ALBERT

Notes: New sanitary landfills are being opened each day to accommodate the rising volume of solid wastes. Selection of proper sites is a very major part of the disposal problem, particularly as they might affect the surrounding surface and ground water.Leachate production is inevitable in the humid East and throughout most of the country. Several alternatives are suggested that would result in the assimilation of migrating leachate into, the environment at tolerable limits or for its renovation prior to final discharge: Alternative 1—knowledge of existing hydrogeologic conditions which would favorably control the rate and direction of leachate migration; Alternative 2—engineering the landfill by construction of low-cost facilities to collect and treat leachate; and Alternative 3—construction of limited collection facilities to supplement natural conditions.It is suggested that more emphasis be given to hydrogeologic factors in the selection of refuse disposal sites to insure protection of surrounding surface and ground water. It is time to approach the waste disposal problem on a more sophisticated level by requiring test drilling, monitoring, and by giving consideration to the engineering of, landfills so that man's health and' environment are not jeopardized.

Notes: 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.

Notes: The best features of analog and digital computers were combined to make a management model of a stream-aquifer system. The analog model provides a means for synthesizing, verifying, and summarizing aquifer properties; the digital model permits rapid calculation of the effects of water-management practices. Given specific management alternatives, a digital program can be written that will optimize operation plans of stream-aquifer systems. The techniques are demonstrated by application to a study of the Arkansas River valley in southeastern Colorado.

Notes: Underground detonations may produce observable effects in surrounding aquifers and wells. The nature and the duration of the effect at any observation point seem to depend on several factors such as the amount of energy released by the detonation, the geologic environment, the position of the buried explosive device in relation to the saturated zone, aquifer characteristics, and the distance from point of detonation. Precise measurement of these effects in wells presented numerous technical problems and resulted in the development of specialized techniques. Initially, these effects were observed by measuring the fluctuation of the free water surface in wells. The current technique employs high-resolution pressure transducers deep in the water column. Pneumatic packers may be used to restrict the movement of water into the well. Data are recorded on high-speed oscillographs.

Notes: 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.

Notes: Pumping test data from a single well were used to estimate aquifer volume affecting drawdown. After four days of pumping from a 240 feet thick welded tuff aquifer in southern Nevada, the volume of the wedge-shaped mass tested was estimated to be about 15.6 billion cubic feet (440 million cubic meters). The field coefficient of permeability of the aquifer is 275 gallons per day per square foot.

Notes: In Southern California's San Bernardino Valley a unique experiment is being performed by a local water district, the State government, and a private industry. Both the experiment and the organizational arrangements for getting the job done are the subject of this paper. The experiment is the application of systems analysis technology to water resource management. The organization is formed by a combination of contracts and cooperative agreement between private and government agencies. The result is a favorable environment for the development of effective water resource management strategies.The San Bernardino Valley is similar Co many areas in the world where water resource management reduces to the allocation of locally available ground water and potential imported water resources. This paper outlines in detail the analysis tools and long-range planning needs of effective ground-water management strategies.

Notes: Coal mining in Appalachia has degraded both the surface and ground water. During mining, ground water is drained from the rocks and the pyrite associated with the coal beds is exposed to air. Oxidation of the pyrite produces high iron ana sulfate concentration and a low pH in the water. Some of this polluted water flows directly into nearby streams and some moves into the ground-water system. When the latter occurs, the iron concentration can increase up to several hundred mg/1 and the sulfates to over one thousand mg/1. Unfortunately, in most cases the cessation of mining does not stop the ground-water pollution, and it can take many decades before the ground water again becomes usable.A detailed study of the effects of coal mining on ground water was conducted in the Toms Run drainage basin in northwestern Pennsylvania where coal mining and oil and gas well drilling have occurred for almost 100 years. The rocks of Mississippian and Pennsylvanian Age produce a multiaquifer system–three major aquifers separated by siltstone and shale beds (aquitatdes). The oil and gas wells act as a conduit system permitting acid mine drainage to move downward from the strip mines to underlying aquifers. It then moves laterally down dip and discharges as springs. The acid mine drainage adversely affects the ground-water quality by increasing the iron and sulfate content of the water especially in the vicinity of the strip mines.

Notes: The measure of earth resistivity is a possible means of detecting and outlining zones of ground-water contamination where a resistivity contrast exists between contaminated and unconcaminated ground water.As a preliminary evaluation of the use of electrical resistivity for defining zones of contaminated ground water, five sites on Long Island and three sites in western Texas were examined. The surveys at three of the Long Island sites and at one of the western Texas sites were at least partially successful in their objectives. The lack of success at the other sites is attributed to the particular physical conditions that existed.Further effort toward developing electrical resistivity as a method for evaluating variations in ground-water quality is encouraged.

Notes: An aquifer test and analyses of water samples, showed that the anomalous water quality of a municipal well was caused by leakage from a nearby abandoned well tapping another aquifer.

Notes: Electric-analog or digital-computer models are used to compute the effect of ground-water withdrawal or recharge on streamflow. The results can be generalized on a map showing lines of equal elapsed time. The lines indicate the time of recharging or discharging that is needed to affect the streamflow by a given fraction of the amount pumped or injected. The generalization is based on the similarity in shape of the relations between pumping time and stream depletion for (1) semi-infinite homogeneous aquifers drained by a straight, fully penetrating stream, and (2) complex heterogeneous aquifers. Response curves from a model reflect the combined effect of stream sinuosity, irregular impermeable boundaries, areal variation in aquifer properties, and imperfect hydraulic connection between the stream and aquifer. The elapsed-cime lines are identified by sdf (stream depletion factor) values. These values can be calculated from observations made on an electric-analog model and then may be used in a digital-computer program for determining the effects of ground-water pumping or recharge on streamflow.

Notes: Hydrologic systems in arid lands normally include a recharge area in mountains and a discharge area in lowlands often with an intermediate area of lateral flow between recharge and discharge areas. This system is often modified by local geologic, climatic, and physiographic factors. Most water-supply, contamination and disposal problems arise from a combination of features superimposed on this system by concentration of population and agricultural activity in the discharge areas. Also most of our data on the system comes from the lowlands and little data is available from the recharge areas.In the Great Basin two general categories of ground-water flow systems are recognized: (1) local flow systems where drainage areas are usually small, flow paths are relatively short, interbasin flow is uncommon, springs have large fluctuations in discharge, water temperature is low, and concentration of Na, K, Cl, and SO4 is low, and (2) regional flow systems, where drainage areas are large, flow paths long, interbasin flow common, springs have large discharge, and the water is characteristically of higher temperature and contains higher concentrations of K, Na, Cl, and SO4. Hydrologic approaches used, in addition to conventional methods, include hydrologic budget, water-potential, and water-chemistry studies. Although detailed delineation of most flow systems in Nevada has not been accomplished, integration of hydrologic, geologic, and chemical methods allow approximate portrayal of many systems, both local and regional.Adequate methods upon which to base planning for optimum development of water resources in desert basins are now available. A conceptual model of optimal ground-water reservoir development illustrates how to determine optimum use of storage and perennial yield provided the use to which the water is to be put and the time of withdrawal are known.

