Fjordbøge, Annika Sidelmann2; Lange, Ida Vedel2; Binning, Philip John2; Bjerg, Poul Løgstrup2; Riis, Charlotte6; Christensen, Anders G.6; Terkelsen, Mads5; Kjeldsen, Peter2
1 Water Resources Engineering, Department of Environmental Engineering, Technical University of Denmark2 Department of Environmental Engineering, Technical University of Denmark3 Residual Resource Engineering, Department of Environmental Engineering, Technical University of Denmark4 NIRAS A/S5 Capital Region of Denmark6 NIRAS A/S
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.
2012 World Congress on Advances in Civil, Environmental, and Materials Research (acem´12): Volume of Abstracts, 2012
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World Congress on Advances in Civil, Environmental, and Materials Research (ACEM’12), 2012