bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Large‐Scale Mining Withdrawals of Ground Watera
Authors: Peek Harry M.
Published: July 2006

Expanding water requirements during recent years have intensified development of the productive sedimentary aquifers of the North Carolina Coastal Plain. The effects of this development emphasize the local and regional limitations of the aquifer system and the need for an effective management program.

Withdrawal of about 60 million gallons per day from the Castle Hayne limestone, the most productive unit of the principal artesian aquifer of the area, began in July 1965 at a phosphate mine adjacent to the Pamlico River in Beaufort County. Within a few months, the artesian head was lowered below sea level in an area of about 800 square miles, and to more than 100 feet below sea level in the immediate vicinity of pumping. Under these conditions the aquifer became vulnerable to encroachment of saline water from (1) areas of natural occurrence of brackish water in the limestone member of the aquifer; (2) leakage of brackish surface water through the confining beds; and (3) vertical movement of brackish water from the underlying sand member of the aquifer.

The dramatic and “overnight” effects of the large withdrawals at the mine site and the threat of damage to the aquifer created sufficient public concern so that legislation was passed by the 1967 General Assembly, giving the Board of Water and Air Resources authority to regulate ground‐water withdrawals as needed to protect the aquifers of the State. An adequate management program can be accomplished that will not only protect the aquifer but will improve the development potential. The development of such a management program requires a thorough knowledge of the hydrology of the aquifer system, the objective of studies in progress. The implementation of the program will require the support of an informed public.
Some Aspects of the Scientific Communication System in Hydrology
Authors: Meyboom P.
Published: July 2006

This paper deals successively with some general concepts of scientific communication, with the characteristics of four well‐known hydrology journals and with ways in which messages are obtained. The most important conclusion is a rationale for restrained publication.
A System for Planning and Scheduling Wate Resources Studies and Construction Projectsa
Authors: LeRoux E. F. , Jorgensen D. G.
Published: July 2006

A simplification of the two most commonly used methods of network planning and scheduling is ideally suited to the planning and evaluation of both water resources studies and construction projects. The project planning diagrams illustrate the system for scheduling of project activities and the relation of each activity to the others.
The Ground‐Water Situation in Ohioa
Authors: Norris Stanley E.
Published: July 2006

Present ground‐water use in Ohio, approximately 650mgd (million gallons per day) amounts to about 5 percent of the water that enters the ground‐water reservoirs. The largest ground‐water supplies are developed where natural concentrations of water occur, chiefly in the watercourse aquifers, which consist of sand and gravel of glacial origin (outwash) in the valleys of the major streams. Other important aquifers are glacial outwash in upland areas and in the buried Teays Valley system, the limestone and dolomite aquifers in western Ohio, and sandstone and shale aquifers in the eastern half of the State.

Future outlook is that more of the increasing water demand will be met from ground‐water sources. Ground‐water supplies will be developed at many new sites, and aquifers in areas already heavily pumped will be made to yield more water by the drilling of additional wells and recharging the aquifers artificially. Large quantities of ground water in storage, virtually unexploited, could be used for temporary low‐flow augmentation of streams. Management of ground‐water resources will be needed to help solve supply and distribution problems, and to resolve conflicts between users. Among future problems will be those arising from underground disposal of wastes, a practice which is expected to grow substantially from enforcement of water‐quality standards for streams, set under the Federal Water Quality Act of 1965.
Design and Operation of an Inexpensive Sensitive Piezometer with Short Timelaga
Authors: Allman David W. , Williams Roy E. , Stephenson Gordon R.
Published: July 2006

The growing number of ground‐water research projects that are based primarily on potential distribution data has stimulated the development of several new types of potential measuring, instruments. The primary requirements for these instruments are longevity, precision, sensitivity, and short timelag. Ease of installation, minimum maintenance, low capital investment, and provision of a continuous record are equally desirable. Generally, available instruments will satisfy two or three, but not all of these requirements.

The need for a piezometer possessing all these characteristics was encountered during a flow‐system study beneath an irrigated field. A piezometer subsequently was designed which combines the sensitivity of a Kecke electrical water‐level sensing device with the continuous record provided by a Stevens Type F, graphic recorder. Replacement of the standard Keck sensing “Bob” with a probe specifically designed for small diameter pipes (5/16‐inch I.D.),* provides instrumentation with a short timelag. The absence of a diaphragm and strain gauges enhances longevity. The device is inexpensive, simple and easily installed. Samples of well water for chemical analysis may also be obtained from the piezometers.
Casing Detector and Self‐Potential Loggera
Authors: Frimpter Michael H.
Published: July 2006

