P/EPA
United States
Environmental Protection
Agency
Research and
Development
(RD 681)
EPA/540/A5-89/004
August 1990
International Waste
Technologies/Geo-Con In Situ
Stabilization/Solidification
Applications Analysis Report
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
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EPA/540/A5-89/004
August 1990
International Waste Technologies/
Geo-Con In Situ
Stabilization/Solidification
Applications Analysis Report
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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Notice
The information in this document has been funded by the U.S. Environmental
Protection Agency under Contract No. 68-03-3255 and the Superfund Innovative
Technology Evaluation (SITE) Program. It has been subjected to the Agency's peer
review and administrative review and it has been approved for publication as a
USEPA document. Mention of trade names or commercial products does not constitute
an endorsement or recommendation for use
11
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Foreword
The Superfund Innovative Technology Evaluation (SITE) program was authorized in
the 1986 Superfund amendments. The program is a joint effort between EPA's Office of
Research and Development and Office of Solid Waste and Emergency Response. The
purpose of the program is to assist the development of hazardous-waste treatment
technologies that will be necessary to meet new cleanup standards, which require
greater reliance on permanent remedies. This is accomplished through technology
demonstrations that are designed to provide engineering and cost data on selected
technologies.
This project consists of an analysis of the International Waste Technologies/Geo-Con
proprietary in situ stabilization/solidification process and represents the sixth field
demonstration in the SITE program. The technology demonstration took place at a
former electric service shop owned by General Electric Company in Hialeah, Fla. The
demonstration effort was directed at obtaining information on the performance and
cost of the process for use in assessments at other sites. Documentation will consist of
two reports. The Demonstration Report describes the field activities and laboratory
results and has been previously issued. This Applications Analysis Report provides an
interpretation of the available data and presents conclusions on the results and
potential applicability of the technology.
Additional copies of this report may be obtained at no charge from EPA's Center for
Environmental Research Information, 26 West Martin Luther King Drive, Cincinnati,
Ohio, 45268, using the EPA document number found on the report's front cover. Once
this supply is exhausted, copies can be purchased from the National Technical
Information Service, Ravensworth Bldg., Springfield, VA, 22161, 703-487-4600.
Reference copies will be available at EPA libraries in their Hazardous Waste
Collection. You can also call the SITE Clearinghouse hotline at 1-800-424-9346 or 202-
382-3000 in Washington, D.C. to inquire about the availability of other reports.
Walter W. Kovalick, Jr.,
Acting Director, Technology
Innovation Office
Alfred
Acting -DTfector, Office of Engineering
and Technology Demonstration
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Abstract
An evaluation was performed of the International Waste Technologies (IWT) HWT-20
additive and the Geo-Con, Inc. deep-soil-mixing equipment for an in situ
stabilization/solidification process and its applicability as an on-site treatment method
for waste site cleanup. The analysis of this technology is contained in two reports, the
Technology Evaluation which describes the demonstration and this Applications
Analysis which evaluates the technology based upon all available data.
A demonstration was held at a General Electric Co. electric service shop in Hialeah,
Florida, which provided the bulk of the information for the technology evaluation.
Operational data and sampling and analysis information, for this first field
application of the IWT additive, were carefully monitored and controlled to establish a
database against which other available IWT and Geo-Con data, and their claims for
their technologies, could be compared and evaluated. Conclusions were reached
concerning the technology's suitability for use in cleanups of various contaminants
and at different locations.
The technical criteria used to evaluate the effectiveness of the in situ process were
contaminant mobility (based on leaching and permeability tests), and the potential
long-term integrity of the solidified soils (based on some physical tests and
microstructural studies). The Geo-Con deep-soil-mixing system was also evaluated.
Since the most controlled sampling on the IWT additive was performed during the
demonstration, much of the emphasis of the evaluation is based upon this data. Test
samples were taken of the site material before treatment to characterize.the site and of
the solidified materials after curing for 5 weeks. Samples of treated and untreated
material were analyzed to determine: physical properties (such as unconfined
compressive strength and permeability) that along with the microstructural studies
provides clues to long-term durability of the treated mass; chemical properties (such as
soil composition and leachability) that provide information on contaminant mobility.
This report evaluates the in situ process (based on the test results of the
demonstration), other data provided by the technology developers, and the general
capabilities of cement-based systems. It also discusses the probable applicability of the
technology to sites other than the GE electric service shop.
IV
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Abstract (Continued)
The conclusions drawn from, the available data are that: (1) immobilization of
polychlormated biphenyls (PCBs) appears likely, although due to low leachate
concentrations for both the treated and untreated soils - a result of the low
concentrations of PCBs in the soil encountered in most of the tests - it cannot be
confirmed; (2) heavy metals can probably be immobilized; (3) volatile organics can
bereduced to low concentrations in treated soil leachates, but the ability to immobilize
is not clear; (4) a small volume increase on the order of magnitude of 5%-10% can be
expected; (5) the solidified material shows satisfactory physical properties- - with high
unconfined compressive strengths, moderately low permeabilities, and satisfactory
integrity for the wet/dry samples - but unsatisfactory integrity for the freeze/thaw
samples; and (6) microstructural results show a dense, low-porosity homogeneous
mass - indicating a potential for long-term durability.
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Contents
Page
Foreword iii
Abstract iv
Tables ix
Figures x
Abbreviations and Symbols xi
Conversions xiv
Acknowledgments ....- xv
1. Executive Summary 1
Conclusions 1
Results 2
2. Introduction 5
The SITE Program 5
SITE Program Reports 5
Overview of Stabilization/Solidification 6
Stabilization/Solidification Technologies and Superfund Reponse Actions 6
Key Contacts 8
3. Technology Applications Analysis 9
Introduction 9
Conclusions 9
Evaluation of Performance 10
Environmental Regulations Pertinent to In Situ Stabilization/
Solidification 16
Waste Characteristics and Their Impact on Performance of
the Technology 20
Material Handling Required by the Demonstrated Technology 22
Personnel Issues 22
Procedures for Evaluating Stabilization/Solidification 22
4. Economic Analysis 25
Introduction 25
Results of Economic Analysis 25
Basis of Economic Analysis 26
vn
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Contents (Continued)
References 31
Appendices
A. Process Description 33
B. Vendor's Claims for the Technology 37
C. SITE Demonstration Test Results 53
D. Case Studies 63
References for Appendices 75
Vlll
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Tables
Number
1
2
B-l
B-2
C-l
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
Posttreatment Soil and Leachate Analyses of Samples
CollectedbyGE ......... ....
Estimated Cost
Infrared Data
DSC Data . .
Physical Properties of Untreated Soils - Sector B
Physical Properties of Untreated Soils - Sector C ......... ,
Physical Properties of Treated Soils - Sector B
Physical Properties of Treated Soils - Sector C
Results of Formulation Studies
PCBs in Soils and Leachates - Sector B . .
PCBs in Soils and Leachates - Sector C
Total Volatile Organics in Soils and Leachates
Total of Four Priority Pollutant Metals in Soils and Leachates
Page
12
26
51
51
56
57
58
59
59
60
61
62
62
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Figures
Number Page
A-l Batch Mixing Plant 34
A-2 Overlapping Column Arrangement 35
B-l Coordination Complexes 40
B-2 Pn to dn Bonding 40
B-3 Lewis Acid Base Reactions: Formation of Sigma Bonds 41
B-4 Observed Bonding Phenomenon in the HWT-23
Treatment Matrix 42
B-5 Formation of Permanent Sigma and Pi Bonding
(Covalent Bonding) 43
B-6 Supramolecular Chemistry/Multiple and Secondary Bonding 44
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Abbreviations and Symbols
ANS 16.1
ARARS
ASTM
BOAT
CERCLA
CFR
cm/s
DSC
DSM
EPA
EPTox
°F
FTIR
ft3
FY
F006
F012
F019
g/ml
GC/ECD
GC/MS
Geo-Con
GE
gpm
Modified American Nuclear Industry Leaching Test Methods
Applicable or Relevant and Appropriate Requirements
American Society for. Testing and Materials
Best Demonstrated Available Technology
Comprehensive Environmental Response, Compensation and
Liability Act of 1980
Code of Federal Regulations
centimeters per second permeability units
differential scanning calorimetry
deep soil mixing
Environmental Protection Agency
Extraction Procedure Toxicity Test
degrees Fahrenheit
Fourier transform infrared
cubic feet
fiscal year
wastewater treatment sludges from electroplating operations
quenching waste water-treatment sludges from metal heat-treating
operations where cyanides are used
wastewater treatment sludges from the chemical conversion
coating of aluminum
grams per milliliter
Gas chromatography/electron capture detector
Gas chromatography/mass spectrometry
Geo-Con, Inc.
General Electric Company
gallons per minute
XI
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Abbreviations and Symbols (Continued)
HSWA
HWT-20
IWT
kW
kWh
Ib/min
LDR
LE
MCC-1P
mg/kg
mg/L
NCP
NPL
O&G
ORD
OSHA
OSWER
PCBs
PCP
PSD
ppb
ppm
psi
RCRA
ROD
RREL
SARA
SEM
Hazardous and Solid Waste Amendments to RCRA -1984
Treatment additive offered by IWT
International Waste Technologies
Kilowatt(s)
Kilowatt hour
pounds per minute
Land Disposal Restriction
Law Environmental, Inc.
Materials Characterization Center Static Leach Test Method
milligrams per kilogram
milligrams per liter
National Contingency Plan
National Priorities List
oil and grease
Office of Research and Development
Occupational Safety and Health Act
Office of Solid Waste and Emergency Response
polychlorinated biphenyls
pentachlorophenol
particle size distribution
parts per billion
parts per million
pounds per square inch
Resource Conservation and Recovery Act
Record of Decision
Risk Reduction Engineering Laboratory
Superfund Amendments and Reauthorization Act of 1986
scanning electron microscope
Xll
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Abbreviations and Symbols (Continued)
SITE Superfund Innovative Technology Evaluation Program
TCLP Toxicity Characteristic Leaching Procedure
TMSWC Test Methods for Solidified Waste Characterization
TOG total organic carbon
TSCA Toxic Substances Control Act
UCS unconfined compressive strength
um micrometer
ug/L micrograms per liter
VOC volatile organic compound
XRD X-ray diffraction
yd3 cubic yard
Kill
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Conversions
English (US)
Area: 1 ft2
lin2
Flow Rate: 1 gal/min
1 gal/min
1 Mgal/d
1 Mgal/d
1 Mgal/d
Length: 1 ft
lin
lyd
Mass: 1 Ib
lib
Volume: 1 ft3
1ft3
Igal
Igal
ft = foot, ft2 = square foot, ft3 = cubic foot
in = inch, in2 = square inch
yd = yard
Ib = pound
gal = gallon
gal/min = gallons per minute
Mgal/d = million gallons per day
m = meter, m2 = square meter, m3 = cubic meter
cm = centimeter, cm2 = square centimeter
L = liter
g = gram
kg = kilogram
m3/s = cubic meters per second
L/s = liters/second
m3/d = cubic meters per day
Metric (SI)
9.2903 x 10-3 m2
6.4516 cm2
6.3090 x 10-5 m3/s
6.3090 x 10-2 L/S
43.8126 L/s
3.7854 x!03m3/d
4.3813 x 10-2 m3/s
0.3048 m
2.54cm
0.9144m
4.5359 xlO-2g
0.4536 kg
28.3168 L
2.8317 x lO-2 m3
3.7854 L
3.7854 x 10-3 m3
xiv
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Acknowledgments
This report was prepared under the direction and coordination of Mary Stinson EPA
SITE Project Manager in the Risk Reduction Engineering Laboratory, Cincinnati
Ohio. Contributors and reviewers for this report were the USEPA's Office of Research
and Development; Linda D. Fiedler of the Office of Solid Waste and Emergency
Response; Gregory A. Ondich of the Office of Environmental Engineering and
Technology Demonstration; Jeffrey Newton of International Waste Technologies-
Brian Jasperse of Geo-Con, Inc.; John Harrsen of General Electric Co Walter
Sumansky of NUS Corp.; and Frank Cartledge, Harvill Eaton, and Marty Tittlebaum
ot bcientific Waste Strategies, Inc.
iN WaS PrePared for EPA'S Superfund Innovative Technology Evaluation
(bITE) Program by Stephen Sawyer of Foster Wheeler Enviresponse, Inc., for the U S
Environmental Protection Agency under Contract No. 68-03-3255.
xv
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Section 1
Executive Summary
Introduction
In 1986, the EPA established the Superfund
Innovative Technology Evaluation (SITE) Program
to promote the development and use of innovative
technologies to clean up Superfund sites. The
analysis of the technologies in the SITE Program are
contained in two documents, the Technology
Evaluation Report and this Applications Analysis
Report. This report evaluates and estimates the
applicability and costs of the International Waste
Technologies (IWT)/Geo-Con in situ stabili-
zation/solidification process based on all available
data. This data, other than the demonstration, is
from laboratory studies.
The most extensive testing of the combined
technologies was performed during the SITE
demonstration, based upon an agreed to
demonstration plan between EPA and the
developers, although other information on the
individual technologies is provided by the
developers. EPA used a direct approach to evaluate
the technology by measuring contaminant mobility
and solidified mass durability. The emphasis of the
IWT research work has been to show that chemical
bonding of additive to contaminant occurs. However,
this is only an indirect approach, and it requires a
research program that is outside the scope of a SITE
project.
The demonstration occurred at a General Electric
Co. (GE) electric service shop in Hialeah, Florida in
April 1988. The process involves the in situ injection
and mixing of the IWT additive HWT-20 with the
hazardous waste material. IWT claims that HWT-20
chemically bonds to the PCB contaminants, thus
immobilizing them and containing them within a
hardened, leach-resistant concrete-like mass.
Therefore, the major objectives of the SITE project
were to evaluate the IWT/Geo-Con in situ
stabilization/solidification technology in the
following areas:
Immobilization of polychlorinated biphenyls
(PCBs) - mainly Aroclor 1260, a set of
congeners of known ratio.
Immobilization of organic and heavy metal
contaminants, based on other experience of the
developers.
Demonstration of in situ operation of the Geo-
Con soil mixing equipment.
Degree of soil consolidation (solidification)
caused by the chemical additive, HWT-20.
Probable long-term stability and integrity of
the solidified soil.
Performance and reliability of the Geo-Con
injection and mixing auger.
Costs for commercial-scale applications.
Conclusions
The conclusions drawn from reviewing the data on
this in situ stabilization/solidification process, both
from the SITE demonstration and other available
data in relation to SITE project objectives were:
PCBs do appear to be immobilized by the
process. However, for most of the tests, the PCB
concentrations in the soil and resulting
leachate concentrations were low and so close to
the analytical detection limits that a firm,
decisive evaluation of the technology's ability to
immobilize PCBs could not be performed.
From laboratory studies provided by IWT,
immobilization of volatile and semi-volatile
organics may occur in some instances. This is
based on TCLP leach tests, see Appendix D
Case study D-4. In addition, the IWT additive
contains organophilic clays, which are known
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in some cases to bond to organics. However,
since insufficient data exists, both from the
demonstration and these laboratory studies,
confirmation of immobilization is not possible.
IWT data indicates that the HWT compounds
probably immobilize heavy metals. This is
supported by the fact that most cement-based
systems can immobilize metals.
The PCB concentrations in the soil at the
Hialeah site were too low for effective
evaluation of this technology. Thus, bench scale
testing of samples by EPA with higher
concentrations of PCBs would have enhanced
the evaluation of the IWT additive. Later, such
treatability studies were added to the SITE
demonstrations.
The physical properties of the treated soils were
in general quite satisfactory, which would
support the potential for long-term durability.
High unconfined compressive strengths (UCS)
(300-1,000 psi), low permeabilities (10-6 to 10-7
cm/s), and satisfactory results of the wet/dry
weathering tests were obtained. Many of the
freeze/thaw test specimens showed large weight
losses and samples degraded sharply. However,
IWT has indicated that the additive mixture
used in the demonstration was designed for
Florida, where freeze/thaw weathering should
not be a problem. The volume increase of the
soil after treatment was small, about 8.5% in
the demonstration. The microstructural
analyses of solidified soil samples indicated a
potential for long-term durability; the samples
showed a dense, homogeneous, and low-porosity
structure. The apparent disagreement between
the poor freeze/thaw results (taken only during
the demonstration) and the other satisfactory
results cannot be explained at this time.
The Geo-Con deep-soil-mixing equipment
appeared to work well during the
demonstration and provided intimate mixing of
additive and soil. Geo-Con also has other
experience at hazardous waste sites, where
sludge ponds were solidified and barrier walls
provided, as well as considerable soil
consolidation experience in all types of soils.
Thus, the deep-soil-mixing capabilities of Geo-
Con are well proven.
The IWT/Geo-Con in situ stabiliza-
tion/solidification system is economical.
Remediation costs for two cases were estimated.
For the first case, using Geo-Con's larger 4-
auger system, under the ground rules defined in
Section 4, the cost was $lll/ton of soil. For the
1-auger unit, used during the demonstration,
the cost was $194/ton of soil.
It appears possible to apply the IWT/Geo-Con
technology for immobilization of heavy metals, PCBs
and some heavy organics in wastes up to 25 wt%
organics. Although an HWT-20 admix was selected
for use at the Hialeah site for the treatment of PCB-
contaminated soils, other formulations exist to treat
other contaminants. However, since very limited
bench-scale studies have been performed, it is
recommended that treatability studies site specific
leaching, permeability, and physical tests be
performed on each specific waste to be treated.
The Geo-Con technology can be used for most soils in
most climates with treatment capabilities to a depth
in excess of 100 ft. However, clays, oily sands, and
cohesive soils may reduce auger penetration rate and
depth of operation.
Potential physical limitations in the application of
the IWT/Geo-Con technology need to be considered.
The volume increase may cause some difficulties in
restricted site areas where land contours could be
seriously altered. An additional limitation is the
technology's use in cold climates, where freeze/thaw
degradation of the solidified monolith may occur and
the feed slurry may freeze during operation. Large
rocks (> 10 in.) and man-made obstacles such as
drums and lumber can provide hindrances.
Results
Chemical Tests
Chemical analyses were performed on untreated and
treated soils, along with leaching tests for the
corresponding soil sample. Leachate analyses exist:
on treated and untreated soils from the
demonstration, using the Toxicity Characteristic
Leaching Procedure (TCLP); on Law Environmental
(LE) samples taken at the GE site, using Extraction
Procedure Toxicity (EP Tox) and TCLP; and from
some testing performed by IWT on PCBs, VOCs,
heavy metals, and semivolatile organics, using
TCLP.
The IWT process, as evaluated during the
demonstration, appears to immobilize PCBs.
However, due to the relatively low levels of PCBs at
the Hialeah site, which produced leachate
concentrations close to their detection limits (0.1
ug/L), more information at higher PCB
concentrations are required to confirm this
conclusion. For laboratory prepared samples by LE
using soils from the site known to have different
concentration levels of PCBs, which ranged from 83
to 5,628 mg/kg, results from EP Tox tests showed
immobilization. However, TCLP tests on 5 samples
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showed higher concentrations in the leachates of
treated soils than those of untreated soils. LE had no
definitive explanation for the unexpected results.
Thus, the LE results also provide some uncertainty
on the ability of the process to immobilize PCBs.
The demonstration was inconclusive on the ability of
the process to immobilize VOCs and metals, due to
an insufficient number of samples available for
testing. In addition, IWT did not tailor its HWT-20
additive to immobilize VOCs and metals, but did
design it for PCBs. IWT has performed some TCLP,
tests on treated samples prepared in the laboratory,
and considerable laboratory testing using solvent
extraction, Fourier transform infrared (FTIR) and
differential scanningcalorimetry (DSC). These latter
tests were to prove that the additive chemically
bonds to various organic and inorganic compounds. It
does appear that some bonding occurs, which would
in all likelihood reduce contaminant mobility.
Chemical bonding should also reduce the need for
maintaining physical integrity of the solidified
monolith.
Physical Tests
The most extensive physical testing carried out to
date on the IWT process was performed as part of the
SITE demonstration, although some additional data
was obtained by LE [1] for GE on laboratory
prepared samples and from core samples taken
shortly after the demonstration [2]. All of the
available test data are based on a soil with a very low
organic content, i.e., a very narrow range of
contaminated soils. IWT cannot provide any other
data; their research emphasis is related almost
exclusively to chemical bonding studies, which they
claim show the capabilities of their additives better
than physical tests.
During the demonstration, unconfined compressive
strength (UCS) values ranged from a low of 75 psi in
Sector B to a high of 866 psi in Sector C, with the
overall average about 400 psi. The tests performed
by LE produced UCS values ranging from 198 to
2,127 psi for approximately the same dosage rate of
HWT-20. These are very satisfactory when compared
to the EPA guideline of a 50-psi minimum [3] for
stabilization/solidification systems and other
concrete-based waste-treatment systems, which have
UCS results typically in the range of 15 to 150 psi [4].
However, there are a few other technologies that do
provide larger values of UCS. High UCS values
imply the potential for maintaining structural
integrity.
The results from the 12-cycle wet/dry and
freeze/thaw weathering tests showed low absolute
weight losses for the wet/dry samples (0.3% to 0.4%).
However, for the freeze/thaw test specimens, weight
losses up to 30% were seen, with an average of 6.3%,
while the control sample weight losses were about
0.3%. UCS tests on the weathered samples from the
SITE demonstration showed no loss of strength when
weight losses were less than 3.0%. Above 3.0%, very
severe strength losses were measured, with UCS
values approaching zero at 10% weight loss. These
weathering tests are more severe than weathering
under an actual field environment, but do provide an
indication of short-term durability, since the tests
only consist of 12 cycles. IWT has indicated that they
can adjust the additive mix to be more resistant to
freeze/thaw conditions. Quantification of solidified
mass integrity in terms of life expectancy is not
possible.
Permeability is a measure of a solid's ability to
permit the passage of water. The treated soil values
obtained for the SITE demonstration were between
10-6 and 10-7 cm/s, and they are slightly greater than
those obtained by LE and EPA on samples prepared
by LE. These values are comparable to the target
value of lO-7 cm/s or less used for designing soil
barrier liners for hazardous-waste landfill sites.
Also, this is a large decrease compared to the
untreated soil (10-2 cm/s) and indicates the
groundwater will flow around the treated block. Low
permeabilities should reduce the potential for both
erosion and leaching.
Bulk density results were obtained for the SITE
demonstration as well as for some earlier samples
prepared by LE for GE. The bulk density increase on
solidification averaged 21%, from 1.55 g/mL (96
Ib/ft3) to 1.88 g/mL (117 Ib/ft3), for a total mass
increase (HWT-20 plus water) of 32%, which resulted
in a volume increase of 8.5%. Even though this
volume increase is relatively small, the ground rise
could require removal of treated soil or special site
contouring. Only posttreatment values are available
from the LE tests and they tend to agree with the
demonstration results, showing a bulk density of
about 1.83 g/mL (114 Ib/ft3).
The microstructual analyses performed on SITE
demonstration samples included optical and
scanning electron microscopy and X-ray diffraction
analyses of the crystalline structures. These results
showed a dense, homogeneous, and nonporous
structure. Therefore, a potential for long-term
durability of the treated soil monolith exists.
Operations
Geo-Con, Inc. performed the remedial operations for
the demonstration in two 10x20-ft test sectors. They
were responsible for the slurry preparation, flow
control of additive and water, and soil injection and
mixing. Equipment operations were satisfactory.
Some minor operating problems occurred, such as:
inability to maintain automatic feed control; losing
supplemental water for the last 21 soil columns due
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to a leak in the auger head; and the locations of many
of the soil columns deviated from the targeted
location, producing some poorly treated areas.
However, these difficulties are readily fixable. Geo-
Con also has very considerable experience in soil
consolidation, constructing slurry barrier liners and
work similar to that at Hialeah in all types of soils to
depths in excess of 100 ft. Overall, the conclusion is
that Geo-Con's injection and mixing equipment
provides a unique technology that can be considered
a valid option where in situ stabiliza-
tion/solidification or solidification technologies are
deemed desirable.
Economics
The economic analysis investigated two cases, one
using a 1-auger machine as in the demonstration,
and the other with a 4-augef unit, which would be
used for large-scale operations. Only one additive
rate was assumed, 0.15 Ib HWT-20/lb dry soil, which
is near the minimum that IWT would use for any
remediation. Most of the operating expenses were
provided by Geo-Con, based on their quotation to GE.
The results, based on a 5 d/wk, 8 h/d operation and
the simplified concepts defined in Section 4, showed
the costs would be $11 I/ton of soil for the 4-auger
unit and $194/ton of soil for the 1-auger unit. The
cost components with the most impact on the totals
were equipment rental, the HWT-20 additive, and
labor, which combined, amounted to about 85% of the
total cost.
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Section 2
Introduction
The SITE Program
In 1986, the EPA's Office of Solid Waste and
Emergency Response (OSWER) and Office of
Research and Development (ORD) established the
Superfund Innovative Technology Evaluation (SITE)
Program to promote the development and use of
innovative technologies to clean up Superfund sites
across the country. The SITE Program is composed of
two major elements: the Demonstration Program
and the Emerging Technologies Program.
The major focus has been on the Demonstration
Program, which is designed to provide engineering
and cost data on selected technologies. To date, the
demonstration projects have not involved EPA
funding for technology developers. EPA and
developers participating in the program share the
cost of the demonstration. Developers are responsible
for demonstrating their innovative systems at
chosen sites, usually Superfund sites. EPA is
responsible for sampling, analyzing, and evaluating
all test results. The result is an assessment of the
technology's performance, reliability, and cost. This
information will be used in conjunction with other
data to select the most appropriate technologies for
the cleanup of Superfund sites.
Developers of innovative technologies apply to the
Demonstration Program by responding to EPA's
annual solicitation. To qualify,for the program, a
new technology must be at the pilot or full scale and
offer some advantage over existing technologies.
Mobile technologies are of particular interest to
EPA.
Once EPA has accepted a proposal, EPA and the
developer work with the EPA regional offices and
state agencies to identify a site containing wastes
suitable for testing the capabilities of the technology.
EPA prepares a detailed sampling and analysis plan
designed to thoroughly evaluate the technology and
to ensure that the resulting data are reliable. The
duration of a demonstration varies from a few days to
several months, depending on the length of time and
quantity of waste needed to assess the technology.
After the completion of a technology demonstration,
EPA prepares two reports, which are explained in
more detail below. Ultimately, the Demonstration
Program leads to an analysis of the technology's
overall applicability to Superfund problems.
SITE Program Reports
The analysis of technologies participating in the
Demonstration Program is contained in two
documents, the Technology Evaluation Report and
the Applications Analysis Report. The
Demonstration Report contains a comprehensive
description of the demonstration sponsored by the
SITE program and its results.. This report gives a
detailed description of the technology, the site and
waste used for the demonstration, sampling and
analysis during the test, and the data generated.
The purpose of the Applications Analysis Report is to
estimate the Superfund applications and costs of a
technology based on all available data. This report
compiles and summarizes the results of the SITE
demonstration, the vendor's design and test data,
and other laboratory and field applications of the
technology. It discusses the advantages,
disadvantages, and limitations of the technology.
Costs of the technology for different applications are
estimated based on available data on pilot- and full-
scale applications. The report discusses the factors,
such as site and waste characteristics, that have a
major impact on costs and performance.
The amount of available data for the evaluation of an
innovative technology varies widely. Data may be
limited to laboratory tests on synthetic wastes, or
may include performance data on actual wastes
treated at the pilot or full scale. In addition, there are
limits to conclusions regarding Superfund
applications that can be drawn from a single field
demonstration. A successful field demonstration does
- not necessarily assure that a technology will be
widely applicable or fully developed to the
commercial scale. The Applications Analysis
attempts to synthesize whatever information is
available and draw reasonable conclusions. This
document will be very useful to those considering the
technology for Superfund cleanups and represents a
-------
critical step in the development and
commercialization of the treatment technology.
Overview of Stabilization/Solidification
Stabilization and solidification are treatment
processes designed to accomplish one or more of the
following:
Improve the handling and physical
characteristics of the waste.
Decrease the surface area of the waste mass.
Limit the solubility of hazardous constituents.
Detoxify contained contaminants.
Stabilization is a beneficial action that occurs
through limiting the solubility or mobility of the
contaminants irrespective of a change in physical
characteristics. Solidification implies that a benefit
is obtained through the production of a solidified
block, which has high structural integrity.
Stabilization processes are grouped into categories
according to the types of additives and processes
used. These categories are: (1) cement, (2) lime plus
poz/.olan (fly ash, kiln dust, hydrated silicic acid,
etc.), (3) thermoplastic (asphalt, bitumen,
polyethylene, etc.), (4) thermosetting organic
polymers (ureas, phenolics, epoxides, etc.), (5)
vitrification, and (6) miscellaneous others. The
existing processes, although assumed to be chemical
in nature, involve little chemical alteration. The
waste particles may merely be microencapsulated,
which is particularly true for organic contaminants
[5]. In situ stabilization/solidification is one
variation on the above categories of treatment
processes.
The IWT process is a cementitious process that also
uses proprietary additives and other pozzolans.
Portland cement reaction products are a fused
mixture, in somewhat variable proportions of
calcium, silicon, aluminum, and iron oxides, the
main constituents of which are usually hydrated
calcium alumino-silicates and calcium silicates. This
type of process is usually most applicable to treating
inorganic wastes, such as incinerator wastes and
other sources of heavy metals. Usually the purpose of
adding other pozzolans, such as fly ash, is to produce
a stronger product. Organics (such as oil and grease)
in the soil may interfere with the cement bonding
reactions by coating the soil particles. At soil
contents above 10 wt% interferences from organics-
may occur.
One possible approach that could reduce the mobility
of organic contaminants in cemetitious systems is to
use an additive that interacts with the cement
matrix, while at the same time adsorbing the organic
material. Clay minerals offer one such possibility
and have been used for many years by the nuclear
industry [6]. Of particular interest is the use of clays,
reacted with alkylammonium cations (quaternary
ammonium salts), to enhance clay-organic waste
interaction. Although the actual composition of the
IWT additive is proprietary information, it appears
that its technology is similar to the approach using
organophilic clays. In addition to the chemical
bonding, IWT also claims that some of their additives
break down the contaminant to harmless
compounds.
Stabilization/Solidification Technologies
and Superfund Response Actions
Section 121 (Cleanup Standards) of the Superfund
Amendments and Reauthorization Act (SARA) of
1986 requires that remedies both be protective of
human health and the environment, and be cost-
effective. SARA states a strong preference for
remedies that are highly reliable and provide long-
term protection. The statute also states a preference
for remedial actions that employ treatment that
permanently and significantly reduces the volume,
toxicity, or mobility of hazardous waste.
Stabilization/solidification is one of the treatment
technologies with the potential to meet the cleanup
standards.
Stabilization/solidification has been selected at
numerous Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA) sites to
reduce waste toxicity or mobility. (The SITE
program demonstration of the IWT and Geo-Con
technologies was conducted at a closed electrical
service shop in Hialeah, Fla., which was not a
CERCLA site.) A comprehensive list of sites for
which stabilization/solidification has been chosen is
beyond the scope of this document. However, this
section discusses some of the general trends in the
use of these technologies for CERCLA actions, gives
some examples of site remediations involving
stabilization/solidification and discusses the
potentially applicable or relevant and appropriate
requirements (ARARs) for the use of
stabilization/solidification at CERCLA sites.
Use of Stabilization/Solidification
Both immediate removal activities and remedial
actions under the CERCLA program have used or
will use some type of stabilization/solidification.
Between fiscal years (FY) 85 and 88, at least nine
removal actions involved stabilization/solidification,
usually using lime or kiln dust to treat waste
sludges. As of the end of FY88, stabiliza-
tion/solidification had been selected as a cleanup
remedy in 38 Records of Decision (RODs) for
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National Priorities List (NPL) sites. Eighteen of
these RODs were signed in FY88.
Of the CERCLA sites for which stabiliza-
tion/solidification has been selected or used, the
method has typically been applied to wastes (usually
sludge, sediment, and surrounding soil) that are
acidic or contain heavy metals. For instance,
stabilization/solidification was selected to treat soil
and sediments contaminated with metals at the
following NPL sites: Sapp Battery in Florida,
Marathon Battery in New York, and Independent
Nail in South. Carolina. As the use of incineration
increases, stabilization/solidification may be selected
to treat residual ash, if the ash requires further
treatment to reduce the mobility of metals prior to
redisposal onsite. This application of
stabilization/solidification was chosen for the Geiger
(C&M Oil) site, South Carolina. Stabilization has
also been selected to treat soil contaminated with
radioactive waste at the Denver Radium site in
Colorado.
In addition, stabilization/solidification has been
selected to treat wastes containing organic
compounds. In an application similar to Hialeah, in
1986, stabilization/solidification was selected in the
ROD for the Pepper Steel and Alloys, Inc. site in
Florida for treatment of soil contaminated with
PCBs and heavy metals. The cleanup occurred in
1988, when the soil was excavated, separated from
debris, and mixed with Portland cement before being
returned "to the excavated area of the site. Like the
Hialeah site, the site is sandy and overlies a shallow
aquifer (4 to 5 ft below land surface). Other sites
where stabilization/solidification was selected to
treat organics include: York Oil in New York, to
treat soil and sediment contaminated with metals,
petroleum hydrocarbons and low concentration of
other organics, including PCBs; Fields Brook in
Ohio, to treat sediments containing metals and
organics, including PCBs; Liquid Disposal Landfill
in Michigan, to treat soil and waste containing heavy
metals and organics, including PCBs; Industrial
Waste Control in Arkansas and Bailey Waste
Disposal in Texas, to treat soil containing organics;
and Chemical Control in New Jersey to treat soil
containing heavy metals and organics.
To date, no CERCLA cleanup has selected the in situ
application method offered by IWT and Geo-Con and
tested in this SITE demonstration. In most of the
examples listed above, the application method for the
stabilization/ solidification reagents was not
specified in the ROD and was to be addressed in the
design phase of the remedial action. The two most
frequent types of stabilization/solidification
treatment are bulk mixing in a pit and excavation
and treatment in a tank. However, in situ
stabilization/solidification was specified in the ROD
for the Chemical Control site because of the small
size of the site and other engineering difficulties.
Role of Stabilization/Solidification in the Future
Currently, many stabilization/solidification vendors
use additives (such as dispersants and organophilic
proprietary compounds) in conjunction with setting
agents to improve the ability to bind organics to the
solid product. Because of the availability of these
new mixtures, stabilization/solidification may be
considered more frequently to treat soil
contaminated with organic compounds, alone or
together with metals. In addition to the IWT and
Geo-Con technologies, the SITE program is
evaluating stabilization/solidification methods
offered by five other vendors. These additional
demonstrations all involve soil and sludge
containing organic compounds as primary
contaminants, such a-s solvents, PCBs, petroleum
hydrocarbons, and coal tars. The demonstration of
the IWT and Geo-Con technologies is the only SITE
project to date involving in situ
stabilization/solidification.
Evaluation of the effectiveness of available
stabilization/solidification processes for a specific
site and waste requires bench-scale testing, in which
small samples of the waste and reagents are mixed
and allowed to cure. The treated samples are then
subjected to physical and chemical tests such as
those described in Section 3 of this report. Bench-
scale tests can also assess the potential for emissions
of volatile compounds during the mixing process,
which often involves the release of heat during
reactions between the waste and the additives.
Bench-scale testing of stabilization/solidification is
currently being implemented during the feasibility
study and design phases at many CERCLA sites. It
should be noted that the tests available to evaluate
this technology do not directly measure its long-term
effectiveness.
Regulatory Considerations
CERCLA Section 121(d) requires onsite Superfund
remedial actions to comply with federal, and more
stringent state environmental requirements that are
determined to be ARARs. The current NCP requires
onsite removal actions to comply with federal
ARARs to the extent practicable. Two sets of federal
regulations that are potential ARARs for in situ
stabilization/solidification of PCB waste are the
Land Disposal Restrictions (LDRs) under the
Resource Conservation and Recovery Act (RCRA)
and the PCB waste disposal regulations under the
Toxic Substances Control Act (TSCA). The
regulatory requirements are discussed in more detail
in Section 3 of this report. Regardless of which
-------
regulations are ARARs, all Superfund cleanups must
be protective of human health and the environment.
Stabilization/solidification is not now considered a
best available demonstrated technology (BOAT) for a
RCRA hazardous waste that contains organic
contaminants and is subject to the LDRs. OSWER
Directive 9347.1-02 (Apr. 17, 1989) states that for
the LDRs to be applicable, the CERCLA response
action must constitute placement of a restricted
RCRA hazardous waste. Placement does not occur if
wastes are moved within a unit or are left in place.
Therefore, in situ treatment, such as for the
stabilization/solidification process using IWT and
Geo-Con technologies, does not involve placement,
and the LDRs are not applicable.
Key Contacts
For more information on the demonstration of the
IWT/Geo-Con technology, please contact:
1. EPA Project Manager, concerning the SITE
demonstration and the Hialeah, Fla. site
Ms. Mary K. Stinson
Risk Reduction Engineering Laboratory
GSA Raritan Depot - Bldg. 10
Edison, NJ 08837
(201) 321-6683
2. International Waste Technologies concerning
the process.
Mr. Jeffrey Newton
150 N. Main St.
Suite 910
Wichita, KS 67202
(316) 269-2660
3. Geo-Con, Inc. concerning the deep-soil-mixing
equipment.
Mr. Brian Jasperse
P.O. Box 17380
Pittsburgh, PA 15235
(412) 856-7700
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Section 3
Technology Applications Analysis
Introduction
This section of the report addresses the applicability
of the IWT in situ stabilization/solidification
technology using the Geo-Con/DSM equipment to
remediate various feedstocks based on the results of
the SITE demonstration and other IWT and Geo-Con
data. Since the results of the demonstration provide
the most extensive database available, conclusions
on the effectiveness of the process and its
applicability to other potential cleanups will be
strongly influenced by those results. These are
presented in detail in the Technology Evaluation
Report. Additional information on the IWT and Geo-
Con technologies -- including a process description,
vendor claims, a summary of the demonstration
results, and summaries of outside sources of data -
are provided in Appendices A-D.
To evaluate the combined technologies of IWT and
Geo-Con, the following technical criteria were used:
Ability of the IWT additive to immobilize PCBs
and other contaminants.
Durability of the solidified, treated soil mass ~
which is indicated by results obtained from
many of the physical property tests.
Ability of the Geo-Con DSM equipment to blend
a cementitious additive with contaminated soil.
Following are the overall conclusions being drawn on
the IWT and Geo-Con technologies. The Technology
Evaluation subsection discusses the available data
from the demonstration and IWT studies. It also
provides more detailed conclusions and discussion of
applicability of the IWT and Geo-Con in situ
stabilization/solidification process. This is followed
by subsections covering federal regulations, waste
characteristics and performance of the technology,
materials handling, personnel issues and procedures
for evaluating stabilization/solidification.
Conclusions
The conclusions stated for this in situ stabiliza-
tion/solidification technology are drawn primarily
from the demonstration, but were also supplemented
by information provided by IWT and LE on
laboratory studies. The conclusions are:
PCBs do appear to be immobilized by the
process, based upon TCLP leach test and
physical test results. However, for most of the
tests, PCB concentrations in the soil were
relatively low (<500 mg/kg), and the leachate
concentration levels were low and very close to
the analytical detection limits. Thus,
confirmation of this conclusion is not possible.
In addition, the data that IWT provided were
for posttreatment soil leachates only and a
determination of immobilization is not possible.
From laboratory studies provided by IWT (both
leach tests and more sophisticated tests to prove
chemical bonding) immobilization of volatile
and semivolatile organics appears possible, but
since pretreatment leach tests were not
performed, confirmation is not possible. The
demonstration did not provide sufficient data
points to allow any conclusions to be drawn.
(IWT claims that their additive was not
designed for VOCs.) However, IWT claims the
HWT-20 additive contain organophilic clays,
and the literature [6] indicates that bonding of
organics to some treated clays does occur, thus
immobilization appears possible.
Immobilization of heavy metals is probable.
However, insufficient data are available from
IWT or the demonstration to provide
confirmation. Cement-based systems are
usually effective on heavy metals, and the
reported treated soil leachates for the IWT
technology are low - in most cases less than 100
ug/L.
IWT's primary study efforts are to develop
additives that chemically bond to the
contaminants, and most of its test work is
related to confirming this. However, the
demonstration was not designed to prove this,
thus no conclusions related to chemical bonding
are offered.
-------
Physical properties of treated soil samples - in
each case for samples of very low organics
content (<1.6 wt%) were generally
satisfactory, except for the freeze/thaw
weathering tests, which were performed only
during the demonstration. The UCS values
were high (300-500 psi), the permeabilities
were satisfactory (10-6 to 10-7 Cm/s), and the
volume increase, due to the addition of HWT-20
additive, was low - about 8.5% during the
demonstration. The microstructural analyses
showed a dense, homogeneous and low-porosity
structure, which with the other results obtained
(if the freeze/thaw difficulty can be corrected by
IWT as they claim) indicates that the solidified
mass has the potential for long-term durability.
These physical results, where comparisons can
be made, are approximately equivalent to test
results where cement was substituted for HWT-
20 during the demonstration.
The Geo-Con/DSM equipment appears to work
well and to provide intimate mixing of additive
and soil. Geo-Con and various Japanese
vendors have used in situ injection to
consolidate soils, construct slurry cut-off walls,
etc. in all types of soils, thus, the equipment has
a proven capability of use in a wide variety of
soils and applications.
Applications of this in situ process for
immobilization of PCBs, heavy metals and volatile
and semivolatile organics at low organics content in
the soil seems possible especially for the heavy
metals. Even for high-organic-content wastes - up to
25 wt% ~ immobilization may be possible. However,
physical properties of treated soil in cement-based
systems start to deteriorate at about 10 wt% organics
in the untreated soil. Therefore, since only very
limited bench-scale studies have been performed and
there is no field work at the higher organic levels, it
is recommended that treatability studies (for both
chemical and physical characteristics) be performed
on each waste, whether low or high in organic
content
As for the use of the Geo-Con DSM equipment, few
limitations appear to exist. The DSM equipment, and
similar units in Japan, can operate in most soils and
in most climates, to a depth of more than 100 ft.
However, some limitations may exist:
« A volume increase is expected which may cause
difficulties in restricted areas where land
contours would be seriously altered. Also, for
high-organic-content wastes, where the IWT
additive rate would be increased, the larger
volume increase would be of even more concern.
Soil debris, such as large rocks and buried
drums, would probably have to be excavated
before auger injection. Special injection
equipment should be used for deeper obstacles.
Very low ambient temperatures (below 10°F)
may cause freezing of the feed slurry before
injection.
Evaluation of Performance
The criteria defined in the SITE Program
Demonstration Plan [7] to evaluate the IWT and
Geo-Con in situ stabilization/solidification
technology are:
Immobilization of PCBs as determined from
leaching and permeability tests.
Long-term durability of the solidified soil, as
determined from various physical tests such as
UCS, weathering (wet/dry and freeze/thaw),
and microstructural analyses (microscopy and
X-ray diffraction).
Reliability and versatility of the mechanical
equipment.
The above criteria are a direct approach to the
evaluation of the effectiveness of the technology
before and after treatment. A separate research
project to support the IWT findings of chemical
bonding between additive and contaminant was
outside the scope and intent of the commercial scale
SITE demonstration. The reaction mechanisms do
help to explain the direct results obtained and also
provides insight for extending the results to other
applications. A separate research program would
have complemented the demonstration. The
following discussions, using the available IWT and
Geo-Con information, will provide more detailed
conclusions on the process, particularly as related to
the various physical and chemical properties of the
treated soil.
Chemical Test Results
The chemical analyses of soil and leachates, provide
information in evaluating the immobilization of the
various contaminants. Leaching tests indicate the
chemical stability of the solidified mass [8], its
tendency to leach by water, and the mobility of
contaminants contained in the solidified waste when
they are in contact with aqueous solutions. To
properly evaluate immobilization, both pretreatment
and posttreatment soil and leachate analyses are
required. The most extensive chemical analyses,
measuring both the waste and leachate
compositions, before and after treatment, were
10
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performed as part of the SITE demonstration. Data
are also available from laboratory studies of IWT and
from the laboratory formulation studies by LE for
GE, using electric-service-shop soil. Most of this
work was related to PCBs, although some laboratory
studies were performed by IWT on metals, volatile
organics, and semi-volatile organics. Since it is
important to know the quantity of the contaminants
in the untreated and treated wastes when
performing a leach test, the most complete
information is available from the demonstration
where both analyses were performed. Some before
and after treatment leach test results were
performed by LE [1].
During the demonstration, the IWT in situ
stabilization/solidification process appeared to
immobilize the PCBs, which are relatively immobile
contaminants, even without treatment.
Unfortunately, due to the relatively low levels of
PCBs measured in the soil at the Hialeah site
(maximum 950 mg/kg untreated and 170 mg/kg
treated) during the test, which produced leachates
close to their detection limit (0.1 ug/L), more
information at higher PCB concentrations in the
wastes is required to confirm immobilization.
Law Environmental treated in the laboratory soil
samples containing 83, 1,130, and 5,628 mg/kg PCBs
in the untreated soil, with varying amounts of HWT-
20 - from 0.05 to 0.25 Ib/lb dry soil (see Appendix D-
1). Four different leach tests were performed on both
the untreated and treated soils -- three versions of
the Extraction Procedure Toxicity (EP Tox), and the
Toxicity Characteristic Leaching Procedure (TCLP).
One EP Tox test version used the standard
membrane filter; prior experience has shown that
PCBs absorb onto the filter and provide low,
erroneous values. The other two versions used a
glass fiber filter, one using site water and sulfurous
acid to reduce the pH to 5.0, and the other using the
standard acetic-acid leach medium.
The results of these tests showed the following:
For 'the low-PCB-concentration soils,
untreated-soil leachate values, using only the
standard EP Tox with a membrane filter, were
below the detection limit (1.0 ug/L).
For the medium-PCB concentration soils (1,130
mg/kg), 58% to 94% concentration reductions
(using the glass fiber filter) were seen, with the
treated-soil leachate concentrations in the
range 2.6 to 10.0 pg/L. These values did not
relate to the additive rates, which were in a
narrow range of 0.15 to 0.18 Ib/lb dry soil.
For the high-PCB-concentration soils (5,628
mg/kg), 0% to 90% concentration reductions
(using the glass fiber filter) were seen, with the
treated-soil leachate concentrations in the
range < 1 .to 98 ug/L. The treated soil leachate
value of 98 ug/L was with an additive rate of
0.05 Ib/lb dry soil. At the higher additive rates
of 0.15 and 0.25 Ib, the leachate values ranged
from <1 to 32 ug/L,. which is a concentration
reduction of 51% to 90%.
For the TCLP results, the treated-soil leachate
values for all five samples from low to high
soil-PCB levels were greater than the
untreated-soil leachate values. LE had no
confirmed explanation for this, and suggested
that possibly the leaching fluid (Fluid #2 with a
pH of 2.8) was the cause. The TCLP was
developed to overcome the shortcomings of EP
Tox for the leaching of organics, and therefore,
it would be expected to provide more
satisfactory results. Nevertheless, based on
available leach test results, the studies
performed by LE for GE using HWT-20 did not
show immobilization of PCBs.
For each of the three EP Tox tests, LE found a
relationship between the PCB concentration in the
leachate and the ratio of HWT-20 additive to water.
It found the curve went though a minimum at an
additive-to-water ratio of 1.0-1.5. This result was
likened to the optimum moisture content for cement,
which might tend to confirm the validity of the EP
Tox results versus the TCLP values.
In a second group of samples, LE mixed HWT-20 as a
slurry with the soil, instead of mixing it dry. The
additive was mixed in concentrations of 0.12 to 0.20
Ib/lb dry soil. Untreated soil concentrations of PCBs
were in the range of 893-3,944 mg/kg. Treated soil
leachates (using EP Tox with glass fiber filter)
ranged from 2.4-4.5 ug/L. One untreated soil sample
with a PCB concentration of 5,719 mg/kg had a
leachate concentration of 11.0 ug/L. A table of results
is included in Appendix D.
If the TCLP results are discarded, the EP Tox results
from the LE work show immobilization of PCBs.
However, based on the LE report, there is not a valid
reason to eliminate the TCLP results. Thus, the LE
work is inconclusive on the ability of HWT-20 to
immobilize PCBs. See Appendix D-l for more
detailed information.
IWT performed some laboratory experiments before
the demonstration. One was at very high PCB
concentrations in a soil like at Hialeah 28,800
mg/kg the other at a moderate value 290 mg/kg
the same order of magnitude as some untreated soils
in the demonstration. After treatment for the high
concentration soil - 0.20 Ib HWT-20/lb dry soil -
only 10 wt% PCB could be extracted by methylene
11
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chloride solvent. In addition, IWT reported a TCLP
leachate value of 12.5 mg/L, and very high levels of
chlorinated benzenes in the soil, which they
attributed to the decomposition of PCBs. In the other
test, the additive rate was 0.15 Ib and only two-thirds
of the PCBs could be extracted by a solvent. Also,
volatile organics measured in the untreated soil were
not detected in the treated soil. Thus, it was
concluded by IWT that HWT-20 was bonded to the
PCBs, which seems a reasonable possibility. It
should be noted that the only chlorinated benzene
(chlorobenzene) measured during the demonstration
existed in the same proportion to the other VOCs in
both the untreated and treated soil, so this IWT
observation was not confirmed.
During the demonstration, GE collected and
analyzed samples from two locations in Sector B and
two locations just south of Sector B. The samples
outside the sector (by 1 ft and 2 ft) showed no
consolidation, indicating that the HWT-20 additive
did not spread beyond the test sector, and leach tests
were not performed. For the other two groups of
samples, one was near Sample Location B-20 in an
area where column overlap (see Appendix A for more
information) was poor and the other was near
Sample Location B-21. Samples were collected at six
depths (maximum 17 ft) at each location. These
treated soil samples were analyzed for PCBs. TCLP
leach tests were performed approximately 3 weeks
after the soil samples were collected, thus allowing a
3-week curing period. The results are shown in Table
1, with a summary of the data sheets from the
laboratory report provided in Appendix D-3.
Table 1. Posttreatment Soil and Leachate Analyses of
Samples Collected by GE
Location PCBs in soil, PCBs in TCLP
near Depth, ft mg/kg leachate,
B-21
B-21
B-21
B-21
B-21
B-21
B-20
B-20
B-20
B-20
B-20
B-20
3.0 - 3.6
5.0 - 5.75
7.0 - 7.8
9.5-11.0
12.5 - 14.0
15.5 - 17.0
1.5 - 3.0
3.0 - 4.5
6.0 -. 7.4
7.4 - 9.0
10.5 - 12.0
13.5 - 15.0
34.9
182.0
206.0
166.0
32.9
13.7
22.8
47.7
72.7
57.4
2.0
1.0
1.20
<0.10
0.22
0.12
<0.10
0.11
<0.10
<0.10
<0.10
<0.10
<0.10
<0.10
In the area where treated soil columns overlapped
poorly, the PCB concentration in the soil ranged
from 1.0 to 72.7 mg/kg, with the maximum value at a
depth of 6.0-7.5 ft. All corresponding leachate results
were below the detection limit of 0.1 ug/L. For the
samples near Location B-21, where the overlap was
satisfactory, the PCBs in the soil ranged from 13.7 to
206 mg/kg, with the maximum value at a depth of
7.0-7.8 ft. In this area, the PCB concentrations in the
TCLP were above the detection limit at 4 of the 6
depths. The maximum TCLP leachate-concentratiori
was 1.2 ug/L at a depth where the soil concentration
was about 35 mg/kg PCBs. The next highest leachate
value was 0.22 ug/L, which occurred for soil at the
highest concentration value. At the second-highest
soil value of 182 mg/kg PCBs, the leachate
concentration was below the detection limit. These
results showed that the more properly treated soil,
although higher in PCB concentrations, showed
detectable quantities of PCB in the TCLP extracts,
while for the area of poor overlap, all leachates had
PCB concentrations below detection limits. The data
are similar to the demonstration values and,
although very low, do not clarify whether the IWT
process immobilized PCBs.
Prior to the demonstration, EPA performed tests on
samples previously prepared by LE as a preliminary
evaluation of the technology. The 3 samples tested
had PCB concentrations ranging from 4,100 to 5,700
mg/kg. They were prepared from a batch of untreated
soil with a PCB concentration reported by LE as
5,628 mg/kg. This indicated that the HWT-20
neither degraded or bonded to the PCBs. The 3 TCLP
leachates each had PCB concentrations below the
detection limit of 1.0 ug/L, which would support the
possibility of PCB immobilization.
Thus, using all available sources, it appears that
some data show immobilization of PCBs, while other
data are inconclusive. Therefore, although it appears
that the IWT additives may immobilize PCBs, the
results are not conclusive.
Additional information is provided by IWT on
various laboratory studies it has performed, which
were presented in informal papers it has distributed.
A copy of the most recent one was provided for the
Vendor Claims section, Appendix B. Other papers
are summarized as Appendices D-4 and D-5. The
results presented provide various TCLP leachate
results, after treatment only, for volatile organics,
semi-volatile organics and heavy metals. In addition,
tests using hexane and methylene chloride
extractions were performed, to show that bonding of
the contaminants to the additive occurred. If the
organic contaminants are chemically bonded to the
additive, the ability to extract them, even with an
efficient solvent, is reduced. It would then follow that
these organics may be immobilized.
Many examples are cited by IWT on its ability to
immobilize volatile and semivolatile organics. In
most cases, wastes containing up to 10,000 mg/kg of
12
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an individual organic were reduced to less than 2
mg/L, with many values below detection limits.
However, the detection limits are not defined, and
corresponding values for untreated waste leachates
do not exist. If the detection limits were tens or
hundreds of parts per billion, then immobilization
may have occurred. In one example, where the waste
contained 26,500 mg/kg xylenes, the leachate value
was 4,605 mg/L, which is very high. After adjusting
the additive formulation, the value was reduced to 48
mg/L, which is still large and may not differ
significantly from a TCLP leachate value for
untreated waste. Thus, the ability of the IWT
additive to immobilize VOCs or semivolatiles cannot
be clearly determined from the limited leach test
data available.
