A Graphical Approach for Determining Dilution-Attenuation Factors: Basic Theory and Approach for Submerged Sources |
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| Authors: | David Abrano ic Paul C Johnson Randall J Charbeneau Timothy J Hemstreet |
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| Institution: | David Abranovic;recei ed a B.S. in hydrogeology from Northern Arizona Uni ersity in 1986 and a M.S. in en ironmental engineering from Arizona State Uni ersity in 1996. He is currently working as a senior remediation engineer for En ironmental Resources Management in Scottsdale, Arizona. Paul C. Johnson, Ph.D.;, is an associate professor in the Department of Ci il and En ironmental Engineering at Arizona State Uni ersity. Prior to that he was a senior research engineer at Shell De elopment Company's Westhollow Technology Center. His research and teaching currently focuses on the de elopment and optimization of in situ remediation technologies for fuel-oxygenage treatment and the de, elopment of models for riskbased decision making. Randall J. Charbeneau, Ph.D.;is the associate dean for research and the Jewel McAlister Smith professor in engineering in the Department of ci il Engineering at the Uni ersity of Texas, Austin. Dr. Charbeneau's research and teaching interests include ground water hydrology, subsurface fate and transport of hazardous and radioacti e wastes, ground water pollution, does and risk assessment, multiphase flow, and mathematical modeling. A biographical sketch for Timothy J. Hemstreet;was not pro ided. |
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| Abstract: | The dilution attenuation factor (DAF) is a quantity used to relate the concentration of leachate leaving a source zone (e.g., landfill, impoundment, or contaminated soils) to its impact on down-gradient ground water quality. The DAF is of importance because it plays a key role in U.S. Environmental Protection Agency (EPA)'s methodologies for developing soil cleanup goals and for managing hazardous wastes. In this work, a simplistic graphically-based approach for determining site-specific and generic DAFs was developed. In this case the DAF is based on time-and vertically-averaged concentrations along the plume centerline, and the mathematical framework employs well-known analytical and semianalytical solutions for dissolved contaminant transport. Finite sources with a range of decay characteristics are allowed for. One unique feature of this work is that the graphical approach allows for varying levels of sitespecificity, and thus can be used when one has a little, or a lot, of site-specific information. The graphs visually indicate the sensitivity to various parameters, which is valuable information not easily gleaned from most numerical software simulators. This approach is, however, not applicable to very complex hydrogeologic settings (e.g., fractured geology), or to ground water flows that cannot be reasonably approximated as one-dimensional. |
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