Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods
(2023) In Water Resources Research 59(8).- Abstract
A new methodology was developed to support contaminant mass discharge (CMD)-based risk assessment of groundwater contamination downgradient of point source zones. Geoelectrical cross-borehole induced polarization (IP) data were collected at a site undergoing in situ remediation of chlorinated solvents for determining 2D hydraulic conductivity (K) distributions with an inversion model resolution of 0.15 m (vertically) x 0.50 m (horizontally) in three control planes from 10 to 20 m depth. Additionally, 18 slug tests and 31 grain size distribution analyses (GSA) from the control planes, were used for K-estimation. The geometric means and variance of the IP, slug test, and GSA derived K-estimates were consistent with previously studied... (More)
A new methodology was developed to support contaminant mass discharge (CMD)-based risk assessment of groundwater contamination downgradient of point source zones. Geoelectrical cross-borehole induced polarization (IP) data were collected at a site undergoing in situ remediation of chlorinated solvents for determining 2D hydraulic conductivity (K) distributions with an inversion model resolution of 0.15 m (vertically) x 0.50 m (horizontally) in three control planes from 10 to 20 m depth. Additionally, 18 slug tests and 31 grain size distribution analyses (GSA) from the control planes, were used for K-estimation. The geometric means and variance of the IP, slug test, and GSA derived K-estimates were consistent with previously studied sandy aquifers. Furthermore, the vertical variation in K between two geological settings, a sandy till and a meltwater sand formation, was clearly identified by the IP K-estimates. The vertical variation was backed up by hydraulic profiling tool (HPT) measurements. Random realizations of CMD were simulated based on the cross-borehole IP derived K-values. For comparison, the CMD was also estimated with a geostatistical conditional simulation approach, using the data from slug tests and GSAs. The high IP resolution captured the small scale variations in K across the transects and led to CMD predictions with a narrow uncertainty interval, whereas slug test and GSA either under- or overestimated the magnitude of the areas with the highest CMD. Applying the geophysical cross-borehole method for estimating K-distributions in addition to traditional methods would improve CMD-based risk assessment and evaluation of remediation performance at contaminated sites.
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- author
- Thalund-Hansen, Rasmus ; Troldborg, Mads ; Levy, Léa LU ; Christiansen, Anders Vest ; Bording, Thue S. and Bjerg, Poul L.
- organization
- publishing date
- 2023-08
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- contaminant mass discharge, cross-borehole DCIP, hydraulic conductivity, hydrogeophysics
- in
- Water Resources Research
- volume
- 59
- issue
- 8
- article number
- e2022WR034360
- pages
- 17 pages
- publisher
- American Geophysical Union (AGU)
- external identifiers
-
- scopus:85168413144
- ISSN
- 0043-1397
- DOI
- 10.1029/2022WR034360
- language
- English
- LU publication?
- yes
- additional info
- Funding Information: Funding for this project was provided by Advokat Bent Thorbergs Fond, the Capital Region of Denmark, and DTU Sustain at the Technical University of Denmark. Thanks to Nina Tuxen and Maria Hag from the Capital Region of Denmark for facilitating this study, to the Hydrogeophysics Group of Aarhus University and to Kirsten Rügge, and Morten Dreyer, COWI, for a productive collaboration. Thanks to our former DTU colleagues Bent H. Skov for assisting with field work and Sinh Hy Nguyen for laboratory assistance. And thanks to Anton Bo Bøllingtoft for good discussions and useful input at the office. Funding Information: Funding for this project was provided by Advokat Bent Thorbergs Fond, the Capital Region of Denmark, and DTU Sustain at the Technical University of Denmark. Thanks to Nina Tuxen and Maria Hag from the Capital Region of Denmark for facilitating this study, to the Hydrogeophysics Group of Aarhus University and to Kirsten Rügge, and Morten Dreyer, COWI, for a productive collaboration. Thanks to our former DTU colleagues Bent H. Skov for assisting with field work and Sinh Hy Nguyen for laboratory assistance. And thanks to Anton Bo Bøllingtoft for good discussions and useful input at the office. Publisher Copyright: © 2023. The Authors.
- id
- e5a5b865-4ad5-43a6-a726-02328fb4433a
- date added to LUP
- 2023-08-31 11:11:10
- date last changed
- 2023-11-08 10:28:24
@article{e5a5b865-4ad5-43a6-a726-02328fb4433a,
abstract = {{<p>A new methodology was developed to support contaminant mass discharge (CMD)-based risk assessment of groundwater contamination downgradient of point source zones. Geoelectrical cross-borehole induced polarization (IP) data were collected at a site undergoing in situ remediation of chlorinated solvents for determining 2D hydraulic conductivity (K) distributions with an inversion model resolution of 0.15 m (vertically) x 0.50 m (horizontally) in three control planes from 10 to 20 m depth. Additionally, 18 slug tests and 31 grain size distribution analyses (GSA) from the control planes, were used for K-estimation. The geometric means and variance of the IP, slug test, and GSA derived K-estimates were consistent with previously studied sandy aquifers. Furthermore, the vertical variation in K between two geological settings, a sandy till and a meltwater sand formation, was clearly identified by the IP K-estimates. The vertical variation was backed up by hydraulic profiling tool (HPT) measurements. Random realizations of CMD were simulated based on the cross-borehole IP derived K-values. For comparison, the CMD was also estimated with a geostatistical conditional simulation approach, using the data from slug tests and GSAs. The high IP resolution captured the small scale variations in K across the transects and led to CMD predictions with a narrow uncertainty interval, whereas slug test and GSA either under- or overestimated the magnitude of the areas with the highest CMD. Applying the geophysical cross-borehole method for estimating K-distributions in addition to traditional methods would improve CMD-based risk assessment and evaluation of remediation performance at contaminated sites.</p>}},
author = {{Thalund-Hansen, Rasmus and Troldborg, Mads and Levy, Léa and Christiansen, Anders Vest and Bording, Thue S. and Bjerg, Poul L.}},
issn = {{0043-1397}},
keywords = {{contaminant mass discharge; cross-borehole DCIP; hydraulic conductivity; hydrogeophysics}},
language = {{eng}},
number = {{8}},
publisher = {{American Geophysical Union (AGU)}},
series = {{Water Resources Research}},
title = {{Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods}},
url = {{http://dx.doi.org/10.1029/2022WR034360}},
doi = {{10.1029/2022WR034360}},
volume = {{59}},
year = {{2023}},
}