bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Systematic Approach for Evaluating the Quality of Ground Water Monitoring Data
Authors: Campbell Jill A. , Mabey William R. 
Published: February 2007

AbstractThe recognition and assurance of the quality of ground water monitoring data are crucial to the correct assessment of the magnitude and extent of a ground water contamination problem. This article addresses an approach being developed to systematically evaluate the quality of a given set of ground water monitoring data collected during site investigation/ remedial action efforts. The system consists of a checklist of criteria, grouped into four major categories, which can be applied to laboratory or field measurements.The first category, basis of measurement, considers whether the appropriate sampling, boring and/or analytical methods were chosen to obtain the measurement and the limitations of each method. Secondly, application of the method is assessed. This includes examination of the extent to which procedures were correctly performed, the use of quality control measures and calibration, and possible sources of error in the measurements. Third, evaluation of applied statistical methods is made, with consideration given to which statistics are meaningful in a given context and whether measurements are reproducible. The final category, corroborative information, considers whether independent data or other information are available that add credibility to the values measured.In this approach, a “high quality” data value is defined as one in which accuracy is supported by meeting the preceding criteria. When accompanied by precision information, high quality data allow for defensible assessments and actions. This evaluation system is useful in developing monitoring programs and in guiding documentation of field and laboratory methods during data collection. It relies heavily on experienced judgment and can be catalyst for the beneficial exchange of knowledge and ideas among ground water professionals.
The Effect of Three Drilling Fluids on Ground Water Sample Chemistry
Authors: Brobst Robert B. , Buszka Paul M. 
Published: February 2007

AbstractThree monitoring wells were installed in borings that were constructed using water‐based drilling fluids containing either (1) guar bean, (2) guar bean with breakdown additive, or (3) bentonite. These fluids were selected to observe their effect on the chemistry of subsequent water samples collected from the wells. The wells were installed to depths of 66 feet, 100.5 feet and 103 feet, respectively, in fine‐to‐medium sand and gravel outwash deposits near Antigo, Wisconsin. Drilling fluids were necessary to maintain an open borehole during well construction through strata containing cobbles and boulders.The bentonite and guar drilling fluids caused temporarily elevated concentrations of chemical oxygen demand (COD) in ground water samples collected from the monitoring wells. Using standard development, purging and sampling procedures, elevated COD concentrations persisted for about 50 days for the well bored with the guar‐with‐additive fluid, 140 days for the bentonite well and 320 days for the guar well. Unfiltered ground water samples for all wells had greater concentrations of COD than samples filtered through a 0.45 micron filter. Sulfate concentrations also decreased with time in the guar‐with‐additive well and bentonite well, but not in the guar well.The elevated COD concentrations are attributed to the large concentrations of oxidizable carbon present in the guar bean drilling fluid and in the organic polymers present in the bentonite drilling fluid. Well development and purging procedures, including borehole flushing, surging, bailing and/or chemically induced viscosity breakdown of the guar mud decreased the time before background conditions were achieved. Future research should evaluate the physical and geochemical interaction of different drilling fluid compositions with a variety of geologic matrices and drilling, well development and well purging techniques.
A Field Terminal for Collection and Analysis of Geological and Hydrogeological Data
Authors: Petsonk Andrew M. 
Published: February 2007

AbstractHaving immediate, automated field access to data gathered during geological and hydrogeological investigations can be crucial to definition of the scope and direction of test procedures, as well as to the interpretability of results. A portable, briefcase‐sized data collection and analysis instrument has therefore recently been developed. It is capable of operating as a standalone or operator‐guided field unit. This terminal is pre‐programmed for a number of standard applications, several of which involve BAT® tools, e.g., permeability tests made using the BAT Ground Water Monitoring System. It can, however, be used with a wide range of other tools for controlling data collection during pumping, penetration and pressometer tests, etc.An operator's terminal and independent data collection microcontroller are the major components of this system. Data may be collected from any combination of four ports: an internal, programmable interval timer, a pulser (shaft encoder), and two 14‐bit analog‐to‐digital (A/D) inputs. The latter are primarily used for pressure or resistance transducers. Reading of data may be triggered automatically by the timer and/or pulser, or be performed upon operator command. Many thousands of data points may be stored in the microcontroller, representing one or several tests of any type, intermixed. Via the operator's terminal, any subset of this stored data may be examined, erased, modified or analyzed. A 26‐character LCD display and a four‐color printer/plotter are used to record data and results of analyses. Data may also be transferred to an external computer for more extensive manipulation.Three examples of how this terminal may be used in the field in connection with site investigations are presented in this paper. They involve (a) measurement of saturated hydraulic conductivity, (b) determination of soil stratigraphy using pore pressure sounding, and (c) water network profiling.
Sources of Ground Water Salinization in Parts of West Texas
Authors: Richter Bernd C. , Kreitler Charles W. 
Published: February 2007

AbstractDetermination of chemical constituent ratios allows distinction between two salinization mechanisms responsible for shallow saline ground water and vegetative‐kill areas in parts of west Texas. Mixing of deep‐basin (high Cl) salt water and shallow (low Cl) ground water results in saline waters with relatively low Ca/Cl, Mg/Cl, SO44/ Cl, Br/Cl, and NO3/Cl ratios. In scattergrams of major chemical constituents vs. chloride, plots of these waters indicate trends with deep‐basin brines as high Cl end members. Evaporation of ground water from a shallow water table, in contrast, results in saline water that has relatively high Ca/Cl, Mg/Cl, SO4/Cl, and Br/CL ratios. Trends indicated by plots of this water type do not coincide with trends indicated by plots of sampled brines. Leaching of soil nitrate in areas with a shallow water table accounts for high NO3 concentrations in shallow ground water.
Natural Attenuation of Aromatic Hydrocarbons in a Shallow Sand Aquifer
Authors: Barker J.P. , Patrick G. C. , Major D. 
Published: February 2007

AbstractInadvertent release of petroleum products such as gasoline into the subsurface can initiate ground water contamination, particularly by the toxic, water‐soluble and mobile gasoline components: benzene, toluene and xylenes (BTX). This study was undertaken to examine the processes controlling the rate of movement and the persistence of dissolved BTX in ground water in a shallow, unconfined sand aquifer.Water containing about 7.6 mg/ L total BTX was introduced below the water table and the migration of contaminants through a sandy aquifer was monitored using a dense sampling network. BTX components migrated slightly slower than the ground water due to sorptive retardation. Essentially all the injected mass of BTX was lost within 434 days due to biodegradation. Rates of mass loss were similar for all monoaromatics; benzene was the only component to persist beyond 270 days. Laboratory biodegradation experiments produced similar rates, even when the initial BTX concentration varied.A dominant control over BTX biodegradation was the availability of dissolved oxygen. BTX persisted at the field site in layers low in dissolved oxygen. Decreasing mass loss rates over time observed in the field experiment are not likely due to first‐order deeradation rates, but rather to the persistence of small fractions of BTX mass in anoxic layers.
A Practical Application of Multiphase Transport Theory to Ground Water Contamination Problems
Authors: Hinchee Robert E. , Reisinger H. James 
Published: February 2007

AbstractHydrocarbon transport in the subsurface environment occurs in several phases, chiefly the non‐aqueous phase liquid (NAPL), dissolved and vapor phases. Mechanisms that influence transport include the physicochemical properties of the specific compounds present (density, vapor pressure, viscosity, hydrophobicity) and the physical and chemical properties of the subsurface environment, including geology, aquifer minerology and ground water hydrology. Hydrocarbon liquids are typically complex mixtures composed of numerous compounds, each with its own individual physicochemical and, therefore, transport properties. Examination of chemical data can provide insights into the transport mechanisms operating at a site: Ground water transport results in relative enrichment by more soluble, less hydrophobic hydrocarbon compounds as a function of distance from a spill; vapor phase transport typically results in relative enrichment in more volatile hydrocarbon compounds.Two sites at which subsurface fuel spills resulted in ground water contamination will illustrate the use of transport mechanism theory. At Site 1 a subsurface spill resulted in a NAPL plume approximately 150m (500 feet) and a dissolved hydrocarbon plume resulting from ground water transport of dissolved hydrocarbon approximately 350m (1150 feet) hydraulically downgradient of the source. At Site 2 there was a sudden subsurface fuel spill; ground water pumping with hydrocarbon recovery was begun within a week of spillage. Vapor phase transport resulted in contaminated ground water hydraulically upgradient of the source. In addition, there was cross‐contamination at Site 2, probably as the result of contaminated water level gauging equipment, but the chemical characteristics of this contamination were sufficiently obvious to permit its identification. An understanding of transport mechanisms is instrumental in contamination assessment source identification, contaminant fate prediction and design of an appropriate remedial program.
Measurement of Carbon Dioxide in Soil Gases for Indication of Subsurface Hydrocarbon Contamination
Authors: Kerfoot H.B. , Mayer C.L. , Durgin P.B. , D'Lugosz J.J. 
Published: February 2007

AbstractA preliminary field evaluation of a new application of soil‐gas measurement for delineation of subsurface organic contamination is described. The method measures carbon dioxide concentrations in soil gases and is based on the hypothesis that carbon dioxide concentrations from subsurface oxidation of organic compounds will be porportional to the extent of organic contamination. A correlation coefficient (r) of 0.81 (n=6) was observed between ground water dissolved organic carbon ground water concentrations and carbon dioxide concentrations in the overlying soil gases at one site. Soil‐gas carbon dioxide concentrations measured ranged from 0.09 percent to 0.45 percent.
Oxygen Transfer Through Flexible Tubing and Its Effects on Ground Water Sampling Results
Authors: Holm Thomas R. , George Gregory K. , Barcelona Michael J. 
Published: February 2007

AbstractA model for the diffusion of gases through polymeric tubing was derived which predicts that the amount of gas transferred is proportional to the tubing length and inversely proportional to the pumping rate. The model was experimentally tested and confirmed for oxygen transfer through fluorinated ethylene‐propylene copolymer (FEP) tubing using tubing lengths and flow rates typical of ground water sampling. Diffusion can introduce measurable concentrations of oxygen into initially anoxic water. Diffusive loss of carbon dioxide from water that is oversaturated with respect to atmospheric CO2 does not measurably affect pH under similar usage conditions.
Changes in Volatile Organic Chemical Concentrations After Purging Slowly Recovering Wells
Authors: Herzog Beverly L. , Chou Sheng‐Fu J. , Valkenburg John R. , Griffin Robert A. 
Published: February 2007

AbstractMost guidelines for sampling ground water require the evacuation of multiple bore volumes from the well before a sample is collected. Such recommendations are impractical for wells that are finished in fine‐grained deposits with such slow recharge that they cannot recover rapidly enough for the requisite number of well volumes to be removed. In such situations, the sample is usually collected either 24 hours after evacuation or sometime during well recovery. Neither of these strategies has been supported by field evidence.The purpose of this study was to determine the changes in volatile organic chemical concentration during well recovery. Three hundred samples were analyzed for up to 19 different volatile organic compounds from 11 wells that were finished in fine‐grained glacial tills. Each well was sampled before purging and at several time intervals up to 48 hours after purging. The experiment was conducted three to five times on each well. Samples were collected with dedicated point‐source PTFE bailers equipped with bottom‐emptying devices that were designed for collecting samples for volatile organic chemical analysis. All wells were evacuated with a bailer because they were finished in slowly recharging materials having hydraulic conductivities of between 1 × 10−6 and 7 × 10−5 cm/sec.Results of the chemical analyses were examined statistically using a general linear model and the Tukey honestly significant difference test to ascertain whether the changes in water quality with time after purging were statistically significant. At the 95 percent confidence level, there was no significant difference in chemical compositions at any time interval after purging, although samples collected at four hours had slightly higher concentrations than did earlier or later samples. However, concentrations of volatile organics were significantly lower before purging than after purging. These results clearly show that wells finished in fine‐grained sediments should be purged before samples are collected for volatile organic chemical analysis.
Modeling Ground Water Quality Sampling Decisions
Authors: Hsueh Ya‐Wen , Rajagopal R. 
Published: February 2007

