EPA/540/AR-92/019
December 1992
Low Temperature Thermal
Treatment (LT3®) Technology
Roy F. Weston, Inc.
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
! ' , i ' i n|', ' ' Mi1 ", •' • I ' • • I <
The information in this document has been prepared for the U.S. Environmental Protection Agency (EPA)
Superfund Innovative Technology Evaluation (SITE) program under Contract No. 68-CO-0047. This document
has been subjected to EPA peer and administrative reviews and has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute an endorsement or
recommendation for use.
u
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Foreword
The Superfund Innovative Technology Evaluation (SITE) program was authorized by the 1986 Superfund
Amendments and Reauthorization Act (SARA). The SITE program is a joint effort between the EPA Office
of Research and Development (ORD) and the Office of Solid Waste and Emergency Response (OSWER). The '
purpose of the program is to accelerate the development and use of innovative cleanup technologies applicable
to Superfund and other hazardous waste sites. This is accomplished through field technology demonstrations
designed to provide performance and cost data on selected technologies.
A field demonstration was conducted under the SITE program to evaluate the Low Temperature Thermal
Treatment (LT3®) technology. The technology demonstration took place at the Anderson Development Company
(ADC) site in Adrian, Michigan. The purpose of the demonstration effort was to obtain information on the
performance and cost of the technology and to assess its use at this and other uncontrolled hazardous waste sites.
Documentation of the demonstration consists of two reports: (1) a Technology Evaluation Report, which
describes field activities and laboratory results, and (2) this Applications Analysis Report, which interprets the
demonstration data and discusses the technology's potential applicability.
A limited number of copies of this report will be available at no charge from the EPA Center for
Environmental Research Information, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268. Requests for
this report should include the EPA document number found on the report's cover. When the limited supply is
exhausted, additional copies may be purchased from the National Technical Information Service, Ravensworth
Building, Springfield, Virginia 22161, (703)487-4600. Reference copies will be available at EPA libraries as part
of the Hazardous Waste Collection. To inquire about the availability of other reports, call ORD Publications
in Cincinnati, Ohio, at (513)569-7562.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
in
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Abstract
This report evaluates the Low Temperature Thermal Treatment (LT3®) system's ability to remove volatile
organic compounds (VOC) and semivolatile organic compounds (SVOC) from solid wastes. This evaluation is
based on treatment performance and cost data from the Superfund Innovative Technology Evaluation (SITE)
demonstration and five other case studies.
The LT3* system thermally desorbs organic compounds from contaminated soil without heating the soil to
combustion temperatures. The LT3® system is divided into three treatment areas: soil treatment, emissions
control, and condensate treatment. End products include treated soil, fabric filter dust, treated condensate, and
treated stack gas. The transportable system is comprised of equipment assembled on three flat-bed trailers.
1
The LT3® system demonstration was conducted under the SITE program at the Anderson Development
Company (ADC) site in Adrian, Michigan. During the demonstration, the LT3® system treated lagoon sludge
from the site contaminated with VOCs and SVOCs, primarily 4,4' -methylenebis(2-chloroaniline) (MBOCA).
During the development of the LT3® system, Weston conducted bench- and pilot-scale tests and collected
treatability data for the following wastes: coal tar, drill cuttings (oil-based mud), leaded and unleaded gasoline,
No. 2 diesel fuel, JP4 jet fuel, petroleum hydrocarbons, halogenated and nonhalogenated solvents, VOCs, SVOCs,
and polynuclear aromatic hydrocarbons (PAH).
Based on the results of the SITE demonstration and other case studies, the following conclusions can be
drawn: (1) the LT3® system can process a wide variety of soils with differing moisture and contaminant
concentrations; (2) The LT3® system removes VOCs to below detection limits; (3) The LT3® system generally
decreases SVOC concentrations, but some SVOC concentrations may increase, most likely due to chemical
transformations during heating; (4) under certain conditions, dioxins and furans maybe formed during treatment
in the LT3* system and maybe distributed in process residuals; and (5) remediation costs, including all activities
from site preparation through demobilization, may range from $373 to $725 per ton of soil, depending on soil
moisture content and regulatory requirements.
The report also discusses the applicability of the LT3® system based on compliance with regulatory
requirements, implementability, short-term impact, and long-term effectiveness. In addition, the factors
influencing the technology's performance in meeting these criteria are discussed.
IV
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Contents
Notice ii
Foreword iii
Abstract iv
Acronyms, Abbreviations, and Symbols viii
Conversion Factors x
Acknowledgements xi
1. Executive Summary 1
1.1 Conclusions 1
1.2 Results 2
2. Project Background . 5
2.1 Purpose, History, and Goals of the SITE Program 5
2.2 Documentation of the SITE Demonstration Reports 5
2.2.1 Technology Evaluation Report 6
2.2.2 Applications Analysis Report 6
2.3 Technology Description 6
2.3.1 Principal Treatment Operations 6
2.3.2 Innovative Features of the UT3® Technology 7
2.3.3 LT3® Technology Limitations 7
2.4 Key Contacts 7
3. Technology Applications Analysis 11
3.1 Treatment Effectiveness for Toxicity Reduction 11
3.1.1 VOC Removal 11
3.1.2 SVOC Removal . 13
3.1.3 Formation of Thermal Transformation By-Products 14
3.1.4 Stack Emissions : . 14
3.2 Compliance with Regulatory Requirements 15
3.2.1 Comprehensive Environmental Response, Compensation, and Liability Act ... 15
3.2.2 Resource Conservation and Recovery Act 15
3.2.3 Clean Air Act 16
3.2.4 Occupational Safety and Health Administration 16
3.3 Implementability 16
3.3.1 Mobilization 16
3.3.2 Operations and Maintenance Requirements 17
3.3.3 Reliability 18
3.3.4 Personnel Requirements 19
3.3.5 Demobilization 19
3.4 Short-Term Impact 19
3.4.1 Worker Safety 19
3.4.2 Potential Community Exposures 20
3.5 Long-Term Effectiveness 20
3.5.1 Permanence of Treatment 20
3.5.2 Residuals Handling 20
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3.6 Factors Influencing Performance 21
3.6.1 Size of the Waste Feed 21
3.6.2 Moisture Content of the Waste Feed 21
3.6.3 Particle Size Distribution of the Waste Feed 21
3.6.4 pH of the Waste Feed 21
3.6.5 Contaminated Sludge Flow Rate 22
3.6.6 Heating Fluid Temperature 22
3.6.7 Climatic Conditions 22
4. Economic Analysis 23
4.1 Site-Specific Factors Affecting Costs 23
4.2 Basis of Economic Analysis 23
4.2.1 Assumptions about the LT3® Technology and Capital Costs 23
4.2.2 Assumptions about the Soil and Site Conditions 23
4.2.3 Assumptions about LT3® System Operation 26
4.3 Cost Categories 26
4.3.1 Site Preparation Costs 26
4.3.2 Permitting and Regulatory Costs 27
4.3.3 Equipment Costs 27
4.3.4 Startup Costs 28
4.3.5 Labor Costs 28
4.3.6 Consumable Material Costs 28
4.3.7 Utility Costs 29
4.3.8 Effluent Monitoring Costs 29
4.3.9 Residual Waste Shipping, Handling, and Transportation Costs 29
4.3.10 Analytical Costs 29
4.3.11 Equipment Repair and Replacement Costs 30
4.3.12 Site Demobilization Costs 30
References 30
Appendix A - Developer's Claims 31
A.I Introduction 31
A.2 Potential Application 31
A.3 System Advantages 31
A.4 System Limitations 32
A.5 Costs 32
Appendix B - SITE Demonstration Results 33
B.I Introduction 33
B.2 Site Description 33
B.3 Contaminant Characteristics 33
B.4 Technology Demonstration Testing and Sampling Procedures 34
B.5 Treatment Results 34
B.5.1 VOC Removal 35
B.5.2 MBOCA Removal 35
B.5.3 SVOC Removal ! . ! 36
B.5.4 The Fate of Chloride in the LT3® System 37
B.5.5 The Formation and Distribution of Dioxins and Furans 37
B.5.6 The Fate of Metals in the LT3® System 39
B.5.7 Stack Emissions 39
B.5.8 Physical Properties of Sludge 40
B.5.9 Toxicological Properties of Sludge 41
References 42
Appendix C - Case Studies 45
VI
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Figures
2-1 LT3® System Block Flow Diagram . 7
2-2 LT3® System Layout 8
2-3 Internal View of Thermal Processor 9
B-l MBOCA Concentrations in Untreated and Treated Sludge 37
B-2 AC-MBOCA Concentrations in Untreated and Treated Sludge 38
B-3 3- and 4-Methylphenol Concentrations in Untreated and Treated Sludge 39
B-4 Phenol Concentrations in Untreated and Treated Sludge . ; 40
B-5 BOX Concentrations in Untreated and Treated Sludge and in Fabric Filter Dust 41
B-6 Chloride Concentrations in Untreated and Treated Sludge and Fabric Filter Dust 42
Tables
3-1 Treatment Conditions of the SITE Demonstration and Other Case Studies 12
4-1 Cost Analysis for Operating the LT3® System 24
B-l LT3® System Operating Conditions During SITE Demonstration 35
B-2 Arithmetic Mean Concentrations of CDDs and CDFs 43
B-3 Liquid Condensate Concentrations (ppt) Averaged by Run . . 44
C-l Results of Full-Scale Cleanup of No.2 Fuel Oil and Gasoline-Contaminated Soil 47
C-2 Results of Pilot-Scale Demonstration on VOC-Contarainated Soil 49
C-3 Results of Engineering Technology Laboratory 50
C-4 • Results of Bench-Scale LT3® Test on Coal Tar-Contaminated Soil 51
C-5 Results of Bench-Scale LT3® Testing on Petroleum Hydrocarbon-Contaminated Soil 52
C-6 Results of Bench-Scale LT3® Testing on Chlorinated Benzene-Contaminated Soil 53
vu
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Acronyms, Abbreviations, and Symbols
/xm
AC-MBOCA
ADC
AFB
ARAR
ASTM
BTEX
Btu
CAA
Canonic
CBR
CCJM
CDD
CDF
CEM
CERCLA
cm
CO
CO2
DAC-MBOCA
DOD
ORE
EA
BOX
EPA
fpm
FS
GC/MS
g
gpm
gr/dscm
HC1
hr
kWh
Ib/hr
LC50
LT3®
LDR
MBOCA
m2/g
mg/kg
mg/L
mg/m3
Micrograms per kilogram
Micrograms per liter
Micron
N-acetyl-MBOCA
Anderson Development Company
Air Force Base
Applicable or relevant and appropriate requirement
American Society of Testing and Materials
Benzene, toluene, ethylbenzene, and xylenes
British thermal units
Clean Air Act
Canonie Environmental Services Corporation
California bearing ratio
C.C. Johnson & Malhotra
Polychlorinated dibenzo(p)dioxins
Polychlorinated dibenzofurans
Continuous emissions monitoring
Comprehensive Environmental Response, Compensation, and Liability Act
Centimeters
Carbon monoxide
Carbon dioxide
N,N' -diacetyl-MBOCA
Department of Defense
Destruction and removal efficiency
Endangerment assessment
Extractable organic halide
U.S. Environmental Protection Agency
Feet per minute
Feasibility study
Gas chromatography/Mass spectroscopy
Gram
Gallons per minute
Grains per dry standard cubic meter
Hydrogen chloride
hour
Kilowatt-hour
Pounds per hour
Median lethal concentration
Low temperature thermal treatment
Land Disposal Restrictions
4,4'-Methylenebis (2-chloroaniline)
Square meters per gram
Milligrams per kilogram
Milligrams per liter
Milligrams per cubic meter
vui
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mg/dscm Milligrams per dry standard cubic meter
ND Nondetectable
ng/dscm Nanogram per dry standard cubic meter
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
O2 Oxygen
O&M Operation and maintenance
OCDD Octachloro dibenzo(p)dioxin
ORD Office of Research and Development
OSHA Occupational Safety and Health Administration
OSWER Office of Solid Waste and Emergency Response
PAH Polynuclear aromatic hydrocarbon
PCE Tetrachloroethene
ppb Parts per billion
ppbv Parts per billion by volume
PPE Personal protection equipment
ppm Parts per million
ppmv Parts per million by volume
ppt Parts per trillion
psi Pounds per square inch
QA Quality assurance
QC Quality control
RCRA Resource Conservation and Recovery Act
ROD Record of Decision
RH Relative humidity
rpm Revolutions per minute
RREL Risk Reduction Engineering Laboratory
RI Remedial investigation
SITE Superfund Innovative Technology Evaluation
SARA Superfund Amendments and Reauthorization Act
START Superfund Technical Assistance Response Team
SVOC Semivolatile organic compounds
TCE Trichloroethene
TCDD Tetrachloro dibenzo(p)dioxin
TCLP Toxicity characteristic leaching procedure
THC Total hydrocarbon concentration
TNMHC Total nonmethane hydrocarbon concentration
TOX Total organic halides
TOC Total organic carbon
tons/hr Tons per hour
USATHAMA U.S. Army Toxic and Hazardous Materials Agency
UST Underground Storage Tank
VOC Volatile organic compounds
WESTON Roy F. Weston, Inc.
IX
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r
Conversion Factors
Length:
Area:
English
1 inch (in)
1 foot (ft)
1 mile (mi)
1 square foot (ft2)
Volume: 1 gallon (gal)
1 cubic foot (ft3)
Mass: 1 grain (gr)
1 pound (Ib)
1 ton (t)
Pressure: 1 pound per square inch (psi)
x
x
x
x
X
X
X
X
Factor
2.54
0.305
1.61
0.0929
3.78
0.0283
64.8
0.454
907
0.0703
Metric
centimeter (cm)
meter (m)
kilometer (km)
square meter (m2)
liter (L)
cubic meter (m3)
milligram (mg)
kilogram (kg)
kilogram (kg)
kilogram per square
centimeter (kg/cm2)
Energy. 1 British Thermal Unit (Btu)
1 kilowatt hours (kWh)
x
x
1.05
3.60
kilojoule (kJ)
megajoule (MJ)
Temperature: ("Fahrenheit - 32)
0.556
"Celsius
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Acknowledgements
This report was prepared under the direction and coordination of Mr. Paul R. dePercin, U.S. Environmental
Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Project Manager at the Risk
Reduction Engineering Laboratory (RREL) in Cincinnati, Ohio. Mr. Mark Meckes of the RREL Superfund
Technical Assistance Response Team (START) provided invaluable technical guidance and support throughout
the project. The efforts of Mr. James Hahnenberg of EPA Region 5, Mr. James Huerta and Ms. Denise Muck
of Anderson Development Company, and Mr. Michael Cosmos and Mr. Michael lanni of Roy F. Weston, Inc.,
were essential to the project's success.
This report was prepared for the EPA SITE Program by Mr. Robert Foster, Dr. Chriso Petropoulou, Mr.
David Berestka, Mr. Jeffrey Swano, Mr. Tim Oliver, Ms. LouAnn Unger, Ms. Tammara Muhic, Mr. Michael
Johnson, and Ms. Carol Adams of PRC Environmental Management, Inc. (PRC). Technical input was provided
by Ms; Suzanne Smidt of Versar, Inc.; Mr. Mike Steele of Radian Corporation; and Mr. Alan Todruss of
Construction Technology Laboratories. The report was edited by Ms. Regina Bergner and Ms. Shelley Fu of
PRC. Peer reviewers were Ms. Michelle Simon, Mr. Richard G. Eilers, and Mr. Mark Meckes of RREL.
XI
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Section 1
Executive Summary
This report summarizes the findings of an evaluation for
the Low Temperature Thermal Treatment (LT3®) system
(U.S. Patent No. 4,738,206 and 5,076,674) developed by Roy
F. Weston, Inc. (Weston). This study was conducted under
the U.S. Environmental Protection Agency (EPA) Superfund
Innovative Technology Evaluation (SITE) program. A series
of demonstration tests of the technology were performed by
EPA as part of this program. The demonstration tests were
conducted in November and December 1991, at the
Anderson Development Company (ADC) Superfund site in
Adrian, Michigan. The evaluation of the LT3® system was
based on the results of the SITE demonstration, subsequent
remediation of the ADC Superfund site, and five other case
studies performed by Weston for several private and
governmental clients.
The LT3® system thermally desorbs organic compounds
from contaminated soil without heating the soil to
combustion temperatures. The LT3® system is divided into
three treatment areas: soil treatment, emissions control, and
water treatment. End products include treated soil, fabric
filter dust, treated condensate, and treated stack gas. The
transportable system can be assembled on three flat-bed
trailers.
1.1 Conclusions
Based on the SITE demonstration and other case
studies, the following conclusions may be drawn for the
applicability of the LT3® system:
• The LT3® system can process a wide variety of soils
with differing moisture and contaminant
concentrations. Bench-, pilot-, or full-scale LT3®
systems have been used to effectively treat soil
contaminated with the following wastes: volatile
organic compounds (VOC), semivolatile organic
compounds (SVOC), coal tar, drill cuttings (oil-
based mud), No. 2 diesel fuel, JP4 jet fuel, leaded
and unleaded gasoline, petroleum hydrocarbons,
halogenated and nonhalogenated solvents, and
polynuclear aromatic hydrocarbons (PAH).
• Contaminant removal mechanisms in the LT3®
system include thermal transformation and thermal
desorption. The LT3® system desorbs and
permanently removes VOCs and certain SVOCs
from contaminated soil and sludge. Contaminant
removal efficiency varies with analyte. In general,
VOC removal efficiencies are greater than SVOC
removal efficiencies. Also, among SVOCs,
compounds with lower boiling points are removed
more effectively than compounds with higher boiling
points.
• The LT3® system is most appropriate for wastes
with a moisture content of about 20 percent. Water
can be added to dry wastes to control excessive
dusting. To enhance the efficiency of the LT3®
system, wastes with free liquids or with a moisture
content of greater than 50 percent must be
dewatered. Sludge dewatering affects site
preparation costs significantly. In addition, chemical
additives used as sludge conditioning agents may
affect chemical reactions in the system.
• Screening or crushing oversized material (greater
than 2 inches in size) or clay shredding may be
required for some applications.
• Treatment residuals are not destroyed on site and
require off-site treatment. Two types of residuals
are generated from the LT3® system: (1) liquid
condensate and (2) fabric filter dust. The long-term
effectiveness of the LT3® system ultimately depends
on the methods used to treat or dispose of these
residuals.
• The concentration of contaminants in fabric filter
dust is significantly higher than the concentration of
contaminants in the treated material. These results
indicate that contaminants adsorbed on smaller size
particles are not effectively desorbed during
treatment.
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• Dry, warm weather conditions are ideal for
operating the LT3® system. However, the SITE
demonstration was conducted hi subfreezing
temperatures, and remedial activities at the site
were conducted hi subfreezing or wet weather
conditions. Cold and wet weather caused only
minor operational problems.
• The economic analysis of the LT3® system's
performance compared the costs associated with
treating soils containing 20, 45, and 75 percent
moisture; the treatment cost per ton of treated
material was estimated to be $373, $537, and $725,
respectively. Waste-related factors affecting costs
include waste volume, waste type, soil moisture
content, treatment goals, and regulatory permit
requirements. Site-specific features affecting costs
Include site area, accessibility, availability of utilities,
and geographic location. Also, the characteristics of
the residual waste affect disposal costs.
• Several operational problems with the LT3® system
were observed during shakedown and startup
operations, during the SITE demonstration, and
during routine remedial activities at the ADC site.
Operational problems resulted from mechanical
difficulties with the screws, an inadequately sized
oil-water separator, oversized debris hi the feed
material, leaking sweep ah- gas, excess dust
generation from reprocessed material, and leaking
pipes in the heat transfer fluid system. All
problems were corrected over the course of the
remediation.
• Treatability studies are highly recommended before
large-scale applications of the technology are
considered. Because results may vary greatly with
different solid matrices and waste characteristics,
the LT3® system's performance is best predicted
with preliminary bench-scale testing.
1.2 Results
This section summarizes the results of the LT3® system's
performance during the SITE demonstration and during five
other case studies. A full-scale LT3® system was
demonstrated at the ADC site. A major advantage of
demonstrating a full-scale system is that the results achieved
are more likely to be duplicated by other systems at similar
sites, especially compared to results from, smaller, pilot-scale
or prototype units. Also, the nature of operational problems
encountered during the demonstration should be indicative
of problems at other sites.
The LT3* system SITE demonstration was conducted as
part of a proof-of-process test for full-scale remediation of
the ADC lagoon sludge. The ADC lagoon sludge was
contaminated with VOCs, and SVOCs, primarily
4,4'-methylenebis(2-chloroaniline) (MBOCA). Six 6-hour
replicate tests were conducted during the demonstration.
During the tests, contaminated sludge was heated to above
500 °F for a residence tune of 90 minutes. Sludge was
processed at a rate of 2.1 tons per hour (tons/hr); a total of
80 tons of contaminated sludge was treated during the six
SITE demonstration tests. Key findings from the SITE
demonstration include the following:
• The LT3® system removed most VOCs to below
method detection limits [less than 60 micrograms
per kilogram (/*g/kg) for most compounds]. VOC
concentrations in untreated sludge ranged from 35
to 25,000 jig/kg.
• The LT3® system achieved MBOCA removal
efficiencies ranging from 79.82 to 99.34 percent.
MBOCA concentrations hi untreated sludge ranged
from 43.6 to 860 milligrams per kilogram (mg/kg).
MBOCA concentration hi the treated sludge ranged
from 3 to 9.6 mg/kg.
• The LT3® system decreased the concentration of all
SVOCs initially present hi the sludge with two
exceptions. First, phenol concentrations increased
after treatment, probably because of chemical
transformations during heating. Second, a minor
leak of heat transfer fluid, which contains
triphenylene, probably resulted hi the measured
concentrations of chrysene hi the treated material;
chrysene and triphenylene are indistinguishable
under the analytical method used during the
demonstration.
• Polychlorinated dibenzo(p)dioxins (CDD) and
polychlorinated dibenzofurans (CDF) were formed
in the LT3® system and distributed hi treated sludge,
fabric filter dust, exhaust gas, and liquid condensate.
CDD and CDF concentrations hi untreated liquid
condensate increased with successive test runs. The
condensate was treated through a liquid-phase
carbon adsorption system before being sent off site
for disposal. A vapor-phase carbon column
removed CDDs and CDFs from the exhaust gas;
removal efficiencies varied with congener, from 20
to 100 percent.
• The total nonmethane hydrocarbon concentration
(TNMHC) hi stack emissions from the LT3® system
increased consistently. During the first test run,
TNMHC was 6.7 part per million by volume
(ppmv); during the second test run TNMHC was 7.6
ppmv; and during the third run TNMHC was 11
ppmv. The particulate concentration hi the stack
gas ranged from less than 8.5X10"4 to 6.7xlO"3 grains
per dry standard cubic meter (gr/dscm), and the
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participate emissions ranged from less than
to 9.2X10"4 pounds per hour (Ib/hr). Chloride
concentrations were below the method detection
limit, which had an average value of
2.8xlO'2 milligrams per dry standard cubic meter
(mg/dscm). Chloride emissions were less than
6.0xlO's Ib/hr.
The five case studies evaluated included two full-scale
applications for fuel contaminated sites, a pilot-scale study,
and bench-scale studies at Weston's laboratory and at a
private client's site. Key findings from other case studies
include the following:
• Full-scale remedial activities using the LT3® system
were conducted at a confidential site in Springfield,
Illinois. About 1,000 cubic yards of soil
contaminated with No. 2 fuel oil and gasoline was
successfully treated at 350 °F for a 70-minute
residence tune.
• The U.S. Army Toxic and Hazardous Materials
Agency (USATHAMA) selected Tinker Air Force
Base (Tinker AFB) in Oklahoma City, Oklahoma,
for the demonstration of a full-scale LT3® system.
About 3,000 cubic yards of soil contaminated with
trichloroethene (TCE), chlorobenzene, and JP4 jet
fuel were treated during the demonstration. The
LT3® system reduced the concentrations of all target
contaminants to below cleanup levels.
A pilot-scale test of the LT3® system was conducted
for USATHAMA at the Letterkenny Army Depot
in Chambersburg, Pennsylvania. More than 7.5 tons
of soil contaminated with TCE, dichloroethene,
tetrachloroethene (PCE), and xylene were treated at
320 °F for a residence time of 60 minutes. The
LT3® system achieved removal efficiencies greater
than 99.99 percent.
Weston has conducted several studies using a
bench-scale LT3® system at its Environmental
Technology Laboratory in Lionville, Pennsylvania.
Soils contaminated with VOCs, coal tar, and PAH
were treated at temperatures varying from 250 to
450 °F and residence times ranging from 30 to 45
minutes. In general, target VOCs were removed to
below detection limits and PAH removal efficiencies
were greater than 93 percent.
Weston also conducted bench-scale studies for a
confidential client in Colorado on soil contaminated
with chlorinated benzene. Soil was treated at 400
°F for a residence time of 44 minutes, achieving
removal efficiencies greater than 99.9 percent.
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Section 2
Project Background
This section provides background information on the
SITE program, discusses the purpose of this applications
analysis report, and describes the LT3® system developed by
Weston. The LT3® system was demonstrated under the
SITE program at the ADC Superfund site in Adrian,
Michigan. For additional information about the SITE
program, this technology, and the demonstration site, key
contacts are listed at the end of this section.
2.1 Purpose, History, and Goals of the SITE
Program
The SITE program is a unique, international effort
dedicated to advancing the development, evaluation, and
implementation of innovative treatment technologies
applicable to hazardous waste sites. The SITE program was
established in response to the 1986 Superfund Amendments
and Reauthorization Act (SARA), which recognized a need
for an alternative or innovative treatment technology
research and development program. The SITE program is
administered by the EPA Office of Research and
Development (ORD) Risk Reduction Engineering
Laboratory (RREL).
The SITE program consists of four component
programs: (1) the Demonstration Program, (2) the
Emerging Technology Program, (3) the Monitoring and
Measurement Technologies Program, and (4) the
Technology Transfer Program. This document was produced
as part of the SITE Demonstration Program. The objective
of the Demonstration Program is to provide reliable
performance and cost data on innovative technologies so that
potential users can assess a technology's suitability for
specific site cleanups. To produce useful and reliable data,
demonstrations are conducted at hazardous waste sites or
under conditions that closely simulate actual wastes and site
conditions.
Data collected during a demonstration are used to assess
the performance of the technology, the potential need for
pretreatment and posttreatment processing of the waste,
applicable types of waste and media, potential operating
problems, and approximate capital and operating costs.
Demonstration data can also provide insight into a
technology's long-term operating and maintenance (O&M)
costs and long-term application risks.
Technologies are selected for the SITE Demonstration
Program primarily through annual requests for proposals.
Proposals are reviewed by ORD staff to determine which
technologies have the most promise for use at hazardous
waste sites. To be eligible, technologies must be developed
to the pilot- or full-scale stage, must be innovative, and must
offer some advantage over existing technologies. Mobile
technologies are of particular interest.
Cooperative agreements between EPA and the developer
determine responsibilities for conducting the demonstration
and evaluating the technology. The developer is responsible
for demonstrating the technology at the selected site and is
expected to pay the costs to transport, operate, and remove
its equipment. EPA is responsible for project planning,
sampling and analysis, quality assurance (QA), quality
control (QC), preparing reports, and disseminating
information.
Each SITE demonstration evaluates the performance of
a technology in treating a particular waste at the
demonstration site. To obtain data with broad applications,
EPA and the technology developer try to choose a waste
frequently found at other contaminated sites. In many cases,
however, waste characteristics at other sites will differ in
some way from the waste tested. Thus, a successful
demonstration of the technology at one site does not ensure
that it will work equally well at other sites. Data obtained
from the SITE demonstration may have to be extrapolated
and combined with other information about the technology
to estimate the operating range and limits of the technology.
2.2 Documentation of the SITE Demonstration
Reports
The results of each SITE demonstration are presented
in two documents, each with a distinct purpose: (1) the
Technology Evaluation Report and (2) the Applications
Analysis Report. These documents are described below.
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2.2.1 Technology Evaluation Report
The Technology Evaluation Report provides a
comprehensive description of the SITE demonstration and
its results. It is intended for engineers making a detailed
evaluation of the technology's performance for the
demonstration site and waste situation. These technical
evaluators seek to understand, in detail, the performance of
the technology during the demonstration and the advantages,
risks, and costs of the technology for a specific application.
The report also provides a detailed discussion of QA and
QC measures during the demonstration.
2.2.2 Applications Analysis Report
To encourage wider use of technologies demonstrated
under the SITE program, the Applications Analysis Report
provides information on a technology's costs and its
applicability to other sites and wastes. Prior to a SITE
demonstration, the amount of data available for an
innovative technology may vary widely. Data may range
from limited laboratory tests on synthetic wastes to
performance data on actual wastes treated in pilot- or full-
scale treatment systems. The Applications Analysis Report
synthesizes available information on the technology and
draws reasonable conclusions about its broad-range
applicability. This report is intended for those who are
considering a technology for hazardous site cleanups; it
represents a critical step in the development and
commercialization of a treatment technology.
The principal use of the Applications Analysis Report is
to assist in determining whether a technology should be
considered further as an option for a particular cleanup
situation. The Applications Analysis Report is intended for
decision makers responsible for implementing remedial
actions. The report discusses advantages, disadvantages, and
limitations of the technology. Costs for different applications
may be estimated using 12 cost categories that are based on
available data from pilot- and full-scale applications. The
report also discusses specific factors, such as site and waste
characteristics, that may affect performance and cost.
2.3 Technology Description
The LT3* system thermally desorbs organic compounds
from contaminated soil without heating the soil to
combustion temperatures. The full-scale transportable
system can be assembled on three flat-bed trailers. With
ancillary and support equipment, the system requires an area
of about 5,000 square feet.
2.3.1 Principal Treatment Operations
The LT3® system consists of three main treatment areas:
soil treatment, emissions control, and condensate treatment.
A block flow diagram of the system (see Figure 2-1) is
described below.
Soil is treated in the LT3® thermal processor. The
thermal processor consists of two jacketed troughs, one
above the other. Each trough houses four intermeshed,
hollow-screw conveyors. A front-end loader transports feed
soil (or sludge) to a weigh scale before depositing the
material onto a feed conveyor. The feed conveyor
discharges the soil into a surge hopper located above the
thermal processor. The surge hopper is equipped with level
sensors and provides a seal over the thermal processor to
minimize air infiltration and contaminant loss. The
conveyors move soil across the upper trough of the thermal
processor until the soil drops to the lower trough. The soil
then travels across the processor and exits at the same end
that it entered. Hot oil circulates through the hollow screws
and trough jackets and acts as a heat transfer fluid. During
treatment in the processor, each hollow-screw conveyor
mixes, transports, and heats the contaminated soil. The
thermal processor discharges treated soil into a conditioner,
where it is sprayed with water to cool it and to minimize
fugitive dust emissions. An inclined belt conveys treated soil
to a truck or pile.
A burner heats the circulating oil to an operating
temperature of 400 to 650 °F (about 100 °F higher than the
desired soil treatment temperature). Combustion gases
released from the burner are used as sweep gas in the
thermal processor. A fan draws sweep gas and desorbed
organics from the thermal processor into a fabric filter.
Dust collected on the fabric filter may be retreated or
drummed for off-site disposal. Exhaust gas from the fabric
filter is drawn into an air-cooled condenser to remove most
of the water vapor and organics. Exhaust gas is then drawn
through a second, refrigerated condenser, which lowers the
temperature further and reduces the moisture and organic
content of the off-gases. Electric resistance heaters then
raise the off-gas temperature back to 70 °F. This
temperature optimizes the performance of the vapor-phase,
activated carbon column, which is used to remove any
remaining organics. At some sites, caustic scrubbers and
afterburners have been employed as part of the air pollution
control system, but they were not used at the ADC site.
Condensate streams from the air-coded and refrigerated
condensers are typically treated in a three-phase, oil-water
separator. The oil-water separator removes light and heavy
organic phases from the water phase. The aqueous portion
is then treated in the carbon adsorption system to remove
any residual organic contaminants; after separation and
treatment, the aqueous portion is often used for soil
conditioning. The organic phases are disposed of off site.
When processing extremely wet materials like sludge, the oil-
water separation step may not be appropriate due to the
high volume of condensate generated. In such cases,
aqueous streams from the first and second condensers may
-------
To atmosphere
Oversized
material or
wastewater
Hot oil burner off-gases
Fuel/combustion air
Key
— Solids Flow
Aqueous Flow
Vapor Flow
V
To atmosphere
To off-site
disposal
To discharge
or off-site
disposal
Figure 2-1 LT3® System Block Flow Diagram
be pumped through a disposable filter to remove particulate
matter prior to carbon adsorption treatment and off-site
disposal.
2.3.2 Innovative Features of the LT3® Technology
The LT3® system is a U.S.-patented process for the
treatment of organic contaminants in soils and sludges.
Figure 2-2 presents a general layout of the process
equipment. The most innovative feature of the system is the
use of hollow-screw augers for mixing, conveying, and
indirectly heating the feed material. Figure 2-3 presents an
internal view of the screw augers. The system's other
process treatment units, including the residuals treatment
units, are not unique.
2.3.3 LT3® Technology Limitations
Weston reports that the LT3® system can process a wide
variety of soils with differing moisture and contaminant
concentrations. The developer reports that the technology
is best suited for soils with a moisture content of less than 20
percent and VOC concentrations of up to 1 percent. SVOCs
with boiling points greater than 500 °F can also be treated,
but treatment must be evaluated based on cleanup
objectives. Wastes with a moisture content between 20 and
50 percent can be treated at a reduced capacity basis.
Wastes with a moisture content greater than 50 percent need
to be dewatered to enable treatment in the LT3® system.
Pretreatment screening or crushing of oversized material
(greater than 2 inches in size) or clay shredding may also be
required for some applications.
2.4 Key Contacts
Additional information on the LT3® technology, the
SITE program, and the ADC site can be obtained from the
following sources:
1. Vendor concerning the LT3® technology:
Mr. Michael Cosmos
Roy F. Weston, Inc.
1 Weston Way
West Chester, Pennsylvania 19380
(215) 430-7423
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THERMAL PROCESSOR
DRIVE UNITS
VENT _/
CONDENSER
LIQUID-PHASE
CARBON COLUMNS
LIQUID
CONDENSATE
TANK
DISPOSABLE
FILTERS
REFRIGERATION
UNIT
ORGANIC
COLLECTION
DRUM
OIL-WATER
SEPARATOR
VAPOR-PHASE
CARBON
COLUMN
NOTE: LOCATIONS ARE APPROXIMATE; SOME ANCILLARY EQUIPMENT NOT SHOWN.
Ftgura 2-2 LT*° System Layout
2. The EPA Project Manager concerning the SITE
Demonstration:
Mr. Paul R. dePercin
U.S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
(513) 569-7797
3. Concerning the ADC Site:
Mr. James Hahnenberg
U.S. Environmental Protection Agency
Region 5, Remedial Response Branch
77 W. Jackson Boulevard
Chicago, Illinois 60604
(312) 353-4213
Mr. James Huerta
Anderson Development Company
1415 E. Michigan Street
Adrian, Michagan 49221
(517) 263-2121
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Figure 2-3 Internal View of Thermal Processor
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Section 3
Technology Applications Analysis
This section addresses the applicability of the LT3®
system to treat soils contaminated with VOCs and SVOCs.
Weston's claims regarding the applicability and performance
of the LT3® system are included in Appendix A.
The applicability of the LT3® system was evaluated hi
terms of technical criteria used to select remedial actions at
Superfund sites. These criteria, which can also be applied to
Resource Conservation and Recovery Act (RCRA),
underground storage tank (UST), or other corrective action
decisions, include the following: (1) treatment effectiveness
for toxicity reduction, (2) compliance with regulatory
requirements, (3) implementability, (4) short-term impact,
and (5) long-term effectiveness. These criteria are discussed
below. In addition, factors influencing the technology's
performance in meeting these criteria are discussed at the
end of this section.
The evaluation presented below is based on results of
the LT3® system SITE demonstration, subsequent
remediation of the ADC lagoon sludge (see Appendix B),
and five other case studies (see Appendix C). The treatment
conditions of the SITE demonstration and subsequent
remediation of the ADC site, as well as the other case
studies are summarized in Table 3-1. The results indicate
that the LT3® system can process a wide variety of soils with
differing moisture and contaminant concentrations. The
LT3® system can effectively treat soil and sludge
contaminated with the following wastes: VOCs, SVOCs,
coal tar, drill cuttings (oil-based mud), No. 2 diesel fuel, JP4
jet fuel, leaded and unleaded gasoline, petroleum
hydrocarbons, halogenated and nonhalogenated solvents, and
PAHs.
Although an extensive data base has been generated on
the LT3® system's effectiveness in treating various waste
types under differing operating conditions, results may vary
greatly with different solid matrices and waste characteristics.
Therefore, the technology's performance is best predicted
with some preliminary bench-scale testing. Contaminants
may also behave differently in association with other
compounds and with differing soil types, making preliminary
testing very important in determining the technology's
applicability to meet treatment objectives. Treatability
studies are recommended before considering large-scale
applications of the technology. Testing prior to mobilizing
the full-scale system may eliminate problems associated with
applying the system to compounds and soils for which it is
not suited. Preliminary treatability studies may also be able
to approximate process rates and cleanup capabilities,
allowing an assessment of the LT3® system's applicability for
a specific site.
3.1 Treatment Effectiveness for Toxicity
Reduction
The LT3® system's effectiveness for toxicity reduction
was evaluated based on the following criteria: (1) VOC
removal, (2) SVOC removal, (3) formation of thermal
transformation by-products, and (4) stack emissions. These
criteria are discussed below.
3.1.1 VOC Removal
The LT3® system removes most VOCs present in
untreated soil to below method detection limits. Specific
compounds treated to date include benzene, toluene,
ethylbenzene, and xylenes (BTEX); TCE; and PCE.
Removal efficiencies ranged from 96 to greater than 99
percent.
Toluene and PCE were identified as critical VOCs for
the LT3® technology SITE demonstration. Toluene was
present in untreated sludge at concentrations ranging from
1,000 to 25,000 jttg/kg. The concentration of toluene hi
treated sludge was below the detection limit of 30 /ig/kg.
The concentration of toluene in fabric filter dust ranged
from less than 28 to 410 /ig/kg. For most samples analyzed,
the concentration of toluene in the condensate was below the
detection limit of 5 milligrams per liter (mg/L). However,
toluene was detected in the off-gas before the carbon column
at concentrations ranging between 8,000 and 10,000 parts per
billion by volume (ppbv). Toluene was effectively removed
by the vapor-phase activated carbon column.
11
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Table 3-1 Treatment Conditions of the SITE Demonstration and Other Case Studies
Study
SITE
Demon-
stration
Case
Study 1
Case
Study 2
Case
Study 3
Case
Study 4
Scale
Full-
Scale
Full-
Scale
Full-
Scale
Pilot-
Scale
Bench-
Scale
Site
Adrian,
Michigan
Springfield,
Illinois
Tinker AFB,
Oklahoma City,
Oklahoma
Letterkenny
Army Depot,
Chambersburg,
Pennsylvania
Environmental
Technology
Laboratory,
Lionville,
Pennsylvania
Client Treatment
Conditions
ADC Temperature:
500 to 530 °F
Residence
Time: 90 min
Processing
Rate: 2.1
tons/hr
Confidential Temperature:
350 °F
Residence
Time: 70 min
USATHAMA Processing
Rate: 9
tons/hr
USATHAMA Temperature:
320 °F
Residence
Time: 60 min
Various Temperature:
Industrial 250 to 450 °F
and Federal
Clients Residence
Time: 30 to 50
min
Soil
Type
Sludge
and
Clay
NS
Clay
NS
NS
Amount
of Soil
Treated
80a tons
1,000
cubic
yards
3,000
cubic
yards
7 tons
NS
Contaminants
VOCs, SVOCs,
MBOCA
VOCs, SVOCs,
PAHs,
Gasoline,
No. 2 Fuel Oil
VOCs, SVOCs,
Chlorinated
Solvents, JP4
Aviation Fuel
VOCs
VOCs, SVOCs,
PAHs, Coal
Tar,
Petroleum
Hydrocarbons,
Oiland
Case Bench- Colorado
Study 5 Scale Springs,
Colorado
Confidential
Temperature:
400 °F
Residence
Time: 44 min
NS
NS
Grease, VOCs,
SVOCs, PAHs
Chlorinated
Benzene
* - During the SITE demonstration at the ADC site, Weston treated 80 tons of sludge. Through July 1992, over
3,000 tons of sludge were treated during the remediation of the ADC site.
NS - Not Specified
PCE was also present in untreated sludge at
concentrations ranging from 690 to 1,900 fig/kg. The
concentrations of PCE in treated sludge and fabric filter dust
were below the detection limit of 30 jtgAg for most samples
analyzed. The concentration of PCE in the condensate was
below the detection limit of 5 mg/L. PCE was detected in
the off-gas before the carbon unit at concentrations ranging
from 210 to 220 ppbv. PCE was effectively removed by the
vapor-phase activated carbon column.
Results from the first case study (see Table 3-1) also
showed that VOCs were effectively removed from
contaminated soil. VOCs of concern included BTEX.
Concentrations of these VOCs in untreated soil ranged from
1,000 to 110,000 fig/kg. Concentrations of the VOCs in
treated soil ranged from less than 1 to 5.2 jug/kg. Removal
efficiencies greater than 99.48 percent were achieved.
