ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02757.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTClassification 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 re

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02758.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTConsiderable 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.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02759.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTIn 1905, N. H. Darton described the geology and underground‐water resources of the central Great Plains in his classic report that emphasized the importance of the Dakota aquifer to this region of the United States. Since Darton's work, many investigators have studied Dakota‐aquifer hydrology with regard to development of local or statewide resources. Preliminary mapping of relatively recent fluid‐level data by the U.S. Geological Survey indicates regional potentiometric trends similar to those interpreted by Darton, but altitudes substantially lower in part of the area. The classic artesian‐system concept of the Dakota aquifer is not consistent with some of the data and observations of the past several decades. The simple aquifer geometry and effective lateral hydraulic continuity normally associated with that concept do not appear to characterize the Dakota aquifer reg

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02760.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTAn experimental test program was conducted to measure the longitudinal permeability of a grouted thermoplastic water well casing system. A neat cement grout, with and without calcium chloride or bentonite admixtures, was placed in the annulus of a simulated well. Test pressure and specimen configuration was shown to influence the measured coefficient of permeability. A neat grout with a water/cement ratio of 2.0 had a much higher permeability coefficient than the same grout with a water/cement ratio of 0.46.Once the bond line between the grout and casing was broken, the permeability of the system was generally higher than for the initial test. Specimens with a bell coupling included had a slightly higher permeability than specimens with straight pieces of casing. The effect on permeability of the admixtures in the grout was not conclusive. However, the addition of a bentonite slurry to the test water was observed to decrease the permeability coefficient when tested under low pressure.The permeability coefficient of the basic neat grout casing system ranged from 20 – 100 × 10−5cm/sec at low test pressure. It was concluded that the casing has an impact on the longitudinal permeability of the system since the coefficients of permeability measured were significantly higher than other published values. However, the coefficients of permeability measured were in the range of soils with low permeability such as s

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02761.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTLarge quantities of sludge can be disposed of safely by burial in narrow trenches. This paper describes a study to quantify the amount of buffer area around a trenching operation that would allow for the natural soils to stabilize sludge leachate without threatening the ground‐water supplies of surrounding communities. A vertical buffer consists of a thickness of unsaturated soil below the base of the trench. Its thickness is calculated by comparing the cation exchange capacity of the soil with the exchangeable cations in the sludge leachate. Data from metropolitan Washington, D.C. consistently require a vertical buffer of less than 3 feet thick. A minimum of 3 feet of unsaturated soil is recommended as a margin of safety, although no specific studies were performed to reach this value. The horizontal buffer is a strip of land that must be maintained between the trenching operations and the site boundary. Its width can be more than two orders of magnitude greater than the vertical buffer. Its width is based on the nitrogen loading of the soil from the sludge and the mobility of nitrate in the upper aquifer based primarily on hydraulic conductivity and the characteristics of the sludge/soil interaction. An advection‐dispersion model predicts nitrate concentrations for various buffer widths, and is used in conjunction with a specified maximum allowable nitrate concentration to determine a minimum horizontal buffer under certain ground‐water flow condi

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02762.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTA field investigation into low flow augmentation using seasonal ground‐water abstraction from the unconfined Chalk aquifer in Hampshire, United Kingdom, revealed the presence of a thin, highly transmissive and storative zone in the Chalk close to the water table. A lumped parameter model of the aquifer‐stream system incorporating a variable transmissivity and storativity distribution has been developed to explain the unusual hydrogeological features of the catchment observed during the investigat

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02763.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe goal of this study was to provide a preliminary assessment of the occurrence and movement of the pesticide aldicarb in ground water in the Central Sand Plain of Wisconsin. Aldicarb concentrations in ground water beneath three main study fields and two subsidiary fields were monitored during the period December 1980–August 1981. A total of 67 well points, some nested, and one multilevel sampler were installed for this study. In addition, 25 private wells and seven irrigation wells were sampled.The data collected to date are limited both in space and time. However, several trends are evident: (1) highest concentrations of aldicarb were detected in shallow monitoring wells (those located immediately below the water table); (2) no aldicarb was detected in any of the deep monitoring wells (those located roughly 60 feet below the water table), although aldicarb was found in some of the irrigation wells finished at approximately the same depth; (3) aldicarb seems to be concentrated in roughly a 5‐foot layer near the water table, and (4) marked seasonal fluctuations in aldicarb concentrations occurred in several we

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02764.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTElevated arsenic concentrations were found in ground water near Canal Fulton, Ohio. The hydrologie and chemical properties of the area were studied to determine the source of the arsenic and evaluate the possibility of a similar problem occurring elsewhere. Two major aquifer systems exist within the study area: the Sharon Sandstone of the upland areas; and the outwash sand and gravel deposits of the buried valleys. Ground‐water flow is generally from the north, but local variations are caused by the Tuscarawas River valley on the south and west of the study area. Within the study area, there is no evidence for an anthropogenic source of arsenic to the ground water. Agricultural soils, abandoned underground coal mines, industrial impoundments to the north, and an abandoned industrial dump site within the study area were all eliminated as possible sources for the arsenic. The arsenic in Canal Fulton ground water is entirely inorganic, consisting of about equal parts of arsenate and arsenite. Reduction‐oxidation (redox) considerations suggest that arsenic is controlled by an adsorption equilibrium with ferric hydroxides, and that the reduction of the ferric hydroxides by a recent lowering of Eh and/or pH in the aquifer has liberated both iron and arsenic to solution. A high correlation between ferrous iron and total dissolved arsenic supports this model. It is hypothesized that Eh conditions have been lowered in the aquifer by either the recent introduction of methane gas or the deposition of a thick layer of till during the last glacial retreat. The methane gas could be leaking from deep underground storage at the site and reducing oxidized compounds. The deposition of till would have eliminated local recharge of oxygenated wat

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02765.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTData from field tracer experiments are interpreted to evaluate the adequacy of an advection‐dispersion model for simulating field conditions. A stimulus‐response approach based on chemical reactor theory was applied. Two different pulse stimuli at an injection well resulted in responses in two observation wells located at distances of 8 and 17 m, respectively, from the injection well. The wells are perforated over the entire aquifer thickness of 1–2 m. The behavior of the two conservative tracers agreed closely with each other. Breakthrough response curves revealed extended trailing edges (tailing), especially at the nearer well. A two‐domain model is employed to extend the simple advection‐dispersion equation to account for the observed tailing. Response curves of concentrations were fitted with finite‐difference simulations using the two‐domain model. The simulations using the two‐domain model agreed well with the field observations. The responses at the more distant well were characterized by values of dispersivity equal to or slightly smaller than those at

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1982.tb02766.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY