bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of a Mathematical Model to Estimate Water Levelsa
Authors: Tasker Gary D. , Guswa John H.
Published: July 2006

A mathematical model for estimating daily water levels from less than daily observations was used to analyze an existing water‐level observation network on Cape Cod, Massachusetts. The model assumes that the water‐level fluctuation curve can be approximated by a simple harmonic function of the form: wl(x)=M+A cos(2π/T×+ C) + Bx where wl(x) is the water level for day number x. M, A, C and B are constants, and T is the harmonic period.

The analysis indicated that for those sites which are not affected by tidal fluctuations or man‐made influences (such as pumping), six water‐level measurements per year would allow daily water levels to be interpolated with a standard error of estimate of about 0.06 meters.
The Use of Temperature Logs to Trace the Movement of Injected Water
Authors: Keys W. S. , Brown R. F.
Published: July 2006

Temperature logs were used to study the movement of water injected into wells penetrating the Pliocene Ogallala Formation in the High Plains of Texas. Descriptions of the results of three recharge tests are necessary because the hydrologic response to recharge at each site was very different. The water used for artificial recharge of the aquifer was derived from playa lakes in which the diurnal fluctuation of temperature was as much as 17 ° Celsius. Daily thermal cycles that resulted from injection of this water were traced through the aquifer by use of a series of temperature logs made at frequent intervals in cased holes specially constructed for logging. The thermal pulses were detected by logging holes as far as 46 meters (150 ft) from the recharge well.

In areas where this technique was used, the Ogallala Formation consists of thick sections of uniform medium‐grained sand that visually appear uniform and thus were thought to have uniform hydraulic conductivity. However, the results of temperature logging at each of the three sites clearly demonstrate that the hydraulic conductivity varies greatly through these seemingly uniform lithologic units. Thermal pulse velocities as high as 4.6 meters (15 ft) per hour were found in thin zones immediately adjacent to sand where velocities were a few feet per day. Tracing with temperature logs is potentially useful in locating zones of high intrinsic permeability and in detecting apparent changes in rate of flow as a function of time.
Nitrate, Chloride and Dissolved Solids, Ogallala Aquifer, West Texasa
Authors: Reeves C. C. , Miller W. D.
Published: July 2006

The distribution of nitrate, chloride and dissolved solids from ground water from the Ogallala aquifer in a 27‐county area of west Texas illustrates widespread areas of poor water quality. Elements studied increased in concentration from northwest to southeast across the Southern High Plains. Northeast of a line from about Clovis, New Mexico to Lubbock, Texas, nitrate tends to be <45 mg/l, chloride is <20 mg/l, and dissolved solids are <400 mg/l. However, southwest of this line nitrate may exceed 60 mg/l and in some areas exceeds 170 mg/l. Chloride commonly exceeds 500 mg/l and may be >2000 mg/l, and dissolved solids usually exceed 1000 mg/l and may be >8000 mg/l. Regional distribution may be the result of long‐term migration of Ogallala ground water but the present water quality and distribution, as well as time, distance, stratigraphy and permeability, suggest contamination of Ogallala ground water by vertical rather than lateral migration. Most of the high nitrate values (>45 mg/l) occur in areas having sandy soils which have been intensively cultivated, thus leaching of nitrogen‐based fertilizers is suspect. However, the high chloride and dissolved solids, which exist in essentially the same geographic area, probably represent vertical to local lateral seepage of saline water from large alkali lake basins and local vertical migration from saline Cretaceous aquifers.
Interpretation of Hydrochemical Facies by Factor Analysis
Authors: Dalton Matthew G. , Upchurch Sam B.
Published: July 2006

Hydrochemical facies interpretations are useful tools for determining the flow patterns, origins, and chemical histories of ground‐water masses. Factor analysis is advantageous for hydrochemical interpretations because it is independent of the number or type of variables used. Factor analysis also allows avoidance of problems of closed‐number systems inherent in more traditional techniques, such as trilinear diagrams. This paper applies factor analysis to the interpretation of mixing between sulfate and bicarbonate ground‐water masses. Whereas trilinear diagrams show one mixing trend (bicarbonate with sulfate waters), factor analysis allows interpretation of multiple mixing trends. These trends include the bicarbonate‐sulfate trend; a sodium‐, silica‐, fluoride‐, and temperature‐mixing system that is interpreted as resulting from recharge; and a chloride‐sodium system that appears to represent mixing with residual, connate water. The latter trends are identified as small‐scale, chemical variations that result in dispersion of the data points about the dominant mixing trend on the trilinear diagram. Thus, factor analysis provides greater precision in identifying hydrochemical facies and interpreting their origins.
Comprehensive Analysis of Water‐Table Aquifer Test Data
Authors: Walton William C.
Published: July 2006

Flow to wells in water‐table aquifers is related to anisotropy, vertical components of flow, well storage capacity, degree of well penetration, and changes in aquifer saturated thickness. The manner and extent to which these factors affect water levels may be evaluated with aquifer test data. Families of type curves describe the typical S‐shaped curves of log drawdown versus log time observed around wells in water‐table aquifers. Comprehensive analysis of water‐table aquifer test data is possible with the array of equations derived largely in the late 195O's to 1970's. Erroneous data analysis will result unless complicating factors are fully recognized and taken into account. This paper reviews existing methods which the author accepts and recommends for ground‐water investigator use.
A Multilevel Device for Ground‐Water Sampling and Piezometric Monitoring
Authors: Pickens J. F. , Cherry J. A. , Grisak G. E. , Merritt W. F. , Risto B. A.
Published: July 2006

A simple inexpensive device for sample collection and for monitoring of ground‐water potential at many levels from a single borehole installation has been developed. The device consists of a bundle of polypropylene tubes contained inside a polyvinyl chloride (PVC) pipe that is installed in the aquifer. Each tube protrudes through the wall of the pipe at a different elevation where it serves as a point water sampler and piezometer. The tip of each tube is encased in fine‐meshed stainless‐steel screening. The device is best suited for use in cohesionless deposits and where the piezometric levels are close enough to ground surface to enable samples to be obtained by suction methods. It can be conveniently installed using a hollow‐stem auger, driven casing or wash‐boring methods. The usefulness of this multilevel sampling device has been demonstrated in detailed monitoring of a leachate plume from a sanitary landfill.
Use of Baker's Yeast to Trace Microbial Movement in Ground Water
Authors: Wood Warren W. , Ehrlich Garry G.
Published: July 2006

Field and laboratory tests were made using suspensions of baker's yeast (Saccharomyces cerevisiae) to trace movement of microbes in artificially recharged ground water. Yeast cells penetrated more than 7 meters into a sand and gravel aquifer in less than 48 hours. It is believed that most of the cells travelled through channels formed by the solution of calcium carbonate rather than through intergranular pores. Ease and sensitivity of detection, coupled with negligible background correction, suggest that baker's yeast is an excellent choice as a tracer for this type of application.
N15/N14 Ratios of Ground‐Water Nitrate, Long Island, New Yorka
Authors: Kreitler Charles W. , Ragone Stephen E. , Katz Brian G.
Published: July 2006

Nitrogen‐isotope values (δN15) of ground‐water nitrate on Long Island, New York, correlate with δN15 ranges of nitrate sources which contribute to the ground‐water systems. The δN15 of nitrate in water from the upper glacial aquifer, the water‐table aquifer on Long Island, shows a shift from lighter values in the eastern part of the island where land is used predominantly for agriculture, to heavier values toward New York City where land is used for suburban residences with septic systems or sewers. δN15 values for inorganic fertilizer, unfertilized cultivated fields, and animal wastes show a similar shift from low to high values: −3 ‰ to +2 ‰+ 2 ‰ to + 8 ‰ and +10 ‰ to +20 ‰, respectively.

Nitrogen‐isotope ratios of nitrate in water from the deeper Magothy aquifer indicate a mixed source of nitrate.
Transient Spherical Flow to a Nonpenetrating Well with Constant Drawdowna
Authors: Jaiswal C. S. , Chauhan H. S.
Published: July 2006

The analysis of flow to a flowing nonpenetrating well in a leaky artesian aquifer was obtained. A method has been suggested to determine the aquifer parameters using the pump‐test data on such wells with constant drawdown in the well. A technique is also suggested to determine the aquifer parameters using the well itself as the observation well.
Ground‐Water Quality Standards — Irrelevanta
Authors: Rayner Frank A.
Published: July 2006

Proposals to establish national ground‐water quality standards appear to be premature, and redundant because of the geohydrologic and geochemical factors governing the occurrence and development of ground water. Although it can be reasoned that there is no “good time” to establish additional governmental standards (and the resultant additional governmental regulations), it can also be strongly argued that now is a “bad time” to consider establishment of the proposed standards.

First, a present mood of the general public is away from more governmental involvement in the business and private sectors, and a rebellion against the increasing cost of government. Second, the applicability and workability of present Federal (and some State) laws that could be used to adequately protect ground‐water quality, have yet to be implemented or otherwise sufficiently tested.

The full force and effect of the Water Pollution Control Act (PL 92‐500 with amendments) has yet to be implemented, and Congress is still considering its “oversights” in their drafting of same.

The Safe Drinking Water Act (PL 93‐523), particularly those sections designed or usable to protect ground‐water quality, have yet to be tested by the EPA. Like PL 92‐500, the deadline for implementation of parts of PL 93‐523 has long since passed.

And the far‐reaching effects on ground‐water quality protection that three other federal laws‐the Resource Conservation Recovery Act (PL 94‐580); the Toxic Substances Control Act (PL 94‐469); and Surface Mining Control and Reclamation Act (PL 95‐87)—are totally unknown, since the procedures for full implementation of these acts have yet to be developed.

Therefore, it appears that establishing a new ground‐water quality control act prior to testing existing law and thereby learning from their flaws or shortcomings, could result in unnecessary proliferation of law without its reasonable testing.

This appears to be good time to interrupt the geometric progression that tends to spawn additional laws when laws are developed ahead of their established need.

Equitable and workable ground‐water quality protection could be fostered through the enactment of the long overdue requirements for the integration of surface‐and ground‐water development and management structures. This integration would decrease inefficiency of use of these water resources—which are actually inseparable in identity to their users, the American taxpayers.
Land Application of Waste — State of the Arta
Authors: Wright Kenneth R. , Rovey Catherine Kraeger
Published: July 2006

Land application of treated waste water can provide unique opportunities, not only for a final high level of waste‐water treatment but for reuse of nutrients as well. Recent laws passed by Congress have made it necessary to consider land treatment when planning and designing new waste‐water treatment facilities. The three types of land treatment commonly used are (1) irrigation, (2) overland flow, and (3) rapid infiltration. Selection of the most appropriate type of land treatment for a specific site is based on several considerations, including soil conditions, geology, topography, proximity to surface and subsurface water, and climate.

Ensuring the protection of ground water is essential when siting or designing a land treatment system. Ground water is an important natural resource, having considerable impact on human life and well‐being as well as high economic value. Safeguarding this important resource from contamination includes careful site selection, appropriate pretreatment of waste water prior to its application, and a program of regularly scheduled monitoring to ensure that the waste water is being properly renovated for safe release to the environment.

Utilization of municipal sludge on land for agricultural production is encouraged by federal law, as is land treatment of waste water. Sludge contains concentrated wastes, and there are practical limitations on the levels of heavy metals, salts, and toxic substances in sludges applied to agricultural lands. Sludge is generally stabilized before being applied, to destroy pathogens, and reduce weight, volume and odor.

Several case studies of successful land treatment systems presently in operation are presented to demonstrate the viability of the land treatment concept.
Land Application of Waste — An Accident Waiting to Happena
Authors: Johnson Charles C.
Published: July 2006

Half the population depends on ground water for domestic uses. Use is increasing 25 percent per decade. Ground water is generally used with little or no treatment.

Some persons would transfer the discharge of our waste products from contaminated surface streams to the land and thus relatively clean ground waters.

No standards exist that protect ground‐water quality. Research necessary to give assurance that natural interaction of waste water and soils will remove, to acceptable levels, potentially harmful contaminants, organic and inorganic, that permeate today's waste streams and today's health concerns, has not been done.

Success reports on land treatment of waste water have a not evaluated deterioration of ground water from organic contamination. Most waste waters contain synthetic organics in varying concentrations. EPA recommends their reduction in drinking water to the lowest possible level.

Most instances of ground‐water contamination have been discovered after drinking water is contaminated. Unless the public is willing to treat ground water as it does water from surface streams, greater control of land disposal practices must be exercised. Current practice does not indicate the necessary controls are contemplated or recognized. It follows that the widespread use of the land treatment alternative is, in reality, an accident waiting to happen.
The 208 Planning Approach to Ground‐Water Protection — What Is Wrong and What Can Be Done About It?a
Authors: Schmidt Kenneth D.
Published: July 2006

Generally, the 208 planning approach is deficient in a number of ways. Its origin lies in Public Law 92‐500, which focuses on protection of surface water and special uses of water for fish, wildlife, and recreation. Little ground water is used for these purposes. Nonpoint sources have not been defined in terms that have hydrogeologic significance. Local and State regulatory agencies have often been unsuccessful in controlling ground‐water pollution, yet the 208 approach tends to disregard the reasons for this situation. The reasons for ground‐water pollution in an area must be understood before meaningful control measures can be enacted. These include both technical and institutional problems.

Planners are placed in the forefront of many 208 programs at the local level and often their backgrounds are inadequate in ground water. There is a great lack of ground‐water professionals in regulatory agencies involved, particularly in the Southwest. This deficiency is paramount at high levels and in many regional offices of EPA. There are no provisions in the approach to insure that qualified ground‐water geologists or hydrologists will be involved. Academic training in ground water is presently oriented toward ground‐water development and not pollution. Lastly, public participation is greatly limited by the general lack of knowledge regarding ground water and its pollution.

Successful 208 programs in terms of ground water have been enacted when ground‐water professionals have had major roles. Changes are necessary in the academic training of ground‐water geologists and hydrologists. The public must be educated concerning the long‐term consequences of ground‐water pollution. Lastly, ground‐water professionals must assume the leadership in ground‐water protection.
Evaluation of Nitrate in the Ground War in the Delaware Coastal Plain
Authors: Robertson Frederick N.
Published: July 2006

Data from over 800 well samples collected and analyzed during a study of ground‐water quality in Sussex County, Delaware revealed that the water‐table aquifer contains excessively high concentrations of nitrate in several areas. Over 20 percent of the wells sampled contained concentrations that exceeded 45 milligrams per liter (mg/l), and in many areas, over 50 percent of the wells sampled exceeded 45 mg/l.

Sussex County is part of the Atlantic Coastal Plain Province, geologically consisting of a series of unconsolidated sands, gravels, silts, and clays that contain extensive ground‐water reserves of generally high quality. On the basis of iron and nitrate concentrations, two major areas of differing water quality were delineated: one in which the ground water contained variable concentrations of nitrate with low concentrations of iron (<0.2 mg/l), and another in which it contained large concentrations of iron (>2.0 mg/l) and little detectable nitrate.

