EPA-60G/R-97-116
October 1997
AIR EMISSIONS FROM THE
TREATMENT OF SOILS CONTAMINATED
WITH PETROLEUM FUELS AND OTHER SUBSTANCES
Prepared by:
Bart Eklund
Patrick Thompson
Adricnne Inglis
Whitney Wheeless
William Horton
Radian Corporation
P.O. Box 201088
Austin, Texas 78720-1088
EPA Contract No. 68-D2-0160, Work Assignment 2-62
and
Stephen Roe
E.H. Pechan & Associates, Inc.
2880 Sunrise Boulevard
Suite 220
Rancho Cordova, California 95742
EPA Contract No. 68-D3-0035, Work Assignment 11-92
EPA Project Officer:
Susan A. Thorneloc
Atmospheric Protection Branch (MD-63)
Air Pollution Prevention and Control Division
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Prepared for:
U.S. Environmental Protection Agency
Office of Air and Radiation
and
Office of Research and Development
Washington, DC 20460
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NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
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FOREWORD
The U. S. Environmental Protection Agency is charged by Congress with pro-
tecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions lead-
ing to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research
program is providing data and technical support for solving environmental pro-
blems today and building a science knowledge base necessary to manage our eco-
logical resources wisely, understand how pollutants affect our health, and pre-
vent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for
investigation of technological and management approaches for reducing risks
from threats to human health and the environment. The focus of the Laboratory's
research program is on methods for the prevention and control of pollution to air,
land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites and groundwater; and prevention and
control of indoor air pollution. The goal of this research effort is to catalyze
development and implementation of innovative, cost-effective environmental
technologies; develop scientific and engineering information needed by EPA to
support regulatory and policy decisions; and provide technical support and infor-
mation transfer to ensure effective implementation of environmental regulations
and strategies.
This publication has been produced as part of the Laboratory's strategic long-
term research plan. It is published and made available by EPA's Office of Re-
search and Development to assist the user community and to link researchers
with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
iii
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CONTROL TECHNOLOGY CENTER
Sponsored by:
Emission Standards Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Air Pollution Prevention and Control Division
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Technology Transfer and Support Division
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
iv
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ABSTRACT
This report updates a 1992 report that summarizes available information on air
emissions from the treatment of soils contaminated with fuels. Soils contaminated by leaks or
spills of fuel products, such as gasoline and jet fuel, are a nationwide concern. Air emissions
during remediation are a potential problem because of the volatile nature of many of the fuel
components and the remediation processes themselves, which may promote or result in
contaminant transfer to the vapor phase. Limited information also is included on air emissions
from the treatment of soils contaminated with hazardous wastes.
The report will allow staff from state and local regulatory agencies, as well as
staff from EPA regional offices, to assess the different options for cleaning up soil contaminated
with fuels. Seven general remediation approaches are addressed in this report. For each
approach, information is presented about the remediation process, the typical air emission species
of concern and their release points, and the available air emissions data. Control technologies for
each remediation approach are identified and their reported efficiencies are summarized. Cost
data are given for each remediation approach and for its associated control technologies.
Emission estimation methods (EEMs) for each remediation approach are presented along with a
brief case study. An uncertainty and sensitivity analysis was also prepared for each EEM.
A 1992 report was initially revised in 1995 in fulfillment of EPA Contract No.
68-D2-0160, Work Assignment 2-62, by Radian Corporation. The 1992 report also was prepared
by Radian Corporation.
This second revision to the 1992 report was prepared in 1996 in fulfillment of
EPA Contract No. 68-D3-0035, Work Assignment 0-92, by E.H. Pechan & Associates, Inc.,
2880 Sunrise Boulevard, Suite 220, Rancho Cordova, CA 95742.
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EXECUTIVE SUMMARY
This document summarizes the available information on air emissions from the
treatment of soils contaminated with fuels. It is intended to guide State and local air pollution
control agencies in the evaluation of the air emission potential of treatment of contaminated soil
and the cost-effectiveness of applicable emission control technologies. The scope was limited to
the emissions of volatile organic compounds (VOCs); however, because of the limited data that
were available, information was also included for the emissions of other organic compounds.
This additional information is primarily from the treatment of soils contaminated with hazardous
wastes.
Seven general approaches for the disposal or treatment of soils contaminated with
gasoline, oil, or diesel fuel were identified:
• Excavation and removal;
• Thermal desorption;
• Soil vapor extraction (SVE);
• In-Situ biodegradation;
• Ex-Situ biodegradation;
• Incineration; and
• Soil washing/solvent extraction/soil flushing.
Each general approach may include several specific options. For example, thermal desorption
may be performed in portable units designed specifically for soil treatment or in rotary drum
aggregate dryers that are part of asphalt plants or other industrial facilities.
Literature pertaining to the emissions of volatile organic compounds (VOCs) for
each remediation approach was identified and reviewed. The summarized information was
organized into the same ten part format for each approach:
• Process description;
• Identification of air emission points;
• Identification of typical air emission species of concern;
• Summary of published air emissions data;
• Identification of applicable control technologies;
• Cost data for the overall remediation approach;
• Cost data for the emission controls;
• Equations and models for estimating VOC emissions;
• Case study of the use of the remediation approach; and
• References.
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For most of the technologies examined, VOC emission estimates or measured data were found.
Emission factors, in grams per hour, were identified or developed that are based on available data
as well as assumed "typical" operating conditions for the remediation of relatively large sites.
Cost data, in dollars per ton or cubic yard of soil treated, were obtained from a variety of sources,
but data prior to 1986 were generally avoided because of the changes in remediation technology,
standard operating practices, and regulations in recent years. All cost data for years prior to 1991
were converted to 1991 dollars using a 5% annual escalation factor. Cost data for years
subsequent to 1991 are given on an as-is basis.
Certain limitations of the data presented in this document should be considered
before extrapolations are made to a specific site under consideration. Any generalized guidance
has inherent limitations due to the variety of site-specific and process-specific factors that may be
encountered. Many of the cleanup processes are emerging technologies and have short operating
histories. For these technologies, data on air emissions, treatment effectiveness, and costs are
very limited. Furthermore, each site has its own unique obstacles to cleanup that may force
modifications to the cleanup hardware or operating conditions. The development of typical air
emission rates and emission factors applicable to the maximum number of site conditions and
site locations required assumptions regarding the rate and scope of the cleanup effort, the type of
fuel being treated, the number and nature of emission release points, and so on. The more a
specific site differs from the assumed conditions, the less likely the generalized air emissions
data will be applicable.
In general, only limited information was found for air emissions from the
treatment of contaminated soil. The need for more data is greatest for emerging technologies and
those that are area sources of VOC emissions. The general needs are for more emissions data,
more control cost and effectiveness data, and data for the development of accurate emission
estimation methods (EEMs). The most important research needs that were identified during this
study were:
• VOC emission rate data for excavation;
• Improved EEMs to estimate VOC emissions from excavation; and
• Fate studies for VOCs in biotreatment systems.
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METRIC CONVERSIONS
Non-metric
Multiplied by
Yields Metric
MMBtu/hr
1054.35
MJ/hr (megajoule per hour)
°F
0.555556 (°F-32)
°C
ft
0.3048
m
acfm
0.028317
acmm
dscfm
0.028317
dscmm
gal
3.78541
L
hp
746
J/sec
in
2.54
cm
lb
0.453592
kg
mil
0.0254
mm
mile
1609.344
m
ton
0.907185
Mg (megagram), metric ton,
or 1,000 kg
yd3
0.76455
m3
yd2
0.8361
m2
vii
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TABLE OF CONTENTS
Page
ABSTRACT v
EXECUTIVE SUMMARY vi
METRIC CONVERSIONS vii
LIST OF FIGURES xii
LIST OF TABLES xiii
LIST OF ACRONYMS AND ABBREVIATIONS xvi
1.0 INTRODUCTION 1-1
1.1 Background 1-1
1.2 Objectives 1-1
1.3 Approach 1-2
1.4 Frequency of Use of Various Remediation Options 1-2
1.5 Limitations of the Document 1-5
2.0 SUMMARY OF RESULTS 2-1
3.0 EXCAVATION AND REMOVAL 3-1
3.1 Process Description 3-1
3.2 Identification of Air Emission Points 3-2
3.3 Typical Air Emission Species of Concern 3-2
3.4 Summary of Air Emissions Data 3-2
3.5 Identification of Applicable Control Technologies 3-7
3.6 Costs for Remediation 3-10
3.7 Costs for Emission Controls 3-11
3.8 Equations and Models for Estimating VOC Emissions 3-11
3.9 Case Study 3-14
3.10 References 3-14
4.0 THERMAL DESORPTION 4-1
4.1 Process Description 4-1
4.2 Identification of Air Emission Points 4-7
4.3 Typical Air Emission Species of Concern 4-8
4.4 Summary of Air Emissions Data 4-8
4.5 Identification of Applicable Control Technologies 4-12
4.6 Capital and Operating Costs for Remediation 4-16
4.7 Capital and Operating Costs for Emission Controls 4-17
4.8 Equations/Models for Estimating Emissions 4-17
4.9 Case Studies on Remediation and Air Emissions 4-20
4.10 References 4-22
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TABLE OF CONTENTS (Continued)
Page
5.0 SOIL VAPOR EXTRACTION 5-1
5.1 Process Description 5-1
5.2 Identification of Air Emission Points 5-5
5.3 Typical Air Emission Species of Concern 5-6
5.4 Summary of Air Emissions Data 5-6
5.5 Identification of Applicable Control Technologies 5-6
5.6 Costs for Remediation 5-10
5.7 Costs for Emission Controls 5-10
5.8 Equations and Models for Estimating VOC Emissions 5-12
5.9 Case Study 5-17
5.10 References 5-20
6.0 IN-S1TU BIODEGRADATION 6-1
6.1 Process Description 6-1
6.2 Identification of Air Emission Points 6-3
6.3 Typical Air Emission Species of Concern 6-4
6.4 Summary of Air Emissions Data 6-4
6.5 Identification of Applicable Control Technologies 6-4
6.6 Costs for Remediation 6-8
6.7 Costs for Emissions Controls 6-8
6.8 Equations and Models for Estimating VOC Emissions 6-8
6.9 Case Study 6-9
6.10 References 6-9
7.0 EX-SITU BIODEGRADATION 7-1
7.1 Process Description 7-1
7.2 Identification of Air Emission Points 7-7
7.3 Typical Air Emission Species of Concern 7-7
7.4 Summary of Air Emissions Data 7-9
7.5 Air Emission Controls 7-9
7.6 Costs for Remediation 7-9
7.7 Costs for Emissions Controls 7-12
7.8 Equations and Models for Estimating Air Emissions 7-12
7.9 Case Study 7-13
7.10 References 7-13
X
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TABLE OF CONTENTS (Continued)
Page
8.0 INCINERATION 8-1
8.1 Process Description 8-1
8.2 Identification of Air Emission Points 8-3
8.3 Typical Air Emission Species of Concern 8-3
8.4 Summary of Air Emissions Data 8-5
8.5 Identification of Applicable Control Technologies 8-10
8.6 Costs for Remediation 8-10
8.7 Costs for Emissions Controls 8-13
8.8 Equations and Models for Estimating VOC Emissions 8-13
8.9 Case Study: On-Site Incineration 8-14
8.10 References 8-14
9.0 SOIL WASHING, SOLVENT EXTRACTION, AND SOIL FLUSHING 9-1
9.1 Process Description 9-1
9.2 Identification of Air Emission Points 9-9
9.3 Typical Air Emission Species of Concern 9-9
9.4 Summary of Air Emissions Data 9-10
9.5 Identification of Applicable Control Technologies 9-10
9.6 Capital and Operating Costs for Remediation 9-10
9.7 Capital and Operating Costs for Emission Controls 9-10
9.8 Equations/Models for Estimating Emissions 9-10
9.9 Case Studies of Remediation and Air Emissions 9-10
9.10 References 9-15
10.0 UNCERTAINTY AND SENSITIVITY ANALYSIS 10-1
10.1 Introduction 10-1
10-2 Approach 10-1
10-3 Results 10-2
10-4 References 10-3
APPENDIX A: PROPERTIES AND COMPOSITION OF VARIOUS FUEL TYPES . . A-l
APPENDIX B: STATE CLEANUP REQUIREMENTS B-l
APPENDIX C: EXAMPLE CALCULATIONS C-l
APPENDIX D: DERIVATION OF VOC EMISSION MODEL FOR EXCAVATION . . D-l
APPENDIX E: ARTICLE ON SOIL VAPOR EXTRACTION E-l
APPENDIX F: ENGINEERING BULLETINS FOR TREATMENT PROCESSES ... F-l
APPENDIX G: ARTICLE ON INCINERATION G-l
APPENDIX H: UNCERTAINTY/SENSITIVITY ANALYSIS H-l
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LIST OF FIGURES
Page
1-1 Relative Frequency of Use of Remediation Technologies at UST Sites . . 1-3
1-2 Relative Frequency of Use at UST Sites by Specific Technology 1-4
1-3 Alternative Treatment Technologies Specified in Superfund Remedial
Action RODs from FY 1982 Through FY 1992 1-6
3-1 Summary of Air Emission Points for Excavation and Removal 3-3
4-1 Soil Treatment Temperature Guide 4-4
4-2 Generalized Process Diagram for Thermal Screw-Based
Thermal Desorption 4-6
5-1 Simplified Guide to Applicability of Soil Vapor Extraction 5-2
5-2 Generalized Process Flow Diagram for Soil Vapor Extraction 5-4
5-3 Process Flow Diagram for Terra Vac In-Situ Vacuum Extraction System . 5-18
6-1 Flow Diagram for Off-Gas Treatment System for In-Situ Biodegradation 6-2
7-1 Slurry Biodegradation Process Flow Diagram 7-3
8-1 Process Flow Diagram for Commercial Rotary Kiln Incinerator 8-2
9-1 Schematic Diagram of Aqueous Soil Washing Process 9-3
9-2 Schematic Diagram of Solvent Extraction Process 9-5
9-3 Generalized Soil Flushing Process Flow Diagram 9-8
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LIST OF TABLES
Page
2-1 Summary of Information for Remediation Technologies 2-2
2-2 Typical Control Technologies Used for Remediation Technologies 2-3
2-3 Summary of Cost Information for the Treatment of Contaminated Soil 2-4
3-1 Results of Emission Measurements at Gulf Coast Vacuum Site 3-5
3-2 Emission Rates Measured at the Westminster Superfund Site 3-6
3-3 Summary of Costs for Emission Controls for Area Sources 3-13
3-4 Input Variables for Emission Equations 3-15
4-1 Comparison of Features of Thermal Desorption and Offgas
Treatment Systems 4-2
4-2 Characteristics of Asphalt Aggregate Dryers 4-10
4-3 Estimated Emissions of Selected Compounds for the Cleanup of
PCB-Contaminated Soil Using the IT Process 4-13
4-4 Costs Including Emission Controls for Various Thermal Desorption Units .. 4-18
4-5 Cost Information for Thermal Oxidizers 4-18
4-6 Cost Information for Fabric Filters 4-19
4-7 Results for Use of LTTA System on Pesticide-Contaminated Soil 4-21
4-8 Results for Use of LT3 System on Lagoon Sludge 4-21
4-9 Results for Use of X*TRAX System to Treat PCB-Contaminated Soil 4-23
4-10 Results for Use of ATP Process to Treat PCB-Contaminated Soil 4-24
5-1 Summary of Emissions Data for SVE Systems 5-7
5-2 Summary of Capital Costs to Control VOC Emissions from SVE Systems .. 5-11
5-3 Summary of SVE Models Evaluated by the U.S. EPA 5-14
5-4 Estimated Emissions for Terra Vac's In-Situ Vacuum Extraction System . . . 5-19
xiii
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LIST OF TABLES (Continued)
Page
6-1 Summary of Removal Rates for Bioventing Systems 6-5
6-2 Summary of Source Emission Rates for Bioventing Systems 6-6
6-3 Summary of Surface Emissions at Bioventing Sites 6-7
7-1 Applicability of Slurry Biodegradation for Treatment of
Contaminants in Soil, Sediments, and Sludges 7-2
7-2 Desired Inlet Feed Characteristics for Slurry Biodegradation Processes 7-4
7-3 Performance Results for Slurry Biodegradation Process Treating Wood Preserving
Wastes 7-6
7-4 Summary of Performance Data for Biopile System 7-8
7-5 Summary of Emissions Data for Ex-Situ Bioremediation Systems 7-10
8-1 PICs Found in Stack Effluents of Full-Scale Incinerators 8-6
8-2 Dioxin/Furan Emissions from Thermal Destruction Facilities
(Ng/dscm @ 7% 02) 8-7
8-3 Recent Dioxin/Furan Emissions Data 8-9
8-4 Characteristics of Off-Gas from On-Site Incineration Systems 8-11
8-5 Estimated Range of Costs for Off-Site Incineration 8-12
8-6 Estimated Range of Costs for On-Site Incineration 8-12
9-1 Summary of Costs for Soil Washing and Solvent Extraction 9-11
9-2a Summary of Performance Data on Soil Washing 9-12
9-2b Results of Remediation of Soil Containing Fuel Oil Using Soil Washing ... 9-12
9-3a Results of Remediation of API Separator Sludge by Solvent Extraction .... 9-13
9-3b Results of Remediation of Drilling Mud Waste Using Solvent Extraction ... 9-13
9-4 Results of Remediation Using Soil Flushing 9-14
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LIST OF TABLES (Continued)
Page
10-1 Scenario Development for the Uncertainty/Sensitivity Analysis 10-4
10-2 Uncertainty/Sensitivity Analysis Results 10-5
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LIST OF ACRONYMS AND ABBREVIATIONS
AFB
Air Force Base
BTEX
Benzene, Toluene, Ethylbenzene, and Xylenes
BTU
British Thermal Unit
BTX
Benzene, Toluene, and Xylenes
CO
Carbon Monoxide
CSTR
Continuously-Stirred Tank Reactor
CTC
Control Technology Center
DAVES
Desorption and Vapor Extraction System
DOD
Department of Defense
EEM
Emission Estimation Method
EPA
Environmental Protection Agency
FTIR
Fourier-Transform Infrared
GAC
Granular Activated Carbon
HC1
Hydrochloric acid
HEPA
High Efficiency Particulate Air
IC
Internal Combustion
ICE
Internal Combustion Engine
LEL
Lower Explosive Limit
LTTA
Low-Temperature Thermal Aeration
LTTD
Low-Temperature Thermal Desorption
LUST
Leaking Underground Storage Tank
NA
Not Applicable
ND
Not Determined
NOx
Nitrogen Oxides
OUST
Office of Underground Storage Tanks
PAH
Polynuclear Aromatic Hydrocarbons
PCB
Polychlorinated Biphenyls
PCDD
Polychlorinated Dibenzodioxins
PCDF
Polychlorinated Dibenzofurans
PM
Particulate Matter
PNA
Polynuclear Aromatic
PVC
Polyvinyl Chloride
RCRA
Resource Conservation and Recovery Act
SVE
Soil Vapor Extraction
SVOC
Semi-Volatile Organic Compound
TCDD
Tetrachlorodibenzodioxin
TCE
Trichloroethylene
TEQ
Toxic Equivalent Quantity
THC
Total Hydrocarbons
TNMHC
Total Non-Methane Hydrocarbons
TPH
Total Petroleum Hydrocarbons
TTSD
Technology Transfer and Support Division (former CERI)
TVH
Total Volatile Hydrocarbons
xvi
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LIST OF ACRONYMS AND ABBREVIATIONS (CONTINUED)
UST Underground Storage Tank
UV Ultraviolet
VOC Volatile Organic Compound
xvii
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1.0 INTRODUCTION
1.1 Background
The Control Technology Center
(CTC) at the U.S. Environmental Protection
Agency (EPA) is responsible for supporting
State and local air pollution control agencies
in the implementation of their programs. As
part of this support, the CTC provides
assessments of the control technologies
available for reducing emissions from a
particular type of source. The CTC typically
provides expertise and information not
otherwise available to the State or local
agency.
The CTC has received requests from
State and local regulatory agencies, as well
as from EPA regional offices, regarding how
to assess the different options for cleaning
up contaminated soil. The requests have
addressed a number of specific remediation
techniques, such as the clean-up of soils
using rotary drum dryers. Information is
needed for estimating the potential air
emissions from various types of processes
and for determining what control options
may be appropriate. While some guidance is
currently available, it is dispersed among
multiple documents.
The purpose of this project was to develop a
procedure and guidance document for use by
State and local regulatory agencies for
evaluating the air emission potential and
applicable control technologies for the
treatment of contaminated soil. Radian
Corporation assisted the CTC in this effort.
The original document was prepared in 1992
under EPA Contract Number 68-DO-0125,
Work Assignment 25 and Contract Number
68-D1 -0117, Work Assignment 31. The
document was revised in 1995 under EPA
Contract Number 68-D2-0160, Work
Assignment 2-62. Existing guidance for
how to assess both potential air emissions
and available control technologies was
identified. Examples of different clean-up
operations were identified for soils
contaminated with gasoline, diesel fuel, or
fuel oil. In addition, information on the kind
of control technologies that are available and
their expected range of capital and operating
costs was obtained.
1.2 Objectives
The specific objectives of this
program were to:
• Identify options for the
disposal/treatment of soils
contaminated with gasoline, oil, or
diesel fuel;
• Review the available literature
pertaining to the emissions of
volatile organic compounds (VOCs)
for each clean-up option and
emissions of dioxins/furans from the
thermal treatment options;
• Summarize suggested approaches for
estimating the VOC emissions from
the various clean-up options;
• Identify applicable control
technologies and compile ranges of
capital and operating costs for each
technology; and
• Summarize the information in a
guidance document.
The clean-up options addressed in
this document are:
• Excavation and removal;
1-
1
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• Thermal desorption (includes asphalt
plants);
• Soil vapor extraction (SVE);
• In-Situ biodegradation;
• Ex-Situ biodegradation;
• On-site incineration; and
• Soil washing/solvent extraction.
1.3 Approach
The general approach was to perform
a literature search and telephone survey of
researchers and regulators. Several hundred
publications were reviewed and evaluated.
Contacts were made with researchers active
in the field to identify any new or emerging
information. Contacts also were made with
regulatory staff in California, Florida,
Louisiana, Maryland, Michigan, and Texas
to obtain any air emissions measurement
data submitted as part of permit
applications. These states were thought the
most likely to have such data, but no data
were found in this search.
For each of the identified remedial
options, the literature was reviewed to
develop a process flow diagram and identify
emission points, as well as to analyze
available air emissions data. For most of the
technologies examined, VOC emission
estimates or measured data were found.
Where VOC data were limited, data for
other types of organic compounds were
compiled. EEMS were identified or
developed based on available data as well as
assumed "typical" operating conditions for
the remediation of relatively large sites.
Cost data were obtained from a
variety of sources, but data from prior to
1986 were generally avoided due to the
changes in remediation technology, standard
operating practices, and regulations in recent
years. All cost data prior to 1991 were
converted to 1991 dollars using a 5% annual
escalation factor. All cost data published
after 1991 are reported with no correction.
1.4 Frequency of Use of Various
Remediation Options
The remediation options addressed in
this document are all potentially suitable for
use as part of the remediation process for
soils contaminated with fuels. The various
options, however, are not necessarily all
equally cost-effective nor is their use equally
widespread. EPA's Office of Underground
Storage Tanks (OUST) has surveyed state
agencies responsible for the cleanup of
leaking underground storage tank (UST)
sites to ascertain the frequency of use of
various remediation options. The
information is primarily derived from the
remediation of UST sites contaminated with
gasoline and dates from 1991. This
information is summarized in Figures 1-1
and 1-2.
Figure 1-1 shows the relative
frequency of use of the major classes of
remediation options. Land filling
(excavation and removal) is used somewhat
more than half the time, with in-situ
methods, thermal treatment, or land
treatment also frequently used. Figure 1-2
provides more detail as to the type of in-situ,
land treatment, and thermal treatment
methods employed. For sites employing in-
situ remediation, the exact technology used
is undefined the majority of the time. It is
1-2
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Land Treatment 11%
Figure 1-1. Relative Frequency of Use of Remediation Technologies at UST Sites.
Source: EPA-QUST (Due to rounding, figure may not total to 100%)
1-3
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In-Situ Technologies
Soil Vapor Extraction 9%
Bioremediation 2%
Undefined/Other 89%
Land Treatment Technologies
Landfarming 36%
Aeration 50%
Land Application 13%
Thermal Treatment Technologies
Thermal Desorption 39%
Asphalt Options 61%
Incineration 0.1%
Figure 1-2. Relative Frequency of Use at UST Sites by Specific Technology.
Source: EPA-OUST (Due to rounding, figures may not total to 100%)
1-4
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assumed that soil vapor extraction is
probably used in most of these cases. For
applications of thermal treatment, thermal
desorption is almost always employed and
incineration is only very rarely used.
The frequency with which various
treatment methods have been proposed for
use at Superfund sites is shown in Figure
1-3. Superfund sites may be contaminated
with a number of pollutants instead of or in
addition to petroleum fuels, such as heavy
metals, polychlorinated biphenyls (PCBs),
asbestos, and pesticides. Therefore, it is not
surprising that the frequency with which
various remedies are proposed for Superfund
sites differs from that for UST sites.
1.5 Limitations of the Document
The review of the available
information showed that the amount of data
is more limited than originally expected.
There is not adequate data on VOC air
emissions from remediation to assess the
importance of fuel type, spill volume, the
age of the spill, and the soil type as they
relate to the combination of remediation and
control technologies that are applied.
Therefore, there is insufficient data to
develop empirical step-by-step estimation
procedures and to assess the uncertainty
associated with such estimates.
In this document, the limited existing
information was compiled to provide users
with a summary of air emissions data.
Information is included for VOC air
emissions from the treatment of both soils
contaminated with petroleum fuels and the
treatment of hazardous waste to fill as many
data gaps as possible.
Generalized guidance for the
remediation of soils contaminated with fuels
has inherent limitations. Many of the
cleanup processes are "developing
technologies" and therefore have short
operating histories. For these technologies,
data on air emissions, treatment
effectiveness, and costs are very limited.
Furthermore, each site was its own unique
obstacles to cleanup that may force
modifications to the cleanup hardware or
operating conditions.
The development of typical air
emission rates and emission factors
applicable to the maximum number of site
conditions and site locations required
assumptions regarding the rate and scope of
the clean-up effort, the type of fuel being
treated, the number and nature of emission
release points, and so on. Assumptions were
based on what is "typical" and "reasonable"
for the remediation of relatively large sites.
Obviously, the diverse nature of sites with
fuel contamination will result in the
information presented here being more
applicable to some sites than others. A
limited data set must be used to generalize
about a wide-spectrum of process
conditions.
The VOC air emissions data
compiled in this document can be used for
planning purposes and for comparison to
permit applications, but the user must take
into account the inherent limitations of the
data and the limitations in extrapolating the
data to fit the specific remediation scenario
under consideration.
1
-5
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Established Technologies (335) 56%'2
Innovative Technologies (263) 44%1-2
Offsite Incineration
(92) 15%
Onsite Incineration
(68) 11%
Solidification/Stabilization
(165) 28%
Soil Washing (20) 3%
Solvent Extraction (5) <1%
Ex Situ Bioremediation (34) 6%
In Situ Bioremediation3 (26) 4%
In Situ Flushing (20) 3%
Soil Vapor Extraction
(107) 18%
Other established technologies4 (10) 2%
Chemical Treatment (3) <1%
Dechlorination (5) <1%
In Situ Vitrification (3) <1%
Thermal Desorption (32) 5%
Other innovative technologies5 (8) 1%
'Based on 504 RODs specifying a total of 598 treatment applications.
2The number of times a technology was selected is shown in parentheses,
includes 11 in situ ground-water treatment remedies.
""Other" established technologies are soil aeration, in situ flaming, and chemical neutralization.
5"Other" innovative technologies are air sparging, contained recovery of oily wastes, limestone
barriers, and fuming gasification.
Figure 1-3. Alternative Treatment Technologies Specified in Superfund Remedial Action
RODs from FY 1982 Through FY 1992.
Source: The Hazardous Waste Consultant: May/June 1994.
(Reprinted by permission of the publisher from "Use of Innovative Treatment
Technologies Is Increasing at Superfund Sites", The Hazardous Waste Consultant,
May/June 1994, p. 1.15, Copyright 1994 Elsevier Science Inc.)
1-6
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2.0 SUMMARY OF RESULTS
Information was compiled and
evaluated for six categories of remediation
technologies. Information about each
remediation technology is summarized in
Table 2-1. The remediation technologies
can be categorized as follows:
in-situ approaches
soil vapor extraction
in-situ biodegradation
soil flushing
ex-situ approaches
thermal desorption
ex-situ biodegradation
incineration
soil washing
solvent extraction
Information on excavation also is included
because the ex-situ approaches all require
that the contaminated soil be excavated and
fed to the treatment unit. The fugitive
emissions from the materials handling
operations for ex-situ processes often are
overlooked or ignored, but they may
represent a significant fraction of the total
emissions from the remediation effort.
A variety of control devices may be
employed with each of the remediation
technologies. The most commonly used
controls for each technology are shown in
Table 2-2.
Air emission data for each
remediation technology were compiled. The
reported data primarily are measured
concentrations in the exhaust gas or offgas
(i.e. mass/volume of air), but measured
emission rate data (mass/time) also are
available. There was not sufficient data to
develop meaningful VOC emission factors
based on starting soil contamination levels
for the remediation technologies of interest.
Typical treatment cost data are given
in Table 2-3 for treatment operations with
and without emission controls. The
emission factors are based on "reasonable"
operating conditions for the remediation of
sites contaminated with petroleum fuels, but
these estimates may not be applicable to
some clean-up programs. A range of costs
are given in most cases and these estimates
are considered to be the best available
information in the literature. The cost
estimates are not all based on the same
remediation scenario, so the data for a given
remediation technology may not be directly
comparable to the data for another
remediation technology because the
underlying assumptions of the volume of
contaminated soil, the types and mass of
contaminants that are present, the rate of
treatment, the type of controls employed,
etc. may vary.
2-1
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Table 2-1
Summary of Information for Remediation Technologies
Remediation
Technology
Emission
Points
Typical Air Emission
Species of Concern
Amount of
Air Emissions
Data
Frequency of Use
of
Controls
Comments
Excavation
Soil surface
VOCs, PM
Very limited
Seldom
Often overlooked,
Potential to be major air
emission source
Thermal
Desorption
Stack,
Waste feed
VOCs,
SVOCs
Extensive
Always
Usually performed with
mobile units
Soil Vapor Extraction
Stack
VOCs
Some
>50% of systems
May be converted to
bioventing after initial
period
In-situ Bioremediation
Stack,
Soil surface
VOCs,
Degradation products
Very limited
Seldom
(rarely needed)
Being used/proposed with
increasing frequency
Ex-situ Bioremediation
Open tanks,
Waste feed
VOCs,
Degradation products,
PM from waste feed
Very limited
Seldom
Incineration
Stack,
Waste feed
Metals, PM, NOx, CO,
Dioxins/furans
Very extensive
Always
Seldom first choice for
soils contaminated with
fuels
Soil Washing
Process unit,
Waste feed
VOCs
None
Not known
Developing technology
Solvent Extraction
Process unit,
Waste feed
VOCs,
solvent
None
Not known
Developing technology
Soil Flushing
Soil surface,
Water recovery
system
VOCs
None
Seldom
(rarely needed)
Developing technology
-------
Table 2-2
Typical Control Technologies Used for Remediation Technologies
Emission Source
VOCs/SVOC"s
Particulate Matter
and Metals
Acid Gases
Materials Handling
Excavation
Operational Controls
Foams
Enclosure
Water Sprays
NA
Storage Piles
Polymer Sheeting
Cover
Wind Screen
NA
Transport Vehicles
Cover
Foam
Cover
NA
Roadways
NA
Gravel/Paving
Water Sprays
Water Sprays w/Additives
NA
Thermal Desorption
Condensers
Thermal Incineration
Carbon Adsorption
Cyclone
Venturi Scrubber
Fabric Filter
HEPA Filter
Wet Scrubber
Dry Scrubber
Soil Vapor Extraction
Carbon Adsorption
Catalytic Incineration
Thermal Incineration
Internal Combustion Engine
NA
NA
In-situ Bioremediation
Carbon Adsorption
NA
NA
Ex-situ Bioremediation
Carbon Adsorption
NA
NA
Incineration
NA
Cyclone
Venturi Scrubber
Ionizing Wet Scrubber
Wet ESP
Fabric Filter
Wet Scrubber
Dry Scrubber
Soil Washing
Carbon Adsorption
NA
NA
Solvent Extraction
Thermal Incineration
NA
NA
Soil Flushing
Carbon Adsorption
NA
NA
a SVOC = Semi-Volatile Organic Compound
2-3
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Table 2-3
Summary of Cost Information for the Treatment of Contaminated Soil
Estimated Treatment Cost, $/Mg ($/ton)
Technology
Controlled
Uncontrolled
Excavation and Removal
ND
68 -454
(75 - 500)
Thermal Desorption
32-113
(35 - 125)
NA
Soil Vapor Extraction
47/Mg ofVOC
(52/ton ofVOC)
24/Mg ofVOC
(26/ton ofVOC)
In-situ Biodegradation
NA
91
(100)
Ex-situ Biodegradation
ND
64-118
(70- 130)
On-Site Incineration
354 - 925a
(390-10203)
NA
Soil Washing
NA
48-195
(53-215)
Solvent Extraction
NA
95 - 476
(105 -525)
Soil Flushing
NA
ND
aAssumes incineration of hazardous waste (as opposed to incineration of soil contaminated with
petroleum fuels) and a relatively small site.
ND = Not determined
NA = Not applicable
2-4
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3.0 EXCAVATION AND REMOVAL
3.1 Process Description
Excavation and removal of soils
contaminated with fuels is a common
practice. If removal is the selected remedy,
the excavated soil typically is transported off
site for subsequent disposal in a landfill.
Excavation activities also are typically part
of on-site treatment processes such as
incineration, thermal desorption, ex-situ
biotreatment, and certain chemical and
physical treatment methods. The soil is
excavated and transported to the process
unit, treated, and the treated soil may be
used as fill at the site. The information
presented in this section for excavation and
removal is generally applicable to other soils
handling operations such as dumping,
grading, short-term storage, and sizing and
feeding soil into treatment processes.
The magnitude of volatile organic
compound (VOC) emissions depends on a
number of factors, including the type of
compounds present in the waste, the
concentration and distribution of the
compounds, and the porosity and moisture
content of the soil. The key operational
parameters are the duration and
vigorousness of the handling, and the size of
equipment used. The longer or more
energetic the moving and handling, the
greater likelihood that organic compounds
will be volatilized. The larger the volumes
of material being handled per unit operation,
the lower the percentage of VOCs that are
stripped from the soil, because the surface
area to volume ratio is minimized.
The success of excavation and
removal for a given application depends on
numerous factors with the three key criteria
being: 1) the nature of the contamination;
2) the operating practices followed; and
3) the proximity of sensitive receptors. Each
of these criteria is described below.
As previously discussed, spills or
leaks of fuels typically involve liquids
containing dozens of different constituents.
Excavation and removal is generally a viable
option, except for those cases where air
emissions potentially pose an unacceptable
risk. For example, soil containing percent
levels of benzene or other volatile
carcinogens would likely pose a large risk to
on-site workers and the surrounding
populace if it were to be excavated. In-situ
remediation methods, such as soil vapor
extraction, would be preferable for such a
site, either in lieu of excavation or prior to
excavation to reduce the emissions potential.
The magnitude of emissions from
soils handling operations will vary with the
operating conditions. The rate of excavation
and dumping, the drop height, the amount of
exposed surface area, the length of time that
the soil is exposed, the shape of the storage
piles, and the dryness of the surface soil
layers will all influence the levels of VOC
emissions. Add-on control technologies are
available for minimizing emissions, but
they are relatively ineffective and costly to
implement compared with controls for point
sources. VOC emission control also can be
achieved by controlling the operating
conditions within preset parameters. Large
reductions in emissions can be achieved by
identifying and operating within acceptable
ranges of conditions.
Some release of volatile
contaminants is inevitable during excavation
and removal unless unusual measures are
taken (e.g., enclose the remediation within a
dome), so the proximity of downwind
receptors (i.e. people) will influence whether
3-
1
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or not excavation is an acceptable option.
Excavation of contaminated areas that abut
residential areas, schoolyards, etc. may
require more extensive controls, relocation
of the affected population, or remediation
only during certain periods (e.g.,
summertime for school sites).
The relative advantages of
excavation and removal over other
remediation approaches are that:
• Earth-moving equipment and trained
operators are widely available;
• Large volumes of soil can be quickly
moved in a cost-effective manner;
and
• Residual contamination remaining at
the site is minimal.
The major disadvantages of excavation and
removal versus other remediation
approaches are that:
• The magnitude of air emissions may
be high;
• Air emissions from excavation are
difficult to control; and
• The contaminants are only removed,
they are not destroyed.
3.2 Identification of Air Emission
Points
VOC emissions from handling
operations result from the exchange of
contaminant-laden soil-pore gas with the
atmosphere when soil is disturbed and from
diffusion of contaminants through the soil.
There are several potential emission points
involved in excavation as shown in Figure
3-1; all are considered to be fugitive area
sources. For excavation, the main emission
points of concern are emissions from:
• exposed waste in the excavation pit;
• material as it is dumped from the
excavation bucket; and
• waste/soil in short-term storage piles.
In addition, the earth-moving equipment will
be additional sources of emissions of VOC,
particulate matter, nitrogen oxides, etc.
3.3 Typical Air Emission Species of
Concern
The emissions of concern from soils
handling operations such as excavation can
be any contaminant that is present in the
soil. Relatively large amounts of VOCs may
be released from soil during handling, so
VOCs are typically the emissions of most
concern. Emissions of particulate matter
and associated metals and semi-volatile
compounds may be of concern at some sites.
3.4 Summary Of Air Emissions Data
Given the frequency with which
excavation of contaminated soils is
employed, surprisingly little air emissions or
emission rate data for excavation has been
published. The measurement of emission
rates from dynamic processes, such as
excavation, is difficult and relatively
expensive, and so has rarely been attempted.
Volume EH of the Series of Air-
Superfund Guidance Manuals (Eklund, et
al., 1989) for estimating clean-up emissions
indicates that soils handling operations such
as excavation increase VOC emission rates
3-2
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L6ontOTiraedtSo Emissions from excavation of contaminated sol
Figure 3-1. Summary of Air Emission Points For Excavation and Removal.
Source: Saunders, 1990.
3-3
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from contaminated soil over baseline rates.
The increase in emissions is typically a
factor of ten or more, and the increased
emission rate decays exponentially back to
near the baseline rate over short time periods
(e.g. 4 days). A database of baseline
emission rate measurement data (Eklund, et
al., 1991) is available.
Emission rate measurements were
made at two sites for EPA's Superfund
program (Eklund, 1990). Measured
emission rates from combined excavation
and dumping operations were as high as 4
g/min for specific compounds. Most of the
mass of VOCs present in the soil was
stripped from the soil during excavation,
based on a comparison of measured total
emissions versus the mass of these same
contaminants in the soil (calculated from
soil concentration data). This was true for
both sites, despite differences in soil
concentrations and soil type. Excavation
was found to decrease the soil moisture
content by 35% to 56% and tended to
somewhat decrease (e.g. -13%) the dry bulk
density of the soil.
A few additional studies have been
performed using open path monitoring with
a Fourier-Transform Infrared (FTIR)
instrument to measure ambient
concentrations downwind of excavation
activities. Under certain meteorological
conditions, these measurements can be used
to calculate emission rates.
FTIR measurements were performed
at the Gulf Coast Vacuum Superfund site
during pilot-scale excavation activities
(Scotto, et al., 1992). Results were obtained
for total C8+ branched-chain and for C8+
straight-chained hydrocarbons, as shown in
Table 3-1. No individual VOCs were
identified [the detection limit for benzene,
toluene, ethylbenzene, and xylenes (BTEX)
was about 10 g/sec]. Emission rate
measurements were made every one to two
minutes over a 30-minute period when
excavation was underway. The emission
rates were found to vary by about a factor of
two over both the full 30-minute period and
from one minute to the next (Kagann, et al.,
1993).
FTIR measurements also were
performed during the excavation of trenches
at the Westminster Superfund site (Kagann,
etal., 1993). The site contained acidic
sludges. Data were reported only for sulfur
dioxide; these results are given in Table 3-2.
Theoretical models for estimating
emissions (Eklund, et al., 1992a) indicate
that about 70% of the mass of a volatile
compound such as xylene is emitted during
excavation of soil with a starting
contaminant concentration of 1 ppm under
the assumed typical conditions. Another
theoretical study (Saunders, 1990) of soils
handling emissions estimated that relative to
excavation, other soils handling operations
would have the following emissions: 1)
Truck Filling - 0.58; 2) Transport - 5.23; and
3) Exposed soil - 1.47 (emissions/excavation
emissions).
Field experience indicates that actual
emissions may be substantially lower than
the stripping percentages discussed above.
For dry, porous soils containing low ppb
levels of contaminants it can be assumed
that most or all of the more volatile VOCs
will be lost to the atmosphere during soils
handling. For sites with moist soils and ppm
levels of contaminants, however, a
reasonable assumption may be that only 5 to
10% of the VOCs are emitted to the
atmosphere during each handling step.
3-4
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Table 3-1
Results of Emission Measurements at Gulf Coast Vacuum Site
Activity
Sludge
Volume
in m3 (yd3)
Exposed
Surface Area in
m2 (yd2)
C8+
Hydrocarbon
Emission Rate
in g/sec
Sludge
Disturbance
25-27
(33 - 35)
45 - 125
(54 - 150)
1.33
Sludge
Excavation
26-48
(34 - 63)
125 -261
(150-312)
7.76
Sludge
Dewatering
1.7
(2.2)
3.3
(4.0)
1.24
Post-
Disturbance
26
(34)
91
(109)
1.11
Source: Scotto, et al., 1992.
3-5
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Table 3-2
Emission Rates Measured at the Westminster Superfund Site
Activity in Trenches
Measurement Time
Sulfur Dioxide (S02)
Emission Rate
(g/sec)
Start
End
Excavate First Trench,
Apply Foam
13:30
13:35
0.55
Apply Foam
13:45
13:50
0.92
Foam in Place
14:05
14:20
14:25
14:10
14:25
14:30
0.45
0.73
0.54
Refill Trench
14:30
14:35
1.1
Remove Topsoil from 2nd
Trench
16:05
16:10
0.07
Encounter Waste Material
16:20
16:25
1.0
Apply Foam
16:35
16:40
0.42
Remove 60 Buckets of
Material
16:50
16:55
0.41
Source: Kagann, et al., 1993.
3-6
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More measurement data are needed to
support these assumptions.
No valid emission factors were
found. A theoretical study of the emissions
from the clean-up of leaking underground
storage tank sites (U.S. EPA-OUST, 1989)
estimated that emissions from storage piles
of contaminated soil with a surface area of
186 m2 (2,000 ft2) were:
Average Benzene Emission Rate = 1 lb/hr
Total Benzene Emissions = 336 lb
Average VOC Emission Rate = 50 lb/hr
Total VOC Emissions = 16,800 lb
The total emissions are based on a two-week
time period. Emissions from the actual
excavation process, as opposed to soils
storage, were not estimated.
3.5 Identification of Applicable
Control Technologies
A number of methods are available
for controlling VOC and particulate matter
emissions from soils. In general, any
method designed primarily for particulate
control will also reduce VOC emissions and
vice versa. Compared to point source
controls, VOC emission controls for
excavation and other area sources are
difficult to implement and only moderately
effective. The choice of controls also can
effect treatment and disposal options. For
example, controls such as water sprays or
foams will alter the percent moisture, bulk
density, and average heating value of the soil
and may in some cases make thermal
treatment infeasible.
VOC emission controls for soil area
sources are described below including:
• Covers and physical barriers;
• Temporary and long-term foams;
• Water sprays;
• Operational controls;
• Complete enclosures; and
• Wind Barriers.
Additional information is given in Eklund,
et al., 1992b.
3.5.1 Covers and Physical Barriers
The most commonly used VOC
control approach for area sources is the use
of covers to provide a physical barrier to
vapor transport. The simplest barrier is the
use of relatively clean soil as a cover for
contaminated soil. The soil layer increases
the necessary transport distance for vapor
diffusion and thus greatly reduces, at least
temporarily, the emission rate. Soil covers
are widely used at sanitary landfills to
control the emissions of odorous compounds
and to control wind-borne pollution. The
effectiveness of soil covers will depend on
the depth of the cover and the percent of
contaminated soil that can be covered.
Measured emission rates may be
substantially reduced (e.g., >95%) by the
addition of compacted soil (Suder and
Schmidt, 1992); however, lateral migration
of VOCs may still occur. Soil covers will be
less effective over long time periods and
their use will tend to increase the total
volume and mass of material that must be
treated.
Synthetic covers are typically used to
control VOC emissions from excavated soil
in short-term storage piles. Synthetic covers
are also widely used to control VOC
emissions during transport by rail or truck.
The cover may be thin (4-6 mil) plastic
sheeting or relatively thick (30-40 mil)
plastic sheeting or geotextile material. The
resistance of various polymers to chemicals,
3-7
-------
weather, gas permeability, and tears is
documented (Landeeth, et al., 1983). The
barrier material is available in large rolls and
can be quickly applied to even large soil
piles. The synthetic cover must be secured
against wind.
The barrier can be left in place
indefinitely, though physical and
photodegradation of the polymer will tend to
limit the effective lifetime of thin barriers to
a few weeks. The effectiveness of the cover
will depend on its permeability to the vapors
that are present and the percentage of the
soil pile that is adequately covered.
Laboratory measurements of a 20 mil PVC
membrane showed relatively poor
performance for limiting vapor diffusion
(Springer, et al., 1986). The PVC membrane
proved to be only as effective as a covering
of a few inches of porous soil.
Numerous mulch materials, such as
sawdust, wood chips, straw, and wood fibers
can also be used as a cover for soil
undergoing long-term storage (U.S. EPA,
1991). The mulch acts primarily to control
diffusion by insulating the soil surface and
thereby lowering the soil temperature. The
mulch material also limits diffusion
somewhat if it is used as a cover, but if
mixed in with the contaminated soil the
mulch will generally increase the porosity of
the soil and thereby increase the emission
rate. The mulch also increases the volume
and mass of contaminated material to be
treated or disposed.
3.5.2 Temporary and Long-Term Foam
Covers
Modified fire-fighting foams are
commonly used to control VOC emissions
during the remediation of hazardous waste
sites containing volatile toxic compounds.
At least six types of foam products are
available (Evans and Carroll, 1986) from
vendors such as Rusmar and 3M. The
different foams vary in their compatibility
and effectiveness for various classes of
contaminants. Specialized equipment is
available for applying foams over large
areas. The foam is applied to a depth of 6-
18 inches and coverage rates of 100 m2/min
are possible. The liquid foam concentrate is
applied via an air-aspirating nozzle or chute.
The degree of expansion (how many gallons
of foam produced from a gallon of liquid
concentrate) can be high (250:1), low (20:1),
or medium.
Two general types of foams are used:
temporary and long-term. The temporary
foams provide coverage for up to an hour, at
which time 25% or more of the liquid
incorporated in the foam will have been
released. Long-term foams contain a
stabilizing additive to extend the useful life
of the foam to days or even weeks. The
effectiveness of foams is quite high for the
areas that are covered. Short-term emission
reductions of 75% to 95% (for total paraffins
and total aromatics, respectively) have been
measured in the field over 20 minute time
periods (Aim, et al., 1987). Emission
reductions for total VOCs of 99% to 100%
using stabilized foam have been measured in
the field over 24-hour time periods (Aim, et
al, 1987).
The two primary advantages of
foams are that they can be highly effective
and they can be applied directly to the
backhoe bucket and the exposed
contaminated soil. There are several
disadvantages of foams to consider. The
thick layers of foam required for emissions
control can be applied more effectively to
horizontal surfaces than to vertical surfaces
such as the sides of the excavation pit.
3
-8
-------
Incomplete coverage of the emitting surfaces
will markedly decrease the effectiveness of
the controls. The foam concentrates are
usually over 90% water and the addition of
this water increases the weight of the soil,
makes it more difficult to handle, and makes
it less amenable to thermal treatment. The
foam is difficult to apply on windy days and,
under any conditions, frequent application or
re-application of the foam may be necessary.
3.5.3 Water Sprays
Water sprays are a commonly used
control method for particulate matter (PM)
emissions. The addition of dust control
chemicals such as polymers or acrylics to the
water increases the effectiveness of the
spraying. The water added to the soil will
decrease the air-filled porosity of the soil
and will also tend to cool the surface soil
temperature. The reduction in vapor
transport will diminish VOC emissions,
though the effectiveness of water sprays for
VOC control is not documented. Water
sprays are certainly much less effective than
water-based foams, and they have essentially
the same limitations as those listed above for
foams.
3.5.4 Operational Controls
Operational controls can be effective
in minimizing VOC emissions. These
controls may involve controlling the rate of
excavation, the amount of contaminated soil
area that is exposed, and the duration that
soil piles are left uncovered. The timing of
excavation can also be important.
Scheduling excavation during times of the
day or seasons of the year when wind speeds
and temperatures are low can reduce
emissions. Stagnant wind conditions,
however, may lead to unacceptable ambient
air concentrations at the work site. The
work can also be scheduled to avoid seasons
with dry soil conditions to further minimize
emissions.
3.5.5 Complete Enclosures
If warranted, complete enclosure of
the excavation-site can be accomplished to
minimize VOC emissions. The enclosure
acts to collect any emissions, which can then
be vented to some type of control device
suitable for point sources (see Section 5.5).
The enclosure may be either air supported or
self supported. Self-supported domes are
more practical if trucks or other heavy
equipment must regularly enter and leave the
structure. If properly designed and operated,
the enclosure may reduce VOC emissions to
negligible levels.
There are severe limitations that
limit the use of complete enclosures to the
few sites where other control options are not
acceptable. The capital cost of the structure
is relatively high. Operating costs also can
be very high if large volumes of air must be
treated and exhausted to keep the
concentrations of contaminants in the
atmosphere within the dome at levels that
are safe for the workers. Air temperatures
within the structure may be high enough to
affect worker productivity and safety. The
added safety requirements along with the
added time needed for getting trucks in and
out of the structure likely will extend the
time to complete the excavation and thereby
increase the cost.
The U.S. EPA conducted a feasibility
study of excavation with an enclosure
(Dosani and Aul, 1992). Even with a gas
exhaust system in operation, ambient
concentrations of sulfur dioxide and other
pollutants within the structure made it
necessary for workers to wear Level B or
3-9
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Level A personal protective equipment
(PPE).
of effort such as the cleanup of a typical
LUST site.
3.5.6 Wind Barriers
For small work areas, the use of
wind barriers can reduce VOC emissions by
lowering the effective wind speed at the soil
surface. Commercial, porous wind fence
material that is typically used for dust
control has been found to be more effective
than solid fence material (Springer, et al.,
1986). For larger working areas, fencing is
less practical.
VOC (and PM) emissions from
storage piles can be minimized by
controlling the placement and shape of the
piles. When feasible, the piles can be placed
in areas shielded from the prevailing winds
at the site. The amount of surface area can
be minimized for the given volume of soil
by shaping the pile. The orientation of the
pile will affect the wind velocity across the
pile with the lowest windspeed occurring
when the length of the pile is perpendicular
to the prevailing wind direction.
3.6 Costs For Remediation
The total costs for the treatment of
contaminated soil by excavation and
removal will be the sum of the costs for
excavation, transport, and treatment or
disposal. The total costs will vary widely
and are primarily dependent on the disposal
or treatment costs. Total costs per ton may
range from $75 to $500 or more, for
excavation and off-site disposal. All costs
shown below for years prior to 1991 have
been converted to 1991 dollars using a 5%
annual escalation factor. The cost per cubic
yard will tend to increase for smaller levels
Standard costs for earth-moving
activities are available (Means, 1991).
Estimates of excavation costs for petroleum
contaminated soils are in the range of $2.50
to $6.00 per ton (Troxler, 1992). The costs
of excavation will depend the level of
personal protective equipment required by
the operator and on-site workers. Costs to
excavate soil contaminated with hazardous
wastes for different safety levels are (Lippitt,
et al., 1986):
Hazard
Level
Cost per m3 (yd3)
No Hazard
$22 ±19 ($29±25)
LevelD
$75 ±56 ($95±73)
Level C
$91 ±84 ($119±110)
Level B
$117 ±86 ($153±113)
Level A
$133 ±96 ($148±126)
Published cost estimates for
excavation of soil contaminated with
hazardous wastes vary widely. The
estimated cost to excavate and load sixteen
million cubic yards at the Rocky Mountain
Arsenal was only $6/yd3 (U.S. GAO, 1986).
The cost to excavate large volumes of soils
contaminated with explosives has been
estimated to be $11.14/ton, or about
$ 13.92/yd3 (Tennessee Valley Authority,
1990). This cost comprised 79% labor, 7%
operating expenses, 10% equipment
expense, and 4% for site reclamation. The
cost to excavate large volumes of soils at
another DOD site were estimated per cubic
yard to be (Cullinane, et al., 1986):
3-10
-------
Activity
Cost
per m3 (yd3)
Dry excavation
5.36 (7.02)
Wet excavation
10.72(14.03)
Site grading and
revegetation
1.66 (2.17)
Site grading
1.15(1.51)
Backfilling with clean
soil
25.84 (33.82)
If high-levels of volatile pollutants
are present in the material to be excavated, it
may be necessary to perform the removal
within an enclosure. For the McColl site, in
Fullerton, CA, the cost for excavation of
soils contaminated with hydrocarbons and
sulfur dioxide was estimated to be $593/ton
of in-place waste (Dosani and Aul, 1992).
Cost for post-excavation treatment are not
included. The $593/ton cost includes the
following components: labor (22%),
supplies and consumables (21%), equipment
(12%), and utilities (11%).
Cost estimates for transportation of
petroleum contaminated soils range from
$0.08 to $0.15 per ton per mile (Troxler,
1992). Vendor quotes for off-site
transportation of soil contaminated with
hazardous wastes typically range from $2.50
to $5/yd3 per mile, though they may be
higher under some site-specific conditions.
Costs for transporting soil will be lower for
on-site work and will be lower for off-site
transport if it is not necessary to follow the
procedures typically employed for
transporting soils contaminated with
hazardous wastes. Published cost estimates
for off-site transport include an estimate of
about $3.80/yd3 per mile (Cullinane, et al.,
1986) and an average from ten sites of
$0.25/ton per mile (Yang, et al., 1987). A
cubic yard of soil can be assumed to weigh
about 2500 pounds.
Disposal costs are highly dependent
on the amount and nature of contamination
present in the soil. Vendor quotes for
disposal are typically $250 to $350/yd3 of
soil. Published estimates (Cullinane, et al.,
1986) include costs of $38/yd3 for disposal
in a sanitary landfill and $160/yd3 for
disposal in a RCRA landfill.
3.7 Costs For Emission Controls
Costs for VOC controls for
excavation are not widely available in the
literature. Available data are summarized in
Table 3-3.
3.8 Equations and Models For
Estimating VOC Emissions
The factors that govern excavation
emissions are very complex. During
excavation, the physical properties of the
soil that control the vapor transport rate (e.g.
air-filled porosity) are changing with time
and the concentration of contaminants may
be rapidly decreasing. Predictive equations
for estimating VOC emissions from
excavation have been developed by the U.S.
EPA. The predictive equations require
assumptions about the size of each scoop of
soil, the dimensions of the soil scoops and
the excavation pit, and the shape of the soil
after it is dumped. Further assumptions are
required about the air and soil temperatures
and the length of time that dumped soil is
exposed before it is covered with more soil
or with an emissions barrier.
Since it is rarely feasible or efficient
to dig soil and immediately transfer the soil
directly to transport vehicles or treatment
3-11
-------
systems, any estimation procedure must
account for each event in which the soil is
handled. In most cases, soil will be
excavated and placed into a temporary
holding area and then handled one to two
more times on-site. Elevated levels of VOC
emissions are possible each time the soil is
handled. When estimating emissions from
sequential soil handling steps, it is important
to adjust the starting concentrations for each
step to account for contaminants emitted
during prior steps.
The equations used are shown below.
The average emission rate (g/sec) from
excavation is equal to the sum of emission
rates from the soil pore space and from
diffusion:
The total mass of contaminants in a
given volume of soil, or for an entire site,
can be estimated as follows:
M = SVC P 1.0 (Eq. 3-1)
where:
M = total mass of contaminants in soil
(g);
Sv = total volume of contaminated
material (m3);
C = concentration of species i in bulk soil
(Mg/g);
P = bulk density of soil (g/cm3); and
1.0= constant (g/106 pg/g * 106cm3/m3).
A simple check of the potential total
emissions from remediation of a given
volume of soil, or for the entire site, can be
made by dividing the total mass of
contaminants by the projected duration of
activity:
ER = M / tsv (Eq. 3-2)
where:
ER = emission rate of species i (g/sec); and
tsv = time to excavate a given volume of
soil (sec).
For the remediation of an entire site, tsv is the
duration of remediation (sec). The emission
rate from equation 3-2 is the theoretical
maximum value for the average long-term
emission rate for the remediation activities
assuming all contamination is transferred to
the atmosphere. As a sanity check, it should
be demonstrated that any short-term
emission rate estimates do not predict a
greater mass of contamination being emitted
over some time period than the total mass of
contamination present in the soil.
A model to estimate the short-term
emission rate from the excavation of soil has
been developed by the U.S. EPA (Eklund, et
al., 1992a). The model is presented below;
example calculations are given in Appendix
C to this report. The derivation of the
excavation model is given in Appendix D.
Tabulated physical property data is given in
Eklund and Albert, 1993.
ER = ERPS + ERD|pp
(Eq. 3-3)
„ P M. 106 E, Q ExC
ERps = (TF
(Eq. 3-4)
3-12
-------
Table 3-3
Summary of Costs for Emission Controls for Area Sources
Control
Material Cost
($/mz except as
noted)
Comments
Clay
$4.15
Covers, mat, and membrane
Soil
$1.33
Assume 6" deep; does not include soil transport
Wood chips, plastic net
$0.50
Chip costs vary with site
Synthetic Cover
$4.40
Assume 45 ml thickness
Short-term foam
$0.04
Assume 2.5" thick, $0.7/M3 foam
Long-term foam
$0.13
Assume 1.5" thick, $3.3/M3 foam
Wind screen
$40/m
Per linear meter
Water Spray
$0,001 (varies)
Assuming municipal water cost of $1/$ 1,000 L.
Water requires constant re-application. Water
truck rental: $500/week.
Additives:
Surfactant
Hygro Salt
Bitu/Adhes.
$0.65
$2.58
$0.02
Costs vary with chemical use
Source: Eklund, et al., 1992b.
3-13
-------
ER
(C )(10,000)(A)
DIFF
E, 1
/ \
TTt
1
2
K.„ kJ
1 De 0
(Eq. 3-5)
All variables are defined in Table 3-4. Also
shown in Table 3-4 are the units of each
variable and a typical default value to use if
valid field data are not available. Soil
concentration data typically are available as
Hg/g (ppm). This type of value can be
multiplied by the bulk density of the soil
(g/cm3) and by a conversion factor of 10"6
(g/^g) to yield units of g/cm3:
CS = (C)(P)(10"6)
(Eq. 3-6)
Equation 3-4 is based on the
assumption that the soil pore gas is saturated
with the compound of interest. If this is not
the case, then Equation 3-4 may over predict
the emission rate. The output from Equation
3-4 should be multiplied by the duration of
excavation (i.e., ERps * *sv) and the result
compared to the total mass of contaminants
present in the soil calculated from Equation
3-1 or the following (depending on what
units of concentration data are available):
M = C * Sv *
106 cm3
nr
(Eq. 3-7)
If ERps * tsv > 0.33M, Equation 3-4 is
giving a value that is far too conservative
(i.e., is biased high). In such cases, ERps
should be calculated using the following
equation instead of Equation 3-4:
ERPS = M *
0.33
sv
(Eq. 3-8)
3.9 Case Study
No suitable case study exists for
excavation. Studies that have valid data for
emissions, control efficiencies, and costs are
referenced above in the applicable
subsections.
3.10 References
Aim, R.R., K.A. Olson, and R.C. Peterson.
Using Foam to Maintain Air Quality During
Remediation of Hazardous Waste Sites.
Presented at the 80th Annual AWMA
Meeting (Paper 87-18.3), New York City,
June 21-26, 1987.
Cullinane, M.J., et al. Feasibility Study of
Contamination Remediation at Naval
Weapons Station, Concord, California.
Dept. of the Navy. (NTIS AD-A165 623).
February 1986.
Dosani, M. and E. Aul. Demonstration of a
Trial Excavation at the McColl Superfund
Site, Applications Analysis Report.
EPA/540/AR-92/015. (NTIS PB93-
100121). October 1992.
Eklund, B., et al. 1989. Air/Superfund
National Technical Guidance Study Series,
Volume ID: Estimation of Air Emissions
from Cleanup Activities at Superfund Sites.
Report No. EPA-450/1-89-003 (NTIS PB
89-180061). U.S. EPA, Research Triangle
Park, NC, January 1989.
Eklund, B. Personal communication.
Radian Corporation, Austin, TX. 1990.
Eklund, B., et al. Air Superfund National
Technical Guidance Series: Database of
Emission Rate Measurement Projects.
EPA450/1-91-003 (NTIS PB 91-222059).
June 1991.
3-14
-------
Table 3-4
Input Variables for Emission Equations
Variable
Definition
Units
Default Value
A
Emitting surface area
m2
290
3
Bulk density
g/cm3
1.5
c
Concentration of species I in bulk
soil
Mg/g
--
c.
Mass loading in bulk soil
g/cm3
1.35 x 10^
Cv
Concentration in soil gas
Hg/m3
—
D,
Effective diffusivity in air
cm2/sec
0.0269
E,
Air-filled porosity
Dimensionless
0.44
ER
Total emission rate
g/sec
—
ERps
Emission rate due to soil pore space
gas
g/sec
—
ERdjff
Emission rate due to diffusion
g/sec
—
ExC
Soil-gas to atmosphere exchange
constant
Dimensionless
0.33
Kn
Equilibrium coefficient
Dimensionless
0.613
Mw
Molecular weight
g/g-mol
100
M
Total mass of contaminant
R
~
P
Vapor pressure
mm Hg
35
n
Pi
Dimensionless
3.14
0
Excavation rate
m3/sec
0.042
R
Gas constant
mm Hg-cm3/g-
mol°K
62361
Sv
Volume of soil moved
m3
150
T
Temperature
Degrees Kelvin
298
t
Time to achieve best curve fit
(use default value)
sec
60
t,v
Time to excavate a given volume of
soil
sec
72 (perm3)
10,000
Conversion factor
cm2/m2
„
106
Conversion factor
cm3/m3
—
(Continued)
3-15
-------
Table 3-4
(Continued)
Variable
Definition
Units
Default Value
Other Variables Required to Calculate Certain Variables Listed Above
K
Gas-phase mass transfer coefficient
cm/sec
0.15
P
Particle density
g/cm3
2.65
D.
Diffusivity in air
cm2/sec
0.1
U
Wind speed
m/sec
2
Viscosity of air
g/cm-sec
1.81 x 10"4
P.
Density of air
g/cm3
0.0012
d-
Diameter of emitting area
m
24
Eklund, B., S. Smith, and A. Hendler.
Estimation of Air Impacts for the
Excavation of Contaminated Soil. EPA
450/1-92-004 (NTIS PB92-171925). March
1992a.
Eklund, B. et al., 1992b. Control of Air
Emissions from Superfund Sites.
EPA/625/R-92/012 (NTIS PB93-215614).
November 1992.
Eklund, B. and C. Albert. Models for
Estimating Air Emission Rates from
Superfund Remedial Actions. EPA-451/R-
93-001 (NTIS PB93-186807). March 1993.
Evans, M. and H. Carroll. Handbook For
Using Foams to Control Vapors From
Hazardous Spills. EPA/600/8-86/019 (NTIS
PB87-145660). July 1986.
Kagann, R.H., O.A. Simpson, and R.J.
Kricks. Monitoring for Fugitive Emissions
at Superfund Sites During Activities With an
FTER Remote Sensor. In: Proceedings of
Measurement of Toxic & Related Air
Pollutants (p. 557). EPA/600/A93/024.
1993.
Landeeth, B., et al. Lining of Waste
Impoundment and Disposal Facilities. U.S.
EPA Report SW-870 (NTIS PB86-192796).
March 1983.
Lippitt, J., et al. Costs of Remedial Actions
at Uncontrolled Hazardous Waste Sites:
Worker Health and Safety Considerations.
EPA/600/2-86/037 (NTIS PB86-176344).
September 1986.
Means, 1991. Means Site Work Cost Data,
K. Smit, Sr. Editor. Published by R.J.
Grant. 1991.
Saunders, G.L. Air/Superfund National
Technical Guidance Study Series -
Development of Example Procedures for
Evaluating the Air Impacts of Soil
3-16
-------
Excavation Associated With Superfund
Remedial Actions. EPA-450/4-90-014
(NTIS PB90-255662). July 1990.
Scotto, et al. VOC Emission Rate
Determinations Using Open-Path FTIR
Spectroscopy during Pilot-Scale Site
Disturbance and Remediation Activities: A
Case Study Using the Ratio Technique.
Presented at the 85th Annual AWMA
Meeting (Paper 92-83.04), Kansas City,
MO, June 21-26, 1992.
Springer, C., K.T. Valsaraj, and L.J.
Thibodeaux. In Situ Methods to Control
Emissions from Surface Impoundments and
Landfills. JAPCA Vol. 36, No. 12, ppl371-
1374, December 1986.
Suder, D.R. and C.E. Schmidt. Control
Efficiencies and Costs of Various
Technologies for Reduction of Volatile
Organic Compound Emissions from
Exposed Hazardous and Non-Hazardous
Waste. Presented at the 85th Annual
AWMA Meeting (Paper 11.15), Kansas
City, MO, 1992.
Tennessee Valley Authority. Economic
Feasibility Analysis for Development of
Low-Cost Chemical Treatment Technology
for Explosive Contaminated Soils.
USATHAMA (NTIS AD-A223497). May
1990.
Troxler, W.L. Personal communication.
U.S. EPA, Cincinnati, Ohio. 1992.
U.S. EPA. Estimating Air Emissions from
Petroleum UST Cleanups. Office of
Underground Storage Tanks. Washington,
DC. June 1989.
U.S. EPA. Engineering Bulletin: Control of
Air Emissions From Material Handling.
EPA/540/2-91/023 (NTIS PB93-180041).
EPA/ORD-Cincinnati. October 1991.
U.S. General Accounting Office. Hazardous
Waste: Selected Aspects of Cleanup Plan
for Rocky Mountain Arsenal. NTIS PB87-
102488. August 1986.
Yang, E.C., et al. Compendium of Costs of
Remedial Technologies at Hazardous Waste
Sites. EPA/600/2-87/087 (NTIS PB88-
113477). October 1987.
3-17
-------
4.0 THERMAL DESORPTION
This section contains information
about mobile and stationary process units
that employ thermal desorption to remediate
soil and the use of asphalt aggregate dryers
for soil remediation. Data are included for
the treatment of soil contaminated with
petroleum fuels and soil contaminated with
hazardous wastes.
Key references are two studies that
include summarized information about
existing soil vapor extraction (SVE) systems
in use at field sites (Hutzler, et al., 1989; and
PES, 1989), an evaluation conducted under
EPA's SITE program (Michaels, 1989a), and
an overview paper (Johnson, et al., 1990).
The Johnson, et al.; paper is given as
Appendix E of this report and EPA's .
Engineering Bulletin on SVE is contained in
Appendix F of this report.
4.1 Process Description
In the thermal desorption process,
volatile and semi-volatile contaminants are
removed from soils, sediments, slurries, and
filter cakes. Typical operating temperatures
are 350°-700°F, but temperatures from 200°
to 1,200°F may be employed. The process
often is referred to as low-temperature
thermal desorption to differentiate it from
incineration, which is a thermal treatment
process employing higher temperatures (see
Section 8). Thermal desorption promotes
physical separation of the components rather
than combustion.
Contaminated soil is removed from
the ground and transferred to treatment
units, making this an ex situ process. Direct
or indirect heat exchange vaporizes the
organic compounds producing an offgas that
is typically treated before being vented to
the atmosphere (Vatavuk, 1990). The best
single source of information on thermal
desorption is contained in a recent EPA
Guidance Document (Troxler, et al., 1992).
The engineering bulletin prepared by the
U.S. EPA (U.S. EPA, 1991) for this
technology also contains useful information
and is included as part of Appendix F to this
report.
After it is excavated, the waste
material is screened to remove objects
greater than 1.5" to 3.0" in diameter (de
Percin, 1991a). In general, any one of four
desorber designs are used: rotary dryer,
asphalt plant aggregate dryer, thermal screw,
and conveyor furnace. The treatment
systems include both mobile and stationary
process units designed specifically for
treating soil, and asphalt aggregate dryers
that can be adapted to treat soils. Mobile
systems are most often used, due to reduced
soil transportation costs and to allow for
backfilling of the treated soil. However,
stationary systems also are available and
may be feasible to provide regional services.
Typical specifications for thermal desorption
systems are shown in Table 4-1.
The effectiveness of thermal
desorption is related to the final soil
temperature that is achieved, which in turn is
a function of residence time and heat
transfer. The temperatures and residence
times effective in bench-scale systems also
have proved to be effective in pilot-scale
systems. Such findings support the use of a
bench-scale test to determine the suitability
of thermal desorption and the best residence
time and temperature to use (de Percin,
1991a). The typical treatment temperature
range for petroleum fuels from leaking
underground storage tank (LUST) sites is
4-1
-------
Table 4-1
Comparison of Features of Thermal Desorption
and Offgas Treatment Systems
Rotary Dryer
Asphalt Plant
Thermal Screw
Conveyor Furnace
Estimated number of system
40-60
100-150
18-22
1
Estimated number of contractors
20-30
No estimate
9
—
Mobility
Fixed and mobile
Fixed
Mobile
Mobile
Typical site size, Mg (tons)
450-23,000 (500-25,000)
0-9,000 (0-10,000)
450-4,500 (500-5,000)
450-5,000 (500-5,000)
Soil throughput, Mg/hour (tons/hour)
9-45 (10-50)
23-90(25-100)
3-14(3-15)
5-9 (5-10)
Maximum soil feed size, cm (inches)
5-8 (2-3)
5-8 (2-3)
3-5(1-2)
3-5(1-2)
Heat transfer method
Direct
Direct
Indirect
Direct
Soil mixing method
Shell rotation and lifters
Shell rotation and lifters
Auger
Soil agitators
Discharge soil temperature, °C (°F)
150-300'(300-600")
300-6501' (600-1,200")
300-600
150-250° (300-500c)
300-250" (600-900")
500-850' (1,000-1,600c)
300-800
Soil residence time (minutes)
3-7
3-7
30-70
3-10
Thermal desorber exhaust gas
temperature," C (°F)
250-450' (500-850")
400-500" (800-1,000")
250-450 (500-850)
150 (300)
500-650(1,000-1,200)
Gas/solids flow
Co-current or counter-
current
Co-current or counter-
current
Not applicable
Counter-current
Atmosphere
Oxidative
Oxidative
Inert
Oxidative
Afterburner temperature, °C (°F)
750-1,000(1,400-1,800)
750-1,000f (1,400-1,800")
Generally not used
750-1,000(1,400-1,800)
Maximum thermal duty, Mj/hr
(MMBtu/hr)e
10,500-105,000(10-100)
5,300-105,000 (50-100)
7,400-10,500 (7-10)
10,500(10)
Heatup time from cold condition (hours)
0.5-1.0
0.5-1.0
Not reported
0.5-1.0
Cool down time from hot condition (hours)
1.0-2.0
1.0-2.0
Not reported
Not reported
Total Petroleum Hydrocarbons
Initial concentration (mg/kg)
Final concentration (mg/kg)
Removal efficiency (%)
800-35,000
<10-300
95.0-99.9
500-25,000"
<20"
Not reported
60-50,000
ND-5,500
64-99
5,000
<10.0
>99.9
BTEX
Initial concentration (mg/kg)
Final concentration (mg/kg)
Removal efficiency (%)
NR
<1.0
NR
Not reported
Not reported
Not reported
155
<1.0
>99
Not reported
<0.01
Not reported
'Carbon steel materials of construction
"'Alloy materials of construction
cHot oil heat transfer system
dMoIten salt heat transfer system
"Electrically heated system
'Not used on all systems
BTotaI duty of thermal desorber plus afterburner
'¦Vendor information: Soil Purification, Inc.
Source: Troxler, 1991.
4-2
-------
400° F to 900° F. For the treatment of soils
containing pesticides, dioxins, and
polychlorinated biphenyls (PCBs),
temperatures should exceed 850° F (de
Percin, 1991c). The distillation temperature
range will vary with the type of fuel
contamination, as shown in Figure 4-1.
Thermal desorbers effectively treat
soils, sludges, and filter cakes and remove
volatile and semi-volatile organic
compounds. Some higher boiling point
substances such as PCBs and dioxins may
also be removed (if present). Inorganic
compounds are not easily removed with this
type of process, although some relatively
volatile metals such as mercury may be
volatilized. Temperatures reached in
thermal desorbers generally do not oxidize
metals (de Percin, 1991a).
The soil is most effectively treated if
its moisture level is within a specified range
due to the cost of treating waste with a high
water content. The typical acceptable
moisture range for rotary dryers and asphalt
kilns is 10-30%, (Troxler, 1991 and SPI,
1991), while thermal screw systems can
accommodate higher water loadings of 30-
80%. For removal of VOCs, the soils
ideally should contain 10-15% moisture
because the water vapor will carry out some
of the VOCs (de Percin, 1991c).
High-molecular-weight organic
compounds may foul or plug baghouses or
condenser systems. Therefore, the types of
petroleum products that can be treated by
specific technologies may be limited.
Rotary dryers typically can treat soils that
have an organic content of less than two
percent. Thermal screw units may treat soils
that contain up to 50% organics. (Troxler,
1991).
Thermal desorbers may operate near
or above 1000°F, so some pyrolysis and
oxidation may occur in addition to the
vaporization of water and organic
compounds. Collection and control
equipment such as afterburners, thermal
oxidizers, fabric filters, activated carbon, or
condensers prevent the release of the
contaminants to the atmosphere (de Percin,
1991a). Various types of thermal desorption
systems can produce up to nine residual
process streams: treated soil, oversized
media rejects, condensed contaminants,
water, particulate control dust, clean off-gas,
phase separator sludge, aqueous-phase spent
carbon, and vapor- phase spent carbon (de
Percin, 1991b).
Thermal desorption has the
following advantages over other treatment
processes:
• A wide range of organic
contaminants can be treated; and
• The systems can be mobile.
There are a number of advantages compared
with incineration. Thermal desorbers
operate at lower temperatures, so significant
fuel savings may result (Vatavuk, 1990).
They also produce smaller volumes of off-
gases to be treated. Thermal desorption also
differs from incineration with regards to the
regulatory and permitting requirements and
the partitioning of metals within the process
residual streams. Perhaps most importantly,
thermal desorption enjoys more public
acceptance than other thermal treatment
methods (de Percin, 1991a).
Potential limitations of the treatment
process exist as well. Thermal desorption
does not destroy contaminants; it merely
4-3
-------
No. 6 Fuel Oil
No. 4 Fuel Oil
No. 3 Fuel Oil
No. 2 Fuel Oil
No. 1 Fuel Oil (kerosene)
Jet Fuel - A
Jet Fuel - B
Automobile Gasoline
Naphtha (heavy)
Aviation Gasoline
Naphtha (light)
•
0 100 200 300 40C 500
Distillation Temperature (C)
Figure 4-1. Soil Treatment Temperature Guide.
Source: Troxler, et al. 1992
4-4
-------
strips them from the solid or liquid phase
and transfers them to the gas phase.
Therefore, devices to control VOC
emissions are necessary. The efficiency of
the thermal desorption process will vary
with the chemical and physical properties of
the specific contaminants. Metals (e.g.,
lead) tend to remain in the soil after
treatment, so additional soil processing or
treatment may be required (e.g.,
stabilization).
A generalized schematic diagram of
a thermal screw, thermal desorption process
is shown in Figure 4-2; the system shown
most closely resembles Weston's LT3
system. Other designs may use different
types of control technology. Information
about specific vendor designs is given
below. The information is based primarily
upon the use of portable remediation units,
but the information should be generally
applicable to other types of thermal
desorption, such as rotary drum aggregate
dryers.
4.1.1 X*TRAX™ by Chemical Waste
Management, Inc.
The X*TRAX™ system is a
transportable, indirectly heated rotary dryer,
that treats up to 100 tons per day of soil and
sediment contaminated with hazardous
wastes. Propane fires an outer shell, which
then heats the soil to 300°-900°F. Nitrogen
gas sweeps the water and organic vapor to
gas treatment and mitigates explosion
hazards. Gas treatment consists of
condensation, refrigeration, and carbon
adsorption. The liquid water is separated
from the liquid organic compounds and used
for dust control (de Percin, 1991b).
4.1.2 Taciuk by SoilTech, Inc.
The Taciuk system is a two-zone,
double-shell rotary dryer that treats up to 25
tons per hour of soil and sediments
contaminated with hazardous wastes. The
solids enter the first zone of the inside shell
where temperatures of 300°F vaporize water
and VOCs. Entry into the second zone of
the inside shell enables additional organic
compounds to be volatilized and pyrolyzed
at temperatures of 1000°F.
The high temperature solids enter the
outer shell where they transfer heat to the
inner shell. Fired natural gas or propane
heats the annulus between the shells. A
cyclone, baghouse, caustic scrubber, and
carbon adsorber treat the combustion gases
while a condenser liquefies gases from both
zones. Non-condensable gases from
pyrolysis help to heat the system (de Percin,
1991b).
4.1.3 LT3 by Roy F. Weston, Inc.
The Low Temperature Thermal
Treatment, or LT3 system, treats up to 20
tons per hour of soil and sediment using two
banks of four heated screws. The process
primarily is used for treating hazardous
wastes. The combustion of propane heats
transfer oil, which is pumped through the
screws, heating the shell to 600° F. The
combustion gases sweep the water and
organic vapor to the gas treatment system
(de Percin, 1991b).
4.1.4 DAVES by Recycling Sciences,
Inc.
The Desorption and Vapor
Extraction System (DAVES) treats
contaminated material in a fluidized bed
where it is fed along with hot air. Gas-fired
4-5
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Classifier
contaminated soil
Surge
Hopper
oversize objects
VOC's
particulate
control
dust
Thermal Processor
House
Condenser
treated soil
Oil/Water
Separator
liquid
Gas/Liquid
gas ^
Separator
exhaust gases
1
Heating
System
clean off-gas
Afterburner
organic liquid
Stack
water
Carbon
Adsorber
treated water
spent carbon
Figure 4-2. Generalized Process Diagram for Thermal Screw-Based Thermal Desorption.
4-6
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heaters heat the air to 1000°-MOOT. The
hot air vaporizes water and organic
compounds and carries them to the gas
treatment system. Gas treatment consists of
a cyclone, baghouse, venturi scrubber,
chiller, and carbon adsorber (de Percin,
1991b).
4.1.5 ReTec by Remediation
Technologies, Inc.
The ReTec thermal desorption
system operates at capacities of 0.5-3.5 tons
per hour and is designed to treat soils
contaminated with organic compounds and
oily sludges. If the waste material has a
high moisture content, the process begins
with a dewatering step. Dewatered filter
cakes from the press are fed to storage
hoppers and then transported to the dryer by
a covered conveyer.
The Holo-Flite Processor consists of
a jacketed trough, which houses a double-
screw mechanism. The heat-transfer fluid
(thermal oil or steam) is circulated through
the trough jacket can. The material enters
and exits the dryer through rotary air-locks
to prevent leakage of ambient air into the
processor. The gas flow from the dryer,
which is designed to remove moisture and
the organic compounds with low boiling
points, passes through a particle removal
system, quench chamber, condenser, and
activated carbon beds (Abrishamian, 1991).
The partially treated soil leaves the
dryer and enters the processor, where the
soil is subjected to temperatures between
500 and 900° F and shorter residence times
(relative to the drying step) to remove the
organic compounds with high boiling points.
Molten salt, heated by an electric or fuel-
fired heater, is used as the heating medium
for the processor. The molten salt does not
produce off-gases, and it is non-toxic, non-
flammable, and easily cleaned up if spilled.
Inert gas added to the processor inhibits
oxidation and enhances vaporization of
contaminants. Off-gases from the processor
undergo treatment with cyclones, a semi-
volatile organic separator, chilled condenser,
and activated carbon beds. A solids cooler
lowers the temperature of the solids to less
than 180°F for safe handling (Abrishamian,
1991).
4.2 Identification of Air Emission
Points
The air emissions associated with
thermal desorption come from several
sources. The point sources of air emissions
vary widely with each process. The stack of
an afterburner vents combustion products, as
does a fuel-fired heating system if the
combustion gases are not fed into the
desorber. The fuel-fired heating system
typically operates with propane, natural gas,
or fuel oil. If the VOC emission controls
consist of a baghouse, scrubber, and vapor
phase carbon adsorber, the offgas will
contain small concentrations of the original
contaminants, as well as products of any
chemical reactions that might occur.
The volume of off-gas from a
thermal desorption unit depends on the type
of processor. Devices that are heated
indirectly have offgases composed of
volatilized VOCs and water from the soil
being treated and, possibly, some sweep gas
used to carry the contaminants out of the
device. This volume of gas is typically
1,000 to 5,000 acfrn (Troxler, 1991). In
directly heated units, the off-gas contains
volatilized contaminants and water, but also
the combustion gases used to heat the soil.
4-7
-------
The result is a much larger volume of off-
gas that needs to be treated, around 10,000
to 50,000 acfm (Troxler, 1991). Therefore,
off-gases from indirectly heated units, i.e.
thermal screws, can be treated with smaller
chemical/physical systems, such as a
baghouse or a condenser, followed by an
afterburner.
Fugitive emissions from area sources
may contribute significantly to the total air
emissions from a remediation site. Probably
the largest source is excavation of the
contaminated soil. Other sources may
include the classifier, feed conveyor, and the
feed hopper. Fugitive emissions from the
components of the thermal desorption
system and controls are possible as well.
Emissions also may emanate from the waste
streams such as exhaust gases from the
heating system, treated soil, particulate
control dust, untreated oil from the oil/water
separator, spent carbon from liquid or vapor
phase carbon adsorber, treated water, and
scrubber sludge.
4.3 Typical Air Emission Species of
Concern
The volatile and semi-volative
contaminants under remediation are the
species emitted if no destruction or other
chemical treatment has taken place.
Combustion products such as
particulate matter, nitrogen oxides (NOx),
carbon monoxide (CO), and acid gases may
be emitted if a destructive control device,
such as an afterburner, is used or if the
heating system is fuel-fired. In some cases,
pyrolysis occurs to a certain degree in the
dryer, so products from these reactions also
may be emitted.
4.4 Summary of Air Emissions Data
Air emissions from thermal
desorption systems are influenced by the
waste characteristics, the desorption process,
and the emissions control equipment. As
noted above, pyrolysis may occur at the
elevated temperatures in the desorber.
Dioxins, furans, and phenol concentrations
have been reported to increase with
temperature (Foster, et al., 1992). The
emissions data presented below are divided
into two categories: emissions for asphalt
aggregate dryers and emissions for other
mobile units.
4.4.1 Air Emissions Data for Asphalt
Aggregate Dryers
The VOC emissions from asphalt
aggregate dryers will vary by several orders
of magnitude depending on whether
afterburners are used as a control device.
These treatment systems typically do not
employ VOC controls, unless they have
been modified for soil remediation.
Soil Purification, Inc. (SPI), a
subsidiary of a leading manufacturer of
asphalt plants, has estimated the typical
emissions for soil treatment in a modified
asphalt aggregate dryer. This system
consists of a direct-fired rotary drum
operating at 550-1000°F. A primary
cyclonic tube collector and pulse-jet
baghouse are used to control particulate
emissions. A thermal oxidizer (i.e.,
afterburner) destroys organic compounds in
the off-gas stream (99-99.99% efficiency).
Based on a processing rate of 35-60 tons per
hour, typical emissions from this type of unit
are:
• Particulate: 0.02-0.03 gr/dscf; and
4-8
-------
Total VOC: 0.1-5 lb/hr.
Data are given for three asphalt
plants that were modified for the treatment
of petroleum contaminated soils.
Summaries of the soil properties and
emission characteristics at these plants are
presented in Tables 4-2a and 4-2b.
Afterburners were not used on any of these
systems. Each site is discussed in more
detail below.
Soil contaminated with diesel fuel
and gasoline were treated at an asphalt plant
with a 450 tons/hour capacity at 5%
moisture (Barr, 1990). Soil enters the dryer
opposite of the burner and flows
countercurrent to the combustion gases.
This configuration allows the VOCs which
desorb from the soil in the upper portion of
the dryer to exit the system without
exposure to the burner flame. The results
presented for this plant represent worst-case
conditions because all of the VOCs
volatilized from the soil may not be
destroyed and no additional VOC control
device is present (Barr, 1990). The hot
exhaust gases are routed to a wet scrubber
and a cyclonic demister. The gas is then
emitted to the atmosphere through the stack.
The feed rate for the diesel fuel and
gasoline contaminated soils for the test runs
were 280 and 255 tons/hour, respectively.
The air pollution control equipment
accommodates 80,000 acfm at 300°F (Barr,
1990). The soil headspace concentrations
and removal efficiencies are reported for the
remediation tests. Measured total
hydrocarbon (THC) emission rates for these
tests were 254 and 310 lb carbon per hour
(i.e., about ten times the typical emission
rate during asphalt production). Emission
rates of particulate matter were 64 and 67
lbs/hour.
A second trial burn was performed
on a soil contaminated with petroleum
hydrocarbons. The plant treats up to 120
tons/hour of soil at temperatures around
350-400°F (Batten, 1987). The exhaust gas
from the system contained 129 and 175
ppmv of THC above background. THCs
were emitted at a rate between 30.4 and 47.7
lb/hr. The estimated emission factor for
total non-methane hydrocarbons was 0.21 to
0.26 lbs per ton of soil treated. Based on the
results, Batten (1987) concluded that
hydrocarbon controls would be necessary in
order for the system to meet air pollution
control requirements.
The Soil Cleanup System (SCS,
from Earth Purification Engineering, Inc.)
was demonstrated in the treatment of diesel-
contaminated soil from a leaking
underground fuel tank in Kingvale,
California. The SCS is an asphalt recycling
unit modified to treat contaminated soils.
The offgas from the rotary kiln is routed to
dual cyclones, an exhaust cooler, and a
baghouse. The soil exits the system at
775°F. The emission rates for non-methane
VOCs and semi-volatile organics were 1.04
and 1.57 lb/hour, respectively, or 0.44 and
0.67 lb/ton assuming 1.25 ton/yd3 (SCS,
1990).
4.4.2 Air Emissions Data for Mobile
Units
Thermal desorption has been used at
many sites for the treatment of soils
contaminated with various materials.
Examples are described below. Additional
data are given in the case studies in Section
4-9
-------
Table 4-2
Characteristics of Asphalt Aggregate Dryers
Table 4-2a. Typical Soil Properties3
Parameter
Initial Concentration
(ppm)
Final Concentration (ppm)
Removal Eff. (%)
Benzene
0.11-39.5
<0.01-0.06
84.5-99.9
Toluene
0.27-<2
<0.01-0.1
NA
m,p-Xylenes
<0.8-<3
0.2-1.2
<75
o-Xylcncs
3.1-15.6
<0.01
99.7-99.9
Total Xylenes
13.1
0.1
99.2
Ethylbenzene
0.11
<0.01
>90
THC
39-393
5.7-9.5
85-97.5
Diesel
1875
<1
>99.9
"Based on two or three installations depending on the parameter.
Table 4-2b. Typical Offgas Characteristicsb
Parameter
Stack Concentration
Units
Benzene
4.3-8.6
ppmd
Toluene
0.6-0.8
ppmd
m,p-Xylcnes
0.42-3.5
ppmd
THC
129-2,800
ppm
Naphthalene
5,136-6,757
^g/Nm3
Acenaphtylene
634-901
A^g/Nm3
Accnaphthene
317-638
^g/Nm3
Fluoranthene
405-763
^g/Nm3
Phcnanthrene
385-645
^g/Nm3
Anthracene
<1.4-427
^g/Nm3
Fluoranthene
24-135
^g/Nm3
Pyrene
32-111
Aig/Nm1
bBased on two installations. Emission control equipment consists of a wet scrubber and cyclonic demister.
4-10
-------
4.9, including data on dioxin and furan
emissions.
According to Weston Services, Inc.,
the use of their full-scale LT3 system on the
Springfield, Illinois cleanup of gasoline and
No. 2 fuel oil-contaminated soils produced
stack emissions that were in compliance
with federal and state regulations, including
VOCs, HC1, CO, and particulates (Nielson
and Cosmos, 1989). The emission rate of
BTEX was 1079 grams/hour before controls
and 21 grams/hour after the control devices.
ReTec's thermal adsorption unit was
used in the remediation of coal tar-
contaminated soil. Molten salt in a thermal
screw was used to indirectly heat the soil to
approximately 450° F. The soil was treated
at a rate of 100 pounds per hour. The
controlled emissions of BTEX were 0.26
grams per hour or 0.011 lb/ton (U.S. EPA,
1991).
At the McKin Superfund Site in
Gray, Maine, soil containing primarily
trichloroethylene (TCE) was treated by
Canonie Environmental Services
Corporation. Temperatures varied between
150 and 380°F, and the capacity was 1-4
cubic yards per batch. To achieve 0.1 ppm
TCE concentration in the treated soil, the
temperature was adjusted to 300° F for 6-8
minutes (Webster, 1986). The total reported
emission rates were 24 g/hr.
The Thermotech Systems
Corporation's Portable Soil Remediation
Unit was used to treat petroleum
contaminated soils in Washington, D.C. and
Grand Rapids, MN. The unit has air
pollution controls for particulate matter
(dust collector) and organics (thermal
oxidizer). For the Washington, D.C. site,
the particulate, BTEX, and TPH emissions
were 5.0, 0.13, and 0.42 pounds per hour,
respectively. The emission rate for
particulates from the Grand Rapids site was
2.4 lb/hr (Thermotech, 1990-1991).
U.S. Waste Thermal Processing's
Mobile Thermal Processor, Model 100, was
used to treat gasoline- and diesel-
contaminated soils. The transportable
treatment unit consists of a primary furnace
with an afterburner to incinerate the
combustibles. The offgas from the
afterburner is routed to a wet scrubber for
particulate removal. The soil exit
temperature is maintained between 300 and
650° F, and the afterburner operates at
1800°F, with a minimum residence time of
0.5 seconds. The scrubber is a dual-venturi
collision scrubber. The test was performed
on soil at 5000 and 5500 mg/kg
contamination levels of gasoline and diesel
fuel, respectively. The particulate emission
rates were 4.2 and 2.7 lb/day (Remedial
Technology Unit, 1990).
The Todds Lane Soil Remediation
Plant handles soils contaminated with
petroleum hydrocarbons. Pollution control
devices include a cyclone, multiclones, a
baghouse, and an afterburner. The
maximum anticipated concentrations of
certain VOCs in the soil were used to
estimate the emission rates of the
compounds after the afterburner, assuming
99% efficiency. The total emission rate for
BTEX was determined to be 2.1 pounds per
hour (United Engineers and Constructors,
1991).
The Soil Remediation Unit (SRU)
202 consists of a rotary kiln, an afterburner,
and a baghouse. This unit was used to treat
contaminated soil, and the emissions were
4-
11
-------
reported as follows: particulate -1.7 to 2.5
lb/hr and VOC - 0.1 to 0.74 lb/hr (Air
Consulting and Engineering, 1991).
The pilot-scale X*TRAX system
uses an externally-fired rotary kiln for the
treatment of soils contaminated with
hazardous wastes. The offgas is first treated
in a liquid scrubber where particulate matter
is removed. The gas is then cooled further
to allow for condensation of the
contaminants. The gas is routed through a
particulate filter and to a carbon adsorber
where most of the remaining organics are
removed. The VOC emissions ranged from
0.01-0.08 lb/day for the treatment of clay
and sandy soils (U.S. EPA, 1991).
A pilot-scale test was performed by
IT Corporation for the treatment of creosote-
contaminated soils at the Burlington
Northern Superfund Site. The thermal
desorption unit was operated at 1025°F and
a residence time of 10 minutes. The
treatment unit consists of a rotating desorber
tube partially enclosed within a gas-fired
furnace shell. Nitrogen is introduced into
the system to flush out desorbed
contaminants and to maintain an atmosphere
that does not support combustion. The
offgas is treated with a cyclone, a primary
scrubber, a condenser, a demisting filter, a
particulate filter, and an activated carbon
unit. Finally, the offgas is scrubbed in a
secondary scrubber and then discharged to
the atmosphere. These values represent the
average of six samples (IT, 1991). The IT
system was also used to treat PCB
contaminated soils at a rate of 40 to 70
pounds per hour. The results of these tests
are presented in Table 4-3; the operating
temperature and residence time varied for
each run.
4.5 Identification of Applicable
Control Technologies
Control of volatile organic emissions
is crucial to the overall success of thermal
desorption remediation of contaminated
soils. The process uses physical separation
driven by heat, so the vaporized
contaminants would simply be transferred
from one medium (soil) to another (air) if no
emission controls were employed.
The types of controls available
include both destruction and separation
technologies. Typically two to six types of
controls are used in series; they are chosen
to suit the specific VOC contaminants
present and the other pollutants of concern.
Liquid-phase and solid-waste streams
usually are treated on site or stored for
subsequent off-site treatment. Depending on
the types of contaminants present and their
concentrations, it may be feasible to recover
and reuse the volatilized contaminants. The
offgas stream often is routed to the burner
that provides heat to the dryer.
Typical VOC controls for point
sources are briefly described below; Section
5.5 contains additional information. More
detailed information is available in a recent
EPA report (Eklund, et al., 1992). Asphalt
kilns will have similar air emission control
devices as mobile thermal desorption units,
except that no VOC controls are typically
employed and the air flowrates are higher,
requiring some differences in design
parameters.
Many low-temperature thermal
desorption (LTTD) control devices use an
off-gas treatment system consisting of a
cyclone, afterburner, quench, and baghouse
(fabric filter). The cyclone is used to reduce
4-
12
-------
Table 4-3
Estimated Emissions of Selected Compounds for the Cleanup
of PCB-Contaminated Soil Using the IT Process
Contaminant
Residence
Time
(minutes)
Temperature
°F
Initial
Concentration
Final
Concentration
Units
Rate of
Uncontrolled
Emissions
g/hr
Overall
Estimated
Percent
Efficiency
Estimated
Emissions
Rate
g/hr
PCB's
19
1022
37.5
2
ppm
1.14
95%
5.68e-02
2,3,7,8-TCDD
40
1040
260
0.018
PPb
0.00832
95%
4.16e-04
2,3,7,8-TCDD
19
1040
236
0.018
PPb
0.00755
95%
3.78e-04
2,3,7,8-TCDD
10.5
1040
266
0.018
PPb
0.00851
95%
4.26e-04
2,3,7,8-TCDD
24
860
233
0.5
PPb
0.00744
95%
3.72e-04
2,3,7,8-TCDD
5.6
1022
48
0.084
PPb
0.00153
95%
7.67e-05
2,3,7,8-TCDD
20
1031
56
0.23
PPb
0.00178
95%
8.92e-05
-------
the particulate loading on downstream
devices. The baghouse may be placed
before or after the afterburner; it efficiently
removes particulates to low levels. The
afterburner oxidizes organics and CO by
thermal destruction. Some LTTD systems
use an afterburner followed by a quench
chamber and a venturi wet scrubber. This
system is capable of controlling acid gases if
they are a concern. Some systems collect
the organic contaminants, as shown in
Figure 4-2, rather than destroying them.
4.5.1 Particulate Removal
Off-gases from the desorber typically
pass first through a particulate control
device. Particles that become entrained in
the off-gas stream may be removed with
cyclones, venturi scrubbers, or fabric filters.
Collected particulates are usually returned to
the incoming waste stream and retreated
with the soil.
Cyclone collectors remove particles
by creating a vortex from the inlet gas
stream velocity. Centrifugal acceleration
forces entrained particles outward where
they collide with the wall and fall to a
collection point. Cyclones efficiently
remove the bulk of larger particles, however,
venturi scrubbers or baghouses are required
to remove smaller particles.
Venturi scrubbers are sometimes
used to treat desorber off-gas, and efficiently
remove particles greater than 0.5 |^m in
diameter using an aqueous stream. The
performance is not affected by corrosive,
sticky, or flammable particles, but high
collection efficiencies require a higher
pressure drop and thus are more costly to
operate (Sink, 1991). The scrubber may also
serve as the initial condensation stage for
water and organic compounds.
The fabric filter may be a series of
fine-mesh synthetic fabric bags similar to
the type used in asphalt batch plants. An
induced draft fan can be used to draw the
exhaust gas through a filter. The filter may
be a jet-pulse design such that high-pressure
(80 psig) air periodically removes
accumulated particulates to collection bins.
Dust from the bins may then be combined
with the contaminated soil for reprocessing.
The maximum allowable pressure drop
across the filter may be 15 inches of water
(Weston, 1990), though 3 to 8 inches of
water is typical.
4.5.2 Condenser
Condensers can be used to remove
VOCs from a vapor stream if the design is
efficient for removing the specific
contaminants that are present. This physical
separation process operates on the basis of
the contaminants' vapor pressures, which
vary widely. By reducing temperature or
increasing pressure until the saturation vapor
pressure is reached, the vapor condenses to a
liquid phase and is treated accordingly.
Contaminants with high vapor pressures
require correspondingly low condensation
temperatures. In these situations, a quencher
that removes a large portion of the moisture
present often precedes the condenser to
prevent icing. The coolant may be air,
ambient water, brine, chilled water, or
refrigerants. A separator directs the
vapor/gas and liquid streams to appropriate
control systems.
4.5.3 Liquid Phase Treatment
4-14
-------
The liquid from the condenser is
sometimes partially treated on-site. The
liquid is separated by a gravity oil/water
separator. The insoluble light organic
fraction is skimmed off the top, placed into
5 5-gallon drums and stored for off-site
treatment. The contaminated water from the
separator is passed through carbon
adsorption columns and then typically
recycled on-site. Potential water uses
include dust control, service makeup, and
cooling of the treated soil.
4.5.4 VOC Control by Afterburner
Fume incinerators (i.e., afterburners)
often are used for the control of VOC
emissions from thermal desorption systems,
especially for systems used for treating
underground storage tank sites. An
afterburner used in one system identified in
the literature is a 3.5 million-BTU/hr
(MMBTU/hr) gas-fired fume incinerator, but
afterburners may fire gas at up to 40
MMBTU/hr.
Afterburners typically operate at
1400-1800 °F and have a residence time of
0.5-2 seconds. The air that carries the
vaporized contaminants serves as the
combustion air. The flame vortex exposes
the VOCs to temperatures and turbulence
necessary for complete combustion. A
combustion air (offgas) fan maintains a
minimum of three percent excess oxygen
exiting the afterburner. Exhaust gases
leaving the afterburner are sometimes mixed
with ambient air to be cooled and then
passed through a scrubber (Weston, 1990).
Hot gases typically are quenched with water
prior to entering a baghouse.
4.5.5 VOC Control by Carbon
Adsorption
Often used as a polishing process
after other treatments, carbon adsorption
works on the principle that contaminants are
physically adsorbed onto the activated
carbon. No chemical change or reduction of
the waste amount occurs. Adsorption
processes can occur in either the liquid or
vapor phase. Regeneration or disposal of
spent carbon may also produce emissions,
though this is very rarely done on-site.
Liquid-phase carbon adsorption
usually treats water containing low
contaminant concentrations with a two-stage
system. Clean water is often used to cool
discharge solids from the desorber and
suppress dust formation (Nielson and
Cosmos, 1989).
4.5.6 Scrubber
Exhaust gases from thermal
destruction processes may be treated in a
scrubber to remove particulates or neutralize
acid gases. Wet scrubbers use a liquid to
absorb pollutants from a waste gas stream;
the process is enhanced through a large
liquid/gas contact surface area. Wet
scrubbers operate by either chemical
absorption (reaction between pollutant and
liquid), or physical absorption (pollutant
trapped by liquid). Dry scrubbers operate by
chemical absorption. Acid gases are not
typically a concern when processing
petroleum-contaminated soils because of
low concentrations of halogenated
compounds (Troxler, 1991). Particulate
scrubbers (Venturis) can be employed to
capture the particles by impingement and
agglomeration with liquid droplets. If a wet
scrubber is used to treat the off-gases, a
liquid separator is needed downstream of the
scrubber, such as a cyclone or mist
eliminator.
4-
15
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4.5.7 Miscellaneous System Adaptations
and Control Approaches
Other emissions-control techniques
include using treated water for dust control
and using ultraviolet light. Ultraviolet rays
have been used to destroy dioxin in the
condensate from the thermal desorption of
contaminated soils.
While conducting a pilot study of the
McKin Superfund site in Gray, Maine,
Canonie Environmental Services
Corporation made efforts to control VOC
and dust emissions from excavation and
aeration processes. The soil was
contaminated with trichloroethylene (TCE).
Excavation down to 40 feet was conducted
with a kelly bar caisson rig fitted with a
digging bucket and attached to a 100-foot
crane. Soils discharged from the digging
bucket entered a front-end loader equipped
with a removable plastic cover. Cylindrical
steel caissons were augered into the deep
excavation holes to prevent further
volatilization (Webster, 1986).
4.6 Capital and Operating Costs for
Remediation
Because thermal desorption is
virtually never used without controls, the
costs reflect emission controls as well as
remediation. Most thermal desorption units
offered by vendors are predesigned systems
with VOC and particulate controls already
installed. This is especially true for mobile
systems, which are typically housed on flat
bed trailers. Asphalt plants do not typically
have VOC controls, but if they have been
modified to treat soils, the organic control
device may already be added.
The costs for thermal desorption
(exclusive of emission control costs) for
treatment of soils contaminated with
petroleum hydrocarbons typically range
from $50 - 125/ton for low temperature
thermal screw units and from $35 - 100/ton
for rotary dryers (Troxler, 1991).
IT Corporation performed a pilot
study for cleanup of PCBs on the
Rosemount Research Center site of the
University of Minnesota. IT estimated that
direct operating costs for a full-scale system
would be about $80/ton based on a 10
ton/hour system treating soil with 20 percent
moisture. This figure includes $60/ton for
labor, utilities, fuel, materials and supplies,
and administrative costs, as well as $20/ton
for depreciation. These are hopper-to-
hopper treatment costs; total costs are likely
to be $175 to $350 per ton (Troxler, 1991).
Costs depend on the contaminants present
and site conditions. Cost estimations should
take into consideration planning and
procurement, permitting, site preparation,
equipment mobilization, equipment
erection/startup, operations, equipment
decontamination and demobilization, and
site closure (Fox, et al., 1991).
Soil contaminated with Herbicide
Orange at the Naval Construction Battalion
Center (NCBC) in Gulfport, Mississippi was
treated with the IT Corporation's pilot-scale
thermal desorption/ultraviolet apparatus
(TD/UV). The costs for treating the dioxin-
contaminated soil are summarized below
and include the cost of ultraviolet
destruction technology, which is not
typically a part of the thermal desorption
process (Helsel and Thomas, 1987):
4-16
-------
Amount of Soil,
Mg
(tons)
Total
Cost,
million $
Cost
Per Mg, $
(ton, $)
9,071 (10,000)
6,0
544 (600)
18,143 (20,000)
8.0
365 (402)
36,287 (40,000)
11.8
268 (295)
Remediation Technologies, Inc.
estimates the cost of treating oily soils and
sludges to be in the range of $100-$300/ton
of feed. The costs depend on quantity of
waste, term of the contract, and moisture and
organic content of the contaminated soil.
Estimated costs for some other systems are
presented in Table 4-4.
4.7 Capital and Operating Costs for
Emission Controls
Costs for emission controls are
included in the remediation costs given in
Section 4.6. The installed cost of complete
thermal desorption systems that include
treatment of offgases and condensates
usually is about 2-4 times the cost of the
thermal units themselves (Abrishamian,
1991).
Cost estimates were determined for
thermal oxidizes and fabric filters used with
thermal desorption units (See Tables 4-5 and
4-6). The cost estimates were calculated
from procedures outlined in various U.S.
EPA documents. These values were also
compared with vendor quotes. The
estimation was performed for gas flow rates
of 5,000,15,000, and 40,000 acfin. The
total capital investment was determined for
both mechanical shakers and pulse-jet fabric
filters and includes equipment and
installation costs. Site preparation and
construction costs are not included in this
Figure. The results are presented in Table
4-6.
The cost estimate for an afterburner,
or thermal oxidizer, was based on similar
flow rates (5,000, 15,000, and 40,000 scfm).
Two cases were considered for each flow
rate: a) no heat exchanger (no heat recovery
from the thermal oxidizer) and b) 50% heat
recovery. The cost estimates and vendor
information are summarized in Table 4-5.
As stated earlier, thermal desorption units
are typically sold as a predesigned unit that
already incorporates the control devices into
the total cost of the system.
4.8 Equations/Models for Estimating
Emissions
Theoretical models based on
fundamental principles have been proposed
for predicting the evolution of volatile
compounds from soil in the thermal
desorption process (Lighty, et al, 1990).
Both particle desorption and bed desorption
were examined. The models are partial
differential equations based on mass and
energy balances and on the Freundlich
isotherm equation. In practice, an
assessment of the applicability of thermal
desorption for a given site is not based on
modeling calculations, but instead on the
types of contaminants present in the soil, the
physical properties of the soil, and the
results of any bench-, pilot- or full-scale test
runs. In most cases, the process conditions,
such as temperature and residence time, can
be modified to yield the desired removal
efficiency, though heavier weight petroleum
fuels, such as No. 6 fuel oil, may present
problems for systems with relatively low
operating temperatures. The cost to operate
at these process conditions, however, will
4-17
-------
Table 4-4
Costs Including Emission Controls for Various Thermal Desorption Units
System
Cost,
$/Mg feed
($/ton feed)
Soil Characteristics
Soil Feed Rate,
Mg/hr (tons/hr)
X*TRAX™, Chemical Waste
Management
136-318
(150-350)
30% moisture;
<10% organics
—
LTTA, Canonie Environmental
Services, Corp.
73-136
(80-150)
—
27-45
(30-50)
LT3, Roy F. Weston
91-109
(100-120)
20% moisture;
10,000 ppm organics
9
(10)
SOURCE: Johnson and Cosmos, 1989
Table 4-5
Cost Information for Thermal Oxidizers
Estimated Capital Cost3
Heat Recovery (%)
Flow Rate (scfm)
(1992 $)
Vendor Estimatesb
0
5,000
156,000
100,000c
15,000
209,000
300,000°
40,000
304,000
—
50
5,000
304,000
150,000°
15,000
437,000
450,000°
40,000
580,000
—
"Estimated capital costs based on correlations given in the OAQPS Control Cost Manual
(Vatavuk, 1990).
Typical cost from Soil Purification, Inc. given as $75-300,000 for a thermal oxidizer for a
"typical" size system.
Conversion Technology, Inc.
4-18
-------
aEstimated capital costs based on correlations given in the OAQPS Control Cost Manual
(Vatavuk, 1990).
bTypical cost from Soil Purification Inc. given as $250-350,000 for a pulsed-jet fabric filter for a
"typical" size portable system.
cDustex Corporation.
Note: Cost difference may reflect differences in installed versus delivered costs.
Table 4-6
Cost Information for Fabric Filters
Estimated Capital Cost3
Filter Type
Flow Rate (acfm)
(1992 $)
Vendor Estimatesb
Mechanical Shaker
5,000
159,000
24,000c
15,000
298,000
36,400c
40,000
509,000
—
Pulse-Jet Fabric Filter
5,000
124,000
30,000c
15,000
205,000
52,000c
40,000
456,000
—
dictate whether or not thermal desorption is
competitive with other remediation options.
Using removal efficiencies obtained
from test runs, a mass balance yields the
following equation to estimate an emission
rate for a volatile compound leaving the
desorber. This estimate does not include
emissions from excavation or other handling
of contaminated soil nor does it include
fugitive emissions from the desorber system
or from liquid and solid phase waste
streams. Combustion gases from the heating
system and exhaust gases from afterburners
produce additional emissions not taken into
account by this estimation method.
ERi KC/lOOOXFXV/lOOXl - CE/100)
where:
ERj = emission rate for contaminant i
(g/hr);
Q = concentration of species i in
contaminated soil (mg/kg);
1000 = conversion factor (mg/g);
F = mass rate of soil treated (kg/hr);
V; = percentage of contaminant i
volatilized; and
CEj = percent efficiency of control devices.
Default values have been published by the
U.S. EPA (Eklund, et al., 1993). The default
value for the mass feed rate is 27,200 kg/hr,
with a range of 2,700 to 90,800 kg/hr. The
default value for the percent volatilized is
4-19
-------
dependent on the desorber temperature. For
200 to 600 °F, the values are:
VOCs/BTEX
99.00%
SVOCs/PNAas
90.00%
THC
95.00%
PCBs
50.00%
a PNA = Polynuclear Aromatic
For desorber temperatures of 600 to 1,000
°F, the values are:
VOCs/BTEX
99.99%
SVOCs/PNAs
99.00%
THC
99.90%
PCBs
99.00%
4.9 Case Studies on Remediation and
Air Emissions
Thermal desorption has been used at
a number of sites in recent years. However,
little performance data from these full-scale
operations have been published. Results
from five EPA-sponsored projects are
presented in this section. These results
include thermal desorption effectiveness and
air emissions for soil contaminants, VOCs,
SVOCs, dioxins, and fiirans.
4.9.1 Use of LTTA on Pesticides
The Low Temperature Thermal
Aeration (LTTA) system of Canonie
Environmental Services Corporation was
used at an abandoned pesticides mixing
facility in Arizona. The waste consisted of
soil contaminated with toxaphene, DDT,
DDD, DDE, and others at a total
concentration of 5 to 120 mg/kg.
Contaminated soil was heated counter
currently to 730° F in a rotating cylinder,
with heat provided by propane or fuel oil.
Residence time was 9-12 minutes and the
process throughput was 34 tons/hour. The
emission controls included cyclones,
baghouse, venturi scrubber, and carbon
adsorbers. The scrubber liquid blowdown
was treated by carbon adsorbers and reused
as a wetting agent for the treated soil.
Performance is summarized in Table
4-7 (Peck, 1995). Process streams were
sampled for VOCs and SVOCs. Although
specific results were not available, stack
emissions included acetonitrile,
acrylonitrile, chloromethane, benzene, and
toluene. The study concluded that these
compounds were formed within the process,
but dioxins and fiirans were not formed.
4.9.2 Use of LT3® to Treat Lagoon
Sludge Contaminated with VOCs
and SVOCs
The Low Temperature Thermal
Treatment (LT3) process of Roy F. Weston,
Inc. was use to treat a sludge primarily
contaminated with 4,4'-methylenebis
(2-chloroaniline) (MBOCA) in Michigan.
The MBOCA concentration in the sludge
ranged from 43.6 to 860 mg/kg. The
process equipment consisted of two troughs,
each with two hollow-screw conveyors. Hot
oil flowed through the screws, heating the
sludge to 500-530° F. Residence time was
90 minutes and process capacity was 2.1
tons/hour. The emission controls included a
baghouse, air-cooled condenser, refrigerated
condenser, and carbon adsorber. Condensed
liquids were routed to an oil-water separator,
a paper filter, carbon adsorber, and sent to
off-site disposal. Process performance is
summarized in Table 4-8.
4-20
-------
Table 4-7
Results for Use of LTTA System on Pesticide-Contaminated Soil
Parameter
Untreated Soil
(PPb)
Treated Soil
(PPb)
Off-gas to GAC
(PPb)
Stack Gas
(ng/dscm)
Toxaphene
18,300
<20
<50
<98.6
DDT
18,700
<1.06
<2.0
8.2
DDD
220
<0.39
<1.0
<1.97
DDE
6,980
677
79
1,980
Total PCDD
ND
ND
ND
0.057
Total PCDF
0.1
ND
ND
0.017
Table 4-8
Results for Use of LT3 System on Lagoon Sludge
Parameter
Untreated Soil
Treated Soil
Off-gas to
Adsorber
Stack Gas
MBOCA
43.6-860 mg/kg
3-9.6 mg/kg
NA
ND
VOCs:
Toluene
1-25 mg/kg
<30 ng/kg
8-10 ppmv
"effectively
removed"
PCE
690-1900 mg/kg
<30 ^g/kg
210-220 ppbv
"effectively
removed"
SVOCs:
3- and 4-
methylphenol
3100-20,000
Hg/kg
540-4000 ng/kg
ND
ND
bis(2-ethyl
hexyl)phthalate
1100-7900
Hg/kg
<820 ng/kg
<28 ppbv
ND
TNMHC
—
—
—
6.7-11 ppmv
Total PCDD
0.21 ng/kg
1.52 ng/kg
0.483 ng/dscm
0.0606
ng/dscm
Total PCDF
ND
2.49 ng/kg
0.33 ng/dscm
0.0699
ue/dscm
4-21
-------
4.9.3 Use of X*TRAX to Treat PCB
Contaminated Soil
The RUST Remedial Services, Inc.
X*TRAX Model 200 Thermal
DesorptionSystem was used to remove
PCBs and other organic contaminants from
soil at a site in Massachusetts. The soil was
treated in a rotating cylinder which was
heated by hot flue gases flowing in an
annular region outside the treatment
cylinder. The soil was heated in five zones,
to an average temperature of 850-928° F.
Residence time was about 2 hours and the
equipment capacity was 4.9 tons/hour. A
nitrogen carrier gas and the off-gases were
treated by a concurrent spray scrubber, air-
cooled condenser, refrigerated condenser
(40° F), and mist eliminator. Most gas was
then returned to the process heater, but 5-
10% was vented after passing through a 10
(am filter, a high efficiency particulate air
(HEPA) filter, and carbon adsorbers.
Condensates were separated into water,
organic, and sludge streams, with the sludge
then mixed with the contaminated soil feed.
Separated water was used for scrubber
makeup and for wetting the treated soil. The
organic stream was sent to off-site treatment.
System performance is summarized in
Table 4-9.
4.9.4 Use of ATP to Treat PCB
Contaminated Soil
The SoilTech ATP Systems, Inc.
Anaerobic Thermal Processor was used to
remove PCBs and other organic
contaminants from soil at two sites, one in
New York and one in Illinois. The process
was essentially the same at both sites. In a
four-step process, the soil is heated to
500°F, 1100°F, 1300°F, and then cooled to
600° F, with a total treatment time of about
30-40 minutes. The soil is indirectly heated
in an anaerobic environment.
Dehalogenation reagents (sodium hydroxide
and polyethylene glycol) are added to the
contaminated soil prior to its entering the
ATP. The process capacity was 10
tons/hour. Off-gases were treated by a
cyclone, scrubber, condenser, and a three-
phase separator, which produced gas, water,
and organic streams. The treated gas was
returned to the combustion zone of the ATP.
Organics were mixed with inlet soil and
water was treated on-site. Performance for
the two sites is summarized in Table 4-10.
Some SVOCs were present in the soil in low
concentrations. However, the SVOCs were
either not detectable or were below the
practical quantitation limit in both the
treated solids and the stack gas. Likewise,
some VOCs were also present in low
concentrations in the contaminated soil and
most were below detection limits in the
treated soil samples. Stack gas samples
were not analyzed for VOCs.
4.10 References
Abrishamian, R. Thermal Desorption of
Oily Soils and Sludges. Presented at the
84th Annual AWMA Meeting, Vancouver,
June 1991.
Air Consulting and Engineering, Inc.
Personal communication. 1991.
Barr Engineering. Personal communication.
1990.
Batten, R.L. Air Emissions From an
Asphalt Plant Rotary Drum Aggregate Dryer
Used to Decontaminate Gasoline
Contaminated Soil (Trial Burn).
Presentation at the CAPCOA Engineers
Technical Seminar, December 2-4, 1987.
4-22
-------
Table 4-9
Results for Use of X*TRAX System to Treat PCB-Contaminated Soil
Parameter
Untreated
Soil
Treated Soil
Stack Gas
Total PCBs
318 mg/kg
0.863 mg/kg
ND
VOCs:
Chloromethane
--
—
369.9 |xg/m3
Methyl chloride
--
—
17.6 jig/m3
Toluene
—
--
3.2 ng/m3
Total VOCs
—
—
396.6 |xg/m3
SVOCs:
Hexanedionic acid ester
--
—
70.7 ng/m3
9-Octadecen-l-ol
--
—
33.7 ng/m3
Total SVOCs
--
—
188.2 ng/m3
Total PCDD
310 ng/kg
74.1 ng/kg
0.0304 ng/m3
Total PCDF
597 ng/kg
93.7 ng/kg
0.0158 ng/m3
Total 2,3,7,8-TCDD TEQa
28.8 ng/kg
3.47 ng/kg
0.000323 ng/m3
a TCCD = Tetrachlorodibenzodioxin
TEQ = Toxic Equivalent
4-23
-------
Table 4-10
Results For Use of ATP Process to Treat PCB-Contaminated Soil
PCB Contaminated Soil Treatment in New York
Parameter
Untreated
Soil
Treated Soil
Stack Gas
Total PCBs
28.2 mg/kg
0.043 mg/kg
23.1 ng/dscm
Total PCDD
3.2 ng/kg
ND
3.86 ng/dscm
Total PCDF
0.16 ng/kg
ND
5.66 ng/dscm
Total 2,3,7,8-TCDD TEQ
—
--
0.707 ng/dscm
PCB Contaminated Soil Treatment in Illinois
Parameter
Untreated
Soil
Treated Soil
Stack Gas
Total PCBs
9761 mg/kg
2 mg/kg
0.837 fig/dscm
Total PCDD
ND
ND
ND
Total PCDF
104 jxg/kg
6.05 jxg/kg
0.0787 ng/dscm
Total 2,3,7,8-TCDD TEQ
—
—
0
4-24
-------
de Percin, P.R., 1991a. Thermal Desorption
Attainable Remediation Levels. In:
Proceedings of the 17th Annual Hazardous
Waste Research Symposium, EPA/600/9-
91/002, pp511-520. April 1991.
de Percin, P.R., 1991b. Thermal Desorption
Technologies. Presented at the 84th Annual
Meeting of AWMA, Vancouver, BC, June
1991.
de Percin, P.R., 1991c. Personal
communication. U.S. EPA, Cincinnati, OH.
1991.
Eklund, B., et al. Control of Air Emissions
from Superfund Sites. EPA/625/R-92/012
(NTIS PB93-215614). November 1992.
Eklund, B., W. Dulaney, C. Thompson, and
S. Mischler. Estimation of Air Impacts for
Thermal Desorption Units Used at
Superfund Sites. EPA-451/R-93-005 (NTIS
PB93-215630). April 1993.
Foster, R., et al. Low Temperature Thermal
Treatment (LT3) Technology - Roy F.
Weston, Inc. EPA/540/AR-92/019 (NTIS
PB93-124047). December 1992.
Fox, R.D., E.S. Alperin, and H.H. Huls.
Thermal Treatment For the Removal of
PCBs and Other Organics from Soil. Env.
Progress, Vol. 10, No. 1, pp40-44, February
1991.
Helsel, R.W. and R.W. Thomas. Thermal
Desorption/Ultraviolet Photolysis Process
Technology Research, Test, and Evaluation
Performed at the Naval Construction
Battalion Center, Gulfport, MS, For the
USAF Installation Program - Volumes I and
IV. AFESC, Tyndall Air Force Base, FL.
Report No. ESL-TR-87-28. December
1987.
Hutzler, N.J., B.E. Murphy, and J.S. Gierke.
State of Technology Review — Soil Vapor
Extraction Systems. Report No. EPA-
600/2-89/024 (NTIS PB89-195184). U.S.
EPA, Cincinnati, OH, June 1989.
IT Environmental Programs, Inc. and IT
Corporation. Personal communication with
John Carroll of IT. 1991.
Johnson, et al. A Practical Approach to the
Design, Operation, and Monitoring of In
Situ Soil-Venting Systems. Ground Water
Monitoring Review, pp 159-178. Spring
1990.
Johnson, N.P. and M.G. Cosmos. Thermal
Treatment Technologies for Hazardous
Waste Remediation. Pollution Engineering.
October 1989.
Lighty, J.S., et al. Fundamentals for the
Thermal Remediation of Contaminated
Soils. Particle and Bed Desorption Models.
ES&T Vol. 24, No. 5, pp750-757, May
1990.
Michaels, P.A., 1989a. Technology
Evaluation Report: SITE Program
Demonstration Test. Terra Vac In Situ
Vacuum Extraction System Groveland,
Massachusetts, Volume I. Report No. EPA-
540/5-89/003a (NTIS PB89-192025). U.S.
EPA, Cincinnati, OH, April 1989.
Nielson, R.K. and M.G. Cosmos. Low
Temperature Thermal Treatment (LT3) of
Volatile Organic Compounds From Soil: A
Technology Demonstrated. Env. Progress,
Vol. 8, No. 2, ppl39-142, May 1989.
4-25
-------
PES Corp. Soil Vapor Extraction VOC
Control Technology Assessment. EPA-
450/4-89-017 (NTIS PB90-216995).
September 1989.
Remedial Technology Unit. Personal
communication. R. Lewis, California
Department of Health Services. 1990.
Sink, M.K. Handbook of Control
Technologies for Hazardous Air Pollutant.
EPA/625/6-91/014 (NTIS PB92-141373).
June 1991.
Soil Purification, Inc. Vendor Information
Concerning Asphalt Kilns Modified for the
Treatment of Contaminated Soils. 1991.
Soil Cleanup System (SCS). Personal
communication with John Schmuck of Soil
Recycling Technologies, Inc. 1990.
Thermotech Systems Corporation. Vendor
Information Concerning Laboratory Results,
Emissions and Remediation Reports for the
Portable Soil Remediation Unit.
Thermotech Systems Corporation, Orlando,
FL. 1990-1991.
Troxler, W.L. Personal communication,
Focus Environmental, Inc., Knoxville, TN.
1991.
with Michael Kendall of the Baltimore
County Department of Environmental
Protection and Resource Management.
August 1991.
U.S. EPA. Engineering Bulletin - Thermal
Desorption Treatment. EPA/540/2-91/008
(NTIS PB91-228080). May 1991.
Vatavuk, W.M. OAQPS Control Cost
Manual (4th Edition). EPA/450/3-90/006
(NTIS PB90-169954). January 1990.
Webster, D.M. Pilot Study of Enclosed
Thermal Soil Aeration for Removal of
Volatile Organic Contamination at the
McKin Superfund Site. JAPCA, Vol 36,
No. 10, ppl 156-1163, October 1986.
R.F. Weston, Inc. Task Order 4,
Demonstration of Thermal Stripping of JP-4
and Other VOCs From Soils at Tinker Air
Force Base, Oklahoma City, OK.
USATHAMA Report No. CETHA-TE-CR-
90026. March 1990.
Troxler, W.L., J.J. Cudahy, R.P. Zink, S.I.
Rosenthal, and J.J. Cudahy. Treatment of
Petroleum Contaminated Soils by Thermal
Desorption Technologies. Presented at the
85th Annual Meeting of AWMA (Paper 92-
33.05), Kansas City, MO. June 1992.
United Engineers and Constructors. Air
Toxics Screening Analysis, Todds Lan Soil
Remediation Plant. United Engineers,
Philadelphia, PA. Personal communication
4-26
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5.0 SOIL VAPOR EXTRACTION
5.1 Process Description
Soil vapor extraction (SVE) is a
commonly-used method for treating soil
contaminated with volatile hydrocarbons.
The process is sometimes referred to as soil
venting, vacuum extraction, aeration, or in-
situ volatilization. A closely related
remediation technology-bioventing is
described in Section 6. In general terms, soil
vapor extraction removes volatile organic
constituents from contaminated soil by
creating sufficient subsurface air flow to
strip contaminants from the vadose
(unsaturated) zone by volatilization. As the
contaminant vapors are removed, they may
be vented directly to the atmosphere or
controlled in a number of ways.
Soil vapor extraction has been
widely used to remediate sites contaminated
with gasoline or chlorinated solvents (e.g.,
TCE). It also is sometimes used to
minimize migration of vapors into structures
or residential areas during other types of
remediation. By its nature, SVE is an on-
site, in-situ treatment method.
Complete removal may not be
possible unless the source of vapors (e.g.,
hydrocarbon lens on groundwater) also is
removed, so SVE often is used in
conjunction with or following other remedial
measures such as excavation of subsurface
waste bodies, removal (pumping) of any
hydrocarbon lens that is present, or air
stripping of contaminated ground water.
Combined two-phase treatment of both
ground water and soil gas has been used
successfully for several years (Welshans, et
al., 1991), and increasingly is employed.
The success of SVE for a given
application depends on numerous factors
with the three key criteria being: 1) the
nature of the contamination; 2) the behavior
of subsurface vapor flow at the site; and
3) regulatory requirements.
Spills or leaks of fuels typically
involve liquids containing dozens of
different constituents. For removal by SVE
to be effective, the contaminants generally
must have vapor pressures greater than
1.0 mm Hg at 20°F. A simplified decision
guide forjudging the applicability of SVE is
shown in Figure 5-1.
The tendency of the organic
contaminants to partition into water or to be
adsorbed onto soil particles also affects SVE
effectiveness, so the compound's water
solubility, Henry's Law constant, and soil
sorption coefficient are of interest. The soil
temperature affects each of these variables
and hence, the rate of vapor diffusion and
transport.
The concentrations of contaminants
that are initially present affect their relative
partitioning between vapor and liquid
phases, and the amount that is solubilized or
adsorbed. The time that the contamination
has been present also is an important factor,
as mixtures of contaminants will generally
become depleted of their more volatile
components over time through
volatilization. This process, referred to as
weathering, will tend to cause SVE to
become progressively less applicable as the
site ages. It also affects the operation of the
SVE system, as the more volatile
components are typically removed first and
the composition of the vapors collected and
treated varies over time.
5-1
-------
VAPOR
PRESSURE
Butane
Pentane
Benzene
Toluene
Phenol
Naphthalene
Aldicait
—10"
—10
-2
—10
—10
SVE
LIKELIHOOD
OF
SUCCESS
SOIL AIR
PERMEABILITY
L, i
SUCCESS
VERY
LIKELY
Z SUCCESS
> LESS
I UKELY
V
ik
,v-|
SUCCESS
SOMEWHAT
LIKELY
HIGH
(gravel,
coarse
sand)
MEDIUM
(fine sand)
LOW
(clay)
TIME
SINCE
RELEASE
Match Point
Figure 5-1. Simplified Guide to Applicability of Soil Vapor Extraction.
Source: (Pedersen and Curtis, 1991)
-------
As mentioned above, soil
temperature is an important variable in the
effectiveness of SVE. Increasing the soil
temperature is one option commonly
considered for enhancing SVE performance.
Soil can be heated in one of three ways: 1)
introduction of heated air or steam, 2) input
of electromagnetic energy through the soil,
or 3) heat release through chemical reaction
(HWC, 1994a). The use of heated air or
steam appears to be the most widely used
approach to full-scale thermally enhanced
remediation (HWC, 1992). Approaches
such as microwave, radio frequency, and
electrical heating have been tested at the
pilot scale (George, et al., 1992); (HWC,
1993); and (HWC, 1994b), but full-scale
results are not yet available.
Although SVE may be used in a
variety of soil types, the effectiveness will
depend on the ability of air to flow through
the soil. The ability of vapors to flow
through a porous media such as soil is
usually defined as the air permeability. Any
factors that influence the air permeability of
the soil, such as soil porosity, grain size,
moisture content, depth to ground water, and
stratification must be taken into
consideration when planning this type of
remediation. The presence of cracks,
inadequately grouted boreholes, or other
subsurface conduits will alter the subsurface
flow patterns. The goal is to direct the air
flow through the contaminated zone and
minimize short-circuiting through bypasses.
SVE may not be practical for sites where the
source of vapors is deep underground (e.g.,
>100 feet), in areas with shallow
groundwater tables (e.g., <10 feet) or at sites
where the groundwater level fluctuates
greatly over time. It has been suggested that
SVE is not effective for the fraction of
organic pollutants that are trapped inside the
soil matrix (Travis and Macinnis, 1992).
The types of contaminants present
and the clean-up criteria will affect the cost-
effectiveness of SVE versus other
remediation options. The final cleanup level
for contaminants in the soil will dictate
whether or not SVE is a viable option. Very
stringent cleanup levels may dictate
excavation of the soil and further on-site
treatment. Air emission regulations may
require the use of controls to reduce the
level of contaminants in the SVE exhaust
gas. The cost of such emission controls may
influence the overall selection of a
remediation approach.
Figure 5-2 shows a generalized
process flow diagram for the SVE process.
Typical systems include extraction wells,
monitoring wells, air inlet wells, vacuum
pumps, vapor treatment devices,
vapor/liquid separators, and liquid-phase
treatment devices. Wells are generally 4 to
8 inches in diameter. An option sometimes
employed is to introduce the air at the air
inlet well into the saturated zone (i.e.,
groundwater table). This technique, referred
to as air sparging, acts to strip some of the
volatile and semi-volatile compounds from
the ground water.
A number of potential problems may
arise in implementation of soil vapor
extraction, but effective solutions exist for
most problems. If there is concern that
contaminant vapors from other sources may
be drawn in by the vacuum system, air inlet
wells may be placed around the perimeter of
the site to limit remediation to the site under
treatment. To avoid channelized flow,
butterfly or ball valves may be placed on the
monitoring or extraction wells so that they
may be shut down if necessary.
The extent of short circuiting through
other wells can be determined using a tracer
gas (Olschewski, et al., 1995). If
5-3
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Clean Flue Gas
VAPOR
TREATMENT
VACUUM
PUMP
STACK
VAPOR-LIQUID
SEPARATOR
LIQUID
TREATMENT
CLEAN
WATER
PUMP
Air
Air
AIR
INLET
WELL
AIR
INLET
WELL
EXTRACTION
WELL
EXTRACTION
WELL
Soil Surface
Air
Air
Vadose Zone
Water Table
Figure 5-2. Generalized Process Flow Diagram for Soil Vapor Extraction.
5-4
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contaminated water is extracted in the
process, a liquid phase treatment system is
usually installed. The oxygen introduced by
SVE can promote the growth of iron-
utilizing bacteria and lead to decreased
pump efficiencies for groundwater
extraction; this problem can be minimized
by a chlorination program (McCann, et al.,
1994).
In bioventing (see Section 6), the rate
of vapor extraction is relatively low and the
primary objective is to introduce oxygen into
the subsurface to promote microbiological
activity. This is not the primary goal for
SVE, but introduction of oxygen into the
subsurface during SVE may, as a side
benefit, enhance biodegradation and thereby
improve the overall remediation efficiency.
Evidence of unusually high carbon dioxide
levels indicates that some sites may
experience enhanced subsurface
biodegradation that may be partially or
wholly a result of soil vapor extraction. At
one site, carbon dioxide concentrations in
the soil gas were 8.5%; much higher than the
0.03% or 0.04% typically present in the
atmosphere, though co-disposed municipal
waste could have been partially responsible
for the high levels. Rough calculations
indicated that up to 40% of the gasoline was
destroyed by degradation.
The relative advantages of SVE over
other remediation approaches are:
• the equipment is readily available
and simple to install and operate;
• large volumes of soil can be treated
in a cost-effective manner;
• remediation can proceed in many
cases without disrupting on-going
commercial activities at the site; and
• air emissions are released from a
point source and, thus, can readily be
controlled.
The major disadvantages of SVE
versus other remediation approaches are
that:
• The method is not applicable for
saturated soils or soils with low air-
permeabilities;
• the success of the method varies with
the volatility (vapor pressure) of the
contaminants present; and
• significant residual contamination
may remain in the soil after treatment
under some remediation scenarios.
A number of reports and articles
have been published that provide useful
information regarding SVE systems. The
best single source of information is an EPA
report (Pedersen and Curtis, 1991). Much of
the information in this section was drawn
from that report and a second EPA report
(Thompson, et al., 1991). Other key
references are two studies that include
summarized information about existing SVE
systems in use at field sites (Hutzler, et al.
1989; and PES, 1989), an evaluation
conducted under EPA's SITE program
(Michaels, 1989a), and an overview paper
(Johnson, et al., 1990). The Johnson, et al.,
paper is given as Appendix E of this report
and EPA's Engineering Bulletin on SVE is
contained in Appendix F of this report.
5.2 Identification of Air Emission
Points
The air emissions associated with
SVE systems come primarily from the stack.
Stack heights are typically 10-30 feet and
5-5
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usually only one stack is used (Eklund, et
al., 1992a). Additional releases of volatile
organics may occur from the treatment of
any contaminated water that is extracted.
Fugitive emissions are considered negligible
due to the negative pressure throughout most
of the system.
5.3 Typical Air Emission Species of
Concern
Emissions include untreated volatile
organics from the extraction process.
Removal and emissions of semi-volatile
organic compounds will also occur, though
with less efficiency than for VOCs. Lesser
amounts of air emissions associated with the
control system may also occur. Due to the
variety of technologies used for vapor
treatment, stack emissions may include
products of incomplete combustion, NOx,
particulate matter, CO, and acid gases. Of
primary concern, however, are the volatile
organics emitted from the point sources.
5.4 Summary Of Air Emissions Data
Air emissions data for several SVE
systems are summarized in Table 5-1. The
data are from a variety of soil vapor
extraction systems. Overall, there is little
detailed published information about air
emissions from SVE systems, making it
difficult to assess the representativeness of
this sample.
The emission rate of VOC
compounds over time from continuously
operated SVE systems tends to show an
exponential-type decay curve. If the system
is stopped and then restarted, however, the
VOC emission rate returns to near the
original rate unless the remediation is
nearing completion. Shutting off the
vacuum allows the soil-gas equilibrium to
become re-established. Due to this
behavior, the most efficient method of
operation often is to run the SVE system
only for a part of each day or week, i.e.,
operate in a "pulsed" mode.
Published emission factors for SVE
systems based on typical operating
conditions (Thompson, et al., 1991) are:
• Uncontrolled Emissions: 25,000 g/hr
or 250 kg/day (based on 10 hours of
operation).
• Controlled Emissions: 1,250 g/hr or
0.05 g/g VOC in soil.
5.5 Identification of Applicable
Control Technologies
As the vapors are removed from the
soil, they are either discharged to the
atmosphere or treated to reduce air
emissions. Direct combustion is
theoretically possible if the hydrocarbon
content of the exhaust gas is high enough,
but the concentration typically drops
significantly during removal. Therefore,
natural gas or some other fuel would be
needed to maintain combustion. Also, for
safety reasons, dilution air typically is added
to maintain the VOC concentration below
the lower explosive limit (LEL).
For lower levels of hydrocarbons,
catalytic oxidation may be effective. Carbon
adsorption systems often are used, but they
may be costly to implement and are
generally not acceptable for high-humidity
gas streams. An EPA survey from the late
1980s indicates that the exhaust from about
50% of SVE systems is vented directly to
the atmosphere with no controls (PES,
1989). The trend, however, is for VOC
5-6
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Table 5-1
Summary of Emissions Data for SVE Systems
Source
No. of
Systems
Surveyed
Parameter
Units
Range or Value
Approximate
Average
Crow
(1987)
13
Flow Rate Per Well
cmm
(cfm)
0.2-8
(5.3 - 300)
2
(80)
Removal
kg/day
(lb/day)
0.9-113
(2 - 250)
27
(60)
Exhaust Gas Concentration
ppmv
20 - 350
100
Hutzler, et al.
(1989)
19
Total Flow Rate
cmm
(cfm)
0.1-161
(3 - 5,700)
23
(800)
Treatment:
- None
- Carbon
- Catalytic Incineration
- Combustion
# systems
9
6
1
1
NA
Removal Rate
kg/day
(lb/day)
2-195
(4 - 430)
45
(100)
PES (1989)
17
Total Row Rate
cmm
(cfm)
0.7-318
(25- 11,300)
62
(2,200)
Pollutant Concentration
ppmv
150-38,000
4,000
Control Efficiency
%
90-99
95
controls to be required. For those systems
requiring controls, the most viable options
are:
1)
activated carbon adsorption;
2)
catalytic oxidation;
3)
thermal incineration;
4)
internal combustion engine; and
5)
miscellaneous control approaches.
The first three treatment options are
the most commonly used for large SVE
systems such as those used at Superfund
sites or refineries. Internal combustion
engines (ICE) are a common choice for
control of emissions for small systems such
as those used at Leaking Underground
Storage Tank (LUST) sites. Removal
efficiencies of 95-99% for VOCs should be
theoretically achievable with any of these
control options.
No single control method is
preferred. Each has advantages and
disadvantages that must be considered for
each specific application. Control options
are discussed below. Further information is
available from EPA's Technology Transfer
5-7
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and Support Division (TTSD) (Eklund, et
al., 1992b).
5.5.1 Carbon Adsorption
Carbon adsorption using GAC is the
most common control method for SVE
systems. VOCs are removed by being
physically trapped on the surface of the
GAC or by chemical reactions with the
carbon. The efficiency of GAC is due to its
very large surface area per unit mass. Two
options for GAC systems are available: 1)
"throw away" systems, and 2) fixed bed
regenerable systems. In the first option,
canisters of GAC are used and disposed of
or reactivated off-site. In regenerable
systems, steam or hot air is used to strip
contaminants from the GAC in place. The
contaminants are recovered as a liquid. The
cost-effectiveness of regenerable systems
will increase as the treatment time and the
mass of contaminants to be treated increase.
Modular, skid-mounted treatment
systems are available from numerous
vendors. Prefabricated GAC units
containing up to a ton of carbon are
available. Flow rates over 1,000 scfm can
be accommodated.
The primary advantage of carbon
adsorption over other control options is that
the control efficiency of GAC systems is not
significantly affected by the changes in air
flow rate and VOC concentration that
typically occur at SVE sites. It is applicable
to most contaminants having molecular
weights between 50 and 150; lighter
compounds tend to pass through the GAC
unadsorbed, and heavier compounds tend to
bind permanently to the carbon and cannot
be desorbed. GAC tends to be the control
method of choice for SVE systems with low
VOC concentrations in the exhaust gas (e.g.
less than 500-1000 ppmv). Removal
efficiencies can exceed 99% under optimal
conditions, which include adequate
residence time, moderate temperature (100-
130°F), and no fouling compounds present
in the gas stream.
Carbon adsorption has several
limitations that may be significant for SVE
applications as shown below. One, water
vapor will occupy adsorption-sites and
reduce the removal capacity. It is usually
recommended that the gas to be treated has a
relative humidity of less than 50% for GAC
to be effective. Two, carbon tends to not
retain organics at temperatures exceeding
150°F. This temperature is well below the
temperatures of 200 to 800 °F in the exhaust
gas that can be caused by compression of
offgas in the removal pump. The air can be
cooled or pumps used that do not add much
heat to the system (e.g., liquid ring seal
pumps). Three, high mass loadings of
VOCs in the exhaust gas will cause the
carbon to be exhausted quickly and result in
high costs to replace or regenerate the
carbon. The first two limitations can be off-
set through modifications to the system
design, but these modifications will increase
the cost of remediation.
5.5.2 Thermal Incineration
Thermal incineration can be used to
destroy vapor-phase contaminants.
Contaminant-laden vapors are heated to
temperatures above 1000°F via a direct
flame or a combustion chamber. The
method is applicable to a wide range of
compounds and over a large range of
concentrations. It is not, however, widely
used for SVE applications except for large-
scale, long-term cleanups. For the flame to
be self-sustaining, the VOC concentration
needs to be at percent levels that may be
5-8
-------
above the lower explosive limit for the
contaminant of concern. For lower VOC
levels, auxiliary fuel such as methane or
propane must be added. The cost of this fuel
can be prohibitive. The efficiency of the
method is also affected by changes in the
flow rate. As the flow rate varies from
design conditions, the mixing and residence
times in the incinerator will vary and
decrease the destruction efficiency. Design
efficiency typically is 98% or higher.
5.5.3 Catalytic Oxidation
Catalytic oxidation, also called
catalytic incineration, is similar in design
and operation to thermal incineration except
that a catalyst is present that enhances
combustion. The catalyst is usually
palladium or platinum in a metallic mesh,
ceramic honeycomb, or catalyst-impregnated
beads in a packed bed. The catalyst allows
destruction to occur at lower temperatures
than for thermal incineration (600-900°F).
There is therefore less auxiliary fuel required
and commensurate lower fuel costs.
Design efficiencies of 95 to 99%
percent are typical. The catalyst can be
damaged by overheating, so the air stream
must be diluted, if necessary, to a VOC
concentration below about 3000 ppmv, to
maintain acceptable operating temperatures.
Maintenance of this VOC level raises the
capital and operating cost of the system
since accurate monitoring of the gas stream
is needed, as is the ability to control the
dilution of the gas stream. As for thermal
incinerators, catalytic oxidation systems
function best when the flow rate is constant.
The catalyst will become less
effective over time and can be adversely
affected by trace contaminants in the gas
stream. Depending on the type of catalyst
employed, it can be damaged by chlorinated
hydrocarbons, mercury, phosphorus, or
heavy metals.
5.5.4 Internal Combustion Engines (IC)
Industrial or automotive engines
have been widely used to control VOC
emissions from SVE systems. Depending
on the engine size, air flows of 30 to 100
scfm have been treated. The effective flow
rate is reduced, however, if ambient air must
be added to the air stream to add sufficient
oxygen to support combustion. As with
other thermal treatment methods,
supplemental fuel is needed.
Destruction efficiencies of 99+%
have been reported for the most common
components of gasoline (Pedersen and
Curtis, 1991). Advantages of IC engines as
controls are that the systems are portable,
they can handle very concentrated air
streams without the need for dilution, and
the engine can provide power to operate the
SVE system. Disadvantages are that the
systems can only treat small flow rates and
that manual supervision is required for a
period during start-up to set the flow rates
and operating conditions. Emissions of
NOx from the engine may be a concern in
some locales.
5.5.5 Miscellaneous Control Approaches
A number of additional control
devices may be applicable for controlling
VOC emissions from SVE systems,
including condensers, packed bed thermal
processors, and biofilters. Condensers using
chilled water or other refrigerants can
remove anywhere from 50 to 90% of VOCs
from concentrated streams (>5000 ppmv
VOCs). Packed bed thermal processors
consist of a bed of ceramic beads heated to
5-9
-------
1800°F that is used to destroy organics and
chlorinated hydrocarbons. Biofilters consist
of soil beds that trap VOCs in a manner
analogous to GAC and then are regenerated
by biological action. Biotreatment requires
time to establish an active culture of
microbes and careful control of soil
moisture, temperature, and air flow patterns
to maintain the efficiency of the microbial
action.
5.6 Costs For Remediation
The costs to install and operate an
SVE system will vary from site to site. A
typical cost to install and start up a small
system is less than $100,000 (Newton,
1990). Total capital costs for equipment
range from $65,000 to $135,000, excluding
the cost of each vapor-recovery well
(Cochran, 1987). Typical capital costs for
the major components of the system
(Pedersen and Curtis, 1991) are $2,000 to
$4,000 per well, $10,000 or more for a
vacuum pump (25 hp positive displacement
blower), $2,500 for an air/water separator,
and $10,000 for a structure to house the
system. A major variable is the cost of any
monitoring and control system needed to
maintain the VOC level in the exhaust
stream within preset limits. VOC control
costs are discussed in the next subsection.
Typical operation and maintenance
costs are $6,000 to $26,000 per year
(Cochran, 1987). The major operating costs
(Pedersen and Curtis, 1991) are for power,
VOC controls, monitoring, and labor.
Power costs for a 10 hp system are estimated
to be about $600 per month. Monitoring
and labor costs are highly variable. In
general, operating costs in these areas can be
minimized through the use of automated
monitoring and control equipment. The
optimal split for this trade-off between
capital and operating costs will depend on
the duration of the remediation and the
proximity of the site to the labor source.
Remediation costs often are reported
in terms of cost per volume of soil treated.
Typical operating costs for SVE at a site
with no off-gas treatment and no wastewater
generated range from $ 11 per ton at a large
site with sandy soil to $55 per ton at a small
site with clay soil (Michaels, 1989b).
As discussed in Section 5.1, soil
heating can enhance SVE performance. One
option, hot air injection, is most cost-
effective using electric immersion heaters
for 50-kW or smaller systems. Natural gas
burners are used for larger systems. The
installed cost of a 50-kW hot air injection
system, with stainless steel injection wells,
is about $15,000 to $22,000; electricity cost
is about $3,600 per month. A 200-kW
steam injection system burning natural gas
will cost about $35,000 to $45,000 installed,
with operating costs of gas and water of
about $7,500 per month (HWC, 1994a).
5.7 Costs For Emission Controls
Equations for predicting the costs of
emission controls based on system design
parameters are available (PES, 1989).
Typical costs for various types and sizes of
treatment systems are given in Table 5-2.
The cost estimates are drawn from a number
of vendors and, therefore, a range is shown
in most cases. The costs from different
vendors may not be directly comparable
since the cost basis may vary. For example,
regenerable carbon adsorption systems cost
from $22,000 (one bed) to $55,000 (six
beds) for manually regenerated systems and
5-
10
-------
Table 5-2
Summary of Capital Costs to Control VOC Emissions From SVE Systems
Maximum Flow scmm
Treatment
(scfm)
Capital Cost ($)
Carbon Adsorption
3(105)
20,000"
(Regenerable)
7 (250)
24,000a
14 (500)
33,OOOa
31 (1100)
12,000b
Carbon Canisters
3(100)
700
14 (500)
8,000c
28 (1000)
6,000
113 (4000)
23,000c
Thermal Incineration
2(70)
13,000"
3(100)
25,000"
16 (570)
44,000d
Catalytic Oxidation
3(100)
25,000e
6(200)
31,000 - 69,000e
14 (500)
44,000 - 86,000e
28(1000)
77,000f
142(5000)
140,0008
Internal Combustion Engine
2(60)
62,000
3(100)
50,000
Source: Adapted from Pedersen and Curtis, 1991.
" Includes blower, demister, controls, gauges, valves, and flow ammeter.
b Includes blower, flexible connector, and damper.
c Deep bed units.
d Includes blower, sampling valves, and controls. Heat recovery systems are not included
e Includes burner, blower, flame arrestor, gauges, filters, knockout pot, sampling port, controls,
and skid mounting.
f Dilution system available for an additional $22,000.
8 Source: Eklund, et al., 1992b.
5-11
-------
about $165,000 for a fully-automated
equivalent system (Pedersen and Curtis,
1991). The cost data are intended to show
the general level of costs likely to be
incurred for various types of control options.
Maintenance costs will vary
depending on the type of system and may
include power, fuel, activated carbon, and
the associated labor. The costs will vary
with the size of the system and the operating
rates. Electricity cost to run a 10-hp blower
motor is about $600 per month. Fuel costs
for thermal incineration and catalytic
oxidation depend on the VOC concentration
of the influent air. Typical costs are $500 to
$1,000 per month. Auxiliary fuel costs for
IC engines are also about $500 to $ 1,000 per
month. Activated carbon will cost from $1
to $2 per pound. However, an additional
consideration is that an IC engine can power
a generator, thus reducing electrical costs to
operate pumps and blowers. Typical carbon
costs are about $25 per pound of
hydrocarbons removed (about $160 per
gallon).
In terms of costs per volume of soil
treated, one source estimates the cost of
activated carbon can range from $ 16 per ton
to $28 per ton (Michaels, 1989b). The cost
of wastewater treatment or disposal (if
required) is site-specific and may vary
widely.
5.8 Equations and Models For
Estimating VOC Emissions
The factors that govern vapor
transport in the subsurface are very complex,
and no theoretical models for predicting
emissions or recovery rates for SVE systems
exist that are considered accurate and
reliable due to limitations in obtaining
adequate input data. During operation of
SVE systems, the vacuum that is applied to
the soil and the resulting pressure gradient is
the dominant factor in determining the flow
rate of vapors. The induced vacuum in the
soil decreases with distance from the
extraction well, and a radius of influence
exists that defines the extent to which vapors
can be drawn to the well. The length of this
radius depends on the strength of the
vacuum source; the screened interval of the
well; soil properties such as porosity,
permeability, and moisture content; and site
properties such as surface coverings.
In practice, field tests are typically
performed to evaluate the potential
effectiveness of SVE for a given site. The
field tests may be either pilot-scale
demonstrations of SVE or tests of the air
permeability. This information is used to
determine the number of wells required to
remediate the site and the spacing of the
wells.
Subsurface vapor flow equations
based on Darcy's Law have been published
that predict the flow rate of vented gas
(Johnson, et al., 1990). The key inputs are
the air permeability of the soil, the air-filled
porosity of the soil, the thickness of the soil
layer, the density of the vapor, and the
gradients of pressure and vapor
concentration. Methods for measuring the
air permeability are based on measuring the
difference between the ambient atmospheric
pressure and the air pressure in the soil
during vapor transport.
Johnson, et al., (see Appendix E)
describe a test where air is withdrawn from a
well at a constant flow rate while the draw-
down (vacuum) pressure is measured in a
monitoring well some distance away. The
pressure is plotted versus the log of time,
and the slope of this equation is the air
5-12
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permeability. Measurements at several
monitoring well locations are needed.
Similar test methods may also be employed
such as air injection tests and oil field tests
including pressure buildup and draw-down
tests (Pedersen and Curtis, 1991).
Various computer models are
available for evaluating the feasibility,
design, and performance of SVE systems.
The U.S. EPA recently has evaluated some
of the more commonly used models (Jordan,
Mercer, and Cohen, 1995). The available
models are described in Table 5-3.
For rough estimates of air emissions
from SVE systems, data from pilot-scale
tests at the site can be used with the
following mass balance equation (Eklund
and Albert, 1993):
ER ¦ (C»> (£) (10"f)
where:
ER= Emission rate (g/sec);
C= Cone, in extracted vapors (ng/m3);
Q= Vapor extraction rate (m3/min);
1/60= Conversion factor (min/sec); and
lO^ Conversion factor (g/ng).
The extraction rate, Q, can be
estimated from the results of pilot-scale tests
at the site if any changes in pump size and
number of wells between the pilot- and full-
scale systems are taken into account. If no
pilot-scale data are available, results of field
tests of soil-air permeability can be used to
estimate Q. If these too are not available, a
default value can be used for the extraction
rate. Typical flow rates for Q at Superfund
sites range from 14 m3/min (500 cfm) to 425
m3/min (15,000 cfm), with a typical default
value being Q = 85 m3/min (3,000 cfm).
The contaminant concentration in the
extracted vapors, Cg, can also be estimated
from the results of pilot-scale tests at the
site. The next best approach is to estimate
Cg by collecting samples of the headspace
vapors above the contaminated soil and
measuring the concentration of the
compound(s) of interest. These equilibrium
soil-gas samples can be collected using
ground (soil-gas) probes or by transferring
soil samples from split-spoon samplers (to
minimize VOC losses) to sealed containers
and allowing the headspace to equilibrate.
Field data are required to get an
accurate value for Cg. If no field data are
available, however, a very conservative
value for Cg can be estimated by assuming
that the soil-gas is saturated. The maximum
vapor concentration of any compound in the
extracted vapors is its equilibrium or
"saturated" vapor concentration, which is
calculated from the compound's molecular
weight, vapor pressure at the soil
temperature, and the ideal gas law:
(Pvap)(MW ~ 109)
(R)(T)
where:
Cg= Estimate of contaminant vapor
concentration (pg/m3);
Pvap = Pure component vapor pressure at
the soil temperature (mm Hg);
MW = Molecular weight of component
(g/mole);
R = Gas constant = 62.4 L-mm Hg/mole-
°K;
T = Absolute temperature of soil (°K);
and
109 = Conversion factor (pg-L/g-m3).
5-13
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Table 5-3
Summary of SVE Models Evaluated by the U.S. EPA
Model
Type
Capabilities
Advantages
Limitations
Hardware/Software
Requirements
Availability
Hyper-
Ventilate, v2.0
(IBM PC)
vl.01 (Apple
Macintosh)
Screening
Calculates air
permeability, well flow
rates, mass removal
rate, mass removal
from several idealized
diffusion-limited
scenarios
Calculates contaminant
concentrations over
time for multiple
constituents
Provides rapid
estimates for
determination of the
potential feasibility of
SVE
Provides rapid
estimates of
contaminant
concentrations in
extracted gas, allows
comparison of
removal rates of
different constituents
Analytical air flow
solution
Should not be used
to design SVE
systems
IBM PC or Compatible:
80386/80387 coprocessor
or 80486, 4 MB RAM,
DOS 3.1 or higher,
Microsoft Windows 3.x
and runtime version of
Object PLUS
Apple Macintosh (Plus,
SE, SE/30, II, IIX, or
portable): 1 MB RAM,
Apple HyperCard
Software (v2.0 or greater)
Available from EPA as
EPA/600/R-93/028 (EPA
ORD Publications, 513-
569-7562)'
Object PLUS available from
Object PLUS Corp., 125
Cambridge Park Dr.
Cambridge, MA 021402
VENTING,
v3.01
Screening
Calculates contaminant
concentrations over
time for multiple
constituents
Provides rapid
estimates of
contaminant
concentrations in
extracted gas, allows
comparison of
removal rates of
different constituents
User supplies flow
rate to extraction
well
Simplistic one-
dimensional
representation of
mass transport
Should not be used
to design SVE
systems
IBM PC/AT or
Compatible, DOS, 512
KB RAM, math
coprocessor
Environmental Systems &
Technologies, Inc.
2608 Sheffield Drive,
Blacksburg, VA 24060-
8270
703-552-0685
(Continued)
'From NTIS: Report with disk (PB93-502664/AS)
Report only (PB93-134880/AS)
2From NTIS: IBM PC Disk (S/N 055-000-00427-7)
Macintosh Disk (S/N 055-000-00403-0)
-------
Table 5-3
(Continued)
Model
Type
Capabilities
Advantages
Limitations
Hardware/Software
Requirements
Availability
AIRFLOW1*1
v2.07
Air flow
Calculates pressure
distribution in a radial
domain, calculates air
flow pathlines and
velocities
Easy-to-use 'CAD-
type' graphical user
interface which
simplifies model
input and setup
Rapid setup aids in
hypothesis testing for
simple problems
Many sample
problems included
with the code
Only allows for one
extraction well
No mass transport
IBM PC or compatible,
80386/80486, 4 MB
RAM, DOS 2.0 or higher,
mouse and math
coprocessor for 80386-
based machines
recommended
Waterloo Hydrogeologic
Software
19 McCauley Drive
(RR#2)
Bolton, Ontario,
Canada L7E SR8
905-880-2886
CSUGAS
Air flow
Calculates vacuum
distribution in the
subsurface in inches of
water
Allows full, three-
dimensional analysis
of heterogeneous,
multi-well air flow
problems
Text-based
input/output is
flexible and up to the
user
Lack of easy-to-use
input/output
interface may
intimidate
beginners
No steady-state
solution option
No mass transport
IBM PC AT/XT or
compatible, 640 KB
RAM, DOS 2.0 or higher
Dr. James W. Warner
Department of Civil
Engineering
Colorado State University
Fort Collins, CO 80523
303-491-5048
(Continued)
-------
Table 5-3
(Continued)
Model
Type
Capabilities
Advantages
Limitations
Hardware/Software
Requirements
Availability
AIR3D
Air flow
Calculates pressure
distribution in the
subsurface
Easy-to-use 'CAD-
type' graphical user
interface which
simplifies model
setup and input
Allows three-
dimensional analysis
of complex problems
Users need an
awareness of the
operation and
limitations of the
MODFLOW code
No mass transport
IBM PC or compatible,
DOS 3.3 or higher, 4 MB
RAM, VGA card and
color monitor, mouse is
highly recommended
American Petroleum Inst.
1220 L Street
Northwest
Washington, DC 20005
The original version of
AIR3D (without the GUI) is
available free of charge
from: USGS Book and
Open File Reports
BLDG810, Box 25425
Denver, CO 80225
VENT2D/
VENT3D
Air flow and
multi-
component
contaminant
transport
Calculates pressure
distribution in the
subsurface, multi
component contaminant
constituent
concentrations over
time in the subsurface
Only readily available
compositional flow
and transport code
Source code is
available
Text-based
input/output is
flexible and up to the
user
Grid size limited to
25 x 25 cells (can
be increased with a
different version
available from the
author)
IBM PC or compatible,
80X86 with math
coprocessor, DOS 3.0 or
higher, 525 KB RAM
David A. Benson
524 Claremont Street
Reno, NV 98502
702-322-2104
Source: Jordan and Mercer, 1995.
-------
Values of molecular weight, vapor
pressure at 25 °C, and saturated vapor
concentration at 25 °C are given in Eklund
and Albert, 1993. It is important to note that
the above equation gives the theoretical
maximum value of Cg. It will overpredict Cg
for any compound present in the soil at
relatively low concentrations. It will also
overpredict the long-term average value of
Cg since the concentration of contaminants
in the gas extracted using a SVE system will
tend to drop over time. It can drop by more
than 95% in the first two days of operation,
though pulsed operation will allow the soil-
gas concentration to be periodically re-
established at levels near the initial
concentration.
The above equation assumes that an
infinite source of vapors exists and that the
contaminants are present in the soil or
ground water at relatively high
concentrations (e.g., total hydrocarbons of
500 ppm in the soil). Therefore, the vapor-
phase concentration for a given compound is
assumed to be independent of the
concentration of that same compound in the
soil/liquid matrix.
Removal rates can be 500-600
kg/day or higher, and control efficiencies
(when applicable) range from 60-99%. As
previously mentioned, only about half of the
sites listed used any VOC control
equipment.
5.9 Case Study
Process Description
Terra Vac Incorporated has
developed a vacuum extraction system
designed to remove volatile organic
contaminants from the vadose zone. At the
Groveland, Massachusetts Superfund site,
the contaminated air stream was treated with
two sets of activated carbon canisters
(Michaels, 1989a and Michaels, 1989b).
Due to weather conditions, liquid water was
extracted as well, so a vapor-liquid
separator was included to remove
contaminated water to a holding tank. The
process design is shown in Figure 5-3. Air
inlet wells were not used at this site.
Because no biodegradation was
taking place in this case, the compounds
released to the atmosphere were the same as
those found in the soil. By far the most
predominant contaminant removed was
trichloroethylene, although 1,1,1-
trichloroethane, trans-1,2-dichloroethylene,
and tetrachloroethylene were also extracted.
Emission Factors
Table 5-4 shows emissions factors
for each of the four contaminants. The
estimated total VOC peak emission factor is
18 g/hr. Based on the field data, the carbon
adsorption control device had an efficiency
of better than the 99% assumed in these
calculations. In addition to stack emissions
from vapor treatment, there would be
evaporative emissions from contaminated
water stored on-site in a holding tank.
These emissions would add an estimated 3
g/hr to the total emissions. The removal
efficiency for the total mass of contaminants
present at the site was not demonstrated, nor
was the associated control efficiency.
Costs
The equipment fabrication and
construction costs were estimated to be
$55,000 (in 1991 dollars). The total cost to
treat 6,000 tons of contaminated soil
(removing 1,300 pounds of VOCs) at the
site was estimated to be $310,000 or $52 per
ton. Of this, costs for activated carbon were
$14 per ton and for liquid waste disposal
were $8 per ton. Including power and labor
5-17
-------
Clean Flue Gas
CARBON CANISTERS
VACUUM
PUMP
PUMP
TANK
TRUCK
STACK
HOLDING
TANK
EXTRACTION WELLS
EXTRACTION WELLS
O,
°c
©
>
Q.
Q.
O.
O
MONITORING
_ WELLS
WiterTaMe —""
Figure 5-3. Process Flow Diagram for Terra Vac In Situ Vacuum Extraction System.
5-18
-------
Table 5-4
Estimated Emissions for Terra Vac's In-Situ Vacuum Extraction System
Pollutant
Molecular
Weight g/mol
Peak
Uncontrolled Stack
Emissions
g/hr8
Peak Controlled
Stack Emissions
g/hrb
Trichloroethylene (TCE)
131.29
1,712
17.1
trans-1,2-Dichloroethylene (DCE)
96.94
99.4
0.99
1,1,1 -Trichloroethane (TCA)
133.41
13.6
0.14
Tetrachloroethylene (PCE)
165.83
3.18
0.03
Totals
1,830
18.3
a Uncontrolled emissions equal removal rate of each contaminant.
b Based on estimated 99% overall control efficiency for two carbon adsorption canisters in
series.
5-19
-------
of better than the 99% assumed in these
calculations. In addition to stack emissions
from vapor treatment, there would be
evaporative emissions from contaminated
water stored on-site in a holding tank.
These emissions would add an estimated 3
g/hr to the total emissions. The removal
efficiency for the total mass of contaminants
present at the site was not demonstrated, nor
was the associated control efficiency.
Costs
The equipment fabrication and
construction costs were estimated to be
$55,000 (in 1991 dollars). The total cost to
treat 6,000 tons of contaminated soil
(removing 1,300 pounds of VOCs) at the
site was estimated to be $310,000 or $52 per
ton. Of this, costs for activated carbon were
$14 per ton and for liquid waste disposal
were $8 per ton. Including power and labor
costs, the VOC control system represents
about one-half of the total remediation cost.
5.10 References
American Petroleum Institute, AIR3D,
Washington, DC.
Benson, David A., VENT2D/VENT3D,
Reno, NV.
Cochran, R. Underground Storage Tank
Corrective Action Technologies.
EPA/625/6-87-015 (NTIS PB87-171278).
January 1987.
Colorado State University - Department of
Civil Engineering, CSUGAS, Fort Collins,
CO.
Crow, W.L. Personal communication.
Radian Corporation, Austin, TX. 1987.
Environmental Systems & Technologies,
Inc., VENTING v3.01, Blacksburg, VA.
Eklund, B., et al., 1992a Estimation of Air
Impacts for Soil Vapor Extraction. EPA-
450/1-92-001 (NTIS PB92-143676).
January 1992.
Eklund, B., et al., 1992b. Control of Air
Emissions from Superfund Sites.
EPA/625/R-92/012 (NTIS PB93-215614).
November 1992.
Eklund, B. and C. Albert. Models for
Estimating Air Emission Rates from
Superfund Remedial Actions. EPA-451/R-
93-001 (NTIS PB93-186807). March 1993.
EPA ORD Publications, Hyper-Ventilitate
v2.0 (IBM PC) vl.01 (Apple Macintosh),
EPA/600/R-93/028,sd 1993.
George, C.E., G.R. Lightsey, I. Jun, and J.
Fan. Soil Decontamination via Microwave
and Radio Frequency Co-Volatilization.
Environmental Progress, Vol. 11, No. 3,
pp216-2119, August 1992.
Hutzler, N.J., B.E. Murphy, and J.S. Gierke.
State of Technology Review — Soil Vapor
Extraction Systems. Report No. EPA-
600/2-89/024 (NTIS PB89-195184). U.S.
EPA, Cincinnati, OH, June 1989.
HWC, 1992. In Situ Steam-Enhanced
Extraction Process. The Hazardous Waste
Consultant: July/August 1992. HWC, 1993.
Electrical Heating and Plasma-Based
Destruction May Enhance Soil Vapor
Extraction. The Hazardous Waste
Consultant: March/April 1993.
HWC, 1994a. Survey of Soil Heating
Techniques for Enhanced Vapor Extraction.
5-20
-------
The Hazardous Waste Consultant:
November/December 1994.
HWC, 1994b. Radio Frequency Heating
Technology Enhances Soil Vapor
Extraction. The Hazardous Waste
Consultant: July/August 1994.
Johnson, et al. A Practical Approach to the
Design, Operation, and Monitoring of In
Situ Soil-Venting Systems. Ground Water
Monitoring Review. Spring 1990.
Jordan, D.L., J.W. Mercer, and R.M.Cohen.
Review of Mathematical Modeling for
Evaluating Soil Vapor Extraction Systems.
EPA/540/R-95/513 (NTIS PB95-243051).
July 1995.
McCann, M., P. Boersma, J. Danko, and M.
Guerriero. Remediation of a VOC-
Contaminated Superfund Site Using Soil
Vapor Extraction, Groundwater Extraction,
and Treatment: A Case Study.
Environmental Progress, Vol. 13, No. 3,
pp208-213. August 1994.
Michaels, P.A., 1989a. Technology
Evaluation Report: SITE Program
Demonstration Test. Terra Vac In Situ
Vacuum Extraction System Groveland,
Massachusetts, Volume I. Report No. EPA-
540/5-89/003a (NTIS PB89-192025). U.S.
EPA, Cincinnati, OH, April 1989.
Michaels, P.A., 1989b. Applications
Analysis Report: Terra Vac In Situ Vacuum
Extraction System Groveland,
Massachusetts. Report No. EPA-540/A5-
89/003 (NTIS PB90-126665). U.S. EPA,
Cincinnati, OH, July 1989.
Newton, J. Remediation of Petroleum
Contaminated Soils. Poll. Eng.. 22 (13) 46-
52. December 1990.
Object PLUS Corp., Hyper-Ventilitate
v2.0(IBM PC) vl.01 (Apple Macintosh),
Cambridge, MA.
Olschewski, A., U. Fischer, M. Hofer, and
R. Schulin. Sulfur Hexafluoride as a Gas
Tracer in Soil Venting Operations. Environ.
Sci. Technol., Vol. 29, No. 1, pp264-266.
January 1995.
Pedersen, T.A. and J.T. Curtis. Soil Vapor
Extraction Technology: Reference
Handbook. EPA/540/2-91/003 (NTIS PB91-
168476). February 1991.
PES Corp. Soil Vapor Extraction VOC
Control Technology Assessment. EPA-
450/4-89-017 (NTIS PB90-216995).
September 1989.
Thompson, P., A. Inglis, and B. Eklund.
Emission Factors for Superfund
Remediation Technologies. EPA-450/1-91-
001 (NTIS PB91-190975). March 1991.
Travis, C.C. and J.M. Macinnis. Vapor
Extraction of Organics from Subsurface
Soils - Is it Effective? Environ. Sci.
Technol., Vol. 26, No. 10, ppl885-1887.
November 1992.
Waterloo Hydrogeologic Software,
AIRFLOW™ v2.07, Bolton, Ontario,
Canada.
Welshans, G., B. Behtash, K. Morey, and B.
Sootkoos. AWD Technologies Integrated
AquaDetox®/SVE Technology -
Applications Analysis Report.
EPA/540/A5-91/002 (NTIS PB92-218379).
October 1991.
5-21
-------
6.0 IN-SITU BIODEGRADATION
6.1 Process Description
In-situ biodegradation is the term for
biological treatment processes that are
performed in place and therefore do not
require excavation and removal of the
contaminated soil. Biodegradation of
contaminants in soils is most often
accomplished through bioventing, which
employs subsurface addition of oxygen
through air injection or soil gas extraction to
promote the biodegradation of contaminants.
Other in-situ bioremediation approaches
include the infiltration of nutrients, electron
acceptors (such as oxygen), and
microorganisms to enhance the microbial
activity and remediation of contaminants.
The main purpose of in-situ
treatment is to stimulate the natural
microbiological activity of soil to
decompose organic constituents into carbon
dioxide and water. Systems that work to
enhance this natural biological activity
typically use injection wells to provide an
oxygen source (such as air, pure oxygen, or
hydrogen peroxide) to stimulate aerobic
degradation. In bioventing systems, oxygen
is added to the subsurface through air
injection wells within the contaminated soil
or through vapor extraction wells at the
perimeter of the contaminated zone.
Nutrients may also be needed to support the
growth of waste-consuming
microorganisms. In some cases,
microorganisms that have the ability to
metabolize specific contaminants of interest
may be added to the soil.
During in-situ biotreatment,
biodegradation is actually only one of
several competing mechanisms. The
contaminants may also be leached,
volatilized, undergo chemical degradation,
or be adsorbed onto the soil particles. The
overall removal achieved by in-situ
biotreatment processes represents the
combined impact of all of these
mechanisms. Field studies have shown that
volatilization may account for the majority
of VOCs that are removed (Dupont, 1993;
HWC, 1993; Downey et al., 1994; van Eyk,
1994). Recent bioventing studies, however,
have shown that volatilization can be
minimized by optimizing the air flow rate so
that volatilization accounts for less than 20%
of the total hydrocarbon removal for these
systems (Miller et al., 1991; Dupont, 1993;
Downey et al., 1995). In addition, the vent
gas can be recycled to further increase the
fraction of contaminants biodegraded
(HWC, 1993).
Like all biotreatment processes, in-
situ treatment is not applicable for the
remediation of non-biodegradable
contaminants such as heavy metals and other
inorganic compounds. Some halogenated
organic wastes also are not amenable to
biotreatment or may require substrates to
biodegrade these contaminants. Test data
from 137 sites have shown that bioventing
has almost universal application for
remediating hydrocarbon-contaminated
soils, including gasoline, JP-4, diesel fuel,
heating oils, and waste oils (AFCEE, 1994).
In many instances, sites are
remediated initially using SVE to remove
the more volatile constituents, and then the
air flow rate is decreased and bioventing is
used to biodegrade the remaining
constituents.
Figure 6-1 shows a general
schematic of an in-situ biodegradation
process. Air injection wells are installed
within the zone of contamination to
6-1
-------
Air with
stripped volatiles
to control device
Air
Air
INJECTION
WELL
INJECTION
WELL
VENT
Soil Surfai
Contaminated
Soil
Air
Air
Air
Goal of air injection is to supply additional oxygen
to microbes and speed biodegradation. However,
air injection will also strip volatiles from soil.
Figure 6-1, Flow Diagram for Off-Gas Treatment System For In-Situ Biodegradation
6-2
-------
provide oxygen to stimulate the natural
microbiological activity of the soils. An
extraction or vent well can alternatively be
used to provide oxygen to the subsurface,
but this configuration may require off-gas
treatment.
The primary factor affecting the
volatilization of contaminants is the rate of
air flow through the subsurface. The lower
air flows used in bioventing, relative to soil
vapor extraction systems, enhance
biodegradation while minimizing
volatilization. Other site factors, such as the
temperature and soil moisture, can
significantly affect the biodegradation rate
for a site. As a result, competing
mechanisms such as volatilization may
predominate.
For an in-situ biotreatment process,
the time required to treat the contaminated
soil will vary greatly depending on a number
of factors including the:
• Physical and chemical properties of
the soil matrix;
• Physical and chemical properties of
the contaminant;
• Initial concentration of the
contaminant in the soil; and
• Biodegradability of the contaminants
(i.e., biodegradation rate constants).
Hydrocarbon degradation rates have been
measured from 300 to 7300 mg/kg TPH per
year at numerous bioventing sites
(Fredrickson, 1993; HWC, 1993). One site
showed 99.5% removal as measured by soil
TPH concentrations after 9 months of soil
vapor extraction and 14 months of
bioventing treatment. The average and
maximum initial TPH concentrations were
<1000 mg/kg and 15,000 mg/kg,
respectively. Biodegradation accounted for
44% of the total TPH removal.
The primary advantages of in-situ
treatment, especially bioventing, are
simplicity and low-cost. The equipment and
operating costs for this type of treatment are
very low compared to other technologies.
The mechanical equipment required is
simply a blower to inject or extract air.
The primary disadvantages of in-situ
treatment are that only certain compounds
are amenable to degradation, the removal
efficiency may vary across a site, and the
treatment may be relatively slow.
6.2 Identification of Air Emission
Points
The specific point source of air
emissions from bioventing systems is the
off-gas collected by the extraction system.
These vapors typically are collected through
an extraction system and released through a
short stack. Because the flow rate of
bioventing systems is low and much of the
contaminants are biodegraded in the
subsurface, the off-gas from these systems
often does not require treatment.
In some in-situ bioremediation
systems, air injection wells are used to
supply oxygen and no gas extraction system
is employed. In such systems, area-wide
emissions can occur, but the flow rates are
typically low enough that emissions at the
surface are thought to be minimal.
6-3
-------
6.3 Typical Air Emission Species of
Concern
air emissions, the bioventing system usually
must be optimized.
Typical emissions from in-situ
biotreatment process are a result of the
volatilization of VOCs in the soil. The
primary air emission species of concern are
the specific volatile contaminants present in
the soil. The air emissions may be biased
towards the lighter molecular weight VOCs
that make up the contamination. In addition,
products of partial biodegradation are
possible.
6.4 Summary of Air Emissions Data
Although in-situ biodegradation has
been used to remediate numerous sites
contaminated with petroleum hydrocarbons,
few data on air emissions are available in the
literature. Most bioventing studies have
measured the concentration of contaminants
in the system off-gas to estimate the fraction
of total petroleum hydrocarbons volatilized
versus bioremediated. As previously
mentioned, sites may first be remediated
using SVE to remove the more volatile
constituents followed by bioventing to
biodegrade the remaining constituents.
Depending on the type and volatility of the
contaminant, biodegradation can contribute
from 50% to 90% to the total removal of
petroleum hydrocarbons. Table 6-1 presents
a summary of these data.
Source emission rates were
determined at two sites, as shown in Table
6-2. Although the volatilization was in the
range of 20 to 30 lb/day, the contribution of
volatilization to the total removal was only
10% to 20%. To achieve this ratio of
biodegradation to volatilization and
minimize
The Hill AFB site is a good example
of the difference in operating SVE systems
versus bioventing systems and the amount of
volatilization that can occur. Initially, the
site was remediated by SVE and the
volatilization and biodegradation rates were
200-400 lb/day and 70 lb/day, respectively.
After 9 months of operation, the operating
scheme was modified for bioventing. The
bioventing volatilization and biodegradation
rates were 20 lb/day and 100 lb/day,
respectively.
Flux testing was conducted at five
sites utilizing bioventing systems to measure
the potential surface emissions during
remediation. These results are summarized
in Table 6-3. The maximum surface
emission observed during the study was 2.5
mg/day/m2. Rates of biodegradation are
typically 100 times greater than the rates of
volatilization observed at these sites
(AFCEE, 1994).
6.5 Identification of Applicable
Control Technologies
As the vapors are removed from the
soil, they are either discharged to the
atmosphere or treated to reduce air
emissions. Bioventing utilizes low air flow
rates to provide only enough oxygen to
sustain biological activity, so off-gas
treatment is rarely needed. Off-gas
treatment is most likely to be needed at sites
contaminated with VOCs that have vapor
pressures greater than 1 atm because they
will be more likely to volatilize rather than
biodegrade (Cookson, 1995).
6-4
-------
Table 6-1
Summary of Removal Rates for Bioventing Systems
Site
Contaminant
' Initial Soil
; Concentration
Removal
Due to
Volatilization
Removal
Due to
Biodegradation
Notes
Ref.
Burlington
Northern RR,
NE
No. 2
diesel fuel
20,000 to 50,000 mg/kg
TRPH
<10%
>90%
2-yr bioventing test;
Overall TRPH reduction:
55-60%
Downey et al.,
1995
Eglin AFB, FL
gasoline
1200 mg/kg TRPH
500 mg/kg BTEX
35%
65%
Biodegradation exceeded
volatilization as main removal
mechanism after 30 days.
Downey et al.,
1994
Retail gas
station
gasoline
100 to 20,000 mg/kg
BTEX
100 to 57,000 mg/kg
mineral oil
800 kg
hydrocarbons
(1,764 lb
hydrocarbons)
572 kg
hydrocarbons
(1,261 lb
hydrocarbons)
Initially performed SVE;
reduced air flow after week 67
for bioventing;
2 years of operation
van Eyk, 1994
Tyndall AFB,
FL
jet fuel
NA
26 kg HC (45%)
(57 lb HC)
32 kg HC (55%)
(71 lb HC)
7-mo. test;
Under optimal air-flow
conditions, 82% HC removal
by biodegradation (18% by
volatilization) was achievable
Miller et al.,
1991
Hill AFB, UT
JP-4
max. 15,000 mg/kg
TPH
avg. >1000 mg/kg TPH
53,600 kg (56%)
(118,2001b)
42,100 kg (44%)
(92,900 lb)
Total removal: SVE for 9 mo.
and bioventing for 14 mo.
99.5% overall contaminant
removal
Dupont, 1993
-------
Table 6-2
Summary of Source Emission Rates for Bioventing Systems
Site
Emission Rates
Total Emissions
Notes
Reference
Burlington
Northern
Railroad, NE
0.3 kg/day BTEX
(0.7 lb/day BTEX)
14.7 kg/day diesel
(32 lb/day diesel)
10,700 kg (23,600 lb)
over 2 years
Equivalent to 600 mg/kg TRPH concentration
reduction;
<10% of removal by volatilization
Downey et al., 1995
Hill AFB, UT
9 kg/day
(20 lb/day)
53,600 kg (118,200 lb)
over 2 years (includes 9-
month SVE test)
Biodegradation rate of 45 kg/day (100 lb/day);
<20% of removal by volatilization (during
bioventing test)
Dupont, 1993
-------
Table 6-3
Summary of Surface Emissions at Bioventing Sites
Base
Site Type
Air Injection
Rate, scnura
(scfm)
TVH Flux
Estimate
(g/day)
Initial
Soil Gas TVH
(ppmv)
Plattsburg AFB, NY
Fire training pit
0.4(13)
200
8400
Beale AFB, CA
Fire training pit
0.8 (30)
70
4800
Boiling AFB, D.C.
Diesel fuel spill
0.6 (20)
200
860
Fairchild AFB, WA
JP-4 fuel spill
0.4(15)
150
29000
McClellan AFB, CA
Diesel fuel spill
1.4 (50)
30
380
Source: AFCEE, 1994
TVH = Total volatile hydrocarbons
AFB = Air Force Base
6-7
-------
Although most bioventing systems
do not contain VOC control systems, the
most viable options when controls are
necessary are similar to those for soil vapor
extraction systems. These options include:
• Activated carbon;
• Catalytic oxidation; and
• Internal combustion engine.
Removal efficiencies of 95% to 99% should
be theoretically achievable with any of these
control options. A final option are biofilters
which capture VOCs on soil beds and
biodegrade the contaminants.
6.6 Costs for Remediation
Costs to perform in-situ
bioremediation are low. The major capital
investments are the blower and the treatment
wells. Operating requirements are minimal
and consist mainly of electricity and routine
maintenance. The total costs for bioventing
are in the range of $ 10 to $60 per cubic yard
(AFCEE, 1994). The unit cost for
bioventing is typically lower than SVE
because off-gas treatment is not needed
(Cookson, 1995). Unit costs are much lower
than for low temperature thermal desorption
and excavation/landfarming treatment
processes (HWC, 1993; AFCEE, 1994).
