Source zone remediation by ZVI-clay soil-mixing: Reduction of tetrachloroethene mass and mass discharge at a Danish DNAPL site

Annika Sidelmann Fjordbøge, Ida Vedel Lange, Philip John Binning, Poul Løgstrup Bjerg, Charlotte Riis, Anders G. Christensen, Mads Terkelsen, Peter Kjeldsen

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Abstract

The presence of chlorinated solvent source zones in the subsurface pose a continuous threat to groundwater quality. The remediation of Dense Non-Aqueous Phase Liquid (DNAPL) sites is especially challenging and the development of innovative remediation technologies is needed. Zero-valent iron (ZVI) technologies have proven effective for remediation of chlorinated compounds. ZVI-Clay soil-mixing is a new remediation technology, which combines abiotic degradation (via ZVI addition) and immobilization (via soil-mixing and clay addition), whereby a great potential for reduction of both contaminant mass and mass discharge is obtained.
The technology was tested at a Danish DNAPL site, where the secondary aquifer was heavily contaminated by tetrachloroethene (PCE). ZVI-Clay soil-mixing was tested at a small source zone (~200 m3) with soil concentrations ranging up to 12,000 mg/kg. The objective of the field test was to document in situ destruction of the contaminant mass and the down-gradient response in contaminant mass discharge.
The field sampling consisted of baseline measurements and a 19-month monitoring program (7 sampling campaigns) subsequent to the implementation of ZVI-Clay soil mixing. The concentrations of chlorinated ethenes were monitored via soil sampling at the source zone and groundwater sampling at a control plane with multilevel samplers covering the entire contaminated plume down-gradient (3 m) of the source zone.
The results showed a significant mass depletion of PCE (2-3 orders in magnitude) with ethene as the main degradation product. The down-gradient reduction of contaminant mass discharge occurred more slowly; after 19 months a mass discharge reduction of 76 % was obtained for PCE. However, due to a temporary increase in cis-DCE, the overall down-gradient reduction of all the chlorinated ethenes was limited to 21 %. Long-term modeling (Comsol Multiphysics) was used to predict that a contaminant mass discharge reduction of 2-3 orders in magnitude will take 3-5 years.
Original languageEnglish
Title of host publicationThe 2012 World Congress on Advances in Civil, Environmental, and Materials Research (ACEM´12) : Volume of Abstracts
EditorsChang-Koon Choi
Publication date2012
Pages346
ISBN (Print)978-89-89693-34-5-98530
Publication statusPublished - 2012
EventWorld Congress on Advances in Civil, Environmental, and Materials Research (ACEM’12) - Seoul, Korea, Republic of
Duration: 26 Aug 201230 Aug 2012
http://acem12.cti3.com/

Conference

ConferenceWorld Congress on Advances in Civil, Environmental, and Materials Research (ACEM’12)
CountryKorea, Republic of
CitySeoul
Period26/08/201230/08/2012
Internet address

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