bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Dual‐Wall Reverse‐Circulation Drilling in Ground Water Exploration and Monitoring
Authors: Strauss M. Fred , Story Steve L. , Mehlhorn Norman E.
Published: February 2007

Dual‐wall reverse‐circulation drilling uses flush‐threaded double‐wall drill pipe and high‐pressure air to provide continuous return of formation and water samples. Cuttings and formation waters are not contaminated with drilling additives or mixed with other borehole material. Up‐hole velocity of about 70 ft/sec provides reliable logging of water, mineral or contaminant‐bearing strata. Water samples representative of specific strata may be airlifted or bailed to the surface.

In the percussion hammer system, dual‐wall drill pipe is advanced through chiefly unconsolidated material by the percussion action of an above‐ground pile hammer. The borehole is drilled and temporarily cased in one pass. Wells or monitoring devices are installed as the drill pipe is hydraulically retracted during construction. A rotary head may be adapted as an option to allow dual‐wall rotary drilling into consolidated or crystalline formations through a percussion hammer drill string temporarily left in place as a conductor.

The complex geology and variety of geoenvironmental problems in southern California has provided a testing ground for dual‐wall drilling on hazardous material site investigations. Several case histories have demonstrated the capabilities and versatility of this method, including: (1) the installation of 4‐inch and 6‐inch diameter gasoline monitoring and recovery wells through gravels and cobbles at a filling station where hollow‐stem auger drilling failed; (2) the confirmation of a dry borehole initially drilled by direct rotary at a landfill; and (3) multiple installations of monitoring devices through municipal refuse at a city of Los Angeles landfill.
Investigation of Failure Mechanisms and Migration of Organic Chemicals at Wilsonville, Illinois
Authors: Herzog B.L. , Griffin R.A. , Stohr C.J. , Follmer L.R. , Morse W.J. , Su W.J.
Published: February 2007

Ground water contamination was discovered in 1981 in a monitoring well at the Earthline disposal facility near Wilsonville, Illinois. Organic chemicals had migrated at a rate 100 to 1000 times greater than predicted when the site received its permit to operate in 1978. Postulated failure mechanisms included migration through previously unmapped permeable zones, subsidence of an underground mine, organic‐chemical and clay‐mineral interactions, acid‐mine drainage and clay interactions, trench‐cover settlement, and erosion.

In this investigation, the Illinois State Geological Survey found the primary reason for the rapid migration: the presence of previously undetermined fractures and joints in glacial till. The inaccurate predictions of hydraulic conductivity were based on laboratory‐determined values that did not adequately measure the effects of fractures and joints on the transit time calculations. Field‐measured hydraulic conductivity values were generally 10 to 1000 times greater than their laboratory‐measured counterparts, thus largely accounting for the discrepancy between predicted and actual migration rates in the transit time calculations. The problem was compounded, however, by the burial of liquid wastes and by trench covers that allowed excess surface runoff to enter the trenches. Organic‐chemical and clay‐mineral interactions may also have exacerbated the problem in areas where liquid organic wastes were buried.
The Hydropunch™: An In Situ Sampling Tool for Collecting Ground Water from Unconsolidated Sediments
Authors: Edge Russel W. , Cordry Kent
Published: February 2007

The Hydropunch™ is a stainless steel and Teflon® sampling tool that is capable of collecting a representative ground water sample without requiring the installation of a ground water monitoring well. To collect a sample, the Hydropunch (Patent #4669554) is connected to a small‐diameter drive pipe and either driven or pushed hydraulically to the desired sampling depth. As the tool is advanced, it remains in the closed position, which prevents soil or water from entering the Hydropunch. Once the desired sampling depth is obtained, the tool is opened to the aquifer by pulling up the drive pipe approximately 1.5 feet (0.46m). In the open position, ground water can flow freely into the sample chamber of the tool. When the sample chamber is full, the Hydropunch is pulled to the surface. As the tool is retracted, check valves close and trap the ground water in the sample chamber. At the surface the sample is transferred from the Hydropunch to an appropriate sample container. The tool is a fast, inexpensive alternative for collecting ground water samples from a discrete interval. It is excellent for vertical profiling or defining the areal extent of a contaminant plume.
Subsurface Transport of Inorganic and Organic Solutes from Experimental Road Spreading of Oil‐Field Brine
Authors: Bair E. Scott , Digel Robert K.
Published: February 2007

A study designed to evaluate ground water quality changes resulting from spreading oil‐field brine on roads for ice and dust control was conducted using a gravel roadbed that received weekly applications of brine eight times during the winter phase and 11 times during the summer phase of the study. A network of 11 monitoring wells and five pressure‐vacuum lysimeters was installed to obtain ground water and soil water samples. Thirteen sets of water‐ quality samples were collected and analyzed for major ions, trace metals, and volatile organic compounds. Two sets of samples were taken prior to brine spreading, four sets during winter‐phase spreading, five sets during summer‐ phase spreading, and two sets during the interim between the winter and summer phases. A brine plume delineated by elevated specific‐conductance values and elevated chloride concentrations developed downgradient of the roadbed during both the winter and summer phases. The brine plume caused chloride concentrations in ground water samples to exceed U.S. EPA public drinking‐water standards by two‐fold during the winter phase and five‐fold during the summer phase. No other major ions, trace metals, or volatile organic compounds exceeded the standards during the winter or summer phases. More than 99 percent dilution of the solutes in the brine occurred between the roadbed surface and the local ground water flow system. Further attenuation of calcium, sodium, potassium, and strontium resulted from adsorption, whereas further attenuation of benzene resulted from volatilization and adsorption.
A Surface‐Flux Measurement Method for Screening Contamination from Volatile Organic Compounds
Authors: Karp Kenneth E.
Published: February 2007

