ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00498.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00499.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00500.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00502.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00503.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00504.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn 1992, the U.S. Environmental Protection Agency (EPA) proposed risk‐based management of hazardous waste. A major component of the proposed rule is the determination of non‐site‐ specific screening concentration levels from waste leachate. Ground water at a downgradient exposure point must not exceed those screening levels, or more stringent requirements would apply.The screening concentration level is determined with verified models and equations that simulate the transport and attenuation of chemicals as they travel from the source area to the exposure point. A consortium of screening levels is determined in this paper by considering varying physical, chemical, and biological conditions. In addition, a method is developed for multi component leaching from contaminated soils in a landfill to determine the time‐dependent behavior of a finite source. Finally, this paper discusses infiltration rate through the cla

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00505.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA large subsurface pool of waste solvent product, consisting primarily of 1,1,1‐tichloroethanc and carbon tetrachloride, was encountered during investigations at an industrial site in northern New Jersey. In the 1950s the product was discharged through a settling chamber directly below the shallow water table. Eventually the product accumulated within elongated depressions of erosional surface of varved clays at depths 10 to 15 feet below grade. The host sediment, line to medium sand, was overlain by line sand and silt. The delineated area of pooled DNAPLs covered 2750 feet2, and the maximum pool thickness exceeded 3 feel.The primary recovery involved pumping product from nine wells. Each recovery well was equipped with a sump extending into the clay, which enabled the system to keep the product pumping level below the bottom of the pool. A total of 3495 gallons of solvent product was recovered over two years. Nearly half of this volume was produced by two wells placed at the lowest points of the pools. Postpumping sampling of the former pools indicated that 43 to 94 percent of the pooled solvent mass was removed during the primary recovery. Average initial product salutation within the pool was estimated at 53.2 percent of the total porosity measured at 31 percent. Average residual saturation after the primary product recovery was 3.7 percent of the total pore volume.To test the feasibility of residual product recovery, an experimental secondary recovery was undertaken. Using sheet piling, a 506 feet2lest cell was constructed inside the former DNAPL pool. The cell featured a central recovery well, six peripheral wells, and monitoring probes. I he selected sequence of secondary operations included partial dewatering. hot water injection, final dewatering, and thermally enhanced vapor extraction (TVE). During six weeks of the secondary recovery operations. 87.9 gallons of product were removed, of which 72 percent was from TVE. 25 percent from hydraulic mobilization effects. and 3 percent from dissolution of residuals. Confirmatory soil sampling showed an average reduction of residual contamination by 93.4 percent in comparison to the concentration of residuals prior to the secondary recovery. For the lest cell, a combined total solvent recovery of 99.6 percent was achieved. This high recovery exceeded DNAPL recoveries expected or achieved in other field‐scale attem

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00506.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper presents analytical solutions for determining non‐steady‐state capture zones produced by a single recovery well and steady‐state capture zones produced by multiple recovery wells. Analysis of non‐steady‐slate capture zones is based on the lime‐dependent location of caplure zone stagnation points and the geometric similarity between steady‐slate and non‐steady‐state capture zones. The analytical solution of steady‐state capture zones is obtained from spatial variations of discharge potential across the capture zone boundary. Both capture zone analyses are based on the assumptions of uniform flow field with a constant hydraulic conductivity, the Dupuit assumption of insignificant vertical flow, a negligible delayed yield, and a fully penetrating well with a constant pumping rate. For a ground water pump‐and‐trcat remediation program, the pumping rate and well location design variables can be adjusted to ensure containment of the ground

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00507.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA small‐scale field experiment was carried out to demonstrate the effectiveness of using septic system ‐type infiltration beds for on‐site treatment of landfill leachate. Using an infiltration bed with a 3‐m‐thick vadose zone of medium sand, and loaded at a rate 01 18 cm/day, a treatment efficiency of>99 percent was obtained for Fe, 94 percent for NH4+, and 54 percent for dissolved organic carbon (DOC). Attenuation occurred during one‐ to two‐day residency in the aerobic vadose zone (pore gas O2>12 percent by volume) as a result of oxidation reactions that caused nitrification of NH4+, convened Fe2+to Fe3+allowing subsequent precipitation of sparingly soluble Fe oxyhydroxide minerals, and biodegraded DOC. Attenuation of an aerobically degradable trace volatile organic compound (dichlorobenzene) was also noted, although other less degradable compounds (trichloroethylene and tetrachloroethylene) persisted.Fe mineral precipitation caused a discontinuous hardpan layer to occur in the zone immediately below the infiltration pipes. However, this layer did not become impermeable or continuous enough to significantly impede infiltration during the 82‐day experiment.Advantages of this technology for leachate treatment are that it is low cost, it is simple to construct and operate. and treatment occurs on‐site, avoiding the cost of transporting leachate off

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1995.tb00508.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY