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Remediation of Residual NAPL from Aquifers by Permeability Modification: A Review

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  037032,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14235) @2003
Authors:   Neil John D’Cunha, Debasmita Misra, David L. Barnes, Gang Chen
Keywords:   Remediation, NAPL, Permeability Modification, Biopolymers, Cold regions

Organics become trapped as non-aqueous phase liquids (NAPL) in the subsurface matrix and serve as a source for continuous dissolution of contamination. Organics can remain in significant quantities as residual contaminants even after the bulk phase has been removed. A combination of the aquifer properties and the characteristics of the drive fluid are responsible for these conditions. As the drive fluid sweeps through the aquifer it follows the path of least resistance, which is the high permeability zone. Thus the contaminants trapped in the low permeability zones remain as residuals and serve as a source for prolonged contamination. In this paper, we will present a review of the various techniques that are employed for remediation of residual contaminants.

Various methods of aquifer remediation are well documented. They can be divided into various combinations of physical, chemical, and biological methods. Parameters that are taken into consideration in selection of a remediation method are subsurface characteristics, volume of contaminant, site-specific conditions and target level of cleanup desired.

Flow patterns of the drive fluid in the aquifer can be altered by blocking the high permeability zones. This could be accomplished using combinations of particulate, chemical and biological methods. We provide a review of such methods with particular focus on the use of biopolymer gelants and natural freezing of soils to modify the aquifer permeability for effective remediation of residual NAPL.

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