bluuebunny/crossref_metadata_2025 huggingface dataset:
The Application of Television Borehole Logging to Ground Water Monitoring Programs
Authors: Morahan Thomas , Dorrier Richard C.
Published: February 2007

Borehole television has been successfully utilized to gather in situ information on boreholes and wells in several ground water monitoring programs. Borehole television surveys are proposed as a viable alternative to other downhole instruments in the subsurface investigation stages of a ground water monitoring program.

The borehole television camera used by the authors was originally developed for use in the examination of nuclear reactor cores; the camera has since been modified for use in borehole investigations. The lens attachments are capable of looking sideward or downward and include built‐in lighting assemblies. Use of the camera, lenses and various support equipment are discussed.

The in situ characterization of fractures that can provide pathways for contaminant migration poses a significant challenge. Borehole television inspection can provide information on the frequency, size and orientation of these fractures. Vertical correlations of rock cores in areas where voids are present (i.e. deep mining or karst topography) can also be simplified by this technique. In addition, borehole television can also be used to check monitoring well integrity. Casing inspections are especially useful where construction details are not known. Well screens may be inspected in place to determine if rusting has enlarged the screen openings or if screens have been damaged during emplacement or well development operations (i.e. surge block, air jetting, etc.). This information may prove to be very valuable in the decision to decommission a well. Examples of these successful applications in ground water monitoring programs at several Superfund hazardous waste sites are presented.
Monitoring in the Vadose and Saturated Zones Utilizing Fluoroplastic
Authors: Fishbaugh Timothy
Published: February 2007

A ground water monitoring program should include an investigation of all possible areas of concern. To be completely effective, the program should include soil sampling, soil analysis and water‐quality examination of both the saturated and unsaturated zones. A well‐tooled drill rig can take all the proper soil samples, perform all necessary tests and install a functional monitoring well. With the introduction of the fluoropolymer (Teflon(r)) sleeve lysimeter, a single monitoring well can be constructed to monitor both the saturated and unsaturated zones in one installation. The monitoring well screen and casing may also be completely constructed of fluoropolymer.

The sleeve lysimeter is designed with a threaded hollow inner diameter, allowing it to be attached between the joints of a casing string. This hollow I.D. acts as an extension of the casing; the lysimeter surrounds the casing. This creates an isolated vessel for sampling the vadose zone. Access to the screened monitoring well below is unaffected. Tests have shown that when properly installed, these porous fluoropolymer filter units can collect samples with no interaction between the filter and collected fluids.
A Computerized Ground Water Monitoring System
Authors: Way Shao‐Chih (Ted) , McKee C.R. , Wainwright H. K.
Published: February 2007

This article describes a computer automated, hydrologic analysis system designed to allow the collection of high quality, long‐term pumping test data. The instrument solves two of the major problems encountered in the field during aquifer tests: insufficient data, particularly during the early part of a test when drawdown is rapid; and high labor costs associated with long‐term monitoring.

To illustrate the system's application, results are presented from the test of a highly transmissive aquifer. The aquifer's drawdown response was rapid; thus the time‐drawdown curve was essentially flat after the first two minutes of the test, and correspondingly rapid data acquisition was essential for a unique solution of the aquifer's three‐dimensional hydraulic conductivities.
New Tape For Ground Water Measurements
Authors: Sanders Paul J.
Published: February 2007

A composite tape has been developed which can be the link to various sensing devices for measuring ground water parameters. The tape consists of a standard steel engineering tape with two conductors at the edges of the tape, similar to a TV antenna wire. The tape coating is clear Tefzel®, which has outstanding chemical and physical resistance. At the bottom end of the tape is a probe which can sense either water level by conductivity, a layer of organic liquid by an optical device, temperature by advanced semiconductor temperature transducers, pH, dissolved oxygen, absolute conductivity, or any other measurement that can be made with a small in situ probe.

The steel tape itself provides one of three conductors and, because of its thin, flat shape, provides an excellent ground plane for electronic noise reduction. A multiplexing circuit commonly used in the electronics industry is placed inside the probe tip housing and routinely allows up to 16 signals to be transmitted to the hub at ground level. Most probes can be powered with a common 9V rechargeable battery. Signals are given either by low power‐consuming light‐emitting diodes (LEDs) ∼ 5 milliamperes (mA), piezo‐audible alarms ∼ 3mA, or liquid crystal displays ∼ l‐2mA

This configuration allows for extremely accurate depth profiles of the desired parameters.
Types and Usages of Drilling Fluids Utilized to Install Monitoring Wells Associated with Metals and Radionuclide Ground Water Studies
Authors: Ericson Wayne A. , Brinkman James E. , Darr Paul S.
Published: February 2007

Evaluation for metal and radionuclide contamination associated with selected inactive uranium mill tailings repositories required the installation of monitoring wells in both shallow unconfined and deep artesian aquifer systems. To prevent ionic exchange between the dissolved cationic metals and the cations in bentonitic drilling fluids, organic‐based fluids were used during the drilling and installation of monitoring wells. Experience gained at three western U.S. sites involving inactive uranium mill tailings indicates organic drilling fluids can be used to advance drill holes in soil materials ranging from saturated silts and fine sands to unsaturated gravels. However, it has been determined that certain types of these organic fluids can clog very narrow screen slots and remain present in well discharge, even after several hours of well cleaning. Certain types of organic drilling fluids appear to be preferable for these types of water chemistry studies.
An Evaluation Technique for Ground Water Quality Beneath Urban Runoff Retention and Percolation Basins
Authors: Nightingale Harry I. , Harrison Doug , Salo John E.
Published: February 2007

A subsurface water (vadose zone or ground water) extractor is described. Construction materials were Teflon and a porous ceramic suction cup. The unique features are:

 •Check valves are not needed.

 •Complete retention of water sample in a 1.8L capacity reservoir, even if vacuum is lost or when the reservoir is pressurized to transfer sample to ground surface and the collection bottle.

 •The extractor can usually be retrieved if the access well and well head as described are used. The ceramic cup can then be replaced if necessary and the extractor reused at another site. The water extractor is not suitable for obtaining samples for analysis of highly volatile pollutants.

Up to four of these water extractors were used to monitor the quality of percolating urban runoff water and top of the ground water table (20 to 30m) beneath retention/recharge basins. The presence of water in the basins requires constructing a sealed borehole annular space, a watertight well head, and seal around the Teflon access tubes to the extractor at a control box containing the valves in the access tubes.
A Comparison of Sampling Mechanisms Available for Small‐Diameter Ground Water Monitoring Wells
Authors: Nielsen David M. , Yeates Gillian L.
Published: February 2007

The objective of most ground water quality monitoring programs is to obtain samples that are “representative” or that retain the physical and chemical properties of the ground water in an aquifer. Many factors can influence whether or not a particular sample is representative, but perhaps the most critical factor is the method or type of sampling device used to retrieve the sample.

The sampling equipment available today ranges from simple to highly sophisticated, and includes bailers, syringe devices, suction‐lift pumps, gas‐drive devices, bladder (Middelburg‐type) pumps, gear‐drive and helical rotor electric submersible pumps and gas‐driven piston pumps. New devices are continually being developed for use in small‐diameter wells in order to meet the needs of professionals engaged in implementing elaborate ground water monitoring programs.

In selecting a sampling device for a monitoring program, the professional must consider a number of details. Among the considerations are: the outside diameter of the device, the overall impact of the device on ground water sample integrity (including the materials from which the sampling device and associated equipment are made and the method by which the device delivers the sample), the capability of the device to purge the well of stagnant water, the rate and the ability to control the rate at which the sample is delivered, the depth limitations of the device, the ease of operating, cleaning and maintaining the device, the portability of the device and required accessory equipment, the reliability and durability of the device, and the initial and operational cost of the device and accessory equipment. Based on these considerations, each of the devices available for sampling ground water from small‐diameter wells has its own unique set of advantages and disadvantages that make it suitable for sampling under specific sets of conditions. No one sampling device is applicable to all sampling situations.
Geophysical Monitoring of Ground Water Contamination Around Waste Disposal Sites
Authors: Greenhouse John P. , Monier‐Williams Mark
Published: February 2007

The potential and the problems for geophysical monitoring programs at waste disposal sites are discussed. No data are presented, but the expectations, design criteria and implementation of a geophysical monitor are examined for a hypothetical landfill. We conclude that any geophysical monitor must be designed to allow for future changes in the physical setting, geophysical technology and the personnel who will record, process and interpret the data. This suggests that permanent installations be kept to a minimum, and that a high priority be given to simplicity and reliability. It is also important that the detection limits of the monitor be clearly established, that the noise levels in readings unrelated to changes in contamination levels are well defined and that the monitor is integrated into an overall hydrogeological monitoring program.
Installation of Observation Wells on Hazardous Waste Sites in Kansas Using a Hollow‐Stem Auger
Authors: Perry Charles A. , Hart Robert J.
Published: February 2007

Noncontaminating procedures were used during the hollow‐stem auger installation of 12 observation wells on three hazardous waste sites in Kansas. Special precautions were taken to ensure that water samples were representative of the ground water in the aquifer and were not subjected to contamination from the land surface or cross contamination from within borehole. Precautions included thorough cleaning of the hollow‐stem auger and casing, keeping drill cuttings from falling back into the borehole while drilling, and not adding water to the borehole. These procedures were designed to prevent contamination of the ground water during well installation.