AbstractQuestions such as what, where, when, and how often to sample play a central role in the development of monitoring strategies. Limited resources will not permit sampling for many contaminants at the same frequency at all well sites. Therefore, a resource allocation strategy is necessary to arrive at answers for the preceding types of questions. Such a strategy for a ground water quality monitoring program is formulated as an integer programming model (an optimization model). The model will be of use in the process of deciding what constituents to sample and where to sample them so as to maximize a given objective, subject to a set of budget, sampling, and regulatory constraints. The maximization objective in the model is defined as a weighted function of population exposure to a scaled measure of observed chemical concentrations. The sampling constraints are based on the observed variability of contaminants in the aquifer, needed precision in estimates, a chosen level of significance, the available budget for implementing the program, and selected regulatory constraints. The model is tested with field data obtained for 10 selected constituents from more than 650 wells in the Cambrian‐Ordovician aquifer in Iowa. Results from two alternative formulations of the model are compared, analyzed, and discussed. Further avenues for research are briefly outlined.
A National Evaluation of the Leaching Potential of Aldicarb Part 1. An Integrated Assessment Methodology
Authors: Lorber Matthew N. , Cohen Stuart Z. , Noren Stephen E. , De Buchananne George D. 
Published: February 2007

AbstractA methodology was developed to determine the potential for aldicarb to leach to ground water and appear at or near concentrations of concern in different areas of the continental United States. Aldicarb use in 11 “ground water regions,”as defined by Heath (1984), was evaluated. These regions were selected based on significant use of aldicarb on citrus, cotton, potatoes, peanuts, and soybeans. The unit of study, therefore, became known as “crop/Heath‐Region combinations”(CHRCs). A total of 32 CHRCs were evaluated. Three measures of leaching potential were used to evaluate each CHRC. One was based on hydrogeologic vulnerability, one was based on agronomic and site‐specific characteristics, and one was based on ground water monitoring data. Each measure was rated as “high,””medium,””low” or “insufficient data” in terms of potential for aldicarb to leach for crop‐growing areas in the region. Using a weight‐of‐evidence approach, each CHRC was given a final rating of “high,”“medium,” and “low” potential to leach based on the three measures within the CHRC. Potatoes in Heath Regions 7 (Glaciated Central) and 9 (Northeast and Superior Uplands) were rated high, whereas potatoes in Regions 1 (Western Mountain Ranges), 3 (Columbia Lava Plateau), and 11 (Southeast Coastal Plain) were rated low. Cotton in Regions 1,2 (Alluvial Basins), 5 (High Plains), 10B (Gulf Coastal Plain), and 11 were rated low. Citrus and peanuts in Region 11 were rated high. All other CHRCs, including all soybean CHRCs, were rated medium.
EPA's Approach to Evaluating and Cleaning Up Ground Water Contamination at Superfund Sites
Authors: Haley Jennifer L. , Lang David J. , Herrinton Lisa 
Published: February 2007

AbstractEPA's approach for developing, evaluating, and selecting ground water response actions at Superfund sites with contaminated ground water involves a series of key decisions to support necessary actions. These actions include the following:Planning how the site will be managedDetermining data needsDetermining remedial action objectivesDeveloping alternativesSelecting and implementing the remedy.The key decisions should reflect a policy and decision‐making approach developed within the framework of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA 1980) as amended by the Superfund Amendments and Reauthorization Act (SARA 1986) and program policies to implement these acts. This paper outlines a flexible, iterative process, described in detail in the Guidance on Remedial Actions for Contaminated Ground Water at Superfund Sites (U.S. EPA 1988), by which ground water remedies can be identified, evaluated, selected, and implemented at Superfund sites beginning with initial site investigation tasks and ending with evaluation of implemented actions. Proper consideration of the factors presented in this paper should result in an efficient, effective procedure for making remedial action decisions for contaminated ground water that ensures protection of human health and the environment.
The Ground Water Recharge and Pollution Potential of Dry Wells in Pima County, Arizona
Authors: Wilson L.G. , Osborn M.D. , Olson K.L. , Maida S.M. , Katz L.T. 
Published: February 2007

