Download or read book Uncertainty Analyses of a Vadose Zone Transport Model for Soil Remediation Criteria of Volatile Organic Compounds written by Yue Rong and published by . This book was released on 1995 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mass Transport of Volatile Organic Compounds Between the Saturated and Vadose Zones written by Monte S. Harner and published by . This book was released on 1996-12-01 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volatile organic compounds (VOCs) dissolved in the saturated zone are transported into the vadose zone primarily by gaseous phase diffusion. If the saturated zone is remediated, VOCs present in the vadose zone may become a secondary source of contamination for the groundwater The amount of VOCs that remain in the vadose zone is dependent on site hydrology, soil properties, and the chemical properties of the contaminants. The purpose of this study was to determine what conditions caused VOC concentrations in the vadose zone to significantly recontaminate the saturated zone. A one-dimensional numerical model was developed to investigate the transport of a VOC, trichioroethylene, between the saturated and vadose zones under a variety of conditions. The model featured steady-state unsaturated water flow and transient contaminant transport Transport mechanisms included aqueous phase advection-dispersion and gaseous phase diffusion. Partitioning between the water, gas, and soil compartments were modeled as equilibrium processes. Sensitivity analyses were performed on several variables including soil type (homogeneous and heterogeneous profiles), water infiltration rate and vadose zone depth. Results indicated that recontamination was most significant rate, and vadose zone depth. Results indicated that recontamination was most significant in the presence of heterogeneous soils, low infiltration rates and deep vadose zones.

Download or read book Introduction to Environmental Forensics written by Brian L. Murphy and published by Elsevier. This book was released on 2007-05-01 with total page 821 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Environmental Forensics helps readers unravel the complexities of environmental pollution cases. It outlines techniques for identifying the source of a contaminant release, when the release occurred, and the extent of human exposure. Written by leading experts in environmental investigations, the text provides detailed information on chemical "fingerprinting" techniques applicable to ground water, soils, sediments, and air, plus an in-depth look at petroleum hydrocarbons. It gives the environmental scientist, engineer, and legal specialist a complete toolbox for conducting forensic investigations. It demonstrates the range of scientific analyses that are available to answer questions of environmental liability and support a legal argument, and provides several examples and case studies to illustrate how these methods are applied. This is a textbook that would prove useful to a range of disciplines, including environmental scientists involved in water and air pollution, contaminated land and geographical information systems; and archaeologists, hydrochemists and geochemists interested in dating sources of pollution. Co-edited by one of the experts from the Civil Action case in Woburn, MA Provides essential information about identifying environmental contaminants responsible for millions of deaths per year Contains the latest information and coverage of issues crucial to both forensics investigators and environmental scientists

Download or read book Estimation of Volatile Organic Compound Concentrations in the Vadose Zone written by RK. Sextro and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Obtaining defensible and conservative estimates of the nature, extent and concentration of volatile organic compounds (VOCs) in the vadose zone is extremely important when formulating the conceptual model of the site, when performing risk assessments, for estimating contaminant mass, for assessing remedial alternatives, for selecting target areas for cleanup, and/or for making no further action/investigation decisions. Studies have shown that soil gas analytical results provide both a more complete indication of the VOCs present and a higher estimate of their respective concentrations in the vadose zone than the analysis of soil samples alone. For the past several years deep downhole (to 30+ meters) soil gas sampling and analysis has been performed by various consultants during remedial investigations (RIs) and remedial actions (RAs) of the vadose zone at McClellan Air Force Base. A number of these soil gas results have been confirmed by the concurrent collection and analysis (for VOCs) of soil samples (preserved by either refrigeration to 4 degrees centigrade or refrigeration combined with methanol preservation). The use of this VOC sampling and analysis strategy has resulted in the optimization of VOC sampling and analysis procedures, in a better understanding of the relationship between the concentration of VOCs in soil gas and in the soil, and in a more accurate and comprehensive conceptual model for VOC contamination in the vadose zone. The paper will present the methodologies used by the various consultants for sample collection, preservation, and in the analysis of soil gas and soil samples, present the results of a focused QC study on soil gas sampling and analysis, and discuss the correlation between the soil gas and soil matrix analytical results. The current and future strategies for the sampling, analysis, and estimation of VOCs in the vadose zone during RIs and RAs will also be presented.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1996 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Vadose Zone Characterization Monitoring written by L. Gray Wilson and published by Routledge. This book was released on 2018-05-02 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is written in a simple, straightforward manner without complicated mathematical derivatives. Compiled by experienced practitioners, this guide covers topics such as basic principles of vadose zone hydrology and prevalent monitoring techniques. Case studies present actual field experiences for the benefit of the reader. The Handbook provides practitioners with the information they need to fully understand the principles, advantages, and limitations of the monitoring techniques that are available. The Handbook of Vadose Zone Characterization & Monitoring expands and consolidates the useful and succint information contained in various ASTM documents, EPA manuals, and other similar texts on the subject, making it an invaluable aid to new practioners and a useful reference for seasoned veterans in the field.

Download or read book Petroleum Abstracts written by and published by . This book was released on 1997 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 962 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantifying Vadose Zone Flow and Transport Uncertainties Using a Unified Hierarchical Approach written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to develop and demonstrate a general approach for modeling flow and transport in the heterogeneous vadose zone. The approach uses similar media scaling, geostatistics, and conditional simulation methods to estimate soil hydraulic parameters at unsampled locations from field-measured water content data and scale-mean hydraulic parameters determined from available site characterization data. Neural network methods are being developed to estimate soil hydraulic parameters from more easily measured physical property data such as bulk density, organic matter content, and percentages of sand, silt, and clay (or particle-size distributions). Field water content distributions are being estimated using various geophysical methods including neutron moderation, ground-penetrating radar, and electrical resistance tomography. One of the primary goals of this research is to determine relationships between the type of data used in model parameterization, th e quantity of data available, the scale of the measurement, and the uncertainty in predictions of flow and transport using these methods. Evaluation of the relationships between available data, scale, and uncertainty will use primarily existing data from large-scale, controlled experiments.

Download or read book Identification and Compilation of Unsaturated vadose Zone Models written by Paul Van der Heijde and published by . This book was released on 1994 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book EPA Publications Bibliography written by United States. Environmental Protection Agency and published by . This book was released on 1991 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vadose Zone Contamination Measurement and Modeling written by and published by . This book was released on 1993 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigated the effects of the slow sorption mechanism on the transport of volatile organic contaminants in the vadose zone. Recent research has shown that slow sorption may have a significant impact on the transport of volatile organic compounds in the subsurface. Specifically, this document examined the effects of slow sorption on the Vapor Extraction System (VES) and the Purge and Trap Measurement System. It was found that the slow sorption of organic molecules on soil may profoundly influence the efficiency of VES and purge and trap. In addition, this thesis investigated possible alternatives to purge and trap, including the utilization of lasers and optoelectronics. Mathematical simulation and modeling of slow sorption effects during vapor extraction operations was accomplished with the use of the Soil Vapor Extraction (SVE) Computer Model.

Download or read book Index to Graduate Theses and Dissertations on California Geology 1990 Through 1997 written by and published by . This book was released on 1998 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 1424 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Parameter Importance of an Analytical Model for Transport in the Vadose Zone written by Tanner Hans Bushnell and published by . This book was released on 2007 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The American Society of Testing and Materials (ASTM) has established a three tier risk-based corrective action (RBCA) program for cleaning up petroleum release sites, which is supported by the Environmental Protection Agency. RBCA programs make the cleanup of spill sites more efficient by requiring additional site information only when a more accurate risk assessment is needed. For spill sites that do not pass the first tier general assessment, a Tier 2 evaluation involving site specific information and screening level models to assess the potential risk must be conducted. Screening level models generally require site specific input parameters. To increase efficiency it would be helpful to know which parameters have large affects on model output and which parameters do not affect the model output significantly. There have been many studies focused on model sensitivity to input parameters. For an input parameter to vary there must be uncertainty about the value. This research proposes a method of including parameter uncertainty with model sensitivity to quantify the importance of a parameter, where the term importance is a combination of parameter uncertainty and sensitivity. Using the method developed in this thesis, an importance assessment was conducted on an analytical model for vadose zone transport. It was found that for sites posing high risk, with large spill volumes and shallow water table depths, the input parameters of water table depth and spill volume were the most important. The input parameters of precipitation and contaminant biodegradation half-life showed high importance in lower risk situations; when the water table was deep. A comparison of sensitivity analysis to importance showed differences in their results. The sensitivity analysis identified those parameters that the model was sensitive to, while the importance assessment identified the parameters that were sensitive and whose range of uncertainty was large enough to affect model output values. This information could be used for resource allocation decisions when acquiring additional site specific information.

Download or read book Modeling the Transport of Volatile Organic Chemicals in Variably Saturated Subsurface Regions written by Teresa Birnbaum Culver and published by . This book was released on 1989 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: