ALBERT

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 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: 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: Water well drillers gather information essential to recovery tests as part of normal procedure. Added effort could yield additional valuable information. More care in measurement of water levels both before and after a period of pumping can be used with ground-water formulae to determine approximate well efficiency.A relationship exists between the ability of an aquifer to perform (transmissibility) and the specific capacity of a well. By means of pumping tests, both transmissibility and specific capacity may be measured. The theoretical specific capacity can be obtained based on the measured transmissibility. Well efficiency may be estimated from a comparison between measured specific capacity and theoretical specific capacity.Tests of wells owned by the City of Houston, Texas, were selected for analysis. Test results were compared with curves showing theoretical relationships. From the comparison, wells in the Houston area are not completely developed. It may not be economical to develop a well to 100 percent efficiency, but theoretical relationships should be used in well development.

Notes: An induction-tuned device was designed and tested under a variety of well casing conditions. It can detect casing lengths to within 0.4 to 2.0 inches for casing ranging from 2 to 14 or more inches in diameter which are made of either magnetic or nonmagnetic metals. A casing separation as small as one inch is detectable for 12-inch diameter casing and a four inch or more separation is detectable for 4-inch I.D. casing. These values indicate the range in sensitivity expectable when determining casing separations.Dial readings in microamps are indicated as the ptobe is raised or lowered within a well bore. Readings vary depending whether the probe is centrally located or located to one side. The maximum and minimum dial reading is established for a given casing diameter at the start of a survey. A consistent change in dial reading from previous valves indicate a casing diameter change.The sensing element is a coil whose inductance is changed by varying its proximity to any metallic conductor. A coil and capacitor in parallel make a tuned circuit resonant at 3 K.C. The device includes a transistor in a phase shift oscillator, and a second transistor which acts as a current amplifier, a 0–100 μa d. c. meter driven through a bridge rectifier, capacitors, and other elements. Twelve to 14 volts at 4 to 6 milliamperes or less than 0.1 watt is sufficient to power the device.A maximum meter reading is obtained by adjusting an oscillator to the resonant frequency of the probe. Lowering the probe into a well casing detunes the probe, changing its impedance and the meter reading.All electrical elements are standard except the probe and all materials can be purchased for about $40.00 exclusive of the reel and cable assembly.

Notes: The electrical resistivity method has been a valuable tool used in the discovery of ground-water recharge facilities with percolation capacities in excess of 100,000 acrefeer per year. The procedures used in doing the field work and the methods of plotting the data are described using a typical area where studies were made. Correlations of soil types, recharge rates, and resistivity data for Santa Clara -County are included. Ground-water level data from observation wells are used to measure the regional and long-term effects of the ground-water recharge program.

Notes: Buried valleys are classified into two main types — those valleys completely buried by glacial drift, without present streams along their courses (Type I), and those partly buried or partly exhumed, usually with present streams along their courses (Type II). If a stream is flowing mainly in a Type II valley, the bottom of which is deeply buried by drift, local areas where the stream is cutting bedrock are postglacial channels of derangement. Postglacial channels of derangement, which often can be recognized on a topographic map, reveal that a buried valley (often Type I) exists nearby.

Notes: Ground water of acceptable quality is commonly interspersed with water of inferior quality. Water of inferior quality may be naturally occurring salty water commonly underlying fresh water, or it may be enclaves of contaminated water from wastes that lie in the fresh-water bodies. Disposal of wastes on and in the ground and pumping of water from wells cause a dispersion of contaminated water; migration of contaminated water toward wells may be spontaneously induced by the natural hydraulic gradient, or it may be induced artificially by the cone of depression about one or more wells. Economic methods of determining precisely the boundary zones between contaminated and uncontaminated water are not available. Much reliance is placed on monitoring wells.A prerequisite to monitoring is a synthetic hydrogeologic framework or model in which the behavior of the contaminated water is conceived. Such a conceptual model, using pertinent data that are available, helps to assess the need for monitoring and to guide a monitoring program for optimum results. Unplanned, indiscriminate monitoring of water from wells is expensive, inefficient, and fallible. The need for monitoring will increase in the future; yet, the proper objective is to improve the technology of determining the distribution of contaminated water so that monitoring can be minimized and conducted with optimum results.

