bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Management Practice Effects on Pesticide Movement to Ground Water
Authors: Shoemaker L. L. , Magette W. L. , Shirmohammadi A. 
Published: February 2007

AbstractThe assessment of agricultural impacts on water quality are now being redirected to include both ground water and surface water. Mathematical models have enhanced the ability of scientists’to evaluate these impacts. A variety of public domain models are available that can aid in evaluating the effects of managerial activities on pesticide movement to ground water. However, the ideal non‐point source (NPS) pollution management model does not exist. Current models fail to adequately describe the transport of chemicals to ground water and, simultaneously, the effect of managerial practices on transport mechanisms. Much more work is necessary to develop a model that can describe water quality impacts of agricultural practices in a holistic framework that includes ground water and surface water concerns.
The Detection of Naturally Occurring BTX During a Hydrogeologic Investigation
Authors: Slaine David D. , Barker James F. 
Published: February 2007

AbstractBenzene, toluene and xylenes (BTX) were detected in ground water during a contaminant hydrogeological investigation of a landfill site. The landfill site was situated on approximately 10m (33 ft) of clay and glacial till overburden soils, which were underlain by a shaly limestone bedrock. The top part of the bedrock was the regional aquifer in the study area. Initial thoughts were that the landfill was the source of the BTX. However, the BTX was detected in ground water a considerable distance from the known extent of the leachate plume. Subsequent detailed analysis of rock cores showed the BTX could be leached from bituminous layers of shale that were interbedded in limestone. Rock core testing included gas chromatograph (GC) analysis of organic free reagent water used for leaching tests, flame ionization detection on a solvent used for leaching tests and thermal desorption analysis of the solid rock. The naturally occurring BTX, along with the presence of brackish ground water in the shaly bedrock, made it difficult to identify ground water contamination emanating from the landfill. Thus, the presence of BTX should not be considered definitive evidence of ground water contamination in certain sedimentary rock aquifers.
A Method to Evaluate the Vertical Distribution of VOCs in Ground Water in a Single Borehole
Authors: Hoffman Fredric , Dresen Michael D. 
Published: February 2007

AbstractVolatile organic compounds (VOCs) are present in multiple water‐bearing zones beneath and downgradient of Lawrence Livermore National Laboratory. This area is composed of interfingering unconsolidated alluvial sediments with hydraulic conductivities ranging over four orders of magnitude. The more permeable sediments exhibit moderate hydraulic interconnection horizontally and less interconnection vertically, and appear to consist largely of interconnected stream channel deposits. To optimize selection of monitoring well screened intervals in this complex environment, a technique that enables collection of saturated formation samples from each water‐bearing zone without contamination from other VOC‐containing zones was developed, tested, and implemented. The technique utilizes a wireline punch‐coring system that allows the drill bit to be replaced with a core barrel without removing the drill rod from the borehole. To help ensure that a sample from one water‐bearing zone is not contaminated by VOCs from another zone, the drilling fluid is replaced with new fluid before each sampling run. Overnight chemical analysis by gas chromatography enables field personnel to know the vertical distribution of VOCs as drilling proceeds. Since its first use in 1985, the technique has successfully characterized the presence or absence of VOCs in ground water in 123 of 140 wells, many with concentrations in ground water in the low parts‐per‐billion range. Our sampling technique is a cost‐effective and rapid method of evaluating the vertical distribution of VOCs in ground water in a complex hydrogeologic environment.
Differentiation of the Origins of BTX in Ground Water Using Multivariate Plots
Authors: Lesage S. , Lapcevic P. A. 
Published: February 2007

AbstractMultivariate plots were utilized to create fingerprints of aromatic hydrocarbon residues in ground water. The technique allows hydrogeologists to distinguish between residues of benzene, toluene, ethyl benzene, and total xylenes originating from ground water contact with petroleum in natural deposits and refined petroleum waste products. Examples were taken from deep‐well injection of refinery wastes, natural petroleum deposits, municipal and industrial landfill leachates, coal tar and creosote contaminated waters, and varnish industry contaminated ground water. The data were plotted from ASCII files generated through either Lotus 123™ or a database (The Manager™) report program, using a simple Fortran interactive program with Plot88™ subroutines.
Evaluating the Effectiveness of Ground Water Extraction Systems
Authors: Haley Jennifer L. , Hanson Bill , Enfield Carl , Glass John 
Published: February 2007

AbstractThe most common process for remediating contaminated ground water is extraction and treatment. Data from 19 on‐going and completed ground water extraction systems were collected and analyzed (U.S. EPA 1989b) to evaluate the effectiveness of this process in achieving cleanup concentration goals for ground water. This analysis indicated several trends including (1) containment of ground water plumes was usually achieved; (2) contaminant concentrations dropped significantly initially followed by a leveling out; (3) after the period of initial rapid decline, the continued decreases in concentration were usually slower than anticipated; and (4) certain data important to optimizing system design and operation had often not been collected during the site characterization phase.Factors limiting the achievement of cleanup concentration goals fell into four basic categories: (1) hydrogeological factors, such as subsurface heterogeneity, low‐permeability units, and presence of fractures; (2) contaminant‐related factors, such as high sorption to soil and presence of non‐aqueous phases (dissolution from a separate non‐aqueous phase or partitioning of contaminants from the residual non‐aqueous phase); (3) continued migration from source areas and the size of the plume itself; and (4) system design factors, such as pumping rates, screened intervals, and extraction well locations.The findings of this study indicate that ground water extraction is an effective method for preventing additional migration of contaminant plumes and achieving risk reduction. However, the findings indicate that in many situations, it may not be practicable to rely solely on ground water extraction and treatment to achieve health‐based cleanup concentrations throughout the contaminated zone and fulfill the primary goal of returning ground water to beneficial use.This study suggests several recommendations (U.S. EPA 1989a) for improving ground water response actions including (1) actions to contain contaminant plumes should be initiated early; (2) data on vertical variation of hydraulic conductivity, distribution of the contaminant mass, and partitioning of contaminants to soil or a stationary phase in the saturated zone should generally be collected as part of the site characterization process; (3) remedial actions should be implemented in stages to better utilize information on aquifer response as the system is being designed and implemented; (4) remedial actions should be monitored and modified during operation to optimize system efficiency; and (5) methods to enhance extraction effectiveness and efficiency should be considered.
Impact of Recharge Through Residual Oil Upon Sampling of Underlying Ground Water
Authors: Wise William R. , Chang Chi‐Chung , Klopp Rick A. , Bedient Philip B. 
Published: February 2007

AbstractAt an aviation gasoline spill site in Traverse City, Michigan, historical records indicate a positive correlation between significant rainfall events and increased concentrations of slightly soluble organic compounds in the monitoring wells of the site. To investigate the recharge effect on ground water quality due to infiltrating, water percolating past residual oil and into the saturated zone, an in situ infiltration experiment was performed at the site. Sampling cones were set at various depths below a circular test area, 13 feet (4 meters) in diameter. Rainfall was simulated by sprinkling the test area at a rate sufficiently low to prevent runoff. The sampling cones for soil‐gas and ground water quality were installed in the unsaturated and saturated zones to observe the effects of the recharge process. At the time of the test, the water table was below the residual oil layer. The responses of the soil‐gas and ground water quality were monitored during the recharge and drainage periods, which resulted from the sprinkling.Infiltrated water was determined to have transported organic constituents of the residual oil, specifically benzene, toluene, ethylbenzene, and ortho‐xylene (BTEX), into the ground water beneath the water table, elevating the aqueous concentrations of these constituents in the saturated zone. Soil‐gas concentrations of the organic compounds in the unsaturated zone increased with depth and time after the commencement of infiltration. Reaeration of the unconfined aquifer via the infiltrated water was observed. It is concluded that water quality measurements are directly coupled to recharge events for the sandy type of aquifer with an overlying oil phase, which was studied in this work. Ground water sampling strategies and data analysis need to reflect the effect of recharge from precipitation on shallow, unconfined aquifers where an oil phase may be present.
Computer Modeling of Scale Formation During Treatment of Ground Water in Air Strippers
Authors: Matisoff Gerald , Narquis Clifford 
Published: February 2007

AbstractDuring treatment to remove volatile organic compounds from contaminated ground water, inorganic scale sometimes precipitates in an air stripper tower. This leads to increased costs and down‐time associated with tower media replacement. In order to determine the kind, quantity, and rate of scale formation, the ground water from five locations in Florida was simulated using an aqueous equilibrium chemistry and flow process model. In all cases the pH of the outflow water is higher than that of the inflow water because of degassing of CO2. This often results in the precipitation of calcium carbonate. The addition of air to reduced ground water results in the oxidation of iron and the precipitation of ferric hydroxides. Model estimates of scale formation are about a factor of two to five too high. This indicates that the precipitation reactions do not reach equilibrium within the air stripper. Future work will require the inclusion of biological fouling and a kinetic expression to account for the observed non‐equilibrium.
The Utility of Multiple‐Completion Monitoring Wells for Describing a Solvent Plume
Authors: Korte N.E. , Kearl P.M. 
Published: February 2007

AbstractAt a study site in the midwestern United States, multiple‐completion wells demonstrated that a vertical hydraulic gradient was responsible for the contamination pattern exhibited by chlorinated solvent plumes. The typical pattern consisted of little or no contamination in the upper portion of the aquifer with concentrations increasing with depth. When ground water contamination was discovered in an unexpected portion of the site, water level elevations and contaminant distribution data obtained from multiple‐completion wells resulted in identification of the source location. The well eventually determined to be located in the source area displayed contaminant levels much higher in the upper zone of the aquifer — the opposite contamination pattern of other on‐site wells. Such results indicated that the spill had occurred near this location and that solvent residing along the capillary fringe was continuing to contaminate the aquifer.
The Disposable E‐Log
Authors: Greenhouse John P. , Pehme Peeter E. 
Published: February 2007

AbstractA device was developed to make fine‐scale in situ measurements of formation and ground water conductivity at depths up to 10 meters in unconsolidated shallow aquifers. It consists of a casing that is left in place (“disposable”) and a probe that slides down the center of the casing making readings or taking water samples through screened slots. The device is inexpensive, designed to be jetted into place, and intended for use in monitoring situations where drilling rigs and wireline logs are impractical. It offers, in principle, 10cm resolution of the conductivities and the formation factor as a function of time.Results from three of these units installed across a landfill plume near North Bay, Ontario, demonstrate the usefulness of these kinds of measurements in a monitoring study, and the problems that can be encountered in a highly contaminated environment.
Atrazine Used as a Tracer of Induced Recharge
Authors: Duncan Diana , Pederson Darryll T. , Shepherd Timothy R. , Can James D. 
Published: February 2007

AbstractThe city of Lincoln draws water from a well field along the banks of the Platte River in east‐central Nebraska. We have been able to follow the infusion of atrazine into this well field under induced recharge. Samples of water from the river, several monitoring wells and a production well were analyzed by GC/MS and solid phase extraction and found to change in concentration over the range 0.1 and 5.0 ppb of atrazine through the spring, summer, and fall 1989. Increases in the concentration of atrazine relating to precipitation events in the Platte River Basin were observable in the well water samples and ultimately in Lincoln municipal tap water. Atrazine from the river was seen to move via induced recharge and into well field ground water and away from the river at an observable rate. The concentration of atrazine in the river is dependent upon time of year and precipitation in the river basin.
Cascade Air Stripping: Techno‐Economic Evaluation of a New Ground Water Treatment Process
Authors: Nirmalakhandan N. , Peace G.L. , Shanbhag A.R. , Speece R.E. 
Published: February 2007

AbstractA simple modification of the conventional air‐stripping process introduced as cascade air stripping is proposed for efficient and economical removal of semivolatile and low volatility contaminants from ground water. The technical feasibility and economic viability of this process are evaluated using field test results and cost model simulations. The field tests enabled the process model to be verified at various water flow rates ranging from 150 gpm to 400 gpm. The field study also demonstrated the feasibility of the proposed system at a near full‐scale level. Cost models were used to compare the proposed process to conventional air stripping and granular‐activated carbon adsorption in removing a range of contaminants. This analysis showed that the treatment cost (ø/1000 gal) of cascade air stripping is about 15 percent lower than conventional air stripping and about 40 percent lower than granular‐activated carbon adsorption.
Potential of Common Well Casing Materials to Influence Aqueous Metal Concentrations
Authors: Hewitt Alan D. 
Published: February 2007

AbstractStatic leaching and sorption laboratory studies were performed to assess the potential of polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and two types of stainless steel (SS 304 and SS 316) well casing materials to influence metal concentrations in ground water solutions with low dissolved oxygen. Overall, PTFE was inert, whereas one or both stainless steels significantly altered the solution concentrations of Cd, Cr, Cu, Pb, Fe, and Ni. PVC was generally more reactive than PTFE, but did not significantly alter the solution metal concentrations as often, or as greatly, as either of the stainless casings.
Reversed Flow Test: A Borehole Logging Method for Estimating Pore Water Quality and Inflow Rates Along an Uncased Borehole Profile
Authors: Tellam J.H. 
Published: February 2007

AbstractThere is often a need to estimate the variation in water quality and flow rate with depth in an aquifer given access only to an uncased borehole. In such situations, borehole logging techniques can be applied. This paper describes the Reversed Flow Test (RFT), a rarely used borehole logging method. The RFT is intended to provide information on pore water quality and inflow rates along the length of an uncased borehole profile. They are carried out by logging the conductivity of the borehole fluid under two pumping phases. During the first pumping phase the pump intake is located at the top of the borehole, and during the second the intake is located at the base. Provided the pumping rates are low and the system does not have marked lateral heterogeneity, stable conductivity profiles are often achieved within a relatively short time period. The data are interpreted to give estimates of electrical conductivity and inflow at each point in the profile. The test has been successfully carried out on a range of British aquifers, and four case histories are summarized here. In each case, the test was easily accomplished by two people in less than a day.
Progressive Packer/Zone Sampling Method for VOC Plume Delineation in Consolidated Aquifers
Authors: Laney Stephen E. , Enberg Charles A. 
Published: February 2007

AbstractThe progressive packer/zone sampling method was used to identify the bottom of a plume of volatile organic compounds (VOCs) in the parts‐per‐million (ppm) range using one well in each of three separate locations. The method involves progressively drilling a 20‐foot length of borehole through casing, setting an inflatable packer at the top of the drilled zone, purging the zone of three volumes of water using the airlift method, sampling the zone in situ through the packer string using a bailer, then repeating the procedure.A plume consisting of chlorinated VOCs, alcohols, and vinyl chloride occurs in a low‐yielding fractured bedrock aquifer located in the Passaic Formation at a site in central New Jersey. The thickness of the plume in total VOC concentrations exceeding 1 ppm was determined using the progressive packer/zone sampling method to a depth of 200 feet. The first borehole was completed as a monitoring well in the “hottest” zone encountered during testing. Additional wells were then clustered with this exploratory well to delineate the plume in the parts‐per‐billion (ppb) range. Cross contamination from previously sampled zones was not a problem as long as total VOCs in the ppm range were targeted and the sample interval was properly purged.Instead of using a multiple well cluster consisting of an indefinite number of wells to determine the bulk thickness of a plume at a specific location, information from one borehole may suffice during the exploratory phase. Costs to the client and cross contamination potential to the aquifer can be minimized by limiting the number of boreholes needed for vertical delineation.
Acquisition of Representative Ground Water Quality Samples for Metals
Authors: Puls Robert W. , Powell Robert M. 
Published: February 2007

AbstractR.S. Kerr Environmental Research Laboratory (RSKERL) personnel have evaluated sampling procedures for the collection of representative, accurate, and reproducible ground water quality samples for metals for the past four years. Intensive sampling research at three different field sites has shown that the method by which samples are collected has a greater impact on sample quality, accuracy, and reproducibility than whether the samples are filtered or not. In particular, sample collection practices that induce artificially high levels of turbidity have been shown to have the greatest negative impacts on sample quality. Results indicated the ineffectiveness of bailers for collection of representative metal samples. Inconsistent operator usage together with excessive purging generally resulted in excessive turbidity (>100 NTUs) and large differences in filtered and unfiltered metal samples. The use of low flow rate purging and sampling consistently produced filtered and unfiltered samples that showed no significant differences in concentrations. Turbidity levels were generally less than 5 NTUs, even in fine‐textured glacial till. We recommend the use of low flow rates, during both purging and sampling, placement of the sampling intake at the desired sampling point, minimal disturbance of the stagnant water column above the screened interval, monitoring of water quality indicators during purging, minimization of atmospheric contact with samples, and collection of unfiltered samples for metal analyses to estimate total contaminant loading in the system. While additional time is spent due to use of low flow rates, this is compensated for by eliminating the need for filtration, decreased volume of contaminated purge water, and less resampling to address inconsistent data results.
Hydrogeological Investigation of Hydrocarbon Contamination of Ground Water in Albolote (Granada, Spain)
Authors: Cruz‐Sanjulián J. , Olías M. , del Valle M. , Rubio J.C. 
Published: February 2007

AbstractIn July 1988, hydrocarbons were detected in wells in the urban area of Albolote, near Granada, Spain, near the border of the “Vega de Granada” alluvial aquifer. According to available hydrogeological data, the contamination was attributed to leaks in the underground pipelines of a nearby (300m) industrial factory, where the loss of 40,000 to 50,000 liters of gasoline had been detected some weeks before. A complete hydrogeological investigation was then undertaken, involving, among other techniques: (a) an inventory of the existing wells in the area; (b) the preparation of piezometric maps; (c) the application of electrical geophysical methods; (d) the drilling of piezometers and new pumping wells between the urbanized area and the leak point; (e) the improvement of the pluviometric and piezometric control by the installation of a pluviograph and several limnigraphs; (f) the sampling, initially daily and finally weekly, in a 20‐well observation network, also used for piezometric control; and (g) the geostatistical study of the analytical data. The contamination plume, extended in the direction of the flow lines, has a length of 500m and a width of less than 50m, and appears to have occurred mainly in a paleochannel. Hydrocarbons (1600 liters) were recovered by pumping and by using absorbent blankets, as well as by a gas and liquid suction method. Hydrocarbon concentrations have continuously decreased. However, sporadic increases, associated with rainfall, have been observed suggesting the presence of retained hydrocarbons in the unsaturated zone. The rate of decrease in hydrocarbon concentrations has currently slowed, particularly in the less affected zone. As a means of activating the cleaning up of the unsaturated zone, an artificial recharging method has been designed.