Notes: In 1965, a ground-water recharge facility was constructed and placed in operation to forestall an impending water shortage at Minot, North Dakota. The facility is unique in that the rate of recharge to a buried sand and gravel aquifer is augmented by perforating an overlying bed of clay using hydraulic connectors (gravel-filled bored holes) in conjunction with an open-pit excavation. The connectors were drilled by typical well-boring techniques and the open pit was excavated by common construction methods. The recharge technique made it possible to add about million gallons per day of water to underground storage with a total capital investment of about $200,000. The alternative originally proposed was a 50-mile long pipeline to Garrison Reservoir, at a 1959 estimated cost of $12,000,000. The recharge technique employed at Minot should have wide application in the ground-water industry in areas where natural recharge to permeable deposits is impeded by overlying beds of low permeability.

Notes: A two-dimensional, passive element electric analog model was used to determine the spatial distribution of natural ground-water recharge in the Santa Cruz River basin of southern Arizona. Existing records were used to draw a ground-water level contour map of the area in its undeveloped condition. The model was made to duplicate these contours by varying inputs from known locations of recharge. Recharge distribution as determined by the model was consistent with previous estimates, but no direct correlation was found with the contributing drainage area.

Notes: The tidal efficiencies of wells tapping the principal artesian aquifer in Glynn County, Georgia decrease with distance from the influencing tidal body and also decrease with well depth. Although the magnitude of water-level fluctuation of these wells is largely dependent upon the distance to a large tidal body, the time of a high or a low water level in the wells is mainly dependent upon the time of a high or a low tide in a small, nearby tidal body. A modified formula for computing tidal efficiency is developed:〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT24:GWAT_24_mu1"/〉 From this formula, tidal efficiency can be calculated rapidly and easily

Notes: A totally new concept, called the Deep Tunnel Plan for Flood and Pollution Control, is being implemented by the Metropolitan Sanitary District of Chicago. The plan envisions temporary storage of combined sewer overflows in a system of tunnels excavated in solid rock, deep under the City. After the end of a storm, the stored water would be pumped to the surface where it would be treated to remove pollution before being discharged into the waterways.Early planning studies indicate that the most favorable location for the tunnels is the Galena-Platteville Dolomite which is the uppermost member of the Cambrian-Ordovician aquifer. The protection of this highly-developed aquifer from any possible contamination is therefore mandatory for the feasibility of the Deep Tunnel Plan.Preliminary investigations using an electric analog model, constructed on the basis of available data, indicate that aquifer protection can be provided by a system of recharge wells which would maintain flow into the tunnels at all times. Further detailed studies are in progress to verify and refine those preliminary conclusions. These studies include (a) detailed exploratory drilling; (b) controlled aquifer tests in selected zones; (c) pumping tests for specific capacity in the zone to be tunneled; (d) recharge injection tests; and (e) analog model analysis for future effects of the tunnels and recharge operations.

Notes: The interdisciplinary graduate program in hydrogeology at the University of Idaho is described. The curriculum is structured to permit the design of individual study programs which are in keeping with multiple use concepts. Flexibility sufficient to permit courses to be taken in several fields which support the students' major area of research is provided. This flexibility is maximized by the offering of two degree options. Discussion of a number of the research projects at the University illustrates several of the types of problems now being studied.

Notes: The University of Connecticut well field is located in a sand and gravel ice-contact stratified drift aquifer which fills the Fenton River valley to a depth of about 60 feet. The water that supplies these wells consists of captured ground-water underflow which would normally discharge into the Fenton River, and water induced directly into the aquifer from river flow by pumping. Measurements of streamflow made at three weirs installed in the Fenton River adjacent to two of these pumped wells show the influence of wells on streamflow. Approximately 34 percent of the water pumped from the wells was stolen from the river via induced streambed infiltration, although this figure varies in accordance with pumping. Water-level measurements in 30 observation wells installed in the aquifer around the pumped wells show that the cones of depression spread underneath the river, following coarse-grained partially buried eskers. The fact that the water table is detached from the river and is below the streambed near the pumped wells is explained by the low vertical permeability of the streambed in contrast to the horizontal permeability of the rest of the aquifer. The streambed is unable to recharge the aquifer with as much water as the aquifer can carry away. Time-drawdown pumping test plots show no effect of the river.

Notes: A resistance network analogue is used to study the early stages of a pumping test in an unconfined aquifer. The results are compared with an alternative analysis due to Boulton (1965) and a good agreement is obtained.Unlike the theoretical analysis the analogue technique is versatile and can easily be used to study pumping tests with nonidealized boundary conditions, e.g., partially penetrating wells can be simulated. Thus the analogue method of analysis could prove to be a more realistic method for studying pumping tests than standard analytical techniques.

Notes: Coarse granular deposits in preglacial river valleys are an important source of ground water on the Canadian prairies. Such an aquifer can commonly be modeled by an infinite-strip leaky-artesian aquifer. Test results can be analyzed, future drawdowns predicted, and safe yields estimated by applying the standard leaky-artesian formula in conjunction with image-well theory, making due allowance for well-loss factors.This paper develops basic formulas required for safe yield estimation for an array of n wells located on the axis of an infinite-strip leaky-artesian aquifer. In general, determination of safe yield for each well depends on the solution of n simultaneous linear or nonlinear equations. For certain symmetrical arrays, however, the number of equations to be solved is approximately halved. A linear equation will apply for any well if flow adjacent to the well bore always obeys the Darcy law for all pumping rates of interest. If all n equations are linear, they may be solved by the methods of matrix algebra; if not, a trial-and-error solution must be adopted.The method is illustrated by an application to a 6-mile stretch of a buried-valley aquifer near Edson, Alberta. The numerical coefficients in the system of equations are first derived and the equations then solved to obtain estimated 20-year safe yields for well arrays containing up to 38 equally spaced wells.

Notes: In 1966 more than 50 billion gallons of water was pumped daily from an estimated 10 to 15 million water wells in the United States. This was more than one-sixth of the national withdrawal of water. On the basis of past rates of increase, a much greater future use of ground water is suggested. Our annual investment in water wells is one-half to three-quarter billion dollars, not including pumps and plumbing. In 1964 approximately 436,000 new wells were drilled; however, less than 1 percent of these wells were logged by any geophysical means. The application of _ge_o.phy.sical well logging to ground-water hydrology is comparable to its use in petroleum exploration in the 1930's; however, we can take advantage of equipment and interpretation techniques developed in the oil industry that are available now for use in ground-water investigations.Although most petroleum well logging techniques may be utilized in hydrology; modifications in equipment and interpretation are necessary because of basic economic and environmental differences between petroleum and ground-water evaluation. If logging is to be widely applied to ground-water exploration and evaluation, the expense of equipment and services must be reduced. Fortunately, this can be accomplished, because most water wells are not as deep as oil wells and the temperatures and pressures are lower.The Water Resources Division of the U. S. Geological Survey is conducting research on the application of borehole geophysics to ground-water hydrology. The following logging devices are utilized in the evaluation of ground-water environments: spontaneous potential, resistivity, gamma, gamma-gamma, neutron, radioactive tracer, flowmeter, caliper, fluid resistivity, gradient and differential temperature, and sonic velocity. Lightweight logging sondes and control modules are operated by one man, either on a vehicle-mounted 6,000-foot logger or on a suitcase-mounted 500-foot logger. An inexpensive magnetic tape system has been developed and is used routinely for log recording and playback.If commercial well logging service is to be widely used in ground-water exploration and development, water well contractors, and State and municipal agencies must be educated on the advantages of obtaining more information from each hole drilled. It will be necessary also to demonstrate how well logging can provide much of this information. In addition, the well logging industry must adapt their equipment and services to the requirements of ground-water hydrology. The need for additional logging capability in this field exists at the present time and is expected to increase. Hopefully industry will be able to fill the gap.

