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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 www.asabe.org
Citation: Paper number 037032, 2003 ASAE Annual Meeting . (doi: 10.13031/2013.14235) @2003Authors: 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.