bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sampling the Chemistry of Shallow Aquifer Systems — A Case Study
Authors: Pionke H. B. , Urban J. B. 
Published: February 2007

AbstractPumped waters from 14 Pennsylvania wells, located in shallow sandstone, siltstone and shale aquifers, were continuously monitored for dissolved oxygen (D. O.), nitrate (NO3), pH, electrical conductivity (EC) and water temperature in a discharge manifold at the well head. The amount of pumping or purging required to stabilize these parameter readings varied by well site and parameter being analyzed. However, the purging required was generally greatest for D. O. and least for water temperature where: D. O. < NO3 pH < EC < water temperature. Wells located near the siltstone‐shale interface generally required far more purging than did wells located elsewhere. Although parameter stability was often achieved within purging one bore volume, the complexity, diversity, and variability in the data and these well‐ground water systems, suggest that no single purging rule is appropriate. Instead, the extent of purging required before sampling these shallow aquifers should be determined by incorporating on‐site monitoring of target or related parameters into the purging process.From a sampling perspective, the relationship between NO3 and D. O. concentrations during purging were analyzed relative to aquifer type. For most wells located in sandstone or siltstone, NO3 concentrations remained relatively constant during purging irrespective of changes in D. O. For most wells located in shale, these two were positively and similarly correlated, suggesting that a general relationship exists.
Subsurface Venting of Vapors Emanating from Hydrocarbon Product on Ground Water
Authors: Crow Walter L. , Anderson Eric P , Minugh Edward M. 
Published: February 2007

AbstractThe results of an API‐sponsored pilot‐scale subsurface venting system study are presented. The purpose of this study was to evaluate the effectiveness of forced venting techniques in controlling and removing hydrocarbon vapors from a subsurface formation. Both qualitative and quantitative sampling and analytical procedures were developed to measure hydrocarbon vapors extracted from the soil. Vapor recovery and equivalent liquid product recovery rates were measured at each test cell evacuation rate.Two identical test cells were installed. Each cell contained 16 vapor monitoring probes spaced at distances from 4 to 44 feet from a vapor extraction (vacuum) well. Each cell was also configured with two air inlet wells to allow atmospheric air to enter the subsurface formation. The vapor monitoring probes were installed at three discrete elevations above the capillary zone. In situ vapor samples were obtained periodically from these probes to measure changes in vapor concentration and composition while extracting vapors from the vacuum well at three different flow rates (18.5 scfm, 22.5 scfm and 39.8 scfm). In situ vapor samples were analyzed using a portable gas chromatograph to quantify and speciate the vapors. Vacuum levels were also measured at each vapor sampling probe and at the vacuum well.The soil venting techniques evaluated during this study offer an alternative approach for controlling and eliminating spilled or leaked hydrocarbons from sand or gravel formations of high porosity and moderate permeability. These techniques may also be used to augment conventional liquid recovery methods. The data collected during this study will be useful in optimizing subsurface venting systems for removing and controlling hydrocarbon vapors in soil. Study results indicate pulsed venting techniques may offer a cost‐effective means of controlling or eliminating hydrocarbon vapors in soil.
Detecting Changes in Ground Water Quality at Regulated Facilities
Authors: Loftis Jim C. , Harris Jane , Montgomery Robert H. 
Published: February 2007

AbstractThe Resource Conservation and Recovery Act (PL 94–580) and related federal and state legislation have mandated routine monitoring of ground water quality at regulated facilities. The objective of the required monitoring activities is detection of adverse changes in ground water quality caused by the facilities.Both failure to detect pollution and an incorrect determination of pollution can be very expensive. It is crucial, therefore, that monitoring programs be designed and operated to provide statistically sound information. It is equally important that users of ground water quality data understand the nature and limitations of information from monitoring.To address the preceding issues, the authors present a general approach to analyzing ground water quality data in light of the stated monitoring objective. The suggested approach accounts for “natural” variation in background water quality through pairing of observations. The limitations of quarterly sampling for detecting small changes in quality over a short time frame are discussed.
A Multiple‐Packer/Standpipe System for Ground Water Monitoring in Consolidated Media
Authors: Welch S.J. , Lee D.R. 
Published: February 2007