Notes: A shallow, wide spread perching layer was isolated in the alluvial profiles of western Fresno County, California. Geologic and hydrologic interpretations are given, based on field and laboratory measurements of the physical properties of this layer. Some of the approaches investigated included using existing electrical logs from irrigation wells, head loss observations in wells and piezometers, core drilling, and core analysis. Differences in alluvial profile permeabilities are shown which result in perched water under the existing field flow conditions. The quantity of vertical flow through the layer is estimated using core permeabilities and hydraulic gradients observed in the field.Hydraulic properties and descriptions for the perched zone are presened which can be used to delineate profile flow limitations at other locations in the San Joaquin Valley. The study may be used in estimating the rate at which this perched water table could rise If, in the future, imported water and changes in irrigation patterns cause a large quantity of water to flow vertically.

Notes: The most commonly practiced method of artificial recharge at present is through basins. This spreading method may not be physically feasible or practicable if land values are high or a shallow, densely compacted layer forms a barrier impeding the direct downward percolation of the ponded surface water.For the case of the latter condition, alternative methods of wells or trenches dug down to the pervious aquifer and backfilled with gravel have been investigated. These were explored from the standpoint of construction and operating cost and hydraulic efficiency as influenced by such factors as the depth to the aquifer, the thickness, depth of saturation, permeability and specific yield of the aquifer, interference of closely spaced wells and duration of continuous operation of the wells or trenches. Furthermore, effects of bacterial growth and chemical composition of the recharge water on the hydraulic performance of wells or trenches are discussed.An economic comparison based on field conditions in a prospective recharge site at Stockton, California, is used to illustrate the developed criteria for relative effectiveness of the two methods.As a general conclusion, it was found that while recharge through trenches would be more efficient hydraulically and economically for the case of very shallow subsurface barriers, wells would become more competitive as the thickness of an impervious top layer increases.

Notes: The horizontal viscous flow model with “infinite” areal extent can be used for almost any well flow problem whether two-dimensional or three-dimensional, steady or nonsteady, single aquifer or multiaquifer. This model can also be used in the field of soil mechanics for subsurface drainage problems. The design includes scale model analysis and the application of conformal mapping techniques in order to simulate an ideal aquifer. Construction, calibration, and test procedures for the model are described. The apparatus has proved to be both a valuable research tool and an excellent teaching aid.

Notes: Water-supply problems in Spain have become acute during the past decade owing to expansion of industry, construction of modern houses and apartments, and development of a tourist industry. A training program in ground-water hydrology and geology was established three years ago in Barcelona to help supply personnel who would be able to cope with these problems. Training is also given to foreign nationals, a total of nine countries having been represented to date. Part of the success of the school rests on the fact that a large variety of ground-water problems exist in the vicinity of Barcelona. Students obtain a firsthand knowledge of sea-water intrusion, aquifer-testing techniques, agricultural and municipal degradation of water quality, and drilling and exploration techniques within a wide variety of rock types.

Notes: A well-designed and calibrated orifice meter is an accurate and inexpensive measuring device for flow. Endline orifices can be calibrated at work sites by solving an equation that interrelates easily measured dimensions of the orifice and outflow.

Notes: 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.

Notes: The planned development of an individual water supply from a group of wells must take into consideration several controllable and uncontrollable factors. The uncontrollable factors may include aquifer coefficients of transmissibility and storage, aquifer boundaries, static water level, aquifer depth, recharge capabilities, and competing users. The controllable factors often include the acreage allocated to ground-water development, well locations, and pumping rates. Well-field design is oriented mainly toward proper selection of the controllable factors.Water requirements, the cost of water and the life of the well field are related to limitations of acreage, draw-down of water level, and investment in pumping and transmission facilities. All of these factors, in turn, are influenced by the location of individual wells with respect to one another.Well-field design calculations involve the combined interference of water level drawdown among the various wells in the field. Repeated computational trials for various numbers of wells and well spacings may be required. Calculations using conventional methods are, in most cases, rather time-consuming.The final design decision can be approached quickly if it is assumed that the wells have regular spacing. Through the use of a simple formula and table developed in this paper, a given well-field problem can be calculated in a few minutes with a slide rule. When well spacing deviates appreciably from the regular spacing assumed, the final design calculations should be made with computer techniques.

Notes: This article contains a summary of a few disease out-breaks caused by ground-water contamination, and the difficulties in designing and monitoring for effective quality control. There is a discussion of problems associated with large basin recharge with treated sewage. For instance, do we have adequate microbial indicators? Or will the nitrate concentration build up if there is a semiclosed circuit involved? Chlorination of well water withdrawn for domestic use is advocated as good insurance for microbial control.

Notes: A new design method for deep well dewatering systems is given. The method analyses three dimensional flow to the multiwell systems by considering the two end points to the initial fast phase of water table fall. The method is applied to a dewatering case history and proves to be successful.

Notes: A new method of determining aquifer storage coefficients has been developed for use in operations involving ground-water recharge through wells. This work evolved from a research project dealing with the fate of DDT and nitrate in the Ogallala Aquifer in the High Plains of Texas.A tritium tracer was used to determine the detention time of the recharge water passing through a saturated volume of the aquifer. Tracer behavior was formulated ‘mathematically and verified by model simulation. The formulations provide a graphical solution for the detention time from which the storage coefficient may be calculated.The method will have immediate value in establishing storage coefficients of aquifers, such as the Ogallala, where plans for importation and distribution of supplemental water involve utilization of underground storage. Regarding water-table conditions, this method promises to produce more reliable storage values than have been obtained from pumping tests.

Notes: Heavy development in certain areas of the United States and the growing shortage of additional, readily available water supplies therein have forced planners and hydrologists to resort progressively to more elaborate water-supply systems. Among the most elaborate and most expensive systems proposed to date are the various plans for. transferring water toward the south from northward flowing Arctic rivers. A considerable portion of this water would be utilized for the expansion of already heavily urbanized areas.Meanwhile, many of the densely populated areas experiencing water shortages are subjected to other, perhaps more complex problems which appear to be, at least in part, a product of their increasing size. Therefore, the expenditure of large sums to supply them with water for indefinite growth appears to merit scrutinous study.An alternative approach designed to minimize both water diversion costs and problems associated with over-populated areas is the stimulation of development in carefully selected regions well endowed with water and other natural resources. One such area and several of its attributes are discussed herein.

Notes: A gravity survey covering 250 square miles and including the Walnut Gulch watershed at Tombstone, Arizona has been conducted. The watershed is one of the experimental areas of the Southwest Watershed Research Center, Agricultural Research Service in Tucson, Arizona.The gravity survey method was selected as the geophysical method that would give a regional picture of the subsurface geology before making extensive surveys by the seismic. refraction method. Basically, the gravity survey method detects and measures variations in the earth's gravitational force. These variations are associated with changes in rock and alluvium density near the surface. Many geologic structures of interest in watershed ground-water hydrology cause disturbances in the normal density distribution which give rise to anomalies.The geology of the watershed is typical of Basin and Range province and contains deep basin fill deposits surrounded on the east, south, and southwest by igneous intrusives, volcanics, and sedimentary rocks. Concealed border faults may have a decided effect on the hydrology of the watershed.Four base stations were established and 360 gravity stations occupied by a Worden Educator* gravimeter loaned from the Geophysics Laboratory of the University of Arizona. Bench marks and large scale topographic maps served as control. Raw field data were reduced to the simple Bouguer anomaly values through the use of a computer program.The gravity survey reveals a 16-mgal. gravity low over the east-central portion of the watershed. This low is interpreted as indicating that about 3200 feet of low density alluvium underlies the area at this point. Gravity highs are associated with mountain ranges and igneous plugs where the more dense rocks occur.

Notes: Recent increased interest in subsurface disposal of industrial liquid wastes in Illinois has shown the need for both geohydrologic and engineering criteria and State regulatory policies for evaluating proposed installations, with the object of protecting other resources, chiefly potable ground water.Favorable geohydrologic conditions–specifically the presence of a variety of permeable formations that contain nonpotable water and are well confined from shallow to great depth–make waste disposal by wells feasible in much of the southern two-thirds of Illinois. Natural safeguards permit disposal wells to be planned with conventional engineering precautions and only a minimal program of preoperational testing.In much of the northern third of the State, the permeable rocks contain potable water to great depth, and there is moderate to high development of the ground-water resource because of urban and industrial concentration. Exhaustive testing, substantial proof of acceptable site conditions, and incorporation of optimum engineering safeguards are considered necessary before the State regulatory agency can authorize installation.

Notes: Comparative costs of ground water were needed for comprehensive planning of water resources development in the Susquehanna River basin in order to appraise the feasibility of alternative sources of water supply. Log-normal plots on logarithmic-probability paper that represented specific capacities adjusted to 180 days of pumping were used to estimate well yields and costs of obtaining the ground water from each of 65 potential aquifers. The 25, 50, and 75 percent probability of occurrence of the specific capacities of successful wells were used in the calculations. The estimated well yields at these probabilities of occurrence were obtained using hypothetical well designs and selected drawdowns. Ground-water costs for the estimated or design yields were calculated using amortized costs of well construction, electrical power costs, and maintenance costs, all obtained from standard sources.The calculated well yields and costs for the 25 to 75 percent probability interval range from 15 to 9,000 gpm (gallons per minute) and from $0.004 to $0.11 per thousand gallons of design yield. The yields and costs group according to aquifer rock type. The calculated costs decrease with increasing well yield and the available yield depends upon the aquifer rock type available. Representative costs per thousand gallons of design yield for selected yields from aquifers composed of different rock types analyzed are: 50 gpm −$0.060 for shale and interbedded sandstone and shale, and $0.050 for metamorphic rock; 100 gpm - $0.043 or shale and interbedded sandstone and shale, $0.037 for metamorphic rock, and $0.032 for carbonate rock; 500 gpm—$0.020 for sandstone, $0.015 for carbonate rock, and $0.012 for glacial sand and gravel; and 1,000 gpm —$0.009 for glacial sand and gravel. Differences in cost to obtain the same yield from different rock types are primarily due to differences in electrical power costs as determined by differences in pumping water levels.If used with caution, the generalized yield and cost estimates for aquifer rock types may have usefulness in estimating ground-water costs and yields in similar humid areas. They are primarily useful for planning and comparative purposes, but not for the actual design of engineering Projects.

Notes: Hazards to ground water may result from adding to water which may infiltrate the soil, or to the soil through which water percolates, wastes from man's life processes; his industrial and commercial activity; or his use of water, fertilizers and pesticides in agriculture. From experimental data it is evident that particulate matter, including bacteria and viruses, do not move far with percolating water in a soil system. The chemical products of biodegradation of organic wastes, however, with a few exceptions such as phosphates, move quite freely and hence reach ground water. Since they are no different than the compounds found in ground waters the effect of domestic use of water is generally to increase the concentration of salts normally present in such waters. From the vast spectrum of compounds produced by the chemical industry and used in industry and commerce comes hazards to ground-water quality such as metal ions, phenols, tar residues, brines, and exotic organics which may through accident, carelessness or waste-water discharge contaminate ground water. Mineralization with nutrients and soluble soil fractions, and possibly, pesticide residues are the hazards from agricultural use. Leaching from solid waste landfills is possible under poor long-term management and might involve chemicals, iron, and various earth minerals. It is concluded that the most serious hazard is the buildup of dissolved solids to levels inimical to beneficial use.

Notes: In this paper, basic design principles for disposal wells are set out and then exemplified by discussion of two recently constructed wells for disposal of very corrosive refinery waste. One well is designed for 700 gpm of waste containing 4200 ppm hydrogen sulfide. The other is designed for 50 gpm of waste containing 32 percent hydrochloric acid. Both wells are in the Gulf Coastal Plain and are completed in a deep, unconsolidated fine sand containing salt water. Screens fabricated from exotic metals were incorporated in the design. Unique combinations of materials were used for the casing.It is pointed out that oil field type completions are often used in disposal well construction, which usually results in low specific injection capacity, high operation and maintenance costs, and short useful life of the hydraulic structure.

Notes: A supply of good-quality water is our most critical natural resource, for our municipal growth and an increasingly healthy industrial base. The economic viability of our farms depends upon it. The locating and development of this resource is the province of the hydrogeologist.The hydrogeologist is more than just a ground-water geologist, for he deals with water in virtually every geologic situation, above-the water table as well as below it, and at the surface as well as underground.The hydrogeologist must of course possess the necessary background in the allied sciences and fluid mechanics, and should know something of the social science aspects of water decision-making. He must be able to work closely with the civil and sanitary engineers, and he must be able to make himself understood to planners.In performing his work he has a responsibility to society, and this is equated with a responsibility to his profession. As Martin Van Couvering has said, the respect that our profession deserves “cannot be bought or solicited; it has to be earned by the right kind of performance.”

Notes: One of the deepest water-exploration wells in the southeastern United States was completed in 1966 at Jacksonville, Florida. It was drilled to a depth of nearly 2,500 feet to supply geologic and hydrologic information on the deeper unexplored part of the Floridan aquifer. This aquifer consists of a series of water producing zones separated by nonproducing zones. An important new fresh-water producing zone was found, and the contact between the fresh water and salt water was located. The well was completed in three separate zones so that it could be used to monitor the the deeper part of the aquifer to detect any salt-water encroachment. This paper describes the objectives, techniques, and results of drilling the test well.

Notes: A rapid graphical technique for the determination of aquifer transmissibility from a variable discharge pumping test is presented. The data required include the variation of discharge with time during the pumping test and a record of the recovery ar an observation well after the well was shut off. An example using a synthetic well data is provided.

Notes: Comparison of the analysis of 3 and 4 day pumping tests with the analysis of water-level changes due to 18 years of pumping suggests that experience in an area can be a critical factor in determining the transmissivity and storativity of an aquifer.

Notes: The rapidly increasing development of ground-water resources in northeastern Illinois has brought about regional and local problems of water supply, thus creating considerable interest in the feasibility of artificial recharge as a partial solution. Artificial ground-water recharge is considered as a partial solution to regional and local problems of water supply in the primarily metropolitan region of northeastern Illinois. Five artificial recharge facilities are now in operation in the area; their average annual recharge rates range from 25,000 to 395,000 gallons per day (gpd). Several additional areas where artificial recharge may be feasible are identified on the basis of criteria established for the region.An initial study in the Park Forest-Chicago Heights area indicates that recharge to the Silurian dolomite aquifer, the source of water supply in the area, is feasible. This study provides guidelines to aid in additional studies of artificial recharge in northeastern Illinois.

