bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of Lysimeter Leak Detector Networks for Surface Impoundments and Landfills
Authors: Bumb Amar C. , McKee Chester R. , Evans Roy B. , Eccles Lawrence A. 
Published: February 2007

AbstractSampling of soil pore moisture in the vadose zone underneath land disposal facilities (landfills and surface impoundments) for hazardous waste has been suggested as an “early warning system” to detect leakage from these facilities. Some states require vadose zone moisture sampling at such sites. Given a leak of a particular size, mathematical models can estimate the necessary moisture sample volume collection times and lysimeter spacings to guarantee detection of the leak in a homogeneous medium. Examination of 47 hazardous waste sites existing in 1984 indicated the most were located in areas with water tables too shallow to permit vadose zone detection monitoring. Several of the 47 sites had soils that could be described as loamy sand, silt loam or silty clay. Using these three soils as examples, the process of lysimeter leak‐detector network design has been illustrated. For a particular loamy sand with a saturates hydraulic conductivity of 10‐6 cm/ sec, the maximum ceramic lysimeter spacing is 15.5 feet at a depth of 30 feet to collec a moisture sample of 10 mL in one week from a 1 ft2 leak. For a silt loam, maximum lysimeter spacing would be 17 feet at depth of 15 feet. For silty clays, the maximum lysimeter spacing is 7 feet at a depth of 2 feet; maximum emplacement depth is about 9 feet. Calculations show that in some soils, suction lysimeters will not be able to collect usable moisture samples. Since soil properties vary widely and lysimeter spacing is strongly dependent on soil‐moisture characteristics appropriate soil measurements and modeling must be performed at each disposal facility to estimate lysimete performance and to select locations for emplacement.
Simulation of Vapor Transport Through the Unsaturated Zone — Interpretation of Soil‐Gas Surveys
Authors: Silka Lyle R. 
Published: February 2007

AbstractSoil‐gas surveys are becoming more widely accepted as a tool for the preliminary determination of the extent of soil and ground water contamination by volatile organic compounds (VOCs). The interpretation of the results of published soil‐gas surveys has been necessarily limited and qualitative due to a lack of adequate models. There has been considerable effort in the recent past to characterize the transport and fate of pesticides in soil. However, the behavior of pesticides generally differ substantially from those of VOCs.This paper presents a computer model developed to simulate the diffusive transport of VOC vapor through unsaturated soils using a two‐dimensional, finite‐difference, solution to Fick's second law of diffusion. An effective diffusion coefficient that incorporates the effects of tortuosity, moisture content, and soil organic carbon content is computed. Although the model has not been validated due to the unavailability of adequate field or laboratory data, nevertheless, sensitivity analyses demonstrate the importance of soil moisture and, secondarily, organic matter content in controlling the migration of VOC vapor through the unsaturated zone. The interpretation of soil‐gas surveys can be complicated by unknown spatial heterogeneities in soil moisture and organic carbon content, temporal variations in moisture content, extent of contaminant migration as a non‐aqueous phase liquid and by the unknown extent of VOC liquid and contaminated ground water.
Tracer Test Analysis of Anisotropy in Hydraulic Conductivity of Granular Aquifers
Authors: Kenoyer Galen J. 
Published: February 2007

AbstractA simple method of determining the anisotropy ratio of hydraulic conductivity in near‐surface granular aquifers using tracer test and piezometer measurements is presented. Depending on the length of time allowed, the test will yield anisotropy ratios that are representative of the distance traversed by the tracer during the test, up to tens of feet from the injection point for some systems. This method is illustrated with an application to a ground water flow system in northern Wisconsin.
Reliability of Chemical Analyses of Water Samples — The Experience of the UMTRA Project
Authors: Rice George , Brinkman James , Muller Dianna 
Published: February 2007

