Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer

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Abstract

Understanding the fate and transport of contaminants in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules. Several modeling approaches have been developed to describe contaminant transport in fractured media, such as discrete fracture, equivalent porous media, and dual continuum models. However, these modeling concepts are not well tested for real limestone geologies. Our goal is therefore to develop, evaluate and compare approaches for modeling transport of contaminants in fractured limestone aquifers.
The model comparison is conducted for a contaminated site in Denmark, where a plume of dissolved PCE has migrated through a fractured limestone aquifer. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology and hydrogeology. To describe the geology and fracture system, data from borehole logs and cores was combined with an analysis of heterogeneities and fractures from a nearby excavation and pump test data. We present how field data is integrated into the different model concepts. A challenge in the use of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias towards fracture sampling; however, concentrations in the limestone matrix are needed for assessing contaminant rebound and remediation strategies.
Each model is compared with field data, considering both model fit and model suitability. Results show a considerable difference between the approaches, and that it is important to select the right one for the actual modeling purpose. The comparison with data showed how much information is required to discriminate between models, and recommendations on how to identify the best modeling approach are made.
Original languageEnglish
Publication date2015
Number of pages1
Publication statusPublished - 2015
Event2015 NGWA Conference on Groundwater in Fractured Rock - Burlington, Vermont, United States
Duration: 28 Sep 201529 Sep 2015

Conference

Conference2015 NGWA Conference on Groundwater in Fractured Rock
CountryUnited States
CityBurlington, Vermont
Period28/09/201529/09/2015

Cite this

Mosthaf, K., Fjordbøge, A. S., Broholm, M. M., Bjerg, P. L., Rohde, M. M., Overheu, N. D., & Binning, P. J. (2015). Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer. Abstract from 2015 NGWA Conference on Groundwater in Fractured Rock, Burlington, Vermont, United States.
Mosthaf, Klaus ; Fjordbøge, Annika Sidelmann ; Broholm, Mette Martina ; Bjerg, Poul Løgstrup ; Rohde, Magnus Marius ; Overheu, Niels D. ; Binning, Philip John. / Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer. Abstract from 2015 NGWA Conference on Groundwater in Fractured Rock, Burlington, Vermont, United States.1 p.
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title = "Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer",
abstract = "Understanding the fate and transport of contaminants in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules. Several modeling approaches have been developed to describe contaminant transport in fractured media, such as discrete fracture, equivalent porous media, and dual continuum models. However, these modeling concepts are not well tested for real limestone geologies. Our goal is therefore to develop, evaluate and compare approaches for modeling transport of contaminants in fractured limestone aquifers. The model comparison is conducted for a contaminated site in Denmark, where a plume of dissolved PCE has migrated through a fractured limestone aquifer. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology and hydrogeology. To describe the geology and fracture system, data from borehole logs and cores was combined with an analysis of heterogeneities and fractures from a nearby excavation and pump test data. We present how field data is integrated into the different model concepts. A challenge in the use of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias towards fracture sampling; however, concentrations in the limestone matrix are needed for assessing contaminant rebound and remediation strategies. Each model is compared with field data, considering both model fit and model suitability. Results show a considerable difference between the approaches, and that it is important to select the right one for the actual modeling purpose. The comparison with data showed how much information is required to discriminate between models, and recommendations on how to identify the best modeling approach are made.",
author = "Klaus Mosthaf and Fjordb{\o}ge, {Annika Sidelmann} and Broholm, {Mette Martina} and Bjerg, {Poul L{\o}gstrup} and Rohde, {Magnus Marius} and Overheu, {Niels D.} and Binning, {Philip John}",
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note = "2015 NGWA Conference on Groundwater in Fractured Rock ; Conference date: 28-09-2015 Through 29-09-2015",

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Mosthaf, K, Fjordbøge, AS, Broholm, MM, Bjerg, PL, Rohde, MM, Overheu, ND & Binning, PJ 2015, 'Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer' 2015 NGWA Conference on Groundwater in Fractured Rock, Burlington, Vermont, United States, 28/09/2015 - 29/09/2015, .

Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer. / Mosthaf, Klaus; Fjordbøge, Annika Sidelmann; Broholm, Mette Martina; Bjerg, Poul Løgstrup; Rohde, Magnus Marius; Overheu, Niels D.; Binning, Philip John.

2015. Abstract from 2015 NGWA Conference on Groundwater in Fractured Rock, Burlington, Vermont, United States.

Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review

TY - ABST

T1 - Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer

AU - Mosthaf, Klaus

AU - Fjordbøge, Annika Sidelmann

AU - Broholm, Mette Martina

AU - Bjerg, Poul Løgstrup

AU - Rohde, Magnus Marius

AU - Overheu, Niels D.

AU - Binning, Philip John

PY - 2015

Y1 - 2015

N2 - Understanding the fate and transport of contaminants in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules. Several modeling approaches have been developed to describe contaminant transport in fractured media, such as discrete fracture, equivalent porous media, and dual continuum models. However, these modeling concepts are not well tested for real limestone geologies. Our goal is therefore to develop, evaluate and compare approaches for modeling transport of contaminants in fractured limestone aquifers. The model comparison is conducted for a contaminated site in Denmark, where a plume of dissolved PCE has migrated through a fractured limestone aquifer. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology and hydrogeology. To describe the geology and fracture system, data from borehole logs and cores was combined with an analysis of heterogeneities and fractures from a nearby excavation and pump test data. We present how field data is integrated into the different model concepts. A challenge in the use of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias towards fracture sampling; however, concentrations in the limestone matrix are needed for assessing contaminant rebound and remediation strategies. Each model is compared with field data, considering both model fit and model suitability. Results show a considerable difference between the approaches, and that it is important to select the right one for the actual modeling purpose. The comparison with data showed how much information is required to discriminate between models, and recommendations on how to identify the best modeling approach are made.

AB - Understanding the fate and transport of contaminants in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules. Several modeling approaches have been developed to describe contaminant transport in fractured media, such as discrete fracture, equivalent porous media, and dual continuum models. However, these modeling concepts are not well tested for real limestone geologies. Our goal is therefore to develop, evaluate and compare approaches for modeling transport of contaminants in fractured limestone aquifers. The model comparison is conducted for a contaminated site in Denmark, where a plume of dissolved PCE has migrated through a fractured limestone aquifer. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology and hydrogeology. To describe the geology and fracture system, data from borehole logs and cores was combined with an analysis of heterogeneities and fractures from a nearby excavation and pump test data. We present how field data is integrated into the different model concepts. A challenge in the use of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias towards fracture sampling; however, concentrations in the limestone matrix are needed for assessing contaminant rebound and remediation strategies. Each model is compared with field data, considering both model fit and model suitability. Results show a considerable difference between the approaches, and that it is important to select the right one for the actual modeling purpose. The comparison with data showed how much information is required to discriminate between models, and recommendations on how to identify the best modeling approach are made.

M3 - Conference abstract for conference

ER -

Mosthaf K, Fjordbøge AS, Broholm MM, Bjerg PL, Rohde MM, Overheu ND et al. Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer. 2015. Abstract from 2015 NGWA Conference on Groundwater in Fractured Rock, Burlington, Vermont, United States.