ALBERT

Notes: Tracers are used widely to determine the direction and velocity of ground-water movement. Failures of tracer tests are most commonly a result of incorrect choice of tracers, insufficient concentrations of tracers, and a lack of an understanding of the hydrogeologic system being tested. Some of the most useful general tracers are bromide chloride, rhodamine WT, and various fluorocarbons. For certain purposes, dyed clubmoss and baker's yeast have proved valuable. Many radionuclides including 3H, 82Br, and 198Au are almost ideal for numerous purposes, but radiation hazards associated with their use together with local, State, and Federal regulations have discouraged widespread field applications in recent years within the United States.

Notes: The Tucson, Arizona, metropolitan area has 450,000 inhabitants and is expected to have nearly 800,000 inhabitants by the year 2000. Tucson is totally dependent on ground water drawn from two basin aquifer systems for its water supplies, as are agricultural, mineral and industrial operations in the area.Municipal, agricultural, mineral and industrial ground-water withdrawals in the two basins amount to some 376,000 acre-feet per year (AFY). Dependable ground-water supplies in the two basins amounts to about 80,000 AFY. Thus, the two aquifer systems are overdrafted by approximately 296,000 AFY, 80 percent of which is by irrigation agriculture.In Arizona, ground water belongs to the owner of the land overlying the aquifer. To ensure adequate ground-water supplies, the City of Tucson has been purchasing and retiring farmlands in one of the basins. However, litigation that reached the Arizona Supreme Court led the Court to rule that the City could pump only 2.4 AFY per acre of farmland retired. The City has retired about 12,000 acres in the basin and in 1978 withdrew some 20,000 AFY of ground water for municipal use.Retiring these farmlands to secure water rights impacts on area economy and creates weed problems for farmers who own land near the retired lands. The City of Tucson budgets about $50,000 annually for weed control.A possible alternative to retiring farmlands and to cultivating crops that require heavy irrigation is cultivating arid-adapted vegetation that has economic potential. Jojoba (Simmondsia chinensis) is a shrub native to the Sonoran Desert that appears to be an economically viable arid-land crop. It needs about 1.5 AFY per acre compared with traditional crops grown in the Southwest that have average needs of 4 AFY or more.The economic value of jojoba is based on the oil extracted from its seeds. It is a unique, unsaturated oil composed of nonglyceride esters consisting almost entirely of straight-chain acids and alcohols. Such oils are difficult to synthesize in commercial quantities, and the only known natural source is the sperm whale, an endangered species.If farmers in the basin cultivated jojoba, water use could be reduced by about 2.5 AFY per acre, from 4 AFY per acre for traditional crops to 1.5 AFY for jojoba. Even if the City of Tucson had to subsidize farmers at a rate of $40 per acre for the 10 years it takes jojoba to produce economically feasible yields, the City would save more than 50 percent of the cost to purchase and retire farmlands and still be able to draw water from the basin for municipal uses.This dual use of water in the basin would permit agriculture to continue its contribution to area economy while the City could continue meeting its water needs by piping water out of the basin into the metropolitan area. However, implementing this plan would require changing Arizona ground-water laws.

Notes: Median nitrogen concentrations of ground water and water from streams in Nassau County were statistically analyzed on an areal and temporal basis and by individual well to compare concentrations of nitrogen in ground water beneath sewered and unsewered areas. The comparison is discussed in terms of hydrogeologic conditions and major point and nonpoint sources of nitrogen.Although no significant differences in median nitrate concentrations during the 25-year period of record were observed between the sewered and unsewered areas, recent (1972–76) ammonium and nitrate data suggest a relative improvement in water quality in the sewered area. This finding is based on (1) significantly lower ammonium and nitrate concentrations in stream water of the sewered area during base flow, (2) significantly lower median ammonium concentrations in ground water in the sewered area, (3) significant decreasing long-term nitrate trends in water from 8 of 13 wells in the sewered area where records were sufficient for analysis, and (4) significantly lower median nitrate concentrations near the water table beneath the sewered area.The lack of significant difference between median nitrate concentrations in the sewered and unsewered areas may be in part due to sampling bias and to the considerable length of time necessary for ground water in the sewered area, which was contaminated by cesspool and septic-tank effluent before sewering, to reach a point of discharge in a stream or bay.In addition, ammonium leached from landfills and nitrate originating from nonpoint sources such as fertilizers and animal wastes, cannot be removed by sewers and may be obscuring water-quality improvements brought about by sewering.

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

Notes: At a flyash landfill in southeastern Wisconsin, dry ash has been placed directly in contact with a shallow sand and gravel aquifer. Substantial modification of ground-water quality has occurred primarily by sulfates, calcium and magnesium. However, after eight years, the contamination has spread less than 200 meters from the site in a permeable aquifer. In addition, toxic metals contained in the ash have proven quite immobile in the ground water. Fortuitous location of the disposal site in alkaline sediment upflow from ground-water discharge in a marsh appears to have limited the extent of contamination.

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

Notes: It was proposed that the horizontal extent of the ground-water mound is limited for finite times of recharge from strip basins even in infinite aquifers. A method of identifying the extent of the ground-water mound using solutions of the equation of flow for finite aquifers was suggested. These solutions were obtained using two different procedures of linearization, those of Baumann and Hantush, and Laplace transforms. The resulting expressions were of a general nature and the equations of Hantush for infinite aquifers were shown to follow as a special case. The range of validity of the two procedures of linearization was tested using experimental results from sand tank models of finite aquifers, available in literature. The Baumann linearization was valid (correct to within ±5 percent of experimental values) up to a water table rise less than 0.4 times the initial height of the water table. The Hantush linearization was valid (correct to within ±2 percent of experimental values) for the entire range of water table rise studied, i.e. up to three times the initial height of the water table. The Hantush procedure was thus shown to have wider applicability. However, both procedures were found to yield results which have satisfactory agreement with experimental results over larger ranges than earlier reported for infinite aquifers.The effect of variation of the horizontal extent of the recharge mound on the water table profile was studied by treating the limit of the horizontal mound itself as a parameter. The water table rise was computed using the Hantush linearization procedure for different values of the ratio B/L (B/L = 15, 20, 25, 30, 35, 40 and ∞) where 2B is the horizontal extent of the mound and 2L the width of the recharge strip. The finite extent of the ground-water mound in an infinite aquifer was given by that value of B/L for which the predicted profile was identical to that produced when B/L =∞.

