vvEPA
United States
Environmental Protection
Agency
Office of Research and
Development
Cincinnati, OH 45268
EPA/600/K-93/003
May 1993
Seminar on Characterizing
and Remediating Dense
Nonaqueous Phase Liquids
at Hazardous Sites
Presentation Outlines and
Slide Copy
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
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Disclaimer
Any mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
Printed on Recycled Paper
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Table of Contents
Speaker Biographies A-l
Dense Nonaqueous Phase Liquid (DNAPL)
Contamination and Transport 1-1
David K. Kreamer
DNAPL SHe Characterization 2-1
Robert M. Cohen
James W. Mercer
Options for DNAPL Remediation 3-1
Charles J. Newell
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Speaker Biographies
Robert M. Cohen
Principal Hydrogeologist, GeoTrans, Inc., Sterling, VA
Robert M. Cohen is a principal hydrogeolegist with GeoTrans, Inc. He received a B.S. from Dickinson College and an M.S.
from Pennsylvania State University, with degrees in geology. Since 1982, Mr. Cohen has been with GeoTrans, Inc. where
he has directed numerous environmental contamination and ground water resource development projects.
Mr. Cohen has been involved in the evaluation of various nonaqueous phase liquid (NAPL) contamination sites, including
several chemical waste landfills in the Niagara Falls, New York area (Love Canal and 102nd Street hazardous waste
landfills, among others) as well as the Fairfax, Virginia, Tank Farm petroleum release site, PCB sites in Florida, and
several sites contaminated with chlorinated solvents. In 1987, Mr. Cohen co-authored a paper on the investigation and
hydraulic containment of four NAPL contaminated chemical waste landfills in Niagara Falls, New York. In 1990, he
co-authored a review paper on NAPL contamination and in 1992 he co-authored the U.S. Environmental Protection Agency's
(EPA's) Dense Nonaqueous Phase Liquids (DNAPLs) Workshop Summary document. Also in 1992, Mr. Cohen co-authored a
paper on evaluating visual methods to detect NAPLs in soil and water. Along with Dr. James W. Mercer, Mr. Cohen
recently completed an EPA guidance document entitled "DNAPL Site Evaluation."
David K. Kreamer
Director, Water Resources Management Graduate Program
University of NevadaLas Vegas, Las Vegas, NV
David K. Kreamer is presently the Director of the interdisciplinary Water Resources Management Graduate Program at the
University of NevadaLas Vegas. He also is an associate professor of geoscience and a member of the Graduate Faculty
in Civil and Environmental Engineering. Prior to joining the faculty of University of NevadaLas Vegas, he was an
assistant professor of civil engineering at Arizona State University. Dr. Kreamer's undergraduate work was in microbiology
and chemistry; he holds a M.S. and a Ph.D. in hydrology, with a minor in geosciences, from the University of Arizona.
Dr. Kreamer's present responsibilities include teaching, research, service, and program administration. He has researched
many water-related topics, particularly the fate and transport of environmental contaminants, NAPLs, vadose zone hydrology,
radioactive waste disposal, ground water hydrology, landfills, monitoring well design, and water resources management. He
has been an invited lecturer at many conferences including a presentation in Brazil for the American Participant Program
administered through the Executive Branch of the U.S. Government. He has given national lectures and training for EPA,
the U.S. Bureau of Land Management, and the National Ground Water Association. In addition, he has presented
workshops at the Hanford Nuclear Site and for the states of Alaska, Arizona, and Idaho.
Dr. Kreamer has been an external peer reviewer for risk assessment methodologies at the Rocky Flats Plant as part of the
Rocky Mountain Consortium and for the Early Site Suitability documentation for the hydrology of Yucca Mountain. He
served as a member of EPA's Science Advisory Board subcommittee on carbon-14 migration as carbon dioxide gas from
high level nuclear waste repositories. He has worked at many CERCLA (Comprehensive Environmental Response,
Compensation, and Liability Act) and RCRA (Resource Conservation and Recovery Act) sites, including Johnston Atoll in the
Pacific Ocean. Dr. Kreamer has authored over 40 professional publications.
A-l
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James W. Mercer
President, GeoTrans, Inc., Sterling, VA
James W. Mercer received a B.S. from Florida State University, and a M.S. and a Ph.D. from the University of Illinois, with
degrees in geology. Dr. Mercer began working at the U.S. Geological Survey in 1971, where his research involved
geothermal reservoir simulation and engineering. He worked on the simulation of isothermal two-phase flow (light
nonaqueous phase liquids [LNAPLs] and water) and subsequently worked on the simulation of two-phase heat transport
(steam and water). His work was published in the 1970s. In 1979, Dr. Mercer co-founded GeoTrans, Inc. and in 1980 he
began simulation analysis of the Love Canal hazardous waste site in Niagara Falls, New York. In 1985, Dr. Mercer
received the Wesley W. Homer Award of the American Society of Civil Engineers for the work that he performed at the
Love Canal site.
Dr. Mercer became involved at other sites in Niagara Falls, New York, including the Hyde Park and 102nd Street landfills.
He continued to study the physics of DNAPL flow and co-authored a paper on SWANFLOW, a three-dimensional multiphase
flow code. He also became involved in characterizing DNAPL sites. In 1987, Dr. Mercer lectured on NAPLs for the
National Water Well Association's Distinguished Seminar Series and in 1989 he lectured on characterizing oily wastes for
EPA. In 1990, Dr. Mercer published a paper entitled "A Review of Immiscible Fluids in the Subsurface: Properties, Models,
Characterization and Remediation." In 1991, he participated in the DNAPL Workshop sponsored by EPA's Robert S. Kerr
Environmental Research Laboratory. Along with Mr. Robert M. Cohen, Dr. Mercer recently completed an EPA guidance
document entitled "DNAPL Site Evaluation." Throughout the 1980s, Dr. Mercer continued to work on numerous sites and
projects involving NAPLs, with work ranging from site characterization to evaluation of various types of remediation.
Charles J. Newell
Vice President, Groundwater Services, Inc., Houston, TX
Charles J. Newell has a B.S. in chemical engineering and a M.S. and a Ph.D. in environmental engineering from Rice
University. He has ten years of experience working as an environmental consultant on surface water, ground water, and
NAPLs issues. Dr. Newell currently serves as a vice president and environmental engineer at Groundwater Services, Inc.
His project experience includes ground water flow modeling, solute transport modeling, design and construction of ground
water and NAPL remediation systems, and field evaluation of emerging remediation technologies.
Dr. Newell directed the development of the OASIS ground water modeling software system under a two-year contract from
EPA's Center for Groundwater Research. He has applied this software to solute transport studies and risk assessments at
several industrial sites. He participated in the DNAPL Workshop sponsored by EPA's Robert S. Kerr Environmental Research
Laboratory. Dr. Newell has co-authored EPA publications that address both DNAPLs and LNAPLs issues. Dr. Newell served
as an instructor on ground water modeling for the Graduate Environmental Engineering Program at the University of
Houston and is a contributing author to the Standard Handbook of Environmental Engineering.
A-2
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Dense Nonaqueous Phase Liquid (DNAPL)
Contamination and Transport
David K. Kreamer
Director, Water Resources Management Graduate Program, University of NevadaLas Vegas
I. Introduction
A. Sdiedule for the Day
B. Definitions and Introduction
II. DNAPL Properties
A. Chemical Composition
1. General DNAPL Classification
a. Halogenated versus Non-Halogenated
b. Volatile versus Semi Volatile
c. Other DNAPLs
2. Organic Chemistry Review
3. Types of Problem Compounds
a. Solvents/Degreasers
b. Selected Pesticides
c Pol/chlorinated Biphenyl Oils
d. Creosote and Coal Tar
B. Physical Properties of DNAPLs
1. Density
2. Viscosity
3. Solubility
a. Aqueous Solubility and Preferential Dissolution
b. Solubility in the Oil Phase
c. Cosolvency
4. Vapor Pressure, Henry's Law, and Volatilization
5. Partitioning Into Organic Liquids/Kow
6. Surface Tension and Interfacial Tension
1-1
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7. Wettability and Wetting Angle
a. Capillary Force
b. Hydrophobicity
8. Electrical Properties
9. Photo (Light) Related Properties
a. Fluorescence
b. Photochemical Sensitivity
c Photo-enhanced Degradation
10. Immunological Response
C. Miaobial Transformation
1. The Subsurface Microbial Environment
2. Processes Affecting the Rate of Biodegradation
3. Typical DNAPL Biodegradation
a. Solvent Dehalogenation
b. Aromatic Dehalogenation
c PCB Degradation
4. Cometabolism
5. Rules of Thumb for Biodegradation
6. Critical Evaluation of Biorestoration Claims
III. Yadose Zone Movement of DNAPLS
A. Nonaqueous Phase Movement
1. Wetting Front Instabilities (Fingering)
2. Blockage by Water and Stratigraphic Layers
a. Porous Media
b. Fractured Media
3. Perched Layers, Slanted Layers, and Well Construction Challenges
B. Leaching and Aqueous Phase Movement
1. Unsaturated Zone Aqueous Phase Movement
2. Unsaturated Zone Hydraulic Conductivity
C Vapor Movement
1. Leaching of Vapors
2. Advective Gaseous Flux
a. Pressure Induced Flow
b. Density Driven Flow
3. Diffusion
1-2
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IV. DNAPL Movement in Ground water
A. Nonaqueous Phase Movement
1. Non-Geological Considerations
a. Spill Size
b. Types of DNAPL Spilled
2. Considerations in Movement
a. Initial Penetration of Groundwater
b. Effect of Pore Size
c Downward Migration
d. Mobilization
3. Porous Media
4. Fractured Rock
B. Aqueous Phase Movement
1. Dissolution - Process and Rates
2. Preferential Dissolution
3. Advection and Dispersion
4. Retardation
1-3
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SEMINAR SERIES
Characterizing and Remediating
Dense Nonaqueous Phase Liquids
at Hazardous Sites
DNAPL Contamination and Transport
DNAPL Site Characterization
Options for DNAPL Remediation
DNAPLS
DNAPL Contamination
and Transport
David K. Kreamer, Ph.D.
Director
Water Resources Management Graduate Program
University of Nevada, Las Vegas
DNAPLs
DNAPL Contamination
and Transport
Talk Outline
DNAPL Properties
Vadose Zone Movement
Groundwater Movement
1-5
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Terminology
NAPL : Nonaqueous Phase Liquid
DNAPL: Dense Nonaqueous Phase Liquid
LNAPL : Light Nonaqueous Phase Liquid
Terminology (Cont.)
LNAPLs
Floaters
Sp. Gravity < 1.0
WATER
= 1 -0
DNAPLs
Sinkers
Sp. Gravity > 1.0
DNAPLs
Classification
Halogenated Vs. Non-Halogenated
Volatiles Vs. Semi-Volatiles
Miscellaneous
1-6
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DNAPLs
Examples
Halogenated Semi-Volatiles
Chlordane
Aroclo M260
Dieldrin
Pentachlorophenol
* ATSDR (Agency for Toxic Substances and Disi
List of Hazardous Substances
11
13
30
31
aase Registry)
DNAPLs
Examples
Halogenated Volatiles y^yjj*
Chloroform 8
Trichloroethylene (TCE) 10
Tetrachloroethylene (PCE) 22
Carbon Tetrachloride 33
ATSDR List of Hazardous Substances
DNAPLs
Examples
Non-Halogenated Semi-Volatiles
Benzo(a)Anthracene 40
Naphthalene 60
Phenol 85
Chrysene 95
ATSDR List of Hazardous Substances
1-7
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DNAPLs
Examples
Miscellaneous
Mercury
Creosote
3
16
' ATSDR Ust of Hazardous Substances
Organic Chemistry
|Organics|
I
| Aliphatic |
Aromatic
[Alkanes| |Cycloalkanes| [Alkenes[ |Alkynes
.Organic Chemistry
Alkanes (Paraffins)
Saturates
Single Bonds
H
H -C-H
I
H Methane
Cn H2n+2
H H
I I
H C-C-H
I I
H H
Ethane
1-8
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DNAPLs
ci
Cl _C - CI
I
Cl
Carbon Tetrachloride
Cl H
Cl C C H
I I
Cl H
1,1,1-Trichloroethane
Cl Cl H
I I I
H-C-C-C-H
H H H
1,2-Dichloropropane
Organic Chemistry
'nn2n
Alkenes (Olefins) cn H
Unsatu rates
At least one C=C (double) Bond
H
-c'
H
H
Ethene
CH
H
Propene
DNAPLs
ci
H
ci
Cl
Cl
\
Cl
Trichloroethylene
(TCE)
Tetra(per)chloroethylene
(PCE)
1-9
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Organic Chemistry
2n.2
Alkynes c H
Unsaturates
At least one CsC (Triple) Bond
Acetylene
Organic Chemistry
Aromatics
Carbon atoms connected in a planar
ring structure with bonds in "resonance"
Different from Cycloalkanes
Organic Chemistry
Aromatics
Cycloalkanes
Corner represents Corner represents CHr
carbon atom "
CH
'CH
CI^CH-CH«
2
Cyclohexane
1-10
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Organic Chemistry
Aromatics
H
H I
>> .C
/C*C-C\
H ~ H
H
Benzene
or
Benzene
DNAPLs
Phenol
Naphthalene Benzo(a)Anthrazene
ci
CI
Pentachlorophenol
CI
Dieldrin
Why is it difficult to figure out
Pesticides ?
Example : Co-ral (livestock insecticide)
Aliases : Muscatox, Resistox, Coumaphos,
Bay 21/199, Asuntol, Baymix, Meldane.
Chemical Name:
O,0-diethyl-O-(3-chloro-4-methyl-
1-2-oxo(2H)-1-benzopyran-7-yl)-
phosphorothionate.
or 3-chloro-4-methyl-7-coumarinyl
diethyl phosphorothionate
Specific Gravity: 1.47
(Verschueren, 1983)
1-11
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Selected Pesticide Names
Name
Other Name
or Ingredient
Compound 497 Dieldrin
Seedrin Liquid Aldrin
Purpose
Ambush Aldicarb, Temik Systemic
Insecticide
Insecticide
Insecticide
Fumigant
(Verschueren, 1983)
Selected Pesticide Names
Name
Other Name
or Ingredient
Purpose
Grisetin
Griseofulvin
Fungicide
Co-op Brushkiller Iso-Octyl esters Herbicide
112
Warf-12
of 2,4-D and
2,4,5-T
Warfarin
Rodenticide
(Verschueren, 1983)
DNAPLs
Interesting Names/Abbreviations
TCA = Trichloroacetic acid S.G. 1.63
= 1,1,1 Trichloroethane S.G. 1.35
= Tucson Commission
on the Arts S.G. ?
ABS = Teepol715 = AAS
IDE = ODD
1-12
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DNAPLs
Poly Chlorinated Biphenyls (PCBs)
Mixtures of poly chlorinated biphenyls
Relatively non-flammable, useful heat-
exchange and dielectric properties
Electrical Industry : Capacitors & Transformers
Also used in Lubricating and Cutting Oils,
Pesticides, Adhesives, Plastics, Inks, Paints,
and Sealants
PCBs - Examples
2I2',5,5' - Tetrachloro
bipheny!
2,2',31,4,4'5',6-
Heptachloro
biphenyl
DNAPLs
PCBs (Cont.)
Generally, more Chlorine => more Water Soluble
Degree of chlorination often indicated by
trade name
- Aroclor 1242 - 42 % Chlorine (S.G. 1.42)
Aroclor 1260 - 60 % Chlorine (S.G. 1.44)
- Phenoclor DP6 and Clophen A60 have
approximately 6 Chlorine atoms/molecule.
1-13
-------
Creosote
A mixture of phenols and phenol
derivatives.
Obtained by the destructive distillation
of wood tar, or from the fractional
distillation of coal tar.
Most common wood preservative
Composition of Creosote
Aqueous Log
Solubility (mg/l) K^, K
Naphthalene 31.700 3.37 1,300
Acenaphthalene 3.930 4.33
Fluorene 1.980 4.18
Phenanthrene 1.290 4.46 23,000
Fluoranthene 0.260 5.33
Pyrene 0.135 5.32 84,000
(J.M.Henson, 1989)
DNAPLs
Physical Characteristics
Density
Viscosity
Solubility
Octanol - Water Partition Coeff. (Kow)
Vapor Pressure and Henry's Coeff.
1-14
-------
DNAPLs
Physical Characteristics (Cont.)
I nterfacial Tension
Wettability
Dielectric Constant
Light (Photo) Related Reactions
DNAPLs
Density
Mass (of fluid) per unit volume (g/mL)
Similar expressions include
Specific Weight
Specific Gravity
DNAPLs
Density (Cont.)
Specific Weight
Weight per unit volume (Ibs/ft3)
Specific Gravity
Density Relative to Water
Wt. of given vol. of Liquid
Wt. of same vol. of Water
1-15
-------
Density - Examples
Pentanel
Benzene £
Creosote |
Naphthalene I
TCE
PCEj
Pentachlorophenol
Mercury
1 1.5
(g/mL)
DNAPLs
Viscosity
Measure of a fluid's resistance to flow
Main Cause : Molecular Cohesion
Absolute (Dynamic) Vs. Kinematic
Typical Units : Centipoise (cp)
1 cp = 0.01 poise = 0.01 g/s.cm
DNAPLs
Viscosity (Cont.)
"Mobility" Increases with Increasing Temp.
As Temperature Increases, the
Cohesive forces Decreases, and the
Absolute Viscosity Decreases, thus
Increasing its "mobility"
1-16
-------
DNAPLs
Viscosity (Cont.)
May change with time
Crude Oil, after loosing lighter Volatile
compounds due to evaporation, may
become heavier and more viscous
Viscosity - Examples
Benzene|^^] ^ Water(1.0 cp)
Pentane | |
Ethylene Dibromide |
TCE|
PCE|
m-Cresol |
Mercury |
0 0.5 1 1.5 2
* 15.5 C, Varies w/ Creosote (cp)
mix. (USEPA, 1988)
DNAPLs
Hydraulic Conductivity (K)
K = fn [ Fluid density (p) & Viscosity (u.) ]
K=JlPi-
V
In Saturated Porous Media, Fluids with
will move faster relative to Water.
1-17
-------
DNAPLs
Aqueous Solubility
Equilibrium Concentration of a Chemical
or Compound in Water.
mg/L
Influencing Variables
- Molecular Weight & Structural Complexity
- Dissolved Salts or Minerals
- Cosolvency in mixed solvent system
-pH
DNAPLs
Aqueous Solubility (cont.)
Factors affecting rate of dissolution
Solubility of the Compound
Groundwater Flow Conditions
Contact Area
Contact Time
Aqueous Solubility - Examples
Toluene D
Benzene C
Dieldrinj
Pentachlorophenol |
PCEl
TCEB
Chloroform
Phenol
o
515
1780
0.1
14
150
1100
2000 4000 6000 8000
Solubility (mg/L)
1-18
-------
DNAPLs
Three Phase System
[DNAPL
Partition Coeffs.
K = Soil-Water
K' = DNAPL-Water
[WATER] ^^ [SOIL |
Octanol-Water Partition Coeff.
Tendency of a chemical to partition
between Organic and Aqueous phase
Con. in Octanol phase
Con. in Aqueous phase
Low KOW => Hydrophillic
High KOW => Hydrophobic
Kow - Examples
Ethanol
Phenol
Chloroform
TCE
PCE
Naphthalene
Chlordane
-1
1-19
-------
Cosolvency
Addition of a second solvent to a
mixture, changes the original solubility
of a chemical.
Two solvents change other properties
as well
Vapor Pressure
Determines how readily vapors volatilize
from pure liquid phase
Partial pressure exerted at the surface
of the liquid phase by the free molecules
Directly dependent upon temperature
atm, mm Hg
Vapor Pressure (Cont.)
Migration Controlled by Diffusion
Soil-Vapor Monitoring
Soil Venting
(Mercer, 1989)
1-20
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Vapor Pressure - Examples
Toluene n 22
Benzene | ~\ 76
Dieldrin) i.s
Naphthalene | 0.054
PCE 14
eo
0 40 80 120 160
Vapor pressure (mm Hg)
Henry's Law Constant (KH)
Con. of a compd. in the vapor phase
H ~ Con. in the aqueous phase
Also
r ^r
Vapor Pressure (atm) atm-m
Solubility (mol/m3) _ mol
[j
Henry's Law Constant (Cont.)
Soil-Gas Monitoring Implications
Higher the K H for a compound, the more
readily it will partition into the vapor
phase, and will be more amenable to
Soil-Gas monitoring.
1-21
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Henry's Law Const. - Examples
1E-06
1E-04 1E-02
KH (atm.m3/mol)
Dieldrin
Aldrin
Naphthalene
PCE
TCE
TCA
] Toluene
]Benzene
DNAPLs
Four Phase System
Partition Coeffs.
K = Soil-Water
K1 = DNAPL-Water
K" = DNAPL-Air
K = Water-Air
H (Henry's Const.;
Interfacial Tension
Interfacial Tension
Force exerted on the
interface between
two liquids
1-22
-------
Interfacial Tension (Cont.)
Measured as the force required to draw
a thin platinum wire ring through
the interface between two liquids.
Typical Unit: dynes/cm
Magnitude of Interfacial Tension is
lesser than the larger of Surface Tension
for pure liquids
Interfacial Tension (Cont.)
Higher the IT., less likely emulsions will
form, and better the phase separation
after mixing.
Lower the IT. between a DNAPL and
water, higher the instability of the
interface, and more likely the immiscible
fingering.
The Blender Test
Put a drop of DNAPL in a small vial of water and
blend the contents using a blender apparatus.
The effect of shear on the hydro-
carbon-water mixture can be examined.
Indicates whether emulsions can form
under certain pumping conditions
(Mercer, 1989)
1-23
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Interfacial Tension- Examples
Hexane|_
Toluene £
Benzene [
Carbon Tetrachloride
Aniline
10 20 30
dynes/cm
40
19.1
27.6
28.9
26.2
42.9
50
Wettability
Describes the preferential spreading of one
fluid over solid surfaces in a two fluid system.
(S.G.Huling et al., 1991)
Inferred from the Contact (Wetting) angle [-0-]
(USEPA. 1990)
The wetting angle is typically measured against
a clean, polished mineral surface (usually
calcite and quartz).
(Mercer, 1989)
A 0 >90°
0 fan\
I I
Wetting Fluid: DNAPL
Water
V e<9o°
,. \/DNAPLj
I I
Wetting Fluid: Water
Water
Fluid Relationships:
System Wetting Fluid Non-Wetting Fluid
airwater water air
air: DNAPL DNAPL air
water:DNAPL water ^ DNAPL
air:DNAPL:water waterxjrgamoair'1'
(1 ) Wetting fluid order
After Waterloo Centre for Groundwater Research, 1989
RSKERL 101-015
1-24
-------
Capillary Rfse Theory
0
Adhesive dominant Cohesive dominant
v y
Capillary Rise Theory ^^^^^^^^^^^^H
FT°
"*.' " *
Upward Force :
03 0 FT Cos 0 ( 2 s r)
/ Downward Force :
jh (sr2h)(pg)
? 2 FTCos 0
--> h .T
...?... oar
p y '
^tiectrical Properties ^^^^^^^^^^^
Dielectric Constant
Other Electrical Properties
1-25
-------
Light (photo) Related Reactions
Fluorescence
Light-Induced Reactions
Photoassisted Degradation
Fluorescence
Spontaneous emission of visible light
resulting from a concomitant movement
of electrons to higher and lower orbital
states when excited by UV radiation.
NAPLs can be identified by visual
examination of soil or water samples
using this property.
(R.M.Cohen et al., 1992)
Fluorescence (Cont.)
The examination is made in a dark room
by scanning the sample in a clear plastic
bag with the UV light.
The sample fluoresce depending upon
the contaminants.
Nearly all crude Oils, petroleum products,
aromatics, and many Unsaturated
Aliphatics fluoresce.
(R.M.Cohen etal., 1992) ,
1-26
-------
Light (Photo) -Induced Reactions
DNAPL is sorbed onto Solid-Phase Extraction
Membranes (SPE) from the aqueous phase
Silver Nitrate reagent is sprayed on the
SPE tabs and exposed to UV light.
(EJ.Poziomeketal., 1993)
Light (Photo) -Induced Reactions
(Cont.)
DNAPL presence indicated by the development
of gray coloration on the tabs.
Proven effective for PCBs
(EJ.Poziomeketal., 1993)
DNAPLs
Photoassisted Catalytic Degradation
Isothermal, parallel plate, fluidized
bed reactor
Titanium dioxide (TiO2) illuminated with
near ultraviolet light.
Cr-doped TiO2tested under visible light
excitation.
(Dibble, 1989)
1-27
-------
DNAPLs
Photoassisted Catalytic Degradation
(Cont.)
Reactor effluents analyzed by Gas
Chromatography
Gaseous TCE tested, 100 % conversion
to carbon dioxide and hydrogen chloride
High flowrates possible over long
periods of time
(Dibble, 1989)
Immunological Response
Immunoassays use polyclonal antibodies
Semi quantitative
Available tests for PCBs in soil and
other NAPLs
Microbial Ecology of Subsurface
1 x10 6 to 1 x10 8 microbes/gm soil
(more in pristine environments)
> 90% of microbes attached to soil
Metabolically active
Metabolically versatile
Oxic and anoxic conditions
1-28
-------
Microbial Transformation
Variables Affecting Rate of
Biodegradation
(Lymanetal., 1990)
Substrate Related
Physico - Chemical Properties
Concentration
(Lymanetal., 1990)
Organism Related
Species Composition of Population
Spatial Distribution
Population Density
Inter & Intra Species Reactions
Enzymatic Makeup and Activity
(Lymanetal., 1990)
1-29
-------
Environment Related
Temperature
pH
Moisture
Oxygen Availability
Salinity
Other Nutrient Availability
Soil Toxicity
(Lymanetal., 1990)
Selected Types of Aerobic & Anaerobic Respiration
- Microbial Metabolism of Organics
.... ,. . . .. Relative
Electron Metabolic p0t6ntia|
Process Acceptor Products Energy
Aerobic Heterotrophic Q
Respiration 2
Denitrification
Iron Reduction
Sulfate Reduction
Fermentation
Methanogenesis
(Adapted from Suflita et al., 1991)
N03
Fe3+
so*
Glucose
CO2,
CO2 ,H2O
CO2 , N2
C02,Fe2+
CO2,H2S
EtOH
CO2,CH4
L
HIGH
LOW
Halogenated Aliphatic Compounds
Anaerobic Conditions
k'sfc \f >
1 2 *'
>k3:
>k4
4 Kn
1-30
-------
Rate Reactions
Zero-Order
Ct=Co-kt
ti/2=Co/2k
First Order
C,= Co e
, ti/2 =0.693/k
v si
Slope = -k
t
1/C
Slope = k
Rate Reactions (Cont.)
Hyperbolic Reactions
S
u. - u^ Monod Equation
KS + S
\n = Specific growth rate (1/t)
\i = Max specific growth rate (1/t)
m
K = Saturation Coeff. (mg/L)
s
S = Growth limiting substrate
concentration (mg/L)
Dehalogenation
of Aromatic Compounds
Oxidative j |Hydrolytic| [Reductive]
(Commandeur et al. 1990)
1-31
-------
Oxidative Dehalogenation
Halogen is lost fortuitously during
oxygenation of the ring
Only in aerobic conditions
R x-
i i
JJ
°2 2[H] R
~
Dioxygenase
t
R = e.g. COOH, H, NH,
X = F, Cl, Br, I. ' (Commandeur et al. 1 990)
Hydrolytic Dehalogenation
Hydrogen is specifically replaced by a 'OH' group
Oj atom in the hydoxyl group is derived from
water instead of oxygen
Aerobic and Denitrifying conditions
R
($
1
x
H2° X" R
) U J . (A)
*" Hydroxylase s^^1
R = e.g. COOH, H, NH0 TOH
X = F, Cl, Br, 1. 2 (Commandeur et al. 1990)
Reductive Dehalogenation
Halogen is replaced by a Hydrogen
Halogenated aromatic compound acts as
the terminal electron acceptor
Sulfogenic and Methanogenic conditions
5 (HI X- "
O -i =U O
^s/^ X Dehalogenase ^^^
R = e.g. COOH, H,NH, ^
X = F, Cl, Br, I. (Commandeur etal. 1990)
1-32
-------
PCB Degradation
Anaerobic Conditions
Reductive Dechlorination
(Chlorines replaced by H's)
Reduces Toxicity
Enhances Aerobic Degradability
(J.M.Henson, 1989)
PCB Degradation (Cont.)
Anaerobic Conditions
Soils previously exposed to PCB's showed
activity.
. Added 700 ppm Aroclor 1242
Time 0 -1 % mono chlorinated biphenyls
Time 16 wks - 76% mono chlorinated biphenyls
- Penta-chlorinated biphenyls gone
- Most activity in first 4 weeks
(J.M.Henson, 1989)
PCB Degradation (Cont.)
Aerobic Conditions
Lower Chlorinated Compounds more
Susceptible
Treatment Evaluations should Perform
Mass Balance
GC/MS to Detect Preferential
Degradation
(J.M.Henson, 1989)
1-33
-------
PCB Structure and Biodegradability
The less chlorinated the biphenyl, the
faster aerobic degradation takes place.
( Biphenyls with more than 5 chlorines
substituted are resistant to degradation)
Dioxygenation takes place on the ring
with the least chlorine atoms.
(Furukawa, 1982)
PCB Structure and Biodegradability
(Cont.)
Nonchlorinated vincinal ortho and meta
positions favor dioxygenation
PCBs with chlorine substituents on both
rings are more recalcitrant than isomers
containing an unchlorinated ring.
Congeners with substituted ortho
positions are recalcitrant.
(Furukawa, 1982)
Cometabolism
Definition
The degradation of a compound that
does not provide a nutrient or energy
source for the degrading organisms
but is broken down during the degradation
of other substances.
(Alexander M., 1979)
1-34
-------
Cometabolism (Cont.)
Does not provide a growth substrate
=> The Population increase
characteristic of metabolic
degradation reaction does
not take place.
Rate of degradation is often slower
(Alexander M., 1979)
Rules of Thumb
for
Biodegradability
Rules of Thumb
for Biodegradability
Branching
Highly branched Compounds are more resistant.
Chain Length
Short chains are more resistant
Oxidation
Highly oxidized compounds, like halogenated
compounds, may resist further oxidation under
aerobic conditions but may be more rapidly
degraded under anaerobic conditions.
(Lymanetal., 1990)
1-35
-------
Rules of Thumb
for Biodegradability
Substituents (Number of)
Increased substitution hinders oxidation
responsible for breakdown of alkyl chains
No significant oxidation of PAH's with
more than three rings
On aromatic ring, the more the chlorines
the more resistant the compound.
(Lymanetal., 1990)
Rules of Thumb
for Biodegradability
Substituents (Position of)
Ortho and meta substituted aromatics
with methyl, chloro, nitro or amino are
more resistant than corresponding para
substituted.
Meta-disubstituted phenols and
phenoxyls are more resistant than
ortho or para isomers.
(Lymanetal., 1990)
Rujes of Thumb
for Biodegradability
Substituents (Type of)
For Naphthalene compounds, nuclei
bearing single small alkyl groups (methyl,
ethyl, or vinyl) oxidize faster than those
with a phenyf substituent
1-36
-------
Rules of Thumb for Biodegradabiiity
Some Examples
Biodegradable
O-CH -COOH
Additional
chlorine
in meta
position
Recalcitrant
O-CH -COOH
Cl
2,4,5 - D
2,4,-dichlorophenoxy
acetic acid
(2,4 - D)
2,4,5-trichlorophenoxy
acetic acid
(Atlas and Bartha, 1987)
Rules of Thumb for Biodegradabiiity
Some Examples
Biodegradable
Recalcitrant
o
CH,
H
H - N - C - O -
CH
H - C - N - C - CH2CI
CH,,
N-Alkyl
substitution
o
Propham gmjmygymy propachlor
(Isopropyl-N-phenyl- (N-isopropyl1 -2-
carbamate) {Atlas and Bartha 1987) chloroacetanilide)
Critical Evaluation of
Biorestoration Claims
Reduction in Subsurface Concentration
-Mass Balances
Increase in Biomass/Activity
Production of Catabolites
Consumption of Terminal Electron Acceptor
1-37
-------
Critical Evaluation of
Biorestoration Claims (Cont.)
Adaptation/Acclimation Phenomena
Biodegradation Kinetics
All factors relative to appropriate
Abiotic Controls
DNAPLs
Vadose Zone Movement
Nonaqueous Phase Movement
Aqueous Phase Movement
Vapor Movement
VADOSEZONE
Nonaqueous Phase Movement
Wetting Front Instabilities
Blockage by Water and Stratigraphic
Layers
Perched Layers
1-38
-------
Solid
Water
DNAPL
RSKERL 101-003
DNAPL, WA TER, AND AIR IN POROUS MEDIA
DNAPL SHORT CIRCUITING THROUGH A WELL
WELL
VADOSE ZONE
Aqueous Phase Movement
and Leaching
Leaching and Water Movement
Unsaturated Zone Hydraulic Conductivity
1-39
-------
RAIN
M M M
Groundwater Flow
Sample Numbers Required to Estimate Various
Soil, Water, and Chemical Transport Properties
to Within 10, 20, 50% of the Mean Value at
95% Confidence Interval
Parameter
10% 20% 50% Comments
Porosity
Bulk Density
Soil pH
Saturated "K"
K(G)
(Jury)
4
4
3
576
4225
1
1
1
144
1057
1
1
1
23
169
4 Studies
8 Studies
4 Studies
12 Studies
1 Study
(4 methods)
VADOSE ZONE
Vapor Movement of DNAPLs
Leaching of Vapors
Advective Gaseous Flux
Diffusion
1-40
-------
Leaching of NAPL Liquids and Vapors
* * t *
Capillary Fringe
groundwaler
(IOW i
Dissolved Phase
DNAPL
Gaseous Vapors
Residual
Saturation of
DNAPL in
Vadose Zone
Infiltration, Leaching and
Mobile DNAPL Vapors
Groundwater
Flow
Plume From DNAPL
Soil Vapor
Plume From DNAPL
Residual Saturation
After, Waterloo Centre (or Groundwater Research, 1989
RSKERL 101-002
DNAPL Residua
Saturation
1-41
-------
CONCENTRATION OF TOTAL VOCs IN SOIL CORES
IN HUNDREDS OF mg/kg
1234567
0
CO,
TOTAL VOCs
DEPTH 10
(FEET)
25
SATURATED
SAMPLE
25
15 20
% C02
Comparison of measured gaseous carbon dioxide concentrations versus total organic
compounds in soil cores from a vadose zone In a region of known contamination.
DNAPL Movement in Groundwater
Nonaqueous Phase
Aqueous Phase
GROUNDWATER
Nonaqueous Phase Movement
Non-Geological Considerations
Movement
Porous Vs. Fractured Rock
1-42
-------
GROUNDWATER
Non-Geological Considerations
Spill Size
Types of DNAPL Spilled
Residual
Saturation of
DNAPL in Vadose
Zone
Infiltration and
Leaching
Groundwater
Flow
Plume of Dissolved
Contaminants
Residual
Saturation in Saturated Zone
After, Waterloo Centre for Groundwater Research, 1989 RSKERL 101-007
Water
DNAPL
Solid
Jl-OOJ
DNAPL & WATER IN A POROUS MEDIA
1-43
-------
GROUNDWATER
Considerations in Movement
Initial Penetration of Groundwater
Effect of Pore Size
Downward Migration
Mobilization
Dissolved
Contaminants c
Low Permeable
Stratigraphic Unit
Groundwater
Flow
CLAY
RSKERL 101-011
1-44
-------
After, Waterloo Centre for Groundwater Research, 1989
RSKERL 101-012
Where KX2> Iv, > KX3
K x = Horizontal Hydraulic Conductivity
DNAPL
Residual
Saturation
After, Waterloo Centre for Ground Water Research, 1989
RSKERL 101-013
1-45
-------
Impermeable Boundary
After Waterloo Centre for Goumd Water Research 1989 RSKffil 101-0
Measured > Actual
T T~
I Actual
Measured _j_
DNAPL Pool
_ Impermeable
Boundary
Measured > Actual
Measured
Actual
I n^n.
1 i
RSKERL 101-019
DNAPL Pool
Impermeable Boundary
RSKERL 101-018
1-46
-------
Ground Surface
\7 Ground Water Surface
DNAPL Surface ^ Waler Drainhne
^7 cr
DNAPL ^ DNAPL Drainline
Bedrock
Oil Distribution
Ground Surface
V Ground Water Surface
DNAPL SurfaceJ^*^1 ~~^H
Bedrock
DNAPL Mounding
Ground Surface
Ground Water Surface ^
DNAPL Surface -ZT^~rv^^lZ^ ^
n
Bedrock
--
DNAPL Recovery
1-47
-------
High Level
Storage
Treatment
High Level
Water
--i*-
Hydraulically Induced
DNAPL Level
Static DNAPL Level
Gravel
Conductance
>c Sensor
Sand
15 -10-5
5 10 15
20
FINGER
Max Richard L Johnson eL d., 1982
1-48
-------
Kr = relative permeability
C '-
4 Increasing DNAPL Saturation
Increasing Water Saturation >
i
-1^1
Water Saturation
100% H
DNAPL Saturation
After Schwille, 1988
RSKERL101-017
Recovery well
Mobilization
Injection wells
1-49
-------
Ground.
Surface
Groundwater
Zone
" - ^ DISSOLVED
CONTAMINANTS
Groundwater CLAY LI
Flow
DNAPL
s- POOL
IMPERVIOUS
1-50
-------
HORIZONTAL DNAPL MIGRATION
IN FRACTURED ROCK
GROUNDWATER
Aqueous Phase Movement
Dissolution - Process and Rates
Preferential Dissolution
Advection and Dispersion
Retardation
Facilitated Transport
DNAPLs
Example
1m
1m
Contaminated
Soil Section
Dissolution
Hydraulic Conditions
K=10"3cm/sec
i = 1%, n = 30%
=> V = 0.03 m/day
Q= 1m2x 0.03 m/day
= 0.03m3/day
= 30 L/day
1-51
-------
DNAPLs
Dissolution (Cont.)
Example (Cont.)
.3
30 Urri of TCE
s.g. = 1.46 =>( 43.8 kg )
Solub. = 1100mg/L
10%Solub = 110mg/L= 1.1x104kg/L
Time to dissolve = 37 Years
^^^Q 30 L/m3of Dieldrin (s.g. 1.74), S=0.1mg/l
Time to dissolve = 479,452 Years
DISSOLUTION RATE DIFFERENCES
Preferential Dissolution
In a mixture, such as creosote, certain
compounds dissolve more readily than
others.
The mixture "ages"
(Changes composition with time).
1-52
-------
Preferential Dissolution
=1.98mg/L ) S = 31.7mg/L
Advection and Dispersion
Transport of solutes along streamlines
at average groundwater velocity.
Dispersion
Transport of solutes by hydraulic mixing
process due to local variations in
groundwater velocity.
Advection and Dispersion
Instantaneous
Point Source
o C-
^
Dispersion Disp
at time 0 at tin
B^~
^
ersion
ie 1
Dispersion
at time 2
-»
*
1-53
-------
Retardation
Retardation Groundwater Velocity
Factor (R) solute Velocity
kpPd kp = focxkoc
R = 1 + ppd = bulk density
n = effective porosity
Facilitated Transport
Cosolvent effect
Particle Transport
- Organic
- Inorganic
Biological
References
Atlas, R.M., and Bartha, K., Microbial Ecology -
Fundamentals and Applications, Benjamin/Cummings
Publishing Company, 1987,553 pp.
Cohen, Robert M., et al., Evaluation of Visual Methods to
Detect NAPL in Soil and Water: Ground Water Monitoring
Review, Fall 1992, pp 132-139.
Commandeur, L.C.M. and Parsons, J.R., Degradation of
Halogenated Aromatic Compounds: Physiology of
Biodegradative Microorganisms, Kluwer Academic Publishers,
1991, pp 207-220.
1-54
-------
References (Cont.)
Huling, Scott G., Facilitated Transport: EPA Superfund
Ground Water Issue, EPA/540/4-89/003,1989.
Huling, Scott G., et al., Dense Nonaqueous Phase Liquids:
EPA Ground Water Issue, EPA/540/4-91 -002,1991.
Lyman, W.J., et al., Handbook of Chemical Properties
Estimation Methods, McGraw Hill Book Company, 1990.
Poziomek, E.J., et al., A Field Screening Method for PCBs
in Water: Publication from the Third International Symposium
on Field Screening Methods for Hazardous Wastes and
Toxic Chemicals, Las Vegas, February 1993.
References (Cont.)
Suflita, J.M. and Sewell, Guy W., Anaerobic Biotransformation
of Contaminants in the Subsurface, USEPA Environmental
Research Brief, EPA/600/M-90/024 February 1991.
Verschueren, K., Handbook of Environmental Data
on Organic Chemicals, Van Nostrand Reinhold
Company, 1983,1310pp.
Questions ?
1-55
-------
DNAPL Site Characterization
Robert M. Cohen, Principal Hydrogeologist, GeoTrans, Inc.
James W. Mercer, President, GeoTrans, Inc
I. DNAPL Investigation Motivation
II. Characterization Objectives and Conceptual Model Development
III. DNAPL Site Identification
A. Historical Information
B. Site Data Interpretation
C. NAPL Detection Methods
IV. Noninvasive Methods
A. Aerial Photograph Interpretation
B. Soil Gas Surveys
C. Surface Geophysics
V. Invasive Methods
A. Concerns and Risks
B. Risk Minimization
C. Drilling
D. Monitor Wells
E. Fluid Measurement Data
2-1
-------
DNAPL SITE
CHARACTERIZATION
Robert M. Cohen and James W. Mercer
GeoTrans, Inc.
Sterling, Virginia
REFERENCES
DNAPL Site Evaluation, USEPA
guidance document (1993)
Estimating Potential for Occurrence of
DNAPL at Superfund Sites, USEPA Quick
Reference Fact Sheet (1992)
Dense Nonaqueous Phase Liquids - A
Workshop Summary, USEPA (1992),
EPA/600/R-92/030
Waterloo Centre for Groundwater Research,
University of Waterloo, DNAPL short course
TOPICS
WHY INVESTIGATE DNAPL
DNAPL SITE CHARACTERIZATION OBJECTIVES |
METHODS FOR DIRECT DETECTION OF
NAPL IN SOIL AND WATER
v ,-w'-,'»,- - ,- -
DNAPL SITE IDENTIFICATION
2-3
-------
WHY CHARACTERIZE DNAPL?
' Subsurface DNAPL cannot be adequately
characterized by investigating miscible
contamination due to differences in
transport principles and properties
<1ef5)
DIFFERENT TRANSPORT MECHANISMS
DNAPL v. Dissolved Contaminants
DNAPL UST Leak
WHY CHARACTERIZE DNAPL?
' DNAPL movement extends the source of
groundwater contamination from the
release area to the limits of DNAPL
migration ("the moving landfill" analogy)
(2 of 5)
2-4
-------
DEFINED AREAS AT A DNAPL SITE
V
"*- c'oSnSon
PLAN VIEW (after USEPA, 1992)
WHY CHARACTERIZE DNAPL?
DNAPL migration dominates contaminant
mass loadings to offsite areas, streams,
wells, etc.
(3 of 5)
WHY CHARACTERIZE DNAPL?
DNAPL can persist for decades as a
significant source of groundwater and
soil gas contamination
(4 of 5)
2-5
-------
DISSOLUTION TIMES FOR TCE
POOLS (POOL DEPTH=0.01 LENGTH)
300
(after Johnson and Pankow, 1992)
10 m pool - 3500 Liters
x 4 m pool - 224 Liters
/2m pool 24 Liters
0.5 1 1.5
Groundwater Velocity (m/d)
WEATHERING/DISSOLUTION OF
CHLOROBENZENE MIXTURE
(Mackayetal., 1991)
Chlorobenzene
A1,2,4-TriCB
1,2,3,5-TetraCB
10000 20000 30000 40000
Water-to-DNAPL Volume Ratio
WHY CHARACTERIZE DNAPL?
To avoid selecting an inappropriate
remedy or exacerbating the contamination
problem by remedial activities
(5 of 5)
2-6
-------
Well by Ace Environmental, Inc. |
Your Deep-Discount Consultant
Sand
T
DNAPL
DNAPL SITE
CHARACTERIZATION
GOALS
RI/FS
PROCESS
REVIEW |
EXISTING DATAj
f "" MK
r~bEVELOP INITIAL 1 <
ICONCEPTUAL MODEL! >
_ fRoNT
*" ^SJTE
MVASIVE & INVASIVE!
CHARACTERIZATION!
DERSTANDINGl
3F PROBLEM 1
PROCESSES |
f MORE 1-CREFINE CONCEPTUAL MODEtt
i
JNEEDEDJ ^ f ASSESS "|
IRISK & REMEDY|
L
TREATABILITY|
& PILOT 1
STUDIES J
2-7
-------
KEY OBJECTIVES OF DNAPL
SITE CHARACTERIZATION
Determine DNAPL properties
Identify DNAPL release/source areas
Define stratigraphy
Delineate DNAPL distribution
Minimize investigation risk
DNAPL PROPERTIES
Composition (yields information on
solubility, volatility, toxicity, etc.)
Density
Viscosity
Wettability
Interfacial tension
DNAPL PROPERTIES:
SIGNIFICANCE OF DENSITY AND
VISCOSITY
Thicker, less dense Thinner, denser
2-8
-------
DNAPL Height Required to Enter a
Saturated Medium *»nsity=i3g/cc
Critical DNAPL Height (m)
int tension=0 04 N/m
contact ang =35 deg
)001
0.01 01 1
Pore Radius or Fracture Aperture (mm)
10
IDENTIFY DNAPL RELEASE AREAS
AND VOLUMES
Site history information
Air photos and maps
Knowledge of industrial practices
Field investigations and data
interpretation
USE KNOWLEDGE OF SOURCE
AREAS TO GUIDE INVESTIGATION
Gas .-
Hdder Fomjjr
Site
Tar-Water
Separator
2-9
-------
DEFINE STRATIGRAPHY
Stratigraphic barriers and traps
Migration pathways
* Fractures in rock or cohesive soil
* Coarse lenses and layers
** Rootholes, burrow holes
> Manmade structures (sewers,
foundations, wells) and backfill
> Heterogeneity and anisotropy
Distribution of Sand Lenses in Parallel-Plate
Cell (from Kueperand Frind, 1991)
DBHJICEO
WATCH
OUT
1
,
1
4
SOU
r- . t
MCE
*
I 9 >
3
I
1
4
3
2
1
1 1
4
4
1
1
2 - * 83 OTTAWA
S -» 30 SILICA
4 -*TO SILICA
Source
245 sec.
313 sec.
Observed
Distribution of
PCEin
Parallel Plate
Cell with Time
(from Kueper
and Frind,
1991)
2-10
-------
Surface of Unfractured Clay Unit Showing
DNAPL Movement Down Topographic
Valleys (from Newell and Connor, 1992)
DNAPL Movement Along Top of Sandy Till
from the Former Ville Mercier Lagoons
(from The Mercier Remediation Panel, 1993)
STRATIGRAPHIC CONTROL ON DNAPL FLOW
VILLE MERCIER, QUEBEC
Lagoon Area 1972
LNAPL DNAPL
2-11
-------
STRATIGRAPHIC TRAP AT THE 102nd ST.
LANDFILL, NIAGARA FALLS, NY
after OCC/din (1990)
E-W CROSS SECTION, LOVE CANAL
NIAGARA FALLS, NY
Typical Weathering Sequence in Fine-Grained
Media (from McKay et al., 1993)
GROUND SURFACE
a. 3
lij
0
FRACTURES/HORI2 METRE
Ol 1 IP IOO
FRACTURES
WITH
OXIDATION
STAINING
/ BEST
FIT
2-12
-------
APPRQX.
04m ~
t* omeR
Columnar-polygonal
fracture pattern (after
McKay etal., 1993).
iit ODDER
1.6 GALLON
DRIP RELEASE
. OF PCE
PENETRATED
3.2 METERS
INTO THE
BORDEN
SAND
after Paulson and
Kueper (1992)
Injection Pipe;
Sheet
piling
Aquitard
surface
Multi-level TDR probes
INTERPRETED
PCE
SPREADING
BELOW THE
WATERTABLE
ALONG
CAPILLARY
BARRIERS IN
THE BORDEN
SAND
(anerKueperetal., 1993)
2-13
-------
GEOLOGIC VARIABILITY
Results in complex contaminant distribution
Limits effectiveness of remedies which rely on
fluid delivery systems to flush and/or contact
contaminants
External agents (injected air, cosolvents,
waterflood, etc.) will follow high K zones
Favors containment strategy
DELINEATE DNAPL DISTRIBUTION:
Mobile and Residual
Review site history and data
Noninvasive methods
Invasive methods
Data synthesis
Containment Concept at Ville Mercier
(from The Mercier Remediation Panel, 1993}
T
Cutoff Wall
Recovery Well
I DRAFT]
2-14
-------
MINIMIZE RISK ASSOCIATED
WITH INVESTIGATION
Worker health and safety concerns
Risk of inducing unwanted DNAPL
movement by invasive field activities
> Outside-in approach
> Noninvasive methods
* Optimize invasive methods and materials
* Phased characterization
Simplified Conceptual Model of DNAPL
Chemical Migration
Dissolved
Contaminant
Plumes
Residual ONAPL
+
DNAPL Pool
after Huling and W*av*r (1M1) and WCOR (1M1)
METHODS FOR
DIRECT
DETECTION OF
NAPLINSOILAND
WATER
2-15
-------
DNAPL DETECTION
To minimize risk of causing DNAPL
migration during drilling
To delineate DNAPL zone for remedy
design
DIRECT VISUAL DETECTION
OF NAPL IN SOIL AND WATER
Inexpensive
Immediate
Difficult where NAPL is clear and
colorless, at low saturation, or
distributed heterogeneously
SAMPLE SCREENING
Organic Vapor Analysis (OVA)
2-16
-------
0
3000
?1000
^ 300
o
'g 100
**
g 30
5 10
1 3
1
rganic Vapor Analysis of Soil
Heads pace
. L _
^r[~-
»_
i
*
.
i
&
0
-
*
f *
*
Chlorobenzene Kerosene PCE Blanks
. *
5 10 15 20
% NAPL Saturation
25
DIRECT DETECTION METHODS
Unaided
UV fluorescence
Hydrophobic dye shake test
Centrifugation
Use syringe needle to extract and place
suspect globules into a water column
Use hydrophilic filters or hydrophobic
materials for phase separation
HYDROPHOBIC DYE SHAKE TEST
Add water and hydrophobic dye
powder to soil in container
Cap and shake
Examine for presence of dyed NAPL
2-17
-------
HYDROPHOBIC DYE
Sudan IV powder dyes organic fluids red upon
contact but does not partition into water or air
Few mg powder used per sample
100 grams costs about $19.
Irritant and potential mutagen
Other color hydrophobic dyes available
UV FLUORESCENCE DETECTION
OF NAPL
Fluorescent NAPLs include nearly all petroleum
products, all aromatic compounds, and many
unsaturated aliphatic hydrocarbons (e.g., TCE &
PCE)
Saturated aliphatic hydrocarbons such as
dichloromethane generally do not fluoresce
unless mixed with fluorescent impurities
(1of2)
UV FLUORESCENCE DETECTION
OF NAPL
SW-LW blacklight cheap and simple to use
Can examine soil-water slurry in polybag;
squeeze sample to bring fluid to surface
UV analysis used for decades by oil industry to
identify petroleum in well cuttings
(2 of 2)
2-18
-------
VISUAL METHOD CONCLUSIONS
The hydrophobia dye shake test,
followed by UV fluorescence, are simple,
practical, and inexpensive means for
direct NAPL detection
VISUAL METHOD CONCLUSIONS
For volatile NAPLs, organic vapor
analysis can be used to screen samples
for further examination, and possibly to
infer NAPL presence
DNAPL Site
Identification
(Newell and Ross, 1992)
2-19
-------
IS IT A DNAPL SITE???
INDUSTRY | DNAPL DETECTED IN
TYPE WELLS, GROUNDWATER,
SOIL OR ROCK SAMPLES
PROCESS
OR WASTE
PRACTICE
DNAPL INDICATED
BY CHEMICAL ANALYSIS
DNAPL SUGGESTED
BY CHEMICAL ANALYSIS
DATA ADEQUATE?]
SITE HISTORY INFORMATION
Corporate owner/operator records
Government records
Universities, libraries, historic societies
Personnel interviews or depositions
Aerial photographs and maps
INDUSTRIES USING DNAPLS
-Chemical -Dry cleaning
-Solvents&refrigerants »Textile]
- Electronic/computer Metg| (
- Metal parts/products Meta| ^^^
-Music instruments .storage/transfer
-Aircraft/automotive Pajnt remova|
-Office machinery ,Wood preserving
- Plastics ^ stee( cokjng
- Pharmaceuticals , Waste djs ,
-MGPs (1850-1950)
2-20
-------
COMMON SUSPECT AREAS
> Floordrains/sumps
i Pits, ponds,
lagoons
> Sewer systems
i Septic tanks
i Leach fields
Disposal areas
> Pipelines
> Disturbed areas
Process tanks
Wastewater tanks
UST areas
AST areas
Chemical storage
and transfer areas
Loading docks
Drainage paths
DETECTING NAPL IN WELLS
> Survey fluid column with interface probe
> Pump or bail samples from top and
bottom of fluid column
> Use other discrete-depth sampler
> Inspect fluid on weighted cotton string,
bailer cord, probe wire, etc.
INFERRING NAPL PRESENCE
FROM CHEMICAL ANALYSES
Chemical concentration in groundwater
>1% of pure phase or effective solubility
limit
Chemical concentration in soil >10,000
mg/kg (1 % of soil mass)
1of2
2-21
-------
INFERRING NAPL PRESENCE
FROM CHEMICAL ANALYSES
Chemical concentration in groundwater
calculated from soil-water partitioning
relationship and soil analysis > effective
solubility (Feenstra et al., 1991)
Extremely high OVA concentrations
2 of 2
SUSPECTING NAPL BASED
ON FIELD CONDITIONS
DNAPL chemical concentrations increase with
depth in a pattern that is inconsistent with
advective transport
DNAPL chemical concentrations increase
counter to the hydraulic gradient from a release
area presumably due to DNAPL spreading
1of3
SUSPECTING NAPL BASED
ON FIELD CONDITIONS
i Erratic concentrations of NAPL chemicals
in groundwater, soil and soil gas
> Dissolved NAPL chemical concentrations
rebound after turning off a pumping system
2of3
2-22
-------
Off
MAX
target
: one Nitration
CONCENTRATION
REBOUND
UPON CESSATION
OF PUMPING
TIME
SUSPECTING NAPL BASED
ON FIELD CONDITIONS
Presence of DNAPL chemicals in
groundwater that is older than potential
release dates (using tritium for age dating)
Deterioration of wells and pumps
3of3
ISI
INDUSTRY
TYPE
PROCESS
OR WASTE
PRACTICE
DNAPL)
USE ]
T A DNAPL SITE???
) DNAPL DETECTED IN 1
WELLS, GROUNDWATER,
SOIL OR ROCK SAMPLES I
DNAPL INDICATED 1
BY CHEMICAL ANALYSIS
^.. . .. , y
DNAPL SUGGESTED 1
BY CHEMICAL ANALYSIS j
DATA ADEQUATE?)
2-23
-------
DATA AND CONDITIONS THAT CAN HELP
INDICATE NAPL PRESENCE OR ABSENCE
Many wells with screens across the
water table and in stratigraphic traps
Multi-level fluid sampling capability
Extensive chemical analysis
Defined stratigraphy & release history
TOPICS
Noninvasive methods
Invasive methods and concerns
STRATEGY
Phased study
Site-specific application of methods
Outside-in approach
Noninvasive methods
Optimize invasive methods
2-24
-------
NONINVASIVE
METHODS
NONINVASIVE METHODS
Air photo interpretation
Soil gas analysis
Surface geophysics
NONINVASIVE METHODS
Can often be used during the early
phases of field work to optimize the
cost-effectiveness of a site study.
Conceptual model refinements derived
using these methods reduce the risk of
spreading contaminants during later
invasive field work.
2-25
-------
AIR PHOTO INTERPRETATION
Historic conditions (i.e., waste
disposal practices and areas, ponded
fluids, disturbed soils, vegetative
stress, etc.)
Photogeology (to interpret geologic
and hydrologic conditions)
Fracture trace analysis (to identify
surface expressions of fracture
zones)
AIR PHOTO INVENTORY
Earth Science Information Center
U.S.G.S. in Reston, VA
Provides free listing of available images
from government and private vendors
Source, date, scale, film type, etc.
FRACTURE TRACES
Linear surface expressions of subsurface
zones of fracture concentration, typically
5-60 ft wide and near vertical, that are
mapped by stereo-interpretation of air photos
Surface features used to map fracture traces
include: straight valley segments; aligned
sags, depressions, soil tone anomalies, etc.
Groundwater flow and chemical migration are
concentrated in bedrock fractures, particularly
where permeability is enhanced by dissolution.
2-26
-------
FRACTURE TRACE DIAGRAM
(from Lattman and Parizek, 1964)
Contaminant
detection
and
recovery are
enhanced by
locating
wells in
fracture
zones
3 Plan view
FRACTURE TRACE APPLICATIONS
> To identify preferential zones of fluid
flow and chemical migration
> To site monitor and recovery wells
2-27
-------
VOCs IN GROUNDWATER AND
NAPL VOLATILIZE INTO SOIL GAS
SOIL GAS SURVEYS
Delineate volatile NAPL in vadose zone
Delineate shallow groundwater
contamination
Very limited capacity to delineate deep
groundwater contamination
Results can be misleading if subsurface
conditions are misunderstood
Requires confirmation by analysis of soil
and fluid samples
SOIL GAS GRAB SAMPLING
Typical procedure:
* Drive hollow probe to 3-10 ft
> Pump and purge soil gas from probe
* Collect sample from gas stream in glass or
stainless steel container
Can collect and analyze 20-50 samples/day
@$110-$190 each
Onsite analysis facilitates direction of survey
With introduction of volatile tracers into tanks
or pipelines, can be used for leak detection
2-28
-------
CORRELATION BETWEEN FREON 113
IN SHALLOW SOIL GAS AND
GROUNDWATER (anerThompson and Marrin, 1987)
10,000
=5 1000
«*» 3
0)
LU
100
10
1
1 10 100 1000 10,000
Freon 113 in Groundwater (ug/L)
TYPICAL NAPL ANALYTES AND PRODUCTS
DETECTABLE BY SOIL GAS ANALYSIS
BTEX compounds
Carbon Tetrachloride
Chloroform
1,1-Dichloroethane
1,1,-Dichloroethene
1,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
1,1,1-Trichloroethane
1,1,2-Trichloroethane
Trichloroethene
Gasoline
Jet Fuel
Diesel Fuel
Heating Oil
Coal Tar
Solvents & Cleaning
Fluids
Refrigerants
Paint Thinners
modified from
Tillman el al
(1989)
VOCs DIFFUSE FROM RESIDUAL NAPL
CONTAMINATE SHALLOW GROUNDWATER
REPARTITION TO SOIL GAS
Residual NAPL
i in Soil Gas
"~* MM
Dissolved VOCs
Groundwater Flow
after Rivett and Cherry (1991)
2-29
-------
VOC TRANSPORT IN SOIL GAS
AND GROUNDWATER
Source
VOC* Sir
Soil Gas
DNAPL
Groundwater Flow after Rivett and Cherry (1991)
LIMITED DIFFUSION OF VOCs FROM
GROUNDWATER TO SOIL GAS REDUCES
SOIL GAS SURVEY EFFECTIVENESS
Groundwater Flow
after Rivett and Cherry (1991)
SURFACE GEOPHYSICS
GPR
EM-Conductivity
Magnetometry
Metal Detection
Resistivity
Seismic
«Stratigraphy & migration pathways
° Conductive plumes
° Buried wastes and utilities
2-30
-------
Geologic Interpretation Using Ground Penetrating
Radar (GPR) (after Benson, 1991)
SURFACE
FINE
OUARTZ
SAND
CLAY
LOAM
GPR Image of a Buried River Channel Deposit
(from MacLeod and Dobu*h, 1991)
Detecting Buried Metal Drums in a
Trench 20' x 100" x 6' Deep
(after Benson, 1991)
Magnetomer
Metal Detector
2-31
-------
TkMi tuAU » G«Ho» O'
GPR Image of
3 Buried
55-Gallon
Drums (from
Benson, 1991)
EM Conductivity Survey Data at Love Canal
Anomalies Correlate with Drummed Chemical Waste
Disposal Areas
after Technos (1980)
DIRECT DETECTION OF DNAPL
USING SURFACE GEOPHYSICS
GPR to provide detailed stratigraphic images
and detect anomalous dielectric properties
due to NAPL presence
EM Conductivity or Electrical Resistivity to
monitor reductions in electrical conductivity
due to NAPL presence
2-32
-------
FAVORABLE CONDITIONS FOR
DIRECT DETECTION OF DNAPL
Simple stratigraphy
Large quantities
Baseline pre-release survey
Expert investigators
SURFACE GEOPHYSICAL SURVEYS
Enhance delineation of release areas,
stratigraphy, and migration routes
Direct detection of NAPL is limited by
lack of cost-effective methods and
geophysicists trained in methods
potentially applicable at NAPL sites
INVASIVE
METHODS
AND
CONCERNS
2-33
-------
TEST PIT AND TRENCHES
Delineate
-Stratigraphy
-Waste disposal areas
-Grossly contaminated areas
»Buried pipelines, USTs, etc.
Sampling
Large, continuous exposure
Limited risk of vertical migration
INVASIVE METHOD CONCERNS
AT DNAPL SITES
Increased health and safety risk
Matehal compatability
Cross-contamination potential
(DNAPL » dissolved)
Data acquisition and interpretation
INVASIVE METHOD RISKS
Drilling and well installations may create
vertical pathways for DNAPL movement
Pumping may induce DNAPL migration
2-34
-------
INVASIVE METHOD RISKS
Induced NAPL transport may:
> Heighten the risk to receptors
* Increase remedial difficulty and cost
*-Generate misleading data leading to
development of a flawed conceptual
model and a flawed remedy
INVASIVE METHODS RISKS
INCREASE WHERE THERE ARE
Fractured and/or heterogeneous media
Subtle NAPL barrier layers
Multiple NAPL release locations
Large NAPL release volumes
Mobile NAPL (low viscosity, high density)
RISK MINIMIZATION
13 suggestions
Use knowledge of stratigraphy and DNAPL
distribution to guide drilling
Characterize DNAPL
zone from top down
Avoid unnecessary
drilling in the DNAPL
zone
2-35
-------
RISK MINIMIZATION
Minimize time during which
boring is open
Minimize length of hole open
to formation
RISK MINIMIZATION
Maintain hydrostatic head in borehole; consider using
a dense drilling fluid
Use telescoped-casing drilling techniques to isolate
contaminated zones
Install packer & pump
Auger & split spoon install casing grout into annulus using
to top of rock jnsjde augers positive displacement
TELESCOPED WELL CASING TO
ISOLATE SHALLOW ZONE
2-36
-------
RISK MINIMIZATION
»Use less invasive
"Direct-Push" sampling
methods (i.e., Cone
Penetrometer, Geo-
Probe, HydroPunch) to
examine stratigraphy, soil
gas, and fluids with depth
CONE PENETROMETER
Advantages
+ Efficient for stratigraphic
logging of soft soils
Limitations
Unable to penetrate
dense formations
+ Continuous measurement - Limited depth capability
Limited soil and fluid
sampling capability
Limited well
construction capability
Needs confirmation
Limited availability
+ Sensors measure
penetration resistance,
pore pressure, radiation,
fluorescence ...
+ Soil gas and fluid sampling
+ No cuttings
Less intrusive; can grout
hole
RISK MINIMIZATION
Carefully examine samples as drilling progresses to
avoid drilling through a barrier layer below DNAPL
Visual evidence (sheens, staining, globules, etc.)
* Organic vapor analysis
> Hydrophobic dye test and/or UV examination
> Examine fractures, soil ped faces, macropores,
coarser lenses
> Dissect samples to reveal inner surfaces
2-37
-------
RISK MINIMIZATION
Consider chemical compatability of well materials
>-PVC & ABS - degraded by aromatics and organic
solvents
» Carbon steel - corrodes
Fluoropolymers - good resistance except to
fluorinated solvents; very expensive
-Stainless steel - generally recommended due to
good resistance (however, DNAPL may wet steel)
-DNAPL may shrink bentonite; however,
bentonite-cement grout may be appropriate
RISK MINIMIZATION
!8
Noninvasive methods p~-
At many sites, the
DNAPL zone can be :
'
. H i '"a
characterized by limiting drilling to shallow depth;
deeper units can be characterized by drilling
beyond the DNAPL zone
BEDROCK DRILLING/TESTING
PROTOCOL
Pressure grout surface casing to top of rock
Core 15' rock interval
Packer-pump test, collect sample
Pressure grout test interval
Ream grout to 6", pressure test, regrout if
needed
Continue coring, testing and grouting to base
of aquifer
2-38
-------
DNAPL SITE DRILLING RISKS
Some potential for causing downward
DNAPL migration occurs with all drilling
methods
"Safe" methods for drilling and constructing
wells through DNAPL zones have not been
adequately demonstrated
MONITOR WELL USE
Characterize immiscible fluid distribution, flow
directions and rates, groundwater quality, and
hydraulic properties
Well design and location influence DNAPL fluid
movement and distribution in the well environment
Qualitative nature of DNAPL distribution data
FLUID MEASUREMENT METHODS
Interface probe
Hydrocarbon and water detection pastes
Transparent bailers
Other depth-discrete bailers
Weighted string
Consider the potential for cross-
contamination and the cost to
decontaminate equipment.
2-39
-------
MEASURED DNAPL THICKNESS > POOL THICKNESS
(after Huling and Weaver, 1991)
MEASURED DNAPL THICKNESS < POOL THICKNESS
WELL CROSS-CONTAMINATION: DNAPL THICKNESS
AND ELEVATION MEASUREMENTS POTENTIALLY MISLEADING
DNAPL
New DNAPL pool
2-40
-------
DNAPL SINKS TO BASE OF COARSE SANDPACK
DNAPL SINKS THROUGH WELL AND SANDPACK
FINE-GRAINED SANDPACK RESISTS DNAPL ENTRY
Thin DNAPL pool
'< - - A .
1 <5
Capillary
barrier
2-41
-------
DNAPL UPCOMING DUE TO GROUNDWATER PURGING
(after Huling and Weaver, 1991)
DNAPL RISE IN WELL DUE TO CAPILLARY PRESSURE
^^^* Waste Pit
Residual
O.NAPL
Top of DNAPL pool is
undergoing drainage
DNAPL
pool
i>a^j^r^».B«A.ji^^w-»J3gsa43juiBLUi^aaiaiaaii
^^^~^^s^imm$=iim
Ssuj-g^sssBs;
^-'-ysSi.'SjssKS^;
^i£!§SSssSSsst
JHsSSsasKsS^"
(after WCGR, 1991)
2-42
-------
DNAPL WELL DESIGN SUGGESTIONS
Complete to top of capillary barrier beneath
DNAPL
Screen across entire continuous DNAPL
thickness
Sandpack coarser than media (consider
hydrophobic sandpack)
Competent materials
FLUID MEASUREMENT DATA
Interpret with caution
Compare well fluid distribution
measurements to boring data
INTEGRATED INVESTIGATION
AND DATA ANALYSIS
No practical cookbook approach
Site-specific conditions and issues
Phased characterization to meet risk and
remedy assessment needs
Apply standard and special methods to
deal with DNAPL site concerns and data
needs
2-43
-------
References
DNAPL Site Characterization
Robert M. Cohen and James W. Mercer
Benson, R.C. "Remote Sensing and Geophysical Methods for Evaluation of Subsurface Conditions." Practical Handbook
of Ground-Water Monitoring. D.M. Nielsen, ed. Chelsea, Ml: Lewis Publishers, 1991: 143-194.
Cohen, R.M. and J.W. Mercer. DNAPL Site Evaluation. Chelsea, Ml: Lewis Publishers, 1993.
Huling, S.G. and J.W. Weaver. "Dense Nonaqueous Phase Liquids." USEPA Groundwater Issue Paper. EPA/540/4-91,
1991: 21.
Johnson, R.L. and J.F. Pankow. "Dissolution of Dense Immiscible Solvents in Groundwater: 2. Dissolution from Pools
of Solvent and Implications for the Remediation of Solvent-Contaminated Sites." Environmental Science &
Technology, Vol. 26, No. 5, 1992: 896-901.
Kueper, B.H., D. Redman, R.C. Starr, S. Reitsma, and M. Mah. "A Field Experiment to Study the Behaviour of
Tetrachloroethylene Below the Watertable: Spatial Distribution of Residual and Pooled DNAPL." Submitted to
Ground Water.
Kueper, B.H. and E.O. Frind. "Two-Phase Flow in Heterogeneous Porous Media: 1. Model Development." Water
Resources Research. Vol. 27, No. 6, 1991a: 1049-1058.
Kueper, B.H. and E.O. Frind. "Two-Phase Flow in Heterogeneous Porous Media: 1. Model Application." Water
Resources Research, Vol. 27, No. 6, 1991b: 1059-1070.
Lattman, L.H. and R.R. Parizek. "Relationship Between Fracture Traces and the Occurrence of Ground-water in
Carbonate Rocks." Journal of Hydrology, Vol. 2, 1964: 73-91.
Mackay, D., W.Y. Shiu, A. Maijanen and S. Feenstra. "Dissolution of Non-Aqueous Phase Liquids in Groundwater."
Journal of Contaminant Hydrology, Vol. 8, No. 1, 1991: 23-42.
MacLeod, I.N. and T.M. Dobush. "GeophysicsMore Than Numbers." National Water Well Association Outdoor Action
Conference Proceedings. Las Vegas, NV, 1990.
McKay, L.D., J.A. Cherry, and R.W. Gillham. "Field Experiments in Fractured Clay Till: 1. Hydraulic Conductivity and
Fracture Aperture." Water Resources Research. Vol. 29, No. 4, 1993: 1149-1162.
Mercier Remediation Panel. "Evaluation of Long-Term Remedial Measures for the Subsurface Contamination
Associated with the Former Mercier Lagoons." Preliminary draft report submitted to Laidlaw Environment
Services, 1993.
2-45
-------
ReferencesContinued
Newell, CJ. and R.R. Ross. "Estimating Potential for Occurrence of DNAPL at Superfund Sites." USEPA Quick Reference Fact
Sheet, Ada, OK: Robert S. Kerr Environmental Research Laboratory, 1992.
Poulsen, M.M. and B.H. Kueper. "A Field Experiment to Study the Behavior of Tetrachloroethylene in Unsaturated Porous
Media." Environmental Science and Technology. Vol. 26, No. 5, 1992: 889-895.
Riveft, M.O. and J.A. Cherry. "The Effectiveness of Soil Gas Surveys in Delineation of Groundwater Contamination-. Controlled
Experiments at the Borden Field Site." Proceedings of the Conference on Petroleum Hydrocarbons and Organic Chemicals in
Ground Water: Prevention, Detection, and Restoration, National Water Well Association/American Petroleum Institute.
Houston, TX, 1991: 107-124.
Technos, Inc. Geophysical Investigation Results, Love Canal, New York. Report to GCA Corporation and USEPA, Miami, FL:
Technos, Inc., 1980.
Thompson, G.M. and D.L. Marrin. "Soil Gas Contaminant Investigations: A Dynamic Approach." Ground Water Monitoring
Review, Vol. 7, No. 3, 1987: 88-93.
Tillman, N., K. Ranlet and T.J. Meyer. "Soil Gas Surveys: Part I." Pollution Engineering, Vol. 21, No. 7, 1989a: 86-89.
Tillman, N., K. Ranlet and T.J. Meyer. "Soil Gas Surveys: Part II, Procedures." Pollution Engineering. Vol. 21, No. 8, 1989b: 79-
84.
U.S. Environmental Protection Agency. "Dense Nonaqueous Phase LiquidsA Workshop Summary." Dallas, TX, April 17-18,
1991: EPA/600-R-92/030. Robert S. Kerr Environmental Research Laboratory, Ada, OK.
WCGR. "Dense, Immiscible Phase Liquid Contaminants (DNAPLs) in Porous and Fractured Media, A Short Course." Notes from
the DNAPL Short Course, October 7-10, 1991, Waterloo Center for Groundwater Research, University of Waterloo, Kitchner
Ontario, Canada.
2-46
-------
Options for DNAPL Remediation
Charles J. Newell
Vice President, Groundwater Services, Inc
I. Introduction
A. Design Process
B. Can We Clean Up DNAPL Sites?
C. How Remediation Technology Evolves
II. Proven DNAPL Remediation Options
A. Remediating DNAPb in the Unsoturated Zone
1. Excavation
a. Applicability
b. Design Basis Information
c. Design Process
d. Case Study
2. Soil Vapor Extraction (SVE)
a. Applicability
b. Design Basis Information
c. Design Process
d. Case Study
B. Remediating DNAPLs in the Saturated Zone
1. Pumping DNAPL
a. Applicability
b. Design Basis Information
c. Design Process
d. Case Study
2. Pump-and-Treat (DNAPL Dissolution)
a. Applicability
b. Design Basis Information
c. Design Process
d. Case Study
3-1
-------
3. In-Situ Biodegradafion
a. Applicability
b. Design Basis Information
L Design Process
d. Case Study
C Other DNAPL Remediation/Control Approaches
1. Treatment Train
2. Containment
a. Hydraulic Containment
b. Physical Barriers
c Natural Dilution/Attenuation
d. Case Study
III. Emerging DNAPL Remediation Technologies
A. Implementing Emerging Remediation Technologies
B. Selected Emerging Technologies
1. Air Sparging in the Saturated Zone
2. Dewatering/Soil Venting
3. Surfactants and Other Mobility-Increasing Agents
4. Chemically-Enhanced Dissolution
5. Bioventing
6. Steam Injection
7. Pumping Systems: Horizontal Wells and Wellpoint Pumps
8. Permeable Reaction Walls (Magic Sand)
3-2
-------
OPTIONS FOR
DNAPL REMEDIATION
Charles J. Newell, Ph.D., P.E.
Groundwater Services, Inc.
Houston, Texas
3-3
-------
Roadmap
Introduction
-Design Process
-Can We Clean Up DNAPL Sites?
-How Remediation Technology Evolves
Five Proven Remediation Technologies
Emerging Technologies
Typical Remediation Work Program
Site
Characterization I
Design
Conceptual Detailed
Installation
Operations
V
/"
Design Process and Products
y
~\
|D«tailedDesignJ
No. of Write
Types of Pump*
UtchtnlctlSptct.
PtIOt
3-4
-------
Can We Clean Up DNAPL Sites?
No Proven Technologies s
to:
-Remove All DNAPL
-Reach Drinking Water
Standards
GENERAL DNAPL MANAGEMENT
STRATEGY
Dissolved Phase Zone:
RESTORE AQUIFER
Potential DNAPL Zone:
CONTAIN ORGANICS
Confirmed DNAPL Zone:
RECOVER DNAPL AND CONTAIN ORGANICS
How Remediation Technology Evolves
Cost-Effective Technology
Proven
Technology
Experimental
Technology
Emerging
Technology
Concepts
3-5
-------
Road map
Introduction
- Five Proven Remediation
Technologies
Emerging Technologies
Five Proven Remediation
Technologies
> EXCAVATION AND DISPOSAL/
TREATMENT
> Soil Vapor Extraction (SVE)
> Pumping DNAPL
> Pump & Treat (Dissolution)
> In-Situ Biodegradation
Excavation and
Disposal / Treatment
Haul to Off-Site Landfill
On-Site or Off-Site
Thermal Treatment
On-Site Physical /
Biological Treatment
3-6
-------
Applicability of Excavation
Standard Construction Practice to 25
Feet Depth
Dewatering Required if Below Water
Table
Unconsolidated Material
Best Technology for Small Volumes
Design Basis Information: Excavation
Excavation: Depth, Volume
Disposal: Type of Waste, Distance
Thermal Treatment: BTU Content, Type
of Soil
On-Site Treatment
-Soil Vapor Extraction
-Biodegradation
Design Process: Excavation/Disposal
Excavation Cost: $ 20 - $ 50 per cubic
yard
-Depth of Excavation?
-Area of Excavation?
-Need to Control Fugitive Dust, Vapors?
-Safety Issues?
Off-Site Disposal
-Need for On-Site Pretreatment?
-Distance to Landfill?
-Hazardous Waste Landfill: $ 100 - $ 500 per
cubic yard
3-7
-------
Design Process: Treatment
Thermal Treatment
-High Vs. Low BTU?
-Presence of PCBs, Dioxin?
-Low Temperature Treatment $ 100 - $ 200 / ton
-Thermal Destruction $ 300 - $ 1,000 / ton
On-Site Treatment
-Site Available for Treatment?
-Volatile or Biodegradable?
