bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Electrical Resistivity Methods for Investigation of Ground Water Conditions at a Landfill Site
Authors: Sweeney Jerry J. 
Published: February 2007

AbstractTwo electrical methods were used and compared in the Investigation of a solid waste landfill site in the central Coast Ranges of California Terrain conductivity measurements and dipole‐dipole resistivity surveys were used in support of an investigation of the hydrology and geochemistry of the site with main concerns being: 1) establishment of baseline conditions, 2) determination of possible contamination and 3) design of a sampling/ monitoring system. Geophysical data were obtained prior to the start of the drilling program and later integrated with reconnaissance geologic data for the purpose of selecting sites for monitoring wells. Two electrical methods were used: 1) dipole‐dipole resistivity; best suited for determining changes in electrical properties with depth and 2) terrain conductivity; best suited for determining lateral changes in electrical properties at a particular depth. Interpretations of the surveys were used in making inferences about the geometry of the saturated zone, ground water gradients, and relative depths to the saturated zone in areas with highly variable conditions. The data were useful in checking for possible ground water contamination and for extrapolating well data across the site.Electrical properties of rock at low frequencies are dominated by effects due to the presence of pore fluids. Differences in conductivity between saturated and unsaturated rock depend primarily on inherent electrical properties of the rock, porosity and conductivity of the fluid. Electrical detection of subsurface zones of contamination, sometimes referred to as “plumes”, in either the saturated or unsaturated zones, requires the existence of a zone of contrasting electrical behavior produced by the contamination. Such contrasts, or anomalies, can be caused by the presence of increased (higher conductivity) or decreased (lower conductivity) concentration of ions. In areas where materials with contrasting electrical properties (such as sandstone and claystone) are present in the subsurface with irregular geometry, anomalies can be difficult to interpret and additional information about geology and ground water conditions must be relied upon.The geophysical survey for this study began with dipole‐dipole resistivity measurements carried out along orthogonal lines in the landfill area. Subsequently, terrain conductivity measurements were carried out and compared with this data. A brief explanation and comparison of the methods used and the results of the surveys are discussed. Following completion of the surveys, the dipole‐dipole data were modeled with the use of a finite‐element computer algorithm. The models are compared with geological and hydrological data obtained during the drilling phase of the program.
Transport of Organic Compounds Dissolved in Ground Water
Authors: Newsom Joan M. 
Published: February 2007

AbstractOrganic compounds, such as trichlomethylene (TCE) and chlorobenzene, that have been found in drinking water supplies are of public concern because they are possibly carcinogenic. These substances can now be routinely detected in trace amounts with gas chromatograph mass spectrometers. There are some polar organic compounds, which are not detectable individually by common methods and therefore little is known about them.The transport of organic compounds is more difficult to predict than the flow of ground water because:Trace amounts of pollutants are difficult to measureTransport is complicated if the compound is partitioned into several phasesThe concentration of organics in ground water may vary due to aquifer heterogeneity and other hydrologic factorsReactions with other organic compounds and reactions with the aquifer material (such as adsorption) may affect the mobility of the organicsBiodegradation may also affect net transport.Adsorption is a factor in the attenuation of non‐polar organics in aquifers with significant organic content (>0.1 percent organic carbon). The organic material adsorbs the non‐polar organic chemicals. The mobility of a pollutant in such an aquifer depends on at least two parameters: the levels of dissolved organic matter and the content of organic carbon in the aquifer material. The partition coefficient of the chemical pollutant between the aquifer and water is commonly calculated as a function of the organic content of the aquifer and the partition coefficient between octanol and water.Field and laboratory results reported in the literature indicate that the following organic compounds may be biodegradable under aerobic conditions: alkyl benzenes and chlorobenzenes. Under anaerobic conditions halogenated aliphatics, alkyl benzenes, several pesticides and phenolic compounds may be biodegradable. Halogenated aliphatics appear not to degrade under aerobic conditions and non‐chlorinated aro‐matics and chlorobenzenes appear not to degrade under anaerobic conditions. Alkyl benzenes biode‐grade more rapidly than their halogenated counterparts.
Subsurface Disposal of Liquid Low‐Level Radioactive Wastes at Oak Ridge, Tennessee
Authors: Stow Stephen H. , Haase C. Stephen 
Published: February 2007

AbstractLiquid low‐level radioactive wastes have been disposed of by subsurface injection at Oak Ridge, Tennessee, for the last two decades. The process entails mixing the wastes with cement and other additives, then pumping the slurry under pressure into a highly impermeable shale; the pressure is sufficient to create bedding plane fractures in which the grout, containing the wastes, sets. Research is being conducted to develop an understanding of the hydrology of the site and monitoring methods. The present regulatory climate regarding injection wells has created an uncertain future for this technique.
The Effect of Sampling Frequency on Ground Water Quality Characterization
Authors: Rajagopal R. 
Published: February 2007

AbstractThere is an implicit relationship between the frequency of sampling and the value of information obtained. This relationship is briefly explored by a study of nitrates in aquifers of the Quaternary age and fluorides and sulfates in aquifers of the Cambro‐Ordovician age in Iowa. The ambient distribution of these chemicals, in general, is positively skewed with a significant number of observations in the lower end of the feasible range. It is shown that a much broader perspective of the distribution of these chemicals in ground water can be obtained by studying a whole spectrum of parameters (quantiles) ranging from the minimum to the maximum, rather than just the mean or the median alone. Simple random samples of varying sizes drawn from the available data base revealed that many parameters of location, such as the quantiles, of nitrates, fluorides, and sulfates in selected aquifers can be estimated closely by samples of sizes 50, 100 and 250. Results based on such hindsight warrant further investigation of the behavior of sampling distributions of a set of high priority chemicals in different hydrogeological environments.
Interpretation of VLF Resistivity Data for Ground Water Contamination Surveys
Authors: Stewart Mark , Bretnall Robert 
Published: February 2007

AbstractVery low frequency (VLF) military communications systems provide a primary field that can be used for shallow geophysical surveys to locate ground water contamination and vertical geologic contacts. Useful properties that can be easily obtained from the interaction of the earth and the primary field are the magnitude of the vertical secondary magnetic field, the surface impedence, and the phase angle between the electrical and magnetic horizontal components. The variations in the secondary magnetic field can be related to vertical geologic contacts, such as the edges of landfill trenches. The surface impedence yields an apparent terrain conductivity, which can be used to locate low‐resistivity anomalies often associated with contaminated ground water. The phase angle gives information on vertical variations in resistivity, phase angles less than 45° indicating increasing resistivity with depth. The depth of penetration of the VLF field is about one skin depth. For a frequency of 20 kHz, the skin depth in meters is approximately equal to 3.67 where p is terrain resistivity in ohmmeters.
A Computer Data Base for Overview of Ground Water Pollution Investigations
Authors: Hoffman Jeffrey L. 
Published: February 2007

AbstractA vast amount of managerial information is needed to efficiently conduct and monitor concurrent investigations of ground water pollution sites. The New Jersey Geological Survey has developed a computer data base to summarize these data and provide a template for their systematic collection. A series of computer programs access the data base and produce a variety of reports. These reports greatly simplify the review of ground water pollution case loads, geographical distribution and allocation of resources. The accuracy and usefulness of the reports are directly related to the timeliness of the information in the data base. Descriptions of the input data and the output reports show the utility of this method for information storage and retrieval. These programs could easily be adapted to other situations requiring similar types of data. Copies of the programs are available from the author.
Multiple Completion Monitor Wells
Authors: Nakamoto Dennis B. , McLaren Frederick R. , Phillips Peter J. 
Published: February 2007

