United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
EPA/540/A5-90/008
March 1991
Toxic Treatments, In Situ
Steam/Hot-Air Stripping
Technology
Applications Analysis Report
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION =
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EPA/540/A5-90/008
March 1991
Toxic Treatments, In Situ Steam/Hot-Air Stripping Technology
Applications Analysis Report
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Printed on Recycled Paper
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Notice
The information in this document has been funded by the U.S. Environmental
Protection Agency under Contract No. 68-03-3485 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.
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Foreword
The Superfund Innovative Technology Evaluation (SITE) Program was
authorized by the 1986 Superfund Amendments and Reauthorization Act (SARA).
The program is a joint effort by EPA's Office of Solid Waste and Emergency
Response (OSWER) and Office of Research and Development (ORD) to enhance
the development of hazardous waste treatment technologies necessary for imple-
menting new cleanup standards that require greater reliance on permanent rem-
edies. This is accomplished by performing technical demonstrations that provide
engineering and economic data on selected technologies.
This project consists of an analysis of the Toxic Treatments (USA), Inc.,
(TTUSA) in situ steam/hot-air stripping technology. A Demonstration Test took
place at a former bulk liquid waste storage facility, located at the GATX Annex
Terminal site in San Pedro, California. The purpose of the demonstration was to
obtain information on the performance and cost of the process in order to assess
the technology's potential application at other hazardous waste sites. The Tech-
nology Evaluation Report describes the field acdvities and laboratory results.
This Applications Analysis Report provides an interpretation of the available data
and a discussion of the 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 Jr
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 Building Springfield
Virginia 22161, (703) 487-4600. Reference copies will be available in the
Hazardous Waste Collection atEPA libraries. Information regarding the availability
of other reports can be obtained by calling the SITE Clearinghouse Hotline at
(800) 424- 9346 or (202) 382-3000 in Washington, D.C.
C-
E. Timothy Oppelt.'Dlrector
Risk Reduction Engineering Laboratory
Hi
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Abstract
This document is an evaluation of the performance of the Toxic Treatments
(USA), Inc., (TTUSA) in situ steam/hot-air stripping technology and its applica-
bility as an on-site treatment technique for hazardous waste site soil cleanup of
volatile and semivolatile contaminants. Both technical and economic aspects of the
technology were examined.
A demonstration of the TTUSA stripping technology was conducted beginning
in the fall of 1989 at the GATX Annex Terminal site located at the Port of Los
Angeles, California. Operational data and sampling and analysis information were
carefully compiled to establish a data base against which other available data, as
well as the vendor's claims for the technology, could be compared and evaluated.
Conclusions concerning the technology's suitability for use in stripping the range
of contaminants at this test site were reached, and extrapolations regarding appli-
cations at other sites with different contaminants and soil types were made.
The following conclusions were derived primarily from the Demonstration
Testresults and supported by other available data: (1) the process removed volatile
organic compounds at an average efficiency of approximately 85% from the
contaminated soils tested; (2) the technology reduced the level of semivolatile
compounds in the soil by approximately 50%; (3) there was no evidence of
significant downward migration of contaminants based on qualitative testing; (4)
fugitive emissions from the soil during and after treatment were low; and (5) the
process is capable of removing volatile organic compounds in situ in relatively short
time periods with competitive economics.
IV
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Contents
Foreword iii
Abstract iv
Tables vi
Figures vi
Abbreviations and Symbols vii
Acknowledgments viii
1. Executive Summary 1
Introduction 1
Conclusions 1
Results 2
2. Introduction 3
The SITE Program 3
SITE Program Reports 3
Key Contacts 4
3. Technology Applications Analysis 5
Introduction 5
Conclusions 5
Technology Evaluation 6
Ranges of Site Characteristics Suitable for the Technology 11
Environmental Regulations and Comparison with TTUSA Stripping Technology Performance 12
4. Economic Analysis 15'
Introduction , 15
Results of Economic Analysis 15
Basis of Economic Analysis 20
References 24
Appendix A—Vendor's Claims 25
Introduction 25
Potential Application 25
System Advantages 25
The Process 26
System Limitations 26
Cost Information 27
Appendix B—SITE Demonstration Test Results 28
Volatiles in Soil 28
Semivolatiles in Soil 28
Dye Studies 28
Condensed Organics 29
Treated Water 29
Fugitive Emissions 29
TCLP Results 29
Physical Tests 29
Appendix C—Process Description 31
The Process Tower 31
The Gas Treatment System ; 31
The Distillation System 31
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Appendix D—Case Studies 33
Baseline Testing .33
Process Improvement and Soil Vapor Emissions Tests 34
Mixing, Treatment, and Downward Migration Tests 35
TTUSA Bench-Scale Tests 36
Six-Week Deep Study 37
References , 39
Tables
1. Demonstration Test Results for Volatiles 7
2. Estimated Costs in $/Cubic Yard 16
3. Summary of Estimated Costs in $/Cubic Yard for Various Treatment Rates
and On-line Operating Factors 21
4. Vendor's Cost Estimates 27
5. Demonstration Test Results for Semivolatiles 29
6. Fugitive Emissions from Blocks A-28-e, A-29-e, and A-30-e 30
7. Demonstration Test Results for Physical Properties 30
8. Chemical Analysis Results for Baseline Testing 34
9. Physical Analysis Results for Baseline Testing 35
10. Spiked-Soil Contained-System Tests Results 38
11. Contaminated-Soil Contained-System Tests Results 38
Figures
1. Sampling locations for fugitive emissions 10
2. Summary of cost breakdown for 12 cost categories 19
3. Demonstration results for fluorescein dye. 30
4. Schematic of the process tower 32
VI
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Abbreviations and Symbols
ARAR
BOAT
BTU
C
CAA
CERCLA
CFR
CWA
DHS
DOT
EPA
F
FID
ft
gal
GATX
GC
g
gpm
kg
kW
kWh
Ib
L
MCL
MCLG
MDL
mg
Hg
min
ml
NPDES
NPL
ORD
OSWER
OVA
PAH
ppb
ppm
ppmV
psig
%
RCRA
RREL
s
SAIC
SARA
Applicable or Relevant and Appropriate Requirements
Best Demonstrated Available Technology
British Thermal Unit
Celsius
Clean Air Act
Comprehensive Environmental Response Compensation and Liability Act
Code of Federal Regulations
Clean Water Act
Department of Health Services (California)
Department of Transportation
Environmental Protection Agency
Fahrenheit
Flame lonization Detector
Feet
Gallons
GATX Terminals Corporation
Gas Chromatograph
Gram
Gallons per minute
Kilograms
Kilowatts
Kilowatt-hours
Pounds
Liters
Maximum Contaminant Level
Maximum Contaminant Level and Goal
Method Detection Limit
Milligrams
Micrograms
Minutes
Milliliters
National Pollutant Discharge Elimination System
National Priority List
Office of Research and Development
Office of Solid Waste and Emergency Response
Organic Vapor Analyzer
Polynuclear Aromatic Hydrocarbon
Parts per billion
Parts per million
Parts per million Volume
Pounds per square inch gauge
Percent
Resource Conservation and Recovery Act
Risk Reduction Engineering Laboratory
Seconds
Science Applications International Corporation
Superfund Amendment and Reauthorization Act
vii
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scfm
SCAQMD
SDWA
SITE
SW
SVC
TCLP
THC
TSD
TTUSA
VAC
VOC
Standard cubic feet per minute
Southern California Air Quality Management District
Safe Drinking Water Act
Superfund Innovative Technology Evaluation
Solid Waste
Semivolatile Compound
Toxicity Characteristic Leaching Procedure
Total Hydrocarbons
Treatment, Storage, and Disposal
Toxic Treatments (USA), Inc.
Voltage Alternating Current
Volatile Organic Compound
Acknowledgments
This report was prepared under the direction and coordination of Mr. Paul de
Percin,EPASuperfundInnovativeTechnology Evaluation (SITE)Program Manager
in the Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio. Con-
tributors and reviewers for this report were James Cummings and Richard Nalesnik
of U.S. EPA, Washington, D.C.; Stephen James, Robert Olexsey, John Martin, and
Guy Simes of U.S. EPA, RREL, Cincinnati, Ohio; and Phil La Mori of TTUSA, San
Francisco, California.
This report was prepared for EPA's SITE Program by the Process Technology
Division of Science Applications International Corporation (SAIC) for the U.S.
EPA under Contract No. 68-03-3485.
VIII
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Section 1
Executive Summary
Introduction
This report summarizes the findings of an evaluation of
the in situ steam/hot-air stripping technology developed by
Toxic Treatments (USA), Inc. (TTUSA). The study was con-
ducted under the Superfund Innovative Technology Evaluation
(SITE) Program. A Demonstration Test of the technology was
performed by EPA as part of this Program. The results of this
test, along with supporting data from other testing performed
by TTUSA and background information from literature con-
stitute the basis for this report.
The TTUSA technology is a mobile .in situ stripping
process that utilizes steam and hot air to treat soils contaminated
with volatile compounds without the need for excavation.
Previous experience with steam/hot-air stripping systems has
demonstrated that a large fraction of the volatile compounds
can be stripped from the soil and that semivolatile compound
levels can be reduced to some extent The level of contaminant
removal is dependent on the following factors: contaminants
present, treatment time, soil conditions, chemical reactions,
and soil binding.
Conclusions
A number of conclusions may be drawn from the evalua-
tion of this innovative technology. The most extensive data
were obtained during the SITE Demonstration Test; data from
other testing activities have been evaluated in relation to SITE
Program objectives. The conclusions drawn are:
• The process can remove a significant amount of VOCs
from contaminated soil.
• Treatment of a contaminated area can successfully extend
into the saturated zone. Percent removal and treatment
rates are comparable to treatment in the vadose zone.
• The system operates in a batch-like fashion such that the
amount of volatile contaminants removed from the soil is
a function of treatment time.
• The in situ steam/hot-air stripper can also reduce the level
of semivolatile organic compounds in the soil treatment
block. Although the semivolatiles detected prior to treat-
ment are not present in the post-treatment soil, they remain
unaccounted for elsewhere in the process.
• Data obtained from qualitative dye studies in and below
the treatment area do not indicate downward migration of
organic contaminants to below the zone of treatment.
Total fugitive emissions from the soil during and after
treatment are low. Process fugitive emissions are also low
apart from emissions during regeneration of the gas-
phase carbon beds. Recent design modifications to the
process have alleviated this problem.
The mixing action of the augers does not produce a
homogeneous area of treatment. Chemical analyses for
volatile and semivolatile contaminants and dye test data
indicate that substantial variations occur within treated
soil blocks.
The treatment process did not affect the physical proper-
ties of the tested soil to any significant extent. Neither
moisture content nor bulk density of the soil are influenced
to any statistical degree by the addition of steam to the
treatment area.
The TTUSA process can strip VOCs from a variety of soil
types. Soils with a high clay content have a binding effect
on the compounds which results in long treatment time
requirements for this type of soil. Sandy soils lend them-
selves to much shorter remediation times than clay soils.
Soils with moderate amounts of clay can be treated
readily by the TTUSA process. Increased clay content
decreases economical feasibility of treatment
• VOCs with high boiling points, such as tetrachloroethene,
require a greater soil block treatment time than volatile
compounds with low boiling points such as methylene
chloride.
• The unit is transportable on 5 tractor/trailer rigs, 1 of
which is deemed an oversize load. Assembly and disas-
sembly times are each estimated at one week.
• The in situ steam/hot-air stripper is an attractive eco-
nomical alternative to other soil stripping technologies
for sites that require short remediation times. The cost of
operating the system is strongly dependent on the treatment
time required per block.
Successful operation of the in situ steam/hot-air stripper
is limited by several logistical considerations. Depending on
the treatment area, site preparation activities may be extensive
or even prohibitive. The treatment area must be graded to a
minimum slope of 1% and must be greater than 0.5 acre in
size (at least 2 acres total site area). The treatment area must
be compacted sufficiently to support the unit's weight. All
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underground obstacles larger than 12-in diameter and over-
head wires lower than 30 ft must be removed.
Results
• For treatment in the vadose zone to a depth of 5 ft, the
level of volatile contaminants in the soil can be reduced
to an average concentration less than the target level .of
100 ppm. The average removal efficiency of the TTUSA
process on volatile contaminants is approximately 85%.
For treatment which extends into the saturated zone and
below the zone of contamination, the level of volatile
contaminants in the soil can also be reduced to an average
concentration less than the target level of 100 ppm.
• The amount of semivolatile contaminants in the soil can
apparently be reduced by approximately 50%. The fate of
these semivolatiles remains unknown.
The largest contributor to soil fugitive emissions is the
block that has just been treated, after the shroud has been
moved to a new position. This block has its highest
emission rates immediately upon completion of treat-
ment, but these rates decrease rapidly with time.
Moisture content and bulk density appear to change slightly
as a result of treatment, however this effect is not statis-
tically significant. Particle density, which was evaluated
only during the SITE Demonstration, was found to increase
by an average of 6.5%.
During normal operation of the stripper, the process can
achieve an on-line treatment time factor of approximately
70%.
For a treatment rate of 3 yd3/hour and an on-line factor of
70%, the cost based on an economic analysis is $317/yd3;
if the treatment rate can be increased to 10 yd3/hr with the
same on-line factor, the cost drops to $11 I/yd3.
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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. Now in its fourth year, SITE is helping to
provide the treatment technologies necessary to implement
new federal and state cleanup standards aimed at permanent
remedies, rather than quick fixes. The SITE Program is com-
posed of three major elements: the Demonstration Program,
the Emerging Technologies Program, and the Measurement
and Monitoring 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 funding for technology developers. EPA
and developers participating in the program share the cost of
the demonstration. Developers are responsible for demon-
strating their innovative systems at chosen sites, usually Su-
perfund 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 infor-
mation 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 Dem-
onstration Program by responding to EPA's annual solicitation.
EPA will also accept proposals at any time when a developer
has a treatment project scheduled with Superfund waste. To
qualify for the program, a new technology must be at the pilot
or full scale and offer some advantage over existing technolo-
gies. Mobile technologies are of particular interest to EPA.
Once EPA has accepted a proposal, EPA and the devel-
oper 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 sam-
pling 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.
The second principal element of the SITE Program is the
Emerging Technologies Program, which fosters the further
investigation and development of treatment technologies that
are still at the laboratory scale. Successful validation of these
technologies could lead to the development of a system ready
for field demonstration. The third component of the SITE
Program, the Measurement and Monitoring Technologies
Program, provides assistance in the development and demon-
stration of innovative technologies to better characterize Su-
perfund sites.
SITE Program Reports
The analysis of technologies participating in the Demon-
stration Program is contained in two documents: the Technol-
ogy Evaluation Report and the Applications Analysis Report.
The Technology Evaluation Report contains a comprehensive
description of the demonstration sponsored by the SITE pro-
gram and its results. It gives a detailed description of the
technology, the site and waste used for the demonstration,
sampling and analysis during the test, the data generated, and
the quality assurance program.
The scope of the Applications Analysis Report is broader
and encompasses estimation of 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 technol-
ogy.
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 waste, 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 demonstra-
tion. A successful field demonstration does not necessarily
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assure that a technology will be widely applicable or fully
developed to the commercial scale. The Applications Analy-
sis 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.
Key Contacts
For more information on the demonstration of the TTUS A
technology, please contact:
1. EPA Project Manager concerning the SITE demonstra-
tion:
Mr. Paul de Percin
US. EPA
Risk Reduction Engineering Lab.
26 W. Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7797
2. Regional contact concerning the San Pedro, California
site:
Ms. Julia Bussey
California DepL of Health Services
Toxic Substances Control Division
4250 W. Broadway, Suite 360
Long Beach, CA 90802
(213) 590-4930
3. Vendor concerning the process:
Dr. Phil La Mori
Toxic Treatments (USA), Inc.
151 Union Street, Suite 155
San Francisco, C A 94111
(415) 391-2113 ;
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Section 3
Technology Applications Analysis
Introduction
This section of the report addresses the applicability of
the Toxic Treatments (USA), Inc. or TTUSA process to
various potential soil contaminants and site conditions based
primarily upon the results obtained from the SITE:demon-
stration as well as additional TTUSA applications test data.
Since the results of the Demonstration Test provide the most
extensive data base, conclusions on the technology's effec-
tiveness and its applicability to other potential cleanups are
based primarily on those results, which are presented in detail
in the Technology Evaluation Report. Additional information
on the TTUSA technology, including vendor's claims, a brief
process description, a summary of the Demonstration Test
Results, and reports on outside sources of data using the
TTUSA technology are provided in Appendices A-D.
Following are the overall conclusions drawn on the
TTUSA technology. The "Technology Evaluation" subsection
discusses the available data from the Demonstration Test,
TTUSA, and literature: This subsection also provides more
details on the conclusions and applicability of the TTUSA
process.
Conclusions
In general, stripping technologies operate to remove a
select species from a given media. This technology moves
from treatment block to treatment block to remove VOCs
from soil at a contaminated site; it also reduces the level of
semivolatile organic contamination, although the mechanism
of reduction and ultimate fate of the semivolatiles is unknown.
Long-term effectiveness of this process is promising since the
source of contamination is removed or significantly reduced.
The overall removal efficiencies for volatile compounds
by the TTUSA in situ steam/hot-air stripping technology are
high; the efficiencies for reducing (not removing) the amount
of semivolatiles present in the soil are moderate. Post-treatment
levels of contamination are dependent on treatment time and
operational technique, but low levels of volatile contamina-
tion can be attained without significant downward migration,
fugitive emissions, or effects on the physical properties of the
soil.
The conclusions drawn from reviewing data on the TTUSA
in situ steam/hot-air stripping process are:
• The process can strip a substantial amount of VOCs from
contaminated soil.
t
Treatment of a contaminated area can successfully extend
into the saturated zone. Percent removal and treatment
rates are comparable to treatment in the vadose zone.
Batch operation of the system allows the amount of
volatile contaminants removed from the soil to be varied
as a function of treatment time.
The in situ steam/hot-air stripper can reduce the level of
semivolatile organic compounds in the treated soil. How-
ever, the fate of semivolatile contaminants has not been
determined.
Qualitative data obtained from dye studies conducted in
and below the treatment area do not indicate downward
migration of organic contaminants to below the zone of
treatment.
Total fugitive emissions from the soil as a result of
treatment are low. Process fugitive emissions are also low
apart from emissions during regeneration of the gas-
phase carbon beds. The design of the carbon bed system
has been modified to alleviate this problem.
The mixing action of the augers does not produce a
homogeneous area of treatment. In fact, the treated block
is very heterogeneous in nature. Chemical analyses for
volatile and semivolatile contaminants and dye test data
indicate that substantial variations occur within treated
soil blocks.
The treatment process does not affect the physical prop-
erties of the soil to any significant extent Although
treatment is conducted with steam, neither moisture con-
tent nor bulk density of the soil are influenced.
The TTUSA process can strip VOCs from a variety of soil
types. The impact of soil type is more economic than
operational, i.e., soils with a high clay content have a
binding effect on the compounds, resulting in long treat-
ment time requirements for this type of soil; sandy soils
lend themselves to much shorter remediation times than
clay soils.
VOCs with high boiling points, such as tetrachloroethene,
require a greater block treatment time than volatile com-
pounds with low boiling points such as methylene chlo-
ride.
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Several site limitations must be effectively addressed to
facilitate successful operation of the in situ steam/hot-air
stripper. Depending on the treatment area, site preparation
activities may be extensive or even prohibitive. The treatment
area must be graded to a minimum slope of 1% and must be
greater than 0.5 acre in size (at least 2 acres total site area).
The treatment area must be compacted substantially to accom-
modate support for the unit's weight. All underground obstacles
larger than 12-inch diameter and overhead wires lower than
30 feet must be removed. \
Technology Evaluation
The following discussions utilize all available information
to provide more detailed conclusions on the process, particu-
larly as related to chemical and operational test results. A
summary of the data from the Demonstration Test is presented
in Appendix B; data from other tests conducted on the tech-
nology may be found in Appendix D, "Case Studies". Detailed
estimates regarding the cost of using this technology are
presented in a separate section of this report, Section 4,
"Economic Analysis".
Chemical Test Results
The TTUSA in situ steam/hot-air stripping technology is
designed to remove VOCs from contaminated soil. Testing
activities have demonstrated that the process can effectively
meet this design criteria; an average removal efficiency of
approximately 85% was achieved during the SITE Demon-
stration Test for VOCs. Tests have also revealed a second,
unexpected consequence of the stripping process: it reduces
the level of semivolatile organic compounds in the soil, to a
moderate degree. The in situ steam/hot-air stripper has dem-
onstrated the ability to diminish the level of semivolatiles by
approximately 50%, although the fate of these semivolatiles
was not determined.
The SITE Demonstration Test was conducted in Area A
of the GATX Annex Terminal site. Sampling activities took
place in a 12-block test area where the contaminated soil was
treated only to the water table (to a depth of 5 feet) and in a 6-
block test area where an alternative treatment protocol was
implemented to treat the soil into the saturated zone and below
the full zone of contamination (to depths ranging from 8 to 11
feet). Screening data indicated that the selected test blocks
were heavily contaminated with both volatile and semivolatile
contaminants and that the soil in both areas had a high clay
content This provided a demanding test on the ability of the
equipment to remove substantial amounts of contamination
from the soil. On the other hand, high removal efficiencies
were relatively easy to obtain due to the high initial concen-
trations of the contaminants.
Demonstration Test pre-treatment soil cores obtained from
the 12-block test area showed average initial levels of con-
tamination from 28 parts per million (ppm) up to 1,130 ppm
total VOCs. Post-treatment cores in this area indicated signifi-
cant decreases in the level of volatile organics, with average
levels ranging from 12 up to 196 ppm total VOCs. Based on
composite samples, the average concentration in the 12-block
test area was 71 ppm with a standard deviation of 80 ppm. The
95% confidence interval range for the true mean of the post-
treatment cores was 45 to 98 ppm. Table 1 presents a summary
of these results. The most dominant chemical species were
consistently chlorobenzene, trichloroethene, and
tetrachloroethene. Percent removal in individual blocks in the
12-block test area varied from 54% to 96% with an average
value of 85%. Similar results have been obtained in tests
conducted throughout the Annex Terminal site by TTUSA.
Baseline Testing of 10 blocks in Areas A, B, and D demon-
strated an average post-treatment volatile contaminant con-
centration of 61 ppm. Average pre-treatment concentration of
volatile contaminants in these blocks was 2,140 ppm.
In the 6-block test area, the final volatile contamination
within a block was reduced to an average level ranging from
16 to 119 ppm (based on the analyses of composite cores).
The average for the entire 6-block test area was 53 ppm total
volatile organics with a standard deviation of 73 ppm. The
95% confidence interval range for the true mean of the post-
treatment cores was 19 to 87 ppm. These results are also
summarized in Table 1. Ketones (specifically acetone, 2-
methyl-4-pentanone, and 2-butanone) were found to be the
primary contaminants in the post-treatment soil. Percent re-
moval data could not be calculated for treatment in this area
since pre-treatment data was only available for one discrete
depth of one core obtained from the 6-block test area. The
purpose of this additional testing was not to determine process
efficiency, but only to evaluate contaminant concentration
after treatment
While the percent removal for VOCs is impressive, the
important evaluation criterion here is not so much the amount
of contamination removed, as it is the level to which the
contamination is reduced. TTUSA's operational objective
was to obtain a final contamination level in the soil of 100
ppm or less. The post-treatment contamination level appears
to be a function of the treatment time. The longer a block is
treated, the lower the final contamination level for that par-
ticular block.
A significant finding from the second phase of post-
treatment sampling (in the 12-block test area) during the
Demonstration Test was that, one in every 6 sampled cores
(composite or discrete) still showed levels of contamination
above the 100 ppm target level. This finding had not been
identified during previous testing and is discussed in more
detail in the Technology Evaluation Report. Discrete samples
from blocks A-31-e and A-35-e both show that the lower
portion of the block appears to be less well treated. However,
this may be due to the manner in which the stripper was
operated, i.e., the augers may have passed below the maximum
treatment depth (5 feet in the 12-block test area) and brought
up contamination from below the treated area without allow-
ing sufficient time for treatment of this contaminated soil. If
this was the case, then generation of a buffer zone or treatment
to below all zones of contamination would eliminate this
problem.
To further investigate this theory, phase three post-treat-
ment sampling of the Demonstration Test was conducted in
the 6-block test area where the soil was treated to below the
full zone of contamination. Here, one in every 9 soil cores
obtained from this sampling effort demonstrated post-treat-
ment contamination levels above 100 ppm. This is not statis-
tically different from the 1 in 6 cores above 100 ppm in the
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Table 1. Demonstration Test Results for Volatiles
12-Block Test Area
Block
Number
A-25-e
A-26-e
A-27-e
A-28-e
A-29-e
A-30-e
A-31-e
A-32-e
A-33-e
A-34-e
A-35-e
A-36-e
Avgb
StdDev*
Pre-
Treatment
fag/g)
54
28
642
444
850
421
788*
479
1133
431
283
153
466
457
Post-
Treatment
fag/8)
14
12
29
34
82
145
61
64
104
196
60
56
JT
80
Percent
Removal
(%)
73
56
96
92
90
65
92
87
91
54
79
64
~85
NAC '•
6-Block Test Area
Block
Number
A-26-n
A-27-n
A-28-n
A-29-n
A-30-n
A-31-n
Avgb
StdDev*
Pre-
Treatment
fag/8)
NA
NA
NA
NA
NA
NA
NA
NA
Post-
Treatment
fag/g)
16
22
36
80
119
45
~53~
73
Percent
Removal
(%)
NA
NA ;
NA
NA
NA
NA
NA
NA
" Only analyses of 2 of the 3 sample cores taken were
available.
b Reported for the entire treatment area based on analysis of
all composite cores.
"Not applicable.
12-block test area. Therefore, these data do not fully support
the idea that residual contamination above 100 ppm was due
to bringing untreated soil into the treated area. Untreated soil
below the maximum treatment depth in the 6-block test area
did not show signs of contamination.
Although a direct comparison cannot be made between
the performance of the in situ steam/hot-air stripper in the 12-
block test area and the 6-block test area, intuitively the strip-
per seems to have performed better in the 6-block test area.
The initial levels of contamination appeared to be higher
based on in-line monitoring equipment and the soil had a
higher clay content. Also, volatile contamination in the 6-
block test area was primarily ketones with no significant
concentrations of the contaminants detected in the 12-block
test area (i.e., chlorobenzene, trichloroethene, and
tetrachloroethene). Ketones may be more difficult to remove
because of their increased water solubility.
During TTUSA's Baseline Calibration test, TTUSA de-
veloped a correlation between the in-line monitoring equip-
ment [a flame ionization detector (FID) and a gas
chromatograph (GC)] which measure VOC concentrations in
the shroud and the actual VOC contamination in the soil. This
correlation provides a contamination profile during operation;
it also acts as an indicator to determine the termination point
for treatment of a particular block. TTUSA's operational
objective is to attain less than 100 ppm total VOCs in each
block treated. The results of TTUSA's Baseline Testing;
Process Improvement and Soil Vapor Emissions Tests; and
Mixing, Treatment, and Downward Migration Tests (see Ap-
pendix D), however, show that VOC contamination levels in
only 75% of the 16 blocks tested (in Areas A, B, and D) were
reduced to below 100 ppm. The Demonstration Test was
conducted entirely in Area A. Volatile organic contamination
levels in 75% of the blocks in the 12-block test area and 83%
of the blocks in the 6-block test area sampled during the
Demonstration Test were reduced below this target level
based on averaging the three composite cores obtained from
each block. All previous sampling by TTUSA in Area A had
indicated that the technology had reduced the VOC level to
below the desired 100 ppm in 100% of the blocks sampled. In
their testing, however, TTUSA determined the final treatment
level by taking two discrete samples from one core within the
treated block. These discrete samples were taken at depths of
2.5 and 4.5 feet. The sampling and analysis performed during
the Demonstration Test was much more extensive than had
been previously accomplished. It is possible'that the TTUSA
sampling strategy was not comprehensive enough to find local
zones of high contamination after treatment of the block.
The failure of the process to reduce VOC contamination
to the target level in some of the test blocks is likely related to
a deficiency in the FID-GC/soil contamination correlation,
not the technology itself. This correlation estimates the actual
soil contamination based on FID readings which are verified
by GC readings. Both the FID and GC give an average
reading of the level of organic compounds in the shroud. "Hot
spots" in the soil within the treated block are not identified by
either of these instruments. There is potential for error in both
the initial generation of the correlation and the actual practice
of utilizing it. The technology has technically demonstrated
the ability to reduce contamination in soil to very low levels.
The residual contamination levels above 100 ppm encountered
in some treatment blocks may be attributed to operational, not
technical, factors. All of the blocks in the Demonstration Test
that had an average contamination level greater than 100 ppm
after treatment had final FID readings that were relatively
high. It appears that, to achieve a low cleanup level without
any "hot spots", the average FID attained on the final pass
should be as low as possible with respect to the target treatment
level. Failure to reduce the shroud FID reading throughout the
entire treatment block can lead to incomplete treatment in
portions of the block. This requirement obviously conflicts
with the economics of the process since site cleanup becomes
more expensive as treatment time per block increases.
Semivolatile contamination in the 12-block test area prior
to treatment was high,-ranging from 336 up to 1,400 ppm total
-------
S VCs. Post-treatment contamination was reduced to levels as
low as 49 ppm and as high as 818 ppm total SVCs. As
previously mentioned, however, the fate of these semivolatiles
has not been determined. The major semivolatile contaminants
found in the soil during the Demonstration Test were bis(2-
cthylhexyl)phthalate and phenols. Levels of semivolatile con-
taminants were reduced on average by over 50%. This is
comparable to other studies conducted on SVCs: the Bench-
Scale Tests indicated levels of SVCs reduced ranged from
approximately 45% to 85%; reduced levels of SVCs calculated
during the Baseline Testing were 65% to 95%. The higher
percent removals of SVCs obtained during independent
TTUSA testing is a result of higher initial concentrations.
Appendix D, "Case Studies", describes the results of these
tests.
Poor SVC mass balances encountered throughout testing
activities raised questions regarding the fate of semivolatiles
as a result of treatment The Bench-Scale Tests (see Appendix
D) were performed in part to address this issue. Although
several theories have been investigated, none provide any
supporting data. One possible explanation for the poor semi-
volatile mass balances is that a reaction of the phthalate
compounds, catalyzed by the clay in the soil, is taking place.
The expected result of such reactions would be phthalate salts,
which are chemically bound to the soil, and alcohols, which
would decompose and dehydrate to form C8 - CIS aliphatic
hydrocarbons. However, analysis of post-treatment samples
does not indicate the presence of these compounds. The
probability that the SVCs may have migrated down below the
treatment block by the flushing action of condensing steam
from the treatment process was also investigated during the
Demonstration Test Qualitative fluorescein dye testing indi-
cated that downward migration of the dye did not appear to be
a result of treatment which confirmed earlier testing by TTUSA
(see Mixing, Treatment, and Downward Migration Tests,
Appendix D).
The SVC reduction percentages reported for the Bench-
Scale Tests (45% to 85%), obtained in a contained system, are
comparable to results obtained during full-scale testing. Large
amounts of SVCs were still unaccounted for in the contained
system tests. The results of the Bench-Scale Tests suggest that
downward migration, biological activity, and dilution by mix-
ing are not significant factors in the field treatment results.
The 1240 L of condensed organics collected in the hold-
ing tank during treatment of the 12-block test area separated
into two distinct phases. The top phase was clear and colorless
with a density of 0.997 g/mL. This phase consisted primarily
of water with only about 1% organic contamination. The
bottom phase was yellowish in color and slightly opaque with
a density of 1.192 g/mL. This phase was over 90% condensed
organics, mostly volatiles. The volume of the top phase was
more than twice that of the bottom phase. This was typical of
normal operational conditions. The volume of the upper phase
(mostly water) can easily be reduced by recycling the top
phase liquid through the distillation system. The distillation
system removes the majority of the water and directs it to the
cooling tower; the remaining condensed organics are again
directed to the holding tank to await disposal. Chlorobenzene,
trichloroethene, and tetrachloroethene dominated the chemical
composition of the condensed organics collected during the
treatment of the 12-block test area. This was anticipated since
these three volatile compounds were the major soil contami-
nants.
Prior to passing through the wet carbon bed after the
distillation process, the average volatile contamination level
in the water stream during treatment of the 12-block test area
was approximately 280 ppm; semivolatile contamination av-
eraged approximately 140 ppm. The water stream showed
significant reductions in contamination levels after passing
through the wet carbon bed. The levels decreased by an
average of 97% for volatile contaminants and 99% for
semivolatiles. Residual VOC levels averaged near 8 ppm;
residual semivolatile organic compound levels averaged less
than 55 ppb. The carbon bed thus removes significant amounts
of contaminants from the water stream and reduces the final
concentration of contaminants in this stream to a satisfactory
degree. Residual contamination in the treated water is released
as an air emission, not a water discharge. The impact of
residual contamination is somewhat diminished by the dilu-
tion effect of the treated water stream upon entering the
cooling tower sump. Organic vapor analyzer (OVA) readings
taken during the Demonstration Test of the exhaust plume of
the evaporative cooling tower did not detect any volatilization
of organic compounds in the tower sump.
The in situ steam/hot-air stripper operates as a closed
process except when one of the dry activated carbon beds is
undergoing regeneration. The only potential escape path for
contaminants leaving the system is in the air discharged from
the inactive carbon bed stack during bed regeneration. Typical
levels of contamination in this recycled stream were low (<50
ppmV) although sampling activities indicated one high level
(approximately 500 ppmV). This high value was most likely
obtained just prior to breakthrough of the activated carbon bed
before regeneration. The return airstream from the active
carbon bed is recycled back to the ground through the augers.
Any contaminants in this airstream are reinjected into the soil
and are again subjected to the treatment process.
Certain chemical species are more difficult to remove
from the soil by in situ steam/hot-air stripping than others.
High boiling point VOCs require longer block treatment times
than compounds with lower boiling points. This is expected
based on the simple relation between boiling point and vola-
tilization. Baseline Testing (see Appendix D) indicated that
those compounds with boiling points below 175°F (80°C)
were frequently removed to levels which could not be detected.
When they were detected, these low boiling compounds ex-
hibited significant reductions in concentrations. Those with
boiling points above 175°F also exhibited significant reductions
in concentration, but the concentrations were less frequently
reduced to below the detection limit Testing operations have
indicated that tetrachloroethene is a particularly difficult
compound to remove. The difficulties encountered in remov-
ing tetrachloroethene can be explained by its known high
stability and resistance to hydrolysis. Further information may
be found in TTUSA's Baseline Testing; Process Improvement
and Soil Vapor Emissions Tests; and Mixing, Treatment, and
Downward Migration Tests (Appendix D). Xylenes are typi-
cally difficult compounds to remove because of their high
molecular weight. However, bench-scale testing of steam
-------
stripping processes have shown that xylenes can be removed
by this type of process [1].