Because the use of water during well installation could contaminate the aquifer or dilute contaminants already present in the aquifer, two methods of well installation that did not introduce outside water to the borehole were used. The first method involved using a slotted 3/4‐inch coupling that was attached to the bit plate of the hollow‐stem auger, allowing formation water to enter the auger, thereby preventing sand‐plug formation. This method proved to be adequate, except when drilling through clay layers, which tended to clog the slotted coupling. The second method involved screened well swab that allowed only formation water to enter the hollow‐stem auger and prevented sand from plugging the hollow‐stem auger when the bit plate was removed.
Flow and Containment of Injected Wastes
Authors: Miller C. , Fischer T. A. , Clark J.E. , Porter W.M. , Hales C.H. , Tilton J.R.
Published: February 2007

Proper design, construction, testing and maintenance of Class 1 (hazardous waste) injection wells can guarantee that all waste is delivered to the injection zone. To assess the effects of waste injection, analytical models were developed which predict waste movement and pressure increases within the injection zone, and describe upward permeation through confining layers.

A basic plume model was used to track waste from several injection wells with varied injection history at DuPont's Victoria Texas site. To determine the maxi‐mum distance that any portion of the waste might travel, special purpose models were employed to account for (1) density differences between the waste and the native formation brine, and (2) layered permeability variation within the injection zone. The results were generalized to a “multiplying factor concept,” which facilitates development of a worst‐case scenario.

A pressure distribution model based on the Theis (1935) equation for radial flow was applied to the Victoria site, with modifications to account for multiple wells, injection history and geological complexities.

Permeation into an intact confining layer was investigated by a new technique based on the Hantush and Jacob (1955) “leaky aquifer” theory. The model defines the maximum permeation distance, taking into account post‐injection pressure decay.

Defects within confining layers, such as faults, fractures and abandoned wells, have been considered. Studies to evaluate their detailed characteristics are continuing. Initial results indicate that faults and fractures are not likely to provide conductive pathways in Gulf Coast settings, and site‐specific evaluations are required to assess the impact of abandoned wells.
Study of Current Underground Injection Control Regulations and Practices in Illinois
Authors: Visocky Adrian P. , Nealon John S. , Brower Ross D. , Krapac Ivan G. , Hensel Bruce R. , Guthrie Mark A.
Published: February 2007

In 1984, the Illinois Department of Energy and Natural Resources was required to assess the regulations and practices of the Illinois Underground Injection Control (UIC) program as it relates to Class I hazardous waste disposal wells. Nine injection wells, including two standbys (one inactive), are currently in operation at seven sites in the state. These wells range in depth from 1540 to 5524 feet (470 to 1683m; most inject wastes into porous carbonate formations (two wells inject into a thick sandstone). In 1984, approximately 300 million gallons (1.1 billion liters) of industrial wastes were disposed of in these wells. Acids were the most common waste disposed of, although water made up 70 to 95 percent of the wastes by volume. Illinois has been granted primacy in operating this program.

The geologic environment, consisting of the unit accepting the waste and confining units lying above and below, has the capacity to accept the waste, to retain it, and to protect all underground sources of drinking water (USDW) from contamination by its injection. The geology of Illinois is relatively simple and includes disposal zones and associated confining units suitable for deep‐well injection across the central two‐thirds of the state.

The regulatory structure for Class I injection wells is generally adequate in concept and scope to ensure containment of injected wastes and to safeguard underground sources of drinking water in Illinois. There is a need to update and strengthen selected portions of the regulatory practices in the areas of waste sampling protocol, chemical analysis of collected waste samples, and evaluation of injection well testing and monitoring data.

A number of technologies exist that can treat and dispose of most hazardous and non‐hazardous waste streams. Each of these technologies has associated with it economic, environmental and societal impacts.
Operation and Maintenance of Underground Injection Wells
Authors: Buttam Jack R.
Published: February 2007

The DuPont Victoria Texas plant has gained 195 well‐years of experience in operating and maintaining underground injection wells since 1953. This experience demonstrates that it is very important to locate wells where proper geology exists for ground water protection. The well construction features and materials are equally important. Well operation at this plant features a leak detection system that continuously monitors the mechanical integrity of the wells. The evaluation of these monitoring data provides early detection of problems before the environment can be harmed. Investigation and diagnostic techniques are then used to determine the nature and exact location of problems, whether they exist at the surface or downhole in the injection tubing, packer or casing. Once the problem is defined, remedial action is instituted. Finally the success of the repair is confirmed through additional testing.

