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In Situ Vertical Circulation Column: Containment System for Small-Scale DNAPL Field Experiments |
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| Authors: | Dominique Sorel John A. Cherry Suzanne Lesage |
| Affiliation: | Dominique Sorel;has recently joined Geomatrix Consultants as a staff hydrogeologist. She holds a B.A.Sc. in civil engineering from the Universitéde Sherbrooke and an M.Sc. in hydrogeology from the University of Waterloo. Her interests include in situ treatments for ground water rehabilitation, behavior of DNAPLs in the subsurface, hydraulic, geochemical, and biological limitations, and controls on remediation techniques. John A. Cherry;has degrees in geological engineering and hydrogeology and, since 1971, has been a professor at the University of Waterloo where he is a member of the Waterloo Centre for Groundwater Research. For the past 25 years, his research has focused on processes and monitoring of ground water contamination and on design and implementation of controlled field experiments for various purposes. Suzanne Lesage;is research scientist in the Groundwater Remediation Project at the National Water Research Institute of Environment Canada in Burlington, Ontario, and an adjunct professor in the Department of Earth Sciences at the University of Waterloo. She has more than 15 years experience in investigating the fate of organic contaminants in ground water, soils, and landfill leachates. Her current research interest is on the use of natural substances in remediation. The projects include the remediation of chlorinated solvents using vitamin B |
| Abstract: | The in situ vertical circulation column (ISVCC) is a cylindrical containment system consisting of an instrumented steel cylinder used for experimental ground water studies in sandy aquifers. Vertical flow is imposed inside the ISVCC. Although vertical wells are an option, the ISVCC installed in the Borden Aquifer is instrumented with horizontal wells and monitoring ports to avoid creating vertical preferential flow paths. The cylinder was driven downward into the aquifer using a small backhoe equipped with a vibrating plate. The ISVCC penetrates the 2.3-m-thic sand aquifer and is keyed 20 cm into the underlying clay aquitard. The cylinder was installed inside a 2 m X 2 m steel sheet pile enclosure so that the enclosed segment of aquifer could be conveniently dewatered and then excavated to allow installation of the horizontal wells. The dispersivity of the column was comparable to literature values for long sand-packed laboratory columns. Pure phase DNAPL (tetrachloroethene and 1,1,1-trichloroethane) was slowly pumped into two ports in the center of the column. Following this DNAPL injection, an aqueous solution of vitamin B The ISVCC provides a convenient means for testing in situ technologies in the experimental stage or for selection of proven technologies to find the most effective at a specific site. It is inexpensive, easy to install, and maximizes control over flow distribution in a heterogeneous aquifer. Its application will be restricted where low hydraulic conductivity beds are present in the aquifer. |
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