Notes: Ground-water development frequently provides a means whereby tremendous new economic opportunities are opened up. If supplies are overdrawn (mined) the ensuing regional economy may be able to afford replacements from more costly sources. In the United States the Salt River Valley of Arizona and the valleys of California provide examples.Two cases are treated in this paper, Israel and West Pakistan. In Israel, besides furnishing more than half of the basic source of water supply, ground-water development provides opportunity for both quantity and quality management, which makes possible use of surface supplies and reclaimed sewage as firm rather than marginal sources. This development will permit the total water resource of this small country, where agricultural production ranks among the world's most efficient, to be utilized effectively down to almost the last drop by the mid 1970's. Israel must then look to desalted water from the sea for-further expansion of its over-all water supply.In West Pakistan a combination of level terrain and leaky canals since about 1890 led to threatened waterlogging and salinity of more than 25 million acres of irrigated land, even though supplies were less than half adequate for good productivity. By the 1950's low yields and increasing population threatened starvation. However, initiation of ground-water development, first by the government and later by private enterprise, has, since 1960, led to construction of 3,500 governmental tube wells of about 3 cfs capacity and 30,000 private tube wells of slightly less than 1 cfs capacity.Results have been dramatic. Agricultural production and use of fertilizer are rapidly increasing, and opening of well development to private enterprise is providing the irrigator with benefits of free competition for his water custom which he did not previously enjoy. Ultimately, besides providing full supplies for an estimated 26 to 30 million acres, drainage and salinity problems will be mitigated if about 50 million acre-feet are pumped each year from ground water including about 28 million acre-feet to be mined from a reserve of about 1,900 million acre-feet. With some difficult surface storage development due to terrain, mining may eventually be reduced. Though an eventual technological solution for the continuing overdraft is not now in sight, perhaps an economy may be built which can afford such a solution when the time comes.

Notes: The effects on flow of a nearby stream from pumping a well can be calculated readily using dimensionless curves and tables. Computations can be made of: (1) the rate of stream depletion at any time during the pumping period or after the cessation of pumping; (2) the volume induced from the stream during any time, both during pumping or after the cessation of pumping; and (3) the effects, both in rate and volume of stream depletion, of any selected pattern of intermittent pumping. Sample computations illustrate the use of the curves and tables. An example shows that intermittent pumping may have a pattern of stream depletion not greatly different from a pattern for steady pumping of an equal volume.The residual effects of pumping, that is, effects after cessation of pumping, on streamflow may easily be greater than the effects during the pumping period. Adequate advance planning that includes consideration of residual effects thus is essential to effective administration of a stream-aquifer system.

Notes: The Piedmont is underlain by igneous and metamorphic rocks, from which it is difficult to locate quantities of ground water adequate for municipal and industrial purposes. Ground-water occurrence and movement in the Piedmont is controlled by topography, recharge and discharge, rock type, fracture systems, and type and thickness of saprolite.Approximately 12 square miles in the Heflin area, Cleburne County, Alabama, were included in this study. Fractures within bedrock are the most effective avenues for ground-water movement in this area, but domestic supplies can be produced from saprolite and alluvium overlying bedrock. Thick saprolite contributes to bedrock-fracture production by absorbing water from streams and rainfall and releasing it slowly to underlying fractures.Seismic methods were used with geologic, hydrologie and topographic data to locate and define favorable areas for drilling. As shown on the seismic sections, faults or fracture systems appear to correlate with depressions on bedrock surfaces associated with thick saprolite zones. Seismic data indicate twenty-five prospective areas for test drilling.Resistivity data were used to confirm seismic depth to bedrock, and to locate gravelly zones in buried stream channels. Some of the buried alluvium is thick enough to be considered a potential aquifer.Twenty-five prospective areas are indicated by geophysical work in the Heflin area. A proposal to drill 10 wells to evaluate the most promising of these areas is presently being considered.

Notes: The Floridan aquifer in northeast Florida is comprised of limestone and dolomite beds of Tertiary age. These formations in ascending order are: the Cedar Keys Formation of Paleocene age; the Oldsmar Limestone, Lake City Limestone, Avon Park Limestone, and the Ocala Group, all of Eocene age; locally the Suwannee Limestone of Oligocene age; and limestone and sand beds at the base of the Hawthorn Formation of Miocene age. The top of the Ocala Group ranges in elevation from 100 feet above sea level to 550 feet below sea level throughout the area.Except in the western part of the area where the Ocala Group is at the surface, impermeable beds in the Miocene to Recent deposits overlie the aquifer and confine the water under artesian pressure. Hard, impermeable beds within the aquifer separate the water-bearing zones. The coefficient of transmissibility ranges from about 50,000 gpd/ft (gallons per day /foot) to more than 1,000,000 gpd/ft and the coefficient of storage ranges from 1.5 × 10−4 to 1.7 × 10−2 in areas where the water in the aquifer is under artesian conditions.The estimated annual recharge averages one-half mgd (million gallons per day) in the western part of northeast Florida and 45 mgd in the south central part. Limited recharge also occurs throughout the central and eastern part of northeast Florida by downward leakage of water through the overlying confining beds. The coefficient of leakance of these confining beds ranges from about 1.7 × l0−2 to 1 ×10−3 gpd/ft3.Natural discharge occurs by perennial and intermittent springs and upward leakage through the confining beds in the areas of artesian flow. Artificial discharge by wells occurs principally in the farming, urban, and industrial areas in the eastern part of northeast Florida.Between 1940 and 1962 artesian pressures declined from 5 to 25 feet throughout the eastern part of northeast Florida.Seasonal declines of artesian pressure of 5 to 10 feet in the farming areas resulted in temporary increases of chloride content of water of 200 to 500 ppm (parts per million). The chloride content of water in the aquifer in the vicinity of Jacksonville and Fernandina has increased from 22 to 1400 ppm in wells more than 1,400 feet deep. Thus far, impermeable zones below the fresh water have prevented serious salt-water contamination in shallower wells at Jacksonville and Fernandiua.