AbstractA simple system of packers and plastic standpipes has been used for sampling water and monitoring piezometric levels at four to six selected points in 2.98 inches (76mm) bedrock boreholes for up to five years. The relatively inexpensive packers held a required inflation pressure for at least four months and could be removed from the borehole when desired. The approach used is adaptable for other purposes and has been used for borehole dilution tests and vertical tracer tests.
Monitoring Dissolved Oxygen in Ground Water: Some Basic Considerations
Authors: Rose Seth , Long Austin 
Published: February 2007

AbstractDissolved oxygen (D.O.) concentration has a significant effect upon ground water quality by regulating the valence state of trace metals and by constraining the bacterial metabolism of dissolved organic species. For these reasons, the measurement of dissolved oxygen concentration should be considered essential in most water quality investigations. D.O. measurements have been frequently neglected in ground water monitoring. This is because O2 has often been assumed absent below the water table; measurement of O2, concentrations is not mandated by drinking water standards; and the redox potential has previously been considered an adequate and encompassing electrochemical measurement. Redox potentials, however, cannot adequately predict dissolved oxygen concentrations nor can D.O. concentrations be used to calculate redox potentials.D.O. concentrations can be measured precisely in the field by titration or electrode methods. The best methods of sample recovery are those that use positive pressure displacement devices. A fully adequate sampling procedure will isolate ground water from the atmosphere and will collect samples at restricted depth intervals at ambient temperature and pressure.
The Representativeness of Pore Water Samples Collected from the Unsaturated Zone Using Pressure‐Vacuum Lysimeters
Authors: Peters Charles A. , Healy Richard W 
Published: February 2007

AbstractPressure‐vacuum lysimeters are an inexpensive means of collecting numerous water samples from the same location in the unsaturated zone over a period of time. However, prior studies have indicated that the chemistry of water samples may be altered by the collection technique, creating concern about the representativeness of the pore water samples obtained. A study conducted using soil water pressure‐vacuum lysimeters in outwash sand and glacial till deposits demonstrates that for non‐dilute‐solution samples the effect on pH of sampling with lysimeters is minimal, and that measured major cation and anion concentrations are representative of the natural pore water; trace‐metal concentrations can be significantly altered by collection procedures at low concentrations.
Making the Most of Field‐Measurable Ground Water Quality Parameters
Authors: Garner Stuart 
Published: February 2007

AbstractThe primary ground water quality parameters temperature, pH, Eh, electrical conductivity, and dissolved oxygen must be measured in the field, though not necessarily in situ, to avoid errors caused by contamination such as aeration. These measurements, when made during the purging of a well, can be used to verify aquifer‐representativeness of a sample, detect abnormalities within an aquifer, check laboratory measurements to detect sample deterioration, and prompt further monitoring actions.Electronic sensors are available for reliable field measurement of the primary parameters. Measurements should be made continuously in an in‐line flow cell that is sealed from the atmosphere. Flow can be provided by a bladder pump dedicated to a single well. Samples for laboratory analysis should be collected when the values of the primary parameters do not vary more than 10 percent per casing volume pumped.
Contamination of Farmstead Wells by Pesticides, Volatile Organics, and Inorganic Chemicals in Kansas
Authors: Steichen James , Koelliker James , Grosh Doris , Heiman Alan , Yearout Robert , Robbins Victor 
Published: February 2007

AbstractConcern about the public health consequences of possible contamination of farmstead wells led to a random statewide survey in Kansas. Results of the analyses showed that 8 percent of tested wells had detectable amounts of pesticides, 2 percent had detectable amounts of volatile organic chemicals, and 37 percent had some inorganic contaminant exceeding the maximum contaminant level (MCL). Nitrate was the most common source of inorganic contamination, exceeding the MCL in 28 percent of the wells. Selenium levels exceeded the MCL in 9 percent of the wells. A multiple regression model for nitrate‐N was developed. The factors included the age of the well, land use around the well, and the distance to the closest possible source of organic contamination.
Migration of Petroleum Products Through Sandy Hydrogeologic Systems
Authors: Abdul Abdul S. 
Published: February 2007

AbstractLaboratory column experiments were carried out to study the migration of petroleum products through a sandy porous medium. It was found that the oil pressure needed to displace water from the pores of the sand medium increased with depth below the top of the column. While oil under negative pressure displaced water through the variably unsaturated zone, a significant vertical column of oil was needed to displace water from the pores at the water table. These results indicate that oil penetration to and below the water table will occur only if the porous medium is highly conductive and the rate of oil leak is high. For small to moderate leak rates and hydraulic conductivities, oil would preferentially spread laterally through the zones above the water table. This process of spreading could serve as a natural barrier to severe aquifer contamination by petroleum products.A simplified procedure was developed to give an order‐of‐magnitude estimate of the preferred subsurface migration pathways of leaked petroleum products. This procedure utilizes the main drainage and wetting curves for oil and water and the interfacial pressure between these two fluids. This approach could be useful in guiding exploratory investigations, reducing both the risk for further spreading of the contaminants and the investigative cost.
Evaluation of a Carbon Adsorption Method for Sampling Gasoline Vapors in the Subsurface
Authors: Wallingford Edward D. , DiGiano Francis A. , Miller Cass T. 
Published: February 2007

AbstractMonitoring of the vapor phase has emerged as a very convenient method for detecting volatile organic contaminants in the subsurface. It can provide a reliable way of placing ground water monitoring and recovery wells. The most common method uses a driveable ground probe (DGP) to extract a vapor‐phase sample followed by direct injection of the vapor into a portable gas chromatograph (GC). However, many regional offices of regulatory agencies and consultants do not have ready access to such equipment. This research explores an alternative–the carbon adsorption method—in which the vapor is withdrawn by the DGP but concentrated on a small activated carbon trap (150mg). The carbon traps can be returned to a central laboratory for solvent extraction and GC analysis. This provides the advantages of increased sensitivity, reduction in field equipment and convenience of in‐lab analyses (multiple GC injections are possible). A simple DGP and carbon trap system was constructed and tested at a field site. Vapor‐phase concentrations of target compounds present in gasoline were mapped quite conveniently, ranging from 10,000μg/liter (vapor phase) to less than 10μg/L. These concentrations were also shown to decrease in the direction of the ground surface, as expected. Measurements of target compounds in soil showed that the vapor phase contributed a large fraction of the total contaminant burden where a non‐aqueous‐phase layer (NAPL) had been identified; as important, however, is the rather uniform contamination of the soil outside the NAPL region. Finally, the concentrations of target compounds in the vapor phase and ground water could be related in a manner roughly described by a simple equilibrium model, although exceptions were noted.
Small‐Scale Retrospective Ground Water Monitoring Studies for Agricultural Chemicals: Study Design and Site Selection
Authors: De Martinis James M. 
Published: February 2007

AbstractA small‐scale retrospective ground water monitoring study is designed to determine if, after years of normal usage, an agricultural chemical has leached to ground water. These studies are conducted on actively planted fields in hydrogeologically vulnerable areas. Because the results of such studies may have larger ramifications for the particular agricultural chemical over much broader hydrogeologic and geographic areas, care must be exercised in selecting particular fields to be monitored and in establishing site‐specific ground water monitoring networks.The U.S. Environmental Protection Agency, Office of Pesticide Programs, has established draft guidelines and suggested field protocols for such studies. These guidelines serve as a baseline for such studies, though many other hydrogeologic and agronomic factors play significant roles. Small‐scale retrospective studies are ordinarily broken into a series of tasks that lead to the selection of a suitable test site(s) by determining on a national scale where to monitor; meeting minimum hydrogeologic and agronomic criteria; and establishing a ground water monitoring program.A detailed hydrogeologic vulnerability analysis is conducted in product use areas for the chemical being studied. A series of screening steps results in a subset of moderate‐ to high‐use counties that are underlain by permeable soils and vulnerable to ground water impacts from agricultural chemicals. Once these counties are determined, suitable test fields can be selected.The individual site selection criteria can be exhaustive. However, these criteria in combination with one another are necessary to ensure that the selected sites will yield information as to whether or not the chemical has leached through the soil profile and the unsaturated zone to ground water. The following criteria are considered essential to a particular site: flat topography; “workable” field size; documented history of use of the chemical being monitored; avoidance of regional and farm‐specific point sources; typical irrigation and farm practices for the crop on which the chemical is applied; farmer cooperation; field accessibility; permeable soils and unsaturated zone; and shallow water table. There are also other hydrogeologic and agronomic parameters that need to be assessed prior to site selection.The hydrogeologic and agronomic criteria are not always easily met. For example, the topography and shallow water‐table criteria could eliminate key agricultural areas in the United States where the agricultural chemical to be monitored may be used. However, the data generated during these field‐scale retrospective studies, when properly conducted, can provide information regarding whether or not a particular agricultural chemical has leached to ground water under worst‐case conditions.
Field Evaluation of a Slim‐Hole Borehole Induction Tool
Authors: Taylor Kendrick C. , Hess John W. , Mazzela Aldo 
Published: February 2007

AbstractThe Geonics EM‐39 borehole induction tool was field tested to evaluate its performance under controlled conditions. The effects of temperature changes and borehole fluids were found to be negligible under most conditions. The instrument can be calibrated in large bodies of water of known electrical conductivity. When properly calibrated, the ± 5 percent accuracy claimed by the manufacturer is obtainable. A geologic unit must be at least 4m thick for the electrical conductivity of the unit to be accurately measured. Geologic units thinner than 4m thick can be detected if the conductivity contrast to adjacent units is sufficiently large.
In Situ Bioreclamation: A Cost‐Effective Technology to Remediate Subsurface Organic Contamination
Authors: Wilson Scott B. , Brown Richard A. 
Published: February 2007

AbstractIn situ bioreclamation is a proven technology that cost‐effectively treats organic contamination in subsurface environments. As a remediation strategy, it reduces both the contamination dissolved in ground water, as well as residual soil‐bound contamination.To maximize biodegradation, the technology is applied after conducting laboratory studies. Application of the technology involves infiltrating necessary nutrients to the contaminated subsurface.Results of a specific case study indicate excellent performance with rapid cleanup of petroleum hydrocarbon contamination from soils and ground water.Costs associated with in situ bioreclamation technology showed a savings of approximately 50 percent over simple pump‐and‐treat technology. Time frame for cleanup was shown to be approximately 30 percent of the projected time frame of simple pump‐and‐treat technology.
A Practical Approach to Shallow Petroleum Hydrocarbon Recovery
Authors: Hayes Douglas , Henry Evan C. , Testa Stephen M. 
Published: February 2007

AbstractA practical pumping system for the recovery of free petroleum hydrocarbon product from shallow aquifers has been developed. The system is patterned after suction‐lift well point dewatering systems used in the construction industry. Pumping equipment consists of double‐diaphragm suction‐lift pumps manifolded to up to four recovery wells. Recovery wells are constructed with screens below the water table and sealed wellheads to enable vacuum‐assisted flow of fluids to the wells. Pumps utilized are pneumatically driven, can be pumped dry without damage, induce a vacuum on the wells when pumping dry, and provide delivery of pumped fluids to fluid separation and storage facilities. The system is effective in both low‐ and high‐permeability formations due to the wide range in available pumping rates afforded by the pumps.
Limitations of Monitoring Wells for the Detection and Quantification of Petroleum Products in Soils and Aquifers
Authors: Abdul Abdul S. , Kia Sheila F. , Gibson Thomas L. 
Published: February 2007

AbstractTheoretical analysis and laboratory column experiments were carried out to investigate the conditions required for petroleum products (oil) to flow into a well installed through a sandy porous medium contaminated with the oil. The results indicated that oil would flow into a well only after a layer of “free oil” is formed in the adjacent porous medium. Because significant quantities of oil could be stored in the porous medium under the influence of capillary suction prior to the formation of the zone of free oil, the presence of oil in a well would indicate an advanced stage of oil contamination of the subsurface. While monitoring wells could be used to delineate the extent of the free‐oil plume and the plume of dissolved petroleum constituents, they are not useful for delineating the extent of capillary held oil.The experimental results also indicated that the ratio of the oil‐layer thickness in the well to that in the porous medium is not a constant as is sometimes assumed in practice. Further, estimates of the oil thickness in the medium based on the oil thickness in wells and on capillary properties measured in the laboratory were sensitive to the values of the parameters used in these estimates. The measured thickness of the oil layer in a monitoring well alone may not yield reliable estimates of the amount of oil in the subsurface, and assuming that the oil‐thickness ratio is a constant can lead to inadequate site assessments and inappropriate remedial plans.
A Remedial Investigation of an Organically Polluted Outwash Aquifer
Authors: Jackson Richard E. , Patterson Ronald J. 
Published: February 2007

AbstractA glacial outwash aquifer underlying the Gloucester Landfill near Ottawa, Canada, has become polluted with various organic chemicals following the disposal of laboratory solvents in shallow trenches immediately above the aquifer. Several remedial alternatives have been considered by the government of Canada. Impermeable barrier walls were rejected as being unsuitable given the permeable nature of the underlying bedrock. It appears improbable that pools of liquid organic chemicals (DNAPLs) exist within the aquifer, although ganglia are likely present. Therefore, much of the contaminant plume can be removed hydraulically over a period of five years by the operation of four purge wells discharging to an on‐site treatment plant from which the purified water is returned to the aquifer by recharge wells. The residual contamination is anticipated to be cleaned up by in situ biorestoration techniques currently under development.
Hydraulic Conductivity Measurements in the Unsaturated Zone Using Improved Well Analyses
Authors: Elrick D.E. , Reynolds W.D. , Tan K.A. 
Published: February 2007

AbstractThe flow of ponded water into and through the unsaturated zone depends on both the saturated and unsaturated components of the hydraulic conductivity. Recent studies indicate that the ratio of the saturated (Kfs) to the unsaturated (φm) components (Kfs/φm=α*) of flow lies within prescribed bounds for most field soils, i.e., 1m−1≤α*≤ 100 m−1. In addition, the fact that the calculation of Kfs and φm is not strongly dependent on the choice of α*, suggests that a site estimation of α* leads to reasonable “best estimates” of Kfs and φm when using the constant head well permeameter technique. As a consequence, measurement of the steady flow rate using only one ponded head may be all that is necessary for many practical applications. Multiple head measurements or independent measurements of α* or φm can be used, however, to give more accurate estimates of Kfs if required.
Marketing Perspectives for the 1990s
Authors: Pierro W.J. 
Published: February 2007

AbstractA recent survey sent to 500 environmental consulting firms across the United States has helped document specific promotional vehicles used within the environmental consulting industry, as well as highlighted a wide spectrum of attitudes toward adopting a formalized marketing function within a technically oriented firm. The population of study, from which a 22 percent response rate was received, consisted of scientific, engineering, and combination firms providing hydrogeologic, environmental assessment, natural resource, and hazardous waste management services. The study, conducted for a master's thesis in business administration, was supported in part by Hofstra University of Hempstead, New York.The study indicated that consultants' resistance toward professional services marketing was directly proportional to the amount of referral work they received; that environmental consultants promote themselves significantly more often through commercial rather than non‐commercial vehicles; and that scientific firms were significantly more resistant to adopting a marketing function than engineering or combination scientific/engineering firms.