Notes: As the volume of hydrogeologic literature increases, researchers are finding it more difficult to identify and locate information. The National Water Well Association's Library/Information Center is a central source of ground-water information. In addition to collecting books, journals, and reports relevant to ground-water research, the Library/ Information Center conducts both manual and computer literature searches. A bibliographic data base of hydro-geologic references is in development.

Notes: The time-consuming curve construction and, in some cases, curve matching, and the gross approximations of aquifer geohydrologic properties, can be supplanted by a simple, speedy, accurate, and inexpensive analysis of pumping test data by a handheld programmable calculator.With such calculators—in actuality, minicomputers-pumping test data can be analyzed within seconds, while the test is ongoing, and pumping test time and expense can be reduced, while still securing representative values for transmissivity and storage coefficients.

Notes: Ground-water modeling is an area of current research. As such, new techniques and applications continually evolve. In addition to being influenced by the necessity to solve certain problems, recent developments in modeling are influenced by the state of model evolution and computer capabilities.

Notes: An evaluation of sources of nitrogen in an urban area indicates that it may be difficult to distinguish effects on the quality of underlying ground water. In Nassau County two principal sources of nitrogen are human waste water and fertilized turf. The effects of these sources, combined with other sources such as domestic animals and precipitation, are such that management of one source, i.e. the removal of waste water via sewers, may be less effective than expected.

Notes: A numerical model is presented that solves the partial differential equations describing the motion of salt water and fresh water separated by a sharp interface. The areal equations are based on the Dupuit approximation and are obtained from partial integration over the vertical dimension. Finite-difference techniques are applied and the utility of several solution schemes is tested. The most efficient and accurate solution scheme uses block line-successive over-relaxation. Examples are given to: (1) test the model, (2) evaluate the Dupuit approximation, and (3) demonstrate the application to a field situation. The results show that the model is in good agreement with an analytical solution, but under severe conditions the Dupuit approximation may be inappropriate. The model is applied to a field area near Kahului, Maui, Hawaii and results extend the analysis of the problem beyond previous efforts.

Notes: Ground-water discharge was found to be the primary cause of flood peaks generated at two small wetland controlled basins in eastern Massachusetts. Within the wetlands, ground water rose rapidly following precipitation and in near synchronization with stream levels indicating a close coupling between ground water and the stream. Stream hydrographs were separated into baseflow and surface runoff by a dynamic technique which matches the hydrograph of an index well with the stream hydrograph to determine the moment of maximum ground-water discharge. Hydrograph analysis showed that for both wetlands ground water was the major component of all flood peaks and accounted for approximately 93% of the total annual discharge.

Notes: Ground-water quality has been monitored at a fly ash disposal site. The monitoring technique consists of electrical resistivity soundings, and profiles in conjunction with analysis of water samples from 33 wells on the site. In addition laboratory measurements were made on samples from the well borings to determine the changes in resistivity of each lithology as a function of water saturation, and the temperature and conductivity of the pore fluid.For a line approximately perpendicular to the ground-water flow, we were able to detail the subsurface lithology using electrical sounding, and in conjunction with the laboratory studies, it was possible to determine the vertical and horizontal extent of the contamination for that cross section.Electrical profiles, which were taken on a monthly basis, were able to monitor the changing concentration of leachate after the profiles were corrected to a common ground-water temperature.

Notes: Step-testing of wells penetrating a jointed, fractured, sometimes cavernous limestone-dolomite artesian aquifer showed characteristic patterns of extreme variation in specific capacity at different discharge rates. The application of principles developed by Jacob for well-loss determinations, and subsequent modifications by others, did not yield meaningful results. It was found that a log-log relationship between discharge and drawdown, through a large number of steps, could be used to evaluate the degree of nonlinear head losses in and near the well bore and make possible the extrapolation of drawdowns at higher discharge rates. This technique also has been used to estimate transmissivity which, in at least one instance, was confirmed by the subsequent evaluation of observation-well data by both straight-line and type-curve methods. The easy use and rapid initial evaluation of test data afforded by this method gave rise to the name “Cheat Sheet.”

Notes: An investigation of waste-migration patterns from a septic system indicates that complex patterns result from minor variations in regolith adsorptive capacity and texture, local hydrology, and possibly soil microbiology. The existence of multichemical, bifurcating plumes suggest that monitor wells arranged up and downgradient and capable of multilevel sampling are essential to adequately delineate contaminant migration in ground water. The data also indicate that sampling for a single constituent could yield misleading information about the nature and distribution of other ground-water contaminants. The ability for chemical removal by the regolith is in direct response to minor variations in silt- and clay-sized particle content and corresponds to Langmuir adsorption isotherms. Silt- and clay-sized particles are dominantly organic in origin. Minor iron and aluminum hydroxyoxides and clays are present.Substrate samples, when collected at regular intervals and analyzed for adsorbed constituents and textural variability, provide an integrated picture of the distribution of waste chemicals through time. Such samples also provide insight into the mechanics of plume configuration and flow characteristics within the regolith. The study shows that regolith adsorption data are essential to the determination of life expectancy of the regolith as a contaminant treatment system.