Using data generated during the Demonstration Test,
mass balances were attempted on both the condensed organics
and the water. The organic mass balance could not be per-
formed. When the pre- and post-treatment soil contamination
levels were compared to the amount of organics collected in
the condensed organics tank, it was found that a large dis-
crepancy occurred. This discrepancy could easily occur because
of the highly heterogeneous nature of the soil prior to, and
even after, treatment. The wide standard deviation around the
mean of the pre-treatment composite cores indicates the dif-
ficulty in accurately characterizing the heterogeneous blocks
and accounts for the poor closure obtained. The discrete core
samples and the dye samples also show inhomogeneity in the
post-treatment soil blocks. Holdup of contaminants in the
process system before the Demonstration Test could also
introduce error into the balance. The water balance achieved a
more satisfactory result with approximately 50% of the water
being accounted for in the soil or the treatment process. The
high standard deviation in the pre- and post-treatment percent
moisture analysis in the soil samples and suspected inaccura-
cies in the ability to measure totalized volumes in all of the
water streams account for complete lack of closure in the
balance.
Although in situ treatments are not subject to land ban
regulations, toxic characteristic leaching procedure (TCLP)
was performed on soil samples before and after treatment.
These analyses indicated that the treatment process has little
effect on the teachability of the soil. However, they also
showed the heterogeneous nature of the treatment blocks
before and after treatment The leachability of the contaminants
in all post-treatment soil samples were below the regulatory
limits as listed in the Federal Register [2].
Operational Test Results
Semivolatile compounds that were unaccounted for fol-
lowing treatment prompted investigation into the potential of
the process to induce downward migration of contaminants. A
dye study which utilized fluorescein dye packets to trace the
behavior of the contaminants during treatment was conducted
as part of the Demonstration Test Four blocks in the 12-block
test area were spiked with fluorescein dye before treatment
began in the test area. Following treatment by the TTUSA
process, these blocks were sampled within and below the
treatment area and analyzed for the presence of the dye. A
similar study was conducted by TTUSA in their Mixing,
Treatment, and Downward Migration Tests (see Appendix
D). Both tests indicated that downward migration of organic
contaminants to below the zone of treatment did not appear to
be a result of treatment. Dye was found to be present in
samples taken below the treatment depth but at concentrations
significantly lower than within the treatment area. Occasion-
ally, high levels of fluorescein were found at a particular
depth (sample interface) below the zone of treatment,; In these
instances, it was assumed the dye at this location could be due
to cross-contamination of samples. Because the fluorescein
dye is more soluble than the VOCs or S VCs found on-site, it is
reasonable to assume that any downward migration of the
VOCs and SVCs is less than that displayed by the dye.
Fugitive emissions from both the soil and the process
itself were sampled and monitored during and after treatment.
Fugitive emissions from the soil were low, on the order of
approximately 21 grams for total emissions due to treatment
of a single block (based on data gathered from the 12-block
test area). Some heating of the soil surrounding a block
undergoing treatment occurs during its treatment The effect
of this heating on fugitive emissions was evaluated during the
Demonstration Test by placing flux chambers on four blocks
surrounding the treated block (see Figure 1) and on the treated
block itself after treatment was completed and the shroud had
been removed. During treatment of the Demonstration Test
block, Location 1 had the lowest emission rate of the five
locations sampled. Location 1 lies in a row which had already
undergone treatment The majority of the contamination had
been removed by treatment, and sufficient time had elapsed to
allow the emission rate to reach background levels. Treatment
in Location 1 was also responsible for driving out a portion of
the contamination from Location 2. Emission rates from Lo-
cation 2 (untreated) were therefore higher than those from
Location 1 (treated) but lower than those from Locations 4
and 5 (also untreated). Location 4 demonstrated the highest
emission rate for samples taken during treatment of the high-
lighted block in the configuration shown in Figure 1. This
result is reasonable since Location 4 lies in an untreated area
adjacent to the block currently undergoing treatment In ad-
dition, it is not adjacent to any other blocks that have already
been treated, eliminating the possibility for any contamination
to be driven off by treatment of these blocks.
Although the emission rate from Location 4 was the
highest among those sampled in the configuration shown in
Figure 1, it was substantially lower than that observed from
the previously treated adjacent block immediately following
its treatment. The emissions from this block were high imme-
diately upon completion of its treatment, but decreased rapidly
with time. The emissions were expected to be relatively high
since the block, still hot from its treatment, was no longer
covered by the shroud and off-gases were allowed to escape
from the soil into the atmosphere. Operational testing by
TTUSA during their Process Improvement and Soil Vapor
Emissions Tests (see Appendix D) demonstrated that using a
2-inch layer of clean soil to cover treated treatment blocks
reduces fugitive emissions by over 50%. This procedure has
since been put into practice and the primary source of fugitive
emissions has been reduced. Since emission rates are so low,
testing has not been performed to evaluate the effect of
covering the treated blocks with a deeper layer of clean soil
(greater man 2 inches), but it is anticipated that use of a deeper
layer of clean soil would result in greater reductions in the
emission rates. Overall, the fugitive emissions generated from
treatment of a block are considered to be insignificant
Potential process fugitive emissions were also monitored
during operation of the in situ steam/hot-air stripper to ensure
that contaminants were not leaking into the atmosphere. Po-
tential gas leakage from the shroud, exhaust from operation
and steam regeneration of the gas-phase carbon beds, and
cooling tower evaporative vapors were also periodically
monitored with an OVA instrument.
.Apart from emissions produced by regeneration of the
carbon beds, process emissions during the Demonstration
-------
Direction a/Treatment
imiiniii
iiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiii
(Block Under Treatment)
niiiiiikiiiiiiiiiiiiiiiiiiiiiiiyiiiiiiiiiiiiiiiiiiiiiiiiiii
IIIIIIIIIIIIIIIIIIIIIIIIHIIIIIIIIIIIIIIIIIIIIIIIIIII
(Untreated)
iimiiiiiiiimmiiiiiiiimmiiiiiiiiiiimiiiiifmiiiii
'•"I
Treated Soil Block
Untreated Soil Block
ilJ
j ! Surface Soil Gas Flux Chamber In Place During Treatment
i I
Surface Soil Gas Flux Chamber Placed After Treatment
Figure 1.
iiiiim Test Area Soil Blocks (12 Total)
Sampling locations for fugitive emissions.
Test were low. Research performed since the completion of
the Demonstration Test revealed that the path between the two
carbon beds was inappropriately closed off by flapper valves.
This situation has since been rectified by replacing the flapper
valves with butterfly valves equipped with viton seats.
Based on information provided by TTUSA, soil type has
an effect on the rate of treatment. Clay soils are generally the
most difficult to treat Organic compounds have a greater
tendency to bind to clay soils due to the structure and organic
content of the clay soils. Volatilization of organic compounds
in the soil is therefore more difficult to achieve. Clay soils
also offer slightly more resistance to penetration and mixing
by the augers than other soil types, contributing somewhat to
their treatment demand. Sandy soils demonstrate much shorter
treatment times than clay soils.
An on-line treatment time factor of 71% was achieved
during the Demonstration Test. This was determined by com-
paring the operation time to the time spent on-site each
workday. The operation time excludes downtime for mainte-
nance (as this is performed during separate shift hours) but
includes time required for relocation of the shroud since this is
part of normal operating procedures. Downtime experienced
in a normal workday is attributed to operational maintenance
to remedy clogged nozzles, freezing problems in the refrig-
eration system, loss of vacuum beneath the shroud, etc. TTUSA
claims an on-line factor of 70% to 75% can be attained during
normal operation of the in situ steam/hot-air stripper.
The chemical profile of the contaminants in the soil
affects the treatment rate. A site contaminated with very
volatile compounds, such as gasoline, can be treated rapidly.
High concentrations of volatile contaminants or the presence
of semivolatile contaminants would require longer treatment
times for each block. As mentioned previously, certain chemical
species can also demand more remedial attention.
The mixing action of the augers does not produce a
homogeneous area of treatment. The augers and cutter bits
were designed to loosen and homogenize the soil in their
vicinity while injecting steam and hot air to volatilize con-
taminants. Based on test results, homogeneous mixing is not
an apparent consequence of auger action. Residual contami-
nation in the treated blocks was anticipated to be fairly
homogeneous. Instead, treated soil blocks are extremely het-
erogeneous in nature as indicated by chemical analyses for
volatile and semivolatile contaminants and dye test data.
Wide vertical and lateral variation is exhibited among post-
treatment samples obtained from the same block.
The technology is a mobile process transportable from
site to site. The unit can be conveyed on five tractor/trailer
10
-------
rigs, one of which is designated an oversize/overweight load.
Assembly of the steam/hot-air stripper can be performed in
one week. Disassembly of the equipment also requires one
week.
The extent of post-treatment requirements is dependent
on the future use of the site. The site is left clear and free of
subsurface objects. This may or may not be beneficial since
all sewer piping and underground wiring is removed prior to
treatment and therefore these utilities must be replaced. Treat-
ment of the soil utilizing this stripping process also leaves the
soil disturbed so that it is no longer compacted or level. The
treated areas may require grading and recompaction based on
the anticipated service of the site.
Physical Test Results
Results from the Demonstration Test do not indicate a
significant statistical change in the moisture content of indi-
vidual soil blocks as a result of treatment Evaluation of the
average moisture content for the entire 12-block test area did,
however, show a slight decrease in the moisture content as a
result of treatment with average pre-treatment levels of ap-
proximately 30% and average post-treatment levels of ap-
proximately 28%. Baseline Testing (see Appendix D) in three
areas also indicated a slight decrease in average moisture
content from pre-to post-treatment. The data are not statistically
conclusive because of the high standard deviation.
The bulk density of individual blocks appears to increase
slightly as a result of treatment based on Demonstration Test
and Baseline Testing results. The average bulk density of all
blocks in the 12-block test area of the Demonstration Test
increased from 1.52 g/cc to 1.55 g/cc following treatment.
Again, the high standard deviation of the data leads to incon-
clusive results.
The specific gravity of the soil increased by an average of
6.5% in the 12-block test area evaluated during the Demon-
stration Test. Analysis of this property provides a measure of
the void space in the soil and indicates that the porosity
decreased.
Ranges of Site Characteristics Suitable for the
Technology
Site Selection
The selection of sites with potential for treatment by the
in situ steam/hot-air stripping technology is based on the
following criteria:
• Only soils contaminated with volatile organics are poten-
tially remediable by this particular technology.
• The site ideally requires sufficient land area around the
identified treatment area to provide a buffer zone to
maneuver the in situ steam/hot-air stripping unit. Suffi-
cient uncontaminated space adjacent to the treatment area
is also required for placement of support equipment and
trailers.
• Access roads must be available and must be able to
convey the trailer transporting the control room and cat-
erpillar, which is classified as an overwidth load and
weighs approximately 88,000 pounds.
• A minimum treatment area of approximately 0.5 acres
(20,000 square feet) is necessary for economical utiliza-
tion of the in situ treatment technology.
Surface, Subsurface, andClearance Characteristics
The rig can apply a pressure of up to 25 pounds per
square inch (psi) on the underlying soil when the shroud is
lifted. Therefore, the area to be treated by the in situ stripper
must be capable of supporting the treatment rig so that it does
not sink or tip. The soil must be penetrable by the augers and
free of underground piping, wiring, tanks, or drums. Materials
of this type must be relocated before treatment can commence.
Surface and subsurface obstacles greater than 12 inches in
diameter including rocks, concrete, and trash metal must be
removed to avoid damage to the stripping equipment. Incom-
plete treatment could result if these materials are not removed.
Sites with large known or suspected amounts of such material
may be unsuitable for in situ treatment due to the effort re-
quired for removal.
Power and telephone b'nes or other overhead obstacles
must be removed or rerouted to avoid conflict with the 30-foot
treatment tower.
Topographical Characteristics
The ground where treatment will be performed must be
flat and level. For the current in situ steam/hot-air stripper
model the surface must be gradeable to less than 1%.
Site Area Requirements
The site requires sufficient space for a bermed equipment
decontamination area, a small personnel decontamination area,
two or more liquid storage tanks, and office trailers. The
treatment area should meet the minimum area requirements
for economical use of the in situ steam/hot-air stripping unit
The shape of the site is also important; rectangular areas
are most efficient. A site which is broken up into oddly-
shaped or narrow areas by buildings or natural formations
may provide an extra challenge to the maneuverability of the
equipment require additional treatment time per soil treatment
block, and result in less efficient block treatment patterns.
Climate Characteristics
Since the steam/hot-air stripper operates on the soil in situ,
any climatic conditions that affect properties of the soil ad-
versely with respect to the treatment process may render the
site inappropriate for treatment by this process. For example,
an extremely cold climate, where the soil becomes frozen
solid, would cause difficulty with soil penetration and would
require large amounts of energy to heat the soil to the treatment
temperature; the same is true of snow covered ground.
Cold temperatures would increase heat loss from the
equipment, requiring additional heat input to the steam and
hot air, while aiding the efficiency of the condensing coolers.
Although the equipment's operational abilities in very cold
temperatures have not been fully determined, the most likely
limiting factor is the diesel fuel lines, which would begin to
experience flow problems at ambient temperatures less than
20°F. Freezing of cooling water lines may also limit the
11
-------
operating temperature for the stripper. Thorough insulation of
all lines may allow for operation in even colder weather.
Hot weather (high ambient temperature) decreases the
cooling capacity of the evaporative cooling tower. This, in
turn, reduces the effectiveness of the water coolers in con-
densing organics in the treatment train. The upper temperature
limit for effective operation is an ambient temperature of
approximately 100°F. Problems caused by hot weather may
be alleviated by operating the in situ steam/hot-air stripper at
night, if ambient nighttime temperatures allow. In general,
moderate temperatures are preferred for optimal operation.
Saturated surface soils, especially those with high clay
content, may impede the movement of heavy equipment and
may noi be capable of supporting the unit's weight. Therefore,
although heavy annual rainfall does not preclude the use of the
in situ steam/hot-air stripping technology, scheduling opera-
tions during the drier seasons may result in more efficient and
timely treatment.
Severe storms may result in hazardous operating condi-
tions, since the equipment is fully exposed to the weather. The
process tower, often standing alone or standing taller than
surrounding structures, provides a ready pathway for lightning.
Geological Characteristics
Major geological constraints that can render a site unsuit-
able for IB situ steam/hot-air treatment include landslide po-
tential, volcanic activity, and fragile geological formations
that may be disturbed by heavy loads or vibrational stress.
The entire treatment area must be composed exclusively
of soil, at least to the proposed treatment depth. Unremovable
rock formations in the treatment area would preclude use of
the i« situ stripper. Although the IB situ steam/hot-air stripper
is capable of treating most kinds of soil, the soil type impacts
treatment process time and effectiveness. Soil type also dictates
acceptable climate characteristics by its response to rainfall
and other climatic conditions. Wet sandy soils tend to have a
greater load capacity than other wet soils. Soils with more
clay and silt tend to become malleable and unstable when wet,
potentially causing problems with the support and mobility of
the equipment Dry, clay soil can form hard clumps which
may not break up during the treatment process, thus reducing
the effectiveness of treatment. Also, data from the Baseline
Calibration (see Appendix D) suggests that organic contami-
nants may bind more strongly with clay soils than to soils with
larger particles.
The presence of a shallow water table does not preclude
treatment with the IB situ steam/hot-air stripper. The unit can
easily and efficiently treat the soil and water in and below the
saturation zone as a normal part of site treatment. This result
was not identified during the Demonstration Tests, but has
been demonstrated by TTUSA in operations following the
completion of the demonstration.
Utility Requirements
The IB situ steam/hot-air stripping process requires water
supply of at least 8 to 10 gallons per minute (gpm) at 30
pounds per square inch gauge (psig). Power for the in situ
steam/hot-air stripper is provided by on-board diesel genera-
tors.
Environmental Regulations and Comparison
with TTUSA Stripping Technology
Performance
Operation of the TTUSA in situ steam/hot-air stripping
technology for treatment of contaminated soil will require
compliance with certain Federal, State, and local regulatory
standards and guidelines. This technology may be used at
Federal Superfund National Priorities List (NPL) sites and
other sites. Superfund site regulatory requirements applicable
to the use of this technology are discussed below under the
Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA). Other Federal, and State and local
environmental regulations are subsequently discussed in more
detail as they apply to the performance, emissions and residuals
evaluated from measurements taken during the Demonstra-
tion Test.
The Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA)
The Comprehensive Environmental Response, Compen-
sation, and Liability Act (CERCLA) of 1980 as amended by
the Superfund Amendments and Reauthorization Act (SARA)
of 1986 provides for Federal funding to respond to releases of
hazardous substances to air, water, and land. Section 121 of
SARA, entitled Cleanup Standards, states a strong statutory
preference for remedies that are highly reliable and provide
long-term protection. It strongly recommends that remedial
actions use on-site treatment that "...permanently and signifi-
cantly reduces the volume, toxicity, or mobility of hazardous
substances." In addition, general factors which must be ad-
dressed by CERCLA remedial actions are:
• long-term effectiveness and permanence;
• short-term effectiveness;
• implementability; and
• cost.
The TTUSA in situ steam/hot-air stripping technology has
been shown to remove an average of approximately 85% of
VOCs from contaminated soil at the demonstration site. In
this respect, the technology "permanently and significantly"
reduces the volume, toxicity, and potential mobility of the
contaminants in the soil.
The use of this technology for site treatment results in a
certain degree of long-term effectiveness and permanence
because hazardous wastes are actually removed from the soil
during treatment. Over the short term the potential for human
exposure to contaminated soil from excavation or contact with
surface soil is immediately and significantly reduced after
treating the site. Exposure due to excavation is minimal since
this is an in situ process. Fugitive air emissions from the soil
and from the process during operation of the stripping tech-
nology have been determined to be low. These results are
further discussed below under "State and Local Regulations."
In addition to the above general requirements, Section
121 of CERCLA requires that Superfund treatment actions
must meet or exceed any "applicable or relevant and appro-
priate" (ARAR) standard, requirement, criteria, or limitation
12
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under any Federal law or State environmental statute. Local
standards may also be relevant and appropriate. These criteria,
as related to use of the TTUSA stripping technology, are
discussed below.
Federal Regulations
Resource Conservation and Recovery Act (RCRA)
The Resource Conservation and Recovery Act (RCRA) is
the primary Federal legislation governing hazardous waste
activities. Subtitle "C" of RCRA contains requirements for
generation, transport, treatment, storage, and disposal of haz-
ardous waste, most of which are also applicable to CERCLA
activities.
The primary hazardous waste generated by the TTUSA
process is the condensed organics removed from the contami-
nated soil. Due to generation of this hazardous waste, the site
responsible party must obtain a EPA generator identification
number and comply with accumulation and storage require-
ments for generators under Tide 40, Code of Federal Regula-
tions (CFR), Part 262 (July 1, 1988) or have a Part B,
Treatment, Storage, and Disposal (TSD) permit or interim
status. (Compliance with RCRA TSD requirements is re-
quired for CERCLA sites.) A hazardous waste manifest must
accompany off-site shipment of waste. Transport must comply
with Federal Department of Transportation (DOT) hazardous
waste transportation regulations. The receiving TSD facility
must be permitted and in compliance with RCRA standards.
The RCRA land disposal restrictions (40 CFR Part 268)
require that certain hazardous wastes receive treatment after
removal from a contaminated site and prior to land disposal,
unless a variance is granted. Since the condensed organics are
a liquid hazardous waste, treatment will be required prior to
land disposal. Technology or treatment standards have been
established for many liquid hazardous wastes; those appli-
cable to use of the TTUSA process at a given site will be
determined by the type of waste generated. Incineration of this
liquid hazardous waste may be the Best Demonstrated Avail-
able Treatment (BOAT) prior to disposal (of any residue) in a
certified landfill.
Another disposal option for the waste which is classified
as recycling under 40 CFR Parts 261 and 266, may be burning
the waste in a boiler or an industrial furnace such as a cement
kiln. However, a waste must meet BTU requirements of 5,000
to 8,000 BTU to be treated in this manner [3]. State regulations
may further restrict the wastes and appropriate treatment
techniques.
Soil treatment by the stripping technology is an in situ
process and therefore the soil itself does not require land
disposal and compliance with the associated land disposal
restrictions.
Clean Water Act
The Clean Water Act (CWA) regulates direct discharges
to surface water through the National Pollutant Discharge
Elimination System (NPDES) regulations. These regulations
require point-source discharges of wastewater to meet estab-
lished water quality standards. The TTUSA process has a
cooling water blowdown discharge and a boiler blowdown
discharge. These wastewaters are anticipated to be discharged
to the sanitary sewer, requiring a discharge permit or at least
concurrence from state and local regulatory authorities that
the wastewater is in compliance with discharge standards. The
cooling water blowdown may contain residual VOCs from the
water purification process. Although not classified as a haz-
ardous waste, this wastewater may require treatment for re-
moval of VOCs (specifically, chlorinated organics) prior to
sewer discharge.
Safe Drinking Water Act
The Safe Drinking Water Act (SDWA) establishes pri-
mary and secondary national drinking water standards. These
standards consist of Maximum Contaminant Levels (MCLs),
MCL Goals (MCLGs), and aesthetic standards. MCLs are
relevant and appropriate as in situ cleanup standards where
either surface or groundwater is or may be used for drinking
water. Although the TTUSA technology is designed and
intended for treatment of contaminated soils, residual soil
contamination after treatment could potentially impact
groundwater quality through leaching. Therefore, the use of
MCLs for VOCs of concern may be relevant and appropriate
at sites overlying a drinkable groundwater aquifer.
Clean Air Act
The Clean Air Act (CAA) establishes primary and sec-
ondary ambient air quality standards for protection of public
health, and emission limitations for certain hazardous air
pollutants, including benzene. The pollutants listed, in the
ambient air quality standards are generally not applicable to
operation of the TTUSA in situ steam/hot-air -stripping tech-
nology, except perhaps for diesel exhaust, which may be more
stringently regulated by state or local standards. The emission
standards for hazardous air pollutants promulgated thus far
have been rather narrowly defined; they apply only to new and
modified stationary sources, and will probably not be relevant
to TTUSA technology treatment activities.
The Federal environmental regulations discussed above
are the most significant for operation of the TTUSA stripping
technology. However, other statutes may have ARAR re-
quirements. Some of these ARARs may be location- and
action-specific.
State and Local Regulations
Compliance with ARARs may require meeting State
standards that are more stringent than Federal standards or
may be the controlling standards in the case of non-CERCLA
treatment activities. For use of the TTUSA stripping technol-
ogy, soil cleanup standards will be the most significant of
these standards. These standards may be based on the results
of a waste site risk assessment. Results from the Demonstra-
tion Test showed that the overall average post-treatment soil
VOC contamination was 71 ppm with a standard deviation of
80 ppm. The 95% confidence interval range for the true mean
of the post-treatment cores was 45 to 98 ppm. Mean residual
soil VOC levels ranged from 12 to 196 ppm. Results of
Baseline Testing by TTUSA in September 1988 (see Appen-
dix D, "Case Studies") showed that mean residual VOC levels
ranged from 12 to 140 ppm.
13
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Air emissions may also be regulated by the State and/or
local air quality district. These may include exhaust emissions
from the stripping technology's diesel engines, emissions
from contaminated soil excavation activities, and releases of
reactive organic gases, such as some of the volatile compounds
treated by the TTUSA technology. Based on the Demonstra-
tion Test results and assuming that six heavily contaminated
soil blocks are treated each day, the total emissions from the
blocks would be less than 140 g/day (about 0.3 Ib/day). The
maximum limitation by the SCAQMD for release of reactive
organic gases is 34 kg/day (75 Ib/day).
Water quality may also be regulated by State standards.
The State water authority could specify standards for ground-
water beneath the site or for potentially contaminated surface
water runoff. The TTUSA process has successfully treated
contaminated soil in and below the water table. Groundwater
quality may potentially be directly affected by treatment into
and below the water table. Preliminary data indicates that the
groundwater itself is actually treated.
14
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Section 4
Economic Analysis
Introduction
The primary purpose of this economic analysis is to
estimate costs (not including profits) for a commercial-size
treatment utilizing the transportable TTUS A in situ steam/hot-
air stripping system. The costs associated with this technology
are defined by 12 cost categories that reflect typical cleanup
activities encountered on Superfund sites. Each of these cleanup
activities is defined and discussed, forming the basis for the
estimated cost analysis presented in Table 2. The costs pre-
sented are based on treatment of 8,925 yd3 of contaminated soil,
the amount of soil to be treated at the Demonstration Test site.
The actual Demonstration Test treated approximately 65
yd3 of contaminated soil at the site. The costs presented in
Table 2 are based on anticipated on-line operations of the unit
since periodic shutdowns are required in order to respond to
maintenance or operational problems. Costs are given for
70%, 80%, and 90% on-line conditions. Costs which are
assumed to be the obligation of the responsible party or site
owner have been omitted from this cost estimate and are
indicated by a line (—) on Table 2. Categories with no costs
associated with this technology are indicated by a zero (0) on
Table 2.
Important assumptions regarding operating conditions
and task responsibilities that could significantly affect the cost
estimate results are presented below:
• The cost estimates presented in this analysis are represen-
tative of charges typically assessed to the client by the
vendor and do not include profit Costs such as preliminary
site preparation, permits and regulatory requirements,
initiation of monitoring programs, waste disposal, sam-
pling and analyses, and site cleanup and restoration are
considered to be the responsible party's (or site owner's)
obligation and are not included in the estimate presented.
Whenever possible, applicable information is provided
on these topics so that the reader may perform his own
calculations to obtain relevant economic data.
• The treatment area is divided into 1,643 blocks each
measuring 7 ft-4 in by 4 ft and treated to a depth of 5 ft
The total volume of each block is 5.43 yd3, and the total
volume treated is 8,925 yd3.
• For hypothetical 100% on-line conditions, the treatment
rate is assumed to be 3 cubic yards per hour. Operations
are assumed to be 16 hours a day, five days a week with
the exception of site preparation operations that are as-
sumed to be 8 hours a day, five days a week.
Operations for a typical 16-hr day require: one supervi-
sor, two health and safety engineers, four operators, and
five mechanics.
• Site preparation estimates do not include administrative
costs; these administrative costs are included in estimates
for assembly, treatment, and disassembly.
• Equipment capital costs are not used directly and are
limited to the cost of the in situ steam/hot-air stripper
($1,981,000). Percentages of this $1,981,000 are used for
estimating purposes.
• Depreciation and other costs that are estimated as per-
centages of equipment capital costs on an annual basis
have been prorated. (The costs for depreciation and insur-
ance and taxes accrue during assembly, treatment, and
disassembly; scheduled maintenance costs accrue during
treatment only; contingency costs are assessed for the
entire length of the project including site preparation,
assembly, treatment, and disassembly.)
• A 65% utilization factor is incorporated into depreciation
costs to account for depreciation that occurs during main-
tenance, marketing, and regulatory delays which take
place while the equipment is not on-site.
• Wastewater is assumed to meet local water quality stan-
dards.
Many actual or potential costs that exist were not included
as part of this estimate. They were omitted because site-
specific engineering designs, that are beyond the scope of this
SITE project, would be required. Certain functions were
assumed to be the obligation of the responsible party or site
owner and were not included in the estimates.
Results of Economic Analysis
Table 2 presents the economic analysis for operating
factors ranging from 70% and 266 treatment days (399 days
on-site) to 90% and 207 treatment days (315 days on-site).
Data gathered during the Demonstration Test indicates that a
70% on-line factor most closely represents the operating
conditions during this period of time. The results of the
analysis show a cost per cubic yard range from $252 to $317.
These costs are considered to be order-of-magnitude esti-
15
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Table 2. Estimated Costs in $/Cubic Yard*1'
On-line Factor
70%
Site Preparation Costs
Site Design and Layout* —
Survey and Site Investigations' —
Legal Searches' —
Access Rights and Roads0 —
Preparations for Support Facilities* —
Utility Connections' —
Auxiliary Buildings' —
Technology-Specific Requirements 367
Total Site Preparation Costs 3.67
Permitting and Regulatory Costs
Permits' —
System Monitoring Requirements' —
Development of Monitoring and Analytical
Protocols' _=—
Total Permitting and Regulatory Costs —
Equipment Costs
Major Equipment
- Detoxifier ($1,981.000^
Support Equipment' 0
Equipment Rental 14,24
Total Equipment Costs 1424
Startup and Fixed Costs
Mobilization
- Transportation 253
-Assembly 3.21
Sliakedown 1-71
Testing 1.14
Working capital 2.11
Depreciation (10-year schedule; 65%
utilizationfactor; prorated for assembly,
treatment, and disassembly time) 34.97
Insurance and Taxes
(10% of Equipment Capital Costs;
prorated for assembly,
treatment, and disassembly time) 2355
Initiation of Monitoring Programs' —
Contingency
(10% of Equipment Capital Costs;
prorated for sitepreparation, assembly,
treatment, and disassembly time) 24.40
Total Startup and Fixed Costs 93.62
Labor Costs
Supervisory and Administrative Staff 14.00
Professional and Technical Staff 70.03
Maintenance Staff 58.11
Clerical Support* _Q
Total Labor Costs 151.37
3.67
3.67
ML
3.67
0
12*
12.23
253
3.21
1.71
1.14
2.11
30.76
20.71
21.57
83.74
12.25
61.28
50.85
0
132.45
0
11.19
11.19
253
3.21
1.71
1.14
2.11
27.48
1850
19.36
76.05
117.73
(Continued)
16
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Table 2. Continued
On-line Factor
70%
80%
90%
Supplies Costs
Raw Materials
- Chemicals, Health & Safety Gear,
and Office/General Supplies 10.70
Total Supplies Cost 10.70
Consumables Costs
Utilities
-Fuel
- Water
- Electricity'f
Byproducts and Post-treatment
Total Consumables Cost
Effluent Treatment and Disposal Costs
On-Site Facility Costs' —
Off-Site Facility Costs
- Wastewater Disposal' 0
- Monitoring Activities' 0
Total Effluent Treatment and Disposal Costs~0
Residuals and Waste Shipping, Handling, and
Transport Costs
Preparation*
Waste Disposal*
Total Residuals and Waste Shipping,
Handling, and Transport Costs —
Analytical Costs
Operations' 0
Environmental Monitoring* —
Total Analytical Costs 0
Facility Modification* Repair, and Replacement Costs
Design Adjustments' 0
Facility Modifications' 0
Scheduled Maintenance (materials)
(10% of Equipment Capital Costs,
60% materials factor, prorated for
treatment time) 13.62
Equipment Replacement? 0
Total Facility Modification, Repair,
and Replacement Costs 13.62
9.41
9.41
0
0_
0
0
0
0
0
11.91
0
11.91
Ml
8.41
20.75
0
0
0
0
10.59
(Continued)
17
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Table 2. Continued
On-line Factor
70%
90%
Site Demobilization Costs
Shutdown
-Disassembly
Site Cleanup and Restoration'
Permanent Storage'
Total Site Demobilization Costs
Total Cost
3.21
0
321
317.06
3.21
0
3.21
251.58
' Tills cost analysis does not include profits of the contractors involved.
*The American Association of Cost Engineers defines three 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%.
c These costs are assumed to be the obligation of the responsible party (or site owner) and are not included in the cost
estimate.
''Tltis cost is not used directly but is used for estimating other costs (i.e., depreciation, working capital, insurance and taxes,
scheduled maintenance, and contingency).
' There are no charges associated with these potential cost factors for this technology.
fFor this estimate, it is assumed that electricity is supplied by on-board diesel generators, therefore some of the fuel is used
to generate electricity. If electricity is provided by the local utility company, fuel costs decrease and electricity costs
increase.
mates as defined by the American Association of Cost Engi-
neers with an expected accuracy within +50% and -30%;
however, because this is a new technology, the project con-
tingency is high. These cost values may be different than
those normally claimed by TTUSA (see Appendix A,
"Vendor's Claims").
Figure 2 presents a breakdown of the costs for each of the
twelve cost categories. The results show that, for a treatment
rate of 3 ydVhour, the technology is labor intensive with ap-
proximately 47% of the total cost attributed to labor. For
higher treatment rates, the technology becomes less labor
intensive. The number of employees required could be reduced
by working 8-hour days instead of 16-hour days; however,
this would increase the number of days required on-site, and
in turn increase the overall cost.
For a treatment rate of 3 yd3/hour, only 4% of the costs
associated with operating the TTUSA in situ steam/hot-air
stripper are independent costs. Independent costs are costs
that do not depend on site size, transportation distance, or on-
line efficiency for any particular treatment rate. This percentage
increases with increases in the treatment rate. Site preparation
costs are governed by the size of the site; transportation costs
vary slightly with the distance traveled to the site. The remain-
ing costs of operation can be reduced by increasing the on-line
operating factor and thus decreasing the time required on-site.
Site preparation costs are minimized when treating a site
with few surface and subsurface obstacles. This reduces both
the time requirements for initial site preparation and the time
requirements for interruption of treatment when subsurface
obstacles are encountered during treatment.
The cost of power can be reduced by approximately 50%
if power is supplied directly from the grid system (via the
local electric company) rather than from an on-board genera-
tor. Presently, the in situ steam/hot-air stripper does not op-
erate in this fashion, but may be modified to utilize a
transformer for this function. The savings realized by this
modification is not substantial, since current power costs
represent only about 1% of the total cost per cubic yard.
The results presented above and in Table 2 represent
conditions similar to those observed during the Demonstration
Test. The demonstration site consisted of clayey soils heavily
contaminated with both volatile and semivolatile organic
compounds; approximately 3 yd3 were treated per hour with
an on-line factor of 70%. Other sites may have more sandy
soils, lower levels of contamination, or solely volatile con-
tamination. All of these conditions would significantly in-
crease the number of blocks which could be treated per day.
Therefore, results have also been calculated for treatment
rates of 6, 10 and 20 yd3/hour. A summary of these results,
along with the results for a treatment rate of 3 ydYhour, is
presented in Table 3.
Independent costs range from approximately 4% to 18%
of the total costs while labor costs range from approximately
48% to 33% of the total costs for treatment rates of 3, 6, 10
and 20 yd3/hour, respectively. For operation at 3 yd3/hour,
independent costs are low and the cost of the technology is
labor intensive. Using 3 yd3/hour at 70% on-line as a refer-
ence, treatment rates effect the total costs as follows: doubling
the number of cubic yards treated per hour (to 6 ydVhour)
decreases the total costs by approximately 47%; increasing
the number of cubic yards treated per hour by a factor 6.67 (to
18
-------
Cost in $!Cubic Yard
$300 —
$250 —
$200
$150 —
$100 —
$50 —
$0
1.3%
1.5%
3.3%
Demobilization
Site Preparation
Supplies
Facility Modification
Equipment
Consumables
Startup and Fixed
Labor
70%
80%
Percent On-Line
90%
Figure 2. Summary of cost breakdown for 12 cost categories.