Notes: Two case histories are presented which illustrate that by analyzing drill cuttings or bailed samples, by knowing total depth of a test hole and position of the static water level, and by studying the driller's log, not only can a well's yield be predicted—but also drawdown may be predicted for any well in advance of a pumping test.The estimation of specific capacity (gpm/ft of drawdown) is invaluable in well design, particularly in the United States, where drilling contractors work rapidly and efficiently. Knowledge of probable specific capacity can aid in recommending proper screen length, diameter, slot width, and setting. It will enable cost estimates for proper pump size to be made, for casing requirements to be determined, and also for ultimate well diameter and depth to be determined. Test-pump setting can also be anticipated.Case History No. 1 illustrates the above techniques, and how a new well was drilled, developed, designed, and completed adjacent to a poorly designed and equipped water well. The new well proved to be nine times more efficient (i. e., “better”) than the old well. Reasons for this improvement are shown, and the two wells are compared and contrasted.Case History No. 2 shows data from a constant-rate pumping test following calculation of a well's specific capacity using estimates of aquifer permeability. Analysis of dynamic water-level recovery measurements resulted in a transmissibility of 16,150 gpd/ft compared to an estimated 16,000 gpd/ft from a visual inspection of sand analysis grading curves. The well's specific capacity was estimated to be between 8.4 and 8.9 gpm/ft of drawdown. The measured specific capacity was 8.35 gpm/ft with an efficiency of 85 percent. Actual permeability was 230 gpd/ft compared to the estimated 228 gpd/ft2!Six figures are included showing well construction details, sieve analysis curves, a semi-log plot of recovery measurements obtained during an aquifer pumping test, and graphic representations of approximate permeabilities for granular materials ranging from clay/silt to fine gravel. Six tables give characteristics of samples recovered from two test wells, permeability estimates of the disturbed samples, approximate permeabilities of various granular materials, and specific capacities for 100 percent effective water wells with varying diameters, coefficients of storage, and pumping periods. Three photographs further illustrate the principles enumerated.The methods described can give acceptable results (although they may not be as spectacular as the two detailed case histories) if sound judgement is used; if local conditions are somewhat known; if sampling methods are described; and if the procedures are not abused by expecting extreme accuracy. A reasonable estimate, or perhaps, just a close scientific “guesstimate” is all that should be hoped for by the hydrogeologist and his client in predicting well yields. But these techniques are a great advance over the“forked peach stick” philosophy still used for similar purposes by pseudo-scientists in the United States and foreign countries (although no cases where a dowser or “water witch” has successfully predicted drawdown in addition to yield have come to the attention of the writer).The data in this report are derived from approximately 500 wells or more designed by the author in 26 States and in many locations abroad. Rather good success has been obtained regarding close correlation between estimated and measured specific capacities from a variety of geologic environments and aquifer parameters.

Notes: The intensively irrigated Arkansas River Valley in Colorado is underlain by a valley-fill aquifer resting in a U-shaped trough cut in relatively impermeable Cretaceous rocks. Ground water is pumped to supplement surface water; in the last 10 years pumping has more than doubled. Ground water is closely related to the Arkansas River; percolation from irrigation recharges the aquifer, which discharges into the river. Pumping has resulted in a reduction in streamflow because it intercepts water that ordinarily would have reached the river. The 1,500 irrigation wells in the Arkansas Valley withdrew 230,000 acre-feet of water in 1964.An analog model is being used to evaluate the relation of ground water to surface water and to predict effects of changes in water management. The model, simulating a 150-mile reach of the Arkansas Valley (Pueblo to the State line), has a resistor spacing of 8 per modeled mile. The framework for the model was a transmissibility map; transmissibility ranges from less than 50,000 to 700,000 gallons per day per foot. Specific yield averages about 0.2. Hydrologic boundaries, such as the Arkansas River, and the bedrock valley-fill contact were simulated. Applied water, precipitation, evapotranspiration, and ground-water pumping were the independent variables programed. The model is being verified by comparing predicted changes in water level and river discharge with observed changes.

Notes: A method is presented for computing maximum drawdown in a well being pumped intermittently but in accordance with a regular sequence of fixed periods of pumping at constant discharge followed by fixed periods of rest. The method is extended to allow for interruption of the basic pattern by occasional changes such as the elimination of the pumping phase from certain individual cycles.

Notes: The frequency distribution of dissolved-solids content of ground waters in geologically and climatologically homogeneous terrane units commonly approximates a log-normal distribution. A graphic logarithmic transformation is de-scribed which permits rapid calculation of approximate values for the mean, standard deviation, and coefficient of variation. Statistical parameters calculated by this method show good agreement with known physical conditions in the terranes studied and are precise enough for use as a mea-sure of variability of quality of ground waters for national planning purposes.

Notes: Photogeologic study has been useful in the location of ground-water sources in the state of Sao Paulo, Brazil, and could be important to the investigation of water resources in other areas.Until 1963, it was believed that large areas of the state were unsuited for the location of ground-water wells (as in pre-Devonian crystalline formations) and others weregenerally considered too hazardous (Paleozoic and Tertiary: sandstone lenses in shales). Since that time, when aerial photographs of the whole state became available, the authorhas verified an earlier hypothesis of his own that there are actually very few areas in the state which do not have suitable locations for water wells, and that photogeology is a most valuable method of prospecting.The water sources are parts of highly developed fault/ fracture systems which are identifiable on aerial photo-graphs, at least in this warm humid climate with dry season. Over the fractures the rocks are deeply decomposed, the debris are removed in the rainy season, and existence of water in the dry season promotes higher and denser vegeta-tion along aquiferous fractures, which usually are located in deep straight-line valleys. Even where competent beds are overlain by more than 100 m of unconsolidated strata, many discontinuous nets of parallel straight-line segments are detectable probably because all fractures are really faults with significant throw.To be most effective, the method requires stereoscopic study of areas having dimensions on the order of 10 × 10 km. The selection of locations for drilling should be sup-ported by analyses of the dip of fracture planes (hade) and by other geological-geophysical methods, especially by subsoil electrical resistivity surveying.

Notes: The purpose of this paper is to stimulate additional interest in the hydrogeologic aspects of the International Hydrological Decade (IHD) program and to urge the full cooperation and participation of hydrogeologists in the research and educational activities of the Decade. The IHD, 1965–74, will strengthen the scientific base for water use and conservation, stimulate education and training in hydrology, and improve the ability of developing and developed countries alike to cope with their water resources problems. UNESCO provides an international intergovernmental umbrella and the Secretariat for IHD. More than 90 Member States of UNESCO are participating in IHD and a majority of these have established National Committees for IHD.The UNESCO/IHD program will consist primarily of activities of participating countries themselves, catalyzed, coordinated, and supplemented by international intergovern-mental agencies and scientific associations. Activities of Member States of UNESCO include: collection of basic data through data analysis and applied hydrology; applied and basic research; continental and global water balances and the global hydrological cycle; establishment of hydrological networks and the development of technical competence; fundamental research; definition of principal hydrological features of countries such as precipitation, discharge of water, sediment and dissolved load, evapotranspiration, distribution of tritium in precipitation, surface and ground waters; experimental basin studies to provide insight on the interplay of environmental and hydrological parameters in a broad range of geological, climatic, and ecological conditions; distribution of water in the atmosphere, in lakes and rivers, underground, in permanent ice and snow and permafrost; studies of the rate at which water moves through the hydrologic cycle; use of orbiting satellites and remote sensing instruments for measuring phenomena in the atmosphere and at the Earth's surface and for relaying observational data; organization of egional advanced training and study courses and hydrological institutes; exchange of teams of experts, exchange of professors and research scientists; and organization of symposia and regional seminars.The US/IHD program focuses on the following five major objectives: (1) large-scale balances of water and water-borne material studies; (2) hydrological performance of river, lake, and ground-water basin systems studies; (3) studies of specific hydrological processes and their variations in time, and improvement of methods and techniques; (4) education and training; and (5) services providing coordination and administration support. These objectives provide a framework within which the scientific and engineering community can contribute to IHD. A provisional US/IHD program statement identified, among others, the following hydrogeologic activities: estimation of ground-water discharge to the sea, effects of variations in piezometric head on land subsidence, hydrology in limestone areas, radionuclide tracer studies, chemical behavior of ground water, and dispersion in moving ground water.Hydrogeologists are urged to submit proposals concerning activities for possible inclusion in the US/IHD program. The following seven criteria guide the formulation and inclusion of activities in the US/IHD program by the U. S. National Committee for IHD: (1) the activity is sufficiently fundamental or aimed at results so useful that it will interest all hydrologists; (2) the activity requires joint or coordinated work in two or more countries; (3) the activity concerns a problem whose solution and verification would be improved by work in two or more countries; (4) the activity concerns continental, hemispheric, or global phenomena or processes; (5) the activity requires action in international areas such as polar regions, international waters, and multi-national basins; (6) the activity involves the hydrologic use of earth-orbiting satellites; and (7) the activity involves intercountry exchange or visits of personnel (in some instances, the exchange or visit itself may be the main item of interest). Proposals may be of projects already in progress, for expansion or modification of on-going projects, or for new work. Proposals may be submitted as contributions, requiring no financial aid from or through the IHD; for endorsement by IHD as an aid in obtaining financial aid elsewhere; or, when funds become available, as IHD projects receiving financial assistance from the IHD. Further information may be obtained from: U. S. Na-tional Committee for the International Hydrological Decade, National Academy of Sciences, 2101 Constitution Avenue, N. W., Washington, D. C. 20418.

Notes: A type-curve method for determining anisotropy of unconfined aquifers, developed from electric analog simulation, is applied to drawdowns observed near, a well pumping from a glacial outwash aquifer at Piketon, Ohio. The coefficient of vertical permeability, P z'averaged 365 gpd per square foot. Computed drawdown for the pumped well, based on this value, differed by only a small amount from the observed drawdown. The coefficient of storage, determined from type curves for an image well system, averaged 0.20, typical of unconfined aquifers. Application of the method required a thorough knowledge of geohydrologic controls operating at the test site.

Notes: Criteria and factors are considered which affect the design of a Hele-Shaw viscous flow model for use in ground- water studies. Procedures and construction techniques for assembling such a model are outlined. Some of the advantages and drawbacks in using a viscous flow model are discussed, Three examples are used to demonstrate the use of the model

Notes: A nuclear (atomic) explosive, detonated at suitable depth below the land surface, appears to offer substantial advantages and economies as a tool in the development and management of water, under certain special hydrologic situations. It is appropriate, therefore, that we seek to understand not only the potentials, but also the limitations of such a detonation. This paper is a first, small step toward that end.Greatly over-simplified, what does an underground nuclear detonation do that it can become a tool of water development and management? Consider first a detonation at a depth sufficiently great that none of the products vent to the atmosphere. Minimum depth for such “containment,” in feet, is close to: 〈displayedItem type="mathematics" xml:id="m1"〉1〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT13:GWAT_13_m1"/〉in which W = explosive energy, in kilotons.

Notes: In this short paper, selected water quality problems and the research efforts aimed at their solution supported under P. L. 88–379 (the Water Resources Research Act of 1964) at State Water Research Centers are presented. The water quality problems and associated research efforts presented are not necessarily of high priority with respect to the national needs for water quality knowledge; rather, the problems and research discussed are presented as typical of local or regional situations and as examples of the awareness of State Water Resources Research Centers to the local or regional needs for improving water quality management.Selected water quality problems associated with urban- ization, modern agriculture, industry, recreation, and natural environments are discussed with respect to the needs for new knowledge leading to improved management of water resources. Selected Water Resources Research Centers' projects with the objectives of discovering some of that new knowledge are discussed with respect to the research approach adopted by the investigators.

Notes: Maximum yields from minimum aquifers can be accomplished only by strict adherence to best known practice procedures while following the three necessary steps to well completion. These steps are well design, well construction and well development.In well design good practice begins with an accurate log and the obtaining and careful testing of formation samples. From such data, optimum depth, diameters, screen settings, and gravel pack gradations for expected yields can be selected.Well construction should incorporate equipment suited for the kind of formation, size of well, and depth to be drilled. It should be operated by competent and reliable personnel capable of faithfully maintaining all specifications and finishing in a reasonable time, with a well in which all measurements shown on the log are correct.Development techniques which are appropriate for the well, aquifer, and drilling equipment should be used, al-though it appears the high velocity horizontal jetting tool, used in conjunction with chemicals and regulated pumping, offers the most promise.

Notes: The nature and extent of movement of ABS (alkylben-zenesulfonate) and other sewage components through natural soils were studied in the laboratory and in the field north of Denver, Colorado. Small amounts of ABS and bacteria pass through soils and reach the zone of saturation, where they move laterally down-gradient several thousand feet. Total dissolved solids show little fluctuation during such movement, possibly because extracted solutes are replaced by other solutes leached from the soils during water infiltration.In laboratory studies Denver sewage-plant effluent was filtered through packed columns of 8 types of soils. ABS was not significantly removed by most of the soils; how-ever, muck, greensand marl, and residual basalt soil ini-tially removed up to 94 percent of the ABS. Some ABS was removed only after development of bacterial slime on the soils; subsequent infiltration caused leaching of the slime and its adsorbed ABS and other constituents. All soils initially removed about 90 percent of the bacteria within a few feet of travel, but a small percentage passed through the soil. Bacterial clogging occurred quickly in the fine soils but only in modest amounts in the coarse sand, even after three months of flow.Field studies included analyses of river and irrigation water contaminated from a sewage-plant effluent, and well water from selected sites down-gradient between unlined irrigation ditches and the river. Concentrations of ABS and bacteria were significantly reduced during infiltration of irrigation ditch water to the water table. As noted in the laboratory the concentrations of both of these contaminants can be reduced through soil filtering action. In addition there may be some dilution of the infiltrate by the ground water. Dissolved solids showed practically no change between the ditches and the wells.

Notes: A method for determining a spatially distributed set of ground-water withdrawals that maintains a regionally “optimized” potentiometric surface is presented. A goal-programing approach, in its quadratic form, is used to minimize the sum of squares of differences between the optimized surface and a “target” potentiometric surface. Constraints on withdrawals and recharge, imposed through a two-dimensional ground-water flow equation, and bounds on drawdowns assure that the withdrawal strategy developed is realistic and physically feasible. Application is demonstrated using data from the Grand Prairie region of Arkansas.

Notes: Relatively little work has been done using streamflow data as a means of estimating hydrologic parameters such as transmissivity and storativity. An approach to this problem utilizing the physical insight offered by electric analog modeling techniques has been developed with streamflow data from two small drainage basins in northwest Virginia. Streamflow modeling has produced regional estimates of the ratio of transmissivity to storativity, and results from each region indicate this ratio to be larger than expected. This discrepancy is resolved by assuming that the drainage basins contain only a small percentage of permeable rock, and this assumption suggests a further use of the model to estimate the percent of permeable rock in a watershed. The analog approach presented here shows potential for further development using digital computer methods.

Notes: Influences of limestone on physical and chemical characteristics of Abrams Creek in Cades Cove, Great Smoky Mountains National Park, were investigated from February to July 1977. Infiltration of stream water into subsurface permeable limestone conduits caused reduced and intermittent surface flow within the middle reach of the Cove. At the downstream (west) edge of the Cove, inflowing waters characteristically warmed the stream in winter and cooled it in summer and increased stream conductivity, total hardness, and pH. Management activities in the Cove did not appear to appreciably affect the chemistry of the aquatic system downstream relative to the large effects of limestone substrate.

Notes: In situ water-quality measurements, with respect to various ion and dissolved solids concentrations, have been closely approximated using open-hole borehole geophysical logs. Analyses have shown good correlation between water resistivity (Rw, as determined from the logs) and dominant ion concentrations sampled from a wide range of water quality in Tertiary carbonate and granular formations.Rw can be accurately determined by cross-plotting saturated formation resistivity (Ro), obtained from normal or lateral resistivity logs, against formation bulk porosity from neutron, density, or acoustic velocity logs. Plotting these data on Hingle Resistivity-Porosity Cross Plot (RPCP) paper with the proper matrix cementation factor (m, commonly 1.4 for unconsolidated sands or 1.6 for noncompacted Tertiary carbonates), will yield a graphical solution for Rw based upon the relationship Rw=φm Ro. The graphical technique also provides information concerning water-quality variations with depth, true matric resistivity, location of confining beds, and vertical changes in formation porosity.Once Rw has been determined, other ion concentrations can be estimated based upon chemical analyses of water samples from adjacent wells tapping a similar type water mass (i.e., calcium-bicarbonate, sodium-chloride water, etc.). Total dissolved solids (TDS), chloride, sulfate, potassium, sodium, magnesium, and hardness (as CaCO3) concentrations have consistently shown a high correlation with Rw.

Notes: A model to solve the inverse problem in ground water has been developed. The model consists of an unconstrained multivariable optimization algorithm and a ground-water simulation model. The optimization algorithm is a modified version of Newton's second derivative method. It is a ground-water-specific algorithm and was found to be more efficient than other more general unconstrained optimization algorithms requiring first- and/or second-order derivatives and those requiring no derivatives. The groundwater simulation model is based on a finite-difference technique but it can be replaced easily by a finite-element model. The results of an application of this model to a real aquifer are discussed in a companion paper titled “Inverse Problem in Ground Water: Model Application.”

Notes: Field studies along the southeastern shore of Trout Lake, Wisconsin, documented the presence of downward hydraulic gradients in a known discharge area as well as an anomalous distribution of seepage to the lakebed which deviates significantly from the generally accepted dogma that ground-water seepage rates decrease exponentially with distance from shore. A numerical ground-water model facilitated identification of the hydrologic control, namely the presence of a unit of high hydraulic conductivity, that accounts for the anomalous data, and is important for understanding the dynamics of the flow system. Field data including seepage measurements, visual inspection of lakebed materials and springs, and information obtained during drilling, indicate that a lens of coarse-grained material intersects the lake. However, the significance of the coarsegrained material was not fully appreciated until a ground-water model was used to simulate the flow system. The model indicated that the presence of the coarse-grained lens has a marked effect on the flow pattern in the nearshore area causing downward hydraulic gradients which divert ground water into the lens and cause the occurrence of a localized high-seepage area offshore where the lens intersects the lake. The numerical model predicts the anomalous seepage distribution noted in the field and the downward hydraulic gradients demonstrating that numerical models are practical tools for interpreting field data and for use in hypothesis testing.

Notes: A parameter identification (PI) procedure is developed and implemented with the United States Geological Survey's Method of Characteristics (USGS-MOC) model. The PI procedure can be used to estimate selected model parameters from limited observations by quadratic programming. The code combining the PI procedure and the USGS-MOC model has been tested by two numerical examples from a hypothetical aquifer. The test results show that the proposed algorithm can identify transmissivity and dispersivity accurately under ideal situations. The effects of using a simple characterization of the aquifer on parameter estimation and model are shown. Because of the improved efficiency in model calibration, extended application to field conditions is encouraged. However, it is cautioned that the interested users should be aware of the difficulties in field applications of PI, and it is recommended that sound engineering and scientific judgements are always needed in the use of the proposed, or any other PI method.

Notes: This paper illustrates several interesting effects of aquifer stratification on the results of two-well tracer tests by means of a simplified computer model. In the model, it is assumed that the aquifer is horizontal, confined, of constant thickness and porosity, and perfectly stratified in the vicinity of the test wells. The nonuniform advection pattern is taken into account in detail by the model, but the local hydrodynamic dispersion is completely neglected. This simplified model has been verified in part by comparisons with available analytical solutions valid for homogeneous aquifers and in part by comparisons with the results of a two-well field experiment of Pickens and Grisak (1981a) which was performed in a locally stratified aquifer. The applications of the model to several field situations with assumed values of the relevant parameters show that the concentration versus time breakthrough curve measured at the withdrawal well during a standard two-well test would be very sensitive to variations of the hydraulic conductivity in the vertical. Without the use of supplementary observation wells with isolated multilevel sampling points, the standard test would give little useful information about the hydraulic and dispersive characteristics of an aquifer. Factors such as the length of the tracer injection period, the use of recirculation and the physical size of the experiment all have a strong effect on the breakthrough curve measured at the withdrawal well, making the interpretation of field results difficult unless aquifer stratification is measured and properly taken into account.

Notes: . The use of a small packer in slug tests can improve the quality of time versus head level measurements, particularly during the important early stages of the test. The packer is placed in the piezometer below the static water level and inflated. Water is then added to the piezometer until it is full to the top of the casing. The packer is deflated and the times for the water level to reach selected depths are measured with an electric sonde.

Notes: .Values of transmissivity and storage commonly are derived for a nonleaky confined aquifer by manual curve matching of pumping-test data. Automatic matching of pumping-test data with the Theis type curve is possible using the method of least squares, provided the Cooper-Jacob approximation of the well function W(u) is considered. A FORTRAN program was developed to carry out this automated matching. Results derived from published data show that the method gives parameters close to the ones derived by the standard method of manual curve matching.

Notes: As more and more cases of ground-water contamination are reported, the public has become increasingly aware of the importance of preserving the quality of this limited resource, especially in areas totally dependent on ground-water sources. Although most of the attention is focused on pollution by organic chemicals, these compounds are responsible for a relatively small percentage of ground-water-related disease outbreaks. The majority of waterborne disease outbreaks are caused by bacteria and viruses present in domestic sewage. Septic tanks contribute the largest volume of waste water, 800 billion gallons per year to the subsurface, and are the most frequently reported cause of ground-water contamination associated with disease outbreaks. The U.S. Environmental Protection Agency has designated areas with septic tank densities of greater than 40 systems per mi2 (1 system per 16 acres) as regions of potential ground-water contamination. Numerous cases of ground-water contamination have been reported in areas of high septic tank density; lot sizes in these areas range from less than one-quarter acre to three acres. The single most important means of limiting ground-water contamination by septic tanks is to restrict the density of these systems in an area.