The cost of a full-scale bioventing
system for the remediation of 5,000 cubic
yards of soil with an average concentration
of 3,000 mg/kg of JP-4 would be $90,300.
This estimate includes pilot testing and 2
years of remediation (AFCEE, 1994).
6.7 Costs for Emissions Controls
Typically, emission controls are not
required for bioventing systems. When
controls are required, the cost is likely small,
on the order of $20,000 to $60,000.
However, this cost can be a significant
portion of the total remediation cost for
bioventing systems.
6.8 Equations and Models for
Estimating VOC Emissions
Vapor transport and biodegradation
in contaminated soil are complex and
competing processes. No practical, accurate
theoretical models for predicting emissions
or recovery rates are known to exist for
bioventing systems. The pressure gradient
(and related flow rate) and the
biodegradation rate are the dominant factors
in determining the mass rate of vapors.
Using data from pilot or full-scale
tests at the site, air emissions can be
estimated from the following mass balance
equation (Eklund, et al., 1993):
ER = Cg (Q/60) 10"6
where:
ER = Emission rate for contaminant of
interest (g/sec);
Cg = Concentration of the contaminant in
the soil gas (pg/m3);
Q = Exhaust gas flow rate (m3/min);
1/60 = Conversion factor (min/sec); and
10"6 = Conversion factor (g/^g).
This equation does not address surface
emissions.
If the extraction rate is not available
from pilot tests, it can be estimated from the
following:
6-8
-------
Q = (1.0/1440) SvEa
where:
1.0 = Estimated flow rate for maximum
biodegradation and minimum
volatilization (pore volume/day);
1/1440 = Conversion factor (day/min);
Sv = Volume of soil (m3); and
Ea = Air-filled porosity (fraction).
Bioventing systems typically operate at flow
rates that are equivalent to 0.25 to 2.0 pore
volumes per day. A flow rate of 1.0 pore
volumes per day is thought to maximize the
amount of biodegradation and minimize the
amount of volatilization (Eklund, et al.,
1993). Typically, flow rates for bioventing
systems are between 10 and 50 acfm
(Dupont, 1993).
Field data, such as field
measurements from pilot tests, provide the
most accurate values for the contaminant
concentration. If field data are not available,
a very conservative estimate can be made by
assuming that the soil gas is saturated. The
maximum vapor concentration is its
equilibrium or saturated vapor
concentration:
Cg = £vapMW109
RT
where:
Pvap = Pure contaminant vapor pressure at
the soil temperature (mm Hg);
MW = Molecular weight of contaminant
(g/gmol);
R = Gas constant (62.4 L-mmHg/gmol-
°K);
T = Absolute temperature of soil (°K);
and
109 = Conversion factor (|jg-L/g-m3).
This equation will overpredict the long-term
average value since the soil gas
concentration tends to drop exponentially
over time (Downey et al., 1994). This
calculation also does not account the for
biodegradation of contaminants, which is the
primary removal mechanism in bioventing
processes.
6.9 Case Study
No suitable case study was found for
the in-situ bioremediation of soils
contaminated with petroleum hydrocarbons.
6.10 References
Air Force Center for Environmental
Excellence (AFCEE), Brooks AFB, TX.
Bioventing and Performance Cost Summary.
July 1994.
Cookson, J.T. Bioremediation Engineering,
Design and Application. McGraw-Hill, Inc.,
New York. 1995.
Downey, D.C., O.A. Awosika, and E.
Staes. Initial Results from a Bioventing
System with Vapor Recirculation.
Hydrocarbon Bioremediation. Hinchee,
R.E., B.C. Alleman, R.E. Hoeppel, and R.N.
Miller, Eds. Lewis Publishers, Boca Raton,
pp. 347-352. 1994.
Downey, D.C., P.R. Guest, and J.W. Ratz.
Results of a Two-Year In Situ Bioventing
6-9
-------
Demonstration. Environmental Progress,
Vol. 14, No. 2, pp. 121-125. May 1995.
Dupont, R.R. Fundamentals of Bioventing
Applied to Fuel Contaminated Sites.
Environmental Progress, Vol. 12, No. 1, pp.
45-53. February 1993.
Eklund, B., et al. Estimation of Air Impacts
for Bioventing Systems Used at Superfund
Sites. EPA-451/R-93-003 (NTIS PB93-
215655), April 1993.
Fredrickson, J.K., H. Bolton, and F.J.
Brockman. In Situ and On-Site
Bioreclamation. Environmental Science
Technology, Vol. 27, No. 9, pp. 1711-1716.
1993.
HWC. Full-Scale Bioventing in Low-
Permeability Soil Proves Successful. The
Hazardous Waste Consultant, pp. 1.17-1.20.
The Hazardous Waste Consultant,
July/August 1993.
Miller, R.N., C.C. Vogel, and R.E. Hinchee.
A Field-Scale Investigation of Petroleum
Hydrocarbon Biodegradation in the Vadose
Zone Enhanced by Soil Venting at Tyndall
AFB, Florida. In Situ Bioreclamation. R.E.
Hinchee and R.F. Olfenbuttel, Eds.
Butterworth-Heinemann, Stoneham, MA.
1991.
van Eyk, J., Venting and Bioventing for the
In Situ Removal of Petroleum from Soil.
Hydrocarbon Bioremediation,
Hinchee, R.E., B.C. Alleman, R.E. Hoeppel,
and R.N. Miller, Eds. Lewis Publishers,
Boca Raton, pp. 243-251. 1994.
6-10
-------
7.0 EX-SITU BIODEGRADATION
7.1 Process Description
Ex-situ biodegradation is the general
term for treatment processes in which the
contaminated soil or sludge is excavated and
remediated through biological processes.
Ex-situ bioremediation technology most
often involves slurry-phase bioremediation
where an aqueous slurry is created by
combining contaminated soil or sludge with
water and then the contaminants are
biodegraded in a self-contained reactor or in
a lined lagoon. Ex-situ biodegradation also
encompasses solid-phase bioremediation,
such as landfarming, composting, and
biopiles. In these processes, the
contaminated soil is excavated, and oxygen,
nutrients, water, or microorganisms are
added to enhance the natural biodegradation
of the contaminants.
7.1.1 Slurry-Phase Bioremediation
There are two main objectives
behind using slurry-phase bioremediation:
to destroy the organic contaminants in the
soil or sludge, and, equally important, to
reduce the volume of contaminated material.
This process can be the sole treatment
technology in a complete cleanup system, or
it can be used in conjunction with other
biological, chemical and physical treatment.
Slurry biodegradation has been shown to be
effective in treating highly contaminated
soils that have fuel or other organic
contaminant concentrations ranging from
2,500 mg/kg to 250,000 mg/kg. The slurry
process has also shown potential for treating
a wide range of contaminants including
pesticides, creosote, pentachlorophenol,
PCBs, and other halogenated organics. The
effectiveness of slurry biodegradation for
certain general contaminant groups is shown
in Table 7-1.
Figure 7-1 shows a general
schematic of the slurry biodegradation
process. However, the design of slurry
processes may vary significantly among
vendors. Furthermore, each vendor's
process may be capable of treating only
certain types of contaminants. Treatability
studies to determine the biodegradability of
the contaminants and the solids/liquid
separation that occurs at the end of the
process typically are necessary before final
selection of ex-situ biodegradation as a
remedy for a given site.
As shown in Figure 7-1, waste
preparation is required before applying
slurry biodegradation. The preparation may
include excavation and handling of the
waste material as well as screening to
remove debris and large objects. Particle
size reduction, water addition, and pH and
temperature adjustment also may be required
to meet feed specifications. Table 7-2
shows the desired feed characteristics for a
typical slurry biodegradation process.
After appropriate pretreatment, the
wastes are suspended in a slurry form and
mixed in a tank to maximize the contact
between contaminants and microorganisms
capable of degrading those contaminants.
From the mix tank, the slurry is pumped
(using special slurry pumps) to the
bioreactor system. The bioreactor system
can either be an above-ground continuously
stirred tank reactor (CSTR) or a lined
lagoon. Since aerobic treatment is the most
common mode of operation for slurry
biodegradation, aeration must be provided to
the bioreactors by either floating or
submerged aerators or by compressors or
pargers. Nutrients and neutralizing agents
7-
1
-------
Table 7-1
Applicability of Slurry Biodegradation for Treatment of
Contaminants in Soil, Sediments, and Sludges
Contaminant
Applicability
ORGANIC CONTAMINANTS:
Halogenated volatiles
1
Halogenated semivolatiles
2
Nonhalogenated volatiles
1
Nonhalogenated semivolatiles
2
PCBs
1
Pesticides
2
Dioxins/Furans
0
Organic Cyanides
1
Organic Corrosives
0
INORGANIC CONTAMINANTS:
Volatile metals
0
Nonvolatile metals
0
Asbestos
0
Radioactive materials
0
Inorganic corrosives
0
Inorganic cyanides
1
REACTIVE CONTAMINANTS:
Oxidizers
0
Reducers
0
Source: U.S. EPA, 1990.
KEY:
2 = Demonstrated Effectiveness; Successful treatability test at some scale has been
completed.
1 = Potential Effectiveness; Expert opinion is that the technology will work.
0 = No Expected Effectiveness; Expert Opinion is that the technology will not work.
7-2
-------
Process Vents to
Emission Control
Soil*
Slurry
Slurry
Water
Water
Solids
Nutrients/Additives
V7777777A
DEWATERING
BIOREACTOR
MIXING TANK
Oxygen to
Aerators
* Waste preparation may be required. This includes excavation as
well as other pre treatment to remove metals & other inorganics.
Figure 7-1. Slurry Bioremediation Process Flow Diagram
7-3
-------
Table 7-2
Desired Inlet Feed Characteristics for Slurry Biodegradation Processes
Characteristic
Desired Range
Organic Content
0.025 - 25 wt %
Solid Content
10 - 40 wt %
Water Content
60 - 90 wt %
Solids Particle Size
< 1/4 in. diameter
Feed Temperature
15-35 degC
Feed pH
oo
00
i
in
7-4
-------
also are supplied to remove any chemical
limitations for microbial activity. Other
materials, such as surfactants and
dispersants, may be used to improve the
material's handling characteristics.
In the bioreactor, microorganisms
may be added initially to seed the reaction,
or they may be added continuously to
maintain the correct concentration of
biomass. The required residence time for
the waste in the bioreactor will depend on a
number of factors including:
• The physical and chemical properties
of the soil or sludge matrix;
• The physical and chemical properties
of the contaminant, including its
concentration in the waste; and
• The biodegradability of the
contaminants.
A typical residence time may be as short as
several days (e.g., 10) or as long as 8 to 9
weeks, depending on-site conditions.
Once the biodegradation of the
contaminants is completed, the treated slurry
is sent to a separation/dewatering system. A
clarifier for gravity separation can be used to
remove the water from the soil.
Slurry bioreactors are generally
transportable units that can be brought on-
site by trailer. Typically, commercial units
require a set-up area of 0.5 to 1 acre per
million gallons of reactor volume. Water
needs at the site can be high since the waste
must be put in slurry form. Large quantities
of wastewater also may have to be stored on-
site prior to discharge to allow time for
analytical tests to verify that the discharge
standard for the site has been met.
Limited performance data on slurry
biodegradation systems are currently
available. Some of the data presented in this
report are based on information supplied by
vendors. The validity of these results has
not been evaluated.
Table 7-3 shows performance data
for a full-scale slurry biodegradation system
designed by Remediation Technologies,
which was used to treat wood preserving
sludges at a site in Sweetwater, Tennessee
(U.S. EPA, 1990). The system achieved an
overall removal efficiency of greater than
95%, but the breakdown of the removal
efficiency between biodegradation and
volatilization is not available.
Another full-scale test of a slurry
biodegradation system was conducted by
ECOVA Corporation (U.S. EPA, 1990). In
this cleanup effort, more than 750 yd3 of soil
contaminated with pesticides was treated.
Soil pesticide levels were reduced from 800
mg/kg to less than 20 mg/kg (>97.5%
efficiency) in 13 days using a 26,000-gallon
bioreactor. Residuals of the process were
treated further by land application.
Under the Superfund Innovative
Technology Evaluation (SITE) program, a
pilot-scale demonstration of slurry-phase
bioremediation was performed for creosote-
contaminated soil. During a 12-week test,
greater than 87% of the total polynuclear
aromatic hydrocarbons (PAHs) were
removed from the contaminated soil (U.S.
EPA, 1993). Other case studies evaluated in
the SITE report showed similar removal
efficiencies. The slurry bioremediation of
petroleum sludge from an impoundment
yielded >90% removal of PAHs by both
volatilization and biodegradation processes.
Another study performed at a waste disposal
services site in Texas resulted in 80%
7-5
-------
Table 7-3
Performance Results for Slurry Biodegradation Process
Treating Wood Preserving Wastes(a)
Compound
Initial
Concentration
Final
Concentration
Removal(b)
Solids
(mg/kg)
Slurry
(mg/kg)
Solids
(mg/kg)
Slurry
(mg/kg)
Solids
(%)
Slurry
(%)
Phenol
14.6
1.4
0.7
<0.1
95.2
92.8
Pentachlorophenol
687
64
12.3
0.8
98.2
92.8
Naphthalene
3,670
343
23
1.6
99.3
99.5
Phenanthrene & Anthracene
30,700
2,870
200
13.7
99.3
99.5
Fluoranthene
5,470
511
67
4.6
98.8
99.1
Carbazole
1,490
139
4.9
0.3
99.7
99.8
(a)
(b)
Treatment done using a 50,000 gallon reactor supplied by Remediation Technologies.
Includes the combined effect of volatilization and biodegradation
-------
removal of most contaminants and 100%
removal of some contaminants (U.S. EPA,
1993).
7.1.2 Solid-Phase Bioremediation
Solid-phase bioremediation involves
the excavation and preparation of
contaminated soil to enhance the
bioremediation of contaminants in the soil.
Land treatment (land farming) refers to the
placement of the soil in an above-ground
treatment system and tilling the soil at
regular intervals to improve aeration and
contact between the microorganisms and the
contaminants. Nutrients and
microorganisms may be added to the soil.
Composting involves the storage of
biodegradable waste with a bulking agent to
increase the porosity of the soil material.
Oxygen is supplied through tilling or forced
aeration. The moisture, temperature, and
nutrients may need to be amended to
successfully biodegrade the contaminants.
Soil heap (or biopile) bioremediation is
similar to composting in that the
contaminated soil is piled in large mounds.
However, for these processes air is usually
provided by pulling a vacuum through the
pile.
Table 7-4 gives a summary of the
performance data available for biopile
processes. Generally, the removal
efficiencies of biopiles are similar to that of
slurry-phase bioremediation systems. At the
McClellan AFB site, both a biopile and a
slurry phase process were tested. The
removal efficiencies were 76% and 88%,
respectively (Stefanoff and Garcia, 1995).
7.2 Identification of Air Emission
Points
As shown in Figure 7-1, there are
three primary waste streams generated in
slurry-phase bioremediation processes: the
treated solids (sludge or soil), the process
water, and air emissions. The solids are
dewatered and may be further treated if they
still contain organic contaminants. Also, if
the solids are contaminated with inorganics
or heavy metals, they can be stabilized
before disposal. Some portion of the
process water can be recycled, with the
remainder treated in an on-site treatment
system prior to discharge.
The air emissions from slurry
biodegradation processes can either be area
or point sources. For processes using open
lagoons, emissions come from the exposed
surface of the lagoon. In systems using
above-ground self-contained reactors, the
primary source of emissions usually is a
process vent. The air emissions from
composting and land treatment systems
usually are area emissions, whereas the
emissions from biopiles can be area or point
sources depending on the air delivery
system.
7.3 Typical Air Emission Species of
Concern
In ex-situ bioremediation processes,
the emissions of concern are usually VOCs.
The soils-handling steps required to deliver
the contaminated soil to the treatment unit
may also emit significant amounts of PM.
Emissions from soils handling are addressed
in Section 3 of this document.
7-7
-------
Table 7-4
Summary of Performance Data for Biopile Systems
Site
Contaminants
Initial
Contaminant
Concentration
TPH
Removal
Notes
Reference
Distribution
facility in
Tustin, CA
Gasoline
85 to 8900
ppm TPH;
average = 1296
ppm
TPH below
action levels
(50 ppm) in
100% of the
treated soil
80 days
remediation
Autry amd
Ellis, 1992
Unknown
Petroleum
1100 to 3300
mg/kg TPH;
average= 1187
mg/kg
>90%
Typical final
concentration:
48 mg/kg
Hater et al.,
1994
Refinery
Refined
products and
crude oil
NA
55%
Contamination
is very
weathered
Hayes et al.,
1995
McClellan
AFB, CA
Fuel and oil
disposal site
3900 mg/kg
TPH
76%
Final
concentration:
920 mg/kg
Stefanoff
and Garcia,
1995
Glass bottle
manufacturing
facility
Fuel oil
Up to 20,000
mg/kg TPH
90% HC
100%
gasoline
components
Off-gas
recirculated
through soil
pile
Miller 1995
7-S
-------
7.4 Summary of Air Emissions Data
Little information exists on volatile
losses from ex-situ bioremediation
processes. Table 7-5 summarizes the data
available for both slurry-phase and biopile
systems. Although these data are limited,
volatilization appears to be a small
component of the overall removal of
hydrocarbons in these processes.
In open lagoons and composting and
land treatment processes, the primary
environmental factors which influence air
emissions, in addition to the
biodegradability and volatility of the waste,
are process temperature and wind speed.
Emissions tend to increase with an increase
in surface turbulence due to wind or
mechanical agitation. Temperature affects
emissions through its influence on microbial
growth. At temperatures outside the band
for optimal microbial activity, volatilization
will increase (U.S. EPA, 1989a). Emissions
from self-contained reactors are also
determined by reactor design parameters
such as the amount of air or oxygen used to
aerate the slurry. Higher gas flow will strip
more volatiles out of solution and increase
air emissions.
7.5 Air Emissions Controls
When the air emissions from slurry
biodegradation or biopiles processes are
released through a process vent, standard
VOC air pollution control technologies can
be applied. Common alternatives for
controlling VOC vent emissions include
carbon adsorption as well as thermal and
catalytic oxidation. The vent stream will
likely contain dilute amounts of VOCs, so
auxiliary fuel must be used in either thermal
or catalytic oxidizers. For the relatively low
VOC levels and low gas flows from
bioreactors and biopiles, carbon-based VOC
emission controls are generally the best
choice for point source emissions. For
biopiles, the off-gas stream can be
recirculated to the heap to reduce VOC
emissions further through biodegradation.
When the air emissions from ex-situ
bioremediation processes are area emission
sources, applying air pollution control
technologies is more difficult. Two control
options are commonly used. The first
alternative is to use a vapor collection hood
to capture any VOC emissions and then
route those emissions to a standard control
device. A second, generally less favorable,
alternative is to use an oil film or foam on
top of the slurry to suppress evaporative
losses. Typically, the air emissions from
area sources are small and do not require
controls.
7.6 Costs for Remediation
Presently there are little cost data
available on slurry biodegradation processes
because of limited experience with this type
of remediation. The cost for slurry-phase
bioremediation is estimated at $50 to
$250/yd3 (U.S. EPA, 1993). One vendor
estimates the cost of full-scale operation to
be $85-160/yd3 of soil, depending on the
initial contaminant concentration and the
total amount of soil to be treated. The
process cost will also vary depending on the
need for additional pre- and post-treatment
of the soil and on the type of air emissions
control equipment. Labor costs for materials
handling and operation can account for one-
half of the cost of these systems (U.S. EPA,
1993).
The cost of biopiles and other solid-
phase bioremediation processes are less
known. One study found that a biopile was
7-9
-------
Table 7-5
Summary of Emissions Data for Ex-Situ Bioremediation Systems
Site
Contaminants
Emission
Rate
Total
Emissions
Biodegradation/
Volatilization
Notes
Reference
Slurry-phase bioremediation
Burlington
Northern
Superfund
site, MN
Creosote
0.014 lb/hr THC
max (day 1);
0.00015 lb/hr
THC (day 6)
NA
NA
Off-gas concentrations
peaked during day 1 and
decreased to near baseline
by day 5.
U.S. EPA,
1991
Refinery
Petroleum
sludge
NA
910 kg HC
NA
425,000 kg of soils were
treated. Emissions
reduced to background by
day 6.
U.S. EPA,
1993
Sheridan
disposal
services
site, TX
Petroleum
sludge
NA
10-20 kg/yr;
1.5 kg
dredging
30 kg storage
tank;
4 kg pond
NA
A full-scale system is
estimated to have 500 to
2,000 kg ofVOC
emissions.
U.S. EPA,
1993
(Continued)
-------
Table 7-5
(Continued)
Site
Contaminants
Emission
Rate
Total
Emissions
Biodegradation/
Volatilization
Notes
Reference
Biopile
Distribution
facility in
Tustin, CA
Gasoline
NA
NA
99%/1%
Air emissions measured
for the stockpiling/
handling, mixing, and
curing operations. Mixing
component accounted for
96% of contaminants lost.
73% of VOCs lost were
trapped in carbon units.
Autry and
Ellis, 1992
Unknown
Petroleum
0.021 lb/hrHC
once through;
0.067 lb/hr HC
after treatment
(carbon)
NA
NA
Off-gas was also recycled
back to the biopiles to
further reduce emissions.
Hater et
al„ 1994
Refinery
Petroleum
16 ppb BTEX
startup;
5 ppb BTEX
(day 8);
<1 ppb BTEX
(day 35)
NA
>99%/
-------
more cost-effective than a slurry-phase
system because the biopile was more robust
with respect to varying soil characteristics
and because of the difficulties in dewatering
slurries (Stefanoff and Garcia, 1995).
The materials handling component is
consistent across all types of ex-situ
bioremediation processes, so most of the
cost differences would occur in the
treatment and post-treatment portions of
these processes.
7.7 Costs for Emissions Controls
Equations for predicting the costs of
emission controls based on system design
parameters are available (PRE, 1989).
Section 5 of this document provides typical
costs for various types and sizes of treatment
systems which could be applied to an ex-situ
biodegradation process. As mentioned in
Section 5, the cost estimates are drawn from
a number of vendors and, therefore, a range
is shown in most cases. The cost data are
intended to show the general level of costs
likely to be incurred.
7.8 Equations and Models for
Estimating Air Emissions
Although no models have been
explicitly developed for estimating
emissions from ex-situ bioprocesses used to
treat contaminated soil, there are currently,
several public-domain PC models available
for estimating air emissions from a variety
of other biotreatment options, principally
surface impoundments. The two most
commonly used models are CHEMDAT-7
(U.S. EPA, 1989b) and the Surface
Impoundment Modeling System (SIMS).
Both CHEMDAT-7 and SIMS are based on
mass transfer and biodegradation models
developed by the U.S. EPA. The mass
transfer model uses two-film resistance
theory, along with the characteristics of the
impoundment, to estimate overall mass
transfer coefficients for each pollutant. The
biodegradation model assumes Monod
kinetics to estimate a biodegradation rate.
The accuracy of estimating emissions
from ex-situ biotreatment processes, though,
is limited by the assumptions inherent in
both CHEMDAT-7 and SIMS. Both models
perform all calculations at 25 °C and rely on
physical property and kinetic data that are
not always readily available for the modeled
contaminants. Furthermore, both models
rely on a simple thermodynamic analysis and
are only valid in the Henry's Law regime.
Henry's Law is applicable to dilute solutions
and may not be applicable to bioslurries. In
addition, neither CHEMDAT-7 nor SIMS
use thermodynamic models that can predict
the presence of two liquid phases.
The validity of CHEMDAT-7 and
SIMS for modeling emissions from ex-situ
biotreatment processes will depend on the
process used and the operating parameters.
Their validity must be evaluated on a case-
by-case basis. If these models prove to be
unacceptable for a given application,
emissions can be estimated using a simple
mass balance approach. For continuous-
flow slurry systems, the following simple
correlation is applicable (Thompson, et al.,
1991):
ERj = (C/l,000)(Mr)(V/100)
where:
ERj = emission rate for contaminant i
(g/hr);
Cj = concentration of species i in
contaminated soil (mg/kg);
7-
12
-------
Mr = mass rate of soil treated (kg/hr); and
V; = percentage of contaminant i
volatilized (%).
The percentage of each contaminant that is
volatilized will vary greatly depending on
the physical properties of the contaminant
and the design of the treatment system.
Based on field studies of an aerated
impoundment treating contaminated water,
as much as 20% of each compound may be
volatilized depending on its volatility and
biodegradability (Eklund, et al. 1988).
For batch slurry biotreatment
systems, a similar expression can be used to
estimate air emissions:
ERt = (Ci/l,000)(M)(%Vi/100)/(t)
where:
ERj = emission rate for contaminant i
(g/hr);
Cj = concentration of species i in
contaminated soil (mg/kg);
M = mass of soil treated (kg);
V; = percentage of contaminant i
volatilized (%); and
t = residence time in treatment system.
Again, volatilization may be 20% or higher,
depending on the properties of the
compound of interest. This equation can
also be used to estimate the emissions from
solid-phase bioremediation processes.
Emissions will also occur when
excavating the contaminated soil, while
transporting it to the treatment unit, during
any soil preparation steps, and when feeding
the soil into the tieataie.nl process. These
fugitive emissions are noi addressed in
either the PC-based models or in the mass
balance equations discussed above. Fugitive
VOC emissions from soils handling
operations are addressed in Section 3.
7.9 Case Study
No suitable case study was found for
the ex-situ bioremediation of soils
contaminated with petroleum hydrocarbons.
7.10 References
Autry, A.R. and G.M. Ellis.
Bioremediation: An Effective Remedial
Alternative for Petroleum Hydrocarbon-
Contaminated Soil. Environmental
Progress, Vol. 11, No. 4, pp. 318-323.
November 1992.
Eklund, B., et al. Assessment of Volatile
Organic Air Emissions From an Industrial
Aerated Wastewater Treatment Tank. In:
Proceedings of the 14th Annual Hazardous
Waste Research Symposium, EPA/600/9-
88/021 (NTIS PB89-174403) pp 468-475.
July 1988.
Hater, G.R., J.S. Stark, R.E. Feltz, and A.Y.
Li. Advances in Vacuum Heap
Bioremediation at a Fixed-Site Facility:
Emissions and Bioremediation Rate.
Hydrocarbon Bioremediation. Hinchee,
R.E., B.C. Alleman, R.E. Hoeppel, and R.N.
Miller, Eds. Lewis Publishers, Boca Raton,
pp. 368-373. 1994.
Hayes, K.W., J.D. Meyers, and R.L.
Huddleston. Biopile Treatability,
Bioavailability, and Toxicity Evaluation of a
Hydrocarbon-Impacted Soil Applied
Bioremediation of Petroleum Hydrocarbons.
R.E. Hinchee, J.A. Kittel, and H.J.
7-13
-------
Reisinger, Eds. Battelle Press, Columbus.
1995.
Miller, M.E. Bioremediation on a Big Scale.
Environmental Protection, pp. 15-16. July
1995.
Stefanoff, J.G. and M.B. Garcia. Physical
Conditioning to Enhance Bioremediation of
Excavated Hydrocarbon Contaminated Soil
at McClellan Air Force Base.
Environmental Progress, Vol. 14, No. 2,
pp. 104-110. May 1995.
Thompson, P., A. Inglis, and B. Eklund.
Emission Factors for Superfund
Remediation Technologies. EPA-450/1-91-
001 (NTIS PB91-190975). March 1991.
U.S. EPA, 1989a. Background Document
for the Surface Impoundment Modeling
System (SIMS). Report No. EPA 450/4-90-
019b (NTIS PB91-156729). U.S. EPA,
Research Triangle Park, NC, September
1990.
U.S. EPA, 1989b. Hazardous Waste
Treatment, Storage, and Disposal Facilities
(TSDF) -- Air Emission Models. Report
No. EPA-450/3-87-026. (NTIS PB88-
198619). U.S. EPA, Research Triangle
Park, NC, December 1987.
U.S. EPA. Engineering Bulletin - Slurry
Biodegradation. EPA/540/2-90/016 (NTIS
PB91-228049). September 1990.
U.S. EPA. Technology Evaluation Report:
Pilot-Scale Demonstration of a Slurry-Phase
Biological Reactor for Creosote-
Contaminated Soil, Volume I. EPA/540/5-
91-009 (NTIS PB93-205532). March 1993.
U.S. EPA. Applications Analysis Report.
Pilot-Scale Demonstration of a Slurry-Phase
Biological Reactor for Creosote-
Contaminated Soil. EPA/540/A5-91/009
(NTIS PB94-124039). January 1993.
7-14
-------
8.0 INCINERATION
Thermal treatment processes include
those designed to destroy the contaminants,
such as incineration, and those designed to
effect transfer of the contaminants to the gas
phase, such as thermal desorption (see
Section 4). Incineration is seldom used to
remediate soils contaminated with fuel
products because of economic
considerations, and it is much less
commonly employed for this purpose than
thermal desorption, excavation and removal,
and other treatment technologies.
8.1 Process Description
A broad range of technologies can be
categorized as thermal destruction/
incineration. The most common
incineration technologies include liquid
injection, rotary kiln, and multiple hearth
(Lee, et al., 1986; Cheremisinoff, 1986).
However, for remediation of fuel-
contaminated soils, rotary kilns are most
often used. In general, soil remediation by
thermal destruction can be classified under
two general categories: 1) on-site treatment
using a transportable incinerator, or 2)
shipment of contaminated soils off-site to a
larger, permanent incinerator. For the
treatment of soils contaminated with
petroleum fuels, on-site incineration using
mobile or transportable units is much more
common than off-site incineration.
Although incineration is a well-established
technology, the evolution of mobile or
transportable incinerators is a more recent
development.
The literature on incineration is very
extensive. The best source of information
on air emissions from incineration is a recent
review (Dempsey and Oppelt, 1993), which
is contained in Appendix G to this report.
In broad terms, thermal destruction
of hazardous waste is an engineered process
in which controlled combustion is used to
reduce the volume of an organic waste
material and render it environmentally safe.
Thermal treatment is a flexible process
capable of being used for many waste types
including solids, gases, liquids, and sludges.
Figure 8-1 shows a generalized
process flow diagram for incineration
systems. A typical system includes the
waste feed system, primary and (in most
cases) secondary combustion chambers, and
exhaust gas conditioning system.
At the front-end of a hazardous
waste incineration system is the waste feed
process. The configuration of the waste feed
system is determined by the physical
characteristics of the waste. Contaminated
soil is introduced to the combustion chamber
by means of screw augers or belt feeders. If
liquids are to be treated as well in the
incinerator, they are usually injected into the
unit by means of an atomization nozzle(s),
which uses steam or compressed air as an
atomization fluid. Liquids with entrained
solids may require screening to prevent
clogging of the atomizer nozzle.
The largest part of the waste
destruction usually takes place in the
primary combustion chamber. As
mentioned earlier, for contaminated soils
this chamber is usually a rotating kiln.
Gases formed in the primary combustion
chamber are then routed to a secondary
combustion chamber, or afterburner, where
any unburned hydrocarbons or products of
incomplete combustion such as CO can be
fully oxidized. Temperatures typically will
be 1200-2300°F in the primary chamber and
2000-2500 °F in the after burner.
8-
1
-------
SECONDARY
AIR FAN
Clean
Flue Gas
Auxiliary Fuel
Energetic —r—
Waste
Liquids
QUENCH
SECONDARY
COMBUSTION
CHAMBER
Solids
Sludges—
ROTARY
KILN /
STACK
PRIMARY AIR FAN
Process Water
FLUE GAS
TREATMENT
SYSTEM
i r
To Ash
Disposal
Figure 8-1. Process Flow Diagram for Commercial Rotary Kiln Incinerator.
8-2
-------
After the combustion gases leave the
incinerator, they may be routed through a
variety of air pollution control devices
including gas conditioning, particulate
removal, and acid gas removal units. Gas
conditioning is accomplished with
equipment such as waste heat boilers or
quench units. Typical particulate removal
devices include venturi scrubbers, wet
electrostatic precipitators, ionizing wet
scrubbers, and fabric filters. Acid gas
removal units include packed-, spray-, or
tray-tower absorbers; ionizing wet
scrubbers; and wet electrostatic
precipitators.
The advantages of thermal treatment
include the following:
• Demonstrated effectiveness;
• Applicability to a wide range of
wastes (can be used on most
contaminant and soil types); and
• High commercial availability.
However, thermal treatment also has a
number of significant disadvantages such as:
• High cost;
• Public resistance to the construction
and permitting of incinerators; and
• The need to meet stringent treatment
requirements for process residuals.
8.2 Identification of Air Emission
Points
The air emissions associated with
full-scale thermal treatment are primarily
stack emissions of combustion gas. There
may, however, be some additional
evaporative emissions from equipment leaks
and waste handling. Full-scale, off-site
incineration units may vent all emissions
from waste handling and transfer activities
to the combustion chamber as make-up air.
The air emissions for on-site incinerators are
similar to off-site units, except that waste
handling activities have a greater likelihood
of being uncontrolled. For off-site units,
typical incinerator stacks will be 100-200 ft
high. For transportable units, stack heights
range from 40-100 ft. The fugitive
emissions sources associated with thermal
treatment will likely be ground-level.
As previously discussed, fugitive
emissions from excavation and other area
sources may be a significant fraction of the
total air emissions.
8.3 Typical Air Emission Species of
Concern
Emissions from both on-site and off-
site incinerators include: undestroyed
organics, metals, particulate matter, NOx,
CO, and acid gases. The cause of each of
these pollutants is discussed below.
Fugitive emissions associated with
excavation, storage, and handling of the feed
material must also be considered when
assessing potential air impacts from
incineration (see Section 3).
8.3.1 Unburned Hydrocarbons
In general, incinerators treating
wastes must achieve a required destruction
and removal efficiency of at least 99.99%
for RCRA wastes and 99.9999% for PCB-
or dioxin surrogate wastes. The remaining
0.01% or 0.0001% of the waste can be
assumed to pass through the system
uncombusted (Eklund, et al., 1989).
However, in addition to unburned
8-3
-------
hydrocarbons there may be some additional
reactions in the combustion process that may
produce a number of other organic
compounds, called products of incomplete
combustion (PICs). PICs may include
dioxins, formaldehyde, and benzo(a)-pyrene
and other PAHs. PIC formation is not
restricted to the combustion chamber; the
reactions which produce PICs may continue
to occur in the combustion gases as they
travel through the incineration system and
out of the exhaust system (Eklund, et al.,
1989; Treholm and Oberacker, 1985).
Studies indicate that PIC emissions
are a natural consequence of the kinetically-
limited thermal degradation of hazardous
wastes. Comparison of PIC
formation/destruction rates based on theory
and nominal incineration conditions indicate
that PIC emissions can be several orders of
magnitude higher than predicted based on
equilibrium (Dellinger, et al., 1991). This
finding suggests that temporal or spatial
excursions from these nominal conditions
are occurring, which lead to PIC formation.
Possible causes of PIC emissions include
low temperatures due to quenching,
residence-time short circuits due to nonplug
flow and/or unswept recesses, and locally
high waste/oxygen concentration ratios due
to poor microscale mixing.
Dioxins and furans are potential
PICs. Dioxins are three-ringed compounds
of the chemical family dibenzo-p-dioxins.
Furans are three-ringed structures of the
chemical family dibenzofurans that are
similar in structure to dioxins. "Dioxin" and
"furan" usually refer to the chlorinated
congeners of dibenzo-p-dioxin and
dibenzofuran. Dioxins and furans are
considered to be potent carcinogens. These
compounds may be present in incinerator
exhaust gas as a result of incomplete
combustion or the recombination of exhaust
products from the burning of mixtures
containing chlorinated compounds
(Dempsey and Oppelt, 1993). The total
dioxin/furan emissions tend to correlate with
the chlorine content of the waste feed
(Helble and Hlustick, 1994). Thus, dioxin
and furan emissions should not be a concern
for the treatment of soils containing
petroleum fuels with no chlorinated
compounds present.
8.3.2 Metals
The metals introduced to the
incinerator via the waste feed stream are not
destroyed. Depending on their boiling point,
they can either be volatilized or remain as
solids. Volatilized metals will exit the stack
as a gas or they will condense or adsorb onto
particles in the stack gas stream. Metals
associated with particulate matter (PM) will
be captured in the PM control device. Non-
volatilized metals can be fluidized and swept
up into the combustion gas or leave the
incinerator in the bottom ash.
8.3.3 Particulate Matter
The waste feed, auxiliary fuel, and
combustion air can all serve as sources for
particulate emissions from an incineration
system. Particulate emissions may result
from inorganic salts and metals that either
pass through the system as solids or vaporize
in the combustion chamber and recondense
as solid particles in the stack gas. High-
molecular-weight hydrocarbons may also
contribute to particulate emissions if
oxidation is not complete. RCRA
requirements for particulate emissions call
for a limit of 0.08 grains/dscf corrected to
7% 02. A number of potential PM control
devices can be used, including Venturis, wet
8-4
-------
electrostatic precipitation, ionizing wet
scrubbers, and fabric filters.
8.3.4 Nitrogen Oxides
Achieving high levels of destruction
of organic wastes is directly related to
combustion chamber temperature: the
higher the temperature, the greater the
destruction and removal efficiency (DRE) of
organics. Unfortunately, the fixation of
nitrogen and oxygen to form NOx also
increases with combustion temperatures.
NOx emissions caused by this mechanism
are referred to as thermal NOx. Also, if there
are bound nitrogen atoms in the waste (e.g.
amines), additional NOx emissions, called
fuel NOx, will be formed. In such cases,
two-stage combustion or emissions controls
may be needed.
8.3.5 Carbon Monoxide
Carbon monoxide emissions are
generally low (<100 ppmv) in incinerators
because of the high operating temperatures
and excess oxygen maintained in the
process.
8.3.6 Acid Gases
Hazardous waste incineration will
also produce acid gases. These include
oxides of sulfur (SOx) and halogen acids
(HC1, HF, and HBr). The sulfur, chlorine,
fluorine, and bromine contents of the waste
and fuel feed determine the emission levels
of their respective acid gases. The
concentrations of these elements range
widely amongst different wastes;
consequently, the resulting acid gas
emissions will also show wide variability.
Acid gas emissions are usually not a concern
for the incineration of soils contaminated by
petroleum fuels. Most incinerators are
equipped with some type of flue gas
treatment system to control acid gas
emissions. Control efficiencies typically
range from 85-99%. Units treating soil
contaminated with halogenated solvents
generally are required to meet RCRA
requirements governing HC1 emissions.
8.4 Summary of Air Emissions Data
The wide variety in design and
operation of incinerators makes it difficult to
generalize about air emissions. However,
extensive research has been done to
determine the range of unburned
hydrocarbon and PIC emissions that can be
expected from full-scale incinerators. Table
8-1 shows the range of PIC concentrations
found in testing of several different full-
scale incinerators. Given the volume
flowrate of the incinerator off-gas, these
concentrations can be used to estimate the
range of emissions from a particular
incinerator system. The data in Table 8-1
are not necessarily based on the incineration
of fuel- contaminated soils, and therefore,
may overestimate emissions from the
treatment of fuel-contaminated soils.
A summary of dioxin and furan
emissions from incinerators and other
thermal destruction facilities is given in
Table 8-2. Emissions of dioxins and furans
from hazardous waste incinerators generally
are below detection limits. Reasonable
worst-case emission rates of polychlorinated
dibenzo-p-dioxin (PCDD) and
tetrachlorodibenzofuran (TCDF) are 102 and
1.41 ng/m3, respectively (Dempsey and
Oppelt, 1993). Results of recent
dioxin/furan emissions tests are summarized
in Table 8-3.
8-5
-------
Table 8-1
PICs Found in Stack Effluents of Full-Scale Incinerators1
PIC
Number of Sites
Concentrations (ng/L)
Benzene
6
12 - 670
Chloroform
5
1 - 1,330
Bromodichloromethane
4
3-32
Dibromochloromethane
4
1 - 12
Bromoform
3
0.2 - 24
Naphthalene
3
5- 100
Chlorobenzene
3
1 - 10
Tetrachloroethylene
3
0.1-2.5
1,1,1 -T richloroethane
3
0.1 - 1.5
Hexachlorobenzene
2
0.5-7
Methylene chloride
2
2-27
o-Nitrophenol
2
25-50
Phenol
2
4-22
Toluene
2
2-75
Bromochloromethane
1
14
Carbon disulfide
1
32
Methylene bromide
1
18
2,4,6-Trichlorophenol
1
110
Bromomethane
1
1
Chloromethane
1
3
Pyrene
1
1
Fluoranthene
1
1
Dichlorobenzene
1
2-4
Trichlorobenzene
1
7
Methyl ethyl ketone
1
3
Diethyl phthalate
1
7
o-Chlorophenol
1
2-22
Pentachlorophenol
1
6
2,4-Dimethyl phenol
1
1-21
'Data from Trenholm, Gorman, and Jungclaus, 1984.
8-6
-------
Table 8-2
Dioxin/Furan Emissions from Thermal Destruction Facilities
(ng/dscm @7% 02)
Facility Type"
Sample
(Waste)"
2378-
TCDD
PCDD
PCDF
I-TEQs/89c
ng/dscm
g/yi"1
HWI (Commercial, Rotary Kiln, Liquid Injection)
FGe (HW)
NDf
ND
ND
ND
ND
HWI (Confidential)
FG/FA (HW)
ND
22
70
17.7
1.95
HWI (On-site Liquid Injection)
FG (HW)
ND
ND
7.3
0.93
0.02
HWI (On-Site Liquid Injection)
FG (HW)
ND
ND
ND
ND
ND
HWI (Commerical, Two Chamber, Liquid Injection
and Hearth)
FG/FA (HW)
ND
ND
1.7
0.57
0.02
HWI (On-site Kiln and Liquid Injection in Parallel)
FG (HW)
ND
ND
ND
ND
ND
HWI (Liquid Injection Incinerator Ship)
FG/FA (PCB)
ND
ND
ND
0.3
0.16
HWI (Fixed Hearth)
FG/FA (PCP)
ND
ND
ND
ND
ND
HWI (Liquid Injection)
FG/FA (PCB)
ND
0.64
9.9
1.63
0.81
HWI (Rotary Kiln/Liquid Injection)
FG/FA (PCB)
0.003
0.108
3.18
0.073
0.001
HWI (Pilot-scale Rotary Kiln)
FG/FA (PCB)
0.003
0.108
3.18
.073
0.001
Cement Kiln
FG (HW)
ND
ND
ND
ND
ND
Cement Kiln
FG (HW
ND
ND
ND
ND
ND
Lime Kiln
FG/FA (HW)
ND
ND
ND
ND
ND
Industrial Boiler/A (Watertube Stoker)
FG/FA (PCP)
ND
75.5
NR8
10.5
0.84
Industrial Boiler/D (Converted Stoker)
FG/FA (HW)
ND-0.002
0.64-0.8
0.24-5.5
0.45
0.12
Industrial Boiler/E (Packaged Watertube)
FG/FA (HW)
ND
ND
0.14
0.01
0.0026
(Continued)
-------
Table 8-2
(Continued)
Facility Type8
Sample
(Waste)b
2378-
TCDD
PCDD
PCDF
I-TEQs/89c
ng/dscm
g/yrd
Industrial Boiler/M (Tangentially Fired Watertube)
FG/FA (HW)
ND
ND
0.81
0.11
NAh
Industrial Boiler/L (Packaged Watertube)
FG/FA (HW)
ND
1.1
2.5
0.336
NA
aHWI = Hazardous Waste Incinerator.
bInformation in parentheses describes waste feed; HW = hazardous waste; PCB = polychlorinated biphenyls; PCP = pentachlorophenol
waste.
Calculated by the International Toxicity Equivalency Factor/89 (I-TEF/89) method. If isomer specific data were not available,
homologue data were considered to be composed of the most toxic isomers.
dAssumes 8160 operating hours per year.
eFG = flue gases analyzed; FA = flue gas particulate analyzed.
fND = not detected.
8NR = not reported.
hNA = Not available.
'SDA/FF = spray dryer absorber/fabric filter.
jESP = electrostatic precipitator.
Source: Dempsey and Oppelt, 1993.
-------
Table 8-3
Recent Dioxin/Furan Emissions Data
Trial
Total Dioxins
ng/dscm
Total Furans
ng/dscm
TEQ
ng/dscm
Reference
Plant A
4.34-7.12
1.48-2.86
0.06-0.133
Santoleri, 1994
Plant B
3.43
66.63
0.054
Plant Ca
0.403-0.76
1.95-4.35
4.83-5.72
Plant D
2.71-23.25
4.23-12.57
0.126-0.415
EPA Research
Facility
0.081-0.130
2.53-4.42
—
Waterland and
Venkatesh,
1994
Trial Burn
3.6-210b
0.056-2.45
Canter, 1995
Performance
Tests
0.7-39b
0.010-0.27
"Level of chlorinated organics in waste feed was 22%.
bDioxins + furans.
8-9
-------
8.5 Identification of Applicable
Control Technologies
Unlike other soil remediation
technologies, incineration does not require
additional add-on VOC controls because it
converts organics into carbon dioxide and
water. However, additional controls are
usually required to reduce emissions of acid
gases, particulate matter (PM), and metals.
The two primary alternatives for
controlling acid gas and PM emissions are
wet or dry scrubbing systems. Wet
scrubbing systems typically use a packed- or
spray-tower scrubber with a caustic
scrubbing solution to remove acid gases and
a venturi scrubber or wet electrostatic
precipitator to remove particulate matter.
Dry scrubbing systems typically use a spray
dryer absorber or dry sorbent injection to
remove acid gases from the waste gas
stream. The calcium-based alkali absorbent
is usually in the form of slaked lime. Semi-
dry systems inject the alkali as a slurry with
water which is then evaporated. Dry ESPs
or fabric filters are used to remove
particulate matter from the gas stream.
Table 8-4 shows typical ranges of emissions
and estimated removal efficiencies for acid
gas and PM control systems. The efficiency
of PM control systems depends on the
particle-size range present in the flue gas.
Pollutants of special concern from
incinerators include mercury and
dioxins/furans. Recent tests by the EPA
have demonstrated mercury control
efficiencies averaging 87% using a wet
scrubber (Carroll, Thurnau, and Fournier,
1995). Dioxins/furans typically are present
in the vapor-phase (70-80% of the total), so
particulate matter controls are of limited
effectiveness for these compounds
(Williamson, 1994). Emissions of dioxins
and furans can be controlled through the use
of activated carbon. Dioxin and furan
emissions have been reduced to <0.1 ng/m3
using an activated carbon filter (Steinhaus
and Dirks, 1994) and have been reduced
over 90% using process control and carbon
injection (Sigg, 1994).
8.6 Costs for Remediation
The costs to use thermal destruction
to remediate fuel-contaminated soil will vary
from site to site and depend on whether on-
site or off-site treatment is used. The choice
between off-site and on-site incineration is
usually determined by the volume of soil to
be treated and the proximity of full-scale
off-site hazardous waste incinerators. The
cost of using a transportable on-site
incinerator will only be justified if the
volume of contaminated soil to be
remediated is large and/or the expense of
off-site incineration is excessive because of
transportation costs or other factors.
Table 8-5 shows approximate costs
for off-site incineration. As the table shows,
the estimated cost for incinerating
contaminated soil is $540 - $1,070 per ton
including transportation costs. It should be
emphasized that this costs will vary with
type of contamination and the volume of soil
to be remediated (Cochran, et al., 1987).
Table 8-6 shows approximate costs
for on-site incineration (U.S. EPA 1990).
As indicated in the table, costs may range
from $180 to $1,580 per ton depending on
the volume of soil being remediated. Also,
as the table shows, on-site incineration is
most economical when a large volume of
waste must be treated. The cost of
remediation per ton falls significantly as the
volume increases. For large-scale on-site
8-10
-------
Table 8-4
Characteristics of Off-Gas from On-Site Incineration Systems
Table 8-4a. Typical Properties of Off-Gas from Combustion Chamber3
Parameter
Units
Value
Air flow rate
ACFM
30,000 - 50,000
Temperature of Exit Gas
°C(°F)
760-982(1,400- 1,800)
Oxygen Content
%
3
System Pressure Drop
In. H20
10-15
"Based on a limited number of designs.
Table 8-4b. Typical Emissions
EPAb Conservative
Estimated
Efficiencies
Typical Actual
Control
Efficiencies
Typical Range of
Emission Rates
Particulate Matter
99+%
99.9+%
0.005-0.02 gr/dscf
Hydrogen chloride (HC1)
—
99+
10-50 mg/Nm3
Sulfur dioxide (SO?)
—
95+
30-60 mg/Nm3
Sulfuric acid (R,S04)
—
99+
2.6 mg/Nm3
Arsenic
95
99.9+
1-5 jig/Nm3
Beryllium
99
99.9
<0.01-0.1 mg/Nm3
Cadmium
95
99.7
0.1-5 mg/Nm3
Chromium
99
99.5
2-10 mg/Nm3
Antimony
95
99.5
20-50 mg/Nm3
Barium
99
99.9
10-25 mg/Nm3
Lead
95
99.8
10-100 mg/Nm3
Mercury
85-90
40 - 90+
10-200 mg/Nm3
Silver
99
99.9+
1-10 mg/Nm3
Thallium
95
99+
10-100 mg/Nm3
PCDD/PCDF
—
90-99+
1-5 ng/Nm3
b Based on spray dryer fabric filter system or 4-field electrostatic precipitator followed by a wet
scrubber.
c Total of all congeners.
SOURCE: Donnelly, 1991.
8-11
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Table 8-5
Estimated Range of Costs for Off-Site Incineration3
Types of Waste
Cost Range, $/Mg ($/ton)
Drummed Waste
154-490(170-540)
Liquids
64 - 490 (70 - 540)
Clean Liquids with High Btu Value
18-64(20-70)
Soils and/or Highly Toxic Liquids
490-971 (540- 1,070)
"Data from Cochran, R., et al., 1987.
Table 8-6
Estimated Range of Costs for On-Site Incineration3
Site Size (Tons)
Cost Range, $/Mg ($/ton)
Very Small (<5,000)
481 - 1,433 (530- 1,580)
Small (5,000- 15,000)
354-925 (390- 1,020)
Medium (15,000 - 30,000)
236-617 (260-680)
Large (>30,000)
163 -481 (180-530)
"Data frorri Engineering Bulletin: Mobile/Transportable Incineration Treatment (U.S.
EPA/540/2-90-014) 1990. Data are for the treatment of hazardous waste.
8-12
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incineration, capital costs are on the order
of $5,000,000—$15,000,000. Operating
costs, which consist primarily of fuel and
labor, will also be substantial. Additional
costs will also be incurred for the disposal of
the incinerator ash, unless the treated soil
can be backfilled on-site.
8.7 Costs for Emissions Controls
Costs for controlling acid gas and
particulate emissions are substantial.
Depending on the volume of gas treated, the
installed cost for a wet scrubbing system on
a full-scale (i.e., fixed base) incinerator
could be $l,000,000-$3,000,000. Costs for
wet scrubber controls for a mobile system
are likely to be on the order of $200,000-
$1,000,000. Similar costs would be
expected for dry scrubbing systems.
8.8 Equations and Models for
Estimating VOC Emissions
A simple mass approach (Thompson,
et al., 1991) can be used to estimate
emissions from incineration. Separate
correlations for each pollutant of concern are
presented below.
8.8.1 Unburned Hydrocarbons
An emission rate for unburned
hydrocarbons can be generated from a mass
balance on the incinerator system:
ERi = [l-(DRE/100)](Ci)(mw)
where:
ERj = emission rate for pollutant i (g/hr);
DREj = destruction efficiency (assume
99.99% if not known);
mw = total mass flow rate of waste feed
(kg/hr); and
Cj = waste feed concentration for
pollutant i (g/kg).
Typical feed rates for soils are 5,900 kg/hr,
with a range from 900 to 24,000 kg/hr
(Eklund and Albert, 1993).
8.8.2 Products of Incomplete
Combustion
Emissions of PICs, both the amount
and the type, will vary greatly from unit to
unit depending on design and waste feed.
Data is currently unavailable to generate a
single emission factor.
8.8.3 Metals
Metals are not destroyed in the
incineration process. They leave the system
via either the bottom ash, are captured in the
air pollution control system, or exit with the
stack gas. There are currently no
correlations available for determining the
partitioning of metal emissions in
incineration systems. If stack data is
available for the incinerator in question,
metals emissions rates can be estimated
from:
ERj = (Ci)(mw)(%MEi/100)
where:
ERj = emission rate for metal i (g/hr);
Q = concentration of metal i in the feed
(g/kg);
= mass flow rate of waste (kg/hr); and
8-13
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MEj = metal emitted to air expressed as a
percentage of metal fed (%) (See
Dempsey and Oppelt, 1993 -
Appendix G, Table XV).
8.8.4 Acid Gases
The production of acid gases (HC1,
S02, and HF) is determined by the
respective chlorine, sulfur, and fluorine
contents in the waste and fuel feed streams.
A conservative approach to calculating the
air emissions of these acid gases is to
assume complete conversion of CI, S, and F
into their respective acid gas products and
apply a typical removal efficiency for the air
pollution control system. These equations
follow the form:
ERj = (Cj)(Ri/j)mw(l-%CEi/100)
where:
ERj = emission rate for acid gas i
(g/hr);
Cj = concentration of element (CI, S, or F)
in waste (g/kg);
Rj/j = stoichiometric ratio of acid gas to
(g/g);
mw = mass flow rate of waste (kg/hr); and
CE(= control efficiency of acid gas
treatment system (%).
8.8.5 Nitrogen Oxides and Carbon
Monoxide
In general, incinerator systems are
not considered significant sources of NOx
emissions. NO, is usually only a concern for
wastes with high nitrogen content. Typical
NOx emissions for an incinerator may be on
the order of 100-200 ppmv (dry basis), or
expressed on a fuel basis, 0.12-0.33 lbs NOx
per MMBtu. If a low-NOx burner is used,
the emissions may be on the order of 0.05
lbs of NOx per MMBtu.
CO emissions from incinerators are
also not considered a major problem. Most
systems are designed to be fired with excess
air (i.e., oxygen rich) to ensure complete
combustion of organic material to carbon
dioxide. Vendors typically guarantee CO
emissions less than 100 ppmv (dry basis).
Actual measured CO levels are often lower.
8.9 Case Study: On-Site Incineration
No suitable case study was found for
the incineration of soils contaminated with
petroleum fuels.
8.10 References
Canter, D.A. Assessing Risks from
Facilities Burning Hazardous Waste: EPA
Experience to Data. Presented at the 88th
Annual Meeting of the Air & Waste
Association (Paper 95-TA30A.02), San
Antonio, TX, June 18-23, 1995.
Caroll, G.J., R.C. Thurnau, and D.J.
Fournier. Mercury Emissions from a
Hazardous Waste Incinerator Equipped with
a State-of-the-Art Wet Scrubber. J. Air
Waste Manage. Assoc., Vol. 45, No. 9,
pp730-736. September 1995.
Cheremisinoff, P.N. Special Report:
Hazardous Materials and Sludge
Incineration. Pollution Engineering,
Volume 18, Number 12, pp. 32-38.
December 1986.
Cochran, R., et al. Underground Storage
Tank Corrective Action Technologies.
8-14
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EPA/625/6-87-015 (NTIS PB87-171278).
January 1987.
Dellinger, B., P. Taylor, and D. Tirey.
Minimization and Control of Hazardous
Combustion Byproducts. EPA/600/2-
90/039 (NTIS PB90-259854). August 1990.
Dempsey, C.R. and E.T. Oppelt.
Incineration of Hazardous Waste: A Critical
Review Update. J. Air Waste Mange.
Assoc., Vol. 43, No. 1, pp25-73, January
1993.
Donnelly, J. Air Pollution Controls for
Hazardous Waste Incinerators. In:
Proceedings of the 12th Annual HMCRI
Hazardous Materials Control/ Superfund
1991. Hazardous Materials Control
Research Institute, Silver Spring, Maryland.
December 1991.
Eklund, B.M., et al. Air/Superfund National
Technical Guidance Study Series, Volume
HI: Estimation of Air Emissions from
Cleanup Activities at Superfund Sites.
EPA-450/1-89-003 (NTIS PB89-180061).
January 1989.
Eklund, B. and C. Albert. Models for
Estimating Air Emission Rates from
Superfund Remedial Actions. EPA-451/R-
93-001 (NTIS PB93-186807). March 1993.
Helble, J.J. and D. Hlustick. Dioxin
Emissions and Cogener Distributions
Resulting from Hazardous Waste
Incineration. Presented at the 87th Annual
Meeting of AWMA (Paper-WA85.02),
Cincinnati, OH, June 19-24, 1994.
Lee, C.C., G.L. Huffman, and D.A.
Oberacker. Hazardous/Toxic Waste
Incineration. Journal of the Air Pollution
Control Association (JAPCA), Volume 36,
Number 8. EPA, Cincinnati, OH. August
1986.
Santoleri, J.J. Dioxin Emissions - Why 6-9s
DRE? In Proceedings: 1994 International
Incineration Conference, Houston, TX.
Sponsored by AWMA, AIChE, DOE, EPA,
etc.
Sigg, A. Control of Dioxin and Furan
Emissions From Waste Incineration
Systems. In Proceedings: 1994 International
Incineration Conference, Houston, TX.
Sponsored by AWMA, AIChE, DOE, EPA,
etc.
Steinhaus, G. and F. Dirks. Reduction of
Dioxin/Furan Emissions From an
Incineration Plant by Means of an Activated
Carbon Filter. In Proceedings: 1994
International Incineration Conference,
Houston, TX. Sponsored by AWMA,
AIChE, DOE, EPA, etc.
Thompson, P., A. Inglis, and B. Eklund.
Emission Factors for Superfund
Remediation Technologies. EPA-450/1-91-
001 (NTIS PB91-190975). May 1991.
Trenholm, A., P. Gorman, and G. Jungclaus.
Performance Evaluation of Full-Scale
Hazardous Waste Incineration Volume I.
EPA-600/2-84- 181a, (NTIS PB85-129500).
November 1984.
Trenholm, A. and D. Oberacker. Summary
of Testing Program at Hazardous Waste
Incinerators. In Proceedings of the 11th
Annual Research Symposium, Incineration
and the Treatment of Hazardous Waste.
EPA/600/9-85/028 (NTIS PB86-199403).
September 1985.
U.S. EPA. Engineering Bulletin - Mobile/
Transportable Incineration Treatment.
8-15
-------
EPA/540/2-90/014 (NTIS PB91-228023).
September 1990.
Waterland, L.R. and S. Venkatesh. Dioxin
Emission Measurements From a Rotary Kiln
Incinerator. In Proceedings: 1994
International Incineration Conference,
Houston, TX. Sponsored by AWMA,
AIChE, DOE, EPA, etc.
Williamson, P. Production and Control of
Polychlorinated Dibenzo-p-Dioxins in
Incineration Systems: A Review. Presented
at the 87th Annual Meeting of AWMA
(Paper-WA85.01), Cincinnati, OH, June 19-
24, 1994.
8-16
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9.0 SOIL WASHING, SOLVENT
EXTRACTION, AND SOIL
FLUSHING
9.1 Process Description
Three remediation technologies are
described below: soil washing, solvent
extraction, and soil flushing. These are all
primarily separation processes designed to
decrease the volume of contaminated soil,
and further treatment of the collected
contaminants typically will be required.
While these separation processes may be
more effective in treating soils contaminated
with petroleum fuels, generally they are
employed to treat soils containing metals or
heavy organic compounds.
Additional information about each of
these three remediation technologies is
contained in the engineering bulletins
contained in Appendix F.
9.1.1 Soil Washing
Soil washing is an ex situ process in
which contaminated soil is excavated and
fed through a water-based washing process.
It operates on the principle that
contaminants are associated with certain size
fractions of soil particles and that these
contaminants can be dissolved or suspended
in an aqueous solution or removed by
separating out clay and silt particles from the
bulk soil. Additives such as surfactants or
chelating agents sometimes are used to
improve the separation efficiency (treatment
using additives may be referred to as
chemical extraction). The aqueous solution
containing contaminants is treated by
conventional wastewater treatment methods
(U.S. EPA, 1990).
Most organic and inorganic
contaminants bind chemically or physically
to clay or silt soil particles, which in turn
adhere to larger sand and gravel particles
primarily by the relatively weak forces of
compaction and adhesion. Typically, 99%
of the contaminants in soil are associated
with particles of less than 60 pm in diameter
(Leggiere and Wehner, 1995). Particle-size
separation by washing enables the
contaminated clay and silt particles (and the
bound contaminants) to be concentrated.
Separating the sand and gravel from the
small contaminated soil particles
significantly reduces the volume of
contaminated soil, making further treatment
or disposal more economical. The larger
particles may be returned to the site (U. S.
EPA, 1990).
Soil washing is effective for a wide
range of organic and inorganic
contaminants, including petroleum and fuel
residues (Anderson, 1993). Removal
efficiencies range from 90-99% for volatile
organic compounds (VOCs) and from 40-
90% for semi-volatile compounds.
Compounds with low water solubilities such
as metals and pesticides sometimes require
acids or chelating agents to assist in removal
(U.S. EPA, 1990). If soil washing lowers
contaminant concentrations in the soil to
acceptable levels, the only additional
treatments to be considered are emission
controls for any water or air discharge. In
many cases, however, further soil treatment
is required and soil washing serves as a cost-
effective pre-processing step.
Soil washing potentially can be
effective for the remediation of soils with a
small amount of clay and silt particles, but
large amounts of clay and silt particles
mitigate the effectiveness of soil washing.
Soil washing is reported to be cost-effective
9-
1
-------
for soils containing up to 40% fines, but it is
most applicable to soil with 20% or less
fines (HWC, 1993). Particle size distribution
is a key parameter in determining the
feasibility of soil washing. The relative
effectiveness of soil washing for various soil
types is shown below.
Bench-scale and pilot-scale
treatability tests are recommended before
undertaking full-scale operation. Further
concerns about feasibility include the
fraction of hydrophobic contaminants that
require surfactants or organic solvents for
effective removal, how the complexity and
stability of the contamination affect
washing-fluid formulation, and the effect of
washwater additives on wastewater
treatment (U.S. EPA, 1990).
Figure 9-1 shows a process diagram
of a soil washing process. Excavation and
removal of debris and large objects precedes
the soil washing process. Sometimes water
is added to the soil to form a slurry that can
be pumped. After the soil is prepared for
soil washing, it is mixed with washwater and
extraction agents are sometimes added. At
this point, three separation processes occur:
1) water-soluble contaminants are
transferred to the washwater;
2) contaminants are suspended in the
washwater; and
3) clay and silt particles to which
contaminants are adhered are
separated from larger soil particles.
After separation from the washwater,
the soil is rinsed with clean water and may
be returned to the site. The suspended soil
particles are removed by gravity from the
washwater as sludge. Sometimes
flocculation is used to aid in sludge removal.
This sludge is more highly contaminated
than the original soil and undergoes further
treatment or secure disposal. The spent
washwater from which the sludge is
removed is treated and recycled. Residual
solids from the recycle process may require
further treatment (U.S. EPA, 1990).
Soil washing generates four waste
streams:
1) contaminated solids separated from
the washwater;
2) wastewater;
3) wastewater treatment sludge and
residual solids; and
4) air emissions.
There are a number of treatment
options that may be feasible for the
contaminated clay fines and solids:
incineration, low-temperature thermal
desorption, solidification and stabilization,
and biological or chemical treatment. It is
recommended that as much blowdown water
be recycled as possible. Blowdown water
released to local wastewater treatment plants
Particle Size
Distribution
(mm)
Relative
Effectiveness
>2
Requires pretreatment of
oversized particles
0.25-2
Effective soil washing
0.063-0.25
Limit soil washing
<0.063
Clay and silt fraction:
not amenable to soil
washing
9-2
-------
Treated
Air Emissions
Makeup Water
and Additves
Excavated or Pumped
Contaminated Soil
Recycled Water
Treated
Water
Prepared Soil
Blowdowa Water
Sludges/
Contaminated Fines
SOIL
WASHING
PROCESS
SOIL
PREPARATION
WASTEWATER
TREATMENT
EMISSION
CONTROL
Figure 9-1. Schematic Diagram of Aqueous Soil Washing Process.
9-3
-------
must meet local discharge standards. Sludge
and solids from wastewater treatment
require appropriate treatment and disposal.
Collected air emissions from the waste site
or soil-washing unit can be treated using
carbon filters (Banerjee, et al., 1993).
Advantages of the soil washing
process include:
• Applicability to a wide variety of
organic and inorganic compounds;
• High removal efficiencies for certain
soil types; and
• Minimal fire and explosion hazards.
Some disadvantages are that soil
washing:
• Is only suitable for certain soil types;
• Does not destroy contaminants; and
• May require additives that improve
removal but compromise treatment
of the waste streams.
9.1.2 Solvent Extraction
Solvent extraction differs from soil
washing in that it employs organic solvents
rather than aqueous solutions to extract
contaminants from the soil. Like soil
washing, it is a separation process that does
not destroy the contaminants. The
contaminants will have greater solubility in
the solvent than in the soil. The equilibrium
concentration gradient drives the mass
transport process such that the contaminant
transfers from the soil to the solvent. When
the soil is separated from the solvent, the
soil contaminant concentrations are
presumably lower than before contact with
the solvent. "Solvent extraction" treats
organic compounds much more effectively
than inorganic compounds and metals. It
can be used in conjunction with other
processes to reduce remediation costs (U.S.
EPA, 1994).
Sediments, sludge, and soils
contaminated with volatile organic
compounds (VOCs), petroleum wastes,
PCBs, and halogenated solvents can be
effectively treated with solvent extraction.
The removal of inorganic compounds such
as acids, bases, salts, and heavy metals is
limited, but these types of compounds
usually do not hinder the remediation
process. Metals may undergo a chemical
change to a less toxic or leachable form but
their presence in the waste streams may also
restrict disposal and recycle options (U.S.
EPA, 1994).
Figure 9-2 shows a process diagram
of the solvent extraction process. The
remediation process begins with excavating
the contaminated soil and feeding it through
a screen to remove large objects. In some
cases, solvent or water is added to the waste
in order to pump it to the extraction unit. In
the extractor, solvent is added and mixed
with the waste to promote dissolving of the
contaminants into the solvent. Laboratory
testing can determine which solvent
adequately separates the contaminants from
the soil (U.S. EPA, 1992). Generally, the
solvent has a higher vapor pressure than the
contaminants (i.e., it has a lower boiling
point) so that with an appropriate pressure or
temperature change, the solvent may be
separated from the contaminants,
compressed, and recycled to the extractor
(U.S. EPA, 1994).
9-4
-------
Treated
Air Emissions
Excavated or Pumped
Contaminated Soil
Recycled Solvent
Solvent with
Organic Contaminants
Solids
WASTE
PREPARATION
EXTRACTOR
SEPARATOR
EMISSION
CONTROL
Figure 9-2. Schematic Diagram of Solvent Extraction Process.
9-5
-------
Up to five waste streams may result
from the solvent extraction process:
1) Concentrated contaminants;
2) Solids;
3) Wastewater;
4) Oversized rejects; and
5) Treated air emissions.
The concentrated contaminants may be
analyzed and subsequently designated for
further treatment, recycle, or reuse before
disposal. While solvent extraction
presumably improves the condition of the
solids, they often still need dewatering,
treatment for residual organic compounds,
additional separation, stabilization, or other
treatment. The water from the dewatering
process, the solids, and the water from the
extractor will need to be analyzed to aid in
the choice of the most appropriate treatment
and disposal.
The solvent-extraction units are a
closed-loop design in which the solvent is
recycled and reused. Typically, solvent
extraction units are designed to produce
negligible air emissions, but solvents have
been detected in the off-gas vent system
(U.S. EPA, 1994). In addition, significant
levels of emissions (both vapor-phase and
particulate matter) may occur during waste
preparation activities such as excavation and
materials handling.
The primary advantage of solvent
extraction is the treatability of a wide variety
of media. This capability is in contrast to
soil washing, the success of which is heavily
dependent on the particle size distribution.
Some disadvantages of the process
are that solvent extraction:
• Does not destroy the contaminants;
• May not be appropriate for
contaminants with high vapor
pressures because these compounds
may be removed with the solvent in
the separation process instead of
remaining with the concentrated
contaminant stream;
• Is compromised by the presence of
detergents and emulsifiers which
compete with the solvent in
dissolving the contaminants;
• May leave residual solvent and
contaminant concentrations in the
treated waste;
• Is not effective for high molecular
weight or hydrophilic compounds;
and
• May use flammable or mildly toxic
solvents.
A variety of solvent extraction
systems have been developed to treat several
types of contamination (see Appendix F for
further information). Four systems where
full-scale or pilot-scale performance data are
available are described below.
CF Systems
Probably the most widely used
solvent extraction system is the CF Systems,
which uses liquified hydrocarbons such as
propane and butane as the solvent to treat
soil and sludge, and carbon dioxide to treat
wastewater. Water is added to the waste to
enable pumping of the material through the
extraction process. Particles greater than 1/8
inch in diameter are removed. In some
cases, oversized particles are reduced in size
for subsequent processing. The pH is
adjusted in the feed to minimize corrosion of
9-6
-------
metallic components of the treatment
system. CF Systems has used a 25-tons/day-
capacity unit to remediate refinery sludge
and achieved extraction efficiencies greater
than 99% for benzene, toluene, and xylenes
(BTX) and PAH compounds (U.S. EPA,
1994).
RCC B.E.S.T.™
RCC's B.E.S.T.™ system does not
need a pumpable waste and uses aliphatic
amines (often triethylamine) as the solvent.
Feed pH is adjusted to alkaline conditions,
and objects over one inch in size are
removed. The process operates at near
ambient temperature and pressure. Due to
its high vapor pressure and low boiling point
azeotrope formation, triethylamine is
removed with steam stripping. The full-
scale system has treated refinery waste
streams, heavy metals, PAHs, and PCBs.
Terra-KIeen
The Terra-KIeen solvent extraction
system has been used at three Superfund
sites to remediate soils containing PCBs.
Removal efficiencies of 90% or better were
achieved.
Dehydro-Tech
The Carver-Greenfield (C-G)
Process® , developed by Dehydro-Tech
Corporation, was evaluated in a pilot-scale
test to remediate 640 pounds of
contaminated drilling mud. About 90% of
the oil and essentially 100% of the total
petroleum hydrocarbons were removed from
the material.
9.1.3 Soil Flushing
Soil flushing differs from soil
washing and solvent extraction in that it is
an in-situ process in which the solvent is
injected into or sprayed over the
contaminated area, percolates through the
soil and dissolves the contaminants (it is
sometimes referred to as in-situ soil
washing). A process diagram for soil
flushing is shown in Figure 9-3. Water is
introduced and allowed to percolate down
into the soil. The applied solution may
contain fertilizer or other additives designed
to promote microbiological activity in the
subsurface. Elutriate is collected in a series
of wells and drains. If possible, the
collected liquid is recycled. Standard pump-
and-treat methods are employed to remove
and treat the ground water.
Flushing solutions may include the
following:
1) Water for water-soluble
contaminants;
2) Acidic aqueous solutions for metals
and basic organic contaminants;
3) Basic aqueous solutions for some
phenols, complexing and chelating
agents for metals such as zinc, tin,
and lead; and
4) Surfactants.
Soil flushing is generally used in
conjunction with other treatment
technologies such as activated carbon, in-
situ biodegradation, or chemical
precipitation to treat the contaminated
ground water that is collected (U.S. EPA,
1991). The method is theoretically suitable
for a wide range of contaminants. Soil
flushing is most effective for permeable
soils (KM.OxlO3 cm/sec).
The advantages of soil flushing
(Rizvi and Nayyar, 1995) are that it:
9-7
-------
Spmy
Application
~^r
PUMP
STORAGE
POND
Water
Table
Whig
Figure 9-3. Generalized Soil Flushing Process Flow Diag
9-8
-------
• Can be used to remove
contamination from areas
inaccessible to excavation or other
treatment;
• Can be used to provide oxygen and
nutrients to enhance natural
biodegradation; and
• Entails minimal disturbance to any
on-going operations at the site.
The disadvantages of the method
include:
• Soil flushing is limited to medium-
to-coarse grained soils so that the
reinjected water can readily flow
through the soil;
• The depth to groundwater must not
be too shallow (or surface flooding
may occur) nor too deep (or recovery
will be affected); and
• Solvents and contaminants may
migrate into uncontaminated areas
and also be resistant to removal due
to soil heterogeneity (Chambers,
C.D., et al., 1990).
Laboratory tests are recommended to
determine the best flushing solution for the
types of soil and contaminants present. The
flushing solution may affect the soil such
that removal is hindered and it may also alter
the soil's physical and chemical properties
after remediation. The suitability of the site
to soil flushing should be determined by a
groundwater injection test and/or a ground
water pumping test.
9.2 Identification of Air Emission
Points
In the soil-washing process, the
greatest potential for emissions of volatile
contaminants occurs in the excavation,
materials handling, feed preparation, and
extraction processes. Air emissions from
the excavation and pretreatment steps
typically are uncontrolled. Air emissions
from the batch soil-washing process may be
collected and, if so, typically are treated by
carbon adsorption or incineration (U.S.
EPA, 1990). The waste streams also have
the potential to be sources of VOC
emissions.
Solvent extraction may also produce
emissions during excavation and soil
transport and from contaminated oversize
rejects (U.S. EPA, 1994). The solvent
recovery process involves vaporization of
the solvent, so fugitive emissions are
possible from this as well as other stages of
the solvent process. The waste streams also
have the potential to be sources of VOC
emissions to the extent that any VOCs are
present.
Emissions from soil flushing may
emanate from the soil surface, solvent
storage vessels and spray system, and from
locations where the contaminant-laden
flushing solution is recovered and treated.
9.3 Typical Air Emission Species of
Concern
For petroleum-contaminated soils,
the primary air emission species of concern
are volatile and semi-volatile organic
compounds. For solvent extraction
processes, emissions of the solvent itself
also may be cause for concern. For soil
flushing, products of aerobic and anaerobic
9-9
-------
decomposition are possible, but these tend to
be predominantly carbon dioxide and
methane.
9.4 Summary of Air Emissions Data
No data were identified for the air
emissions from soil washing, solvent
extraction, and soil flushing. Information on
emissions from excavation may be found in
Section 3.
9.5 Identification of Applicable
Control Technologies
Carbon adsorption and incineration
are typical controls used to treat collected
emissions. In solvent extraction, volatile
solvents are recovered and recycled. These
control technologies are described in Section
5.5.
9.6 Capital and Operating Costs for
Remediation
Recent data on operating costs for
specific soil washing and solvent extraction
processes are summarized in Table 9-1.
Capital cost data generally are very limited,
though some data may be found in the SITE
program reports given in the references.
Cost for remediating contaminated
soil by soil washing range from $53 to $215
per ton of feed soil, according to information
from vendors of the equipment. The more
expensive processes included in the cost
range cover disposal of soil residue (U.S.
EPA, 1990).
Solvent extraction costs are most
influenced by waste volume, number of
extraction stages, operating parameters, and
lost time resulting from delays in equipment
operation. Operating parameters include
labor, maintenance, setup, decontamination,
and demobilization. The choice of solvent,
solvent/waste ratio, feed rate, extractor
residence time, and number of passes
through the extractor determine the
efficiency of the process. Estimated costs
range from $50 to $900 (U.S. EPA, 1994).
No cost data are available on soil
flushing, although costs are expected to be
moderate if inexpensive flushing solutions
are used and the network of extraction wells
is relatively simple.
9.7 Capital and Operating Costs for
Emission Controls
No cost data for emission controls
for these treatment processes were found.
General costs for controlling point source
emissions are given in Section 5.7.
9.8 Equations/Models for Estimating
Emissions
No equations or models for
predicting the air emissions from these
processes were identified.
9.9 Case Studies of Remediation and
Air Emissions
Given the lack of air emissions data,
no suitable case studies showing emissions
were found for these processes.
Remediation performance data, however,
were available and Tables 9-2 through 9-4
show selected results of treatments at several
sites. Further information may be obtained
from the relevant documents listed below.
9-10
-------
Table 9-1
Summary of Costs for Soil Washing and Solvent Extraction
Treatment
Method
Type of
Contamination
a
Process
Rate, Mg/hr
(tons/hr)
Operating Cost,
$/Mg
($/ton)b
Reference
Soil Washing
—
—
68-113 (75-125)
HWC, 1994
Soil Washing
TPH, metals,
etc.
5-91 (5-100)
24-120 (27-132)
HWC, 1994
Soil Washing
Fuel oil
53 Mg/day
(58 tons/day)
109(120)
Leggiere and
Wehner, 1995
Soil Washing
TPH, metals,
etc.
68 Mg/day
(75 tons/day)
181(200)
Leggiere and
Wehner, 1995
Soil Washing
Crude oil
454-1,814 total
Mg
(500-2,000 total
tons)
67-145 (74-160)
Baneijee, et al.,
1993
Soil Washing
Lead
2-4
150(165)
Gaire, 1995
Solvent
Extraction
TPH
1.4
200 (221)
Raptis, et al.,
1992
Solvent
Extraction
PCBs
50 tons/day
136-408 (150-
450)
Valentinetti,
1990a and 1990b
aTPH = total petroleum hydrocarbons
bDoes not include cost of excavation
9-11
-------
Table 9-2a.
Summary of Performance Data on Soil Washing
Process
Contaminants
Range of
Removal
Efficiencies
Residual
Concentrations,
ppm
Soil Cleaning of America
oil and grease
50 - 83%
250 - 600
Biotrol Soil Treatment System
Pentachlorophenol
90 - 95%
<115
other organics
85 - 95%
<1
EPA's First Generation Pilot
oil and grease
90 - 99%
<5 - 2400
MTA Remedial Resources
volatile organics
98 - 99+%
<50
semi-volatile organics
98 - 99+%
<250
most fuel products
98 - 99+%
<2200
Bodemsandering Nederland BV
aromatics
>81%
>45
crude oil
97%
2300
Harbauer of America
total organics
96%
159-201
PAH
86 - 90%
91.4-97.5
Heidemij Froth Flotation
oil
>99%
20
Klockner Umweltechnik
hydrocarbons
96.3%
82.05
chlorinated hydrocarbons
>75%
<0.01
aromatics
99.8%
<0.02
PAHs
95 4%
15.48
Source: U.S. EPA, 1990.
Table 9-2b.
Results of Remediation of Soil Containing Fuel Oil Using Soil Washing
Test Run
TPH in Untreated Soil
(mg/Kg)
TPH in Treated Soil
(mg/Kg)
Removal
Efficiency
#1
7,666
2,650
65%
#2
7,567
2,033
73%
#3
9,933
2,833
72%
Source: Banerjee, et al., 1993.
9-12
-------
Table 9-3a.
Results of Remediation of API Separator Sludge by Solvent Extraction
Compound
Initial
Concentration
(ue/g)
Final
Concentration
(pg/g)
Percent
Removal
Benzene
30.2
0.18
99%
Toluene
16.6
0.18
99%
Ethylbenzene
30.4
0.23
99%
Total Xylenes
13.2
0.98
93%
Anthracene
28.3
0.12
99%
Benzo(a)pyrene
1.9
0.33
83%
Bis-(2-ethylhexyl)phthalate
4.1
1.04
75%
Chrysene
6.3
0.69
89%
Naphthalene
42.2
0.66
98%
Phenanthrene
28.6
1.01
96%
Pyrene
7.7
1.08
86%
Source: Valentinetti, 1990b.
Table 9-3b.
Results of Remediation of Drilling Mud Waste Using Solvent Extraction
Test Run
Removal Efficiency of
Indigenous Oil
Removal Efficiency of
Indigenous TPH
#1
92.1%
100%
#2
88.3%
100%
Source: Raptis, et al., 1992.
9-13
-------
Table 9-4
Results of Remediation Using Soil Flushing
Site
Compound
Peak
Ground Water
Concentration
(H g/L)
Ending
Ground Water
Concentration
(H g/L)
Reduction
Gasoline station
Well #1'
Benzene
7
ND
100%
Toluene
76
ND
100%
Ethylbenzene
140
ND
100%
Xylenes
1,300
5
99.6%
Naphthalene
81
ND
100%
Bus garage
Well #42
Benzene
1,800
690
62%
Toluene
9,000
1,400
84%
Ethylbenzene
2,300
1,500
35%
Xylenes
10,000
5,600
44%
Naphthalene
270
369
-37%
Source: Rizvi and Nayyar, 1995.
Notes:
1. Data for gasoline station are from June 1992 to February 1995
2. Data for bus garage are from June 1993 to February 1995
9-14
-------
9.10 References
Anderson, W.C., ed. Innovative Site
Remediation Technology - Soil
Washing/Soil Flushing. American Academy
of Environmental Engineers, Ananapolis,
MD. 1993.
Banerjee, P., J. Swano, and M. Flaherty.
Biogenesis™ Soil Washing Technology -
Innovative Technology Evaluation Report.
EPA/540/R-93/510 (NTIS PB94-120045).
September 1993.
Chambers C.D., et al. Handbook of In Situ
Treatment of Hazardous Waste -
Contaminated Soils. EPA/540/2-90/002
(NTIS PB90-155607). January 1990.
Gaire, R.J. BESCORP Soil Washing
System for Lead Battery Site Treatment -
Applications Analysis Report.
EPA/540/AR-93/503 (NTIS PB95-199741).
January 1995.
HWC, 1993. Full-Scale Soil Washing
System Remediates Superfund Site. The
Hazardous Waste Consultant:
November/December 1993.
HWC, 1994. On-Site Soil/Sediment
Washing is Applied to Both Land and
Marine Sites. The Hazardous Waste
Consultant: September/October 1994.
Leggiere, T.C. and T. Wehner. Soil
Washing - Theory and Implementation
Application of Soil Washing at
Contaminated Sites. Presented at the 88th
Annual Meeting & Exhibition of the Air &
Waste Management Association (Paper 95-
WA90.01), San Antonio, TX, June 18-23,
1995.
Raptis, T., et al. The Carver-Greenfield
Process® Dehyro-Tech Corporation -
Applications Analysis Report.
EPA/540/AR-92/002 (NTIS PB93-101152).
September 1992.
Rizvi, S.S.H. and H.S. Nayyar. Remediation
of Petroleum Contaminated Soil Using In-
Situ Soil Washing: Case Studies and
Strategies. Presented at the 88th Annual
Meeting & Exhibition of the Air & Waste
Management Association (Paper 95-
WA90.05), San Antonio, TX, June 18-23,
1995.
U.S. EPA, 1990. Engineering Bulletin - Soil
Washing Treatment. EPA/540/2-90/017
(NTIS PB91-228056). September 1990.
U.S. EPA, 1991. Engineering Bulletin - In
Situ Soil Flushing. EPA/540/2-91/021
(NTIS PB92-180025). October 1991.
U.S. EPA, 1992. Guide for Conducting
Treatability Studies under CERCLA:
Solvent Extraction. EPA/540/R-92/016b
(NTIS PB92-239599). August 1992.
U.S. EPA, 1994. Engineering Bulletin-
Solvent Extraction. EPA/540/S-94/503
(NTIS PB94-190477). April 1994.
Valentinetti, R. Technology Evaluation
Report: CF Systems Organics Extraction
System - Volume 2, New Bedford,
Massachusetts. Report No. EPA-540/5-
90/002 (NTIS PB90-186503). January
1990a.
Valentinetti, R. Applications Analysis
Report: CF Systems Organics Extraction
System - Volume 1, New Bedford,
Massachusetts. Report No. EPA-540/5-
90/002 (NTIS PB90-186495). August
1990b.
9-15
-------
10.0 UNCERTAINTY AND
SENSITIVITY ANALYSIS
10.1 Introduction
An analysis of the uncertainty
associated with the EEMs presented in
Chapters 3 through 8 was performed and the
results are presented in this chapter. Every
method that is used to estimate air pollutant
emissions, whether it is an emission factor
or a more complex emissions model, carries
a certain level of uncertainty. There are two
sources of uncertainty associated with
EEMs:
• Uncertainty of the EEM itself: this
refers to the ability of the method to
accurately predict real-world
emissions. In other words, if each
value for all of the parameters in the
method are precisely known, how
accurate is the EEM (in terms of
precision and bias) in predicting
actual emissions?
• Uncertainty in the values of the EEM
variables: in many cases, the values
for the EEM parameters will not be
precisely known and must be
estimated. In addition, where the
parameter may have a measured
value, there is variability associated
with this value. Often a sensitivity
analysis is performed in order to gain
an understanding of which variables
have the largest impact on the
predicted result (i.e., which
contribute the most to the variability
in the prediction).
Ideally, an analysis of uncertainty
would address both sources and present the
results as a combined result. However, in
order to analyze method uncertainty (as
described under the first bullet), field data
are needed for comparison against the EEM-
predicted results. These data are very rarely
available and were not available for use in
this uncertainty analysis. Limited EEM
predictions compared against field data have
shown that the EEMs can be expected to
yield conservatively-biased (i.e., high)
predictions within a factor of 3 to 10 (see
Table A-7 in Appendix D).
A description of the approach and
results obtained for the uncertainty analysis
of EEM variables is given in the sections
that follow. A sensitivity analysis is also
performed for each EEM in order to
determine which variable(s) contribute the
most to the variability in the predicted
results.
10.2 Approach
Monte Carlo simulations of each
EEM were performed using a commercially-
available software (Crystal Ball Version
4.0). Monte Carlo simulation is an efficient
technique for analyzing real-world problems
that have a large number of possible
outcomes based on the potential values of
associated variables. In a Monte Carlo
simulation, random numbers for each
variable are generated that conform to the
real-world potential values. A large number
of EEM trials are run (e.g., 10,000) using
these randomly-generated values. Based on
the results of this large number of trial
simulations, a distribution and summary
statistics are derived. These statistics can be
used to gain an understanding of the
variability associated with the EEM
projections (e.g., mean, coefficient of
variation, 95% confidence limits).
In order to perform the
uncertainty/sensitivity analysis, assumptions
10-
1
-------
had to be derived for an example
application. The same set of assumptions
(e.g., soil properties and benzene
concentration level) were used during the
analysis of each EEM. It was assumed that
there was a need to develop an emission rate
for benzene from soil remediation activities.
The soil had been contaminated with
gasoline and moderate levels of benzene
were present (10 ppm). No other physical
data were available for the soil (e.g.,
moisture content, bulk density, temperature)
which is common during these analyses.
However, it was assumed that the
remediation would occur during the summer
months (ambient temperature of 25 degrees
C) and that the soil was a fine-textured clay.
For each EEM, a spreadsheet was
developed that contained the equation(s) for
estimating emissions and the associated
variables. For each variable, assumptions
were assigned that described the range and
distribution of potential values (e.g., normal,
uniform, triangular). These assumptions are
summarized in Table 10-1. Most of the
information used to develop the variable
distributions were taken directly from the
text of this report. For example, the
percentage of benzene that is anticipated to
volatilize during thermal desorption was
assumed to be 99.50% based on information
given in Chapter 3. Further, based on the
same information and engineering
judgement, it was assumed that the
minimum percentage of benzene volatilized
would be 99.00% and that the maximum
would be 99.99%. Using the minimum,
maximum, and likeliest values, a triangular
distribution was developed for input to the
Monte Carlo simulations.
Using the assumptions listed in
Table 10-1 and the equations given in
Chapters 3 through 8, Monte Carlo
simulations were run for each EEM to
develop distributions of the potential
emission rates. Along with the distributions
of potential emission rates, charts depicting
the sensitivity of the EEM to the associated
variables were developed.
10.3 Results
A summary of the
uncertainty/sensitivity analysis is shown in
Table 10-2. Monte Carlo modeling results
are given in Appendix G. For each EEM, a
point estimate of the emission rate is given.
This value was derived by using the
appropriate equation given in Chapters 3
through 8 and the mean or most likely values
for the associated variables given in Table
10-1.
The mean of each Monte Carlo
distribution is shown in Table 10-2 along
with 95% confidence limits for the potential
emission rate. In the final column, the
variables which had the largest influence on
the EEM predictions are listed along with
the contribution to variance associated with
each.
For excavation/removal, the total
emission rate was influenced most by the
soil bulk density variable. This variable is
used to determine the air-filled porosity
parameter (Ea) which, in turn, is used during
the estimation of both the emission rate from
the pore space and the emission rate from
diffusion. These results signify the
importance of gathering and using site-
specific data whenever possible. Based on
the 95% confidence limits, the total
emission rate could vary by a factor of more
than 5.
For thermal desorption, the emission
rate was shown to vary by a factor of about
10-2
-------
8. The variability was driven almost
exclusively by the uncertainty in the
estimate of control efficiency.
For soil vapor extraction, the vapor
extraction rate was only independent
variable, and therefore was the only variable
that contributed to quantifiable uncertainty
in the emission rate estimate. The 95%
confidence limits show that the range in
potential emissions could span a factor of
about 2.
The analysis for in-situ
biodegradation revealed that again the bulk
density of the soil contributed the most to
variability in the emission rate. However,
the estimate of the number of pore volumes
extracted per day was also a high
contributor. Potential emissions varied by a
factor of nearly 8.
For ex-situ biodegradation, the EEM
was shown to be most sensitive to the
estimate given for V (the fraction of benzene
volatilized). This situation is likely to
persist, as there is scant data of this type
available. Potential surrogate data for use
here include from studies of VOC
volatilization from sewage treatment plants
and sewer systems.
As with thermal desorption, the
variability in predicted emissions for
incineration is driven by estimates of control
efficiency. Specific vendor estimates or
guarantees would likely improve upon the
assumptions used here. Often a minimum
control efficiency can be guaranteed (e.g.,
>99.90%) that would be high enough to
tighten the assumed distribution. This
would result in lower variability of the
projected emissions.
Details of the Monte Carlo
simulations are given in Appendix G. Each
EEM begins with a print-out of the
spreadsheet used to build the emission
projections (forecasts). Charts that display
the sensitivity of the EEM to each variable
are shown. Figures are also shown that
depict the distributions of each forecast (e.g.,
emission rates) and assumptions.
10.4 References
Brady, N.C., The Nature and Properties of
Soils, MacMillan Publishing Co., New
York, NY, 1984.
Fleischer, E.J., et al., "Evaluating the
Subsurface Fate of Organic Chemicals of
Concern Using the SESOIL Environmental
Fate Model", Proceedings of the Third
Eastern Regional Groundwater Conference,
National Well Water Association,
Springfield, MA, July 29-31, 1986.
Pechan, personal communication from staff
of Weston, Inc., 1996.
10-3
-------
Table 10-1
Scenario Development for the Uncertainty/Sensitivity Analysis
Variable
Value
Comments
Benzene concentration (C)
10 ppm
Based on hypothetical representative sampling of the site.
The distribution is assumed to be normal with a mean of 10
and a standard deviation of 1.0.
Soil moisture content (Mfrac)
15%
Mid-point of the typical range for clay soils [clay soil is
characteristic of the site (Brady, 1984)]. Distribution is
uniform with 12% as the minimum and 18% as the
maximum.
Ambient temperature (Ta)
298K
Assumed that the remediation takes place during the
summer months.
Soil temperature (Ts)
293K
The soil temperature will be about 5 degrees cooler than
the assumed ambient temperature of 298K. Based on data
from Brady (1984).
Soil bulk density (beta)
1.5 g/cm3
Soil assumed to be moderately compacted and finely-
textured (Brady, 1984). The distribution is uniform with a
minimum of 1.0 and a maximum of 2.0.
Particle density (p)
2.65 g/cm3
Assumed from information given in Chapter 3. Uniform
distribution around a 2.65 g/cm3 mean and a +/- 5% error.
Volatilized fraction during thermal
Resorption (V)
99.50%
From information presented in Chapter 2. Triangular
distribution with a minimum of 99.00%, a maximum of
99.99%, and a likeliest value of 99.50%.
Soil feed rate into the thermal desorber
IF)
27,200 kg/hr
Assumed from information given in Chapter 2. Uniform
distribution around a mean of 27,200 kg/hr and a +/- 10%
error.
Vapor extraction rate during soil vapor
extraction (Q)
85 m3/min
Assumed from information given in Chapter 5. Uniform
distribution around a 85 m3/min mean and a +/- 30% error.
Pore volumes per day for in-situ
Dioremediation (pv)
1.0
Based on information given in Chapter 5. Distribution is
triangular with a minimum of 0.3, a maximum of 2.0, and
the likeliest value of 1.0.
Fraction volatilized during continuous
2x-situ bioremediation (V)
0.60 vol/vol
Based on limited data soil/water partitioning (Fleischer, et
al., 1986). End-points of the uniform distribution derived
from an error estimate of +/- 30%.
Mass feed rate of soil into the
:ontinuous ex-situ bioreactor (Mr)
600 kg/hr
Assumed based on information provided in Chapter 6.
Distribution is uniform with 600 kg/hr the mid-point and
the end points determined from a +/- 10% error estimate.
Mass feed rate of soil into the thermal
ncinerator (Mw)
4,500 kg/hr
Assumed based on information from Pechan (1996).
Distribution is uniform with 4,500 kg/hr as the mid-point
and end-points determined from a +/- error assumption of
10%.
Control efficiency (CE) during thermal
iesorption and thermal oxidation
processes
99.50%
Based on engineering judgement. Distribution is assumed
to be triangular with a minimum of 99.00%, a maximum of
99.99%, and a most likeliest value of 99.50%.
Contaminated area
2500 m2
Assumed.
Contaminated death
5 m
Assumed.
10-4
-------
Table 10-2.
Uncertainty/Senstivity Analysis Results
EEM No.
Remediation Process
Predicted Benzene Emissions, g/sec (g/hr)
EEM Parameters Contributing the Most
to Emissions Variability
(% Contribution to Variance)
Point Estimate
of Emissions
Monte Carlo Predictions
Mean
95% Confidence
Limits
1
Excavation/Removal:
Emissions from Pore Space
Emissions from Diffusion
Total Emissions
0.59
3.26
3.85
0.98
3.19
4.17
0.16-2.71
1.10-5.23
1.41-7.38
ER pore space:
excavation rate (Q) = 50%; bulk density
(beta) = 32%; exchange constant (ExC) =
17%.
ER diffusion;
bulk density (beta) = 90%
ER total:
bulk density (beta) = 85%
excavation rate (Q) = 6%
2
Thermal Desorption
1.35
1.36
0.32 - 2.54
control efficiency (CE) = 93%
3
Soil Vapor Extraction
0.47
0.47
0.33 - 0.60
vapor extraction rate (Q) = 100% (this is
the only independent variable)
4
In-Situ Biodegradation
0.017
0.018
0.005 - 0.039
bulk density (beta) = 58%; pore volumes
extracted per day (pv) = 40%
5
Ex-Situ Biodegradation
3.72
3.60
1.80-5.82
fraction volatilized (V) = 89%; benzene
concentration (C) = 6%
6
Incineration
0.23
0.23
0.052 - 0.42
control efficiency (CE) = 93%
-------
APPENDIX A
PROPERTIES AND COMPOSITION OF VARIOUS FUEL TYPES
Brief descriptions are given below for liquefied petroleum gases, gasoline, diesel fuel Jet
fuel, oil, and asphalt and bitumen.
Liquefied Petroleum Gases (LPG) comprise ethane ethylene, propane, propylene,
normal butane, butylene, and isobutane and are typically produced at refineries or natural
processing plants. Normal butane added to gasoline helps to regulate its vapor pressure and
isobutane serves as an alkylation feedstock and is sold as LPG.
Gasoline is a petroleum derivative with over 100 components boiling from 90°F to
420°F. Additives that improve gasoline performance can change its physical properties
significantly. Adding normal butane adjusts the Reid vapor pressure (RVP) so that it varies
between about 9.5 psi in the winter and 23.5 psi in the summer1. Butane accounts for about 75%
of the vapor pressure of gasoline with pentanes making up much of the remainder. Detergent
additives acting as surfactants reduce the surface tension which in turn influences subsurface
migration. Hydrophilic additives such as methyl-tert-butyl ether (MTBE), methanol, and ethanol
boost octane numbers and considerably increase the solubility of gasoline in water2.
Diesel Fuel is used by trucks, railroads, stationary engines, and some automobiles. The
three types of diesel most commonly used are No.l and No.2 for automobiles and trucks; and
No.4, which is heavier and used by large, slow-speed vehicles3. This middle distillate tends to be
less volatile, less mobile in soil, and less water soluble than gasolines4.
'Handbook of Energy Technology and Economics, Robert A. Meyer, ed. John Wiley and
Sons, 1983, NY.
2David K Kreamer and Klaus J. Stetzenback, "Development of a Standard, Pure-
Compound Base Gasoline Mixture for Use as a Reference in Field and Laboratory Experiments,
" Spring 1990, Ground Water Monitoring Review, p. 136.
3Handout of Energy Technology and Economics, Robert A. Meyer, ed. John Wiley and
Sons, 1983, NY, pp.217-18.
4"A guide to the Assessment and Remediation of Underground Petroleum Releases," API
Publication 1628, 2nd Ed., August 1989, p. 9.
A-l
-------
Jet Fuels used by commercial and military aircraft resemble kerosene and have a similar
boiling range to light diesel fuels and heating oils. Jet fuels contain no more than 20% aromatic
compounds5. This middle distillate tends to be less volatile, less mobile in soil, and less water
soluble than gasolines6.
Oil - Heating oils No. 1 and No.2 are used to heat homes and businesses. The heavier
oils, Nos. 4, 5, and 6, are used by shipping and industry and have higher viscosities and pour
points7.
Asphalt and Bitumen are solid phase components of crude oil that remain virtually
immobile in soil because shallow subsurface temperatures rarely rise above their melting points8.
'Handbook of Energy Technology and Economics, Robert A. Meyer, ed. John Wiley and
Sons, 1983, NY, pp. 217-18.
6"A guide to the Assessment and Remediation of Underground Petroleum Releases," API
Publication 1628, 2nd Ed., August 1989, p. 9.
7Handbook of Energy Technology and Economics, Robert A. Meyer, ed. John Wiley and
Sons, 1983, NY, pp. 217-18.
8"A guide to the Assessment and Remediation of Underground Petroleum Releases," API
Publication 1628, 2nd Ed., August 1989, p. 9.
A-2
-------
.Tet Fuels used by commercial and military aircraft resemble kerosene and have a similar
boiling range to light diesel fuels and heating oils. Jet fuels contain no more than 20% aromatic
compounds5. This middle distillate tends to be less volatile, less mobile in soil, and less water
soluble than gasolines6.
Oil - Heating oils No. 1 and No.2 are used to heat homes and businesses. The heavier
oils, Nos. 4, 5, and 6, are used by shipping and industry and have higher viscosities and pour
points7.
Asphalt and Bitumen are solid phase components of crude oil that remain virtually
immobile in soil because shallow subsurface temperatures rarely rise above their melting points8.
'Handbook of Energy Technology and Economics, Robert A. Meyer, ed. John Wiley and
Sons, 1983, NY, pp. 217-18.
6"A guide to the Assessment and Remediation of Underground Petroleum Releases," API
Publication 1628, 2nd Ed., August 1989, p. 9.
7Handbook of Energy Technology and Economics, Robert A. Meyer, ed. John Wiley and
Sons, 1983, NY, pp. 217-18.
8"A guide to the Assessment and Remediation of Underground Petroleum Releases," API
Publication 1628, 2nd Ed., August 1989, p. 9.
A-3
-------
APPENDIX B
STATE CLEANUP REQUIREMENTS
B-l
-------
State cleanup standards
for hydrocarbon contaminated soil and groundwater
Summary of Alabama Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
602. 624
«
any amount
5 ppb
5 ppb
Ethylbenzene
•
any amount
700 ppb
700 ppb
Toluene
•
any amount
1000 ppb
1000 ppb
Xylenes
*
any amount
10.000 ppb
10.000 ppb
Diesel
PAH
EPA Method 610.625
•
any amount
Site
Site Specific**
Specific**
Waste Oil
BTEX
EPA Method 602. 625
•
any amount
Same as
Same as Gasoline
Gasoline
PAH
EPA Method 610. 625
•
any amount
Same as
Same as Diesel
Diesel
^emedW'on El«Pment
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More Information!
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p '"'iiUr ' ":;l
1 ~V-'-
Fliteway Air Products, Inc.
7233 North 51 it Boulevard • Mltwiukae. Wlicontln 83223
(414) 357-8780 « 1 -800-236-3380 • FAX (414) 3S7-859B
Fliteway Is the Mghtway!
Contact: Dorothy Malaiex, Alabama Department
of Environmental Management.
205-270-5613
* Dictated by Method,
•• Health Advisory Limits.
Note: Risk Assessment may be used to allow
for a higher level.
These states do not have charts
and ask that interested parties
call for information:
Colorado: 303-692-3330
Connecticut: 203-566-5599
Rhode Island: 401-277-3872
Acknowledgements
The Association for the
Environmental Health of Soils
(AEHS), of Amherst, Mass.,
funded production of this project.
AEHS is committed to facilitating
the transfer of technical and
educational information related to
the health of soils. AEHS conducts
national and international
conferences, workshops and
seminars. For more information,
call 413-549-5170.
Project manager war Tamlyn
Oliver of AEHS.
Thanks to program staff in the
50 states who provided current
information under deadline
pressure-
Thanks to Betty Niedzwiecki.
Mary Terry and Melissa Guerzon
for proofreading and review.
Thanks to John Marencik, of
EnviroQuest Technologies, Inc.,
Kansas City, Mo., for
conceptualizing data collection
parameters.
14 December 1994 Soils
Write In 225
B-2
-------
mtuMI
Summary of Alabama Cleanup Standards for Hydrocarbon Contaminated SoiJ
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
TPH
EPA Method 9071
*
any amount
100 ppm
100 ppm**
TPH
Standard Method 5520
*
any amount
100 ppm
100 ppm**
TPH
EPA 418.1
*
any amount
100 ppm
100 ppm**
Diesel
TPH
EPA Method 9071
*
any amount
100 ppm
100 ppm**
TPH
Standard Method 5520
*
any amount
100 ppm
100 ppm**
TPH
EPA 418.1
«
any amount
100 ppm
100 ppm**
Waste Oil
TPH
EPA Method 9071
*
any amount
100 ppm
100 ppm**
TPH
EPA 418.1
*
any amount
100 ppm
100 ppm**
¦ Dictated by Method Contact: Dorothy Malaier. Alabama Department of
•• Risk Assessment may be used to allow for a higher level. Environmental Management 203-270-3613
Summary of Alaska Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
GRPH (C6-C10)
EPA Method 8015M
1 mg/1
any amount
sheen
sheen
Benzene
EPA Method 602
.005 mg/1
any amount
.005 mg/1
005 mg/1
Toluene
EPA Method 602
.005 mg/1
any amount
1 mg/1
I mg/1
Ethylbenzene
EPA Method 602
.005 mg/1
any amount
0.7 mg/1
0.7 mg/1
Xylene
EPA Method 602
.005 mg/1
any amount
10 mg/1
10 mg/1
Diesel
DRPH (C10-C28)
EPA Method 8100M
1 mg/1
any amount
sheen
sheen
Waste Oil
All of the Above and
TPH (>C29)
EPA Method 418.1
1 mg/1
any amount
sheen
sheen
Contact: Cynthia Pring-Ham. Alaska Department of
Environmental Conservation 907-465-5200
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December 1994 Soils 15
B-3
-------
Summary of Alaska Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Ciasoline
Gasoline Range Petro.
Hydrociftwns C«-C 3
EPA Method 80I5M
1 mg/kg
any amount
Site Specific
50l000ppm
Site Specific/30- lOOOppm
BTEX
EPA Method 8020
0.05 mg/kg
any amount
Site Specific
10- lOOppm
Siic Spcc.flc/10-lOOppm
Benzene
EPA Method 8020
0.05 mg/kg
any amount
Site Specific
l-.5ppm
Site Specific/0. l-.5ppm
Diesel
Diesel Range Petro.
Hydrocarbons C io-C;i
EPA Method 8100M
10 mg/kg
any amount
Site Specific
I00-2000pj)in
Sue Spccitic/100-2000ppm
Waste Oil
All of the Above and
TPH(>C;,)
EPA Method 418.1
25 mg/kg
any amount
2000 ppm
2000 ppm
Contact: Cynthia Pring-Ham. Alaska Department of
Environmental Conservation 907-465-5200
Summary of Arizona Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline. Diesel.
TPH
EPA Method 418.1
lab dep.
any amount
X>Non-Det.
Not Applicable
Waste Oil
Benzene
EPA Method 502.2* ••
lab dep.
any amount
X>Non-Det.
X< 5ppb
Toluene
EPA Method 502.2*"
lab dep.
any amount
X>Non-Det.
X< lOOOppb
Ethylbenzene
EPA Method 502.2"*
lab dep.
any amount
X>Non-Det.
X< 700ppb
Xylenes
EPA Method 502.2"-
lab dep.
any amount
X>Non-DeL
X< 10,000ppb
VOCs
EPA Method 502.2"«
lab dep.
any amount
X>Non-Det.
* •••
' •• Ail target compound) in addition to BTEX anaJy/ed by these test methods must oe reported. The first round of Contact: Scar Mckenzie. Arizona Department of
waer samples from a newly completed well must be analyzed using EPA Method 502.2. Subsequent samples may be Environmental Ouality 602-628-6708
analyzed using 502.1 or 503.1 upon ADEQ approval
Refer to most recent ADHS. HBGLs ana/or MCL for information on specific compounds not gives under AWQS
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EPA wants advice to
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The EPA is holding five
national roundtable discussions
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environmental permitting
process by gathering advice
from individuals on how to
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16 December 1994 Soils
B-4
-------
Summary of Arizona Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
ADHS Method BLS-181
lab
dependent
any amount
X>N D.
XN.D.
X<0.13ppm but risk
assessment option exists
Toluene
EPA Method 8020
lab
dependent
any amount
X>N.D.
X<200ppm but risk
assessment option exists
Ethylbenzene
EPA Method 8020
lab
dependent
any amount
X>N.D.
X<68ppm but risk
assessment option exists
Xylenes
EPA Method 8020
lab
dependent
any amount
X>N.D.
X<44ppm but risk
assessment option exists
Kerosene
Identical with all the above gasoline categories.
Diesel
TPH only
ADHS Method BLS-181
lab
dependent
any amount
X>N.D.
X<100ppm but risk
assessment option exists
Jet Fuel
Identical to all the above Gasoline categories.
Heavy Oil
Identical to Diesel above.
Solvents
TPH
ADHS Method BLS-181
lab
dependent
any amount
X>N.D.
X<100ppm but risk
assessment option exists
VOCs
EPA Method 8010***
lab dep.
any amount
X>N.D.
BTEX: Identical in all respects to BTEX for gasoline above.
Waste Oil
TPH
ADHS Method BLS-181
lab
dependent
any amount
X>N.D.
X<100ppm but risk
assessment option exists
BTEX Not Required
VOCs
EPA Method 8010
lab dep.
any amount
X>N.D.
• •••
BTEX: Benzene. Toluene. Ethylbeniene. Xylene: TPH: Total Petroleum Hydrocarbon. N.D.: Non Detect ADHS: Contact: Sean Mckenzie. Arizona Department of
Arizona Department of Health Services. VOCs: Volatile Organic Compounds. N. A. Not Applicable (i.e. standards have Environmental Quality 602-62S-6708
not been established) MCL: Maximum Contaminant Level. *** All target compounds in addition to BTEX analyzed by
these test methods must be reported. The first round of water samples from a newly completed well must be analyzed
with EPA Test Method S02.2. Subsequent samples may be analyzed using 502.1 or 503.1 upon ADEQ approval.
Refer to most recent ADHS. HBGLs and/or MCL for information on specific compounds not given under AWQS
Summary of Arkansas Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Benzene/ Total
EPA Method 8020
Ippb
Not Used
5 pp6 Benzene
Site Specific*
BTEX
lOOppb BTEX
TPH
EPA Method 418.1
lOppm
Not Used
15 ppm
Site Specific*
TPH
Modified 8015
lOppm
Not Used
15 ppm
Site Specific*
Diesel
TPH
EPA Method 418.1
lOppm
Not Used
15 ppm
Site Specific*
TPH
Modified 8013
lOppm
Not Used
15 ppm
Site Specific*
Waste Oil
TPH
EPA Method418.1
lOppm
Not Used
15 ppm
Site Specific*
TPH
Modified 80 IS
lOppm
Not Used
15 ppm
Site Specific*
May also require VOC scan (8240) under certain circumstances
* Based on Risk Assessment
Summary of Arkansas Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
EPA Method 418.1
lOppm
Not Used
100 ppm
Site Specific/lOO-lOOOppm*
TPH
Modified 8015
lOppm
Not Used
100 ppm
Site Specific/100- lOOOppm*
BTEX
EPA Method 8020
Ippm
Not Used
40 ppm
Site Specific/0-400ppm*
Diesel
TPH
EPA Method 418.1
lOppm
Not Used
100 ppm
Site Specific/100-lOOOppm*
TPH
Modified 8015
lOppm
Not Used
100 ppm
Site Specific/100-lOOOppm*
Waste Oil
TPH
EPA Method 418.1
lOppm
Not Used
100 ppm
Site Specific/lOO-lOOOppm*
TPH
EPA Method 8015
lOppm
Not Used
100 ppm
Site Specific/lOO-lOOOppm*
Modified
May also require VOC scan (8240) and TCLP for metals under some circumstances
• Based on Risk Assessment Contact: James Atchley, Arkansas Department of
Pollution Control & Ecology 501-562-6533
18 December 1994 Soils
B-5
-------
Summary of California Cleanup Goals for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA 602
0.7ppb
DHS Acuon Level
Toluene
EPA 602
"State Action l,evel
lOOppb DHS
Xylene
EPA 602
MCLs (1750ppb)
Ethylbenzene
EPA 602
MCLs (680ppb)
Diesel
HVOs
EPA 601
Same as above
Waste Oil
Same as above
• Health based guidance number nonenrorcable.
Summary of California Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action Cleanup Level
Constituent
& Number
Level
Level
Laval
Gasoline
TPH
DHS Recommended
¦
NA
• •
•••Benzene
EPA Method 8020
•
NA
NA to Ippm
•••Toluene
EPA Method 8020
•
NA
NA to 50ppm
•••Ethylbenzene
EPA Method 8020
•
NA
NA to 50ppm
•••Xylene
EPA Method 8020
•
NA
NA to 50ppm
HVOs
EPA Method 8010
•
NA
Site Specific
Diesel
TPH
DHS Recommended
•
NA
10 to lOOOppm
TRPH
EPA Method 418.1
*
NA
100 to lO.OOOppm
OTrv n 1: u
a juiiiv a. v*a.
-)v au/v»
* Test Specific. * * TSere are three action levels associa^d w/ TPH A BTEX for sties wftjcti fall into caieconea tow. medium and high.
••• If BTFX levels are detectable, even though TPH cnocentraoon ts below iOppmgasor lOOppm D*esd proceed from sue investigation to
the general risk appramj. Note: Califcroa does not have stale staodard cleans cveh. Values shown are immuiieded acooo from the
LUFT manual. CTeam^j levels are site jpeafic. CiMorrua has 9 Reponal Bovds throughout the stale and 105 local afenexs. Notification a
required for all unauthorized releases unless the openior is abte to clean up the reiease within eight hour*. u cfad not esape from a secondary
axiuinment. dm not increase haanJ of fire crexpkxmn and did not desenome secondary contammeat of UST
CoDUct: Paul Johnston. California
Slate Water Resources.
Central Board 916-227-4337
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December 1994 Soils 19
B-6
-------
Summary of Delaware Cleanup Standards tor Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
APHA 5520C. 503B
5 mg/1
any amount
Site Specific**
EPA Method 418.1
5 mg/1
any amount
Site Specific**
California Method
5 mg/1
any amount
•
Site Specific**
GC-FID
BTEX
EPA Method 5030. 8020.
5 Mg/1
any amount
Site Specific**
8240
EPA Method 602. 624
5 Mg/1
any amount
•
Site Specific**
Equivalent Method
5 ng/1
any amount
*
Site Specific**
Diesel
TPH
Same As Gasoline
any amount
•
Site Specific**
Waste Oil
TPH
Same As Gasoline
any amount
*
Site Specific**
BTEX
Same As Gasoline
any amount
*
Site Specific**
No established action levels. site specific. ** Drinking water standards to approximately lOppm BTEX and Ipptn
[. Contact: Patncia M. Ellis. Ph.D.. Delaware Dept of Natural
^oce: Water samples not required during tank removal activities. Water samples required as pan of hydrogeologic investigation.
Resources & Environmental Control 302-323-4588
Summary of Delaware Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level*
I
Constituent
& Number
Level
Level
Level*
J
Gasoline
TPH
Mod 8015. Mod 418.1
40 mg/kg
any amount
100 ppm
Site Specific
EPA Method 9071
generally<100
APHA Methods 5520E/
40 mg/kg
any amount
Same As Above
5520C. 503B. 503E
TPH
California Method
10 mg/kg
any amount
Same As Above
GC-FD
BTEX
EPA Method 3010/8020.
1 mg/kg
any amount
BTEX>10ppm
Site Specific
5030/8020
B>lppm
general lyS 10 BTEX. 1 B
EPA Method 3810.8240.
1 mg/kg
any amount
8240 purge & trap. Mod 602
Diesel
TPH
as above
as above
any amount
1000 ppm
Site Specific
generally<1000
Waste Oil
BTEX
as above
as above
any amount
BTEX> lOppm
Site Specific
B>lppm
generally<10 BTEX. 1 B
TPH
as above
as above
any amount
1000 ppm
Site Specific
generallyfi lOOOppm
* Class 8 Site. Note: Class A sites—more sensitive, more stringent. Class B sites—average sensitivity. Class C
sites—less sensitive, less stringent Sites are rated by the DE DNREC as either A. B. or C. Facton influencing
ratings include well locations, groundwater depth, residential, commercial or industrial settings, etc.
: Patncia M. Ellis. Ph.D.. Delaware Department of Natural
Resources & Environmental Control 302-323-4588
Summary of Florida Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 602
NA
any amount
Ippb
Total Volatiles
EPA Method 602
NA
any amount
50ppb
Organic Aromancs
1.2 dichloroethane
EPA Method 601
NA
any amount
3ppb
(EDB)
EPA Method 601
NA
any amount
02ppb
1, 2 dichloroethane
Lead
50ppb
EPA Method 239.2
NA
any amount
MTBE
EPA Method 602
NA
any amount
50ppb
Diesel
Same As Above
Plus
PAHs (Excluding
EPA Method 610
lOppb
any amount
Detection Level
Naphthalenes)
Total Naphthalenes
EPA Method 610
NA
any amount
lOOppb
TRPH
EPA Method 418.1
NA
any amount
5 ppm
Waste Oil
Same As Diesel
Plus
Priority Pollutant
EPA Method 624
NA
any amount
Site Specific
Site Specific
Volatile Organics
Priority Pollutant
EPA Method 625
NA
any amount
Site Specific
Site Specific
Extractable Organics
Ar. Cd. Cr. Pb
NA
any amount
Site Specific
Site Specific
20 December 1994 Soils
B-7
-------
Summary of Florida Cleanup Standar-jo
for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection Notification
Level Level
Action
Level
Cleanup Level
Gasoline
Organic Vapor
Analysis
OVA with Flame
Ionization
lOppm
>500 ppm*
VOA50 ppm*
VOA< i OOopb*"
TRPH< lOppm**
• Soils »ith TPH readmp jreater than 500ppm lor 50ppm lor Diesel) require rcroediauon. Soiis with v^or readings Contact: Thomas Conrvdy. Florida Department of
•torn 10 *00 ppm mav recuire cleanup depending on site factor*. •• Soil c:canuo cntcna fortnermai uvaunent. Environmental Protection 904-488-0190
Summary of Georgia Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8020
1 Mg/1
any amount
5 Mg/1
Site Specific 5-71 pg/1
Toluene
EPA Method 8020
1 Mg/1
any amount
1000 Mg/1
Site Specific
1000-200.000 Mg/1
Ethylbcnzene
EPA Method 8020
1 Mg/1
any amount
700 Mg/1
Site Specific
700-28.718 Mg/1
Xylene
EPA Method 8020
i Mg/1
any amount
10.000 ug/1
Drinking water standards
10.000Mg/l
Diesel/ Waste Oil
Benzo la) Pyrene
EPA Method 550. 8270
.06/10 Mg/1
any amount
.0311 Mg/1
Site Specific 0311-.2 Mg/1
Anthracene
EPA Method 8270
10 Mg/1
any amount
110.000 Mg/1
• 110.000 Mg/1
Chrysene
EPA Method 8270
10 Mg/1
any amount
.0311 Mg/1
• 0311 ug/1
Fluorajithene
EPA Method 8270
10 Mg/1
any amount
370 Mg/1
* 370 Mg/1
Fluorene
EPA Method 8270
10 Mg/1
any amount
14.000 Mg/1
* 14.000 Mg/1
Pyrene
EPA Method 8270
10 Mg/1
any amount
11.000 M E/l
* 11.000 Mg/1
ConUct: Mariin Gottscnalk. Ph.D . Georgia Department
• Georgia in-stream water quality standards of Natural Resources. 40*-362-2687
Summary of Georgia Cleanup Standards for Hydrocarbon Contaminated Soil*
Product
Parameter/ Lab Test Protocol
Constituent & Number
Detection
Level
Notification
Level
Action Cleanup Level
Level
Gasoline
BTEX
Diesel
Waste Oil
TPH Modified California
F.PA Method 8020 0.001 mg/kg
TPH Modified California
Method
TPH Modified California
0.1 mg/kg
any amount
0.1 mg/kg
0.1 mg/kg
any amount
20 mg/kg
any amount
any amount
100 mg/kg Site Specific/100-500 mg/kg
Site Specific/20- iOO mg/kg
100 mg/kg Site Specific/100-500 mg/kg
100 mg/kg Site Specific/100-500 mg/kg
" Amendments to the Georgia rules for underground storage tank management have oeca
proposed • the amendments would significantly revise the soil clean-up standards, the
amendments are expected to be adopted in January. 1995.
Contact: Mariin Gonschalk. Ph D.. Georgia Department
of Natural Resources. 401-362-2687
Summary of Hawaii Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Teat Protocol
4 Number
Detection
Level
Notification
Level
Action
Level
Cleanup Criteria
Above The UlC / Bek>w TV Llf
1 ik i MiufcJ) / Line (Makail
Gasoline
TPH as Gasoline
EPA Method 5030. 8015
• ••¦
••••¦j *••••
or LUFT Method
Benzene
III!
005 / 1.7 ppm
Rthylbenrene
.7 / .14 ppm
Toluene
• •••
1/2.1 ppm
Diesel. Jet Fuel.
TPH as Diesel
••
• •••• /
Kerosene. Fuel Oil
Benzene
¦ •••
.005 / 1.7 ppm
Ethylbenzene
• ••*
,7/14 ppm
Toluene
• •••
1/2.1 ppm
Acenapthene
...
NS/ .320 ppm
Naphthalene
...
