bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogeological Decision Analysis: 3. Application to Design of a Ground‐Water Control System at an Open Pit Mine
Authors: Sperling Tony , Freeze R. Allan , Massmann Joel , Smith Leslie , James Bruce 
Published: August 2005

AbstractControl of ground water plays an important part in operations at many open pit mines. Selection of an efficient and cost‐effective ground‐water control program is frequently complicated by the complex and somewhat uncertain hydrogeo‐logic environment found at most mine sites. This paper documents a case study of dewatering operations at Highland Valley Copper that shows how risk‐cost‐benefit analysis can be used to identify the best ground‐water control strategy to improve stability of pit walls under such conditions.For each of a specified set of design alternatives, the analysis involves evaluation of an economic objective function, comprised of revenues, operating costs, and monetary risks associated with slope failure. The risk calculation requires an accurate estimate of the probability of slope failure on the pit wall. The calculation involves a coupled, steady‐state, saturated‐unsaturated, finite‐element ground‐water flow model and a limit equilibrium slope stability model. The coupled model is invoked in a conditional Monte Carlo simulation that is based on a geostatistical description of the level of uncertainty inherent in the available hydrogeological and geotechnical data.Although the emphasis in this paper is on identifying the optimum slope angle and ground‐water control strategy for open pit mines, the framework is equally well‐suited to the analysis of design issues for any engineering projects in which the hydrogeological environment plays an important role.
Hydrograph Analysis in a Fractured Rock Terrane
Authors: Moore Gerald K. 
Published: August 2005

AbstractA typical watershed near Oak Ridge, Tennessee is underlaid by a stormflow zone, which approximately corresponds with the root zone of vegetation, and by a ground‐water zone. Analysis of the streamflow hydrograph and water‐level hydrographs during the nongrowing season shows that discharge from the stormflow zone constitutes nearly all streamflow after the end of overland runoff but that discharge from the ground‐water zone is dominant after about 8–10 d (days) of recession. Simple equations that express the relationship between streamflow recession and storage depletion can be used to calculate average values of specific yield, transmissivity, and hydraulic conductivity in both the stormflow and ground‐water zones. The calculated values are reasonable and are nearly the same as those obtained by other methods.
Analysis of Ground‐Water Flow and Injection Fluid Transport in the Floridan Aquifer Near Pensacola, Florida
Authors: Ward David S. , Mercer James W. , August Lisa L. 
Published: August 2005

AbstractLiquid waste has been injected into a permeable part of the lower limestone of the Floridan aquifer since 1963, raising hydraulic head in the injection zone throughout a region of northwestern Florida. The injection zone consists of a moderately permeable limestone, hydraulically isolated from overlying aquifers by a thick layer of clay. The formation fluid is saline, but becomes fresher up dip, northward where the limestone crops out. Numerical simulations were performed at regional and local scales to assess the regional pressure increase, to analyze the movement of the 10,000 mg/1 total dissolved solids (TDS) isopleth (formation fluid) in the lower limestone of the Floridan aquifer, and to analyze the migration of the injection fluid, both historically and predictively, in the injection formation. This work is based largely on previous work by Merritt (1984), but uses the SWIFT code. Modifications to Merritt's work include increasing the hydraulic conductivity near the injection wells and using more recent injection rates; extensions include particle tracking and solute transport modeling. The simulations indicate that regional pressure increases should be much less than previously predicted. Using the new results, by the year 2033, the average movement of the 10,000 mg/1 TDS isopleth due to injection is expected to be approximately 2200 ft (671 m). Additionally, by the year 2033, the indiluted injection fluid (95% of injection concentration) should migrate to an approximate diameter of 2.1 mi (3.4 km) from the injection wells.
Field Determination of Geological/Chemical Properties of an Aquifer by Cone Penetrometry and Headspace Analysis
Authors: Chiang C. Y. , Loos K. R. , Klopp R. A. 
Published: August 2005