Leachate values for metals were below 1.0 mg/L in
almost all cases reported, with most of them below
0.1 mg/L, which may meet existing regulatory
standards for land disposal restrictions and delisting.
However, in all tests, the concentration in the wastes
was tens or hundreds of parts per million, which is
not large. Since TCLP leachate values for untreated
soils were not provided, except during the
demonstration immobilization of the metals cannot
be determined from the available data. However,
most cement-based additives can immobilize heavy
metals, so it is reasonable to believe the IWT
additives also have the capability.
Chemical Bonding Tests-
Currently the most extensive studies by IWT, which
were outside the scope of the demonstration,
[9,10,11] are the tests to prove that its additive bonds
to, or destroys, the organic contaminants (see
Appendix D-6). If bonding occurs, even if the forces of
attraction are weak, the mobility of the contaminant
is reduced and the physical integrity of the treated
waste may become less important, since bonding, as
well as encapsulation, will prevent contaminant
mobility. If this research is successful, the IWT
technology might meet many of the current or
potential regulations for both organics and metals
(where reductions in the contaminant concentration
in the wastes are measured). Various tests have been
used in attempts to prove this claim, such as direct
extraction with an organic solvent, Fourier
transform infrared (FTIR), and differential scanning
calorimetry (DSC). These tests, and the protocol to
evaluate the process try to show bonding in the
following manner:
Solvent Extraction
During sample preparation for analyses of VOCs and
semi-volatiles, the organics are extracted from the
waste by hexane and the quantity is measured by gas
chromatography/mass spectrometry (GC/MS). If
bonding occurs, the solvent may not extract all of the
contaminant and it will appear to have a reduced
concentration level. If hexane does not extract the
toxin, water in most cases will not either. The tests
reported by IWT have shown reduced concentration
levels of contaminants after treatment with HWT
additives.
FTIRShifts in infrared vibrational frequencies of
organic bonds occurred after treatment, showing a
change in bond length between atoms. This indicates
that weak bonding has occurred. Even weak bonding
of this type should reduce the mobility of the
contaminants.
DSCThis procedure measures the changes in
temperature and energies required to release the
contaminants from the soil matrix before and after
treatment. If for example, the heat of vaporization
increases, compared to the pure compound not in the
solid matrix, as shown for the IWT additive [10], this
indicates a bond may exist, restraining the release.
IWT also claims that there is a breakdown in the
organic molecules to smaller molecules, and that the
energy for release of the organics increases.
However, elevated temperatures are required when
performing a DSC analysis, and clays (which are
aluminosilicates related to zeolites, a known
catalytic group) are known to catalyze many organic
reactions. In proving chemical bonding or
degradation, the key is whether these reactions
occurred before heating; there is no evidence
provided to this effect.
Evidence from solvent extraction and FTIR studies
suggests that weak bonding probably occurs between
many contaminants and the IWT additive. However,
the basic IR spectra of the organics were observed in
mixtures of HWT-20 and organics, with only modest
frequency shifts. In addition, the extraction results of
IWT showed only partial recovery of unaltered
organics. However, the demonstration results and
LE tests showed no evidence of PCB or VOC
degradation. Thus, it is likely that the various IWT
additives can reduce the mobility of many organic
contaminants.
Physical Test Results
The physical tests - UCS, weathering (wet/dry and
freeze/thaw), and permeability -- provide
information on the potential durability of treated
waste. Permeability is also a strong factor
influencing contaminant mobility. However,
quantitative relations between the time the
solidified mass can maintain its integrity and the
test results (including microstructural observations)
do not exist.
The most extensive physical testing on the IWT
process was performed in the SITE project and
reported in the Technology Evaluation Report [12].
This not only included the demonstration results, but
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"screening test" results [13] on samples provided by
LE to obtain a preliminary evaluation of the
technology. The only additional information
provided by IWT are data obtained by Law
Environmental for GE in 1986 on laboratory
prepared samples (using the same electric-service-
shop soil) and from core samples taken from Sector B
shortly after the demonstration. Thus, all physical
test data are based on soil with a very low organic
content from one small plant location. As a result,
information on physical properties exists for only a
very narrow range of contaminated soils.
Unconfined Compressive Strength-
Unconfined compressive strength is a primary
indicator of durability of solidified wastes. The
results of the samples taken from Sector B and C
show very satisfactory strengths for the solidified
material relative to EPA's guideline minimum of 50
psi [3] for stabilization/solidification systems. The
results ranged from 75 to 579 psi in Sector B and 247
to 866 psi in Sector C. Results on laboratory prepared
samples by LE, with additive concentrations
between 0.10 Ib HWT-20/lb dry soil and 0.25 Ib
HWT-20Ab dry soil, ranged from 198 to 2,127 psi (see
Appendix D-2 for more details). The moisture
contents of the laboratory-treated soil samples (2.8
wt%-13.6 wt%) were considerably lower than for the
average of the field samples (18 wt%). The higher
UCS values for the LE samples were at the higher
moisture levels. The data does not show a definitive
trend of UCS versus additive dosage rate at either
high or low moisture content. It is possible that the
samples with very low moisture content were
incompletely hydrated, thus weakening the cement
matrix. Another potential factor affecting UCS (not
observed) is the degree of uniformity of the soil-
additive mixing. This would probably favor the
laboratory results, where the mixing should be
better than that obtained in the field.
Three samples from a second batch of site soil, which
were prepared by LE [14] using the additive in a
slurry form (compared to the earlier formulations
using dry additive addition), were tested by EPA
during the Technology Screening Tests [13]. They
produced UCS values of 418-1,185 psi for treated-
soil moisture contents in the range of 8.6 wt%-16.1
wt%. Laboratory formulations during the
demonstration by NUS Corp., the laboratory
analyses contractor, using site soil with Type 1
Portland cement substituted for HWT-20 at 15 wt%
and 20 wt% cement - produced equivalent results at
approximately the same moisture levels. Thus, the
HWT-20 produces UCS values equivalent to using
cement.
All these UCS results for soil with a very low
organics content are quite satisfactory compared to
the EPA guideline minimum of 50 psi. Cement-based
waste treatment systems are typically in the range of
15-150 psi [4], although a comparison may not be fair
without knowing the weight of additives used or the
organics contents of the waste. High UCS values
imply the potential for maintaining structural
integrity for many years. In conclusion, the UCS
values are quite good and indicate a potential for
long-term structural integrity.
Permeability-
Permeability (also called hydraulic conductivity)
indicates the degree to which the material permits
the passage of water, and is thus one measure of
potential for contaminants to be released to the
environment. It would also be a factor in estimating
the potential for long-term durability of the treated
waste. Permeability depends on the solidified
material's density, degree of saturation, and particle
size distribution, as well as pore size, void ratio,
interconnecting channels and the liquid pressure.
Except for one value obtained by LE [13] and 3
values obtained during the EPA screening tests all
values available are from the demonstration. The
demonstration values averaged about 4xlO-7 cm/s,
while the screening tests averaged 2.7x10-8 cm/s, and
the one value in the LE laboratory tests was 7.6x10-8
cm/s. Thus, it appears that the field data are an order
of magnitude higher than the laboratory data. All
the treated values are very low compared to the
untreated soil values, which averaged about 3xlO-2
cm/s. As a point of reference, cement systems usually
can attain permeabilities of 10-5 to 10-6 Cm/s [15].
Therefore, it is concluded that the IWT process can
produce a solidified mass of low permeability, which
is marginally acceptable when compared to the EPA
criterion of 10'7 cm/s - the value targeted for soil
barrier liners for landfills used for hazardous waste
disposal. In addition, this large decrease, compared
to the untreated soil, indicates that the groundwater
will flow around, not through, the treated block.
Thus, if only one large mass is produced, the
contaminants will remain isolated from the
groundwater as long as the durability of the
monolith is maintained.
Weathering-
Weathering effects can break down the internal
structure of the solidified soil, producing potential
paths for water flow, which would increase
permeability and the potential for contaminant
leaching and weaken the solidified mass.
' Weathering tests, which are more severe than field
conditions in terms of the rate and degree of
temperature change, only provide an indication of
the short-term (12 cycles) treated-soil integrity in
the face of natural weathering stresses. The tests are
recommended as a means of comparing weathering
performance of different processes, but cannot be
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used to predict the long-term durability of solidified
masses.
Twelve-cycle wet/dry and freeze/thaw tests were
performed during the demonstration for all treated
soil samples. The average of the cumulative relative
weight-losses between test specimen and control for
the 37 wet/dry tests was approximately 0.1%, with
the absolute weight losses of the test specimens less
than 0.4%. For the 38 freeze/thaw tests, the average
cumulative relative weight loss was 6.3%, with the
absolute weight loss of the control specimens
approximately 0.3, the same as for the wet/dry tests.
Freeze/thaw weathering tests, although not of
concern at the Hialeah site, are of concern in more
northerly climates. The results are of concern
because of the recognized potential for frost damage
of concrete structures. The test uses a greater rate of
cooling than the maximum of about 5°F/h that is
expected in nature. In addition, the tests are carried
out on specimens that are nearly water saturated,
where the water can rapidly freeze and cause
fracturing of the solidified waste, increasing the
permeability of the solidified mass. Relatively dry
concrete (such as that used for above-grade
structures such as buildings) below 80% of
saturation level is less likely to fracture than
saturated material.
Tests for UCS were performed on approximately one-
half of the test specimens and controls after the 12
weathering cycles. For all the controls and wet/dry
specimens, the UCS results were comparable to the
unweathered values. However, for the freeze/thaw
test specimens, when the weight loss exceeded 3%,
UCS values deteriorated, approaching zero at about
10% weight loss. Permeabilities performed on
wet/dry and freeze/thaw test specimens showed no
apparent increases compared to unweathered
specimens, although freeze/thaw samples with high
weight losses 10% and above were not tested.
Therefore, it can be concluded that the IWT process
will maintain its integrity through wet/dry cycling.
However, freeze/thaw cycling produces severe
degradation of the solidified mass. Without
formulation changes in the additive (which IWT
claims they can accomplish), severe problems might
be encountered with this process in cold climates. A
scheduled long-term monitoring program exists,
during which the treated soil will be sampled
annually. This will provide additional information
on durability of the solidified mass. The first long-
term sampling occurred in April 1989.
Bulk Density-
Bulk densities were measured on all pretreatment
and posttreatment samples from the demonstration.
Some other posttreatment values were provided by
GE (all on samples prepared by LE for GE) from the
first laboratory studies reported by LE, and from the
screening tests performed by the EPA.
For the demonstration, the bulk density increase
with treatment was quite satisfactory. The average
density gain was 21%, changing from 1.55 g/mL (96.7
Ib/ft3) to 1.88 g/mL (117.3 Ib/ft3) for a 32% increase
(HWT-20 plus water) in mass. The results of the 3
treated-soil samples provided by GE and measured
by EPA during the screening tests were comparable
to the samples from the field, and averaged 1.83
g/mL (114.2 Ib/ft3). The earlier laboratory
formulations with additive dosage rates of 0.10 to
0.25 Ib HWT-20/lb soil - ranged from 1.48 mg/L (92.3
Ib/ft3) to 1.86 g/mL (116.0 Ib/ft3). These latter
samples had a moisture content ranging from 2.8
wt% to 13.6 wt%, with the lowest bulk-density values
at the highest moisture content. Both groups of test
specimens were lower in moisture content than the
posttreatment field samples. For the samples
described above, untreated-soil bulk densities were
not performed. Therefore, it is concluded that a
significant bulk-density increase on soil treatment;
about 20% is likely at an additive dosage of 0.17 Ib/lb
of dry soil; and a small but significant volume
increase occurs.
Based on all the physical test results performed on
IWT treated-soil samples, it would be expected that a
potential for long-term integrity of the treated soil
exists if the problem for freeze/thaw degradation is
overcome.
Microstructural Results
Optical microscopy, scanning electron microscopy,
and X-ray diffraction analyses were performed on
untreated- and treated-soil samples during the SITE
demonstration. These methods are commonly used
techniques for understanding the mechanism of
structural degradation of soil, cement, and soil-
cement mixtures, both with and without the addition
of inorganic and organic compounds. Relatively few
studies exist of the microstructure of complex
waste/soil mixtures such as those resulting from
stabilization/solidification procedures. Thus,
interpretation of microstructural observations may
in some cases be difficult. However, valid
information can be obtained on the potential
durability of the solidified mass. These observations
complement the weathering test results, which are
short-term measures of solidified mass integrity, and
UCS test results, which are an indirect indication of
durability. The microstructural studies provide
information on the potentials for structural changes
over the long-term, although quantitative
predictions on durability are not possible.
The results show that the solidified material has a
potential for long-term durability. The solidified
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mass is dense, homogeneous and of low porosity.
Compositional variations in the vertical and
horizontal direction, based on the consistency of the
mineral structure from sample to sample, were
absent. Thus, it appears that mixing by the Geo-Con
DSM equipment was satisfactory. It would seem that
the low porosity should reduce the susceptibility to
damage from wet/dry and particularly freeze/thaw
cycles, by reducing the quantity of water in the pores
of the solid (water in the pores would freeze and may
cause fracture). However, the test specimen
degradation occurring in the freeze/thaw cycling
tests appears to conflict with the expected
performance of low porosity solids with high
strength.
Operations
For this SITE technology, IWT was the provider of
the chemical additive, and Geo-Con performed the
remedial operations. Geo-Con was responsible for the
slurry preparation, flow control of additive and
water, and soil injection and mixing. As indicated in
Appendix B on Vendor Claims, Geo-Con has
substantial experience in shallow- and deep-soil-
mixing for contaminated soils, lagoon closures and
structural reinforcement.
Equipment operations during the demonstration
were satisfactory. Some minor operating problems,
readily fixable, were encountered, as described in the
Demonstration Report [12]. These minor difficulties
included: deviations in the location of the auger from
the designated point; a major water leak in the auger
drill head, which eliminated the supplemental water
for the last 21 soil columns; and inability to maintain
automatic feed control of the HWT-20 and water to
the auger.
Geo-Con has considerable experience in many types
of soil improvement operations. They have
constructed more than 400 slurry cut-off walls and
performed work on soil capping, lagoon and
landfilling closures, soil and sludge stabilization and
foundation strengthening. In addition, the
technology concept is used by others in the U.S. and
has been extensively used in Japan for about twenty
years.
Overall, the conclusion is that Geo-Con provides a
technology that has proven to be technically sound in
most types of soils and should be considered as a
valid option where in situ stabilization/solidification
or solidification technologies are deemed desirable.
Summary of Performance
Stabilization/solidification technologies generally
reduce contaminant mobility, particularly for toxic
metals, and increase volume. These techniques
nearly always leave some uncertainty about long-
term effectiveness, because laboratory tests can
neither fully duplicate field conditions over long
periods of time, nor establish what actually happens
to the contaminants during treatment [15,16]. This
is true for the IWT/Geo-Con in situ technology also.
It can be concluded that the overall physical
properties of low-concentration-organics soil treated
by the IWT in situ process are satisfactory. However,
some potential for durability difficulties under
freeze/thaw conditions exists. Although IWT claims
to be able to process wastes that are high in organics,
physical test data that might indicate the potential
for long-term durability do not exist. However, IWT
claims that chemical bonding is the key aspect of its
technology, and its research and additive
development is based on this approach; success in
this effort will reduce contaminant mobility even if
structural integrity of the solidified mass cannot be
maintained.
The only field experience of IWT is at the GE site in
Hialeah, Fla. For the SITE demonstration, the
ability of the HWT-20 additive to immobilize PCBs is
not conclusive. However, IWT's laboratory studies
indicate that PCBs probably can be immobilized. For
the immobilization of volatile and semi-volatile
organics and heavy metals, insufficient data exists
from the demonstration to draw any conclusions.
However, it is possible that the HWT additives
provided by IWT are able to immobilize some
organics and metals, based on some IWT laboratory
results and the fact that some treated organophilic
clays [6] with similarities to the HWT family of
additives are known to bond to organics and metals.
The Geo-Con deep-soil-mixing equipment worked
well at the Hialeah site. Along with their other
experience in related work Geo-Con offers a
technology that should be considered as a valid
option for in situ stabilization/ solidification
applications.
Environmental Regulations Pertinent to
In Situ Stabilization/Solidification
This section discusses selected EPA guidance
concerning federal environmental regulations that
may pertain to the use of in situ
stabilization/solidification of PCBs and hazardous
waste at CERCLA sites. Most of the discussion
pertains to any in situ treatment technique. It is
beyond the scope of this document to provide a
comprehensive description of all regulations that
may pertain to the implementation of these
technologies. More information on regulations
pertaining to CERCLA actions is available in the
CERCLA Compliance with Other Laws Manual [17]
and the series Superfund Land Disposal Restriction
(LDR) Guides [18-23]. Also, although the discussion
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focuses on CERCLA activities, it should be helpful to
those contemplating the use of this technology for
other remedial activities, such as those under RCRA
corrective action or RCRA closure.
In Situ vs Staged Treatment
The term "in situ" is a Latin term meaning "in a
natural or original position." The term "in place" is
often used interchangeably with "in situ." In situ
treatment describes treatment of waste that has not
been excavated. In practice, treatment may not be
feasible or cost-effective unless the waste is first
excavated, moved, or consolidated, prior to
redeposition in a location specifically designed for
treatment. Although technically this "staged" treat-
ment is not treatment in place, the same techniques
could be used, such as the application of
stabilization/solidification agents using an auger.
Staged treatment may trigger regulatory
requirements additional to those that apply to
treatment of waste that has not been excavated. For
this reason, the discussion that follows distinguishes
between in situ treatment and staged treatment. For
the purpose of this discussion, in situ treatment
refers only to the treatment of waste in place,
without prior excavation. Staged treatment is the
application of in situ techniques to waste that first
has been excavated.
The Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA)
The Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) of 1980,
as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986 provides for
federal authority to respond to releases of hazardous
substances to air, water, and land. CERCLA
authorized EPA to revise the National Oil and
Hazardous Substances Pollution Contingency Plan
(NCP)" to include responses to hazardous substance
releases. The NCP defines methods and criteria for
determining the appropriate extent of removal,
remedial, and other measures. The latest revisions to
the NCP, which reflect SARA, will be promulgated
in early 1990. Specific techniques mentioned in the
NCP for remedial action at hazardous waste sites
include solidification technology for handling
contaminated soil, sediment, and waste.
Section 121 (Cleanup Standards) of SARA requires
that remedies be protective of human health and the
environment and be cost-effective. SARA states a
preference for remedies that are highly reliable;
provide long-term protection; and employ treatment
that permanently and significantly reduces the
volume, toxicity, or mobility of hazardous waste.
Lastly, section 121 requires compliance with Federal
and State applicable and relevant and appropriate
requirements (ARARs), and provides six conditions
under which the ARARs may be waived. The
proposed NCP defines applicable requirements as
those standards, requirements, criteria, or
limitations promulgated under Federal or State law
for which the jurisdictional prerequisites fully
address the circumstances at the site or the proposed
remedial activity. Relevant and appropriate
requirements are those that, while not "applicable,"
address problems or situations sufficiently similar to
those encountered at the CERCLA site that their use
is well-suited to the site.
The discussion that follows first reviews regulatory
requirements that may be applicable or relevant and
appropriate to in situ or staged stabilization/
solidification at a CERCLA site. The guidance on
how to determine whether such requirements are
ARARs follows the discussion of each set of
regulatory requirements.
Resource Conservation and Recovery Act
(RCRA), as Amended by the Hazardous and Solid
Waste Amendments (HSWA) of 1984
Some of the regulations promulgated under RCRA
have potential application to in situ and staged
stabilization/solidification at CERCLA sites. RCRA
regulations define hazardous wastes, and regulate
their transport, treatment, storage, and disposal.
Examples of RCRA requirements that may be
ARARs for CERCLA activities include regulations
for treatment in a tank, performance of incinerators,
closure of landfills and surface impoundments, and
treatment standards for land disposal (the LDRs).
Definition of Treatment-
Under RCRA section 260.10 treatment is defined as:
...any method, technique, or process, including
neutralization, designed to change the
physical, chemical, or laiological character or
composition of any hazardous waste so as to
neutralize such waste, or so as to recover
energy or material resources from the waste,
or so as to render such waste non-hazardous,
or less hazardous; safer to transport, store, or
dispose of; or amenable for recovery, amenable
for storage, or reduced in volume.
Therefore, stabilization/solidification of hazardous
waste is considered treatment under RCRA because
it changes the chemical and/or physical
characteristics of the waste in order to render it
nonhazardous or less hazardous, or easier to manage.
The requirements for treatment of hazardous waste
fall into two general categories: treatment in a unit
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or treatment prior to land disposal. Most
requirements for treatment in a unit are unit-
specillc design and operating standards. Treatment
is regulated in the following RCRA-defined units:
tanks, surface impoundments, waste piles, landfills,
land treatment units, incinerators, and thermal
treatment units. In addition to design and operating
standards, requirements for incinerators include a
performance standard of 99.99 percent destruction
and removal efficiency (DRE) (99.9999 percent ORE
for dioxins), in the stack gas emissions.
The requirements for treatment prior to land
disposal, or the land disposal restrictions, are
concentrations of a contaminant in the waste or
waste leachate that must be achieved in order to land
dispose the waste. The LDRs are discussed in more
detail in a later section.
RCRA and In Situ Treatment-
If in situ treatment is used to treat hazardous waste
in a RCRA-regulated unit (for instance, a surface
impoundment), unit-specific standards would be
pertinent. However, in many cases in situ treatment
will be used as part of a RCRA Corrective Action or
CERCLA cleanup to treat wastes that have breached
any unit boundaries that may have existed, and unit-
specific standards would not apply.
In these cases, because wastes treated in situ are
likely to remain in place over the long term, in situ
treatment is usually governed by site-specific
cleanup standards, which are often risk based.
Cleanup standards for in situ stabiliza-
tion/solidification may take the form of permissible
levels of certain hazardous constituents in the
leachate generated from a standard test, such as the
TCLP or EP Toxicity tests. Cleanup standards may
also be expressed as concentrations of hazardous
constituents in the treated waste, rather than in the
leachate. Because most stabilization/solidification
agents do not destroy contaminants, but rather make
them less available to the environment, this
technology may have difficulty meeting a cleanup
goal based on an analysis of total waste composition.
If soil and debris are being treated, and the LDRs are
applicable, guidance for alternative treatability
variance levels and technologies may apply.
Immobilization is specified for inorganic
contaminants, and standards are expressed as
ranges of percent reductions in TCLP leachate
values. The ranges vary, but all fall between 90 and
99.9 percent. Specific variance levels for soil and
debris are given in OSWER Directive 9347.3-06FS
[23].
Since hazardous waste treated in situ will be left in
place, provisions regulating closure and post-closure
of disposal facilities for hazardous waste may apply.
Disposal or landfill closure requires capping and
post-closure care, including groundwater
monitoring, for at least 30 years. "Clean" closure of a
RCRA unit requires removal and decontamination
that would allow the site to remain without care or
supervision after closure. Hybrid closure combines
elements of landfill closure and clean closure. At this
time, draft guidance defining performance standards
for clean closure are health-based standards for
constituent concentrations determined by total
waste analysis, not leachate concentrations.
It is important to note that many in situ treatment
methods include treatment steps aboveground, such
as treatment of volatile organic contaminants
removed from the ground via in situ vacuum
extraction. Above-ground treatment steps would be
regulated by unit-specific standards.
RCRA and Staged Treatment-
If in situ treatment techniques are used to treat
waste that has been excavated and staged, RCRA
requirements, in addition to those described above,
may apply. The potential requirements would
pertain to storing and redisposing of the waste, and
include land disposal restrictions and standards for
construction and managing land disposal units.
Under certain conditions, however, such standards
would not apply during a CERCLA cleanup or RCRA
corrective action. Applicability of RCRA
requirements to CERCLA activities is discussed in a
later section.
Land Disposal Restrictions-
The RCRA land disposal restrictions (LDRs) are
potential ARARs at many CERCLA sites. The RCRA
LDRs prohibit, with certain exceptions, the land dis-
posal of hazardous wastes, unless the wastes are first
treated to standards established by EPA in RCRA
section 3004(d). EPA has promulgated regulations
for compliance with the LDRs in 40 CFR Part 268.
These regulations specify the treatment standards to
which wastes that are subject to the restrictions
("restricted waste") must be treated before being
land disposed. The standards are based on what can
be achieved using best demonstrated available
technology (BOAT). BOAT standards are typically
expressed as concentrations of waste constituents
that may remain after the waste has been treated,
but in some cases are expressed as a specific
technology.
If the LDRs apply to a CERCLA response, there are
several compliance alternatives: (1) comply with the
LDR that is in effect, (2) comply with the LDRs by
choosing one of the LDR compliance alternatives
(e.g., Treatability Variance, No Migration Petition),
or (3) invoke an ARAR waiver (available only for on-
site actions). As discussed previously, alternative
treatability variance levels and technologies have
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been established for CERCLA soil and debris waste
that are restricted from land disposal under the
LDRs.
Applicability of RCRA Requirements to CERCLA
Cleanups-
The CERCLA Compliance with other Laws Manual
provides guidance on how to determine which of
RCRA requirements are applicable to CERCLA
actions. In general, RCRA requirements are
applicable to a waste at a CERCLA site when two
conditions are satisfied: (1) the waste is a RCRA
hazardous waste, and (2) the waste is treated, stored,
or disposed of after the RCRA requirement is
effective. In general, RCRA is applicable to wastes
that were disposed after the effective date of the
RCRA Subtitle C requirements under consideration
(generally November 19, 1980), or to treatment,
storage, or disposal of hazardous waste that had been
excavated at a CERCLA site.
Placement
If "placement" has not occurred, the RCRA disposal
requirements are not applicable. EPA uses the
concept of "areas of contamination" (AOCs) to assist
in defining when "placement" does and does not
occur for CERCLA actions involving on-site disposal
of wastes. An AOC is delineated by the areal extent
of contiguous contamination. For on-site disposal,
placement occurs when, wastes are moved from one
AOC into another AOC. Placement does not occur
when wastes are left in place, or moved within a
single AOC.
CERCLA Substances vs RCRA Hazardous
Wastes-
Not all wastes or substances at CERCLA sites are
RCRA hazardous wastes. Based on the information
gathered during a CERCLA site investigation, it is
determined whether the industrial source or
physical/chemical properties of the wastes present at
the site demonstrate that the CERCLA waste is a
RCRA hazardous waste. For RCRA regulations to be
potentially applicable, there should be affirmative
evidence (e.g., manifests, records, knowledge of
process) demonstrating that the CERCLA waste is a
RCRA hazardous waste. If such evidence does not
exist, the RCRA regulations are not applicable, but
may be relevant and appropriate if the waste is
sufficiently similar to a RCRA waste listed from a
specific industry or process.
To determine whether a CERCLA waste is a RCRA
characteristic waste, site managers may test the
waste or use their knowledge of the properties of the
waste. To determine if a waste is a listed waste,
sampling alone will not be sufficient. The RCRA
listing descriptions will generally require that the
site manager know the source of the waste or its
prior use.
Applicability of LDRs-
OSWER guidance [22] stipulates that for the LDRs
to be applicable, the CERCLA response action must
constitute placement of restricted RCRA hazardous
waste. Placement does not occur, and the LDRs are
not applicable if (1) wastes are treated in situ, or (2)
wastes are excavated, stored, and redeposited, all
within a single AOC, prior to treatment.
The LDRs do apply if excavated waste from an AOC
is placed in a separate unit, such as an incinerator or
tank that is within the AOC, and then treatment
residuals are redeposited into the same AOC.
Therefore, if excavated waste is pretreated (e.g.,
neutralized) prior to redeposition, the LDRs may be
applicable. The extent of waste preprocessing that
triggers the LDRs is not well-defined at this time.
Conclusion-
Because in situ treatment does not involve
excavation or placement of the waste to be treated, it
appears that RCRA requirements would be
applicable only if the waste to be treated in situ was
found to be a RCRA hazardous waste, and the
hazardous waste was disposed after the effective date
of the RCRA requirements. In these limited cases,
although stabilization/solidification is considered
treatment under RCRA, most RCRA standards are
unit-specific design and operating standards, and do
not directly pertain to in situ treatment. The RCRA
requirements that are most likely to be ARARs for in
situ treatment of hazardous waste are related to the
long-term management of the area treated, such as
requirements governing closure and post-closure. In
most cases, in situ treatment in general will be
subject to site-specific cleanup standards.
If wastes are staged prior to solidifica-
tion/stabilization treatment, RCRA requirements
would apply only if (1) the wastes were RCRA
hazardous wastes, and (2) the wastes were moved
outside the AOC for storage or redisposal. In these
cases, additional applicable requirements may
include design and operating standards for the land-
based unit, as well as the LDRs.
Toxic Substances Control Act (TSCA)
The disposal of PCBs and PCB-contaminated
materials, at concentrations of 50 ppm and greater,
and wastes resulting from uncontrolled discharges of
such materials, are regulated under the provisions of
the Toxic Substances Control Act of 1976. Materials
containing PCBs at any concentration also may be
regulated under RCRA if mixed with RCRA waste.
The TSCA regulations, which are found in 40 CFR
761.60, address disposal requirements in relation to
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the concentration of the PCBs in the waste. PCBs in
concentrations greater than 500 ppm must be
disposed by incineration. Wastes containing PCBs in
concentrations of 50 to 500 ppm may be disposed of
either by landfilling, incineration, or an approved,
nonthermal alternative. These requirements are
potentially applicable to any waste containing PCBs,
even if other contaminants are present.
Several states and local governments may also have
their own PCB requirements. For instance, at the
Hialeah site, Dade County is requiring GE to treat
soils that contain PCB concentrations of 1.0 ppm and
above.
TSCA Disposal Requirements for PCBs-
In section 761.3, the TSCA regulations define
"disposal" to include "any actions relating to
destroying, degrading, [or] decontaminating...PCBs
or PCB Items." Incinerators include rotary kilns,
liquid injection incinerators, cement kilns, and high
temperature boilers. In addition to approved
incinerators or other thermal devices, under the
authority of section 761.60(e), EPA may approve
non-thermal PCB disposal processes of "destroying"
PCBs with the same effectiveness as an approved
high-temperature incinerator. EPA guidance [24]
indicates that an equivalent level of performance for
an alternate method of treatment of PCB-
contaminated material is demonstrated if it reduces
the level of PCBs to less than 2 ppm measured in the
treated residual. PCB wastes treated to this level by
an approved process are no longer subject to the
TSCA requirements. Aqueous streams must contain
less than 3 ppb PCBs. Releases to air must be less
than 10 ug of PCBs per cubic meter.
TSCA disposal requirements do not generally apply
to PCB wastes disposed in disposal sites prior to
February 17, 1978, the effective date of the PCB
disposal regulations. The TSCA regulations do not
apply to the PCBs at the Hialeah site because
disposal occurred prior to the February 17, 1978 and
because the PCBs are not being removed, but instead
being treated in situ, without excavation. However,
if PCB waste disposed prior to the effective date of
the regulations is excavated, the waste must be
disposed in accordance with the PCB disposal
regulations.
TSCA Disposal Requirements and
Stabilization/Solidification-
Under the disposal requirements, bulk liquid waste
containing between 50 and 500 ppm of PCBs must be
pretreated and/or stabilized to eliminate the
presence of free liquids prior to final disposal in a
TSCA-approved chemical landfill. To date, no
stabilization/solidification process has been approved
as an alternative disposal method to incineration.
There are not currently any TSCA permitting
standards in place to guide the review of this
technology, in view of the difficulty in comparing
stabilization/solidification of PCBs with high-
temperature incineration. Consequently, Superfund
evaluates stabilization/solidification in terms of
employing the appropriate long-term management
controls consistent with chemical waste TSCA
landfill requirements.
Applicability of TSCA Requirements to CERCLA
Cleanups-
The Superfund PCB Guidance is due to be published
in the spring of 1990. This guidance will clarify when
TSCA requirements are ARARs for CERCLA
activities. In general, TSCA disposal requirements
for PCBs would be applicable to CERCLA activities
in two instances. If PCBs were disposed after
February 17, 1978, the effective date of the
requirements, TSCA disposal requirements would be
applicable to the waste, even if it is treated in situ.
Excavation of the PCB material for treatment or
disposal (such as staged treatment) would also
trigger TSCA requirements, regardless of when the
waste was originally disposed. Lastly, if TSCA
requirements are applicable, it may be difficult to
demonstrate compliance with the use of
stabilization/solidification alone, without subse-
quent disposal in a chemical landfill.
As with other hazardous substances, cleanup levels
for PCBs are generally established on a site-by-site
basis, considering local, state, and federal
requirements. The upcoming Superfund PCB
Guidance will also provide guidelines on starting
point cleanup levels. The PCB Spill Cleanup Policy
(40CFR 761.120 through 761.139) gives cleanup
guidelines for most spills of PCBs greater than 50
ppm occurring after May 4, 1987. This policy gives
cleanup guidelines of 10 to 50 ppm for PCBs in soil,
depending on the location of the spill. The PCB Spill
Cleanup Policy is to be considered in determining
PCB cleanup levels at Superfund sites.
Waste Characteristics and Their Impact
on Performance of the Technology
Stabilization/solidification processes involve the
addition of agents that are intended to mechanically
or chemically bind hazardous constituents to prevent
their release into the environment. These processes
usually increase the strength and decrease the
permeability of the solidified mass. In general, the
stronger, more impermeable and durable a treated
waste, the more effectively it will contain hazardous
constituents. If the material does not fragment,
create dust, or increase the surface area available for
leaching, losses will be minimized. Stabiliza-
tion/solidification processes are potentially effective
for some types of organics for both soils and sludges,
and have been proven effective for various inorganic
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wastes, such as metals, asbestos and radioactive
materials.
The IWT/Geo-Con process used in Hialeah, Fla. is a
cement-based process, where the typical design
concept is to solidify and immobilize waste
contaminants. The principal differences between this
process and other cement-based ones are that the
proprietary additive is applied in situ and that
chemical bonding of the additive to contaminants
may occur, which would contribute to toxic
immobilization. The Geo-Con/DSM equipment has a
wide range of applicability. It can be used in most
soils, with a wide range of physical characteristics, to
depths in excess of 100 ft.
The IWT process is claimed to be applicable for
treatment of soils, sludges, solids and liquids
containing a wide range of organic and inorganic
toxic compounds. IWT prefers to treat materials that
contain less than 25 wt% organics, except for
refinery wastes. For high organic wastes, larger
dosages of additive would probably be required.
IWT's only field experience is at the Hialeah, Fla.
site, where the organic content of the soil was very
low (<1.6 wt%). Its experience with high-organic-
content wastes consists primarily of laboratory tests
where some posttreatment leach tests and chemical
bonding studies were performed, but physical
property studies were not performed. Thus, very
limited proven experience with a variety of soils
exists, which would necessitate treatability studies
to confirm anticipated performance for each
potential waste, especially those high in organics
content.
Although an HWT-20 admix was selected for use at
the Hialeah site for the treatment of PCB-
contaminated soils, other formulations exist to treat
other contaminants. IWT is continuing to develop
new formulations that will improve chemical
bonding and even degrade various organic toxins to
less toxic compounds. Thus, the IWT additive may be
able to treat a wide variety of solid and liquid wastes,
both organic and inorganic.
The Geo-Con/DSM equipment can operate in
virtually all types of soils. Clays, oily sands and
cohesive soils may reduce auger penetration rate.
They may also limit the depth of operation to about
60 ft (due to the excessive torque required). This
depth should be well below any soil contamination at
most locations. In a non-cohesive soil,^ such as a
sandy loam, penetration rates up to 6 ft/min have
been used by Geo-Con for grout injection. In cohesive
soils, the rate would probably be below 3 ft/min. The
primary limitations on using the equipment (which
may be circumvented by excavation at shallow
depths) and special injection procedures at greater
depths, are caused by large rocks (>10 in.), lumber,
drums, etc. Another factor that could impact
operation is that a level surface is needed for the
DSM equipment.
A small enclosed site (smaller than the Hialeah site)
may also provide difficulties of site access for the
auger injection system. To ease this difficulty, the
additive preparation system can be erected remote to
the DSM equipment. This may also allow for its
operation in a clean zone. However, the larger the
distance between the two parts of the system, the
more likely that slurry plugging of the transfer lines
could occur, the more energy would be consumed and
the more difficult would be the communications to
coordinate activities.
Subfreezing temperatures may impact the process in
two ways:
IWT - The cement hydration reactions are
usually affected by temperatures below 40°F,
causing a poor quality product. This may be
overcome in some circumstances by special
cements or by preheating the additive stream to
40 to 50°F.
Geo-Con - Low temperatures may cause slurry
freezing in the pipe lines between preparation
and the auger injection nozzles; operations have
been successful down to a temperature of 10°F.
In very severe cold well below 0°F inability
to penetrate the frozen earth may cause
operational stoppage.
Typically, cement-based stabilization/solidification
systems have the following potential limitations to
their effective use:
Organics content above 45 wt%. This limitation
may not apply to the IWT additives because
they contain organophilic clays that may help
in the immobilization reactions.
Wastes with less than 15 wt% solids.
Excessive quantities of fine soil particles (< 74
um) and excessive large particles (>0.25 in.)
'Various chemicals may retard setting o.r
interfere with cement bonding, such as:
phenols; halides; cyanides; soluble salts of
manganese, tin, zinc, copper, and lead;
arsenates; borates; and some others.
Sulfates could cause swelling and spalling of
the cement.
VOCs may be driven off by the heat of the
hydration for the cement reactions.
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Acidity of the soil or sludge should not present
problems, as cement is highly alkaline. In addition,
lime could be added to provide additional
neutralization potential. The ability of the HWT
additives to overcome the above listed potential
problems has not been addressed by the developer.
Material Handling Required by the
Demonstrated Technology
A successfully treated product from the IWT/Geo-
Con in situ stabilization/solidification system
depends on proper weight, flow calibrations, and
ratios of the admixes. Component feed variations,
such as "slugs" of oil and grease in an otherwise
uniform soil, may present some difficulties. In order
to overcome this disadvantage, if this is a frequent
occurrence, the process is capable of using higher-
than-required admix ratios. However, this procedure
is less cost effective. The primary advantage of in
situ operation is that excavation and transporting of
the contaminated soil is not necessary.
For in situ treatment, heavy equipment is required
to properly inject and mix the additives with the
waste. Both in situ and waste-excavated systems for
above-ground treatment require air monitoring
equipment to track organic and dust exposures
during injection, excavation, transport and feed to
the system. Contaminated water, whether surface or
groundwater, can be used in the process as the water
additive.
The materials handling associated with the Geo-Con
DSM consists of a slurry preparation system, usually
remote from the injection auger and in a non-
contaminated area. Thus, a slurry has to be pumped
a considerable and variable distance to reach the
auger. Since a 57-wt% solids slurry is being handled,
the design must prevent solids settling to avoid line
plugging. The front-end of the slurry preparation
area has less potential for difficulties, and it consists
of feeding a storage silo by an air-conveying system
from the supply truck. From the silo, a calibrated
rotary valve is used to feed the slurry preparation
system. This slurry preparation is batch operated,
but could be designed for continuous operation also.
To confirm that the correct amount of water and
additive was added to the slurry tank, the density of
the slurry is measured onsite by a mud balance.
Personnel Issues
Eleven people are required for the 1-auger and 13 for
the 4-auger Geo-Con/DSM units. This includes
operators, supervisors, health and safety officer, plus
office personnel and a sampling technician. This is
based on a one-shift-per-day operation. These people
must pass appropriate physical exams and have
completed an approved 40-hour hazardous-materials
training course.
Personnel are subjected to the standard OSHA
requirements for operating moving equipment and
would be required to wear the proper personal
protective equipment dictated by the specific site
conditions and contaminants. Personnel have
minimal contact with the waste, as all streams are
remotely handled, except during decontamination
and maintenance. This is also true for many
remediation processes.
Procedures for Evaluating
Stabilization/Solidification
Critical parameters in stabilization/solidification
include the selection and quantity of additive, plus
mixing and curing conditions [25]. These parameters
depend on the chemical and physical characteristics
of the waste. Bench-scale treatability tests should be
conducted to select the proper additives, quantities
and curing times. Therefore, chemical analyses of
the waste should be performed using EPA accepted
procedures [26], to define the type and quantity of
contaminants, along with leach tests to obtain
untreated leachate concentrations. After waste
treatment, the leach tests should be repeated, as well
as unconfined compressive strength tests. This would
be the minimum of tests performed. If time and
money are available, moisture content, bulk density,
and weathering tests should be added.
For evaluating the IWT/Geo-Con process, a more
complete sampling program was defined in the
Demonstration Plan. The samples taken and
analytical procedures used were selected based on
the information required to provide answers to the
technology evaluation criteria. The two important
technical criteria to evaluate any stabiliza-
tion/solidification technology are: immobilization of
the contaminants, and durability of the solidified
mass. Tests were drawn from various related fields
and applied to the hazardous waste to obtain the
answers. Other tests, such as acid neutralization and
specific gravity, also could have been performed as
part of the evaluation. The most important factors in
evaluating contaminant mobility are:
To relate pretreatment to posttreatment results
To measure contaminant concentration in the
waste for the samples being used in leaching
tests
Therefore, for both pretreatment and posttreatment
samples, soil samples were analyzed for PCBs,
VOCs, and heavy metals before samples of the same
material were leached. The TCLP test is the most
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widely accepted procedure and is the basis for
proposed regulatory levels for organics and heavy
metals. It is the most important test in the program
for evaluating contaminant mobility. Two additional
leach tests, MCC-1P and ANS 16.1, also were used on
selected posttreatment samples; they attempt to
evaluate leaching from a solidified mass. MCC-1P
simulates a quasi-static groundwater regime in
contact with the waste where saturation
concentrations may be approached, and ANS 16.1
simulates a more-rapidly moving groundwater
where saturation is not reached. These tests were
drawn from the nuclear industry and are relatively
expensive to perform. They also use different
leachate-to-solid ratios compared to the TCLP test
and to each other, so only a qualitative relationship
between test results is valid.
Following the TCLP test, the next most important
test is permeability, which is a measure of flow of
water through the solid. Since water is the leaching
agent, only water coming in contact with the
contaminants can leach the toxins out. A constant-
head permeability test - such as ASTM D-2434-68 -
can be used for untreated soils where permeabilities
are relatively high, more than 10-4 cm/s. For the
treated soils where permeabilities may range from
10-6 to 10-8 cm/s - the falling head permeability test
is used. This is described in Test Methods for
Solidified Waste Characterization (TMSWC) [27].
Once the contaminant is immobilized, the main
concern is how long it will remain that way.
Therefore, tests were performed to provide
information on potential durability of the treated
soil. In addition, testing must include a long-term
monitoring program for this SITE project a 5-year
period in which samples are collected from the
treated soil that has been exposed to the weather.
The most prominent test is UCS, which provides a
measure of the quality of the solidified mass. It is a
test commonly used by the cement industry and is
relatively inexpensive.
Wet/dry and freeze/thaw 12-cycle tests provide
additional information on degradation of the
solidified material. The tests used are described in
TMSWC and are very similar to the ones used by
ASTM. These tests provide an indication as to
whether the solidified material, when saturated or
near saturation (such as occurs with a high water
table), will disintegrate over the first few weathering
cycles, which may take place within the first year.
The tests cannot be used to predict the life of the
solidified mass in terms of decades or centuries.
The final group of tests, which can be performed and
interpreted at only a few laboratories, go under the
general heading of microstructural analyses. Both
treated-soil samples and a few untreated ones are
analyzed by the following methods:
X-ray diffraction (XRD) - This defines
crystalline structure, which can indicate
changes from the normally expected structure.
Microscopy - both optical and scanning electron
microscopy (SEM). These techniques
characterize crystal appearance, porosity,
fractures and the presence of unaltered waste
forms. From these observations, mixing
efficiency can sometimes be estimated.
Energy-dispersive X-ray spectrometry - This
can determine elemental analysis of crystal
structures and hence composition.
These tests are proven analytic methods for
understanding the mechanism of structural
degradation in materials similar to those of the
demonstration. The literature is replete with
examples of SEM and XRD analyses of soil, cement,
soil-cement mixtures, and each of these mixed with
various inorganics and organic compounds.
However, there have been relatively few studies of
the microstructure of complex waste/soil mixtures,
such as those resulting from a stabiliza-
tion/solidification procedure. Consequently, in some
cases, interpretation of the microstructural
observations may be difficult.
These microstructural data provide information on
the potential for long-term durability of the solid.
They cannot quantitatively predict the life of the
solid mass or provide a direct relationship to results
from the other tests described above. In the future, if
a body of data is developed from long-term
monitoring programs, the predictability of and
interrelationships among these procedures will
improve.
Another test of importance, but one not directly
related to the two technology evaluation criteria
(immobilization and durability), is the inexpensive
test of measuring bulk density. In all solidification
processes, pozzolans and special additives, along
with water in many cases, are added to the waste.
These could result in major waste or soil volume
changes, which may affect the remediation
procedures. Bulk density measurements of the soil
before and after treatment, along with a material
balance, will provide a method of calculating volume
change during the remediation process.
The other physical tests - moisture, pH and particle
size distribution (PSD) are typical soil tests and
provided background information that could become
important if problems occur. Moisture and pH tests
are very inexpensive and a PSD is moderately priced.
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Section 4
Economic Analysis
Introduction
A primary purpose of this economic analysis is to
attempt to estimate costs (not including profits) for a
commercial-size remediation. It is assumed for this
analysis, which is based on the test at Hialeah, that
part of a large Florida site is to be remediated. Many
costs are site specific, being affected by such factors
as: site geology; type and quantity of contaminants;
proximity to the community or to other industrial
sites; regulatory requirements; and local costs of
labor, utilities and raw materials. The analysis
assumes that the remediation occurs in Florida in a
spacious, rural setting, and it simplifies and
eliminates some potentially expensive site-specific
costs.
Due to the short-term nature of the demonstration
and the fact that labor, equipment rentals and
chemical expenses dominate the remediation costs,
the actual costs for Geo-Con and EPA were not used.
However, Geo-Con provided information from its
quotation to GE and this was used as a basis.
Information was provided for a 1-auger machine for
the demonstration, and a 4-auger unit that would be
used for a larger application, such as the complete
remediation of the GE site.
Many actual or potential costs exist that are not part
of this estimate.
The major items are as follows:
At the site a prime contractor performs many
functions, including some services not shown,
or only partially included in this cost estimate.
This includes site preparation, such as building
roads, providing access to the treatment area
and providing utilities to plant battery limits.
Battery limits can be defined as the limits of a
space envelope that includes all of the Geo-Con
equipment plus support equipment to which
utilities and access must be provided.
The treated waste has a greater volume then
the untreated waste. Thus, the treated waste
will cause the ground surface to rise, the
amount depending on the depth of the
treatment operation. The cost of removing
excess material to a landfill could be quite
substantial and is not included.
Even if the excess is moved to another part of the
site, or if it is left in place, land contouring would be
required at some expense. Depending on the option
required, appreciable variations in these costs may
be encountered.
Permitting, and environmental monitoring of
operations for regulatory authorities are not
included.
» Operations are assumed to be 5 d/wk and 8 h/d.
Any changes in this schedule would change the
remediation cost. For example, 24 h/d operation
would reduce it, by decreasing the labor and
equipment rental costs.
Treating an oily waste requires an increased
additive ratio, possibly 0.25 Ib HWT-20/lb dry
soil or more, instead of the usual value of 0.15 Ib
HWT-20/lb dry soil. This would increase
operating costs by about $34/ton.
The results are presented in Table 2.
Results of Economic Analysis
The results of the analysis show the approximate
cost per ton for the 4-auger application is $111 and
for the 1-auger application is $194. Some items
mentioned in the previous subsection and discussed
in more detail under Basis of Economic Analysis,
could increase the cost. Extreme care in defining any
ground rules for the economic analysis is required.
The results show that 85% of the costs are for raw
materials (HWT-20), equipment rental and labor.
IWT estimated the cost of HWT-20 at $380/ton. All
costs are site-specific; on the west coast the cost
might be 20% greater. Labor costs include 10 people
to operate the 4-auger unit, and 8 people for the 1-
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Table 2. Estimated Cost (a,b), S/Ton
4-Auger system
1 -Auger system
Site Preparation
Permitting and Regulatory
Equipment
Geo-Con, $ (c) 801,000 77,000
Equipment rential + subcontractors 26.23 67.90
Consumables 6.94. 19.29
Contingency (10% of direct costs) 1.18 0.45
Start-Up and Fixed Cost
Operator training 0.45 0.31
Site mobilization , 0.90 0.31
Depreciation (10% of direct costs) 1.18 0.45
Insurance and taxes (10% of direct costs) 1.18 0.45
Labor Costs
Salaries and living expenses 15.38 45.73
Administration (10% of direct costs) 1.18 0.45
Supplies - Raw Materials
IWT additive, HWT-20 52.45 52.45
Sodium silicate 0.23 0.23
Supplies - Utilities
Fuel ($1.00/gal) 0.90 2.16
Electricity ($0.04/kWh) 0.06 0.21
Water ($0.80/1,000 gal) 0.02 0.02
Effluent Treatment
Residual Transport
Analytical 1.14 3.28
Facility Modification (10% of direct costs) 1.18 0.45
Demobilization 0.90 0.31
Totals 111.50 194.45
Notes
(a) This does not include profits of the contractors.
(b) The American Association of Cost Engineers defines 3 types of estimates: order of magnitude,
budgetary, and definitive. This estimate would most closely fit an order-of-magnitude estimate,
with an accuracy of +50 to -30%. However, this being a new technology, the range on the
potential accuracy may be significantly wider.
(c) Not used directly, but used for the estimate of other costs.
auger machine. In addition, 3 people are assumed for
purchasing, administration, and sampling.
The largest cost savings in remediating the site
results from using the 4-auger DSM unit, which
would reduce operating time, thus saving both labor
costs and equipment rentals. The next-largest cost
factor is the additive, which is being used at a rate of
15 lb/100 Ib of dry waste. This value is near the
minimum, and could increase significantly for hard-
to-treat wastes, such as those high in oil and grease.
Basis of Economic Analysis
The costs analysis is prepared by breaking the costs
into 12 groupings. These will be described in details
as they apply to the IWT/Geo-Con in situ
stabilization/solidification process. The categories,
some of which do not have costs associated with them
for this technology are as follows:
Site preparation costs including site design
and layout, surveys and site investigations,
legal searches, access rights and roads,
preparations for support facilities,
decontamination facilities, utility connections
and auxiliary buildings.
Permitting and regulatory costs including
permit, system monitoring requirements, and
development of monitoring and analytical
protocols and procedures.
Equipment costs. Broken out by subsystems,
including all major equipment items process
equipment, materials handling equipment and
residual handling equipment. Also includes
descriptions of the equipment specifications
(i.e., throughput and utilization rate).
Startup and fixed costs. Broken out by
categories, including mobilization, shakedown,
testing, working capital, depreciation, taxes,
and initiation of environmental monitoring
programs.
Labor costs. Including supervisory and
administrative staff, professional and technical
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staff, maintenance personnel, and clerical
support.
Raw materials. HWT-20 and sodium silicate.
This is the largest of the 12 cost categories for
the IWT/Geo-Con technology, and any design
optimizations based on treatability studies or
direct field experience could have a large
impact on the bottom line.
Supplies and consumables. Includes utilities,
such as fuel, electricity, and water, and
posttreatment of the treated soil and any
byproducts.
Effluent treatment and disposal. Both onsite
and offsite facility costs, including wastewater
disposal and monitoring activities.
Residuals and waste shipping, handling, and
transport. Including the preparation for
shipping and actual waste-disposal charges.
Analytical. Including laboratory analyses for
operations and environmental monitoring.
Facility modification, repair, and replacement
costs. Including design adjustments, facility
modifications, scheduled maintenance, and
equipment replacement.
Demobilization. Including shutdown, site
cleanup and restoration, permanent storage
costs, and site security.
The estimates are based on the following general
assumptions:
The remediation occurs at a large, rural Florida
site.
A total of 38,400 tons of soil, containing 8 wt%
moisture, is processed in each of the two cases
estimated. This figure assumes that 50,000 ft2
is treated to a uniform depth of 16 ft, with the
soil density the same as the GE site, 96 lb/ft3.
Although there was a prime contractor onsite,
this cost is not included. The contractor
provided certain functions for the IWT/Geo-Con
processing unit, such as site preparation.
Many of the cost estimates were provided by
Geo-Con [28].
The twelve cost factors, along with the assumptions
utilized for each, are described below.
Site preparation costs. It is assumed that this
work will be performed by the site prime
contractor and that there will be no charges to
this cleanup. This assumes that roads, site
preparation for the Geo-Con DSM machine and
its support equipment, and access to the
feedstock are provided by others, along with the
supply of electricity and water to battery limits.
It also assumes that any final contouring of the
land will also be performed by the prime
contractor.
Permitting and regulatory costs. It is assumed
that this hypothetical Florida site is a
Superfund site, so no permits will be required,
either federal or state. The need for developing
analytical protocols or monitoring records is
assumed not to exist. On non-Superfund sites,
this activity could be expensive and very time
consuming.
Equipment costs. Based on information
provided by Geo-Con, the capital cost for the 1-
auger machine is $77,000 (plus some equipment
rentals) and $801,000 for the 4-auger machine.
Of these total costs, the mixing plant was
approximately $50,000 and is the same for both
units. Equipment rental costs and subcontract
costs were provided by Geo-Con, and (with some
adjustments) were $26.23/ton and $67.90/ton
for the 4-auger and 1-auger units, respectively.
Geo-Con's profit was estimated so that their
quotation values could be converted to costs.
Additional items -- such as fuel, sodium silicate,
water storage, fences, and lighting -- are
assumed to be provided by the prime contractor
and are not included in these remediation costs.
, The equipment rental and subcontracts are one
of the largest operating costs. Rental equipment
includes such items as front-end loaders, back-
hoes for soil excavation and transport, a steam
cleaner for decontamination, a pickup truck, a
drill rig, a crane and personnel facilities. The
subcontracts include such items as trucking,
piping and electrical hookup.
Consumables are also included in this group,
and include expendable health and safety
clothes, health and safety instrumentation,
trailers for office space, sanitary facilities,
lights and sampling materials. Geo-Con
provided a cost for consumables of $9/yd3 for the
4-auger machine and $25/yd3 for the 1-auger
machine.
Since some additional equipment is required for
this hypothetical site compared to the GE site,
and Geo-Con's values include profit, the
analysis assumed that these dollar values
balanced and that Geo-Con's quotation was to
be only costs.
27
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A contingency cost, approximately 10% of the
direct costs on an annual basis, is allowed for
unforeseen or improperly defined costs. This is
separate from the previously described design
basis uncertainties.
Startup and fixed costs. The costs included in
this group are operator training, initial
shakedown of the equipment, equipment
depreciation, insurance and taxes. The labor
costs and living expenses for mobilization,
operator training, and initial shakedown of
equipment are estimated from Geo-Con's total
labor-cost quotation.
It is assumed that 5 days of training are
required for the Geo-Con operators,
supplementary field personnel, the site health
and safety officer and the sampling technician.
The costs include salaries, overheads and
expenses at the rates described below for labor.
Initial startup includes setup of the Geo-Con
equipment and checkout of its operation. One
week is allowed for this site mobilization, but
travel costs to the Florida site are not included.
The installation of any support tankage,
pumps, etc., is not assumed as a charge to the
remediation. This is probably a modest cost,
equivalent to a few dollars per ton, but the
design of a system and a budgetary or detailed
estimate of it is outside the scope of this
economic analysis. For purposes of this
estimate, this installation work is assumed to
be by the site prime contractor and not charged
directly to the IWT/Geo-Con operation.
The depreciation costs are based on a 10-yr life
for all equipment. Costs are based on the write-
off of $77,000 worth of equipment for the 1-
auger system and $801,000 for the 4-auger
system.
Insurance and taxes are lumped together and
are assumed to be 10% of direct costs taken on
an annual basis.
Labor costs. These costs are salaries plus
overhead, along with living expenses and some
miscellaneous administrative expenses. It is
expected that a total of 13 people will be
required for the 4-auger unit and 11 people for
the 1-auger unit. It is expected that most of the
people will be on expenses, except for the 3
support people who are assumed to be local
hires.
Geo-Con indicated they require a total of 10
people for the 4-auger machine and 8 people for
the 1-auger unit. It is also assumed that there is
1 office manager at $30/h, 1 secretary at $16/h,
and 1 sampling technician at $25/h. These 3
people are assumed to be locally hired and not
on an expense account. The costs which are
provided by Geo-Con and include startup and
operating training (after correcting for profit)
are $13.20/ton of waste for the 4-auger unit and
$37.02/ton of waste for the 1-auger unit. All
these costs are assumed to include a 10% to 15%
contingency that allows for overtime and
unexpected expenses. The values shown in
Table 2 include the 3 additional people
described above.
An additional labor-related expense item is
administrative costs, which include office
expenses, such as supplies, telephones,
furniture, and reproduction equipment, but not
salaries. This cost is assumed to be 10%, on an
annual basis, of direct costs.
Supplies and consumable costs - raw materials.
This cost group includes typical variable costs
and is the largest expense for the 4-auger unit.
The raw materials are the IWT additive, HWT-
20, and sodium silicate. The cost for HWT-20
was provided by IWT. The HWT-20 was
charged to the project at $380/ton delivered to
the Florida location. The HWT-20 was assumed
to be used at a rate of 0.15 Ib/lb dry soil with the
soil at an average moisture content of 8 wt%.
The sodium silicate is assumed to be added for
the bottom 3 ft at 5% of the rate for the HWT-
20. The cost of sodium silicate, based on a
verbal quotation from a supplier, is $0.0885/lb.
Supplies and consumable costs utilities. The
utilities included are fuel, electricity and water.
Also included are byproducts that require
treatment or transport to a landfill. The latter
item does not apply to this economic analysis,
since no byproducts are produced.
It was estimated that the total fuel
consumption for the 4-auger system, for the
crane and all the associated vehicles is 200
gal/d, and for the 1-auger system, is 140 gal/d.
External electricity is not required for this
equipment. The fuel was assumed to cost
$1.00/gal. Electricity is assumed to power
lights, trailers, etc., at an assumed average
daily-rate of 10 kW. The cost of electricity is
assumed to be $0.04/kWh.
Water use is primarily for the process, with 500
gal/d assumed for equipment decontamination
and other miscellaneous requirements. Based
on a material balance that assumes the
untreated soil contains 8% moisture and the
treated soil has 18% free moisture plus water
28
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for cement hydration, the water consumption is
approximately 14.2 gpm for the large unit and
4.3 gpm for the smaller unit. The cost of water
is assumed at $0.80/1,000 gal. There are no
byproducts from the IWT process, and soil
pretreatment or posttreatment is not necessary.
Effluent treatment and disposal costs. Since
there are no liquid effluent streams associated
with this technology, no costs accrue to this
category.
Residual and waste shipping, handling and
transport costs. There are no residuals or
byproducts associated with the IWT technology.
Therefore, there are no expenses associated
with this category of potential costs. However,
if this changes due to the inability of the site to
handle the volume increase produced in the
treatment of the wastes, a major new expense
for transporting the excesses to an approved
landfill would occur.
Analytical costs. It is assumed that sample sets
will be taken daily for the first two weeks of
operation. After that, samples will be collected
once a week until the cleanup is completed.
Both physical and chemical analyses will be
run on all samples, with the cost per set
approximately $1,200. The cost/ton reported in
Table 2 is an overall average value, based on a
completed project.
Facility modification, repair and replacement
costs. The costs accrued under this category
include maintenance and working capital.
Maintenance materials and labor costs are
difficult to estimate and cannot be predicted as
functions of preliminary design concepts.
Therefore, annual maintenance costs are
assumed as 10% of capital costs. Working
capital costs are assumed to be negligible, as all
supplies purchased to* have on-hand are
assumed to be fully consumed by the project's
completion. The cost of using money early in
the project is neglected.
Demobilization costs. It is assumed that all
personnel will be onsite for one week for
demobilization. This is sufficient time for
disassembly of the Geo-Con equipment,
decontamination and cleanup. Any additional
work required to return the site to
pretreatment condition, is assumed to be done
by the site prime contractor and is not charged
to the IWT process.
29
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References
1. Report of Initial Bench Scale Testing
Solidification/Fixation Agent Evaluation, Law
Environmental, Inc., a division of Law
Engineering Testing Co., Marietta, Ga. Report
for General Electric Co., August 1986, Case
Study D-l.
2. Data Sheets from Southwestern Laboratories to
Law Environmental, Inc., a division of Law
Engineering Testing Co. (for GE), May 1988,
Houston, Tex., Case Study D-3.
3. Prohibition on the Placement of Bulk Liquid
Hazardous Waste Landfills -- Statutory
Interpretive Guidance. EPA 530-SW-86/016.
OSWER, Washington, D.C., 1986.
4. Guide to the Disposal of Chemically Stabilized
and Solidified Waste. SW-872 Revised.
Municipal Environmental Research
Laboratory, Office of Research and
Development, Cincinnati, Ohio, 1982.
5. Tittlebaum, M.E., et al., State of the Art
Stabilization of Hazardous Organic Liquid
Wastes and Sludges, CRC Critical Review in
Environmental Control, Vol. 15, Issue 2, CRC
Press, Boca Raton, Fla., 1985, pp. 179-211.
6. Sheriff, T.S., et al. Modified Clays for Organic
Waste Disposal. Environmental Technology
Letters, Vol. 8, pp. 501-504,1987.
7. Demonstration Test Plan In Situ
Stabilization/Solidification of PCB-
Contaminated Soil, USEPA, 1988, RREL,
Cincinnati, Ohio.
8. Evaluation of Test Protocols for
Stabilization/Solidification Technology
Demonstrations. Draft Report. Planning
Research Corp., 1988. Contract 68-03-3484.
USEPA, RREL, Cincinnati, Ohio.
9. Presentation of the HWT Chemical Fixation
technology and Japanese In-Place Treatment
Equipment, Informal Document Issued by IWT,
1986, Wichita, Kan.
10. Advanced Chemical Fixation of Organic and
Inorganic Content Wastes, Informal Document
Issued by IWT, 1988, Wichita, Kan.
11. Gibbons, J.J., and R. Soundararajan. The
Nature of Chemical Bonding Between Modified
Clay Minerals and Organic Waste Materials,
American Laboratory, 7/88.
12. Technology Evaluation Report: SITE Program
Demonstration Test, International Waste
Technologies In Situ Stabiliza-
tion/Solidification, Hialeah, Florida,
EPA/540/5-89/004a, June 1989.
13. In Situ Stabilization/SolidificationResults of
Split Samples Analyses. Letter Report,
Enviresponse, Inc. to USEPA, Edison, N.J.,
EERU Contract No. 68-03-3255,10/6/87.
14. Report of Chemical and Physical Laboratory
Analyses for Bench Scale Specimens, GE
Service Shop, Hialeah, Fla. Letter Report, Law
Environmental Service to General Electric Co.,
10/10/86, Marietta, Ga., Case Study D-2.
15. Cote, P., et al. An Approach for Evaluating
Long-Term Leachability from Measurements of
Intrinsic Waste Properties, Hazardous and
Industrial Solid Waste Testing and Disposal,
6th Vol., ASTM STP 933, Dr. Lorenzen, et al.,
Editors, ASTM, Philadelphia, Pa., 1986, pp. 63-
78.
16. Are We Cleaning Up? Ten Superfund Case
Studies-A Special Report. OTA-ITE-362. U.S.
Government Printing Office, Washington, D.C.
U.S. Congress, Office of Technology
Assessment, 1988.
17. CERCLA Compliance with Other Laws Manual
(Draft), USEPA, OSWER Directive 9234.1-01,
8/18/88, Washington, D.C.
31
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18. Superfund LDR Guide #1, Overview of RCRA
Land Disposal Restrictions (LDRs), USEPA
Directive: 9347.3-01FS, July 1989.
19. Superfund LDR Guide #2, Complying with the
California List Restrictions Under Land
Disposal Restrictions (LDRs), USEPA
Directive: 9347.3-02FS, July 1989.
20. Superfund LDR Guide #3, Treatment
Standards and Minimum Technology
Requirements Under Land Disposal
Restrictions (LDRs), USEPA Directive: 9347.3-
03FS, July 1989.
21. Superfund LDR Guide #4, Complying with the
Hammer Restrictions Under Land Disposal
Restrictions (LDRs), USEPA Directive: 9347.3-
04FS, July 1989.
22. Superfund LDR Guide #5, Determining When
Land Disposal Restrictions (LDRs) are
Applicable to CERCLA Response Actions,
USEPA Directive: 9347.3-05FS, July 1989.
23. Superfund LDR Guide #6A, Obtaining a Soil
and Debris Treatability Variance for Remedial
Actions, USEPA Directive: 9347.3-06FS, July
1989.
24. Draft Guidelines for Permit Applications and
Demonstration Test Plans for PCB Disposal by
Nonthermal Alternate Methods, August 21,
1986, USEPA Office of Toxic Substances,
Chemical Regulation Branch, Washington,
D.C.20460.
25. Technology Screening Guide for Treatment of
CERCLA Soils and Sludges, EPA/540/2-88/004,
9/88, OSWER, Washington, D.C.
26. Test Methods for Evaluating Solid Wastes,
USEPA/OSWER, SW-846, Third Edition, 11/86.
27. Test Methods for Solidified Waste
Characterization, Draft Report, Environment
Canada, 1985.
28. Deep Soil Mixing for Stabilization of
Contaminated Soils, Hialeah, Fla. Letter from
Geo-Con, Inc. to Enviresponse, Inc., 8/30/88,
Pittsburgh, Pa.
32
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Appendix A
Process Description
Description of the Primary Treatment
Mechanisms
Solidification and stabilization are treatment
processes that are designed to accomplish one or
more of the following results [1,2]:
Improve the handling and physical
characteristics of the waste, as in the sorption of
free liquids
Decrease the surface area of the waste mass
across which the transfer or loss of
contaminants can occur
Limit the solubility of any hazardous
constituents of the waste, e.g., by pH
adjustment or sorption
Change the chemical form of the hazardous
constituents to render them innocuous or make
them less leachable.
Solidification entails obtaining these results
primarily by producing a monolithic block of treated
waste with high structural integrity. Stabilization
techniques limit the mobility of waste contaminants
or detoxify them, whether or not the physical
characteristics of the waste are changed or
improved. This is accomplished usually through the
addition of materials to ensure that the hazardous
constituents are maintained in their least mobile or
least toxic form [3].
One goal of treating hazardous wastes is removal of
the particular waste compound or compounds from
the hazardous waste category; this process is called
delisting. Delisting of stabilized/solidified waste is
possible upon the demonstration to EPA's
satisfaction that the component or characteristic for
which the waste originally was listed: (1) is no
longer present in the treated product; (2) no longer
exhibits the characteristics of the original waste; or
(3) contains the contaminants exclusively in an
immobile form. This determination of the
nonhazardous character of the waste product makes
possible the less expensive and less rigorous disposal
of the wastes in any solid waste landfill.
Treatment Process Flow
In the IWT in situ stabilization/solidification process
the contaminated material is mixed with water and a
cement-based proprietary additive called HWT-20.
The developer (IWT) claims the contaminants bond
to the additive, as well as producing a cohesive mass,
thus immobilizing the contaminants.
A batch mixing plant prepares and feeds the
additives (see Figure A-l). HWT-20 is conveyed from
a supply truck by air to a storage silo. A measured
amount of water is fed to a mixing tank, and HWT-20
is added at a weight ratio of about 4/3 to water. A
positive displacement pump then feeds the slurry to
the drill rig. The HWT-20 feed rate is nominally 15
Ib dry additive/100 Ib dry soil but may be greater for
difficult applications, such as oily sludges.
Supplementary water is fed to the drill rig on a ratio
basis to the slurry. This ratio varies with soil
moisture content. At Hialeah this was based on
being above or below the water table. The final
soil/HWT-20/water slurry is targeted to contain
approximately 1.6 to 1.7 Ib water/lb HWT-20.
The control system for the Geo-Con equipment
consists of the following:
Water totalizer for flow to the slurry mix tank
HWT-20 rotary feeder between the storage silo
and mix tank
Magnetic flow meter for measuring slurry flow
to the drill rig
Flow totalizers for supplementary water
Instrument package that controls the ratio of
slurry feed to the drill rig auger penetration
rate and water-to-slurry feed ratio
33
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Pump
Valve
Flow Line
Control Line
Communication Line
Figure A-1. Batch mixing plant.
The Geo-Con/DSM system of mechanical mixing and
injection consists of 1 set of cutting blades and 2 sets
of mixing blades attached to a vertical drive auger.
The blades rotate at approximately 15 rpm. Two
conduits are constructed inside the drive rod and
injection ports are provided at the bottom of the
shaft, so that the additive slurry and water can be
injected into the zone being agitated by the rotating
blades. To create a vertical column of treated soil, the
blade is advanced to the desired maximum depth of
treatment. The HWT-20 additive is injected in
slurry form and mixed into the soil and limestone as
the blade is rotated during entry into the soil, and is
mixed again on withdrawal from the ground. As
necessary, additional cycles of injection and mixing
are made along the length of the column to provide
the required blending. Column positioning is
planned so that the columns overlap, and all the
ground in the target area is affected (see Figure A-2).
The diameter of the treated soil column is
approximately 36 in. The drilling pattern consists of
alternating primary and secondary strokes. In each
sector, all the primary columns are performed before
the secondary columns.
The DSM machine tracks into position, and the
horizontal and vertical alignments are checked. The
elevation measurements are made by using a small
tracking wheel attached to a digital tachometer. This
fixture is mounted at the top of the auger head and
tracks the depth of the drill head. The tachometer
output is shown on a digital display. Machine
location verification is by use of a stationary laser.
The control of the positioning is to about one-tenth of
a degree from vertical for the suspended auger.
For large-scale commercial operations, a 4-auger
DSM machine would be used. The overlapping
column arrangement still exists except that the
alternative primary and secondary columns are by
groups of four.
Comparison to Existing Treatment
Technologies
Comparing the IWT process for in situ
stabilization/solidification to other cement-based
technologies reveals that unique characteristics
exist in the IWT immobilization action of the
additive on the contaminants and the equipment
used. The proprietary additive is a silicate-based
cementitious material, which also includes
organophilic clays. These types of clays have been
known, with proper treatment, to adsorb organic as
well as inorganic material and allow interaction
with cement. They also can be tailored by chemical
treatment during additive preparation to allow
adsorption of different groups of organic compounds.
Using these characteristics for hazardous waste
immobilization is a new and novel approach. The
IWT chemical fixation products can be used for the
treatment of both organic and inorganic toxic wastes.
In situ treatment of contaminated soils is also
unusual. This approach uses technology that has
been used in Japan for two decades to improve soil
characteristics. It has been used in Japan, and for the
last few years by Geo-Con, Inc., in the U.S. for
shoring building foundations, making slurry-
retaining walls, filling voids in soil, and for
providing soil consolidation and environmental
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Figure A-2. Overlapping column arrangement.
barriers. Virtually all competing technologies first
excavate the soil, treat it, and then return it to the
ground. Thus, the major expense of excavating,
sizing, and handling the soil is eliminated with use of
the IWT/Geo-Con process.
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Appendix B
Vendor's Claims for the Technology
The information in the appendix is prepared by
IWT and GEO-CON, INC. and provides their
claims for their technologies. The reader is
cautioned that these claims are those made by
the vendors and are not necessarily
substantiated by test data. The claims are
evaluated against the test data in Section 3 and
Appendix C.
37
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Contents
Topic Page
Conceptual Basis of the Advanced Chemical Fixation Technology . 39
Chemistry Overview 39
Overview of the In Situ Application : 42
PCB Leaching and Extraction Studies 42
Treatment of ACF by High Content Organic Waste 43
Aniline Fixation Study 45
Treatment of Volatile Organics in a Soil Material with PFRS Materials 45
Treatability Studies of Metals and Inorganics 46
Summation 46
Table B-1 Infrared Data 51
Table B-2 DSC Data 51
Figure B-1 Coordination Complexes 40
Figure B-2 Pn to dn Bonding 40
Figure B-3 Lewis Acid Base Reactions: Formation of Sigma Bonds 41
Figure B-4 Observed Bonding Phenomenon in the HWT-23 Treatment Matrix 42
Figure B-5 Formation of Permanent Sigma and Pi Bonding (Covalent Bonding) 43
Figure B-6 Supramolecular Chemistry/Multiple and Secondary Bonding 44
IWT Response to the USEPA Applications Analysis Report 46
Geo-Con, Inc. Claims 49
38
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Conceptual Basis of the Advanced
Chemical fixation (ACF) Technology
Waste treatment techniques that are composed of
Portland cement, fly-ash, cement kiln dust, quick-
lime, soil, clay, asphalt, sodium silicate, slag,
gypsum, etc., in various combinations for
solidification/stabilization (S/S) have been used for a
number of years all over the world. Users and
suppliers of these technologies have in some cases
also used the term chemical fixation (CF) to define
various compositions of these materials, possibly
with the addition of trace compounds to accentuate
their effectiveness with certain waste types.
Whatever the terminology used, S/S or CF,
particular compositions of these materials are the
basis of the proprietary treatment products on the
market. Certainly one of the major appeals of this
class of treatment technology is the relatively lower
cost, if the treatment is sufficiently effective for the
waste types to which it is applied. Stabilization/
solidification has been viewed by many in the
environmental field as a physical or civil
engineering process instead of a sophisticated
chemical system. Tests for the effectiveness of
treatment revolved around certain level of physical
changes in the "ante et post" treatment state.
"Successful" treatments of some metals, radioactive
and nonradioactive, in certain concentrations in
sludges, soils, and liquids, as measured by particular
light acid and water leach tests, have given
additional marketing credence to the notion that this
is a viable and effective treatment for a wide range of
waste types. Very little in-depth research of the
chemistry and physics of S/S and CF was done
because "it worked", as determined by certain static
and dynamic, deionized water leach tests. Also the
use of the term CF with various associated
unsubstantiated or stretched logic claims as to a
given product or composition's ability to treat a given
waste effectively added another level of apparent
creditability. In parallel to the use of S/S over the
past few years, there has been a somewhat erratic, or
wandering, but yet evolving regulatory structure,
influenced by an increasingly negative and dubious
public opinion of the true effectiveness of S/S and CF
and its users. The environmentally active and
concerned public elements and to an increasing
degree the regulatory authorities saw no true
distinction between S/S and CF except marketing
hyperbole. In many groups, S/S and CF are viewed as
"low tech, no-tech, or pseudo-tech" approaches to
waste treatment. Important to solving the
effectiveness issue are the questions of what
comprises reasonable, realistic, or necessary test
procedure of S/S and CF technologies and the "how
clean is clean?" standards. The treatment evaluation
methods and standards for S/S and CF are a point of
contention among the users and marketers of S/S and
CF, competing forms of treatment, the regulatory
authorities, and the public.
In the midst of this complex scenario we have been
doing research into the basic chemistry of chemical
fixation of organics and inorganic toxic
contaminated soils, sludges, and liquids for the past
few years. We believe the necessary reality of S/S, or
more appropriately defined CF, involves exceedingly
complex chemical mechanisms and phenomena, and
this class of technology should be evaluated on such
terms as to its true effectiveness. One of the major
objectives of this article is to develop a definitional
separation between the nature of S/S and CF using
the HWT-20 Series (Patent Pending, IWT)
compositions as the prototype of a new Advanced
Chemical Fixation (ACF) class of treatment
technology. In that regard, we will review GC/MS
readings of acid leach and solvent extraction tests of
cases involving soils contaminated with PCBs and
other high content mixtures of organics treated with
the International Waste Technologies (IWT), HWT-
20 Series Products. A recently discovered problem
with high content organic waste treated with a
typical S/S mixture using a quick-lime, pozzolan base
will be discussed. We have also used infrared
adsorption (FTIR) and differential scanning
calorimetry (DSC) to give insights into the chemical
bonding mechanisms of this particular type of ACF
technology with a range of organic compounds in a
pure liquid or contaminated soil form. It would be
useful at this point to give some background
information relative to the chemical design and
analytical thinking that went into the HWT-20 ACF
prototype. As was implied earlier, we believe that
S/S and CF should be based on an accurate paradigm
of the chemical process rather than an
adsorption/dilution panacea judged effective only by
end-state physical characteristics of questionable
relevance and validity. Our position is that the
extent and strength of the chemical bonding and
alteration to innocuous forms within the treated
matrix is a truer measure on the short and long term
effectiveness of this category or form of treatment.
Chemistry Overview
This HWT ACF technology is based on three sets of
interrelated functional chemical groups. There is a
matrix cement chemistry, a free radical and ion
attack and organophilic linking mechanisms. The
underlying concepts have been discussed in some
intermediate level of detail in previous papers, so we
will summarize this time.
Cement Matrix Chemistry
The objective of the cement chemistry is not
primarily end-state physical properties, but the
39
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facilitation of the overall objective of bonding the
toxic molecules and ions within a given
contaminated material. In line with that point,
certain aspects of the cement hydration reaction
(CHR) are altered and stretched out in time; the
fibrils (sulpho-ferri-hydrates) that exist in the second
stage of the CHR are modified to be more chemically
reactive and caused to be more dense. Certain
admixtures are used to cause a greater dispersion of
the cement particles in impure environments which
in turn will promote better development of the weak
IPN (Interpenetrating Polymer Network) bonding
function. This function is the slowest reaction of all
three functional groups and its primary function is to
be the silicate anchor matrix to which all other
reaction products attach.
Free Radical and Ion Attack Chemistry
This is a parallel chemistry that can be made up of a
wide range of compounds that produce highly
reactive ions and complexes in the HWT-20 slurry.
This activity does not interfere with the functioning
of the other major functional CF groups. This
chemical function should attack various toxic
organic and inorganic elements within the
contaminated medium and reduce them to relatively
inert forms or reaction products that can
subsequently react with one of the other functional
groups in fhe HWT-20 ACF material. A simple
example of this capability is the use of transition
metal complexes, but even these must be thought out
carefully for one could cause certain counter-
productive reactions. An example of this in Figure B-
1, Coordination Complexes, and an explanation of
the bonding is given in Figure B-2.
6 (CeHsOH; * M3*(Transition Metal)« [M (C6H5OH)6]3+
C6H5OH
O
xs Octahedral Phenol
\ X Metal Complex
CeHsOH C£=
s a^ » Nv
x^" v^h^-N
^ ^W*"5; ^> °6H!
X^ «^ v * ^y
^^ ^. * _^ .'
;OH
X
N
N
N
S
1
\~"
\
\
N\
.V
"" "w
/ X
£''
O
C6HSOH
Evidence:
UV - Visible Spectral - Drastic Color Change
Figure B-1. Coordination complexes.
nElectron Charge Clouds
Metal da orbitals (empty or
partially filled orbitals)
Evidence:
Shift in FTIR Frequency for Ring Breathing
Figure B-2. Pn to dn bonding.
Organophilic Linking Mechanisms-
These are intercalation compounds, such as modified
smectite clays, that interact with the organics
present, within certain ranges of predetermined
selectivity, by a sorptive process in either of two
general modes. The strong, short-range bonding is
based on a Bronsted and/or Lewis acid or base
reaction (see Figure B-3), relative to such a reaction
we have observed with triethanolamine. The weak,
long ranges forces are basically hydrogen bonds (see
Figure B-4), induced dipole or Van der Waals1 forces.
There can be an initial reaction based on the weak
force reaction and later a second strong or Lewis base
reaction.
These modified smectite clays have both organic and
inorganic properties due to the substitution of the
quaternary ammonium ions in the normally
inorganic clay structure of the Group IA and IIA for
metal ions. This makes them ideal linking
mechanisms between the toxic organics in the waste
and the cement matrix. The introduction of the
quaternary ammonium ions also opens the basal
spaces in a pillaring effect to allow like polarity
organics into the strong force reaction zone. Bonds
can range from weak Van der Waals1 forces to strong
coordinate covalent bonds.
The important point is that this is primarily a
problem in supramolecular chemistry and the
multiple and secondary bonding and positioning of
the appropriate molecular structures is the key
issue. The individual FTIR shifts on functional
40
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Aluminum Oxide Layer
FTIR Analysis
Triethanolamine
2104
1075
Treated
2297
1070
Shift
193
-5
Peak
Assignment
Amine Salt
Formation
H Bonding
Silicon Dioxide Layer
X = Electron Deficient Species or H Which is a Lewis Acid.
Evidence: Shift in N - R (n) Frequency in Positive Direction (Increase)
DSC Analysis - Triethanolamine
Edotherms
150.97
337.30
Hot
Vaporization
(Literature)
Kcal/mol
12.78
Observed H of
Vaporization
Kcal/mol
24.16
Percentage
Increase in
Energy
89.0
Boiling
Point
335.4
Highest
Endothermic
Temperature
337.30
Figure B-3. Lewis Acid Base Reactions: Formation of Sigma Bonds (o).
groups seen are usually not considered large and in
some cases are slight, but the number of bonds, the
sum of the shifts, and the positioning of the bonds is a
stronger effect in most cases than one would see in a
primary bond. An indication of the strength of this
multiple and secondary bonding phenomena can be
seen in "Percentage Increase in Energy" of the DSC
analysis of a given waste (see Figure B-3). We have
also done DSC studies on the treatment of pure
phenol, nitrobenzene, and trichloroethylene and
have achieved percentage energy increases of 220.7,
275.9, and 52.8 respectively. A significant adjunct
condition is that the behavior of a pure substance in
a laboratory gives one an idea of what is possible, but
in a real, complex waste many other factors will
interfere with the ACF material chemistry in
achieving the maximum desired effect. There are
some positive assisting factors but in most cases one
must design ACF materials to overcome a variety of
chemical hurdles before the fixation reaction can
reach the desired level of efficiency. The use of
advanced chemical techniques and analysis provides
invaluable insights into the waste chemical
mechanisms.
Fourier Transform Infrared (FTIR)--
FTIR studies are used to understand the extent of
interaction between the toxic compounds and the
HWT-20 ACF material. This analytic technique
measures the changes in vibrational motion in
specific bond relationships. It also helps to determine
the functional elements present in a given molecule
involved in a bonding process.
Differential scanning calorimetry (DSC)
DSC measures the changes in temperature and
energies associated with various significant
chemical changes involved in bonding, such as the
enthalpies of melting, evaporation, decomposition,
41
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Hydrogen Bonding of Phenol Molecules
Oxygen
f
Aluminum
Oxide Layer
Phenol Molecules
Silicon Dioxide
Layer
Oxygen
Evidence:
Lowering of FTIR Stretching Frequency
Phenol Treated Phenol Shift Peak Assignment
962 cm"' 934 cm"' -28 cm'' C - O
3640 cm"' 3632 cm"' -8 cm"' H - Bonded OH
Figure B-4. Observed bonding phenomenon in the HWT-
23 treatment matrix.
phase transition, etc. This technique can indicate the
strength of bonding.
Overview of the In Situ Application
The application of the ACF technology can take place
above ground level using a variety of mixing systems
or in the ground, in situ, as was done at the former
General Electric transformer repair facility in
Miami, Florida. The use of high and/or low-pressure
rotary shaft injection, with or without mechanical
blade mixing, has been done for more than ten to
fifteen years in the construction industry for creating
injection piles and sub-surface barriers. It was a
natural extension of this construction method to be
used in the treatment of contaminated soils and
sediments, if one had a cement chemistry that would
prevent both inorganics and organics from leaching
at an unacceptable level. The low pressure rotary
shaft injection and blade mixing equipment offered
by Geo-Con, Inc. was chosen because it would give an
even, homogeneous blending of the HWT-20 ACF
with the soil and subsurface porous limestone strata
encountered at the site and create accurately placed,
consistently overlapping columns. An additional
purpose of the in situ method, other than the fact it
treats the contaminated soil in-place, is that GE was
interested in using this technique of application in
sites where there was volatile and semivolatile
organic contamination of the subsurface soils where
it would not be desirable to expose these soils to the
air by a removal technique.
At the SITE Program's Demonstration, Geo-Con
used a relatively small diameter drill one yard
for two reasons. The drilling for most of the time was
in rock and the objective was to prove the concept of
in situ treatment. The mixing drill process could be
operated in sand/clay soils with a larger diameter
drill (2 to 3 yards) and/or multiple, parallel drills,
resulting in a quicker and more economical
treatment. In situ treatment costs can be as low as
$20 to 30/yard, excluding treatment chemicals, on a
large project, up to $60 to 70/yard in difficult
situations.
PCS Leaching and Extraction Studies
The HWT-20 CF Series was successfully used in the
treatment of PCBs at the General Electric (GE)
Miami Site under the U.S. Environmental Protection
Agency's Superfund Innovative Technology
Evaluation (SITE) Program. This application was
done in situ, using mixing drills down to 6.15 meters
(m) from Geo-Con, Inc. of Pittsburgh. The first 1.2 m
was sand, the second 2.5 m was a porous coral like
limestone, and below that quartz sand, with fresh
water at 1.2 m. The level of addition of the HWT-20
CF material was 15 wt% to soil. In other words, for
every metric ton of contaminated soil 150 kg of dry
HWT-20 was added in a slurry form: The maximum
concentration of PCBs was 5,700 ppm and was found
by GC/ECD. The leaching procedures were the
USEPA TCLP (Toxicity Characteristic Leaching
Procedure), 18-hour dynamic acetic acid test, ANS
16.1 and the MCC-1P leach procedures. Essentially
no PCBs came out in the EPA testing, and only one
sample was found to leach in GE's testing, that was
1.2 ppb on a two-week old sample. GE did methylene
chloride extractions of drill core samples as well, and
did not find in excess of 206 ppm PCBs in the treated
samples using GC/ECD.
Some of the pre-project laboratory experiments,
carried out by Dr. R. Soundararajan, gave some
insights into what was occurring in the treated soil
matrix. In a sample of PCB-contaminated soil from
the same site and the same sample barrel as the
above sample, eight-hour methylene chloride
extractions were performed on the untreated and
crushed treated samples.
Analysis was done by GC/MS with the machine
calibrated against all 221 position-isomers of PCBs.
In one sample of this experiment, an admixture was
included that produced a sulfurous acid that would
totally disable the organophilic clay linking-
42
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mechanisms between the PCBs and the slower-
developing silicate-based anchoring matrix. In the
second sample, the admixture was removed so that
primary linking mechanisms could function. The
results are as follows, untreated soil released 28,800
ppm PCBs in a methylene chloride extraction:
Sample 1:
Admixture
Sample 2:
No
Admixture
Treated extraction 26,437 ppm 2,800 ppm
Treated TCLP 10,437 ppm 12.5 ppm
These tests were done only three days after
treatment. A treatment dilution factor of 20% is
included in the above numbers. The TCLP numbers
did improve with the age of treated sample. This
particular sample showed only 5,000-6,000 ppm
values using standard GC analysis, mainly because
the GC/MS was registered with all 221 PCB isomers.
Also high values (40,000-50,000 ppm) of chlorinated
benzenes were found, most likely the decomposition
products of the PCBs, since no chlorinated benzenes
were ever used at the site. The chlorinated benzenes
were reduced, in a similar proportion to the
reduction in PCBs of Sample 2, from untreated to
treated extraction values. Almost all of the existing
PCB isomers after treatment were the low value
chlorine forms.
The conclusions of the above experiment were
supported further in another set of leach and
extraction tests performed on a sample of a clay/sand
soil contaminated with low levels of PCBs (290 ppm).
The eight-hour testing procedure was the same as
above, with the focus on which isomers were bonded
or retained in the treatment matrix after solvent
extraction of crushed treated samples. The TCLP
leach tests of the treated material were all non-
detectable. The sample cured for seven days. The
treatment level of HWT-20 was 15 wt% to the weight
of soil. In the untreated soil there was some
chlorobenzenes and substituted phenols but none
were found in the treated soil. Only the lighter PCB
isomers (tri, tetra, and penta) were found in the
treated soil. The hexa- and hepta-chlorophenols were
not found in the treated. The total PCB content
extracted was 190 ppm or 65 wt%.
Relative to PCBs, the current HWT ACF treatment
technology is able to alter or bond to a high degree
the heavier chlorinated PCB molecules and to a
lesser degree the lighter chlorinated molecules. It is
very effective in preventing the leaching of PCBs
against the TCLP of all types. Also the HWT-20 ACF
treatment sufficiently bonds and prevents the
leaching of the PCB decomposition products,
substituted.benzene and phenol compounds. Newer
formulations of a more advanced IWT ACF product
show significantly greater rates of bonding or
chemical alteration of organics, including PCBs. An
example of the treatment of a PCB-containing waste
with our newer "Polyfunctional Reactive Silicates"
(PFRS) (TM) is shown in Figures B-5 and B-6. These
ACF materials are based on new inorganic carceplex
structures and heretofore non-existent organic
trailers. As the results show, this is the most
effective PCB reaction to date and the research is
continuing to be positive. The first of these new
PFRS materials should be commercially available
later this year.
A = O + H2X
ACF Toxic
Material Waste
i- A = X + H2O
Irreversibly Bonded
End Product
Figure B-5. Formation of Permanent o + n Bonding
(Covalent Bonding),
Treatment by ACF of High Content
Organic Waste
An organic content waste with a high percentage of
heavy hydrocarbons and with relative trace to small
fractional loadings of volatile and semivolatile toxic
compounds is normally a difficult material for the
usual S/S mixtures to effectively treat, unless some
integer multiple by weight of the S/S material is
added to the weight of the waste and end-state
physical properties are all that is being considered.
The waste sample, in this case, was a soil with a
heavy concentration of long chain hydrocarbons from
Bis( l-chloro-iso-propyl)ether
Naphthalene
Phenanthrene
Benzo(A)anthracene
Untreated extraction
8,528 ppm
18,060 ppm
20,184 ppm
30,460 ppm
Treated extraction TCLP
ND ND
1,445 ppm ND
ND ND
ND ND
43
-------
Dichlorobiphenyl
AI2Oy Layer
O
O
\
S,O2 Layer
O O
Solvent Extraction and Leach Results:
Untreated
(ppm)
PCB 17,580
Dichlorobiphenyl
1150cm'1
Solvent Extraction of Treated (ppm) TCLP
N.D. N.D.
FTIR Study of PCB
Treated PCB Shift
1118cm'1 -32
Peak Assignment
Cl to Al
Coordinate Bond
Figure B-6. Supramolecular chemistry/multiple and secondary bonding.
an acid/clay process for recycling used oil. The major
organic toxic components of this waste, as
determined by a solvent extraction and analyzed by a
GC/MS are shown below:
This contaminated sample was treated 50% by
weight with an experimental and more advanced
chemical fixation material and allowed to cure for
only two days. This treatment level is too high for an
actual project, but what we were trying to achieve is
an accelerated effect that would allow us to examine
the bonding activity more quickly by the solvent
extraction (GC/MS), FTIR, and DSC analyses. A
dilution factor of 50% was used in all quantification.
Standard methods of analysis and QA/QC were used.
With such a complex mixture to analyze by FTIR and
DSC the approach had to be different than working
with a pure, known organic liquid. In using FTIR, we
focused on functional groups that we knew were
there in relatively large concentrations and looked
for shifts within those groups to indicate a level of
bonding activity. In reviewing the data, we have
found that there were significant shifts in a number
of FTIR frequency regions, and hydrogen bonding
was occurring between the aliphatic amines,
hydroxyl compounds, and the oxygen in the A^Os
and SiC-2 in the CF material. There was an amine
salt formation, as the result of a Lewis base reaction
at 1,580 cm-1. The most significant shift occurred at
1005 cm-1 where a hydrogen bond was formed with
an SiC-2. This is explained by the fact that the oxygen
in the silica strongly interacted with the hydrogens
of alkyl, hydroxyl, and amino groups, which results
in a reduction of the O-Si-O bond order (Table B-l,
Infrared Data).
The DSC data (TableB-2, DSC Data) also confirms
that relatively significant bonding activity is
occurring. The enthalpy of vaporization has
increased by 54.9% from untreated to treated soil.
44
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The DSC analysis is an energy summation function
rather than a focus on a specific reaction.
Aniline Fixation Study
Aniline is considered to be a difficult compound for
chemical fixation to control in terms of leaching and
is also extremely toxic. IWT ACF products were
tested against fourteen other products and mix
designs in this treatability study. The objective was
to treat the aniline contaminated lime/soil (pH 12.5)
material such that the TCLP value was less than 50
ppb. IWT tested successfully using the HWT-9 ACF
material and will be used in the remediation project
starting in November of 1989 by Geo-Con in an in
situ mode.
Cement leach values continued to increase over time.
FTIR studies were done on the aniline plus cement
and aniline treated by HWT-9 samples. These results
supported the premise that there is significant
chemical bonding by a different and shifted chemical
activity spectra of the HWT-9, particularly in the
characteristic absorption bands associated with the
aniline molecule as compared to the cement plus
aniline.
Treatment of Volatile Organics in a Soil
Material with PFRS Materials
In a recent analysis by Kiber Associates, Atlanta, for
a major corporation one of IWT's new Polyfunctional
Reactive Silicates designs was bench tested in a
treatment of spiked soil samples from Miami,
Florida, with seven VOCs. The mixing of the samples
for the TCLP tests took place in a controlled
atmosphere and checked for the degree of
volatilization of the VOCs during mixing and curing.
Temperature profiles of the samples before and after
treatment were also plotted.
Samples were spiked with the following compounds
and concentrations: benzene 75 ppm, chlorobenzene
150 ppm, m-xylene 10 ppm, 1,1 dichloroethane 10
ppm, 1,3 dichloropropylene 10 ppm, carbon
tetrachloride 10 ppm, and ethyl benzene 10 ppm.
All samples were treated at 15% by weight of the
treatment material, with a 30 day cure.
Methonol Extraction of Treated Material - Detectable
Extraction Data (ppb)
HWT-20 - 27 benzene, 1072 chlorobenzene, 47 ethyl
benzene, 177 xylene
HWT-20M - 591 chlorobenzene
HWT-23H - 444 benzene, 6407 chlorobenzene, 370
ethyl benzene, 262 xylene
PFRS - 320 chlorobenzene
The PFRS material could be altered further to
improve the solvent extraction results of the
chlorobenzene.
TCLP Leach Data of Treated Material - Detectable
Leach Data (ppb)
HWT-20 -14 benzene, 404 chlorobenzene, 73 xylene
HWT-20M-306 chlorobenzene
HWT-23H - 364 chlorobenzene
PFRS - 45 chlorobenzene
The temperature of the samples HWT-20 and HWT-
23H rose from 17°C to 25°C during mixing and
curing, HWT-20M went to 29°C, and PFRS went to
32°C. Total VOCs lost into the air during mixing and
curing was 3% for the cooler treated samples and
4.5% for the PFRS and HWT-20M samples. This air
leaching should be reduced significantly if the
application was done in-place, underground, instead
of in the open in an above ground mixer.
Independent analytical work done in The
Netherlands on PFRS treated soils contaminated
with mercury, arsenic, chlorobenzenes, organo-
chloro-pesticides, chloro-phenoxy-pesticides, organo-
phosphate pesticides, nitrophenols, chlorophenols,
and carbon disulfide against the Dutch availability
and leach tests was successful. Testing of these
samples in the U.S. by TCLP and solvent extraction
procedures was also well inside the EPA limits.
Recent experimental work done by Dr. R.
Soundararajan has indicated that lime, lime/fly ash,
or pozzolan-based S/S of organic-content waste of a
sufficient level (this threshold is not yet known, but
certainly the oil recycling waste in this case applies)
will generate significant carbon monoxide and/or
acetylene gas when exposed to water of even mild
acidity. Also, during the process of S/S or CF
treatment, it is desirable to keep the heat generation
by the reaction with water as low as possible, since
the more heat generated the more the volatilization
of the organics. The IWT ACF technology only
contains trace amounts of lime in the cement fraction
of its composition and no pozzolans are used. The rate
of addition of the IWT ACF materials used to weigh
waste is relatively low, 12% to 20%, and has a lower
heat of hydration than straight cement.
Other "tricks" one must watch out for in the field of
S/S or chemical fixation are the use of compounds
that convert various toxic compounds to other
compounds that can be volatilized out of the system
during the cement or poz/olan/lime hydration
reaction, and/or a masking technique by using
certain long chain hydrocarbons such as mineral oil.
The way to screen for these is: 1) know the addition
rate of the treatment material relative to the weight
of the waste; 2) determine whether organic based
additives being used; 3) use a GC/MS as the
45
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Total aniline (ppm)
146 (10 day cure)
325 (10 day cure)
325 (10 day cure)
325 (30 day cure)
Cement (32 days)
Percent treatment
by weight
20
20
30
20
30
Untreated TCLP
(ppm)
7.1
12.5
12.5
12.5
12.5
Treated TCLP
(ppb)
ND<1
110
ND<1
ND<1
100
analytical instrument with subtraction filtering; 4)
do a complete priority pollutant scan for volatiles
and semivolatiles in the treated analysis; 5) consider
an air-leaching test during the mixing and hydration
phase of the pre-project bench testing and during at
least 30 days after if you suspect this approach is
being used.
Treatability Studies of Metals and
Inorganics
I. Arsenic and Mercury in Soil
Total concentrations - As 43,000 ppm, Hg
5,300ppm
TCLP values after seven days of sample treated at
30% by weight with HWT-11 was the following, As
3.5 ppm and Hg 0.06 ppm. These numbers should go
lower as the sample cures further.
II. Chromium + 6 and Cyanide
From another site in Alabama the following was
obtained from a treatment with HWT-11H compared
to treatment by straight Portland cement. Total
chromium 6,310 ppm, total cyanide 235 ppm.
Untreated leachate, Cr 37 ppm, CN 0.34 ppm
HWT-11H Treatment
Cr CN
0.29 ppm <0.02 ppm
BD BD
Treatment
to/weight of Cement Treatment
soil Cr CN
15% 5.25 ppm 0.86 ppm
35% 3.93 ppm
BD - below detection
III. Hexavalent Chromium
Waste lagoons contaminated with chromium at
7,155 ppm. Cr+6 leached at 150 ppm. Treatment
was at 25% by HWT-11H. The leach data from a one
day cure was Cr + 6 nondetectable and total
chromium leached at 0.15 ppm.
IV. Arsenic, Lead, Copper
A soil sample was contaminated with arsenic 2,200
ppm, lead 670 ppm, chromium 1,250 ppm, and copper
at 3,000 ppm. Treated at 15% by weight with HWT-
11 the EP Toxicity leach values after a one week cure
were arsenic 0.126 ppm, lead nondetectable,
chromium 1.1 ppm, and copper 0.22 ppm.
Summation
Chemical fixation technology is far more advanced
and cost effective than most people realize, especially
from those companies or groups that have done in-
depth chemical research of the basic fixation reaction
mechanism. International Waste Technologies has
and is doing this basic research and believes that the
HWT ACF Product Series and the new, more
advanced products (PFRS) that will come out in the
near future will compete favorably with thermal and
biological methods in the destruction, alteration,
and/or bonding of organics and the immobilization of
inorganics. The effectiveness of ACF technology can
be verified analytically, with relative quickness and
function in a wide range of contaminated
environments at relatively acceptable costs and ease
of use factors. An important key to the success of this
category of toxic waste treatment is for the
regulators and users of this type of technology to
insist on high standards of relevant chemical testing
and verification in the pre-project treatability
analysis and careful QA/QC during project
application.
In situ applications that are effective in terms of
homogeneity of mixing the ACF material with the
contaminated soil to the required level and that do
not leave any voids can be an effective, economical,
and a necessary part of the waste treatment picture.
The Geo-Con system successfully demonstrated that
objective.
IWT Response to the USEPA Applications
Analysis Report
The EPA has taken a generally critical approach,
particularly with respect to the fixation chemistry,
in this applications analysis. Based on the drafts we
have received to date, the overall reasoning of this
position is in general rather curious to us, but
46
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specifically the EPA has been negative in the
following nine major points.
1. The EPA has ignored the use of the appropriate
types of chemical analysis that would be able to
discern whether the IWT chemical fixation
material, HWT-20, is in fact chemically bonding
with the PCBs to any degree instead of a weak
adsorption, encapsulation, dilution phenomena as
its total means of waste treatment. The chemical
bonding could have been verified by using FTIR
and DSC analysis of the PCB-contaminated site
material treated with the HWT-20 in a bench top
test. The chemical bonding capability to organics
of the IWT fixation material is central to IWT's
product claims. IWT did perform such analysis on
contaminated soil from the site but was unable to
convince the EPA to duplicate these tests (see
section titled "Vendor Claims", subtitled "PCB
Leaching and Extraction Studies"). Their position
is that IWT agreed to a test plan in March 1988,
which we did. They then took the position that
there were no conditions under which the test plan
could be amended. The main reason we asked for
additional testing to clear up the bonding question
was in order to counter the EPA's speculative
attack to discount our product claims in the
various draft reports it sent to us. The additional
testing requested by IWT would have been a
relatively small additional cost and certainly it
would be warranted in the case of a new
technological approach along with all the
conventional testing. The analytical procedures
needed to be expanded over what had been done in
the past to verify our proposed concept. Instead the
EPA speculated and implied from a generally
uninformed position that, at best, there was no
evidence to support this claim. In fact, there is no
way to judge what relevant chemical processes are
occurring and how effective they are from the
analytical work done by the EPA. The claim of
chemical bonding with organics is important
because it lifts the solidification/ stabilization
(S/S) process to a new and important level over
what has been done in the past in this field. S/S is
relatively inexpensive and easy to use. It is also
easy to verify its effectiveness compared with
other forms of waste treatment and if it can reach
a new and important plateau of quality of
treatment, then it is very significant.
2. The EPA used a technology evaluation team of the
IWT SITE Demonstration which had a perspective
anchored in a concept structure that reflected the
antiquated and simplistic notions of chemical
fixation as a physical process that should be
evaluated like an extension of civil engineering
testing. IWT is not taking the position that all
physical testing is wrong, only that this
evaluation process should have been augmented
with some innovative expertise in the area of
inorganic/organic chemistry, clay chemistry, and
physics. This would have caused the EPA to
expand the initially agreed to test plan.
3. The EPA has mentioned many times in this report
that the HWT-20 fixation material freeze/thaw
results were poor. This may be true from the point
of view as a building material, but the EPA had
failed to do any leach testing of the treated
material that went through the freeze/thaw
testing to see if the freeze/thaw process affected in
a negative fashion the HWT-20's ability to
prevent leaching to an excessive degree.
Continued freezing and thawing will break the
sample into small pieces. The TCLP leach test
requires the sample to be ground to a small grain
size and the HWT-20 did well on the TCLP
testing. TCLP tests on the samples used in the
freeze/thaw tests would have been simple to
perform. Also, the chemical fixation material is
designed on the basis of many factors. If freezing
and thawing were proven an important issue, the
mix could be changed to improve its
characteristics in that respect. This change is
simple cement chemistry. Freezing and thawing
are not going to occur from the surface to twenty
feet down in Miami, Florida. Also most of the
treatment occurred under water, therefore the
curing treated mass would acquire a lot of pore
water which, when exposed to freeze/thaw cycles,
will cause cracking. In the wet/dry weathering
test, which is really what will happen in this
environment, results were excellent. Permeability
results were in the range of what would be
acceptable as a liner material.
4. The dilution factor issue of the mixing process of
Geo-Con's in situ mixing drill could have been
determined absolutely in properly controlled, pre-
project bench testing rather than having the EPA
speculate about this effect. The EPA postulates
that since there is 95% reduction in the presence
of metals from untreated to treated B-6 and B-7
samples attributed to mixing, then that should
correlate as a one to one mapping to the reduction
of the presence of organics. What valid reasoning
states that the metals and organics must always
congregate in the same area? The majority of
outstanding questions relating to the effectiveness
of the HWT-20 material revolve around the fact
that insufficient pre-project bench testing was
done and once the test plan was established many
months prior to the actual demonstration it
seemed set in concrete. Many of the important
questions could have been resolved even after the
demonstration by doing chemical bench studies
then, but that seemed impossible. It is not IWT's
fault that this was not done. We raised the issue
time and time again in various written
47
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communications to the EPA project management.
The report penalizes us and our technology for
these deficiencies. They advised IWT to apply for
another study.
5. The EPA buries in the text of this report rather
than explaining in the various summaries that
this is an actual project for General Electric (GE),
not something contrived for an EPA technology
demonstration only, and that the requirements
placed on IWT and GE by the involved State and
Federal regulatory authorities relative to the
efficacy of the chemical fixation treatment are tied
to PCBs only, and that VOCs were not an issue in
terms of treatment at that time. IWT could have
added additional compounds into the HWT-20
mixture to improve its ability to reduce leaching
of VOCs, but this was not required. Even with this
handicap the HWT-20 material affected a drop in
the leaching of the total VOCs by a factor of 147
and 13 (see Samples B-6, B-7) and a factor of 36
and 22 in the total content of VOCs. Even relative
to the immobilization of metals this report seems
to cast doubt on the capability of the HWT-20
chemical fixation material. In contradiction to
this implication, the EPA testing shows that the
metals passed even drinking water values in the
leach testing on the treated materialv Further
independent testing on the treatment'of VOCs
was done on various mix designs of IWT chemical
fixation materials by a major U.S. corporation and
the results are given in the section titled,
"Treatment of Volatile Organics in a Soil Material
with PFRS". This clearly shows the significant
impact of formula changes on the ability to
contain and chemically fix VOCs.
6. The EPA refers to test information, reports, and
articles given to them by IWT as evidence to
support the basically negative premise of this
applications analysis. These reports and articles
were put together over a four-year period under
different requirements while the IWT chemical
fixation technology was in the process of
evolution, and it still is changing as we learn
more. There were not even specific leach value
standards set at the time that some of this work
was done. The test work reported was always run
by independent, credible laboratories working
under the prescribed EPA and analytical
procedures at the time. This was not a coherent
body of work strictly put together for this
Applications Analysis Report, it was information
given to the EPA for educational purposes on the
development of the thinking and experimentation
as the technology evolved. It was meant to give
them the fundamental issues involved, not be used
as evidence against IWT.
7. The EPA explanation of the nature and value of
FTIR and DSC analysis is completely lacking and
raises the question about their capability and
reasoning behind their position in writing this
report. Their understanding of bonding is
insufficient as well and.shows in their
explanations in the draft reports we have seen to
date.
8. The comments the EPA makes on IWT's lack of
field experience seem to us unfair since the
regulations and interpretation of these
regulations which make the IWT technology
viable commercially have only been in effect since
late 1987 and the body of regulation that governs
what and how waste can be treated by chemical
fixation, especially organics to pass TCLP, is still
evolving. Even considering this, IWT has gained
the confidence of companies such as General
Electric and Westinghouse. Both Geo-Con and
Westinghouse Environmental are including the
IWT advanced chemical fixation technologies in
conjunction with their waste treatment
marketing. IWT has subcontracted to
Westinghouse in completing a 10,000 yd3 project
to treat lead-contaminated soils in Atlanta.
General Electric will complete the 8,750 yd3
Miami Project (which will include the treatment
of PCBs, VOCs, and metals) starting in November
1989 using the IWT treatment materials. Region
IV-Atlanta of the EPA selected, based on
independent testing, IWT to supply the treatment
material for a site containing cyanide and
hexavalent chromium to drinking water
standards. IWT was also selected and has supplied
the Italian Government with fixation materials
for the first remediation project in Italy under the
new regulations that are modeled after the U.S.
environmental laws, including the use of the
TCLP tests.