• •••
NS / .78 ppm
Fluoranihene
• • •
NS / .013 ppm
Benzo «a) Pyrene
• • ••
.0002 / NS ppm
• 5030/8015 or SO-iCY 8020 or 5030/ 8240 or oQl or 624 •• 3550/8015 or 3510/ 8270 or 3520/8270 or LUFT. Conttct: KimSavaae. Department ot Health Underground
••• ?5I()/ 8310or 332'J/ X3lOor 3510/8100or ibZQi 8100or 610. Ail spills over 25 galloru that c«n« be T.nir rtiuicnn *fW-
. oniuned and cleaned up within *4 hours. ~•••• So Cleanup cntena based on i'PH-ftowever that does no* Morage lanKLn
preclude use as screening method. Note: NS»No Standard. Note: Standards are currently undergoing revisions.
UlCsUndcfsroufKi Iniceiion Control.
December 1994 Soils 21
B-8
-------
Summary of Hawaii Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol Detection
& Number Level
Notification
Level
Action
Level
Cleanup Criteria
Above The UlC / Below The UlC
LineiMiukJi / Line (Main)
Gasoline
TPH as Gasoline
EPA Method 5030. 8015. LUFT
* •* *
«•*»•j •••••
Benzene
•
.05 / 1.7 ppm
Ethylbenzene
•
»•«*
7/1.4 ppm
Toluene
«
10/ 21 ppm
TPH as Diesel
« «
j ••••*
Benzene
•
• •••
05 / 1.7 ppm
Ethylbenzene
«
• •••
7/1.4 ppm
Toluene
*
10/21 ppm
Naphthalene
100/ 100 ppm
Acenapthene
• ••
100/ 100 ppm
Fluoranthene
»***
500 / 500 ppm
Benzo (a) Pyrene
• «*
1 / I ppm
• 5030/ 8015 or 5030/ 8020 or 5030/ 8240. •• 3550/ 8015 or 3540/ 8270 or 3550/ 8270 or LUFT Method.
••• 3540/ 8310 or 3550/ 83IOor 3540/ 8270 or 3550/ 8270. •••• All spills over 25 gallons thai cannot be
contained and cleaned up within 24 hourv •••*• No Cleanup criteria basal on TPH-towever that does not
preclude use as screening method. Note: NS=No Standard. Note: Standards are currently undergoing revisions.
UIC=Underground Injection Control.
Contact: Kim Savage, Department of Health Underground
Storage Tank Division 808-586-4226
Summarv of Idaho Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8020
lppb
any level
5 Mg/l
5 ppb(Mg/l)
Toluene
Ippb
any level
1000 Mg/1
1000 ppb (Mg/l)
Ethylbenzene
lppb
any level
700 Mg/l
700 ppb (Mg/l)
Total Xylenes
lppb
any level
10,000 Mg/l
10.000 ppb (Mg/l)
Diesel
PAH
EPA Method 8270
DWS
Drinking water standards
BTEX
EPA Method 8020
lppb
any level
Same As Gas
Same As Gas
Waste Oil
TPH
EPA Method 418.1
lOOppm
lOOppm
VOCs
EPA Method 8240
Site Specific
Drinking water standards
RCRA Metals
EPA Method 6010
Site Specific
Drinking water standards
PAHs
EPA Method 8270
Site Specific
Drinking water standards
Note: Risk based assessments are allowed on a case by case basis.
HES,INC.
Quality
Analytical Support
•UST/LUST
•RCRA/TCLP
• Pesticides / PCBs
• Inorganics
azleton
nvironmental
ervices, Inc.
CALL us at:
608-232-3333
or FAX us at
608-233-0502
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ilota manufacturer
ippller of...
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500- 12th Street S.E.
Madison, SO 57042
FAX: (605) 256-2629
Write In 327
22 December 1994 Soils
Writs In 154
Write In 354
B-9
-------
Summary of Idaho Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
EPA Method 8015
*
any amount
> 40ppm
Site Specific/40-200ppm
Modified as Gas
Diesel
TPH
F.PA Method 8015
~
any amount
> lOOppm
Site Specific/100-2000ppm
Modified as Diesel
Waste Oil
Chlorinated
EPA Method 8010
any amount
Site Specific
Site Specific
Solvents
or 8240
TPH
F.PA Method 418.1
•
any amount
> lOOppm
lOOppm
TCLP. RCRA
EPA Method 6010
•
any amount
Site Specific
Site Specific/
Metals
RCRA Critena
PCBs
EPA Method 8080
•
any amount
Site Specific
Site Specific
• Dependent on sample matrix and concentration. 10 mg/kg target. Contacts Thomas Neace. Idaho Division of
Note: Risk based assessments are allowed on a case by case basis. Environmental Quality 208-334-5860
Summary of Illinois Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Gasoline
Benzene
•
.002mg/l
• ••
Site Specific
BETX
•
002-.005**
• ••»
Site Specific
Other Petroleum
Benzene
¦
,002mg/l
Site Specific
BETX
•
.002-.005**
»•*
Site Specific
Naphthalene
•
010m g/1
• • •
« •• •
Site Specific
Acenaphthene
•
018mg/l
Site Specific
Anthracene
*
.0066mg/l
«*•*
Site Specific
Fluoranthene
•
0021m g/1
* • •
• •• •
Site Specific
Fluorene
•
0021mg/l
• ••
«•••
Site Specific
Pyrene
•
0027mg/l
• •••
Site Specific
Total Care. PNAs
00013-
0015**
• •••
Site Specific
Total Non-Care.
-
00076-
•••
• •• •
Site Specific
PNAs
010**
Waste Oil
LUST Pollutants
List
Compound
Specific
• ••
Site Specific
• Any aporoved tPA SW-R46 Method. •• Each ccr.stuuent has unique ADL. ••• Sotification cniena based on anv Contact: G. Tod Rowe. Illinois Environmental
release of proauct. not specific contaminant levels. •••" *ny amount above the cleanup objectives. ••••• Any amount Protection Aeencv 217-782-6761
obove the screening detection limns listed on LUST pollutants list •••••" Acceptable Detection Limits.
Summary of Illinois Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
• •••*
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Gasoline
Benzene
002m g/1
••
**•
Site Specific
BETX
002-.005mg/l
• •
• ••
Site Specific
Other Petroleum
Benzene
.002rag/l
• •
• ••
Site Specific
BETX
.002-.005me/l
•»
• ••
Site Specific
Naphthalene
660m g/1
• •
Site Specific
Acenaphthene
1.2mg/l
*•*
Site Specific
Anthracene
660m g/1
Site Specific
Fluoranthene
,660m e/1
•*
Site Specific
Fluorene
140mE/l
• ¦
Site Specific
Pyrene
!80mg/1
• ¦
Site Specific
Total Care. PNAs
0087-
«•
*•«
Site Specific
. lOmg/l
Total Non-Care.
.0051 -
Site Specific
PNAs
660mg/l
Waste Oil
LUST Pollutants
Compound
Site Specific
List
Specific
• Any approved USEPA SW-M6 Method. ••
Notification cniena based on any rctc
ase o» product, not specific
Contact: G.
Tod Rowe. Illinois Environmental
contaminant levels Any amount above the cleanup objective* •••• Any amount above the screening detection limits Protection Agency 217-782-6761
luted on LUST poilutanti list. ••••• Acceptable Dctecuon Limits.
December 1994 Soils 23
B-10
-------
Summary of Indiana Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Acceptable
Detection
Notification
Action
Cleanup Level
Constituent
Methods
Level
Level
Level
Kerosene.
Benzene. Toluene.
GC/PID 8020 or
5ppb(ug/l)
any amount
Site Specific
Site Specific
Gasoline
Eihylbenzene.
GC/MS 8240/60 or
Xylene'
GC/MS 524.2
TPH (optional)
GC/FID 8015 -
500ppb(ug/l)
Modified (California)
Naptha.
Benzene.
GC/PID 8020 or
5 ppb
any amount
5ppb
5ppb
Diesel
Toluene.
GC/MS 8240/60 or
Ippb
Ippb
Eihylbenzene.
GC/MS 524.2
700ppb
700ppb
Xylene* and
lO.OOOppb
lO.OOOppb
Semi-Volalile
GC/MS 8270 or
lOppb
any amount
Site Specific
lOOppb
Organics (SVOC)
GC/MS 525
TPH (optional)
GC/FID 8015 -
500ppb
any amount
Site Specific
Site Specific
Modified (California)
Waste Oil
voc*
GC/PID 8020 or
5ppb
any amount
Site Specific
MCLs
GC/MS 8240/60
Total SVOC
GC/MS 8270
lOppb
any amount
Site Specific
MCLs
TPH
418.1 IR
lOOOppb
any amount
Site Specific
Site Specific
PCB
GC/ECD 8080/8081
5ppb(ug/l)**
any amount
Site Specific
MCLs
Metals***
use the appropriate
set by the appro-
any amount
Site Specific
MCLs
SW-846 method
priate method
Contact: John Gunter. Indiana Department of
• This analysis also should include Methyl-tertiary-butyl-ether (MTBE1. " PCB Aroclor 1254 and 1260 Fnvimnmenial Mana«ment 317-233-6412
detection limit must be 10 ppb. ••• Metal scans must include: Banum. Cadmium. Chromium (total). Lead.
Mercury. Nickel, and Zinc.
Summary of Indiana Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Acceptable
Detection
Notification
Action
Cleanup Level
Constituent
Methods
Level
Level
Level
Kerosene,
Total Petroleum
GC/FID 8015-
20ppm
any amount
On-site
On-site
Gasoline
Hydrocarbons
Modified (California) or
> 100
< 100
(TPH)
GC/MS 8240/60
Off-site
Off-site
any amount
N.D.
Napiha.
TPH
GC/FID 8015 -
20ppm
any amount
On-site
On-site
Diesel
Modified (California) or
> 100
< 100
GC/MS 8270
Off-site
Off-site N.D.
any amount
Waste Oil
VOC* and
GC/PID 8020 or
20ppm
any amount
Site Specific
Site Specific
GC/MS 8240/60
SVOC and
GC/MS 8270
20ppm
any amount
Site Specific
Site Specific
TPH and
418.1 IR
20ppm
any amount
Site Specific
Site Specific
PCB and
GC/ECD 8080/8081
lppm
any amount
Site Specific
Site Specific
Metals'*
use the appropriate
set by the appro-
any amount
Site Specific
Site Specific
SW-846 method
priate method
* This analysis also should include Methyl-tertiary-butyl-ether (MTBE). ** Metal scans must include: Barium.
Cadmium. Chronuum (total). Lead. Mercury. Nickel, and Zinc.
Contact: John Gunter. Indiana Department of
Environmental Management 317-233-6412
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24 December )994 Soils
Write In 210
B-ll
-------
Summary of Iowa Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection Notification
Level Level
Action
Level
Cleanup Level
Gasoline
Benzene
Toluene
Xylene
F.:hylbenzene
OA-i
any amount
5 ppb
2420 ppb
12000 ppb
700 ppb
.Site Specific
Site Specific
Site Specific
Site Specific
Diesel
same
OA-1
any amount
same as
Gasoline
Site Specific
Was;e Oil
same
OA-I
any amount
same as
Gasoline
Site Specific
Summary of Iowa Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Oetectlon Notification
Level Level
Action
Level
Cleanup Level
Gasoiine
TPH
Iowa OA-1
anv amount
100 mg/kg
Site Specific
Diesel
TPH
Iowa O.A-2
anv amount
100 mgAg
Sile Specific
Waste Oil
TPH
Iowa OA-2
any amount
100 mg/kg
Site Specific
Contact: Jim Humeston. Iowa Department or Natural Resources 515-281-8957
Summary of Kansas Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection Notification
Level Level
Action
Level
Cleanup Level
Gasoline
Benzene
EPA Method 502.2. 8020
5ppb 5ppb
5ppb
5ppb
Ethylbenzene
EPA Method 502.2.503.1.
524.1.524.2
68ppb 68ppo
680ppb
680ppb
Toluene
EPA Method 502.2.503.1.
524 1.524.2
lOOppb lOOppb
lOOOppb
lOOOppb
Xylene
EPA Method 502.2.503.1.
524.1. 524,2
44ppb 44ppb
440ppb
440ppb
1-2 Dichloroethane
FPA Method 502.1.503.1
524 1.524 2.601.624.1624
5ppb 5ppb
5ppb
5ppb
Diesei
Napihalene
14.3ppb 14.3ppb
I43ppb
I43ppb
Summary of Kansas Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection Notification
Level Level
Action
Level
Cleanup Level
Gasoline
TPH
•
;o
100 ppm
!00ppm
Benzene
EPA Method 6020.8021.
8240.8260
. 14ppm
1.4 ppm
! 4ppm
1-2 Dichloroeihane
EPA Method 8010. 8021.
8240. 8260
8ppm
8 ppm
8ppm
Diesel
TPH
*
lOppm
100 ppm
iOOppm
Waste Oil
TPH
•
lOppm
100 ppm
lOOppm
Contact: Thoma* Winn. Department ct Health &
* Purge ind irap. Summation of peaxs chromiwgraph Environment. V13-296-1 684
Get on-line
with EPA
The EPA Cleanup Information
Bulletin Board System. CLU-IN.
offers a wide range of information
on line that can be downloaded to
your computer via modem.
To access CLU-IN. cail 301-589-
8366.
To contact the Help Desk by
voice phone, call 301-589-8368.
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Phone 508-872-1115 Fax 508-872-3468
Write in 390
December 1994 Soils 25
B-12
-------
Summary of Kentucky Cleanup Standards%r Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8240. 8260
5ppb
5ppb
5ppb
5 to 400ppb
8020 or 8021
Toluene
EPA Method 8240. 8260
8020 or 8021
lOOOppb
lOOOppb
lOOOppb
1000 to 9400ppb
Ethylbenzene
EPA Method 8240. 8260
8020 or 8021
700ppb
700ppb
700ppb
700 to 2400ppb
Xylene
EPA Method 8240. 8260
8020 or 8021
lO.OOOppb
lO.OOOppb
lO.OOOppb
lO.OOOppb
Diesel*
PAH
EPA Method 8100.
8270 or 8310
5ppb
5ppb
5ppb
5ppb
Waste Oil*
Oil & Grease
EPA Method 9070
5ppm
5ppm or
over background
>5ppm or over
background
less than background
Total Lead
EPA Method 7420.
7421 or 6010
I5ppb
I5ppb
!5ppb
I5ppb
* Currently under review, numbers may chanee Contact: Doyle Mills. Division ot Waste Management 502-564-6716
Summary of Kentucky Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline*
Benzene
EPA Method 8240. 8260.
0.006ppm
0.006ppm
0.006ppm
0.006 to 20ppm
8020 or 8021
Toluene
EPA Method 8240. 8260.
8020 or 8021
0.7ppm
0.7pptn
0.7ppm
0 7 to I30ppm
Xylene
EPA Method 8240. 8260.
8020 or 8021
7 Opptn
7.Opptn
7.0ppm
7 0 to 200pptn
Ethylbenzene
EPA Method 8240. 8260.
8020 or 8021
0.35pptn
0.35pptn
0.35ppm
0.35 to 550pptn
Diesel
PAH
EPA Method 8100.
8270 or 8310
Ipptn
Ippm
lpptn
1 ppm
Waste Oil
Oil & Grease
EPA Method 9071
lpptn
lOppm or
> lOppm or
< lOppm or
over background
over background
less than background
Total Lead
EPA Method 7420,
Ipptn
over background
over
less than background
7421 or 6010
or >lOppm
backeround
or < 20ppm
"These values varv depending on facility classification, see 080E. Conu,c,: 2?,yl5^Ls;?mMon 01 Waste Mana*emem
502-564-6716
Summary of Louisiana* Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline*
Benzene
EPA Method 8240
EPA Method 8020
5ppb
2ppb
any amount
MDL
Non-Deiect/Background
Toluene
EPA Method 8240
EPA Method 8020
5ppb
2ppb
any amount
MDL
Non-Detect/Background
Ethylbenzene
EPA Method 8240
EPA Method 8020
5ppb
-PPb
any amount
MDL
Non-Detect/Background
Xylene(Total)
EPA Method 8240
EPA Method 8020
5ppb
5ppb
any amount
MDL
Non-Detect/Background
Gasoline**
TPHG
CA DHS SW 846-
8015 Modified
any amount
1 ppm
>2.5ppm
BTEX
EPA Method 8020
any amount
25 ppm
_.5ppm
Diesel*
TPH-D
Modified 8015
250ppb
any amount
MDL
Non-Detect/Background
California DHS
Diesel**
TPH-D
CA DHS SW 8410.
8015 Modified
any amount
* * *
Waste Oil**
Oil & Grease
EPA Method 5520F
Standard Method
any amount
100 ppm
300ppm
Volatile Organics
EPA Method SW846-
M8260
any amount
lOppm
Note Louisiana is currently revising cleanup level* to reflect risk based levels. • Groundwater Pnxection Division •• Contact: Department ot Environmental
Underground Storage Tanks Division. •••No values at present time. California DHS SW&46-80I5 Modified. Quality 504-765-0741
26 December 1994 Soils
B-13
-------
Summary of Louisiana* Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection Notification Action
Level Levei Level
Cleanup Level
Gasoline
Diesel
BTEX
TPHG
TPHD. California
Ap.A.
TCLP
(Heavy Metals)
EPA Method 8020
any amount
any amount
Site Spectfic/clOOppm
Site Specific/<30()ppm
Site Specific/<300pptn
Waste Oil
SW846/I3H
any amount
Substitute C HW
Requirements
Note. Louisiaru is currently revising [heir cleanup 'ev«
-------
Summary of Maryland Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level (1)
Action Cleanup Level (2)
Level
Gasoline
BTEX and MTBE
EPA 602. 8020. 8240
Any Amount
>Background Site Specific
Diesel/Fuel Oil
TPH
Modified 8015
Any Amount
>Background Site Specific
Naphthalene
EPA 8240
or lOppm
Used Oil
TPH
EPA 418 1
Any Amount
>Background Site Specific
TCLP
Modified 8015
or lOppm
There are no promulgated clean-up standards. All decisions on how clean is clean ' are made via site-specific risk
characterization. Note: For groundwater there are no promulgated clean-up standards.
Contact: Herb Meade. Marylano Department
of the Environment 410-63 i
Summary of Massachusetts Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level (2)
Constituent
& Number
Levei
Level (1)
Level
A / B / C Site Specific
Gasoline
Benzene
NS
NS
5/2000ng/l
NS
5/ 2000/ 7000 Mg/l
Toluene
NS
NS
1000/6000ug/l
NS
1000/6000/50.000 ug/1
Ethylbenzene
NS
NS
700/4000ug/l
NS
700/ 30.000/ 4000 ug/1
Total Xylenes
NS
NS
6000/6000ug/l
NS
10.000/ 6000/ 50.000 ug/1
MTBE
NS
NS
700/50.000ug/l
NS
700/ 50.000/ 50.000 ug/1
Diesel
TPH
NS
NS
1000/50.000ug/l
NS
1000/NA/ 50.000 ug/l
Naphtalene
NS
NS
20/6000ug/l
NS
20/ 6000/ 6000 ug/1
Phenanthrene
NS
NS
50/50ug/l
NS
30/ NA/ 50 ug/1
Benzene
NS
NS
5/2000ug/l
NS
5/ 2000/ 7000 ug/1
Waste Oil
TPH
NS
NS
I000/50.000ug/t
NS
1000/N A/50.000 ug/1
Various Metals
NS
NS
Metal/ area specific NS
Metal/ area Specific
Various PAHs
NS
NS
Compound/ area
specific
NS
Compound/ area Specific
Sole: ue/l approximates ppb. NS= Nor Specified in regulation. NA= Not Applicable (Non-volatile contaminants). (I) Two notification
thresholds have been established depending upon potential use ol groundwater. < 2) Three cleanup values have been established depending
upon potential groundwater use/ exposure: A-groundwater actual/ potential dnnking water supply: B-where groundwater could be source of
vapor emissions to building; C-everywhere. Alternative levels possible based upon site-specific Risk Characterization.
Contact: John J. Fitzgerald. Mais.
Dept. of Environmental
Protection 617-932-7702
Summary of Massachusetts Cleanup Standards for Hydrocarbon Contaminated SoM
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level (1)
Action
Level
Cleanup Level (2)
Gasoline
Benzene
NS
NS
ILV60 Mg/g
NS
Site Specific/10-200Mg/g
Toluene
Ethylbenzene
Total Xylenes
NS
NS
NS
NS
NS
NS
90/500 ng/g
80/500 ng/g
500/500 ng/g
NS
NS
NS
Site Specific/90-2500(ig/g
Site Specific/80-2500Mg/g
Site Specific/500-2500pg/g
Diesel
MTBE
TPH
NS
NS
NS
NS
3/200 ng/g
500/2500 ng/g
NS
NS
Site Specific/3-200Mg/g
Site Specific/500-5000pg/g
Naphthalene
Phenanthrene
Benzene
NS
NS
NS
NS
NS
NS
4/1000 pg/g
100/100 (ig/g
10/60 ng/g
NS
NS
NS
Site Specific/4-IOOOpg/g
Site Speciftc/100-2500ng/g
Site Specific/10-200>ig/g
Waste Oil
TPH
Various Metals
NS
NS
NS
NS
500/2500 pg/g
Metal/ Area
specific
NS
NS
Site Specific/500-5000pg/g
Metal/ Area Specific
Note: Mg/g=ppm mass/ ma&s dry weight basis. NS= Nn Specified in regulation. < I) Two notification thresholds have been established for Contact: John J. Fitzgerald. Mass.
high" and "low" exposure potential areas. (2) Nine cleanup values have been established depending upon exposure potential/ accessibility of Dept. of Environmental
soil, and usd classification of underlying groundwater. Alternative cleanup levels are allowed based upon a site-specific risk characterization. Protection 617-932-7702
Note: Please refer to Massachusetts regulations 310 CMR 40.0000 for complete details on cleanup numbers and requirements.
h
n_
/ Mobile
/ Analytical
I_
Mobile Analytical
Ken Wilcox Associates, Inc.
Phone (816) 795-7997
Fax (816) 795-7998
Site Investigations and
Tank Closures
On-Site Chemical Analysis
• Compliance Quality Results
• BTEX (8020) and TPH (418.1)
• Other VOC Analysis
• One-Hour turnaround
• Cost Effective (No Remobilization)
• Sample Handling Minimized
• Geoprobe Sampling Available
EPA wants you
to know
EPA is updating a brochure that
provides information on how to
order a variety of informational
materials on USTs.
For a free copy, order publication
EPA 510-B-93-003 from NCEP.
Box 42419. Cincinnati. Ohio
45242. Or fax order to 5134fa-
6685.1
28 December 1994 Soils
Write In 145
B-15
-------
Summary of Michigan Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Criteria
Constituent
& Number
Level
Level
Level
A(ppb) / B(ppb) / C(ppb)
Gasoline
Benzene
502.2. 503.1.524.1
Ippb
any amount
1.2ppb
1.2/NA/60
Toluene
524.2. 602. 8020
Ippb
any amount
790ppb
1500/790/ ;io
Lthylbcnzene
8021. 8240. 8260. CLP-Low
Ippb
any amount
74ppb
680/7-1 / 31
Xylenes
All Above Except CLP-Low
3ppb
any amount
280ppb
13.000/280 /59
Premium Gas
MTBE
502.2. 503.1.524.1
50ppb
any amount
230ppb
230 /NA/ 380
524.2. 602. 8020
8021,8240. 8260. CLP-Low
Leaded Gas
Lead
200.8. 239.2. 1,620.
4ppb
any amount
4ppb
4/NA/66
6020. 7421
Diesel
BTEX**
Same As Gasoline
PNAs
525. 550.550.1.610
5ppb
any amount
Varies By
Vanes By Component
8270. 8310. CLP-Low
Component
8100*
Waste Oil
BTEX and Lead**
Same As Gasoline
PNAs
Same As Gasoline
A=Health based dnnking water value. B=Aesthetic drinking water value. C=GSI value.
Contact: Christine Flaga. Michigan Department
• Acceptable methods for determining PNA compounds are below MDLs of OM#6 when neither petroleum
of Natural Resources Environmental
hydrocarbons nor PNAs ait present. If present other PNA methods such as 8270 or 8310 should be used.
Response Division 517-373-0160
Summary of Michigan Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Criteria
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
lOppb
any amount
24ppb
24ppb
Toluene
• •
tOppo
any amount
16,000ppb
I6.000ppb
Ethylbenzene
• •
lOppb
any amount
I500ppb
I500ppb
Xylenes
a •
30ppb
any amount
5600ppb
5600ppb
Premium Gas
MTBE
a*
lOOppb
any amount
4600ppb
4600ppb
Leaded Gas
Lead
EPA Method 6020. 7420
lOOOppb
any amount
80ppb
80ppb
and 7421
PNAs
EPA Method 8270. 8310.
330ppb
any amount
•
•
CLP-RAS 8100
Waste Oil
BTEX and Lead
BTEX in Diesel at same levels as in gasoline
PNAs
Same as in Diesel
• Varies by component ••EPA Method 8020. 8021. 8240, 8260. CLP-RAS.
Note: Other metals and organic solvents of waste oils need to be tested for. Call MDNR for information.
Contact: Christine Flags. Michipn Department
of Natural Resources. Environment*)
Response Division 517-373-0160
Summary of Minnesota Cleanup Standards for Hydrocarbon Contaminated Groundwater 1
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
IPH
Wisconsin DNR
any amount
Site
Site Specific***
GRO Method
Specific***
VOCs
Purge & Trap GC
any amount
Site
Site Specific**
Procedure
Specific**
Diesel
TPH
Wisconsin DNR
any amount
Site
Site Specific***
DRO Method
Specific***
VOCs
Purge St Trap GC
any amount
Site
Site Specific**
Procedure
Specific**
Waste Oil-
TPH #
Wisconsin DNR
any amount
Site
Site Specific***
DRO Method
Specific***
VOCs
Purge 8l Trap GC
any amount
Sice
Site Specific* *
Procedure
Specific**
* Defined as virgin oil that is discarded before use ** Rased on nsk assessment and Minnesota Department of
Health Recommended Allowable Limits for dnnking *aict. (and multiples thereof "* In most cases, action and
cleanup levels in *roundwjMer are based on VQC levels.
Contact: Minnesota Pollution Control Agency
b 12-296-6300 or 1-300-657-3864
Continues on page 38-+
December 1994 Soils 29
B-16
-------
AL
Real
World
Experience
with
Technology-
Based
Solutions
Environmental
Remediation Services
• Thermal treatment of
contaminated soils
• Industrial facility decon-
tamination/restoration
• Site remediation
• Environmental demoli-
tion/dismantlement
• Mobile hazardous water
treatment
• Site assessment
• Drilling
Analytical Laboratory
Services
• Chemical analysis of
organic compounds
• Chemical analysis of
inorganics
• Leachate preparation
and TCLP
• Water quality analysis
and wet chemistry
• Air quality analysis
• Field sampling and
groundwater monitoring
• Mobile laboratory
services
#Waxymillian
Technologies
Boston • Pittsfield
Lanesboro
Call 1 •800*695*7771
Write In 165
30 December 1994 Soils
%
cadeMix
'ii
@0
Why clay is so difficult to handle,
and tips to minimize problems
By Alfred Conklin, Ph.D.
¦lay presents a challenge to
anyone who wishes to work
with soil. There are several
reasons for the difficulties that clays
pose. Several types of clays with
different characteristics occur in most
soils. Clays hold large amounts of
water and attract and hold cations and
organic matter. Also some are
extremely sticky and plastic (able to
hold a shape) while others are
slippery. If worked when wet they
become puddled—where particles act
independently of each other—making
them almost impervious to water.
Frequent traffic compacts clay.
type of clay called bentonite that is
used in oil drilling fields and
environmental treatment wells. Other
types of clay are used as fillers in
paper and other consumer products. In
the chemical industry, clay is used as
a catalyst to increase the rate of
certain chemical reactions. Some
researchers have even suggested that
soil clays acted as a catalyst for life on
earth.
The soil scientist defines clay as
inorganic panicles less than 0.002 mm
in diameter. Panicles this small are
colloidal, that is, they do not settle out
of aqueous suspension. Clays can be
HOh hoh
h°H HOh
HOh
HOh
HOh hoh hoh hoh
000000000000000
HOh o
HO
HO
HOh O
HO
o
H H \ / \ / \ /\ /\/\/\/\/\/w\/
OH OH OH OH OH OH OH OH OH OH OH OH OH OH
.. HOh O OOOO
^ HH HH HHHHHH
O O
H H
Mg
O
H H
Figure 1
resulting in impervious layers. Proper
handling can ameliorate some of these
problems, but they cannot be totally
reversed.
Clay is a common pan of everyday
life. Modeling clay comes to mind as
a common product. Clay is used in
many useful ways. Drilling mud is a
Alfred Conklin Jr., Ph.D. is a
professor in the agriculture
department of Wilmington College,
Wilmington, Ohio.
divided into two broad classes
depending on their origin: clays that
are unchan^p from rock, primary
minerals—and those that have been
significantly changed, secondary
minerals. In soil, secondary minerals
are most common. Thus, in this
discussion, we will only consider
these secondary clay minerals, their
characteristics and how they affect
physical and chemical characteristics
and remediation of contaminated soils.
Soil clays are constantly being
synthesized and decomposed, so that
Continues on page 32
B-17
-------
Stat# standards,
from page 29
Summary of Minnesota Cleanup Standards for Hydrocarbon Contaminated Sojl
Product
Parameter/
Constituent
Lab Test Protocol
S Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
TPH
Wisconsin DNR
any amount
40 ppm"*
Site SDCCitk****
G RO Method
BTEX
«
any amount
40 ppm**
Site Specific*0"*
MTBE
•
my amount
40 ppm**
Site Specific****
Diesel
TPH
Wisconsin DNR
any amount
lOppnr"**
Site Specific****
DRO Method
BTEX
ft
any amount
10 ppm*"
Site Specific****
Waste Oil
Same as Diesel
* All sa/npies. en tan specifically noted. Should use an EPA approved method nr equivalent. " Soil Vaoor
t**adsp*ce aiuiyni i aQppm. Visual evidence of contamination or soil vapor heads pace £ 10 ppm-
"••• Additional investigation needed if base. sidev.aU sot! samples are >50ppm TPH for sands.
Contact: Minnesota Pollution Control Agency
612-296-6300 or 1-800-657-1864
Summary of Mississippi Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Teat Protocol
Detection
Notification
Action
Cleanup Level
Conatltuent
& Number
Level
Level
Level
Gasoline
BTEX
EPA Method 602,624.
•
any amount
18 ppm
m •
8020.8240.8260
of more
Diesel
TPH
EPA Method 418.1
Ippm
any amount
18 ppm
• •
or more
Waste Oil
TPH
EPA Method 418.1
Ippm
any amount
18 ppm
**
or more
• Benzene- 09ppb. Toulette-.lppb, Eihylbeniene-.05ppb. Meia & Para Xylene-. Ippb.
Contact: Manila Martin. Mississippi Underground
•* !8ppm or less if no sensitive environmental receptors present.
Storage Tank Division 601-9AI-50S8
Summary of Mississippi Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Teat Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
BTEX
EPA Method 602. 624,
«
any amount
lOOppm
**
8020. 8240.8260
or over
Diesel
TPH
EPA Method 418.1
4ppra
any amount
100 ppm
..
or over
Waste Oil
TPH
EPA Method 418,1
Ippm
any amount
100 ppm
«•
or over
¦ Benzene-11.25ppb. Toluene-i2.5ppb. Eihylbenzene-6.25ppb. Meta & Para Xylene-i2 5ppb.
•* lOOppm or less if no sensitive environmental receptors present
CooUet: Martha Martin. Mississippi Underground
Storage Tank Division 601*961-5058
Summary of Missouri Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Teat Protocol
Detection
Notification
Action
Cleanup Level
Conatltuent
4 Number
Level
Level
Level
TPH
EPA Method 418,1
5.0ppm
5.0ppm
Site
Site SpecifK/5-IQppm
Specific
Benzene
EPA Method 8020 or
OOSppm
.OOSppm
Site
Site Specific/J-50ppb«
3240
Specific
Toluene
EPA Method 8020 or
005ppm
OOSppm
Site
Site Specific/max ISOpps
8240
Specific
Ethylbenzene
EPA Method 8020 or
-OOSppm
.OOSppm
Site
Site Specific/max 320ppb
8240
Specific
Xylene
EPA Method 8020 or
.OOSppm
,005ppm
Site
Site Spectfic/max 320ppb
8240
Specific
Total BTEX
EPA Method 8020 or
OOSppm
,005ppm
Site
Site Specific/mai 750ppb
8240
Specific
ic I"v9Cflltnjfe
JalllC (U VJuUllllC
TPH
EPA Method 418.1
Same as Gasoline
BTEX
EPA Method 8240
Same as Gasoline
Heavy Metals
EPA Method 1311/6010
TCLP
Contact the Environmental Services Program. Site specific.
Gasoline
Diesel
Waste Oil
(TCLP)
* 5ppb for Drinking Water. Not*: Regulatory levels ;n 40CFR 261.24
Note; In iamiary 1995 new regulations which will affect TPH irKthodolcmy *ni b* promoigated.
contact Miswmn Department of Natural Resources with question*.
Contact; John Crawshaw, Missouri Department o!
Natural Resources 116-795-8653
38 December 1994 Soils
B-18
-------
Summary of Missouri Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Notification
Action
Cleanup Level
Level
Level
Level
5.0ppm
25ppm
Site
Site Specific/50-500ppm
Specific
05ppm
5ppm
Site
Site Specific
Specific
Min (Total BTEX<2ppm)
05ppm
Total BTEX
Site
Max (Benzene 2ppm.
Ippm
Specific
Toluene lOppm.
05ppm
Total BTEX
Site
Ethvlbenzene 50ppm,
lppm
Specific
Xylene 50ppm)
05ppm
Total BTEX
Site
lppm
Specific
Gasoline
Diesel
Waste Oil
TPH
Benzene
Toluene
Eihylbenzene
Xylene
Same as Gasoline -
TPH
BTEX
Heavy Metals
EPA Method 418.1
Modified
EPA Method 8020 or
8240
EPA Method 8020 or
8240
EPA Method 8020 or
8240
EPA Method 8020 or
8240
Same as Gasoline
EPA Method 8240
EPA Method 1311/6010
(TCLP)
Same as Gasoline ^
40 mg/kg Contact the Environmental Services Program. Site Specific
Note: TCLP Regulatory levels in 40CFR 261.24
Note: In January 1995 new regulations which will affect TPH methodology will be promolgated.
contact Missouri Department of Natural Resources with questions.
Contact: John Crawshaw. Missouri Department of
Natural Resources 816-795-8655
Summary of Montana Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
GRO**
Not Specified
any concentration
Not Specified Site Specific
Benzene
602. 624. 524.2
Not Specified
any concentration
5.0ppb > MCL (Site Specific)***
Toluene
602. 624. 524.2
Not Specified
any concentration
lOOOppb > MCL (Site Specific)
Ethylbenzene
602. 624. 524.2
Not Specified
any concentration
700ppb > MCL (Site Specific)
Xylenes
602. 624, 524.2
Not Specified
any concentration
10,000ppb > MCL (Site Specific)
Diesel
TPH
DRO**
Not Specified
any concentration
Not Specified Site Specific
BTEX
Same As Gasoline
Waste Oil
TPH
DRO** with a used oil
Not Specified
any concentration
Not Specified Site Specific
standard
VOCs*
624. 524.2
Not Specified
any concentration
Not Specified See above for BTEX
Cadmium.
Not Specified
Not Specified
any concentration
5-10ppb 5-10ppb
Chromium. Lead*
Metal Spec. Metal Spec.
* Contamination from metals and halogenated VOCs is under the jurisdiction of another program.
•• Must be performed according to MDHES guidelines.
•** <5.0ppb for waier used for domestic purposes
Contact: Michael Savlta. Montana Department of Health
and Environmental Sciences 406-444-5970
Summary of Montana Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
GRO**
Non-specific
100 ppm
NA
Site Specific >100ppm
Levei Required
Benzene
EPA Method 8020. 8260
Non-specific
1 ppm
NA
Site Specific Slppm
Level Required
Total BTEX
EPA Method 8020, 8260
Non-specific
10 ppm
NA
Site Specific > lOppm
Level Required
Site Specific SlOOppm
Diesel
TPH
DRO**
Non-specific
100 ppm
NA
Level Required
Waste Oil
TPH
DRO** with a used oil
Non-specific
100 ppm
NA
Site Specific SlOOppm
standard
Level Required
VOCs
EPA Method 8260
Non-specific
NA
See above for BTEX*
Cadmium.
Not Specified
Non-specific
NA
*
Chromium. Lead
Level Required
' Contamination from metals and halogenated VOCs is under the jurisdiction of another program. Contact:
'• Must be performed according to DHES guidelines.
Michael Savka. Montana Department of Health
and Environmental Sciences 406-444-5970
December 1994 Soils 39
B-19
-------
Summary of Nebraska Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Oetectlon
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Benzene
EPA Method 8021.8020.
8240. 8260. 602. 624
< Cleanup
Level
any amount
> Cleanup
level
Sppb
Toluene
EPA Method 8021,8020.
3240. 8260. 602. 624
< Cleanup
Level
any amount
> Cleanup
level
jDOOppb
Ethylbenzene
EPAMethoa 8021.8020,
3240. 8260. 602. 624
< Cleanup
Level
3ny amount
> Cleanup
level
7000ppb
Xylenes
EPA Method 8021.8020.
3240. 8260.602. 624
< Cleanup
Level
any amount
> Cleanup
level
" O.OOOppb
TRPH
EPA Method 418.1
£ Cleanup
Level
any amount
> Cleanup
level
ZOOOppb
Diesel
Benzene
EPA Method 8021. 8020,
8240. 8260. 602. 624
< Cleanup
Level
any amount
> Cleanup
level
Sppb
Toluene
EPA Method 8021.8020.
8240. 8260, 602. 624
< Cleanup
Level
any amount
> Cleanup
level
1000ppb
Ethylbenzene
EPA Method 8021.8020.
8240, 8260, 602,624
< Cleanup
Level
any amount
> Cleanup
level
7000ppb
Xylenes
EPA Method 8021.8020.
8240, 8260,602. 624
< Cleanup
Level
any amount
• > Cleanup
'"•level
! O.OOOppb
TRPH
EPA Method 418.1
< Cleanup
Level
any amount
> Cleanup
level
2000ppb
Waste Oil*
TRPH
EPA Method 418.1
< Cleanup
Level
any amount
"k. Cleanup
level
2000ppb
• Other sampling, analysis and cleanup regulations established on a case by case basis. Contact: Marc Fisher. Nebraska Department of
Environmental Quality 402-471 -4230
B-20
-------
Summary of Nebraska Recommended Cleanup Goals for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8021. 8020
< Cleanup
any amount
> Cleanup
Site Specific/.005-50ppm
8240.8260
Level
Level
Total BTEX
EPA Method 8021. 8020
< Cleanup
any amount
> Cleanup
Site Specific/l-10,000ppm
8240. 8260
Level
Level
TRPH
EPA Method 418.1
< Cleanup
any amount
> Cleanup
Site Specific/10-500ppm
Diesel
Benzene
EPA Method 8021.8020
< Cleanup
any amount
> Cleanup
Site Specific/.005-50ppm
8240. 8260
Level
Level
Total BTEX
EPA Method 8021. 8020
< Cleanup
any amount
> Cleanup
Site Specific/l-10.000ppm
8240.8260
Level
Level
TRPH
EPA Method 418.1
S Cleanup
any amount
> Cleanup
Site Specific/100-500ppm
Waste Oil*
TRPH
EPA Method 418.1
< Cleanup
any amount
> Cleanup
Site Specific/ 10-500ppm
VOCs. SVOCs
EPA Method 8240/
S Cleanup
any amount
> Cleanup
Established Case-By-Case
8260: 8270
Level
Level
* Other sampling, analysis and cleanup regulations are established on a case by case basis.
Note: Soil levels are recommended and not stipulated by regulation.
Contact:
Marc Fisher. Nebraska Department of
Environmental Quality 402-471-4230
Summary of Nevada Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 624*
1 Mg/1
> 25 Gallons or
MCLs
MCLs
3 Cubic Yards
5ppb
Toluene
EPA Method 624*
1 ng/1
MCLs Ippm
MCLs
Ethylbenzene
EPA Method 624*
1 Mg/1
MCLs.7ppm MCLs
Xylene
EPA Method 624*
I Mg/1
MCLs lOppmMCLs
Diesel
Benzene
EPA Method 624*
1 Mg/1
> 25 Gallons or
MCLs
MCLs
3 Cubic Y ards
As Above
Toluene
EPA Method 624*
1 Mg/1
MCLs
MCLs
Ethylbenzene
EPA Method 624*
1 Mg/1
MCLs
MCLs
Xylene
EPA Method 624*
1 Mg/1
MCLs
MCLs
•Other EPA approved methods are also acceptable for use.
on System.
For over 25 years, the Raytheon
Corporation has solved pollution
problems throughout the world.
Today, its subsidiary, Cedarapids Inc
with the help of other Raytheon
companies is providing thermal
remediation systems to decontaminate
hydrocarbon contaminated soils.
No other company offers as unique
a blend of petroleum/chemical
engineering, process equipment
manufacturing and proven field
experience in thermal soil remedia-
tion. Find out why Cedarapids
stationary or portable systems are
more capable, efficient, reliable and
safer to operate than other systems
on the market today.
Call (319) 399-4742 to discuss
your particular requirements.
Cedarapids
A RayftMM Company
Wilt* In 200
B-21
-------
Summary of Nevada Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Para mater/
Lab Test Protocol
Detection
Notification
Action Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
7PH
EPA Method 8015
10 trig/kg
> 25 Gallons or
!00ppm 100 ppm
Modified
3 Cubic Yards
Diesel
TPH
EPA Method 8015
lOmg/kg
> 25 Gallons or
100 ppm .00 ppm
Modified
3 Cubic Yards
Waste Oil
TPH
EPA Method 8015
10 nigAg
> 25 Gallons or
100 ppm 100 ppm
Modified
3 Cubic Yards
MCLs MCI .s
TCLP Inorganics
MCLs MCLs
Contact; Lmy Woods. Nevada Department of Conservation and Natural Kesouraj 702-687-4670
Summary of New Hampshire Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Teat Protocol
Detection
Notification
Action Cleanup Standards
Constituent
& Number
Level
Level
Level
Gasoline
voc
•
Test Specific
Same As
Site Specific Benzene 5ug/l
Cleanup Level
Ethylbenzene 700pg/l
MTBE lOOpg/l
Toluene lOOOjig/l
Xylenes IO.OOOug/1
No's 2.4,5.6 Fuel
voc
«*
Test Specific
Same As
Site Specific VOCs Same As Above
Oil aid Diesel
PAH
Cleanup Level
Benzo(a)pyrene .2pgfl
Naphthalene 20ug/l
Waste Oil and
VOC
Same as Above
iirailiar weight
PAH
products
Initially S260 plu$ MTBE ail other sajnotes 8020 pJys MTBE or 8240 piui MTBE or S260 plus MTBE.
* Initially 8250 ano «27G/83tO all other samples 8020, 8240, S260or 8270/8310
Contact: George Lombardo. New Hampshire Department
of Environmental Services 603-271-3503
Your remediation projects
deserve the best
"We make it happen!"
.EnviroSupply,
Service
INC
IC Engines
Thermal/Catalytic Oxidizers
Tin iustix mi: min iin:nisi nt innsruM/MMiox ;< sitwuL:s
J /Authorized service
dealer lor;
Baker Furnace
VR Systems
ThormTccn
Many ethers loo'
J Srra.7 equipment snips and rcntai:
Grixna wa:er sampling Remediation pumps
I'ID's I FiO's R-essure transducers
Cata loggers Gcncialors
DO meters Gas vapor probe
-------
» J
Summary of New Hampshire Cleanup Standards for Hydrocarbon Contaminated So]!
Product Parameter/ Lab Test Protocol Detection
Notification
Action Cleanup Guidelines I
Constituent & Number Level
Level
Level (ppm) (ppm)
Gasoline VOC * Test Specific
Same As
Benzene>.2
2
and TPH
Cleanup Level
l -2-Dichlorocthane> 04
.04
(TPH as gasoline!
Ethvlbenzene >75
75
Isopropylbenzene>23
23
MTBE>.6
.6
Totuene>75
75
Xylenes>750
750
TPH>10.000
10.000
No's 2.4.5,6 Fuel VOC, PAH and ** Test Specific
Same As
VOCs and TPH Same As Above
Oil and Diesel TPH (TPH as oil)
Cleanup Level
Napthalene >.66
.66
Acenapythene >.66
.66
Benzo(a)pyrcne >.66
.66
Benzo(b)Fluoranthene > 66
.66
Benzo(k)Fluoranthene > 66
.66
Chrysene > 66
.66
Dibenzo(a)anthracene > 66
.66
Fluoranthene > 66
.66
lndene(1.2.3-ed)pyrene > 66
.66
2-methylnaphthalene > 66
.66
Total Non-
>7800 >7800
Carcinogenic PAHs
Waste Oil and Same as Above
Site Specific Site Specific
similiar products Plus TCLP
|
' Initially 8260 plus MTBE and P&T-GC/FID for TPH. All other samples 8020 plus MTBE or 8240
plus MTBE and P&T GC1FTD for TPH.
••Initially 8260, 8270/8310 and extraction GC/FID for TPH. All other samples 8020. 8240. 8260 or
8270/8310 and extraction GC/FID for PAH.
Contact: George Lombardo. New Hampshire Department
of Environmental Services 603-271-3503
Summary of New Jersey Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level*
Gasoline
Benzene
EPA Method 524
(Drinking Water)
Test Specific
any amount
NS
1
Toluene
EPA Method 524
(Drinking Water)
Test Specific
any amount
NS
1000
Ethylbenzene
EPA Method 524
(Drinking Water)
Test Specific
any amount
NS
700
Xylene
EPA Method 524
(Drinking Water)
Test Specific
any amount
NS
40
Anthracene
EPA Method 525
Test Specific
any amount
NS
2000
Naphthalene
EPA Method 524.2
Test Specific
any amount
NS
Lead
NS
Test Specific
any amount
NS
10
Benzo (A) Pyrene
EPA Method 525
Test Specific
any amount
NS
NA
Diesel
Same As Above For Gasoline
NS=Not Specified
•Higher of Groundwater Quality Criteria or Practical Quantitation Limit.
EPA toughens
landfill rules
EPA's new Phase il Land
Disposal Restriction requires that
soils contaminated with benzene
and other organics must be treated
prior to disposal in a Subtitle C or
D landfill. New universal treatment
standards for over 200 hazardous
constituents have been identified.
This restriction will increase the
cost of landfilling contaminated
soils.
Contact: New Jersey Department of Environmental
Protection 609-984- 3156
Applied Environmental Services i
Environmentally Processed Asphalt I
Soil and Groundwater Remediation i
Hazardous Waste Management i
~~ Asphaltic Metals Stabilization i
Construction Management 1
Earth Sciences and Site Characterization p
Environmental Specialists Hydrogeoiogv ;
San Juan Capistrano, CA • (714)489-2777
El Centro, CA* (619) 353-5156
Write in 219
December 1994 Soils 43
B-23
-------
Summary of New Jersey Cleanup Criteria for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action Cleanup Criteria
Constituent
& Number
Levei
Level
Level
Rosorm / Non r
-------
Summary of New York Cleanup Standards for Hydrocarbon Contaminated SoN
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8021 or 8020
2ppb
any amount
I4ppb
Site Specific
Ethylbenzene
EPA Method 8021 or 8020
2ppb
any amount
lOOppb
Site Specific
Toluene
EPA Method 8021 or 8020
2ppb
any amount
lOOppb
Site Specific
Xylene
EPA Method 8021 or 8020
2ppb
any amount
lOOppb
Site Specific
MTBE
EPA Method 8021 or 8020
Ippb
any amount
1OOOppb
Site Specific
Other Compounds
EPA Method 8021
Compound
any amount
Compound
Site Specific
Listed in STARS #1
Specific
Specific
Diesel
Naphthalene
EPA Method 8021
Ippb
any amount
200ppb
Site Specific
Anthracene
EPA Method 8270
330ppb
any amount
1OOOppb
Site Specific
Fluorene
EPA Method 8270
330ppb
any amount
1OOOppb
Site Specific
Pyrene
EPA Method 8270
330ppb
any amount
1OOOppb
Site Specific
Other Compounds
EPA Method 8021
Compound
any amount
Compound
Site Specific
Listed in STARS #1
or 8270
Specific
Specific
Waste Oil
PCBs
EPA Method 8270
Compound
Compound
Compound
Compound
Specific
Specific
Specific
Specific
Contact: Chris O'Neill. New York Department of Environmental Conservation 518-457-9412
Summary of North Carolina Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 602
MDL
>!ppb
>lppb
> I ppb
or 502.2 & 524.2
Ethylbenzene
EPA Method 602
MDL
>29ppb
>29ppb
>29ppb
or 502.2 & 524.2
Toluene
EPA Method 602
MDL
>1OOOppb
>1OOOppb
>l000ppb
or 502.2 & 524.2
Xylenes
EPA Method 602
MDL
>530ppb
>530ppb
>530ppb
or 502.2 & 524.2
MTBE
Modified 602
MDL
>200ppb
>200ppb
>200ppb
Lead
3030C
MDL
>15ppb
>15ppb
>l5ppb
EDC
601
MDL
>0.38ppb
>0.38ppb
>0.38ppb
EDB
Modified 602
MDL
>0.0004ppb
>0.0004ppb
>0.0004ppb
or 502.2 & 524.2
Diesel.
BTEX
602 or 502.2 and 625
MDL
As Above
As Above
As Above
Kerosene, etc.
with 10 Largest Non-
Target Peaks Identified
Note: MDL = Method Detection Limit.
Contact: Mike Cleary. North Carolina Division of Environmental Management. 919-733-1322
^ ENSCl
ENVIRONMENTAL, INC
Serving the Mid-Atlantic and
Southeastern States
1-800-241-9890
High Point, NC • Raleigh, NC • Blackburg, VA • Chesapeake, VA • DanvilJe, VA
•Onsite and Offsite Remediation
• Environmental Consulting
• Project Oversite
•Industrial Services
• Hazardous Waste Management
M i rsr-..r- . Write In 198
46 December 1994 Soils
Learn from
the rule-maker
EPA offers a four-page Guide
for Alternative Technology
Demonstrations Projects that
give information about how to
set up demonstration projects
for alternative cleanup
technologies. EPA also offers
Technologies and Options for
UST Corrective Actions:
Overview of Current Practice
that summarizes experiences
and outlines state requirements.
Call 800-424-9346 for a free
copy of either or both
publications.
B-25
-------
Summary of North Carolina Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
G^oiine.
TPH
5030 sample prep, w/
MDL
Oppm
lOppm
Sue Specific*
A.'iaflon Fuels, etc
modified 8015
Diesel.
TPH
5030 + 3550 sample
MDL
5030-lOppm
lOppm
Site Specific*
Kerosene etc.
prep, w/ modified 8015
3550-40ppm
40ppm
Heavy Fuels
TPH
9071
MDL
>250ppm
>250ppm
Site Specific*
Virgin Products!
Waste Oil
It'll
9071 and 8021. if
9071 :> 250ppm or cmpds.
are detected by 8021. ihen
MDL
9071 i>250pomi
8021 OMDL)
1311 OMDL)
9071 (>250ppm) Site Soecific*
8021 OMDL)
1311 OMDLt
use 1311 (TCLP)
Vlctals
Pb. Ba. As. Cd
Cr. Ag. Hg. Se
131 KTCLP)
MDL
>Cleanup Level
>Cleanup
Level
Naturally Occurring
Background Concentrations
Note: MDL = Method Detection Limit. * North Carolina uses a Site Sensitivity evaluation lo Contact: Mike Cleary. North Carolina Division of
rate sites, cleanup criteria are based on evaluation. Environmenial Management. 91*>-733-1322
Summary of North Dakota Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Benzene
EPA Method 524.2
5?pb
any amount
5ppb
Site Spccitic/5ppD
Toluene
EPA Method 524.2
5ppb
any amount
5ppb
Sue Specific
Elhvlbenzene
EPA Method 524 2
5ppb
any amount
5ppb
Site Specific
Xylenes
EPA Method 524.2
5ppb
any amount
5ppb
Site Spectfic
Diesel
TRPH
F.PA Method 418.1
1 mg/1
Site Specific
Wasie Oil
Lead
EPA Method 239.2
2ug/l
Site Specific
Chromium
EPA Method 218.2
2Mg/l
Site Specific
Cadmium
EPA Method 213.2
2ug/l
Site Specific
Summary of North Dakota Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Oetectlon
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
G.Lsoline
TPH
EPA Method 418.! or
*DHS
any amount
100 ppm
Site Specific/10O+ ppm
Dse^el
TPH
EPA Method 418.1 or
any amount
100 ppm
Site Speciftc/lOO+ ppm
•DHS
Waste Oil
BTEX
EPA Method 8020
any amount
5mg/l
Benzene
Lead
EPA Method 239.2
any amount
5nig/l
Chromium
EPA Method 218.2
any amount
5mg/l
TOX
EPA Method 9020. 9022
any amount
1000mg/t
* California Department of Health Services Method. Contact: Dave GUu. Suie Department of Health and
Consolidated Laboratories 701-221-5210
Summary of Ohio Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Oetectlon
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 602
Method Specific
any amount
005 ppm
Site Specific-
Toluene
EPA Method 602
Method Specific
any amount
12 ppm
Site Specific
Ethylbenzene
EPA Method 602
Method Specific
any amount
.700 ppm
Site Specific
Total Xylenes
EPA Method 602
Method Specific
any amount
10 ppm
Site Specific
TPH
None Specified
None Specified
None Specified
None Specified None Specified
Diesel
Benzene
EPA Method 602
Method Specific
any amount
005 ppm
Site Specific
Toluene
EPA Method 602
Method Specific
any amount
12 ppm
Sue Specific
ELihylbenzene
EPA Method 602
Method Specific
any amount
.700 ppm
Site Specific
Total Xylenes
EPA Method 602
Meihod Specific
any amount
10 ppm
Site Specific
PNAs
EPA Method 610
Meihod Specific
any amount
Site Specific Site Specific
TPH
None Specified
None Specified
None Specified
None Specified None Specified
Waste Oil
VOAs
EPA Method 624
Meihod Specific
any amount
Site Specific Site Specific
Contact: Raymond Roe. Ohio Department ot Commerce <>14-752-7941
December 1994 Soils 47
B-26
-------
Summary of Ohio Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification Action
Cleanup Level
Constituent
& Number
Level
Level Level
Gasoline
Benzene
EPA Method 8020
Method Specific
Action Level Based .006 - 500 ppm Site Specific 1
Toluene
EPA Method 8020
Method Specific
Action Level Based 4-12 ppm
Site Specific
Eihylbenzene
EPA Method 8020
Method Specific
Action Level Based 6-18 ppm
Site Specific
Total Xvlenes
EPA Method 8020
Method Specific
Action Level Based 28-85 ppm
Site Specific
TPH
Modified Method 8015
Method
Action Level 105-600
Site Specific
Specific
Based ppm
Diesel
Benzene
EPA Method 8020
Method Specific
Action Level Based .006 - 500
Site Specific
Toluene
EPA Method 8020
Method Specific
Action Level Based 4-12 ppm
Site Specific
Eihylbenzene
EPA Method 8020
Method Specific
Action Level Based 6-18 ppm
Site Specific
Total Xylenes
EPA Method 8020
Method Specific
Action Level Based 28-85 ppm
Site Specific
PNAs
EPA Method 8100
Method Specific
Any Level Site Specific Site Specific
TPH
EPA Method 418.1
Method Specific
Any Level 380-1156ppm Site Specific
Contact: Raymond Roc, Ohio Department of Commerce 614-752-7941
Summary of Oklahoma Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
1/2/3 ppm
Gasoline. Diesel TPH
*
Ippm
any amount
TPH>2ppm
TPH: 2/ 10/25
and Kerosene
above action level
B>.005ppm
B: .005 / .05 / .5
8TEX
•
lppm
any amount
T>lppm
T: 1 /10 / 100
above acuon level
E>.7ppm
E: .7 / 7 / 70
X>10ppm
X: 10/100/1000
Summary of Oklahoma Cleanup Standards for Hydrocarbon Contaminated Soil
Product Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
1/2/3 ppm
Gasoline. Diesel TPH
*
lppm
any amount
TPH>50ppm
TPH: 50/500/ 1000
and Kerosene
above action level
B>.5ppm
B: .5/5 /10
BTEX
*
lppm
any amount
T>40ppm
T: 40/400/ 1000
above action level
E>15ppm
E: 15/ 150/ 1000
X>200ppm
X: 200/ 1000/1000
Note: Oklahoma uses a Rone&abon Index in determining cleanup standards on • ae-by-site boss.
* No methods are ^enficd- Whatever method a specified mug be able to detect the most stnngent cleanup levels.
Contact: Oklahoma Corporation Commission. Underground
Storage Tank Program 405-521-3!07
CONTAMINATED
SOIL SOLUTION
THERMAL I^EDIAjUarn^HNOiXHT^
Can Clean HydrocarbonContaminated~SoiL^
frdDtesiteo
• Cost effective
^future, liability
*•' No unnecessary^ se of
tmdfnrSpace^^ -
-Contact WHiewjurenvironmertfal.consultantfopjudber-
infomutkm regartfingTrae-of-our «quipmenfon your site. MDNR"
ahd MUSTfA have appioted Uiia fajiiwtemr.
__ Wezcanjrffer you a better solution to contamination cleanups.
rfclfc/lSB.qTlil
Fa* 616/258-6113
Kalkaska Construction Services, Inc. 418 S. Maple, KalkaskaTMt 4%46~
48 December 1994 Soils
Write In 237
EPA opens
tank training center
The EPA, in cooperation with
the University of Tennessee at
Chattanooga, has developed the
4M Center for Underground
Storage Tanks Training and
Technology.
The center provides training in
measurements, monitoring and
mitigation. It also develops
practical field experience on
technologies to assess and clean
up spills and leaks.
For more information call 615-
785-2103.
B-27
-------
Summary of Oregon Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
BTEX
EPA Method 8020 or
.5 ppb
any amount
B: Jppb. T: 700ppb
8240
E: lOOOppb, X: lO.OOOppb
Additives
F.PA Method 8010 or
.5 ppb
any amount
1 2-Dibromoethane-lppb
8240
I 2-Dichiotethane-5ppb
Lead-5ppb
Diesel
BTEX
Same As Gasoline Above
PAHs
EPA Method 8310
.1 ppb
any amount
Carcinogenic
Benzo (A) Pyrene .2ppb
Benzo(A)Anthracene .lppb
Benzo (b) Ruoranthene 0.2
Benzo (k) Ruoranthene 0.2
Chrysene 0.2
Dibenzo i a.bi Anthracene 03
Indenopyrene 0.4
Note: Oregon uses a sice scoring matrix to determine petroleum cleanup standards in soil. Contact: Michael Anderson. Department of
Environmental Qualify. 503-229-6764
Summary of Oregon Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Diesei
TPH
TPH
DEQ Method. TPH-G
DEQ Method. TPH-D
or TPH-418.1
10mg/kg
20mg/kg
any amount
any amount
Site Specific.
Level l=40opm.
Level 2=80ppm
Level 3=130ppm
Site Specific
Level l=100ppm.
Level 2=500ppm.
Level 3=1000ppm.
Note: Oregon uses a site scoring matrix to determine petroleum cleanup standards in soil. Contact. Michael Anderson. Department of
Summary of Pennsylvania Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8020
•2 |ig/l
any amount
None
Non-Detect
Toluene
EPA Method 8020
.2 Mg/1
any amount
None
Non-Detect
Ethylbenzene
EPA Method 8020
.2 ng/1
any amount
None
Non-Detect
Total Xylene
EPA Method 8020
any amount
None
Non-Detect
PHC
AP1-GRO
.1 mg/1
any amount
None
Non-Detect
Total Lead*
None Specified
any amount
Nooe
Non-Detect
Diesel
PHC
API-DRO
.1 mg/1
any amount
None
Non-Detect
* When tank contained a leaded Gasoline.
Contact: Doug Cordelli. Department of Environmental
Resources 717-772-5835
Summary of Pennsylvania Cleanup Standards for Hydrocarbon Contaminated Soils
Product
Parameter/
Lab Teat Protocol
Detection
Notification
Action
Cleanup Level
Conetltuent
& Number
Level
Level
Level
Gasoline
Benzene
F.PA Method 8020
2 Mg/1
0.2ppm
0.2ppm
0.2ppm
Toluene
EPA Method 8020
2 Mg/1
0.5ppm
0 5ppm
0.5ppm
Ethylbenzene
EPA Method 8020
2 pg/1
lppm
lppm
lppm
Total Xylene
EPA Method 8020
0.7pprn
0.7ppm
0.7ppm
PHC- Petroleum
API-GRO
5 mR/kg
200ppm
200ppm
200ppm
Hydrocarbons
Residential Areas 200 ppm
Total I^ad*
None Specified
any amount
N/A
Industrai Areas 600ppm
Diesel
PHC
API-DRO
4 mR/kg
200ppm
200ppm
200ppm
Waste Oil
TPH
EPA Method4l8.1
any amount
Site
Site Specific
Specific
, ... . i i i i. Ooauct: Doue Cordeib. Department ot Environmental
• When tank contained a leaded Gasoline. 8
Resources 717-772-5835
December 1994 Soils 49
B-28
-------
Summary of South Carolina Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
(MCLs)
Gasoline
BTEX
EPA Method 8020
Test Specific
any amount
• •
B:.5ng/1. T:1000(ig/I.
E:700pg/1, IO.OOOpg/1
MTBE
EPA Method 8020
Test Specific
any amount
• •
Recommended 40mg/1
TPH
EPA Method5030*
Test Specific
any amount
• •
Not Established
Diesel
BTEX
EPA Method 8020
Test Specific
any amount
• *
B:.5ng/1. T:1000pg/1.
E:700Mg/l. I0.000vig/1
Naphthalene
EPA Method 8020
Test Specific
any amount
**
Not Established
TPH
EPA Method 3510*
Test Specific
any amount
• •
Not Established
Waste Oil
BTEX
EPA Method 8240
Test Specific
any amount
B:.5pg/1, T:1000vig/1.
E:700Mg/l. I0,000yg/1
• California method or equivalent. **
Site Specific.
Summary of South Carolina Cleanup Standards rar Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
BTEX
EPA Method 8020
1 mg/kg
any amount
• *
Site Specific
TPH
EPA Method 5030»
10 mg/kg
any amount
**
Site Specific
Diesel
BTEX
EPA Method 8020
1 mg/kg
any amount
**
Site Specific
Naphthalene
EPA Method 8020
any amount
«*
Site Specific
TPH
EPA Method 3550*
10 mg/kg
any amount
• *
Site Specific
Waste Oil
BTEX
EPA Method 8240
1 mg/kg
any amount
«*
Site Specific
Naphthalene
EPA Method 8240
any amount
• •
Site Specific
TPH
EPA Method 9071
10 mg/kg
any amount
• *
Site Specific
• California method or equivalent.
•• Site Specific.
Contact: Read Miner. South Carolina Department of Health
& Environmental Control 803-734-5331
RYAN-MURPHY, INCORPORATED
Ryan-Murphy announces the opening of a soil remediation facility in Fontana, California.
The facility utilizes the GEM-1000 mobile thermal treatment unit to remediate soil.
The GEM Soil Recycling Facility provides:
• Recycling of petroleum contaminated
soils;
• Certificate of Recycling issued;
• Soil analysis by independent
laboratory;
• Competitive rates for any size project;
• Re-use of treated soil for commercial or
industrial projects;
• Termination of liability for the
generator.
RMI'S GEM 1000 mobile treatment unit (pictured above) can
remediate contaminated soil on your site or at the Good Earth Soil
Recycling Facility.
The GOOD EARTH SOIL RECYCLING FACILITY
8810 Cherry Avenue, Fontana, California
(909) 356-5100 fax (909) 356-5256 or (800)207-1995
ffyan-MwrpJiy, Incorporattd
The Good Earth Company" 4HI
50 December 1993 Soils
Write in 174
B-29
-------
Summary of South Dakota Cleanup* Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
~election
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Etiiylbenzene
«**
7ppm
-7ppm
7ppm
-7ppm
Benzene
•*»
OOSppm
.OOSppm
.OOSppm
005ppm
Toluene
...
Ippm
Ippm
Ippm
Ippm
Xylene
...
lOppm
lOppm
IQppm
lOppin
TPH
...
!ppm
-Ippm
.Ippm
**
Diesei
TPH
...
Ippm
Ippm
as
Waste Oil
TPH"
...
* FPm
!ppm
.Ippm
* South Dakota docs riot specifically refer io flic groundwater aualitv standards as "Cleanup Standard*" but in a practical sense they
are used as such ** Compliance in ihe .Ippm level is required tf the ccmurrunation t$ within the radius of influence of a well or Contact: Doug Miller. Department of
wiUtio > delineated well bead protection area, unless a variance >s obtained. Otherwise the compirace itveJ is lOppm. Environmental &rtd Natural
•** No particular method is specified however, methods used must conform with "Sti^danj Methods for Esamintrtion of Water and Resources 605-773-3296
Waste water* and "EPA Methods. Methods for Chemical Analysts of Waters and Wastes."
Summary of South Dakota Cleanup Standards for Hydrocarbon Contaminated Soil
I Product
Parameter/
Lab Test Protocol Detection
Notification
Action Cleanup Level
Constituent
& Number Level
Level
Level
| Gasoline
TPH
* lOppm
any amount
10-100 ppm 10-100 ppm«*
Diesel
TPH
•
Waste Oil
TPH
*
EPTOX Mediods
*
* California/ USGS rrwtfscd or similar methods thai can quaatify TPH by integrating all deux table pcjXs within Contact: Doug Miller. Department ot Ecvoronmenul
the time period in which 95* of (he recover*ole hydrocarbons are eluted. •• Action Levels/ Cleanup Levels arc Natural Resources 605-773-3296
Site Specific and are based on (he type of contaminant released, deptit to an aquifer and ibe soil type present
41 • A fully permitted
facility...
'Featuring state ot
the art technology
D AMBRA for;
CONSTRUCTION CO., INC.
RECYCLING PETROLEUM
CONTAMINATED SOIL
in a dean, efficient and cost effective system
dedicated to solving this environmental proDtem.
We Accept: Petroleum Contaminated
Soils for Recycling into:
• Gravel Roadbase
• Landfill Cover
• Aggregate in Hot Mix Asphalt Paving.
We Provide: Excavation, Loading
and Hauling Services to Facilitate Soil
Removal from the Site
PLEASE CALL OR WRITE:
D'Ambra Construction Co., Inc.
800 Jefferson Boulevard
Warwick, Rhode Island 02887
800-966-SOIL(7645) FX: 401-732-4725
Writ# in 211
December 1994 Soils 51
Polywall
¦ barrier s v s r e m I
I—
Linear Contaminant
Remediation System
Horizontal Technologies, Inc. (HTT) offers two innovative,
effective, and economical proprietary technologies. Separately
or together, ;hey can meet a wide variety of environmental
needs. The POLYWALL is constructed of a continuous sheet of
high density polyethylene geomembrane which is placed
vertically using specialized equipment. The LCILS. is a site-
specific configuration consisting of single or multiple lines of
multi-tiered, trenched, horizontal wells that can be used to
iniect or extract vapors or liquids. Both systems
are installed in a single pass without the "~
need for sheeting, shoring, <
dewatering,
• Interceptor
Trench Cutoff
• Containment
• AirSparpug
• Biortmediatioa
• Soil Hushing
• Product Recovery I
• SVE
: HORIZONTAL TECHNOLOGIES, INC
for mon information caiL-
1-800-989-1128
RO. Box 1S0820
Cape Coral, FL 33915
Fax 813-995-8465
Pnmdt'itf InmtettK SchMa te Suksmfact Earirmmmtal CUIenpi,
Write in 175
B-30
-------
Summary of Tennessee Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Benzene
SW-846
5030 P&T/ 8020 GC
.002ppm
any amount
> 5ppb
Applic. CL based on GW
Class, > 5ppb or >70ppb
TPH
Tennessee Method for
Gasoline Range Organics
.Ippm
any amount
> lOOppb
> lOOppb or >l000ppb
Diesel
TPH
Tennessee Method for
Diesel Range Organics
Ippm
any amount
> lOOppb
> lOOppb or >l000ppb
Waste Oil
TPH
503E or 418.1
Ippm
any amount
> lOOppb
> lOOppb or >1000ppb
Contact: Curtis Hopper. Tennessee Department of
Environment and Conservation 615-532-0956
Summary of Tennessee Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Total BTX
SW-846
.002ppm
any amount
>10 ppm
Applic. Q. based on GW Class.
5030 P&T/ 8020 GC
& Soil Perns. > lOppm- >S0Oppm
TPH
TN Method for
lOppm
any amount
>100 ppm
> lOOppm— >1000ppm
Gasoline Range Organics
Diesel
TPH
TN Method for
lOppm
any amount
>100 ppm
> lOOppm— >l000ppm
Diesel Range Organics
Waste Oil
TPH
503E or 418.1
lOOppm
any amount
>100 ppm
> lOOppm— >l000ppm
Contact: Corns Hopper. Tennessee Department of
Environment and Conservation 615-532-0956
Summary of Texas Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8020
Ippb
any amount
•
Site Specific/Risk-based**
Toluene
EPA Method 8020
Ippb
any amount
•
Site Specific/Risk-based**
Ethylbenzene
EPA Method 8020
IPP*>
any amount
*
Site Specific/Risk-based**
Xylene
EPA Method 8020
Ippb
any amount
*
Site Specific/Risk-based**
TPH
EPA Method 418.1
5ppm
any amount
Site
None***
Specific
Diesel
Benzene
EPA Method 8020
Ippb
any amount
«
Site Specific/Risk-based**
Toluene
EPA Method 8020
Ippb
any amount
•
Site Specific/Risk-based**
Ethylbenzene
EPA Method 8020
Ippb
any amount
a
Site Specific/Risk-based**
Xylene
EPA Method 8020
Ippb
any amount
«
Site Specific/Risk-based**
TPH
EPA Method 418.1
.5ppni
any amount
Site
None***
Specific
PAHs
EPA Method 8100,
Chemical
any amount
Site
Site Specific/Risk-based**
8270, 8310
Specific
Specific
Waste Oil
BTEX
EPA Method 8020
Ippb
any amount
«
Site Specific/Risk-based**
TPH
EPA Method 418.1
5ppm
any amount
Site
None***
Specific
VOCs
EPA Method 8240
Cbetracai Specific
any amount
Site Specific
Site Specific/Risk-based**
PAH
EPA Method 8100. 8270. 8310
ChemicaJ Specific
any amount
Site Specific
Site Specific/Risk-based**
* EPA Maximum Contaminant Level.
** No Range Available. Based on set procedures. •••Not used for establishing cleanup goals.
Contact: Chris Chandler. Texas Natural Resource
Conservation Commission 512-239-2200
EPA smiles at
immunoassay
The Environmental Monitoring
Systems Laboratory-Las Vegas
(EMSL-LV) is investigating the
usefulness of immunochemical
techniques to monitor contamination
in environmental and biological
matrices. EMSL-LV believes
immunoassay techniques hold great
promise for the quantitative analysis
of target analytes.
EPA SITE studies indicate a strong
correlation between field
immunoassays, laboratory
immunoassays and gas
chromatography-mass spectrometry.
Studies are underway in the use of
antibody-coated, fiber-optic
immunosensors.
52 December 1993 Soils
B-31
-------
Summary of Texas Cleanup Standards for Hydrocarbon Contaminated SoM
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Benzene
EPA Method 8020
.5mg/kg
any amount
Site Specific/Risk-based**
Toluene
EPA Method 8020
5mg/Vg
any amount
Site Specific/Risk-based**
Ethylbenzene
EPA Method 8020
5mg/Vg
any amount
Site Specific/Risk-based**
Xylene
EPA Method 8020
5mg/kg
any amount
Site Specific/Risk-based**
TPH
EPA Method 418.1
lOmg/kg
any amount
*
None***
Diese:
Benzene
EPA Method 8020
5mg/kg
any amount
Site Specific/Risk-based**
Toluene
EPA Method 8020
5mg/kg
any amount
•
Site Spccific/Risk-based**
Ethylbenzene
EPA Meihod 8020
5mg/kg
any amount
•
Site Specific/Risk-based**
Xylene
EPA Meihod 8020
3mg/kg
any amount
»
Site Specific/Risk-based**
TPH
EPA Meihod 418 1
lOmg/kg
any amount
•
None***
PAHs
EPA Meihod 8100.
8270.8310
Chemical
Specific
any amount
Site Specific/Risk-based**
Waste Oil
BTEX
EPA Meihod 8020
.5mg/kg each
any amount
Site Specific/Risk-based**
TPH
EPA Method 418.1
lOmg/kg
any amount
•
None4**
VOCs
PAH
EPA Method 8240
EPA Method 8100. 8270. 8310
Chemical Specific
OkttuoJ Specific
any amount
any amount
•
a
Site Specific/Risk-based**
Site Specific/Risk-based**
' Product Specific/ Site Specific.
'* No Range Available. Based on set procedures "••Not used for establishing cleanup goals.
Contact: Chris Chandler. Texas Natural Resource
Conservation Commission 512-239-2200
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Call today for your free EIS catalog:
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ENVIRONMENTAL
INSTRUMENT
gERVICES
Write In 092
December 1994 Soils 53
B-32
-------
Summary of Utah Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
TPH
CDHS Method
500ng/l
any amount
500m g/1
*
8015 Modified
Benzene
EPA Method 602 or 624
2ng/l
5m g/1
«
Toluene
EPA Method 602 or 624
2m g/1
1000m g/i
•
Ethylbenzene
EPA Method 602 or 624
2ng/I
700m g/1
«
Xylene
EPA Method 602 or 624
8/1
I 0.000m g/1
¦
Naphthalene
EPA Method 602 or 624
2pg/l
20m g/1
*
Diesel
TPH
CDHS Method
500p g/1
any amount
500Mg/I
*
8015 Modified
Benzene
2(jg/l
5m g/I
*
Toluene
2(jg/l
I000Mg/l
*
Ethylbenzene
2m g/1
700m g/1
•
Xylene
2m«/1
10.000m g/1
«
Naphthalene
2pg/l
20m g/1
*
Waste Oil
TRPH
EPA Method 418.1
500vig/l
any amount
•
Oil & Grease
EPA Method 413.1
10,000m g/1
any amount
10.000Mg/l
lO.OOOpg/l
BTEXN
Same as Diesel BTEXN Above
* Same as Action Level, but Site Specific
Note: Depends on level of environmental sensitivity and is determined on a case-by-case basis.
Contact: Robin Jenkins. Utah Department of
Environmental Quality 801-536-4100
Summary of Utah Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline**
TPH
CDHS Method
lOmg/kg
any amount
30mg/kg
•
8015 Modified
Benzene
EPA Method 8020
2mg/kl
any amount
2mg/kg
«
Toluene
EPA Method 8020
2mg/ki
any amount
lOOmg/kg
*
Ethylbenzene
EPA Method 8020
.2mg/kl
any amount
70mg/kg
*
Xylene
EPA Method 8020
.2mg/kl
any amount
iOOOmg/kg-
«
Diesel
TPH
CDHS Method
lOmg/kg
any amount
lOOmg/kg
«
8015 Modified
Benzene
EPA Method 8020
2mg/kl
any amount
.2mg/kg
«
Toluene
EPA Method 8020
.2mg/kl
any amount
lOOmg/kg
•
Ethylbenzene
EPA Method 8020
2mg/kl
any amount
70mg/kg
*
Xylene
EPA Method 8020
.2mg/ki
any amount
lOOOmg/kg •
«
x Waste Oil
Naphthalene
EPA Method 8020
2mg/kl
any amount
*
TRPH
EPA Method 418.1
lOOmg/kg
any amount
lOOmg/kg
«
Oil & Grease
EPA Method 413.1
lOOmg/kg
any amount
300mg/kg
•
BTEXN
Same as Diesel BTEXN Above
• Same as Action Level, but Site Specific.
** Level I environmental sensitivity.
Contact: Robin Jenkins. Utah Department of
Note: Depends on level of environmental sensitivity and is determined on a case-by
-------
Summary of Vermont Cleanup Standards for Hydrocarbon Contaminated Soil
product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
BTEX
EPA Method 8020
lOOppb
any amount
•
Site Specific
Diesel
BTEX
EPA Method 8020
any amount
•
TPH
EPA Method 418.1
lUppm
any amount
1000 ppm
Site Specific
or Extended GC
Waste Oil
VOCs
EPA Method 8240
100 Mg/Vc
any amount
•
Site Specific
* 20 limes trvc groundwater enforcement standard for specific compounds.
Contact: Chuck Scttwer. Agency of Environmental Conservation K02-241-1888
Summary of Virginia Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
ft Number
Level
Level
Level
Gasoline
BTEX
EPA Method 8020
•
any amount
Site Specific/Risk Based
TPH
Cal Luft Method
.5 mg/1
any amount
Site Specific/Risk Based
Diesel
BTEX
EPA Method 8020
•
any amount
Site Specific/Risk Based
TPH
Cal Luft Method
.5 mg/1
any amount
Site Specific/ Risk Based
Waste Oil
TPH
Cal Luft Method
5 mg/1
any amount
Site Specific/Risk Based
Summary of Virginia Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
BTEX
EPA Method 8020
*
any amount
Site Specific/Risk Based
TPH
Cal Luft Method
lOmg/kg
any amount
Site Specific/Risk Based
Diesel
BTEX
EPA Method 8020
«
any amount
Site Specific/Risk Based
TPH
Cal Luft Method
lOmg/kg
any amount
Site Specific/ Risk Based
Waste Oil
TPH
Cal Luft Method
•
anv amount
Site Specific/Risk Based
* PQL for constituents is suicd in SW84A Note: Methods above are rwjuircd for remediation monitoring under permit
During Site Chancierustion. Closure, etc. all EPA approved methods and CaJ tuft Method for TPH are acceptable.
Cootact: Dave Chance. Virginia DEQ
804-527-5188
FOR SALE
Like New-Used One Year
SOIL REMEDIATION PLANT
Tarmac 50-TPH
Located near Bristol, Virginia
Saltville, Virginia
703-496-4437
Write In 222
N
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GNB Environmental Services Inc.
A Pacific Dunlop Company
GNB, a leader In the metais industry, has the people,
systems, technologies, and commitment to handle all of
your soil remediation needs.
Treatability Testing
Stabilization/
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In-Situ Technologies
Metals Recovery
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Leaching
Thermal Treatment
RCRA/CERCLA
Corrective Actions
• Tank Services
GNB has four Regional Offices to serve you-.
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Headquarters Southeast South Central
(404)551-9100 (214)998-3505
MINNEAPOLIS LOS ANGELES
North Western
(612)681-5200 (213)262-1101
Write In 216
December 1994 Soils 55
B-34
-------
Summary of Washington Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol Detection
Notification
Action
Cleanup Level
Constituent
& Number Level
Level
Level
Gasoline
BTEX
EPA Method 8020 or 8260 *
any amount
NS
B. 5ppb. T.40ppb
E: 30ppb.X: 20ppb
TPH
WTPH-G
any amount
NS
lOOOppb
Total Lead
EPA Method 7421 ' *
any amount
NS
5ppb
Diesel
TPH
WTPH-D
any amount
NS
lOOOppb
Waste Oil
TCLP
*
any amount
NS
Analvte Specific
PCB
EPA Method 8080
any amount
NS
.1 Mg/l
Total Metals
EPA Method 6010, 7000 *
any amount
NS
Metal Specific
Series
Volatile Organics
EPA Method 8021.8260 •
any amount
NS
Analyte Specific
Phenols
EPA Method 8040 or 8270 •
any amount
NS
Analyte Specific
PAHs
EPA Method 8100 or 8270 •
any amount
NS
.1 Mg/l
* Test Specific. NS=Not Specified.
Contact: Mary Ellen McfCain. Washington Department of Ecology. 206-407-7218
Summary of Washington Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol Detection
Notification
Action
Cleanup Level
Constituent
& Number Level
Level
Level
MMhod A / Mrthod B
Gasoline
Benzene
EPA Method 8020 or 8260 *
any amount
NS
5mg/kg / .5mg/kg
Ethylbenzene
EPA Method 8020 or 8260 *
any amount
NS
20mg/kg / 20mg/kg
Toluene
EPA Method 8020 or 8260 •
any amount
NS
40mg/kg / 40mg/kg
Xylenes
EPA Method 8020 or 8260 •
any amount
NS
20mg/kg / 20mg/kg
TPH
WTPH-G
any amount
NS
I00mg/kg/ lOOmg/kg
Total Lead
EPA Method 6010. 7420 •
any amount
NS
250mg/kg/ lOOOmg/kg
or 7421
Diesel
TPH
WTPH-D
any amount
NS
200mg/kg / 200mg/kg
Waste Oil
TCLP
EPA Method 1311
any amount
NS
Analvte Specific
PCBs
EPA Method 8080
any amount
NS
Img/kg
Volatile Organics
EPA Method 8021
any amount
NS
Analyte Specific
or 8260
Phenols
EPA Method 8040 or 8270 •
any amount
NS
Analyte Specific
PAHs
EPA Method 8100 or 8270 •
any amount
NS
lmg/kg
Total Metals
EPA Method 6010 and •
any amount
NS
Metal Specific
7000 series
• Test Specific. NS=Non Specified. Note: Washington State has rating main* for establishing cleanup standards- Contact: Mary Ellen McKain. Washington
Method A = Routine Cleanups with numbers in Method A Tables. Method 8 = Residential (Risk Based) Department of Ecology, 206-407-7218
Method C = I) Commercial (Risk Based). 2) Indunnai (Risk Based). Methods A or B dean up levels are below
Area Backround Levels.
Summary of West Virginia Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Constituent
Lab Test Protocol
& Number
Detection
Level
Notification
Level
Action
Level
Cleanup Level
Gasoline
Benzene
EPA Method 8020
Ippb
any amount
5ppb
5 ppb
Toluene
EPA Method 8020
Ippb
any amount
1000 ppb
lOOOppb
Ethylbenzene
EPA Method 8020
lppb
any amount
700 ppb
700 ppb
Xylenes
EPA Method 8020
Ippb
any amount
10,000 ppb
10.000 ppb
TPH
EPA Method 8015
5ppm
any amount
Site Specific
Toluene
EPA Method 8020
lppb
any amount
1000 ppb
1000 ppb
Diesel
Benzene
EPA Method 8020
Ippb
any amount
5ppb
5 ppb
Ethylbenzene
EPA Method 8020
lppb
any amount
700 ppb
700 ppb
Xylenes
EPA Method 8020
lppb
any amount
10.000 ppb
10.000 ppb
TPH
EPA Method 8015
Modified. GRO & DRO
5ppm
any amount
Site Specific
56 December 1994 Soils
B-35
-------
Summary of West Virginia Cleanup Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8020
any amount
50ppb
Site Specific
Toluene
EPA Method 8020
any amount
lOppm total
Site Specific
BTEX
Ethylbenzene
EPA Method 8020
any amount
lOppm total
Site Specific
BTEX
Xylenes
EPA Method 8020
any amount
lOppm total
Site Specific
BTEX
TPH
EPA Method 8015
50ppm
Site Specific
Modified*
Diesel
Benzene
EPA Method 8020
any amount
50ppb
Site Specific
Toluene
EPA Method 8020
any amount
lOppm total
Site Specific
BTEX
Ethylbenzene
EPA Method 8020
any amount
lOppm total
Site Specific
BTEX
Xylenes
EPA Method 8020
any amount
lOppm total
Site Specific
BTEX
TPH
EPA Method 8015
lOOppm
Site Specific
Modified*
" Repon GRO and DRO separately
Contact: Mike Sutptun. West Virginia Department of
Natural Resources 304-558-6371
Summary of Wisconsin Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Conatltuent
& Number
Level
Level
Level
Gasoline
GRO.
DNRWl Modified GRO Mated
•*
any amount
None
Site Specific
VOC]
EPA Method 5030/ 8021
••
any amount
Compound Specific
PVOC4
*
••
any amount
Site Specific
Benzene
EPA Manod 8021 or 5030/8020
• a
any amount
5ppb
.5
Toluene
•
••
any amount
343«
68.8
Xylenes
«
M
any amount
6206
124
Ethylbenzene
*
any amount
1360^
140
MTBEJ
EPA Method 8021
••
any amount
60ppb
12
Trimethylbenzene(s)
Lead*
EPA Method 3020/ 7421
«•
any amount
iSppb6
1J
Diesel
GRO. VOC1
Same as above
None
None
PVOC"
for Gasoline
PAH5
EPA Method 8310 (HDLO
any amount
See Below
See Below
BTEX & MTBE
Same as above
for Gasoline
Waste Oil
PCBs5
EPA Method 3510/ 8080.
••
any amount
.036
¦0036
or 3520/8080
DRO.VOC3.
Same as above
None
None
PVOC
for Gasoline
Lead^
Same as above
CDJ
EPA Method 3020/7131
¦ •
any amount
5ppb<>
5ppb6
PAHs
Benzo (A) Pyrene
EPA Method 8310rHDtn
••
any amount
003ppb
0003ppb
Napthalene
EPA Method 8310 (HDLC)
• •
any amount
40ppb
8ppb
* EPA Method 303(Y 8021 or S03(V 8020 •• Test Specific I. Wisconsin Admin. Code NR 1*0 Enforcement Standard (acuve remedy required). 2. Wisconsin Admin. Code
NRI40 Preventative Action Level (cleanup goal). 3 Sample n lent once. 4. Petroleum Volatile Organic Compounds defined in analytical guidance. 5. Site Specific. 6. See
aAaiyocal guidance. 7. Proposed new level, scheduled forea/ly 199V
Summary of Wisconsin Criteria* for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
GRO
W| DNR Modified
• •
any amount
10 ppm4
Site Specific
GRO Method
PVOCI
EPA Method 8260 or
e «
any amount
Any Amount
voc3
5030/8020 or 5030/8021
PB2
EPA Method 3050/ 7420 or
••
any amount
Any Amount^
Site Specific
3050/7421 or 3050/6010
Diesel
DRO
DNR Modified
••
any amount
10 ppm4
Site Specific
DRO Method
PVOC
F.PA Method 8260 or
•*
any amount
Any Amount
• ••
5030/8020 or 5030/8021
58 December 1994 Soils
B-36
-------
PAH3
EPA Method 8310HDLC *•
3540/8270 or 3550/8270
any amount
Any Amount
Site Specific
Waste Oil
PAH3
EPA Method 8310HDLC **
3540/8270 or 3550/8270
any amount
Any Amount^
Site Specific
VOC2-3
EPA Method 5030/8021
or 8260
any amount
Any Amount
Site Specific
PVOC
EPA Method 5030/8020 or ••
5030/8021 or 8260
any amount
Any Amount^
PCB
EPA Method 3540/8080 ••
or 3550/8080
any amount
Any Amount
Site Specific
* The soil cleanup standards given currently have the statu* of guidance and are expected to be in code before the Contact: Greg Parker. Wisconsin Department
end of 1994. •• Test Specific. •"•Benzene-5.5. Toluene-1500. Ethylbenzene-2900. Xylene-1100. 1.2. dichloroctane-4.9. of Natural Resources 608-267-7560
Notes: (1) Petroleum Volatile Organic Compounds-defined in Analytical Guidance. (2) Sample at least once. (3) See Analytical
Guidance. (4) At tank removal. (3) Site speafic-may require investigation, may require cleanup.
Summary of Wyoming Cleanup Standards for Hydrocarbon Contaminated Groundwater
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Cleanup Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 524.2
5 Mg/1
any amount
>5Mg/l
5Mg/l
Ethylbenzene
EPA Method 524.2
5 Mg/1
any amount
>700Mg/l
700Mg/l
Toluene
EPA Method 524.2
5 Mg/1
any amount
>1000Mg/l
1000m g/1
Xylenes
EPA Method 524.2
5 Mg/1
any amount
>10.000Mg/l
10.000Mg/l
Leaded Gas
Total Lead
EPA Method 239.2/6010
5 Mg/1
any amount
>50pg/l
50n g/l
TPH
Modified 8015
4 Mg/1
any amount
>10mg/l
10mg/l
Waste Oil
BTEX same as
Gasoline
TPH
Modified 8015
4 ng/1
any amount
>IOmg/l
I0mg/1
Total Lead
EPA Method 239.2/6010
5 Mg/1
any amount
>50Mg/l
50m g/l
Total Cadmium
EPA Method 213.2/6010
1 Mg/1
any amount
>lMg/l
ing/l
Total Chromium
EPA Method 218.1/6010
50 Mg/1
any amount
> 100Mg/l
100m g/l
Treatment Facility Operators
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Return on Capitol (1st year)
$1,000,000
$522,000
S12
$25
208%
177%
(Estimated economics based on an average facility using existing equipment
and personnel, processing an average of 9,000 tons of soil per month.)
for more information call Mr. Crabtree at
Genesis Eco Systems Inc.
Integrating Science, Technology, and Compliance
3341 Fitzgerald Road, Suite D Rancho Cordova, CA 95742
(916) 638-5733 FAX (916) 638-1167
Write In 224 Deceml">Rr Soils 59
B-37
-------
Summary of Wyoming Clean-up Standards for Hydrocarbon Contaminated Soil
Product
Parameter/
Lab Test Protocol
Detection
Notification
Action
Clean-up Level
Constituent
& Number
Level
Level
Level
Gasoline
Benzene
EPA Method 8020
lmg/kg
any amount
•
Ethylbenzene
EPA Method 8020
.lmg/kg
any amount
*
«
Toluene
EPA Method 8020
lmg'kg
any amount
*
•
Xylenes
EPA Method 8020
¦ lmg/kg
any amount
*
¦
Leaded Gas
Total Lead
EPA Method 289.2/6010
5mg/kg
any amount
*
•
TPH
Modified 8015
4mg/kg
any amount
>30rng/l
30mg/l gw<50'
>l00mg/l
I00mg/1 gw>50*
Fuel Oils
BTEX same as
Gasoline
TPH
Modified 8015
4 mg/kg
any amount
>100mg/kg
lOOmg/kg
Lubricating Oil
BTEX and TPH
same as Fuel Oil
Waste OU
BTEX same as
Gasoline
TPH
Modified 80! 5
4 mg/kg
any amount
>i00mg/kg
lOOmg/kg
Total Lead
EPA Method 239.9/6010
5 mg/kg
any amount
"
•
Total Cadmium
EPA Method 213.1/6010
.5 mg/kg
any amount
•
•
Total Chromium
EPA Method 218.1/6010
.5 me/ka
anv amount
*
«
* Si us Specific. Nflttt Site Specific khI tenon/ cleanup J«ve Is for organic compound^ elements trt determined from CooUkU LeRoy Feusoer, Department of
*a cnviitmmenial faic/ ua/uporr-risk model contained in She WDEQ/ WQD techmcaJ guidance document. Procedures Environmental Quality 307*777-7096
for Establishing Environmental Resiocioon Standard* for Leaking Underground Storage Tank Remediation Action*.
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B-38
-------
Soil teachability,
from page 37
fine grained soils to adsorb significant quantities of
petroleum contaminants leaked to the environment.
• The effectiveness of natural mechanisms for
contaminant attenuation—biodegradation. dilution and
dispersion—which are active at many leaking t^k sites.
• Other site specific factors which may help limit the
spread of contamination from the sue—soil properties,
hydrogeologv, site capping, depth to groundwater—which
may help protect water resources.
In addition, the short term remediation of contaminated
soils to levels which were designed as water quality
standards, often low ppb levels, may be neither
technologically or economically feasible at many sites.
A better approach to the identification of cost-effective,
site-specific soil cleanup levels to protect water resources
may include the use of laboratory based contaminant
leachability tests. The EPA's TCLP (Toxicity Characteristic
Leaching Procedure) Method 1311 and the SPLP (Synthetic
Precipitation Leaching Procedure) Method 1312. are tools
which may be appropriate to evaluate contaminant
leachability from soils. (See EPA SW846 for testing
methods.) The TCLP is a waste classification procedure and
has provisions which make it appropriate for the evaluation
of wastes which contain volatile, semi-volatile and non-
volatile contaminants. In many respects, the SPLP is similar
to the TCLP. except the SPLP is designed to use simulated
rain water as the solvent during the leachability test.
The EPA procedures are designed to measure the
concentrations of contaminants in a leachate from a short
term (less than 24 hours) lab test. There are some technical
considerations that must be resolved before the results from
laboratory leachability testing may be used to identify site-
specific soil cleanup levels. Many of the technical issues
involve appropriate sampling of the contaminated soil mass
and integrating the results from the leachability tests with
known, site-specific conditions, such as site hydrogeology
and uses of groundwater resources. In some states, such as
California, the corrective action regulations allow
responsible parties at some contaminated underground
storage tank sites to propose appropriate cleanup levels
based on results of an impact assessment. (California Code
of Regulations, Division 3, Chapter 16. Article II.) In many
cases, it may be appropriate for the responsible party to
propose soil cleanup levels which are based on the results of
leachability testing for the contaminants of concern. A
technically sound proposal for establishing soil cleanup
levels based on leachability testing merits serious
consideration and possible acceptance by all parties—
property owners, financial institutions and regulatory
agencies involved in corrective action at petroleum
contaminated sites. Appropriate and effective use of results
from soil leachability testing could be helpful in
establishing soil cleanup levels which are cost-effective and
protective of long term groundwater quality !
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December 1994 Soils 61
B-39
-------
APPENDIX C
EXAMPLE CALCULATIONS
CONTENTS
Page
Emissions from Excavation (Section 3) C-2
Emissions from Thermal Desorption (Section 4) C-4
Emissions from Soil Vapor Extraction (Section 5) C-5
Emissions from In-situ Biodegradation (Section 6) C-7
Emissions from Ex-situ Biodegradation (Section 7) C-8
Emissions from Thermal Destruction (Section 8) C-9
C-l
-------
SAMPLE CALCULATIONS FOR EXCAVATION
(Section 3)
A site has approximately 10,000 m3 of soil contaminated with chloroform, 1,1,1-
trichloroethane, and trichloroethylene in concentrations of 0.1, 10, and 1.0 ppm (/xg/g),
respectively. The distribution of the contamination within the soil is not accurately known.
The soil's bulk density averages 1.5 g/cm3. Removal of all contaminants is expected to take
20 days of continual operation (1.728xl06 sec).
First estimate the total emissions potential for the site using Equations 3-1 and 3-2 from
page 3-12:
Mchioro = (10,000 m3)(0.1 /ig/g)(1.5 g/cm3)(l g//xg cm3/m3) = 1,500 g
ERchioro = M/tsv = 1,500 g / 1.728xl06 sec = 8.7 x 10~4 g/sec;
ERtce = (10,000)(1.0)(1.5)(1) / (1.728xl06) = 8.7 x 10"3 g/sec;
ERtca = (10,000)(10)(1.5)(1) / (1.728xl06) = 8.7 x 10"2 g/sec.
These represent the average long-term emission rate if 100% of the contamination were
volatilized and stripped from the soil.
The calculations using the excavation model and the default values given in the report
are shown below for chloroform. First, the excavation rate is calculated from the known
information: Q = 10,000 m3 / 1.73xl06 sec = 0.0058 m3/sec. Next, the concentration must
be converted from ppmw to g/cm3 using Equation 3-6:
Cs = (0.1 /ig/g)(1.5 g/cm3)(10"6 glfig) =1.5xl0"7 g/cm3
Now, the pore space and diffusion emissions can be calculated using Equations 3-3 and 3-4
from page 3-12:
ERPS = (35)(100)(106)(0.44)(0.0058)(0.33) / (62,361)(298) = 0.16 g/sec
ERdiff =(1.5x10"7)(10,000)(290) / (0.44 / 0.613 * 0.15) + (3.14 * 60 / 0.0269 * 0.613)05
= 0.4350 / 4.785 + (11,425)°5 = 0.0039 g/sec.
The value, ERPS, must be compared to the total mass of contamination present in the soil using
Equation 3-7 on page 3-14:
ERPS * tsv= (0.16 g/sec)(1.728xl06 sec) = 2.8xl05 g
This value (2.8xl05 g) is > 0.33 M (0.33 * 1,500 = 500 g), so Equation 3-4 is giving a value
that is far too conservative. Therefore, ERPS should be calculated using Equation 3-8:
C-2
-------
EMISSIONS FROM EXCAVATION
(Section 3)
(Continued)
ERPS = M * 0.33/tsv = (1,500 g)(0.33) / (1.728xl06 sec) =2.9xl0"4 g/sec
The total emission rate of chloroform is thus:
ER - ERPS + ERDIFF = 0.00029 + 0.0039 = 0.0042 g/sec
This is somewhat greater than the 8.7 x 10"4 g/s rate found from Equation 3-1. Equation 3-1,
however, predicts the average emission rate if all contamination in the soil were to volatilize.
However, 100% of the VOCs will not volatilize and be stripped from the soil, so it is
reasonable that the emission rate estimate exceeds the average emission potential.
More accurate estimates could be obtained using compound-specific and sitc-specific
input values rather than the default values. For example, the vapor pressure of chloroform is
208 mm Hg versus the default value of 35 mm Hg, and the molecular weight of chloroform is
119.38 g/mol versus the default value of 100 g/mol.
C-3
-------
SAMPLE CALCULATIONS FOR THERMAL DESORPTION
(Section 4)
A site to be remediated contains soil with the following levels of contamination:
Benzene
1.0/ig/g
Toluene
24.0 ng/g
Xylene
110.0/ig/g
Ethyl Benzene
20.0 fig/g
The full-scale desorption unit has a capacity of 7.5 tons per hour, and the percent volatilized is
99.00 for the other compounds of interest (i.e., equals the default value for BTEX). A fume
incinerator with a 98% control efficiency will be used. Note that 1 jig/g = 1 mg/kg.
To find the emission rate using the equation on page 4-18, the first thing to do is to get
the input values into the proper units. The mass treatment rate of 7.5 tons/hr = 6820 kg/hr.
Thus:
EBenz = (1.0 mg/kg / 1,000 mg/g)(6,820 kg/hr)(99.00/100)(l-98/100) = 0.135 g/hr
= (0.135 g/hr) / (3,600 sec/hr) = 3.8x105 g/sec;
E,.0l = (24/1,000)(6,820)(99.00/100)( 1-98/100) =3.24 g/hr = 9.0X10"4 g/sec;
EXyl = (110/1,000)(6,820)(99.00/100)(1-98/100) =14.8 g/hr = 4.1xl0"3 g/sec; and
EahyiBenz = (20/1,000)(6,820)(99.00/100)( 1 -98/100) = 2.70 g/hr = 7.5xl0"4 g/sec.
C-4
-------
SAMPLE CALCULATIONS FOR SOIL VAPOR EXTRACTION
(Section 5)
A contaminated site to be remediated contains soil contaminated to the following
extent:
Benzene:
100 ppm
(100 Mg/g)
Toluene:
300 ppm
(300 fig/g)
Carbon Tetrachloride:
50 ppb
(0.050 fig/g)
Naphthalene:
800 ppb
(0.800 ng/g)
The site is a 200 m2 field behind a factory. The water table is 30 m below the surface at this
location. The entire volume of soil down to the water table is assumed to be contaminated. A
vendor has quoted an estimate of five months to complete the clcan-up. No physical data on
the type of soil is known.
The uncontrolled stack emission rates are calculated with the equation on page 5-12.
Use of this equation requires knowledge of the vapor extraction rate; for this scenario, a
medium-sized SVE system of 85 m3/min may be assumed. One further needs the
concentration of the extracted vapors. The saturated vapor concentrations can be calculated
using the equation on page 5-17 or can be obtained from the following reference: Eklund and
Albert, 1993*. The saturated vapor concentrations given in this reference are:
benzene
4.00 x 108 /zg/m3
toluene
1.49 x 108 ng/m3
carbon tetrachloride
9.34 x 10Vg/m3
naphthalene
1.58 x 105 fig/m3
These values all assume that the soil is saturated with each contaminant. Given the low
concentrations present in the soil, the extracted vapor will actually be well below saturation
and the estimates will be quite conservative.
Putting the values given above into a mass balance equation for air emissions yields:
ERbenz - (4.00xl08 /ig/m3)(10"6 g/^g)(85 m3/min) / (60 sec/min) = 570 g/sec
ERtohl = (1,49xl08)(10"6)(85) / (60) - 210 g/sec
ERCCI4 = (9.34xl08) (10 6)(85) / (60) = 1,300 g/sec
ERraph = (1.58xl05)(10"6)(85) / (60) - 0.22 g/sec.
C-5
-------
* Eklund, B. and C. Albert. Models for Estimating Air Emission Rates from Superfund
Remedial Actions. EPA-451/R-93-001 (NTIS PB93-186807). March 1993.
C-6
-------
EMISSIONS FROM IN-SITU BIOTREATMENT SYSTEMS
(Section 6)
Assume the same scenario as given above for soil vapor extraction: A contaminated
site to be remediated contains soil contaminated to the following extent:
Benzene:
100 ppm
(100 fJLglg)
Toluene:
300 ppm
(300 ng/g)
Carbon Tetrachloride:
50 ppb
(0.050 Mg/g)
Naphthalene:
800 ppb
(0.800 jig/g)
The site is a 200 m2 field behind a factory. The water table is 30 m below the surface at this
location. The entire volume of soil down to the water table is assumed to be contaminated. A
vendor has quoted an estimate of five months to complete the clean-up. No physical data on
the type of soil is known. During a pilot-scale test of the suitability of bioventing, the off-gas
was found to have a concentration of roughly lxlO4 /xg/m3 for benzene and toluene, and IxlO5
/xg/m3 for carbon tetrachloride. No naphthalene was detected (DL = 1x10"Vg/m3).
The extraction rate for the soil venting is calculated using the 2nd equation given on
page 6-8. The volume of contaminated soil is 200 m2 * 30 m = 6,000 m3. The air filled
porosity can be assumed to be 0.44 (see Table 3-4). Using these input values, the extraction
rate can be calculated:
Q (m3/min) = (1.0/1440 min)(6,000 m3)(0.44) = 1.83 m3/min
Using the available information, the emissions can be calculated as follows:
ERbcnz = (lxlO4 jag/m3)(10"6 g//xg)(1.83 m3/min) / (60 sec/min) = 3.05xl0"4 g/sec
ERlo;u = (lx 104)( 106)(1.83) / (60) = 3.05x101 g/sec
ERccm = (lx 105)( 10"6)( 1.83) / (60) = 3.05xl0"3 g/sec
ERnaph = (1x10 6)(10"6)(1.83) / (60) = < lxlO"12 g/sec.
C-7
-------
EMISSIONS FROM EX-SITU BIOTREATMENT SYSTEMS
(Section 7)
Consider a site with a contaminated lagoon. The lagoon holds 500,000 L with an area
of 100 m2. The sludge beneath it is contaminated to a depth of about 3 m. The contaminants
present in the sediments are benzene and chlorobenzene. The overlying water is considered to
be uncontaminated. The concentrations are 10 jug/g benzene and 20 /xg/g chlorobenzene in the
sludge (jug/g = mg/kg). The bulk density of the sediments was measured and is 2.0 g/cm3.
Therefore, the 300 m3 of contaminated sludge would weigh 600,000 kg. A batch biotreatment
system will be used with a treatment rate of 2,000 kg batches treated for one day (86,400 sec)
each. The Henry's Law constants for both compounds are in the 10~3 range, and V is assumed
to be 20%.
Using the equation for batch treatment, the emission rates are estimated to be:
ERBenz = (10 mg/kg /1,000 mg/g)(2,000 kg)(20/100) / 86,400 sec = 4.6xl0'5 g/sec; and
ERchl = (20/l,000)(2,000)(20/100) / 86,400 = 9.3xlO"5 g/sec.
C-8
-------
EMISSIONS FROM THERMAL DESTRUCTION
(Section 8)
Consider the following remediation scenario. The soil in a hypothetical site has been
tested, and it contains:
PCBs
2%
1,2,4-Trichlorobenzene
2800 ppb
The contractor will use a rotary kiln incinerator with a feed rate of 6000 kg/hr. An ultimate
analysis of the soil shows it to contain: 1.0% S, 0.5% CI, 0.15% Ba, and 0.08% Pb. The
device burns propane, which is assumed to not contribute measurably to the emissions of any
of the above compounds. The exit gas flow rate is not known. A scrubber will be used to
control emissions of acid gases, and the vendor indicates that control efficiencies of 95% for
S02 and 99% for HC1 can readily be achieved.
First, find the concentration of organic contaminants in the waste feed in the specified
units of g/kg (note that 1% = 10,000 ppm, 1,000 ppb = 1 ppm, and ppm =/xg/g):
Cpcb =(20,000 Mg/g)(10"6 g//xg)( 1,000 g/kg) = 20 g/kg;
CrCB = (2.8)(10"6)(1,000) = 0.0025 g/kg.
Next calculate the organic emissions using the 1st equation on page 8-13 and a DRE for PCBs
of 99.9999%, and a DRE for TCB of 99.99%.
ERpcb = (1 - 99.9999/100)(6,000 kg/hr)(20 g/kg) = 0.12 g/hr
= (0.12 g/hr) / (3,600 sec/hr) = 3.3 x 10 5 g/s; and
ERTCB = (1 - 99.99/100)(6,000)(0.0025) = 0.0015 g/hr = 4.2 x 10'7 g/s.
The uncontrolled metals emission rates are found using the second equation on page 8-
13 (the controlled emissions may be significantly lower). First, find the concentration of
contaminants in the waste feed in the specified units of g/kg (note that 1% = 10,000 ppm and
ppm =n g/g):
CBa = (1,500 Mg/gXlO"6 g/Mg)O,000 g/kg) = 1.5 g/kg; and
CPb - (800)(10-6)( 1,000)= 0.8 kg/hr.
The partitioning factor for both metals is 100% (from EPA, 1989); that is, the metals can be
expected to be present in the gas-phase. The emission rates are then:
Eua =(1.5 g/kg)(6,000 kg/hr)(100/100) = 9,000 g/hr
= (9,000 g/hr) / (3,600 sec/hr) = 2.5 g/sec; and
EPb = (0.8)(6,000)(100/100) = 4,800 g/hr = 1.3 g/sec
C-9
-------
EMISSIONS FROM THERMAL DESTRUCTION
(Section 8)
(Continued)
For acid gases, again the first step is to convert the concentration of the element in the
waste to the proper units:
Cci = (5,000 Mg/g)(106 g//ig)(l,000 g/kg) = 5.0 g/kg; and
Cs = (10,000)(10"6)( 1,000) = lOg/kg.
Their stoichiometric ratios are 1.028 (g HC1 / g CI) for HC1 and 1.998 (g S02/ g S) for S02:
EHC1 =(5 g/kg)( 1.028)(6,000 kg/hr)( 1-99/100) = 308 g/hr
= (308 g/hr) / (3,600 sec/hr) = 0.086 g/sec; and
Es02 = (10)(1.998)(6,000)(1-95/100) = 5,990 g/hr = 1.7 g/sec.
C-10
-------
APPENDIX D
DERIVATION OF VOC EMISSION MODEL FOR EXCAVATION
D-l
-------
APPENDIX D
MODEL DERIVATION
Derivation of a Screening Model for
VOC Emissions From Soils Handling Activities
Bart Eklund
Radian Corporation
8501 N. Mopac Blvd.
Austin, TX 78759
March 11, 1992
D-2
-------
Screening Model for VOC Emissions from Soils Handling Activities
APPENDIX A - MODEL DERIVATION
A.1 INTRODUCTION
Background information about the modeling problem is presented in this
appendix followed by a presentation of an emission model for estimating VOC emissions
from the excavation of contaminated soil. A simplified version of the model is
developed, then the models are evaluated.
Objective
Develop simple predictive model for estimating VOC emissions from soils
handling activities, such as excavation.
Intended Use
The model will be used for assessing potential emissions during
remediation of Superfund sites. At a minimum, the model should provide an emission
factor to estimate emissions per unit time or unit operation. Ideally, it should also be
appropriate for evaluating the effect of different remediation scenarios, e.g. starting
waste concentrations, excavation rates, and control efficiencies.
Requirements
1. Model should be conservative, since the data may be used in some
cases for health risk assessment.
2. Model should require as few input parameters as is feasible for ease
of use.
Assumptions
1. During excavation, the surface area of soil in contact with the
atmosphere is greatly increased. This results in up to one-third of
the soil gas being released to the atmosphere. In dry soils
containing very low levels of VOCs, most of the contaminants are
present in the soil pore spaces, thus the percentage of the VOCs
emitted is relatively high.
2. Once the soil has been dumped into place, the organic liquid to soil
gas equilibrium is quickly re-established. The emissions can be
estimated by a modification of the RTI landtreatment model.1
V 5-14 and 5-15 of EPA-450/3-87-026, Review Draft, November 1989.
D-3
-------
.3. The freshly dumped soil is soon covered by relatively deep layers of
subsequently excavated soil. These layers of soil result in longer-
term emissions from the deeper layers being diffusion controlled,
i.e., low. Therefore, the significant period for emissions is during
excavation and the first six minutes or so afterwards. Subsequent
(i.e. t > 6 min) emissions from this material are assumed to be zero.
4. The total exposed surface area of contaminated soil is assumed to
remain constant. New material is exposed at the same rate that
previously exposed material is covered.
5. The emissions from the pit are approximately equivalent to the
emissions from the pile of excavated soil. The emissions from the
soil in the backhoe bucket are negligible.
6. Wet soils are assumed to have relatively low levels of VOC
emissions, even if the soil VOC concentrations are high. Wet soils
may have little air-filled porosity and therefore the rate of diffusion
of VOCs through wet soils is relatively low.
Possible Excavation Scenarios
Two general scenarios are followed during excavations at waste sites.
1. Soil is excavated using a backhoe and placed into a short-term
storage pile. The soil is later picked up from the pile and dumped
directly into transport vehicles (e.g. trucks or railcars) that are
subsequently covered to minimize further emissions. Overall, each
m3 of soil is excavated and dumped two times.
2. Soil is excavated using a backhoe and placed into a temporary
storage pile. The soil is moved from the pile using a front-end
loader (and/or backhoe) to a staging area where a large storage pile
is established. The pile is typically covered to minimize leaching
and air emissions. The soil is eventually re-excavated and dumped
into transport vehicles (e.g. trucks or railcars) that are subsequently
covered to minimize further emissions. Alternatively, the soil may
be re-excavated and fed to an on-site treatment system. Overall,
each m3 of soil is excavated and dumped three times.
It is rarely feasible or efficient to dig soil and immediately transfer the soil directly to
transport vehicles or treatment systems. The excavation scenario and the emission
equations shown below are designed to predict the emissions from a single soil handling
event. To predict the total emissions from excavation, the equations must be
sequentially applied to each event where the soil is handled (i.e., two or three times in
most cases). The values for certain input parameters to the equations, such as the
concentration of the contaminant in the soil and the bulk density of the soil, will be
D-4
-------
altered by the act of excavation and a separate (different) value will be required for
these parameters when modeling each soil handling event of the overall excavation
process.
Details of Excavation Scenario
Soil is excavated for 50 min/hour2. Each scoop of soil contains 2 m3 of
material and has dimensions of lm x 2m x lm. The cycle time is 40 seconds3, so 75
scoops are moved per hour (= 150 m3 of soil moved per hour). The excavation pit, after
one hour of operation, has dimensions of 10m x 15m x lm.
Each scoop of dumped soil is assumed to maintain its 1x2x1 dimensions, so
that the pile of dumped soil is equivalent to a series of stacked blocks. After one hour, a
pile 5m x 10m x 3m high is established. The total exposed surface area of the pile is 140
m2 and the bottom of the pit has another 150 m2 of exposed area (the sides of the
excavation pit are assumed to be clean overburden). The exposed surface areas are
assumed to remain constant during further hours of operation with any additional area
being covered with some type of impermeable cover that acts as a barrier to further
emissions.
A.2 DERIVATION OF EMISSION MODELS
The models are based on adding the emissions resulting from the release
of soil-gas (pore space gas) to the atmosphere when excavation soil is dumped onto a
storage pile to the emissions resulting from diffusion from contaminated soil present in
the excavation pit and in the storage pile. A discussion of the input parameters and
typical input values are given in Sections A.4 and A.5. Limitations of the models are
also given in those sections.
Pore-Space Gas Model
The general form of the equation used to estimate the emission rate from
the pore space gas for any given compound is the ideal gas law:
P V = nR T (Eq. A-l)
where: P = Vapor pressure of compound i (mm Hg);
V = Volume (cm3);
n • = Number of moles of gas;
2Page 8-35 of the Excavation Handbook by H.K. Church (MCGraw-Hill, 1981) states
that excavation equipment can be assumed to be in use for 30 to 50 minutes per hour.
3Page 12-38, op cit, gives a cycle time of 0.67 minutes for a 25 foot hoist distance and
a 90° angle of swing return.
D-5
-------
R
T
Gas constant; and
Temperature (°K).
The mass of contaminants present in the pore space of soil can be determined as follows.
First substitute MPS/MW for n and then solve for MPS:
M
PS
P V MW
R T
(Eq. A-2)
where:
Mps
MW
Mass of pore space contaminants (g); and
Molecular weight of species i (g/g-mole).
Then substitute soil volume and air-filled porosity terms for V to account for the volume
of air within a given volume of soil. Air-filled porosity is the fraction of the total soil
volume that is air. A factor of 106 to convert from cm3 to m3 is also needed:
M,
PS
P MW
RT
(106)(E.)(Sv)
(Eq. A-3)
where:
Ea
106
Sv
R
Air-filled porosity (dimensionless);
Conversion factor (cm3/m3);
Volume of soil moved (m3); and
Gas constant, 62,361 (mm Hg - cm3/g-mole °K).
To derive an emission rate, Equation A-3 must be modified to account for
the rate at which soil is being moved and to account for the percentage of soil gas that is
released or exchanged with the atmosphere:
ER,
PS
P MW
RT
(10s)(E,)(Q)(ExC)
(Eq. A-4)
where: ERPS = Average emission rate from the pore space gas (g/sec);
ExC = Soil gas to atmosphere exchange constant (%/100); and
Q = Excavation rate (m3/sec).
The excavation rate term, Q, is equal to Sv divided by the total time period
in seconds over which the given volume of soil is being moved. Equation A-4 assumes
that the instantaneous emission rate is equivalent throughout the excavation cycle,
whereas the emissions from each scoop of soil are probably due primarily to two
emission puffs: one when the backhoe bucket enters the soil and initially disturbs the soil
and the second, larger puff, when the bucket dumps the soil onto the storage pile.
Equation A-4 also assumes that the pore space is saturated with the contaminant vapor.
D-6
-------
Diffusion Model
The general form of the equation used to estimate the emission rate from
the contaminated soil in the excavation pit and in the storage pile is the RTI
landtreatment model:
M0
EF = —-
1
E' )'
' K t
lK^ kJ
k KJ
(Eq. A-5)
-t/tb
where:
EF
M„
K
eq
De
t
t„
Emission flux through the soil at some time t (g/cm2-sec);
Initial loading of contaminant in soil (g/cm2);
Depth to which contaminant is mixed in soil (cm);
Weight fraction of VOC in air space (dimensionless);
Gas-phase mass transfer coefficient (cm/sec);
Effective diffusivity (cm2/sec);
Time since start of excavation of soil of interest (sec); and
Time constant for biological decay of contaminant i (sec).
Several modifications to the model were made to make it applicable to
excavation. First, the biological expoential decay term (e',/lb) was set equal to one since
the timeframes of interest are very short. Second, the initial loading term (M0) and the
depth to which the waste is mixed term (1) were combined into a waste loading term,
designated C. Third, a factor of 10,000 was added to convert the emission units from
mass per cm2 to mass per m2. Fourth, a term was added to account for the surface area
of the emitting soil. The resulting equation is:
ER,
(C)(10,000)
Diff
Tt t
[SA]
(Eq. A-6)
vDe Ke,,
where:
ER
Diff
c
10,000
SA
Instantaneous emission rate from diffusion through the soil
(g/sec);
Soil concentration of species of interest (g/cm3);
Conversion factor (cm2/m2); and
Surface area of emission source (m2).
D-7
-------
.The surface area term, SA, includes the area of the exposed contaminated
soil for both the excavation pit and the storage pile. It is assumed that the surface area
of the emission source remains constant, i.e., excavation was already underway before the
particular soil being modeled was handled and excavated soil is moved off-site or
covered to reduce emissions at the same rate that new soil is being uncovered and
excavated. To model the case where no contaminanted soil is initially exposed, the
surface area term in Equation A-6 can be divided by a factor of two to yield an average
amount of exposed surface area.
A.3 EMISSION MODELS
The overall emission rate equation is formed by adding Equations A-4 and
A-6. Note that the timeframes of the two equations as shown are not equivalent.
Equation A-4 describes the emissions over the course of excavating and dumping one
scoop of soil (40 seconds in the assumed scenario), while Equation A-6 gives an
instantaneous emission rate at some time t since the contaminated material was first
exposed to the air. An average value for t is discussed in Section A.4 and the timeframe
of the two models are reconciled so that they yield an average emission rate.
The general form of the emission models for estimating an "average"
emission rate for the excavation of contaminated soil is given as Equation A-7 and a
worst-case emission rate is given as Equation A-8. It is a simple matter to modify either
of these equations to calculate an emission flux (i.e., rate per area) or total emissions for
a given period of time.
Emission Rate
An emission rate in g/sec for excavation was derived in the previous
section and is:
ER =
P MW
RT
(io6)(Ej(Q)(ExC) + (C)( 10,000)— (SA)
(Eq. A-7)
( E, 1
( \
7t t
[ k=aJ
I De K J
Worst-Case Emission Rates
The worst-case (i.e., maximum) instantaneous emission rate, ER^x, for
contaminated soil occurs when the exposed surface area is at a maximum and
immediately after a bucket load of soil is dumped onto the storage pile. This emission
rate can be approximated by considering the case where a pure chemical is exposed to
the atmosphere. This emission rate can be determined from Equation A-6 (there is no
need to consider pore space gas concentrations and diffusion since the pure chemical is
already exposed to the atmosphere). Set the time term, t, equal to zero and replace the
Kcq term with the equivalent expression: P*MW*Ea/R*T*C. Equation A-6 then reduces
to:
D-8
-------
ER =
MAX
(k )(P)(MW)(SA)( 10,000) (Eq" A"8)
RT
A.4 SIMPLIFIED EMISSION MODELS
The first half of Equation A-7 is simplified first, followed by simplification
of the second half of Equation A-7.
Simplified Pore-Space Gas Model
The first half of Equation A-7 can be simplified as follows. Assume the
following:
R = 62,361;
MW = 100;
T = 298;
ExC4 = 0.33.
Substituting these values into the first half of Equation A-7 yields an emission rate for
pore space gas, ERPS, of:
(Eq. A-9)
P MW^VPUnwPvn (P)(Ea)(Q)(100)(106)(0.33)
ERps = (10 )(E )(Q)(ExC) =
RT (62,361 )(298)
(Eq. A-10)
ERps ~
5.4 g/m3
> mm Hg ,
~ P * E, « Q « 0.33
4 Assume ExC = 0.33 for dry, sandy soils and ExC
a high clay content.
D-9
= 0.10 for wet soils or those with
-------
Vapor pressures for most VOCs of interest are available in tabluated
physical constants in Appendix B. These values are for 25°C, but P can be estimated at
other temperatures5. According to SEAMs, the air-filled porosity (Ea) can be assumed
to be:
Ea
Soil Conditions
0.35
Wet, or compacted soil
0.55
Dry, uncompacted soil
Ea can be assumed to be 0.05 for sludges, tarry wastes, and saturated soils.