-Soil Vapor Extraction (SVE)
-Biodegradation
Five Proven Remediation Technologies
Excavation and Disposal /Treatment
-*- SOIL VAPOR EXTRACTION (SVE)
Pumping DNAPL
Pump & Treat (Dissolution)
* In-Situ Biodegradation
Soil Vapor Extraction
Vapor Treatment System
EHunci vi
Manifold
Air/Vapo, (Where Required)
A
3-8
-------
Applicability of SVE
Vapor Prauura LHollliood of Soil Air
(mm HoJ Suceasi Permubfllty
I
Butane *»
Benzenea*-
Xylene *
AMfcaito *
i
-10-
.10- Very
-ir Likely
-10'
-10° Somewhat
-i»< Likely
-it-
-'»' Less
-1*4 Likely
V
1 HIGH
(CoarMSand/
Grav*l)
ig
}:I MEDIUM
a (Fin. Sand)
LOW
(Clay or Silt)
I
ou>fl« COW, I»N
r
Design Basis Information: SVE
Air Permeability
-Estimated from Soil Properties
- Measured With Test in FwM
Contaminant Characteristics
-DNAPL Composition
-Volatility (Vapor Pressure, Henry's Law Coefficient)
Air Flow
jraphy
r Impermeable Cap
-Water Table and Need for Pumping
SVE Design Process
Choose Number of Vapor Extraction
Wells
Choose Well Spacing, Inlet Wells, Seals
Design Well Screens and Construction
Remember Vapor Treatment
Check for Groundwater Upwelling
3-9
-------
Five Proven Remediation Technologies
> Excavation and Disposal / Treatment
> Soil Vapor Extraction (SVE)
> PUMPING DNAPL
> Pump & Treat (Dissolution)
> In-Situ Biodegradation
Pumping DNAPL
Applicability of DNAPL Pumping
Sites With Large Amounts of
DNAPL
Look for Wells With Free-Phase
DNAPL
Easier to Remove Chlorinated
Solvents
Potentially Higher Gradient Under
Confined Conditions
3-10
-------
Design Basis Information: DNAPL Pumping
General
-Types of Chemicals, Viscosity, Interfacial Tension
-Stratigraphy
-Hydraulic Conductivity
Free-Phase DNAPL
-Thickness of DNAPL Pool
-Relative Permeability of DNAPL
Residual DNAPL
-Maximum Hydraulic Gradient
-Capillary Number
DNAPL Pumping Design Process
Choose Location of DNAPL Wells
Select Pumps and Materials
Assess EOR Technologies
-Vacuum-Enhanced Pumping
-Watarflooding
-Surfactants
-Steam
Design Treatment System
Five Proven Remediation Technologies
Excavation and Disposal /Treatment
Soil Vapor Extraction (SVE)
Pumping DNAPL
-*»- PUMP & TREAT (DISSOLUTION)
In-Situ Biodegradation
3-11
-------
Pump-and-Treat (Dissolution)
Dissolve Residual DNAPL
Based on Number of Pore Volumes
Key Concept: Effective Solubility
Applicability of Dissolution
DNAPLs in Saturated Zone
DNAPL with Very Soluble Components
Sites With Low Amounts of DNAPL
Highly Permeable Aquifers
Design Basis Information: Dissolution
Mass of Residual DNAPL in Subsurface
Effective Solubility of Key Contaminants
Maximum Potential Groundwater
Velocity
Remediation Period
3-12
-------
Dissolution Design Process
> Estimate Total DNAPL Mass
> Make Concentration Assumptions
-Constant Solubility
-Effective Solubility
> Divide to Get Number of Pore Volumes
> Size Recovery Well System
Five Proven Remediation Technologies
Excavation and Disposal /Treatment
Soil Vapor Extraction (SVE)
Pumping DNAPL
Pump-and-Treat (Dissolution)
-*- IN-SITU BIODEGRADATION
In-Situ Biodegradation
Oxygen
Addition
To:
Treatment
Treatment / Recycle
Recycle
Nutrient
Addition
In-SHu Biodegradation
Zone
3-13
-------
Applicability of In-Situ Biodeg.
> Sites With Non-Chlorinated Compounds
-BTEX
-Creosote Sites (Napthalene, PAHs)
-Coal Tar
> Sites With Depressed Oxygen in Plume
Area
' Aquifers With High Permeability
Design Basis Information: In-Situ Biodeg.
Biodegradability of Contaminants
-Chlorinated Compounds: No
- Non-Chlorinated Aromatic*: Yes
Presence of Indigenous Aerobic
Microorganisms
-Bugs Almost Always Present
-NEVER ADD BUGS
Water Chemistry
-Iron
-Calcium Carbonate
In-Situ Biodeg. Design Process
> Estimate Total DNAPL Mass
> Calculate Required Mass of Oxygen to Be Injected
- YMd: J gm Oxygm lor 1 gm Hydrocarbon
' Select Method to Add Oxygen to Injection Water
- Bubble Air In Injection Water -10 ma/I
- Pure Oiygtn - 25 mgfl
- Hydngtn P«ro«Pd. -100 mgA (?)
' Calculate Water Needed
' Size Recovery Well System
3-14
-------
Other DNAPL Remediation Approaches
Treatment Train
1 Long-Term Containment
GENERAL DNAPL MANAGEMENT
STRATEGY
Dissolved Phase Zone:
RESTORE AQUIFER
Potential DNAPL Zone:
CONTAIN ORGANICS
Confirmed DNAPL Zone:
RECOVER DNAPL AND CONTAIN ORGANICS
Hydraulic Containment
> Design Methods
-Javendahl Capture Zone Curves
-Computer Models
' Operational Factors
-Well Efficiency
-Seasonal / Annual Effects
Capture Zone
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Physical Barriers
Purpose
-Prevent Outward Migration of Organics
-Reduce Inflow of Ground Water
Design
-Type of Barriers
-Configuration
Construction
-Routinely Installed Down to 50 Feet
-Cost: - $ 10 - $ 20 per square foot for Slurry Wall
DNAPL Occurrence at Superfund Site
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Hydraulic Containment With Slurry Wall
Slurry Wall well
"TOT
Pits
Slurry Wall
Sf-Drinking Water
Aquifer
Capture Zone With No Slurry Wall
Pumping Rate: 2 GPM
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Capture Zone With Slurry Wall "A"
Pumping Rate: 1 GPM
DNAPL
Not
Present
Capture Zone With Slurry Wall "B"
Pumping Rate: 0.3 GPM
. DNAPL
Not
Present
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Natural Dilution / Attenuation
Key Processes
-Hydrolysis
-Natural In-Situ Biodegradation
-Recharge
-Discharge to Surface Water
Assessment Techniques
-Monitoring
-Computer Modeling
Roadmap
Introduction
Five Proven Remediation
Technologies
-^Emerging Technologies
Air Sparging
Air
Compressor
Blower I
Vapor
Treatment
P"APt-«^-*';' B±,es
Volatilizes Organics and Promotes In-Situ Biodeg.
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Dewatering / Soil Venting
Dewatering Fluid
to Wastewater
Treatment
Air Vented to
Atmosphere
1) Before 2) During
Exposes Contaminated Saturated Zone for SVE
Mobility-Increasing Agents
Separator
Surfactant Recycle
Surfactants
Water
:le Pj Water
_J" DNAPL
Mobilizes NAPLs
Chemically-Enhanced Dissolution
Separator
Surfactant Recycle B High
Concentration
of Water
Surfactants !
Water
Increases Solubility by Orders of Magnitude
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Bioventing
I Vapor Treatment
Clay or
Surface Seal
Saturated
Zone
Combines SVE and In-Situ Biodeg. for Unsaturated Zone
Steam Injection
Steam
Source
Mobilizes DNAPLs and Increases Solubility
Pumping Systems
Horizontal Wells Wellpoint Pumps
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Permeable Reaction Walls
Sale: Permeable
Biotic or Abiotic
funnel: Reaction Wall
Impermeable
Barrier Wall
Funnels Dissolved Organics Through Reaction Wall
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References
Options for DHAPL Remediation
Charles J. Newell
Hinchee, R.E., D.C. Downey, and EJ. Coleman. "Enhanced Bioreclomation, Soil Venting, and Groundwater Extraction:
A Cost-Effectiveness and Feasibility Comparison." Proceedings of the Conference on Petroleum Hydrocarbons and
Organic Chemicals in Ground Water, National Water Well Association/American Petroleum Institute, Nov. 17,
1987= 147.
Hunt, J.R., N. Sitar, and K.D. Udell. "Nonaqueous Phase Liquid Transport and Cleanup." Water Resources Research,
Vol. 24, No. 8, 1991.
Johnson, P.C., et al. "A Practical Approach to the Design, Operation, and Monitoring of In-Situ Soil-Venting
Systems." Groundwater Monitoring Review, Spring 1990.
Lee, M.D., R.L. Jamison, and R.L. Raymond. "Applicability of In-Situ Bioreclamation as a Remedial Action
Alternative." Proceedings of the Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water,
National Water Well Association/American Petroleum Institute. Nov. 17, 1987: 167-185.
Mackay, D.M. and J.A. Cherry. "Ground-Water Contamination: Pump and Treat Remediation." Environmental Science
& Technology. Vol. 23, No. 6, 1989.
Mercer, J.W., and R.M. Cohen. "A Review of Immiscible Fluids in the Subsurface: Properties, Models, Characterization
and Remediation." Journal of Contaminant Hydrology. Vol. 6, 1990.
Miller, C.T., M.M. Poirier-McNeill, and A.S. Mayer. "Dissolution of Trapped Nonaqueous Phase Liquids: Mass Transfer
Characteristics." Water Resources Research. Vol. 26, Mo. 11, 1990: 2783-2796.
Schwille, F. Dense Chlorinated Solvents in Porous and Fractured Media: Model Experiments (English Translation).
Ann Arbor, Ml: Lewis Publishers, 1988.
U.S. Environmental Protection Agency. "Dense Nonaqueous Phase Liquids." EPA Ground Water Issue Paper,
EPA/540/4-91-002, 1991 a.
U.S. Environmental Protection Agency. "Dense Nonaqueous Phase LiquidsA Workshop Summary." EPA Ground
Water Issue Paper, EPA/600-R-92/030, 1992b.
U.S. Environmental Protection Agency. In Situ Treatment of Contaminated Ground Water: An Inventory of Research
and Field Demonstrations: Strategies for Improving Ground Water Remediation. EPA/500/K-93/001, January
1993.
U.S Environmental Protection Agency. Soil Vapor Extraction Technology Reference Handbook. EPA/540/2-91/003,
February 1991. (COM Reference)
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ReferencesContinued
Waterloo Centre for Ground Water Research, University of Waterloo Short Course. Dense Immiscible Phase Liquid Contaminants
in Porous and Fractured Media. Kitchener, Ontario: University of Waterloo, October 1991.
Wilson, J.L. and S.H. Conrad. "Is Physical Displacement of Residual Hydrocarbons a Realistic Possibility in Aquifer Restoration?"
Proceedings of the Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water, National Water Well
Association. Houston, TX, Nov. 5-7, 1984.
Wilson, J.L., et al. Laboratory Investigation of Residual Liquid Organics from Spills, Leaks, and the Disposal of Hazardous
Wastes in Groundwater. EPA/600/6-90/004, April 1990.
Wilson, J.T. and C.H. Ward. "Opportunities for Bioreclamation of Aquifers Contaminated with Petroleum Hydrocarbons."
Developments in Industrial Microbiology (Journal of Industrial Microbiology Suppl. No. 1), Volume 27, 1987.
ReferencesCase Studies
Connor, J.A., C.J. Newell, and O.K. Wilson. "Assessment, Field Testing, and Conceptual Design for Managing DNAPL at a Superfund
Site." Proceedings of the Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water, National Water Well
Association. Houston, TX, 1989.
Newell, C.J., J.A. Connor, D. Wilson, and T.E. McHugh. "Impact of Dissolution of Dense Non-Aqueous Phase Liquids (DNAPLs) on
Groundwater Remediation." Proceedings of the Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water,
National Water Well Association. Houston, TX, November 1991.
Sale, T. and K. Pionteck. "A Decade of Remedial Action at a Former Wood-Treating Facility." Pre-Conference Seminar, Wafer
Environment Federation 65th Annual Conference. New Orleans, LA, Sept. 19, 1992.
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