AbstractGround water quality investigations require reliable chemical analyses of water samples. Unfortunately, laboratory analytical results are often unreliable. The Uranium Mill Tailings Remedial Action (UMTRA) Project's solution to this problem was to establish a two‐phase quality assurance program for the analysis of water samples. In the first phase, eight laboratories analyzed three solutions of known composition. The analytical accuracy of each laboratory was ranked and three laboratories were awarded contracts. The second phase consists of on‐going monitoring of the reliability of the selected laboratories.The following conclusions are based on two years of experience with the UMTRA Project's Quality Assurance Program:• The reliability of laboratory analyses should not be taken for granted.• Analytical reliability may be independent of the prices charged by laboratories.• Quality assurance programs benefit both the customer and the laboratory.
Screened Auger Sampling: The Technique and Two Case Studies
Authors: Taylor Theodore W. , Serafini Michael C. 
Published: February 2007

AbstractThe screened auger is a laser‐slotted, hollow‐stem auger through which a representative sample of ground water is pumped from an aquifer and tested for water‐quality parameters by appropriate field‐screening methods. Screened auger sampling can be applied to ground water quality remedial investigations, providing:(1) a mechanism for determining a monitoring well's optimal screen placement in a contaminant plume; and (2) data to define the three‐dimensional configuration of the contaminant plume.Screened auger sampling has provided an efficient method for investigating hexavalent chromium and volatile organic compound contamination in two sandy aquifers in Cadillac, Michigan. The aquifers approach 200 feet in thickness and more than 1 square mile in area. A series of screened auger borings and monitoring wells was installed, and ground water was collected at 10‐foot intervals as the boreholes were advanced to define the horizontal and vertical distribution of the contaminant plumes. The ability of the screened auger to obtain representative ground water samples was supported by the statistical comparison of field screening results and subsequent laboratory analysis of ground water from installed monitoring wells.
A Discrete Point Sampler for Ground Water Monitoring Wells
Authors: MacPherson James R. , Pankow James F. 
Published: February 2007

AbstractA discrete point sampler has been developed that overcomes disadvantages inherent in several current small‐volume samplers. It is designed to obtain ground water samples after a well has been purged with a pump. It consists of a sample chamber, two ports, and a stopcock for withdrawing sample aliquots. After lowering the sampler into a well, sampling is initiated by pulling on a line that sequentially removes the plugs in the lower and the upper level ports. The sample chamber fills from the bottom port and vents air from the top port. The device is suitable for sampling for volatile organic compounds in ground waters that are not subject to spontaneous bubble degassing. The upper port is sufficiently far above the lower port that none of the water that is sampled is exposed to the vented air. The sample chamber fills in such a way that the water that is taken from the chamber for analysis is not exposed to the headspace in the chamber.
A New Continuous‐Sampling Wireline System for Acquisition of Uncontaminated, Minimally Disturbed Soil Samples
Authors: Clark Robert R. 
Published: February 2007

AbstractA new wireline system has been developed to alternately full‐hole drill or continuously sample soil in a variety of soils. Those samples recovered by the system are complete, relatively undisturbed, and minimally affected by drilling fluids. The system, which includes an outer barrel, center‐bit insert tube and a spring‐retract‐sampler inner barrel, can be used with either a core or rotary‐type drill. The system's outer barrel and bit act as a casing advancer to prevent hole collapse in unstable soils. The outer barrel and bit remain in the hole while either the center‐bit‐insert tube or the soil‐sampler inner barrel are wirelined in and out of the outer barrel and drill rod column. When the center‐bit insert is wirelined into place, it combines with the outer barrel and bit to become a full‐hole drilling tool. When this center‐bit insert is replaced with the soil‐sampler inner barrel, the system is capable of continuous soil sampling to depths ranging from several hundred to several thousand feet. The spring of this soil‐sampler inner barrel is designed to extend the drive‐shoe some 6 to 8 inches ahead of the outer‐barrel bit and the circulating fluids. Therefore, the sample is not in continuous contact with the circulating fluids during the sampling process.As the sample enters the soil‐sampler tube, those circulating fluids inside the tube are forced up and out through the inner barrel's fluid bypass. The result is a sample relatively free of contamination or washing by drilling fluids. Because the soil‐sampler tube comes in contact with the circulating fluid as it travels into sampling position, there is a film coating the recovered sample. Similarly, the fluid also coats either end of the sample. However, that film is easily scraped away before analysis. Should additional protection be required, a liner can be inserted inside the sampler tube. Sample contaminants can be totally eliminated through the use of filtered‐air circulation. In field use, negligible tearing or amalgamation of the samples has been experienced, because the soil‐sampler tube and retract‐spring are suspended from dual bearings, which prevent inner barrel rotation.
An Evaluation of Some Systems for Sampling Gas‐Charged Ground Water for Volatile Organic Analysis
Authors: Barker J.F. , Dickhout R. 
Published: February 2007