A simple and rapid method of determining casing length and permeable zones in wells tapping bedrock can be useful to well drillers and hydrologists. A device consisting of a galvanometer, a reel of insulated wire, and a copper electrode locates the casing depth, changes of lithology, and permeable zones. The small‐diameter electrode permits measurement through well‐seal access ports avoiding the expensive and time‐consuming procedure of removing the seal and drop pipes to measure casing depth with a magnet. The measured electromotive force changes rapidly when the electrode passes the end of casing. Thus, the depth of casing is easily determined from the length of wire payed out. Changes in electromotive force measured within the uncased part of a well frequently indicate permeable zones, thereby aiding in choice of the most efficient drop‐pipe length, and also yielding useful information for hydrogeologic studies.
Steady‐State Lateral Movement of Water Through the Unsaturated Zone of an Unconfined Aquifera
Authors: Mobasheri F. , Shahbazi M.
Published: July 2006

In a steady‐state condition the lateral flow rate through the unsaturated zone of an unconfined aquifer increases with a decreasing rate as the depth of the unsaturated zone increases while hydraulic gradient is kept constant. This flow rate reaches a maximum as the depth of the zone is increased. This maximum flow rate is computed by various methods such as an aquifer model, graphical integration of the characteristic hydraulic conductivity curve and a flow net diagram. Based on these calculations a simple method is outlined for estimation of steady‐state flow rate through the unsaturated zone of an unconfined aquifer. It is also concluded that in shallow unconfined aquifers the contribution of the flow through the unsaturated zone to the total lateral flow can be significant.
Small Diameter Wells Drilled by Jet‐Percussion Methoda
Authors: Matlock W. G.
Published: July 2006

Observation wells and access holes for neutron probe use were drilled by a jet‐percussion drill rig in coarse alluvial material near Tucson, Arizona. The method combines the jetting action which effectively removes loose materials with the percussion necessary to break up tighter formations and large particles. A unique feature of the equipment is the provision for simultaneous drilling and driving the casing to keep the hole open in loose formations. Washed samples of the material being drilled can be obtained from the recirculating water system. Drilling rates were from seven to ten feet per hour, and costs including casing were less than $1.50 per foot. Maximum depth is about 100 feet.

Hydrologic study of a ground‐water reservoir requires access to the aquifer. Observations are made where the water table intersects the land surface, such as at springs or seeps, or through existing wells. However, wells are not always found in desired locations or are pumped so heavily that their usefulness as observation wells is impaired. Measurements are also made in the unsaturated zone with neutron moisture measuring equipment, which requires a small diameter cased access hole for the neutron probe.

An observation well needs a diameter only large enough for access by measuring devices and must be immediately responsive to changes in aquifer water level. For neutron probe use, the required diameter is about two inches, and the well must have no significant effect on moisture movement in the unsaturated zone. To meet these requirements the drilling process should have no lasting effect on the formation surrounding the well. Finally, since the wells have no economic utility, construction cost must be low.

A network of observation wells and neutron probe access holes was drilled as part of a project to evaluate the natural recharge from Rillito Creek near Tucson, Arizona. The formation along the creek bed is a coarse alluvial outwash containing almost no clay, considerable running sand, and some large gravel and boulders. Commercial churn (percussion) and hydraulic rotary drills, commonly used for drilling in this area, were first tried but encountered much difficulty in the loose materials.

Previous investigators used jetting equipment drill small diameter holes in a variety of alluvi formations (Cederstrom and Tibbitts, 1961; Bowma: 1911; and Pillsbury and Christiansen, 1947). Howeve in most cases, either open hole drilling was used because the fine material content and the limited numb. of boulders or large gravel particles made this methc possible, or drilling mud was used to maintain th hole. The jetting method uses water pumped unde pressure through hollow rods and a drill bit to loose the material and carry it to the surface. The jettin water receives little aid from the drill in loosenin the material to be removed. Usually the drill cutting are settled out in a tank or basin, and the water i recirculated.
Well Screens and Gravel Packsa
Authors: Blair A. Hunter
Published: July 2006

The purpose of well screens and gravel packs is to maintain open access within the aquifer ensuring that thorough development of the well is not impeded by sand. Where a well draws on unconsolidated sands and gravels, or other friable materials, the installation of a screen and pack is essential.

The use of correctly designed equipment is important and this paper represents a review of the diverse types available, but does not set out to make any recommendations.

Well screen designs should incorporate the following features:

Minimum entrance velocity.

Maximum open area of screen.

Correct design of slots to minimize blockages.

Slot size should match aquifer or gravel pack medium.

Screen material should be corrosion resistant.

Screen should allow for periodic maintenance.

Commercial well screens fall into various categories according to their slot designs. A slot shape, offering the maximum open area consistent with strength, is a priority and the material used in screen manufacture has an important bearing on this. Blockage of screens may be caused by chemical deposition formed by precipitation or corrosion products, and coated screens have been introduced seeking to inhibit this.

Gravel packs should include the following design features:

Sand free operation after development.

Give lowest possible resistance to permeation.

Offer low entrance velocities.

Be resistant to chemical attack and have an efficient service life.

The gravel pack should ensure that the completed well operates free of sand; thus the particle size of the pack depends upon the particle size of the aquifer. Gravel pack design should be guided by standard sieve analysis.

It is evident from the variety of claims made for well screens and gravel packs that further research is necessary. It is suggested that the following points need further investigation:

Improved design of nonblocking opening.

Design consideration of screen resistance to chemical attack.

Best type of gravel and optimum thickness of the pack.

Head loss through the screen and pack.
Effects of a Concentrated Acid on Water Chemistry and Water Use in a Pleistocene Outwash Aquifera
Authors: Grubb Hayes F.
Published: July 2006

A break in a waste‐discharge line associated with a 49‐foot rise in stage of the Ohio River in March 1967 allowed an undetermined volume of 22 percent hydrochloric acid to enter the Pleistocene outwash aquifer used by a Kentucky industry. Chloride concentrations in excess of 30,000 mg/l (milligrams per liter) were observed in the water discharged from the industrial well nearest the break in the waste‐discharge line. Chlorides ranged from 5–26 mg/l in water pumped from this area prior to intensive development. Other changes in water chemistry such as an increase in iron from 5 mg/l to 9,600 mg/1 indicate a dissolution of the aquifer materials. Movement of the highly mineralized water in response to river stage and pumping of the industrial wells has forced the industry to change its water‐supply system. Three wells, approximately 600 feet from the river, were the primary water source prior to March 1967. By March 1968, the well nearest the acid source was abandoned, the remaining two wells near the river were used in a supplemental capacity and a fourth well 1,500 feet from the river plus a new well were the primary water sources. Fluctuations of chlorides in an industrial well near the river for a 16‐month period indicate a persistent body of highly miner alized water near the acid source. Movement of this water body appears to be regulated at low river stages by the inclined surface of the New Albany Shale bedrock.
Estimating the Ground‐Water Contribution to Storm Runoff by the Electrical Conductance Methoda
Authors: Visocky Adrian P.
Published: July 2006

The feasibility of determining the ground‐water contribution to stream flow during periods of storm runoff by continuous monitoring of a stream's electrical conductance was investigated. Methods involving graphical techniques or ground‐water stage versus base flow rating curves are generally used to determine the ground‐water contribution, but the ground‐water contribution can also be estimated if stream flow and the conductance of surface water and of ground water are known. The conductance method was tested on a 95‐square‐mile basin in north‐central Illinois. Continuous records of stream flow, stream‐flow conductance, and ground‐water stage within the basin were collected. A rating curve of base flow versus mean ground‐water stage was constructed, and ground‐water discharges determined from the rating curve were compared with those computed from conductance data. The conductance method normally gave a lower estimate of the ground‐water contribution than did the rating‐curve method. However, analyses of storms which were preceded by extended dry periods resulted in much lower estimates of ground‐water discharge by the rating‐curve method than by the conductance method. The conductance method offers a simple alternative for use in areas where observation wells are unavailable or where rating curves are difficult to construct.
A Hydrological Approach to Control Acid Mine Pollution for Lake Hope
Authors: Ahmad Moid Uddin
Published: July 2006

Acid mine drainage is a serious problem in the Appalachian region. Coal mining has disturbed the natural ground flow system. The mines are continuously being flushed by this disturbed flow system and producing enormous quantity of sulphuric acid. A study of McDaniel Mine has revealed that the flow is lateral and clay layers under the coal do not allow it to leak into the underlying aquifer. A study of water well logs within 10 miles of Todd Mine revealed the existence of three separate aquifers. A pilot plan for Todd Mine is proposed to discharge the uncontaminated water from the upper aquifer to the lower aquifer under the concept of “weeping wells.” The acid discharge from the mine may be stopped. The extension of this scheme may solve the serious problem of pollution of Lake Hope. The concept may further be extended to other areas of the Appalachian region to control acid mine pollution.
A Hydrogeophysical Survey Using Remote‐Sensing Methods from Kawaihae to Kailua‐Kona, Hawaii
Authors: Adams William M. , Peterson Frank L. , Mathur Surendra P. , Lepley Larry K. , Warren Clifton , Huber Richie D.
Published: July 2006

Several geophysical techniques have been specialized for applications to exploration for ground water in an insular basaltic environment. This article describes a multidisciplinary application of several such techniques to the Kona Coast of Hawaii in Hawaii. Aerial infrared scanning and low‐level aeromagnetic surveys were the major reconnaissance techniques. For detailed study, modified audiomagnetotelluric and D. C. resistivity profiling methods were used. The improved knowledge of subsurface structure confirmed the expectation that no large flows, such as suitable for commercial exploration, occur in that coastal sector.
A Shortcut for Computing Stream Depletion by Wells Using Analog or Digital Modelsa
Authors: Taylor O. James
Published: July 2006

Theory indicates that the effect of a discharging well on a nearby stream is independent of the length of the reach. The theory was confirmed using a digital computer model of short and long reaches of a stream‐aquifer system. Digital computations using short reaches of most stream‐aquifer systems will give results comparable in accuracy to one of a long reach with considerably less effort and expense.
Future Demands on Ground Water in Northeastern Illinois
Authors: Schicht Richard J. , Moench Allen F.
Published: July 2006

