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  • Articles  (2,706)
  • Blackwell Publishing Ltd  (2,706)
  • 1995-1999  (1,957)
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  • Energy, Environment Protection, Nuclear Power Engineering  (2,706)
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  • Articles  (2,706)
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  • 1
    Electronic Resource
    Electronic Resource
    Heat Convection in Warm Springs Valley, Virginia (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb01943.x
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  • 2
    Electronic Resource
    Electronic Resource
    KARST OF CHINA (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb02754.x
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  • 3
    Electronic Resource
    Electronic Resource
    DISCUSSION OF “Kd's – Can They Be Used to Describe Reversible Ion Sorption Reactions in Contaminant Migration?” by E. J. Reardon, May-June 1981 issue, v. 19, no. 3, pp. 279–286 (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb02755.x
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  • 4
    Electronic Resource
    Electronic Resource
    REPLY TO the preceding Discussion by R. J. Serne of “Kd's—Can They Be Used to Describe Reversible Ion Sorption Reactions in Contaminant Migration?” (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb02756.x
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  • 5
    Electronic Resource
    Electronic Resource
    NATIONAL GROUND-WATER LIBRARY GOES PUBLIC (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb01323.x
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  • 6
    Electronic Resource
    Electronic Resource
    RISING GROUND WATER – PROBLEM OR RESOURCE? (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Abstract. Ground water rising to within 6 m (20 feet) of average ground surface elevations in Louisville, Kentucky caused concern to municipal officials and building owners in the central urban area. An average rise of more than 11 m (35 feet) occurred between 1969 and 1980.An evaluation of foundation conditions and structural configurations in central Louisville indicated rising ground water could create:1. slight but significant possibilities of structural settlement problems;2. high possibilities of damage to basement floors and walls; and3. very high possibilities for disruption of utility conduits.Efforts to determine the cause of this rise in ground-water level have focused on the historical relationships between ground-water levels, pumpage rates and precipitation values.Historical data indicated that ground-water levels in a system undisturbed by man could reach ground surface elevations in central Louisville. Preliminary studies indicated a strong relation between average ground-water levels and changes in pumping rates and incident precipitation. A further detailed study showed extremely high correlation (R = 0.995) between average ground-water levels in 1966–1980 and cumulative departures in precipitation and pumping rates from 1950–1965 average precipitation and pumping rates.A study of the feasibility of lowering ground-water levels while simultaneously storing energy in the aquifer system was begun but was interrupted by devastating explosions of hexane in the sewers beneath south-central Louisville on February 13, 1981. Although a dry year in 1980 and no change in pumping rate have slowed the rise in ground-water level temporarily, long-term solutions to this problem need to be developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb02753.x
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  • 7
    Electronic Resource
    Electronic Resource
    EFFECT OF HYDROSTATIC PRESSURE ON POLIOVIRUS SURVIVAL IN GROUND WATER (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb01947.x
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  • 8
    Electronic Resource
    Electronic Resource
    Theory for Aquifer Test Analysis in Fractured Rocks Under Linear (Nonradial) Flow Conditions (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The flow of ground water in a fractured rock aquifer may be linear toward a natural production surface rather than radial toward a pumping well, if the well penetrates a fracture having a permeability many orders of magnitude greater than the permeability of the surrounding aquifer. The well and its hydraulically connected production surface are called an extended well. Flow lines in a linear system are parallel, and drawdown is a function of the perpendicular distance from the extended well and not a function of the radius of the pumped well. The location of a concealed fracture and hydraulic diffusivity of the linear system can be determined if drawdown data from two observation wells are available.Linear flow has been recognized in fractured rock aquifers from aquifer test data in three widely separated areas of New Mexico and probably is the cause of the anomalous response observed in fractured rock aquifers in Mendocino and Placer Counties, California. Test data were curvilinear on semi-log plots and straight lines on log-log plots, suggesting that traditional methods of aquifer test analysis are not applicable. Straight lines could be fitted to arithmetic plots of pumped well and observation well data when plotted as drawdown versus √t, indicating that the flow in the vicinity of the test well is linear. Linear flow may be a common phenomenon that has been overlooked in the analysis of aquifer tests in fractured rock aquifers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb01325.x
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  • 9
    Electronic Resource
    Electronic Resource
    Ground-Water Flow Systems and Stability of a Slope (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Shoreline recession on the Great Lakes has caused millions of dollars worth of property damage in the lake bordering States and Canadian provinces. A variety of projects have been funded to study the erosion problem. The general conclusion of these studies is that wave action at the base of the bluff is the most important basic cause of bluff-top retreat. The purpose of this study was to investigate the role of various physical processes in causing bluff erosion. One part of the study was to ascertain the role of ground water in bluff stability. In this study, along a certain stretch of the Lake Michigan shoreline, 9 to 10 m (27 to 30 ft) per year of bluff-top recession that is not correlated to toe erosion was recorded. Heads were measured in 25 piezometers and a complex ground-water flow system was defined at this site. A glacial sand unit that is under artesian pressure was found 5 m (15 ft) above the toe of the bluff. Another “perched” system was observed in a fractured till unit at the top of the bluff. Water-table fluctuations have been recorded over a year and fluctuations of up to 13 m (39 ft) in the lower sand unit were measured. These fluctuations were found to have a significant influence on bluff stability. Pore pressures calculated from field measurements, along with the effective strength parameters of the soil units, were then used in the slope stability analysis to determine safety factors.Ground-water flow systems are found to be highly complex at the land-lake interface due to the inhomogeneities of the glacial materials that compose the bluffs. Furthermore, these complex ground-water flow systems influence the stability of the upper part of the bluffs. Because of the complexities, extrapolation of results to other stretches of the shoreline is difficult. However, methodologies and the awareness of how water-table fluctuations and multi-layered ground-water flow systems affect slope stability can be of help in other field situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb01324.x
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  • 10
    Electronic Resource
    Electronic Resource
    Evaluation of a Chimney Drain Design in an Earthfill Dam (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Two earthfill sections of Wallace Dam on the Oconee River near Eatonton, Georgia were constructed with vertical drainage filters (chimney drains) in a clay fill zone. In order to evaluate the performance of the filter in the west dike of Wallace Dam, the finite element Galerkin method was utilized in formulating a numerical model to study the steady-state saturated-unsaturated seepage characteristics through the earth dam. The resulting model is applied to Station 58+00 of the west dike of Wallace Dam. Numerical results for the four cases analyzed in this study describe the location of the zero pressure isobar and total hydraulic head values ranging from 425 feet (130 m) to 365 feet (111 m). Model results indicate a maximum seepage velocity of 2.62 feet per day (0.80 m/day) using a saturated horizontal hydraulic conductivity of 0.283 foot per day (8.64 cm/day). A maximum seepage rate is calculated to be 0.266 cubic foot per second (7.52 × 10−3 m3/sec). Analysis of the hydrostatic uplift forces along the base of the dam indicates an average pressure head reduction of 51 feet (16 m) from the upstream to the downstream side of the dam. Comparison of local seepage velocities to the critical seepage velocity upstream of the filter and inside the filter indicate a factor of safety against piping (a factor of safety against a quick condition arising in the soil) ranging from 0.3 to 3.7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb01326.x
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  • 11
    Electronic Resource
    Electronic Resource
    Regional Trends in Transmissivity and Hydraulic Conductivity, Lower Cretaceous Sands, North-Central Texas (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Depositional and structural history control regional trends in transmissivity and hydraulic conductivity in Lower Cretaceous-age sandstones along the Balcones-Ouachita trend in north-central Texas. Because of a scarcity of pumping tests, delineation of trends was possible only by incorporating transmissivities estimated from specific capacities. Statistical comparison of estimated and pumping-test transmissivities confirmed the validity of this approach. The resulting contour maps should be useful in evaluating these aquifers as potential low-temperature geothermal resources. The method can also be applied to other aquifers to facilitate ground-water management programs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00764.x
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  • 12
    Electronic Resource
    Electronic Resource
    Rapid Solution of the Nonlinear Step-Drawdown Equation (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The step-drawdown test is frequently utilized by hydrogeologists as an aid in assessing well efficiency and approximate pumping capacity. Unfortunately, the analysis of step-drawdown data presently requires either a solution to a system of highly nonlinear equations or the application of tenuous assumptions relative to the solution form. A method for solution is derived which does not require limiting assumptions, type-curve methods or extensive computer facilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00765.x
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  • 13
    Electronic Resource
    Electronic Resource
    Gravity Exploration of a Buried Valley in the Appalachian Plateau (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00766.x
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  • 14
    Electronic Resource
    Electronic Resource
    Updated Radioisotope Studies in Zimbabwean Ground Waters (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The Sabi Valley alluvial plain is the largest tract of alluvium in Zimbabwe. The ground-water hydrology of the alluvial plain was studied by three independent methods: the classical approach of potentiometric surface construction and pump test analyses, the use of in-borehole velocity and direction measurements with artificial radioactive isotopes applied to the point-dilution techniques, and a natural and thermonuclear tritium survey.The three methods of approach produce remarkably close values for the ground-water throughflow within the plain. A safe yield figure of 2.5 cubic metres/sec is currently used with confidence for the ground-water reservoir as a result of this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00767.x
