bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Method for Collecting Core Samples Without a Drilling Rig
Authors: Starr Robert C. , Ingleton Robert A.
Published: February 2007

A new piston sampler allows the collection of high‐quality core samples from sand, silt or clay, up to depths of 18 meters. The sampler is operated by a one‐ or two‐person crew without a drilling rig. The sampler and ancillary equipment fit easily into a half‐ton truck, making this a highly portable sampling system. Other advantages include minimal mechanical disturbance and precisely known sample depth. Casing is not required to maintain an open corehole below the water table and drilling fluid is not used in the corehole, so the solids and pore water of the sample should not be contaminated by foreign fluids. High‐quality samples for physical, geochemical, and microbiological characterization of the subsurface are easily obtained with this new device.
Application of VLEACH to Vadose Zone Transport of VOCs at an Arizona Superfund Site
Authors: Rosenbloom J. , Mock P. , Lawson P. , Brown J. , Turin H.J.
Published: February 2007

Cleanup standards for volatile organic compounds in thick vadose zones can be based on indirect risk (transport to ground water) when contamination is below depths of significant direct risk. At one Arizona Superfund site, a one‐dimensional vadose zone transport model (VLE‐ACH) was used to estimate the continued transport of VOCs from the vadose zone to ground water. VLEACH is a relatively simple and readily available model that proved useful for estimating indirect risk from VOCs in the vadose zone at this site. The estimates of total soil concentrations used as initial conditions for VLF.ACH incorporated a variety of data from the site. Soil gas concentrations were found to be more useful than soil matrix data for estimating total soil concentrations at this arid‐zone site. A simple mixing cell model was used with the VLEACH‐derived mass loading estimates from the vadose zone over time to estimate the resulting changes in ground water concentrations. For this site, the results of the linked VLEACH/mixing cell simulations indicate it is likely that the federal MCI. for TCE will be exceeded in underlying ground water if remedial action on I he vadose zone is not pursued.
Effects of River Stage and Waste Water Discharges on the Unconfined Aquifer, Hanford, Washington
Authors: Gilmore T. J. , Borghese J. V. , Newcomer D. R.
Published: February 2007

This study examined the effects of river stage and waste water discharge on the unconfined aquifer near the N nuclear reactor on the U.S. Department of Energy‐operated Hanford site in Washington State. River levels were statistically correlated with water‐level data from 12 wells.

During the course of this study, water table elevations declined in the study area primarily as a result of a significant decrease in discharge to waste water disposal facilities, A minor contributing factor was the regional decline of the water table caused by decreasing waste water discharges upgradient of the study area.

High‐frequency river‐level fluctuations (e.g., short‐term daily fluctuations) had good correlation with water‐level variations in a well approximately 750 feet inland. Low‐frequency river‐level fluctuations (e.g., long‐term seasonal fluctuations) had good correlation with water‐level variations in a well approximately 1000 feet from the river shore. Time lags and attenuation generally increased with distance from the river as expected, with the exception of two northern wells. These two wells were relatively more responsive to river‐level fluctuations at a greater distance inland from the river. This suggests that hydraulic properties (e.g., hydraulic conductivity) are a control on the aquifer reponses.

During peak river stage in June, the river level rose above water table elevations in several wells implying a temporary reversal in ground water flow direction near the river.
Effects of Improper Characterization of Aquifer Thickness on Estimates of Hydraulic Conductivity from Pumping Tests
Authors: Hudak Paul F.
Published: February 2007

Pumping test data for surficial aquifers are commonly analyzed under the assumption that the base of the aquifer corresponds to the bottom of the test wells (i.e., the aquifer is truncated). This practice can lead to inaccurate hydraulic conductivity estimates, resulting from the use of low saturated thickness values with transmissivity estimates, and not accounting for the effects of partially penetrating wells. Theoretical time‐drawdown data were generated at an observation well in a hypothetical unconfined aquifer for various values of saturated thickness and were analyzed by standard curve‐matching techniques. The base of the aquifer was assumed to be the bottom of the pumping and observation wells. The overestimation of horizontal hydraulic conductivity was found to be directly proportional to the error in assumed saturated thickness, and to the (actual) ratio of vertical to horizontal hydraulic conductivity (Kv/Kh). Inaccurately high estimates of hydraulic conductivity obtained by aquifer truncation can lead to overestimates of ground water velocity and contaminant plume spreading, narrow capture zone configuration estimates, and overestimates of available ground water resources.
Landfill Performance Assessment at a Semiarid Site: Modeling and Validation
Authors: Stephens Daniel B. , Coons Larry M.
Published: February 2007

The HELP model (Version 2.05) was applied to simulate the long‐term percolation from a proposed landfill in southern New Mexico. The model predicted percolation would be about 0.0012 in/yr (10‐10 cm/s). This result compared very favorably with independent estimates of recharge at the site which used the chloride mass balance method and hydrogeologic properties. The recharge estimates at this site are also quite similar to values obtained at other sites in New Mexico and west Texas. The long‐term percolation through a closed landfill at this site is very small and would be nearly 1000‐fold smaller than the saturated hydraulic conductivity of a typical clay liner.
Fate of Chlorinated Aliphatic Hydrocarbons in the Vadose Zone and Ground Water
Authors: Barbee Gary C.
Published: February 2007

The large‐scale production and use of chlorinated aliphatic hydrocarbons (CHC) in the United Suites has resulted in numerous documented cases of soil and ground water contamination. Potential chronic exposure from contaminated soil and ground water, as well as from products used in the home, is sufficient reason to develop a thorough understanding of the environmental fate of these known and possible human carcinogens.

Most CHCs are very mobile in the subsurface environment, either as volatilized constituents in the vadose zone due to their high vapor pressure and low water solubility: as dissolved constituents in ground water since they are not strongly adsorbed by aquifer materials: and as dense nonaqueous phase liquids (DNAPLs) in ground water, primarily because they have low water solubility and densities greater than water. As free‐phase chemicals (i.e., DNAPLs). CHCs may pool on low‐permeability subsurface stratum and cause shrinkage and cracking of clay minerals, thereby significantly increasing the stratum's hydraulic conductivity and allowing rapid CHC breakthrough and migration. Although laboratory and field studies have demonstrated this effect, additional investigations are needed to determine the impact CHC DNAPLs have on low‐permeability in situ sediments.

CHCs are persistent environmental contaminants because they resist chemical and biological degradation. I'hc average half‐life for CHC abiotic transformations ranges from two months to greater than 1010 years. Chlorinated ethenes are the most resistant CHCs to abiotic degradation. Biodegradation half‐lives for CHCs may vary considerably but range from about two weeks to eight months or more. Anaerobic reductive dehalogenation is recognized as a primary CHC biodegradation process in ground water, although aerobic CHC hiodegradation may be a significant process in the shallow subsurface.

Technological applications of remedial processes fur stimulating in situ CHC biodegradation in soils and ground water need to be developed, particularly with regard to CHCs entrained as residual saturation.
Rapid Assessment of Trichloroethylene in Ground Water
Authors: Hewitt Alan D. , Shoop Sally A.
Published: February 2007

On‐site analysis of trichloroethylene (TCE) in aqueous samples by head‐ space sample preparation and gas chromatography (HS/GC) provides for quick and precise concentration estimates. This analytical approach is well suited for the on‐site determination of volatile organic compounds (VOCs) in a variety of sample matrices, including ground water and saturated and unsatured soils. For these reasons, HS/GC can be used to establish analyte concentrations on a near real time basis to help select appropriate casing material during monitoring well installation. This application and the collection of multiple well samples during sampling events facilitates the hydrogeological site interpretation and the formulation of remediation strategies.
An Assessment of the Nguyen and Finder Method for Slug Test Analysis
Authors: Butler James J. , Hyder Zafar
Published: February 2007

The Nguyen and Pinder method is one of four techniques commonly used for analysis of response data from slug tests. Limited field research has raised questions about the reliability of the parameter estimates obtained with this method. A theoretical evaluation of this technique reveals that errors were made in the derivation of the analytical solution upon which the technique is based. Simulation and field examples show that the errors result in parameter estimates that can differ from actual values by orders of magnitude. These findings indicate that the Nguyen and Pinder method should no longer be a tool in the repertoire of the field hydrogeologist. If data from a slug test performed in a partially penetrating well in a confined aquifer need to be analyzed, recent work has shown that the Hvorslev method is the best alternative among the commonly used techniques.
Generation of Hydrogen Gas as a Result of Drilling Within the Saturated Zone
Authors: Bjornstad Bruce N. , McKinley James P. , Stevens Todd O. , Rawson Shirley A. , Fredrickson James K. , Long Philip E.
Published: February 2007

Hydrogen gas was discovered within the steel casing above standing water in a percussion‐drilled borehole on the Hanlord Site in south‐central Washington state. In situ measurements of the borehole fluids indicated anoxic, low‐Eh (<‐400 mV) conditions. Ground water sampled from adjacent wells in the same formation indicated that the ground water was oxygenated. H2 was generated during percussion drilling, due to the decomposition of borehole waters as a result of aqueous reactions with drilled sediment and steel from the drilling tools or casing. The generation of H2 within percussion‐drilled boreholes that extend below the water table may be more common than previously realized. The ambient concentration of H2 produced during drilling was limited by microbial activity within the casing‐resident fluids. H2 was generated abiotically in the laboratory, whereby sterilized borehole slurry samples produced 100 times more H2 than unsterilizcd samples. It appears that H2 is metabolized by microorganisms and concentrations might be significantly greater if not for microbial metabolism.
Vertical Contaminant Profiling of Volatile Organic* in a Deep Fractured Basalt Aquifer
Authors: Kaminsky J.F. , Wylie A.H.
Published: February 2007

Volatile organic compounds delected in ground water from wells at Test Area North (TAN) at the Idaho National Engineering Laboratory (INEL) prompted RCRA facility investigations in 1989 and 1990 and a CERCLA‐driven RI/FS in 1992. In order to address ground water treatment feasibility, one of the main objectives, of the 1992 remedial investigation was to determine the vertical extent of ground water contamination, where the principle contaminant, of concern is trichloroethylene (TCE). It was hypothesized that a sedimentary interbed at depth in the fractured basalt aquifer could be inhibiting vertical migration of contaminants to lower aquifers. Due to the high cost of drilling and installation of ground water monitoring wells at this facility (greater than $100,000 per well), a real time method was proposed for obtaining and analyzing ground water samples during drilling to allow accurate placement of well screens in zones of predicted VOC contamination. This method utilized an inflatable pump packer pressure transducer system interfaced with a datalogger and PC at land surface. This arrangement allowed for real lime monitoring of hydraulic head above and below the packer to detect leakage around the packer during pumping and enabled collection of head data during pumping for estimating hydrologic properties. Analytical results were obtained in about an hour from an on‐site mobile laboratory equipped with a gas chromalograplvmass spectrometer (GC/MS). With the hydrologic and analytical results in hand, a decision was made to either complete the well or continue drilling to the next test zone. In almost every case, analytical results of ground water samples taken from the newly installed wells closely replicated the water quality of ground water samples obtained through the pump packer system.
Accuracy, Precision, and Stability of a Vibrating‐Wire Transducer Measurement System to Measure Hydraulic Head
Authors: Zarriello Phillip J.
Published: February 2007