Notes: The Orange County Water District in Southern California imports approximately 75 percent of its supply from aqueducts drawing waters from the Colorado River and Northern California. Twenty-five percent comes from natural flow in the Santa Ana River and local precipitation. Only about one-half of the aqueduct water is treated and distributed in pipelines. The other one-half is applied to infiltration basins and ponds for ground-water recharge. This allows communities within the District to draw ground water as their major supply, which is supplemented by aqueduct water purchased after treatment by the Metropolitan Water District of Southern California. The economic advantages of ground-water recharge, as opposed to direct use of surface supplies, include eliminating water treatment, minimizing the size of pipe networks to distribute potable supplies, and reducing the requirement for storage reservoirs. However, using the basin aquifers as a reservoir to balance cyclic supply and demand creates two possible problems: excessive pumping lowers the fresh-water table below sea level, and infiltration can result in a gradual increase in the level of dissolved salts in the ground water. Sea-water intrusion has been greatly reduced by injection wells that provide a hydraulic barrier between the salt water and fresh inland water. Salt accumulation in the basin is a more serious long-term problem since the salinity in the Colorado River water is increasing. Greater use of less salty Northern California water and reducing unwanted seepage of waste waters containing high dissolved solids are two of the remedial measures being implemented at present.

Notes: A serious type of clogging occurs in wells which abstract anaerobic water from the shallow aquifer in the river region in The Netherlands. These clogged wells can easily be regenerated by means of sodium hypochlorite (15%). The figure for the specific yield after regeneration approximates to the figure on commissioning.During the pumping to waste to clear the well after regeneration, the types of reaction products present in the spent chlorine solution were investigated. From this it can be deduced that the chlorine solution added was utilised mostly for the oxidation of iron sulphides. The remainder was used mainly for the oxidation of organic material. At the same time, calcium carbonate went into solution and iron carbonate was formed. During the regeneration of a number of wells, some silt was also removed.Although information can be obtained in this way about the composition of the materials removed, it is impossible to form any concept of the nature in which these substances are present around the clogged wells.

Notes: Four case histories illustrate the various roles that digital computer simulation models can play in ground-water exploration. The case histories describe their use in evaluating aquifer parameters and characteristics, in estimating ground-water recharge, in resolving data inconsistencies, and in determining the optimal allocation of exploration funds. The models are especially useful in identifying data deficiencies and inconsistencies.

Notes: A nitrogen powered, all-glass-Teflon, continuous delivery, noncontaminating pump system is described. Continuous flow rates up to 45 gal-hr-1 (2.84 1-sec-1) are obtainable. The system was developed and field tested to sample water wells with static heads greater than 32 ft (10 m) for measurements of trace level organics. The system is equally applicable to environments such as marine, lake, and other unconfined water or fluid systems. Also, the analysis can be extended to inorganic and microbial assays in that the sample obtained is unaltered with respect to chemical, physical, and biological properties.

Notes: .A test-injection well was drilled to a depth of 3,200 feet (976 m) to determine the feasibility of deep underground injection of 50 mgd (190,000 m 3/day) ADF of secondary treated waste water in south Dade County, Florida. Geological formation samples and water samples were collected and analyzed during the drilling of the well and geophysical logging was performed in the well at several stages. At this site, the Floridan aquifer extends from a depth of 920 feet (281 m) to 1,680 feet (512 m) and generally consists of limestone which is fossiliferous in part. Water from this aquifer is brackish, with chlorides ranging from 700 mg/l at the top to 15,000 mg/l at the bottom. The strata from 1,680 feet (512 m) to 2,790 feet (851 m) are essentially nonwater-producing and act as a confining bed between the Floridan aquifer and the Boulder Zone.The Boulder Zone begins at 2,790 feet (851 m) in depth and consists of a very hard, fractured, cavernous, dark dolomite. The water from this aquifer is very similar to sea water. The subsurface temperature gradient at this site is reversed from the normal gradient, cooling with depth at an average rate of approximately 0.4° F (0.22°C) per 100 feet (30 m). The injection zone extends from approximately 2,830 feet (863 m) to 2,920 feet (891 m) in depth. Results of pumping tests indicate that the Boulder Zone is very transmissive and has a good confining bed above it.

Notes: A major potential failure mode of thermoplastic well casing is collapse. The casing may be subjected to a collapsing pressure during grouting operations, backfilling, well development or simply from lateral soil pressure. Since the strength of thermoplastic materials significantly decreases at elevated temperatures, it is important to know how casing collapse resistance varies with temperature.A series of experiments have been performed to determine the collapse resistance of poly (vinyl chloride) (PVC) and acrilonitrile-butadiene-styrene (ABS) well casing over a wide range of temperature. Results indicate that collapse resistance is inversely proportional to a function of the outside diameter-to-wall thickness ratio as indicated in the ASTM F480 standard and that collapse resistance decreases by approximately ½ psi per degree Fahrenheit increase in temperature above room temperature.

Notes: Due to chemical reactions between steel casing and stored water in capped artesian wells, the pH, Eh, TDS, major and trace ion concentrations and saturation indices can be significantly, but relatedly altered from their aquifer values. To obtain true aquifer water samples, either all the stored water must be flushed from the well or a sampling tube must be used to ensure that the water is taken from within the aquifer. Flushing time can be calculated from well dimensions and best be monitored in the field by measuring temperature and electrical conductivity.This study has been made of confined wells in a fissured limestone, but the reactions which occur are likely to be common to aquifers of different hydrogeology.

