ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00970.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00971.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00972.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00973.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00974.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractDetermination of the nature, extent, and rate of off‐site chemical migration are common objectives of hazardous waste site investigations. Chemical analyses of water samples from monitoring wells and measurements of hydraulic head and hydraulic conductivity provide the basis for making these determinations. Accurate site assessment, therefore, depends upon the appropriate monitoring well design and sampling and testing procedures.During the course of remedial investigations in Niagara Falls, New York, it has been necessary to evaluate the ground water quality and hydraulic characteristics of 5‐ to 30‐feet thick overburden formations. Many of the monitoring wells completed to these formations consist of a partially penetrating screen (5 feet at the base of the formation) with a fully penetrating sandpack. Questions regarding how this well design influences the source of sampled ground water and hydraulic tests were examined using an extremely fine axisymmetric grid with SATURN, a two‐dimensional, finite‐element ground water model, and a particle tracking post‐processor.A discrete sensitivity analysis was made to determine how flow patterns induced by pumping at 1 gpm are affected by: different screen and sandpack configurations, the ratio of sandpack to formation hydraulic conductivities, heterogeneity, anisotropy, and sandpack thickness. The simulations show that the source (and chemistry given a non‐uniform chemical distribution) of ground water sampled will vary considerably depending on a number of factors. Analysis of simulated drawdowns in the monitoring well during purging shows that calculated transmissivities for the range of well designs and conditions modeled will be accurate to within one‐half ord

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00975.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe procedures used to construct monitoring wells with hollow‐stem augers may vary depending on the hydrogeologic conditions at the site. In cohesive materials in which the borehole stands open, the auger column may be fully retracted from the borehole prior to the construction of the monitoring well. In non‐cohesive materials in which the borehole will not stand open, the monitoring well may be constructed through the hollow axis of the auger column.The techniques used to construct monitoring wells through the hollow axis of the auger column may vary depending on the specific site conditions and the experience of the driller. Selection of an appropriately sized diameter hollow‐stem auger for the installation of the required size of well casing is necessary to permit an adequate working space between the casing and augers, through which filter pack and annular seal materials are emplaced. Assurance that the filter pack and annular seal are properly emplaced is typically limited to careful measurements taken and recorded during construction of the monitoring

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00976.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractHole stability problems occurring during construction of monitoring wells in coarse, unconsolidated alluvium can be overcome by using a drill‐through casing driver mounted on a standard top‐head drive rotary rig. Steel casing is driven contemporaneously with drilling, providing continuous hole stability. Samples of aquifer material and ground water can be taken at discrete depths as drilling proceeds. Monitoring well completion is accomplished by: (1) using the steel casing as an open‐ended piezometer; (2) installing a telescoping well screen; (3) plugging the casing end and perforating desired intervals, (4) installing one or more smaller diameter wells, and then (5) pulling back the steel casing. Advantages of this drilling method include maintenance of hole stability during drilling and well completion, faster borehole construction time than traditional methods in coarse alluvial deposits and other poorly sorted formations, and collection of representative samples of the geologic formations and ground water; additionally, drilling fluids are not req

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00977.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTwenty monitoring wells were installed in fine‐grained glacial till at two sites in southeastern Wisconsin to study the effects of monitoring well construction, installation, and development on the amount of fine‐grained suspended material in the well. The types of well screens used were continuous slot, factory slot, factory slot with a filter wrap, and porous piezometer tips. Some of the wells were installed before the open borehole began to fill with water; others were installed after the water levels in the lower section of the borehole had begun to rise. About half of the wells were developed by surging while the others were simply bailed without surging. Installation of the wells in the initially dry holes resulted in wells that yielded samples with very low turbidity compared to wells installed in wet holes. Water samples from wells that were surged were more turbid than those that were not. The type of construction materials investigated had no effect on the turbidity of samples from the we

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00978.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe approximations implicit in Cochran's approximation to the Behrens‐Fisher test are examined. This test is often used in evaluating ground water quality problems with temporal and spatial variabilities. Concern is focused on the impact of the number of samples and the magnitude of the variances at the sampling locations. Recommendations are presented for utilization of the t‐test and Cochran's approximation, because Cochran's test is an approximation formula. Indications are provided for where the results may be giving answers different from those inten

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1988.tb00979.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY