bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Study of a Pseudomonad Infestation in a Well at Shilo, Manitoba
Authors: Cullimore D. R. 
Published: March 2006

ABSTRACTWater from a newly installed well (4A) at the Canadian Forces Base, Shilo in Manitoba, Canada was reported to be producing a hydrocarbon smell and sporadic turbidity which was shown to be caused by the generation of a significant population of the bacterium Pseudomonas aureofaciens. In this investigation, the pseudomonad was isolated, identified and found to be able to degrade mineral oil (as a source of organic carbon) aerobically but was not capable of nitrate respiration or of anaerobic growth. The generation of high populations (and turbidity) of Pseudomonas aureofaciens in the well water was linked to the presence of dissolved oxygen in the water along with sufficient hydrocarbons to support growth. The maximum population recorded was 8 × 105 C.F.U./ml. The origin of the hydrocarbons in the ground water was postulated to have been long‐term solvent spills from a nearby paint shop.
Regional Trends in Transmissivity and Hydraulic Conductivity, Lower Cretaceous Sands, North‐Central Texasa
Authors: Macpherson Gwendolyn L. 
Published: March 2006

ABSTRACTDepositional 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.
Gravity Exploration of a Buried Valley in the Appalachian Plateau
Authors: Wilson Michael P. , Peterson Donald N. , Ostrye Thomas F. 
Published: March 2006

ABSTRACTThe 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.
Drawdowns in Large‐Diameter Wells Due to Decreasing Abstraction Rates
Authors: Rushton K. R. , Singh V. S. 
Published: March 2006

ABSTRACTDue to characteristics of centrifugal pumps, most pumping tests in large‐diameter wells exhibit a decreasing abstraction rate with increasing drawdown. Type curves are obtained for the case of abstraction rates which are functions of the well drawdown; values for the type curves are obtained from a numerical model. For the case of constant abstraction, these curves provide an alternative to the classical approach. By plotting the ratio of drawdowns at different times, it is possible to identify more easily when the aquifer begins to contribute to the well discharge. The practical application of the technique is illustrated by a field example.
Evaluation of Surface Impoundment Assessment in New Mexico
Authors: Person Mark , Antle Rebecca , Stephens Daniel B. 
Published: March 2006

ABSTRACTSurface Impoundment Assessment (SIA) is a methodology for determining the potential for ground‐ water contamination from pits, ponds and lagoons. SIA produces a numerical rating of a site, based on the sum of scores assigned to four categories: vadose zone properties, ground‐water availability, ground‐water quality, and waste characteristics. The SIA for New Mexico was conducted as part of a nationwide survey of potentially hazardous waste‐disposal sites. Comparisons of the contamination potential scores and observed ground‐water contamination from mining, milling, and industrial impoundments in New Mexico using histograms, Mann‐Whitney U‐Test, and linear logistic regression indicate that vadose zone properties and the nature of the waste contribute most to the general success of the SIA method to predict contamination. The remaining two categories which rate ground‐water availability and natural ground‐water quality do not appear to be reasonable measures of ground‐water contamination potential. Rather, these categories are more indicative of the value of the ground‐water resources.
Evaluating System for Ground‐Water Contamination Hazards Due to Gas‐Well Drilling on the Glaciated Appalachian Plateau
Authors: Harrison Samuel S. 
Published: March 2006

ABSTRACTRecent drilling for natural gas in the Glaciated Appalachian Plateau area of northwestern Pennsylvania has caused limited, but increasing ground‐water contamination. By evaluating hydrogeologic parameters at a proposed gas well site, such as the ground‐water flow system, permeability of surficial sediments, and the presence of fracture zones, the contamination hazard of the site can be assessed. Three case studies document that the most hazardous sites are generally located on or near valley walls of major drainageways. The relatively steep hydraulic gradient, the frequent presence of highly permeable surficial sediments, and the low to moderate dilution of contaminants along the intermediate‐length flow paths at these sites all contribute to a relatively high pollution hazard. In addition to locating gas wells in high‐hazard hydrogeologic zones, allowing the annulus of gas wells to become pressurized is the other major factor contributing to aquifer contamination.
An Examination of Scale‐Dependent Dispersion Coefficients
Authors: Molz Fred J. , Güven Oktay , Melville Joel G. 
Published: March 2006

ABSTRACTMany hydrologists have observed that dispersion coefficients, when measured in the field, turn out to be scale‐dependent. That is, the greater the travel distance in a tracer test used to measure dispersivity, the larger the dispersivity value that is calculated. Recently, Güven et al.(1983) presented a study which contains a basis for understanding the phenomenon of scale‐dependent dispersion within a deterministic framework. The results of that study are used as a basis for defining a scale‐dependent macro‐ dispersion coefficient for unidirectional flow in a stratified aquifer. Theoretical expressions are then obtained for the macrodispersivity, its various components, and its small time and large time limits. Using the data of Pickens and Grisak (1981a, b), numerical values are calculated for the macrodispersivity, and estimates are made of the travel distance required in order to reach Fickian conditions. Asymptotic large time macrodispersivity values of 49.5 m to 990 m and travel distances of 5.4 km to 109 km result for the particular aquifer studied. Based on these results it appears that Fickian conditions will seldom apply in practice to porous media flow. This study and previous studies show that the primary physical mechanism that causes spreading of a solute near the source is different advection rates at different elevations in the aquifer. Present results and comparisons with field data indicate that this phenomenon is not represented well by a scale‐ dependent dispersion coefficient. In modeling dispersion phenomena, it appears that more emphasis should be placed on field study and the accurate determination of hydraulic conductivity variations and other nonhomogeneities, and less on incorporating somewhat arbitrary dispersion coefficients into complex mathematical models.
Ground‐Water Modeling in a Southwestern Alluvial Basin
Authors: Hawkins David B. , Stephens Daniel B. 
Published: March 2006

ABSTRACTA two‐dimensional finite‐difference computer code was used to model the ground‐water flow system in an alluvial basin in southwest New Mexico. A three‐step approach was used to determine the transmissivity distribution for the model. First, values of the natural logarithm of transmissivity (In T) were interpolated from existing data using the kriging technique. This interpolation scheme also produced a map of standard deviations of the kriging errors. Second, a conventional flow net was drawn from steadystate water levels with the aid of the kriged hydraulic head distribution. Third, the approximate transmissivity map, the standard deviation map of the kriged In T values, and flow net were used to select the segment of each streamtube where transmissivity was known with greatest certainty (smallest In T kriging error). Then, transmissivities in other segments of the stream tubes were calculated from Darcy's Law. This distribution, when input to the numerical model, did not have to be altered appreciably during the calibration for a steady‐state and seven‐year transient period. Most of the transient calibration was accomplished by adjusting storage coefficients. Considering the uncertainty in the available pumping data, very good agreement was found between observed and predicted water levels during a four‐year model verification period.
Matrix Diffusion Effects on Contaminant Migration from an Injection Well in Fractured Sandstone
Authors: Feenstra Stan , Cherry J. A. , Sudicky E. A. , Haq Zia 
Published: March 2006

ABSTRACTDeep‐well injection into fractured sandstone is an option for the disposal of contaminated mine dewatering discharge from an open pit uranium mine. As part of the assessment of potential contaminant migration from deep‐well injection, the effect of matrix diffusion was evaluated. An analytical mathematical model was developed for the simulation of the radial movement of a contaminant front away from an injection point under steady flow conditions in a planar fracture with uniform properties. The model includes the effects of advection in the fracture, diffusion of contaminants from the fracture into the rock matrix, and equilibrium adsorption on the fracture surface as well as in the rock matrix. Effective diffusion coefficients obtained from laboratory experiments on 11 intact core samples varied from 3.4 × 10−8 to 3.2 × 10−7 cm2/s. Model simulations were made with diffusion coefficient values in this range and with single‐fracture injection rates estimated from fracture frequencies in boreholes, and from bulk hydraulic conductivity values obtained from field tests. Because of matrix diffusion, the rate of outward movement of the front of the nonreactive contaminants from the injection well is much slower than the rate of water flow in the fractures. Simulations of the movement of contaminants that undergo adsorption indicate that even a small distribution coefficient for the rock matrix causes the contaminants to remain very close to the injection well during the one‐year period. The results of the simplified model demonstrate that matrix diffusion is an important process that cannot be neglected in the assessment of a waste disposal scheme located in fractured porous rock. However, in order to make a definitive assessment of the capability of matrix diffusion and associated matrix adsorption to significantly limit the extent of contaminant migration around injection wells, it would be necessary to conduct field tests such as a preliminary or experimental injection.
Ground‐Water Quality at a Creosote Waste Site
Authors: Bedient P. B. , Rodgers A. C. , Bouvette T. C. , Tomson M. B. , Wang T. H. 
Published: March 2006

ABSTRACTAn abandoned creosote facility in Conroe, Texas, has become a field site for the National Center for Ground Water Research (NCGWR) at Rice University. Ground‐water contamination in the shallow aquifer beneath the site was characterized by sampling soils and water quality at 14 monitoring wells and 35 boreholes.Results from six sampling trips over two years for inorganic and organic chemical concentrations in the ground water show wells around the site were contaminated to levels above 800 μg/l for naphthalene, 400 μg/1 for methyl naphthalene, and 150 μg/1 for dibenzofuran. Conservative constituents, traced by chloride concentrations up to 75 mg/l, have migrated 300 ft (90 m) downgradient of the site. Organic contaminants have been adsorbed and microbially degraded in their migration from the waste source as evidenced by their attenuated concentrations. Detailed field pump tests have been performed to evaluate hydraulic conductivity at several of the shallow wells. The U.S. Geological Survey (USGS) Solute Transport Model (Konikow and Bredehoeft, 1978) has been used to predict chloride plume patterns and evaluate parameters which govern transport processes at the Conroe waste site.
A Syringe and Cartridge Method for Down‐Hole Sampling for Trace Organics in Ground Water
Authors: Pankow James F. , Isabelle Lome M. , Hewetson Janet P. , Cherry John A. 
Published: March 2006

ABSTRACTA newly developed technique which allows the down‐hole sampling and subsequent analysis of ground water for trace organic contaminants was tested during an investigation of contaminant migration at an inactive landfill site in Burlington, Ontario, Canada. The sampling device, which is lowered down piezometers with a tube, consists of a small cylindrical cartridge of sorbent material attached to a syringe. Vacuum or pressure applied at the surface controls the movement of the plunger in the syringe. The volume of the syringe determines the volume of sample water that passes through the cartridge. The cartridge is removed from the syringe at the surface. One cartridge is used for each sampling; the syringe is reusable. The residual water in the cartridge is removed in the laboratory, and the cartridge is desorbed to a fused silica capillary column for analysis by gas chromatography (GC). The analyses discussed here were performed on a GC/mass spectrometer/data system (GC/MS/DS). Of the many organic compounds that were identified in the samples, three compounds were clearly landfill‐related: 1,1,1‐trichloroethane, chlorobenzene, and para‐dichlorobenzene. The three compounds were found at levels substantially above blank levels in 9, 5, and 5 piezometers, respectively. The average concentrations were 14., 5.3, and 0.88μg/1 (ppb), respectively. The pooled coefficients of variation for the analyses for the three compounds were 27., 6.9, and 6.4%, respectively. The volatility of 1,1,1‐trichloroethane was probably the cause of the greater variability in its analytical data. The main advantages of the technique over most conventional sampling methods include: (1) down‐hole sampling in a manner which minimizes the potential for volatilization losses; (2) avoidance of passage of the sample through long sections of tubing that may contaminate the sample or cause adsorptive losses; (3) convenience of sample handling, storage, and shipping; and (4) high sensitivity.
Subsurface Injection of Treated Sewage into a Saline‐Water Aquifer at St. Petersburg, Florida — Water‐Quality Changes and Potential for Recovery of Injected Sewage
Authors: Hickey John J. , Ehrlich Garry G. 
Published: March 2006

ABSTRACTThe city of St. Petersburg is testing subsurface injection of treated sewage into the Floridan aquifer as a means of eliminating discharge of sewage to surface waters and as a means of storing treated sewage for future nonpotable reuse. The injection zone at the test site at the start of injection contained saline water with chloride concentrations ranging from 14,000 to 20,000 milligrams per liter (mg/1).Treated sewage with a mean chloride concentration of 170 mg/1 was injected through a single well for 12 months at a mean rate of 4.7 × 105 cubic feet per day. The volume of water injected during the year was 1.7 × 108 cubic feet. Dissolved oxygen was contained in the sewage prior to injection. Water removed from the injection zone during injection was essentially free of oxygen. Probable growth of denitrifying bacteria and, thus, microbial denitri‐fication, was suggested by bacterial counts in water from two observation wells that were close to the injection well.The volume fraction of treated sewage in water from wells located 35 feet and 733 feet from the injection well and open to the upper part of the injection zone stabilized at about 0.9 and 0.75, respectively. Chloride concentrations stabilized at about 1,900 mg/1 in water from the well that was 35 feet from the injection well and stabilized at about 4,000 mg/1 in water from the well that was 733 feet from the injection well. These and other data suggest that very little near injection‐quality treated sewage would be recoverable from storage in the injection zone.
Hydrogeology of Wadi Al‐Yammaniyah, Saudi Arabia
Authors: Memon Bashir A. , Kazi Asadullah , Bazuhair Abdulghafar S. 
Published: March 2006

ABSTRACTQuaternary alluvium, ranging in thickness from a few to 100 meters underlain by Precambrian rocks of metamor‐phic and igneous origin, constitutes an important source of ground water in Wadi Al‐Yammaniyah, Saudi Arabia. The purpose of this report is to assess the hydraulic properties, quality of water, and estimated change in storage in waterbearing rocks in the area.The results of eight pumping tests carried out in hand‐dug, large‐diameter wells, indicate that the hydraulic conductivity of the alluvial aquifer ranges from 5.6 × 10−5 to 1.85 × 10−3 cm/second (3.36 × 10−5 to 1.11 × 10−3 m/minute) and that its storativity varies from 8.23 × 10−2 to 1.17 × 10−1.The aquifer is replenished by sporadic but intensive rainfall of short duration. The present withdrawal is only about 10 percent of the annual recharge which is estimated at 52 × 106 m3. It is shown that there is a substantial potential for the future development of potable ground water which would be required for the development of the area.
Modeling of Trace Organics Biotransformation in the Subsurface
Authors: Bouwer Edward J. , McCarty Perry L. 
Published: March 2006

ABSTRACTBiofilm processes are potentially important for transformations of organic micropollutants in ground water. Some theoretical hypotheses and empirical observations suggest that a concentration threshold exists for some compounds below which the concentration cannot be reduced by bacterial action. However, in the presence of one compound at a relatively high concentration, termed the primary substrate, another compound present at trace concentrations, termed the secondary substrate, can be biotransformed as well. These concepts were evaluated through laboratory column studies with several halogenated organic compounds of importance in ground water. A biofilm model can successfully describe utilization of trace substrates, and application to modeling the subsurface is discussed. A simplified batch model with first‐order kinetics may be adequate for describing subsurface microbial processes when low active organism and pollutant concentrations exist over a large scale.
An Idealized Ground‐Water Flow and Chemical Transport Model (S‐PATHS)
Authors: Oberlander Phil L. , Nelson R. W. 
Published: March 2006

ABSTRACTThe number of studies on the actual and potential environmental consequences of contaminated ground water is growing. One means of studying these consequences is through an idealized flow and transport model, S‐PATHS, which allows the hydrologist to determine the salient features of contaminant migration with a minimum of data.The transport of contaminants by ground water from many waste disposal sites can be geometrically idealized as flow between a line and a circle. The flow system adjacent to the disposal site can be represented as a contaminant line source, and a downgradient pumping well as a circular sink. To study waste disposal sites on a larger scale the model geometry is reversed and the disposal site is represented as a circular source, and a river or other convenient line of evaluation is represented as a line sink. This idealization allows S‐PATHS to describe the flow and transport process directly by a single partial differential expression. S‐PATHS considers transmissivity, effective porosity, sorption, source strength, source concentration, decay, potentiometric gradient, circle size, and distance to the line. Coding for the model is not lengthy and can be run on a large‐capacity, hand‐held calculator.
Field Testing the Hypothesis of Darcian Flow Through a Carbonate Aquifer
Authors: Hickey John J. 
Published: March 2006

ABSTRACTThe acceptability of the hypothesis of Darcian flow through a semiconfined carbonate aquifer was tested prior to running a multiple‐day aquifer test in Pinellas County, Florida. The approach used to test the hypothesis was to run a number of hour‐long aquifer tests at different discharges with drawdown measured at the same time during each test in two observation wells, one at 35 feet and the other at 733 feet from the pumped well. If the hypothesis were acceptable, a plot of drawdown versus discharge should describe a straight line.A linear relation was described in 15‐minute and 1‐hour data plots of drawdown versus discharge for both observation wells. Thus, the hypothesis of Darcian flow through the semiconfined carbonate aquifer was deemed acceptable. Drawdown data from the distant observation well collected during the following multiple‐day aquifer test were then analyzed for aquifer‐property values of transmissivity, storage coefficient, and leakance coefficient using standard methods. Discharge for the multiple‐day test was within the discharge range of the hour‐long tests.
Simulation of Ground‐Water Flow in a Mined Watershed in Eastern Ohioa
Authors: Weiss Jonathan S. , Razem Allan C. 
Published: March 2006

ABSTRACTA 43‐acre watershed in Muskingum County, Ohio, was studied to determine the hydrologic consequences of strip mining for coal. A quantitative description of the effects on the ground‐water flow components of the hydrologic system has been obtained using digital models.The premining watershed was characterized by nearly flat‐lying sedimentary rocks of the Pennsylvanian System. Underclay beneath the two major coal beds formed bases for perched zones, creating three separate aquifers. Recharge to the ground‐water system occurred mainly by percolation of precipitation. Most of the discharge from the top and middle aquifers occurred by downward leakage to the underlying aquifers. A smaller amount of discharge occurred as springflow or streamflow near the intersections of the underclays and land surface.Mining has destroyed the top aquifer, and has replaced the bedrock by spoil material. Water levels in the spoils are at a much lower altitude than existed in the premining top aquifer because of a combination of (1) a larger hydraulic conductivity, (2) areal variations of the hydraulic characteristics of the confining bed, and (3) a slower rate of recharge from precipitation caused by removal of vegetation and soil compaction. Covering of previously exposed portions of the middle aquifer and a lower hydraulic head in the spoils has allowed less recharge to the middle aquifer. Additional flow is induced across the western boundary of the watershed and has reduced the outflow across the eastern boundary. Discharge from the middle aquifer as downward leakage and streamflow is less than before mining.
The Optimal Spacing of Interfering Wells: An Analytic Solution
Authors: Briscoe John 
Published: March 2006

ABSTRACTAn exact expression is derived for the optimal spacing between interfering wells in a rectangular well field in an ideal confined aquifer. A simple, practical method for determining the optimal spacing is presented. The optimal spacing is shown to be substantially different from the spacing determined by use of the Theis formulation. The economic savings resulting from use of the revised approach are evaluated and found to be considerable, especially when the number of wells is large and the transmissivity of the aquifer low.