bluuebunny/crossref_metadata_2025_split huggingface dataset:
Approximation of Biodegradation Rate Constants for Monoaromatic Hydrocarbons (BTEX) in Ground Water
Authors: Wiedemeier Todd H. , Swanson Matthew A. , Wilson John T. , Kampbell Donald H. , Miller Ross N. , Hansen Jerry E. 
Published: February 2007

AbstractTwo methods were used to approximate site‐specific biodegradation rates of monoaromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylenes [BTEX]) dissolved in ground water. Both use data from monitoring wells and the hydrologic properties of the quifer to estimate a biodegradation rate constant that can be used in ground water solute fate and transport models. The first method uses a biologically recalcitrant tracer in the ground water associated with the hydrocarbon plume to normalize changes in concentration of BTEX under anaerobic conditions; attenuation of the tracer is attributed to dilution, sorption, and/or volatilization. Attenuation of BTEX in excess of the attenuation of the tracer is attributed to biodegradation, although other processes may affect the observed rate. The second method assumes that the plume has evolved to a dynamic steady‐state equilibrium. A one‐dimensional analytical solution to the advection‐dispersion equation is used to extract the rate of attenuation that would be necessary to produce a steady‐state plume of the configuration found at the site. Attention is attributed largely to biodegradation bacause the analytical solution removes the effects of sorption and dispersion and volatilization is assumed to be minimal.Neither method fully accounts for the effects of continuing dissolution of BTEX in the source area or nonlinear sorption. Therefore, the rats cannot be attributed fully to biodegradation, but still are useful for ground water contaminant fate and transport modeling. The methods were applied to a data set from a JP‐4 jet fuel spill at Hill Air Force Base, Utah. In estimats along two seprate flow paths, natural attenuation rates for BTEX ranged form 0.006 to 0.038 day−1, with most rates near 0.02 day−1. The rate for benzene ranged from 0.025 to 0.038 day−1. The rates of attenuation of individual BTEX compounds as estimated by the two methods were in close aggrement. For an individual compound, the rate estimated using the second method was at most 36 percent greater than, but usually within 20 percent of, the rate estimated using the first method, suggesting that intrinsic bioremediation was the dominant process that attenuated BTEX.
Reduced Sediments: A Factor in the Design of Subsurface Oxidant Delivery Systems
Authors: Korom Scott F. , McFarland Michael J. , Sims Ronald C. 
Published: February 2007

AbstractA preliminary field performance evaluation of in situ bioremediation of a contaminated aquifer at the Libby, Montana, Superfund site, a former wood preserving site, was conducted for the Bioremediation Field Initiative sponsored by the U.S. Environmental Protection Agency (U.S. EPA). The current approach for site remediation involves injecting oxygen and nutrients into the aquifer to stimulate microbial degradation of target compounds that include polycyclic aromatic hydrocarbons and pentachlorophenol. The preliminary field evaluation determined that, in addition to the oxygen demand associated with the microbial oxidation of the organic contamination, uncontaminated aquifer sediments at the site are naturally reduced and also exert a significant oxygen demand. This conclusion is supported by three types of information: (1) analyses of ground water samples; (2) results from a field‐scale tracer test; and (3) results of laboratory evaluations of oxygen use by reduced aquifer sediment samples. An estimate of the cost of supplying hydrogen peroxide to satisfy the oxygen demand of the uncontaminated reduced sediments is provided to demonstrate that the additional cost of oxidizing the reduced sediments could be significant. The presence of naturally occurring reduced sediments at a contamination site should be considered in the design of subsurface oxidant delivery systems.
A Field Test of Electromigration as a Method for Remediating Sulfate from Shallow Ground Water
Authors: Patterson Charles G. , Runnells Donald D. 
Published: February 2007

AbstractEloctromigraiion offers a potential tool for remediating ground water contaminated with highly soluble components, such as Na+, Cl, NO3 and SO4−. A field experiment was designed to lest the efficacy of electromigration for preconcontrating dissolved SO42 in ground water associated with a fossil‐fuel power plant. Two shallow wells, 25 feel apart (one 25 feel deep, the other 47 feet deep), were constructed in the upper portion of an unconfined alluvial aquifer. The wells were constructed with a double‐wall design, with an outer casing of 4‐inch PVC and an inner lube of 2‐inch FVC; both were fully slotted (0.01 inch). Electrodes were constructed by wrapping the inner lulling with a 100‐foot length of rare‐earth metal oxide/copper wire. An electrical potential of 10.65 volts DC Was applied, and tests were run for periods of 12, 44, and 216 hours. Results showed large changes in the pH from the initial pH of ground water of about 7.5 to values of approximately 2 and 12 at the anode and cathode, respectively. Despite the fact that the test conditions were far from ideal, dissolved SO42‐; was significantly concentrated at the anode. Over a period of approximately nine days, the concentration of SO42‐ at the anode reached what appeared to he a steady‐state value of 2200 mg/L. compared lo the initial value in ground water of approximately 1150 mg/L. The results of this field lest should encourage further investigation of electromigration as a tool in the remediation of contaminated ground water.
Vitamin B12‐Catalyzed Dechlorination of Perchloroethylene Present as Residual DNAPL
Authors: Lesage Suzanne , Brown Susan , Millar Kelly 
Published: February 2007

AbstractThe goal of this study was the cleanup of residual solvents in the saturated zone using an in situ biochemical treatment. Perchloroethylene (PCE) was chosen as a model compound because it is the most commonly found organic ground water contaminant. A mixture of vitamin B12 with titanium citrate was pumped as the remedial solution through a column containing 100 μL of PCE residual. The rate of reaction was found to be first order with respect 10 the concentration of PCE and to the concentration of vitamin B2. At 10 ppm B12, more than 85 percent PCM was degraded to trichloroelhylene (TCE) and dichloroelhylene (DCE) in two hours. The presence of low to moderate concentrations of organic carbon had no significant effect on the reaction. Vitamin B12 reduced by titanium citrate was found lo be compatible with the survival of anaerobic bacteria. The four major advantages of the biochemical system over the use of anaerobic bacteria are that (1) the rate is faster: (2) there is no need for the careful balance of nutrients or the addition of an extraneous carbon source: (3) there is no restriction in the concentration range of the compound to be treated; and (4) the remedial solution is mobile, even in the presence of organic carbon.
Electrical Leak Detection System for Landfill Liners: A Case History
Authors: White C.C. , Barker R.D. 
Published: February 2007

AbstractAs landfill specifications become more stringent in the United Kingdom, the development of increasingly sophisticated monitoring methods is necessary to meet environmental protection goals. This case history describes the development of a 2‐million‐cubic‐meter‐capacity landfill located in a sandstone quarry and 1 km from a public water supply borehole, where the sensitivity of the site to ground water contamination and the proximity to a public water supply borehole are particular issues.The landfill design incorporated a more sensitive environmental monitoring system, using a geophysical technique. The monitoring system comprises a permanent grid of electrodes installed beneath the landfill, connected by multicore cable to a computer‐controlled earth resistance meter and switching unit in the site weighbridge. It was designed to detect holes in the landfill liner prior to and after covering with waste and to monitor the migration of contaminants beneath the landfill before they reach the perimeter observation boreholes, should leakage occur.Such monitoring can enable the integrity of the landfill to be routinely reviewed; holes can be repaired if they are readily accessible and, if not, monitoring provides an early warning to enable the implementation of any additional monitoring or corrective action, based on the environmental risk posed by the site.The system was first used as a quality assurance test once the landfill liner, which covered an area of 3 hectares, was installed. The system proved sensitive, detecting a hole consisting of two narrow knife cuts. Such sensitivity allows a high degree of confidence to be placed upon the integrity of the liner resulting in a significant contribution to public reassurance. The landfill is now operational, and monitoring using the geophysical system will be undertaken on a monthly basis for the first year, with the frequency of monitoring reviewed thereafter.
Control of BTEX Migration Using a Biologically Enhanced Permeable Barrier
Authors: Borden Robert C. , Goin Russell Todd , Kao Chih‐Ming 
Published: February 2007

AbstractA permeable barrier system. consisting of a line of closely spaced wclls. was installed perpendicular to ground water flow to control the migration of a dissolved hydrocarhon plume. The wells were charged wiih concrete briquets that release oxygen and nitrate at a controlled rate. enhancing aerobic bio‐degradation in the downgradient aquifer.Laboratory batch reactor experiments were conducted to identify concrete mixtures that slowly released oxygcn over an extended time period. Concretes prepared with urea hydrogen peroxide were unsatisfactory, while concretes prepared with calcium peroxide and a proprietary formalation of magnesium peroxide (ORC®) gradually released oxygen at a steadily declining rate. The 21 percent MgO2conerete cylinders and briquets released oxygen at measurable rates for up to 300 days, while the 14 percent CaO2briquets were exhausted by 100 days.A full‐scale permeable barrier system using ORC was constructed at a gasoline‐spill site. During the first 242 days of operation. total BTFX decreased from 17 to 3.4 mg/L. and dissolved oxygen increased from 0.4 to 1.8 mg/L. during transport through the barrier. Over time, BTEX treatment efficiencies declined. indicating the barrier system had becomc less effective in releasing oxygen and nutrients to the highly contaminated portion of the aquifer. Point dilution tests and sediment analyses performed at the conclusion of the project indicated that ihc aquifer in the vicinity of the remediation wells had been clogged by precipitation with iron minerals. This clogging is believed to result from high pH from the concrete and oxygen released by ihc ORC. Oxygen‐releasing permeable barriers and other aerobic bioremediation processes should be used with caution in aquifers with high levels of dissolved iron.
Effects of Olestra on Organic and Solids Removal in Septic Tanks
Authors: McAvoy Drew C. , Greff Jacqueline A. , Webb D. Ronald , Allgood Greg S. 
Published: February 2007

AbstractA field study was conducted to examine the fate and potential effects of olestra, a non‐caloric fat replacer, in septic tanks. The study compared the performance of parallel septic tanks, which were led domestic waste water with liquid and solid forms of olestra, against a control tank receiving waste water without olestra. Results showed that 36 g/d of olestra dosed to the tanks (a three‐fold exaggeration of expected loadings) had no adverse effect on system operation (based on visual observations and sludge accumulation) or performance (based on removal of organic content and solids) over a six‐month period. Removal efficiencies for total suspended solids (TSS), carbonaceous biochemical oxygen demand (CBOD), and chemical oxygen demand (COD) were not significantly different (p<0.05) in the olestra tanks when compared to the control tank. In addition, a relatively small amount of the total olestra added (3 to 6%) was recovered in the septic tank effluents over the course of the study. Accumulation of tank solids was not affected as measured sludge levels in the tank at the middle and end of the study showed no difference between the olestra dosed tanks and the control tank.
Design and Optimization of a Ground Water Monitoring System Using GIS and Multicriteria Decision Analysis
Authors: Dutta D. , Gupta A. Das , Ramnarong V. 
Published: February 2007

AbstractA GIS‐based methodology has been developed to design a ground water monitoring system and implemented for a selected area in Mae‐Klong River Basin, Thailand. A multicriteria decision‐making analysis has been performed to optimize the network system based on major criteria which govern the monitoring network design such as minimization of cost of construction, reduction of kriging standard deviations, etc. The methodology developed in this study is a new approach to designing monitoring networks which can be used for any site considering site‐specific aspects. It makes it possible to choose the best monitoring network from various alternatives based on the prioritization of decision factors.
Inorganic Water Quality Monitoring Using Specific Conductance in Mexico
Authors: Marín Luis E. , Steinich B. , Escolero Oscar , Leal Rosa María , Silva Braulio , Gutierrez Susana 
Published: February 2007

AbstractFive inorganic geochemical data sets with ion balances less than or equal to 5% (for different hydrogeologic basins in Mexico) were used to construct specific conductance (SC) vs. total dissolved solids (TDS) curves for each aquifer. These curves allow one to proxy the specific conductance for inorganic water quality. The data from these five curves were integrated to form a “global” curve for Mexico. The equation that defines the line is SC = 1.40 TDS + 18. We propose that, in addition to allowing ground water monitoring, establishing a SC vs. TDS curve may be implemented to monitor drinking water supplies such as wells and reservoirs. If anomalously high values are observed, this would warrant detailed geochemical sampling.
Demonstration of a Microbiologically Enhanced Vertical Ground Water Circulation Well Technology at a Superfund Site
Authors: Lakhwala Fayaz S. , Mueller James G. , Desrosiers Richard J. 
Published: February 2007

AbstractA full‐scale ground water circulation well (GCW) system was installed and operated to demonstrate in situ remediation of soil and ground water impacted with a mixture of chlorinated and nonchlorinated organic compounds at a Superfund site in upstate New York. System performance and applicability under site‐specific conditions were evaluated based on the system's ability to meet the New York State Department of Environmental Conservation (NYSDEC) cleanup goals for target compounds in ground water and soil. Contaminants from the unsaturated zone were mobilized (volatilized) by one‐way vacuum extraction, and treated via enhanced biodegradation (bioventing). In the saturated zone, contaminants were mobilized by soil flushing (solubilized) and treated by a combination of air stripping and biodegradation. An in situ aqueous phase bioreactor, and an ex situ gas phase bioreactor, were integrated into the system to enhance treatment via bioremediation. After 15 months of operation, the mass of target contaminants in soil and ground water combined had been reduced by 75%. Removal by biological mechanisms ranged from 35% to 56% of the total observed mass reduction. The in situ and the ex situ bioreactors mineralized 79% and 76%, respectively, of their target biodegradable contaminant loads. Results indicate that some mass reduction in target contaminants may have been from aerobic and aerobic processes within the circulation cell. Nonchlorinated compounds were relatively easy to mobilize (volatilize, solubilize, and/or transport) and treat when compared to chlorinated compounds. The data collected during the 15‐month study indicate that remediation could be accomplished at the Sweden‐3 Chapman site using the technology tested.
Using Phase Diagrams to Predict the Performance of Cosolvent Floods for NAPL Remediation
Authors: Falta Ronald W. 
Published: February 2007

AbstractCosolvent flooding using water miscible solvents such as alcohols has been proposed as an in situ NAPL remediation technique. This process is conceptually similar to enhanced oil recovery (EOR) using alcohols and some surfactant formulations. As a result of interest in the EOR aspects of these systems, analytical and graphical methods based on fractional flow theory were developed in the petroleum engineering literature for modeling theses floods. The existing fractional flow solutions have not been used previously in environmental applications of cosolvent flooding, but they are applicable and provide many useful insights into the process. These applications are discussed, with an emphasis on emplaining the mechanisms which tend to mobilize trapped NAPL during a cosolvent flood. The theory provides a simple way to predict the general behavior of a cosolvent flood using the phase diagram. It is concluded that the one‐dimensional performance of a cosolvent flood can be predicted largely by inspection of the ternary phase diagram. In particular, the nature of the cosolvent flood depends primarily on the position of the cosolvent injection concentration relative to a critical the line extension which passes through the plait point, tangent to the binodal curve.
Modeling and Remediation of Ground Water Contamination at the Engelse Werk Wellfield
Authors: Wang Xichuan , Ngo Truong X. , Zhou Yangxiao , Nonner Jan C. 
Published: February 2007

AbstractContaminants have been threatening the Engelse Werk wellfield located between the town of Zwolle and the IJssel River in the Netherlands. Chemical analysis of water samples taken in production wells, both at the IJssel River and near the Zwolle railway station, indicated elevated concentrations of mainly organic contaminants including benzene, bentazon, acenaftene, trichloroethane, and bromacil. Immediate contaminant prevention and remediation measures are needed to safeguard the production wells. Ground water flow and transport models were developed to assist in the design of remediation strategies. Ground water flow models indicated that the IJssel River and a waste disposal ditch at the railway station are within the capture zone of the wellfield. A chloride transport model simulated minimum travel times in the order of four to 13 years for contaminants in the IJssel River to reach the production wells of the wellfield. A transport model for benzene was set up to advise on the remediation measures to be taken at the waste disposal ditch to clean up the contamination in the upper aquifer between this site and the Engelse Werk wellfield. The designed remediation system consists of 12 pumping wells with a combined capacity of 1650 m3/day. The system is capable of reducing the benzene levels at the threatened production wells at the Engelse Werk wellfield to a permissible level below 0.1 μg/L within a period of 5 years.
Downhole Weir for Measuring Flow Rate in RecirculationWellsWells
Authors: Gilmore Tyler , Davis John , Coates James 
Published: February 2007

AbstractRecirculating wells are increasingly being used for ground water remediation and aquifer characterization investigations. Determination of flow rate is required for proper design and spacing of recirculation wells. The measurement of flow rate, however, can be difficult using standard equipment. To overcome some of the flow measurement problems associated with more common measurement systems, a new device in the form of a downhole weir was developed for recirculating wells that use a two‐casing design. The weir was designed to measure flow rates between 10 and 40 gpm. In this flow range, the weir had an accuracy of ±2.8 gpm. This accuracy may be improved with some modifications.
Field Demonstration of Permeable Wall Flushing for Biostimulation of a Shallow Sandy Aquifer
Authors: Devlin J. F. , Barker J. E 
Published: February 2007

AbstractA pilot‐scale nutrient injection will (NIW) (4 m by 4 m by 1 m) was installed in the Borden Aquifer lo serve as a pulsed injection source of a potassium acetate solution for the stimulation of anaerobic microbial activity. The success of the flushing procedure was evaluated by monitoring the breakthrough of the acetate solution at several multilevel piezometers installed in the wall. Although some variation in the ground water velocity was observed with depth, the wall was flushed with reasonable uniformity after about six hours of injection and withdrawal, representing about one pore volume, Calculations bused on head level data collected during the flush, and on the solute breakthrough curves, indicated that about 90% of the flow induced by the pumping and injecting was confined to the permeable wall. These results show that a permeable wall injection system is a viable method of introducing solutes uniformly to a cross section of aquifer, with minimal perturbation of the natural flow system. In addition lo its importance for the biostimulation system tested in this project the flushing of permeable walls may have applications in other semi‐passive remedial systems, such as the rejuvenation of reactive barriers.
Geophysical Investigations of Cased Well Completions
Authors: Wheaton John , Bohman Bob 
Published: February 2007

AbstractMonitoring and production wells must be carefully completed to ensure protection of ground water resources. public health. and quality of hydrogeologic data. Poor completions and annular leakage can cause ground water to be lost to other aquifers, discharged to the ground surface, or contaminated by surface water or other ground water. Knowledge of and confidence in specific well completions are vital to the interpretation of potential well problems and hydrologic data.Once a well is finished, the only access for inspection is via the casing. Water well completion forms provide only a record of the intended completion and offer few insights into completion (or post‐completion) problems. Borehole geophysical tools, however. can provide valuable completion data in certain settings.A variety of geophysical equipment and techniques is available to evaluate cased wells. The availability and cost of some oil‐field techniques, however, are sufficiently prohibitive to discourage use in water wells and monitoring wells. Standard, readily available borehole geophysical tools can provide useful information to verify or refute a completion report. To apply borehole techniques to completed wells, however, the tools must be calibrated by logging known completions in a controlled setting.This project included laboratory calibration tests of omni‐directional and focused gamma‐gamma density tools, and field tests involving these logs plus caliper, natural gamma, neutron, electrical. and sonic logs. Tool responses were measured in 312 laboratory tests representing different tools and well completions; the field tests were conducted in nine monitoring wells in eastern Montana.The study demonstrated a suite of readily available, cost‐effective tools that could identify most completion components in actual monitoring wells. Caliper. (4Pi) gamma‐gamma density, and full‐waveform sonic logs are probably the most valuable of the tools tested. Casing material was clearly distinguished by all nuclear tools. Grouts were identified using omni‐directional 4Pi density tools: in some situations, focused gamma‐gamma density and neutron logs were also helpful, Grout thickness was difficult to determine in the. field settings, to Each individual tool should be calibrated in known settings prior to use in field investigations, and the results carefully evaluated.