Notes: The significance of the work associated with the protection of aquifers against salt-water encroachment, primarily in the area of Southern California goes far beyond the solution of this local problem. Engineers and planners are now able to turn to the record of extensive practice in the field of artificial ground-water recharge to modify the concepts based on theoretical studies. Thus depleted aquifers, anywhere, can be evaluated as potential reservoirs for the storage of ground water – evaluated as to cost, legal complications, and administrative design in the same way, and on the same basis, that surface-water impoundments are evaluated.The work done on the West Coast in artificial recharge increases the number of alternates that are available to the water planner and, in the long run, this may be the most significant output of the engineering, construction, and operation of the barrier projects.

Notes: Electrical earth resistivity and soil temperature surveys have been conducted in the vicinity of four sanitary landfills in northeastern Illinois to test the possibility of detecting and tracing any chemical or temperature alteration of ground water by leachates from buried refuse. Reference data on water quality, levels, and movement were provided by a system of monitor wells drilled for a hydrogeologic study of the landfills.The resistivity survey, which was in homogeneous silty sand outwash, traced mineralized water from the landfill for a distance of more than 1000 feet. Apparent resistivity values were one fourth those obtained from unaffected areas. Interpretations of direction of ground-water flow and location of discharge boundaries from the geophysical data agree vith interpretations based on the monitor well data.The soil temperature survey indicated the presence of a halo of higher temperatures around the landfill and indicated areas of surface recharge.The geophysical surveys show, in general, that chemically altered water is traceable in uniform earth materials where the depth of the water table is constant.

Notes: The U. S. Geological Survey, on behalf of the U. S. Atomic Energy Commission, performs a broad range of geologic and hydrologic studies related to underground nuclear explosions at the Nevada Test Site. One phase of the studies involved extensive geophysical logging and hydraulic testing in deep exploratory holes at Pahute Mesa, Nevada Test Site. Various geophysical logs and hydraulic testing techniques used in the study are described in this paper.Interpretations of logs and logging techniques depend on factors such as rock characteristics in a particular area, drilling methods, and the objectives of the hydrologic investigations. From experience gained at Pahute Mesa, some qualitative data on rock lithologies and hydraulic conditions in the borehole may be determined by electric, caliper, temperature, and fluid resistivity logs. Quantitative data on the major water-yielding intervals in the borehole are obtained from radioactive tracer or spinner surveys. Interpretations of the geophysical logs have been verified by isolating specific zones in the drill holes with inflatable packers and spacers. These intervals were tested by injection or swabbing of fluid and measuring the resultant change in water level caused by fluid outflow from or inflow to the interval of rock isolated by the packers.

Notes: Portable pumping equipment for sampling of wells, discribed by written text, photographs, and a detailed drawing, has been constructed by the Robert S. Kerr Water Research Center.The equipment can sample to depths of 300 feet at pumping rates ranging between 7 and 14 gallons per minute, with rate variation dependent upon sampling depth.The unit is convenient in size and easy to operate because only one line has to be handled during its operation. This is a wire-reinforced rubber hose that supports the submersible pump, contains the electrical cable, and conveys water.

Notes: The landlocked Republic or Upper Voira lies in the heart of West Africa and comprises a wide lareritic plateau at the south edge of the Sahara Desert. From south to north, the rainfall decreases from about 1.200 mm. to less than 500 mm.; the evaporation increases from a low of 1,945 mm. to 3,385 mm.; and temperatures from 30° C to 34° C.Latentic rocks occur as surficial deposits over much of the reconnaissance area, and generally are ferruginous, hard, and cemented. The underlying bedrock consists primarily of granite and granodiorite with lesser amounts of metamorphics.The so-called “under latérite” materials, consisting of the weathering products of the igneous and metamorphic rocks, constitute the principal aquifers in the investigated areas. These clays and sands generally can be counted upon to yield small supplies of water, adequate for at least domestic and stock use. Large-diameter dug wells are used exclusively to tap the thin water-bearing zones. Where 15 meters or more of weathered material occur above fresh bedrock, water can be found and exploited. A “good” well is one which produces 2,000 litersb per hour.The chief importance of the bedrock as a source of water is that it may yield at least a small quantity of water from fractures at most localities where ir is below the water table.Water in sufficient quantity and adequate quality is not now available to raise the standards of living in the 631 villages in the areas visited. Most of the immediate need can be met by developing ground water from the weathered material through large-diameter dug wells.