ALBERT

Notes: The existence of high-density, nearly-structureless bedrock buried by relatively low-density sediments makes gravity prospecting a very informative technique for bedrock-topography studies of the northern Appalachian Plateaus. Locating bedrock exposures and using available well data reduces the area of the gravity search. Depths to bedrock from wells correlate excellently with depths from gravity anomalies. The minimum anomaly detected was 0·18 milligal, corresponding to a depth of approximately 40 feet.

Notes: A comparative study was undertaken on the decay rates of three bacterial types (S. typhimurium, E. coli and S. faecalis), an enterovirus (poliovirus type 1) and a bacterial phage (f2) in ground water maintained under laboratory conditions. Except for f2 phage, all the microorganisms tested were relatively stable in ground water. S. faecalis survived best among all the bacteria tested and its decay rate was similar to that of poliovirus type 1.Under field conditions, bacterial indicators were also found to be stable in the ground-water environment. The decay rate for fecal streptococci was lower than for fecal or total coliforms in the shallow wells.

Notes: A technique has been developed for the determination of the exchangeable cation population of calcareous sandy material with cation exchange capacities of less than 1 meq/100 g. The technique involves the addition of exchange salt in the dry state to samples of porous media using original pore water as the exchange salt solvent. In applying this technique to samples from below the water table, the amount of pore water available for reaction is reduced by centrifuging in the field to bring the moisture content close to field capacity values. By utilizing the minimum amount of pore water, interferences during the exchange process due to calcite precipitation or dissolution are minimized. The extent of calcite dissolution or precipitation that occurs can be appraised by measuring alkalinity or total carbon on the pore water before and after addition of the exchange salt. Three salts, NH4C1, CsCl and LiCl were tested for their suitability for this technique. CsCl was found to be preferable because of its low tendency to dissolve carbonate and the preference of Cs+ on exchange sites.Application of the method to a field site in southern Ontario yielded a value of 0.51 ± 0·09 meq/100 g over 15 samples for the cation exchange capacity of a near surface glaciofluvial sand deposit. It is believed that this technique could be applied with reasonable accuracy and reproducibility to materials with exchange capacities of as low as 0·1 meq/100 g.

Notes: The upconing of the salt-water interface in an unconfined coastal aquifer due to water withdrawal by an infiltration gallery is analyzed numerically based on the variational formulation of the problem. Sometimes in coastal areas, from the point of view of safe withdrawal of water on a long-term basis, the use of an infiltration gallery is found to be feasible in preventing severe upconing of the interface that would have resulted from heavy pumpage by a vertical well. The numerical procedure presented here is capable of delineating profiles of the free surface and interface along with the length of the outflow face and quantity of freshwater flow to the sea. Full consideration of the nonlinear boundary conditions on the free surface and interface is included for a steady flow towards a gallery in both isotropic and anisotropic aquifers. The extent of upconing of the interface under different operating conditions of the gallery for different aquifer geometries has been studied. A general understanding of the flow phenomenon in the vicinity of the gallery has been established. The results of the analysis can be used to plan a water withdrawal scheme without causing contamination by salt water.

Notes: The streambed-leakage factor ranged from 0.11 to 1.68 million gallons per day per acre per foot of head loss. Most values for the streambed infiltration rate and the streambed-leakage factor for six tests before 1970 were higher than for six tests in 1976–79, suggesting a change in streambed permeability in the intervening time.A well field to serve a government-owned uranium enrichment facility, consisting initially of 4 wells, later increased to 15 wells, was designed to yield up to 20 million gallons per day. The wells are on a line parallel to the river at distances from the stream ranging from 122 to 330 feet. Distance between wells ranges from 190 to 303 feet. Specific capacities of the wells, based on 24-hour acceptance tests, ranged from 63 to 147 gallons per minute per foot of drawdown and averaged 100 gallons per minute per foot of drawdown. By late Summer of 1976, pumpage from all 15 wells ranged from 12 to 15 million gallons per day. Drawdown was about as expected, based on design criteria developed from the aquifer tests, except that pumping levels were lower than expected in the Fall and Winter of 1976–77, resulting from low streamflow and low river temperature.

Notes: Vast deposits of oil shale are contained in the Piceance basin in northwestern Colorado. The basin may contain as much as 40 million acre-feet of stored water associated with these deposits, much of which may have to be drained for mining. Yet, most analyses of watersupply for oil-shale development have focused on surface water with only brief mention of ground water.This study used a synthetic streamflow model to investigate the effects of using conservative estimates of ground water on the required active storage capacity of a hypothetical reservoir on the White River. Results of the study indicate that use of ground water from mine drainage and/or auxiliary wells may have a significant impact on the size and timing of surface-water reservoirs. Thus, ground water may be an important source of supply, particularly during early development of an oil-shale industry. The study results strongly suggest that further investigations are needed on the physical availability of ground water as well as the institutional, legal and waterquality constraints on its use.

Notes: Egypt is presently involved in a comprehensive program of land reclamation. Surface water has already been exhausted in meeting the urgent needs of agricultural expansion. If irrigation efficiency were increased, large amounts of surface water would be saved. However, this entails complex social, technical and political problems outside the scope of this paper. Ground-water development has priority over increasing irrigation efficiency (which would take a longer time).This paper deals with identification of the intruded salt-water wedge in the huge artesian Delta aquifer. The case is unique because most of this aquifer is invaded by salt water, and the major portion of its annual ground-water recharge is derived from the direct seepage from the Nile River and the huge net of irrigation canals serving about 3 million acres (∼ 11,561 km2) of fertile land, as well as the infiltration of excess irrigation water. The annual overall ground-water recharge to the aquifer was estimated as 6·40 km3/yr as explained later.Methods of salt-water control and various techniques of water resources management are discussed in this paper. Because of the great variation in the depth of the aquifer, two unconventional methods for identifying the salt-water wedge are also presented.

Notes: . Programs are presented for the HP41C and TI59 programmable calculators for determining the ratio of horizontal to vertical hydraulic conductivity in anisotropic confined aquifers from pumping test data or for calculating drawdown given the aquifer parameters. The programs, based on Hantush's drawdown equations (1961), eliminate the need to perform triple interpolation in obtaining the drawdown correction factor given in tabular form by Weeks (1969). The programs are illustrated by example.

Notes: A numerical model of flow and transport in the vicinity of Price's Landfill and the Atlantic City public water-supply wells is used to estimate the extent of the existing contamination problem. Model parameters such as boundary conditions, pumping rates, permeability, and dispersivity are varied to demonstrate the sensitivity of the model to these quantities. A historical simulation of the past ten years of contamination is obtained and two schemes for remediation of the contamination problem are compared. In the light of this work, additional data requirements are revealed.

Notes: Ion-exchange high performance liquid chromatography coupled with ultraviolet absorption detection is shown to be a rapid and sensitive method for analysis of some common anions in water. Sensitivity of measurement is approximately 50 ppb for NO−2, NO−3, Br−, I−, and SCN− while Cl− has a detection limit in the one to ten ppm range. Chromatograms require 8 to 13 minutes to complete. Analyses are performed on either of two stationary phases (Whatman SAX 10 μm or Brownlee anion exchange) depending on the anions of interest in the analysis and their interferences.

Notes: Vertical electrical soundings using DC resistivity methods have been completed along over 60 miles of survey lines in southwest Florida. The resistivity soundings were obtained in order to outline major hydrogeologic features as part of a regional hydrogeologic investigation covering approximately 400 square miles. The two significant hydrogeologic features which can be effectively mapped on a regional scale by DC methods are the presence of shallow, high resistivity limestones associated with late Tertiary reef complexes, and the approximate depth to waters with TDS concentrations well above the potable water limits. The reef limestones commonly exhibit very high transmissivities and are potential sites for ground-water development. The approximate thickness of potable waters allows resource investigations to be limited to the most promising areas and a rough assessment of the total resource to be made for long-term planning. The interpretation and mapping of the resistivity section is accomplished through published resistivity inversion and computer graphics programs. This automated data processing produces resistivity maps and sections without requiring extensive geophysical training of the interpreter. The automatic interpretations compare well with more traditional master curve interpretation procedures, and have the same limitations with equivalence of solutions and geologic correlation, but are produced with considerably less effort.

Notes: With an Apple II microcomputer it is possible to rapidly generate and graphically compare theoretical time-drawdown curves with field data from pumping tests in confined aquifers. This technique has the advantage over standard curve-matching methods in that any solution can be tested over the complete range of field data.

Notes: Four formally equivalent response modes were used to elicit laypeople's beliefs regarding the lethality of various potential causes of death. Results showed that respondents had an articulated core of beliefs about lethality that yielded similar orderings of maladies by lethality regardless of the response mode used. Moreover, this subjective ordering was fairly similar to that revealed by public health statistics. However, the absolute estimates of lethality produced by the different response modes varied enormously. Depending upon the mode used, respondents were seen to greatly overestimate or greatly underestimate lethality. The implications of these discrepancies for public education and risk analysis are explored.

Notes: The differences between probabilistic risk assessment (PRA) and safety analysis (SA) are discussed, and it is shown that PRA is more suitable than SA for determining the acceptability of a technology. Since a PRA by the fault tree-event tree analysis method used for reactor safety studies does not seem to be practical for buried waste, an alternative approach is suggested using geochemical analogs. This method is illustrated for the cases of high-level and low-level radioactive waste and for chemical carcinogens released in coal burning.

Notes: Public opinion poll data have consistently shown that the proportion of respondents who are willing to have a nuclear power plant in their own community is smaller than the proportion who agree that more nuclear plants should be built in this country. Respondents’ judgments of the minimum safe distance from each of eight hazardous facilities confirmed that this finding results from perceived risk gradients that differ by facility (e.g., nuclear vs. natural gas power plants) and social group (e.g., chemical engineers vs. environmentalists) but are relatively stable over time. Ratings of the facilities on thirteen perceived risk dimensions were used to determine whether any of the dimensions could explain the distance data. Because the rank order of the facilities with respect to acceptable distance was very similar to the rank order on a number of the perceived risk dimensions, it is difficult to determine which of the latter is the critical determinant of acceptable distance if, indeed, there is only one. There were, however, a number of reversals of rank order that indicate that the respondents had a differentiated view of technological risk. Finally, data from this and other studies were interpreted as suggesting that perceived lack of any other form of personal control over risk exposure may be an important factor in stimulating public opposition to the siting of hazardous facilities.

Notes: This paper examines how LP/HC (low-probability/high-consequence) risk analysis is used in planning for locally unwanted land uses, or LULUs. LULUs are development projects that are predictably objectionable to many of their neighbors. Examples are nuclear power plants, hazardous waste facilities, refineries, and airports. The paper begins by elaborating the idea of LULUs, focussing on those whose planning typically requires or invokes some form of LP/HC risk analysis. It then discusses how land planning and planners actually use the LP/HC approach to deal with LULUs. It argues that in practice land-use planners and their associates employ a concept of risk different from that of economists, scientists, and engineers and more like that of political decision-makers and the public at large. It concludes with a political interpretation that offers some suggestions for productively reducing this divergence in the treatment of LULUs that pose LP/HC risks.

Notes: The rapid aging of the U.S. population, increases in the absolute prevalence of chronic diseases, and the associated rise in the proportion of the GNP expended on medical care all indicate the need for methods to accurately forecast future health care expenditures for specific chronic diseases. Additionally, if these methods are biomedically realistic, they can be used to evaluate the economic implications of specific prevention strategies designed to reduce chronic disease incidence, prevalence, and mortality. Projection strategies that are not biomedically realistic, such as models that assume that risks for demographic subgroups do not change over time (e.g., “static component” models), though possibly accurate over the short run, are not suitable for assessing the long term effects of specific proposed health policy interventions which are designed to alter risks.In this paper we present a strategy for forecasting health care costs which is based on a model that represents the natural history of a chronic disease in terms of a preclinical state, a clinical state, case fatality rates, cures, and the implications of exogenous medical factors. Using this model we project that the treatment costs associated with respiratory cancer in the white male population of the U.S. may undergo a two-thirds increase in real dollars over the period 1977 to 2000. About one-half of this increase is due to a demographic shift to an older population structure, with the remainder due to higher respiratory cancer incidence rates in younger cohorts. Alteration of certain parameters of the model to simulate various interventions suggests that about three-quarters of the cost of this disease could be eliminated, though realization of any significant part of this savings would require a lengthy phase-in period.

Notes: This methodology begins by quantifying the fragility of all key components and structures in the plant. By means of the logic encoded in the plant event trees and fault trees, the component fragilities are combined to form fragilities for the occurrence of plant damage states or release categories. Combining these, in turn, with the seismicity curves yields the frequencies of those states or releases. Uncertainty is explicitly included at each step of the process.

Notes: A classical decision problem is considered where a decision maker is to choose one of a number of actions each offering different consequences. The outcome from a choice of action is uncertain because it depends on the existing state of Nature. Also, the outcome, once an action and state of Nature are specified, may be a vector or a random vector. The decision maker employs both Bayesian methods and fuzzy set techniques to handle the uncertainties. The decision maker is also allowed to use multiple, possibly conflicting, goals in order to determine his best strategy. The Bayesian method produces a set of undominated strategies to choose from, whereas the fuzzy set technique usually produces a unique optimal strategy.

Notes: Scientists have long used conventional toxicological methods to establish “safe levels of exposure” for chemicals presumed to have threshold health effects or doses below which significant effects are unlikely to occur. These same methods cannot be used to establish safe levels of exposure for non-threshold pollutants, such as carcinogens. Therefore, Federal regulatory agencies in the United States are using risk assessment methods to provide information for public health policy decisions concerning increases in risk associated with increases in exposure to carcinogenic and other non-threshold pollutants. Acceptable exposure/risk levels are decided by policymakers who consider descriptions and estimates of risks together with social and economic benefits from the uses of the chemical. This paper focuses on the development of quantitative risk assessment approaches by Federal regulatory agencies in the United States, and identifies the mathematical models currently being used for risk extrapolation, including their inherent uncertainties. The uncertainties and limitations of these methods have led some scientists to question the utility of quantitative risk extrapolation. The experience of the U.S. Environmental Protection Agency (EPA), as summarized in this paper, can provide a realistic basis for evaluating the pros and cons. Finally, shortcomings in current risk assessment methods and their use in policy decisions are explored, and areas for possible improvement, given current scientific knowledge, are identified.

Notes: Risk acceptance criteria in the form of limit lines are investigated in the context of prospect theory. This theory departs from utility theory in several respects, an important one being the use of weights other than probabilities in the evaluation of the expected impact of uncertain outcomes. Hypothetical functions reflecting certain attitudes toward consequences and rare events are developed and combined to produce several limit lines.

Notes: In this paper, we argue that risk in a new situation can be calculated by comparison with the most closely analogous previous situation that we can find. In many cases, such as automobile accidents, we argue that this year is analogous to preceding years. With toxic chemicals the analogy is less direct—we compare with other toxic chemicals or with chemicals shown to be toxic in other species. Because the unreliability or uncertainty of the analogy can be high, it is necessary to use less sensitive, but more reliable, methods of estimating risk to prevent continued use of a hazardous material, and subsequent tragedy if the hazard should turn out to be unexpectedly large. This suggests more robust techniques to reduce the regret, or societal cost of being wrong, because increased sensitivity is sometimes attained at the expense of sampling error.

Notes: Analysis of energy-system impacts requires quantifications of short- and long-term local, regional, and global modifications. This paper describes and illustrates an approach for assessing long-term health risks due to dispersion of naturally occurring radionuclide series and chemical toxins by normal and altered landscape-chemical cycles. Health hazards are expressed as dose factors which convert environmental concentrations into a corresponding dose field (organ doses in rad for radionuclides; daily intake for toxic elements). The dose field is translated into a population health risk. The external environment is modelled by considering the manner in which elements are distributed and mobilized within the earth system. The landscape prism is presented as a tool for visualizing and mapping toxic material cycles near the crustal surface. An approach is provided for dividing the landscape into a set of compartments consistent with patterns of element circulation observed in the global environment. We investigate the response of regional landscapes to increases of 238U, 226Ra, arsenic and lead in soil and groundwater. It is found that each decay series or element imposes a hazard by its behavior in the total environment that cannot be quantified by a simple measure of toxicity.

Notes: Many risks have the property that large numbers of people are exposed and have little or no individual control over the risks they face. Dams, nuclear power plants, and recombinant DNA research have proven controversial not simply because there is vast uncertainty about the true level of risk associated with each, but because a fundamental issue is that in each case social risks can be lessened by spending more on safety: dams can be designed to withstand larger earthquakes, nuclear plants can have additional safety equipment, and DNA research could be done in yet more carefully isolated laboratories. Since each person will have preferences regarding the proper trade-off between increased cost and increased safety, there is little possibility of consensus. More importantly, we show that a voting process for expressing individual preferences can be manipulated and is seriously flawed in the sense that it does not lead to an “efficient” outcome. In addition, we show that virtually all people are unhappy with the safety decision, in the sense that each would prefer either a safer or a cheaper outcome. Thus, making safety decisions that affect a large group of people who will not be able to control the outcome is even more difficult than has been appreciated. We suggest some ways of handling some of the difficulties.

Notes: An estimation of the human lung cancer “unit risk” from diesel engine particulate emissions has been made using a comparative potency approach. This approach involves evaluating the tumorigenic and mutagenic potencies of the particulates from four diesel and one gasoline engine in relation to other combustion and pyrolysis products (coke oven, roofing tar, and cigarette smoke) that cause lung cancer in humans. The unit cancer risk is predicated on the linear nonthreshold extrapolation model and is the individual lifetime excess lung cancer risk from continuous exposure to 1 μg carcinogen per m3 inhaled air. The human lung cancer unit risks obtained from the epidemiologic data for coke oven workers, roofing tar applicators, and cigarette smokers were, respectively, 9.3 × 10−4, 3.6 × 10−4, and 2.2 × 10−6 per μg particulate organics per m3 air. The comparative potencies of these three materials and the diesel and gasoline engine exhaust particulates (as organic extracts) were evaluated by in vivo tumorigenicity bioassays involving skin initiation and skin carcinogenicity in SENCAR mice and by the in vitro bioassays that proved suitable for this analysis: Ames Salmonella microsome bioassay, L5178Y mouse lymphoma cell mutagenesis bioassay, and sister chromatid exchange bioassay in Chinese hamster ovary cells. The relative potencies of the coke oven, roofing tar, and cigarette smoke emissions, as determined by the mouse skin initiation assay, were within a factor of 2 of those determined using the epidemiologic data. The relative potencies, from the in vitro bioassays as compared to the human data, were similar for coke oven and roofing tar, but for the cigarette smoke condensate the in vitro tests predicted a higher relative potency. The mouse skin initiation bioassay was used to determine the unit lung cancer risk for the most potent of the diesel emissions. Based on comparisons with coke oven, roofing tar, and cigarette smoke, the unit cancer risk averaged 4.4 × 10−4. The unit lung cancer risks for the other, less potent motor-vehicle emissions were determined from their comparative potencies relative to the most potent diesel using three in vitro bioassays. There was a high correlation between the in vitro and in vivo bioassays in their responses to the engine exhaust particulate extracts. The unit lung cancer risk per μg particulates per m3 for the automotive diesel and gasoline exhaust particulates ranged from 0.20 × 10−4 to 0.60 × 10−4; that for the heavy-duty diesel engine was 0.02 × 10−4. These unit risks provide the basis for a future assessment of human lung cancer risks when combined with human population exposure to automotive emissions.

Notes: In this paper we extend the work reported in prior studies. The conclusion drawn from the aggregate of those studies was that the limitation on liability imposed by the Price–Anderson Act for a catastrophic accident at a nuclear power plant ($560 million) is comparable to de facto limitations on recovery following catastrophic events in many other industries. The analysis in those reports was at a high level of abstraction, comparing almost exclusively the potential loss from high consequence accidents with the current assets of major firms in relevant industries. We found that potential loss exceeded assets.

Notes: The U.S. Office of Science and Technology Policy describes toxic substance regulation as composed of two stages. Stage I (facts) uses empirical data and scientific judgment to characterize human exposure and risk. Stage II (values) uses social and political judgment to decide regulatory action based on significance of the risk, benefits of the agent, and costs of its control. This paper argues that such a view represents an unrealistic and unattainable goal. We present examples showing how values enter virtually every part of risk analysis, and we review work on the vagaries in human judgment concerning both facts and values. These issues indicate that U.S. regulatory policy needs reconsideration.

Notes: In this paper we propose a framework for conducting a decision analysis for a societal problem such as earthquake safety. The application deals with the formulation and evaluation of alternative policies for the seismic safety problem faced by the city of Los Angeles with regard to its old masonry buildings. A social decision analysis compares the costs and benefits of the alternative policies from the viewpoints of the impacted constituents. The emphasis is on identifying acceptable policy that considers the interests of the impacted constituents and provides incentives for their cooperation. Alternatives ranging from strict regulation to free market are examined. In order to evaluate the trade-offs between additional cost and savings in lives, a direct willingness-to-pay and an economic approach, based on property value differential, are used. Recommendations range from strict regulation for the residential and critical buildings (schools, hospitals, fire stations, etc.) to simply informing the occupants (in the case of commercial and industrial buildings) of the risks involved.

Notes: Measures to tighten homes to conserve energy, as are being encouraged and subsidized by federal and state governments, may reduce air infiltration by 20% or more. Standard prudent risk-assessment methodologies predict that, due to increased levels of indoor radon caused by this reduction in ventilation, the added lifetime lung cancer risk to members of the public is of order 200/million people exposed. In situations where the radon source term is unusually high, or extreme reductions in ventilation are made, the added risk can be more than an order of magnitude greater. While these imputed risks are far outside the range that is normally tolerated, no systematic efforts are in progress to mitigate or limit the risk in any way. Furthermore, efforts to determine better the variations in radon source term and the health effects of indoor radon are being deemphasized. The technical background is presented in some detail, and implications with regard to management of risks to the public are discussed.

Notes: Book Reviewed in this article:Risk Analysis of Six Potentially Hazardous Industrial Objects in the Rijnmond Area, A Pilot Study

Notes: The ages and origins of saline ground waters in coastal aquifers can be important indicators of local aquifer flow characteristics. Unfortunately, attempts to classify such waters using established trilinear diagram techniques are frequently inconclusive due largely to the dominance of sodium and chloride ions. In a study of saline ground waters from the Chalk limestone of eastern central England, an alternative, less conventional, dilution diagram procedure is employed which reveals previously unrecognized differences in local major ion chemical character. These differences are interpreted in terms of the origins of the saline ground waters and their histories of mixing. Significantly, the interpretations reinforce and, in some cases, refine earlier interpretations based on notably less extensive minor ion and environmental isotope data. It is concluded that the saline ground waters are associated with at least three periods of saline intrusion during the past 120,000 years.

Notes: A programmable calculator program is given along with examples for a general impulse response function for calculating step and rectangular pulse response for stream-aquifer interaction, pumping in leaky and nonleaky artesian aquifers, and two-dimensional dispersion.

Notes: The Pearl Harbor aquifer, an important ground-water resource for southern Oahu, Hawaii, contains an enormous fresh-water lens, up to 300 m (1,000 ft) thick, floating above saline water. The upper boundary of the fresh-water lens is confined near the coast and phreatic inland, whereas its lower boundary is not confined. A finite-difference flow model was used to simulate the Pearl Harbor aquifer system. The location of the fresh-water/salt-water interface, which constitutes the lower boundary of the flow system model, was estimated by Hubbert's formula. Known geohydrologic boundaries and aquifer parameters were also simulated. First, formation of the lens by filling the aquifer with fresh water from natural recharge was simulated to reconstruct the initial conditions before exploitation of the lens and to partially calibrate the model against the hydraulic-head distribution in 1879. The model then was calibrated fully by simulating the lens’reponse to actual historical pumping patterns covering a time span of 100 years (1880 to 1980). Simulated heads compared favorably with the observed heads over time and space. The calibrated flow model may serve as a useful tool in the management of the Pearl Harbor aquifer.

Notes: Most underground coal mines in Illinois are relatively dry despite their location in saturated rock lying hundreds of meters below the water table. This is probably due to the low permeabilities of the rock units associated with the coal seams. Little is known about how mines affect the groundwater system, so it is difficult to predict where a mine is likely to encounter an influx of ground water.To obtain information on the hydrogeological character of the roof rocks, an array of piezometers was installed in roof-bolt holes at two locations within an underground coal mine in central Illinois. Pressure vs. time measurements were obtained from piezometer arrays located in areas of the mine ranging from dry to wet conditions. Data collected from the piezometers indicate that water drainage from a saturated sandstone above the coal is largely controlled by local structural and stratigraphic features, and these features determine the distribution of wet and dry areas in the mine. Hydraulic conductivities of the sandstone were determined in the laboratory and in situ from drainage profiles and from tests of instantaneous head changes. Results of these tests indicated that dewatering in front of mining would not be successful in this mine.

Notes: A hydrogeologic investigation was conducted to determine the source of recharge to the Littlefield Springs, a series of carbonate springs occurring along a 10 km (6 mile) reach of the Virgin River in northwestern Arizona. The most probable sources of recharge to the springs were determined to be influent Virgin River water and precipitation within the springs hydrologic basin. These recharge sources could account for the total discharge of the springs. The Littlefield Springs have essentially constant discharge 1.84 cms (65 cfs), and quality 2940 mg/L TDS. Tritium analyses of the spring and river water indicate that there are at least two different sources of recharge to the Littlefield Springs–one a minimum of 22 years old and the other younger than 22 years old. Analysis of the influent Virgin River upstream from the springs indicates a 1·42 cms (50 cfs) loss at 2130 mg/L TDS and the same ionic ratio of dissolved constituents as the springs. The travel time of this recharge source is interpreted to be a minimum of 22 years. Local recharge to the springs has been estimated to be 0·31 cms (11 cfs). The presence of local recharge is indicated by pulse train gaging of the springs, and by water quality at a well upstream of the springs and at the first upstream occurrence of the springs. The travel time of this recharge source is interpreted to be less than 22 years.

Notes: The cation composition of water in the Aquia aquifer of southern Maryland changes systematically in the direction of ground-water flow. In the upgradient parts of the aquifer, calcium is the dominant cation in solution. Between 10 and 20 miles downgradient, calcium and magnesium are dominant. Between 20 and 35 miles downgradient, magnesium and potassium are dominant, and, beyond 40 miles downgradient, sodium is the most abundant cation in solution. The exchangeable cation composition of glauconite in the Aquia aquifer changes systematically in the direction of flow in a manner similar to the changes in water chemistry. These observations are interpreted as evidence that cation exchange reactions are processes that simultaneously alter water composition and glauconite composition along the flowpath.Exchange parameters K’and n for glauconite in the Aquia aquifer were determined for the reactions: 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT343:GWAT_343_mu1"/〉〈displayedItem type="mathematics" xml:id="mu2" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT343:GWAT_343_mu2"/〉〈displayedItem type="mathematics" xml:id="mu3" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT343:GWAT_343_mu3"/〉 The exchange parameters for each reaction were tested by an indirect method. Molar ratios of exchangeable cations or glauconite were calculated from water chemistry data using the derived k’and n values. In each case, the trend of calculated molar ratios compared favorably with measured molar ratios. The calculated exchange parameters demonstrate that the exchange process is not linear for the Ca2+ -Na+ and Mg2+ -Na+ ion pairs.The sum of exchangeable cations on glauconite samples is significantly lower in the outcrop area than downgradient. Corresponding to this, the concentration of dissolved silica and dissolved oxygen in Aquia water is high near the outcrop area and decreases downgradient. This pattern suggests that incongruent dissolution of glauconite is an additional process that modifies glauconite composition near the outcrop area but is less important downgradient.

Notes: One of the primary problems in field investigations of ground-water pollution is locating the contaminant plume. Drilling of sampling holes on a hit-or-miss basis is both time-consuming and expensive. Under many subsurface conditions, surface electrical resistivity profiling can quickly and cheaply locate the general position of the plume and identify areas most feasible for sampling and monitoring. Many contaminants contain an ionic concentration considerably higher than the background level of native ground water. When such a contaminant is introduced into an aquifer, the electrical resistivity of the saturated soil is reduced. Surface electrical resistivity profiling across a suspected area can identify this reduced resistivity zone as an anomaly. The sensitivity of the method depends on relative uniformity of geology and topography as well as minimal extraneous electrical interferences. It is also essential that the “A” spacing used in the profiling procedure be carefully selected. If the resistivity contrast between contaminated and uncontaminated ground water is high, detection of at least the central part of the plume is likely within expected geologic variation. The method has been successfully used in the location of plumes from contaminants including brine, uranium reprocessing liquid wastes and landfill leachate in glacial deposits of New England.

Notes: The Piper (1953) trilinear diagram has been widely used to graphically represent the dissolved constituents of natural waters and to test for apparent mixtures of waters from different sources. Because of the time required to plot points and calculate the proportional values of mixing, this treatment of data was often quite tedious, particularly in studies involving large numbers of chemical analyses. The PIPER program was written in BASIC to be run on a Hewlett-Packard desktop computer with an X-Y plotter. Data input is in ppm units. The program plots points in all three fields of the trilinear diagram, draws at each point within the central diamond field a circle with a radius correspondent to the concentrations expressed in meq/1, checks for points that fall on a straight line (or within a predetermined tolerance of a straight line) representing postulated mixtures with two end members, and/or within a triangle representing mixtures of three end members. Finally, the program does a numerical analysis of the mixing ratios of the constituents for postulated mixing systems according to the methodology as presented by Piper (1953).

Notes: An investigation was conducted to evaluate the effects of aquifer interconnection caused by the collapse of cavities formed in coal seams by two small underground coal gasification experiments in the Powder River Basin, Wyoming. The main objective of the work was to assess the magnitude and extent of changes in the ground-water flow patterns near the sites of the two experiments. Hydraulic head measurements in the three affected aquifers were used to calibrate a steady-state ground-water flow model of the interconnection zone at each site. Flow modeling and field measurements show that water from one or both of the upper aquifers enters the collapse rubble and flows down to the lowest aquifer (the gasified coal seam) where it flows away from the collapse zones. The hydraulic conductivity of the collapse rubble is less than that of the aquifers and provides only a very moderately permeable interconnection between them. A marked reduction in the hydraulic conductivity of the gasified coal seam near the collapse zones causes restriction of flow in the seam, away from them. Changes in hydraulic head and flow patterns caused by aquifer interconnection extend generally only 200–300 ft (60–90 m) away from the experiment sites. Flow in the uppermost aquifer at one of the sites may be influenced as far as 400 ft (122 m) away. At both experiment sites, aquifer interconnection allows water from the uppermost (sand) aquifer, which contains the poorest quality water of the three aquifers, to enter one or both of the underlying coal aquifers.

Notes: Numerical models can be used to aid in the design and licensing of dewatering and depressurizing systems by simulating changes in hydraulic head produced by the interference patterns of various configurations and pumping rates of wells, wellpoints, or ejectors. The total quantity of water that must be pumped to achieve the desired objective can be approximated by modeling the inflow rate into a network of constant-head nodes located around the perimeter of an excavation and assigning a hydraulic-head value to these nodes equivalent to the average level to which the water table or potentiometric surface would be lowered by a dewatering or depressurizing system. As a result, it is possible to determine the decrease in the inflow rate as the flow system goes from the period of transient flow, when significant quantities of water are released from storage in unconfined aquifers and hydraulic gradients are steeper, to the period of steady-state flow when no water is released from storage and hydraulic gradients are flatter. Based on the inflow rate data, simulations can be made showing the effectiveness of various pumping well configurations. In these simulations, the number, location, and pumping rates of wells can be varied to design a dewatering or depressurizing system that maximizes well interference and drawdown with a minimum number of wells. Decreases in the inflow rate during transient flow can be accounted for by adjusting well discharge rates during the transient flow period.Simulation results can be used to determine the radius of influence of the system, calculate induced drawdown in nearby wells, determine the amount of time required for predrainage prior to construction, calculate the amount of induced infiltration from nearby surface-water

Notes: After analysis of the geological, hydrological, hydrochemical, isotope, and pumping test data of the karst aquifer in the Mesozoic Tripolitza carbonates of the Molai area, it was concluded that the carbonates contain two flow systems. The western system discharges through the shore and submarine springs at Glyfada into the Gulf of Lakonia; its catchment, which has no exploitable reservoir, is connected to the springs by a narrow conduit related to a fracture zone in marbles that accompany the Molai fault. The eastern flow system, along the northern fringe of the Molai Plain, has a reservoir with acceptable (less than 120 m deep) pumping levels; its water quality, however, is variable. The system discharges, probably by dispersed seepage flow, into the Aegean Sea. The unusual characteristics of the karst in the Molai area can be explained by the continuous tectonic activity which has prevented the completion of various stages of karst development.

Notes: . Observations on the collapse of a medieval castle built on an artificial mound testify that contemporary slippage was adroitly accommodated by building adjustments. However, 300 years of continuous usage without an effective waste disposal system eventually caused the latrine tower to collapse.

Notes: The hydraulic properties of commercial well screens were investigated to determine which screen design features affected head loss. The test program began with laboratory experiments and continued as a field-scale experiment with the installation of a well field in the Thames Valley Gravel Aquifer.The laboratory experiments indicated that, for all practical purposes, the head loss attributable to all of the screens tested was negligible. The experimental head loss, however, did vary from screen to screen, particularly at high intake velocities, and the screens could be ranked on the basis of their hydraulic efficiencies. This efficiency hierarchy is explained tentatively in terms of the screen construction methods and slot geometry. The field experiments showed that the hydraulic performance of all well screens is independent of screen design provided that the open area of the screen is above about 10%. The field experiments also indicated that the development capacity of a screen in a gravel aquifer is not wholly dependent on screen design, but that progressive development does increase the hydraulic efficiency of a well.

Notes: Based on 13 aquifer infiltration tests at 11 sites, aquifer transmissivity ranged from 17,000 to 40,000 square feet per day, and the streambed infiltration rate ranged from 0·06 to 0·19 million gallons per day per acre along a seven-mile reach of the Scioto River in south-central Ohio. Despite these wide ranges, the sand and gravel aquifer, 40 to 65 feet thick, underlying 10–20 feet of river alluvium south of the glacial boundary, is fairly homogeneous due largely to the absence of till interbeds.Performance of a major well field designed on the basis of the tests has been about as predicted, validating the techniques of data collection and analysis.At each site, a well for pumping was drilled on the floodplain, 150 to 750 feet from the river, and an array of observation wells was installed on lines extending through the pumped well, one line perpendicular to the river and the other parallel.Values of drawdown measured in the observation wells at the end of constant-rate pumping periods, usually of three days duration, were used to determine line-source distance and aquifer transmissivity. The rate of streambed infiltration and the streambed-leakage factor, the latter term relating the infiltration rate to drawdown beneath the stream, also were determined at all but one site. Drive-point wells installed in the riverbed, or along the near bank, in the vicinity of the pumped well were used to determine drawdown beneath the river due to pumping.

Notes: Significant amounts of brine produced in conjunction with oil well operations in the Greater Altamont-Bluebell field have been disposed of to surface impoundments. Mass balance calculations indicate that about 93% of this brine, a total of 4,430 acre-feet (5·45 × 106 m3) over the ten-year period studied, is lost through seepage, introducing a total salt load of 200 million pounds (90 × 106 kg) into the shallow aquifer system. Estimates of salt-water plume movement indicate that potential adverse economic impacts on irrigators and other water users in the Duchesne River Valley could reach hundreds of thousands of dollars. Lining of disposal ponds and increased use of injection wells will reduce future contamination. A monitoring program should be set up to determine actual levels of contamination of domestic and agricultural water supplies.

Notes: Abstract. Installation of shallow sand-packed piezometers in auger holes with caving saturated sands in the Great Dismal Swamp of Virginia and North Carolina was greatly facilitated by freezing the piezometer and sand pack together. The frozen unit made it possible to install up to three wells per day with little difficulty.

Notes: Ground-water management in coastal aquifers is becoming highly complex due to the increase in water demand coupled with the threat of salt-water encroachment. The salt-/fresh-water interface produced by the natural flow of the aquifer is distorted as a result of ground- water exploitation. The solution of these problems includes several simplifications of unknown effects. This paper deals with the first phase in ground-water management, namely locating the interface due to natural flow by simple equations which give results practically the same as the rigorous solution.During the last four decades, the use of the Ghyben-Herzberg (G-H) principle to determine the salt-/fresh-water interface in coastal aquifers was questioned by many investigators due to the neglect of the water movement. Some of the highly complex solutions which were later introduced are reviewed in this paper and compared with the G-H results for a very wide range of parameters. It has been found that the G-H principle is valid for practical purposes and that the differences between location of the interface predicted by the G-H principle and those determined by the rigorous solutions may be less than the differences resulting from small errors in the field records of water levels.For exceptionally high natural velocities and/or for more precision within the zones very close to the shore, two simple equations derived on the basis of the rigorous solutions are given. Each equation is written in terms of the practically popular G-H solution with a correction factor added. The results of these equations are tabulated in dimensionless values for practical use. Moreover, the extent and size of the fresh-water lens can be determined from the field records of one or two shallow observation wells. An illustrative example is given to clarify the procedure.

Notes: Toxic waste contamination is currently threatening the Atlantic City, New Jersey public water-supply wells. The geohydrologic data for this region are presented and organized into a format suitable for a numerical model study of the contamination problem. Presentation of the data in light of numerical work reveals the importance of good estimates of boundary conditions, historical pumping records, reliable water-quality data, accurate well logs, and reasonable parameter estimates. One set of measured head data is simulated.

Notes: AQMODL is an analytical mathematical aquifer modeling program for the HP-41C handheld programmable calculator. It does not require any written instructions for its use. It guides the operator through its use and prevents operator error. It is designed so that it can be used by anyone only basically familiar with the operation of the HP-41C calculator, and with aquifer modeling.There are no special key assignments, and no special data preparation or storage operations or any other prior preparation necessary before running AQMODL, simply XEQ AQMODL and follow the calculator’guidance.AQMODL can be used to model simple or complex single aquifer situations. It considers any regional change (rising or falling) in water level not necessarily associated with the development being modeled. It also models the aquifer's water-level gradient.Sixty pumping and/or recharge wells can be entered into the model, and the resultant change in water level and water-level elevation determined at an unlimited number of observation points in the aquifer.

Notes: The Kufra and Sarir basins of Libya have huge ground-water resources. Three well fields–Sarir, Kufra, and Jalo–have been constructed for irrigation purposes. The Tazerbo and West Sarir well fields are under construction. Wells in these well fields have tapped only a small portion of the total ground water available. The hydrological behavior of the Sarir well field (determined by using analytical and numerical models) indicated a leaky artesian aquifer and a significant partial penetration effect. Long and short-term pump tests did not provide true estimates of the values of transmissivity and the coefficient of storage.A steady-state model of the Kufra and Sarir basins indicated a minimum of 80 m3/s of underflow entering from Tibesti, Chad and Sudan. A transient model was constructed to pump a total of 120 m3/s from 14 well fields. The simulation indicated that sufficient drawdown was available to last at least 50 years.

Notes: Due to characteristics of centrifugal pumps, most pumping tests in large-diameter wells exhibit a decreasing abstraction rate with increasing drawdown. Type curves are obtained for the case of abstraction rates which are functions of the well drawdown; values for the type curves are obtained from a numerical model. For the case of constant abstraction, these curves provide an alternative to the classical approach. By plotting the ratio of drawdowns at different times, it is possible to identify more easily when the aquifer begins to contribute to the well discharge. The practical application of the technique is illustrated by a field example.

Notes: Nonpumping monitoring wells are commonly installed and sampled to delineate the extent of a contaminant plume and its chemical character. Samples from municipal and private pumping wells are frequently collected during ground-water contamination investigations as well. Pumping wells are also employed for remedial actions.To properly interpret sampling data from monitoring and pumping wells and to estimate their potential effectiveness in remedial actions, it is important to clearly define the geometry of that portion of the aquifer contributing water to the well (the capture zone). Velocity distribution plots by manual and computerized methods are illustrated and shown to be simple and of reasonable accuracy.

Notes: Surface Impoundment Assessment (SIA) is a methodology for determining the potential for ground- water contamination from pits, ponds and lagoons. SIA produces a numerical rating of a site, based on the sum of scores assigned to four categories: vadose zone properties, ground-water availability, ground-water quality, and waste characteristics. The SIA for New Mexico was conducted as part of a nationwide survey of potentially hazardous waste-disposal sites. Comparisons of the contamination potential scores and observed ground-water contamination from mining, milling, and industrial impoundments in New Mexico using histograms, Mann-Whitney U-Test, and linear logistic regression indicate that vadose zone properties and the nature of the waste contribute most to the general success of the SIA method to predict contamination. The remaining two categories which rate ground-water availability and natural ground-water quality do not appear to be reasonable measures of ground-water contamination potential. Rather, these categories are more indicative of the value of the ground-water resources.

Notes: Recent drilling for natural gas in the Glaciated Appalachian Plateau area of northwestern Pennsylvania has caused limited, but increasing ground-water contamination. By evaluating hydrogeologic parameters at a proposed gas well site, such as the ground-water flow system, permeability of surficial sediments, and the presence of fracture zones, the contamination hazard of the site can be assessed. Three case studies document that the most hazardous sites are generally located on or near valley walls of major drainageways. The relatively steep hydraulic gradient, the frequent presence of highly permeable surficial sediments, and the low to moderate dilution of contaminants along the intermediate-length flow paths at these sites all contribute to a relatively high pollution hazard. In addition to locating gas wells in high-hazard hydrogeologic zones, allowing the annulus of gas wells to become pressurized is the other major factor contributing to aquifer contamination.

Notes: Many hydrologists have observed that dispersion coefficients, when measured in the field, turn out to be scale-dependent. That is, the greater the travel distance in a tracer test used to measure dispersivity, the larger the dispersivity value that is calculated. Recently, Güven et al.(1983) presented a study which contains a basis for understanding the phenomenon of scale-dependent dispersion within a deterministic framework. The results of that study are used as a basis for defining a scale-dependent macro- dispersion coefficient for unidirectional flow in a stratified aquifer. Theoretical expressions are then obtained for the macrodispersivity, its various components, and its small time and large time limits. Using the data of Pickens and Grisak (1981a, b), numerical values are calculated for the macrodispersivity, and estimates are made of the travel distance required in order to reach Fickian conditions. Asymptotic large time macrodispersivity values of 49.5 m to 990 m and travel distances of 5.4 km to 109 km result for the particular aquifer studied. Based on these results it appears that Fickian conditions will seldom apply in practice to porous media flow. This study and previous studies show that the primary physical mechanism that causes spreading of a solute near the source is different advection rates at different elevations in the aquifer. Present results and comparisons with field data indicate that this phenomenon is not represented well by a scale- dependent dispersion coefficient. In modeling dispersion phenomena, it appears that more emphasis should be placed on field study and the accurate determination of hydraulic conductivity variations and other nonhomogeneities, and less on incorporating somewhat arbitrary dispersion coefficients into complex mathematical models.

Notes: Warm Springs Valley, located in northwestern Virginia, is characterized by the discharge of springs from cavernous limestone at temperatures up to 40°C, although the measured geothermal gradient is a normal 10°C/km. The area is therefore hypothesized to be an important example of a situation where thermal convection is sufficient to produce high-temperature surface waters. A finite-difference numerical model was constructed to simulate the simultaneous transport of heat and fluid under combined forced and free convection conditions. This model was used to test the hypothesized heat flow system for Warm Springs Valley.The results of the testing show that, within the hydrogeological constraints found at Warm Springs Valley, convection with a normal geothermal gradient is capable of producing 40°C hot springs. The conditions required a zone of enhanced vertical hydraulic conductivity in the area of ground-water discharge and a deep zone of enhanced horizontal hydraulic conductivity. The enhanced zones are consistent with the geology found in the basin.

Notes: A two-dimensional finite-difference computer code was used to model the ground-water flow system in an alluvial basin in southwest New Mexico. A three-step approach was used to determine the transmissivity distribution for the model. First, values of the natural logarithm of transmissivity (In T) were interpolated from existing data using the kriging technique. This interpolation scheme also produced a map of standard deviations of the kriging errors. Second, a conventional flow net was drawn from steadystate water levels with the aid of the kriged hydraulic head distribution. Third, the approximate transmissivity map, the standard deviation map of the kriged In T values, and flow net were used to select the segment of each streamtube where transmissivity was known with greatest certainty (smallest In T kriging error). Then, transmissivities in other segments of the stream tubes were calculated from Darcy's Law. This distribution, when input to the numerical model, did not have to be altered appreciably during the calibration for a steady-state and seven-year transient period. Most of the transient calibration was accomplished by adjusting storage coefficients. Considering the uncertainty in the available pumping data, very good agreement was found between observed and predicted water levels during a four-year model verification period.

Notes: Laboratory investigations have been carried out on one- and two-component artificial sand samples in order to estimate the relations between formation factor (F), porosity (φ), and permeability (K). The measurements were carried out by varying grain size and size distribution while keeping constant shape and packing; in our experimental conditions the measured formation factor approximated the intrinsic formation factor.The relationship between formation factor and porosity (F = a ·φ−m) is independent of grain size and size distribution; the coefficient values are: a = 1·15, m = 1·42.The relationship between permeability and formation factor has the general form K = r · F−s, where s is constant, and r is a function of the mean size d of the small component of the samples.The K-F relation can be established only if d is constant; in these conditions the relationship is an inverse one, and the negative trend is related to the variations in size distribution.

Notes: Abstract. Poliovirus survival was studied in ground water under hyperbaric pressures ranging from 500 to 4000 psi. It was found that, as compared to control samples incubated at atmospheric pressure, poliovirus was stable under hyperbaric pressures. The virus was, however, comparatively less stable in sea water subjected to 1000 psi pressure.