AbstractThis paper summarizes a study to estimate the potential for dry‐well drainage of urban runoff to recharge and pollute ground water in Tucson, Arizona. We selected three candidate dry wells for study. At each site we collected samples of runoff, dry‐well sediment, vadose‐zone sediment, perched ground water, and ground water. Water content data from vadose‐zone samples suggest that dry‐well drainage has created a transmission zone for water movement at each site. Volatile organic compounds, while undetected in runoff samples, were present in dry‐well sediment, perched ground water at one site, and ground water at two sites. The concentrations of volatile organics (toluene and ethylbenzene) in the water samples were less than the corresponding EPA human health criteria. Pesticides were detected only in runoff and dry‐well sediment. Lead and chromium occurred in runoff samples at concentrations above drinking water standards. Nickel, chromium, and zinc concentrations were elevated in vadose‐zone samples at the commercial site. Of the metals, only manganese, detected at the residential site, exceeded Secondary Drinking Water Standards in ground water. It is concluded that the three dry wells examined during this study are currently not a major source of ground water pollution.
Soil‐Gas Surveying for Subsurface Gasoline Contamination Using Total Organic Vapor Detection Instruments Part I. Theory and Laboratory Experimentation
Authors: Robbins Gary A. , Deyo Brendan G. , Temple Mark R. , Stuart James D. , Lacy Michael J. 
Published: February 2007

AbstractFactors influencing the response of total organic vapor detection instruments used in soil‐gas surveying for subsurface gasoline leakage were investigated through performing theoretical assessments and laboratory experiments. Theoretical assessments indicate that total organic vapor measurements will depend on response conditions and the relative concentration of constituents in soil gas, in addition to absolute constituent levels. Laboratory tests conducted using flame ionization, photoionization and explosimeter devices indicated that conditions influencing their responses included instrument flow rate and soil‐air permeability when performing direct‐probe sampling; the linear range of the instrument; the multicomponent nature of gasoline vapors; and levels of oxygen, nitrogen, carbon dioxide and relative humidity in soil air. If an instrument's response to these conditions is not taken into account, survey results may be misleading. To circumvent adverse instrument responses, a serial dilution technique is presented.
Hydrogeology of the Brunswick (Passaic) Formation and Implications for Ground Water Monitoring Practice
Authors: Michalski Andrew 
Published: February 2007

AbstractFractured shales of the Brunswick Formation provide a major aquifer in the most industrialized region of New Jersey. Numerous cases of ground water contamination have been documented in this formation. However, effectiveness of monitoring and remediation efforts is often hampered by the use of inappropriate concepts regarding ground water flow controls in this complex aquifer system. One such concept presumes that near‐vertical fractures parallel to the strike of beds provide principal passages for the flow and produce an anisotropic response to pumping stress. Field evidence presented in this paper confirms that the Brunswick Formation hosts a gently dipping, multiunit, leaky aquifer system that consists of thin water‐bearing units and thick intervening aquitards. The water‐bearing units are associated with major bedding partings and/or intensely fractured seams. Layered heterogeneity of such a dipping multiunit aquifer system produces an anisotropic flow pattern with preferential flow along the strike of beds. Within the weathered zone, the permeability of the water‐bearing units can be greatly reduced. The commonly used hydrogeologic model of the Brunswick as a one‐aquifer system, sometimes with vaguely defined “shallow” and “deep” zones, often leads to the development of inadvertent cross‐flows within monitoring wells. If undetected, cross‐flows may promote contaminant spread into deeper units and impair the quality of hydrogeologic data. Hydrogeologic characterization of the Brunswick shales at any given site should be aimed primarily at identification of the major water‐bearing and aquitard units. Recommended techniques for this characterization include fluid logging and other in‐well tests.