ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTInfiltration through a small (3 × 9 × 1 m) experimental earthen liner, similar to those used for waste disposal was evaluated. The liner was constructed using full‐size compaction equipment, and in‐situ ponded infiltration rates were measured using two large (1·5‐m diameter) sealed double‐ring infiltrometers. An average apparent steady‐flux density of 1·5 × 10−7cm/s was achieved after two to three weeks. Wetting front depths of 7·3 cm and 9·6 cm after 46 days were calculated assuming a Green‐Ampt piston flow infiltration system. One of the infiltrometers was ponded with water containing rhodamine dye and after the 46‐day infiltration test, a uniform rhodamine dye front was observed at about the 4‐cm depth. Sharpness of the dye front suggests that the piston flow assumption is a reasonable one. Apparent saturated hydraulic conductivity of the liner was estimated from the infiltration data to be no more than 3·6 × 10−8cm/s, meeting the present EPA permeability requirement for earthen liners of no more than 1 × 10−7cm/s. Transit time for the wetting front to reach the liner bottom at the 0·91‐m depth was predicted to be about three years. Seepage flux after liner saturation was estimated at 4·8 × 10−8cm/s

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTOn the basis of the degree of mineralization, approximately 40 percent of the ground water in Ross Creek Basin may be considered as fresh (TDS<2,000 ppm), and 60 percent as brackish (2,000

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTStatistical‐based, semiquantitative techniques [Factor Analysis (FA) and Correspondence Analysis (CA)] were applied to chemical data from two aquifers to assess the usefulness of such techniques at the initial stages of hydrochemical studies.For the first case, both FA and CA defined three factors to account for the major ion variations observed in the Milk River aquifer (Alberta, Canada), namely, sulfate reduction occurring in the recharge area and mixing of waters of different ages in the deeper portions of the aquifer, ion‐filtration processes, and ion exchange on clays. For the FA, the comparison between varimax and oblique rotations led to similar interpretations.For the second study area, the San Pedro River basin (Arizona, U.S.A.), FA (Q‐mode) extracted two factors, which helped segregate waters from the two aquifers in the area. The CA, applied only to samples from the confined aquifer, drew two factors which were related to dissolution of gypsum coupled with ion exchange (softening) as the main mechanisms operating in the aquifer, along with a hypothetical presence of fluorite in the aquifer sediments to justify the rather high [F‐] observed in local ground waters.Comparisons made between the results presented and the findings of earlier studies highlight the descriptive capabilities of FA and CA as exploratory tools in hydrochemical investi

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTUnsaturated solute transport experiments were conducted using several small and one large column packed with the same sandy soil material.Chloride and tritium were used as tracers for water movement. Soil solution samples were collected as a function of time in the small columns and versus time and depth in the large column. The data were compared with solutions of the classical two‐parameter convection‐dispersion equation and also with solutions of a more elaborate four‐ parameter transport model that assumes a fraction of the water to be immobile. Fairly symmetrical effluent curves resulted from both the small and large columns, suggesting small transfer coefficients between mobile and immobile regions and small amounts of immobile water. Dispersivity values ranged from 1 cm for the small columns to about 5 cm for the 6‐m‐long column; retardation factors for chloride were nearly the same (about 0.8) for both column sizes. Thus, while the dispersivity measured in the small columns did not apply to the large columns, the same retardation factors could be applied to the different scal