AbstractLoss of volatile organics during sampling is a well‐recognized source of bias in ground water monitoring; sampling protocols attempt to minimize such loss. Such bias could be enhanced for ground water highly charged with dissolved gases such as methane. Such ground water was the object of this study. A positive‐displacement bladder pump, a momentum‐lift pump and a suction‐lift, peristaltic pump were employed in sampling both methane‐charged ground water for volatile aromatic hydrocarbons and a CO2‐charged reservoir water for volatile chlorinated hydrocarbons. In both cases, the suction‐lift pump produced samples with a significant negative bias (9 to 33 percent) relative to the other methods. Little difference between samples produced by the other pump Systems was noted at the field site, but in sampling the reservoir, the bladder pump produced samples that were 13 to 19 percent lower in halocarbon concentration than were samples from the momentum‐lift pump.These negative biases are tentatively interpreted as losses due to volatilization during sampling. Slightly greater negative biases occur for compounds of higher volatility as estimated from their Henry's law constants. Additional studies appear to be warranted in order to adequately establish the scientific basis for recommending protocols for sampling ground water in which degassing could enhance the loss of volatile organics during sampling.
Comparison of Methods for Sampling Dissolved Nitrogen in a Fractured Carbonate‐Rock Aquifer
Authors: Lietman Patricia L. , Gerhart James M. , Wetzel Kim L. 
Published: February 2007

AbstractAs part of an agricultural non‐point‐source study in the Conestoga River head waters area in Pennsylvania, different methods for collecting ground water samples from a fractured carbonate‐rock aquifer were compared. Samples were collected from seven wells that had been cased to bedrock and drilled as open holes to the first significant water‐bearing zone. All samples were analyzed for specific conductance, dissolved oxygen, and dissolved‐nitrogen species. Water samples collected by a point sampler without pumping the well were compared to samples collected by a submersible pump and by a point sampler after pumping the well. Samples collected by using a point sampler, adjacent to major water‐bearing zones in an open borehole without pumping the well, were not statistically different from samples collected from the pump discharge or from point samples collected adjacent to major water‐bearing zones after pumping the well. Samples collected by using a point sampler without pumping the well at depths other than those adjacent to the water‐bearing zones did not give the same results as the other methods, especially when the water samples were collected from within the well casings. It was concluded that, for the wells at this site, sampling adjacent to major water‐bearing zones by using a point sampler without pumping the well provides samples that are as representative of aquifer conditions as samples collected from the pump discharge after reaching constant temperature and specific conductance, and by using a point sampler after pumping the well.
Should We Use a Well Foot (Sediment Trap) in Monitoring Wells?
Authors: Yu John K. 
Published: February 2007

AbstractTraditionally, the water well contractor adds a section of blank casing to the bottom of the well screen in a production well. This practice has been carried over to ground water monitoring wells by some engineers and hydrogeologists, and is even recommended by the RCRA Technical Enforcement Guidance Document (TEGD). After examining the proclaimed advantages, it is the author's opinion that the well foot is not necessary for a monitoring well.
Screening of Ground Water Samples for Volatile Organic Compounds Using a Portable Gas Chromatograph
Authors: Buchmiller Robert C. 
Published: February 2007

AbstractA portable gas chromatograph was used to screen 32 ground water samples for volatile organic compounds. Seven screened samples were positive; four of the seven samples had volatile organic substances identified by second‐column confirmation. Four of the seven positive, screened samples also tested positive in laboratory analyses of duplicate samples. No volatile organic compounds were detected in laboratory analyses of samples that headspace screening indicated to be negative. Samples that contained volatile organic compounds, as identified by laboratory analysis, and that contained a volatile organic compound present in a standard of selected compounds were correctly identified by using the portable gas chromatograph. Comparisons of screened‐sample data with laboratory data indicate the ability to detect selected volatile organic compounds at concentrations of about 1 microgram per liter in the headspace of water samples by use of a portable gas chromatograph.
In‐House Well Drilling Operations for a Ground Water Monitoring Program, Suffolk County, New York
Authors: Cary Steven V. , Markel Richard 
Published: February 2007

AbstractAll public agencies involved in ground water monitoring and protection face the requirement of obtaining well drilling services consistent with their needs. Most will rely on contracted drilling services, but a limited number of agencies having responsibilities for long‐term aquifer monitoring and the promulgation of monitoring standards may find that implementing an in‐house well drilling program is an effective approach to achieving their ground water protection goals.Suffolk County, located on Long Island, New York, has been operating a well drilling program for 10 years, with three levels of drilling capability to meet the requirements of characterizing and monitoring an unconsolidated regional aquifer system. The program's cost and labor requirements are substantial, but this approach has provided uniformly high‐quality data and the hands‐on experience needed to test drilling innovations and produce monitoring regulations that are effective and feasible. If soundly organized and run, an agency‐directed drilling operation will be readily adaptable to changing needs and priorities. In Suffolk County, this has included emergency response and fuel‐spill monitoring. A successful program must also include a demonstrated geologic identification and well logging capability, close laboratory support, and an experienced hydrogeological or ground water engineering staff.This approach may be suitable for other regional agencies based on their ground water conditions and water‐supply protection needs.
A Proposal to Use Chlorine‐36 for Monitoring the Movement of Radionuclides from Nuclear Explosions
Authors: Phillips Fred M. , Davis Stanley N. , Kubik Peter 
Published: February 2007

AbstractChlorine‐36 has been produced in large amounts by hundreds of nuclear explosions on the Nevada Test Site as well as 12 off‐site explosions at eight locations in five states. Continued monitoring of the redistribution of radionuclides by subsurface water is of concern in most of the areas affected by the detonations. Chlorine‐36 has the following advantages as a built‐in tracer for this redistribution: its mobility is equal to or greater than water, its long half‐life assures its continued usefulness over long periods, collection and storage of samples is simple, it is not subject to vapor transport at ordinary temperatures, its natural background is very low, and it does not form insoluble precipitates. Chlorine‐36 from the Gnome event near Carlsbad, New Mexico, illustrates how 36C1 can be used to help study the redistribution of radionuclides in the soil profile. Chlorine‐36 is also potentially useful as a tracer to study movement of contaminants around large nuclear reactor complexes and near respositories for radioactive waste.
Remote Data Collection and Control for Hydrogeologic Monitoring
Authors: Adomait Martin , Gillham Robert W. 
Published: February 2007

AbstractA hydrogeologic field experiment, conducted at a research site some 125 miles (200km) from the home base, used commercially available computer controller technology for data collection and experimental control. A telephone line connected to the equipment facilitated the downloading of data, provided a means of remotely monitoring the operating performance, and made it possible to adjust the monitoring procedures.This experiment demonstrated the benefits of a remotely controlled data acquisition system for a long‐term investigation. Identification of problems and the adjustment of the sampling algorithm by telephone reduced costly travel time. The considerable amount of data collected, the data evaluation techniques, and the continuous monitoring, provided a high degree of confidence in the results.
Preliminary Delineation of Contaminated Water‐Bearing Fractures Intersected by Open‐Hole Bedrock Wells
Authors: Williams John H. , Conger Randall W. 
Published: February 2007