Notes: Field investigations in Paradise Valley, Arizona, conducted during 1974 and 1977, delineated areas of ground water with up to 132 mg/1 nitrate. Two alternative interpretations are developed as to possible sources of the excess nitrate. The first is a conventional interpretation identifying the use of nitrogenous fertilizers as the primary source and disposal of treated waste-water effluent as a secondary source. An alternative interpretation identifies the source as a sand and gravel unit that is interpreted as a braided-stream deposit, located about 152 m (500 ft) below the land surface. The source of the nitrate may have been NH4Cl leached from tuffs in the adjacent Superstition Mountains, subsequently oxidized to nitrate and deposited in abandoned channels of the braided-stream complex. At present, it is not possible to make a definitive choice among the possible nitrate sources.

Notes: Monitoring the chemistry of ground water near in-situ uranium leach mines is complicated by chemical variations unrelated to the mining operation that result from (1) spatial differences in the aquifer environment, and hence, in the water chemistry, (2) inconsistent or inadequate sampling procedures, and (3) errors in chemical analyses. Differences in the chemistry of water from place to place in the aquifer should be identified in pre-mining baseline studies and must be taken into account during monitoring of the leaching operation, because natural waters of chemistry different from that established at a particular well during the baseline sampling period may be drawn into the monitoring well by pumping. The most important factor in developing proper sampling techniques is the configuration of the well and pumping equipment; if the pump intake is set near the point where water enters the well, and if the pumping rate is kept low to reduce turbulent mixing of waters in the well, it is not necessary to pump a full well-bore volume before collecting a sample. Errors in chemical data can be eliminated by proper storage and handling of the samples and by careful checking of the analyses for chemical balance and eliminating the analyses that do not balance properly. Interpretation of the chemical data should be made only after assuring that these monitoring problems have been taken into account.

Notes: Abstract. Microcomputers can be a major tool for the hydrologist. Small and portable, microcomputers can be useful for the acquisition and modeling of an aquifer while on site. This would result in very low cost for computer usage and fast processing time. Their low cost makes the availability almost universal. Tests were run on the TRS-80 system using the Prickett finite difference model and the Theis equation. The results indicate that with the exception of memory storage no problems should arise. With newer generations of microcomputers core memory storage will no longer be a problem.

Notes: Polynomial approximations have been developed for the infinite series embodied in the Theis equation. These have the following advantages when programmed for use on computers or hand calculators: (1) they are easy to program; (2) they are computationally efficient; and (3) they eliminate round-off errors.

Notes: The Fort Payne Formation of Early Mississippian (Osagean) age crops out over extensive areas of central Tennessee, south-central Kentucky, and northern Alabama. Specific formation lithologies are known to have been modified locally through weathering into an artesian aquifer along the Eastern Highland Rim of central Tennessee. The shallow aquifer can be divided into two parts; uppermost is a highly permeable chert gravel zone that is in hydraulic communication with a lower zone of interconnected solution cavities within bedrock. The gravel, at depths as great as 24.4 m (80 ft), fines upward into the clay-sized chert of the upper confining bed. The lower confining bed is the Chattanooga Shale of Late Devonian to Early Mississippian age.Field and petrographic studies of the Fort Payne Formation indicate that the aquifer has developed near the base of the unit. The chert gravel portion of the aquifer has developed from silicified dolowackestones of the Beaver Creek Limestone Member and from interbedded Fort Payne dolostones. The lower portion of the aquifer occurs within preferentially weathered, silicified and non-silicified dolosiltstone.

Notes: A survey of the requirements of State regulatory agencies responsible for monitoring ground-water quality at waste disposal sites was conducted in order to gain a concise profile of monitoring practices across the country, and also to provide the basis for a monitoring manual to serve as technical background and guidance for the citizens of Minnesota. The survey considered a variety of topics including the regulatory framework for requiring monitoring, chemical parameters analyzed, recommended methods of monitoring well construction and sample collection, laboratory quality control, data interpretation, and post-operational monitoring requirements.The survey showed that most State monitoring programs are in their infancy. Many States, however, are beginning to devote serious effort and manpower commitments to the development of monitoring programs, although there is considerable divergence of opinion regarding how these programs should be conducted. Federal legislation establishing minimum performance criteria instead of detailed operating requirements for waste disposal sites will increase the need for sound water monitoring programs at these sites in the future.

Notes: The ground-water system in many of the irrigated areas of the Colorado River Basin is derived almost entirely from deep percolation of irrigation water and seepage from irrigation conveyance and tail-water collection systems. Salt pickup rates from irrigated soils in the basin vary in the different areas. Among the high salt pickup areas is the Grand Valley in western Colorado, estimated at 8 tons/acre/year. Water entering the ground-water supply from irrigation practices in the valley amounts to about 145,000 acre-feet/year and contributes about 690,000 tons/year to the salt load of the Colorado River. Samples of base-flow water from the weathered Mancos Shale aquifer in the valley vary in salinity from about 1,500 to about 9,000 mg/l with a mean of 4,100 mg/l; while water samples from alluvial aquifers range from 305 to 124,000 mg/l with a mean of about 11,500 mg/l. Base-flow returning to the river in the drains and washes has concentrations that average about 4,200 mg/l.Water losses and quantities of irrigation return flows can be reduced by improving farm irrigation efficiencies and by partial or complete lining of canals, laterals, and ditches. Increasing on-farm irrigation efficiency through system improvements and irrigation scheduling is the most cost-effective measure. However, achievement of higher efficiencies will require changes in water laws to encourage conservation and revised water pricing policies that discourage waste.

Notes: .Calcium hydroxide ground-water seepage, highly mineralized, with a pH measured as high as 12.7 has been discovered in the Yarmouk Valley of Jordan. The origin of the seepage is rainfall recharge through over 100 meters of portlandite-rich rock. The portlandite [Ca(OH)2] was formed by thermal metamorphism of calcite due to (spontaneous) combustion of organic-rich marl and limestone. The pH is believed to be the highest ever reported for natural ground water.

Notes: Due to the growing demand for bottled mineral waters, a study was undertaken to determine the quality of fourteen different brands of still and sparkling bottled waters. Objective testing showed a wide variance in taste as waters have different tastes and individual preferences are the rule. By analytical means, the mineral content of most of the tested waters met U.S.E.P.A. standards; however, some samples had unacceptable levels of sulfate, hardness, and other constituents. Cost comparisons show a wide variation in price, with all the tested waters many times more than normally available tap waters.

Notes: Partial differential equations may be used to describe a large number of problems in ground-water hydrology. Without a solution, however, these equations are of little value. Only a simplified subset of the general equations can be solved by analytical means, and these often describe idealized situations that are limited in application. Numerical solution of these equations using high speed digital computers offers a logical alternative.

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

Notes: The expression 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT137:GWAT_137_mu1"/〉 is a handy tool for predicting aquifer parameters using all the drawdown and recovery data obtained during step-drawdown tests or periods of cyclic or intermittent pumping.For inefficient wells the expression 〈displayedItem type="mathematics" xml:id="mu2" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT137:GWAT_137_mu2"/〉 fits pumping wells better. The data from conventional step-drawdown tests of pumping wells can be used to obtain T, C, and y. If the data fail to fit the ideal, they may be used to interpret local hydrologic conditions.

Notes: Grouting of water wells is commonly done to increase the well life and to protect the water supply. When Portland cement-based grouts cure, a by-product of the process is heat of hydration which causes increased temperatures in the vicinity of the well casing. Since thermoplastic casing materials lose significant strength at elevated temperatures, it is important to know what range of temperature increases might be associated with the grouting operation.A series of experiments has been performed to determine these temperature increases. Wells were simulated in the laboratory and temperatures monitored throughout the casing-grout-soil system. Results indicate that under certain circumstances the casing temperature could increase by as much as 180° F; however, for nominal 1 1/2-inch grout thicknesses, casing temperature increases between 17° F and 26° F were measured.

Notes: Through the years the Theis equation has played an important role in ground-water hydrology. Comparison of experimental pumping-test data with this theoretical curve by graphic means has been a standard method of determining aquifer transmissivity and storage. The purpose of this paper is to present a technique and an algorithm to automatically fit experimental pumping-test data to the Theis equation by obtaining the “best” transmissivity and storage in the least squares sense through the use of sensitivity analysis. The automated fit for pumping-test data developed in this work should be a useful tool for the ground-water hydrologist. Use of the technique is simple, quick, and inexpensive, and has the advantage of always being objective. As a measure of the error in fitting, the rms deviation in drawdown is calculated for the “best” transmissivity and storage.

Notes: The assumptions inherent in the theoretical analysis of constant drawdown overflow tests are difficult to achieve in practice. This paper shows that, even if there is a restriction in the flow which causes some delay in the achievement of the constant drawdown condition, the theoretical discharge curve is followed once the constant drawdown condition is reached. Recovery tests following overflow are also examined and it is shown that the discharge used in the calculation should be the discharge at the instant that the test is stopped. Further, it is demonstrated that if well and formation losses occur, the aquifer response is distinctly different from that of the theoretical analysis.A brief description is given of an alternative method of analysis using a numerical model. A preliminary study of a field test yields promising results.

Notes: A comparison of the concentrations of nitrate in three public supply borehole sources which abstract water from the Chalk in a relatively local area, led to a more detailed study of the possible causes of high nitrate values at one of the sources and the geological and recharge characteristics of all three.The local catchment area of the high nitrate source is actively fertilized, both by sludge spreading and the application of artificial fertilizers. The catchment areas of the other two ground-water sources are not subject to the same intensive agricultural activity. It is suggested the differences in water quality between the three supplies are related to the variations in land use and the local hydrogeology.The study makes it clear that due to local influences each source may have a unique hydrogeochemical character irrespective of being located in the same regional geological catchment area.More detailed investigations on the origins of the nitrate in the abstracted ground waters are planned as a follow-up to this initial study.

Notes: A common problem with a downhole water sampler consisting of a reservoir for fluids and a remote controlled motor-operated piston valve assembly has been sample contamination due to damage or destruction of the O-ring seal on the piston of the sampler. O-ring damage results from shaving by sharp edges in the entry-ports area or from erosion by high fluid velocities through the entry ports when sampling at depths below water level greater than 2,500 feet (762 meters). Beveling of sharp edges in the entry ports and modification of the piston by installation of a needle valve and seat solved the problem of O-ring damage and resultant loss of sample integrity. Other modifications include a high pressure needle valve in the removable reservoir chamber bottom that allows the reservoir to be drained while pressurized, and an O-ring piston in the reservoir chamber that permits collection of water samples that are essentially free from contamination by surface air. With the latter modifications, the sampler can also be used for injecting brine or other tracers in quantities as large as 34 fluid ounces (1 liter).

Notes: The precipitation of humates at the interface between a humic acid solution and an aluminum potassium sulfate solution was studied in porous media models to gain some insight into the deposition of Colorado Plateau type uranium deposits. The effects of variable flow rates, porous-media layering, mudstone lenses, fluid density differences, and geochemical reactions on the flow phenomenon and the resulting precipitate were evaluated. A numerical model was developed to predict the shape and location of the interface where precipitation occurs. The numerical model was verified by comparing its predictions with the results obtained from the porous media model. The association of precipitate bands with modeled sedimentary features and the similarities between these precipitate bands and actual deposits in the Colorado Plateau suggest that these model studies provide data useful both in understanding and predicting the relations between tabular ore deposits and ground-water flow patterns.

Notes: Programmable calculator programs have been given previously for the calculation of head or pressure change resulting from the pumping from or injection into wells completely penetrating fully confined or semiconfined aquifers. Programs are documented here for wells partially penetrating a fully confined aquifer. The programs are for the TI 59 card programmable calculator.

Notes: In steam-electric power plants, large volumes of surface waters are used for cooling the plant's condensers. There, approximately two-thirds of the energy produced by the fuel is removed as waste heat. This heat is carried away by the cooling waters, is dispersed into the atmosphere or surface-water bodies, and is lost for other potential uses. When condenser cooling systems such as towers or ponds are used, there is also a considerable net loss of water through evaporation.Injection and storage of spent cooling waters underground would reduce the evaporative (consumptive) losses to the atmosphere. Later, these waters could be recovered for use in heating and in industrial or agricultural applications. The resulting conservation of energy and water may make such a project economically feasible in the near future as the costs of water and fuel increase.In this paper, we review the use of ground water from a confined aquifer for this application and analyze a simple configuration of one withdrawal and one injection well to determine: (1) the areal extent of temperature changes caused by reinjection of spent cooling waters into the aquifer from which they originated; and (2) how long it would take for the water to become too hot to use for cooling.

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

Notes: Three key hydrogeochemical environments based on the oxidation-reduction state of ground water are defined by the presence or absence of dissolved oxygen and hydrogen sulfide. The mobility of arsenic is greatly influenced by these dissolved gases and the behavior of iron in these same environments.The main forms of arsenic in aqueous environments are arsenate and arsenite. Arsenate occurs in oxygenated waters but if colloidal ferric hydroxide is also present, the arsenate may be adsorbed and removed from solution. In strongly reducing waters containing hydrogen sulfide arsenic is removed from solution and precipitated either as arsenic sulfide, heavy-metal sulfarsenite compounds, or coprecipitated with iron sulfides. In mildly reducing waters lacking both dissolved oxygen and hydrogen sulfide arsenic occurs as the arsenite ion. In waters of this type the mobility of both arsenic (as arsenite) and iron (as ferrous iron) are at a maximum. It must also be stressed that arsenite is 60 times more toxic to humans than arsenate.

Notes: Comprehensive, steady-state investigations were carried out on plots adjoining drained tracts in Byelorussia's southern marshified lowlands, plots encompassing different plant cover, types of soil and ground-water levels, to ascertain the influence of ground-water level and its fluctuations on the formulation and productiveness of forest, field and meadow verdure.It was established that when the ground-water level diverged—higher or lower—from optimum (i.e., depth approximately equal to the height of the capillary lift), productiveness of plants fell; that intensive utilization and drying of peat bog soils led, as a rule, to mineralization of the peat and air and water erosion (the lower the level falls the more intensively mineralization proceeds). It is calculated that with cultivated crops the loss of peat is some 10 tons per hectare per year, 5-6 with cereals and 2-3 with grasses.Lowering the ground-water level on any area leads to changed levels on adjacent areas, the ground waters being elements of a unified system. In the sandy soils most widespread in the Byelorussian lowlands, lowering of ground-water level perceptible in the vital activities of plants occurs up to 2 kilometers from the drained tract. In all cases reductions in ground-water level and in the duration and height of flooding led to degradation of the meadows.It is concluded that comprehensive calculations on the possible harmful effects of drainage reclamation-caused changes in a large territory's hydrological regime are a prerequisite for rational utilization of the land and maximum productiveness and preservation of the natural landscape.

Notes: It has been demonstrated that a microcomputer costing less than $10,000 can accommodate a ground-water basin model with a large number of nodes. Analyses indicate that finite difference and finite element models with several hundred nodes also can be accommodated. Microcomputers have several advantages over the larger and much more expensive macrocomputers as ground-water basin modeling tools: easy to learn language used for programming, simplicity of operation, and low costs leading to easy access by investigators and users. Because of these advantages, willing investigators can learn to do modeling work by using a microcomputer and also write programsto computerize time-consuming tasks and thus effect substantial manpower cost savings.

Notes: Linear regression can be applied to multirate pumping test data from a single pumped well to estimate the constants of the equation 〈inlineGraphic alt="inline image" href="urn:x-wiley:0017467X:GWAT281:GWAT_281_mu1" location="equation/GWAT_281_mu1.gif"/〉. An equation 〈inlineGraphic alt="inline image" href="urn:x-wiley:0017467X:GWAT281:GWAT_281_mu2" location="equation/GWAT_281_mu2.gif"/〉 has been derived which enables the values of An at various times to be used to estimate the transmissivity of the aquifer adjacent to the pumped well with due allowance for well loss. An extension of method enables estimation of the order of the storage coefficient.

Notes: Programmable calculator programs have been previously given for the calculation of head or pressure change resulting from the pumping from or injection into wells completely penetrating a fully confined aquifer. Programs are documented and example calculations shown here for wells completely penetrating a semiconfined aquifer. The programs are for the TI 59 card programmable calculator.

Notes: A numerical model based on a finite difference technique has been developed to analyse and solve the problem of an unconfined coastal aquifer of infinite extent with free surface and interface along with the width of outflow face as unknown boundaries. The problem has been formulated in a complex potential plane and a five-point operator of a finite difference scheme has been used to reduce the governing flow equation into a set of linear algebraic equations which is solved by the Gauss-Seidel iterative method with an over-relaxation factor. Results of the analysis provide a generalised dimensionless plot for assessing the fresh-water flow to the sea from the known field information of aquifer characteristics and water-table head landward from the shoreline.