Results from the second case study (see Table 3-1)
showed that TCE, the primary VOC of concern, was
effectively removed. The concentration of TCE in untreated
soil was 6,100 mg/kg. The concentration of TCE in treated
soil was below the cleanup goal for the site.
During the third case study (see Table 3-1), untreated
soil was contaminated with the following VOCs:
dichloroethene, PCE, TCE, and xylene. Concentrations of
VOCs in untreated soil ranged from 586,000 to 27,20J,QCO
/tg/kg. Concentrations of VOCs in the treated soil ranged
from 730 to 1,800 /tg/kg. Removal efficiencies greater than
99.88 percent were achieved.
12
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Results from the fourth case study (see Table 3-1)
showed that soil contaminated with the following VOCs was
treated effectively: methylene chloride; adetone; n-butanol;
1,2-dichloroethane; 1,2-dichloropropane; isoprqpanol;
methanol; and cyclohexane. Concentrations of VOCs in
untreated soil ranged from 120 to 120,000 fig/kg.
Concentration of VOCs in treated soil ranged 340 to less
than 6,000 |*g/kg. Removal efficiencies greater than 98.9
percent were achieved.
In addition, during the fourth case study, soil
contaminated with ethylbenzene and methylene chloride was
effectively treated. The concentration of ethylbenzene before
treatment was 78,000 fig/kg, and the concentration of
methylene chloride was 14,000 Mg/kg. After treatment both
contaminants were reduced to below the detection limit of
5
3.1.2 SVOC Removal
In general, the LT3® system reduces the concentration of
SVOCs. Removal efficiencies ranged from 57 to greater
than 99 percent. Among SVOCs, compounds with lower
boiling points are removed more effectively than compounds
with higher boiling points.
MBOCA, 4-methylphenol, and bis(2-ethylhexyl)-
phthalate were identified as critical analytes for the LT3®
system SITE demonstration. During the SITE
demonstration the LT3® system achieved MBOCA removal
efficiencies ranging from 79.82 to 99.34 percent. MBOCA
concentrations in untreated sludge ranged from 162 to 860
mg/kg. MBOCA concentrations in treated sludge ranged
from 3 to 9.6 mg/kg. MBOCA was detected in the
condensate at concentrations ranging from 100 to
257 micrograms per liter (/tg/L). No MBOCA was detected
in the exhaust gas from the refrigerated condenser. The
decrease in MBOCA concentration after treatment was
accompanied by an increase in the measured concentration
of N-acetyl-MBOCA (AC-MBOCA). AC-MBOCA is a
known metabolite of MBOCA, indicating that the removal
of MBOCA was probably due partially to thermal desorption
and partially to the degradation of MBOCA to the
AC-MBOCA metabolite. However, the presence of co-
eluting compounds may have interfered with the quantitation
of AC-MBOCA. The concentration of N,N'-diacetyl-
MBOCA (DAC-MBOCA), another metabolite of MBOCA,
decreased after treatment in most samples analyzed. The
decrease in DAC-MBOCA concentration was probably due
either to thermal desorption or to conversion to
AC-MBOCA.
The LT3® system also decreased the concentration of
other SVOCs initially present in the sludge. 4-Methylphenol
and bis(2-ethylhexyl)phthalate were identified as critical
analytes for the LT3® system SITE demonstration. The
concentrations of 3- and 4-methylphenol ranged from 3,100
to 20,000 /tg/kg in the untreated sludge. After treatment, 3-
and 4-methylphenol concentrations ranged from 540 to 4,000
/ig/kg, representing removal efficiencies of between 57.0 and
97.4 percent. The concentration of 3- and 4-methylphenol in
fabric filter dust ranged from 1,200 to 5,100 /ig/kg. Liquid
condensate contained 3- and 4-methylphenol at
concentrations ranging from 7,900 to 25,000 /ig/L. However,
no 3- or 4-methylphenol was detected in the exhaust gas
exiting the refrigerated condenser.
Bis(2-ethylhexyl)phthalate was present in untreated
sludge at concentrations ranging from 1,100 to 7,900 /ig/kg.
After treatment, the concentration of bis(2-
ethylhexyl)phthalate was reduced to below the detection
limit, which was less than 820 Mg/kg for most samples. The
concentration of bis(2-ethylhexyl)phthalate in fabric filter
dust ranged from 650 to 3,600 Mg/kg- Because of its high
boiling point (723.2 °F), bis(2-ethylhexyl)phthalate is not
likely to be desorbed during heating in the LT3® system,
because the sludge treatment temperature ranged from only
500 to 530 °F. Therefore, the decreased concentration of
bis(2-ethylhexyl)phthalate was probably due to thermal
decomposition during heating. The decomposition scenario
is supported by the sampling results of the liquid condensate
and the exhaust gas from the refrigerated condenser. The
concentration of bis(2-ethylhexyl)phthalate in the condensate
was below the detection limit of 3,000 /tg/L. Similarly, the
concentration of bis(2-ethylhexyl)phthalate in the exhaust gas
was below the detection limit of 28 ppbv.
Although concentrations of most SVOCs decreased with
treatment, the concentration of the following two SVOCs
increased with treatment: phenol and chrysene. The
increased phenol concentration after treatment is most likely
due to chemical transformations during heating, most likely
the dehalogenation of 1,2-dichlorobenzene, a reaction that
has been reported to take place at elevated temperatures
and alkaline pH conditions (Larock, 1989). The
dehalogenation scenario is supported by other demonstration
results, which also indicate that the extractable organic
halide (BOX) concentration hi sludge is reduced after
treatment, while the concentration of chloride is increased.
During the SITE demonstration, chrysene (or
triphenylene), which was not originally present in the
untreated sludge, was detected in treated sludge and fabric
filter dust. A minor leak of heat transfer fluid, which
contains triphenylene, probably caused the apparent increase
in chrysene concentration. Triphenylene and chrysene
produce indistinguishable responses in the gas
chromatography/mass spectroscopy (GC/MS) analytical
technique used.
During the fifth case study (see Table 3-1), soil
contaminated with SVOCs was also effectively treated. The
total concentration of SVOCs in the soil was 530 mg/kg. Of
that amount, 523 mg/kg was 1,4-dichlorobenzene; the
13
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remaining portion consisted of other SVOCs. The
concentration of 1,4-dichlorobenzene after treatment was
6.25 / representing a removal efficiency of greater than
99.9 percent.
Soils contaminated with PAHs were treated during the
first and fourth case studies. Concentrations of PAHs in
untreated soil ranged from 890 to 580,000 jtg/kg. The
concentration of PAHs in treated soil ranged from less than
330 to 14,000 M?/kg. Removal efficiencies ranged from 62.9
to greater than 99 percent.
3.1.3 Formation of Thermal Transformation By-
Products
Chemical characteristics of contaminants hi the waste
feed determine the types of by-products formed during heat
treatment. Under certain conditions, dioxins and furans may
form in the LT3* system as thermal transformation by-
products. The following specific treatment conditions tend
to encourage the formation of dioxins and furans: (1) the
presence of chemical precursors, (2) alkaline pH, (3) high
concentrations of free chloride, (4) temperatures greater
than 500 °F, and (5) long residence times. For some
applications, such as the SITE demonstration, the LT3®
system will operate under these conditions.
The following groups of compounds are associated with
the formation of dioxins (EPA, 1980):
Class I - Polyhalogenated Phenols
Class II - Ortho-Halophenols and Ortho-Halophenyl
Ethers
Class III- Aromatic Compounds and Ortho-
Substituted Aromatic Compounds
Analytical results of the SITE demonstration showed
that the following potential dioxin precursors were present
in untreated and treated sludge samples: phenol; 1,2-
dichlorobenzene;4-chloroaniline;4,6-dinitro-2-methylphenol;
2,4-dibromophenol; o-chloroaniline; aniline; 2-chlorophenol;
4-bromophenol; and 2,4-dibromophenol. Alkaline pH
resulted from the addition of lime; high concentrations of
free chloride resulted from the addition of ferric chloride.
Both chemicals were added to the sludge prior to LT3®
processing as conditioning agents before sludge dewatering.
Treatment temperatures ranged from 500 to 530 °F.
Polychlorinated dibenzo(p)dioxins (CDD) and
polychlorinated dibenzofurans (CDF) were formed in the
LT3* system and distributed in fabric filter dust, treated
sludge, condensate, and exhaust gas. Fabric filter dust
consistently contained higher concentrations of CDD and
CDF than treated sludge, and the dust was the only solid
matrix containing measurable amounts of 2,3,7,8-tetrachloro
dibenzo(p)dioxin (2,3,7,8-TCDD). The average
concentrations of CDD and CDF in treated sludge ranged
from 0.066 to 2.42 /^g/kg. Octachloro dibenzo(p)dioxin
(OCDD) was the only congener found in one sample of
untreated sludge. OCDD was detected at 0.63 parts per
billion (ppb), near the detection limit of 0.54 ppb. CDD and
CDF concentrations in condensate increased with successive
test runs. The condensate was treated through a liquid-
phase carbon adsorption system before being sent off site for
disposal. The vapor-phase carbon column removed CDDs
and CDFs from the exhaust gas; removal efficiencies varied
with congener, from 20 to 100 percent.
3.1.4 Stack Emissions
Stack gas emitted from the LT3® system generally
contains low concentrations of chloride and particulate
matter. However, the total hydrocarbon concentration
(THC) in the stack gas should be continuously monitored to
determine when the vapor-phase activated carbon unit
should be replaced. Contaminant breakthrough should be
monitored to prevent emissions of VOCs and any thermal
transformation by-products.
During the SITE demonstration and subsequent
remediation at the ADC site, THC was monitored through
a continuous emission monitoring (CEM) system operating
as part of the LT3® system. The CEM system recorded
THC values as high as 100 ppmv. To control emissions,
Weston replaced the vapor-phase carbon adsorption column
regularly.
During the SITE demonstration (see Table 3-1), the
TNMHC in stack gas was determined. TNMHC includes
both VOCs and SVOCs. VOC emissions from the stack
were predominately composed of propylene and
chloromethane. SVOC stack emissions did not contain any
predominant contaminants, and testing indicated that all
compounds were present in concentrations at or below
instrument detection limits. TNMHC hi stack emissions
from the LT3® system increased consistently. During the
first test run, TNMHC was 6.7 ppmv; during the second test
run, TNMHC was 7.6 ppmv; and during the third run
TNMHC was 11 ppmv. Because a new vapor-phase
activated carbon column was used during the SITE
demonstration, the results suggest that breakthrough
occurred after a relatively short period of time.
The particulate concentration in the stack gas ranged
from less than S.SxlO"4 to 6.7xlO"3 gr/dscm, and particulate
emissions ranged from less than 1.2X10"4 to 9.2X10"4 Ib/hr.
Chloride concentrations were below the method detection
limit, which had an average value of 2.8xlO"2 mg/dscm;
chloride emissions were less than 6.0xlO'5 Ib/hr.
During the SITE demonstration and subsequent
remediation at the ADC site, fugitive dust emissions from
the treated sludge pile area were occasionally observed.
Dust levels ranged from 0.16 to 0.99 milligrams per cubic
14
-------
meter (mg/m3) downwind of the treated sludge pile and
inside the control trailer near the treated sludge pile.
Fugitive dust concentrations were higher than the action
level of 0.15 mg/m3.
During the first case study (see Table 3-1), the following
specific air emission limitations were met: (1) carbon
monoxide (CO) less than 100 ppmv, (2) THC less than 100
ppmv, and (3) no visible dust emissions.
During the third case study (see Table 3-1), an
afterburner was used as part of the emissions control system.
No VOCs were detected in the stack, and stack emissions
were in compliance with federal and state regulations for
hydrogen chloride (HC1), CO, and particulates.
3.2 Compliance with Regulatory Requirements
This subsection discusses specific environmental
regulations pertinent to the operation of the LT3® system,
including the transport, treatment, storage, and disposal of
wastes and treatment residuals. Applicable or relevant and
appropriate requirements (ARAR) include the following: (1)
the Comprehensive EnvironmentalResponse, Compensation,
and Liability Act (CERCLA); (2) the Resource Conservation
and Recovery Act (RCRA); (3) the Clean Air Act (CAA);
and (4) the Occupational Safety and Health Administration
(OSHA). These four general ARARs are discussed below;
specific ARARs must be identified for each site.
3.2.1 Comprehensive Environmental Response,
Compensation, and Liability Act
CERCLA, as amended by SARA, provides for federal
authority to respond to releases of hazardous substances,
pollutants, or contaminants to air, water, and land. Section
121 of SARA provides cleanup standards and requires that
selected remedies be cost-effective and protective of human
health and the environment. The federal cleanup standards
of SARA prefer highly reliable remedial actions that provide
long-term protection. Preferred remedial actions
permanently and significantly reduce the volume, toxicity, or
mobility of hazardous substances, pollutants, or
contaminants. The LT3® system permanently reduces the
toxicity of the feed wastes; a substantially reduced volume of
residuals may require additional treatment or long-term
management.
Federal cleanup standards also require that remedies
selected at Superfund sites comply with federal and state
ARARs. ARARs for a remedial action may be waived
under six conditions: (1) the action is an interim measure,
and the ARAR will be met at completion; (2) compliance
with the ARAR would pose a greater risk to health and the
environmental than noncompliance; (3) it is technically
impracticable to meet the ARAR; (4) the standard of
performance of an ARAR can be met by an equivalent
method; (5) a state ARAR has not been consistently applied
elsewhere; and (6) ARAR compliance would not provide a
balance between the protection achieved at a particular site
and demands on the Superfund for other sites. These waiver
options apply only to Superfund actions taken on site, and
justification for the waiver must be clearly demonstrated
(EPA, 1988).
The ADC site was being remediated under CERCLA
authority. Two significant ARARs were considered: state air
pollution regulations and state ground-water protection and
health risk standards. At a Superfund site, only the
substantive requirements of an air pollution discharge permit
must be met through appropriate pollution control. In most
cases, the site manager will obtain a permit for the system.
With the appropriate use of air pollution control equipment,
such as vapor-phase carbon adsorption units to remove
uncondensed toxic organics, the LT3® system can meet state
requirements. The LT3® system cannot, however, meet
ground-water protection standards for metals, because
metals are not removed from soils during treatment.
Pretreatment, posttreatment, or off-site disposal of treated
material at a Subtitle D landfill may be required if the
CERCLA substances are contaminated with metals.
3.2.2 Resource Conservation and Recovery Act
RCRA regulations define hazardous wastes and regulate
thek transport, treatment, storage, and disposal. Wastes
defined as hazardous under RCRA include characteristic and
listed wastes. Criteria for identifying characteristic
hazardous wastes are included in 40 CFR Part 261 Subpart
C. Listed wastes from nonspecific and specific industrial
sources, off-specification products, spill cleanups, and other
industrial sources are itemized in 40 CFR Part 261 Subpart
D.
Residual wastes from the LT3® system include both
liquid and solid wastes that maybe hazardous under RCRA.
Operation of the LT3® system generates the following wastes:
• Fabric filter dust — Contaminants may adsorb on
fine particles, thus precluding retreatment.
• Condensate organics — Organic contaminants are
generally condensed and then prepared for off-site
disposal.
• Condenser water ~ If oil-water separation or other
suitable on-site treatment is not practical, discharge
or off-site disposal may be possible.
• Condenser water filters - Disposable filters contain
solid-phase contaminants.
• Activated carbon — Activated carbon units must be
disposed of as waste if regeneration is not possible.
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• Personal protection equipment (PPE) — Disposable
PPE is generally incinerated or landfilled.
Under both CERCLA and RCRA, treatment residuals
generated by the LT3® system are subject to land disposal
restrictions (LDR). Dioxins and furans may be present in
low concentrations in treatment residuals from the LT3®
system and other thermal desorption systems. Under 40
CFR Section 268.31, F020 to F023 and F026 to F028, dioxin-
containing wastes are prohibited from land disposal unless
the treatment standard of 1 part per billion (ppb) for each
dioxin or furan isomer is met. Fabric filter dust generated
during the SITE demonstration exceeded this value for some
isomers, but concentrations of the 2,3,7,8-TCDD congener,
which is considered the most toxic, were less than 1 ppb.
Requirements for corrective action at RCRA-regulated
facilities are provided in 40 CFR Part 264, Subpart F
(promulgated) and Subpart S (proposed). These subparts
also generally apply to remediation at Superfund sites.
Subparts F and S include requirements for initiating and
conducting RCRA corrective actions, remediating ground
water, and ensuring that corrective actions comply with other
environmental regulations. Subpart S also details conditions
under which particular RCRA requirements may be waived
for temporary treatment units operating at corrective action
sites. Thus, RCRA mandates requirements "similar to
CERCLA, and as proposed, allows treatment units such as
the LT3® system to operate without full permits.
3.2.3 Clean Air Act
The CAA requires that treatment, storage, and disposal
facilities comply with primary and secondary ambient air
quality standards. ' To monitor gas emissions, the LT3®
system includes CEM at the discharge stack for CO, carbon
dioxide (COj), oxygen (Oj), and THC. A state air pollution
permit is required, except at CERCLA sites where only the
substantive requirements of a permit must be addressed. In
addition to CEM parameters, permit limits may be
established for total suspended particulates, acid gases, toxic
organics such as dioxins and furans, and stack height. The
LT3* off-gas treatment system can be modified to include an
afterburner or caustic scrubber to meet site-specific
requirements.
3.2.4 Occupational Safety and Health
Administration
CERCLA response actions and RCRA corrective actions
must be performed in accordance with OSHA requirements
detailed in 29 CFR Parts 1900 through 1926, especially Part
1910.120, which provides for the health and safety of workers
at hazardous wastes sites. On-site construction activities at
Superfund or RCRA corrective action sites must be
performed in accordance with Part 1926 of OSHA, which
provides safety and health regulations for construction sites.
3.3 Implementability
The LT3® system implementation includes mobilization,
O&M requirements, reliability, personnel requirements, and
demobilization. These aspects of implementation are
discussed below. In general, the system is easy to set up and
operate. However, waste feed characteristics can impact
system reliability if the feed is not adequately prepared.
3.3.1 Mobilization
The first step for the implementation of the LT3® system
is equipment mobilization. Site characteristics are important
factors to be considered prior to the mobilization of the
LT3® system. These characteristics include site area, site
preparation, and site access.
Site Area
Weston has developed three different thermal
processors, each of a different size and capability. The
bench-scale LT3® unit with two 3-foot screws was initially
used to evaluate the treatment concept. This unit led to a
pilot-scale unit with two 10-foot screws, which was used hi
initial field tests. Finally, the full-scale production unit was
built with eight 20-foot screws. This full-scale unit was used
during the SITE demonstration. The mobile unit is
comprised of equipment assembled on three flat-bed trailers,
with ancillary and support equipment on another three
trailers. The entire system requires a relatively flat area of
about 5,000 square feet.
Site Preparation
Site preparation is typically needed prior to operating
the LT3® system. For the SITE demonstration the following
site preparation was needed:
• Placement of gravel in areas where the LT3® system
was to be located; gravel was needed to maintain a
roughly consistent grade across the processing area.
• Placement of supports, such as steel plates, wood,
concrete blocks, and so on in areas where the
heaviest equipment would be situated. Support
material should be placed below the tires and drop
legs to prevent equipment from leaning or sliding in
soft soil.
• Placement of gravel in areas of expected heavy
vehicular traffic, as necessary.
• Construction of earthen ramps, as necessary, to
provide access for excavation and transportation
equipment.
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• Establishment of health and safety zones to
accommodate both on-site operating and off-site
support personnel.
Site Access
Site access requirements for the LT3® equipment are
minimal. The site must be accessible to trailer trucks
delivering the LT3® equipment, and the bed of the access
road must be able to support these vehicles. Because the
LT3® unit trailer is oversized, some highway restrictions may
apply. State and local authorities should be contacted for
specific requirements and restructure.
3.3.2 Operations and Maintenance Requirements
O&M requirements for the LT3® system include general
utility services as well as services and supplies. These
requirements are discussed below.
Utilities
Operating the LT3® system requires the following
utilities:
• Electrical Power -- The LT3® system requires 460-
volt, three-phase, 600-ampere electrical service.
Transformers in the LT3® system reduce the
electrical service to 240-volt, three-phase and 120-
volt, single-phase service to operate the CEM
system and control circuits, respectively.
• Diesel Fuel — Diesel fuel for heavy equipment,
supplied by a tank-mounted pickup truck may be
purchased from a nearby retailer.
• Fuel — Natural gas at a pressure of 15 pounds per
square inch (psi) is required for the burner that
heats the heating fluid. The LT3® system's total
maximum natural gas consumption is 7.2 million
British thermal units per hour (Btu/hr). Propane
can also be used as an alternative fuel.
• Process Water — Process water is primarily needed
for quenching treated material and for
decontamination purposes. Water may be supplied
by an existing on-site water distribution system. In
many applications, treated condensate may be used
for this purpose.