9. No matter what IWT claims relative to the ability
of its fixation products to treat a given waste, and
even if we received an outstanding rating by the
EPA in this report, every project situation would
require this treatment technology to be proven
again and again in appropriate pre-project bench
tests, technology reviews, and possibly even pilot
project tests. This technology has a wide range of
applications, is effective if proper screening is
done, and is economical and efficient. The IWT
chemical fixation technology and the in situ
method of application must not be too bad if three
of the EPA technology evaluators used in this
project decided to go into business copying at least
the form, and to a yet unknown degree, the
content of the technology to become competitors of
IWT and Geo-Con before this report was even
finalized.
48
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EPA HAS TURNED OVER THIS MATTER TO
EPA'S OFFICE OF INSPECTOR GENERAL FOR
INVESTIGATION.
Geo-Con, Inc. Claims
Geo-Con is generally in agreement with the SITE
Demonstration Report as regards comments relating
to Geo-Con's Deep Soil Mixing (DSM) System.
We do feel, however, that some clarification is
needed pertaining to the report's assertion that
"location of the soil columns deviated from the
planned points and some untreated areas between
columns exist".
In actuality, the locations of most columns were
within normal drilling tolerances. One column
deviated six inches. A graphical plot was made of
actual locations of columns and untreated areas
referred to were assumed from that graph, and not
found through the coring program. For the most part,
the columns created are slightly larger than the
nominal thirty-six inch diameter which accounts for
minor deviations. In any case, the distance between
centers of columns can be shortened to raise the
factor of safety against an untreated area. In
general, the report confirms that the soil mixing was
very effective.
DSM has proven to be an excellent method of mixing
slurry with contaminated soils for chemical fixation.
A completed DSM fixation project results in a
homogeneous mixture of slurry and in situ soils. It
appears that the question to answer is what
materials would be effective in neutralizing specific
pollutants and in what dosages.
There are other proven uses of DSM for
environmental applications that are also economical.
DSM has been used to construct hydraulic barriers to
isolate contaminated soils and prevent contaminated
groundwater from leaching into a nearby water
source.
DSM was selected over other conventional hydraulic
barrier techniques because it does not require any
soil to be excavated, thereby eliminating costly
backfill and disposal. A cement-bentonite slurry
blended with soil to meet the permeability
requirements and reinforcing steel was added for
structural requirements.
For solidification and stabilization of contaminated
soil by DSM, many common material's such as
cement, lime, kiln dust, and fly ash can be batched
into slurry form and mixed into the soil.
For aerobic bacterial destruction or organic wastes,
oxygen can be pumped through the augers and out
the tip at high enough pressures to aerate the soil
and accelerate its bacterial activity. (Existing
applications of aerobic destruction are limited to
near surface spills.)
Steam or other heated gases can be injected through
the augers to strip the soil of volatile organics. A
hood at the surface would evacuate the waste gases
to a plant for recover and disposal. This method
would decrease the potential for offsite emission that
is always present during an "evacuate and remove"
type of operation.
Shallow Soil Mixing (SSM) is a variation of DSM.
SSM utilizes a single large diameter auger to
perform stabilization and fixation projects where the
contamination is less than thirty feet deep. It is more
economical than DSM at shallow depths because
much more soil is targeted at one time.
DSM offers a number of advantages over
conventional techniques:
No excavation is required.
Treatment at depths up to 150 feet.
Effective for a wide variety of soil conditions.
A relatively rapid construction sequence.
Easy to adjust mix designs and flows.
No need to dewater.
Geo-Con Background
Geo-Con, in addition to its soil improvement and
specialty foundation work, is a full service remedial
construction company. Geo-Con has experience in
drainage ditches, capping, lagoon/landfilling
closures, soil/sludge stabilization, and drum
removal. Geo-Con is also a leader in slurry cut-off
walls, having installed more than 400 walls to date,
including soil-bentonite, cement-bentonite, and soil-
attapulgite.
In addition to the DSM soil-fixation project in
Hialeah, Florida, Geo-Con has performed the
following selected projects:
Site Remediation Stabilization and Geomembrane
Installation Sludge Pond Closure/Vickery, Ohio-
The sludge pond closure project conducted in
Vickery, Ohio, by Geo-Con in 1986 was the largest
privately financed project of its kind in the nation.
Approximately 265,000 cubic yards of PCB and
dioxin-contaminated metal sludges were stabilized.
Geo-Con first completed a pilot project to
demonstrate the technical feasibility of handling and
49
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solidifying the waste with cementitious agents.
Eventually, all the sludges on the sites were
stabilized, without incident, in the face of keen
public awareness and publicity. All solidified
sludges, contaminated soil, and debris were
stockpiled for temporary storage. All solidification
work required EPA Level B and Level C worker
protection, which was monitored pursuant to a site-
specific health-and-safety plan by in-house
industrial hygienists and site safety officer.
The empty and decontaminated sludge ponds were
regraded to form one large cell to permanently
contain the stabilized sludge. Geo-Con was
contracted to construct the RCRA closure cell. The
cell will be comprised of a clay liner with three
synthetic liners and leachate collection and detection
systems. At the time of the writing of this project
summary, the capillary barrier system and clay liner
had been completed and the synthetic liners were
being replaced.
Geo-Con Remediation Experience
Sludge Stabilization and Capping Project - Sparta,
Wisconsin-
Geo-Con was selected to perform various services
leading to the closure of a metal plating lagoon and
dump site in Southern Wisconsin. Geo-Con
performed sludge and waste stabilization laboratory
studies to determine the most cost-effective
acceptable reagents for this particular waste stream.
Once the reagent was identified, Geo-Con in
conjunction with EDER Associates, the Owner's
environmental consultant, prepared health and
safety programs and operating plans to support the
closure plan.
Geo-Con stabilized over 2,000 cubic yards of sludge
on this project and is performing grading operations
to allow placement of final cap and cover systems.
Site Remediation - Lagoon Solidification Cap and
Landfill Creosote Impoundment/Savannah,
Georgia-
Geo-Con closed an unlined lagoon for a wood
treatment facility in Savannah, Georgia. This project
involved the onsite, in situ stabilization of 12,000
cubic yards of creosote contaminated sludge to attain
specified strengths and moisture content. After
solidification, the sludge was transferred to an onsite
disposal location where the waste was compacted,
graded, covered with a clay cap, synthetic liner, and
cover materials. All operations were accomplished by
Geo-Con forces using EPA Level C and Level D
protection equipment along with a "real time" air-
monitoring program.
Site Remediation - Deep Soil Mixing Cutoff Wall -
Bay City, Michigan
This project utilized the DSM technique to prevent
PCBs from migrating into the Saginaw River. A
large manufacturing company required a cutoff wall
to contain groundwater contaminated by its
operations.
Because the soils were very soft (< 1 blow count per
foot), a conventional soil-bentonite cut-off wall could
not be constructed. The problem was magnified,
because the alignment of the wall is as close as six
feet in some areas to the Saginaw River. If the soil-
bentonite trench were to collapse during
construction, and if there was a break of adjacent
lagoons, there could have been a disastrous spill. The
Owner opted for the DSM technique, which produced
a 4,500-ft-long impermeable structural wall 35 to 65
ft deep, which was keyed into a subsurface aquiclude.
Treating the soil in-place saved the Owner the
expense of removal and disposal of the contaminated
soil and eliminated a sensitive and complicated
operation.
50
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Table B-1. Infrared Data
Waste extract
cm-1
Waste
extract + binder
cm-1
Infrared frequency
shift
cm-1
Infrared function group assignments
3,394
3,382
3,373
1,597
1,035
3,385
3,372
3,355
1,580
1,005
-9
-10
-18
-17
-30
OH Stretch O--H....O
NH Stretch NH....O
Keto Group CO....H
Hydrogen Bonding Si Si
O
Table B-2. DSC Data
DSC Endothermic Peak Values
Temperature
(Degrees C)
Waste extract 1 38.90
Waste extract + binder 121.2
414.4
414.5
Waste extract
cal/gram
Total H (vaporization) , 18.63
Total H (vaporization)
corrected to 100%
TGA - Percent wt. loss at
given temperature range
PERCENT INCREASE in H
H. (Vaporization)
cal. per gram
18.63
6.15
2.32
2.06
10.53 Total
Waste extract + binder
cal/gram
10.53
28.65
Waste extract
+ binder
36.48
54.9
(vaporation) for waste
extract + binder
51
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Appendix C
SITE Demonstration Test Results
Introduction
A very narrow scope of soil contaminants exists at
the GE electric service" shop. The untreated soils
measured in two sectors showed a maximum PCB
concentration of 950 mg/kg, which was less than one-
half the anticipated value based on sampling
performed by Law Environmental (LE) for GE. The
PCB concentrations appear to be very localized,
particularly in Sector B where the higher PCB
concentrations were seen. The additive was mixed
with the soil by the Geo-Con/DSM equipment,
providing vertical, and some horizontal, blending.
After soil treatment, which produced a mass increase
of 32% due to the addition of HWT-20 and water, the
maximum PCB concentration was 170 mg/kg, with
only one other sample value above 100 mg/kg. In
Sector B, the average PCB concentration of the
treated soil (50 mg/kg) was about one-quarter of that
of the untreated soil (180 mg/kg) after correcting for
the additive volume. These low soil values produced
TCLP leachates very close to the detection limit,
which made interpretation of the results more
difficult.
Although high VOCs were measured up to 1,485
mg/kg total ~ the VOCs were found in only 3
samples, which were in Sector B. This was
insufficient information from which to draw any firm
conclusions. Heavy metals, at relatively low
concentrations (a maximum of 5,000 mg/kg total),
were measured at only the same 3 locations as for the
VOCs. Thus, the significance of the results is limited,
both due to the small number of samples and low soil
and leachate concentrations. In addition, IWT claims
that their HWT-20 additive was not tailored for
immobilization of VOC and metals, only PCBs.
The analytical data consists of physical and chemical
tests on untreated and treated soils from various soil
depths between 1 and 17 ft below grade. Clean soil
and contaminated soil blends from both Sectors B
and C were mixed in the laboratory with Type 1
Portland cements to provide a baseline comparison to
the soil treated with HWT-20. The demonstration
results are discussed separately in terms of the
physical tests, chemical tests and operations.
Results
A large amount of analytical and operating data was
obtained, but due to the limitations described above,
the program objectives could not be completely met.
The detailed results and operating summaries are in
the Technology Evaluation Report [4]. The results of
the physical testing are shown in Tables C-l through
C-5, at the end of this Appendix.
Physical Results
The physical tests showed that the IWT in situ
stabilization/solidification process could readily
solidify soils contaminated with PCBs and VOCs.
However, the total organics content of the soil tested
was very low, mostly under 1.0 wt%, with a
'maximum of 1.6 wt% at B-6, a location of high VOCs.
The process produced a structurally firm material
with good physical properties, except under the
freeze/thaw weathering testing where large weight
losses, more than 5%, were measured on many
samples. The moisture content of the treated soil
samples averaged about 18 wt%.
On treatment, the bulk density increased
approximately 21%, from 1.55 g/mL (96.7 Ib/ft3) to
1.87 g/mL (116.7 Ib/ft3). This was for an average
weight addition of HWT-20 and water of 32%. Thus,
the volume increased by 8.5%, which is equivalent to
about an 18-in. ground rise in Sector B and 14 in. in
Sector C. This was confirmed by observation of the
ground rise in the two sectors a 1 l/2-to-2 ft rise in
Sector B and a 1- to 1-1/2-ft rise in Sector C.
The unconfined compressive strengths (UCS) in
Sector B averaged 288 psi. This ranged from 75 psi at
Sample Location B-19 an interface location of
relatively poor overlap (based on the mapping of the
soil treatment locations by LE) to 579 psi at
Sample Location B-23 - a location near the center of
a primary column. In Sector C, the UCS averaged
53
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536 psi. This ranged from 247 at Sample Location C-
15, to 866 psi at Sample Location C-l, both column
centers. The average additive dosage rate in Sector C
(0.193 Ib additive/lb dry soil) was 13% greater than
in Sector B (0.171 Ib). Although in some moisture
ranges a concentration change affects the UCS of
cement, this was not observed at Hialeah. In
addition, no effect of bulk density change on the UCS
was observed. These UCS values are quite
satisfactory, easily meeting the EPA guideline
minimum of 50 psi [5] for this type of technology.
The permeability tests showed a reduction after soil
treatment from an average of 1.8 x 10-2 cm/s for
untreated soil to 4.2 x 10-7 cm/s for treated soils. This
treated soil value was slightly greater than the EPA
and industry guideline maximum of 10-7 cm/s for
hazardous-waste-landfill soil-barrier liners. Not only
does a low permeability reduce contaminant
mobility, but it lessens solid erosion and weathering
degradation. This four- orders-of-magnitude
decrease in permeability should divert all
groundwater around the treated monolith.
The wet/dry weathering tests showed low weight
losses, with the absolute losses about 0.3-0.4%. The
relative weight losses, compared to the control
specimen, were about 0.1%. However, the
freeze/thaw results were not satisfactory. Half of the
samples tested had relative weight losses of more
than 3.0%, the maximum being 30.7%. The weight
losses of the control samples for these tests were
0.3%-0.5%. UCS tests on about half of the weathered
samples showed that the strength was equivalent to
unweathered samples, except when the relative
weight loss exceeded 3.0%. Many of the samples from
the freeze/thaw tests with high weight losses
crumbled at the start of UCS testing. Permeabilities
for wet/dry and freeze/thaw samples with moderate
weight losses were equal to the unweathered
samples.
The microstructural studies, using scanning-electron
and optical microscopy and X-ray diffraction
analyses, found the treated soil to be dense,
homogeneous, and of low porosity. Variations in the
vertical and horizontal directions were absent. Thus,
it was concluded that the Geo-Con mixing operation
was efficient and that a solidified mass with a
potential for long-term durability can be produced.
Formulation tests were also performed in the
laboratory, where 3 solidified samples were
prepared. They used uncontaminated soil and
composite soil samples from Sectors B and C with
Type 1 Portland cement, instead of HWT-20, at
dosage rates of 0.15 and 0.20 Ib/lb dry soil. The
results showed the bulk densities were equivalent to
those of the treated field samples. The UCS values
doubled when the dosage rate of cement was
increased from 15% to 20% of the contaminated soil.
The UCS values for the contaminated soils were
about equal to or greater than the values for field
samples, and the moisture content was lower, which
may have contributed to the higher UCS values.
Chemical Results
Both soil and leachates were analyzed for PCBs,
volatile organics and heavy metals. The leachate
results were compared to the corresponding soil
compositions.
The untreated soil contamination consisted
primarily of PCBs (Aroclor 1260), with one localized
area in Sector B of VOCs and heavy metals. High
PCB concentrations were measured in Sector B, with
the maximum being 950 rag/kg, compared to the
5,700 mg/kg value reported by IWT in Appendix B.
Other minor discrepancies between information
reported in Appendix B and actual results also exist.
The maximum PCB concentration measured in
Sector C was 150 mg/kg. After soil treatment, the
concentrations in Sector B were reduced on average
by a factor of about 4, providing a maximum treated-
soil concentration of 170 mg/kg. In Sector C, the
reduction was only about 25 wt%. This indicates that
soil blending during the additive injection operation
produced large reductions in concentrations for the
samples in Sector B, indicating that the high PCB
concentrations measured were localized. Even
greater concentration reductions after soil treatment
were observed for heavy metals and VOCs. Analyses
for VOCs did not provide any evidence of PCB
decomposition, which was claimed by IWT. As noted
above, the microstructural analyses showed a
homogeneous mass, indicating good vertical and
horizontal blending.
The treated-soil leachate analyses for PCBs showed
all values below the nominal detection limit (for SW-
846 Method 8080) of 1.0 ug/L. However, when
analyses of 7 treated-soil leachates from the more
contaminated areas were repeated at a reduced
detection limit of 0.1 pg/L, four samples were found
to be below the new detection limit, with the others
0.2 ug/L or less. This compares to untreated soil
samples, which had leachate values up to 13.0 ug/L
(there was one apparent wild point at 400 ug/L).
Additional information contributing to the
determination of PCB immobilization follows. All
untreated soil samples (with soil compositions at or
above 300 mg/kg) had measurable leachate
compositions (above 1.0 mg/L). All untreated soil
samples of less than 60 mg/kg had leachate PCB
concentrations below detection limits. For the in-
between untreated soil concentrations, some
leachate had PCB levels above the detection limit
(1.0 ug/L), while others did not. All treated soil PCB
compositions were 170 mg/kg or less, with most of
54
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them below 100 mg/kg. Twelve samples analyzed
using Leach Tests MCC-1P and ANS 16.1 all
produced leachates with PCB concentrations below
the detection limit (1.0 ug/L). TCLP leach tests on
the 4 contaminated formulation samples produced
leachate concentrations for PCBs below the detection
limit of 1.0 mg/L. Therefore, it appears that the
HWT-20 additive may have immobilized the PCBs,
but since all the leachate concentrations, from both
untreated and treated soils, were so close to the
detection limit, more information at higher soil
concentrations is required to confirm this conclusion.
The untreated soil with high VOC concentration was
located near a former buried drainage drum. The
designations for these samples are B-6, B-7 and B-8,
which are samples collected in one location at three
different depths - 1-2 ft, 7-8 ft and 11-12 ft below
grade. Three VOCs were identified total xylenes,
ethylbenzene and chlorobenzene with the xylenes
found in the greatest quantities. The maximum total
VOC concentration in the untreated soil was 1,485
mg/kg at Location B-6. After treatment, the VOC
concentrations were reduced sharply to a maximum
total concentration of 41.3 mg/kg at B-6, with each
component reduced approximately in the same ratio.
This reduction was probably due to soil blending.
However, some other factors - such as volatilization
of VOCs to the atmosphere and excessive holding
time of the samples in the laboratory before analyses
may have contributed significant reductions.
Immobilization of VOCs could not be determined,
since only 3 samples were measured, and the treated
soil TCLP leachates were quite low, mostly below
100 ug/L (except for xylenes, which were about,300 to
400 ug/L). Meanwhile, the untreated soil TCLP
leachates were about 10 times larger for each VOC
component, with the maximum total VOC leachate
concentration being about 4.4 mg/L. IWT claims that
their HWT-20 additive used in this test was not
tailored to immobilize VOCs.
The heavy metals, lead, chromium, copper and zinc,
were also detected only at Sample Locations B-6, B-7,
and B-8. The maximum total concentration was
5,000 mg/kg at B-6, with lead representing about
half of the total metals in the untreated soil. A lower
proportion of lead was observed in the treated soil
samples. The maximum total-metals concentration
in the treated soil was only 279 mg/kg, also at B-6.
This soil concentration change after treatment is
very large, which tends to confirm that the reduction
in treated soil concentrations was due primarily to
soil blending with low contamination areas. The
laboratory methods for metals analysis consists of an
acid digestion procedure followed by Atomic
Absorption spectroscopy, which will measure each
metal, whether or not it was bonded to the additive.
TCLP leachate analyses for total heavy metals in
untreated soils ranged from 0.32 to 2.65 mg/L, with
zinc showing the highest concentrations and the
other 3 metals comprising 30% or less. The treated
soil leachates contained very low concentrations of
metals, with individual metals at 100 mg/L or less
and the total metals concentration ranging from 120
to 210 mg/L. Since only 3 samples are available and
the leachate values are low, any immobilization of
metals cannot be determined. IWT claims that their
HWT-20 additive was not tailored for immobilizing
metals.
The results of the chemical analyses are shown in
Tables C-6 through C-9 at the back of this Appendix.
Operations
Geo-Con's equipment operations during the
demonstration were satisfactory, although some
problems were encountered. These difficulties were
minor, and with engineering design changes many
could have been avoided. The problems were, as
follows:
Automatic control of the feed streams (water
and HWT-20) to the auger could not be
maintained. Eventually manual control was
required. This was caused in part by the fact
that the additive feed system was oversized
because it was designed for a 4-auger machine.
Flow surges of additives were encountered on
many soil columns. The remixing of the soil and
additive on the auger upstroke tended to reduce
any impact this may have had on treated soil
properties.
A water leak in the auger head occurred, which
restricted the use of supplemental water on the
last 21 soil columns. GE instructed Geo-Con to
continue operations to minimize time loss. An
impact on the physical and chemical properties
of the treated soil was not observed.
Positioning of the auger deviated from the
targeted locations, producing some untreated
areas between soil columns.
Difficulties were encountered in aligning the
auger to start many of the columns,
particularly in Sector C. These difficulties
produced delays of a few min up to 40 min.
55
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Table C-1. Physical Properties of Untreated Soils - Sector B
Sample
designation(a)
B-1
B-2
B-3
B-4
B-5
B-6
B-7
B-8
B-9
B-10
B-11
B-1 2
B-1 3
B-1 4
B-15
B-1 6
B-1 7
Moisture
content
%
2.8
3.0
6.4
4.4
4.7
3.6
13.3
13.3
16.8
24.8
6.3
34.9
15.6
22.5
3.2
9.7
7.5
12.4
12.3
Bulk density
g/mL
1.50
1.56
1.21
1.41
1.55
1.28
1.46
1.74
1.85
1.59(C)
1.25
1.58
1.52
1.63
1.46
1.73
1.52
1.83
1.46
1.30
1.85
1.32
PH
-
7.7
8.4
7.6
7.5
7.3
11.2
8.3
8.1
7.8
8.5
7.8
8.1
7.8
7.7
8.1
7.9
8.2
8.3
Oil & grease
%
<0.1
0.1
<0.1
0.1
<0.1
0.1
0.8
1.6
0.4
<0.1
<0.1
0.2
<0.1
. 0.3
0.1
0.8
0.1
0.8
0.7
TOG
mg/kg
2,100
1,300
2,900
2,500
1,600
2,600
16,000
12,000
3,100
< 100
< 100
8,100
920
1,500
320
960
11,000
9,900
9,400
Permeability x
102cm/s(b)
1.6
1.0
1.0
0.76
0.50
1.2
1.4
6.0
0.98
0.15
2.6
0.05
0.91
0.05
0.98
2.1
3.7
0.13
0.55
(a) Sample depths
B-1, 2, 3, 4. 5, 6, 10, 14, 16 at 1-2 ft
B-7, 11, 15, 17 at 7-8 ft
B-8, 12 at 11-12 ft
B-9, 13 at 16-17 ft
(b) Each value shown is the permeability multiplied by 102. For example, the B-1 permeability is I.6xl0-2, and when
multiplied by 102 is reported as 1.6. .
(c) Modified bulk-density test using split spoon.
56
-------
Table C-2. Physical Properties of Untreated Soils - Sector C
Sample
designation(a)
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
C-11
C-12
C-13
C-14
"
C-15
C-1 6
C-1 7
Moisture
content
16.7
14.6
17.1
14.8
9.1
9.1
5.7
20.2
14.7
5.9
8.2
19.5
5.7
12.5
23.5
5.3
15.1
23.2
(a) Sample depth
C-6, 9, 12, 15 at 1-2 ft
C-1, 2, 3, 4, 5, 7, 10, 13, 16 at
C-8, 11, 14, 17 at 11-12 ft
(b) Modified bulk-density test using
Bulk density
g/mL
1.37
1.29
1.67
1.41
1.28
1.46
1.74
1.85
1.60
1.60
1.74
1.63(b)
1.39(b)
1.63
1.82
1.63
1.59(b)
1.66
1.20
1.65
1.60(b)
7-8 ft
split spoon.
Oil & grease
pH %
8.6 0.4
8.5 <0.1
8.2 0.4
8.2 0.2
8.7 0.2
8.3 0.2
8.6 <0.1
8.5 <0.1
8.4 <0.1
8.6 <0.1
8.5 <0.1
8.5
-------
Table C-3. Physical Properties of Treated Soils - Sector B
Moisture Permeability
Sample content Bulk density Compressive 107
designation % g/mL strength, psi cm/s(h)
B-1 15.7
B-2 9.9
B-3 20.3
B-4 17.6
B-5 31.1
B-6 23.1
12.9
B-7 24.7
B-8 19.0
B-9 15.5
B-10
B-11 12.9
B-1 2
B-1 3
B-14 20.2
B-1 5 21.2
B-1 6 26.5
B-1 7 13.3
B-1 8
B-19 19.1
B-20 17.6
B-21 18.1
B-22 20.9
22.9
B-23 17.2
B-24 20.1
1.78
1.72
1.74
1.81
1.66
1.77
1.75
1.81
1.88
1.96
-
2.24
2.15
-
1.78
1.83
1.81
1.82
--
1.58
1.79
1.92
1.99
1.76
1.98
1.90
492
330
508
172
206
86
114
115
173
303
470
--
321
204
--
221
256
413
507
-
75
199
479
428
177
579
351
1.4
...
3.3
0.8
2.3
4.2
21.0
5.9
11.0
2.6
8.3
4.1
3.5
3.5
Weathering tests
wt. loss % (a)
X
W/D
0.38
0.32
0.37
0.42
0.37
0.43
0.49 '
0.34
0.53
0.44
0.40
0.26
0.46
0.39(b)
0.39(C)
0.27
0.41
F/T
0.65
1.48.
2.07
3.34
1.84
3.04
27.92
29.53
1 .66(f)
6.06(g)
4.37
1.10
0.87
1.34(d)
6.05(6)
23.28
10.73
(a) Reported as % loss of starting weight on a dry basis. The weight losses of the wet/dry (W/D) and freeze/thaw (F/T)
controls were 0.3-0.4%.
(b) Permeability after 1 2 W/D weathering cycles = 2.7x1 0-7 cm/s.
(c) Permeability after 1 2 W/D cycles = 4.9x1 o-7 cm/s.
(d) Permeability after 1 2 F/T cycles = 8.9x1 o-8 cm/s.
(e) Permeability after 12 F/T cycles = 1 .2x1 0-7 cm/s.
(0 Permeability after 12 F/T cycles = 3.9x1 0-8 cm/s.
(g) Permeability after 1 2 F/T cycles = 5.9xtO-7 cm/s.
(h) All values shown are the permeability multiplied by 107. For example, B-1 permeability is i.4xlO~7, and when multiplied
by 1 07 is reported as 1 .4
58
-------
Table C-4. Physical Properties of Treated Soils - Sector C
Sample
designation
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C:10
C-11
C-12
C-1 3
C-14
C-15
C-16
C-1 7
C-l 8
Moisture
content
%
18.8
14.3
20.9
17.9
20.2
14.6
12.3
16.7
20.0
15.9
20.8
18.9
19.7
23.8
15.5
13.5
18.0
15.4
16.7
16.1
Bulk density
g/mL
1.97
1.93
1.95
2.01
1.96
1.95
1.91
1.82
1.91
2.00
1.95
1.93
1.97
1.84
1.99
1.99
1.80
2.02
2.02
1.91
Compressive
strength, psi
866
528
482
611
656
294
567
343
524
813
460
466
783
409
553
636
247
435
521
530
Permeability x
10?
cm/s (d)
0.24
1.0
6.4
4.1
1.6
1.9
2.2
4.6
2.5
Weathering
wt loss %
W/D
0.35
0.41
0.27
0.31
0.38
0.40
0.34
0.31
0.38
0.39
0.32
1.68
0.27
0.40
0.25
0.31
0.33
0.30
0.29
0.32
tests
(a)
FIT
2.06
8.11
3.94
30.75
2.53
3.12
1.65
1.97(b)
0.72
1.70
0.88
0.99(C)
4.20
8.04
20.98
2.14
2.57
2.95
14.45
(a) Reported as % loss of starting weight on a dry basis. The weight losses of the controls were 0.3-0.4%.
(b) Permeability after 12 F/T cycles = 2.3x10-7 cm/s.
(c) Permeability after 12 F/T cycles = 3.0x10-8 cm/s.
(d) All values shown are the permeability multiplied by 107. For example, C-8 permeability is 4.1x10-7, and when multiplied by 107
is reported as 4.1.
Table C-5. Results of Formulation Studies
Addition Rates
Clean Soil .
Property
Slump flow, %
Moisture content, %
Bulk density, g/mL
UCS, psi
TCLP PCBs (Aroclor1260), i»g/L
15%
cement
139.8
3.6
2.01
740
20%
cement
102.8
4.0
2.02
1,770
Sector B
15%
cement
58.1
5.1
2.01
1,332
20%
cement
79.7
5.0
2.03
<1 0
Sector C
15%
cement
129.7
8.9
1.88
170
20%
cememt
116.5
8.9
1.81
318
59
-------
Table C-6. PCBs in Soils and Leachates - Sector B
*
PCB concentration
Sample
designation
B-1
B-2
B-3
B-4
B-5
B-6
B-7
B-8
B-9
B-10
B-11
B-12
B-13
B-14
B-1 5
B-1 6
B-17
B-1 8
B-1 9
B-20
B-21
B-22
B-23
B-24
Untreated soil
mg/kg
52
74
55
88
78
16
650
460
220
16
1.1
950
140
250
26
63
300
490
500
-
--
--
--
-
--
--
Untreated soil TCLP
leachate, ng/L
< 1.0
1.2
1.0
1.1
1.6
(0.62)
< 1.0
12.0
(15)
400.0
(250)
< 1.0
< 1.0
< 1.0
7.2
(0.33)
1.1
< 1.0
< 1.0
13.0
3.7
(0.50)
4.2
1.8
(1.0)
-
~
~
--
-
--
--
Treated soil
mg/kg
40
53
40
41
18
35
63
82
9.6
< 1.0
--
170
16
-
11
7
100
100
~
97
50
60
- 130
98
<1.0
1.6
Treated soil TCLP
leachate, yg/L
<1.0
<1.0
<1.0
<1.0
(<0.1)
<1.0
<1.0
<1.0
(0.15).
<1.0
(0.12)
<1.0
<1.0
--
<1.0
(<0.10)
<1.0
"
<1.0
<1.0
<1.0
(<0.10)
<1.0
(<0.20)
--
<1.0
<1.0
<1.0
<1.0
<1.0
<1.0
<1.0
() Repeat analyses of existing TCLP leachates analyzed to a detection limit of 0.1 ng/L. Original analyses
performed to a detection limit of 1.0 jig/L.
60
-------
Table C-7. PCBs in Soils and Leachates - Sector C
PCB concentration
Sample
designation
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
C-11
C-1 2
C-1 3
C-14
C-1 5
C-16
C-1 7
C-1 8
Untreated soil
mg/kg
98
2.5
96
92 -
9.1
27
16
150
15
17
86
16
23
32
1.8
80
46
13
< 1
-
Untreated soil TCLP
leachate, ng/L
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
1.3
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
-
Treated soil Treated soil TCLP
mg/kg leachate, ng/L
20 < 1 .0
19 <1.0
110 <1.0
3.5 < 1 .0
40 < 1 .0
22 < 1 .0
26 < 1 .0
16 <1.0
27 < 1 .0
5.9 < 1 .0
20
80 < 1 .0
45 < 1 .0
4.7 < 1 .0
1 .2 < 1 .0
1 .0 < 1 .0
17 < 1 .0
6.0 < 1 .0
< 1.0 <1.0
7.1
( ) Repeat analysis of existing TCLP leachate analyzed to a detection limit of 0.1
61
-------
Table C-8. Total Volatile Organics in Soils and Leachates
Sample designation (a)
B-6
Total xylenes
Chlorobenzene
Ethylbenzene
Total
B-6d(b)
Total xylenes
Chlorobenzene
Ethylbenzene
Total
B-7
Total xylenes
Chlorobenzene
Ethylbenzene
Total
B-8
Total xylenes
Chlorobenzene
Ethylbenzene
Total
Untreated soil
mg/kg
1,300
65
120
1,485
560, 1000(0)
20, 150
74, 28
916 avg.
140, 190(c)
5, 7
13, 23
1 89 avg.
Untreated
soil leachate
ng/L
3,700
280
440
4,420
6,600
290
1,000
7,890
2,100
100
290
2,490
Treated soil
mg/kg
35.0
1.9
4.4
41.3
32.0
2.2
4.6
38.8
34.0
2.5
4.5
41.0
1.7
<1.2
0.66
2.4
Treated
soil leachate,
ng/L
30
<5
<5
30
<13
<13
<13
<13
430
54
120
604
270
19
36
325
(a) Depth of samples; B-6 at 1 -2 ft; B-7 at 7-8 ft; and B-8 at 11 -12 ft.
(b) Duplicate.
(c) Values shown represent two soil analyses.
Table C-9. Total of Four Priority Pollutant Metals in Soils and Leachates
Sample designation"
B-6
Chromium
Copper
Lead
Zinc
Total
B-7
Chromium
Copper
Lead
Zinc
Total
B-8
Chromium
Copper
Lead
Zinc
Total
Untreated soil
mg/kg
400
910
2,500
1.000
4,810
43
70
310
240
663
84
59
280
190
613
Untreated
soil leachate
H9/L
10
240
200
2.200
2,650
10
20
<50
290
320
10
20
100
300
430
Treated soil
mg/kg
50
39
140
50
279
47
12
55
80
194
46
6
11
17
80
Treated
soil leachate,
HQ/L
40
60
70
40
210
40
50
<50
30
120
30
40
<50
100
170
* Depth of samples: B-6 at 1 -2 ft; B-7 at 7-8 ft; and B-8 at 11 -12 ft.
62
-------
Appendix D
Case Studies
Data in this Applications Analysis Report have been quoted from case studies provided by IWT
and GE. A summary of each of these sources is included in this appendix and designated below.
D-l Report of Initial Bench Scale Testing Solidification/Fixation Agent Evaluation, 8/86
D-2 Letter Report: Report on Chemical and Physical Laboratory Analyses for Bench Scale
Specimens, 10/10/86
D-3 Data Sheets from Southwestern Laboratories
D-4 Presentation of the HWT Chemical Fixation Technology and Japanese In-Place
Treatment Equipment
D-5 Advanced Chemical Fixation of Organic and Inorganic Content Wastes
D-6 Economic Analysis: Letter from Geo-Con, Inc. to Foster Wheeler Enviresponse, 8/30/88
63
-------
Case Study D-1
Law Environmental Report to General Electric: Report of Initial Bench Scale Testing
Solidification/Fixation Agent Evaluation
Description
A laboratory study was conducted by Law Environmental for General Electric to determine
the effectiveness of the International Waste Technologies HWT-20 additive. Thirty-gallon
samples from the quartz/sand top-soil layer were collected, based on high, medium or low
concentrations of PCBs. The average concentrations of these samples were 5,628, 1,130, and 83
ppm PCBs, respectively. In addition, a sample was collected from a limestone layer (5-10 ft
below grade), which had a concentration of 73 ppm PCBs. From each of the four 30-gal soil
samples, 3 specimens were taken for laboratory analysis of total PCBs.
For each of the three 30-gal sand-samples, 6 batches (18 total) were prepared; on treatment
with the additive, each batch filled 10 molds, 3 in. dia. by 6 in. long. From the limestone
sample, 2 batches were prepared. Each batch prepared (total of 20) used a different additive
concentration, ranging from 0.03 to 0.25 Ib/lb dry soil, at a different moisture range,
representing soil either above and below the water table.
Testing Protocol
The following physical tests were performed on untreated soil samples:
Particle size distribution ASTM D-421-85 and D-422-63
Permeability (constant head) ...ASTM D-2434-68 (reapproved 1974)
Moisture-density relation ASTM D-698-78, Method A
Moisture content ASTM D-2216-80
Chemical analyses of the soil samples were performed using EPA SW-846 Method 3550 for
sample preparation, and Method 8080 for PCB analyses.
Four different leaching procedures were used to evaluate the effectiveness of the HWT-20
additive:
EP Toxicity (standard) with membrane filter.
EP Toxicity with glass fiber filter.
EP Toxicity with glass fiber filter and site water plus sulfurous acid (pH = 5) as the leaching
medium.
Toxicity Characteristic Leaching Procedure (TCLP) using extraction fluid #2.
Major Conclusions
No conclusions are presented in this document.
64
-------
Data Summary
The measured physical properties on the untreated soils were:
Particle size distribution Typical for Hialeah area (distributions not provided)
Compaction test -- Maximum dry density 103 Ib/ft3 at an optimum moisture content of 10 wt%
Permeability 7.4 x 10:3 cm/s (one sample)
The leachate results for the 4 leach tests of pre- and posttreatment samples were as follows:
Leachate results, pg/L(a)
Untreated soil
concentration
mg/kg
1,130
1,130
5,628
5,628
73 (b)
Addictive rate
Ib/lb dry soil
0.15
0.18
0.05
0.25
0.15
EP Tox,
membrane
3.0/1.2
2.0 / 2.0
7.0 / 7.0
2.0 /< 1.0
<1.0/<1.0
EP Tox,
glass fiber
54 / 10
54/3
39/39
39/4
5/<1.0
EP Tox,
site water
13/2.6
13/5.5
65/98
65 / 32
4/<1.0
TCLP
10 /28
10/14
33/119
33/170
1 .3 /3.0
(a) Pretreatment/posttreatment
(b) Limestone
The EP Toxicity (EP Tox) tests showed reductions in PCBs in the leachate of the treated soil
samples compared to that of untreated soil samples over and above that which would occur
from dilution from the additive. The TCLP leachates for the treated soils all had higher PCB
concentrations than the untreated soil. Law Environmental had no explanation for the latter
results.
In addition, LE found that there was an optimum ratio of weight-of-additive/weight-of-water
for maximum treatment effectiveness. This value is in the range of 1.0 to 1.5. Since there was a
consistency among the 3 EP Tox tests, the validity of the EP Tox results, compared to the
TCLP results, is enhanced.
65
-------
Case Study D-2
Law Environmental Letter Report to General Electric: Report on Chemical and Physical
Laboratory Analyses for Bench Scale Experiments
Description
The description provided for Case Study D-l is applicable here.
Testing Protocol
This work consists of analyses that were part of Case Study D-l, but issued subsequent to the
initial report. The results provided are for the treated-soil physical properties, which were not
included in the first case study. The following physical tests were performed on treated soil
samples:
Moisture content ASTM D-4216
Dry unit weight Weight/volume
Permeability (falling head) "Test method for solid waste characterization," Section 13
- Unconfined compressive Strength... ASTM D-2216-80
Major Conclusions
No conclusions presented.
Data Summary
Additive rate
Ib/lb dry soil
0.15
0.10
0.20
0.10
0.15
0.18
0.25
0.15 (c)
0.15 (d)
Mositure content
before/after, %
7.6 / 2.8
9.5 / 5.4
10.1 /4.1
24.4/13.1 (b)
24.5 /13.6 (b)
20.9/11.4 (b)
19.7/9.8 (b)
19.8/9.6 (b)
24.5 / -
Density dry
Ib/fl?
UCS(a)
psi
99.3
103.2
102.8
92.1
92.5
108.5
116.4
115.4
92.7
198
310
299
367
714
1,223
2,127
1,899
Strain at failure, %
0.427
0.351
0.347
0.373
0.472
0.737
1.07
0.936
(a) All height-to-diameter ratios were 2.1 except in the first test, which used a ratib of 1.9.
(b) Moisture content simulating values found below watertable.
(c) Limestone - all other samples are treated quartz sand.
(d) Permeability was 7.6 x 10'8 cm/s.
Some additional treated-soil leachate results were provided subsequent to this letter report. In
these tests, the HWT-20 was added as a slurry to the soil from the same 30-gal batches of
contaminated soil as described in Case Study D-l (previous tests used dry additive) to more
closely simulate field operations. The results were as on the next page:
66
-------
Average PCB concentration in
untreated soil, ppm
1,130
5,628
5,628
5,628
5,628
Additive rate
Ib/lb dry soil
0.15
0.15
0.1 5(a)
0.20(a)
0.1 5(a)
Average PCB
concentration in
treated soil, mg/kg
893
3,942
2,844
3,261
2,929
EP Tox leachate
H9/L
2.45
4.15
4.46
4.13
2.84(b)
(a) Moisture content simulating below watertable.
(b) Used EP Tox with glass fiber filter, substituting site water (no PCBs) for de-ionized water in the
extraction. All EP Tox tests replaced the standard membrane filter with a glass fiber filter.
67
-------
Case Study D-3
Data Sheets from Southwestern Laboratory
Description
Samples were collected from 2 core borings by LE during the demonstration. One boring was at
an anticipated poorly tested area (B-3) based on information compiled by LE on Geo-Con
auger-injection locations and the other was near a treated-soil column center (B-2). Samples
were collected at level increments of 18 to 24 in. and analyzed for PCBs. TCLP leach tests were
then performed on each sample with PCB concentration measured to a detection limit of 0.1 ug/L
Testing Protocol
The samples were cured for approximately 2 weeks before the TCLP leach tests were performed.
The leachate analyses were performed 7 days after the extraction.
Major Conclusions
No conclusions are provided with the data.
Data Summary
Sample
designation(a)
Depth, ft
PCBs in soil,
mg/kg (b)
PCBs in TCLP
leachate, jig/L
B-2 3.0- 3.6 34.9 1.20
B-2 5.0- 5.75 182.0 <0.10
B-2 7.0 - 7.8 206.0 0.22
B-2 9.5-11.0 166.0 0.12
B-2 12.5-14.0 32.8 <0.10
B-2 ' 15.5-17.0 13.7 0.11
B-3 1.5 - 3.0 22.8 <0.10
B-3 3.0- 4.5 47.7 <0.10
B-3 6.0- 7.5 72.7 <0.10
B-3 7.5 - 9.0 57.4 <0.10
B-3 10.5-12.0 . 2.0 <0.10
B-3 13.5-15.0 1.0 <0.10
Blank <1.0 <0.10
(a) These designations are those of LE and are not related to those reported earlier in this report.
(b) PCBs - Araclor 1260
68
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Case Study D-4
Presentation of the HWT Chemical Fixation Technology and Japanese In-Place Treatment
Equipment
Description
This is an informal report prepared by IWT describing the technology. In the report, IWT claims
that their HWT components have the physical characteristics of sorption, where all free water is
absorbed, and of pozzolan-Portland cement where micro-encapsulation occurs in conjunction
with the chemical alteration of the toxic character of the waste. This stabilization, they say, is a
technological improvement over the successful approaches that have been used by the Japanese
since 1970 on large-scale waste cleanups.
It is claimed that the HWT set of chemical fixation products generate complex crystalline
inorganic-polymers. These macromolecules are made up of selected polyvalent inorganic
elements that react in a polyfunctional manner, producing branched and cross-linked polymers
of sufficient density to cause some interpenetrating-polymer-network (IPN) bonding. These
polymers are said to have a high resistance to acids and other naturally existing deteriorating
factors. Structural bonding in the polymer is mainly covalent. There is a two-phased reaction in
which the toxic elements and compounds are complexed first in a fast reaction, and then
permanently complexed further in the building of macromolecules, which continue to generate
over a long time.
The first part of the chemical fixation generates irreversible colloidal structures and ion
exchanges with toxic metals and organics by special intercalation compounds. Phase two is the
generation of the macromolecule framework. This is also a relatively irreversible colloid
synthesis, which is a slower-moving reaction going from soil-mix to gel, to crystalline, three-
dimensional inorganic polymer. The treated material should be able to pass the required
leaching tests within 7 to 28 days. By varying the composition of the HWT treatment
compounds, the bonding characteristics and durability of the structure are varied to suit a
particular waste situation and desired leaching standards.
This paper also describes various in situ technologies used in Japan. The original plan of IWT
was to use the JST Method of deep-soil-mixing of Japan National Railways and Sanwa Kizai
Co., Ltd. This was subsequently changed to the Geo-Con, Inc., deep-soil-mixing equipment.
Testing Protocol
The earliest leach tests performed by IWT for wastes treated with HWT-20 are described. These
tests included:
EP Toxicity for PCBs
Hexane Extraction for Pentachlorophenol (PCP)
TCLP for K051, API separator bottoms
TCLP for a sludge containing 70% water
TCLP for a liquid waste
The hexane extractions show the amount of available contaminant that can be released from the
waste. IWT is claiming that chemical bonding exists between HWT-20 and the contaminants,
and if hexane or methylene chloride cannot extract it, then it is bonded and unavailable to
leaching also.
Major Conclusions
No conclusions are presented in the document.
69
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Data Summary
Contaminants
PCB
PCB
PCB
PCB
POP
PCB
PCB
PCP
POP
PCP
Concentration
in waste, mg/kg
1,140
1,140
6,000
6,000
11,000
1,800
9,200
290-500
290-500
290-500
Type of
waste
Soil
Soil
Soi
Soil
Soil
Oily liquid
Oily liquid
Soil
Soil
Soil
Extraction
test
EP-Tox
Hexane
EP-Tox
Hexane
Methylene chloride
EP-Tox
EP-Tox
Hexane
Hexane
Hexane
HWT-20
additive,
Ib/lb dry
0.15
0.15
0.25
0.25
0.15
0.20
0.20
0.05
0.10
0.15
Cure
time,
days
14
14
28
28
14
3
3
28
28
28
Extractant
concentration,
mg/L
0.006
355
0.00008
1,300
450
0.069
0.337
38
2.3
0.26
Cr 630 K051 TCLP
Pb 332 K051 TCLP
Ethylbenzene 10 K051 TCLP
Xylenes 83 K051 TCLP
Anthracene 19 K051 TCLP
Chrysenene 29 K051 TCLP
Meihylnaphthalene 470 K051 TCLP
Naphthalene 93 K051 TCLP
Phenanthrene 206 K051 TCLP
Acrylonitrile 120 Sludge TCLP
Acrylic Acid 5 Sludge TCLP
Acrolein 59 Sludge TCLP
Acetonitrile 150 Sludge TCLP
Cu 78 Sludge TCLP
Sb 13 Sludge TCLP
Vinyl chloride 1,671 Liquid TCLP
Trichloroethylene 11,200 Liquid TCLP
Trichloroethylane 3,800 Liquid TCLP
Tetrachloroethylene 5,900 Liquid TCLP
0.15-0.25
0.15-0.25
0.15-0.25
0.15-0.25
0.15-0.25
0.15-0.25
0.15-0.25
0.15-0.25
0.15-0.25
0.15
0.15
0.15
0.15
0.15
0.15
0.33 28
0.33 28
0.33 28
0.33 28
0.03-0.04
0.05
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
1.5
0.1
0.5
3.9
0.2
0.7
ND
ND
ND
ND
"Not provided. ND = Nondetected; detection limit not defined.
The PCB and PCP tests show that only a small fraction of these contaminants are extracted by hexane or methylene
chloride.
The PCB and PCP tests show that only a small fraction of these contaminants are extracted by
hexane or methylene chloride.
70
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Case Study D-5
Advanced Chemical Fixation of Organic and Inorganic Content Wastes
Description
This is an informal IWT report, a followup to the one described in Case Study D-4. It describes
test results using a more-advanced additive called HWT-22. The paper describes IWT's view of
the mechanisms for the additive bonding to the contaminants. Results are also presented from
various extraction tests and from infrared scanning and differential scanning calorimetry
(DSC). These latter tests are performed to show changes in the treated waste structure. The
infrared scanning shows shifts in vibrational frequencies between atoms, and DSC measures
changes in energy and temperature to release the contaminants from the soil.
IWT claims a number of unique properties associated with the additives, which are:
The inorganic polymer network can be used as a durable medium with a wide range of types
of bonding with organics and inorganics.
An impact on cement hydration reactions that causes a more effective dispersion of
treatment chemicals throughout the waste.
Promotion of surfactant functions that promote microscopic homogeneity.
Use of intercalation, or linking, compounds to interact with the organic toxins by a sorptive
process. The intercalation compound can be sodium bentonite (or another clay) that has
been reacted with a quaternary ammonium compound. The nature of the amine can be
varied depending on the class of organic toxins to be immobilized.
The paper provides detailed discussion of the bonding mechanisms.
Testing Protocol
Two sets of extraction tests not included in Case Study D-4 are reported, one using TCLP and the
other using solvents of differing polarities. This latter test was performed to show the strength of
bonding of various contaminants of different polarity.
Various organic compounds were selected for a series of infrared and DSC experiments to better
understand the bonding mechanism. The infrared test measures bond lengths after waste
treatment and compares them to the bond length in the untreated contaminant. The DSC test
was performed to measure the energy necessary to release the compounds from the matrix.
Major Conclusions
The following conclusions are provided by IWT on its test work:
- There is true multiple bonding between HWT-22 and organic components of the waste.
- When heat is applied, many of the organics fragment into simpler molecules.
- The total energy to drive organics o.ut of the treatment mix is higher than their normal heats
of vaporization.
- Gas chromatography/mass spectroscopy (GC/MS) data indicate that other bonding reactions
are catalyzed by clay additives.
71
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- The use of processed intercalation compounds chemically alters many classes of organics.
These compounds, combined with cement, blend into a chemical fixation material that is a
viable alternative to other more costly methods of waste treatment.
Data Summary
The following TCLP leach-test results were obtained by adding 0.15 Ib HWT-20/lb dry waste
(before thickening) to K049 slop oil emulsion, which also contained some K048, dissolved air
flotation float from the refinery industry, and K051 API separator bottoms. Kiln dust was
added to the liquid waste on a 1/1 ratio to thicken before the HWT-20 was added. Curing time
was 21 days, and a volume expansion of 25% was experienced.
Contaminant
Cr
Pb
As
Ba
Cd
Hg
Se
Ag
Cu
Zn
Concen-
tration
mg/kg
1.9
16.3
4.8
22.1
2.4
1.3
1.3
57.7
32.7
3.1
TCLP
leachate
concentration
mg/L
0.28
0.08
0.0009
1.4
0.04
0.08
0.005
0.07
0.06
0.005
Contaminant
Ni
V
xylenes
4-methylphenol
isophorone
2-nitrophenol
2,4-dinitrophenol
PCP
phenanthrene
anthracene
Concen-
tration
mg/kg
6.3
173.1
26,500
9.1
2,226
816
316
49
21
28
TCLP
leachate
concentration
mg/L
0.02
0.2
4,605
ND
8.5
1.3
ND
1.3
1.4
1.1
ND = Not detected (detection limit not defined).
The results show that xylenes were leached at a very high rate. IWT changed the formulation to
HWT-21, and the new leachate concentration for xylenes dropped to 48 mg/L.
The following extraction results were obtained by using solvents of various polarities. The
higher the polarity index, the stronger the solvent.
Solvent (polarity index)
Contaminant
Dimethylsulfoxide (7.2) n-Butanol (4.0) Iso octane (0.1)
Extractopm concentration, mg/L
4-Methylphenol
Isophorone
2,4-Dimethylphenol
2-Nitrophenol
Hexachlorobenzene
PCP
Anthracene
Phenanthrene
Methylnaphthalene
10.0
2,179
207.5
724
0.15
21.3
3.3
6.5
0.22
5.5
1,213
116
361
0.10
13.7
4.7
3.9
0.12
1.9
695.3
29.0
91.4
0.24
5.6
22.8
19.2
0.84
The above table reveals that the greater the polarity of organic compound, the stronger the
bonding to the matrix.
72
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Results for the infrared analyses, showing the frequency shifts for the various bonds
studied, are presented below:
Compound
Nitrobenzene
Phenol
Chloroaniline
Chloronaphthalene
Triethanolamine
Treatment material
frequency, 1/cm
1,150
1,720
2,929
934
3,632
662
2,348
3,542
660
2,611 ,
2,297
1,070
Shift from
untreated, 1/cm
-25
-22
- 5
-22
-8
22
6
-48
19
-37
193
-5
Peak assignment
Aromatic mono substitution
C-N stretch
C-H stretch
C-O stretch
H-bonded OH
C-CI stretch
C-H stretch
N-H stretch
C-CI stretch
C-H stretch
Amine salt formation
H bonding
Some of the numerical results from the DSC tests were:
Compound
Phenol
Trichloroethylene
Nitrobenzene
Triethanolamine
Literature value
for heat of vaporization
kcal/mole
11.89
8.32
12.17
12.78
Observed heat
of vaporization
kcal/mole
38.13
34.43
18.6
24.16
% Increase
220.7
314.2
52.8
87.8
Additional observations of IWT are:
- All compounds leave the matrix at more than one temperature.
- Total energy involved in the treated matrix was much higher than the heat of vaporization of
the pure compounds.
- When the effluent gases were analyzed, neither the original compound nor any of its
fragments were seen.
73
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Case Study D-6
Economic Analysis: Letter from Geo-Con, Inc., to Foster Wheeler Enviresponse, Inc., 8/30/88
Description
Geo-Con provided cost information for remediating the Hialeah, Fla., site using either a 1-auger
or 4-auger machine. All costs provided include overhead and profit. The input is based on using
15 Ib HWT-20 additive/100 Ib dry soil.
Cost Component, $/yd3
4-Auger
Labor 22.00
Equipment 28.00
Subcontracts 6.00
Other (purchases, insurance, health and safety) 9.00
Materials (HWT-20) 85.00
Mobilization/Demobilization, $
Labor 26,000
Equipment 24,000
Subcontracts (trucking, etc.) 18,000
Other (purchases, insurance) 22,000
Subtotal 90,000
Capital Costs. $
Augers 125,000
Flow control system 132,000
DSM drill 368,000
Leads 42,000
Power Pack 84,000
1-Auger
55.00
70.00
18.00
25.00
85.00
9,000
8,000
10,000
5,000
32,000
7,000
20,000
N/A
N/A
N/A
Subtotal 751,000
27,000
74
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References for Appendices
1. Tittlebaum, M.E., et al. State-of-the-Art on
Stabilization of Hazardous Organic Liquid
Wastes and Sludges, in CRC Critical Reviews in
Environmental Control, Vol. 15, Issue 2, CRC
Press, Boca Raton, Fla., 1985, pp. 179-211.
2. HandbookRemedial Action at Waste Disposal
Sites. EPA 625/6-85/006. USEPA, ORD,
Cincinnati, Ohio and OSWER, Washington,
D.C., 1985.
3. Guide to the Disposal of Chemically Stabilized
and Solidified Waste. USEPA, SW-872 Revised.
Municipal Environmental Research Laboratory,
ORD, Cincinnati, Ohio, 1982.
4. Technology Evaluation Report International
Waste Technologies In Situ Stabiliza-
tion/Solidification, USEPA ORD/RREL,
Cincinnati, Ohio, 1989.
5. Prohibition on the Placement of Bulk Liquid
Hazardous Waste in LandfillsStatutory
Interpretive Guidance. EPA 530-SW-86/016,
OSWER, Washington, D.C., 1986.
75
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