Understanding The Factors Influencing Contaminant Attenuation And Plume Persistence

Persistent Link:
http://hdl.handle.net/10150/578836
Title:
Understanding The Factors Influencing Contaminant Attenuation And Plume Persistence
Author:
Guo, Zhilin
Issue Date:
2015
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release 01-Oct-2015
Abstract:
The phenomenon of plume persistence was observed for five federal Superfund sites by analysis of historical groundwater-withdrawal and contaminant-concentration data collected from long-term pump-and-treat operations. The potential factors contributing to plume persistence are generally recognized to include incomplete isolation of the source zone, permeability heterogeneity, well-field hydraulics, and non-ideal (rate-limited, nonlinear) desorption. However, the significance of each factor, especially the site-specific contribution is undetermined, which is very important for site development and management. One objective of this study is to quantify the impacts of different factors on mass-removal efficiency. Three-dimensional (3D) numerical models were used to simulate the impact of different well-field configurations on pump-and-treat mass removal. The relationship between reduction in contaminant mass discharge (CMDR) and mass removal (MR) was used as the metric to examine remediation efficiency. Results indicate that (1) even with effort to control the source, residual impact of source can still be a factor causing plume persistence, (2) the well-field configuration has a measurable impact on mass-removal efficiency, which can be muted by the influence of permeability heterogeneity, (3) in terms of permeability heterogeneity, both variance and correlation scale influence the overall mass-removal behavior, (4) the CMDR-MR relationship can be used to quantify the impacts of different factors on mass-removal efficiency at the plume scale. It has been recognized that the use of pump and treat for groundwater remediation will require many decades to attain site closure at most complex sites. Thus, monitored natural attenuation (MNA) and enhanced attenuation (EA) have been widely accepted as alternatives because of their lower cost and sustainable management for large, complex plumes. However, the planning and evaluation of MNA/EA applications require greater levels of characterization data than typically collected. Advanced, innovative methods are required to characterize specific attenuation processes and associated rates to evaluate the feasibility of MNA/EA. Contaminant elution and tracer (CET) tests have been proposed as one such advanced method. Another objective of this study is to investigate the use of modified well-field configurations to enhance the performance of CET tests to collect critical site-specific data that can be used to better delineate attenuation processes and quantify the associated rate coefficients. Three-dimensional numerical models were used to simulate the CET test with specific well-field configurations under different conditions. The results show that the CET test with a nested (two-couplet) well-field configuration can be used to characterize transport and attenuation processes by eliminating the impact of the surrounding plume. The results also show that applying select analytical mass-removal functions can be an efficient method for parameter estimation, as it does not require the use of mathematical transport modeling and does not require the attendant input data that are costly and time-consuming to obtain.
Type:
text; Electronic Dissertation
Keywords:
permeability heterogeneity; plume; tracer test; well-field hydraulics; Soil, Water & Environmental Science; mass flux
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water & Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Brusseau, Mark L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleUnderstanding The Factors Influencing Contaminant Attenuation And Plume Persistenceen_US
dc.creatorGuo, Zhilinen
dc.contributor.authorGuo, Zhilinen
dc.date.issued2015en
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.releaseRelease 01-Oct-2015en
dc.description.abstractThe phenomenon of plume persistence was observed for five federal Superfund sites by analysis of historical groundwater-withdrawal and contaminant-concentration data collected from long-term pump-and-treat operations. The potential factors contributing to plume persistence are generally recognized to include incomplete isolation of the source zone, permeability heterogeneity, well-field hydraulics, and non-ideal (rate-limited, nonlinear) desorption. However, the significance of each factor, especially the site-specific contribution is undetermined, which is very important for site development and management. One objective of this study is to quantify the impacts of different factors on mass-removal efficiency. Three-dimensional (3D) numerical models were used to simulate the impact of different well-field configurations on pump-and-treat mass removal. The relationship between reduction in contaminant mass discharge (CMDR) and mass removal (MR) was used as the metric to examine remediation efficiency. Results indicate that (1) even with effort to control the source, residual impact of source can still be a factor causing plume persistence, (2) the well-field configuration has a measurable impact on mass-removal efficiency, which can be muted by the influence of permeability heterogeneity, (3) in terms of permeability heterogeneity, both variance and correlation scale influence the overall mass-removal behavior, (4) the CMDR-MR relationship can be used to quantify the impacts of different factors on mass-removal efficiency at the plume scale. It has been recognized that the use of pump and treat for groundwater remediation will require many decades to attain site closure at most complex sites. Thus, monitored natural attenuation (MNA) and enhanced attenuation (EA) have been widely accepted as alternatives because of their lower cost and sustainable management for large, complex plumes. However, the planning and evaluation of MNA/EA applications require greater levels of characterization data than typically collected. Advanced, innovative methods are required to characterize specific attenuation processes and associated rates to evaluate the feasibility of MNA/EA. Contaminant elution and tracer (CET) tests have been proposed as one such advanced method. Another objective of this study is to investigate the use of modified well-field configurations to enhance the performance of CET tests to collect critical site-specific data that can be used to better delineate attenuation processes and quantify the associated rate coefficients. Three-dimensional numerical models were used to simulate the CET test with specific well-field configurations under different conditions. The results show that the CET test with a nested (two-couplet) well-field configuration can be used to characterize transport and attenuation processes by eliminating the impact of the surrounding plume. The results also show that applying select analytical mass-removal functions can be an efficient method for parameter estimation, as it does not require the use of mathematical transport modeling and does not require the attendant input data that are costly and time-consuming to obtain.en
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectpermeability heterogeneityen
dc.subjectplumeen
dc.subjecttracer testen
dc.subjectwell-field hydraulicsen
dc.subjectSoil, Water & Environmental Scienceen
dc.subjectmass fluxen
thesis.degree.namePh.D.en
thesis.degree.leveldoctoralen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineSoil, Water & Environmental Scienceen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorBrusseau, Mark L.en
dc.contributor.committeememberBrusseau, Mark L.en
dc.contributor.committeememberArtiola, Janick F.en
dc.contributor.committeememberMaddock, Thomas IIIen
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.