Services and Supplies
A number of readily obtainable services and supplies are
required to operate the LT3® system. Major services
needed for remedial activities may include (1) heavy
equipment rigging, (2) sludge dewatering, (3) regular vacuum
cleaning of the LT3® system off-gas ducts, and (4) laboratory
analyses to monitor the system's performance.
During the SITE demonstration and ADC site
remediation, subcontractors or off-site facilities furnished the
major services required by the remedial activities. Weston
hired a national hazardous waste services subcontractor to
dewater the sludge using a filter press. Weston hired local
industrial services subcontractors to set up the unit and to
vacuum ducts that carry off-gas and dust from the thermal
unit to the fabric filter. When the system operated 24 hours
per day, vacuuming was required about once a month. To
monitor the performance of the LT3® system, samples were
collected every 12 hours and sent to an off-site laboratory for
analysis.
Supplies required for the remedial activities included (1)
lime and ferric chloride stabilizing agents, (2) heat transfer
fluid, (3) absorbing cloth and oil-dry material, (4) diesel fuel,
(5) plastic sheeting, (6) steel drums, (7) fiber drums, (8)
vapor-phase carbon adsorption columns, (9) paper filters,
and (10) liquid-phase carbon adsorption columns. These
supplies are discussed below.
At the ADC site, lime and ferric chloride were added to
the untreated sludge before dewatering as conditioning
agents at a rate of 0.1 pound of each chemical per gallon of
raw sludge. Both chemicals were added directly to the
mixing tank from 50-pound paper bags.
The heating fluid system has a capacity of about 1,000
gallons. At the beginning of LT3® operations, the heating
fluid tank is filled with heating fluid; no additional heating
fluid is normally needed for further operation of the system.
However, heat transfer fluid is occasionally added to the
LT3® system to replace heating fluid lost from accidental
leaks. Absorbing cloth and oil-dry material were
occasionally applied to the ground beneath the heating fluid
sj'stem to contain accidental spills of the heating fluid.
Heavy equipment operation requires about 35 gallons of
diesel fuel per day. Diesel fuel was supplied every week by
a local retailer and stored on site in an aboveground storage
taink.
A 20-foot by 20-foot plastic sheet was used to cover the
pile of treated sludge produced every 12 hours. In addition,
two 55-gallon steel drums are needed every 12 hours to
collect and store fabric filter dust, and one 55-gallon fiber
drum is needed each shift to store used PPE.
During the ADC site remediation, one vapor-phase
carbon adsorption column was replaced every 5 to 10 days
of LT3® system operation. The frequency with which the
vapor-phase carbon adsorption units need to be changed
depends on site-specific factors and contaminant
concentrations.
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The condensate treatment system at the ADC site used
two paper filters with a nominal pore size of 50 micron
(ftm). The filters operated in series to remove particulate
matter. Filters were changed after every 12 hours of system
operation. Two liquid-phase carbon adsorption columns
were used in series to treat liquid condensate exiting the
paper filters. Both liquid-phase carbon columns were
replaced about every 2 months of operation.
3.3.3 Reliability
The LT3* system may be subject to several operational
problems. This section summarizes operational problems
observed during (1) shakedown and startup operations, (2)
the SITE demonstration, and (3) remedial activities at the
ADC site. Operational problems resulted from mechanical
difficulties with the screws, a malfunctioning oil-water
separator, oversized debris hi the feed material, leaking
sweep air gas, excess dust generation from reprocessed
sludge, and leaking pipes in the heat transfer fluid system.
Operational problems with the LT3® system resulted in an
on-line efficiency of about 70 percent. These problems are
discussed below.
Startup operations at the ADC site lasted about 2 weeks,
largely because of troubleshooting associated with the screws
and the heating fluid system. Before the LT3® system
arrived at the ADC site, the screws had been resurfaced to
prevent heating fluid from leaking during processing. The
screws were filled with water to check for leaks. However,
after the leak check was completed, Weston estimated that
about 400 gallons of water remained in the screws. When
hot heating fluid passed through the screws, this water
vaporized, causing a potentially dangerous pressure buildup
in the system. To avoid this potential problem, the system
was drained and filled with new heating fluid. Several days
of operation were needed to evaporate the residual water,
which was released through pressure control valves.
Another operational problem during shakedown was (
associated with the rotational speed of the screws. The
residence time required to achieve proper treatment was
approximately 90 minutes. However, the LT3® system was
equipped with motor drives that could not provide a
residence time longer than about 70 minutes. To rectify this
problem, Weston replaced the motor drives with units that
were capable of sustaining a longer residence time.
The LT3* system includes a three-phase oil-water
separator and a liquid-phase carbon adsorption unit for
treating liquid streams exiting the air-cooled and refrigerated
condensers. However, the oil-water separator did not
function properly during shakedown operations at the ADC
site because of the unexpectedly large volume of condensate
produced. The liquid stream flowed out of the air-cooled
condenser at a rate of about 2 gallons per minute (gpm),
and the liquid stream exited the refrigerated condenser at a
rate of about 0.6 gpm. Both liquids were routed into a
holding tank and were treated through a paper filtration unit
prior to the carbon adsorption system.
The most severe and common operational problems
during the ADC site remediation resulted from large rocks
or oversized debris in the feed sludge. On several occasions,
large rocks became wedged in the screw conveyors, resulting
in several days of downtime. In two instances, the gear box
broke when rocks became wedged between screws. On both
occasions, machining new parts and reinstalling the gearbox
took about 11 days. On another occasion, a rock hi the feed
sludge broke the coupling that connects the screws to the
gearbox. Machining new parts and repairing the system
required about 15 days of downtime.
In each case, before repairs could begin, the LT3" system
had to be shut down and allowed to cool. After about 12
hours of cooling, Weston personnel could enter the LT3®
system's thermal processor to remove the remaining sludge
and locate the obstruction hi the screws. This operation
requires a confined space entry permit. In some cases, the
jammed rock had to be chipped out using a pneumatic
hammer.
On several other occasions when the screws became
jammed, downtime was avoided by repeatedly reversing the
screws' rotation until the obstructive rock worked free. On
these occasions, Weston personnel cleared the system by
manipulating it from the control room, eliminating any need
for a confined space entry.
Following repeated shut downs due to jammed screws,
Weston rented a diesel-powered shaker screen. Initially, a
screen with 2.5-inch openings successfully removed oversized
material from the feed. However, additional downtime
resulted when a 2-inch-diameter rock jammed the screws.
To ensure that the LT3® system would continue operating
with no downtime, Weston installed a screen with 1.25-inch
openings below the screen with 2.5-inch openings. The two
screens successfully prevented oversized material from
jamming the screws, however, it increased screening time for
the wet, clay material at the ADC site.
Several operational changes could minimize or prevent
downtime caused by rocks hi the feed. First, screening the
feed with the shaker screen proved to be a successful, but
not foolproof, method of keeping the screws free of
obstructions. Failure of the gearbox and couplings could be
avoided by replacing the steel phi that connects the screw
couplings to the gearbox couplings. If the steel phi were
replaced with a phi of weaker material, the expendable phi
would break before more expensive and intricate parts of the
system failed. Keeping a ready supply of spare parts and
then- specifications could also minimize replacement time.
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Another operational problem was associated with sweep
air leaking from the LT3® system feed hopper. Sweep air is
held in the LT3® system by sludge in the feed hopper. As
sludge was drawn in to the LT3® system, gaps formed in the
feed flow in the hopper, allowing sweep air to escape.
Sweep air leaked approximately once every 3 hours of
operation. Weston rectified the situation in less than 5
minutes by adding more feed and manually poking the feed
with a shovel to make the feed flow more uniform.
Other operational problems occurred when treated
sludge was reprocessed to meet MBOCA cleanup goals.
Treated sludge had a low moisture content and a large
amount of small particles. When it was reprocessed, large
amounts of dust were picked up by the sweep air, clogging
the sweep air ducts. The ducts had to be cleaned out
periodically, resulting in several 1-hour periods of downtime.
During remedial activities at the ADC site, heating fluid
leaked from a valve in the return line running from the LT3®
system to the heating system. To repair the leak, the heating
system's burner was turned off, and the leaking pipe was
isolated. Heating fluid contained in the leaking part of the
pipe was then drained into a drum. After the valve was
replaced, the heating fluid no longer leaked. Operations
began again after about 5 hours of downtime. Only about 10
to 20 gallons of heating fluid was lost due to the leak, a
relatively small amount compared to the 1,000-gallon
capacity of the heating fluid system. The heating fluid
discharged was not reused; it was kept on site for future
disposal.
3.3.4 Personnel Requirements
Operation of the LT3® system requires six people. This
number includes a field project manager, an O&M
supervisor, a site safety officer, and three equipment
operators. Two equipment operators supply a constant feed
of untreated sludge, one operating a front-end loader while
the other inspects the feed traveling up the feed conveyor.
These two persons are also responsible for ensuring a steady
flow from the feed hopper into the LT3® system. The other
operator performs general site activities, including moving
treated waste. For sludge dewatering, feed screening, or
under special circumstances such as ambient air sampling,
additional personnel are required on site.
3.3.5 Demobilization
After the SITE demonstration, the LT3® system
remained on site to perform remedial activities at the ADC
site. Therefore, equipment demobilization was not part of
the SITE demonstration. This section summarizes typical
demobilization activities, such as those planned by Weston
at the completion of the remedial activities at the ADC site.
Demobilization includes removal of the LT3® system and
the trailer containing the control room and office.
Decontamination of the exterior of the LT3® system trailers
and ductwork and all excavation and material handling
equipment will be conducted using a high-pressure spray
washer in the decontamination area. The interior of the
LT3® processor will be decontaminated by operating the heat
processor for several hours at the maximum operating
temperature to remove remaining contaminants. Other
demobilization activities include the removal and off-site
disposal of all plastic liners from the material staging area.
Liners will be decontaminated with high-pressure water and
detergent, if practical.
All decontamination water will be treated on site using
granular activated carbon. Spent activated carbon units will
be returned to the supplier for regeneration. Disposable
PPE will be collected in drums, manifested, and sent off site
for disposal.
3.4 Short-Term Impact
The potential short-term impact of the LT3® system
application includes worker safety and potential community
exposures. Personnel operating the LT3® system and
performing remedial activities are required to have health
and safety training in order to perform site activities in a
safe manner. Also, with proper operation and monitoring of
the LT3® system, community exposures are minimal. The
LT3® system's impact on workers and the nearby community
is discussed below.
3.4.1 Worker Safety
Worker safety considerations associated with LT3®
operations can be grouped in two categories: (1) physical site
hazards and (2) potential chemical hazards. General site
hazards during the operation of the LT3® system include the
following:
• Heavy equipment hazards
• Occupational noise exposure
• Potential slip, trip, or fall hazards
• Potential for contact with mechanical equipment
(motors, fans, and conveyors) and electrical
equipment or utility lines
• Open trench and excavation hazards
• Airborne dust hazards
• Potential splashing of liquid
• Confined space entry
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In addition, the heating fluid system presents potential
burn hazards. The hot oil circulates through the LT3®
processor at up to 650° F, presenting a great hazard at
transfer points in the lines or in the event of a line rupture.
Potential chemical hazards involve inhaling, absorbing,
ingesting, and coming in contact with constituents of concern
in contaminated material. The exposure likelihood of this
activity is high during excavation and handling of
contaminated sludge. At the ADC site, primary constituents
of concern included MBOCA; manganese; 4-methylphenol;
phenol; 1,2-dichlorobenzene; and toluene.
All personnel working at the site had a minimum of 40
hours of health and safety training, and all were under
routine medical surveillance. Remedial activities at the ADC
site were conducted using Level C PPE.
3.4.2 Potential Community Exposures
Potential community exposures to health hazards from
the operation of the LT3® technology include exposure to (1)
stack gas emissions, (2) fugitive dust emissions, (3) liquid
spills resulting from condensate handling, and (4) noise from
the operation of the LT3® system. When the LT3® system
operates properly and is regularly maintained, the potential
for community exposures are minimal.
3.5 Long-Term Effectiveness
The LT3® system permanently removes contaminants
from soil. However, treatment residuals are not destroyed
on site and require proper off-site treatment and disposal.
Long-term effectiveness of the LT3® system was assessed
based on the permanence of the treatment and the handling
of process residuals. These items are discussed below.
3.5.1 Permanence of Treatment
The LT3* system desorbs and permanently removes
contaminants from the contaminated soil. Approximately 25
tons of treated material were produced every 12 hours of
LT3* system operation at the ADC site. Treated material
from each processing period was staged separately. During
remedial activities at the ADC site, treated material was
transported to a clean staging area to await analytical results.
If analytical results indicated that the thermal treatment had
not achieved the required level of treatment, the material
was reprocessed in the LT3® system.
3.5.2 Residuals Handling
Two types of residuals are generated from the LT3®
process: (1) condensate and (2) fabric filter dust. The long-
term effectiveness of the LT3® system ultimately depends on
the methods used to treat or dispose of these residuals.
Operation of the LT3® system generated condensate at
a rate of about 2 to 2.8 gpm. The amount of condensate
produced may differ significantly, depending on the moisture
content of the sludge. During the SITE demonstration and
full-scale remediation at the ADC site, condensate from the
LT3® process was routed to a holding tank. From the tank
it was pumped through a filter to remove particulate matter
and through a liquid-phase carbon adsorption system to
remove organic contaminants. Treated condensate was then
shipped off site for disposal at a hazardous waste disposal
facility. In other LT3® system applications, treated
condensate was used to quench and control dust from
treated sludge.
Another residual generated from the condensate
treatment system is a separated organic stream. At the
ADC site, the organic stream was a heavy residue that
accumulated in the bottom of the holding tank. This heavy
residue most likely consisted of organic solids settling in the
bottom of the tank. After the SITE demonstration tests, the
solid residue was removed from the bottom of the holding
tank and mixed with contaminated sludge for reprocessing
during remedial activities. However, during remedial
operations at the site, the heavy residue was drummed for
future off-site disposal.
In previous LT3® system applications, condensate was
treated by a three-phase, oil-water separator, which allowed
water to separate from insoluble light and heavy organic
components. Light organics were removed by a skimmer
and weir. The heavy organic phase was removed through a
manually operated drain at the bottom of the separator.
Both organic phases removed from the oil-water separator
were drummed for off-site disposal. Drummed organics
were manifested and shipped off site for treatment and
disposal at a RCRA-permitted facility. Water flowing out of
the separator was directed to a liquid-phase carbon
adsorption system. The water treatment system can be
modified to include other standard processes to meet site-
specific discharge disposal requirements.
At the ADC site, approximately two 55-gallon drums of
fabric filter dust were collected every 12 hours of LT3®
system operation. Three disposal options were considered
for fabric filter dust. Depending on sample analytical results,
the dust would be (1) mixed with treated material for on-site
disposal, (2) recycled for further treatment, (3) or drummed
for off-site disposal. SITE demonstration analytical results
showed that the concentrations of contaminants in the fabric
filter dust were above cleanup goals. Dust produced during
the SITE demonstration and during full-scale operation was
drummed for off-site disposal. Special care should be taken
when retreating fabric filter dust. The dust contains large
amounts of small particles, which can easily be carried away
by the off-gas, clogging the system's off-gas ducts.
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3.6 Factors Influencing Performance
Several factors may influence the LT3® system's
performance, including waste characteristics, operating
parameters, and climate. Waste characteristics that may
influence the performance of the LT3® system include the
waste feed material's size, its moisture content, its particle
size distribution, and its pH. Two primary operating
parameters found to affect contaminant removal efficiency
were optimized during shakedown operations before the
SITE demonstration: (1) contaminated sludge flow rate and
(2) heating fluid temperature. The effects of the feed
materials waste characteristics, the LT3® system operating
parameters, and the climate are discussed below.
3.6.1 Size of the Waste Feed
The LT3® system operates best when the waste feed
material consists of small, uniformly sized particles,
preferably less than 2 inches in diameter. Severe operational
problems may result from large rocks or oversized debris in
the feed material. Large rocks may become wedged in the
screw conveyors, resulting in several days of downtime.
During the SITE demonstration, oversized material in the
sludge was removed manually before dewatering operations
and before the waste feed entered the LT3® system. In
previous LT3® applications, feed material was shredded, and
only material smaller than 2 inches in size was processed.
During remedial activities at the ADC site, a vibrating screen
was used to pretreat dewatered sludge.
3.6.2 Moisture Content of the Waste Feed
The LT3® process is most efficient for wastes with a
moisture content of about 20 percent. Wastes with a high
moisture content require additional thermal energy to
maintain the treatment temperature while removing the
water, thereby increasing operating costs. Wastes with a
high moisture content also generate more condensate,
thereby increasing handling requirements. Wastes with a low
moisture content produce large amounts of dust during
treatment, and they may create operational problems. To
enhance the efficiency of the LT3® system, wastes with a
moisture content greater than 50 percent must be dewatered.
Water can be added to dry wastes to control excessive
dusting.
The ADC lagoon sludge had a fluid consistency, with a
moisture content ranging from 65 to 70 percent. Thermal
desorption by the LT3® system cannot be used when the feed
material contain free liquids. Free liquids may leak through
the seals of the thermal processor and flush through the
system without being treated. To maximize the efficiency of
the LT3® system, ADC lagoon sludge was excavated with a
Mudcat hydraulic dredge and was dewatered using a plate
and frame filter press. The average dewatering time was 40
minutes. Before dewatering, lime and ferric chloride were
added to the sludge as stabilizing agents. For each gallon of
sludge, 0.1 pound of each chemical was added. The
moisture content of the dewatered sludge ranged from 41 to
44 percent. Dewatered sludge was stockpiled hi a storage
building prior to treatment.
3.6,.3 Particle Size Distribution of the Waste Feed
The waste feed's particle size distribution and available
surface area are important factors that affect the
performance of the LT3® system. Contaminants tend to be
adsorbed on smaller soil particles, because soil composed of
small particles has a larger surface area, making more sites
available for contaminant sorption. In general, sandy soils
are more effectively treated compared to clay type soils,
which consist of small particles.
SITE demonstration results indicated that the available
surface area of the contaminated sludge ranged from 49.1 to
52.3 square meters per gram (m2/g). These values are
comparable to the surface area of kaolinite, a clay material,
which has been reported to be 25 m2/g (Stumm and
Morgan, 1981). During excavation and stockpiling activities,
ADC lagoon sludge was mixed with clay from the base of
the lagoon, which may account for the similarity between the
surface area of the sludge and the surface area of kaolinite.
SITE demonstration results also showed that the
contaminant concentration in the fabric filter dust was
significantly higher than the contaminant concentration in the
treated material. These results indicate that contaminants
were adsorbed on smaller soil particles and were not
effectively desorbed during heating; instead contaminants
remained attached to the smaller particles, which were
carried away hi the sweep gas stream and trapped hi the
fabric filter.
Large amounts of small particles hi the feed material
could possibly cause operational problems by blocking the
system's off-gas ducts. During the full-scale remediation of
the ADC lagoon sludge, Weston reprocessed treated sludge
that did not meet cleanup requirements. Because the
treated sludge consisted of very small particles, reprocessing
produced large amounts of dust, causing operational
problems and increased maintenance requirements.
3,6.4 pH of the Waste Feed
The pH of the waste feed may also affect the
performance of the LT3® system. The pH of the waste feed
controls the net surface charge of the soil particles, which is
hi turn related to contaminant sorption. In addition, soil pH
determines the type and extent of chemical reactions that
occur during heat treatment in the LT3® system. Because
lime was added to the ADC lagoon sludge as a conditioning
agent, the pH of the untreated sludge was alkaline, ranging
from 10.9 to 11.2. The alkaline pH of the sludge may have
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induced several chemical transformation reactions during
heat treatment. For example, based on the SITE
demonstration results, the phenol concentration hi the sludge
was found to increase after treatment, while the
concentration of 1,2-dichlorobenzene, which was originally
present, decreased. The increase in phenol concentration is
most likely due to the dehalogenation of 1,2-
dichlorobenzene, a reaction that has been reported to take
place at elevated temperatures and alkaline pH (Larock,
1989). The dehalogenation scenario is supported by other
demonstration results, which also indicate that the BOX
concentration in sludge is reduced after treatment, while the
concentration of chloride is increased. In addition, the pH
of treated sludge was lower than the pH of untreated sludge,
ranging from 9.1 to 9.6. The reduction in pH is probably
caused by the formation of HC1 during dehalogenation
reactions.
The pH of the condensate stream was also alkaline,
ranging from 10.1 to 10.2. This alkaline pH may have
resulted from lime particles being carried away in the off-gas
stream before becoming dissolved in the condensate.
If lime had not been added to the waste feed, the pH of
the treated material and the liquid condensate would
probably be acidic, due to the formation of HC1 from
dehalogenation reactions. Acidic pH and" elevated
temperatures can cause equipment corrosion, which could
cause additional equipment problems.
3.6.5 Contaminated Sludge Flow Rate
The feed material's flow rate determines its residence
time in the LT3* processor. At a selected heating fluid
temperature, the residence time determines the treatment
temperature. The treatment temperature in turn determines
the efficiency of contaminant removal and the extent of
chemical transformations during heating. The LT3® system
can process contaminated material at a rate of up to 10
tons/hr. However, during the SITE demonstration, sludge
was treated at a rate of only 2.1 tons/hr, which resulted in
a residence time of 90 minutes. The sludge residence time
in the heat processor was maintained by adjusting the
rotational speed of the screws.
3.6.6 Heating Fluid Temperature
A heated, circulating fluid indirectly provides the thermal
energy needed to maintain the desired treatment
temperature in the heat processor. The treatment
temperature affects the rate and degree of contaminant
volatilization and formation of thermal transformation by-
products. For the SITE demonstration, the LT3® heat
processor needed to maintain a sludge temperature of above
500 °F in order to volatilize organics from the contaminated
sludge. The heat transfer fluid used during the SITE
demonstration and the full-scale remediation was Therminol
66, produced by Monsanto. According to manufacturer
guidelines, Therminol 66 performs best in temperatures
ranging from 20 to 650 °F. During the SITE demonstration,
the operating temperature of the heating fluid was 650 °F.
In previous LT3® operations, Dowtherm HT, manufactured
by Dow Chemical, was used as heating fluid. The maximum
recommended temperature for continuous operation with
Dowtherm HT is also 650 °F.
A heating fluid temperature of 650 °F and a 90-minute
residence tune resulted in a sludge treatment temperature
between 500 °F and 530 °F. The operating treatment
temperature of the sludge was maintained by controlling the
temperature, pressure, and flow rate of the heating fluid.
However, because the moisture content of the contaminated
sludge varied, the sludge treatment temperature also varied.
Variations in treatment temperature can influence the
treatment efficiency of the LT3® system.
3.6.7 Climatic Conditions
Dry, warm weather conditions are ideal for operation of
the LT3® system. However, the SITE demonstration was
conducted in subfreezing temperatures, and remedial
activities at the site were conducted in subfreezing or wet
weather conditions. Cold and wet weather caused minor
operational problems. The hose supplying water to the
treated sludge conditioner had to be covered with insulation
tape due to freezing temperatures. The insulated tape was
occasionally damaged, and the water supply hose
subsequently froze. Weston personnel thawed the hose with
a portable heater. Snowy conditions hampered visibility at
the site but did not affect the performance of the LT3®
system. Wet weather hampered sludge excavation and
handling. The LT3® system was not operated in extremely
hot conditions at the ADC site.
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Section 4
Economic Analysis
This section presents cost data associated with the LT3®
technology. Costs have been placed in 12 categories
applicable to typical cleanup activities at Superfund and
RCRA sites. This economic analysis discusses site-specific
factors affecting costs, assumptions the analysis is based on,
and each of the 12 cost categories as they apply to the LT3®
technology. Costs are presented in August 1992 dollars for
Weston's full-scale production unit with eight 20-foot screws.
Data was compiled during several pilot studies and during
the SITE demonstration and subsequent full-scale operations
at the ADC site. This analysis presents the costs associated
with treating 3,000 tons of VOC-contaminated soil, with a
VOC concentration of 10,000 parts per million (ppm). The
analysis also compares the costs associated with treating soils
containing 20 percent, 45 percent, and 75 percent moisture
content.
An economic analysis of the LT3® technology reveals that
operating costs are most affected by the feed rate and
residence time. The soil moisture content and the soil
treatment temperature (which is determined by contaminant
type and concentration) are site-specific factors that affect
costs. The treatment temperature and the soil moisture
content determine the feed rate and residence time needed
to properly treat soil and, to some degree, the amount of
residual waste produced.
4.1 Site-Specific Factors Affecting Costs
Site-specific wastes and features affect the costs of this
soil treatment technology. Waste-related factors affecting
costs include waste volume, waste type, soil moisture content,
treatment goals, and regulatory permit requirements. Site-
specific features affecting costs include site area, accessibility,
availability of utilities, and geographic location. The
characteristics of the residual waste also affect supply and
disposal costs. Residual wastes produced by the LT3® system
and their characteristics determine if the wastes can be
recirculated for treatment in the system or if they must be
disposed of off site as hazardous wastes.
4.2 Basis of Economic Analysis
Table 4-1 presents a breakdown of the factors
considered for each of the 12 cost categories. These costs
are considered to be order-of-magnitude estimates, with an
expected accuracy within 50 percent above and 30 percent
below the actual costs. The table presents a breakdown of
costs for a 3,000-ton remedial action site; it also compares
treatment costs for soils containing 20, 45, and 75 percent
moisture. Larger or smaller projects may have different cost
per ton values. Because fixed costs are not affected by the
volume of soil treated, larger projects will usually have a
lower cost per ton. The following sections present
underlying assumptions about (1) the LT3® technology and
capital costs, (2) soil and site conditions, and (3) the LT3®
system used in this economic analysis.
4.2.1 Assumptions about the LI8® Technology and
Capital Costs
This analysis is intended for potential clients needing to
treat soils contaminated with VOCs or SVOCs. This
analysis assumes that Weston will subcontract the LT3®
system to government or private clients for on-site soil
treatment. The LT3® technology will be delivered to the site
by six semitrailer trucks and will be assembled by Weston.
The assembled equipment will consist of the LT3® system
used at the ADC demonstration, with no deviations. Neither
depreciation nor salvage value is applied to the costs
presented in this analysis.
4.2.2 Assumptions about the Soil and Site
Conditions
Soil and site conditions have a great impact on total
project cost, primarily because they determine how long the
LT^1 system will need to operate. The amount and type of
contaminants in soil and the cleanup goals for the site will
determine the temperature and residence time necessary for
treatment. High soil moisture content will increase
residence tune and the amount of residual water produced.
As a result, costs are affected by lower production speeds
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Tab/a 4-1 Cost Analysis for Operating the LI*® System
Cost Categories
Site Preparation Costs6
Administrative Costs
Fencing Costs
Construction Costs
Dewaterlng Costs
Total Site Preparation Costs
Permitting and Regulatory Costs'3
Permit
Engineering Support
Total Permitting and Regulatory Support
Equipment Costs
LT3® Rental0
Support Equipment Rental
Dumpsters0
Wastewater Storage Tanks9
Steam Cleaner
Portable Toilef
Optional Equipment Rental0
Total Equipment Costs
Startup Costs'1
Mobilization
Assembly
Shakedown
Total Startup Costs
Labor Costs0
Operations Staff
SHe Manager
Maintenance Supervisor
Site Safety Officer
Total Labor Costs
Supply and Consumable Costs
PPE°
PPE Disposable Drums
Residual Waste Disposal Drums
Activated Carbon"
Diesel Fuel0
Calibration Gases"
Total Supply and Consumable Costs
Cost Per Ton of Soil Treated*
Soil Moisture Content
20% 45% 75%
11.00
.40
.70
NA
12.10
3.30
80.00
83.30
13.00"
.70
1.00
.10
.10
12.00
26.90
10.00
25.00
15.00
50.00
39.00
21.60
7.20
7.20
75.00
6.00
.50
1.20
8.00
.65
.35
16.70
11.00
.40
.70
NA
12.10
3.30
80.00
83.30
22.00
1.35
2.00
.10
.20
20.00
45.65
10.00
25.00
15.00
50.00
79.50
44.30
14.60
14.60
153.00
10.00
1.00
1.20
24.00
1.00
1.10
38.30
11.00
.40
.70
187.90
200.00
3.30
80.00
83.30
22.00
1.35
2.00
.10
.20
20.00
45.65
10.00
25.00
15.00
50.00
79.50
44.30
14.60
14.60
153.00
10.00
1.00
1.20
24.00
1.00
1.10
38.30
24
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Cosf Per Ton of Soil Treated3
Soil Moisture Content
Cost Categories
20%
45%
75%
Utility Costs
Natural Gas (@ $1.43/1,000 ft3)
Electricity (@ $0. 18/kWh)
Water (@$ 1.00/100 gallons)
Total Utility Costs
Effluent Montitorina Costs'
Residual Waste and Waste Shipping, Handlina. and
Transportation Costs
Oversized Material (2% of feed soil)
Drums
Wastewater
Total Residual Waste and Waste Shipping,
Handling, and Transportation Costs
Analytical Costs
Treatability Study*
Sample Analysis for VOCs
Total Analytical Costs
Eouipment Repair and Replacement Costs
Maintenance
Design Adjustments'
Facility Modifications'
Total Equipment Repair and Replacement Costs
Site Demobilization Costs
TOTAL COST PER TON OF SOIL TREATED3
7.80
2.10
.60
10.50
0.00
5.40
27.00
7.20
39.60
10.00
4.20
14.20
11.70
0.00
0.00
11.70
33.00
373.00
26.00
6.30
.60
32.90
0.00
5.40
27.00
14.40
46.80
10.00
12.00
22.00
19.80
0.00
0.00
19.80
33.00
536.85
26.00
6.30
.60
32.90
0.00
5.40 .
27.00
14.40
46.80
10.00
12.00
22.00
19.80
0.00
0.00
19.80
33.00
724.75
NA = Not Applicable
" = Cost per ton of soil treated; figures are rounded and have been developed fora 3,000-ton project.
b = Fixed cost not affected by the volume of soil treated.
c = Costs are Incurred for the duration of the project.
d = Feed rate is double that of soils with 45 percent moisture content.
" = Costs are incurred only during soil treatment activities.
' = Cost included in the cost of renting the LT3® system.
25
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and increased handling requirements. For example, soils
with 20 percent moisture content have a feed rate double
that of soils with 45 percent moisture content. In addition,
a higher soil moisture content, such as 75 percent, may
require soil dewatering, a process that will further increase
costs.
Site preparation costs are determined by the volume of
contaminated soil, the size of the site, and the availability of
utilities. This analysis assumes that a natural gas pipeline is
available at the site. Utility costs can be minimized if
natural gas is available to power the LT3® system's heating
units. Otherwise, propane, which can be transported to the
site, is the least expensive alternative fuel capable of
achieving the necessary operating temperatures. This
analysis also assumes that the contaminated soil is a fairly
homogenous clay-type soil, with a low moisture content and
only a minimal amount of oversized material. These soil
characteristics will lower site preparation costs.
4.2.3 Assumptions about LI6® System Operation
For soils with a 45 percent moisture content, this
analysis assumes that the LT3® system can treat
contaminated soil in batch cycles at 70 percent efficiency
until the job is done. The soil feed processing rate is
assumed to be 2.1 tons per hour (tons/hr) for a residence
time of 90 minutes. This feed rate was used at the ADC
site. Operating at 70 percent efficiency, about 250 tons of
soil can be treated per week. At this rate, treating 3,000
tons of contaminated soil would take about 3 months,
excluding mobilization and demobilization. Soil with a
75 percent moisture content must first be dewatered. Once
the soil is dewatered to 45 percent moisture content, it can
be treated according to the schedule described above.
For soils with 20 percent moisture content, this analysis
assumes that the LT3® system can treat contaminated soil in
batch cycles at 70 percent efficiency until the job is done.
However, in this scenario, the soil feed processing rate is
assumed to increase to 7 tons/hr for a residence time of
30 minutes. Operating at 70 percent efficiency, about 820
tons of soil can be treated per week. At this rate, treating
3,000 tons of contaminated soil would take almost 1 month,
excluding mobilization and demobilization.
The LT3* system requires three operators and one
supervisor working two 12-hour shifts per day. One
maintenance technician and one site safety officer will be
employed during the first 12-hour shift and as needed during
the second shift.
Weston's full-scale LT3® system, with eight 20-foot
screws, is the only model available. Therefore, no
equipment cost alternatives are presented here. This
analysis presents fixed and variable costs for operating the
full-scale LT3® model.
This analysis is also based on the following assumptions:
• Residual wastes will be disposed of off site.
• Access roads exist and will not have to be
constructed.
• Utility lines, such as electricity and telephone lines,
exist on site.
• Air emissions monitoring will be continuous.
• Treated soil or sludge will be used as backfill at the
site.
4.3 Cost Categories
Cost data associated with the LT3® technology have been
assigned to the following 12 categories: (1) site preparation
costs; (2) permitting and regulatory costs; (3) equipment
costs; (4) startup costs; (5) labor costs; (6) consumable
material costs; (7) utility costs; (8) effluent monitoring costs;
(9) residual waste shipping, handling, and transportation
costs; (10) analytical costs; (11) equipment repair and
replacement costs; and (12) site demobilization costs. Each
of these cost categories is discussed below.
4.3.1 Site Preparation Costs
Site preparation costs include administrative, fencing,
and construction costs. Site preparation costs will vary
depending on the amount of contaminated soil, the size of
the site, and the availability of utilities and access roads. Site
preparation costs will be lower if the contaminated soil is
fairly homogenous and clay-like, with a low moisture content
and only minimal amounts of oversized materials, such as
rocks and debris. Soils with high moisture content will need
to be dewatered.
For this analysis, site preparation administrative costs,
such as legal searches, access rights, and other site planning
activities, are estimated to be $33,000. This analysis also
assumes that minimal site grading is required, natural gas
and water supply lines exist at the site, and heavy equipment
is rented. The costs for heavy equipment are included in
equipment costs (see Section 4.3.3), because the equipment
will be on site for the duration of the treatment.
A 6-foot-high, chain-link security fence with a 12-
foot-wide gate will be needed to surround the 75-square-foot
LT3® system. The site area totals 5,000 square feet. The
fence will cost about $730 for materials, and it is assumed
that the LT3® crew will install it. About 500 feet of
moveable snow fencing was used to enclose active excavation
areas at the ADC site. The fence was intended to prevent
accidents near and around the excavation area. Snow
fencing is available in 50-foot bundles for about $50.00 per
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bundle. Other construction costs include assembling the
LT3® system and installing concrete foundations and soil
staging and storage areas. These construction costs are
assumed to be 10 percent of total site preparation costs.
The primary costs associated with dewatering include
labor, rental of dewatering equipment (such as a filter press
and a slurry pump), mobilization, and demobilization. At
the ADC site these costs were about $187.90 per ton of soil
dewatered from 75 to 45 percent moisture content (Weston,
1992). It is assumed that a filter press can process about 120
tons of soil per day or 840 tons per week. Once a stockpile
of dewatered soil is available, dewatering and thermal
processing may occur concurrently. Because the LT3® is
assumed to process 250 tons of soil per week, dewatering
will not significantly increase the amount of time needed to
complete the project and, therefore, is not considered in this
analysis.
A treatability study will need to be performed to
determine site- and waste-specific temperature requirements
and residence times. Because treatability study costs are
primarily analytical, they are included in analytical costs (see
Section 4.3.10).
4.3.2 Permitting and Regulatory Costs
Permitting and regulatory costs include fees for highway
permits for oversized vehicles and air permits for the LT3®
system's heating unit and monitoring equipment. These fees
are assumed to cost about $5,000 each.
Weston estimates typical total permitting costs to
average $240,000 for engineering support, such as acting as
a liaison to regulatory agencies and generating various
reports. Proof-of-process testing, analysis, and reporting
increase these costs by an average of $100,000
(Weston, 1986). In some cases, condensate from the LT3®
system could possibly be discharged to a publicly owned
treatment works, which would require a National Pollutant
Discharge Elimination System (NPDES) permit. This
permit would increase permitting and regulatory costs and
effluent monitoring costs.
RCRA corrective action sites require additional
monitoring records and sampling protocols, which can
increase the regulatory costs by an additional 5 percent
(EPA, 1991b). CERCLA and SARA require remedial
actions to be consistent with ARARs of environmental laws,
ordinances, regulations, and statutes, including federal, state,
and local standards and criteria. In general, ARARs must
be determined on a site-specific basis.
4.3.3 Equipment Costs
Equipment costs include renting the complete LT3®
system and support equipment. Weston will only lease the
LT3® system to its clients. The rental rate is assumed to be
about $13,000 per month. Support equipment includes roll-
off dumpsters for oversized material; 2,000-gallon storage
tanks for treated wastewater; and a steam-cleaner for
decontaminating equipment. Support equipment costs are
discussed below.
This analysis assumes that oversized material removed
frorn contaminated soil is stored in a 40-cubic-yard roll-off
dumpster prior to disposal. Oversized material is assumed
to constitute 2 percent of the feed soil. By this estimate,
3,000 tons of contaminated soil will contain 60 tons of
oversized material, which would fill nearly two dumpsters.
The average rental cost of a 40-cubic-yard roll-off dumpster
is $500 per month (Ravenswood Disposal Services, 1992).
Disposal costs for oversized material are included in
residuals and waste shipping, handling, and transportation
costs (see Section 4.3.9).
Treated wastewater is generated when processor off-
gasses are filtered and cooled in the LT3® system's
condensers. Condensate is treated in a vapor-phase carbon
adsorption unit before being stored in tanks prior to off-site
disposal. The costs associated with the vapor-phase carbon
adsorption unit are included in consumable material costs
(see Section 4.3.6). Storage tanks are needed for the
duration of the project. At the ADC site, the soil had a
45 percent moisture content, which generated about 120
gallons of wastewater per hour, or 57 gallons per ton of soil
treated. If two 2,000-gallon tanks are rented, wastewater will
have to be disposed of almost every other day. Each tank
can be rented for about $1,000 per month.
The actual amount of wastewater generated and the
subsequent size of the tanks depends on the moisture
content of the feed soil. It is assumed that soils with 20
percent soil moisture content will generate about half as
much water as soils with 45 percent moisture content. In
this scenario two storage tanks should still be rented, but
they will be emptied less frequently and over a shorter
period of time. Disposal costs for wastewater are included
in residuals and waste shipping, handling, and transportation
costs (see Section 4.3.9). Under some circumstances, treated
condensate water can be sprayed directly on the treated soil
to control dust, thus eliminating storage and disposal costs.
A steam-cleaner is needed at the end of the project to
decontaminate equipment. Steam-cleaning units can be
rented for $300 per month (EPA, 1991a). No mobile office
trailer is necessary because it is included with the complete
LT3® system. However, portable toilets are not available
with the system and may have to be rented. Weston
estimates the cost of renting a portable toilet to be $120 per
mouth.
Optional support equipment needed depends on the
depth and amount of soil to be treated. Either front-end
27
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loaders or backhoes can be used to transport soil. At a
minimum, one excavator and two loaders or backhoes are
needed for soil excavating, transporting, and regrading
activities. All this equipment can be rented for about
$12,000 per month, based on normal use during the two-shift
days. It is assumed that LT3® personnel will be licensed to
operate this equipment.
4.3.4 Startup Costs
Startup costs include mobilization, assembly, and
shakedown costs. This analysis assumes that startup will
take 5 weeks and that Weston will provide trained personnel
to deliver, assemble, operate, and maintain the LT3® system
and any necessary support equipment. Also, it is assumed
that Weston's personnel are trained in health and safety
procedures. Therefore, training costs are not incurred as a
direct startup cost. Total startup costs are about $150,000
and include the activities mentioned in this section.
Mobilization involves transporting all equipment to the
site. Transportation costs are site-specific and will vary
depending on the location of the site in relation to all
equipment vendors. Five semitrailers with five drivers are
required to ship the LT3® system to the site from West
Chester, Pennsylvania. Mobilization is assumed to comprise
about 20 percent of total startup costs, costing about $30,000.
Assembly costs include the costs of unloading equipment
from trailers and assembling the LT3® system. These
activities require a crane rental and a crew of four working
12 hours per day for about three weeks. After assembly,
equipment must be hooked up to utilities. Assembly is
assumed to comprise about 50 percent of total startup costs,
costing about $75,000.
Shakedown costs include initial setup, initial startup, and
proof-of-process tests. About 600 tons of sand is used for 2
to 3 days during initial startup. Trial runs take about
2 weeks to complete, after which full-scale operations may
begin. Shakedown costs are assumed to constitute about 30
percent of total startup costs, which total about $45,000.
4.3.5 Labor Costs
Labor costs include the total staff needed for startup,
O&M of the LT3* system. Startup costs were discussed in
the previous section. Labor wage rates, which include
overhead and fringe benefits, are discussed below.
Unless air permits or local requirements dictate
otherwise, the LT3® system will be operated during two 12-
hour shifts, 7 days per week in order to avoid shutting down
the system. System shutdown should be avoided because it
takes about 12 hours for the unit to reach treatment
temperatures. Each shift will have three operators ($27 per
hour), one site manager ($45 per hour), one maintenance
supervisor ($30 per hour), and one site safety officer ($30
per hour). The site safety officer will work during the first
shift and as needed during the second shift. In addition,
part-time project management and office support may be
needed.
4.3.6 Consumable Material Costs
Consumable material costs include the costs of PPE,
drums for used PPE and residual wastes, activated carbon
for off-gas vapor and liquid treatment, diesel fuel for heavy
equipment, and calibration gases for air monitoring
equipment. The quantities of all consumables will depend
on the amount of soil treated.
PPE includes hard hats, safety glasses, respirators, and
disposable protective clothing. Disposable clothing is worn
by three operators who change PPE four times per shift,
costing about $200 per day. Used PPE fills about one 24-
gallon fiber drum per shift, costing about $12.30 per drum,
or $25.00 per day.
The LT3® system typically generates residual wastes such
as dust and spent carbon, both of which require containers
and proper off-site disposal. Dust is removed from the
baghouse about once per shift and is collected in 55-gallon
drums. For the ADC site, about one 55-gallon carbon-steel
drum of dust is generated for every 12.5 tons of soil treated.
Drums cost about $15 each.
The vapor-phase carbon adsorption unit is exhausted
every 10 days of operation and is replaced with a new one.
The vapor-phase carbon adsorption unit contains 1,800
pounds of activated carbon and costs $5,000. Beginning hi
the third month of operation, a monthly service charge of
$420 is incurred for covering the costs of handling spent
carbon and maintaining the unit. Transportation costs for
carbon adsorption units are included in the round-trip freight
charges between Pittsburgh, Pennsylvania, and the site. The
carbon vendor will either dispose of or regenerate the
carbon, the cost of which is included in the cost of the unit.
The liquid-phase carbon adsorption unit is exhausted
every 14 days of operation and is replaced with a new one.
The liquid-phase carbon adsorption unit contains 165 pounds
of carbon and costs about $4,200, plus round-trip freight
charges between Pittsburgh, Pennsylvania, and the site.
Costs can vary by up to $200 for the liquid-phase unit,
depending on the type of carbon used. The rate of carbon
use depends on contaminant types and concentrations.
Vapor-phase carbon adsorption units are needed only during
treatment activities.
Diesel fuel is used to operate all heavy equipment. Fuel
costs are site-specific and will vary depending on the market
price of diesel fuel and the extent of equipment usage at the
28
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site. At the ADC site, about 250 gallons of diesel fuel were
used per week.
Cylinders of CO, O2, CO2, and total hydrocarbon gases
are needed to calibrate LT3® air monitoring equipment.
Each cylinder of gas costs about $200 and is replaced every
3 weeks. The LT3® system requires calibration once per day.
4.3.7 Utility Costs
Utilities used by the LT3® system include natural gas,
electricity, and water. This analysis assumes that natural gas
lines will be available at the site. The LT3® heating unit
generates 6 million Btu/hr and is usually powered with
natural gas, propane, or oil. For soils with a 45 percent
moisture content, about 38,000 cubic feet of natural gas is
used to process about 2.1 tons of soil each hour. About 7
tons of soil are processed per hour for soils with a 20
percent soil moisture content. Assuming current market
conditions, natural gas costs about $1.43 per 1,000 cubic feet.
Therefore, for soils with 45 percent moisture content, natural
gas usage costs about $25.88 per ton treated. For soils with
20 percent soil moisture content, using natural gas costs
about $7.80 per ton treated.
Electricity runs the rest of the LT3® system. The system
is estimated to consume 8,750 kilowatt-hours (kWh) per
week when operating at 70 percent capacity (Weston, 1986).
Electric costs per Kilowatt-hour (kWh) vary depending on
local utility rates. For this analysis, power is assumed to cost
$0.18 per kWh. Therefore, electricity costs about $6.30 per
ton of soil with a 45 percent soil moisture content, and about
$2.10 for soils with a 20 percent soil moisture content. Total
electric power requirements depend on the amount of soil
treated.
To eliminate fugitive dust emissions at the ADC site,
about 2 gpm of potable water is sprayed on treated soil.
This action requires about 60 gallons of water per ton of
soil. Water costs are estimated to be $0.01 per gallon
(Weston, 1986). Therefore, water costs about $0.60 per ton
of soil treated. This cost can vary by as much as 1,000
percent, depending on the geographic location of the site,
availability of water, and distance to the nearest water main
or uncontaminated well (EPA, 1991b). In future application,
it is anticipated that condensate wastewater can be treated
sufficiently to allow it to be used for additional dust control.
4.3.8 Effluent Monitoring Costs
Effluent monitoring costs include costs associated with
air emissions monitoring for compliance with air permit
limits. Monitoring treated off-gas vapors emitted to the
atmosphere is part of the LT3® system and is accounted for
in the rental cost of the system. The only variable affecting
these costs is the cost of calibration gas. Gas costs are
included hi supply and consumable costs (see Section 4.3.6).
In addition, condensate could possibly be discharged to a
publicly owned treatment works, which would require a
NPDES permit. This permit would increase permitting and
regulatory costs as well as effluent monitoring costs.
4.3.9 Residual Waste Shipping, Handling, and
Transportation Costs
Disposal-related costs include costs associated with the
disposal of carbon adsorption units, PPE, and other
residuals, such as oversized material, drums of fabric filter
dust, and wastewater. These costs depend on geographic
location, distance to disposal sites, and site-specific soil
conditions. Transportation costs for carbon adsorption units
are included hi the round-trip freight charges between
Pittsburgh, Pennsylvania, and the site. The carbon vendor
will either dispose of or regenerate the carbon, the cost of
which is included in the cost of the unit.
Wastes drummed or containerized on site include PPE,
oversized material, and fabric filter dust. Approximately one
24-gallon drum of PPE is generated during each 12-hour
shift. The disposal cost is $150 per drum or $300 per day.
Drums of PPE are assumed to be transported by truck to
disposal facilities. Oversized material is estimated to be 2
percent of feed soil. The cost for disposing of oversized
material is assumed to be $270 per ton. The material will be
transported off site in the 40-cubic-yard roll-off container it
is collected in. Filter dust at the ADC site is generated at a
rate of two 55-gallon drums per 12-hour shift. Disposal
costs are estimated to be $150 per drum or $600 per day.
For soil with a 45 percent moisture content, about 57
gallons of wastewater is generated per ton treated.
Wastewater is stored on site until it is transported off site by
5,000-gallon tanker trucks, approximately every other day.
Transportation and disposal costs will average about
$0.24 for every gallon of water generated. Soils with a
20 percent soil moisture content will generate about half as
much water. For future applications, it is anticipated that
filter dust can be recirculated into the system, and
wastewater can be used for dust control. The actual amount
and type of residuals generated will vary from site to site.
For example, soils containing fewer fine particles will
generate less dust.
4.3.10 Analytical Costs
A treatability study will need to be performed to
determine the temperature requirements and residence times
of soil to be treated. This study is estimated to cost $30,000.
Continuous air monitoring of stack emissions is included in
the rental cost of the LT3® system.
During the ADC SITE demonstration, all samples were
shipped off site and analyzed only for the contaminant of
concern. Analytical samples typically consisted of one VOC
29
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sample shipment per shift, at a cost of approximately $210
per shipment. Total analytical costs depend on the number
and types of analyses that must be conducted and the site-
specific contaminants of concern. For example, if four
contaminants of concern by using only one technique,
analytical costs will be significantly reduced. VOC analyses
cost about $210 per sample; SVOC analyses cost about $440
per sample.
4.3.11 Equipment Repair and Replacement Costs
Maintenance labor has been included in labor costs (see
Section 4.3.5). Maintenance material costs are assumed to
be 90 percent of total rental costs. Costs for design
adjustment, facility modifications, and equipment
replacements are assumed to be incurred by Weston.
4.3.12 Site Demobilization Costs
Site demobilization includes LT3® shutdown and
disassembly, site cleanup and restoration, rental equipment
return, and disconnection of utilities. These activities will
require a crew of six. Complete site demobilization is
assumed to take about 3 weeks and costs $100,000.
References
Canonie Environmental Services Corporation, 1990,
Treatability Study Report and Remedial Contracting Services
Proposal (September).
Evans, G., 1990, Estimating Innovative Technology Costs
for the SITE Program, Journal of Air and Waste
Management Association 40:7 (1047-1051).
Larock, R., 1989, Comprehensive Organic
Transformations: A Guide to Functional Group
Preparations. VCH Publishers, Inc., New York, NY.
Ravenswood Disposal Services, 1992, Telephone
Conversation between Lenora Rodriguez and Jeffrey Swano,
PRC (May 20).
Roy F. Weston, Inc. (Weston), 1986, Economic
Evaluation of Low Temperature Thermal Stripping of
Volatile Organic Compounds from Soil, Report No.
AMXTH-TE-CR-86085 (August).
Weston, 1992, Telephone Conversation between Al
Murphy and Jeffrey Swano, PRC (July 3).
U.S. Environmental Protection Agency (EPA), 1980,
Dioxins. Prepared by M. P. Esposito, T. O. Tiernon, and
F.E. Dryden, EPA/600/2-80-197, Cincinnati, Ohio
(November).
EPA, 1988, CERCLA Manual on Compliance with
Other Laws, Interim Final, OSWER, EPA/540/G-89/006.
EPA 1991a, Toxic Treatments, In Situ Steam/Hot-Air
Stripping Technology, Applications Analysis Report.
EPA/540/A-90/008 (March).
EPA, 1991b, E. I. DuPont De Nemours &
Company/Oberlin Filter Company Microfiltration
Technology, Applications Analysis Report. EPA/540/A5-
90/007 (October).
Stumm, W. and J.J. Morgan, 1981, Aquatic Chemistry.
Second Edition, John Wiley & Sons, Inc., New York, NY.
Versar, 1983, Exposure Assessment for 4,4'-
methylenebis (2-chloroaniline) (MBOCA), Final Report.
30
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Appendix A
Developer's Claims
This appendix summarizes claims made by the developer
Roy F. Weston, Inc. (Weston), regarding its low temperature
thermal treatment (LT3®) system. The information
presented therein represents the developer's point of view
and does not constitute U.S. Environmental Protection
Agency (EPA) approval or endorsement of the statements
made in this appendix.
A.I Introduction
The Weston LT3® system is a patented process (U.S.
Patents No. 4,738,206 and 5,072,674) used to remove volatile
and semivolatile organic compounds (VOC and SVOC) from
a variety of solid matrices, including soil, sludge, and
sediments. The LT3® system desorbs or evaporates
contaminants from the solid matrix using an indirect heat
exchanger. The main part of the heat exchanger is a hollow-
flight screw conveyor. Volatile contaminants and moisture
are evaporated from the solid matrix and drawn into an air
emission control system under vacuum. The air emission
control system collects contaminants using a series of
condensers and adsorbers.
A.2 Potential Application
The LT3® system can be used to treat solid matrices
contaminated by a variety of VOCs and SVOCs. The LT3®
system has been used to treat soil contaminated with
chlorinated solvents, nonchlorinated solvents, fuel-derived
hydrocarbons, polynuclear aromatic hydrocarbons, and
chlorinated anilines. Following treatment, solids may
typically be backfilled on site.
The LT3® system is typically mounted on a truck to
facilitate mobility. However, fixed facility operations are
possible and, in specific cases, are more cost effective than
mobile operations, particularly for large sites or facilities that
continually generate wastes. Remedial activities conducted
under the Superfund or Underground Storage Tank (UST)
programs have been successfully completed using the mobile
LT3® system.
Resource Conservation and Recovery Act (RCRA)
classified wastes have been treated in bench- and pilot-scale
tests. Following treatment, solid residuals have complied
with federal Land Disposal Regulations (LDR). RCRA
wastes can be treated by using the mobile system or by
constructing fixed facilities when handling routinely
generated solid wastes.
Prior to application, a bench-scale test should be
performed to determine the technology's ability to meet
cleanup criteria and to establish the operating conditions
necessary. Bench-scale tests generally provide sufficient
information to develop full-scale processing systems. Weston
offers bench-scale testing through the Environmental Testing
Laboratory (ETL) in Lionville, Pennsylvania. The ETL has
a RCRA permit to receive and test hazardous waste samples
in order to determine their treatability.
A.3 System Advantages
The LT3® system offers the following advantages over
other remedial methods and thermal treatment systems:
• By heating soils to evaporate volatile contaminants
and moisture at temperatures well below the
combustion temperature associated with incineration
operations, the system operates with substantial fuel
and energy savings.
« Indirect heating of the soil reduces the quantity of
off-gas contacting the solid matrix and
contaminants. With gas flows 10 to 20 tunes
smaller than direct-fired desorbers or incinerators,
the emissions control equipment is greatly reduced
in size. Furthermore, the total amount of off-gas to
which the public could potentially be exposed is
greatly reduced.
« By controlling emissions using condensation and
carbon adsorption, the LT3® system can recycle
usable products, thus avoiding the generation of
harmful products of incomplete combustion that are
31
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sometimes associated with improperly operated
incinerators.
• The LT3® system can provide for retention times of
up to 90 minutes, as demonstrated at the Anderson
Development Company (ADC) site. These long
residence times are well above the residence times
possible in similar rotary-type desorbers and
incinerators.
• The hollow-flight screw conveyor provides
substantial mixing and breakdown of soil clumps.
Clay materials, which tend to ball and clump, are
broken down and handled readily by the LT3®
system.
A.4 System Limitations
The LT3* system has the following physical and chemical
limitations:
• The LT3* system is intended for ex situ treatment of
solids. Material that is excessively wet must be
dewatered or blended. All solid material must be
screened to remove material greater than 2 inches
in size. • Oversized material may be shredded or
crushed to meet this feed-restriction criterion.
• The LT3® system is designed to treat solids
contaminated by VOCs and SVOCs. While the
system's ability to treat metals has been tested, no
removal of metals has been observed.
A.5 Costs
The costs for applying the LT3® system are provided on
a lump sum basis for fixed costs, such as mobilization,
permits, and demobilization, and unit costs for solid
treatment. Costs are developed on a site-specific basis and
depend on (1) the quantity of solid to be treated, (2) the
contaminants in the solid, the (3) solid moisture content, and
(4) the location of the facility.
32
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Appendix B
SITE Demonstration Results
B.I Introduction
Since early 1991, the U.S. Environmental Protection
Agency (EPA) Superfund Technical Assistance Support
Team (START) and its Office of Research and
Development (ORD) have provided technical support to
EPA Region 5 in evaluating remedial options for the
Anderson Development Company (ADC) Superfund site in
Adrian, Michigan. EPA determined that low temperature
thermal desorption was an appropriate technology to treat
contaminated sludge at the site. The record of decision
(ROD) for the site stated that, following successful proof-of-
process testing, the Low Temperature Thermal Treatment
(LT3®) system developed by Roy F. Weston, Inc. (Weston),
could be used to remediate organic contaminants. Proof-of
process testing would be conducted under the EPA
Superfund Innovative Technology Evaluation (SITE)
program. The SITE demonstration of the LT3® technology
was conducted at the ADC site in November and December
1991, in a cooperative effort among ORD, EPA Region 5,
ADC, and Weston. This appendix briefly describes the ADC
site and summarizes the SITE demonstration activities and
results.
B.2 Site Description
The ADC facility covers approximately 12.5 acres within
a 40-acre industrial park. The facility is located on the
southeast side of Adrian, Lewanee County, Michigan. ADC
manufactures specialty organic chemicals. Between 1970 and
1979 it manufactured and sold 4,4' -methylenebis (2-
chloroaniline), also known as MBOCA or Curene 442. In
1979, sludge from the City of Adrian wastewater treatment
plant was found to be contaminated with MBOCA. The
source of this contamination was a lagoon at the ADC site.
In 1983, the ADC site was included on the National
Priorities List (NPL). A remedial investigation (RI), an
endangerment assessment (EA), and a feasibility study (FS)
were subsequently conducted by C.C. Johnson & Malhotra,
P.C. (CCJM, 1989).
~\
The RI indicated contamination of some surface soil in
the lagoon area, all the sludge in the lagoon, and some clay
on the side slopes of the lagoon and underneath the sludge.
MBOCA contamination in these areas exceeded the health-
based cleanup goal of 1.6 milligrams per kilogram (mg/kg),
as determined by the EA. Volatile organic compounds
(VOC), semivolatile organic compounds (SVOC) other than
MBOCA, and some metals were also detected, primarily in
the lagoon sludge and clay.
In September 1990, bench-scale tests conducted by
Canonie Environmental Services Corporation (Canonie)
determined that low temperature thermal desorption was a
viable remedial technology to remove MBOCA from the
ADC lagoon sludge and clay. Treatability study results
indicated that thermal desorption was capable of reducing
MBOCA concentrations in the lagoon sludge and clay to
below the cleanup goal of 1.6 mg/kg. Bench-scale tests were
conducted using treatment temperatures greater than 520 °F
and a residence time of 12.5 minutes. Because of scheduling
conflicts, Canonie could not perform the remediation of the
site. ADC contracted Weston to perform remedial activities
at the site using the LT3® system. Optimum operating
conditions were determined by Weston during shakedown
and startup operations before the SITE demonstration.
B.3 Contaminant Characteristics
MBOCA (CAS No. 101-14-4) is a yellow to light gray-
tan, nearly odorless, crystalline solid. The physical form of
MBOCA is granular, with a size range of 0.5 to 1.0
centimeters (cm). MBOCA is a member of the class of
compounds known as aromatic amines. The chemical
formula of MBOCA is CH2 (C6H3C1NH2)2. The structure of
MBOCA is presented below.
H,N
Cl
33
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The physical and chemical properties of MBOCA
determine its removal mechanisms during thermal treatment
in the LT3* system. MBOCA has a relatively low solubility
in water and an extremely low vapor pressure, ranging from
3.7x10"* to 5.4X10"5 torr over a broad temperature range.
Several values have been reported for its melting point,
ranging from 210.2 to 230 °F. Because MBOCA
decomposes at above 392 °F, physical and chemical
transformations may govern the fate of MBOCA during
thermal treatment. Two known degradation products
(metabolites) are N-acetyl-MBOCA (AC-MBOCA) and
N,N'-diacetyl-MBOCA (DAC-MBOCA) (Versar, 1983).
Sorption of MBOCA to organic material and clay
dominates its fate in soil and aquatic environments.
MBOCA is easily adsorbed by granular activated carbon.
Soil adsorption of two similar aromatic amines, aniline and
parachloroaniline, has been found to depend both on the
organic matter and the clay content of the soil. The cationic
bonding of MBOCA with soil may be irreversible.
Photooxidation and chemical oxidation may also be
important transformation processes in the atmosphere and
in the uppermost layer of soil and water systems.
Biodegradation of MBOCA has been demonstrated, and it
is probably effective in removing MBOCA from soil and
from wastewater with sufficiently acclimated microorganisms
(Versar, 1983).
B.4 Technology Demonstration Testing and
Sampling Procedures
The original experimental design for the SITE
demonstration test specified four test runs at optimum
conditions: two test runs for sludge and two test runs for clay
treatment. However,'much of the clay was excavated and
stockpiled together with the sludge, and a distinguishable
clay matrix could not be found. Therefore, to collect the
number of samples needed, three replicate tests for sludge
treatment were conducted the week of November 25, 1991.
Approximately 40 tons of contaminated material (13 for each
of three runs) were processed during the demonstration.
Each demonstration test required approximately 6 hours of
LT3* system operation. The residence time and the
temperature in the thermal processing unit were optimized
during Weston's shakedown period prior to the
demonstration. Table B-l summarizes the system's
operating parameters.
Sampling began when the system reached steady-state
conditions in terms of temperature and sludge flow rate.
For each run, sludge and liquid samples were collected every
30 minutes for the 6-hour test period. Stack gas samples
were collected over a period of about 4 hours during the
middle of each run.
During the demonstration, samples were collected from
six process points: (1) untreated sludge, (2) treated sludge,
(3) fabric filter dust, (4) condensate (5) exhaust gas before
the carbon unit, and (6) stack gas after the carbon unit.
Samples were also collected from the City of Adrian service
water line. Solid, liquid, and gas samples were analyzed for
the following critical parameters: MBOCA, VOCs, SVOCs,
dioxins, and furans. To trace the fate of chloride through
the system, samples were also analyzed for chloride, total
organic halide (TOX), and extractable organic halide (BOX).
Noncritical parameters were also analyzed to characterize
the feed and treated sludge. These parameters were metals,
toxicity characterisric leaching procedure (TCLP) metals,
particle size distribution, moisture, density, total organic
carbon (TOC), soil classification, available surface area, total
toxicity bioassay, California bearing ratio (CBR), and pH.
All sampling and analyses procedures met the requirements
of a EPA Category II quality assurance project plan (EPA,
1991).
After the first SITE demonstration, the truck carrying
gas samples and sample logbooks caught fire and burned
completely. Because the fire destroyed all stack samples for
particulate matter, VOCs, SVOCs, chloride, and moisture,
SITE demonstration tests had to be repeated. The second
SITE demonstration was performed the week of December
15, 1991.