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  • 15
    Electronic Resource
    Electronic Resource
    Effects of Aquifer Interconnection Resulting from Underground Coal Gasification (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00768.x
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  • 16
    Electronic Resource
    Electronic Resource
    REPLY TO the preceding Discussion by Mark A. Nelson of “Seepage from Oilfield Brine Disposal Ponds in Utah” (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00771.x
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  • 17
    Electronic Resource
    Electronic Resource
    Ground-Water Management in Basalts (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Basalts are a major source of ground water throughout the Columbia River Plateau region of the Pacific Northwest. Development and management of ground water in these basalts are complicated by the spatial variability of the hydrologic characteristics of the deep, stratified lava flows, but new irrigation developments and municipal and industrial water needs are placing increasingly larger demands on the ground-water resource. Water management decisions are aided by individual basin studies that contribute to greater understanding of the regional ground-water system. A distributed-system multiple-storage model for the Deschutes River Basin, Oregon, reveals the magnitude of spatial differences in ground-water recharge, storage, and discharge for this watershed. Input-output analysis elucidates the functional characteristics of the basin groundwater system, and it identifies the presence and magnitude of interbasin linkages in the ground-water system. Implementation of ground-water development strategies based on storage and transmission characteristics simulated by the model demonstrates that basin or regional perspectives are necessary to fully utilize ground-water storage in basalts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb01335.x
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  • 18
    Electronic Resource
    Electronic Resource
    CAVITY WELL (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1982.tb01336.x
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  • 19
    Electronic Resource
    Electronic Resource
    PROTECTIONISM AND WATER (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00740.x
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  • 20
    Electronic Resource
    Electronic Resource
    Survival of Pathogenic and Indicator Organisms in Ground Water (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00741.x
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  • 21
    Electronic Resource
    Electronic Resource
    Major Ion Characterization of Coastal Saline Ground Waters (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00744.x
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  • 22
    Electronic Resource
    Electronic Resource
    Salt-Water Intrusion in the Costa de Hermosillo, Mexico: A Numerical Analysis of Water Management Proposals (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 19 (1981), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: As a result of anthropogenic discharges of ground water far exceeding natural recharge, the Costa de Hermosillo aquifer is being actively intruded by salt water. Because this aquifer is utilized as the sole source of irrigation water for one of Mexico's principal agricultural districts, the application of any future management scheme to control this intrusion must be closely evaluated prior to implementation. A hydrologic and water quality simulation model is applied to the Costa de Hermosillo aquifer to assess the areal and temporal variations in head, velocity, and concentration as a result of changes in the present discharge distribution. The known hydrologic conditions are reproduced as a means of calibrating the model. Only qualitative statements on the future behavior of the aquifer are possible due to the uncertainty of the magnitude of various aquifer parameters and initial conditions. The model employed in this study is found to be a useful technique for the analysis of the effects of the proposed pumping stresses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1981.tb03518.x
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  • 23
    Electronic Resource
    Electronic Resource
    Experiments to Assess the Hydraulic Efficiency of Well Screens (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00722.x
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  • 24
    Electronic Resource
    Electronic Resource
    Pore-Water Pressure in the Roof of an Underground Coal Mine in Illinois (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
    Type of Medium: Electronic Resource
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    Hydrogeology of the Littlefield Springs, Arizona (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
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    DISCUSSION OF “Readers' Forum — Warm Springs Dam (and Other Disasters) Revisited,” by E. H. Boudreau November-December 1982 issue, v. 20, no. 6, pp. 752–753 (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00737.x
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    REPLY TO the preceding Discussion by Ronald B. Robie of “Readers' Forum — Warm Springs Dam (and Other Disasters) Revisited” (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    INCREASED IRRIGATION EFFICIENCY WILL ULTIMATELY SILENCE THE WATER-SHORT BLUES OF THE WASTEFUL WEST (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1983.tb00709.x
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    An Aquifer Simulation Program for Micro-Based Processors (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 19 (1981), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A generalized aquifer simulation program is designed and developed to handle problems connected with different kinds of complex ground-water systems on microprocessors. The characteristic aspect of this program, involving the “Strongly Implicit Procedure” is that it requires only 10K bytes of memory for the generated code.Using this program, the effect of pumping on an aquifer can be studied for multiple pumping periods and predictions or observations can be scrutinized at various time steps within each pumping period. The program can also handle conversion problems between confined and water-table aquifers under leaky or nonleaky states along with the effects of evapotranspiration, constant recharge or discharge boundaries. The utility and precision of the program have been tested using a sample problem quoted by Trescott et al. (1976).
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    REPLY TO the preceding Discussion by Adrian P. Visocky, Ellis W. Sanderson, James P. Gibb, Richard J. Schicht, and Robert T. Sasman, of “Shades of Immortality (Where Do We Hang the Plaque?)” (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    A Numerical Model Study of Ground-Water Contamination from Price's Landfill, New Jersey— I. Data Base and Flow Simulation (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
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    A Numerical Model Study of Ground-Water Contamination from Price's Landfill, New Jersey — II. Sensitivity Analysis and Contaminant Plume Simulation (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    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.
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    Field Determination of Aquifer Thermal Energy Storage Parameters (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Determination of the potential of a specific confined aquifer as an effective thermal energy storage medium requires thorough knowledge of the geochemical, thermodynamic, and hydraulic properties of the aquifer and its confining layers. A series of laboratory and field studies must be performed in order to determine the fundamental parameters. Procedures and analyses of a series of tests for a confined aquifer near Mobile, Alabama were completed prior to an aquifer thermal energy storage experiment. Parameters determined were: the regional gradient; vertical and horizontal permeabilities of the storage aquifer; horizontal dispersivity of the storage aquifer; vertical permeability of the confining layers; and thermal conductivities, heat capacities, and chemical characteristics of the aquifer matrix and native ground water.
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    Sensitivity Analysis and the Ground-Water Inverse Problem (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: In this work, an indirect inverse method utilizing sensitivity analysis is employed to help understand the reasons for model insensitivity. The results of the sensitivity analysis allow the modeler to delineate insensitive areas of the model where inverse procedures will be more subject to error. Sensitivity coefficients are defined and discussed. A differential equation is developed for the sensitivity coefficients that will generally be solved by numerical techniques. A relatively simple least squares' inverse procedure is used on a hypothetical model to illustrate typical problems that can be encountered. In particular, the effect of data accuracy is considered. The low sensitivity areas of models are generally related to small values of δh/δx and δh/δt. The fact that considerable error in the transmissivity and storativity may occur in areas of low sensitivity should not be looked upon as a failing of the inverse procedure. It is simply a fact that not all areas of the model have been stressed equally. The main advantage of the present work is that areas of low sensitivity may be delineated.
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    Economics of Improving Well and Pump Efficiency (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Significant savings are frequently achieved from increasing well and pump efficiency by repair or replacement. Replacement analysis (a part of engineering economics) may be used to schedule these actions. The criterion is to maximize net benefits or minimize the cost of water. The optimal timing of repair or replacement occurs when the cost per unit of water from the old system becomes more than the minimum annualized cost per unit of water from the new system.
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    DISCUSSION OF “Fly Ash Disposal in a Limestone Quarry,” by Jeffrey R. Peffer, May-June 1982 issue, v. 20, no. 3, pp. 267–273 (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    SHADES OF IMMORTALITY (Where Do We Hang the Plaque?) (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    Classification of Ground-Water Systems of the United States (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Classification of ground-water systems provides a useful basis for the transfer of hydrologic knowledge from one site to another and for enhancing the public's understanding of ground water. The five features of ground-water systems useful in classification are (1) components of the system, (2) nature of the water-bearing openings, (3) composition of the rock matrix, (4) storage and transmission characteristics, and (5) recharge and discharge conditions. Using these features, the United States can be divided conveniently into 14 regions.
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    Evaluating and Improving Existing Ground-Water Systems (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Considerable energy savings are available from improving well and pump efficiencies. One major problem is evaluating the well and pump inefficiencies over prolonged periods of time, because these efficiencies are erratic unless normalized. A new well should be tested at different discharges to construct a relationship between specific capacity and drawdown. Future well efficiency tests should compare the specific capacity with the original curve at the test discharge. The departure from the original curve indicates the loss in well efficiency. Similarly, pump efficiency needs to be normalized, so that the tested efficiency may be compared with the original efficiency at the test discharge.
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    DISCUSSION OF “Guest Editorial—Comments on a National Ground-Water Protection Strategy,” by David H. Howells, September-October 1981 issue, v. 19, no. 5, pp. 466–468 (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    Application of Flowmeter and Depth-Dependent Water Quality Data for Improved Production Well Construction (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Ground water production wells commonly are designed to maximize well yield and, therefore, may be screened over several water-bearing zones. These water-bearing zones usually are identified, and their hydrogeologic characteristics and water quality are inferred, on the basis of indirect data such as geologic and geophysical logs. Production well designs based on these data may result in wells that are drilled deeper than necessary and are screened through zones having low permeability or poor-quality ground water. In this study, we examined the application of flowmeter logging and depth-dependent water quality samples for the improved design of production wells in a complex hydrogeologic setting. As a demonstration of these techniques, a flowmeter log and depth-dependent water quality data were collected from a long-screened production well within a multilayered coastal aquifer system in the Santa Clara-Calleguas Basin, Ventura County, California. Results showed that the well yields most of its water from four zones that constitute 58% of the screened interval. The importance of these zones to well yield was not readily discernible from indirect geologic or geophysical data. The flowmeter logs and downhole water quality data also show that small quantities of poor-quality water could degrade the overall quality of water from the well. The data obtained from one well can be applied to other proposed wells in the same hydrologic basin. The application of flowmeter and depth-dependent water quality data to well design can reduce installation costs and improve the quantity and quality of water produced from wells in complex multiple-aquifer systems.
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    Laboratory and Field Investigation of Surfactant Sorption Using Single-Well, “Push-Pull” Tests (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Sorption to aquifer sediments can limit the effectiveness of surfactants injected to solubilize residual nonaqueous phase liquid contaminants in the subsurface. The objective of this study was to evaluate the ability of the single-well, push-pull test to characterize sorption of linear alkylbenzene sulfonate (LAS) and hexadecyl diphenyl oxide disulfonate (DOWFAX) surfactants to natural aquifer sediment in situ. Batch sorption isotherms for both surfactants exhibited Langmuir-type sorption behavior with larger apparent sorption maxima for LAS than for DOWFAX. However, numerical transport simulations based on batch sorption isotherms were unable to predict the retardation and chromatographic separation of LAS homologs and conservative transport of DOWFAX observed during laboratory and field push-pull tests, indicating that the single-well, push-pull test method can more accurately describe in situ surfactant sorption and transport behavior than batch sorption isotherms.
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    A Numerical Study on the Relationship Between Transmissivity and Specific Capacity in Heterogeneous Aquifers (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Specific capacity (Q/s) data are usually much more abundant than transmissivity (T) data. Theories which assume uniform transmissivity predict a nearly linear relationship between T and Q/s. However, linear dependence is seldom observed in field studies. Since hydrogeologic studies usually require T data, many hydrogeologists use linear regression analysis of T versus Q/s data to estimate T values where only Q/s data are available. In this paper we use numerical models to investigate the effects of aquifer heterogeneity on the relationship between Q/s and T estimates. The simulations of hydraulic tests in heterogeneous media show that estimates of T derived using Jacob's method tend to their late-time effective value much faster than Q/s values. The latter are found to be more dependent upon local transmissivities near the well. This explains why the regression parameters for T versus Q/s data depend on heterogeneity and the‘lateness’of the test period analyzed. Since this effect is more marked in high T zones than in low T zones, we conclude that natural aquifer heterogeneity can explain the convex deviation from linearity often observed in the field. A further result is that the geometric mean of T estimates, obtained from short and intermediate time pumping tests, seems to systematically underestimate effective T (Teff) of heterogeneous aquifers. In the studied simulation cases, the median of the T values or the arithmetic mean yield better estimates for Teff.
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    Letter to the Editor (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    Boulton's Delayed Yield: A Different Context (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: In 1954, Boulton proposed a delayed yield idealization to account for the dynamic contribution of water from the zone of desaturation during a pumping test in an unconfined aquifer. During the 1970s, the reasonableness of this idealization was questioned by some on the grounds that the exponential function with a constant parameter, used by Boulton to quantify the drainage process, was too simplistic and that the parameter will, in actuality, vary in time and space. Rather than discussing the merit of the delayed yield idealization in regard to an unconfined aquifer, the present work explores a different physical situation of an aquifer in which Boulton's idealization is realistic. Laboratory evidence exists to suggest that the deformation behavior of some aquifer materials is time dependent (creep or strain accumulation). In turn, this time dependence of deformation leads to a time dependence of the compressibility of the aquifer material, and hence, a time dependence of the aquifer's specific storage. In situations where the specific storage of an aquifer may be characterized by such time dependence, and if such time dependence can be reasonably approximated by an exponential function, then the response of such an aquifer to a constant rate pumping test will be described accurately by Boulton's mathematical formulation.
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    Hydrochemical Approach to the Alterations of the Recharge of a Karst Aquifer Consecutive to a Long Pumping Period: Example Taken from Pinchinade Graben (Mouans-Sartoux, French Riviera) (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The carbonate aquifer of the Pinchinade graben, which has a well-delimited geometry, involves water with well-defined chemical types from calcium sulfate to magnesium bicarbonate. Each ground water type corresponds to a well-delimited area of the aquifer: the magnesium bicarbonate for the Liassic and Rhetian limestone water (with 10 to 30 mg L-1 of sulfate) and calcium sulfate for the water of the relatively impermeable layer of the underlying Keuper (with 300 to 1500 mg L−1 of sulfate). A four-year pumping test with a bimonthly to daily monitoring of water chemistry has allowed evaluation of the renewal of the exploitable water reserve. During the four-year period, the survey shows that the average discharge is balanced by natural recharge (2.8 to 105 m3 y−1). A change in the chemical character of the water was observed from Rhetian to Keuper type (from 35 to 167 mg L−1 of sulfate). Such a change indicates a progressive exhaustion of the Rhetian reserves, which are the greater part of the exploitable reserve in the area. The same phenomenon is observed daily depending on the pumped discharge and the season. For pumping rates below 26 m3 h−1, the borehole drains the Rehetian inflows to a degree depending on high or low water levels. For pumping rates above 26 m3 h−1, whatever the period, the permeable Keuper layers are pumped and sulfate peaks ensue.
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    Enhancements for Passive Vapor Extraction: The Hanford Study (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Passive vapor extraction involves wells that are screened in the unsaturated zone and open to the atmosphere. Gas will flow out of the subsurface through the open well during periods of low barometric pressure. Field and modeling studies have been completed to evaluate enhancements for a passive vapor extraction system at a site contaminated with carbon tetrachloride on the Hanford nuclear reservation near Richland, Washington. During a 38-hour period of low barometric pressure, approximately 500 m3 of air were vented from the subsurface. Approximately 27 grams of carbon tetrachloride were removed from the subsurface during this same outflow event. On an annual basis, more than 15 kilograms of carbon tetrachloride have been removed from each of several passive extraction wells. Computer simulations based on the field data indicate that surface covers smaller than 30 m radius will result in relatively small enhancements of flow. However, with larger surface seals (i.e., up to 90 m radius), volumetric flow rates more than doubled. Simulations showed that check valves might increase the rate at which subsurface gases are extracted by a factor of nearly three. These estimates are sensitive to dispersion coefficients. If not properly designed, filters used to treat effluent gases from passive extraction systems can significantly reduce the effectiveness of these systems.
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    Designing a Monitoring Network for Contaminated Ground Water in Fractured Chalk (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: One of the challenges of monitoring network design in a fractured rock setting is the heterogeneity of the rocks. This paper summarizes the activities and problems associated with the monitoring of contaminated groundwater in porous, low-permeability fractured chalk in the Negev Desert, Israel. Preferential flow documented in the study area required siting the monitoring boreholes in the predominant fracture systems. Lineaments traced from aerial photographs were examined in the field to sort out the large-extension, through-going, multilayer fracture systems crossing the study area. At each proposed drilling site, these fractures were exposed below the sediment cover using trenches. Slanted boreholes were drilled at a distance from the fracture systems so that each borehole would intersect the targeted fracture plane below the water table. Based on their short recovery period and contaminated ground water, these newly drilled, fracture-oriented boreholes appeared to be better connected to preferential flowpaths crossing the industrial site than the old boreholes existing on site. Other considerations concerning the drilling and logging of monitoring boreholes in a fractured media were: (1) coring provides better documentation of the vertical fracture distribution, but dry augering is less costly and enables immediate ground water sampling and the sampling of vadose rock for contaminant analysis; (2) caliper and TV camera logs appear to provide only partial information regarding the vertical fracture distribution; and (3) the information gained by deepening the monitoring boreholes and testing fractures crossing their uncased walls has to be carefully weighed against the risk of potential cross-contamination through the monitoring boreholes, which is enhanced in fractured media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1999.tb00956.x
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    Unsteady Stream Depletion from Ground Water Pumping (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A solution is obtained for stream flow depletion created by pumping from a well beside a stream. This solution assumes that streambed penetration of the aquifer and dimensions of the streambed cross section are all relatively small. It also assumes that the streambed is clogged and that a linear relationship exists between the outflow seepage through the streambed and the change in piezometric head across the semipervious clogging layer. The solution is general enough to include the earlier solutions of Theis, Glover and Balmer, and Hantush. A solution is also obtained for the drawdown at any point within the aquifer, and it is suggested that this solution might be matched with experimental field data to obtain estimates for aquifer and streambed leakage parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1999.tb00962.x
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    Ethics and Hydrogeology (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02090.x
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    Software Spotlight (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02093.x
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    Dipole Probe: Design and Field Applications of a Single-Borehole Device for Measurements of Vertical Variations of Hydraulic Conductivity (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A dipole probe (DP) for measuring vertical variations of hydraulic conductivity has been designed, constructed, and tested in field conditions. The variable-length device designed for the dipole flow test (DFT) consists of three packers separated by changeable spacer rods. The assembled DP is lowered into a well with a long screened interval. The packers are inflated, isolating two screened sections (chambers) between them. A small submersible pump, mounted on the central packer, transfers water from the upper (extraction) chamber into the lower (injection) chamber. This simultaneous injection and extraction creates a recirculatory flow within the aquifer. The chamber head responses are measured by two pressure transducers in the DP chambers. The DP can be used at discrete intervals along the entire well screen length. The DP has been successfully tested in a specially constructed well with a continuous screen in a highly conductive sand and gravel aquifer. During drilling, disturbed samples were collected using the split spoon method and the vertical profile of K was estimated from grain-size analysis. A total of 153 DFTs were performed with various DP geometries. Results indicate that the chamber head changes are sensitive to aquifer properties, reach steady state rapidly, vary linearly with redrculation pumping rate, and can be controlled by changes in DP dimensions. Vertical profiles of K compare well with grain-size analysis estimates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02095.x
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    Methodology for the Study of Unexploited Aquifers with Thermal Waters: Application to the Aquifer of the Alhama de Aragon Hot Springs (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A methodology for the study of thermal waters in unexploited aquifers is proposed. This methodology has been applied to the Alhama Aquifer, which is the origin of the most important thermal springs of the Iberian Peninsula. A conceptual model was made of the aquifer by integrating data such as (1) the geometry at depth (on the basis of deep geophysics) and at the surface (from conventional geological maps); (2) hydrographic analysis of the aquifer discharge; (3) a study of the recharge by classic hydrometeo-rological methods; and (4) conventional and isotopic hydrochemistry. In addition to the hydraulic regional parameters it provides, the model explains the origin of the Alhama springs in terms of simple circulation at a depth of some 900 m and a normal geothermal gradient (3°C/100 m), with no requirement of contact with a source of heat at the bottom of the aquifer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02098.x
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    Type Curves to Determine the Relative Importance of Advection and Dispersion for Solute and Vapor Transport (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The relative importance of advection and dispersion for both solute and vapor transport can be determined from type curves for concentration, flux, or cumulative flux. The dimensionless form of the type curves provides a means to directly evaluate the importance of mass transport by advection relative to that of mass transport by diffusion and dispersion. Type curves based on an analytical solution to the advection-dispersion equation are plotted in terms of dimensionless time and Peclet number. Flux and cumulative flux type curves provide additional rationale for transport regime determination in addition to the traditional concentration type curves. The extension of type curves to include vapor transport with phase partitioning in the unsaturated zone is a new development. Type curves for negative Peclet numbers also are presented. A negative Peclet number characterizes a problem in which the direction of flow is toward the contamination source, and thereby diffusion and advection can act in opposite directions. Examples are the diffusion of solutes away from the downgradient edge of a pump-and-treat capture zone, the upward diffusion of vapors through the unsaturated zone with recharge, and the diffusion of solutes through a low hydraulic conductivity cutoff wall with an inward advective gradient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02102.x
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    Virus Occurrence and Transport in a School Septic System and Unconfined Aquifer (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Federal efforts to establish reliable natural disinfection criteria for ground water supplies require the identification of appropriate indicator viruses to represent pathogenic viruses and an understanding of parameters affecting virus survival and transport in a variety of hydrogeologic settings. A high school septic system and the associated fecal waste-impacted unconfined sand and gravel aquifer were instrumented to: (1) evaluate if the concentrations of enterovirus and coliphage in this system were sufficient to allow their use as indicator viruses; (2) establish viral transport rates, transport distances, and concentrations in a highly conductive cold water aquifer. Enteroviruses were found in only two of eight assays of the septic tank effluent (0.26 and 4.4 virus/L) and were below detection in eight ground water samples. Male-specific and somatic coliphage were detectable in both the septic tank effluent (averaging 674,000 and 466,000 coliphage/L, respectively) and in the impacted underlying ground water, decreasing to detection limits beyond 38 m of the drainfield. Virus transport parameters in this aquifer were measured by seeding high numbers of MS2 and ØX174 coliphage into the ground water and documenting their transport over 17.4 m. A portion of the seeded virus traveled at least as fast as the bromide tracer (1 to 2.9 m/d). Proposed natural disinfection criteria would not be met in this aquifer using standard 30.5 m setback distances. In addition, the virus sorption processes and long survival times resulted in presence of viable seed virus for more than nine months.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02201.x
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    Discussion of Papers (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02826.x
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    Virtual Water: A Strategic Resource Global Solutions to Regional Deficits (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02825.x
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    The Determination of Glacial Till Specific Storage in North Dakota (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Specific storage (Ss) was calculated for 107 glacial till core samples collected in 1962 from 93 drilling sites at U.S. Air Force Intercontinental Ballistic Missile launch and launch control facilities located in North Dakota. Core sample depths ranged from 8 to 26 m. Consolidation tests were performed on the till samples using a floating ring consolidometer. The coefficient of volume change (mv), which is defined as the volume change per unit volume per unit increase in effective stress, was calculated for this study using previously reported consolidation test data. Ss calculated for the 107 till samples ranged from 2.0 × 10-4m-1 to 1.1 × 10-3m-1, with a mean value of 5.6 × 0-4m-1.Till is easily compressible and, as a result, Ss is not constant, but rather a function of loading. With increased depth, effective stress (σ0) increases and Ss decreases. Based on data from 107 till cores in this study, the relationship between σ0 and Ss is described by: Ss= 0.049σ0−0.84, (r2= 0.60, p〈0.0001), where σ0= in situ effective stress in kPa, and Ss= specific storage in m-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02828.x
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    Air Permeability of Porous Materials Under Controlled Laboratory Conditions (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A series of air permeability tests were conducted on four hand-packed samples of alluvial sands and glass beads using a newly developed air permeameter. The permeameter was tested and found capable of precisely controlling soil-water matric potential (in the range 0 to 1 bar) while simultaneously facilitating the direct measurement of air permeability in porous media. Permeameter results indicate that air permeability increases with a corresponding decrease in water content over a monotonic drainage cycle. It was observed that the rate of change in air permeability with respect to changes in water content is highest at high water content and lowest at low water content. In several soil samples, the air permeability approached a constant value at low water content. Air permeability variations with water content were observed to differ among soils of different texture. For example, the intrinsic permeability of water was 11 to 86% of the maximum air permeability. The new permeameter allowed rapid and accurate measurements of air permeability in fine-textured materials over a wide range of matric potentials and water content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02829.x
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    DNAPL Migration Through a Fractured Perching Layer (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The migration of a DNAPL (TCA) was demonstrated by a laboratory flow visualization experiment. The system consists of two unconfined aquifers separated by a siltstone perching layer containing a single fracture that conducts water flow downward. The TCA migrated along a tortuous path in the upper sandy aquifer and moved rapidly through the fracture. We observed no DNAPL pooling above the fracture prior to its entry into the fracture, in contrast to existing mathematical solutions of hydrostatic initial conditions and full saturation below the fracture. A multiphase flow model predicted the experimentally observed mean behavior.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02834.x