AbstractThe cone penetrometer with pore pressure measurements was first introduced in 1975. It is generally regarded in the geotechnical community as one of the most efficient tools for stratigraphic logging of soft soils. Recently, the conventional cone penetrometer has been coupled with a porous probe ground‐water sampler for environmental applications.This coupled system was used to perform soil logging, collect ground‐water samples, and evaluate hydraulic conductivity in an effort to determine the extent and preferential flow pathway(s) of a soluble hydrocarbon plume in a Texas aquifer. Ground‐water samples collected by a porous probe sampler were analyzed for hydrocarbon content by a portable gas chromatograph with a photoionization detector (GC/PID) to characterize the extent of the soluble organic plume and provide a field evaluation of ground‐water quality. Aqueous concentrations of hydrocarbons calculated from vapor headspace measurements by this technique were in good agreement with direct concentration measurements obtained in the laboratory using standard EPA ground‐water analytical procedures. This field procedure makes it possible to efficiently use cone penetrometry equipment in less characterized areas allowing rapid delineation of volatile organic plumes by the headspace analysis.Interpretation of the cone penetrometer test data located a buried channel on the site aligned in an east‐west depositional direction. To the north and south of the channel, the soils exhibited reduced hydraulic conductivity due to their respective soil type or depositional density. Analyses of ground‐water samples collected from the area confirmed that soluble hydrocarbon migration was following the more permeable channel. In addition, depth selective ground‐water sampling recorded sharp changes in the vertical concentration profiles indicating that macroscopic vertical dispersion may be negligible at this site.
Sea‐Water Intrusion in the Coastal Area of Laizhou Bay, China: 1. Distribution of Sea‐Water Intrusion and Its Hydrochemical Characteristics
Authors: Xue Yuqun , Wu Jichun , Liu Peimin , Wang Jianji , Jiang Qingbo , Shi Hongwen 
Published: August 2005

AbstractSea‐water intrusion was observed in China's coastal aquifers as early as the 1960s. At present, it covers an area of more than 580 km2, and is continuing to extend in the coastal area of Laizhou Bay. There is a wide transition zone of 1.5–6.0 km, in which both the simple mixing of local fresh water and sea water and the cation exchange can be recognized. In this paper, extensive chemical and head data sets in four dimensions relevant to the distribution of the sea‐water intrusion and ion exchange are presented.
Combined Use of Geoelectric Sounding and Profiling to Quantify Aquifer Protection Properties
Authors: Kalinski Robert J. , Kelly William E. , Bogardi Istvan 
Published: August 2005

AbstractEvolving environmental regulations have increased the need for defining the protective properties of geologic layers. Of particular significance is the need for defining vertical times‐of‐travel (TOT) through aquitards located above municipal water supply wellfields. Surface geoelectrics provide an inexpensive field measurement method that can be used to quantitatively define protective properties. Protective layer longitudinal unit conductance squared (S2) can be theoretically related to TOT using material relationships between resistivity and hydraulic conductivity divided by porosity (K/n).In an example presented for a municipal wellfield, it was possible to utilize a limited number of geoelectric soundings to establish relationships between S of a conductive protective layer and apparent resistivities measured at individual electrode spacings, providing a method to estimate S with profiling. In this case, longitudinal unit conductance (S) was the geoelectrically equivalent parameter of the protective layer. The use of combined sounding and profiling data in the wellfield area resulted in an overall reduction in the kriging estimation error of S for the protective clay layer and a larger area of coverage over what was obtained with soundings alone.
Designing a Nitrate Monitoring Program in a Heterogeneous, Carbonate Aquifer
Authors: Smith Ronald T. , Ritzi Robert W. 
Published: August 2005

AbstractMultilevel, double‐packer slug tests were performed in open core holes to characterize heterogeneity within a flat‐lying, fractured carbonate aquifer. Hydraulic conductivity was measured to vary by approximately three orders of magnitude in the vertical direction and by as much as two orders of magnitude in the horizontal direction. In general, hydraulic conductivity decreased with distance from the bedrock free‐surface, as the degree of fracturing decreased. The results of the multilevel slug tests provided the basis for hydraulic conductivity zonation within a two‐dimensional finite‐element model, which simulated nitrate transport in cross section. In simulation of steady‐state flow, several shallow, local ground‐water flow systems occurred with exit points that are consistent with springs observable in the field. Yearly rotating crops of corn and soybeans were simulated with nitrate source concentrations based on pore water measurements in the lower soil zones of the field site. The majority of simulated nitrate movement occurred within shallow, localized ground‐water flow systems, where much of the nitrate exited the system relatively soon after entering, without appreciable accumulation of nitrate through the years. Based on these results, a monitoring program with a relatively high spatial and temporal resolution in the shallow, localized ground‐water flow systems was required in order to characterize nitrate concentrations in the ground water. Regional water quality surveys that involve a random sampling of existing, widely spaced wells would likely miss detecting the locations and times of high nitrate concentrations in ground water.
Recovery Analysis from Pumping Tests with Stepped Discharge
Authors: Kawecki M. W. 
Published: August 2005

AbstractRecovery analysis from pumping tests with varying discharge is well‐documented but in practice often wrongly considered to be impractical or even impossible. However, the Theis recovery method for constant rate tests is popular and widely used to determine aquifer transmissivity. The purpose of this paper is to review and promote determination of transmissivity by recovery analysis in tests in which the discharge is not steady but represented by a step function. The equations for a stepped discharge recovery method are presented in a simple form, highlighting the fact that it is a direct extension of the Theis recovery method with the same advantages and ease of application. It is demonstrated that the Theis recovery method cannot generally be used with an average discharge for varying rate tests. Recovery analysis should always be approached with the stepped discharge recovery method, which reduces to the Theis method if the discharge is constant. The stepped discharge recovery method is particularly useful for step tests and for analyzing data from the pumped well, and it should be standard practice to monitor the recovery in all pumping tests on single wells. It is also shown that a different storage coefficient during recovery than during pumping does not result in a shifted straight line in the recovery analysis but in a curve passing through the origin.
Use of Portable Oxygen and Carbon Dioxide Detectors to Screen Soil Gas for Subsurface Gasoline Contamination
Authors: Deyo Brendan G. , Robbins Gary A. , Binkhorst Gordon K. 
Published: August 2005

AbstractThe field screening of soil gas CO2 and O2 using portable instruments is shown to be useful for indirectly detecting and delineating subsurface gasoline contamination. Shallow (< 50 cm) soil gas surveys performed at a site of subsurface gasoline contamination in Connecticut indicated a good correlation between elevated CO2, depleted O2, and total hydrocarbon vapor anomalies. CO2 and O2 anomalies were also found to be spatially coincident with the area of known subsurface gasoline leakage. Soil gas CO2 levels ranged from 0.2 to 18.7 volume percent, whereas O2 levels ranged from 20.8 to 0.5 volume percent. The gases exhibited a nearly constant inverse correlation except near the source of contamination. In this area, CO2 generation from anaerobic degradation of hydrocarbons likely caused a decrease in the observed CO2 and O2 correlation. This suggests that the ratio of soil gas CO2 to O2 may be useful to delineate aerobic and anaerobic degradation zones, the latter being in the vicinity of highly contaminated areas. Periodic sampling of seven permanent soil gas probes over a 17‐month period indicated significant seasonal variations in CO2 and O2. When the soil was warmest during the summer, the CO2 reached a maximum and O2 reached a minimum. The opposite was observed during the winter when the soil achieved its minimum temperature. These observations most likely reflect changes in microbial acitivity in response to subsurface temperature variations. Further, hydrocarbon vapor levels were observed to decrease by several orders of magnitude to nondetectable levels during the winter months. Although CO2 and O2 anomalies were also diminished during the winter months, they were still readily detectable. These observations indicate that soil gas surveying for subsurface gasoline leakage may be enhanced by monitoring CO2 and O2.
Evaluating the Volume of Porous Medium Investigated During Slug Tests
Authors: Guyonnet D. , Mishra S. , McCord J. 
Published: August 2005