Notes: A gravity survey was conducted as part of a ground-water investigation covering 400 mi2 (1,000 km2) in Outagamie County, northeastern Wisconsin. The objective of the gravity survey was to supplement bedrock topography data obtained from well logs and seismic refraction profiles. The gravity method was chosen as it is a rapid and low-cost reconnaissance technique, and conditions in the study area were favorable for a successful gravimetric survey. The simple Bouguer gravity values were referenced to a local base station as only relative gravity values were required. The data were interpolated to a regular grid by an inverse-distance weighted average algorithm. The gravity residual was derived using a five-ring inverse weighted filtering routine. The residual map accurately reflects the major topographic features of the bedrock surface. A two-dimensional geologic model fitted to the residual data agrees well with the simple flat plate approximation used to obtain quantitative estimates of glacial drift thickness. Estimates of drift thickness from the gravity data also agree well with bedrock depths obtained from well logs. The most productive drift aquifers are restricted to the major bedrock valleys. Gravity data were coupled with seismic refraction and well data to produce a bedrock elevation map, from which it is possible to predict the extent and distribution of the major drift aquifers.

Notes: Despite sufficient rainfall, large parts of Eastern India suffer from water scarcity. Ground water occurs in weathered or semiweathered/fractured layers in hard-rock areas whose thickness varies, in general, from 5 to 20 m.Ground-water studies have been carried out in several areas in and around Dhanbad (Lat. 23°48′N, Long. 86°24′E) in Bihar State of India. The area covers Pre-Cambrian hornblende and feldspathic gneisses, schists, granulites, quartzites, metabasics and pegmatities. The area forms a part of ENE-WSW trending Satpura orogenic belt. The quartz reefs formed as fault fillings act as barriers to the flow of ground water. Geophysical investigations, using electrical methods, with Schlumberger configuration using AB up to 300 m were carried out at most of the locations. Conventional resistivity meters were used for this purpose.The data from 78 Schlumberger soundings has been analysed. Both A and H type curves were obtained. Spectrum of resistivity values has been prepared to study the over-all variation of resistivity values in the area. It is observed that the curves with arithmetic mean values are quite representative. The values obtained from spectral and regression analyses are nearly the same.The results of geoelectric soundings have been compared with the geological section wherever available. It is inferred that the thickness of the weathered layer as deduced from Schlumberger soundings includes partly the unweathered/fractured layer as well. An attempt has been made to find an empirical relationship between the daily yield of water in gallons/day and the longitudinal conductance (s = h/p) of the weathered layer. Two empirical relationships have been obtained, one for the winter months, December-January and the other for the summer months, June-July. A suitable explanation for the two curves has been given.

Notes: Abstract. Although Georgia receives approximately 50 inches of precipitation annually, concern over water quantity is increasing in this State. Historically, ground-water problems were associated with major urban-industrial withdrawals but recent irrigation development in the southwestern portion of the State has attracted attention. Irrigation withdrawals were exempted from the permit requirements of the 1972 Ground Water Use Act. This has led to an inability to manage the resource and questions regarding legal rights to the use of water. Current activities in the State indicate that measures may be taken during the 1980 session of the Georgia General Assembly to enable better management of the State's water resources.

Notes: In order to study the potential of the Deccan basalts as aquifers, the properties of transmissivity and storativity must be considered. Analysis of large-diameter dug wells tapping unconfined aquifers in the Deccan basalts shows that there exists a relationship between porosity and specific yield. The aggregate porosities of weathered basalts, vesicular basalts and fractured-jointed basalts are respectively up to 34%, 50%, and 15%. On the contrary, specific yield has a maximum value of 7%, 4%, and 1% respectively. In relation to aggregate porosity the specific yield is low suggesting that in Deccan basalts effective porosity constitutes only a small fraction of aggregate porosity. It is found that this effective porosity is about 7%. The weathered basalts and vesicular basalts have higher transmissivities than fractured-jointed basalt and, therefore, form better aquifers. The variation in transmissivity values in various directions, and from point to point, indicates that the Deccan basalts are hydrogeologically anisotropic and heterogeneous in nature.

Notes: The limiting factors for the, safe yield in the investigated coastal area were sea water along the coastline and saline water at about 250 m below sea level. Both types of salt water will intrude into existing wells, when the potential heads are changed sufficiently by increasing pumping. Besides this, the recharge rate due to precipitation affects the potential head.In a hilly central part of the region, water infiltrates into the ground, and seeps to the saturated zone where it flows some kilometers to flat marshy regions near the coast and estuaries. There it comes up to drainage systems near the land surface (long cycle).In the marshy region the infiltrated water exfiltrates into drains and ditches after a short passage of some meters in the upper zone of the aquifer (short cycle).The calibration of a digital ground-water model gave the existing ground-water budget. The prognostication of the safe yield was based on these results.The most interesting problem of model calculations was to take into consideration the dependence of the recharge rate on the depth of the ground-water table below the land surface. If the ground-water level is lowered by pumping below the drainage system, the short cycle will be interrupted. The downward seeping water flows within a saturated zone to the wells and affects the potential head. The greater the drawdown, the greater is the recharge rate. The depression of the water table by pumping is compensated up to a certain degree.

Notes: The numerical models used in ground-water studies are general computer programs that can be applied to a variety of hydrogeological conditions. These programs are based on approximations to the governing partial differential equations for ground-water flow and transport. To use these models requires an understanding of the physical problem and field data. Although program input data and output results are quantitative, the appropriate application of numerical models remains a partly subjective procedure. To use models, the hydrologist must assess the merits of alternative numerical methods, evaluate available data, estimate data where missing or absent, and interpret computed results. The review of previous model applications can provide valuable insight on how these tasks may be approached.

Notes: An investigation into the cause of high lake levels during the early 1970's in a ground-water dominant lake in northwestern Wisconsin was conducted from December 1976 to July 1978, in part to address allegations by shoreline property owners that regulation of water levels in a reservoir 2.4 km south of the lake had caused the high lake levels. High lake levels also coincided with above average precipitation. Data collected during the study allowed the definition of the ground-water flow system around the lake and the calculation of the water budget for the lake. Field data indicated that there is no ground-water flow between the reservoir and the lake and that ground water flowing out of the reservoir is intercepted by a trough in the potentiometric surface. The trough is probably oriented along a permeable fault zone or a buried river valley. A ground-water flow model was used to determine whether increased recharge rates of the magnitude that probably occurred as a result of above average precipitation in the early 1970's would be sufficient to account for the observed rise in lake level or whether regulation of the water level in the reservoir could be expected to affect lake level.