Future water demands were estimated for each 10‐year interval from 1980 to 2020 for areas in the Chicago region dependent upon ground water as a source of supply. Demands were compared with ground‐water availability to define water deficient areas. Two approaches were considered in developing the ground‐water resource. The first approach limits ground‐water withdrawals to the maximum rate of natural ground‐water recharge that can be induced by pumping. The second approach allows withdrawals to exceed natural recharge. When limiting ground‐water withdrawals to recharge a large part of the region will require importation of water by as early as 1980. With proper pumpage distribution it is conceivable that there is sufficient water that can be withdrawn (mined) in excess of natural recharge to meet demands through the year 2020.
Ground Water in the Aden Sector of Southern Arabiaa
Authors: Cederstrom D. J.
Published: July 2006

A reconnaissance of parts of the former West Aden Protectorate enables a characterization of the dominant hydrologic elements to be made. In this desert environment intermittent streams from the east‐west range of mountains provide considerable water for flood irrigation and groundwater recharge of alluvial fans along the Gulf of Aden. High yield wells are developed in the coastal area and in at least one alluvial area on the back slope facing the Empty Quarter. Ground water in the interior is generally restricted to areas where wadi flow provides occasional recharge. Relatively few rock wells have been drilled in the area. Many wells in the alluvium yield silty water leading to clogging of the wells and undue pump wear.
High‐Capacity Wells for Conjunctive Use of Water
Authors: Ham Herbert H.
Published: July 2006

The Bureau of Reclamation's authorized Lower Teton Division multipurpose project is based on conjunctive use for irrigation of surface water from the Snake River and ground water from the Snake Plain basalt aquifer of southeastern Idaho. Ground water will be provided to replace surface water adversely diverted to Division lands during dry years. Extensive investigations, including the construction and testing of five test wells of 12‐ to 18‐cubic‐foot per‐second (cfs) capacity, indicate that use of such large wells is feasible, and that the basalt aquifer will yield the initial 400‐cfs maximum flow without appreciable detrimental effect. Location of well fields and design and construction practices were primarily controlled by field conditions; use of theoretical parameters was essentially precluded.
Pit Recharge Influenced by Subsurface Spreading
Authors: McWhorter David B. , Brookman John A.
Published: July 2006

Artificial recharge from pits, trenches, or basins ordinarily is not considered feasible in situations where a thick layer of slowly permeable material exists near the surface. Results of a field investigation of recharge from an irrigation tail‐water pit indicate that pit or trench recharge is feasible under this condition provided that a much more permeable stratum exists above the less permeable one. The more highly conductive layer acts as a subsurface spreading basin which greatly enhances the opportunity for recharge.

The potential for recharge from pits penetrating a highly conductive layer underlain by a slowly permeable stratum can be calculated from the results of a simple theoretical analysis which is presented. The importance of subsurface spreading is demonstrated by a numerical example using conditions similar to those encountered during the field investigation. Under these conditions a narrow pit or trench 525 feet long and 10 feet deep has the potential for recharging at a rate of 1 million gpd or about 700 gpm. Subsurface spreading occurs over nearly 10 acres for this case. Evaporation is reduced because the need for spreading the water over large areas on the land surface is eliminated. Since the length of pit perimeter and not the surface area is the important factor for design, the volume excavated can be minimized by constructing long narrow pits or trenches.
Determining Wedge Angle for a Wedge Aquifer
Authors: Berg A. Vanden , Lennox D. H.
Published: July 2006

Analysis of drawdown data from either the pumped well or an observation well in a horizontal, wedge‐shaped aquifer results in determination of the distances from the well to the four nearest image wells.

These results may be used, in the case of pumped‐well data alone, to determine the wedge angle; if only observation‐well data are used, eight possible positions of the wedge can be determined; a combination of pumped‐well and observation‐well data further reduces the number of possible wedge configurations to two, which are each other's mirror image in the line through the wells; only additional geologic or hydrologic information can distinguish between these two to delineate the aquifer area completely.
Where Have All the Toxic Chemicals Gone?a
Authors: Walked William H.
Published: July 2006

Many municipal, industrial, domestic and farm water supplies throughout the country are derived from wells tapping shallow aquifers that have a high contamination potential from surface derived sources. Unfortunately, water samples from most of these wells are not analyzed on a regular basis even for bacteria or simple chemical pollutants such as nitrate. Practically none of them are routinely checked for more serious contaminants such as viruses, weed killers, pesticides, trace metals, and an almost countless number of toxic chemical compounds commonly used in our environment and eventually discarded in garbage dumps, waste‐burial grounds, or disposal wells. Because of this, the possibility of serious ground‐water contamination often is not discovered until a high degree of contamination is present.