Nitrate concentrations ranged from zero to 224 mg/l; average and median values determined for the area of nitrate occurrence were 33.9 mg/l and 25 mg/l respectively. Treatment of the nitrate data allowed depicting of 19 areas of possible excessive nitrate contamination. Nitrate occurrences were closely related to land use, soil permeability, water‐table depths and aquifer chemistry. The greatest incidence of high nitrate concentrations was associated with confined feeding operations. Other nitrate sources are septic tank effluent, natural and chemical fertilizers, foliage in forests, and precipitation.
Spring Discharge in Relation to Rapid Fissure Flow
Authors: Smith Edward John
Published: July 2006

Rapid fissure flow has been recognised as an important factor in understanding the hydraulic behaviour of the Lincolnshire Limestone aquifer of eastern England. A study of the hydrogeology of a Lincolnshire Limestone spring‐fed catchment enables three zones of discharge to be defined, based on their relative elevation along the valley floor. Comparison of the discharge characteristics of each zone reveals the existence of rapid ground‐water flow associated with a discrete fissure system. Comparison of spring discharges and ground‐water storage during a period of “high,”“low” and “typical” recharge enables a conceptual flow model of the aquifer to be constructed. A two‐layered model is proposed, in which the secondary zone (upper unit) is characterised by higher transmissivity and lower storativity than the primary zone (lower unit). In addition, there is evidence of a rapid increase in transmissivity with water‐table elevation in the secondary zone. The areal distribution of the secondary zone is associated with a net work dry valleys. The spatial distribution of the two zones is explained by geological structure, lithological variations and the post‐glacial history of the area. A two‐layered model is developed with these concepts in mind in order to simulate the spring discharges. Once proven, the model can be integreated with the regional hydrogeology and incorporated into existing digital models of the aquifer.
Hydrogeological Processes and Chemical Reactions at a Landfill
Authors: Baedecker Mary Jo , Back William
Published: July 2006

Chemical and isotopic analyses were made of water from wells in and downgradient from a landfill to determine chemical and isotopic effects of generation and migration of leachate on ground water. The distribution and wide concentration range of oxygen and methane permit the delineation of an anaerobic zone, a regional oxygenated zone and an intermediate zone. The ratio of reduced nitrogen to nitrate indicates location of reducing fronts as the leachate migrates. The pH of the native ground water is low (≥5.0) primarily because of the low pH of rainfall and the lack of calcareous or other soluble minerals in the aquifer material. The pH is higher (∼6.6) in the leachate because of generation of carbon dioxide, ammonia, and methane. The native ground water has a low TDS (80 mg/l) while the leachate has an average TDS of 2800 mg/l and is primarily a NaHCO3 type water. Sulfate concentrations are extremely low and H2S was not detected.

We suggest that a major source of cations may be their exchange from the clays by the ammonium generated in the leachate. High concentrations of Fe and Mn are attributed to a source in the refuse but more important to reduction of oxide cements and coatings resulting from degradation of organic matter. The main source of bicarbonate is from organic degradation with minimal CO2 from the soil zone. At one landfill site 52% of the total alkalinity is attributed to organic compounds, mainly organic acid anions. The δ13C of bicarbonate in the leachate is exceedingly heavy (+18.400/00) which results from fractionation during the formation of methane. The 10 per mil deuterium enrichment of water may be due to decomposition of deuterium‐enriched compounds and bacterial processes that preferentially consume the lighter hydrogen isotope.
The Application of a Digital Model for Evaluating the Bedrock Water Resources of the Maumee River Basin, Northwestern Ohioa
Authors: Naymik Thomas G.
Published: July 2006

Increasing population and industrial development in northwestern Ohio indicated the need for an evaluation of the bedrock ground‐water resources of the region. A digital ground‐water model was designed and used as a tool for predicting water‐level declines resulting from projected ground‐water withdrawal. Potentiometric surfaces, keyed to historic, accelerated, and peak projected ground‐water withdrawals, were predicted by decades to the year 2036. These withdrawals at the calculated rates will cause severe overdrafts at Lima, Toledo, and Findlay, Ohio, and at Ft. Wayne, Indiana, by the year 2036.
Electric Analog Model Study of Aquifer in Krishni‐Hindon Interstream Region, U.P., India
Authors: Gupta C. P. , Thangarajan M. , Rao V.V.S. Gurunadha
Published: July 2006

Overexploitation of ground water in Krishni‐Hindon interstream region (Lat. 29°05′N–29°29′N and Long. 77°19′E–77°32′E) in Uttar Pradesh, India, prompted us to carry out aquifer modeling studies. The area lies in Gangetic alluvial plain. The interconnections in the phreatic aquifer and the lower semiconfined aquifer led to the assumption of a single‐story aquifer for which an R‐C analog model was constructed.

The input‐output quantities in the model have been simulated using current/voltage generators and current sinks which are appropriately programmed in time‐domain with the help of wave‐form synthesizers for a realistic representation of the field system.

The model study shows that the aquifer can sustain the present output rate of 200 mcm/year without much damage to the ground‐water regime. In another scheme, an annual increase of 5% in exploitation rate, shows deleterious effects on the aquifer. Decreased rainfall/droughts would worsen the situation.

The influence of hydraulic connectivity between the aquifer and the Krishni‐Hindon river system is quite significant. If the present exploitation rate were to continue for 20 years, the annual inflow to the aquifer from rivers is estimated to increase by about 36.0 mcm.

More hydrogeological data is required for further validation and refinement of the model.
Programmable Hand Calculator Programs for Pumping and Injection Wells: I — Constant or Variable Pumping (Injection) Rate, Single or Multiple Fully Penetrating Wells
Authors: Warner Don L. , Yow M. Gene
Published: July 2006

Small programmable calculators have recently become available that will allow many routine pumping or injection well calculations to be made rapidly, accurately and inexpensively. Programs and example calculations are given for the exponential integral and multiple well‐multiple rate pumping or injection well equations using water well and oilfield units. The programs are for the TI 59 card programmable calculator.
A Simplified Statistical Sequence Applied to Routine Water Quality Analysis: A Case History
Authors: Alther George A.
Published: July 2006

A sequence of simple statistical tests was used to interpret the data from a routine water sampling project for a stream that was contaminated with effluent from a sewage treatment plant. The contamination of this stream was apparent from the murky condition of the water and its pungent odor. The outlet of the sewage treatment plant enters the stream at its origin.

The chemical variables analysed were Ca, Mg, Na, K, Cl, nitrates, TDS, and hardness. Background data from other streams in this drainage basin and data from the stream under investigation were subjected to cluster analysis in order to classify the sampled area into geochemical provinces. The contaminated stream under investigation comprised one province and the background streams constituted another province. A linear regression performed on the data showed a statistically significant decrease of several variables with increasing distance from the outlet of the sewage treatment plant. An abrupt decrease in concentration of iron some 450 m below the plant outlet implied the presence of two populations with different means, which was statistically verified with a trimmed t‐test.

Use of these simple tests greatly facilitated interpretation of the data.
Chemical Changes in an Industrial Waste Liquid During Post‐Injection Movement in a Limestone Aquifer, Pensacola, Florida
Authors: Ehrlich G. G. , Godsy E. M. , Pascale C. A. , Vecchioli John
Published: July 2006

An industrial waste liquid containing organonitrile compounds and nitrate ion has been injected into the lower limestone of the Floridan aquifer near Pensacola, Florida since June 1975. Chemical analyses of water from monitor wells and backflow from the injection well indicate that organic carbon compounds are converted to CO2 and nitrate is converted to N2. These transformations are caused by bacteria immediately after injection, and are virtually completed within 100 m of the injection well. The zone near the injection well behaves like an anaerobic filter with nitrate respiring bacteria dominating the microbial flora in this zone.

Sodium thiocyanate contained in the waste is unaltered during passage through the injection zone and is used to detect the degree of mixing of injected waste liquid with native water at a monitor well 312 m (712 ft) from the injection well. The dispersivity of the injection zone was calculated to be 10 m (33 ft). Analyses of samples from the monitor well indicate 80 percent reduction in chemical oxygen demand and virtually complete loss of organonitriles and nitrate from the waste liquid during passage from the injection well to the monitor well. Bacterial densities were much lower at the monitor well than in backflow from the injection well.
Theis Parameter Evaluation from Pumping Tests by Sensitivity Analysis
Authors: McElwee Carl D.
Published: July 2006

Through the years the Theis equation has played an important role in ground‐water hydrology. Comparison of experimental pumping‐test data with this theoretical curve by graphic means has been a standard method of determining aquifer transmissivity and storage. The purpose of this paper is to present a technique and an algorithm to automatically fit experimental pumping‐test data to the Theis equation by obtaining the “best” transmissivity and storage in the least squares sense through the use of sensitivity analysis. The automated fit for pumping‐test data developed in this work should be a useful tool for the ground‐water hydrologist. Use of the technique is simple, quick, and inexpensive, and has the advantage of always being objective. As a measure of the error in fitting, the rms deviation in drawdown is calculated for the “best” transmissivity and storage.
Programmable Hand Calculator Programs for Pumping and Injection Wells: II — Constant Pumping (Injection) Rate, Single Fully Penetrating Well, Semiconfined Aquifer
Authors: Warner Don L. , Yow M. Gene
Published: July 2006

Programmable calculator programs have been previously given for the calculation of head or pressure change resulting from the pumping from or injection into wells completely penetrating a fully confined aquifer. Programs are documented and example calculations shown here for wells completely penetrating a semiconfined aquifer. The programs are for the TI 59 card programmable calculator.
Aquifer Occurrence in the Fort Payne Formationab
Authors: Moran Mary S.
Published: July 2006

The Fort Payne Formation of Early Mississippian (Osagean) age crops out over extensive areas of central Tennessee, south‐central Kentucky, and northern Alabama. Specific formation lithologies are known to have been modified locally through weathering into an artesian aquifer along the Eastern Highland Rim of central Tennessee. The shallow aquifer can be divided into two parts; uppermost is a highly permeable chert gravel zone that is in hydraulic communication with a lower zone of interconnected solution cavities within bedrock. The gravel, at depths as great as 24.4 m (80 ft), fines upward into the clay‐sized chert of the upper confining bed. The lower confining bed is the Chattanooga Shale of Late Devonian to Early Mississippian age.

Field and petrographic studies of the Fort Payne Formation indicate that the aquifer has developed near the base of the unit. The chert gravel portion of the aquifer has developed from silicified dolowackestones of the Beaver Creek Limestone Member and from interbedded Fort Payne dolostones. The lower portion of the aquifer occurs within preferentially weathered, silicified and non‐silicified dolosiltstone.
Ground‐Water Modeling: Mathematical Modelsa
Authors: Mercer James W. , Faust Charles R.
Published: July 2006

Ground‐water modeling begins with a conceptual understanding of the physical problem. The next step in modeling is translating the physical system into mathematical terms. In general, the final results are the familiar ground‐water flow equation and transport equations. These equations, however, are often simplified, using site‐specific assumptions, to form a variety of equation subsets. An understanding of these equations and their associated boundary and initial conditions is necessary before a modeling problem can be formulated.
Trace‐Organics Biodegradation in Aquifer Recharge
Authors: Rittmann Bruce E. , McCarty Perry L. , Roberts Paul V.
Published: July 2006

The low organic concentration and high specific surface area that characterize ground‐water recharge environments allow biofilms to predominate microbial kinetics. Consideration of the kinetics of substrate utilization and growth of biofilms indicates that microbiological activity occurs very near the injection well. The aggregate substrate expressed, for example, as chemical oxygen demand, can be considered the primary substrate; the biofilm's growth is supported through the utilization of the aggregate primary substrate. Individual trace organic compounds, none of which could support biofilm growth alone, are utilized as secondary substrates. Although biodegradable, secondary substrates that have slow utilization kinetics will pass through the biologically active zone undegraded. Field data from the ground‐water recharge project in Palo Alto, California, illustrate that naphthalene and heptaldehyde are biodegraded, while other compounds, such as chloroform and chlorobenzene, pass through the biologically active zone without biodegradation.
The Role of Ground Water in Stream Discharges from Two Small Wetland Controlled Basins in Eastern Massachusetts
Authors: O'Brien Arnold L.
Published: July 2006

Ground‐water discharge was found to be the primary cause of flood peaks generated at two small wetland controlled basins in eastern Massachusetts. Within the wetlands, ground water rose rapidly following precipitation and in near synchronization with stream levels indicating a close coupling between ground water and the stream. Stream hydrographs were separated into baseflow and surface runoff by a dynamic technique which matches the hydrograph of an index well with the stream hydrograph to determine the moment of maximum ground‐water discharge. Hydrograph analysis showed that for both wetlands ground water was the major component of all flood peaks and accounted for approximately 93% of the total annual discharge.
Simulation of Salt‐Water Interface Motion
Authors: Mercer James W. , Larson Steven P. , Faust Charles R.
Published: July 2006

A numerical model is presented that solves the partial differential equations describing the motion of salt water and fresh water separated by a sharp interface. The areal equations are based on the Dupuit approximation and are obtained from partial integration over the vertical dimension. Finite‐difference techniques are applied and the utility of several solution schemes is tested. The most efficient and accurate solution scheme uses block line‐successive over‐relaxation. Examples are given to: (1) test the model, (2) evaluate the Dupuit approximation, and (3) demonstrate the application to a field situation. The results show that the model is in good agreement with an analytical solution, but under severe conditions the Dupuit approximation may be inappropriate. The model is applied to a field area near Kahului, Maui, Hawaii and results extend the analysis of the problem beyond previous efforts.
A Nitrogen Powered Continuous Delivery, All‐Glass‐Teflon Pumping System for Ground‐Water Sampling from Below 10 Meters
Authors: Tomson M. B. , Hutchinsa Steve , Kingb Joe M. , Warda C. H.
Published: July 2006

A nitrogen powered, all‐glass‐Teflon, continuous delivery, noncontaminating pump system is described. Continuous flow rates up to 45 gal‐hr‐1 (2.84 1‐sec‐1) are obtainable. The system was developed and field tested to sample water wells with static heads greater than 32 ft (10 m) for measurements of trace level organics. The system is equally applicable to environments such as marine, lake, and other unconfined water or fluid systems. Also, the analysis can be extended to inorganic and microbial assays in that the sample obtained is unaltered with respect to chemical, physical, and biological properties.
Investigation of Organic Contamination of Ground Water in South Brunswick Township, New Jersey
Authors: Roux Paul H. , Althoff William F.
Published: July 2006

Analyses of several hundred ground‐water samples from over 100 wells, and water table elevations measured in about 60 wells were used to determine the sources, distribution and movement of organohalide contaminants within two unconsolidated aquifers in South Brunswick Township, New Jersey. 1,1,1‐trichloroethane and other organic contaminants were found to have migrated more than 3,000 feet from one source to a public supply well. Lithologic logs from existing wells and monitor wells drilled for the investigation indicate that the Old Bridge aquifer, used for domestic supplies, is underlain by a clay aquitard (Woodbridge clay?) which in turn is underlain by the Farrington sand, a very productive and heavily pumped aquifer used for public supply. Well logs and water elevations were used to define the existence and location of a breach or window in the clay formation. This feature recharges the deeper aquifer and has allowed organic contaminants to reach the Farrington after contaminating wells screened in the upper unit. A large‐capacity well has been contaminated as a result. Water table altitudes were used to show the possible existence of a second breach in the clay layer that may allow organics to reach a second public supply well screened in the lower aquifer within the next few years.
Aquifer Response in the Ultramafic Field Area of Sukhinda Valley — Orissa (India)
Authors: Radhakrishna I. , Venkateswarlu T.
Published: July 2006

Analysis of a long‐duration aquifer performance test utilizing a well near Kansa in the Sukhinda ultramafic body of the Cuttack District in Orissa has demonstrated that nonequilibrium formulae can be applied to hard‐rock regions depending upon the stage of hydrogeological regime and the vertical leakage in the system. Graphical analysis of test results under nonsteady and steady‐state conditions have helped in understanding the behavior of aquifers and their characteristics. A comparative examination of results obtained by different methods and careful insight has helped in delineating the boundary conditions, long‐term withdrawal effects and well spacing problems in the present area, and this approach could be applied in similar well fields.
Ground‐Water Information: NWWA Provides the Resources
Authors: Poland Jean
Published: July 2006

As the volume of hydrogeologic literature increases, researchers are finding it more difficult to identify and locate information. The National Water Well Association's Library/Information Center is a central source of ground‐water information. In addition to collecting books, journals, and reports relevant to ground‐water research, the Library/ Information Center conducts both manual and computer literature searches. A bibliographic data base of hydro‐geologic references is in development.
Hydraulic Properties of Coal and Related Materials, Northern Great Plains
Authors: Rehm Bernd W. , Groenewold Gerald H. , Morin Kevin A.
Published: July 2006

The hydraulic properties (hydraulic conductivity, specific storage and porosity) of coal and the sediments that surround the coal must be known or estimated to properly evaluate the environmental impact of coal strip mining on ground‐water flow systems. Published and unpublished data have been summarized from five study areas in North Dakota, three areas in Wyoming, two areas in Montana and two study sites in Alberta. Coal and sand beds form important aquifers in the region. Both materials have hydraulic conductivities of about 2 × 10−6 m.s−1 and specific storage values on the order of 5 × 10−6 m−1. Aquitards in the region consist of clayey silt to clay bedrock and pebble−loam (in parts of the region). The aquitards are fractured to varying degrees resulting in a wide range of measured hydraulic conductivity values. The aquitards are, in general, 100 to 1,000 times less permeable than the aquifers. Specific storage values of the aquitard material is on the order of 3 × 10−4 m−1. The hydraulic conductivity of strip mine spoils has a six order of magnitude range with a mean of 8 × 10−7 m.s−1. Variability is due to a number of factors including spatial variation of overburden lithology, method of spoil handling and contouring and time of year during which the spoil is handled. The hydraulic conductivity of the coal shows wide spatial variability within a given mine site. Variability of coal hydraulic conductivity between mines within North Dakota is less than within a given mine. Within the Northern Great Plains the permeability of coal may increase slightly from east to west.
The Clogging of Shallow Discharge Wells in the Netherlands River Region
Authors: van Beek C.G.E.M. , Kooper W. F.
Published: July 2006

A serious type of clogging occurs in wells which abstract anaerobic water from the shallow aquifer in the river region in The Netherlands. These clogged wells can easily be regenerated by means of sodium hypochlorite (15%). The figure for the specific yield after regeneration approximates to the figure on commissioning.

During the pumping to waste to clear the well after regeneration, the types of reaction products present in the spent chlorine solution were investigated. From this it can be deduced that the chlorine solution added was utilised mostly for the oxidation of iron sulphides. The remainder was used mainly for the oxidation of organic material. At the same time, calcium carbonate went into solution and iron carbonate was formed. During the regeneration of a number of wells, some silt was also removed.

Although information can be obtained in this way about the composition of the materials removed, it is impossible to form any concept of the nature in which these substances are present around the clogged wells.
Hydrogeology of the Gallup Sandstone, San Juan Basin, Northwest New Mexico
Authors: Stone William J.
Published: July 2006

Comparison of the hydrologic and geologic characteristics of the Gallup Sandstone (Late Cretaceous) has shown that its aquifer properties, the movement of its ground water, and the variation in its water quality are subject to considerable geologic control. This control is imposed mainly by the distribution of seven progradational sandstone bodies which make up the Gallup. These fluvial and marine sandstone bodies were deposited along the shore of a northeast‐regressing sea. The two transmissivity zones recognized have the same trend as that of the upper marine sandstone bodies (northwest‐southeast), and transmissivity decreases northeast of the pinch‐out of the lower marine sandstone bodies. Ground‐water flow is variously controlled by geologic structure, the geometry and orientation of the marine sandstones, and the position of the northeast limit of the Gallup Sandstone. Concentration of dissolved solids, as reflected by specific conductance, is controlled in part by distance from recharge area and in part by the distribution of transmissivity. The types of geologic control determined for the Gallup should apply to other Cretaceous, marine‐sandstone aquifers in the San Juan Basin, and, in a general way, to ancient shorezone deposits elsewhere.
Fault Controlled Ground‐Water Circulation Under the Colorado River, Marble Canyon, Arizona
Authors: Huntoon Peter W.
Published: July 2006

Springs with observed yields totalling about 10,000 gal/min discharge along both sides of the Colorado River in Marble Canyon, Arizona, between river miles 30 and 34.5. The waters originate from the plateaus on the respective sides of the canyon and are conducted to the floor of the canyon along the Fence fault zone or associated fractures. Chemical quality and temperature data demonstrate that some of the water discharging from springs on the west bank actually originates east of the river. This water flows under the Colorado River in the Fence fault zone, where it mixes with water from the west side before discharging from springs along the west bank. This is an unusual occurrence for the area and results because the heads at the springs along the west bank are the lowest in the circulation system associated with the fault.
DIGITAL RECORDER FOR AQUIFER TESTS
Authors: Getzen Rufus T.
Published: July 2006

Data loggers, in combination with appropriate electronic measuring devices, can improve pumping‐test data by reducing cost and by increasing accuracy, precision, speed, and computational convenience. The data logger (digital recorder) described herein was tested and found to work well. Sensitivity to blowing sand and freezing temperatures, excessive power consumption, and poor display legibility in bright sunlight are minor design deficiencies that slightly restrict the usefulness of this data logger. These problems can be easily corrected.
Geoelectric Soundings for Predicting Aquifer Properties
Authors: Kosinski Walter K. , Kelly William E.
Published: July 2006

Two bedrock valleys, filled with glacial outwash material, were investigated with Schlumberger resistivity soundings. Aquifer electrical resistivities were determined for 16 vertical electrical soundings at seven sites in southern Rhode Island where pumping tests had been run previously. Resistivities for the different aquifer materials were derived with boring log control. The auxiliary point methods were used to reduce the aquifer layering to a single representative resistivity value. Relationships between the representative aquifer resistivity and aquifer permeability and transmissivity were derived.
Kd's — Can They Be Used to Describe Reversible Ion Sorption Reactions in Contaminant Migration?
Authors: Reardon E. J.
Published: July 2006

In considering reversible sorption processes in ground‐water flow systems, it is important to determine whether the ground water is in steady‐state or dynamic chemical evolution. In steady‐state chemical evolution, the sorbed site populations at any point along the flow path are in equilibrium with the way in which ground water will evolve chemically due to mineral dissolution/precipitation, redox reactions, etc., during flow when it reaches this point. In dynamic chemical evolution it is not. In the steady‐state case, a location in the flow system can be characterized by a constant distribution coefficient over time for an ionic species involved in reversible sorption reactions. In the dynamic case, the distribution coefficient can be expected to vary at a location in a flow system over time. Subsurface contaminant migration problems which confront hydrogeologists invariably are of the dynamic chemical evolution type and the notion of a constant distribution coefficient or Kd to describe reversible sorption processes cannot be entertained.
AN ALL‐TEFLON BAILER AND AN AIR‐DRIVEN PUMP FOR EVACUATING SMALL‐DIAMETER GROUND‐WATER WELLS
Authors: Buss Daniel F. , Bandt Keith E.
Published: July 2006

During the past decade, increasing concern has arisen over the potential contamination to ground‐water systems by chemical substances which could threaten human health or the environment. Assessment of the impact of toxic substances on ground‐water quality is only as good as the chemical data analyzed in ground‐water samples.

Small‐diameter observation wells can be evacuated rapidly by an air‐driven pump. This air‐driven system has proven very effective when depth to water surface distances are greater than the suction lift height. The use of this device has greatly reduced well evacuation time in comparison to the conventional bailer. Following evacuation of several well volumes, an all‐teflon bailer can be used to collect the water sample for analysis. This material can be machined with some difficulty, but its inert properties render it a most desirable material for this purpose. Both of the devices discussed herein may be improved upon to fit different‐sized wells or different situations. The materials are easily accessible and except for machining of the teflon bailer parts, can be constructed with minimal effort. These devices were designed by Keith Bandt and Dan Buss of Camp Dresser & McKee, Inc., and used by the authors on various ground‐water monitoring projects to meet collection standards dictated by the U.S. EPA (1977) and the Wisconsin Department of Natural Resources (WDNR, 1977).
Analysis of Ground‐Water Hydrographs for Defining a Crystalline Hydrogeological Environment
Authors: Briz‐Kishore B. H. , Bhimasankaram V.L.S.
Published: July 2006

Water levels and gradients are a consequence of the nature of geological media and their study helps to define the hydrogeological environment. In this paper, water levels of wells in a typical weathered and fractured granitic environment of Shadnagar Basin, Andhra Pradesh were analyzed. These studies indicate the hydraulic continuity and unity of ground‐water flow systems in weathered and fractured granites contrary to the conclusions of earlier workers. Also, the long‐term behaviour of hydrographs reveals that the basin is not over‐developed and precipitation is the only source of recharge to the ground‐water system.