Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods

Rasmus Thalund-Hansen; Mads Troldborg; Léa Levy; Anders Vest Christiansen; Thue S. Bording; Poul L. Bjerg

doi:10.1029/2022WR034360

Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods

Rasmus Thalund-Hansen^*, Mads Troldborg, Léa Levy, Anders Vest Christiansen, Thue S. Bording, Poul L. Bjerg

^*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avis › Tidsskriftartikel › Forskning › peer review

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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 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.

Originalsprog	Engelsk
Artikelnummer	e2022WR034360
Tidsskrift	Water Resources Research
Vol/bind	59
Nummer	8
ISSN	0043-1397
DOI	https://doi.org/10.1029/2022WR034360
Status	Udgivet - aug. 2023

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10.1029/2022WR034360Licens: CC BY-NC-ND

Water Resources Research - 2023 - Thalund‐Hansen - Assessing Contaminant Mass Discharge Uncertainty With Application ofForlagets udgivne version, 5,03 MBLicens: CC BY-NC-ND

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Thalund-Hansen, R., Troldborg, M., Levy, L., Christiansen, A. V., Bording, T. S., & Bjerg, P. L. (2023). Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods. Water Resources Research, 59(8), Artikel e2022WR034360. https://doi.org/10.1029/2022WR034360

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title = "Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods",

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 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.",

keywords = "contaminant mass discharge, cross-borehole DCIP, hydraulic conductivity, hydrogeophysics",

author = "Rasmus Thalund-Hansen and Mads Troldborg and L{\'e}a Levy and Christiansen, {Anders Vest} and Bording, {Thue S.} and Bjerg, {Poul L.}",

note = "Publisher Copyright: {\textcopyright} 2023. The Authors.",

year = "2023",

month = aug,

doi = "10.1029/2022WR034360",

language = "English",

volume = "59",

journal = "Water Resources Research",

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Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods. / Thalund-Hansen, Rasmus; Troldborg, Mads; Levy, Léa et al.
I: Water Resources Research, Bind 59, Nr. 8, e2022WR034360, 08.2023.

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avis › Tidsskriftartikel › Forskning › peer review

TY - JOUR

T1 - Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods

AU - Thalund-Hansen, Rasmus

AU - Troldborg, Mads

AU - Levy, Léa

AU - Christiansen, Anders Vest

AU - Bording, Thue S.

AU - Bjerg, Poul L.

PY - 2023/8

Y1 - 2023/8

N2 - 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.

AB - 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.

KW - contaminant mass discharge

KW - cross-borehole DCIP

KW - hydraulic conductivity

KW - hydrogeophysics

U2 - 10.1029/2022WR034360

DO - 10.1029/2022WR034360

M3 - Journal article

AN - SCOPUS:85168413144

SN - 0043-1397

VL - 59

JO - Water Resources Research

JF - Water Resources Research

IS - 8

M1 - e2022WR034360

ER -

Assessing Contaminant Mass Discharge Uncertainty With Application of Hydraulic Conductivities Derived From Geoelectrical Cross-Borehole Induced Polarization and Other Methods

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