AbstractThis paper presents a methodology for quantifying the volume of porous medium investigated during a slug test in an unbounded porous medium, in the presence of a linear constant‐head or no‐flow boundary, and in the presence of a radial no‐flow boundary. For the unbounded case, type curves are generated for different values of the wellbore storage coefficient, which relate the distance travelled by a given pressure perturbation (1, 5, and 10% of the initial drawdown in the well), to dimensionless time. This distance is found to increase linearly on a log‐log plot until it reaches a maximum which is a function of the wellbore storage coefficient. The appropriate choice of dimensionless groups allows the different curves for each level of perturbation to be collapsed into one curve. Functional relationships offer an alternative to using the type curves graphically. For bounded systems, type curves relate the distance to the boundary to the time of 1 and 5% deviation from the unbounded response. Although these curves cannot be collapsed, the presented range of wellbore storage coefficients covers most practical situations. Developed relationships allow the estimation of the maximum distance travelled by the pressure perturbations in the unbounded case, and the maximum distance at which a linear constant‐head or no‐flow boundary, or a radial no‐flow boundary, still produces a given deviation in the pressure response measured at the well. An application shows that substantial error may result if the distance to a boundary is evaluated while neglecting storage in the well. Finally, application of the methodology developed for a linear no‐flow boundary to a real data set yields a realistic distance to the boundary and a far better match between simulated and measured data than if an unbounded system is considered. The type curves and relationships presented here should be applicable to slug test design and analysis.
Continuous Measurements of Ground‐Water Seepage Using an Automatic Seepage Meter
Authors: Taniguchi Makoto , Fukuo Yoshiaki 
Published: August 2005

AbstractAn automatic seepage meter using a heat pulse method was developed to obtain a continuous measurement of ground‐water seepage rates. According to calibrations of the automatic seepage meter fitted with a 50 cm diameter collection funnel, seepage rates from 2 X 10‐5 to 5 X 10‐4 cm/sec can be obtained by measuring the time when the temperature as measured by a thermistor peaks after applying a heat pulse. The automatic seepage meter was used to measure continuous seepage rates into Lake Biwa, Japan. The ground‐water seepage rate measured by the automatic seepage meter in Lake Biwa changed by six times within 12 hours. The automatic seepage meter is useful for surface‐/ground‐water studies, because a continuous seepage rate can be obtained without errors caused by the resistance of a collection bag to water flow.
A Comparative Study of Calculation Methods for Recharge of Rainfall Seepage to Ground Water in Plain Area
Authors: Liu Yong , Zhang Chun 
Published: August 2005

AbstractGround water in the plain area of China is recharged mostly with rainfall and to a lesser extent with surface water and nearby ground water. There are several methods for the calculation of recharge of rainfall seepage to ground water. The calculated values using different methods vary due to the accuracy of parameters and calculation methods chosen. A comparative study of methods used to calculate ground‐water recharge by rainfall seepage is made using the water‐balance method and the ground‐water regime analysis method applied to the plain area of China. The accuracy of the ground‐water regime analysis method is superior to that of the water‐balance method. The influential factors (lithology, depth to ground water, precipitation capacity, etc.) of ground‐water recharge by rainfall seepage and the accuracy of these factors are also discussed.
Vertical Heterogeneity in Horizontal Components of Specific Discharge: Case Study Analysisa
Authors: Ronen Daniel , Berkowitz Brian , Magaritz Mordeckai 
Published: August 2005