AbstractThis paper discusses the multiple completion monitor well design concept in terms of drilling methods, construction methods, cost considerations, and potentially adverse effects caused by interactions between construction materials and ground water. The report is based on McLaren Environmental Engineering's experiences in constructing monitor wells containing up to seven piezometers within a single 10‐inch diameter borehole.The air rotary casing hammer method is used to penetrate unconsolidated sediments and the remainder of the hole is drilled by the direct mud rotary method. Intervals for piezometer completions are based upon lithologic descriptions and downhole electrical logging.Piezometers are 2½‐inch and 1‐inch blank pipe with 2½‐inch mill slotted and 1½‐ihch wire wound perforated pipe. Each perforated pipe interval is within a gravel envelope. Cement grout (4½ gallons water to 94 pounds cement) is used to seal the annular space between perforated intervals.Contracting costs for multiple completion monitor wells are less than for an equal set of single completion monitor wells. For example, a six completion monitor well, 300 feet deep, costs $15,300. Six single completion monitor wells with the same perforated intervals cost $46,800. The cost differences are mainly for drilling extra footage and installing more grout.McLaren Environmental Engineering uses multiple completion monitor wells to investigate ground water conditions in stratified alluvium. We have demonstrated the effectiveness of cement grout hydraulic seals by measuring differences in hydraulic heads
An Effective and Inexpensive Gas‐Drive Ground Water Sampler
Authors: Norman William R. 
Published: February 2007

AbstractGround water scientists engaged in assessment of contaminant occurrence and migration are faced with a number of practical problems. These problems include, but are not limited to, escalating drilling costs, labor costs for proper sampling of monitoring wells, collection of ground water samples that are representative of aquifer conditions and accurate delineation of hydrogeologic regimes and the areal and vertical distribution of ground water contaminants.In response to these problems, a number of ground water sampling devices have been developed. One device is a gas‐driven ground water sampler developed for multilevel installation. Use of these samplers have been shown to decrease project costs and allow easy collection of high quality samples. However, the currently available samplers are relatively expensive, some of them operate on a closed check valve system, which does not allow determination of piezometric heads in aquifers with fluctuating water tables and they are not adaptable to design changes in the field necessitated by site‐specific hydrogeologic conditions.GHR Engineering Associates Inc. has designed an effective gas‐driven sampler, which accomplishes the same objectives as the commercially available models, but is on the average, one‐tenth the cost of currently available samplers. It offers the advantages of being more cost‐effective than commercially available models, has an open check valve system to allow measurements of water table fluctuation and is easily adaptable in the field to meet site‐specific hydrogeologic conditions.
Sampling for Toxic Contaminants in Ground Water
Authors: Bryden Gregg W. , Mabey William R. , Robine Keith M. 
Published: February 2007

AbstractIn this paper, we relate recent developments in ground water sampling techniques to the practical application of sampling for toxic contaminants in ground water. We address the choices that must be made in choosing equipment for a particular project by going through a step‐by‐step procedure for collecting a ground water sample from a typical monitoring well. Ground water sampling topics that are discussed include: choice of equipment for purging and sampling a well, monitoring for purged ground water indicators and quality assurance/quality control.
Use of a Geo Flowmeter for the Determination of Ground Water Flow Direction
Authors: Guthrie Marilyn 
Published: February 2007

AbstractThe Geo Flowmeter is manufactured by K.V. Associates of Falmouth, Massachusetts, and is used to determine ground water flow direction and velocity in monitoring wells or open boreholes. It operates by emitting heat pulses and measuring subsequent temperature increases carried by the ground water movement. The meter can be used in wells as small as 2 inches in diameter and only a single well is required for determination of ground water flow direction and rate.This paper is a case history of the use of the Geo Flowmeter in a complex hydrogeologic setting consisting of a partially above grade landfill located between a navigable waterway and a large storm water impoundment basin. Mounding effects of the landfill, tidal changes in the channel, varying water levels in the impoundment basin and a complex substrate (alternating layers of sand, silt and clay) presented a challenge for ground water interpretation and analysis. The Geo Flowmeter was lowered into existing monitoring wells surrounding the landfill to determine ground water flow direction and rate. Sensitivity of the meter was sufficient to distinguish two separate flow directions in a single well screen. Later investigation involving installation of piezometers, long‐term ground water level monitoring and plotting of ground water contours verified initial findings of the meter.This article presents numerous graphs and pictures to illustrate field use of the instrument and discusses advantages and disadvantages of its use. Actual field data collected is included to provide a basis for evaluating the accuracy of the instrument and identifying situations where it may be used.
Determining Head and Pressure Distribution in Low Transmissivity Formations and Soils
Authors: Kennedy K.G. , Hollingshead S.C. , Leech R.E.J. 
Published: February 2007

AbstractThere has been increased interest in low transmissivity formations as barriers to, and hosts for, different hazardous waste. Long periods of time are generally required to measure their in situ pressures or hydraulic heads. Sites need extensive instrumentation and monitoring schemes, which may be costly and may require long periods of time prior to providing well documented site‐specific data. A method has been developed that allows pressure and head distribution to be determined based on limited formation testing. This distribution can then be used to refine the final design of the borehole monitoring instrumentation.Recent work on shallow and deep, hazardous and nuclear waste disposal studies in Canada and Europe has provided the opportunity to investigate different methods for extrapolating and estimating the distribution of pressure and equivalent hydraulic head of the pore water in tight formations. The result is an approach that is cost‐effective, technically reasonable and relatively rapid. The technical basis of the method is not new. However, its application to determining profiles of either formation pressure or hydraulic head has not been well documented. This approach has potential for use in many site investigation studies.The method determines the profile of head or pressure between two “input” layers or formations, which have been well characterized with respect to their pressures or hydraulic heads and associated fluid characteristics. The pressure profile between the two layers is a function principally of the transmissivity of the tight formations between the input layers. Therefore, the primary objective of testing of the zones between the two input layers is designed to quantify this parameter. This testing can be relatively rapid compared to the time required to measure a representative formation pressure or water level. The technique is computerized for efficient tabulation and graphical data display. This paper presents the rationale associated with the extrapolation technique. Examples are given where the technique has been applied to both soil and rock formations with transmissivities less than 10‐8 m2/s and at depths up to 2,000m.
Interpretation of Gas Chromatographic Data in Subsurface Hydrocarbon Investigations
Authors: Senn Randolph B. , Johnson Martin S. 
Published: February 2007

AbstractCapillary column gas chromatography (GC) is extremely useful in investigations of subsurface contamination by petroleum hydrocarbons. Fluid samples collected from observation wells are evaluated by GC methods to detect and analyze petroleum hydrocarbons in dissolved and liquid phases. The presence, types and concentrations of many petroleum‐derived hydrocarbons dissolved in ground water can be determined. GC analysis can also be used to determine the composition of liquid hydrocarbon products, including gasoline, distillates and heavier oils. The degree of degradation of sampled liquid hydrocarbon product can be estimated from GC information, and this information can be helpful in estimating the length of time the product has been in the subsurface. Determination of the hydrocarbon source and migration path can be made from GC analysis of fluid samples collected at two or more locations.This paper is intended to demonstrate interpretative techniques that can be used by hydrogeologists to facilitate the detection, identification and mitigation of subsurface hydrocarbons.
A Wireline Piston Core Barrel for Sampling Cohesionless Sand and Gravel Below the Water Table
Authors: Zapico Michael M. , Vales Samuel , Cherry John A. 
Published: February 2007

AbstractA coring device has been developed to obtain long and minimally disturbed samples of saturated cohesionless sand and gravel. The coring device, which includes a wireline and piston, was developed specifically for use during hollow‐stem auger drilling but it also offers possibilities for cable tool and rotary drilling. The core barrel consists of an inner liner made of inexpensive aluminum or plastic tubing, a piston for core recovery, and an exterior steel housing that protects the liner when the core barrel is driven into the aquifer. The core barrel, which is approximately 1.6m (5.6 feet) long, is advanced ahead of the lead auger by hammering at the surface on drill rods that are attached to the core barrel. After the sampler has been driven 1.5m (5 feet), the drill rods are detached and a wireline is used to hoist the core barrel, with the sample contained in the aluminum or plastic liner, to the surface. A vacuum developed by the piston during the coring operation provides good recovery of both the sediment and aquifer fluids contained in the sediment. In the field the sample tubes can be easily split along their length for on‐site inspection or they can be capped with the pore water fluids inside and transported to the laboratory. The cores are 5cm (2 inches) in diameter by 1.5m (5 feet) long. Core acquisition to depths of 35m (115 feet), with a recovery greater than 90 percent, has become routine in University of Waterloo aquifer studies. A large diameter (12.7cm [5 inch]) version has also been used successfully. Nearly continuous sample sequences from sand and gravel aquifers have been obtained for studies of sedimentology, hydraulic conductivity, hydrogeochemistry and microbiology.
Drilling and Constructing Monitoring Wells with Hollow‐Stem Augers Part 2: Monitoring Well Installation
Authors: Hackett Glen 
Published: February 2007

AbstractThe procedures used to construct monitoring wells with hollow‐stem augers may vary depending on the hydrogeologic conditions at the site. In cohesive materials in which the borehole stands open, the auger column may be fully retracted from the borehole prior to the construction of the monitoring well. In non‐cohesive materials in which the borehole will not stand open, the monitoring well may be constructed through the hollow axis of the auger column.The techniques used to construct monitoring wells through the hollow axis of the auger column may vary depending on the specific site conditions and the experience of the driller. Selection of an appropriately sized diameter hollow‐stem auger for the installation of the required size of well casing is necessary to permit an adequate working space between the casing and augers, through which filter pack and annular seal materials are emplaced. Assurance that the filter pack and annular seal are properly emplaced is typically limited to careful measurements taken and recorded during construction of the monitoring well.
A Critical Examination of Approximations Implicit in Cochran's Procedure
Authors: McBean Edward A. , Kompter Michel , Rovers Frank 
Published: February 2007

AbstractThe approximations implicit in Cochran's approximation to the Behrens‐Fisher test are examined. This test is often used in evaluating ground water quality problems with temporal and spatial variabilities. Concern is focused on the impact of the number of samples and the magnitude of the variances at the sampling locations. Recommendations are presented for utilization of the t‐test and Cochran's approximation, because Cochran's test is an approximation formula. Indications are provided for where the results may be giving answers different from those intended.
Nitrate in the Intermediate Vadose Zone Beneath Irrigated Cropland
Authors: Spalding Roy F. , Kitchen Lisa A. 
Published: February 2007

AbstractMore than 1000 feet of fine‐textured, unsaturated zone core beneath nitrogen‐fertilized and irrigated farmland was collected, leached and analyzed for nitrate‐nitrogen. Fertility plots treated with 200, 300, and 400 Ibs N/acre/yr accumulated significant quantities of nitrate‐nitrogen in the vadose zone below the crop rooting zone. The average nitrate‐nitrogen concentration approximately doubled with each 100 lbs N/acre/yr increment above the 100 lbs N/ acre/ yr treatment. Nitrate loading estimates for the plots treated with 400 lbs N/ acre/ yr indicate that over 1200 lbs N/ acre was in the vadose zone beneath the crop rooting zone. In 15 years, the nitrate moved vertically at least 60 feet through these fine‐textured, unsaturated sediments. As much as 600 lbs N/acre have accumulated in the vadose zone under independent corn producers’fields.Vadose zone sampling is effective in predicting future non‐point nitrate‐contaminated areas.