Microorganisms contained in water may be effectively removed by filtration in a short distance of travel through fine‐grained earth materials. However, most toxic chemical compounds are not. Instead, these are carried by precipitation recharge to surficial ground‐water reservoirs. After entry such contaminants move downgradient through the aquifer materials, usually at rates of only a few feet per year with little if any dilution, to natural discharge points such as streams, lakes and swamps, or to pumping wells.

Ground‐water contamination occurrences from nitrate, arsenic, chromate, cadmium, chlorinated hydrocarbons, and a large number of other toxic chemicals are increasing. These show that a serious threat to public health may be imminent unless all surficial and underground disposal sites of toxic chemicals are located, the extent and magnitude of ground‐water contamination from each site evaluated, and corrective measures applied where necessary.
Efficiency of Partially Penetrating Wells
Authors: Sternberg Yaron M.
Published: July 2006

A graphical solution is presented for the determination of total drawdown of partially penetrating wells. This simplified solution agrees with the more complicated exact solution and can be used to evaluate the efficiency of such wells.
Protection of Water‐Supply Wells from Contamination by Wastewatera
Authors: Bemhart Alfred P.
Published: July 2006

Wastewater disposal by a combination of soil infiltration and evapotranspiration is better than disposal through centralized sewerage systems, because the first alternative returns wastewater nutrients where they belong—to growing plants—rather than discharge the pollutants where they cause damage through eutrophication of lakes and rivers, as the second alternative does.

Wastewater disposal by soil infiltration and evapotranspiration achieves advantages for our much abused environment only if three conditions are met: (1) sufficient land area is available, (2) strong microbial activities are evident, and (3) water‐supply wells are protected.

The proposed method for design and area calculation of seepage beds stresses—in addition to the quality of soil—the importance of microbial actions to keep the soil pores open. For silt‐loam‐clay mixtures of soils, the required seepage bed area varies from 365 sq ft (34 m2) to 640 sq ft (60 m2) for average households if actions of higher aerobic microorganisms are strong.

Water‐supply wells located on the same property are protected from wastewater contamination by natural purification in deep layers of undisturbed soil. The protective distance between mouth of well and seepage bed has a vertical and a horizontal component, the former determined by the depth of the well. The need for a sufficiently long horizontal component influences the required property size. It also depends on the types of soil at deeper layers. For an 80 ft deep well for example, the horizontal protective distance varies from 80 ft (24 m) for silt‐loam mixtures to 140 ft (42 m) for sand‐silt mixtures.

Wastewater can be entirely evaporated, if soil infiltration would be a hazard to water‐supply wells. Evapotranspiration beds of 2000 sq ft (186 m2) with strong microbial activity are needed for average households.
TECHNIQUES FOR LOCATING WATER WELLS IN FRACTURED CRYSTALLINE ROCKSa
Authors: Florquist Bruce A.
Published: July 2006

. Since 1964, this geologist has used surficial geology to locate hundreds of water wells in fractured crystalline rocks of the Colorado Rockies. The techniques, procedures and priorities that have been established during that period have been incorporated into a training program that is used to teach new personnel how to determine the best water well location on a given tract.

In summary, new geologists are taught how to determine the water needs of the client, “read” the surficial geology, determine the best or controlling water associated features of the area, determine the depths of the wells to take maximum advantage of geohydrologic conditions, and prepare a report in layman's terms so that the client fully understands the ground‐water conditions and what can be expected from wells.

By using these methods, our staff is able to maintain a 95%+ success ratio and provide these services at a reasonable fee. This paper will present our program which should be applicable to any area that has similar geology.
Water‐Management Studies of a Stream‐Aquifer System, Arkansas River Valley, Coloradoa
Authors: Taylor O. James , Luckey Richard R.
Published: July 2006

A mathematical model was developed and used to simulate the stream‐aquifer system in the Arkansas River valley in southeastern Colorado, from Pueblo to the Colorado‐Kansas State line. The model simulates the interrelations among ground water and surface water including reservoirs, losses, and transmountain diversions, utilizing various water‐distribution rules. The model was used to analyze 24 water‐management plans designed to reduce shortages in the irrigation supply. One management plan simulated salvage of water from phreatophyte evapotranspiration, different reservoir operation regulations, use of imported ground and surface water, a new reservoir, additional ground‐water use, and application of excess streamflow. The resulting annual dependable supply was increased from 610,000 acre‐feet to 870,000 acre‐feet in relation to an annual demand of 1,100,000 acre‐feet. The model can be used as a tool to analyze other water‐management plans.
Geohydrology of the Buried Triassic Basin at the Savannah River Planta
Authors: Marine I. Wendell
Published: July 2006

At the Savannah River Plant near Aiken, South Carolina, as at other locations where there are chemical separations plants for the processing of nuclear fuels, the high‐level radioactive wastes are stored in concrete and steel tanks buried just beneath the surface of the ground. This waste is of such activity and longevity that it cannot be dispersed into the environment, but it must be contained for periods of time extending at least into hundreds and perhaps thousands of years. One concept for the terminal containment of this waste is to store it in excavated chambers within the bedrock, which is covered by about 1000 feet of Coastal Plain sediments at the plantsite. As part of the safety evaluation of this concept, the geology and hydrology of both the Coastal Plain sediments and the bedrock have been studied. However, intensive investigation of bedrock waste storage has now been deferred pending more detailed evaluation of alternative concepts of waste storage and management.

In the studies completed, a buried Triassic basin that might have potential for waste storage was discovered beneath the southern third of the plantsite. Investigation into the characteristics of this basin was started in 1971. This was not an engineering or design study but was aimed at understanding the geohydrology of the Triassic basin to determine its compatibility with the safe storage of waste.

Seismic surveys, gravity and magnetic surveys, and the drilling of several exploratory wells indicate that the Triassic basin is about 30 miles long, 6 or more miles wide, and perhaps 5300 feet thick. One well penetrated the Triassic border, a second was in the center of the basin, and a third investigated an inferred intrabasin fault. The rock is predominantly mudstone of very low permeability with a few lenses of poorly sorted gritty sand. The water yield of all the exploratory wells is extremely low, and water‐transmitting fractures are virtually nonexistent.

In two wells within the basin, heads above land surface have been measured that cannot be explained by connection with a recharge area. Ten possible explanations have been evaluated: aquifer head, fossil head, tectonic compression, rapid loading and compaction of sediments, water derived from igneous intrusions, infiltration of gas, precipitation of minerals, phase changes, temperature increase, and osmotic membrane phenomena. Systematic evaluation, particularly of the time for dissipation of an elevated head to the head of its surroundings, eliminates most of these explanations. Those that remain as possible explanations are: tectonic compression, temperature increase, and osmotic membrane phenomena. It is not known at present whether the high head is general over the entire basin or only in segments of it.
Total Dissolved Solids in Ground Water of the Wainwright Area, Albertaa
Authors: Hackbarth D. A.
Published: July 2006

The technique for gridding of random data developed by Newton (1973) is useful in ground‐water investigations. The method appears to have potential for both regional and local ground‐water studies.

The method as applied to the Wainwright area of Alberta shows that total dissolved solids content in glacial drift and at several depths in the bedrock is related to both the thickness and nature of the drift and to nature of the bedrock. Total dissolved solids in the ground water in areas of thick and coarse‐grained drift are lower than in areas of thin and finer‐grained drift. The dissolved solids content of the bedrock is lower where the bedrock is of nonmarine origin and where the overlying drift is thick. In areas where the bedrock is of marine origin and the glacial drift thin the total dissolved solids content of the ground water tends to rise.
Monitoring Toxic Chemical Pollution from Land Disposal Sites in Humid Regions
Authors: Walker William H.
Published: July 2006

Practically all of the toxic chemical land disposal sites now in operation are equipped with only minimal and generally ineffectual monitoring systems, which seldom are capable of detecting even excessive surface‐water and ground‐water pollution from such sites. From monitoring data normally obtained, it is practically impossible to quantitatively evaluate the total toxic chemical buildup in contiguous soil, plant, and water environments or the vertical and horizontal migration patterns of pollutants through underlying earth materials. Monitoring facilities and procedures described in this paper are designed to provide that data required to effectively evaluate all of these parameters. These evaluations in turn should be most helpful in selecting the safest possible sites for hazardous waste disposal, and in developing ways and means to design, operate, and monitor such facilities that will assure minimal danger to public health from this particular waste disposal practice in the future.
Orthophosphate in Ground Water, Hall County, Nebraska
Authors: Atkinson Jon C.
Published: July 2006

Analytical data for 161 sampling sites indicate orthophosphate concentrations in ground water ranging from 0 to 1.7 mg/1. Ground water in about 50 percent of the county contains concentrations of 0.1 mg/1 or greater. In two areas aggregating 115 square miles, orthophosphate concentrations exceed 0.5 mg/1. Principal sources of phosphate in ground water in Hall County include: indigenous soil phosphate, municipal sewage effluent, commercial fertilizer, and feedlot wastes.
Bacterial Flora of Saline Aquifersa
Authors: Willis C. J. , Elkan G. H. , Horvath E. , Dail K. R.
Published: July 2006

The bacterial flora of three unpolluted saline aquifers were examined. Aerobic, anaerobic, and facultative microorganisms were isolated and classified to genus. The organisms isolated were those commonly found in surface water and soil. Methanogenic bacteria were present in all aquifers.
Cathodic Protection Wells and Ground‐Water Pollutiona
Authors: Ritchie Edwin A.
Published: July 2006

Any improperly constructed or inadequately destroyed water well can endanger ground‐water quality by providing a path for pollutants to reach usable water. Another kind of well, the cathodic protection well, can also present a hazard to ground water.

Cathodic protection wells house devices used to alleviate electrolytic corrosion of pipelines, tanks, and other installations situated in a corrosive environment. They are widely used in the petroleum and gas industry. Cathodic protection is a technique used to prevent or minimize this corrosive action by redirecting the current to a substitute anode which then deteriorates instead of the pipeline. To offset the disadvantages of horizontal, or shallow vertical, anodes, and since almost all ground water has enough salt to conduct electricity, the vertical deep anode (cathodic protection well) was developed. They normally range from 100 to 500 feet in depth and 8 to 10 inches in diameter.

To prevent cathodic protection wells from acting as conveyances for pollutants, they must be properly designed and constructed at the outset and, when their useful lives are over, properly destroyed. This is best done by following standards of good practice. California has developed and is implementing such standards as part of its program for ground‐water basin protection.
Countermeasures to Control Oil Spills in Western Canadaa
Authors: Hall P. L. , Quam H.
Published: July 2006

Increasing concern over ground‐water pollution from hydrocarbons is being expressed by governments and industries in western Canada. The Manitoba government has recently held public hearings on the subject and is now working with the petroleum industry to develop new legislation concerning the handling of refined petroleum products. The petroleum industry has developed a series of “oil spill manuals” which describe procedures for controlling leaks and spills of petroleum products. Emphasis is now being placed on education and prevention, and hydro‐geologists are involved in developing training manuals and films.
Evaluating Ground‐Water Paths Using Hydraulic Conductivitiesa
Authors: Naney James W. , Kent Douglas C. , Seely Edward H.
Published: July 2006

A method is presented for selecting ground‐water flow paths by comparing modeled and measured hydraulic conductivity distributions. A flow chart is included which shows the steps followed in selecting the concept of groundwater flow which best fits measured hydrogeologic conditions.

Both noneffluent and effluent stream conditions are evaluated using the method. Residual maps of hydraulic conductivity are used to show how modeled hydraulic conductivity may be as much as 300 times that expected when the wrong concept is used. Flow nets of modeled and measured data downstream from a flood‐water‐retarding structure are developed using the selected hydrogeologic conditions.

Fitting hydraulic conductivity data results in a distribution of ground‐water flow paths which better represent actual flow conditions. The method provides a unique means of calibrating a model in a pilot test area and applying it to geologically similar nearby watersheds. It is also useful for checking paths of subsurface flow where flow distribution is important as it is in the movement of chemical pollutants or nutrients from a source of recharge, such as a watershed impoundment, to downstream waters.
Geoelectric Sounding for Delineating Ground‐Water Contamination
Authors: Kelly William E.
Published: July 2006

A resistivity survey was made in the vicinity of a landfill in a glacial aquifer to determine the extent of ground‐water contamination. The survey consisted of 12 electrical soundings with the Winner probe configuration. An examination of the sounding curves and logs of nearby test borings suggested a three‐layer geoelectric model for studying water quality variations.

The thicknesses and the resistivities of the upper two layers were fixed. Differences in apparent resistivity were assumed to be due only to differences in specific conductance of ground water in the saturated zone (third‐layer resistivities). Apparent resistivities at the largest probe spacing, 102 feet (31 m), were then computed for a range of assumed third‐layer resistivities. Specific conductances corresponding to third‐layer resistivities were then computed using an assumed formation factor of 4.5. A relation between apparent resistivity at the 102‐foot spacing and specific conductance was developed for converting apparent resistivities to specific conductances. Quadratic trend surfaces developed for specific conductances measured at monitoring wells and computed from apparent resistivity are shown to be in good agreement.

Under favorable conditions, interpretation of electrical sounding curves provides a basis for estimating specific conductance of ground water from surface resistivity methods. This leads to a quantitative assessment of ground‐water contamination which compares favorably with that determined from monitoring wells.
The Dashte‐Naz Ground‐Water Barrier and Recharge Projecta
Authors: Williams Dennis E.
Published: July 2006

The danger from salination poses a significant threat to development of ground‐water resources for domestic or irrigation use in near‐coastal environments throughout the world. The Dashte‐Naz farm area near the Caspian Sea in northern Iran is no exception. Large‐scale ground‐water development in this region has been limited to wells south of the Caspian Sea near the base of the Alborz mountains where sediments are coarse and natural recharge high. In the northern regions, however, exploitation of the groundwater resources for agriculture and livestock purposes has proven fruitless with most of the high‐yielding wells turning saline after only several irrigation pumping seasons. The source of the salination comes not from encroachment of Caspian Sea water but rather from sediments saturated with connate or fossil waters. A wide zone of dispersion separates the salinated aquifers from the fresh‐water aquifers nearer the mountains.

The Dashte‐Naz ground‐water barrier and recharge project was conceived for purposes of overcoming the problem of exploitation of fresh ground‐water reserves in the vicinity of saline‐water fronts. The project presently under construction is a pilot research project on the practicality of using an injection well barrier for storing water underground in areas immediately adjacent to saline ground‐water reservoirs. The results from this project will be used to design other water‐supply projects in Iran not only
Injection/Extraction Well System–A Unique Seawater Intrusion Barriera
Authors: Sheahan N. Thomas
Published: July 2006

A multiple‐aquifer system in the bayfront area of Palo Alto, California is being intruded with seawater from San Francisco Bay. In order to combat this potential degradation of the ground‐water supplies in the area, a sea‐water intrusion barrier is being constructed consisting of a series of injection wells used to inject 2.0 million gallons per day (7.6 × 106 l/d) of reclaimed wastewater into a shallow aquifer. The injected water is subsequently removed by a similar system of extraction wells to avoid any possible degradation of the water‐supply aquifers from this source, and to allow reuse of the reclaimed wastewater. The investigation phase included test drilling, aquifer testing and injection testing to determine the feasibility of the injection/extraction (I/E) concept. The number, spacing and location of I/E doublets were optimized using a digital computer model. The double‐cased, double‐screened wells were constructed using corrosion‐resistant materials and were designed for ease of routine maintenance. In operation, injection and extraction will be computer controlled by sensing piezometric levels in a series of monitor wells. Water pumped from the extraction wells will be sold for industrial and agricultural purposes. The I/E well system has been approved for 87½ percent Federal and State grant funding.
A Nonstructural Approach to Control Salt Accumulation in Ground Watera
Authors: Helweg Otto J.
Published: July 2006

One of the more subtle and dangerous areas of pollution is that occurring in ground water from normal irrigation practices. The pollution from salt buildup is presently one of the unsolved problems in managing stream‐aquifer systems. This paper presents several strategies that offer a possibility of controlling this salt buildup. For example, instead of applying irrigation ground water near the site of the well, the ASTRAN Method transfers it downstream to be applied on land where the ground water is a lower quality thereby controlling the increase in salt concentration. Instead of preventing seepage loss in delivery canals, the percolating water is used to maintain ground‐water quality. Finally, timed releases of return flow remove salts without exceeding surface‐water quality constraints.
Improving the Sanitary Protection of Ground Water in Severely Folded, Fractured, and Creviced Limestonea
Authors: Jones Elmer E. , Murray Charles M.
Published: July 2006

The construction of wells yielding safe, sanitary water in areas of severely folded, fractured, and creviced limestone depends on the retention of enough sediment in the transmission paths to restrict the movement of contaminants. The described research has been directed towards two problems–the identification of terrain and hydrologic features that indicate a lack of adequate sanitary protection of ground water in the formation, and means of improving this protection. Intermittent spring‐sinks along streams or in low‐lying areas indicate a reversal of ground‐water flow in the area. When the water level rises above a critical level sediments that have accumulated in the formation over many years may be discharged in a few days, resulting in a loss of filtering ability.

Ground‐water levels and bacteriological contamination have been monitored on four wells in Washington County, Maryland, since 1973. Ground‐water quality deteriorated after tropical storm Agnes washed sediments from the formation. Techniques for preventing surface contaminant entry, improving filtering ability of the formation, and providing controlled relief of hydrostatic pressure have been studied as ways of protecting ground water in the formation.
Land and Water Use Impacts on Ground‐Water Quality in Las Vegas Valleya
Authors: Kaufmann Robert F.
Published: July 2006

Marked changes in the occurrence and quality of near‐surface ground water in Las Vegas Valley, Nevada result from urban and industrial land and water use practices. In‐valley recharge has increased tenfold in the period 1943 to 1973 and now amounts to about 40,000 acre‐feet/year (49.3 million m3). Ground‐water flows leaving the Valley have increased from 250 acre‐feet/year to about 12,000 acre‐feet/year.

Twenty to 400 tritium units (T.U.) in shallow ground water confirm widespread addition of recent recharge. Trend‐surface analysis of recent water‐quality data for depth intervals or “slices” of 0 to 50, 51 to 100, and 101 to 300 feet (0 to 15.2 m, 15.5 to 39.5 m, 30.8 to 91.4 m) revealed that natural trends below a depth of 50 feet are explainable in terms of broad hydrogeologic conditions. From 0 to 50 feet quality is highly irregular and markedly more influenced by land and water use practices and waste disposal in particular. Chloride, TDS, and nitrate are particularly diagnostic of return flows as is spring development and (or) a rising water table resulting from increased recharge and low vertical permeability. Statistical tests on water‐quality data for the period 1912 to 1968 yielded generally insignificant change with time. However, the extreme paucity of the data base makes any conclusion questionable.

More efficient irrigation practices could reduce the present irrigation water demand by 15,000 acre‐feet/year and reduce return flows by 11,000 acre‐feet/year. Return flows by the year 2000 could easily amount to 75,000 acre‐feet/year or about three times the total water budget of the Valley prior to urbanization. Therefore, groundwater problems are likely to worsen and, if present monitoring practices prevail, go unnoticed.