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe concentration of dissolved inorganic carbon (DIC) species and the other major ionic constituents were determined at 45 sampling locations within the Tucson basin aquifer. The distribution and concentration of the various inorganic carbon species were related to the hydrogeological characteristics of the principal recharge zones within this alluvial basin. Bicarbonate alkalinity concentrations were highest subjacent to a floodplain where calcite and other relict salts likely precipitated in the shallow subsurface under past pluvial conditions.Calculated partial pressure of carbon dioxide (PCO2) values were highest where the water table is sufficiently elevated to support phreatophyte growth. The regional distribution of PCO2suggests that the generation of carbon dioxide is limited to the oxidation of influent plant detritus below the stream channels. The alkalinization of Tucson basin ground water is ultimately constrained by this limited production of CO2. The dissolution of calcite in young ground water (<200 years) and the precipitation of calcite in deeper, more chemically evolved ground water likely represent other important controls upon DIC concentrations.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTArtificially recharging the ground‐water system is one water resource option available to the Las Vegas Valley Water District in response to increasing water demand during summer peak periods. The existing water‐supply system for Las Vegas Valley is limited since peak water‐use demand periods in 10 to 20 years or less will require the construction of additional facilities. To prepare for these short‐term (and longer) demands, the Las Vegas Valley Water District, in cooperation with the U.S. Bureau of Reclamation, conducted a limited ground‐water recharge demonstration project using treated Colorado River water.A major concern of water managers regarding artificial recharge is the resulting water chemistry when treated (potable) Colorado River water is injected into the ground‐ water system. Both waters are high in calcium creating a potential for calcite precipitation which, in addition to clogging the perforations in the water well casing, could potentially reduce aquifer permeabilities by clogging the pore space of the flow media.Approximately 525,000 gallons of potable water were injected into a semiconfined ground‐water aquifer over a three‐day period interspersed with two pumping periods. Water chemistry samples taken throughout the injection project showed no imbalance with regard to calcium or any other chemical constituent. Therefore, artificial recharge is feasible and is one water resource technique available to meet an increasing water demand based on the existing water quality of the Colorado River and the quality of the ground water in the ar

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTRecovery of contaminated ground water in a fractured bedrock system presents some unique problems. Typically, the most common problem occurs from the inability to adequately characterize the discrete fractures through which contaminants may be migrating. Without adequate characterization, difficulties arise in properly positioning recovery wells and verifying the performance of the system. To overcome these difficulties at a site in Upstate New York, an innovative approach was developed involving the creation of an artificial fracture zone through controlled blasting to intercept contaminated ground‐water flow.Site investigations delineated the extent of a ground‐ water contamination plume migrating within a fractured bedrock aquifer (Medina sandstone) which underlies approximately 15 ft of glacial till. A 72‐hr aquifer test involving one recovery well resulted in a low yield (3.5 gpm with 20 ft of drawdown). Data collected from adjacent observation wells indicated poor interconnection among the naturally occurring fractures. Although the response of some observation wells mirrored that of the recovery well, others showed little or no response to pumping. Therefore, achieving the corrective action objectives (i.e., preventing further contaminant migration and removing and treating contaminated ground water) would be difficult using a “traditional” multiple recovery well system. It was decided that controlled linear blasting could provide the enhanced fracture interconnection necessary to successfully intercept the contaminated ground‐water plume, which would then be captured and removed by judicious placement of recovery well(s) installed within the fracture zone.Using a carefully controlled single line pattern blasting technique, a 6‐ft wide, 300‐ft long fracture zone was created in the upper 25 ft of the bedrock aquifer perpendicular to the centerline of the plume. Following fracturing, a second 72‐hr aquifer test was conducted at the same location and under conditions similar to the first test. The second test indicated that the single recovery well located in the newly created fracture zone should be fully capable of recovering contaminated ground water and preventing further migration of the plume. The recovery well produced a substantially higher yeild of 18.5 gpm with only 11.2 ft of drawdown. Futhermore, all of the nearby observation wells showed significant response to pumping.Success at this site is promising, and the approach may prove useful at other sites involving contaminated

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTA deconvolution method is proposed for the estimation of aquitard/aquiclude vertical hydraulic diffusivities on the basis of water‐level measurements in piezometers completed both in the confining layer(s) and in neighboring aquifers. The water levels may fluctuate in an arbitrary manner which is not necessarily caused by a prescribed pumping regime (as required in conventional pumping tests). A simple formula from the literature can be used to correct the measured water levels for time lag in the piezometer response. If the specific storage of the confining material is known from laboratory consolidation tests, the hydraulic diffusivity estimates can be translated into vertical hydraulic conductivities. The method is illustrated with the aid of a case study from southern California and is shown to yield robust parameter estimate

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1989.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY