of variation in density of the glacial sediments or of topographic effects of the buried bedrock surface. The results of the analysis led to an improved estimate for the bedrock elevation and thickness of valley fill. The interpretation has implications with regard to the volume of glacial sediments in the area and their potential productivity as sources of ground water in the future.
Analysis of Steady‐State Salt‐Water Upconing with Application at Truro Well Field, Cape Cod, Massachusetts
Authors: Reilly Thomas E. , Frimpter Michael H. , LeBlanc Denis R. , Goodman Alvin S. 
Published: March 2006

ABSTRACTSalt‐water upconing describes the phenomenon where salt water is transported vertically upward under a well in response to pumpage in a fresh‐water aquifer underlain by salt water. Sharp interface methods have been used successfully to describe the physics of upconing. A finite‐element model is developed to simulate a sharp interface for determination of the steady‐state position of the interface and maximum permissible well discharges. The model developed is compared to previous published electric‐analog model results of Bennett and others (1968). Both methods are applied to a test case at Truro, Massachusetts, where maximum permissible discharges are determined by the finite‐element model to range from 0.47 to 1.05 cubic feet per second for the Test Site No. 4 location.
Hydrogeology of an Alkaline Fly Ash Landfill in Eastern Iowa
Authors: Le Seur Spencer Linda , Drake Lon D. 
Published: March 2006

ABSTRACTThe hydrogeology and chemical quality of the shallow ground‐water regime at a coal fly ash landfill was investigated near Montpelier, Iowa. An embankment dam retains the two‐hectare deposit of silt‐sized alkaline coal fly ash in an upland ravine. The fly ash landfill was operated between 1964–;1973 and was subsequently capped with a thin loess layer and seeded to pasture. The ash is underlain by loess, over clay‐rich till, over sandstone. Ground water now saturates the lower one‐half of the ash.Nineteen shallow monitoring wells were installed around and within the landfill. Sampling in 1983–;1984 was conducted for water levels, temperature, pH, alkalinity, specific conductance, calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), sulfate (SO42−), chloride (Cl−), arsenic (As), and selenium (Se).Calculated ion balances for 30 analyses had an error of less than 4%. Native loess‐derived ground water of a calcium bicarbonate type enters the landfill, and then shifts to a calcium sulfate type. A distinct leachate plume presently extends at least 46 meters downgradient from the landfill, passing under and through the dam, then discharging into a small pond. SO42− and Se concentrations in the plume exceed EPA drinking‐water standards, and trace As was detected.Although ground‐water pH increased after entering the landfill, bicarbonate alkalinity declined. Results of equilibrium solubility calculations suggest that this condition evolved from calcite supersaturation within the landfill, precipitating calcium carbonate. Dissolution of calcium and magnesium oxides on the glassy fly ash spheres sustains the highly alkaline leachate strength.
Ground‐Water Contamination Near a Uranium Tailings Disposal Site in Colorado
Authors: Goode Daniel J. , Wilder Russell J. 
Published: March 2006

ABSTRACTContaminants from uranium tailings disposed of at an active mill in Colorado have seeped into the shallow ground water onsite. This ground water discharges into the Arkansas River Valley through a superposed stream channel cut in the resistant sandstone ridge at the edge of a synclinal basin. In the river valley, seasonal surface‐water irrigation has a significant impact on hydrodynamics. Water levels in residential wells fluctuate up to 20 ft and concentrations of uranium, molybdenum, and other contaminants also vary seasonally, with highest concentrations in the Spring, prior to irrigation, and lowest concentrations in the Fall. Results of a simple transient mixing cell model support the hypothesis that lateral ground‐water inflow, and not irrigation recharge, is the source of ground‐water contamination.
Monitoring Moisture Migration in the Vadose Zone with Resistivity
Authors: Kean William F. , Waller Muriel Jennings , Layson H. Richard 
Published: March 2006

ABSTRACTStudies of moisture migration in the vadose zone were conducted at four field sites using a reverse Schlumberger resistivity array. Gravimetric moisture measurements on soil samples taken at each of the field sites were made to a maximum depth of 1.83 meters, and these results were correlated with resistivity values. Tensiometer measurements were also taken at two of the four sites. The soils at the sites have combined clay and silt content (less than .0625 mm grain size) which varies from 13% to 84%. Three of the sites are underlain by sand or gravel in the unsaturated zone. The fourth site has fractured but relatively impermeable shales and siltstones under the surface soils. Depths to water table varied from 1.58 m to 13.7 m. Resistivity and gravimetric moisture measurements were carried out prior to the addition of water to the surface, and following the application of water, either by watering of the site (at two sites) or during and after rainfall events (at two sites). Monitoring was carried out for periods of one to three weeks. Results indicate that (1) moisture is retained for long periods of time in clay/silt‐rich soils; (2) moisture migration is slow below a moist soil zone and is not readily detected by surface resistivity measurements; and (3) near‐surface moisture changes can be defined by surface resistivity.
Representative Sampling of Ground Water from Short‐Screened Boreholes
Authors: Barber C. , Davis G. B. 
Published: March 2006

ABSTRACTBoreholes terminated with a short (1–3 m) length of screen are often used in ground‐water quality monitoring, although to obtain representative samples, pumping is often required to overcome the effects of stagnant casing storage. Methods for estimating pumping time prior to sampling from a pumped discharge, presented graphically and in summary equations, show that for most requirements, pumping time (ta) to purge well storage (where mixing of casing storage and ground water takes place within the casing) or to overcome casing storage effects (where little mixing occurs within the casing) is given by
image
Here V is the volume of well storage, Q is the average pumping rate, and m is given by
image
where Ct, Cg, and Cc are concentrations of some substance in pumpage, and ground water, and the initial concentration in casing storage, respectively. In boreholes which have been developed and which are regularly pumped and where a relative sampling error of 2.5% is considered to be acceptable, then m has a value of 0.1. Pumping time then equates to the time necessary to pump 2.3 volumes of well storage from the borehole.Laboratory and field evaluations using boreholes in transmissive and low permeability formations generally validate the theoretical approach. The theory can be used as a basis for estimating and optimizing pumping times for monitoring programs where ground‐water samples are recovered from short‐screened boreholes. Additionally, the theory allows the determination of an optimum pumping rate.
Leachate Generated by an Oil‐and‐Gas Brine Pond Site in North Dakota
Authors: Murphy Edward C. , Kehew Alan E. , Groenewold Gerald H. , Beal William A. 
Published: March 2006

ABSTRACTTwo unlined ponds were used for holding and evaporation of brines produced with oil and gas at a well site in north‐central North Dakota. The brine‐evaporation ponds were in use from 1959 up to the late 1970s when they were backfilled and leveled. Continued salt‐water migration at this site since closure has decreased crop yields in surrounding fields and has killed trees in a shelterbelt within an area of approximately 10 acres.An apparent resistivity survey delineated a 360,000‐ft2 area of extremely low resistivity. Isoconcentration maps indicate that a highly saline leachate plume extends laterally in a 500‐foot radius around the ponds and vertically to a depth of 70 feet below the surface.Ground‐water recharge at this site is low because of the semiarid climate and the low hydraulic conductivity of the near‐surface sediments and, as a result, very little flushing of the brine from the sediment beneath the ponds has occurred. Pore water within the unsaturated zone beneath the reclaimed ponds contains essentially the same ionic concentrations as that: of brine impounded in these pits 10 to 25 years ago.Based upon the results of this research, we estimate that brine leachate will continue to migrate at slow rates from this site for tens and possibly hundreds of years if no action is taken. The construction of a mound over the site and/or an infiltration gallery around the perimeter would minimize the spread of brine and make it possible to return this land to production in the foreseeable future.
Combined Use of Hydraulic and Electrical Properties of an Aquifer in a Geostatistical Estimation of Transmissivity
Authors: Ahmed Shakeel , de Marsily Ghislain , Talbot Alain 
Published: March 2006

ABSTRACTMany previous attempts have been made to establish an empirical relation between the electrical and hydraulic properties of aquifers. However, only regression models between transmissivity or permeability and a few electrical parameters have been used on the basis of the available pairs of data. Kriging, a geostatistical technique, estimates a regionalized variable at any point in space, and multivariate geostatistical techniques allow one to use several variables together to estimate any ‘spatial parameter. One such method, cokriging, is used to estimate the transmissivity based not only on measurements of transmissivity, but also on measurements of specific capacity and electrical transverse resistance. The studied aquifer is situated in the Medjerda Valley in Tunisia where very few data on transmissivity and specific capacity are available, but resistivity data are relatively abundant. It is shown that with the geostatistical technique, one can: (1) use several electrical or elastic properties, which are easily measured, in the estimation of the desired parameter without establishing any empirical relation; and (2) make the estimation at any point where none of these properties has been sampled and, at the same time obtain a variance of the estimation error. The method is also compared with the usual regression method.
A Remotely Operated Seepage Meter for Use in Large Lakes and Rivers
Authors: Cherkauer Douglas A. , McBride John M. 
Published: March 2006

ABSTRACTThe many seepage meter designs presented to date are generally fragile and require direct installation by divers. On large surface‐water bodies, such as the Great Lakes, storm wave size, water depth, temperature, and turbidity make these previous seepage meters ineffective. A design is presented in this paper which is heavy and sturdy enough to withstand Great Lakes storms and which can be remotely installed from the water surface. These UWM meters require stabilization on the bottom of 15 to 25 minutes before activation and must be corrected for slow settling and hydraulic inefficiency. Such correction is straightforward, and corrections are presented for sand beds. Field testing shows that corrected seepages from these meters have a maximum deviation of 33% and a standard deviation of 22% from the observed mean. The meter has had over a 90% success rate in installations throughout the Great Lakes. It does not function on rock or soft sediment.
Measurement of Ground‐Water Parameters Using Salt‐Water Injection and Surface Resistivity
Authors: White Paul A. 
Published: March 2006

1. ABSTRACTA method of determining the direction and velocity of ground‐water flow by injecting a salt‐water slug into an aquifer, and tracing its movement with surface resistivity measurements is described. Aquifer hydraulic conductivity can be derived from the measured velocity, the hydraulic gradient, and the aquifer porosity. The method is examined using theoretical considerations and New Zealand field examples.This method of measuring ground‐water velocities has several advantages over conventional well‐to‐well tracer experiments. Only a single access to the aquifer is required. Velocity estimates are more representative of true ground‐water velocities. The method is inexpensive and straightforward to perform. It is applicable to investigating freshwater aquifers within 20 m of the ground surface and when highly conductive materials do not occur above the aquifer.
Cosolvent Influences on Organic Solute Retardation Factors
Authors: Staples Charles A. , Geiselmann Stephanie J. 
Published: March 2006

ABSTRACTPrediction of chemical movement in ground water can be complex. Solute transport calculations need to reflect appropriate mathematical treatment of sorption and retardation by aquifer materials. The presence of cosolvents further complicates solute transport prediction. Results from a series of experiments both simple (small tubes) and complex (soil columns) suggest adequate predictability of solute sorption and attenuation in the presence of cosolvents. The results indicate that simple (small tube) short‐term tests under a variety of sorbent concentrations can be used to predict soil column solute transport if appropriate physical properties are accounted for (soil type, organic load, bulk density). The final results indicate that low levels of cosolvents showed significant reproducible sorption/ attenuation reductions but probably are ultimately not important to overall solute fate.
Applying the USGS Mass‐Transport Model (MOC) to Remedial Actions by Recovery Wells
Authors: El‐Kadi Aly L. 
Published: March 2006

ABSTRACTThe USGS two‐dimensional mass‐transport model (MOC) is widely used in the analysis of ground‐water contamination problems. A need exists to examine the accuracy of the code in situations dominated by radially convergent and divergent flow around wells. The model is applied here to situations that commonly exist in remedial actions involving recovery wells. The cases simulated are a recharge/recovery single well, a recharge/recovery doublet, and plume capture by one or two production wells. The results were tested against analytical and semianalytical solutions. Inaccuracies in model results occurred especially for the doublet case under continued long‐time simulation. Inaccuracies are caused not only by the mainly radial‐flow situation, or by the curvature nature of streamlines, but also by the arrival of contamination at the sink nodes. Better agreement of numerical and analytical solutions was obtained for the single‐well and plume‐capture situations. However, a large mass‐balance error exists for the single‐well case. Inaccuracies can be reduced by modifying the code and reducing the finite‐difference mesh (e.g., Erickson, 1985). However, the use of a very fine mesh (i.e., on the order of a few feet) may prevent the use of the code in large‐scale problems. Care must be taken in applying the model to situations where production or injection wells are close to each other.
An Optimization Model for Analysis of Test Pumping Data
Authors: Kashyap Deepak , Dachadesh Prasong , Jageshwar Sinha L. S. 
Published: March 2006

ABSTRACTAn optimization model for computer‐assisted estimation of aquifer parameters has been developed. It is based upon the principle of minimization of the sum of squares of the differences between observed and computed drawdowns. The objective strategy eliminates the subjectivity associated with the conventional curve‐matching procedures. Apart from the parameter estimation, the model can assist in identifying certain hydrogeological features like leakage, discontinuities, vertical anisotropy, etc. It also can provide a check on consistency among different data sets monitored during a test pumping (e.g., drawdown and recovery data). The application of the proposed model has been illustrated by analysis of field data. The model‐computed parameters honored the observed data more closely than the graphical estimates. The model could also identify leakage as the cause of departure of the time‐drawdown curve from the Theis type curve. In another study, the model results lead to an inference that the recovery data of the pumped well are inconsistent with the rest of the data.
Finite‐Element Simulation of Long‐Term Transient Regional Ground‐Water Flow
Authors: England Lindy A. , Freeze R. Allan 
Published: March 2006

ABSTRACTA finite‐element model is developed to solve the two‐dimensional, transient, ground‐water flow equation on a regional scale over geologic time for the purpose of assessing the rate of hydraulic head decay at depth in response to erosional modifications of the land surface. The model includes a time‐stepping procedure that allows consideration of sedimentary basins with large hydraulic conductivity contrasts. Results confirm that hydraulic head patterns that are not in equilibrium with existing topography can persist at depth over geologically significant periods of time. A sensitivity analysis on a hypothetical layered system shows that the rate of hydraulic head adjustment, due to erosional modifications of the topography, is particularly sensitive to the thickness, continuity, and vertical hydraulic conductivity of the low‐permeability layers. Application of the two‐dimensional model to the Red earth region of northern Alberta, Canada predicts response times that are reduced by two‐thirds over those predicted with one‐dimensional models. The concept of delayed hydraulic response over geologic time has important implications in the siting and design of nuclear waste repositories, the analysis of contaminant plume migration, and the use of the hydrodynamic approach to the exploration for petroleum resources and stratabound ore deposits.
The Victoria Province Drought Relief Project, II. Borehole Yield Relationships
Authors: Houston J.F.T. , Lewis R. T. 
Published: March 2006

ABSTRACTComposite aquifers composed of relatively high storage, low permeability regolith overlying low storage, higher permeability fissured bedrock occur in the Basement terrain of Victoria Province. The adequacy of these aquifers for rural‐water supplies is variable and locating optimum borehole sites is difficult. The analysis of data from the Victoria Province Drought Relief Project suggests that a variety of environmental factors influence borehole yield. Despite the wide scatter of data, certain generalizations can be made using statistical techniques. The results show that for regolith aquifers specific capacity increases with rainfall, regolith thickness, and altitude, which is in turn probably related to the age of the erosion surface. In fissured bedrock aquifers the upper 20 m is crucial for the provision of an adequate yield.