Secondary Effects of Soil Venting and Potential Low-Cost Enhancements |
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| Authors: | John C Walton Charles B Anker |
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| Institution: | John C. Walton is an assistant professor of civil engineering at the University of Texas at El Paso (El Paso, TX 79968-0516;e-mail: ). He has a B.S. degree in biology, an M.S. degree in environmental science, an M.S. degree in chemical engineering, and a Ph.D. in chemical engineering from the University of Idaho. His research interests are in the areas of ground water, nuclear waste disposal, remediation, solar energy, and materials degradation.;Charles B. Anker recently graduated from the University of Texas at El Paso with an M.S. degree in civil engineering. His M.S. thesis considered methods for enhancement of soil venting. Prior to returning to school for his graduate degree, Anker was a high school science teacher for four years. |
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| Abstract: | Soil venting, in addition to removing volatile organic compounds, has secondary effects on soil temprature and moisture content. A simple enthalpy balance model is used to illustrate the maganitude and direction of temperature and moisture content changes in the soil during ordinary venting and with several potential modifications to venting. Because of the importance of latent heat of vaporization, injection of warm, dry air into the substance is generally ineffective in heating the soil. In contrast, injection of humidified, slightly heated air is found to result in significant soil warming even at low flow rates. Soil warming is thought to be an important mechanism for enhancing remediation, particularly in the final or tail stage of cleanup where concentrations slowly decline wiht time. A variety of soil venting alternatives are simulated at hypothetical sites in Chicago, Illinois, and Tucson, Arizona, including simple humidification, humidification with solar heating, and venting under positive pressure. All there methods result in higher final soil temperatures than the control case of normal soil venting. Humidification of the input air at the rates applied does not result in significant change in average soil moisture content or saturation of the soil wtih water. |
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