Modeling Of In Situ Techniques For Treatment Of Contaminated Soils PDF Download

From the Preface Soil vapor extraction within the last few years has gone from being an innovative, relatively untried technology which was viewed with some distrust, to being one of the most reliable, accepted, and cost-effective of the techniques available for the remediation of hazardous waste sites. As with most of the in situ techniques, its use is restricted; the compounds to be removed must have vapor pressures and Henry's constants that are sufficiently large; SVE is effective for removing only those VOCs that are in the vadose zone or floating on the water table, and the soil at the site must be sufficiently permeable that one can move air through all of the domain to be treated by SVE. The design of optimal, cost-effective SVE installations tends to be highly site-specific, and often at complex sites the technique is deployed in concert with such other technologies as pump-and-treat, in situ air sparging, and fixation/stabilization. SVE may also be operated in such a manner as to optimize the extent to which biodegradation of contaminants occurs, a technique that is called bioventing or bio-assisted SVE, a quite new technology addressed in this book. Recently, another aeration technique has been developed_in situ air sparging; this is for use in the remediation of aquifers contaminated with VOCs. Virtually all of the points raised above with regard to SVE are also applicable to ISAS. The technique, being newer than SVE, has not yet achieved the wide degree of acceptance that SVE now enjoys, but ISAS has already achieved a number of successes, has a sound basis in science and engineering, has very little environmental impact, and is applicable to situations for which no other technology has proven cost-effective. It is evident that universal acceptance of this technology will be achieved in the near future. In this book about these techniques, we hope to serve the needs of three groups of readers. First, we have attempted to provide sufficient information on SVE and ISAS to give managers and regulators who may not be familiar with these remediation methods a clear idea of their ranges of applicability. Secondly, we have tried to meet the needs of those engineers who are not experts in the fields of SVE and ISAS, but whose work requires that they read proposals, reports, recommendations, etc., involving the technique with some degree of critical understanding. Thirdly, we have tried to provide a detailed discussion of SVE and ISAS, complete with all the mathematical nuts and bolts, for the environmental engineer whose work is involved with the selection, preliminary planning, design, construction, and operation of SVE and/or ISAS facilities and who may have to use or even to develop computer software in connection with these tasks. The book places heavy emphasis on mathematical modeling, and we believe that there is much to be gained by thoughtful modeling exercises.