AbstractContaminated water‐bearing fractures intersected by open‐hole bedrock wells were preliminarily delineated through a combination of geophysical logging, vertical‐flow measurements, and downhole water sampling as part of remedial site investigations in southeastern New York. The wells investigated range from 100 to 450 feet in depth, have only shallow surface casing, and intersect multiple water‐bearing zones. The distribution of water‐bearing zones that intersect the wells was determined from single‐point resistance, caliper, fluid‐resistivity, temperature, and acoustic‐televiewer logs. Measurable flow in the wells was downward from upper producing zones to lower receiving zones that are poorly connected in the aquifer and that differ in hydraulic head as a result of nearby pumping. A down hole sampler was used to collect discrete and composite water samples for analysis of volatile organic compounds from producing zones that are self‐purging as a result of flow in the wells.The results obtained at two of the study sites are presented—the Spring Valley wellfield and the Mahopac business district. At the Spring Valley wellfield, a supply well completed in Mesozoic sandstone and conglomerate intersects water‐bearing zones at depths of 204 to 245 feet that produced contaminated water that was received by a zone at 278 feet. In the same well, a deeper zone at 345 feet produced uncontaminated water that was received by a zone at 403 feet. Correlation of information from the well, geophysical logs and drill cores from nearby monitoring wells, and bedrock outcrops indicates that most of the water‐bearing zones are bedding‐plane separations that probably provide pathways for contaminant transport in the bedrock aquifer for significant distances.In the Mahopac business district, a deep test well completed in Precambrian gneiss intersected shallow waterbearing zones at 50 to 79 feet that produced contaminated water that was received by deep zones at 260 and 328 feet. The water‐bearing zones consist of single or closely spaced multiple fractures with dips of 5 to 50 degrees. By analogy with the results from this test well, deep open‐hole wells in the area may serve as “short circuits” in the ground water flow system and allow direct transport of contaminants to deeper zones in the fractured‐bedrock aquifer.The methods presented can be used to investigate ground water flow and contamination in fractured‐bedrock aquifers in advance of more focused monitoring programs. The methods can be applied in existing open‐hole wells before test drilling and monitoring well installation to provide for efficient program design. The methods also can be used during the installation of monitoring wells to help determine completion depths and open intervals and to ensure that the wells are not serving as conduits for the flow of contaminated water.
Comparisons of Three Methods to Determine the Vertical Stratification of Pore Fluids
Authors: Taylor Kendrick , Hess John , Mazzella Aldo , Hayworth Joel 
Published: February 2007

AbstractThree methods were used to investigate the possibility of vertical stratification of the pore fluid in an aquifer. The wells available for the study were fully screened and had a 5cm disturbed annulus around them. The first method used a pump with a straddle packer to isolate a short section of the secreened interval. A tracer test demonstrated that most of the pumped sample came from the well bore, presumably by piping through the disturbed. annulus. The second method used induction logs to measure the formation electrical conductivity as a function of depth. Due to the presence of clays and an inability to obtain porosity information, it was not possible to determine the pore fluid electrical conductivity using induction logs. A third method, dilution sampling, was developed that used a straddle packer to isolate a segment of the well screen. A tracer was injected into the packed‐off segment, and the tracer concentration in the well was monitored. The tracer was removed from the packed‐off segment by dilution and advection by ground water. When the tracer was completely removed from the packed‐off segment, the fluid in the segment was considered to be representative of the adjacent pore fluid. Only the dilution sampling method determined unambiguously that the pore fluid was not stratified.