Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring

Léa Lévy; Thue S. Bording; Gianluca Fiandaca; Anders Vest Christiansen; Line M. Madsen; Lars F. Bennedsen; Torben Højbjerg Jørgensen; Leah MacKinnon; Jørgen F. Christensen

doi:10.1016/j.scitotenv.2024.171013

Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring

Léa Lévy^*, Thue S. Bording, Gianluca Fiandaca, Anders Vest Christiansen, Line M. Madsen, Lars F. Bennedsen, Torben Højbjerg Jørgensen, Leah MacKinnon, Jørgen F. Christensen

^*Corresponding author for this work

Department of Geoscience

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

2 Citations (Scopus)

Abstract

Groundwater contamination is a threat to drinking water resources and ecosystems. Remediation by injection of chemical reagents into the aquifer may be preferred to excavation to reduce cost and environmental footprint. Yet, successful remediation requires complete contact between contamination and reagents. Subsurface heterogeneities are often responsible for diffusion into low-permeable zones, which may inhibit this contact. Monitoring the spatial distribution of injected reagents over time is crucial to achieve complete interaction. Source zone contamination at megasites is particularly challenging to remediate and monitor due to the massive scale and mixture of contaminants. Source zone remediation at Kærgård Plantation megasite (Denmark) is monitored here, with a new methodology, using high-resolution cross-borehole electrical resistivity tomography (XB-ERT) imaging calibrated by chemical analyses on groundwater samples. At this site, high levels of toxic non-aqueous phase liquids (NAPL) are targeted by in-situ chemical oxidation using activated persulfate. It may take numerous injection points with extensive injection campaigns to distribute reagents, which requires an understanding of how reagent may transport within the aquifer. A geophysical (XB-ERT) monitoring network of unprecedented size was installed to identify untreated zones and help manage the remediation strategy. The combination of spatially continuous geophysical information with discrete but precise chemical information, allowed detailed monitoring of sulfate distribution, produced during persulfate activation. Untreated zones identified in the first remediation campaign were resolved in the second campaign. The monitoring allowed adjusting the number of injection screens and the injection strategy from one campaign to the next, which resulted in better persulfate distribution and contaminant degradation in the second campaign. Furthermore, geophysical transects repeated over the timespan of a remediation campaign allowed high-resolution time-lapse imaging of reagent transport, which could in the future improve the predictability of transport models, compared to only using on a-priori assumptions of the hydraulic conductivity field.

Original language	English
Article number	171013
Journal	Science of the Total Environment
Volume	920
ISSN	0048-9697
DOIs	https://doi.org/10.1016/j.scitotenv.2024.171013
Publication status	Published - 10 Apr 2024

Keywords

Chemical oxidation
Cross-borehole
Electrical resistivity
Groundwater remediation
Persulfate

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10.1016/j.scitotenv.2024.171013

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Lévy, L., Bording, T. S., Fiandaca, G., Christiansen, A. V., Madsen, L. M., Bennedsen, L. F., Jørgensen, T. H., MacKinnon, L., & Christensen, J. F. (2024). Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring. Science of the Total Environment, 920, Article 171013. https://doi.org/10.1016/j.scitotenv.2024.171013

@article{5c873cae1e5540069d98baa8bdb57d85,

title = "Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring",

abstract = "Groundwater contamination is a threat to drinking water resources and ecosystems. Remediation by injection of chemical reagents into the aquifer may be preferred to excavation to reduce cost and environmental footprint. Yet, successful remediation requires complete contact between contamination and reagents. Subsurface heterogeneities are often responsible for diffusion into low-permeable zones, which may inhibit this contact. Monitoring the spatial distribution of injected reagents over time is crucial to achieve complete interaction. Source zone contamination at megasites is particularly challenging to remediate and monitor due to the massive scale and mixture of contaminants. Source zone remediation at K{\ae}rg{\aa}rd Plantation megasite (Denmark) is monitored here, with a new methodology, using high-resolution cross-borehole electrical resistivity tomography (XB-ERT) imaging calibrated by chemical analyses on groundwater samples. At this site, high levels of toxic non-aqueous phase liquids (NAPL) are targeted by in-situ chemical oxidation using activated persulfate. It may take numerous injection points with extensive injection campaigns to distribute reagents, which requires an understanding of how reagent may transport within the aquifer. A geophysical (XB-ERT) monitoring network of unprecedented size was installed to identify untreated zones and help manage the remediation strategy. The combination of spatially continuous geophysical information with discrete but precise chemical information, allowed detailed monitoring of sulfate distribution, produced during persulfate activation. Untreated zones identified in the first remediation campaign were resolved in the second campaign. The monitoring allowed adjusting the number of injection screens and the injection strategy from one campaign to the next, which resulted in better persulfate distribution and contaminant degradation in the second campaign. Furthermore, geophysical transects repeated over the timespan of a remediation campaign allowed high-resolution time-lapse imaging of reagent transport, which could in the future improve the predictability of transport models, compared to only using on a-priori assumptions of the hydraulic conductivity field.",

keywords = "Chemical oxidation, Cross-borehole, Electrical resistivity, Groundwater remediation, Persulfate",

author = "L{\'e}a L{\'e}vy and Bording, {Thue S.} and Gianluca Fiandaca and Christiansen, {Anders Vest} and Madsen, {Line M.} and Bennedsen, {Lars F.} and J{\o}rgensen, {Torben H{\o}jbjerg} and Leah MacKinnon and Christensen, {J{\o}rgen F.}",

note = "Publisher Copyright: {\textcopyright} 2024 The Authors",

year = "2024",

month = apr,

day = "10",

doi = "10.1016/j.scitotenv.2024.171013",

language = "English",

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Lévy, L, Bording, TS, Fiandaca, G, Christiansen, AV , Madsen, LM, Bennedsen, LF, Jørgensen, TH, MacKinnon, L & Christensen, JF 2024, 'Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring', Science of the Total Environment, vol. 920, 171013. https://doi.org/10.1016/j.scitotenv.2024.171013

Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring. / Lévy, Léa; Bording, Thue S.; Fiandaca, Gianluca et al.
In: Science of the Total Environment, Vol. 920, 171013, 10.04.2024.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring

AU - Lévy, Léa

AU - Bording, Thue S.

AU - Fiandaca, Gianluca

AU - Christiansen, Anders Vest

AU - Madsen, Line M.

AU - Bennedsen, Lars F.

AU - Jørgensen, Torben Højbjerg

AU - MacKinnon, Leah

AU - Christensen, Jørgen F.

PY - 2024/4/10

Y1 - 2024/4/10

N2 - Groundwater contamination is a threat to drinking water resources and ecosystems. Remediation by injection of chemical reagents into the aquifer may be preferred to excavation to reduce cost and environmental footprint. Yet, successful remediation requires complete contact between contamination and reagents. Subsurface heterogeneities are often responsible for diffusion into low-permeable zones, which may inhibit this contact. Monitoring the spatial distribution of injected reagents over time is crucial to achieve complete interaction. Source zone contamination at megasites is particularly challenging to remediate and monitor due to the massive scale and mixture of contaminants. Source zone remediation at Kærgård Plantation megasite (Denmark) is monitored here, with a new methodology, using high-resolution cross-borehole electrical resistivity tomography (XB-ERT) imaging calibrated by chemical analyses on groundwater samples. At this site, high levels of toxic non-aqueous phase liquids (NAPL) are targeted by in-situ chemical oxidation using activated persulfate. It may take numerous injection points with extensive injection campaigns to distribute reagents, which requires an understanding of how reagent may transport within the aquifer. A geophysical (XB-ERT) monitoring network of unprecedented size was installed to identify untreated zones and help manage the remediation strategy. The combination of spatially continuous geophysical information with discrete but precise chemical information, allowed detailed monitoring of sulfate distribution, produced during persulfate activation. Untreated zones identified in the first remediation campaign were resolved in the second campaign. The monitoring allowed adjusting the number of injection screens and the injection strategy from one campaign to the next, which resulted in better persulfate distribution and contaminant degradation in the second campaign. Furthermore, geophysical transects repeated over the timespan of a remediation campaign allowed high-resolution time-lapse imaging of reagent transport, which could in the future improve the predictability of transport models, compared to only using on a-priori assumptions of the hydraulic conductivity field.

AB - Groundwater contamination is a threat to drinking water resources and ecosystems. Remediation by injection of chemical reagents into the aquifer may be preferred to excavation to reduce cost and environmental footprint. Yet, successful remediation requires complete contact between contamination and reagents. Subsurface heterogeneities are often responsible for diffusion into low-permeable zones, which may inhibit this contact. Monitoring the spatial distribution of injected reagents over time is crucial to achieve complete interaction. Source zone contamination at megasites is particularly challenging to remediate and monitor due to the massive scale and mixture of contaminants. Source zone remediation at Kærgård Plantation megasite (Denmark) is monitored here, with a new methodology, using high-resolution cross-borehole electrical resistivity tomography (XB-ERT) imaging calibrated by chemical analyses on groundwater samples. At this site, high levels of toxic non-aqueous phase liquids (NAPL) are targeted by in-situ chemical oxidation using activated persulfate. It may take numerous injection points with extensive injection campaigns to distribute reagents, which requires an understanding of how reagent may transport within the aquifer. A geophysical (XB-ERT) monitoring network of unprecedented size was installed to identify untreated zones and help manage the remediation strategy. The combination of spatially continuous geophysical information with discrete but precise chemical information, allowed detailed monitoring of sulfate distribution, produced during persulfate activation. Untreated zones identified in the first remediation campaign were resolved in the second campaign. The monitoring allowed adjusting the number of injection screens and the injection strategy from one campaign to the next, which resulted in better persulfate distribution and contaminant degradation in the second campaign. Furthermore, geophysical transects repeated over the timespan of a remediation campaign allowed high-resolution time-lapse imaging of reagent transport, which could in the future improve the predictability of transport models, compared to only using on a-priori assumptions of the hydraulic conductivity field.

KW - Chemical oxidation

KW - Cross-borehole

KW - Electrical resistivity

KW - Groundwater remediation

KW - Persulfate

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U2 - 10.1016/j.scitotenv.2024.171013

DO - 10.1016/j.scitotenv.2024.171013

M3 - Journal article

C2 - 38369154

AN - SCOPUS:85185406115

SN - 0048-9697

VL - 920

JO - Science of the Total Environment

JF - Science of the Total Environment

M1 - 171013

ER -

Managing the remediation strategy of contaminated megasites using field-scale calibration of geo-electrical imaging with chemical monitoring

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Keywords

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