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    Reductive Dissolution and Reactive Solute Transport in a Sewage-Contaminated Glacial Outwash Aquifer (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Contamination of shallow ground water by sewage effluent typically contains reduced chemical species that consume dissolved oxygen, developing either a low oxygen geochemical environment or an anaerobic geochemical environment. Based on the load of reduced chemical species discharged to shallow ground water and the amounts of reactants in the aquifer matrix, it should be possible to determine chemical processes in the aquifer and compare observed results to predicted ones.At the Otis Air Base research site (Cape Cod, Massachusetts) where sewage effluent has infiltrated the shallow aquifer since 1936, bacterially mediated processes such as nitrification, denitritication, manganese reduction, and iron reduction have been observed in the contaminant plume. In specific areas of the plume, dissolved manganese and iron have increased significantly where local geochemical conditions are favorable for reduction and transport of these constituents from the aquifer matrix. Dissolved manganese and iron concentrations ranged from 0.02 to 7.3 mg/L, and 0.001 to 13.0 mg/L, respectively, for 21 samples collected from 1988 to 1989.Reduction of manganese and iron is linked to microbial oxidation of sewage carbon, producing bicarbonate and the dissolved metal ions as by-products. Calculated production and flux of CO2 through the unsaturated zone from manganese reduction in the aquifer was 0.035 g/m2/d (12% of measured CO2 flux during winter). Manganese is limited in the aquifer, however. A one-dimensional, reaction-coupled transport model developed for the mildly reducing conditions in the sewage plume nearest the source beds showed that reduction, transport, and removal of manganese from the aquifer sediments should result in iron reduction where manganese has been depleted.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02832.x
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    A Decision Support Model to Assess Vulnerability to Salt Water Intrusion in the Great Bend Prairie Aquifer of Kansas (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A relatively simple ground water decision support system (DSS) was developed to assist in identifying salt-water vulnerable areas and in developing management policies to prevent salt-water intrusion in central Kansas. The DSS is based on a combination of numerical modeling sensitivity analyses, multiple regression analyses, and classification procedures derived from our knowledge of the area. Six ground water salinity models are proposed to evaluate irrigation well permit applications. The choice of model depends on the availability of site-specific data. The DSS takes advantage of GIS database management procedures, and is applied to an actual salt-water intrusion problem site in south-central Kansas. This approach can help local ground water management districts make better decisions on protecting ground water use in salt water vulnerable areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02819.x
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    Preferential Flow and Transport of Nitrate and Bromide in Clay pan Soil (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The in situ measurement of water flow and chemical transport through clay pan soils is crucial to understanding potential water contamination from agricultural sources. It is important due to the large areal extent of these soils in agricultural regions of the midwestern United States and because of preferential flow paths caused by desiccation cracks, worms burrowing, and root development. A study plot at the Missouri Management Systems Evaluation Area near Centralia, Missouri, was instrumented to determine the rate of preferential flow of water and transport of NO3−1 fertilizer in the unsaturated zone through a claypan soil using 15N-NO3−1 and Br-1 tracers. The areal distribution of preferential flow paths was between 2 and 20% in the topsoil. Gravity lysimeter flow caused by preferential flow through the claypan was as much as 150 times greater than the estimated average rate of vertical recharge. As much as 2.4% of the volume of the soil below the clay pan may be occupied by preferential flow paths.The 15N-NO3−1 concentrations in ground water indicate that substantial quantities of fertilizer-derived NO3−1 were transported to ground water through the claypan during the first recharge event following fertilizer application even though that event occurred six months after application. Hydraulic conductivity, measured at three scales, ranged from 6.2 × 10−8 to 7.5 × 10−3 cm/s. The observed increase of calculated hydraulic conductivity with each increase in scale was attributed to the inclusion of more and larger preferential flow paths within the volume over which the measurement was made, indicating hydraulic conductivity measured at one scale may not describe flow and transport at another scale.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02820.x
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    Suitability of Parametric Models to Describe the Hydraulic Properties of an Unsaturated Coarse Sand and Gravel (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The performance of parametric models used to describe soil water retention (SWR) properties and predict unsaturated hydraulic conductivity (K) as a function of volumetric water content (θ) is examined using SWR and K(θ) data for coarse sand and gravel sediments. Six 70 cm long, 10 cm diameter cores of glacial outwash were instrumented at eight depths with porous cup ten-siometers and time domain reflectometry probes to measure soil water pressure head (h) and θ, respectively, for seven unsaturated and one saturated steady-state flow conditions. Forty-two θ(h) and K(θ) relationships were measured from the infiltration tests on the cores. Of the four SWR models compared in the analysis, the van Genuchten (1980) equation with parameters m and n restricted according to the Mualem (m = 1 - 1/n) criterion is best suited to describe the θ(h) relationships. The accuracy of two models that predict K(θ) using parameter values derived from the SWR models was also evaluated. The model developed by van Genuchten (1980) based on the theoretical expression of Mualem (1976) predicted K(θ) more accurately than the van Genuchten (1980) model based on the theory of Burdine (1953). A sensitivity analysis shows that more accurate predictions of K(θ) are achieved using SWR model parameters derived with residual water content (θr) specified according to independent measurements of θ at values of h where θ/h ∼ 0 rather than model-fit θr values. The accuracy of the model K(θ) function improves markedly when at least one value of unsaturated K is used to scale the K(θ) function predicted using the saturated K. The results of this investigation indicate that the hydraulic properties of coarse-grained sediments can be accurately described using the parametric models. In addition, data collection efforts should focus on measuring at least one value of unsaturated hydraulic conductivity and as complete a set of SWR data as possible, particularly in the dry range.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02818.x
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    Field Evaluation of Interfacial and Partitioning Tracers for Characterization of Effective NAPL-Water Contact Areas (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The use of surface-active tracers for measuring the interfacial area between no aqueous phase liquids (NAPLs) and water was evaluated in a hydraulically isolated test cell installed in a surficial aquifer located at Hill Air Force Base (AFB), Utah. Interfacial tracers were developed at the University of Florida for quantifying immiscible fluid-fluid interfaces (air-water or NAPL-water) in porous media. Sodium dodecyl benzene sulfonate (SDBS) was used as the interfacial tracer to measure the effective NAPL-water interfacial area (aNw), while 2,2-dimethyl-3-pentanol (DMP) was used as the partitioning tracer to estimate the NAPL saturation (SN). The observed retardation of SDBS and DMP when compared to a nonreactive tracer (bromide or methanol) at eight multilevel sampling locations and one extraction well, was used to quantify the aNw and SN values averaged over the interval between the injection wells and each monitoring point. The NAPL morphology index, defined here as HN= aNw/φSN (φ= porosity), varied significantly within the test cell. In locations where the magnitude of HN was large, the NAPL was assumed to be more or less uniformly spread, providing good contact with the mobile fluid. In contrast, regions with low HN values were assumed to have NAPL that was more heterogeneously distributed as isolated patches providing poor contact with the mobile fluid. The index HN, provided by the combined use of interfacial and partitioning tracers, has important implications for NAPL source region remediation employing in situ flushing technologies.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02821.x
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    Putting Hydrogeologic Site Studies on Track (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb01079.x
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    Semi analytical Evaluation of Three-Dimensional Velocity Near a Partially Penetrating Well in an Unconfined Aquifer (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This paper presents an effective semi analytical method for computation of ground water velocities near a partially penetrating well in an unconfined aquifer. The Neuman solution (1974) is presented as the sum of the Hantush solution (1964) and a correction term for water table conditions. Hydraulic gradients are directly evaluated from the Hantush solution, whereas the gradients for the Neuman correction are calculated using a numerical inversion of the Laplace transform. The method presented here is verified by comparing it with the results of a finite-difference approximation of hydraulic gradients. Calculations of velocities near a pumping well in an unconfined aquifer indicate that, after an initial increase, the vertical velocity decreases before reaching steady state. The method provides a useful tool for the study of well hydraulics and contaminant transport to a pumping well in an unconfined aquifer.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02823.x
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    Effects of Sea Water Canals on Fresh Water Resources: An Example from Big Pine Key, Florida (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Management of the limited fresh water resources on small oceanic islands has become critical with increasing population and development in coastal areas. Canals, dredged for waterfront property and boat access, penetrate water-bearing material and accelerate the natural discharge from fresh water lenses. Big Pine Key, located in the southern portion of the Florida Keys, is a heterogeneous, two-layer island with several canal networks. The island is approximately 3 km wide and 10 km long. The upper hydros-tratigraphic unit (Miami Oolite Limestone) has a hydraulic conductivity of 100 meters per day (m/day). The lower unit (Key Largo Limestone) has a hydraulic conductivity of 1200 m/day.To quantify the effects of canals on the fresh water lens of Big Pine Key, a numerical model was developed using the Dupuit and Ghyben-Herzberg assumptions. The thickness of the fresh water lens is sensitive to the location of the boundary between the upper and lower hydros-tratigraphic layers. A simulation of present-day Big Pine Key, including canals, compared with predevel-opment conditions shows that the total volume of the lens has decreased by 20% in response to the dredging of canals. As dredging of canals will certainly continue in the future, the numerical model was also used to investigate the types of canals that are most detrimental to a fresh water lens. For an island 3 km wide and 10 km long, a canal that penetrates 2 km lengthwise into the island reduces the volume of the fresh water lens by 6.5%. For the same island dimensions, a canal that penetrates 2 km through the mid-section of the island reduces the volume of the fresh water lens by 7.1 %. Several short canals, with a combined total length of 2 km decrease the volume of the fresh water lens by 4.0 %. The deeper the penetration of the canal into the lens, the greater the influence of the canal. Therefore, several short canals are preferred over one long canal because shorter canals have less of an effect on the total volume of the fresh water lens. Canals also focus ground water discharge. The three configurations of 2000 m long canals each discharge 13 to 15% of the total recharge to the island.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02822.x
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    “Using the Deconvolution Approach for Slug Test Analysis: Theory and Application” by C. Chakrabarty and C. Enachescu, September-October 1997 issue, v. 35, no. 5: 797–806. (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb01083.x
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    Ground Water Contaminant Source and Transport Parameter Identification by Correlation Coefficient Optimization (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Inverse procedures based on correlation coefficient optimization are developed to locate ground water contaminant sources and to identify transport parameters. For cases involving two-dimensional instantaneous and continuous sources, the inverse formulas are explicit. These procedures allow not only for the delineation of the sampled contaminant plume, but also the tracing and the projection of the plume history.
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    Drawdowns in Coupled Aquifers with Confining Unit Storage and ET Reduction (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This paper presents a nonsteady coupled aquifer solution in which transient and steady-state drawdowns due to pumping can be calculated in one or both of two aquifers separated by a semipermeable confining unit in a confined aquifer system. The water pumped is obtained from storage in the aquifers and the confining unit, and a reduction in evapotranspiration (ET) due to a decline in the water table. This solution is different from existing analytical solutions in that it includes both confining unit storage and a drawdown-dependent ET reduction term. A Laplace space solution obtained for the differential equations subject to the initial and boundary conditions is inverted to the time domain using the Stehfest numerical algorithm. The presence of the ET reduction term in the solution allows the drawdowns to reach a steady-state condition, and the presence of the confining unit storage term delays the response of the aquifer system to pumping, particularly in the unpumped aquifer. Use of the solution to calculate drawdowns for a representative field case is illustrated, along with verification of the solution using a numerical ground water flow model.
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    A Numerical Model for Simulation of Bioremediation of Hydrocarbons in Aquifers (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A numerical model was developed to describe the bioremediation of hydrocarbons in ground water aquifers considering aerobic degradation. The model solves the independent transport of three solutes (oxygen, hydrocarbons, and microorganisms) in ground water flow using the method of characteristics. Interactions between the three solutes, in which oxygen and hydrocarbons are consumed by microorganisms, are represented by Monod kinetics, solved using a Runge-Kutta method. Model simulations showed good correlation as compared with results of soil column experiments. The model was used to estimate the time needed to remediate the columns, which varied from one to two years.
    Type of Medium: Electronic Resource
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    Conducting and Interpreting Slug Tests in Monitoring Wells with Partially Submerged Screens (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Conducting and interpreting slug tests in wells with screen sections and sand packs that span the water table are severely complicated by sand pack drainage and resaturation. Sand pack drainage greatly reduces the actual head difference between the well and the formation. Resaturation of the drained sand pack must be properly accounted for, or the formation hydraulic conductivity will be underestimated. The magnitude of error is a function of the well geometry, sand pack properties, and the model chosen to interpret the data. A method has been developed to correct for sand pack resaturation by calculating the specific yield of a drained sand pack using the early recharge data of a slug test. Slug tests were conducted in one well in which the water table varied over time, creating both partially and fully submerged screen and sand pack conditions for comparative testing. The mid-time, log-linear portion of slug test data was corrected using the calculated specific yield of the drained sand pack to yield essentially the same hydraulic conductivity value as the fully submerged screen results. Not accounting for sand pack resaturation would have yielded a hydrauli c conductivity value that was lower than the submerged screen results by a factor of seven.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb01087.x
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    Model Identification Criteria for Inverse Estimation of Hydraulic Parameters (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This study deals with the problem of model structure identification when the zonation method is adopted for parameterization. Our method applies four identification criteria, recommended by Carrera and Neuman (1986a), to a synthetic model and to a set of field data from the Taegu area, Korea. Study of the synthetic model demonstrates that the quality of head data, the depth of data acquisition, and the anisotropy ratio of parameters are important factors for the parameter structure when it is identified using the four criteria. It also shows that a specific criterion is not preferable for every case, but that all four criteria should be considered in order to choose the best among a set of alternative aquifer zonation models. The field example shows that the anisotropy of aquifer parameters should be considered for the parameterization of crystalline rock aquifers, which are the most common systems in Korea.
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    Utilization of Intrinsic Boron Isotopes as Co-Migrating Tracers for Identifying Potential Nitrate Contamination Sources (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The stable isotopes of the conservative element boron, 11 B and 10 B, have been employed as co-migrating isotopic tracers to trace potential sources of nitrate observed in ground water pumped from a large capacity 0.167 m 3/s irrigation well in the Avra Valley of southeastern Arizona. The isotopic ratios provided an identifying signature for two nitrogen carrying source waters: municipal waste water and agricultural return flow. Additional chemical parameters were also examined to corroborate the isotopic indications.Boron isotopes provided a superior delineation of mixing processes in the system compared to the general inorganic chemical parameters. Findings of this investigation indicate that the water pumped by the study well at the beginning of the 1993 irrigation season was composed of a mixture of approximately 25 % municipal waste water and 75 % background ground water. As the irrigation season progressed, an increasing proportion of water was contributed by irrigation return flow from neighboring agricultural fields.
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb01089.x
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    Obtaining Representative Ground Water Samples in a Fractured and Karstic Formation (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Ground water was sampled from a number of wells along recharge pathways between fractured shale and karstic carbonate formations to determine the effect of sampling methods on the colloid abundance and the chemical and hydrologic mechanisms controlling the abundance of ground water colloids. Low-flow minimal drawdown purging and sampling produced samples with much lower and more consistent turbidity than had been obtained during compliance monitoring of the same wells using much higher flow rates and purging of three well volumes. Although some low-yielding wells required very low pumping rates (10 ml/min) to prevent drawdown, water quality parameters (temperature, pH, electrode potential, dissolved oxygen, specific conductance, and turbidity) stabilized fairly quickly. The total volume of water removed during purging was small (usually only a few liters), and did not appear to be related to either the casing volume or the screen volume of the well. This lack of correlation may indicate that a limited volume of the formation is sampled at the low flow rates. Since only a portion of long screened intervals appear to be sampled, care must be given to placement of the sample tubing to access zones where contaminant migration is expected.
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    Predicting the Probability Distribution of Yield from Multiple Boreholes in Crystalline Bedrock (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: In many hard rock lithologies, the distribution of borehole yields can often be regarded as being derived from a log-normally distributed population, characterized by the median yield (m1), and standard deviation of In-transformed values (σ1. By means of numerical techniques using standard spreadsheet software, the distribution of total yield from two or more boreholes can be calculated, assuming that the yields of the boreholes are statistically independent variables and that there is no significant hydraulic interference between boreholes. The results are not necessarily obvious: (1) the median total yield for a group of y noninterfering boreholes (my) is greater than y.mt. The ratio my/y.m1 increases with increasing y and with increasing σ1; and (2) the standard deviation σy of In-transformed yield distributions for water systems consisting of y multiple boreholes is less than the standard deviation σ1 of the In-transformed yield distribution for single boreholes. The standard deviation decreases as the number of boreholes in the group increases.
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    Use of Solute and Isotopic Composition of Ground Water to Constrain the Ground Water Flow System of the Azraq Area, Jordan (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This study shows that hydrological systems in arid areas where water level data are incomplete can be better understood and constrained by using chemical and isotopic data. These constraints significantly alter the conceptual hydrological model of the Azraq area.Previous studies, based on water level data, suggest that water in the Azraq oasis is derived from two major piezometric highs; the western basalt aquifer to the northwest and the Tulul el Ashaquif highlands to the northeast of the oasis. Water from the Tulul el Ashaquif aquifer is also considered to drain to a piezometric low at Ruwaishid to the east, and then into deeper aquifers.Chemical data from this study show that the northwest basalt aquifer provides most of the water (80-85 %) to the Azraq oasis. Water from the Tulul el Ashaquif supplies a relatively small proportion, but due to its high solute content, imparts its chemical signature on the oasis water. This study has shown that water from Tulul el Ashaquif are not supplied to the Ruwaishid area, as previously thought.Stable isotopic data show that each piezometric high contains water which originated in a distinct climatic setting. Both water types are poor in tritium. Traces of tritium at the Azraq oasis and at Ruwaishid indicate some recent local recharge.
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    Radon in Quaternary Aquifers Related to Underlying Bedrock Geology (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A survey of radon concentrations in water abstracted from 31 of Norway's largest waterworks, using ground water from Quaternary fluvial and glaciofluvial sediments, returned values of between 0.4 Bq/L and 83 Bq/L, with a median of 23 Bq/L. Significantly higher Rn concentrations were present in ground water from Quaternary aquifers underlain by gneissic and granitic lithologies compared with those underlain by metasandstones, phyllites and mica schists. Compared to the recommended national action level of 500 Bq/L and concentrations of up to 19,900 Bq/L, which have been detected in boreholes in Norwegian granite aquifers, the concentrations measured in Quaternary aquifers are regarded as unproblematic for consumers, although a more detailed assessment may be required for workers spending a lot of time in wellhead areas.
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    Dissolved Gas Transport in the Presence of a Trapped Gas Phase: Experimental Evaluation of a Two-Dimensional Kinetic Model (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Quantitative information on dissolved gas transport in ground water aquifers is needed for a variety of site characterization and remedial design applications. The objective of this study was to gain further understanding of dissolved gas transport in the presence of trapped gas in the pore space of an otherwise water saturated porous medium, using a combination of laboratory experiments and numerical modeling. Transport experiments were conducted in a large-scale (4 × 2 × 0.2 m) laboratory physical aquifer model containing a homogeneous sandpack. Tracer (Br−) and dissolved gas (O2 or H2) plumes were created using a two-well injection/extraction scheme and then were allowed to drift in a uniform flow field. Plume locations and shapes were monitored by measuring tracer and dissolved gas concentrations as a function of position within the sandpack and tune. In all experiments, partitioning of the dissolved gases between the mobile ground water and stationary trapped gas phases resulted in substantial retardation and tailing of the dissolved O2 and H2 plumes relative to the Br− plumes. Most observed plume features could be reproduced in simulations performed with a numerical model that combined the advection-dispersion equation with diffusion controlled mass transfer of dissolved gas between the mobile aqueous and stationary trapped gas phases. Fitted values of the volumetric trapped gas content and mass transfer coefficient ranged from 0.04 to 0.08 and from 10−6to 10−5 sec−1, respectively. Sensitivity analyses were used to examine how systematic variations in these parameters would be expected to affect dissolved gas transport under a range of potential field conditions. The experimental and modeling results indicate that diffusion controlled mass transfer should be considered when predicting dissolved gas transport in ground water aquifers in the presence of trapped gas.