Only a limited number of repairs have been required over the past 33 years and all have been carried out without endangering the environment.
An Inexpensive Flow‐Through Cell and Measurement System for Monitoring Selected Chemical Parameters in Ground Water
Authors: Garske Edward E. , Schock Michael R.
Published: February 2007

An inexpensive flow‐through cell was designed and constructed to enable the accurate measurement of redox potential (Eh), conductivity and pH from shallow monitoring wells. The cell accepts sample water from inert gas‐operated bladder pumps. The electrodes are monitored by meters mounted in a portable rugged waterproof carrying case. The cell is useful for monitoring the purging of stagnant water from the well prior to sample collection for chemical analysis, as well as to provide pH, Eh and conductivity data under conditions as close to in situ as presently practical. In conjunction with the development of the flow‐through cell and measuring system, a portable field kit was constructed and equipped to determine the alkalinity of the water via modified Gran plot titration, immediately upon sample collection.

In addition to the measurement cell system, an in‐line membrane filtration system was developed, that included valves to sequentially switch to different filter units, in case of membrane plugging.
A Laboratory Study of Electromigration as a Possible Field Technique for the Removal of Contaminants from Ground Water
Authors: Runnells Donald D. , Larson Jay L.
Published: February 2007

A method for removing dissolved contaminants from ground water by emplacing electrodes in the aquifer has been tested using laboratory columns of pure quartz silty sand saturated with solutions of CuSO4 and copper‐contaminated synthetic ground water. In the Soviet Union a similar method is commonly used in searching for hidden deposits of metallic minerals. In the Soviet method, electrodes are emplaced in the ground and ions of the metals being sought are caused to migrate along an imposed voltage gradient; the ions are collected for analysis in acid‐filled ceramic cylinders which surround the cathodes.

In this study, quick‐freezing was used to obtain the distribution of ions within the columns as a function of time and space. With voltages up to 2.5 V and cur‐rents of a few tens of microamps, more than 50 percent of the dissolved copper was removed from the interstitial fluid in the porous columns in a period of five days. Current efficiencies ranged from more than 80 percent to less than 5 percent, depending on such factors as length of time of electrolysis, pH, concentration of Cu, and presence of other ions. The efficiency and economics of the technique of electromigration should be evaluated in additional laboratory studies and in the field, but in theory the method should be useful for removing any charged species in ground water, including some organics.
In Situ Biorestoration as a Ground Water Remediation Technique
Authors: Wilson John T , Leach Lowell E. , Henson Michael , Jones Jerry N.
Published: February 2007

In situ biorestoration, where applicable, is indicated as a potentially very cost‐effective and environmentally acceptable remediation technology. Many contaminants in solution in ground water as well as vapors in the unsaturated zone can be completely degraded or transformed into new compounds by naturally occurring indigenous microbial populations. Undoubtedly, thousands of contamination events are remediated naturally before the contamination reaches a point of detection. The need is for methodology to determine when natural biorestoration is occurring, the stage the restoration process is in, whether enhancement of the process is possible or desirable, and what will happen if natural processes are allowed to run their course.

In addition to the nature of the contaminant, several environmental factors are known to influence the capacity of indigenous microbial populations to degrade contaminants. These factors include dissolved oxygen, pH, temperature, oxidation‐reduction potential, availability of mineral nutrients, salinity, soil moisture, the concentration of specific pollutants, and the nutritional quality of dissolved organic carbon in the ground water.

Most enhanced in situ bioreclamation techniques available today are variations of hydrocarbon degradation procedures pioneered and patented by Raymond and coworkers at Suntech during the period 1974 to 1978. Nutrients and oxygen are introduced through injection wells and circulated through the contaminated zone by pumping one or more producing wells.

The limiting factor in remediation technology is getting the contaminated subsurface material to the treatment unit or units, or in the case of in situ processes, getting the treatment process to the contaminated material. The key to successful remediation is a thorough understanding of the hydrogeologic and geochemical characteristics of the contaminated area.
Factors Which Affect Soil‐Pore Liquid: A Comparison of Currently Available Samplers with Two New Desians
Authors: Hornby W.J. , Zabcik J.D. , Crawley W.
Published: February 2007

Presently available suction and free drainage soil‐pore liquid (SPL) samplers were compared with two new SPL sampler designs for use in unsaturated zone monitoring programs. Comparisons and recommendations for appropriate SPL monitoring equipment were based on factors that influence sample quality. These factors are:

The nature of the matrix being sampled

The nature of the constituent being monitored

Seasonal and site managerial influences on water movement

Site condition influence on available options for installation of monitoring equipment.
The Transiometer: An Alternative Method of Soil Moisture Measurement in Slowly Permeable Soils
Authors: Trooien Todd P. , Bender Alan R. , Bischoff John H.
Published: February 2007

The union of a piezoresistive pressure transducer and a porous ceramic cup was termed “transiometer.” The transiometer was constructed from economical and readily available materials. It could be used to measure soil water potentials in both saturated and unsaturated conditions, and was well suited to continuous monitoring with data acquisition equipment.

Transiometer testing was conducted at two sites, one of moderate permeability and the other of slow permeability. The slowly permeable site was instrumented with four replications of the following: (1) transiometers installed at four depths, (2) a transi‐ometerwithout the ceramic cup, (3) apiezometer, and (4) access tubes for monitoring soil moisture with a neutron probe. The moderately permeable site was instrumented with a transiometer, two piezometers, and an access tube for monitoring with a neutron probe.

In saturated conditions the transiometer had a faster response time after installation than the piezometer. Faster response makes the transiometer more desirable for use in slowly permeable soils, especially when monitoring dynamic soil water.

Calculated random error of the transiometer measuring system, including a digital voltmeter and a scanner, was typically 0.09 feet (2.8cm), with a maximum calculated to be 0.38 feet (11.5cm). The two most significant components were imprecision of the scanner card and calibration shift. The transiometer was sensitive to atmospheric pressure fluctuations, with sensitivity to atmospheric pressure change increasing with installation depth.
Analysis of a Contaminated Bedrock Aquifer by Means of a Packer and Attempts at Remediation Using a Packer
Authors: Hiltgen K.D. , Anderson S.E.
Published: February 2007

A dolomite bedrock aquifer in the Northeast has been contaminated with volatile organic compounds. These compounds have made their way into our pumping well, which contains total volatile organic concentrations averaging 2 to 4 ppm. The source of these organics has not been positively identified. Television video logs show considerable vertical fractures in the upper 20 feet of the bedrock aquifer. Below this, where bedrock is more consolidated, there are a few areas of caverns and large crevices, some of which are 10 feet thick. It was first thought that perhaps the organics were entering the well through a few of the crevices that could be grouted off from the remainder of the aquifer. We fabricated an inflatable packer so that isolated sections of the well could be sampled. Using the video logs as guides, the vertical sections of the well was sampled and the centerline of the plume was determined.

The packer was comprised of two steel rim supports that supported innertubes. The two packers were separated with 4 feet of steel rod. Placed on top of the lower section was a standard submersible well pump that could pump a flow rate of 10 gpm. The packer assembly was lowered into the well with a winch and then at selected locations the packer was inflated with air to 50 psig. The submersible pump was turned on and allowed to pump the section for 30 minutes to adequately purge the area and obtain a representative sample.

The results of the sampling showed the maximum concentration to be at 95 feet below the surface. The entire aquifer is 125 feet thick. This means the lower third contains the organics. To determine what vertical section supplies the most water, we divided the well into thirds, and ran a material balance using three different compounds. From the analysis, we determined that a packer placed at the 70‐foot level and only pumping from that section will reduce organics concentration by a factor of 10 and reduce flow only by 20 percent.

A commercial packer has been installed at the 70‐foot level in the well and the pump was raised above this level in hopes to reduce organics concentration in the well water. The packer is still under testing, but after four months of operation, there has been no dramatic decrease in contaminant levels. This may be the result of leakage around the packer or due to the high permeability of the dolomite aquifer.
Use of Computers in the Field
Authors: Gravengaard Gabrielle B.
Published: February 2007

Performing long‐term pump tests, single‐well aquifer tests and long‐term ground water monitoring were, in the past, considered costly and labor‐intensive tasks. However, because of recent advances in portable data acquisition systems, these field tests can be performed in a relatively cost‐effective and efficient manner. Certain data acquisition systems (DAS) have unique options available. Recently developed and commonly used computers are the Envirolab®, the Paroscientific®, and the In‐Situ®. The use of implementing DAS in ground water field studies has proved to be successful when compared to the many disadvantages of performing those tasks manually. Successful acquisition of aquifer characterization data using computerized methods is highly dependent on the implementation of proper field programming and operational procedures. In order to provide high qualify and meaningful data, the field operator must be familiar with proper equipment implementation and programming instructions. Once familiar with these procedures, the use of DAS in the field provides a cost‐effective and efficient tool for aquifer testing.
Volatilization Losses of Organics During Ground Water Sampling from Low Permeability Materials
Authors: McAlary T. A. , Barker J.F.
Published: February 2007

Volatilization biases that can affect a aground water sample before its collection from a monitoring well were evaluated in this study. Previous studies showed that volatilization losses during sampling of high permeability materials do not introduce unacceptable bias, except; for the most volatile compounds. In low permeability materials, however, ground water must normally accumulate for hours to days after flushing before a volume sufficient for sampling is available. During this period, the ground water sample is open to the atmosphere and volatilization can lower the concentration of volatile compounds in solution.

Laboratory simulations were conducted to evaluate this bias using four chlorinated, one‐ and two‐carbon compounds. Two distinct conditions of headspace exposure were investigated: (a) the water standing in the well casing, and (b) formation water entering the screen of a well that has been dewatered during purging.

