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Soil and Groundwater Contamination: Nonaqueous Phase Liquids

ISBN: 978-0-87590-321-7
224 pages
January 2005, American Geophysical Union
Soil and Groundwater Contamination: Nonaqueous Phase Liquids (0875903215) cover image


Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 17.

Nonaqueous phase liquids (NAPLs) are frequently found as soil and groundwater contaminants. Highly toxic even in small volumes, NAPLs can pose a threat to human health and damage surface and subsurface ecosystems.

In this book, we clarify the complex phenomena of NAPL migration and offer insight into the behavior of NAPLs at sites undergoing monitoring and remediation. Contents include discussion on:

  • Principles of NAPL behavior in the subsurface, including flow, transfer of components to water and gas phases, and transport
  • Migration and distribution
  • Site characterization and monitoring
  • Remediation methods, including hydraulic removal, pump and treat, and soil vapor extraction
  • Further discussion on gaps in our understanding of NAPLs at the field scale along with a thorough tutorial approach and supplemental CD, make this book an important guide and resource for practicing engineers and scientists, risk assessment professionals, teachers, and students.
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Table of Contents

Preface  v

1 Introduction
A. S. Mayer and S. M. Hassanizadeh  1

2 Fundamentals
K. H. Jensen and R. W. Falta  5

2.1 NAPL Characteristics and behavior of NAPLs in the subsurface  5

2.2 Parametersr esponsiblefo r NAPL distributiona nd flow in the subsurface  9

2.2.1 Interfacial tension and wettability  9

2.2.2 Capillary p ressure a nd capillary p ressure c urves  12

2.2.3 Relative permeability and relative permeability curves 24

2.2.4 Darcy's law and governinge quations for multiphase flow  27

2.3 NAPL mass transfer and transport  30

2.3.1 VaporP ressurea nd Solubility  31

2.3.2 Phase Densities 32

2.3.3 Concentrations 34

2.3.4 Equilibrium Phase Partitioning  37

2.3.5 Multiphase Transport Mechanisms 43

Migration and Distribution
T. H. IllangasekareK, . H. JensenI,. Javandel, a nd A . S. Mayer  47

3.1 Residuala nd trappeds aturations 47

3.2 The role of geologicalh eterogeneity 49

3.3 Interactions with the water table  54

3.3.1 LNAPL accumulation on water table  54

3.3.2 DNAPL poolingo n vs. penetrationo f the water table 56

3.3.3 Smearing of LNAPL due to water table fluctuations  59

3.4 Capillary barbers and channels 63

3.4.1 NAPL poolingo n vs. penetrationo f low permeable material  63

3.4.2 Migration of DNAPLs along sloping confining layers 72

3.4.3 Occurrenceo f NAPLs in high permeability regions 76

3.5 Small scale NAPL distribution 81

3.5.1 Unstable Fronts and Fingers 81

3.5.2 Occurrenceo f NAPLs in clay or rock fractures 86

4 Site Characterization and Monitoring
A. S. Mayer and M. Oostrom 97

4.1 LNAPL observations  97

4.1.1 Discrepancyb etweenf ree productl evels in
monitoringw ells andL NAPL specificv olume  97

4.1.2 Correlation of LNAPL well measurements to LNAPL volume  107

4.2 Observationso f dissolvedN APL components 116

4.2.1 NAPL componentsp resenti n groundwatear t lower
than solubilityc oncentrationasn d fluctuationsin
concentrations  116

4.2.2 Upgradiento ccurrenceo f dissolvedN APL componentvs vi a gas p hase t ransport 135

5 Remediation
M. Oostrom, R, W. Falta, A. S. Mayer, I. Javandel, and S. M. Hassanizadeh 141

5.1 Remediation methodologies 141

5.2 Hydraulic removal of LNAPL 146

5.2.1 LNAPL trapping as free product migrates towards extraction well 146

5.2.2 LNAPL trapping in the cone of depression 151

5.2.3 Decrease in free LNAPL recovery rates as a function of time  157

5.2.4 Incomplete removal of residual LNAPL with hydraulic methods 163

5.3 Pump and treat 169

5.4 Soil vapor extraction  178

Notation 191

List of Figures 197

List of Tables 204

References 206

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