Notes: A hydraulic trap in the form of a purge well is proposed for the Forwell collector well K-71. The trap, which will protect well K-71 from contamination by contaminants migrating downgradient from the old Breslube waste disposal site, is based on a qualitative flow net obtained from a finite-element model of the Forwell Aquifer. The trap constitutes pumping at the position of observation well OW 9-80 at a continuous rate of at least 6.1 X 10-3 m3/s. The uniqueness of the trap lies in its simplicity and relatively low cost.

Notes: Waters from 91 springs in a 130 X 140 km area of west-central Arkansas were analyzed for all the major ions. The yearly flux of these ions in the rain and pure-water extract of the dry deposition 180 km north of this area was measured and assumed to represent the composition of the recharge to the ground water feeding the springs. Cation/Cl-flux ratios were used as a norm for the concentration of ions in the spring waters by evapotranspiration. Ratios above the norm were interpreted as ion exchange or rock dissolution into the ground waters. Ratios below the norm were interpreted as ion adsorption or, for Ca2+, CaCO3 precipitation processes. Na+ and Mg2+ are invariably above the norm. K+, NH+4 and H+ are invariably below the norm; whereas Ca2+ values are about equally divided between above and below the norm. Equivalents of cations above the norm and below the norm were compared for a number of springs to determine the main ground-water processes for each spring. The Na+/Cl- and K+/Cl- norms for the rain water form near-perfect minimum and maximum envelopes, respectively, of the Na+ vs Cl- plots of the spring-water compositions. This is due to the adsorption affinities of the soil for Na+ being low, and for K+ being high.

Notes: A numerical model was developed to simulate the behavior of two-phase immiscible fluids in ground-water systems for specific application to hydrocarbon spills and leaks. The model is a two-dimensional areal flow model using the finite-element method. A verification of the numerical model was performed using both an approximate analytical solution and a laboratory investigation. The verification results show that the numerical model adequately describes the behavior of immiscible two-phase flow within a coarse porous material.

Notes: Unsteady flow to a large-diameter well in a confined aquifer during recovery has been analyzed by discrete kernel approach. A family of type curves has been presented for different durations of pumping. These type curves provide a fairly accurate means of determining aquifer parameters from data of pump tests conducted in a large-diameter well. The replenishment of well storage at various times has been estimated.

Notes: Chemical analyses of wells penetrating the coastal aquifer of Israel indicate that the relative concentrations of sodium, calcium, magnesium, bicarbonate, and hydrogen species deviate considerably from the ideal mixing line between fresh water and sea water, as represented by the concentration of chlorides. Furthermore, deviation patterns were found to be distinctly different for areas of present sea-water intrusion, and areas from which ancient brines are still flushed. These differences, explainable in major part as the combined effects of cation exchange and carbonate equilibria, can in turn be utilized to distinguish between invading and retreating saline-water bodies, and identify their existence at the very beginning of the salinization process. Observed patterns are verified here in major part, with the aid of a single-cell simulation model.

Notes: Water samples were collected from 34 wells in the Claiborne aquifer in southwest Georgia. Land use/cover is principally forest, wetland, or agriculture. The aquifer is exposed surficially to the northwest but dips beneath confining beds to the southeast. The Claiborne aquifer is generally a fine- to medium-grained quartz sand becoming more calcareous downdip and to the east. Well water was analyzed in the field for pH, electrical conductivity, alkalinity, hardness, and temperature, and in the laboratory for Cl, NH4, NO3, total N, total P, ortho-P, SO4, K, Na, Ca, Mg, and Fe. Hardness gradually increases from 5 mg/1 updip to 162 mg/1 downdip and bicarbonate alkalinity follows the same trend reflecting variations in the aquifer lithology. Higher than normal nitrate concentrations (4-6 mg/1) are found in ground water in the exposed updip portion of the aquifer in areas where agricultural land use for cropland is high. However, in forest-covered areas, ground water in the exposed portion of the aquifer contains nitrate concentrations similar to the confined areas of the aquifer: less than 1 mg/1. Other chemical constituents measured do not show a discernible pattern of variation. One well near a fertilizer storage facility contains nitrate concentrations exceeding the Safe Drinking Water Standards, and other wells in the agricultural portion of the outcrop belt may seasonally exceed these limits.

Notes: The ground-water flowmeter system, model 3OL, manufactured by K-V Associates Inc., Falmouth, Massachusetts was tested under controlled laboratory conditions. The influence of slotted pipe schedule, slot orientation, backfill materials, endcap bags, isolated regions of high hydraulic conductivity, and channelization near the slotted pipe wall was measured. The physical concept of the flow-meter in an ideal configuration was analyzed, and with the aid of an analytical model, the significance of the thermal and hydraulic characteristics of the aquifer and backfill materials is clarified. Results indicate that the basic instrument response is linear, consistent, and predictable qualitatively in a laboratory environment. Analysis and measurements show clearly that very small channelization around a slotted pipe casing or between the slotted pipe and the probe endcap can invalidate the instrument response. Additional potential complications arise due to unknown permeability contrasts between the aquifer matrix and the material used to backfill around the probe.

Notes: In response to the detection of contaminants in several municipal water supply wells in a northern New Jersey community, the New Jersey Department of Environmental Protection (NJDEP) undertook a detailed assessment of the movement of volatile organics through the Brunswick fractured rock aquifer. Understanding the directional or anisotropic behavior of ground-water flow within the aquifer proved to be a crucial factor for identification of the sources of contamination. Since the ground-water flow occurs in a direction predominantly parallel to the strike of the aquifer, the resulting distribution of contaminants allowed the differentiation of two overlapping plumes, each over 4,000 feet in length and each emerging from discrete adjacent sources.The investigations and subsequent cleanup agreements between the NJDEP and the responsible parties allowed savings of several million dollars for the U.S. EPA's Super-fund Program which otherwise would have been used for cleanup of the site. The privately funded cleanup program includes treatment of the affected municipal wells and on-site remedial actions designed to fully restore the aquifer within 10 years.

Notes: Estimation of rates of contaminant movement at land treatment sites requires accurate measurements of water movement through the soil zone. A moisture balance method that employs the zero flux plane concept and several simplifying assumptions about saturated and unsaturated flow conditions gives reasonable estimates of evapotranspiration and percolation fluxes when applied to a land treatment site in central coastal California. The technique requires measurements of the saturated hydraulic conductivity of field soils as well as soil matric suction and moisture content at regular time intervals. Replicate monitoring clusters for matrix suction and moisture content are necessary in spatially variable soils but a detailed knowledge of the spatial variability of saturated hydraulic conductivity is not warranted.

Notes: Analytical and numerical modeling procedures based on the hydrodynamic dispersion were used to analyze the salt-water contamination problem in the Nakhon Luang aquifer underlying the City of Bangkok. A preliminary evaluation is performed for the approximate locations of the contaminating sources, and its rate and pattern of encroachment are predicted under different operating conditions in the future to assist in planning an efficient and economic monitoring network. The contaminating source is widespread and is located on the western side of the Chao Phraya River. With the present trend of pumping, the rate of encroachment is greatest from the northwest direction towards the main pumping center. The study indicates the advantage of performing one-dimensional model analysis prior to attempting two-dimensional regional analysis, particularly in cases where the initial chloride concentration distribution is unknown.