Water standing in the well was depleted in volatile organics by exponential decay with a half life of about four days. Volatilization losses will be less than 10 percent if the standing time is less than about six hours. In wells that have been purged dry, volatilization losses of 10 percent are likely in as little as five minutes as the recovering formation water trickles through the headspace in the dewatered sand filter pack. Losses may reach 70 percent for recovery periods of one hour. When the sand filter pack is drained by the purging procedure, the sample should not be analyzed for volatile constituents since volatilization biases are likely to be substantial.

Conventional open system monitoring wells should be used to collect volatile organic samples only if fresh formation water can be drawn into the well with minimal turbulence and exposure to the atmosphere. One should therefore avoid drawing the water level down into the sand pack when the well is purged. Specialized sampling methods should be developed and evaluated for volatile organics where sample integrity is critical.
Field Evaluation of Well Purging Procedures
Authors: Robin M.J.L. , Gillham R. W.
Published: February 2007

In order to avoid contamination of ground water samples by stagnant water in the well bore, it is generally recommended that the well be purged prior to sampling. There is however, a divergence of opinion both on the need for purging and the best methods of purging. This paper describes detailed field tests in which non‐reactive tracers were used to examine, from a well hydraulics point of view, the need for purging and also the effectiveness of various purging procedures. Results show that in the permeable geologic materials of the test site, and for the non‐reactive tracers, the water within the screened interval will be purged by the natural flow of water through the screen, while the water above will remain stagnant. The volume of water above the screen is referred to here as one bore volume. It,is suggested that with consideration of the required sample volume, the volume of water stored in the screen, the sampling rate, and the position of the sampler intake, dedicated samplers could be used to obtain representative ground water samples without prior purging of the well.

Of the purging procedures tested, pumping from just below the air‐water interface in the well, or the method of “complete removal” of the water within the well bore were the only effective means for complete removal of the stagnant water. Using these procedures, it appeared that representative samples could be obtained with the removal of only two to three bore volumes of water.
Radon‐222 Concentration and Aquifer Lithology in North Carolina
Authors: Loomis Dana P.
Published: February 2007

The presence of the radioactive gas radon (Rn‐222) in many ground water supplies is a potentially significant source of public exposure to ionizing radiation. A wide range of radon concentrations has been measured in ground water in North Carolina, including some far in excess of national average concentrations. North Carolina is, however, geologically complex and ground water radon concentrations vary considerably among the state's aquifers. The highest average radon concentrations occur in areas underlain by granites (geometric mean 5910 pCi/l), and the lowest occur in the Atlantic Coastal Plain region (48 pCi/l). Average radon levels intermediate between these extremes are characteristic of the large areas of North Carolina underlain by gneisses, schists and metavolcanic rocks. Relative average radon concentrations in ground water from the rock types surveyed are consistent with relative abundances of uranium, the parent element of radon, in these rocks. Although other geologic and hydrologic factors also have an effect, aquifer lithology is a useful predictor of the concentration of radon in ground water. The occurrence of high radon concentrations in certain aquifer types; such as granites, shows that geologic factors should be considered in estimates of population exposure to radon, and that knowledge of aquifer geology can help to predict ground water radon concentrations in areas where field sampling has not been done.
Some Biases in Sampling Multilevel Piezometers for Volatile Organics
Authors: Barker J. F. , Patrick G. C , Lemon L. , Travis G. M.
Published: February 2007

Multilevel piezometers are cost‐effective monitoring devices for determining the three‐dimensional distribution of solutes in ground water. Construction includes flexible tubing (plastic or Teflon®). Their sampling is subject to a number of'potential biases, particularly: (1) losses of volatile organic solutes via volatilization, (2) sorption onto the flexible tubing of the piezometers, (3) leaching of organics from this tubing, and (4) collection of unrepresentative samples due to inadequate piezometer flushing. It is shown that these biases are minimal or are easily controlled in most situations.

Another source of bias has been recognized. Organic solutes present in ground water above the screened level can penetrate the flexible plastic or Teflon tubing and contaminate the sampled water being drawn through this tubing. Laboratory tests and field results indicate this transmission causes low organic contaminant concentrations to be erroneously attributed to ground water which is free of such contaminants. The transmitted organics apparently desorb from the plastic tubing during flushing of even 40 piezometer volumes.

Recognition of this transmission problem provides for a better interpretation of existing organic contaminant distribution data. Caution is advised when considering the use of these monitoring devices in organic solute contaminant studies.
Fault Controlled Hydrogeology at a Waste Pile
Authors: Keller Barry , Hoylman Edward , Chadbourne John
Published: February 2007

Geologic mapping, subsurface drilling and monitoring well data indicate the existence of a complex and irregular ground water regime in the vicinity of a cement kiln dust pile on an inactive splay of the Garlock Fault System. Artesian flow, active seeps and water levels that are substantially higher than the elevation of apparent saturated conditions encountered during drilling show that ground water flows upward in certain localized zones. Tracing of chemical indicator parameters characteristic of kiln dust leachate shows that the dust pile is not affecting the chemistry of nearby ground water.
Effects of Selected Sampling Equipment and Procedures on the Concentrations of Trichloroethylene and Related Compounds in Ground Water Samples
Authors: Pearsall Kenneth A. , Eckhardt David A. V.
Published: February 2007

Variations in concentrations of trichloroethylene and related compounds in ground water obtained from seven ground water samplers were used to compare the performance of three submersible pumps, a centrifugal pump, two peristaltic pumps, and a bailer. Two‐ and 4‐inch diameter submersible pumps and a centrifugal pump produced samples whose trichloroethylene concentrations, on the average, did not differ significantly from each other. Ground water samples collected by using a peristaltic pump and silicone tubing had significantly lower trichloroethylene concentrations than samples from the submersible pumps. Concentrations of 1,2‐dichloroethylene and trichloroethylene in ground water samples collected by using a bailer were indistinguishable from those in samples taken by a submersible pump when the concentrations were as much as 96 and 76 micrograms per liter, respectively, but were 15 and 12 percent lower when concentrations were as low as 29 and 23 micrograms per liter, respectively. Tests of different configurations of sampler placement in observation wells indicate that pump placement, rate of pumping, duration of pumping, and the uniformity of the vertical and lateral distribution of trichloroethylene in ground water near the well screen have a potentially significant influence on trichloroethylene concentrations in ground water samples and that these factors can have a greater effect than the type of sampler used.
Sampling the Chemistry of Shallow Aquifer Systems — A Case Study
Authors: Pionke H. B. , Urban J. B.
Published: February 2007

Pumped waters from 14 Pennsylvania wells, located in shallow sandstone, siltstone and shale aquifers, were continuously monitored for dissolved oxygen (D. O.), nitrate (NO3), pH, electrical conductivity (EC) and water temperature in a discharge manifold at the well head. The amount of pumping or purging required to stabilize these parameter readings varied by well site and parameter being analyzed. However, the purging required was generally greatest for D. O. and least for water temperature where: D. O. < NO3 pH < EC < water temperature. Wells located near the siltstone‐shale interface generally required far more purging than did wells located elsewhere. Although parameter stability was often achieved within purging one bore volume, the complexity, diversity, and variability in the data and these well‐ground water systems, suggest that no single purging rule is appropriate. Instead, the extent of purging required before sampling these shallow aquifers should be determined by incorporating on‐site monitoring of target or related parameters into the purging process.

From a sampling perspective, the relationship between NO3 and D. O. concentrations during purging were analyzed relative to aquifer type. For most wells located in sandstone or siltstone, NO3 concentrations remained relatively constant during purging irrespective of changes in D. O. For most wells located in shale, these two were positively and similarly correlated, suggesting that a general relationship exists.
Subsurface Venting of Vapors Emanating from Hydrocarbon Product on Ground Water
Authors: Crow Walter L. , Anderson Eric P , Minugh Edward M.
Published: February 2007

The results of an API‐sponsored pilot‐scale subsurface venting system study are presented. The purpose of this study was to evaluate the effectiveness of forced venting techniques in controlling and removing hydrocarbon vapors from a subsurface formation. Both qualitative and quantitative sampling and analytical procedures were developed to measure hydrocarbon vapors extracted from the soil. Vapor recovery and equivalent liquid product recovery rates were measured at each test cell evacuation rate.

Two identical test cells were installed. Each cell contained 16 vapor monitoring probes spaced at distances from 4 to 44 feet from a vapor extraction (vacuum) well. Each cell was also configured with two air inlet wells to allow atmospheric air to enter the subsurface formation. The vapor monitoring probes were installed at three discrete elevations above the capillary zone. In situ vapor samples were obtained periodically from these probes to measure changes in vapor concentration and composition while extracting vapors from the vacuum well at three different flow rates (18.5 scfm, 22.5 scfm and 39.8 scfm). In situ vapor samples were analyzed using a portable gas chromatograph to quantify and speciate the vapors. Vacuum levels were also measured at each vapor sampling probe and at the vacuum well.

The soil venting techniques evaluated during this study offer an alternative approach for controlling and eliminating spilled or leaked hydrocarbons from sand or gravel formations of high porosity and moderate permeability. These techniques may also be used to augment conventional liquid recovery methods. The data collected during this study will be useful in optimizing subsurface venting systems for removing and controlling hydrocarbon vapors in soil. Study results indicate pulsed venting techniques may offer a cost‐effective means of controlling or eliminating hydrocarbon vapors in soil.
Detecting Changes in Ground Water Quality at Regulated Facilities
Authors: Loftis Jim C. , Harris Jane , Montgomery Robert H.
Published: February 2007

The Resource Conservation and Recovery Act (PL 94–580) and related federal and state legislation have mandated routine monitoring of ground water quality at regulated facilities. The objective of the required monitoring activities is detection of adverse changes in ground water quality caused by the facilities.

Both failure to detect pollution and an incorrect determination of pollution can be very expensive. It is crucial, therefore, that monitoring programs be designed and operated to provide statistically sound information. It is equally important that users of ground water quality data understand the nature and limitations of information from monitoring.

To address the preceding issues, the authors present a general approach to analyzing ground water quality data in light of the stated monitoring objective. The suggested approach accounts for “natural” variation in background water quality through pairing of observations. The limitations of quarterly sampling for detecting small changes in quality over a short time frame are discussed.
A Multiple‐Packer/Standpipe System for Ground Water Monitoring in Consolidated Media
Authors: Welch S.J. , Lee D.R.
Published: February 2007

A simple system of packers and plastic standpipes has been used for sampling water and monitoring piezometric levels at four to six selected points in 2.98 inches (76mm) bedrock boreholes for up to five years. The relatively inexpensive packers held a required inflation pressure for at least four months and could be removed from the borehole when desired. The approach used is adaptable for other purposes and has been used for borehole dilution tests and vertical tracer tests.
Monitoring Dissolved Oxygen in Ground Water: Some Basic Considerations
Authors: Rose Seth , Long Austin
Published: February 2007

Dissolved oxygen (D.O.) concentration has a significant effect upon ground water quality by regulating the valence state of trace metals and by constraining the bacterial metabolism of dissolved organic species. For these reasons, the measurement of dissolved oxygen concentration should be considered essential in most water quality investigations. D.O. measurements have been frequently neglected in ground water monitoring. This is because O2 has often been assumed absent below the water table; measurement of O2, concentrations is not mandated by drinking water standards; and the redox potential has previously been considered an adequate and encompassing electrochemical measurement. Redox potentials, however, cannot adequately predict dissolved oxygen concentrations nor can D.O. concentrations be used to calculate redox potentials.

D.O. concentrations can be measured precisely in the field by titration or electrode methods. The best methods of sample recovery are those that use positive pressure displacement devices. A fully adequate sampling procedure will isolate ground water from the atmosphere and will collect samples at restricted depth intervals at ambient temperature and pressure.
The Representativeness of Pore Water Samples Collected from the Unsaturated Zone Using Pressure‐Vacuum Lysimeters
Authors: Peters Charles A. , Healy Richard W
Published: February 2007

Pressure‐vacuum lysimeters are an inexpensive means of collecting numerous water samples from the same location in the unsaturated zone over a period of time. However, prior studies have indicated that the chemistry of water samples may be altered by the collection technique, creating concern about the representativeness of the pore water samples obtained. A study conducted using soil water pressure‐vacuum lysimeters in outwash sand and glacial till deposits demonstrates that for non‐dilute‐solution samples the effect on pH of sampling with lysimeters is minimal, and that measured major cation and anion concentrations are representative of the natural pore water; trace‐metal concentrations can be significantly altered by collection procedures at low concentrations.
Making the Most of Field‐Measurable Ground Water Quality Parameters
Authors: Garner Stuart
Published: February 2007

The primary ground water quality parameters temperature, pH, Eh, electrical conductivity, and dissolved oxygen must be measured in the field, though not necessarily in situ, to avoid errors caused by contamination such as aeration. These measurements, when made during the purging of a well, can be used to verify aquifer‐representativeness of a sample, detect abnormalities within an aquifer, check laboratory measurements to detect sample deterioration, and prompt further monitoring actions.

Electronic sensors are available for reliable field measurement of the primary parameters. Measurements should be made continuously in an in‐line flow cell that is sealed from the atmosphere. Flow can be provided by a bladder pump dedicated to a single well. Samples for laboratory analysis should be collected when the values of the primary parameters do not vary more than 10 percent per casing volume pumped.
Contamination of Farmstead Wells by Pesticides, Volatile Organics, and Inorganic Chemicals in Kansas
Authors: Steichen James , Koelliker James , Grosh Doris , Heiman Alan , Yearout Robert , Robbins Victor
Published: February 2007

Concern about the public health consequences of possible contamination of farmstead wells led to a random statewide survey in Kansas. Results of the analyses showed that 8 percent of tested wells had detectable amounts of pesticides, 2 percent had detectable amounts of volatile organic chemicals, and 37 percent had some inorganic contaminant exceeding the maximum contaminant level (MCL). Nitrate was the most common source of inorganic contamination, exceeding the MCL in 28 percent of the wells. Selenium levels exceeded the MCL in 9 percent of the wells. A multiple regression model for nitrate‐N was developed. The factors included the age of the well, land use around the well, and the distance to the closest possible source of organic contamination.