AbstractGround‐water management decisions are usually taken under uncertainty, since they depend on unknown parameters of the aquifer such as hydraulic conductivity and specific discharge. This study applies a number of analytical techniques to a case study in order to demonstrate the potential effect of vertical heterogeneity in the horizontal component of specific discharge on evaluating contaminant travel time in an aquifer. The modified point dilution technique developed by Ronen et al. (1986) is applied to study the vertical variability of the horizontal component of specific discharge in a deep unconfined sandy aquifer. This technique, used under natural flow conditions, employs a multilayer sampler, a tracer, and a mathematical diffusion model. Also analyzed are data from a very large unplanned tracer test where the “tracer”, sewage effluent with a high chloride content, was infiltrated into the aquifer for about 30 years. To date, based on available sedimentological evidence and pumping tests, the aquifer has been regarded as homogeneous. However, information from analysis of the tracer test data by two different flow models, and findings obtained by the modified point dilution technique, indicate the existence of zones of high hydraulic conductivity with specific discharges one order of magnitude higher than expected. As a consequence, chloride breakthrough in a pumping well downstream of effluent infiltration was detected after 10 years, at least 70 years earlier than could have been estimated from previously available data. The results demonstrate that consideration must be given to vertical heterogeneity when evaluating contaminant transport and show that detailed site‐specific field studies are needed in order to prevent or control aquifer contamination.
Effects of Pipe‐Outlet Terracing on Ground‐Water Quantity Near Churchtown, Pennsylvania
Authors: Hall David W. 
Published: August 2005

AbstractGround‐water quantity data were collected at a 22‐acre farm site near Churchtown, Pennsylvania, to determine if terracing changed the quantity of water recharging the aquifer. Double‐mass comparisons of water‐level data from six wells at the site were used to determine that the construction and operation of six pipe‐outlet terraces caused no statistically significant changes in the quantity of recharge to the carbonate aquifer. Analyses of water‐table altitude data from site wells indicate that terracing did not change mean annual water‐table altitudes at the site.
Model Calibration Techniques for Use with the Analytic Element Method
Authors: Power Barry F. , Barnes Randal 
Published: August 2005

AbstractThe combination of the analytic element method and a nonlinear parameter estimation technique forges a computationally efficient, information‐rich, and cost‐effective solution to the inverse ground‐water flow problem. The recommended model calibration method uses a nonlinear least‐squares objective, as quantified by misfitting the measured and modeled heads, and a modified Levenberg‐Marquardt algorithm. As detailed and demonstrated by a steady‐state regional aquifer model of Bemidji, Minnesota, automated calibration techniques make ground‐water modeling feasible for a wider variety of projects where tight budgets and a lack of tools may have previously made such modeling inappropriate.
Design of Optimal, Reliable Plume Capture Schemes: Application to the Gloucester Landfill Ground‐Water Contamination Problem
Authors: Gailey Robert M. , Gorelick Steven M. 
Published: August 2005

AbstractA ground‐water quality management model is applied to the Gloucester Landfill site, located near Ottawa, Canada, to examine the effectiveness of various single‐well pumping schemes for the capture of dissolved contaminants. Deterministic and stochastic design analyses are conducted through ground‐water solute transport modeling of the site. The purpose of the modeling analysis is to develop contaminant capture designs that both require minimum pumping rates and possess high probabilities of success.Optimization based upon deterministic simulation indicates that a well located at the front of the plume would effect plume capture and require the lowest pumping rate. However, a smaller total volume of water could be pumped and still effect plume capture if the well were located at the center of the plume and pumped at a higher rate for a shorter time. Stochastic optimization analyses are used to overdesign the pumping rates so that possible design error is overcome. The analyses indicate that design reliability may be increased from 50 to 90 percent by pumping an additional 18 percent at the front or 27 percent at the center of the plume. These pumping overdesign factors are the first such values calculated using the stochastic optimization approach applied to a field site.