The objective of the second SITE demonstration was to
collect liquid, solid, and gas samples for all contaminants
sampled in the gas phase. Sampling was performed for
VOCs, SVOCs, MBOCA, TOX, and chloride. All liquid and
solid samples were collected as daily composites, because
their purpose was primarily to correlate contaminant
concentrations in the gas, liquid, and solid phases.
Therefore, composite samples for each run were collected
and analyzed for each of the contaminants of concern. In
addition, liquid condensate samples were collected and
analyzed for pH. No sludge samples were collected for
dioxins and furans, because gas samples from the November
testing were not lost in the truck fire. Also, noncritical
parameters were not included in the December sampling
program.
B.5 Treatment Results
This section summarizes analytical results of the LT3®
system SITE demonstration and evaluates the system's
effectiveness in treating sludge contaminated with VOCs and
SVOCs. SITE demonstration results are based on extensive
laboratory analyses under rigorous quality control
procedures. Analytical results from all six replicate runs
(three in November and three in December) were analyzed
to determine the system's efficiency. The following sections
discuss (1) VOC removal, (2) MBOCA removal, (3) SVOC
removal, (4) the fate of chloride in the LT3® system, (5) the
formation and distribution of dioxins and furans, (6) the fate
34
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Table B-1 LT3® System Operating Conditions During SITE Demonstration
Equipment
Parameter
Value
Thermal Processor
Fabric Filter
Air-Cooled Condenser
Refrigerated Condenser
Vapor-Phase Carbon Units
Liquid-Phase Carbon Units
Oil-Water Separator
Temperature
Feed Material Flow Rate
Screw Rotational Speed
Residence Time
Air/Cloth Ratio
Cleaning Frequency
Ambient Air Temperature
Discharge Temperature
Empty Bed Velocity
Empty Bed Contact Time
Operating Temperature
Operating Humidity
Flow Rate
Surface Loading Rate
Empty Bed Contact Time
Surface Area Loading
Residence Time
Greater than 500 °F
2.1 tons/hour
0.73 to 0.76 rprn"
90 minutes
4.27
Every 15 to 30 seconds
20 to 30 °F
60 to 70 °F
55 fpmb
0.07 minutes
70 °F
70% RH°
See note d
See note e
a = rpm (revolutions per minute)
b = fpm (feet per minute)
0 = RH (relative humidity)
d = The liquid-phase carbon adsorption units were not used as part of the condensate liquid treatment system during the SITE
demonstration.
e = The oil-water separator did not operate during the SITE demonstration or subsequent remedial activities.
of metals in the LT3® system, (7) stack emissions, (8)
physical properties of sludge, and (9) lexicological properties
of sludge.
B.5.1 VOC Removal
For most VOCs present in untreated sludge, the LT3®
technology achieved residual concentrations below the
method detection limits, which for most VOCs were below
60 Aig/kg. Toluene and tetrachloroethene (PCE) were
identified as critical VOCs for the LT3® technology SITE
demonstration.
Toluene was present in untreated sludge at
concentrations ranging from 1,000 to 25,000 MgAg- The
concentration of toluene in treated sludge was below the
detection limit of 30 jig/kg. The concentration of toluene in
fabric filter dust ranged from less than 28 to 410 /tg/kg. For
most samples analyzed, the concentration of toluene in the
condensate was below the detection limit of 5 milligrams per
liter (mg/L). Toluene was detected in the off-gas before the
carbon column at concentrations ranging between 8,000 and
10,000 parts per billion by volume (ppbv), and was effectively
removed by the vapor-phase activated carbon column.
PCE was present in untreated sludge at concentrations
ranging from 690 to 1,900 jug/kg. The concentrations of
PCE in treated sludge and fabric filter dust were below the
detection limit of 30 jitg/kg for most samples analyzed. The
concentration of PCE in the condensate was below the
detection limit of 5 mg/L. PCE was detected in the off-gas
before the carbon unit at concentrations ranging from 210 to
220 ppbv; PCE was effectively removed by the vapor-phase
activated carbon column.
Toluene has a boiling point of 231.1 °F and PCE has a
boning point of 249.8 °F. Because of their low boning
points, toluene and PCE were apparently easily desorbed
from the sludge and remained hi the off-gas stream after the
air-cooled and refrigerated condensers. However, both
contaminants were effectively removed by the vapor-phase
activated carbon column.
B.5.2 MBOCA Removal
The LT3® system achieved MBOCA removal efficiencies
ranging from 79.8 to 99.3 percent, with MBOCA
concentrations in the treated sludge ranging from 3 to 9.6
mg/kg. MBOCA concentrations in untreated sludge ranged
35
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from 43.6 to 860 mg/kg. The decrease in MBOCA
concentration after treatment was accompanied by an
increase in the measured concentration of AC-MBOCA (see
Figures B-l and B-2), a known metabolite of MBOCA.
These results indicate that the removal of MBOCA is
probably due partially to thermal desorption and partially to
its conversion to AC-MBOCA. However, the presence of
co-eluting compounds may have interfered with the
quantitation of AC-MBOCA. The concentration of DAC-
MBOCA, another metabolite of MBOCA, decreased after
treatment for most samples analyzed, probably due to
removal mechanisms similar to those described for MBOCA.
MBOCA has a high tendency to sorb onto clay particles,
as indicated by its large adsorption coefficient of 1,500
(Versar, 1983). This tendency may have affected the LT3®
system's ability to completely remove MBOCA from the
sludge. MBOCA has a sublimation point of 240.8 to
251.6 °F, which is well below the treatment temperature of
above 500 °F. However, MBOCA was not completely
removed during treatment, probably because of its high
tendency to be sorbed onto soil particles. MBOCA
concentrations in the fabric filter dust were significantly
higher than MBOCA concentrations in the treated sludge,
which supports this hypothesis. MBOCA concentrations in
fabric filter dust ranged from 6.3 to 75 mg/kg. In addition,
MBOCA was detected in liquid condensate at concentrations
ranging from 100 to 257 micrograms per liter G*g/L)- No
MBOCA was detected in the exhaust gas from the
refrigerated condenser.
In fabric filter dust, the concentration of AC-MBOCA
is significantly higher than the concentration of DAC-
MBOCA. Apparently, MBOCA and DAC-MBOCA are
converted to AC-MBOCA during heating. However, AC-
MBOCA associated with small particles is not effectively
desorbed but remains attached to the small particles, which
are carried away in the sweep gas and are removed in the
fabric filter.
B.5.3 SVOC Removal
The LT3® system generally decreased the concentration
of SVOCs in treated sludge. 4-Methylphenol and bis(2-
ethylhexyl)phthalate were identified as critical analytes for
theLT3* system SITE demonstration. The concentrations of
3- and 4-methylphenol ranged from 3,100 to 20,000 /tg/kg in
the untreated sludge. After treatment, 3- and
4-methylphenol concentrations ranged from 540 to 4,000
/
-------
1,000
8 9 10 11 12 13 14 15
!•
MBOCA
Untreated
MBOCA Treated
Figure B-1 MBOCA Concentrations in Untreated and Treated Sludge
B.5.4 The Fate of Chloride in the LT3® System
The dehalogenation scenario discussed above is
supported by other demonstration results, which indicate that
treatment reduced the EOX concentration in sludge but
increased the chloride concentration. Figure B-5 shows the
reduced concentration of EOX after treatment. However,
the EOX concentration in the fabric filter dust was higher
than in the untreated sludge. This increase suggests that
EOX associated with small particles are not effectively
removed. Instead, they remain attached to the small
particles, which are carried away in the sweep gas and are
removed in the fabric filter or carried through to the
condensers. The concentration of TOX in the condensate
ranged from 25 to 73 mg/L, which was significantly higher
than the 0.3 mg/L TOX concentration in the city water.
Figure B-6 shows that the chloride concentration in
sludge increased after treatment, probably as a result of
chloride mineralization from dehalogenation reactions. The
concentration of chloride in fabric filter dust was also higher
than in the untreated sludge. The concentration of chloride
in the liquid condensate ranged from 7.5 to 92.4 mg/L.
The formation of HC1 during dehalogenation reactions
may have caused the reduction in the pH of treated sludge.
The pH of untreated sludge ranged from 10.9 to 11.2. The
pH of treated sludge ranged from 9.1 to 9.6. However, the
pH of the liquid condensate stream was alkaline, ranging
from 10.1 to 10.2. Alkaline pH could have resulted from
lime particles being carried away in the off-gas stream before
becoming dissolved in the condensate. The concentration of
HC1 in the exhaust gas from the refrigerated condenser was
below the detection limit of 0.034 milligrams per day
standard cubic meter (mg/dscm).
5.5.5 The Formation and Distribution ofDioxins
and Furans
Dioxins and furans were detected in process residuals.
Samples were analyzed for polychlorinated dibenzo(p)dioxins
(CDD) and polychlorinated dibenzofurans (CDF). Analytes
included2,3,7,8-tetrachlorodibenzo(p)dioxhi(2,3,7,8-TCDD)
and the following congeners:
Dioxins
tetrachloro dibenzo(p)dioxins (TCDD)
pentachloro dibenzo(p)dioxins (PeCDD)
hexachloro dibenzo(p)dioxins (HxCDD)
heptachloro dibenzo(p)dioxins (HpCDD)
octachloro dibenzo(p)dioxins (OCDD)
Furans
tetrachloro dibenzofurans (TCDF)
pentachloro dibenzofurans (PeCDF)
hexachloro dibenzofurans (HxCDF)
37
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8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
AC-MBOCA Untreated
AC-MBOCA Treated
Figure B-2 AC-MBOCA Concentrations in Untreated and Treated Sludge
hcptachloro dibenzofurnas (HpCDF)
octachloro dibenzofurans (OCDF)
The formation of dioxins and furans is encouraged by
sludge treatment conditions such as elevated temperature
(greater than 500 °F), the presence of chemical precursors,
alkaline pH, and a high concentration of free chloride (EPA,
1980). The following potential dioxin precursors were
present in untreated and treated sludge samples: 1,2-
dichlorobenzene; 4-chloroaniline; o-chloroaniline; aniline;
phenol; 4,6-dinitro-2-methylphenol; 2,4-dibromophenol; 2-
chlorophenol; 4-bromophenol; and 2,4-dibromophenol. As
stated above, alkaline pH resulted from lime being added to
the sludge. High concentrations of free chloride resulted
from adding ferric chloride to the sludge as a conditioning
agent before dewatering.
CDDs and CDFs were formed when sludge was treated
in the LT3* system. OCDD was the only congener found in
one sample of untreated sludge, at a level near the detection
limit [0.63 parts per billion (ppb) versus a detection limit of
0.54 ppb]. Table B-2 shows the arithmetic mean
concentrations of CDDs and CDFs in samples from each
location. Mean values were calculated by assigning zero to
all results reported as nondetectable (ND). As a result,
these mean values may underestimate CDD and CDF
concentrations.
Fabric filter dust consistently contained higher
concentrations of CDD and CDF than treated sludge, and
the dust was the only solid matrix containing measurable
amounts of 2,3,7,8-TCDD. No 2,3,7,8-TCDD was detected
in liquid condensate, but five of the 10 congeners were found
at measurable concentrations. TCDD and TCDF
predominated, with lower concentrations of PeCDD, PeCDF,
and HxCDF. As with the treated soil samples, tetra and
penta congeners were more prevalent.
The liquid condensate data suggest that TCDD and
TCDF, and possibly PeCDD, PeCDF, and HxCDF,
increased measurably with each successive run (see Table B-
3). The condensers were not cleaned between runs, and a
small amount of particulate matter may have accumulated
within the condensers. CDDs and CDFs are strongly
adsorptive, lipophilic, and only slightly water-soluble (EPA,
1980). The increasing concentrations of congeners may be
attributed to the release of CDDs and CDFs from
particulate matter within the condenser.
Vapor-phase activated carbon reduced all CDDs and
CDFs in the off-gas to less than 0.1 nanograms per dry
standard cubic meter (ng/dscm). The removal efficiency
varied with analyte, from 20 percent for HpCDD, to 100
percent (or to nondetectable levels) for PeCDF and
HxCDD.
38
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10 11 12 13 14 IS
3- & 4-Methylphenol Untreated
3- & 4-Methylphenol Treated
Figure B-3 3- and 4-Methylphenol Concentrations in Untreated and Treated Sludge
B.5.6 The Fate of Metals in the LT3® System
Untreated and treated sludge samples had similar metal
concentrations, which was expected because the LT3®
technology is not designed to remove metals. However,
metal concentrations in fabric filter dust were, in general,
greater than the concentration in untreated and treated
sludge. The results also showed that TCLP metal
concentrations were below detection limits.
B. 5.7 Stack Emissions
During the SITE demonstration, the total nonmethane
hydrocarbon concentration (TNMHC) in stack gas was
determined by separate analyses of samples collected in
SUMMA canisters. Analytical results showed that TNMHC
was 6.7 parts per million by volume (ppmv) during the first
run, 7.6 ppmv during the second run, and 11 ppmv during
the last run. Because a new vapor-phase activated carbon
unit was used during the SITE demonstration, the results
suggest that breakthrough occurred after a relatively short
period of time.
Similar observations were made during routine remedial
operations at the ADC site. As part of the LT3® system, a
continuous emissions monitoring (CEM) system was used to
monitor the total hydrocarbon concentration (THC). The
CEM system occasionally recorded THCs as high as 100
ppmv. To rectify the problem, Weston replaced the vapor-
phase carbon unit regularly. However, CEM results
indicaited that THC was below 10 ppmv for only about the
first 12 hours of operation of the new vapor-phase carbon
unit. After 12 hours, THC was significantly higher.
TNMHC includes both VOCs and SVOCs. VOC
emissions from the stack were predominately composed of
propylene and chloromethane. SVOC stack emissions did
not contain any predominant contaminants, and testing
indicated that all compounds were present in concentrations
at or below instrument detection limits.
The particulate concentration in the stack gas ranged
from less than S-SxlO"4 to 6.7xlO"3 grains per dry standard
cubic meter (gr/dsem) and the particulate emissions ranged
from less than 1.2x10* to 9.2X10"4 pounds per hour (Ib/hr).
The chloride concentration in the stack gas was below the
detection limit, which had an average value of 2.8xlO"2
mg/dscm.
In addition, during both the SITE demonstration and
remedial operations at the site, unusual levels of fugitive dust
emissions from the treated sludge pile area were occasionally
observed. During remedial operations, dust levels ranging
from 0.16 to 0.99 milligrams per cubic meter (mg/m3) were
recorded downwind of the treated sludge pile and in the
control trailer located near the treated sludge pile.
39
-------
12,000..
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Phenol Untreated j | Phenol Treated
figure B-4 Phenol Concentrations in Untreated and Treated Sludge
B.5.8 Physical Properties of Sludge
Untreated sludge consisted of wet, nonhomogeneous
clumps of soil. Processed sludge consisted of dry,
homogeneous, fine particles. Because of the decrease in
moisture content, the processed sludge had a tendency to
generate fugitive dust.
The following physical properties of the sludge were
determined: (1) particle size distribution, (2) soil
classification, (3) available surface area, (4) moisture
content, (5) density, and (6) CBR. Each of these properties
is discussed below.
Particle Size Distribution - The arithmetic mean
diameters of untreated sludge and fabric filter dust were
found to be 765 microns (/tm) and 34.12 /tm, respectively.
The size of the fabric filter dust particles is important for the
operation of the fabric filter, which is part of the LT3®
system. Also, the size of the fabric filter dust is important
to determine health risks associated with the inhalation of
the fabric filter dust during operations.
Soil Classification - According to the American Society
of Testing and Materials (ASTM) soil classification system,
untreated sludge was classified hi the A-7-6 soil group.
Typical characteristics of material in this group are plastic
clay soil with 75 percent or more of the particles smaller
than 75 u,m. in diameter, a minimum liquid limit of
41 percent, and a plasticity index above 11. Materials in this
group usually have a high-volume change between wet and
dry states.
Available Surface Area - The available surface area of
the untreated sludge ranged from 49.1 to 52.3 square meters
per gram (m2/g). These values are comparable to the
surface area of kaolinite, a clay material that has a reported
available surface area of 25 m2/g (Stumm and Morgan,
1981).
Moisture Content - The moisture content of the
untreated sludge (after dewatering) ranged from 41 to 44
percent. The moisture content of the treated sludge (after
conditioning) ranged from 7.5 to 23 percent.
Density - Treated sludge had higher maximum dry
densities than untreated sludge. Although no large changes
were observed, analytical results suggest that thermal
processing changed the sludge characteristics. In other case
studies, the density of the soil decreased after treatment
(Weston, 1986).
CBR - To determine the stability of the treated sludge,
CBR values were determined as a function of dry density at
10, 25, and 56 blows per layer of sludge sample. The results
indicated that CBR values increase as a function of dry
density. Treated sludge lacks moisture and is likely to
40
-------
150
Sample No.
EOX Untreated
[""""I EOX Treated
EOX Dust
Figure B-5 EOX Concentrations in Untreated and Treated Sludge and in Fabric Filter Dust
exhibit some instability. To obtain material with significant
bearing capacity and moderate stability, water needs to be
added and the moistened material needs to be compacted to
increase the material's density and stability. The level of
compaction required can be determined from the CBR
value.
B.5.9 lexicological Properties of Sludge
Toxicity tests were conducted on untreated and treated
sludge and sludge leachate samples. Sludge was tested using
the earthworm (Eisenia foetidd) as the test organism.
Leachate was tested using the fathead minnow (Pimephales
promelas) and the water flea (Ceriodaphnia dubia) as the
test organisms.
Four replicate tests of each sludge sample were
conducted with 10 worms per replicate. No dilutions were
conducted, and test results represented 100 percent test soil.
All the worms in the untreated and treated sludge died
within 48 hours. Therefore, a median lethal concentration
(LC50) could not be calculated from the data to determine
if untreated sludge was more toxic.
The mortality of the earth worms in untreated and
treated sludge samples was attributed to the alkaline pH of
untreated and treated sludge. The pH of untreated sludge
ranged from 10.9 to 11.2. The pH of treated sludge ranged
from 9.1 to 9.6. Subsequent to the SITE demonstration,
additional toxicity tests were conducted with untreated and
treated sludge at controlled pH and at different dilutions.
The sludge samples were diluted using artificial soil at 15,
25, 40, 60, and 100 percent. The pH was adjusted using
acidified artificial soil and HC1. The resulting pH of
untreated and treated sludge samples ranged from 7,4 to 8.7
at all dilutions ranging from 15 to 40 percent; at 60 and 100
percent dilutions, the pH ranged from 8.3 to 9.6. The 7-day
LC50 was 56.3 percent for untreated sludge and 76.3 percent
for treated sludge. The 14-day LC50 was 49.1 percent for
untreated sludge and 75.2 percent for treated sludge.
Therefore, at controlled pH, untreated sludge was more toxic
than treated sludge.
The results of the leachate toxicity study also suggest
that the LT3® technology reduces the toxicity of treated
materials. For the fathead minnows, toxicity was reduced
from a LC50 of about 40 percent in the untreated sludge
leachate sample to no toxicity in the treated sludge leachate
sample. For Ceriodaphnia dubia, toxicity was also
reduced. Only 15 percent of the test organisms exposed to
6.25 percent leachate solution from untreated sludge
survived. When the test organisms were exposed to a
solution of 100 percent leachate from treated sludge, 85
percent survived.
41
-------
20.000.
16,000.
12,000.
8,000..
4,000..
Chloride Untreated
['""" j Chloride Treated
Chloride Dust
Figure B-6 Chloride Concentrations in Untreated and Treated Sludge and in Fabric Filter Dust
References
C.C. Johnson & Malhotra, P.C. (CCJM), 1989, Final
Feasibility Study for Anderson Development Company,
Adrian, Michigan.
Larock, R., 1989, Comprehensive Organic
Transformations: A Guide to Functional Group
Preparations. VCH Publishers, Inc., New York, NY.
Merck, 1989, The Merck Index: An Encyclopedia of
Chemicals, Drugs and Biologicals. Eleventh Edition.
Roy F. Weston, Inc. (Weston), 1986, Installation and
Restoration General Environmental Technology
Development, Task 11. Pilot Investigation of Low
Temperature Thermal Stripping of Volatile Organic
Compounds from Soil, Volume 1 (June).
Stumm, W. and J.J. Morgan, 1991, Aquatic Chemistry.
Second Edition, John Wiley & Sons, Inc., New York, NY.
U.S. Environmental Protection Agency (EPA), 1980,
Dioxins. Prepared by M. P. Esposito, T. O. Tiernon, and
F.E. Dryden, EPA/600/2-80-197, Cincinnati, Ohio
(November).
EPA, 1991. Preparation Aids for the Development of
Category II Quality Assurance Project Plans, Risk Reduction
Engineering Laboratory, Cincinnati, Ohio,
EPA/600/8-9/1004 (February).
EPA, 1990. Methods Manual for Compliance with BIF
Regulations. Office of Solid Waste, Publication No.
EPA/530-SN-91-010.
Versar, 1983. Exposure Assessment for 4,4'-
methylenebis (2-chloroaniline) (MBOCA). Final Report.
42
-------
Table B-2 Arithmetic Mean Concentrations of CDDs and CDFs
Sampling Location
Parameter
2,3,7,8-TCDD
TCDD
TCDF
PeCDD f
PeCDF
HxCDD
HxCDF
HpCDD
HpCDF
OCDD
OCDF
Untreated
Sludge
ng/kg
(PPb)
0
0
0
0
0
0
0
0
0
0.21
0
Treated
Sludge
ng/kg
(PPV
0
0.987
2.42
0.534
0.066
0
0
0
0
0
0
Filter Dust Liquid Exhaust Gas from
Condensate Refrigerated
Condenser
ng/kg ng/L
(ppt>) (ppt) ng/dscm
0.10
6.54
19.80
5.98
2.49
0.81
0.50
1.38
0.14
3.20
0.04
0
119.0
697.0.
60.0
47.7
0
2.8
0
0
0
0
0.010
0.137
"''"''. 0.178
0.20
0.14
0.0020
0.0004
0.023
0.005
0.121
0.0067
Stack Gas
ng/dscm
0.0010
0.0087
0.066
0.0089
0
0
0.0003
0.017
0.0012
0.025
0.0024
All CDDs and CDFs not detected are assigned a value ofO.
Detection limits in untreated sludge ranged from 0.04 to 0.80 nanograms per gram (ng/g). Detection limits in treated sludge
ranged from 0.07 to 1.6 ng/g. Detection limits in fabric filter dust ranged from 0.14 to 9.6 ng/g. Detection limits in the liquid
condensate ranged from 1.4 to 17 ng/L.
ng = nanogram
ppt = parts per trillion
43
-------
Table B-3 Liquid Condensate Concentrations (ppt) Averaged by Run '
Parameter1'
Run 1
Run 2
Run 3
TCDD
TCDF
PeCDD
PeCDF
HxCDF
11
0.92
0
0
0
67
490
0
23
0
280
1600
180
120
8.4
a = CDDs and CDFs not detected were assigned a value of zero.
b = HxCDD, HpCDD, HpCDF, OCDD, and OCDF were not detected in liquid
condensate samples.
44
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Appendix C
Case Studies
This appendix summarizes case studies on the use of the
Low Temperature Thermal Treatment (LT3®) system. These
case studies were written and provided by Roy F. Weston,
Inc. (Weston). During the development of the LT3® system,
Weston conducted tests at the bench- and pilot-scale and
collected treatability data for the following contaminants:
coal tar, drill cuttings (oil-based mud), leaded and unleaded
gasoline, No. 2 diesel fuel, JP4 jet fuel, petroleum
hydrocarbons, halogenated and nonhalogenated solvents,
volatile organic compounds (VOC), semivolatile organic
compounds (SVOC), and polynuclear aromatic hydrocarbons
.(PAH). Weston also completed a full-scale remediation
using the LT3® system. The information available for these
case studies ranged from detailed analytical data to relatively
little information on system performance and cost. Results
from the following five case studies are summarized in this
appendix:
Case Study Site and Location
C-l
C-2
Confidential Site, Springfield, Illinois
Tinker Air Force Base, Oklahoma City,
Oklahoma
C-3 Letterkenny Army Depot, Chambersburg,
Pennsylvania
C-4 Environmental Technology Laboratory,
Lionville, Pennsylvania
C-5 Bench-Scale LT3® Test, Colorado Springs,
Colorado
Case Study C-l
Project: LT3® for Petroleum Contaminated Soil
Client: Confidential
Site: Confidential, Springfield, Illinois
Project Description
While renovating an existing building, several leaking
underground storage tanks, previously holding No. 2 fuel oil
and gasoline, were discovered. Weston was awarded the
contract to process the contaminated soil in the LT3® system.
Approximately 1,000 cubic yards of material were excavated
and processed. The objective was to render the soil suitable
for on-site backfill and eliminate the need for transportation
and off-site disposal in a special waste landfill.
Initial concentrations of contaminants were less than
1,000 parts per million (ppm). Stringent cleanup objectives
were established by the Illinois EPA for benzene, toluene,
ethylbenzene, xylene, and naphthalene. In addition, clean-up
objectives for 15 separate PAHs were established at below
the detection limit of 330 parts per billion (ppb).
The Illinois EPA also established stringent air emission
limitations that included the following:
• Carbon monoxide (CO) less than 100 ppm
• Total hydrocarbons less than 100 ppm
• No visible dust emissions
• Development of detailed test and safety plans
• Environmental permitting including air, operating,
and landfill permits for residual material not
suitable for processing (concrete, scrap metal,
oversize rock)
• Excavation and tank removal
• Mobilization of the LT3® system
• Operating of the LT3® system including process
sampling
• Clean soil storage in covered stockpile
• Analysis of soil to confirm that it is clean
• Site closure
45
-------
Results
One thousand cubic yards of contaminated soil were
successfully processed, and all cleanup objectives were met.
Table C-l summarizes analytical results. Processed soil was
approved by the Illinois EPA for on-site backfill. Stack
emissions were in compliance with all state and federal
regulations. Fugitive emissions of dust and organic vapors
were well controlled, with no complaints from residents
located as close as 100 yards away from the LT3® system.
Case Study C-2
Project: LT3® Processing of Soils Contaminated with
Chlorinated Solvents and JP4 Jet Fuel
Client: U.S. Army Toxic and Hazardous Materials
Agency (USATHAMA)
Site: Tinker Air Force Base, Oklahoma City,
Oklahoma
Project Description
In a continuing effort to identify and evaluate new and
innovative technologies for remediation of Department of
Defense (DOD) sites, USATHAMA wanted to perform a
full-scale demonstration of the LT3® system. The LT3®
system had already been proven effective in the pilot-scale
during a field demonstration at Letterkenny Army Depot.
The objective of the test would be to determine optimum
operating conditions and maximum feed rates for feed soil
contaminated with a wide variety of compounds, including
chlorinated solvents, semivolatile organics, and JP4 aviation
fuel (all common contaminants at DOD installations).
Following a comprehensive search of remedial investigation
reports, Tinker Air Force Base (Tinker AFB) was selected
as the site for the full-scale demonstration. Tinker AFB was
selected because of the wide variety of contaminants present
and the plastic clay soil matrix which provided a "worst case"
test regarding material handling and contaminant removal.
Weston was awarded the task of performing the
demonstration project at Tinker AFB. Weston excavated the
existing clay and asphalt cap from the previously closed
landfill. A total of approximately 3,000 cubic yards of
contaminated soil was excavated for treatment during the
demonstration program. Concentrations of trichloroethene
(TCE) in the contaminated soil were as high as 6,100 ppm.
Other significant contaminants included chlorinated organics
(for example, dichlorobenzene) and JP4 aviation fuel.
Weston Scope of Work
• Preparation of all advance plans, including the
following:
Detailed Test Plan
Sampling and Analysis Plan
All environmental permitting including a
RCRA RD&D Permit from U.S. EPA,
Region 6
Health and Safety Plan
• Site preparation and waste excavation
• Mobilization and operation of the LT3® system
• Analysis of soil samples in on-site laboratory
• LT3® system demobilization, decontamination, and
site closure
Results
• The LT3® system reduced the concentrations of all
target contaminants below the goal cleanup levels
and in most cases to less than detection limits.
• The above excellent performance was accomplished
while operating at processing rates as high as 20,000
Ib/hr, which was 33 percent higher than the design
feed rate.
• As a result of this program, estimated costs for
LT3® treatment have been significantly reduced due
to the ability to successfully operate at significantly
increased soil feed rates.
Case Study C-3
Project: LT3® for VOC-Contaminated Soil
Client: USATHAMA
Site: Letterkenny Army Depot, Chambersburg,
Pennsylvania
Project Description
Contamination of soils from past operations involving
VOCs has become one of the preeminent environmental
concerns at several U.S. Army installations. TCE is the
most frequently found contaminant; however, other VOCs
such as dichloroethene, tetrachloroethene, and xylene have
also been found. If allowed to remain in the soil, these
contaminants can migrate to underlying ground water.
USATHAMA contracted with Weston to develop an
innovative solution to this problem. The contract called for
the demonstration of a new technology on a pilot scale at a
site contaminated with VOCs.
46
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Table C-1 Results of Full-Scale Cleanup of No. 2 Fuel Oil and Gasoline-Contaminatad Soil*" b
Contaminant
Benzene
Toluene
Xylenes
Ethyibenzene
Napthalene
Carcinogenic Priority
PAHs
Benzo(a)-
anthracene
Benzo(a)pyrene
Benzo(b)-
fluoranthene
Chrysene
Dibenzo(a,h)-
anthracene
Noncarcinogenic
Priority PAHs
Acenaphthene
Acenaphthalene
Anthracene
Benzo(g,h,i)-
perylene
Benzo(k)-
fluoranthene
Fluoranthene
Fluorene
ldeno(1,2,3-c,d)-
pyrene
Phenanthrene
Pyrene
Boiling
Point
(°F)
176
231
291
277
,.424
850
923
896
875
975
534
518
644
995
896
707
560
950
644
759
Feed Soil
Concentration
fob)
1,000
24,000
110,000
20,000
4,900
<6,000
< 6,000
< 6,000
<6,000
<6,000
890
1,200
2,700
<6,000
<6,000
< 6,000
4,900
< 6,000
2,400
<6,000
Processed Soil
Concentration
(Ppt>)
5.2
5.2
<1.0
4.8
<330
<330
<330
<330
590
<330
<330
<330
<330
<330
450
<330
<330
<330
430
<330
Contaminant
Removal
Efficiency
(%)
99.48
99.98
> 99.999
99.98
>93.3
<94.5
<94.5
<94.5
00.2
<94.5
<62.9
<72.5
>87.8
<94.5
<92.5
<94.5
>93.3
<94.5
82.1
<94.5
Concentration In
TCLP Leachate
(ppb)
Not Analyzed
Not Analyzed
Not Analyzed
Not Analyzed
Not Analyzed
16J
4J
N/D
N/D
N/D
U
0.1 3J
3J
N/D
N/D
N/D
N/D
N/D
3J
N/D
a = Processed soil temperature was 350 °F.
b = Processed soil residence time was 70 minutes.
J = Present at less than detection limit.
N/D = Not detected; detection limit = 20 ppb.
47
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USATHAMA selected a site at the Letterkenny Army
Depot in Chambersburg, Pennsylvania. Weston responded
with the first LT3® system, much as it exists today. The
system incorporated a thermal process 10 feet in length.
Previous experience was limited to laboratory work with a
unit only 3 feet hi length.
Weston Scope of Work
• Design of the pilot system
• Preparation of test and safety plans
• Environmental permitting
• Equipment selection
• Installation, start-up, and test operation
• Demobilization and site closure
• Identification of full-scale design criteria
• Preparation of a technical report including
economics and auxiliary pollution control equipment
specifications
Results
More than 15,000 pounds of contaminated soils were
processed in 28 operating days. Table C-2 summarizes the
analytical results. A removal efficiency of more than
99.99 percent was demonstrated in the soil, and no VOCs
were detected hi the stack of the afterburner, indicating a
destruction and removal efficiency (DRE) of 100 percent for
the system.
Stack emissions were in compliance with all federal and
state regulations including VOCs, HC1, CO, and particulates.
Regulatory authorities allowed the disposal of processed
soil on site as backfill.
Case Study C-4
Project: LT3® Laboratory Testing of Contaminated Soil
Client: Various Industrial and Federal Clients
Site: Environmental Technology Laboratory in
Lionville, Pennsylvania
Project Description
Initially to prove the concept and now as a tool for
determining feasibility and predicting LT3® performance,
Weston has established a laboratory complete with a thermal
processor, sample storage and preparation facilities, and
analytical capabilities. Clients with environmental problems
that might be addressed with the LT3® system can send a
sample of the material to be processed to the laboratory
where testing will determine the feasibility and predict the
performance of the full-scale system.
Testing prior to mobilization of the full-scale system will
avoid the problems of trying to apply the system to
compounds and soils for which it is not suited. Process rates
can be determined and approximations of cleanup
capabilities can be made. Weston has tested a broad
spectrum of materials, but each contaminant behaves
differently in association with other compounds and with
differing soil types making testing of prime importance.
Weston Scope of Work
• Sample collection (if required)
• Sample preparation
• Initial feed soil analysis
• Preparation of a test and safety plan
• Test operation
• Data collection and analysis
• Return of sample material to client
• Final report including predictions of process rates
and cleanup capabilities
Results
A wide range of contaminants hi varying types of soils
and other host matrices have been successfully tested,
including VOCs, petroleum hydrocarbons, coal tars,
chlorinated solvents, a wide range of carcinogenic and
noncarcinogenic PAHs, and many SVOCs, such as xylene
and hexachlorobenzene. In addition Weston has:
• Proven concept feasibility for specific applications
• Developed standard testing and safety plans
• Established the capability to predict process rates
and levels of contaminant reduction
Weston has performance parameters for the generic
waste streams and specific compounds shown hi Tables C-3,
C-4 and C-5.
48
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Table C-2 Results of Pilot-Scale Demonstration on VOC-Contaminated Soil* b
Contaminant
Benzene
Trichloroethene
Tetrachloroethene
Xylene
Other VOCs
Total VOCs
Boiling
Point
(°F)
141
189
250
293
N/A
N/A
Feed Soil
Concentration
(PPb)
586,106
2,678,536
1,422,031
27,197,367
39,127
31,923,167
Processed Soil
Concentration
(PPb)
730
1,800
1,400
550
BDL
4,480
Contaminant
Removal
Efficiency
(%)
99.88
99.93
99.90
99.998
N/A
99.99
Concentration in
TCLP Leachate
(PPb)
Not Analyzed
Not Analyzed
Not Analyzed
Not Analyzed
Not Analyzed
Not Analyzed
' = Processed soil temperature was 320 °F.
* = Processed soil residence time was 60 minutes.
N/A = Not Applicable.
BDL = Below detection limit.
Case Study C-5
Project: Bench-Scale LT3® Test for Chlorinated Benzene
Contaminated Soil
Client: Confidential
Location: Colorado Springs, Colorado
Bench-scale studies were conducted at Colorado Springs,
Colorado, on soil contaminated with chlorinated benzene.
The soil was treated at 400 °F for a residence time of 44
minutes. The total concentration of contaminants was 530
mg/kg. Of that amount, 523 mg/kg was
1,4-dichlorobenzene, and the rest consisted of other
contaminants. Table C-6 summarizes the results. Removal
efficiencies greater than 99.9 percent were achieved.
49
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Table C-3 Results of Engineering Technology Laboratory6' b
Methylena Chloride
Acetone
n-Butanol
1,2-Dlchloroethane
1,2-D!chloropropane
Isopropanol
Methanol
Cyctohexane
Boiling
Point
(°F)
104
134
243
183
356
180
148
176
Feed Soil
Concentration
(PPb)
120,000
12,000
32,000
120
4,000
7,900
30,000
230
Processed Soil
Concentration
(PPb)
22
93
340
<5
<5
<100
<6,000
<10
Contaminant
Removal
Efficiency
(%)
99.98
99.2
98.9
>95.8
>99.9
>98.7
>80.0
>95.7
Concentration in
TCLP Leachate
(PPb)
<14
<473
< 1,200
<5
<5
< 1,700
<230
<10
* « Processed soil temperature was 250 °F.
b = Processed soil residence time was 45 minutes.
50
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Table C-4 Results of Bench-Scale LT3® Test on Coal Tar-Contaminated Soil* b
Contaminant
Benzene
Toluene
Ethylbenzene
Methyl Chloride
Napthalene
Carcinogenic Priority
PAHs
Benzofa)-
anthracene
Benzo(a)pyrene
Benzo(b)-
fluoranthene
Chrysene
Dibenzo(a,h)-
anthracene
Noncarcinogenic
Priority PAHs
Acenaphthene
Acenaphthalene
Anthracene
Benzo(g,h,i)-
perylene
Benzofk)-
fluoranthene
Fluoranthene
Fluorene
ldeno(1,2,3-c,d)-
pyrene
Phenanthrene
Pyrene
Boiling
Point
(°F)
176
231
277
106
424
850
923
896
875
975
534
518
644
995
896
707
560
950
644
759
Feed Soil
Concentration
(PPb)
<150
<150
78,000
14,000
1,200,000
100,000
82,000
45,000
96,000
9,600
28,000
28,000
160,000
38,000
46,000
192,000
222,000
31,000
580,000
275,000
Processed Soil
Concentration
(PPb)
<5.0
<5.0
<5.0
<5.0
1,200
2,100
1,600
1,700
4,400
<660
<660
<660
<660
790
1,800
6,500
<660
670
14,000
3,100
Contaminant
Removal
Efficiency
(%)
>96.7
>96.7
> 99.994
> 99.96
99.9
97.9
98.0
96.2
95.4
>93.1
>97.6
>97.6
>99.6
97.9
96.1
96.6
>99.7
97.8
97.6
98.9
. Concentration in
TCLP Leachate
(ppb)
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
a = Processed soil temperature was 400 °F.
= Processed soil residence time was 50 minutes.
N/D = Not detected; detection limit = 150 ppb.
51
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Tibia C-S Results of Bench-Scale IT*® Testing on Petroleum Hydrocarbon-Contaminted
Boiling Feed Soil Processed Soil
Point Concentration Concentration
Contaminant (°F) '
Oil and Grease
(BylR)
Napthalene
Carcinogenic Priority
PAHs
Benzofa>
anthracene
Bonzo(a)pyrene
Benzo(b)-
fluoranthene
Chrysene
D!benzo(a,h)-
anthracene
Noncarclnogenic
Priority PAHs
Acenaphthene
Acenaphthalene
Anthracene
Benzo(g,h,i)-
perylene
Benzoft)-
iluoranthene
Fluoranthene
Fluorene
ldeno(1,2,3-c,d)-
pyrane
Phenanthrene
Pyrene
Volatile Organic
Compounds
1, 1, 1-Trichloroethane
Other Parameters
Moisture
N/A
424
850
923
896
875
975
534
518
644
995
896
707
560
950
644
759
165
212
100,000 ppm
23,000 ppb
66,000 ppb
110,000 ppb
90,000 ppb
80,000 ppb
19,000 ppb
28,000 ppb
20,000 ppb
49,000 ppb
19,000 ppb
59,000 ppb
57,000 ppb
55,000 ppb
65,000 ppb
52,000 ppb
50,000 ppb
2,600 ppb
21.80%
170 ppm
< 330 ppb
<330 ppb
< 330 ppb
<330ppb
< 330 ppb
< 330 ppb
< 330 ppb
< 330 ppb
< 330 ppb
< 330 ppb
< 330 ppb
< 330 ppb
390 ppb
< 330 ppb
20 ppb J
< 330 ppb
<250 ppb
0.01%
Soil* b
Contaminant Concentration in
Removal Eff. TCLP Leachate
(%) (ppb)
99.82
> 98.57
> 99.50
> 99.70
> 99.63
> 99.59
> 98.26
> 98.82
> 98.35
> 99.32
> 98.26
> 99.44
> 99.42
99.29
> 99.49
99.96
> 99.34
> 90.38
99.95
N/A
1J
N/D
N/D
N/D
N/D
N/D
N/D
2J
1J
N/D
N/D
N/D
7J
N/D
N/D
N/D
N/D
N/A
* = Processed soil temperature was 450 °F.
b = Processed soil residence time was 30 minutes.
N/A ~ Not Applicable
J = Present at less than detection limit.
N/D - Not detected; detection limit = 20 ppb.
52
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Table C-6 Results of Bench-Scale LT3® Testing on Chlorinated Benzene-Contaminated Soil *• b
Contaminant
Benzene
Monochlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
1,2-Dichlorobenzene
1,2,4-
Trichlorobenzene
1,2,3-
Trichlorobenzene
1,2,4,5-
Tetrachlorobenzene
1,2,3,4-
Tetrachlorobenzene
Totals
Boiling
Point
176
270
343
345
357
416
424
475
489
N/A
Feed Soil Processed Soil Contaminant
Concentration Concentration Removal
Efficiency
(PPb) (PPb) (%)
106
318
1,219
524,859
1,431
477
636
530
424
530,000
0.01
0.03
0.35
6.25
0.85
0.22
0.06
0.03
0.05
7.85
99.991
99.991
99.97
99.999
99.94
99.95
99.99
99.994
99.99
99.999
Concentration in
TCLP Leachate
(PPb)
N/D
N/D
N/D
0.0064
0.0048
0.0011
N/D
N/D
N/D
N/A
a = Processed soil temperature was 400 °F.
b = Processed soil residence time was 44 minutes.
N/D = Not detected
N/A = Not Applicable
*U.S. GOVERNMENT PRINTING OFFICE: 1993-753-169
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