Measurement of the vapor flux from volatile organic compounds (VOCs) provides a rapid means for screening large areas of potential contamination. The vapor flux is determined from the rate of VOC concentration buildup inside a 3.1L accumulator device that is sealed to the surface of the contaminated soil. After the VOC concentrations are allowed to increase for a few minutes, they are analyzed with a portable gas chromatograph or a total organic vapor analyzer.

The measurement approach was evaluated at a field site in an area where the ground water and soil had been impacted with Jet Fuel No. 4 (JP‐4). An indication of the areal extent of impact was determined by mapping the surface VOC vapor flux. The pattern revealed by the flux measurements was found to coincide, in rough outline, with the known extent of toluene concentrations in the ground water and with conventional soil‐gas survey results. In addition, a mathematical model describing VOC diffusion into the accumulator device was verified by performing laboratory measurements of the surface VOC vapor flux on a sandbox designed to simulate a hazardous waste site.
Effects of Access Tube Material and Grout on Neutron Probe Measurements in the Vadose Zone
Authors: Keller B. R. , Everett L. G. , Marks R. J.
Published: February 2007

A test‐stand experiment was conducted on neutron probe measurements using steel and Schedule 40 PVC access tubes to determine the effect of backfill grout in boreholes. The experiment used a moveable simulated vadose zone. Access tubes and grout do have masking effects on vadose zone measurements, but vadose zone moisture was detected through all configurations tested. Steel tubing has a smaller masking effect than PVC tubing. The masking effect of grout increased with borehole diameter. Although this experiment produced numerical results, conclusions drawn are qualitative in nature, rather than a quantitative calibration of the technique.
Assessment of Pesticides in Upstate New York Ground Water: Results of a 1985‐1987 Sampling Survey
Authors: Walker Mark J. , Porter Keith S.
Published: February 2007

The New York State Water Resources Institute at Cornell University undertook a two‐year sampling survey of pesticides in ground water beginning in 1985. The survey focused on areas where combinations of agricultural pesticide use, soil texture, and ground water occurrence seemed likely to lead to leaching. The sampling survey included samples from four types of sampling points: (1) monitoring wells; (2) existing water supply wells; (3) test holes; and (4) tile drains. The monitoring wells were sampled repeatedly throughout the project to attempt to characterize temporal changes in water quality corresponding with seasonal changes in ground water levels. The pesticides studied for this project were atrazine, alachlor, cyanazine, metolachlor, carbaryl, carbofuran (and a metabolite, 3‐hydroxy carbofuran), and simazine. All, except for carbaryl, have been found in ground water in other sampling surveys in the United States.

The results of the sampling survey did not reflect the careful choices of enviromental characteristics and pesticide use that seemed likely to lead to leaching. Residues of three pesticides were detected in six single samples from separate sources at four of the 30 sites tested. Three of the six samples came from shallow test holes that were used to sample the shallowest possible saturated soils beneath fields. The three pesticides detected were atrazine, simazine, and 3‐hydroxy carbofuran. Of the six samples, a single sample from a test hole contained atrazine concentrations equal to the current federal health advisory for long‐term exposure to atrazine (3 ppb).

The remaining detections were between the limit of detection for analytical methods and the federal health advisory for each pesticide. The federal health advisories were formulated after the end of the project. Analytical methods may have been insensitive with respect to these advisories. Sampling results from other surveys suggest that many detections of the same pesticides lie below the limits of detection used for this sampling survey.

A possible explanation for the lack of detections, given the design of the sampling survey, may lie in the agricultural practices noted at sampled sites. Most of the farm managers rotated their crops and pesticides on many small fields. Although the environmental conditions chosen for sampling sites were expected to lead to contamination, reported pesticide applications varied from year to year and field to field according to rotational schedules. The inconsistency of applications from year to year may explain the lack of detections (at the limits of quantification used for analyses) noted in this sampling survey.
A Ground Water Monitoring Study for Pesticides and Nitrates Associated with Golf Courses on Cape Cod
Authors: Cohen Stuart Z. , Nickerson Susan , Maxey Robert , Jr. Aubry Dupuy , Senita Joseph A.
Published: February 2007

Scientists and regulators in the United States began emphasizing the study of pesticides in ground water in 1979 and 1980. The scientific community began to emphasize the study of nitrates in ground water as a result of fertilization in the mid to late 1970s. By the mid 1980s. tens of thousands of wells were found to contain elevated nitrate concentrations and detectable concentrations of pesticides. Few, if any, of the data were collected from wells associated with the nation's 13,000 golf courses.