A vibrating‐wire transducer measurement system was investigated to determine its accuracy, precision, and stability for use in a study of ground water movement in low‐permeability material. Twenty transducers with a pressure range of 10 psi were tested for stability over 100 days. half under low pressure (0.256 psi) and half under approximately full‐scale pressure (10 psi). Measurement precision and stability were far better than measurement accuracy. Random noise in the data indicates that the transducers were precise to within 0.02 psi. The transducer measurements were generally stable to within 0.05 psi. but most showed a blight decrease in pressure over time. Measurements by transducers under low pressure were within 0.038 psi of actual pressure, and those made by transducers under high pressure were within −0.20 psi. as indicated by the difference between the mean measurement of each transducer and the mean measurement of all transducers. These measurements were within the reported accuracy for transducers under low pressure, but differed by more than the reported accuracy for transducers under high pressure: this indicates that transducer accuracy is largely determined by the pressure coefficient used to convert transducer readings to pressure units. Pressure coefficient calibration of selected transducers by a water filled standpipe and a digital manometer indicate that hysteresis could be the most significant factor affecting the transducer accuracy Standpipe calibrations indicate a pressure coefficient difference of about 13 percent between increasing and decreasing pressure, but deadweight calibrations indicate a difference of only 1.5 percent. The observed measurement and equipment error could affect interpretation of water level measurements; thus, independent water level measurements and rigorous review of the data arc needed to evaluate the accuracy of transducer measurements.
A Systematic Approach to Designing a Multiphase Unsaturated Zone Monitoring Network
Authors: Cullen Stephen J. , Kramer John H. , Luellen Jon R.
Published: February 2007

A systematic approach is presented for the design of a multiphase vadose zone monitoring system recognizing that, as in ground water monitoring system design, complete subsurface coverage is not practical. The approach includes identification and prioritization of vulnerable areas: select ion of cost‐effective indirect monitoring methods that will provide early warning of contaminant migration: selection of direct monitoring methods for diagnostic confirmation; identification of background monitoring locations; and identification of an appropriate temporal monitoring plan. An example of a monitoring system designed for a solid waste landfill is presented and utilized to illustrate the approach and provide details of system implementation. The example design described incorporates the use of neutron moisture probes deployed in both vertical and horizontal access tubes beneath the lcachate recovery collection system of the landfill. Early warning of gaseous phase contaminant migration is monitored utilizing whole‐air active soil gas sampling points deployed in gravel‐ filled trenches beneath the subgrade. Diagnostic confirmation of contaminant migration is provided utilizing pore‐ liquid samplers. Conservative tracers can be used to distinguish between chemical species released by a landfill from those attributable to other (e.g. off‐site) sources or present naturally in the subsurface. A discussion of background monitoring point location is also presented.
Experimental and Numerical Study of the Transport of Acid Solutions and Copper in Tailings Impoundments
Authors: Munoz Jose Francisco , Rengifo Pablo
Published: February 2007

A two‐dimensional mathematical model for acid leaching of copper from mine tailings using injection and pumping wells is presented. The model considers the transport mechanisms of convection and dispersion with reactions that govern the fates of copper and acid. Reactions considered are acid neutralization, copper solubilization, and copper adsorption. The results of acid leaching experiments in laboratory columns (one‐ dimensional) and in the field at a tailings impoundment are presented. The proposed model was validated for a one‐dimensional experiment, and the model parameter fitting was found to be adequate in terms of the field experiment.
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

Two 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

A 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

Eloctromigraiion 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

The 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

As 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

A 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

A 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

A 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

Five 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

A 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

Cosolvent 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

Contaminants 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

Recirculating 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.
DNAPL — Stop the Madness
Authors: Nyer Evan K.
Published: February 2007

“The EPA decided that showing the presence of DNAPL would prove that cleanup to non‐detect was improbable, and that a new end point could be selected.”

“The only thing that really matters is the total mass of from the natural attenuation.”
Field Demonstration of Permeable Wall Flushing for Biostimulation of a Shallow Sandy Aquifer
Authors: Devlin J. F. , Barker J. E
Published: February 2007

A 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

Monitoring 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.
Laboratory Study of Air Sparging of TCE‐Contaminated Saturated Soils and Ground Water
Authors: Adams Jeffrey A. , Reddy Krishna R.
Published: February 2007

Air sparging has proven to be an effective remediation technique for treating saturated soils and ground water contaminated by volatile organic compounds (VOCs). Since little is known about the system variables and mass transfer mechanisms important to air sparging, several researchers have recently performed laboratory investigations to study such issues. This paper presents the results of column experiments performed to investigate the behavior of dense nonaqueous phase liquids (DNAPFs). specifically trichloroethylene (TCE), during air sparging. The specific objectives of the study were (1) to compare the removal of dissolved TCE with the removal of dissolved light nonaqueous phase liquids (LNAPLs). such as benzene or toluene; (2) to determine the effect of injected air‐flow rate on dissolved TCE removal; (3) to determine the effect of initial dissolved TCE concentration on removal efficiency; and (4) to determine the differences in removal between dissolved and pure‐phase TCE. The test results showed that (1) the removal of dissolved TCE was similar to that of dissolved LNAPL: (2) increased air‐injection rates led to increased TCE removal at lower ranges of air injection, but further increases at higher ranges of air injection did not increase the rate of removal, indicating a threshold removal rate had been reached; (3) increased initial concentration of dissolved TCE resulted in similar rates of removal: and (4) the removal of pure‐phase TCE was difficult using a low air‐injection rate, but higher air‐injection rates led to easier removal.
Installing Multilevel Sampling Arrays to Monitor Ground Water and Contaminant Discharge to a Surface Water Body
Authors: Dean Sean M. , Lendvay John M. , Barcelona Michael J. , Adriaens Peter , Katopodes Nikolaos D.
Published: February 2007

A simple, effective method for the installation and sampling of vertically discrete points in a dynamic beach environment was developed and tested on the eastern shore of Lake Michigan, The installation permitted the vertical resolution of a ground water plume discharging to the lake and allowed monitoring of temporal variations during relatively calm and stormy periods of the year. These installations permit the definition of vertical heterogeneities such as oxidation‐reduction conditions and geochemical characteristics that are expected to impact the transport and fate of ground water contaminants discharged to the surface water.
Ellog Auger Drilling: Three‐in‐One Method for Hydrogeological Data Collection
Authors: Sørensen Kurt , Larsen Flemming
Published: February 2007

The Ellog auger drilling method is an integrated approach for hydrogeological data collection during auger drilling in unconsolidated sediments. The drill stem is a continuous flight, hollow‐stem auger with integrated electrical and gamma logging tools. The geophysical logging is performed continuously while drilling. Data processing is carried out in the field, and recorded log features are displayed as drilling advances. A slotted section in the stem, above the cutting head, allows anaerobic water and soil‐gas samples to be taken at depth intervals of approximately 0.2 m. The logging, water, and gas sampling instrumentation in the drill stem is removable; therefore, when the drill stem is pulled back, piezometers can be installed through the hollow stem. Cores of sediments can subsequently be taken continuously using a technique in which the drill bit can be reinserted after each coring. The Ellog auger drilling method provides detailed information on small‐scale changes in lithology, sediment chemistry, and water, as well as gas compositions in aquifer systems–data essential to hydrogeological studies.
In‐Well Hydraulics of the Electromagnetic Borehole Flowmeter: Further Studies
Authors: Arnold Katrin B. , Molz Fred J.
Published: February 2007

The electromagnetic borehole flowmeter (EBF) is finding increasing application as a method for measuring hydraulic conductivity (K) distributions. A recent paper details an experimental/theoretical study of the effect of in‐well hydraulics on calculated K distributions based on EBF measurements (Dinwiddie et al. 1999). Results showed that minimizing head loss associated with flow through the meter was the key to producing accurate K values. Using the same experimental procedures, the previous study has been extended to develop data from a larger diameter (1 inch) EBF, and to determine if an EBF can be calibrated effectively without using an inflatable packer to force all flow through the meter annulus. Both experiments were aimed at producing low head loss conditions. Results show that overall calibration can be accomplished in the absence of a packer, which reduces head losses to nonmeasurable levels, and use of the 1‐inch EBF with a packer reduces head losses by a factor of 16 when compared with the 0.5‐inch EBF studied by Dinwiddie et al. (1999).