Notes: The San Bernardino Valley Municipal Water District was formed in 1954 to master plan the long-term water supply, including the importation of supplemental water, for that portion of the Upper Santa Ana River Basin area within the District.Prior to the development of a basin management program, the District first undertook to inventory the water resources available to it. Specifically, what is its quantity, distribution, quality, what stresses will the water supply be subjected to, and finally, how is it disposed of? To assemble and store this array of hydrologic data, the District, as part of its basin management program, has undertaken the creation of a hydrologic data base. To facilitate the storage and retrieval of all pertinent data, the District utilizes an on-site high speed digital computer. Into this data base, the District has loaded all available information pertaining to ground-water production, streamflows and diversions, rainfall, ground-water levels, basin recharge, basin inflow/outflow, water quality, and consumptive use. Development and selection of alternative strategies is made more effective because of the availability of historic and real time hydrologic data. An additional benefit derived from the basin management program is that the updating of the operational economics associated with the importation of State Project water can be made with the benefit of the most current data available. This allows the District to optimize its programs and thus maximize the limited resources available to it.

Notes: There are many geological situations where moving ground water transfers a significant amount of heat. Yet, while convective heat transfer is a common phenomenon, it is very difficult to treat analytically. In this paper we present a simple model of convective heat transfer in porous materials and a numerical method of solving the model. The model is then applied to three diverse field situations: (1) a thermal anomaly on the Hartville uplift in eastern Wyoming; (2) a fault-controlled hydrothermal system near Monroe, Utah; and (3) the Luanshya copper mine in the Republic of Zambia. In each case heat transfer by moving ground water is shown to explain the observed thermal anomalies satisfactorily. Our results indicate that in certain situations the effect of ground-water flow needs to be considered in making local and regional assessments of heat-flow data. Furthermore, temperature measurements can be very useful in estimating aquifer recharge, particularly when thermal conductivity and structural information are available.

Notes: Ground-water modeling begins with a conceptual understanding of the physical problem. The next step in modeling is translating the physical system into mathematical terms. In general, the final results are the familiar ground-water flow equation and transport equations. These equations, however, are often simplified, using site-specific assumptions, to form a variety of equation subsets. An understanding of these equations and their associated boundary and initial conditions is necessary before a modeling problem can be formulated.

Notes: In-hole tracer tests were used in a geohydrologic investigation of metamorphic rock at the Savannah River Plant near Aiken, South Carolina, to locate water-transmitting fractures and to determine the connectivity of these fractures between boreholes. Only after development of a conceptual model of the fracture occurrence and connection could the proper methods of analysis for the hydraulic parameters be selected.In-hole tracers were used to locate fractures in a borehole and supplemented other methods, such as core inspection, geophysical logs, borehole wall imaging techniques, dry drilling, and packer tests. The first three of these do not necessarily investigate fluid-transmitting fractures.In the study of the connectivity of fractures between boreholes, the in-hole tracer techniques supplemented determinations by the rapidity of hydraulic response and the use of between-well tracer tests.In hydraulically transmissive rock, fractures were located by changes in the velocity of the tracer pulse in response to adding fluid to the well. In virtually impermeable rock, the movement of the tracer pulse in the rock was normalized to the movement of another tracer pulse in the cased portion of the well because the movement was so slow that direct measurement was difficult. Connectivity of fractures between boreholes was determined by placing an in-hole tracer in one hole and measuring the movement

Notes: The High Plains region of mid-America depends on ground water to a huge extent. A review of three States-Texas, Colorado and Oklahoma—shows a disparity in ground-water management in the region. Texas landowners own the ground water as a property right and the emphasis is on local management districts to control ground-water use. Colorado, in contrast, has State control of ground water and regulation by permit from the State Engineer. Oklahoma is unique in tightly regulating ground water through limitations on pumpage, while still adhering to ownership by the individual landowner.In spite of these differences, six of the High Plains States have united in a joint effort to study the ground water in the Ogallala. A $6 million study funded by EDA will evaluate the economic impacts of ground-water mining and determine future water resources management in the region.

Notes: Ground-water modeling is a tool that can help analyze many ground-water problems. Models are useful for reconnaissance studies preceding field investigations, for interpretive studies following the field program, and for predictive studies to estimate future field behavior. In addition to these applications, models are useful for studying various types of flow behavior by examining hypothetical aquifer problems. Before attempting such studies, however, one must be familiar with ground-water modeling concepts, model usage, and modeling limitations.

Notes: Ground-water chemical quality in alluvial valleys can be stratified, which can cause well-water quality to vary with pumping time, especially after a pump shutdown of several hours. These changes in chemical quality could have public health implications for automatically controlled high-capacity municipal water wells that pump directly into the distribution mains.For a large number of municipal wells, the shapes of the curves for the change-in-specific electrical conductivity and the NO3-N content of well water during the first 96 minutes of constant rate pumping are reported after a 24-hour shutdown as compared with “steady-state” quality. The variables recovery-transmissivity, well specific capacity, type of well construction, and equivalent specific yield of aquifer computed from driller's logs of the bore holes were considered in the analysis.The results showed that well-water quality vs. time curves vary in shape and are related mainly to the well depth and the depth to the perforations. The “steady-state” specific electrical conductivity and NO3-N values were significantly correlated to each other and inversely to recovery-transmissivity and equivalent specific yield. The specific capacity of wells was related to the recovery-transmissivity and to type of well construction.