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    A Nonlinear Time Series Model for Spring Flow: An Example from Shanxi Province, China (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A nonlinear time series model is presented to describe the dynamics of ground water flow. The procedures for model-establishing and parameter estimation are discussed. The proposed nonlinear model uses a threshold parameter that relates different precipitation processes, and a lag parameter that relates the time lag between precipitation events and observed increasing spring flow. This model is then applied to the prediction of time-dependent flow of the Longzichi Spring, Shanxi Province, northwest China. The results in this analysis show that the proposed approach can accurately describe the complicated nonlinear time series and the discharge regime of the Longzichi Spring.
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    Efficient and Responsible Use of Prior Information in Inverse Methods (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Prior information on parameters such as hydraulic conductivity or ground water recharge rates is often used to stabilize the inverse problem in parameter estimation. A cautious use of prior information is advisable, however, because it may be biased or unrepresentative of the model parameters and/or it may not significantly stabilize the parameter estimates. Procedures are given: (1) to identify the model parameters for which prior information may best stabilize the parameter set; and (2) to identify the model parameters for which errors in the prior information lead to the smallest possible errors in the final set of parameter estimates. The first case is referred to as the efficient use of prior information; the second case is referred to as the responsible use of prior information. The procedures are based on an analysis of the model parameter space using response surfaces, multiparameter confidence regions, and eigenspace analysis. The guidelines lead to the selection of prior information on those parameters whose axes are most closely aligned with the longest axis of the parameter confidence region. Simple synthetic examples are used to explain the concepts. The advantages gained in screening the model parameters to identify those parameters for which prior information will be most efficient and responsible in determining the final values of the parameter estimates are demonstrated in the calibration of a ground water flow and solute transport model for the San Juan Basin, New Mexico.
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    Safe Yield and the Water Budget Myth (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00162.x
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    Dimensionality of Ground Water Flow Models (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00163.x
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    Long-Term Performance of an In Situ “Iron Wall” for Remediation of VOCs (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The use of granular iron for in situ degradation of dissolved chlorinated organic compounds is rapidly gaining acceptance as a cost-effective technology for ground water remediation. This paper describes the first field demonstration of the technology, and is of particular importance since it provides the longest available record of performance (five years). A mixture of 22% granular iron and 78% sand was installed as a permeable “wall” across the path of a contaminant plume at Canadian Forces Base, Borden, Ontario. The major contaminants were trichloroethene (TCE, 268 mg/L) and tetrachloroethene (PCE, 58 mg/L). Approximately 90% of the TCE and 86% of the PCE were removed by reductive dechlorination within the wall, with no measurable decrease in performance over the five year duration of the test. Though about 1% of the influent TCE and PCE appeared as dichloroethene isomers as a consequence of the dechlorination of TCE and PCE, these also degraded within the iron-sand mixture. Performance of the field installation was reasonably consistent with the results of laboratory column studies conducted to simulate the field behavior. However, if a more reactive iron material, or a higher percentage of iron had been used, complete removal of the chlorinated compounds might have been achieved. Changes in water chemistry indicated that calcium carbonate was precipitating within the reactive material; however, the trace amount of precipitate detected in core samples collected four years after installation of the wall suggest that the observed performance should persist for at least another five years. The study provides strong evidence that in situ use of granular iron could provide a long-term, low-maintenance cost solution for many ground water contamination problems.
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    Ground Water Age and Nitrate Distribution Within a Glacial Aquifer Beneath a Thick Unsaturated Zone (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The impact on ground water quality from increasing fertilizer application rates over the past 40 years is evaluated within a glacial aquifer system beneath a thick unsaturated zone. Ground water ages within the aquifer could not be accurately determined from the measured distribution of 3H and as a result, chlorofluorocarbon (CFC) and 3H/3He dating techniques were applied. Beneath a 25 m thick unsaturated zone, ground water ages based on CFC-11 concentrations were greater than 3H/3He ground water ages by 6 to 10 years, due to the time lag associated with the diffusion of CFCs through the unsaturated zone. Using the corrected CFC-11 and 3H/3He ground water ages and the estimated travel time of 3H within the unsaturated zone, the approximate position of ground water recharged since the mid-1960s was determined. Nitrate concentrations within post mid-1960s recharge were generally elevated and near or above the drinking water limit of 10 mg-N/L. In comparison, pre mid-1960s recharge had nitrate concentrations 〈2.5 mg-N/L. The elevated NO3− concentrations in post mid-1960s recharge are attributed mainly to increasing fertilizer application rates between 1970 and the mid- to late 1980s. Anaerobic conditions suitable for denitrifkation are present within pre mid-1960s recharge indicating that removal of DO is a slow process taking tens of years. Over the next 10 to 20 years, nitrate concentrations at municipal well fields that are currently capturing aerobic ground water recharged near the mid-1960s are expected to increase because of the higher fertilizer application rates beginning in the 1970s and 1980s.
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    Wellbore Skin Effect in Slug-Test Data Analysis for Low-Permeability Geologic Materials (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The wellbore skin effect on slug-test results was analyzed using numerical simulation and field tests for a well at progressive stages of development. The numerical simulation is based on a composite flow model that incorporates a zone of disturbed formation surrounding the wellbore. Field tests were performed on a water-bearing clayey silt formation at a ground-water remediation site in Wisconsin. Based on the numerical simulation, the radius of investigation was examined. The results show that the early-time and late-time data reflect ground-water flow in the wellbore skin and undisturbed formation, respectively.Both the numerically simulated and the field slug-test data define a downward concave curve on a semilog plot of time versus the logarithm of dimensionless head. For the Hvorslev (1951) and Bouwer and Rice (1976) methods, the late-time segment of the simulated data yields estimates of hydraulic conductivity close to the value defined in the flow model. When a wellbore skin exists, the data curve in a plot of the logarithm of time versus the dimensionless head is shifted horizontally along the time axis. This shift leads to an inaccurate determination of hydraulic conductivity based on the Cooper et al. (1967) method. In the plots of time versus dimensionless head derivatives, the data curve geometry depends on the hydraulic properties of the wellbore skin. Consequently, the wellbore skin effect can be identified and eliminated using derivative-based type curve methods.For low-permeability materials, the effect of wellbore skin on estimates of hydraulic conductivity can be minimized through use of the late-time data. However, proper well installation and development appears to be the most effective and practical solution.
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    Surfactant Remediation Field Demonstration Using a Vertical Circulation Well (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
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    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A field demonstration of surfactant-enhanced solubilization was completed in a shallow unconfined aquifer located at a Coast Guard Station in Traverse City, Michigan. The primary objectives of the study were: (1) to assess the ability of the vertical circulation well (VCW) system for controlling chemical extractants added to the subsurface; and (2) to assess the behavior of the surfactant solution in the subsurface, with a goal of maximum surfactant recovery. A secondary objective was to demonstrate enhanced removal of PCE and recalcitrant components of a jet fuel. The analytical results showed that the surfactant increased the contaminant mass extracted by 40–fold and 90–fold for the PCE and jet fuel constituents, respectively. The surfactant solution demonstrated minimal sorption (retardation) and did not precipitate in the subsurface formation. In addition, the VCW system was able to capture in excess of 95% of the injected surfactant solution. Additional field testing and full-scale implementation of surfactant-enhanced subsurface remediation should be performed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00166.x
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  • 89
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    Simulated Recovery of Light, Nonaqueous Phase Liquid from Unconfined Heterogeneous Aquifers (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A multiphase flow model (ARMOS) was used to evaluate the effects of subsurface heterogeneities on the recovery of light, nonaqueous phase liquids (LNAPLs or simply “oil”). Stochastic inputs for the model included the saturated hydraulic conductivity (Ksw), van Genuchten α and n, the water saturation at field capacity (Sm), and the maximum residual oil saturations in the saturated (Sor) and the unsaturated zones (Sog). The turning bands method was used to generate stochastic soil parameters representing three hypothetical sandy loam soils. Oil recovery in the three heterogeneous cases was compared to an “equivalent” homogeneous soil with effective parameters computed as the geometric means of the stochastic parameters. Distributions of the free oil plumes were described over time using statistical and spatial moment analyses. Due to the smoothing effect of the flow process, the predicted well oil thickness (Ho) and free oil specific volume (Vof) were less variable than the input stochastic parameter In(Ksw). However, Ho and Vof became more variable as free oil volume diminished and the oil distribution was controlled more by soil variability than gradients in the fluid levels. At the onset of oil recovery, the free oil area was greater in all three heterogeneous soils than the homogeneous soil. Nevertheless, soil heterogeneities did not greatly affect oil recovery or trapping in the saturated and unsaturated zones. Heterogeneities may have had a greater influence on oil recovery if a smaller spill had been studied or if the vertical dimension had been simulated explicitly. The results suggest that the geometric mean soil properties provide a useful estimate of the potential for oil recovery from oil spills that span a large number of correlation scales.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00165.x
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  • 90
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    Design of a Surfactant Remediation Field Demonstration Based on Laboratory and Modeling Studies (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Surfactant-enhanced subsurface remediation is being evaluated as an innovative technology for expediting ground-water remediation. This paper reports on laboratory and modeling studies conducted in preparation for a pilot-scale field test of surfactant-enhanced subsurface remediation. Laboratory batch and column studies evaluated the surfactant-contaminant ground-water interactions in an effort to properly design the field-scale demonstration. A series of laboratory tracer tests and numerical simulations were completed to demonstrate the effectiveness of the hydraulic system (a vertical circulation well—VCW) for capturing injected solutions in a shallow, highly conductive, unconfined ground-water formation. The results of these studies were then used to optimize the performance of the VCW system during the subsequent field-scale demonstration study which utilized the VCW for injecting and extracting a surfactant solution. Information from the simulation studies, combined with the results of the batch and column tests, was crucial for procuring regulatory approval for the field demonstration, and successful design of the field-scale demonstration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00167.x
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  • 91
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    An Assessment of Conventional In Situ Air Sparging Pilot Tests (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Short-term (〈 24 h) pilot tests play a key role in the selection and design of in situ air sparging systems. During air injection, changes in dissolved oxygen in ground water, water levels in wells, soil gas pressures, and soil gas contaminant concentrations are measured. These parameters are assumed to be indicators of air sparging feasibility and performance. In this work we assess the validity of this critical assumption. Data are presented from a study site where a typical short-term test was conducted for three days, followed by continued operation of a full-scale system for 110 days. Conventional sampling practices were augmented with more discrete and detailed assessment methods. In addition, a tracer gas was used to better investigate air distributions, vapor flow paths, and vapor recovery efficiency. The data illustrate that conclusions regarding the performance and applicability of air sparging can vary dramatically depending on the monitoring approach used. Samples collected for chemical analyses from conventional monitoring wells were clearly affected by the air sparging during, and for some time after, air injection. Results from this site suggest that typical pilot test measurements might be useful for assessing infeasibility, but do not yield sufficient information to extrapolate to long-term performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00145.x
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  • 92
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    Simulation of Regional Flow and Salinity Intrusion in an Integrated Stream-Aquifer System in Coastal Region: Southwest Region of Bangladesh (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A numerical model for simulation of the regional flow and salt-water intrustion in an integrated stream-aquifer system in coastal regions is developed, considering the dynamic interaction between the streams and the aquifer. The stream-aquifer model comprised of a two-dimensional depth-average finite-element model of the aquifer system and a quasi-steady node and reach model of the river network. The applicability of the model was demonstrated, through simulation of the spatial and temporal distributions of flow and salinity in the estuaries and in the underlying aquifer of the Southwest Region of Bangladesh. The important management aspects of water transfer and additional pumping and their effects on the system were evaluated. The interactions between the streams and the aquifer significantly influenced the flow and salt-water intrusion in the aquifer and the river network. An increased abstraction of ground water in the area caused a significant increase in the estuarine salinity. The salinity intrusion in the estuaries of the area, except in the southwest corner, could be reduced significantly by diverting the available water from the Ganges through the boundary river Gorai.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00147.x
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  • 93
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    Using the Deconvolution Approach for Slug Test Analysis: Theory and Application (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This paper presents a new analysis methodology for determining hydrogeological parameters from a single well slug test. The procedure involves converting pressure versus time data from a slug test into a form equivalent to that from a constant rate test using an exact relationship. Deconvolution techniques are applied to remove wellbore storage effects. The converted data are then analyzed using existing head and head derivative type curves for constant (downhole) rate conditions. It is demonstrated that the analysis of the converted data yields reliable estimates of aquifer transmissivity from conventional slug tests and even from short duration (i.e., small recovery) tests in low transmissivity rocks. This method allows successful analysis of data from slug tests that would be considered unanalyzable using conventional interpretation techniques. Moreover, the proposed method is able to determine aquifer storativity independent of the influence of wellbore skin factor. This is impossible using existing techniques such as those based on Cooper et al. (1967) or Ramey et al. (1975). The applicability of the proposed methodology is demonstrated using several synthetic and field examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00148.x
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  • 94
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    Ground-Water Sampling and Time-Series Evaluation Techniques to Determine Vertical Concentration Distributions (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Data analysis methodologies are developed for using time-series measurements of effluent concentrations during continuous sampling to determine the vertical shape and location of a horizontally uniform contaminant plume and to estimate physical/ chemical aquifer parameters such as vertical anisotropy, effective porosity, and retardation factor. Temporal water-quality variations during constant-flow sampling are calculated in the form of concentration type curves for a wide variety of plume shapes and positions and are shown to be directly related to the geometry and growth rate of the three-dimensional capture volume of the well. An analytical type-curve solution is derived for discrete-interval sampling in homogeneous and isotropic/anisotropic aquifers containing plumes with complex vertical shapes that are described by the superposition of multiple Gaussian distributions. Results from two-dimensional, axisymmetric simulations of ground-water flow and particle transport demonstrate the sensitivity of concentration type curves to sandpack hydraulic conductivity, screen length, well diameter, flow through the well screen during discrete-interval sampling, aquifer anisotropy and heterogeneities, pumping rate, effective porosity, and chemical retardation. Two applications of the concentration type-curve method for determining plume and aquifer characteristics are presented. The first illustrates the use of discrete-interval sampling to evaluate the vertical shape and location of a hypothetical plume in a homogeneous, isotropic aquifer. In the second, extraction-well effluent data collected during a field experiment were used to evaluate the vertical concentration distribution in a sulfate plume and estimate the vertical anisotropy ratio of the aquifer. The results demonstrate the importance of developing consistency in purge and sample volumes to minimize artificial measurement variability in monitoring programs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00151.x
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  • 95
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    Closed-Form Expressions for Water Retention and Conductivity Data (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Closed-form expressions for quantifying the unsaturated soil hydraulic properties are widely used in computer programs to model subsurface flow and transport in porous media and to investigate indirect methods for estimating these properties. For example, water retention data, which relate soil-water pressure head (h) and effective water saturation (Se), are frequently used to predict the unsaturated hydraulic conductivity (K). However, the suitability of different functions to describe unsaturated hydraulic data has rarely been investigated comprehensively. We attempted to fit 14 retention and 11 conductivity functions to 903 sets of water retention and hydraulic conductivity data measured on soil and rock samples or horizons reported in the unsaturated hydraulic database UNSODA. Some of the best mean values for r2 and MSE for fitting Se(h) data were obtained with the retention functions reported by van Genuchten (1980), Globus (1987), and Hutson and Cass (1987). A function reported by Gardner (1958) could describe K (h) data quite well whereas functions reported by Brooks and Corey (1964) and van Genuchten (1980), which are respectively based on the conductivity models by Burdine and Mualem, yielded a relatively good description of K(SC) data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00153.x
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  • 96
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    DISCUSSION (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00117.x
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  • 97
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    DISCUSSION (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00119.x
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  • 98
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    AUTHORS’ REPLY (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00120.x
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  • 99
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    AUTHOR'S REPLY (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00118.x
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  • 100
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    Model Simulations in Support of Field Scale Design and Operation of Bioremediation Based on Cometabolic Degradation (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This paper addresses questions fundamental to the design and operation of aquifer bioremediation based on cometabolic degradation. A model of a full-scale, in situ system for bioremediation of chlorinated ethenes relying on cometabolic degradation was developed and applied to a hypothetical aquifer being considered for a large-scale field demonstration of in situ bioremediation with recirculation. The model was used to identify feasible substrate (electron donor and electron acceptor) delivery schedules. Trichloroethylene (TCE) was the target contaminant. Methane and phenol were considered as electron donors. The delivery of the electron donors and the electron acceptor, oxygen, was varied to evaluate the rate and extent of bioremediation under different substrate delivery schedules. Maximum removal of TCE was predicted when substrates are delivered at ratios near the stoichiometric requirement of electron donor and acceptor for net microbial growth.Additionally, the decrease in TCE removal that results from using substrate delivery schedules other than those achieving the maximum removal of TCE was quantified. This decrease was greater for the methane-oxygen system because the two gaseous substrates compete for transfer into the recirculated ground water. If one substrate is introduced in excess of the amount required for net microbial growth, it accumulates, thus limiting the ability to introduce the second substrate. This imbalance both limits the introduction of the second substrate and accelerates the accumulation of the substrate added in excess. The phenol-oxygen system is less sensitive to deviation away from the best observed substrate delivery schedule because phenol is a relatively soluble liquid and its introduction does not compete with the mass transfer of oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00121.x
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