19
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20 yd'/hour) decreases the total cost per cubic yard by ap-
proximately 79%.
Basis of Economic Analysis
The cost analysis was prepared by breaking down the
overall cost into 12 categories. The categories, some of which
do not have costs associated with them for this particular
technology, are:
Site preparation costs.
Permitting and regulatory costs.
Equipment costs.
Startup and fixed costs.
Labor costs.
Supplies costs.
Consumables costs.
Effluent treatment and disposal costs.
Residuals and waste shipping, handling, and transport
costs.
Analytical costs.
Facility modification, repair, and replacement costs.
Site demobilization costs.
The 12 cost factors examined as they apply to the TTUS A
in situ steam/hot-air stripping process, along with the assump-
tions employed, are described in detail below.
Site Preparation Costs
It is assumed that preliminary site preparation will be
performed by the responsible party (or site owner). The amount
of preliminary site preparation will depend on the site. Site
preparation responsibilities include site design and layout,
surveys and site logistics, legal searches, access rights and
roads, preparations for support facilities, decontamination
facilities, utility connections, and auxiliary buildings. Since
these costs are site-specific, they are not included as part of
the site preparation costs in this cost estimate.
Additional site preparation requirements peculiar to in situ
steam/hot-air stripping are assumed to be performed by the
prime contractor (TTUSA). This site preparation, including
full removal of surface and subsurface objects (i.e., large
rocks, underground piping, etc.), grading, and leveling of the
ground to a maximum 1% grade, is required prior to the
commencement of treatment. Due to the in situ nature of this
treatment, and due to the potential treatment depths, it is
expected that a few subsurface objects will be discovered
during the course of treatment even though the majority of
them would have been removed during the site preparation.
When they are discovered, treatment will be interrupted and
these objects will be removed.
Cost estimates for site preparation are based on operated
heavy equipment rental costs; labor charges are included but
administrative costs have been omitted. It is assumed that
heavy equipment will be rented for approximately one (8-
hour) day for each 900 cubic yards undergoing surface and
initial subsurface preparation. The minimum equipment re-
quired includes: a bladed grader, two large tracked backhoes,
and a water truck. Bladed graders are available at an operated
rate of $89/houn tracked backhoes are available at $132/hour.
The rate for an operated water truck is $56/hour. Larger
equipment is also available if necessary. In addition to the
grader and tracked backhoes, use of a smaller backhoe will be
necessary to accommodate any removal of subsurface obstacles
encountered during treatment. The small backhoe will need to
be on-site for the duration of the treatment This cost has been
incorporated as part of "Equipment Costs".
Permitting and Regulatory Costs
Permitting and regulatory costs are generally the obliga-
tion of the responsible party (or site owner), not that of the
vendor. These costs may include actual permit costs, system
monitoring requirements, and the development of monitoring
and analytical protocols. Permitting and regulatory costs can
vary greatly because they are very site- and waste-specific. No
permitting costs are included in this analysis, however de-
pending on the treatment site, this may be a significant factor
since permitting activities can be very expensive and time-
consuming.
Equipment Costs
Equipment costs include major pieces of equipment (the
in situ steam/hot-air stripper), purchased support equipment
(none), and rental equipment. Support equipment refers to
pieces of purchased equipment necessary for operation. Items
such as a small backhoe, a 60-kW generator, a steam-cleaning
unit, and a truck may be purchased by TTUSA as support
equipment, however, to provide a conservative cost estimate,
all necessary support equipment is assumed to be rented.
The in situ steam/hot-air stripper used during the Demon-
stration Tests is the ATW Detoxifier, Model 1M, manufac-
tured by Calweld, Inc. This model is a prototype, assembled
from used parts. The cost of the prototype in situ steam/hot-air
stripper is $1,981,000. Costs for future models are anticipated
to be slightly higher if provided by the same manufacturer.
Various types of rental equipment will be necessary for
the duration of the project. Rental equipment includes: a small
backhoe, a generator, a steam-cleaning unit, a truck, and
facilities equipment. Weekly and monthly rates are available
in some cases and may represent significant savings, depend-
ing on the site and the type of equipment rented. Liquid
storage tanks are also required, but this cost is directly related
to waste disposal and is assumed to be the obligation of the
responsible party or site owner. Costs for storage tank rental
are reported under "Effluent Treatment and Disposal Costs"
and "Residuals and Waste Shipping, Handling and Transport
Costs".
The backhoe will need to be on-site for the duration of the
treatment; TTUSA personnel will operate and maintain the
backhoe. A small backhoe (without tracks) is available at a
rate of $2,580/month (bare rental). Backhoes are rented based
on normal use (8 hours/day). Rental fees are two times the
base rate for operation 16 hours/day.
The majority of the remaining rental charges have been
calculated on a monthly basis and the equipment is assumed
to be on-site for the duration of the project (including site
preparation, assembly, and disassembly time). A 60-kW gen-
erator will be required to supply power to the office facilities.
Generators are available at a rate of $ 1,000/month. Generators
are rented based on normal use (8 hours/day). Rental fees are
1.5 times the base rate for operation 16 hours/day. A steam-
20
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Table 3. Summary of Estimated Costs in $ICubic Yard for Various Treatment Rates and On-line Operating Factors*
3 Cubic Yards/Hour
70%
Site Preparation Costs 3.67
Permitting and
Regulatory Costs 0
Equipment Costs 1424
Startup and
Fixed Costs 93.62
Labor Costs 151.37
Supplies Costs 10.70
Consumables Costs 26.64
Effluent Treatment
andDisposal Costs 0
Residual and Waste
Shipping, Handling,
and Transport Costs 0
Analytical Costs 0
Facility Modification,
Repair and
Replacement Costs 13.62
Site Demobilization
Costs 321
Total Cost 317.06
80%
3.67
0
1253
83.74
132.45
9.41
2333
0
0
0
11.91
3.21
280.23
90%
3.67
0
11.19
76,05
117.73
8.41
20.75
0
0
0
1059
3.21
251.58
6 Cubic Yards/Hour
70%
3.67
0
737
54.05
75.68
554
1338
0
-
0
0
6.81
3.21
169.74
80%
3.67
0
651
49.14
6622
4.90
11.72
0
0
0
5.96
321
15132
90%
3.67
0
5.85
45.29
58.87
4.40
10.43
0
0
0
530
321
137.00
10 Cubic Yards/Hour
70%
3.67
0
4.62
38.26
45.41
3.48
7.99
0
0
0
4.08
3.21
110.73
80%
3.67
0
4.11
3530
39.73
3.09
7.08
0
0
0
357
3.21
99.76
90%
3.67
0
3.71
3238
35.22
2.79
630
0
0
0
3.18
321
91.16
20 Cubic Yards/Hour
70%
3.67
0
256
2639
22.71
193
4.09
0
0
0
2.04
3.21
66.61
80%
3.67
0
230
24.92
19.87
1.74
3.60
0
0
0
1.79
3.21
61.09
90%
3.67
0
2.10
23.77
17.66
159
321
0
0
0
159
3.21
56.79
" This cost analysis does not include profits of the contractors involved.
" The American Association of Cost Engineers defines three 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%.
-------
cleaning unit will need to be on-site for the duration of the
project to facilitale decontamination of the equipment. Steam-
cleaning units are available at a rate of $300/month. A truck
will be required to perform miscellaneous hauling activities.
Thicks are available at a daily rate of $55.
Facilities equipment is presumed to include two office
trailers ($3QO/month each), one lot of furniture ($200/month),
2 telephones ($100/month each), a computer ($300/month),
and a portable toilet ($70/month).
Startup and Fixed Costs
Mobilization includes both transportation and assembly.
The in situ steam/hot-air stripper is a mobile unit designed to
move from site to site, thus transportation costs are only
charged to the client for one direction of travel. For the
purpose of this estimate, transportation charges are included
with mobilization rather than demobilization.
Transportation costs are broken down into trucking costs
and costs associated with transporting the crew to the site.
Trucking charges include drivers and are based on a 40,000-
pound legal load. Five tractor/trailers are required. A 1,000-
mile basis is assumed at a rate of $1.50/mile/40,000-pound
load. One of the tractor/trailers requires a permit for oversize/
overweight load. A $4,000 permit fee is estimated for this
oversize/overweight load; permitting costs are assessed by
individual states and vary from state to state. The permitting
costs vary with the number of state lines crossed. Transporta-
tion costs for the 12-man crew are based on a $300 one-way
airfare per person. Some TTUSA personnel may choose to
drive their own vehicle to the site, but transporation costs,
accounting for mileage, would essentially be the same. TTUSA
may also elect to hire local personnel and transportation costs
would be reduced accordingly.
Assembly consists of unloading the equipment from the
trucks and trailers used for transportation, as well as actual
assembly. Unloading requires the use of an operated 30-ton
crane, available at $200/day, for one 16-hour day. Assembly
requires a full (12-man) crew working five 16-hour days (one
week). Labor costs include salary and living expenses. See
"Labor Costs" for information on how labor rates are obtained.
Each project requires one week for baseline calibration
prior to the commencement of treatment. Three 16-hour days
are allotted for shakedown purposes. This includes checking
out each of the systems individually prior to starting up the
entire in situ steam/hot-air stripper. The cost of shakedown is
limited to labor charges (including living expenses). Some
testing of the equipment must be performed. This testing
includes actual drilling time which allows soil characteristics
and temperatures achieved to be evaluated prior to treatment.
Testing is assumed to require approximately two 16-hour
days. Testing costs are based on labor charges (including
living expenses).
Working capital consists of the amount of money currently
invested in supplies, fuel, and spare parts kept on hand. The
working capital costs of supplies and fuel is based on main-
taining a one-month inventory of these items. Working capital
costs of spare parts is estimated as 0.5% of the total equipment
capital costs (1.981 M). The total working capital cost for this
project is $18,862.
The depreciation cost is based upon a 10-year life for the
equipment. The depreciation, based upon the writeoff of
$1,981,000 worth of new equipment and $198,100 (10%)
scrap value at the end of 10 years, is $178,290. A 65%
utilization factor has been incorporated to.account for depre-
ciation that occurs while the equipment is not on any worksite.
Maintenance, marketing, and regulatory delays are activities
which take place between projects and make up approximately
35% of the total availability of the equipment This deprecia-
tion cost has been prorated to the actual time spent on-site
(including assembly, treatment, and disassembly).
Insurance and taxes together are assumed for the purposes
of this estimate to be 10% of the equipment capital costs.
These costs have been prorated to the actual time spent on-site
(including assembly, treatment, and disassembly).
The cost of initiation of monitoring programs has not
been included in the scope of this estimate. The nature of in situ
steam/hot-air stripping does not require any monitoring beyond
standard operating procedures. Health and safety monitoring
costs have been incorporated into labor and supply costs.
Depending on the site, however, local authorities may impose
specific guidelines for monitoring programs. The stringency
and frequency of monitoring required may have significant
impact on the project costs.
A contingency cost of approximately 10% of the equip-
ment capital costs is allowed for any unforeseen or unpredict-
able cost conditions. The annual cost of contingency is prorated
to the actual time spent on-site (including site preparation,
assembly, treatment, and disassembly).
Labor Costs
Labor costs may be broken down into two major catego-
ries: living expenses and salaries. Living expenses for all
personnel (except clerical support who, if required, are assumed
to be local hires) consist of per diem and rental cars, both
estimated at 7 days/week for the duration of the treatment Per
diem is assumed to be $100/day/person, but may vary by
location. Three rental cars are assumed to be obtained at a rate
of $30/day. Should TTUSA elect to hire local personnel other
than clerical, living expenses would be reduced by a factor
proportional to the number of local hires.
Supervisory and administrative staff is limited to a single
site supervisor at a rate of $40/hour. Professional and techni-
cal staff includes two health and safety engineers ($50/hour)
and four operators ($30/hour). Maintenance personnel consists
of five mechanics at a rate of $30/hour. Clerical support is not
anticipated on a typical project. If necessary, secretaries are
available locally at an hourly rate of $15. This staffing is the
minimum required for double shift operation. Rates include
overhead and administrative costs; it is assumed that person-
nel will work an average of 40 hours/week.
Supplies Costs
Based on data from previous operations, over a period
which reflects operating conditions similar to those experi-
enced during the Demonstration Test, the costs for chemicals,
22
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health and safety gear, and office/general supplies are esti-
mated at $7,500 per month (16-hour days) for this technology.
Chemicals are limited to those necessary for treatment of the
boiler and cooling tower water. Health and safety gear is
assumed to include: hard hats, safety glasses, respirators and
cartridges, protective clothing, gloves, safety boots, and a
photoionization detector monitoring instrument.
Consumables Costs
Diesel fuel is assumed to be supplied by a local distribu-
tor at $1.03/gallon. Diesel fuel prices, however, fluctuate with
supply and demand and current market prices may impact this
cost
Nonpotable water is available from the City of Los Ange-
les. Since rates in California are governed by the time of year,
it has been assumed that the entire treatment occurs ;in the
summer months in California to provide a conservative esti-
mate. Billing is broken down into four categories, with the
total charges being the sum of the charges for these categories.
Rates are as follows:
1.5-inch line
Summer rate
Adjusted rate
Sewer charge
(commercial rate)
$8.40/month
$0.805/100 ft3
$0.381/100 ft3
$0.868/100 ft3
All electric power utilized by this technology is supplied
via a 250-kW generator located on the process train and thus
the cost of electricity is incorporated into the fuel charges.
Since the in situ steam/hot-air stripper may be modified to
utilize power supplied directly from the grid system (via the
local electric company), local electricity rates are also used to
estimate the cost of the power utilized by the system. This cost
information can be used to draw a comparison between the
expense of operation using a generator to provide electricity
versus operation using electricity from the grid system.
Electricity is available from the City of Los Angeles. For
small business customers whose power usage is up to 7,200
kWh/month, an Al rate applies. "Time-of-use" billing is
optional. This enables a customer to obtain lower rates for off-
peak usage. Again, billing is broken down into two categories,
and the total charge is the sum of the charges assessed in the
two categories.
Flat rate =
Service charge =
"Time-of-use" rate (optional)
Peak hours =
Off-peak hours =
Service charge =
$0.08999/kWh
$0.30/month
$0.13197/kWh
$0.06426/kWh
$0.30/month
Assuming operating hours are from 6:00 a.m. to 10:00
p.m., this results in 8 hours of peak hour operation and 8 hours
of off-peak hour operation. The "time-of-use" rate is not
beneficial in this case since the average "time-of-use" rate
($0.09812/kWh) is greater than the flat rate ($0.08999/kWh).
No byproducts are generated by this process. Further-
more, it is assumed that the process does not produce any
streams that require post-treatment. Normal operation of the
system is inclusive of treatment and processing of all process
streams.
Effluent Treatment and Disposal Costs
Only one effluent stream is anticipated for the in situ
steam/hot-air stripping process. This stream is the wastewater
generated from boiler and cooling tower blowdown that is
pumped to the water storage tank daily. On-site facility costs
are restricted to on-site storage of the wastewater and assumed
to be the obligation of the site owner or responsible party.
Liquid storage tanks are rented at a daily rate. These costs will
accrue over weekends as well as weekdays. One liquid storage
tank will be necessary for wastewater storage prior to disposal.
Liquid storage tanks are available from a Long Beach dis-
tributor, Baker® Tanks, Inc. It is assumed that the wastewater
will be stored in an open tank. Open liquid storage tanks are
available in a 9,700 gallon size for $10.50/day. Delivery and
pickup charges are each $220/tank.
Off-site facility costs are assumed to consist of wastewa-
ter disposal fees. Wastewater is assumed to meet local water
quality standards. It will be pumped from the water storage
tank and will either be used for dust control purposes or will
simply be evaporated from the decontamination pad on-site.
Charges for disposing of the wastewater in this manner are
essentially zero. No monitoring activities are associated with
this action. If off-site disposal is required by local regulatory
authorities, the water will be pumped from the water storage
tank and disposed of by an appropriate firm at a cost of
approximately $ I/gallon.
Should the wastewater contamination exceed regulated
levels, the wastewater is then classified as a waste (rather than
an effluent) and will either be recycled or disposed of as a
hazardous waste. In the first case, wastewater will be recycled
through the process train to diminish organic contaminant
levels in this stream. Although the quantity of wastewater will
not change significantly, recycling demands will contribute an
additional expense to "Effluent Treatment and Disposal Costs"
and will slightly increase condensed organic quantities, that
contributes an additional expense to "Residuals and Waste
Shipping, Handling, and Transport Costs" (see below). In the
latter case, "Effluent Treatment and Disposal Costs" are re-
duced to storage fees, but "Residuals and Waste Shipping,
Handling, and Transport Costs" are substantially increased
due to the quantities of wastewater generated and the high cost
of hazardous waste disposal.
Residuals and Waste Shipping, Handling and
Transport Costs
Waste disposal costs include storage, transportation and
treatment costs and are assumed to be the obligation of the
responsible party (or site owner). It is assumed that residual or
solid wastes generated from this process consist only of
contaminated health and safety gear, used filters, and spent
activated carbon. Landfill is the anticipated disposal method
for this material at an estimated cost of $100/drum.
It is assumed that the only liquid waste generated by this
process is the condensed organics stream produced by treat-
ment of the organic contaminants removed from the soil. The
waste stream is processed until the majority of the water is
23
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removed and the liquid organics, are stored until they can be
transferred into a vessel suitable for hazardous waste transport.
Removal of excess water results in a highly concentrated
organic waste stream and minimizes costs for hazardous
wastewater disposal. It is assumed that the organics will be
stored in a single covered liquid storage tank, sealed to ensure
no loss of organics. Covered liquid storage tanks (9,700
gallons) are available for $ll/day. Covered liquid storage
tanks arc rented at a daily rate, and these costs will accrue over
weekends as well as weekdays. Delivery and pickup charges
are each $220/tank.
The condensed organics will require treatment prior to
their ultimate disposal. The organics will be transported to a
disposal site for incineration. Costs for transportation and
incineration are assumed to be approximately $0.50/gallon. A
second option for disposal of the condensed organics stream is
recycling the material as a fuel additive in a cement kiln. The
costs for this type of treatment are slightly lower (approxi-
mately §0.25/gallon, including transportation).
Analytical Costs
No analytical costs during operations are included in this
cost estimate. Standard operating procedures for TTUSA do
not require planned sampling and analytical activities. Periodic
spot checks may be executed at TTUSA's discretion to verify
that equipment is performing properly and that cleanup crite-
ria are being met, but costs incurred from these actions are not
assessed to the client. The client may elect, or may be required
by local authorities, to initiate a sampling and analytical
program at their own expense.
The analytical costs associated with environmental moni-
toring have not been included in this estimate due to the fact
that monitoring programs are not typically initiated by TTUSA.
Local authorities may, however, impose specific sampling
and monitoring criteria whose analytical requirements could
contribute significantly to the cost of the project.
Facility Modification, Repair and Replacement
Costs
Maintenance labor and materials costs vary with the
nature of the waste and the performance of the equipment. For
estimating purposes, total maintenance costs (labor and ma-
terial) are assumed to be 10% of equipment capital costs on an
annual basis. The ratio of labor/materials costs is typically 407
60. Maintenance labor has previously been accounted for
under "Labor Costs"; maintenance materials costs are esti-
mated at 60% of the total maintenance and prorated to the
time required for treatment. Costs for design adjustments,
facility modifications, and equipment replacements are in-
cluded here.
Site Demobilization Costs
Disassembly consists of taking the in situ steam/hot-air
stripper apart and loading it onto trailers for transportation. It
requires the use of an operated 30-ton crane, available at
$200/hour, for one 16-hour day. Additionally, disassembly
requires a full (12-man) crew working five 16-hour days (one
week). Labor costs include salary and living expenses. Since
this cost is fixed, it is included here. See "Labor Costs" for
information on labor rates.
Site cleanup and restoration is limited to the removal of
all equipment and facilities from the site. These costs have
been previously incorporated into the disassembly and equip-
ment rental charges. Grading or recompaction requirements of
the soil will vary depending on the future use of the site and
are assumed to be the obligation of the responsible party.
References
1. "Low-Cost Cleanup of Toxic Petrochemicals," CBE News,
December 12,1988.
2. Federal Register, Volume 55, No. 61, March 29, 1990.
3. Federal Register, Volume 50, No. 230, November 29,
1985.
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Appendix A
Vendor's Claims
This appendix summarizes the claims made by the devel-
oper, Toxic Treatments (USA), Inc. (TTUSA), regarding in situ
steam/hot-air stripping, the technology under consideration.
This appendix was generated and written solely by TTUSA
and the statements presented herein represent the vendor's
point of view. Publication here does not represent EPA's
approval or endorsement of the statements made in this section;
EPA's point of view is discussed in the body of this report.
Introduction
The Detoxifier is a patented (US #4,776,409), mobile
treatment unit used in the in situ remediation of contaminated
soils and waste deposits. The soil is treated in place and is not
excavated or removed to the surface.
The commercial prototype of the system has undergone
extensive testing under contract with the responsible party at a
site in San Pedro, California. The site, which is under the
control of the California Department of Health Services, is
contaminated with chlorinated hydrocarbons at concentrations
up to 10,000 parts per million (ppm), as well as other volatile
organic compounds (VOCs) and semivolatile compounds
(S VCs) which range from a few parts per million up to 20,000
to 50,000 ppm. The average of total organic compounds is in
the 500 to 1,000 ppm range.
Operations prior to and since the SITE demonstration
(which was conducted on the San Pedro site) in the vadose
zone and in saturated soil have resulted in the removal of an
average of approximately 97% of volatile contaminants (based
on analysis using SW-846 Method 8240). Semivolatile hydro-
carbons (SW-846 Method 8270) have been reduced by an
average of 86%; this result was unexpected due to the high
vapor pressure of the SVCs in relation to the temperature
generated by the system. This removal efficiency is attributed
to potential chemical reactions catalyzed by the clay soil,
steam distillation, and the formation of low boiling azeotropes
of hydrocarbons. Noise and air emissions during operation are
below the limits set by regional environmental regulations in
Southern California, and no undesirable environmental effects
have been identified.
Potential Application
The Detoxifier is capable of a wide range of site
remediation methods, including:
Steam/hot-air stripping of volatile contaminants.
Solidification/stabilization and construction of contain-
ment structures by addition of chemicals or physical
agents (e.g., pozzolanic materials).
Neutralization or pH adjustment by addition of acids or
bases.
• Destruction or chemical modification of contaminants via
use of oxidizing or reducing chemicals.
• Addition of micro-organisms, nutrients and oxygen to
promote in situ biodegradation.
These methods may be applied to the treatment of volatile
and semivolatile hydrocarbons, heavy metals, and other or-
ganic and inorganic compounds. As of the date of this SITE
report, the Detoxifier has only been used in an in situ steam/
hot-air stripping application to remove volatile and semivolatile
hydrocarbons.
System Advantages
The Detoxifier is an environmentally sound system for
the remediation of contaminated soil. It affords the following
advantages over many other treatment systems:
• In situ remediation, eliminating the requirement of exca-
vation, transportation and disposal of contaminated mate-
rial.
• Permanent treatment, limiting health effects and respon-
sible party liability.
• Closed-loop system, preserving air quality and reducing
worker exposure.
• Versatility, providing treatment of a wide range of or-
ganic and inorganic contaminants.
• Treatment efficiency, utilizing real-time measurement of
contamination and achievement of remediation levels (in
hydrocarbon stripping applications).
• Treatment speed, due to the mixing action of the blades
and energy contained in the steam and air jets, the
Detoxifier cleans the soil quickly.
• Transportable, permitting movement from site-to-site.
The Detoxifier is .also believed to be a cost-effective
method of remediating contaminated soil. Because of limited
25
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experience in commercial operations, however, actual cost
data are limited. (See "Cost Information" below.)
The Process
The Detoxifier consists of a process tower, a control unit,
and a chemical process train. These components are configured
to meet site-specific requirements and vary depending on site
conditions and characterization.
The process tower is essentially a drilling and remediation-
agent dispensing system, capable of penetrating the soil me-
dium to depths of 30 feet with the current equipment; equipment
with capability up to 75 feet can be built Remediation agents
are added to and mixed with the soil at various depths by the
drill head assembly. The drill head assembly is composed of
two drill blades, each five feet in diameter with injection
dispensers. A box-shaped shroud, under vacuum, covers the
drill head assembly to isolate the treatment area and prevent
any environmental release. The process tower assembly is
mounted on a modified Caterpillar chassis.
The control system consists of process monitoring and
control instrumentation. In-line analytical instruments con-
tinuously monitor and record treatment conditions. Flame
f onization detectors (FEDs) monitor the concentration of total
hydrocarbons at select process locations, including the off-gas
from the shroud and the purified return air. A gas chromato-
graph (GC) provides periodic data on the identification and
concentration of specific compounds in the off-gas stream.
The output of the FEDs, GC, temperature sensors, depth
gauge, and other instrumentation is stored in a computerized
data logging system, displayed on a terminal and recorded on
a strip chart recorder. The monitoring data are used to control
and optimize the treatment process and determine the
achievement of remediation objectives.
The chemical process train consists of either treatment
systems to decontaminate off-gases and/or feed systems for
the injection of remediation agents. Remediation agents may
be in dry, liquid, vapor or slurry form, depending on the
nature of the contaminants.
Treatment systems to decontaminate off-gases: In appli-
cations involving in situ steam/hot-air stripping of volatile and
scmivolatile hydrocarbons, the off-gas containing the con-
taminants is captured in the shroud and sent in a closed loop
(to prevent any environmental release) to a trailer-mounted
chemical process train for removal of water and chemical
contaminants; the clean air is then recycled to the soil treatment
zone. The liquid contaminant residue is either recycled or
disposed of off-site. Each chemical process train for the
treatment of off-gases contains modules to remove select
contaminant mixtures by scrubbing, condensation, and ad-
sorption. Typically, an off-gas treatment train includes induced
draft fans for gas conveyance and recycling; scrubbers for the
removal of particulates; cooling and refrigeration systems for
condensing the bulk of the volatiles; a distillation unit to
separate hydrocarbons from water; activated carbon adsorption
units and gas monitoring systems.
Feed systems for the injection of remediation agents: Li
applications involving in situ treatment with only the addition
and mixing of remediation agents to the soil without the need
to process off-gas, the chemical process train consists of
chemical containers, measurement instrumentation and a
pumping system to feed remediation agents to the drill head
assembly. Steam and hot air are injected into the soil to
remove VOCs. The steam and hot air are injected into and
distributed within the ground by means of a pair of hollow
kelly bars and rotating mixing blades five feet in diameter.
The VOCs are evaporated from the soil matrix into the
remediation air stream. These off-gases move up beside the
kelly bars to the surface and are collected in a metal shroud,
which is under a slight vacuum. A blower mounted on a
separate process chassis extracts the air and vapors, along
with a small amount of dust, from the shroud and directs them
to a process train where the contaminants are removed and
collected for recycling or disposal.
The remediation of a large area is carried out by a block-
by-block treatment. The area to be remediated is divided into
rows of blocks, with the process tower, control unit and
process treatment train being moved from one block to the
next after the remediation of a block is completed. To assure
complete coverage of the area to be remediated, the drill
assembly is positioned with a 20% overlap of the previously
treated block. The net surface area of a treatment block is
approximately 29 ft2. The volume of each block is determined
by the depth of remediation with each foot of depth equaling
approximately one cubic yard of material.
System Limitations
Use of the Detoxifier system may be limited by both
physical and chemical characteristics of a contaminated site.
Physical Limitations
Because the system involves penetration of the soil, the
surface must be free of obstructions such as hard pavement,
buildings or other structures, and the subsurface must be free
of major obstructions such as large boulders, concrete footings
or water/sewage mains, and steel pipe several inches in di-
ameter. The system has operated in soil containing boulders
and cast iron pipes up to 12 inches in diameter, 2-inch by 12-
inch planks, and rusty oil barrels. New equipment under
construction will have greater power and torque, thus permitting
operations with more significant subsurface obstructions.
Use of the current prototype system in in situ steam/hot-
air stripping applications is limited to flat surfaces with not
more than 1% grade. The new design of the system will
permit operations with grades up to 5%.
Chemical Limitations
The system, which operates at about 180°F (75°Q, appears
to effectively remove organic chemicals with boiling points of
less than 300°F (150°C). Compounds with higher boiling
points become more difficult to remove by the vaporization
process, and those with boiling points in excess of 400°F may
not be economic to remove. However, many of the high
boiling organic compounds are removed by steam distillation,
i.e., formation of organic azeotropes or a steam-organic azeo-
trope. Experience to date has confirmed this result At the
current site, phenol, naphthalene, and isophorone are often
removed to more than 95%, and, even though only minor
quantities of polyaromatic hydrocarbons (PAHs) are found in
26
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the soil prior to treatment, significant quantities of all PAHs
up to chyrsene have been found in the carbon beds. Post-
treatment soil samples generally show removal of PAHs to
below the detection limit. This is believed to occur via steam
distillation.
The process requires increased treatment times in high
clay soils. Experience indicates that soils with 70% clay
require twice the treatment time as 30% clay (the remainder
silt and fine sand). Thus, high clay soils may be too costly to
treat unless a site has sandy regions to reduce average treatment
time. The process is much more efficient when treatment
depths are greater and also when treating into a saturated zone
containing sand and silt Greater depth not only adds effi-
ciency, but also takes advantage of the sweeping movement of
the operation. Working in the saturated zone in sand and silt
soil matrix increases efficiency because the air can penetrate
deeply into the soil which acts like a floating bed reactor.
Treatment rates have been improved 2 to 3 times.
The process has demonstrated significant removal of
semivolatile compounds (e.g., glycol ethers, bis(2-
ethylhexyl)phthalate, other phthalates and adipates) by a vari-
ety of processes, some believed to be catalyzed by clay in the
soil. The reasons for these results are being studied in an
attempt to quantify them and control them. The effectiveness
of the Detoxifier in removing these semivolatiles must be
further determined by additional field or laboratory studies.
Cost Information
Detoxifier treatment cost data are expressed in dollars per
cubic yard of material treated. The rate varies significantly
depending on the following major factors:
• Nature and concentration of contamination.
• Physical properties of the soil being treated.
• Size and depth of the contaminated area.
• Proximity of the site to the'company's geographical
region.
The following estimates include all direct, indirect, ad-
ministrative, and overhead costs as well as profit. The cost
estimates are based on an in situ steam/hot-air stripping op-
eration. As previously stated, the company does not have any
operational or developmental experience in a neutralization,
solidification, chemical modification, or biodegradation ap-
plication of the Detoxifier. It is estimated, however, that the
cost of such applications will be significantly less than a
steam/hot-air operation because of reduced equipment and
labor requirements.
Excluded from project costs are expenses associated with
soil sampling, chemical analysis, and the transportation and
disposal of contaminant residues.
Costs are extremely sensitive to treatment rates, which
are determined by site characteristics. It therefore is realistic
to quote a range of client costs due to the widely divergent
nature of site characteristics. The estimates for an in situ
steam/hot-air stripping application are presented in Table 4
and are based on experience at the SITE Demonstration site,
assuming a two-shift operation at a site within 500 miles of
the company's location and containing 12,000 cubic yards of
material to be treated.
It should be emphasized that these estimated costs are
based on the company's operations to date with the commer-
cial prototype of the Detoxifier. The costs should be reduced
with additional operating experience and follow-on generations
of equipment
Table 4. Vendor's Cost Estimates
Treatment Rate (ycP/hour)
5 10 20
Project " ~~
duration
(months) 8.08
Estimated
cost($ly
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Appendix B
SITE Demonstration Test Results
The contaminated site was divided into 1,643 treatment
blocks (7 feet-4 inches by 4 feet). Twelve of the blocks in
Area A were treated only to the water table (5 feet below the
soil surface) during Jhe Demonstration Test. These blocks
were sampled before and after treatment in accordance with
the Demonstration Plan [1]. An additional six blocks (also in
Area A), which were treated to below the full zone of con-
tamination, were sampled after treatment only.
Volatilcs in Soil
Levels of volatile organics In the soil were measured by
obtaining composite soil core samples before and after treat-
ment by the in situ steam/hot-air stripping technology. The
results are summarized in Table 1 in the body of this report.
For the entire 12-block test area (grouping all composite
sample data points) the total volatile compounds identified by
SW-846 Method 8240 in the soil before treatment had an
average concentration of 466 ppm with a standard deviation
of 457 ppm. The 95% confidence interval range for the true
mean of the pro-treatment cores was 315 to 618 ppm. After
treatment, the average concentration of total volatile com-
pounds identified by Method 8240 was 71 ppm. The standard
deviation for the post-treatment cores was 80 ppm. The 95%
confidence interval range for the true mean of the post-
treatment cores was 45 to 98 ppm. The high standard deviation
in the samples is indicative of the inhomogeniety of the
contamination at the site. Based on the average pre- and post-
treatment data, the effective removal efficiency for volatile
compounds identified by Method 8240 was approximately
85%. Chlorobenzene, trichloroethene, and tetrachloroethene
were the predominant compounds detected.
The block-to-block variation of post-treatment concen-
tration of volatiles in composite samples obtained from the
12-block test area was substantial. Using the average of the
three post-treatment cores in each block, the concentration
varied from 12 to 196 ppm. The concentration of individual
cores varied from 5 to 355 ppm. This high amount of variability
was unexpected since previous data from TTUS A had indicated
that they were able to treat the blocks in Area A consistently
to below 100 ppm using a treatment protocol similar to the
one used during the SITE demonstration.
Levels of volatile organics in the soil after treatment were
also measured in a separate 6-block test area where treatment
extended into and below the water table and below the zone of
contamination. For the entire 6-block test area (based on all
composite data points), the total volatile compounds identi-
fied by SW-846 Method 8240 in the soil following treatment
with the alternative treatment protocol was 53 ppm with a
standard deviation of 73 ppm. The 95% confidence interval
range for the true mean of the post-treatment cores in this area
was 19 to 87 ppm. In the 6-block test area, ketones (specifically
acetone, 2-methyl-4-pentanone, 2-butanone) were found to be
the primary compounds remaining following treatment Only
one discrete pre-treatment sample was obtained from this
area; additional data was not obtained prior to treatment.
Using the three composite cores obtained from each
block to determine the average concentration in a block,
average block concentration ranged from 16 to 119 ppm in the
6-block test area. Concentrations in the individual cores ranged
from 7.2 to 284 ppm.
Semivolatiles in Soil
The in situ stripping technology was not designed to re-
move semivolatiles from the soil. Nonetheless, semivolatile
compounds were reduced by approximately 55% in the 12-
block test area based on analysis of soil cores. However, no
substantial amounts of semivolatiles or their potential treatment
reaction products were found in the condensed organics col-
lection tank. The average pre-treatment semivolatile concen-
tration of compounds identified by Method 8270 was 902
ppm with a standard deviation of 469 ppm. The 95% confidence
range for the true mean lies between 742 and 1062 ppm. The
average post-treatment semivolatile concentration was 409
ppm. The 95% confidence interval for the true mean of post-
treatment cores was 237 to 581 ppm; the standard deviation
was 407 ppm. Block-to-block reduction varied from 7% to
95% among the 12 blocks in the treatment area. (See Table 5.)
The major semivolatile organic compound found in the
post-treatment soil was bis(2-ethylhexyl)phthalate, with a
concentration ranging from 4.6 to 1,200 ppm. Other com-
pounds found in lesser concentrations were phenol, naphtha-
lene, and phenanthrene.
Dye Studies
Fluorescein dye was added to the soil at a depth of 3.5
feet prior to the treatment to serve as a tracer for determining
the post-treatment homogeneity of the soil and for evaluating
the downward migration of contaminants. The dye concentra-
tions were found to be variable through the treatment blocks
after treatment. The highest concentrations of dye were found
28
-------
Table 5. Demonstration Test Results for Semivolatiles
Block
Number
A-25-e
A-26-e
A-27-e
A-28-e
A-29-e
A-30-e
A-31-e
A-32-e
A-33-e
A-34-e
A-35-e
A-36-e
Avg*
StdDeV
Pre-
Treatment
(wfg)
595
1117
1403
1040
1310
1073
781
994
896
698
577
336
902
469
Post-
Treatment
(\igfg)
82
172
439
576
726
818,
610
49
763
163
192
314
409
407
Percent
Reduction
(%)
86
85
69
45
45
24
22
95
15
77
67
7
55
NA»
"Reportedfor the entire treatment area, based on analysis
of all composite cores.
b Not applicable.
in the 4 to 5.5 foot range indicating that the treatment had
reached the bottom of the block. Occasional smaller peaks
were found below the treatment area, although it was not clear
whether this was an artifact of the sampling technique; the dye
peaks below the five foot depth were always found at the
interface of two cores. Figure 3 graphically depicts these
results.
Condensed Organics
The condensed organics, collected in the holding tank,
formed two distinct phases. The bottom phase was essentially
all organics, while the top phase consisted nearly entirely of
water. A total of 1240 L of condensed organics were collected
during treatment of the 12-block test area. The three major
compounds in the condensed organics were the same as those
found in the soil. The approximate concentrations of the major
organics in the bottom phase were:
Trichloroethene - 36%
Tetrachloroethene - 30%
• Chlorobenzene - 22%
The total concentration of semivolatile organic com-
pounds was less than 0.3% in the bottom phase. The top phase
contained about 1% volatile organics and less than 100 ppm
semivolatile organics.
Treated Water
The treated water coming from the wet carbon filter into
the cooling tower contained small residual amounts of VOCs.
The average treatment efficiency for the wet carbon filter was
found to be 97%. The total amount of volatile compounds
detected by Method 8240 in the treated water for the entire
twelve-block test area was 620 grams. The average concen-
tration was about 8 ppm. The main compounds detected in the
treated water were acetone, tetrachloroethene, and
trichloroethene.
Fugitive Emissions
Fugitive emissions were measured using the flux cham-
ber technique from the area around the shroud during treatment
and from the block that had just been treated (after removal of
the shroud). Three soil treatment blocks were measured. In all
three cases, the highest emission rates were measured from
Location 3 which sampled the block which had just under-
gone treatment immediately after removal of the shroud (see
Figure 1 in the body of this report).
Table 6 summarizes the results of the fugitive emission
sampling. The total measured fugitive emissions of organic
compounds from the three heavily contaminated blocks aver-
aged less than 22 grams. Assuming that 6 blocks with similar
levels of contamination are treated each 16-hour day during
remediation, the total organic emissions from the blocks would
be less than 140 grams per day (about 0.3 pounds per day).
TCLP Results
Although in situ treatments are not subject to land ban
regulations, one sample core from both the pre-treatment and
post-treatment soil was subjected to TCLP extraction and
analysis to determine the amount of leachable volatile and
semivolatile compounds, as well as leachable metals in the
soils. Duplicate samples were analyzed for organics and and
metals; they showed significant variabililty for pre- and post-
treatment samples. The results for metals for both pre- and
post-treatment analyses are well below the EPA regulatory
limits found in the Federal Register [2] for all of the compo-
nents. The post-treatment leachate for all organics was below
the regulatory limits.
Physical Tests
Each core from the pre- and post-treatment sampling was
measured and sampled to determine percent moisture, bulk
density, and specific gravity. Table 7 summarizes these results.
Based on statistical analysis, there is essentially no difference
in the moisture content and the bulk density of the soil
between pre-and post-treatment.
29
-------
A-26-e
1 2
Legend
I 1 No Dye Present
ttia 1-200 PPB Dye
iH 201-1000 PPB Dye
> 1000 PPB Dye
No Sample
Figure 3.
Demonstration results for fluorescein dye.
Table 6. Fugitive Emissions From Blocks A-28-e,
A-29-e, andA-30-e
Table 7. Demonstration Test Results for Physical
Properties
Slock
Number
A-28-e
A-29-e
A-30-e
Avg
Starting
Emission
Rate*
(gtm?-
min)
0.0050
0.0045
0.018
0.063
Ending
Emission
Rate3
(glrrf-
min)
0.0010
0.0010
0.0010
0.0010
Emission
Above
Back-
ground1
(8)
65
5.4
49
20
Total
Emission
From
Block
(s)
6.8
5.6
51
21
Percent
Moisture
Pre-Treatment
Avg
StdDev
Post-Treatment
fivg
StdDev
(%)
30.2
7.9
277
5.4
Bulk
Density
(8/cc)
152
0.09
1 55
0.13
Specific
Gravity
(glee)
256
0.09
2 7?
0.07
Sample taken at Location 3. Emissions from Locations 1,2,4,
and 5 were negligible compared to Location 3.
30
-------
Appendix C
Process Description
The in situ steam/hot-air stripper is constructed I of two
major elements: the process tower and the process train. The
process tower includes two hollow augers that drill into the
soil to be treated. The process train consists of two systems
which operate in conjunction during the treatment of the soil:
the process gas treatment system and the condensed liquids
treatment system or distillation system. The gas treatment
system provides the conditioning of steam/hot-air/volatiles so
that the air can be reintroduced into the process. The liquids
treatment system separates the condensed steam from the
condensed volatile organics by distillation. The organic waste
is then collected for disposal or recycling and the condensed
steam is used to supplement the cooling system.
The Process Tower
The process tower, shown schematically in Figure 4,
consists of five major components:
the treatment shroud,
the kelly bars,
the cutter bits,
the rotary table, and
the crowd assembly.
Together, these components loosen the soil, inject the
steam/hot-air, and collect the stripped volatiles from the soil.
The cutter bits are attached to the end of each kelly bar. A
set of mixing blades is also attached above the cutter bits.
Each kelly bar is thus equipped with two sets of opposing
blades (cutter bits and mixing blades) positioned at 90 degrees
from each other, as shown in Figure 4. The cutter bits have
nozzles for injection of steam/hot-air into the soil. Mechanical
power is provided to the kelly bars by the rotary table and
crowd assembly.
The steam and hot air raise the temperature of the soil
mass to 170 to 180°F, thereby increasing the vapor pressure of
the volatiles, volatilizing them away from the soil particles,
and allowing them to be transported to the soil surface by the
action of the steam/hot-air and an applied vacuum. The cutter
bits are moved vertically to selectively treat areas of greater
organic contamination as detected by in-line instrumentation.
This treatment cycle procedure is repeated until the contami-
nant levels in the soil are satisfactorily reduced. The treatment
procedure facilitates overlapping treatment of all depths of the
block to ensure adequate exposure of the contaminants to the
steam and hot air.
Upon emerging from the soil surface, the volatilized
vapors and hot air (off-gas) are collected beneath the treat-
ment shroud and are then passed on to the gas treatment
system of the process train.
The Gas Treatment System
The gas treatment system consists of the following
major equipment:
the scrubber,
the cyclone separator,
the cooling system,
the carbon adsorption system, and
the compressors.
Paniculate matter entrained in the process airstream is
removed in the scrubber. The process airstream is then
directed to a cyclone separator to remove the water droplets
introduced to the airstream in the scrubber and water result-
ing from condensing steam. The water collected in the sepa-
rator is directed to the distillation system for purification.
After this initial conditioning, the airstream is subjected
to three stages of cooling by heat exchangers. These stages
remove water vapor and the volatile compounds from the
airstream by condensation. Condensate that forms inside the
coolers is accumulated and directed to the distillation system.
The process airstream from the cooling system is passed
through the carbon beds to remove volatile organics. There
are two carbon adsorption vessels which are used alternately.
While one vessel is used for adsorption of volatiles in the
airstream, the other vessel undergoes regeneration of its
carbon bed. The liquids produced from regeneration are
directed to the distillation system.
The airstream exiting the carbon adsorption system is
drawn through the intake filter of a two-stage reciprocating
compressor. The compressor is designed to increase the air
pressure from atmospheric to 250 pounds per square inch
gauge (psig), thus increasing the discharged air temperature
to approximately 275°F. This compressed air is passed back
through the kelly bars to the ground to strip more contami-
nants from the soil.
The Distillation System
The condensates that are generated by the cooling sys-
tem, the cyclone separator, and the regeneration of activated
carbon are first passed through a 4-stage coalescer/separator.
31
-------
Water contaminated with light organics is pumped from the
coalescer/separator to the distillation tank. The distillation
tank separates the remaining volatile components from the
water. The vaporized volatile components are removed from
the distillation tank, condensed, and collected in the condensed
organics holding tank.
An activated carbon filter is used to remove residual
organics in the water prior to discharge to the cooling tower
sump. The carbon filter is regenerated, and the organics
removed are discharged to the condensed organics holding
tank.
Kelly
Bars
Shroi
Mixing
Blades
\
'^
.,•»"
"' 4
^.
T
W-fl-tL
">;
r
\
/"/-*
X i ^i
"^ Cutter ft 71
\ Bits -*> '
•
j
•+*•
P
Steam
Generator
Return
Water to Ajf
Cooling Tower
T
>- *
.•*
1
<.
Process
Train
\ r
Condensed
Organics
Collection
Tank
Figure 4.
Schematic of the process tower.
32
-------
Appendix D
Case Studies
Baseline Testing [3]
Description
Baseline Testing was conducted by TTUSA to evaluate
the effectiveness of in situ steam/hot-air stripping in remov-
ing hydrocarbons from the soil at the GATX Annex Termi-
nal site. The Baseline Testing activities included:
• Treatment of 10 blocks.
• Collection of pre- and post-treatment samples.
• Collection of soil vapor emission data before and during
the treatment of the 10 blocks.
• Condensate analysis to evaluate the hydrocarbons col-
lected by the in situ steam/hot-air stripper process treat-
ment train.
Testing Protocol
The pre-treatment soil samples were obtained from 24
borings in Areas A, B, and D: 2 in each of the 10 blocks to be
treated and 4 in locations west of the area to be treated. Post-
treatment soil samples were collected from 14 borings located
in 10 treatment blocks: one boring per block in Areas A and
D, and two per block in Area B. Soil vapor emissions
monitoring was also conducted during Baseline Testing.
Major Conclusions by TTUSA Based on Baseline
Testing
Based on a pre- and post-treatment chemical analysis,
the in situ treatment had a number of effects on the treatment
blocks. A significant reduction in the concentration of VOCs
was observed for all test blocks. The mechanism for the
reduction appeared to be in situ volatilization and recovery
of the volatilized material. This is substantiated by the
calculations performed on chemical analysis data, which
show the mass of VOCs removed from the soil as approxi-
mately equal to the mass of VOCs collected in the holding
tank. Differences between removal and collection can be
attributed to sampling uncertainties and loss to the atmo-
sphere. The target cleanup level, a final VOC concentration
of less than 100 ppm, was achieved in 8 out of 10 of the
blocks treated.
A reduction in the concentration of SVCs was indicated
in all treatment blocks. The mechanism of removal cannot be
supported by the analysis performed, since calculations from
the analyses show that only a fraction of a percent of the
SVCs removed from the soil were collected in the condensate.
The comparison of pre- and post-treatment data indicated
that VOCs with lower boiling points were more effectively
removed by the in situ steam/hot-air stripping process than
higher boiling VOCs. Frequently, compounds with boiling
points below 175°F (80°C) were removed to levels which
could not be detected. When they were detected, these low
boiling compounds exhibited significant reductions in con-
centration. Those compounds with boiling points above 175°F
also exhibited significant reductions in concentration, but the
concentrations were less frequently reduced to below the
detection limit.
The average values of wet and dry soil density increased
following the treatment The average moisture content of the
soil decreased after treatment.
Overall, the treatment process increased the soil vapor
emissions within and directly adjacent to the area under
treatment Data indicate that the increase in emissions does
not appear to be significant.
Occasionally, compounds which were not detected in
pre-treatment samples were found in the post-treatment
samples. Possible explanations for this include: (1) decreased
detection limits due to overall lowering of concentration; (2)
chemical alterations of compounds because of reactions oc-
curring during treatment; and (3) redistribution of compounds
within the block.
Data Summary
Soil emissions data show an average undisturbed emission
rate of 2.0 x 10"3 g/min-m2. During treatment, the level rose to
an average emission rate of 3.2 x 10'2 g/min-m2 at the soil/
shroud interface, and an average of 2.4 x 1Q-2 g/min-m2 at 2 feet
away from the shroud perimeter. Comparisons of emission
rates indicated that Area D had a lower overall emission rate
both before and during treatment. This may be an effect of the
clay type of soil found in Area D. While the data shows an
order of magnitude change of emissions from the soil before
treatment to during treatment, the actual increase, in pounds
of emitted chemicals on a daily basis, cannot be calculated
from the data collected since emissions were not monitored
after treatment of a block was completed. However, it may be
only a small increase over the baseline.
33
-------
The mass of VOCs and SVCs collected by the process
train and removed from the soil were calculated from the
chemical analysis data gathered during the test Table 8 presents
these results; Table 9 presents the results of the physical
analyses. For VOCs, the mass removed from the ten blocks
(296 Ibs) is close to the amount captured in the condensed
organic holding tank (265 Ibs). This represents approximately
90% closure. It is likely that the 10% difference can be
accounted for by measurement uncertainties and losses within
and from the system. The SVC mass balance, however, does
not close in such a manner. The calculated removal from the
soil of the first six treatment blocks in the Baseline Testing
shows 1,018 Ibs of SVCs removed from the soil, but the
amount of SVCs in the condensed organic holding tank was
only 2.1 Ibs (0.2% closure).
Process Improvement and Soil Vapor Emissions
Tests [4]
Description
Utilizing recently modified equipment and procedures,
Process Improvement and Soil Vapor Emissions Tests (called
"Remediation Improvement Tests" by TTUSA) in treatment
Area D were initiated to evaluate the effect of moving the air
manifolds from the top of the blades to the back of the blades
on the augers and to evaluate the effect of utilizing both a gas
chromatograph (GQ and a flame ionization detector (FID),
rather than an FID alone, to determine organic contaminant
levels in the soil blocks during treatment The tests focused on
three treatment blocks. Test activities consisted of:
• The collection of pre- and post-treatment soil samples
from the three subject treatment blocks.
• The treatment of the three subject treatment blocks.
• The collection of soil vapor emissions data, during and
after treatment
Testing Protocol
Pre-treatment soil samples were collected from a total of
six borings in the three treatment blocks (two per block). Post-
treatment samples were collected from a total of three borings
(one per block). Soil temperature was monitored after treatment
to determine the rate that heat dissipated from the soil. Soil
vapor emissions were also measured.
Major Conclusions by TTUSA Based on Process
Improvement and Soil Vapor Emissions Tests
Modifications to equipment and treatment procedures
resulted in a 3.8% increase in removal for tetrachloroethene
and a 3.8% decrease in removal for total VOCs. This indicates
that there was no significant change in treatment efficiency
due to the modifications in the augers and the treatment
procedures.
Soil vapor emissions data implies that treatment by the in
situ steam/hot-air stripping unit did not result in any significant
fugitive emissions during testing. Comparison of the post-
treatment soil vapor emissions indicates that using a clean
Table 8. Chemical Analysis Results for Baseline Testing
Soil
Area
Pre-Treatment Soil
Avg VOC (ppm)
Avg SVC (ppm)
Post-Treatment Soil
Avg VOC (ppm)
Avg SVC (ppm)
Percent Reduction:
Avg VOC
Avg SVC
A
1,114
3,775
12
627
99%
83%
B
1353
12,116
30
1,766
98%
85%
D.
3954
1,014
140
85
96%
92%
AIL
2,140
5,635
61
826
97%
85%
Collected Organics
DHS Sample
Aqueous Layer (mg/L)
Organic Layer (mgIL)
TTUSA Sample
Upper Layer (mgfL)
Middle Layer (mg/L)
Lower Layer (mg/L)
Average (mg/L)
VOC Concentration
1,809
1,000,000
4,499
3,452
587,000
198,317
SVC Concentration
192
21,450
NA"
NA
NA
*NA -Not analyzed
34
-------
Table 9. Physical Analysis Results for Baseline Testing
Area A
B
Bulk Density (Iblff)
Pre-Treatment
Post-Treatment
Percent Increase
Moisture (%)
Pre-Treatment
Post-Treatment
Percent Decrease
75.0
965
29%
37.3
25.4
32%
75.3
88.0
16%
43.4
295
32%
43.4
75.0
73%
88.2
40.8
54%
layer of soil to cover treated treatment blocks reduces fugitive
emissions by over 50%.
Data Summary
Review of the pre- and post-treatment chemical analyses
for tetrachloroethene demonstrated an average removal of
91.2%. Average percent removal for total VOCs was 94.1%.
These results are very comparable to chemical analyses of
samples taken during the Baseline Test, prior to the subject
modifications.
The average soil vapor emission during treatment was
0.16 ppm. This is less than the average pre-treatment vapor
emission concentration for Area D as determined in Baseline
Testing (0.23 ppm). Post-treatment soil vapor emissions from
an uncovered, treated block averaged 2.64 ppm, while emis-
sions from a soil-covered block averaged 1.13 ppm, 57.2%
less.
Mixing, Treatment, and Downward Migration
Tests [4]
Description
Mixing, Treatment, and Downward Migration Tests (called
"Containment Tests" by TTUSA) were conducted on four
treatment blocks in treatment Area B in a progression of
"activities comprised of:
• The collection of pre- and post-mixing and post-treatment
samples from the subject treatment blocks.
• The mixing of four treatment blocks, injecting only hot
air.
• The placement of fluorescein dye packets in four treatment
blocks, the treatment of three treatment blocks, the col-
lection of soil samples from all four blocks for fluorescein
dye evaluation.
• The collection of soil vapor emissions data during and
after treatment
Testing Protocol
Pre-treatment soil samples were collected from six borings
in three blocks. These three blocks underwent mixing proce-
dures; a fourth block was also mixed as a control block. Post-
mixing samples were collected from six borings in the three
test blocks. A 50-gram packet of crystalline fluorescein dye
was placed in each of 20 borings drilled in four (three plus one
control) blocks prior to treatment Post-treatment soil samples
were collected from the three test blocks. One boring was
collected from each block. Soil vapor emissions were measured
during and after the treatment.
Major Conclusions by TTUSA Based on Mixing,
Treatment, and Downward Migration Tests
Based on average VOC concentration data and treatment
time data, it appears that mixing with only hot air injection
caused a decrease in the concentration of VOCs. The percent
decrease appeared to increase with time. A "Student's t-Test",
however, which takes into account the standard deviation of
the data, indicated that mixing procedures had little or no
effect on the concentration of VOCs. Conclusive data for the
effect of mixing on SVC concentration was not obtained
during these tests, and a "Student's t-Test" of the data indicated
that there was no treatment effect [1].
The downward migration of fluorescein dye due to soil
treatment did not appear to be significant. The indicated
extent of dye migration is consistent, even in the treatment
blocks treated with steam and hot air. Because fluorescein dye
is generally more soluble than the VOCs or SVCs found on-
site, it is reasonable to assume that any downward migration
of the VOCs and SVCs would be less than the dye. Therefore,
the extent of downward migration of VOCs and SVCs was not
significant. The data does not conclusively indicate if depth of
dye migration changes with time.
Data indicates that treatment with steam and hot air had a
significant effect on reducing VOC concentrations. Statistical
analysis of the data supports this conclusion. Data on the
reduction of SVCs in the soil was inconclusive. A "Student's
t-Test" indicated that there was no change in the SVC concen-
tration. Statistical analysis of samples taken from below the
treatment zone indicated that there was no change in the
concentration of either the VOCs or the SVCs.
Soil vapor emissions during treatment averaged less than
pre-treatment vapor emission concentrations for Area B as
determined in the Baseline Tests. Again, this implies that
35
-------
treatment by the in situ steam/hot-air stripping unit did not
result in significant fugitive emissions during testing. Soil
vapor emissions decreased further after treatment was com-
pleted.
Data Summary
After the mixing tests with only air, treatment blocks B-
48-g, B- 49-g, and B-50-g showed the following decreases in
average VOC concentrations based on the analysis of pre-
mixing and post-mixing samples: 16%, 75%, and 79%, re-
spectively. After mixing activities, SVC concentrations
increased by 122% for block B-48-g, decreased by 93% for
block B-49-g, and decreased by 70% for block B-50-g. As-
sociated mixing times for the respective treatment blocks
were 21 minutes, 11 minutes, and 100 minutes.
Average dye penetration depth in block B-46-g (treated
with hot air only) for 1,7, and 16 days after treatment was 4.1
feet, 0.1 feet deeper than the treated depth. Average dye
penetration depth over the entire time frame in blocks B^8-g,
B-49-g, and B-50-g (treated with both steam and hot air) was
4.7, 5.5, and 4.5 feet, respectively. Dye migration depth
averaged 0.6 feet deeper than the treated depth for blocks B-
48-g, B-49-g, and B-50-g.
Within the treatment zone, average VOC concentrations
after treatment with air and steam showed a 89%, 91%, and
100% decrease in the VOC concentrations from their corre-
sponding post-mixing levels for blocks B-48-g, B-49-g, and
B-50-g, respectively. Data on the reduction of SVCs in the
soil were inconclusive; results showed a 33% decrease, 59%
increase, and 9% increase in the SVC concentrations from
their corresponding post-mixing levels for blocks B-48-g, B-
49-g, and B-50-g, respectively.
The average soil vapor emission around the shroud pe-
rimeter during treatment was 0.58 ppm. This is less than the
average pre-treatment vapor emission concentration of 1.85
ppm for Area B as determined in the Baseline Tests. Average
post-treatment soil vapor emissions from within the treated
blocks B-48-g, B-49-g and B-50-g and from around the pe-
rimeter of these blocks ranged from 4.78 ppm at zero minutes
after treatment to 1.72 ppm at 291 minutes after treatment
TTUSA Bench-Scale Tests [4,5]
Description
As a follow-up on information generated from previous
tests, several Bench-Scale Tests were performed by TTUSA.
The Bench-Scale Tests were used to evaluate the response of
microbial organisms to treatment as well as the potential for
the removal of semivolatile compounds by various mechanisms
including steam distillation, hydrolysis, oxidation and reduc-
tion. Test activities were comprised of:
• The collection of treated and untreated soil samples for
microbial evaluation.
• The evaluation of microbial activity in treated and
untreated soil.
• A Scoping Bench-Scale Test to evaluate the potential for
hydrolysis of SVCs.
• Sampling of the carbon beds and the liquid organics held
in the liquid storage tank to examine the locations and
quantities of SVCs captured in the full-scale in situ
steam/hot-air equipment
• Five Contained-System Tests to explore the fate of
semivolatiles: three Spiked Soil Tests and two Contami-
nated Soil Tests.
Testing Protocol
The microbial evaluation was conducted to assess the
effect of the steam/hot-air stripping process on the existing
microbe population and the potential for the microbe popula-
tion to re-establish itself after treatment Six soil samples were
obtained from duplicates of samples previously collected
from treated soil and four samples obtained from duplicates of
soil samples previously collected from untreated soil.
Soil from each sample was used to prepare an aliquot for
dilution. One milliliter from each dilution was then transferred
to a petri dish and warm nutrient agar was added. The contents
of the petri dish were thoroughly mixed, allowed to solidify,
and then incubated for 48 hours at 30°C. Following the
incubation period, visible colonies were counted to determine
the number of viable organisms. The 6 petri dishes containing
organisms from the treated soil were then incubated for an
additional 7 days and enumeration procedures repeated to
determine the number of viable organisms after treatment.
The Scoping Bench-Scale Test for hydrolysis was con-
ducted on contaminated soil from the GATX Annex Terminal
site exhibiting total SVC concentration of 887 ppm. A 470-g
aliquot of soil, taken from a well-mixed 2-kg soil sample from
treatment area B, was heated in water to 170°F (77°C) and
held at that temperature for 1 hour. The system was open to
air, so no vapors were captured. Analysis for both VOCs and
SVCs was performed on samples of the pre- and post-treatment
soil and on the water remaining at the conclusion of the test.
To examine the quantities of SVCs captured and their
respective locations of accumulation in the full-scale equip-
ment, samples were collected from the carbon beds and from
the liquid storage tank and were analyzed for semivolatile
compounds.
A series of five Contained-System Tests were also per-,,
formed. A laboratory-scale in situ steam/hot-air stripper
simulating field treatment conditions was used for these tests.
Tests numbered 1,2, and 5 (Spiked Soil Tests) were performed
on clean soil from the site which had been spiked with known
amounts of the major SVCs of interest: bis(2-
ethylhexyl)phthalate, butyl cellosolve, butyl carbitol, 2-
phenoxyethanol, and glycol ether. Tests 3 and 4 (Contaminated
Soil Tests) were performed on contaminated site soil from
treatment block B-48-g. For each run, approximately 5 gallons
of soil were treated with 1 scfrn of air and approximately 0.25
Ib/min of steam, maintaining the temperature of the soil at
176°F (80°C). In all of the Contained-System Tests, samples
of the pre- and post-treatment soil and of the condensed liquid
were analyzed for SVCs. A barium chloride trap was analyzed
in Tests 2 and 3, but since it contained little contamination and
showed no Carbon Dioxide capture, its use was discontinued
in the subsequent tests. For all of the Contained-System Tests,
36
-------
the carbon bed from the bench-scale apparatus was sampled
and analyzed for VOCs; it was also analyzed for S VCs in Test
5 in an attempt to improve the SVC mass balance.
Major Conclusions by TTUSA Based on Bench-
Scale Tests
Based on the soil samples collected in Area B, the num-
ber of microbe colonies grown after 48 hours of incubation
appears to indicate that treatment using the steam/hot-air
stripping process causes microbe populations to decrease.
Evaluation of the potential for microbial regrowth in Area B
indicated that, at an optimal temperature of 86°F (30°C), the
number of microbe colonies increased after an incubation
period of 168 hours in all cases. This indicates that at a proper
temperature, the microbial populations in previously treated
soil are capable of regrowth. Evaluation of the microbial
regrowth data showed higher potential for regrowth in Area D
(clayey soil) than in Area B. Microbial growth is anticipated
to be inhibited for approximately 4 weeks following treatment,
while the soil temperature drops to a favorable range for
growth of microbes.
The biological activity from microbe population in site
soil will not significantly reduce the hydrocarbons at the site.
Much higher microbe populations are necessary in order to
cause a significant decrease in the concentration of hydrocar-
bons due to biological oxidation or reduction. :
The results of the Bench-Scale Tests show agreement
with the full-scale treatment data, exhibiting removals of
SVCs of 46% to 87%; the removals calculated during the
Baseline Test were 64% to 94%. Obtaining this result in a
contained system suggests that downward migration, biological
activity, and dilution by mixing are not significant factors in
the field treatment results. The field mechanisms of removal
appear to be volatilization, steam distillation, catalytic de-
composition, hydrolysis, and binding to the clay in the soil.
The SVC mass balance performed as part of the Contained-
System Tests was poor, similar to that performed for the full-
scale field tests. One possible cause of this is a reaction of the
phthalate compounds, catalyzed by the clay in the soil. The
expected result of such reactions would be phthalate isalts
which are chemically bound to the soil; and alcohols which
would decompose and dehydrate to form C8 - C1S aliphatic
hydrocarbons.
Unlike the full-scale field tests, the VOC mass balance
was also poor. The carbon bed analyzed contained little of
either VOCs or SVCs. This raises some questions about the
nature of the contaminants because the carbon bed is believed
to be able to catch any residual contamination before it enters
the atmosphere. Since VOCs do not bind to the soil, it is
postulated that both SVCs and VOCs are forming aerosols
and escaping through the carbon beds without adsorption.
Due to the recycling of the air in the field treatment system,
escape of organic compounds is expected to be negligible for
the full-scale unit.
Data Summary
The average number of colonies grown in untreated soil
from Area B was 3.4 x 103 colonies per gram. In comparison,
the number of microbe colonies grown after 48 hours of
incubation in treated soil from the same area averaged 2.0 x
102 colonies per gram. Soil samples from Area B evaluated for
regrowth after 168 hours of incubation exhibited increases in
the number of microbe colonies ranging from 420% to
61,800%. Soil samples from Area D were also evaluated for
regrowth after treatment. These samples exhibited changes in
the number of microbe colonies ranging from -30% to 45,300%.
The laboratory incubation temperature was 86°F (30°C). This
is much less than the temperature of the soil during treatment
which is approximately 176°F (80°C).
For the Scoping Bench Scale Tests, percent removal of
SVCs was 69% and percent removal of VOCs was 81%.
The analysis of system carbon beds and the organics from
the liquid storage tank showed moderate amounts of semi-
volatile compounds and large amounts of C8 - C15 olefins,
substantiating the possibility that phthalates are undergoing
reactions catalyzed by the clay.
Data from the Spiked-Soil Contained-System Tests is
summarized in Table 10. Results of the Contaminated-Soil
Contained-System Tests (3 and 4) indicate an average SVC
removal of 53.5% and an average VOC removal of 82% as
shown by Table 11.
Six-Week Deep Study [6]
Description
During the Six-Week Deep S tudy, the performance of the
in situ steam/hot-air stripping unit was tested in the saturation
zone to depths of 10 to 12 feet in Area A at the GATX Annex
Terminal site. Previous operations in all other areas of the site
had been restricted to treatment depths above the water table
(located approximately 6.5 to 7.5 feet below the soil surface in
this area).
Testing Protocol
Available data indicates that a total of 94 highly contami-
nated blocks were treated to 10 to 12 feet in the 23 days since
the beginning of the 6-week test. One block was sampled prior
to treatment Post-treatment samples were collected at 5 to 7
feet and at 9 to 10 feet in approximately 5 borings. TTUSA also
took four soil samples to provide guidance in relating real-time
process operating parameters and soil chemistry. The samples
were taken after the completion of treatment and the results of
these analyses were compared to final FID readings.
Major Conclusions by TTUSA Based on Six-Week
Deep Study
No operational problems of any kind occurred as a result
of treating the saturated zone. The downhole temperature was
often improved when treated below the water table. During
treatment in the saturated zone, the in situ steam/hot-air stripper
was able to operate between 205°F and 210°F downhole,
without exceeding the 170°F limit for shroud gas temperature.
For operations in the vadose zone, the downhole temperature
limitisl75°Ftol80°F.
The removal rate of contaminants below the water table
appears to be faster than in the previous treatment to 5 feet This
is due in part to the elevated downhole temperature. A second
factor influencing the -increased removal rate is the effect of
37
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Table 10. Spiked-Soil Contained-System Tests Results
Test Number
Pie-Treatment
SVC spike (g)
Post-Treatment
SVC in soil (g)
THC in water (g)
THC in carbon bed (g)
TOTAL (g)
THC missing* (g)
Percent Removal
1
1933
31.885
0.017"
NA°
31.902
161398
835%
2
b
b
b
b
b
b
b
5
247.1
31.021
47.293
0.632
78.946
168.154
87.4%
*VOC only; water in Test 1 was not analyzed for SVC.
* Test 2 data was ignored due to serious errors encountered during chemical analysis.
eNA — Not analyzed.
JPre-treatment spike (g) minus post-treatment total (g) equals THC missing (g).
Table 11. Contaminated-Soil Contained-System Tests Results
Test Number 3 4
Pre-Treatment
SVC(g)
VOC(g)
Post-Treatment
SVC in soil (g)
SVC in water (g)
SVC in carbon bed (g)
TOTAL SVC (g)
VOCinsoil(g)
VOC in water (g)
VOC in carbon bed (g)
TOTAL VOC (g)
THC missing (g) based on SVC analysis
THC missing (g) based on VOC analysis
Percent Removal
SVC
VOC
30.987
9.376
16.758
12574
NAb
29332'
3.403
0.133
0.404
3.940
1.655
5.436
45.9%
63.7%
30.987"
9.376"
12.112
7.263
NA
19.375'
0.000
0.670
1.236
1.906
11.612
7.470
60.9%
100.0%
"From an estimated weight, based on volume of container.
*NA — Not analyzed.
c This total excludes SVCs which may appear in the carbon bed since the carbon bed samples
were not analyzed for SVCs.
sandy soil present in and below the water table. It is postulated
that, in these areas, the water causes the treatment to act like a
fluidizcd bed which improves the exchange and removal rates.
The continuous HD-versus-depth readings obtained when
the unit's blades penetrate the soil may provide a qualitative
characterization of the soil contamination chemistry profile.
The in situ steam/hot-air stripper may, therefore, have potential
to determine the depth of contamination and thus the required
treatment depth.
The FID/soil contamination correlation generated for use
when treating to 5 feet does not apply in the saturation zone.
Real-time soil samples indicate that residual soil contamina-
tion levels of only 30 to 60 ppm are possible with FID
readings of 2,500 to 3,000 ppm. This is approximately two
times the FID readings obtained in the vadose zone for
treatment to the same levels.
Data Summary
Complete results on the 8240 and 8270 analyses were not
available as of the date of this report. Results of the 8010
analyses show chlorinated hydrocarbon levels ranging from 24
to 60 ppm, with an average value of 39 ppm. The correlation
between these levels and the final FID readings requires
further investigation.
38
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References
1. Science Applications International Corporation. August
18,1989. "Demonstration Plan for Demonstration Tests
on Toxic Treatments In Situ Steam/Hot-Air Stripping
Technology, Volumes 1 and 2."
2. Federal Register, Volume 55, No. 61, March 30,1990.
3. Harding Lawson Associates. March 8, 1989. "Baseline
Calibration and Testing, Annex Terminal Site, San Pedro,
California." A report prepared for GATX Terminals Cor-
poration.
4. McLaren Engineering. November 30, 1989. "Six-Block
Test Report, Annex Terminals Site, San Pedro, Califor-
nia." A report prepared for GATX Terminals Corpora-
tion.
5. "Toxic Treatments (USA), Inc. January 10,1990. Part of
the Disposition of Chemicals During and After Detoxifier
Remediation." A Draft Report on the Bench-Scale Tests.
6. "Toxic Treatments (USA), Inc. February 1990." Four-
Week Report on Using the Detoxifier to Treat in the
Saturated Zone.
*U.S. GOVEHNMENT PRINTING OFFICE: 1991-550-638
39
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