Golf is popular on Cape Cod, an area that depends on a hydrogeologically vulnerable aquifer system as its principal source of drinking water. Pesticides and fertilizers are applied to golf courses, often at high rates on greens and tees. Therefore the EPA, the Barnstable County government, and several local golf course superintendents collaborated on a study of the impact of golf course turf management on ground water quality.

Nineteen monitoring wells were installed upgradient and in greens, tees, and fairways on four golf courses. Selected soil core samples were collected and analyzed. Four to six rounds of ground water samples were collected over one and a half years and analyzed for 17 pesticides and related chemicals; nitrate‐N samples were collected at least monthly. Seven of the 17 chemicals were never detected. The most frequently detected chemical‐dichlorobenzoic acid ‐ probably had been an impurity in herbicide formulations. Chlordane was detected in several wells at concentrations exceeding the health advisory level, perhaps due either to repeated heavy applications coupled with preferential flow of the bound/particulate phase and /or cross contamination during well installation. The results show no cause for concern about use of these currently registered pesticides.

Nitrate‐N concentrations were generally below the 10 ppm federal MCL, with some exceptions. Overall, nitrate‐N concentrations decreased in response to lower application rates and use of slow‐release fertilizer formulations.
Monitoring Well Completion Evaluation with Borehole Geophysical Density Logging
Authors: Yearsley E.N. , Crowder R.E. , Irons L.A.
Published: February 2007

Grout continuity and the location of the bentonite seal and sand pack in PVC‐cased monitoring wells can be evaluated with cased‐hole geophysical density logs. This method relies upon density contrasts among various completion conditions and annular materials. Notably, the lack of annular material behind pipe (i.e., void space) creates a low‐density zone that is readily detected by borehole density measurements.

Acoustic cement bond logging has typically been applied to the evaluation of cement in the annular space of completed oil and gas production wells, and in some cases to ground water monitoring wells. These logs, however, can only be obtained in the fluid‐filled portion of the borehole, and their interpretation is severely hindered by the presence of the micro‐annulus between casing and cement. The influence of the micro‐annulus on cement bond logs can be mitigated in steel‐cased wells by pressurizing the wellbore during acquisition of the log, but this procedure is not feasible in PVC‐cased monitoring wells. The micro‐annulus does not affect cased‐hole density logs or their interpretation.

Empirical measurements made in the laboratory with density probes provide information on their depths of investigation and response to specific completion conditions. These empirical data, and general knowledge of the density of annular completion materials (sand, bentonite, cement), are used to support interpretations of cased‐hole density logs acquired in the field. Three field examples demonstrate the applicability of geophysical density logs to the evaluation of PVC‐cased monitoring well completions.
Reduction of Nitrate Loadings to Ground Water
Authors: Shirmohammadi Adel , Magette William L. , Shoemaker Leslie L.
Published: February 2007

Non‐point source pollution of ground water systems has become a national concern in recent years. Researchers and regulatory agencies are investigating the source and processes of the contamination. Agricultural best management practices (BMPs) traditionally developed to reduce non‐point source pollution of surface water resources are being investigated for their impact on ground water quality. This study used the CREAMS model to simulate the long‐term effects of seven different BMPs on nitrate nitrogen (NO3‐N) loadings to a shallow, unconfined ground water system. Two representative watersheds, 5.8 and 8.9 hectares (14.3 and 22 acres) in area, in the Coastal Plain physiographic region of Maryland were selected for study. Soils in these watersheds belong to the Matapeake silt loam series and have moderate infiltration capacity. Results from this study indicated that BMPs used in conjunction with winter cover (barley) reduced NO3‐N leaching to the ground water system. It was also found that turfgrass reduced surface losses of water and nitrogen, but increased leaching losses of water and NO3‐N significantly. All of the BMPs simulated in this study resulted in leachate NO3‐N concentrations exceeding 10 ppm, the U.S. EPA health standard for public drinking water, indicating a need for alternate practices for reducing nitrate leaching.
The Use of a Standpipe to Evaluate Ground Water Samplers
Authors: Tai Doreen Y. , Turner Kenneth S. , Garcia Lisa A.
Published: February 2007

A standpipe system was developed for testing the reliability of ground water samplers. The unit consists of a stainless steel pipe 5 inches (13 centimeters) in diameter and 100 feet (30.5 meters) in height. It has 14 sampling ports from which control samples can be withdrawn at the same time and position as the samples are collected by a sampler lowered to that position. Test solutions were made in two mixing tanks, totaling 260 gallons (980 liters), by diluting the concentrate of five volatile chlorohydrocarbons in water at two levels of concentration: 10‐to‐30 and 100‐to‐200 parts per billion (micrograms per liter).

A gas chromatograph interfaced with a purge‐and‐trap system was used to perform the analyses. Comparisons of the control samples with the sampler‐collected samples have indicated that the three non‐pumping samplers had recoveries in the range of 92.4 to 103.5 percent and the three pumping samplers had recoveries ranging from 97.7 to 101.5 percent.
Investigation of Possible Contamination of Shallow Ground Water by Deeply Injected Liquid Industrial Wastes
Authors: Lesage Suzanne , Jackson Richard E. , Priddle Mark , Beck Paul , Raven Ken G.
Published: February 2007

The objective of this study was to assess the possible impact of deep well disposal operations, conducted between 1958 and 1974, on the ground water quality in a shallow fresh water aquifer beneath Sarnia, Ontario, Canada. Because of the breakout of formation fluids in Sarnia and Port Huron, Michigan, in the early 1970s, it had been hypothesized that liquid waste from the disposal zone in bedrock had leaked through numerous abandoned oil, gas, and salt wells in the area up to the shallow fresh water aquifer and from there to the surface.

A monitoring well network of 29 5cm (2 inch) diameter piezometers was established in the thin sand and shale aquifer system, which exists between 30 and 70m (100 and 230 feet) below ground surface. In addition, a 300m (1000 foot) deep borehole was drilled and instrumented with a Westbay multilevel casing, which permitted sampling of the disposal zone.

Ground water samples from the shallow monitoring wells and the Westbay multilevel casing were analyzed for volatiles by GC/MS. Those volatile aromatics that were conspicuously present in the deep disposal zone, e.g., ethyl toluenes and trimethyl benzene, were not detected in the shallow monitoring wells. Thus, if contaminants from the disposal zone did indeed migrate to the shallow aquifer, contamination was not widespread and probably consisted mostly of displaced chloride‐rich formation waters.
A Method for Assessing Residual NAPL Based on Organic Chemical Concentrations in Soil Samples
Authors: Feenstra Stan , Mackay Douglas M. , Cherry John A.
Published: February 2007

Ground water contamination by non‐aqueous phase liquid (NAPL) chemicals is a serious concern at many industrial facilities and waste disposal sites. NAPL in the form of immobile residual contamination, or pools of mobile or potentially mobile NAPL, can represent continuing sources of ground water contamination. In order to develop rational and cost‐effective plans for remediation of soil and ground water contamination at such sites, it is essential to determine if non‐aqueous phase liquid (NAPL) chemicals are present in the subsurface and delineate the zones of NAPL contamination. The presence of NAPL pools may be evident as a floating or sinking phase in monitoring wells. The residual NAPL contamination may be identified in soil samples if residual contents are high and contaminated zones in the soil cores are thick. However, visual identification may not be effective if residual contents are low or if the NAPL residual is distributed heterogeneously in the samples. The chemical analysis of soil samples provides a measure of the total chemical concentration in the soil but cannot determine directly whether NAPL is present in the samples. Qualitatively, soil analyses that exhibit chemical concentrations in the percent range or >10,000 mg/kg would generally be considered to indicate the presence of NAPL. However, the results of soil analyses are seldom used in a quantitative manner to assess the possible presence of residual NAPL contamination when chemical concentrations are lower and the presence of NAPL is not obvious. The assessment of the presence of NAPL in soil samples is possible using the results of chemical and physical analyses of the soil, and the fundamental principles of chemical partitioning in unsaturated or saturated soil. The method requires information on the soil of the type typically considered in ground water contamination studies and provides a simple tool for the investigators of chemical spill and waste disposal sites to assess whether soil chemical analyses indicate the presence of residual NAPL in the subsurface.
LNAPL Distribution in a Cohesionless Soil: A Field Investigation and Cryogenic Sampler
Authors: Durnford D. , Brookman J. , Billica J. , Milligan J.
Published: February 2007

Lighter‐than‐water Non‐Aqueous Phase Liquids (LNAPLs), such as jet fuels or gasolines, are common contaminants of soils and ground water. However, the total volume and distribution of an LNAPL is difficult to accurately determine during a site investigation. LNAPL that is entrapped in the saturated zone due to fluctuating water table conditions is particularly difficult to quantify. Yet, the amount of entrapped product in the saturated zone is theoretically higher, per volume of soil, than the residual product in the unsaturated zone, and small amounts of LNAPL in the saturated zone can contaminate large volumes of ground water.

The only method currently available to quantify the amount of LNAPL is direct soil‐core sampling combined with laboratory analysis of the fluid extracted from the soil cores. However, direct sampling of saturated ground water systems with conventional samplers presents a number of problems. In this study, a new sampler was developed that can be used to retrieve undisturbed soil and pore fluid samples from below the water table in cohesionless soils. The sampler uses carbon dioxide to cool the bottom of a saturated soil sample in situ to near freezing. Results of a field study where a prototype sampler was tested demonstrate the usefulness of a cryogenic sampler and show that the amount of LNAPL entrapped below the water table can be a significant part of the total LNAPL in the soil.
The Geochemistry of Boron in a Landfill Monitoring Program
Authors: Uhlman Kristine
Published: February 2007

Ground water monitoring data collected during the past eight years at a permitted municipal solid waste (MSW) disposal facility located in the midwestern United States indicated fluctuations in typical leachate indicator parameter concentrations. Apparent trends in the data inferred leachate outbreak, generating suspicion as to the integrity of the landfill liner. Eight ground water monitoring wells were installed in three distinct geologic units at the landfill facility, including glacial drift, silurian dolomite, and a post‐glacial peat fen, which is downgradient from the landfill. Piezometer nests were used to define ground water gradients at the site. Using boron as an indicator, the occurrence of analytes of concern in the downgradient monitoring wells were shown to be indicative of the natural geochemistry of site ground water. This work emphasizes the importance of understanding site hydrogeology during the interpretation of ground water quality data.
Vadose Zone Monitoring with the Neutron Moisture Probe
Authors: Kramer John H. , Cullen Stephen J. , Everett Lome G.
Published: February 2007

The neutron moisture probe is widely applicable to vadose zone monitoring problems which require measuring variable moisture contents. Neutron data are proportional to hydrogen density (modified by local chemistry) and sensitive to wetting fronts as well as changing volumes of hydrocarbon liquids. They cannot, however, be used to confirm contaminant chemistry, nor to detect steady‐state flow. Neutron data are amenable to statistical analysis, providing a measure of the significance of data variations. Detection of incipient moisture changes at numerous monitoring locations is more practical using raw neutron data than data calibrated for moisture content because calibrations suffer from uncertainties associated with soil heterogeneities. When properly applied, the neutron probe is an effective monitoring tool as illustrated by three example applications described in this paper: (1) neutron moisture logs are used to detect subtle lithologic changes and identify monitoring horizons; (2) sequential neutron data are used to track induced saturation at a soil flushing pilot study; and (3) neutron logs from a horizontal access tube beneath a waste facility are used to pinpoint moisture anomalies.
Frequency Domain Electromagnetic Induction Sounding Surveys for Landfill Site Characterization Studies
Authors: Jansen John , Haddad Bassem , Fassbender Wayne , Jurcek Patrick
Published: February 2007

A frequency domain electromagnetic induction sounding survey (FDEM) was conducted on a landfill in northern Illinois to determine the depth of fill, locate areas of drum disposal, and locate areas of heavy metal sludge disposal. Sketchy information obtained from interviews of the site personnel identified specific exploration targets and areas of concern. The results of the geophysical survey verified much of the reported disposal history and identified areas suspected to contain hazardous waste.

Based on the results of the survey, the thickness of fill was estimated and two areas with highly conductive fill were located. These areas could represent leachate pockets or sludge disposal areas. An area in which the fill appears to be thicker than expected was identified. This area is thought to represent industrial sludge disposal in trenches excavated into the existing fill and underlying soils. An area with several linear in‐phase, quadrature, and conductivity highs was detected. A subsequent magnetometer survey detected linear magnetic anomalies that are believed to be caused by parallel trenches filled with steel drums. This area is believed to be a previously unreported hazardous waste drum disposal cell excavated into the native soil.

As of this writing, the results of this survey have not been verified by traditional intrusive methods. When these investigations begin, we expect that information provided by the FDEM survey will reduce project costs by directing subsequent investigations, thereby reducing the number of borings and test pits required to characterize the site. While there is an unavoidable margin of error and uncertainty in remote sensing methods, the subsurface coverage provided by this geophysical survey could not have been reproduced by traditional methods without substantial expense. This paper presents the results of the survey and discusses application of the FDEM method on landfills.
Comparison of Stainless Steel vs. PTFE Miniwells for Monitoring Halogenated Organic Solute Transport
Authors: Bianchi‐Mosquera Gino C. , Mackay Douglas M.
Published: February 2007

Field tests of organic solute transport behavior have often been monitored using small‐diameter wells (miniwells). To determine if experimental results could be significantly biased by sorption to, desorption from, or diffusion through sampling lines, dissolved concentrations of tetrachloroethene and carbon tetrachloride were measured in ground water samples collected simultaneously from the same spatial location during a forced‐gradient test in the Borden aquifer using polytetrafluoroethene (PTFE) and stainless steel miniwells (1/8‐inch O.D.).

A semiautomated organic analytical system was used on‐site to obtain real‐time results, which avoided sample holding problems and permitted optimizing sampling times. The breakthrough curves (plots of concentration vs. time) for both organic compounds indicate that under the conditions of this experiment (low organic solute concentrations, short exposure time of sampling lines to the plume, adequate flushing of sampling lines) there is no significant difference between concentration histories (breakthrough curves) collected using a polytetrafluoroethene sampling line and those collected using a stainless steel sampling line. This suggests that organic solute tailing seen in this and also in a similar transport experiment previously conducted at the site is the result of transport processes in the aquifer rather than an artifact introduced by the PTFE miniwells.
Evaluation of Several Vacuum Solution Samplers in Sand and Silt Loam at Several Water Potentials
Authors: McGuire P.E. , Lowery B.
Published: February 2007

Until recently, there was little information available on the water collection capabilities of pore water samplers. This study was conducted to evaluate the performance of ceramic, fritted‐glass, stainless steel, and polytetrafluoroethylene (PTFE) porous samplers in sand and silt loam soil columns over a range of soil water potentials. Soil solution intake for samplers was determined by application of constant and falling vacuums. Constant vacuum was applied for a three‐day period when soils were at field moisture capacity. The PTFE samplers did not function when tested with a constant or falling vacuum. With a 50‐kPa constant vacuum, the ceramic sampler collected the greatest sample volume (average 20 mL) from the sand. With a constant 25‐kPa vacuum, the stainless steel sampler collected the greatest sample volume (average 81 mL) from the silt loam soil. Sampler performance with a fixed volume of vacuum was evaluated by applying 100 kPa vacuum to a 1‐liter reservoir. With this falling vacuum, samplers were tested until no further solution was collected over a 10‐day test period. With a falling vacuum, fritted‐glass and stainless steel samplers, with relatively larger pores and greater hydraulic conductance, collected a greater volume of sample and at a faster rate than ceramic samplers in sand soil that was nearly saturated. When the volume was normalized with respect to sampler surface area, for the falling vacuum tests in silt loam soil at field moisture capacity, the volume collected by fritted glass was significantly higher than those from other samplers. In sand at field moisture capacity or silt loam at soil water tensions ≧30 kPa, ceramic samplers maintained vacuums near 70 kPa and collected more sample than the other samplers during the 10‐day test period.
A Dry Injection System for the Emplacement of Filter Packs and Annular Seals in Ground Water Monitoring Wells
Authors: Boyle D.R.
Published: February 2007

The reliability of filter pack and annular seal emplacements, and the degree of integrity of installed seals, are two of the most important factors to be considered when both installing and later utilizing ground water monitoring wells.

Numerous, and often costly, problems of using existing methods of installing filter packs and annular seals during the construction of ground water monitoring wells have led to the development of a technique of installing these monitoring well components using a dry injection system.

The dry injection system has been used to construct monitoring wells in extremely complex overburden/bedrock environments with a variety of drilling techniques. The system has shown that a high degree of reliability in the, construction of monitoring wells and greater confidence in obtaining representative ground water samples can be achieved over existing methods of filter pack and annular seal emplacement. The system has also been more cost effective than existing methods, especially for deep boreholes and multilevel monitoring system installations.
Comparison of Two Integrated Methods for the Collection and Analysis of Volatile Organic Compounds in Ground Water
Authors: Patterson Bradley M. , Power Terry R. , Barber Chris
Published: February 2007

The principal difficulties with determinations of volatile organic compounds (VOCs) in ground water are the reliability of sampling procedures and analytical methods. Two integrated methods have been developed for routine sampling, processing, and analysis of VOCs in ground water. These methods involve in situ collection of ground water using a modified syringe sampler from PVC piezometers or using dedicated glass syringes from stainless steel multilevel bores. The samples are processed in the syringe using purge and trap or microsolvent extraction and analyzed by GC/MSD.

The modified purge‐and‐trap method is time‐consuming and limited to volatile organic compounds. However, it is extremely sensitive and flexible: the volume of sample used can be varied by the use of different‐size glass syringes (sample volumes from 1 to 100 mL).

In cases where extremely low sensitivity (<10 mg 1−1) is not critical, the microextraction technique is a more cost‐effective method, allowing twice as many samples to be analyzed in the same time as the purge‐and‐trap method. It enables less volatile compounds such as polynuclear aromatic hydrocarbons, phenol, and cresols to be analyzed in the same GC run. Also, the microextraction method can be used in the field to avoid delays associated with transportation of ground water samples to the laboratory.
Investigation and Remediation of Petroleum Product Releases from Residential Storage Tanks
Authors: Pearson Gary , Oudijk Gil
Published: February 2007

Releases of petroleum products from leaking residential storage tanks are a growing problem in the stale of New Jersey. Approximately two releases per day have been reported to the New Jersey Department of Environmental Protection. Product releases may cause aquifers to become contaminated, may affect surface water, or cause vapor problems inside households. As of 1992, there arc no federal or state regulations pertaining to the maintenance and monitoring of residential petroleum storage tanks. Regulations are essential for protecting drinking water supplies. The regulations must address installation procedures, lank materials, monitoring, and tank location.
Application of Electromagnetic Logging to Contamination Investigations in Glacial Sand‐and‐Gravel Aquifers
Authors: Williams John H. , Lapham Wayne W. , Barringer Thomas H.
Published: February 2007

Electromagnetic (EM) logging provides an efficient method for high‐resolution, vertical delineation of electrically conductive contamination in glacial sand‐and‐gravel aquifers. LM. gamma, and lithologic logs and specific conductance data from sand‐and‐gravel aquifers at five sites in the northeastern United States were analyzed to define the relation of KM conductivity to aquifer lithology and water quality. Municipal waste disposal, septic waste discharge, or highway deicing salt application at these sites has caused contaminant plumes in which the dissolved solids concentration and specific conductance of ground water exceed background levels by as much as 10 to 20 limes.

The major hydrogeologic factors that affected KM log response at the five sites were the dissolved solids concentration of the ground water and the silt and clay content in the aquifer. KM conductivity of sand and gravel with uncontaminated water ranged from less than 5 to about 10 millisiemens per meter (mS/m); that of silt and clay zones ranged from about 15 to 45 mS/m: and that of the more highly contaminated zones in sand and gravel ranged from about 10 to more than 80 mS/m. Specific conductance of water samples from screened intervals in sand and gravel at selected monitoring well installations was significantly correlated with KM conductivity.

CM logging can be used in glacial sand‐and‐gravel aquifer investigations to (1) determine optimum depths for the placement of monitoring well screens: (2) provide a nearly continuous vertical profile of specific conductance to complement depth‐specific water quality samples; and (3) identify temporal changes in water quality through sequential logging. Detailed lithologic or gamma logs, preferably both, need to be collected along with the F.M logs to define zones in which elevated EM conductivity is caused by the presence of sill and clay beds rather than contamination.
Detection of Contaminant Plumes by Borehole Geophysical Logging
Authors: Mack Thomas J.
Published: February 2007

Two borehole geophysical methods—electromagnetic induction and natural gamma radiation logs—were used to vertically delineate landfill leachate plumes in a glacial aquifer. Geophysical logs of monitoring wells near two land‐fills in a glacial aquifer in west‐central Vermont show that borehole geophysical methods can aid in interpretation of geologic logs and placement of monitoring well screens to sample landfill leachate plumes.

Zones of high electrical conductance were delineated from the electromagnetic log in wells near two landfills. Some of these zones were found to correlate with silt and clay units on the basis of drilling and gamma logs. Monitoring wells were screened specifically in zones of high electrical conductivity that did not correlate to a silt or clay unit. Zones of high electrical conductivity that did not correlate to a silt or clay unit were caused by the presence of ground water with a high specific conductance, generally from 1000 to 2370 μS/cm (microsiemens per centimeter at 25 degrees Celsius). Ambient ground water in the study area has a specific conductance of approximately 200 to 400 μS/cm. Landfill leachate plumes were found to be approximately 5 to 20 feet thick and to be near the water table surface.
EPA's Approach to Vadose Zone Monitoring at RCRA Facilities
Authors: Durant Neal D. , Myers Vernon B. , Eccles Lawrence A.
Published: February 2007

The U.S. Environmental Protection Agency (EPA) recently proposed to amend federal regulations to require vadose zone monitoring at certain hazardous waste facilities. To support this proposal, EPA evaluated previous policy on vadose zone monitoring and examined advances in vadose zone monitoring technology. Changes in EPA vadose zone monitoring policy were driven by demonstrated advances in the available monitoring technology and improvements in understanding of vadose zone processes/When used under the appropriate conditions, currently available direct and indirect monitoring methods can effectively detect contamination that may leak from hazardous waste facilities into the vadose zone. Direct techniques examined include soil‐core monitoring and soil‐pore liquid monitoring. Indirect techniques examined include soil‐gas monitoring, neutron moderation, complex resistivity, ground‐penetrating radar, and electrical resistivity. Properly designed vadose zone monitoring networks can act as a complement to saturated zone monitoring networks at numerous hazardous waste facilities. At certain facilities, particularly those in arid climates where the saturated zone is relatively deep, effective vadose zone monitoring may allow a reduction in the scope of saturated zone monitoring programs.
The Role of Bioattenuation in the Management of Aromatic Hydrocarbon Plumes in Aquifers
Authors: Salanitro Joseph P.
Published: February 2007

Ground water scientists have made significant advances in understanding the soil interactions, hydrogeology, fate and transport, and subsurface microbiology of aromatic hydrocarbons (BTEX) in aquifer systems. It is now generally recognized that a major factor responsible for the attenuation and mass reduction of BTEX in plumes is the widespread occurrence of hydrocarbon biodegradation by indigenous soil microorganisms in aquifer material. Most well‐studied BTEX plumes that develop from the accidental release of gasoline fuels contain low levels of soluble hydrocarbons (< 1 to 5000 ppb) and have been shown to be spatially confined because of natural biotransformation mechanisms. These in situ processes are controlled by source and aquifer characteristics, permeability, sorption, and geochemical properties of the aquifer. Many laboratory subsoil‐ground water microcosms and field studies (10 to 20 C) have demonstrated the rapid biodecay (1 to SO percent/day for microcosms and 0.5 to 1.5 percent/day for plumes) of these aromatic compounds under primarily aerobic conditions (i.e., those with sufficient dissolved oxygen). The ability to implement ground water bioremediation will depend upon our understanding of source control and aquifer recharge effects on the spatial distribution of plumes. In addition, estimating the biodegradation of sorbed BTEX, determining limits and potential for in situ biostimulation of soluble plumes, and establishing data requirements for predictive modeling of natural attenuation will be useful for this remediation technology. The use of these tools to manage ground water quality appears to represent the most practical alternative, particularly for low‐risk ground water supplies.
Hazardous Waste Remediation: A 21st Century Problem
Authors: Bredehoeft J.D.
Published: February 2007

The United Stales, both the private and the public sector, is currently spending approximately $10 billion annually on environmental cleanup. In 1991. the Waste Management Research and Educational Institute at the University of Tennessee, Knoxville completed an exhaustive study that estimated if we continue to pursue current policies the total cost of the cleanup will be approximately $750 billion — in 1990 dollars. This suggests that given current technology and the current rate of expenditure, cleanup will take 75 years ‐ well into the latter half of the next century.

The legacy of environmental problems associated with our weapons complex is enormous. The Tennessee group estimated that one‐third of the total cost of cleanup — approximately $240 billion — will be borne by the Department of Energy (DOR). Currently, approximately one‐half of the annual expenditures for cleanup conies from DOE —$5 billion, one‐third of the DOE budget.

In contrast, the amount of funds for basic research on environmental cleanup problems is small. The federal government spends less than $100 million annually for basic research — less than 1 percent of the total annual expenditure of $10 billion. This level of funding for basic research seems shortsighted given the current status of cleanup technologies and the expected long duration of the problem.
Enhanced Degradation of Dissolved Benzene and Toluene Using a Solid Oxygen‐Releasing Compound
Authors: Bianchi‐Mosquera Gino C. , Allen‐King Richelle M. , Mackay Douglas M.
Published: February 2007

A field lest to evaluate the applicability of an oxygon‐releasing compound (ORC) to the rernediation of ground water contaminated with benzone and toluene was conducted in the Borden Aquifer in Ontario. Canada. Benzene and toluene were injected as organic substrates to represent BTEX compounds, bromide was used as a tracer, and nitrate was added to avoid nitrate‐limited conditions.

The fate of the solutes was monitored along four lines of monitoring points and wells. Two lines studied the behavior of the solutes upgradient and downgradient of two large‐diameter well screens filled with briquets containing ORC and briquets without ORC. One line was used to study the solute behavior upgradient and downgradient of columns of ORC powder placed directly in the saturated zone. The remaining line was a control.

The results indicate that ORC in both briquet and powder form can release significant amounts of oxygen to conlaminated ground water passing by it. In the formulation used in this work, oxygen release persisted for at least 10 weeks. Furthemiore, the study indicates that the enhancement of the available dissolved oxygen content of at least 4 mg/L each of the ground water by ORC can support biodegradation of benzene and toluene dissolved in ground water. Such concentrations are typical of those encountered at sites contaminated with petroleum hydrocarbons; therefore, these results suggest that there is promise for ORC to enhance in situ biodegradation of BTKX contaminants at such sites using passive (nonpumping) systems to contact the contaminated ground water with the oxygen source.
A Simple Method for Measuring the Vertically of Small‐Diameter Driven Wells
Authors: Kjeldsen Peter , Skov Bent
Published: February 2007

The presence of stones, solid waste, and other obstructions can deflect small‐diameter driven wells during installation, leading to deviations of the well from its intended position. This could lead to erroneous results, especially for measurements of ground water levels by water level meters. A simple method was developed to measure deviations from the intended positions of well screens and determine correction factors required for proper measurement of ground water levels in nonvertical wells. The method is based upon measurement of the hydrostatic pressure in the bottom of a water column, which is established in the well lube. The method was used to correct water level measurement in wells driven through a landfill site. Errors of up to 27 cm in water level were observed at the landfill site. The correction of the water level measurements had a significant effect on estimated local ground water flow directions.
Characterization of Chromium‐ Contaminated Soils Using Field‐Portable X‐Ray Fluorescence
Authors: Puls Robert W. , Clark Donald A. , Carlson Clark , Vardy James
Published: February 2007

A detailed characterization of the underlying and adjacent soils near a chrome plating shop utilized field‐portable X‐ ray fluorescence (XRF) as a screening tool. XRF permitted real‐time acquisition of estimates for total metal content of soils. A trailer‐mounted soil coring unit was used to recover soil samples for XRF analyses. This approach minimized the number of samples required for adequate characterization of the chromium distribution in the soils at the site and permitted immediate delineation of source‘hot spots.’The nondestructive nature of the XRF analyses permitted correlation analysis using inductively coupled plasma (ICP) techniques. Correlation between XRF and ICP was very good (r2= 0.95) but the XRF analyses underestimated the total chromium concentrations, probably because of inappropriate calibration samples.
Considerations for the Design of In Situ Vapor Extraction Systems: Radius of Influence vs. Zone of Remediation
Authors: Johnson Paul C. , Ettinger Robert A.
Published: February 2007

When designing in situ soil vapor extraction systems, the number and placement of vapor extraction wells arc typically based on the radius of influence determined from some combination of pilot test data, theoretical considerations, and experience. In this report, we examine common methods used to determine the radius of influence, and through examples we illustrate how effective this remedial design approach is. Significant conclusions arc the following: (a) systems designed by radius of influence‐based approaches may never achieve desired remedial goals: (b) systems designed by radius of influence‐based approaches may result in longer operation times and higher total costs than a system that incorporates remedial goals and some level of fundamentally based predictive modeling: and (c) at best, the radius of influence‐based approach ensures containment of contaminant vapors.