Alternatively, Ea can be calculated as follows:
Ea= 1
B - (B)(Mfrac)
(Eq. A-ll)
where: B = Bulk density of soil (g/cm3);
Mfrac = Moisture fraction in soil (VVt.% Moisture/100); and
p = Particle density (g/cm3).
Default values are as follows. Bulk density (B) usually is in the range of
1.0 to 2.0 and can be assumed to be about 1.5 for uncompacted soils prior to excavation
After excavation, the bulk density is lower and a value of 1.2 may be assumed. Particle
density (p) is typically about 2.65 ± 5% for soils. These default values yield an Ea for
dry soil of 0.43 before excavation and 0.55 after excavation.
5Vapor pressure can be roughly estimated at temperatures other than 25°C by the
following equation:
-21Tb
<
1 1
1.987
Hi
£j]
(Eq. A-12)
where: P = Vapor pressure of compound i at temperature T (mmHg);
P° = Vapor pressure of compound i at temperature T0 (mmHg);
Tb = Normal boiling point of compound i (°K);
T = Temperature (°K);
T0 = Reference Temperature (°K) - Usually 298°K;
1.987 = Gas constant (cal/g-mol °K); and
21 = Heat of vaporization constant (cal/g-mol °K).
D-10
-------
Using the SEAMS value for Ea (0.55), Equation A-10 for dry soil then
reduces down to:
ERps = P * Q * 0.98 g/mmHg-m3 (Eq" A"13)
Equation A-13 is the simple screening model. If desired, it can be further
reduced. Using the excavation scenario described above, Q can be assumed to be
150 m3/3600 sec. Equation A-13 for dry soil then reduces down to:
ERPS = (0.04 g/mm Hg)*P (Eq. A-14)
Simplified Landtreatment Model
The second half of Equation A-7 can be simplified as follows. The
following equations6'7 can be used to describe the terms Keq and De, which appear in
Equation A-7:
P MW E,
-------
. Keq represents the relative saturation of the soil-gas with respect to a given
compound and cannot realistically exceed 1. Calculated values of Ke using Equation
A-15 will exceed 1 if the soil-gas is below saturation with respect to tliat compound. If
the output of Equation A-15 is Keq > 1, then a value of Keq = 1 should be used in all .
equations having a Keq term. Alternatively, Keq could be determined by field
measurements of the pore space concentration in the soil ratioed to the total
concentration of the contaminant in the soil.
Er can be calculated by Equation A-11 if the moisture fraction is set to
zero.
Assume the following:
R
62,361;
MW =
100;
T
298;
Da -
0.1;
Ea =
0.55;
=
0.625;
Substitute these values into Equations A-15 and A-16 to yield:
(Eq. A-17)
Kcq =
C 332,200
De = 0.035 (Eq. A-18)
The second half of Equation A-7 can then be simplified by inserting
Equations A-17 and A-18, and by assuming that Ea = 0.55 and that kg = 0.15. Equation
A-7 then reduces to:
ER
(C)( 10,000)
(Eq. A-19)
Diff
1.22x10s -
p
\ I
(SA)
2.98x10
7 C t
Equation A-19 provides an instantaneous emission rate at time = t. It is
assumed that emissions from freshly excavated soil are significant for a period of 360
seconds, after which the soil is covered by subsequent layers of excavated material. The
emission rate versus time over this 360 second period for a given scoop of soil will
generally exhibit an exponential decay. The exact shape of this decay curve will vary as
D-12
-------
the input parameters such as vapor pressure and air-filled porosity vary. Therefore, it is
necessary to determine at what time t the instantaneous emission rate approximates the
average emission rate over the 360 second period. This can be done by calculating the
instantaneous emission rates at t = 0 second, t = 15 seconds, t = 30 seconds, and so on.
The emission rate is calculated for every 15 second period up to t = 360 and the results
plotted. The average emission rate is calculated by summing the instantaneous emission
rates and dividing the sum by the number of data points (in this example, 24). The value
for the average emission rate is then found on the plot of emission rate versus time, and
the corresponding time found on the x-axis. This time t is then used in Equation A-19.
For the typical case, the instantaneous rate at t = 60 seconds is a good approximation of
the overall emission rate for the first 360 seconds. Using this value Equation A-19 yields
the simple screening equation:
ERd,„ . , W000> (SA)
1.22 x 106 —
1.79 x 109 -
2
Equation A-20 assumes that the emission flux arising from diffusion is equal for both the
excavation pit and the excavated soil in the storage pile. Equation A-20 will overpredict
emissions if Keq> 1. P at temperatures other than 25°C can be estimated using Equation
A-12. From the excavation scenario described earlier, SA can be assumed to be 290 m2.
Assuming a typical bulk density of undisturbed soil, C can be modified to a
weight basis as follows:
1 3 (Eq.A-21)
c = c * -LEL . io6 Mg/g
1.5 g
where: C' = Concentration of species in soil (ug/g).
The overall emission rate is determined by adding Equations A-13 and
A-20. This estimated value should be checked to see whether or not it exceeds the total
mass of contaminants present in the soil that is moved, which is equal to the theoretical
maximum emissions (not considering emissions from the un-excavated soil in the pit).
To do this, the emission rate should be multiplied by 3,600 seconds to get the total
emissions over a reasonably long period of time, one hour. The mass of contaminants
present in the soil can be determined by:
OpoT = C * Sv * 106 cm3/m3 (Eq. A-22)
where: Cj-ot = Total starting mass of contaminant in excavated soil (g).
Equations A-4 and A-13 are based on the assumption that the soil pore gas
is saturated with the compound of interest. If this is not the case, then Equations A-4 or
A-13 may overpredict the emission rate.. The output from Equations A-4 or A-13 should
be multiplied by the duration of excavation and compared to the total mass of
D-13
-------
contaminants present in the soil. If Equations A-4 or A-13 gives a value that exceeds
one-third of CroT, then they should be replaced with the following equation:
ERps = Cjqt * O'-^Asv (Eq. A-23)
where: t^ = Time to excavate a given volume of soil (sec).
A.5 MODEL EVALUATION
The emission model was evaluated to determine the sensitivity of the
model to various input parameters. All the independent variables in Equation A-7 are
listed in Table A-l. For each variable a typical value is given along with the range of
values likely to be encountered at Superfund site excavations. The uncertainty associated
with measuring each variable is also estimated in Table A-l. The range of physical
properties was based on n-butane being the lightest VOC likely to be encountered at a
site and naphthalene being the heaviest compound likely to be of concern. Typical
physical property values were based on C6 to C8 compounds (e.g. benzene to xylene).
The soil volume term was kept constant to show the variability in surface area for a
given volume of soil. The gas-phase mass transfer coefficient (kg) was estimated using
the correlations given with the RTI landtreatment model and the following input values:
Parameter
Units
Minimum
Value
Maximum
Value
Typical Value
Wind Speed
m/sec
1.0
4.47
2.0
Viscosity of air
g/cm-sec
1.81x10"
Density of air
g/cm3
1.2xl0'3
Diffusity in air
cm2/sec
0.25
0.059 0.1
Diameter of excavation
m
24
The minimum and maximum values for the independent input parameters
from Table A-l were combined to generate a best-case and worst-case set of emission
scenarios. These are shown in Table A-2 along with the case using the typical input
parameters. As seen in Table A-2, the three cases shown differ greatly in the estimated
average emission rate.
To identify which parameters had the greatest effect on the overall
emissions, a set of calculations were performed using the base or typical case as the
starting point. The effect of each parameter was examined by substituting the minimum
and maximum value for each into the base case conditions. The results of this first-order
sensitivity analysis are shown in Table A-3. The two independent variables having the
largest effect on the overall emission rate are the starting concentration of the
contaminant in the soil and the vapor pressure of the contaminant. Note that
temperature has a small effect, but that emissions are inversely proportional to
temperature. This is, of course, contrary to the overall effect of temperature on
emissions: emissions increase as temperature increases. This seeming anomaly is due to
D-14
-------
Table A-l.
Input Parameters for Emission Equations
Equation Parameter
Units
Typical Input Values
Typical Uncertainty
(±%)
Comments
Minimum
Maximum
Typical
IndeDendent Variables
Concentration
ug/Kg (ppbw)
50
5,000,000
100,000
50
Bulk Density
g/cm3 (dry)
1.0
2.0
1.35
10
Moisture
%
5.0
25
10
5
Particle Density
g/cm3
2.55
2.8
2.65
5
Temperature
K
273
313
298
2
Da
cm2/sec
0.059
0.25
0.1
25
Varies w/temperature
P
mm Hg
0.053
1820
35
300
Varies w/temperature
MW
g/gmol
41
166
100
1
R
mm Hg-cm3/gmol-K
62361
62361
62361
1
pi
--
3.14
3.14
3.14
1
kg
cm/sec
0.062
0.52
0.15
25
t
sec
60
60
60
25
Q
m3/sec
0.042
0.042
0.042
30
Surface Area
m2
290
435
290
50
Exchange Constant
%
1
50
33
200
Dependent Variables
C
g/cm3
5.00x10®
0.010
1.35x10^
Ea
vol/vol
0.588
0.107
0.440
Et
vol/vol
0.608
0.286
0.491
De
cm2/sec
0.0273
0.0018
0.0296
Keq
g/g
1.50
0.166
0.613
Keq
g/g (max)
1
Keq cannot exceed one
-------
Table A-2.
Emission Scenarios
Typical Input Values
Emission Scenarios
Parameter
Units
Minimum
Maximum
Typical
Best Case
Worst Case
Typical Case
Concentration
ug/Kg (ppbw)
50
5,000,000
100,000
50
5000000
1000
Bulk Density
g/cm3 (dry)
1.0
2.0
1.35
2.0
1.0
1.35
Moisture
%
5.0
25
10
25
5.0
10
Particle Density
g/cm3
2.55
2.8
2.65
2.55
2.8
2.65
Temperature
K
273
313
298
273
313
298
C
g/cm3
5.00x 10 8
1.00x10 2
1.35x10"
1.00x10 7
5.00x 10 3
1.35x10"
Ea
vol/vol
0.020
0.625
0.440
Et
vol/vol
0.216
0.643
0.491
Da
cm2/sec
0.059
0.25
0.1
0.059
0.25
0.1
P
mm Hg
0.053
1820
35
0.053
1820
35
MW
g/gmol
41
166
100
166
41
100
R
mm Hg-cm3/gmol-K
62361
62361
62361
62361
62361
62361
Pi
--
3.14
3.14
3.14
3.14
3.14
3.14
Kg
cm/sec
0.062
0.52
0.15
0.062
0.52
0.15
De
cm2/sec
3 x 10"6
0.1265
0.0269
Keq
g/g
0.101
0.478
0.613
Keq
g/g (max)
t
sec
60
60
60
60
60
60
Excavation Rate
m3/sec
0.042
0.042
0.042
0.042
0.042
0.042
Surface Area
m2
290
435
290
290
435
290
Exchange Constant
%
1
50
33
1
50
33
Emission Rate
g/sec
1.51 x 10 5
422
4.65
Notes: 1. Use Keq(max) if Keq is >1.
-------
Table A-3.
Results of Sensitivity Analysis
Equation Parameter
Units
Typical Input Values
Change in Emission vs Base Case
Minimum
Maximum
Typical
Minimum Value (± %)
Maximum Value (± %)
IndeDendent Variables
Concentration
ug/Kg (ppbw)
50
5,000,000
100,000
-99.9
348
Bulk Density
g/cm3 (dry)
1.0
2.0
1.35
21.9
-66.4
Moisture
%
5.0
25
10
10.7
-29.1
Particle Density
g/cm3
2.55
2.8
2.65
-6.1
8.4
Temperature
K
273
313
298
5.8
-3.1
Da
cm2/sec
0.059
0.25
0.1
-16.9
41.0
P
mm Hg
0.053
1820
35
-98.5
38.0
MW
g/gmol
41
166
100
-42.7
38.0
R
mm Hg-cm3/gmol-K
62361
62361
62361
NA
NA
Pi
--
3.14
3.14
3.14
NA
NA
kg
cm/sec
0.062
0.52
0.15
-4.3
2.4
t
sec
1
3600
60
1688
-65.4
Excavation Rate
m3/sec
0.042
0.042
0.042
NA
NA
Surface Area
ml
290
435
290
0.0
37.7
Exchange Constant
%
1
50
33
-23.8
12.6
Dependent Variables
C
g/cm3
1.00x10 7
5.00x10 3
1.35xl0'4
-99.9
302
Ea
vol/vol
0.020
0.625
0.440
-98.8
89.0
Et
vol/vol
0.216
0.643
0.491
87.1
-17.3
De
cm2/sec
3.00x 10"6
0.1265
0.0269
-74.7
80.4
Keq
--
1.00x104
1
0.613
-75.3
21.8
-------
main effect of temperature being to increase the vapor pressure and diffusivity terms. If
these terms are not corrected for temperature, then the model will become less accurate
as the temperature deviation from 25°C increases.
Equation A-7 requires the input of the time after the start of excavation
(t). It was assumed earlier that the emission rate at t = 60 seconds was equal to the
average emission rate over t = 0 to t = 360 seconds. It was further assumed that after 360
seconds, the excavated soil would be covered with additional layers of soil and the
diffusion of further material (emissions) would be minimal. The effect of time (t) was
examined by substituting a range of times into the base case conditions. The results of
these trials are given in Table A-4 and depicted in Figure A-l and A-2.
The effect of the initial soil concentration of the contaminant on the
predicted emission rate was examined by using the same base case assumptions and
varying the concentration from 1 ppbw to 10,000 ppmw. These results are shown in
Table A-5 and are plotted in Figure A-3. As the concentration increases, the percentage
of the total mass of material emitted decreases. Also, the relative contribution of pore-
space gas to the total emissions also decreases. The effect of vapor pressure (and
molecular weight) was examined by inserting the values for vapor pressure and molecular
weight for several common organic species into the base case. All compounds were
assumed to be present at 100 ppmw in the soil. These results are shown in Table A-6.
A final check of the models was made by comparing model predictions to
field data (Eklund, et al. Field Measurement of VOC Emissions From Soils Handling
Operations at Superfund Sites. EPA Contract No. 68-02-4392, Work Assignment 64.
September 1990). Comparisons of both the detailed (Equation A-7) and simple models
(Equations A-13 and A-20) to field data are shown in Table A-7. Total emissions for
twenty minute sampling periods are shown for two different field sites. The detailed
model using site-specific input data agrees with the field measurements within a factor of
five in all but two cases. The simplified model shows equally good agreement.
The equations presented here are a first attempt to model emissions from
soils handling operations. The equations are limited by a lack of laboratory or field data
to define certain key relationships between the variables. For example, the excavation
rate and the total exposed area are assumed in the equations to have a direct linear
relationship with the emission rate. No data, however, exist to support this assumption.
Similarly, the effects of temperature, scoop size, and surface area to volume ratio on
emissions have not been investigated. Another limiting assumption is that 33% of the
pore space gas is exchanged with the atmosphere. This value is arbitrary and was
selected since it fit reasonably well with the very limited field data that are available.
Measurements of emission rates from dynamic processes such as excavation
are very difficult to perform and are of limited accuracy. Limitations exist for dispersion
models used in indirect approaches (e.g., transect) and in the sampling and analytical
precision when attempting to determine emission rates using a mass balance approach.
Emerging measurement technologies, such as remote optical sensing, may allow more
detailed evaluation of the effect of these parameters in the future.
D-18
-------
Table A-4.
Effect of Time (t) on Emissions
Time (sec)
Diffusion Emission Rate
(mg/sec)
Total Emission Rate
(mg/sec)
0
81.9
83.1
5
11.0
12.1
10
8.09
9.23
20
5.89
7.03
30
4.87
6.01
40
4.25
5.39
50
3.83
4.96
60
3.51
4.65
90
2.89
4.02
120
2.51
3.65
180
2.06
3.20
240
1.79
2.93
300
1.61
2.74
360
1.47
2.61
420
1.36
2.50
480
1.28
2.41
540
1.20
2.34
600
1.14
2.28
1200
0.81
1.95
1800
0.66
1.80
2400
0.58
1.71
3000
0.51
1.65
3600
0.47
1.61
D-19
-------
Emission Rote vs. "irre (0 to 360 sec)
280
260
220
200
130
1 40
120
30
60
20
0 ti —is— --6 -1] di [i
1 1 I 1 1 1 r"
50 180 210 240 2 70 .50 J 330 350
30
45
60
90 I 20
5
0
1
Time (.sec)
Figure A-l. Emission Rate vs. Time for Base Case Conditions for 0 to 360 seconds.
D-20
-------
Emission Rate Vs. Time (0 to 60 min)
30
¦30
70
60
5C
40
o
10
0
3
5
6
7
8
9
10 20 30 40 50 60
0 0.5
1 5
-)
4
Time (mm)
~ Total Emissions * Diffusive Emissions
Figure A-2. Emision Rate vs. Time for Base Case Conditions for 0 to 60 Minutes.
D-21
-------
Table A-5.
Effect of Cone. (C) on Emissions
Cone (ug/Kg)
Log Cone
(ug/Kg)
Pore Gas
Emission
Rate (g/sec)
Diffusive
Emission
Rate (g/sec)
Total Emission
Rate (g/sec)
Emissions*
Vs. Total
Mass (%)
1
1
1.88 x 10"5
4.52 x 10"5
6.40 x 10"5
114
10
2
1.88 x 10"
4.52 x 10"
6.40 x 10"
114
100
3
1.87 x 10'3
4.52 x 10'3
6.40 x 10"3
114
1000
4
0.019
0.045
0.06
114
10000
5
0.188
1.14
1.33
236
100000
6
1.138
3.51
4.65
82.6
1000000
7
1.138
10.15
11.29
20.1
10000000
8
1.138
25.32
26.46
4.7
* Includes only mass of contaminants in excavated soil
D-22
-------
Emission Rate Vs. Time
As Soil Concentration Var.es
24
20 -i
8
5
6
7
2
4
Log Cone entration l ug/Kg)
~ Totol Emissions + Diffusive Emissions
Figure A-3. Emission Rate vs. Time as Soil Concentration Increases.
D-23
-------
Table A-6.
Effect of Molecular Weight (MW) + Vapor Pressure (P) on Emissions
Cone (ug/Kg)
Molecular
Weight (g/g-mol)
Vapor Pressure
(mm Hg)
Diffusive
Emission Rate
(g/sec)
Total Emission
Rate (g/sec)
Alkanes
butane
58.12
1820
4.52
6.40 *
pentane
72.15
513
4.52
6.40 •
hexane
86.18
150
4.52
6.40 *
heptane
100.2
46
4.05
5.55
octane
114.23
17
2.57
3.21
nonane
128.26
4.3
1.30
1.48
Aromatics
benzene
78.12
95.2
5.18
7.06
ethylbenzene
106.16
10
1.87
2.21
o-xylene
106.2
7.0
1.54
1.78
* Pore space emissions equal the total mass of contaminant present divided by 3.
D-24
-------
Table A-7
Comparison of Model Predictions to Field Data
Site
Run #
Compound
FIELD RESULTS
MODEL PREDICTIONS
PREDICTIONS FOR SIMPLE MODELS
Miss of
Conum.
Present (g)
Total
Emissions
(£)
Pore Space
Emissions
- EPS - (£)
Diffusive
Emissions
- Ei • (£)
Total
Emissions
(e>
Accuracy
(*>
Pore Space
Emissions
-EPS- (£)
Diffusive
Emissions
- Ei - Cg)
Total
Emissions
(£)
Accuracy
(%)
A
1
Xylenes
855
24
49
182
231
863
7.4
62
69
189
2
Xylenes3
12
37
4.0
20.3
24
-34
7.0
20
27
-27
3
Xylenes8
140
82
47
203
249
204
83
203
285
248
A
1
Ethylbenzene
53
6.6
21
32
52
692
3.1
32
35
432
2
Elhylbenzene8
1.2
8.4
0.4
4.2
4.6
-46
3.0
4.2
7.1
-15
4
Ethylbenzene®
14
14
4.6
42
46
230
35
42
76
443
B
2
Xylenes8
0 13
7.2
4.3
20
24
236
5.8
2.0
7.8
8.3
3
Xylenes8
2.7
2.2
0.9
9.2
10
357
5.8
9
15
581
4
Xylenes8
3.7
2.3
1.2
II
12
421
5.8
11
17
621
i Accuracy = (Model - Field)/Field x 100
m a Pore space emissions equal total mass of contaminant present divided by 3.
-------
APPENDIX B
PHYSICAL AND CHEMICAL CONSTANTS
FOR SELECTED COMPOUNDS
D-26
-------
APPENDIX B - PHYSICAL PROPERTY DATA
No.
Organic Compound
CAS NO.
Formula
Molecular
Weight
(g/g-mol)
Vapor
Pressure
(mm Hg)1
Diffusivity in
Air
(cm2 /sec)
1
Acetaldehyde
75-07-0
C2H40
44.00
760
0.1240
2
Acetic acid
64-19-7
C2H402
60.06
15.41
1.1300
3
Acetic anhydride
108-24-7
C4H603
102.09
5.266
0.2350
4
Acetone
67-64-1
C3H60
58.08
266
0.1240
5
Acetonitrile
75-05-8
C2H3N
41.06
90
0.1280
6
Acrolein
107-02-8
C3H40
56.1
244.2
0.1050
7
Acrylic acid
79-10-7
C3H402
72.1
5.2
0.0908
g
Acryionitrile
107-13-1
C3H3N
53.06
114
0.1220
9
Ally! alcohol
107-18-6
C3H60
58.08
23.3
0.1140
10
AJIyt chloride
107-05-1
C3H5CL
76.53
368
11
Aniline
62-53-3
C6H7N
93.13
1
0.0700
12
Anthracene
120-12-7
C14H10
178.23
1.3E-06
13
Benzaldehyde
100-52-7
C7H60
106.12
1
14
Benzene
71-43-2
C6H6
78.12
95.2
0.0932
15
Benzoic acid
65-85-0
C7H602
122.12
0.00704
16
Benzyl alcohol
100-51-6
C7H80
108.14
0.15
17
Benzyl chloride
100-44-7
C6H5CH2C1
126.6
1.21
0.0750
18
Bromoform
75-25-2
CHBr3
252.77
5.6
19
1,3-Butadiene
106-99-0
C4H6
54.09
2100.00
0.2490
20
N-Butane
106-97-8
C4H10
58.12
1820
0.2490
21
2-Butano!
15892-23-6
C4H10O
74.12
10
22
N-Butanol
71-36-3
C4H10O
74.12
6.5
23
N-Butyl-Acetate
123-86-4
C6H1202
116.16
15
24
Tert-Butyl-Alcohol
75-65-0
C4H10O
74.12
0.17
25
Carbon disulfide
75-15-0
CS2
76.13
366
0.1040
26
Carbon tetrachloride
56-23-5
CCL4
153.82
113
0.0632
27
Carbonyl sulfide
463-58-1
COS
60.1
-
28
Catechol
120-80-9
C6H4(OH)2
110.1
-
29
Chlorine
7782-50-5
C12
70.9
-
30
Chlorobenzene
108-90-7
C6H5CL
112.56
11.8
0.0730
31
Chlorodifluoromethane
75-45-6
CHCLF2
86.47
-
32
Chloroform
67-66-3
CHCL3
119.38
208
0.0888
33
Chloromethyl methyl ether
107-30-2
C2H5C10
80.51
-
34
Chloropentafluoroethane
76-15-3
C2CLF5
154.47
-
35
Chloroprene
126-99-8
CH2CHCH2C1
7633
273
0.1040
36
M-Cresol
108-39-4
C7H80
108.14
0.08
0.0740
37
O-Cresol
95-48-7
C7H80
108.14
0.24
0.0740
38
P-Crcsol
106-44-5
C7H80
108.14
0.11
0.0740
39
Cyanogen
460-19-5
C2N2
52.04
3980
40
Cyclohexane
110-82-7
C6H12
84.16
100
0.0839
41
Cyclohexanol
108-93-0
C6H120
100.16
1.22
0.2140
42
Cyclohexanone
108-94-1
C6H10O
98.14
4.8
0.0784
43
Cyclohexene
110-83-8
C6H10
82.15
-
D-27
-------
Appendix B. (Continued)
No.
Organic Compound
CAS NO.
Formula
Molecular
Weight
(g/g-mol)
Vapor
Pressure
(mm HgJ1
Diffusivity in
Air
(cn^ /see)
44
Cyclopentane
287-92-3
C5H10
70.13
317.44
45
Diazomethane
334-88-3
C1I2N2
42.04
-
46
Dibutyl-O-Phthalate
84-74-2
C16H2204
278.35
1.00E-05
0.0439
47
O-Dichlorobenzene
95-50-1
C6H4CL2
147.00
1
00690
48
P-Dichlorobenzene
106-46-7
C6H4CL2
147.00
1.2
00690
49
Dichloroethylether
111-44-4
C4H8C120
143.02
1.4
50
Dichlorodifluoromethane
75-71-8
CCL2F2
120.91
4870
51
1,1-Dichloroethane
75-34-3
C2H4CL2
98.96
234
0.0919
52
1,2-Dichloroethane
107-06-2
C2H4CL2
98.96
80
0.0907
53
1,1-Dichloroethylene
75-35-4
C2H2CL2
96.94
600
0.1040
54
cis-l,2-Dichloroethylene
156-59-2
C2H2CL2
96.94
208
55
trans-1.2-Dichloroeihylene
156-60-5
C2H2CL2
96.94
324
56
Dichloromethane
75-09-2
C1I2CL2
84.93
362
57
Dichloromonofluoromethane
75^*4
CHCL2F
10Z92
1360
58
1.2-Dichloropropane
78-87-5
C3H6CL2
112.99
42
59
1,3-Dichloropropene
542-75-6
C3H402
110.98
43
60
l,2-Dichloro-l,l,2,2-Teiranuoroethane
76-14-2
C2CI.2R
170.92
-
61
Diethanolaminc
111-42-2
C4HUN02
105.14
-
62
Diethyl amine
109-89-7
C4H1IN
73.14
350@35C
63
N,N-Dimeihylaniline
121-69-7
C8H11N
121.18
-
64
Diethyl ether
60-29-7
C4H10O
74.12
440@20C
0.0782
65
Dimethylamine
124-40-3
C2H7N
45.08
563 @ 0C
66
Dimethyl formamide
68-12-2
C3H7NO
73.09
4.0
0 0939
67
1,1-Dimethyl hydrazine
57-14-7
C2118N2
60.10
157
0.1060
68
2,4-Dinitrophenol
51-28-5
C6H4N205
184.11
53.8
69
1,4-Dioxane
123-91-1
C4H802
88.11
37
0.2290
70
Diphenyl
92-52-4
C12H10
154.21
-
71
Epichlorohydrin
106-89-8
C3115CI0
92.53
17
0.0860
72
1,2-Epoxybutane
106-88-7
C4H80
72.0
-
73
Ethanol
64-17-5
C21I60
46.07
50
0.1230
74
Ethyl acetate
141-78-6
C4H802
88.11
100
75
Ethyl acrylate
14038-5
C5H802
100.12
40
0.0770
76
Ethyl amine
75-04-7
C2H7N
45.08
1057
77
Ethylbenzene
100-41-4
C8II10
106.16
10
0.0750
78
Ethyl Bromide
74-96-4
C2H5Br
108.97
-
79
Ethyl carbamate
51-79-6
C3H7N02
89.09
10
80
Ethyl Chloride
75-00-3
C2H5CI
64 51
1200
0.2710
81
Ethylenediamine
107-15-3
C2H8N2
60.10
10.7
82
Ethylene dibromide
106-93-4
C2H4Br
187.88
14
83
Ethylene glycol
107-21-1
C2H602
62.07
0.13
0.1080
W
Ethylene imine
151-56-4
C2H5N
43.07
-
85
Ethylene oxide
75-21-8
C2H40
44.06
1250
0.1040
D-28
-------
Appendix B. (Continued)
No.
Organic Compound
CAS NO.
Formula
Molecular
Weight
(g/g-mol)
Vapor
Pressure
(mm Hg)1
Diffusivity in
Air
(cm2 /sec)
86
Formaldehyde
50-00-0
CH20
30.03
3500
0.1780
87
Formic acid
64-18-6
CH202
46.03
42
0.0790
88
Furan
110-00-9
C4H40
68.08
5%
0.1040
89
Glycerol
56-81-5
C3H803
92.09
1.60E-04
90
N-Heptane
142-82-5
C7H16
100.2
46
91
N-Hexane
110-54-3
C6H14
86.18
150.3
0.2000
92
Hydrazine
302-01-2
H4N2
32.05
14.4
93
Hydrochloric acid
7647-01-0
HQ
36.46
32,450
94
Hydrogen cyanide
74-90-8
CHN
27.03
-
95
Hydrogen sulfide
7783-06-4
H2S
34.08
15,200
0.1760
96
Isobutanoi
78-83-1
C4H10O
74.12
10
0.0860
97
Isobutyl acetate
110-19-0
C6H1202
116.16
-
98
Isopropyl alcohol
67-63-0
C3H80
60.1
42.8
0.0980
99
Isopropyt amine
75-31-0
C3H9N
59.11
460
100
Isopropylbenzene
98-82-8
C9H12
120.19
10.9@40C
101
Methanol
67-56-1
CH40
32.04
114
0.1500
102
Methyl acetate
79-20-9
C3H602
74.08
235
0.1040
103
Methyl atrylate
96-33-3
C4H702
86.09
-
104
Methyl amine
74-89-5
CH5N
31.06
770@ -6C
105
Methyl bromide
74-83-9
CH3BR
94.94
-
106
Methyl-tert-butyl-ether
1634-04-4
C5H120
88.15
245
0.0806
107
Methyl chloride
74-87-3
CH3CL
50.49
3830
0.1260
108
Methylcyclohexane
108-87-2
C7H14
98.19
43
109
Methyl-ethyl-ketone
78-93-3
C4H80
72.11
100
0.0808
110
Methyl formate
107-31-3
C2H402
60.05
500
111
Methyl hydrazine
60-34-4
CH6N2
46.07
49.6
112
Methyl iodide
74-88-4
CH3I
141.94
91
113
Methyl-lsobutyl-Ketone
108-10-1
C6H120
100.16
19.31
114
Methyl isocyanate
624-83-9
C2H3N0
57.05
348
115
Methyl-lsopropyl-Ketone
563-80-4
C5H10O
86.13
15.7
0.0750
116
Methyl mercaptan
74-93-1
CH4S
48.1
-
117
Methyl methacrylate
80-62-6
C5H802
100.10
39
0.0770
118
Methyl-N-Propyl-Ketone
107-87-9
C5H10O
86.13
-
119
Alpha-Methyl-Styrene
98-83-9
C9H10
118.18
0.076
0.2640
120
Monoethanolamine
141-43-5
C2H7NO
61.08
-
121
Morpholine
110-91-8
C4H9NO
87.12
10.08
122
Naphthalene
91-20-3
C10H8
128.19
0.023
0.0590
123
2-Nitropropane
79-46-9
C3H7N02
89.09
12.9
124
N-Nitrosodimethylamine
62-75-9
C2H6N20
74.08
-
125
N-Nitrosomorpholine
59-89-2
C4H8N20
116.11
-
126
N-Nonane
111-84-2
C9H20
128.26
4.28
127
N-Octane
111-65-9
C8H18
114.23
17
D-29
-------
Appendix B. (Continued)
No.
Organic Compound
CAS NO.
Formula
Molecular
Weight
(g/g-mol)
Vapor
Pressure
(mm llg)1
Diffusivity in
Air
(cn^ /sec)
128
N-Penune
109-66-0
C5H12
72.15
513
129
Phenanthrenc
85-01-8
C14H10
178.23
2.00E-04
130
Phenol
108-95-2
C6H6O
94.11
0.0341
0.0820
131
Phosgene
75-44-5
CQ20
98.92
1.394
0.1080
132
Phosphine
7803-51-2
IBP
34 00
2.000
133
Phthalic anhydride
85-44-9
C8H403
148.11
0.0015
0.0710
134
Propane
74-98-6
C3H8
44.1
760
135
1,2-Propanediol
57-55-6
C3H802
76.11
0J
136
1-Propanol
71-23-8
C3H80
60.1
20.85
137
beta-Propiolactone
57-57-8
C3H402
72.06
3.4
138
Propionaldehvde
123-38-7
C3H60
58.08
300
139
Propionic acid
79-09-4
C3H602
74.08
10
140
N-Propyl-Acetate
109-60-4
C5H10O2
102.12
35
141
Propylene oxide
75-56-9
C3H60
58.08
524.5
0.1040
142
1,2-Propylenimine
75-55-8
C3H7N
54.1
112
143
Pyridine
110-86-1
C5H5N
79 1
20
0.0910
144
Quinone
106-51-4
C6H402
108.09
-
145
Styrene
10042-5
C8H8
104.15
7.3
0.0710
146
l,l,l,2-Tctrachloro-2,2-Difluorocihane
76-11-9
C2CL4F2
203.83
-
147
1,1,2.2,-Tetrachloroethane
79-34-5
C2H2CL4
167.85
65
148
Tetrachlo methylene
127-18-4
C2CL4
165.83
19
0.0720
149
Tetrahydrofuran
109-99-9
C4H80
72.11
72.1
0.0980
150
Toluene
108-88-3
C7H8
92.14
30
0.0870
151
P-Toluidine
106-49-0
C7H9N
107 16
0.3
152
1,1,1-Trichlorocthane
71-55-6
C2H3CL3
133.41
123
0.0780
153
1,1,2-Trichloroeihane
79-00-5
C2H3CL3
133.41
25
0.0792
154
Trichlorocthylcne
79-01-6
C2HCL3
131.4
75
00790
155
Tnchlorofluoromethane
75-69-4
CC1JF
137.37
667
156
1,2,3-Tnchloropropane
96-18-4
C3H5CL3
147.43
3.1
157
l,l,2-Trichloro-1.2,2-Trifluoroethane
76-13-1
C2CL3F3
187.38
300
158
Triethyiamine
121-44-8
C6H15N
101.19
400
159
Trifluorobromomeihane
75-6M
CBRK3
148.91
-
160
1,23-Tnmethylbenzene
526-73-8
C9H12
120.19
-
161
1,2,4-Trimelhylbenzene
95-63-6
C9H12
120.19
-
162
1.3.5-Trimethylbenzene
108-67-8
C9H12
120.19
1.86
163
Vinyl Acetate
108-05-4
C4H602
86.09
115
0.0850
164
Vinyl bromide
593-60-2
C2H3Br
107.0
895
165
Vinyl-Chloride
75-01-4
C2H3CL
62.5
2660
0.0900
166
M-Xylene
108-38-3
C8H10
106.2
8
0.0700
167
O-Xylene
95-47-6
C8H10
106.2
7
0.0870
168
P-Xylene
106-42-3
C8H10
106.2
95
1 All vapor pressures arc at 25* C unless otherwise indicated.
D-30
-------
APPENDIX E - ARTICLE ON SOIL VAPOR EXTRACTION
(Source: Pedersen, T.A., and J.T. Curtis. Handbook on Soil Vapor
Extraction Technology. EPA/540/2-91-003. February 1991.
A PRACTICAL APPROACH TO THE DESIGN, OPERATION, AND MONITORING
OF IN-SITU SOIL VENTING SYSTEMS
P. C. Johnson", M. W. Kemblowski", J. D. Colthart",
D. L. Byers", and C. C. Stanleyb
INTRODUCTION
When operated properly, in-situ soil venting or vapor extraction can be
one of the more cost-effective remediation processes for soils contaminated
with gasoline, solvents, or other relatively volatile compounds. A "basic"
system, such as that shown in Figure E-l, couples vapor extraction (recovery)
wells with blowers or vacuum pumps to remove vapors from the vadose zone and
thereby reduce residual levels of soil contaminants. More complex systems
incorporate trenches, air injection wells, passive wells, and surface seals.
Above-ground treatment systems condense, adsorb, or incinerate vapors; in some
cases vapors are simply emitted to the atmosphere through diffuser stacks.
In-situ soil venting is an especially attractive treatment option because the
soil is treated in place, sophisticated equipment is not required, and the
cost is typically lower than other options.
The basic phenomena governing the performance of soil venting systems
are easily understood. By applying a vacuum and removing vapors from
extraction wells, vapor flow through the unsaturated soil zone is induced.
Contaminants volatilize from the soil matrix and are swept by the carrier gas
flow (primarily air) to the extraction wells or trenches. Many complex
processes occur on the microscale, however, the three main factors that
control the performance of a venting operation are the chemical composition of
the contaminant, vapor flowrates through the unsaturated zone, and the
flowpath of carrier vapors relative to the location of the contaminants.
The components of soil venting systems are typically off-the-shelf
items, and the installation of wells and trenches can be done by most
reputable environmental firms. However, the design, operation, and monitoring
of soil venting systems is not trivial. In fact, choosing whether or not
"Shell Development/bShell Oil Company, Westhollow Research Center
Houston, TX 77152-1380
E-1
-------
Vapor Treatment
Unit
Vacuum
Pump
I
f ^
Vapor
Flow
• ••
Vapor Extraction Well
Contaminated
Soil
Vapor
Flow
L
Free-Liquid
Hydrocarbon
Groundwater Table
Soluble.
Plume
Figure E-l. "Basic" In-Situ Soil Venting System
E-2
-------
venting should be applied at a given site is a difficult question in itself.
If one decides to utilize venting, design questions involving the number of
wells, well spacing, well location, well construction, and vapor treatment
systems must then be answered. It is the current state-of-the-art that such
questions are answered more by instinct than by rigorous logic. This is
evidenced by the published soil venting "success stories" (see Hutzler et al.1
for a good review), which rarely include insight into the design process.
In this paper we suggest a series of steps and questions that must be
followed and answered in order to a) decide if venting is appropriate at a
given site, and b) to design cost-effective in-situ soil venting systems.
This series of steps and questions forms a "decision tree" process that could
be easily incorporated in a PC-based expert system. In the development of
this approach we will attempt to identify the limitations of in-situ soil
venting, and subjects or behavior that are difficult to quantify and for which
future study is needed.
THE "PRACTICAL APPROACH"
Figure E-2 presents a flowchart of the process discussed in this paper.
Each step of the flowchart is discussed below in detail, and where
appropriate, examples are given.
The Site Investigation
Whenever a soil contamination problem is detected or suspected, a site
investigation is conducted to characterize and delineate the zone of soil and
groundwater contamination. Often the sequence of steps after initial response
and abatement is as follows:
(a) background review: Involves assembling historical records, plot
plans, engineering drawings (showing utility lines), and interviewing site
personnel. This information is used to help identify the contaminant, probable
source of release, zone of contamination, and potentially impacted areas
(neighbors, drinking water supplies, etc.).
(b) preliminary sice screening: Preliminary screening tools such as
soil-gas surveys and cone penetrometers are used to roughly define the zone of
contamination and the site geology. Knowledge of site geology is essential to
determine probable migration of contaminants through the unsaturated zone.
(c) detailed site characterization: Soil borings are drilled and
monitoring wells are installed based on the results from steps (a) and (b).
(d) contaminant characterization: soil and groundwater samples are
analyzed to determine contaminant concentrations and compositions.
Costs associated with site investigations can be relatively high
depending on the complexity of the site and size of the spill or leak. For
large spills and complex site geological/hydrogeological conditions, site
E-3
-------
Process
Leak or Spill Discovered
I
Site
Investigation
Screen Treatment
Alternatives
Output
Venting ?
Site Characteristics;
• soil stratigraphy
• characteristics of distinct soil layers
(permeability estimates)
• depth to groundwater & gradient
• aquifer permeability (estimate)
• residual levels of contaminants
• distribution of contaminant
• composition of contaminant
• soil & above-ground temperature
• soil vapor concentrations (optional)
• removal rate estimates
• vapor flowrate estimates
• final residual levels & composition
Air Permeability Test
• air permeability of distinct soil layers
• radius of influence of vapor wells
• initial vapor concentrations
aquifer properties (gradient,
transmissivity, storativity)
• number of vapor extraction wells
• vapor well construction
• vapor well spacing
• instrumentation
• vapor treatment system
• flowrate (vacuum) specifications
• groundwater pumping system specifics
No
Yes
No
Yes
Turn Off ?
'clean" site
(target levels based on
exposure assessment)
System Design
System Operation
& Monitoring
Groundwater Pump Test
vennng recovery rates
changes in vadose zone contamination
System Shut-Off
Figure E-2. In-Situ Soil Venting System Design Process.
E-4
-------
investigation costs are often comparable to remediation costs. In addition,
the choice and design of a remediation system is based on the data obtained
during the site investigation. For these reasons it is important to insure
that specific information is collected, and to validate the quality of the
data.
If it is presumed that in-situ soil venting will be a candidate for
treatment, then the following information needs to be obtained during the
preliminary site investigation:
(a) sice geology • this includes soil type and subsurface stratigraphy.
While they are not essential, the moisture content, total organic carbon, and
permeability of each distinct soil layer also provides useful information that
can be used to choose and design a remediation system.
(b) sice hydrogeology - the water table depth and gradient must be
known, as well as estimates of the aquifer permeability.
(c) concaminanc composicion, discribucion and residual levels - soil
samples should be analyzed to determine which contaminants are present at what
levels. Recommended analytical methods should be used to identify target
compounds (i.e., benzene, toluene, or xylenes) and total hydrocarbons present.
For soil analyses these methods are:
EPA 8240 - volatile organic chemicals
EPA 8270 - semi-volatile organic chemicals
EPA 418.1 - total petroleum hydrocarbons
The corresponding water analyses methods are:
EPA 624 • volatile organic chemicals
EPA 625 - semi-volatile organic chemicals
EPA 418.1 - total petroleum hydrocarbons
Vith the current high cost of chemical analyses it is important to
intelligently select which analyses should be performed and which samples
should be sent to a certified laboratory. Local regulations usually require
that a minimum number of soil borings be performed, and target compounds must
be analyzed for based on the suspected composition of the contamination.
Coses can be minimized and more data obtained by utilizing field screening
tools, such as hand-held vapor meters or portable field GC's. These
instruments can be used to measure both residual soil contamination levels and
headspace vapors above contaminated soils. At a minimum, soil samples
corresponding to lithology changes or obvious changes in residual levels
(based on visual observations or odor) should be analyzed.
For complex contamination mixtures, such as gasoline, diesel fuel, and
solvent mixtures, it is not practical or necessary to identify and quantify
each compound present. In such cases it is recommended that a "boiling point"
distribution be measured for a representative sample of the residual
E-5
-------
contamination. Boiling point distribution curves, such as shown in Figure E-3
for "fresh" and "weathered" gasoline samples, can be constructed from GC
analyses of the soil residual contamination (or free-product) and knowledge of
the GC elution behavior of a known series of compounds (such as straight-chain
alkanes). Compounds generally elute from a GC packed column in the order of
increasing boiling point, so a boiling point distribution curve is constructed
by grouping all unknowns that elute between two known peaks (i.e. between
n-hexane and n-heptane). Then they are assigned an average boiling point,
molecular weight, and vapor pressure. Use of this data will be explained
below.
(d) temperature - both above- and below-ground surface.
The cone penetrometer, which is essentially an instrumented steel
rod that is driven into the soil, is becoming a popular tool for
preliminary site screening investigations. By measuring the shear and
normal forces on the leading end of the rod, soil structure, and hence
permeability can be defined. Some cone penetrometers are also
constructed to allow the collection of vapor or groundwater samples.
This tool has several advantages over conventional soil boring
techniques (as a preliminary site characterization tool): the subsurface
soil structure can be defined better, no soil cuttings are generated,
and more analyses can be performed per day.
Results from the preliminary site investigation should be
summarized in contour plots, fence diagrams, and tables prior to
analyses.
Deciding if Venting is Appropriate
As stated above, the three main factors governing the behavior of any
in-situ soil venting operation are the vapor flow rate, contaminant vapor
concentrations, and the vapor flowpath relative to the contaminant location.
In an article by Johnson et al.2 simple mathematical equations were presented
to help quantify each of these factors. Below we illustrate how to utilize
these "screening models" and the information collected during the preliminary
site investigation to help determine if in-situ soli venting is appropriate at
a given site. In making this decision we will answer the following questions:
(1) What contaminant vapor concentrations are likely to be obtained?
(2) Under ideal vapor flow conditions (i.e. 100 - 1000 scfm vapor
flowrates), is this concentration great enough to yield acceptable
removal rates?
(3) What range of vapor flowrates can realistically be achieved?
(4) Will the contaminant concentrations and realistic vapor flowrates
produce acceptable removal rates?
E-6
-------
1.0 ¦
Cumulative
Weight o.8
Fraction
0.6-
0.4
0.2
i i
"Fresh" Gasoline
"Weathered" Gasoline
-40 0 40 80 120 160 200 240
T (°C)
b
Figure E-3. Boiling Point Distribution Curves for Samples
"Fresh" and "Weathered" Gasolines.
-------
(5) What are the vapor composition and concentration changes? Whac
residual, if any, will be left in che soil?
(6) Are there likely Co be any negative effeccs of soil vencing?
Negative answers Co questions (2), (3), or (4) will rule out in-situ soil
venting as a practical treatment method.
(1) - Whac concaminant vapor concentrations are likely to be obtained?
Question (1) can be answered based on the results of soil vapor surveys,
analyses of headspace vapors above contaminated soil samples, or equilibrium
vapor models2. In some cases just knowing which compounds are present is
sufficient to estimate if venting is feasible. In the absence of soil-vapor
survey data, contaminant vapor concentrations can be estimated. The maximum
vapor concentration of any compound (mixture) in extracted vapors is its
equilibrium or "saturated" vapor concentration, which is easily calculated
from knowledge of the compound's (mixture's) molecular weight, vapor pressure
at the soil temperature, residual soil contaminant composition, and the ideal
gas law:
_ xlP1vMw>l
C„t - L (E-l)
where:
C„t - estimate of contaminant vapor concentration [mg/1]
xt - mole fraction of component i in liquid-phase residual
(xt - 1 for single compound)
Pj* - pure component vapor pressure at temperature T [atm]
t - molecular weight of component i [mg/mole]
R - gas constant - 0.0821 l-atm/mole-°K
T - absolute temperature of residual [°K]
Table E-l presents data for some chemicals and mixtures often spilled in the
environment. There are more sophisticated equations for predicting vapor
concentrations in soil systems based on equilibrium partitioning arguments,
but these require more detailed information (organic carbon content, soil
moisture) than is normally available. If a site is chosen for remediation,
the residual total hydrocarbons in soil typically exceed 500 mg/kg. In this
residual concentration range the majority of hydrocarbons will be present as a
separate or "free" phase, th« contaminant vapor concentrations become
independent of residual concentration (but still depend on composition), and
Equation E-l is applicable2. In any case, it should be noted that these are
estimates only for vapor concentrations at Che start of venting, which is
when the removal rates are generally greatest. Contaminant concentrations in
the extracted vapors will decline with time due to changes in composition,
residual levels, or increased diffusional resistances. These topics are
discussed belov in more detail.
E-8
-------
Table E-l. Selected Compounds and Their Chemical Properties.
Compound
Mw
Tb (1 atm) Pv
° (20°C)
Csat
(s/mole")
(atm)
(me/D
n-pentane
72.2
36
0.57
1700
n-hexane
86.2
69
0.16
560
trichloroe thane
133.4
75
0.132
720
benzene
78.1
80
0.10
320
cyclohexane
84.2
81
0.10
340
trichloroe thylene
131.5
87
0.026
140
n-heptane
100.2
98
0.046
190
toluene
92.1
111
0.029
110
tetrachloroethylene
166
121
0.018
130
n-octane
114.2
126
0.014
65
chloro benzene
113
132
0.012
55
p-xylene
106.2
138
0.0086
37
ethylbenzene
106.2
138
0.0092
40
m-xylene
106.2
139
0.0080
35
o-xylene
106.2
144
0.0066
29
styrene
104.1
145
0.0066
28
n-nonane
128.3
151
0.0042
22.0
n-propylbenzene
120.2
159
0.0033
16
1,2,4 trimethylbenzene
120.2
169
0.0019
9.3
n-decane
142.3
173
0.0013
7.6
DBCP
263
196
0.0011
11
n-undecane
156.3
196
0.0006
3.8
n-dodecane
170.3
216
0.00015
1.1
napthalene
128.2
218
0.00014
0.73
tetraethyllead
323
dec. @200C
0.0002
2.6
gasoline1
95
0.34
1300
weathered easoline2
111
•
0.049
220
1 Corresponds to "fresh" gasoline defined in Table E-2 with boiling point
distribution shown in Figure E-3.
2 Corresponds to "weathered" gasoline defined in Table E-2 with boiling point
distribution shown in Figure E-3.
E-9
-------
(2) - Under ideal vapor flow condlclons (i.e. 100 - 1000 scfm vapor
flowrates) , is chis concencradon great enough Co yield acceptable
removal rates?
Question (2) is answered by multiplying the concentration estimate C.,,.,
by a range of reasonable flowrates, Q:
Q (E-2)
Here R„t denotes the estimated removal rate, and C.lt. and Q must be expressed
in consistent units. For reference, documented venting operations at service
station sites typically report vapor flowrates in the 10 - 100 scfm range1,
although 100 - 1000 scfm flowrates are achievable for very sandy soils or
large numbers of extraction wells. At this point in the decision process we
are still neglecting that vapor concentrations decrease during venting due to
compositional changes and mass transfer resistances. Figure E-4 presents
calculated removal rates Rejt [kg/d] for a range of C.Jt and Q values. Ceit
values are presented in [mg/1] and [ppm^] units, where [ppm^] represents
methane-equivalent parts-per-million volume/volume (ppniy) units. The [ppm,.^]
units are used because field analytical tools that report [ppm^ values are
often calibrated with methane. The [mg/1] and [ppm,.^] units are related by:
[ppm^] * 16000mg-CHt/mole-CH4 * 10*6
[mg/1] (E-3)
(0.0821 l-atm/°K-mole) * (298K)
For field instruments calibrated with other compounds (i.e., butane, propane)
[ppniy] values are converted to [mg/1] by replacing the molecular weight of CHt
in Equation E-3 by the molecular weight [mg/mole] of the calibration compound.
Acceptable or desirable removal rates R»ee.pMbi«« can be determined by
dividing the estimated spill mass MlpU1, by the maximum acceptable clean-up
time T:
&accapc»bla ~ MjpUl/T (E-4)
For example, if 1500 kg (®500 gal) of gasoline had been spilled at a service
station and we wished to complete the clean-up within eight months, then
R»cc.pt«bi« "6-3 kg/d. Based on Figure E-4, therefore, CMt would have to
average >1.5 mg/1 (2400 ppm^) for Q-2800 1/min (100 cfm) if venting is to be
an acceptable option. Generally, removal rates <1 kg/d will be unacceptable
for most spills, so soils contaminated with compounds (mixtures) having
saturated vapor concentrations less than 0.3 mg/1 (450 ppm^) will not be
good candidates for venting, unless vapor flowrates exceed 100 scfm. Judging
from the compounds listed in Table E-l, this corresponds to compounds with
E-10
-------
(ppmCH()
1530
15300
00"
Removal
Rale
(kg/d)
.001
100
10
.01
.1
1
Vapor Concentration (mg/1)
* (ppm^ ) - concentration in methane-equivalent ppm (voUvol.) units
Figure E-4. In-Situ Soil Venting Removal Rate Dependence on
Vapor Extraction Rate and Vapor Concentration.
E-ll
-------
boiling points (Tb)>150°C, or pure component vapor pressures <0.0001 atm
evaluated at the subsurface temperature.
- What range of vapor flowrates can realistically be achieved?
Question (3) requires that we estimate realistic vapor flowrates for our
site specific conditions. Equation E-5, which predicts the flowrate per unit
thickness of well screen Q/H [cm3/s], can be used for this purpose:
Q k [l-(P4tm/Pv)2]
*—Pv (E-5)
H H ln(Rv/RI)
where:
k - soil permeability to air flow [cm2] or [darcy]
m - viscosity of air - 1.8 x 10"* g/cm-s or 0.018 cp
Pw - absolute pressure at extraction well [g/cm-s2] or [atm]
PAta - absolute ambient pressure « 1.01 x 106 g/cm-s2 or 1 atm
R„ - radius of vapor extraction well [cm]
Rr - radius of influence of vapor extraction well [cm]
This equation is derived from the simplistic steady-state radial flow solution
for compressible flow2, but should provide reasonable estimates for vapor flow
rates. If we can measure or estimate k, then the only unknown parameter is
the empirical "radius of influence" Rr. Values ranging from 9 m (30 ft) to
30 m (100 ft) are reported in the literature for a variety of soil conditions,
but fortunately Equation E-5 is not very sensitive to large changes in Rx.
For estimation purposes, therefore, a value of Rr-12 m (40 ft) can be used
without a significant loss of accuracy. Typical vacuum well pressures range
from 0.95 - 0.90 atm (20 - 40 in H20 vacuum). Figure E-5 presents predicted
flowrates per unit well screen depth Q/H, expressed in "standard" volumetric
units Q*/H (- Q/H(Pw/PAta)) for a 5.1 cm radius (4" diameter) extraction well,
and a wide range of soil permeabilities and applied vacuums. Here H denotes
the thickness of the screened interval, which is often chosen to be equal to
the thickness of the zone of soil contamination (this minimizes removing and
treating any excess "clean" air). For other conditions the Q*/H values in
Figure E-5 can be multiplied by the following factors:
Rv - 5.1 cm (2")
Ri -
7.6 m (25')
Rv - 5.1 cm (2")
Ri "
23 m (75')
Rv - 7.6 cm (3")
Ri "
12 m (40')
Rv - 10 cm (4")
Ri -
12 m (40')
Rv - 10 cm (4")
Ri ~
7.6 m (25')
multiply by Q*/H by 1.09
multiply by Q*/H by 0.90
multiply by Q*/H by 1.08
multiply by Q*/H by 1.15
multiply by Q*/H by 1.27
As indicated by the multipliers given above, changing the radius of influence
from 12 m (40 ft) to 23 m (75 ft) only decreases the predicted flowrate by
10%. The largest uncertainty in flowrate calculations will be due to the air
permeability value k, which can vary by one to three orders of magnitude
across a site and can realistically only be estimated from boring log data
E-12
-------
1100
R , = i 2 m (40*)
_ no
P = 0.40 atm = 20.3 ft H-,0
W
P = 0.60 atm =13.6 ft H„0
w 2
Vapor
Flowrate
(scfm/ft)
(m /m-min);
P = 0.80 atm = 6.8 ft H-0
•P = 0.90 atm = 3.4 ft H-0
0.11
P = 0.95 atm = 1.7 ft HLO
0.011
fine
sands
medium
sands
clayey
sands
coarse
sands
0.0011
.0001
.01
10
100
1000
Soil Permeabilty (darcy)
[ft H^O] denote vacuums expressed as equivalent water column heights
"Figure E-5. Predicted Steady-State Flowrates (per unit well screen depth)
for a Range of Soil Permeabilities and Applied Vacuums (Pw).
E-13
-------
within an order of magnitude. It is prudent, therefore, to choose a range of
k values during this phase of the decision process. For example, if boring
logs indicate fine sandy soils are present, then flowrates should be
calculated for k values in the range 0.1Q C.
(E-6)
In Figure E-6b, vapor flows parallel to, but not through, the zone of
contamination, and the significant mass transfer resistance is vapor phase
diffusion. This would be the case for a layer of liquid hydrocarbon resting
on top of an impermeable strata or the water table. This problem was studied
by Johnson et al.2 for the case of a single component. Their solution is:
R..t - *?QC„t
1
„ (6D/lA)1/2[ln(RI/Rv)/(PAta-Pv)]1'2 [R^-Ri2]1'2 (E-7)
3H
E-14
-------
a;
;apor flow
side view
vapor flosy
vaoor now
top view
b)
vapor flow
vapor concentration
profile
vapor concentration = 0
impermeable layer
liquid contaminant
c)
vapor flow
V
1
"dried" zone
j diffusing vapors | | _5_
"wet" zone with residual contamination
Figure E-6. Scenarios for Removal Rate Estimates.
E-15
-------
where:
rj - efficiency relative to maximum removal rate
D - effective soil vapor diffusion coefficient [cm2/s]
jjL - viscosity of air - 1.8 x 10"* g/cm-s
k - soil permeability to vapor flow [cm2]
H - thickness of screened interval [cm]
RT - radius of influence of venting well [cm]
Rv - venting well radius [cm]
PAca - absolute ambient pressure - 1.016 x 10s g/cm-s2
Pv - absolute pressure at the venting well [g/cm-s2]
Rt
Here ^ and ^ are the soil bulk density [g/cm3] and soil moisture content
[g-H20/g-soil] .
As an example, consider removing a layer of contamination bounded by
sandy soil (k-1 darcy). A 5.1-cm (2") radius extraction well is being
operated at Pv-0.90 atm (0.91 x 10® g/cm-s2), and the contamination extends
from the region Rx - Rv - 5.1 cm to Rz — 9 m (30 ft). The well is screened
over a 3m (10 ft) interval. Assuming thac:
Pfc -1.6 g/cm3
Bh - 0.10
D° - 0.087 ca2/a
eT - 0.30
Rx - 12 m
then the venting efficiency relative to the maximum removal rate (Equation E-
5), calculated from Equations E-7 through E-9 is:
rj - 0.09 - 9%
E-16
-------
Figure E-6c depicts the situation in which vapor flows primarily past,
rather than through the contaminated soil zone, such as might be the case for
a contaminated clay lens surrounded by sandy soils. In this case vapor phase
diffusion through the clay to the flowing vapor limits the removal rate. The
maximum removal rate in this case occurs when the vapor flow is fast enough to
maintain a very low vapor concentration at the permeable/impermeable soil
interface. At any time t a contaminant-free or "dried out" zone of low
permeability will exist with a thickness 5. An estimate of the removal rate
Rest from a contaminated zone extending from Rr to R2 is:
(E-10)
R.,t - 1T(R2 - R2)C„tD/
-------
1000
200
"Dry" Zone
Thickness
benzene (20 C)
Rj = 5.1 cm
R2 = 900 cm
est 100-
(kg/d) 100;
(cm)
¦100
100
200
400
500
300
0
Time (d)
Figure E-7. Estimated Maximum Removal Rates for a Venting Operation
Limited by Diffusion.
E-18
-------
Mixture removal rates for the situations depicted in Figures E-6b and E-
6c are difficult to estimate because changes in composition and liquid-phase
diffusion affect the behavior. Presently there are no simple analytical
solutions for these situations, but we can postulate that they should be less
than the rates predicted above for pure components.
The use of equilibrium-based models to predict required removal rates is
discussed below under the next question.
(5) - What are the vapor composition and concentration changes? What residual,
if any, will be left in the soil?
As contaminants are removed during venting, the residual soil
contamination level decreases and mixture compositions become richer in the
less volatile compounds. Both of these processes result in decreased vapor
concentrations, and hence, decreased removal rates with time. At low
residual soil contamination levels (<500 ppm) Equation E-l becomes less valid
as sorption and dissolution phenomena begin to affect the soil residual -
vapor equilibrium. In the limit of low residual contamination levels,
contaminant equilibrium vapor concentrations are expected to become
proportional to the residual soil contaminant concentrations. As venting
continues and residual soil levels decrease, therefore, it becomes more
difficult to remove the residual contamination. It is important to realize
that, even with soil venting, there are practical limitations on the final
soil contamination levels that can be achieved. Knowledge of these limits is
necessary to realistically set clean-up criteria and design effective venting
systems.
The maximum efficiency of a venting operation is limited by the
equilibrium partitioning of contaminants between the soil matrix and vapor
phases. The maximum removal rate is achieved when the vapor being removed
from an extraction well is in equilibrium with the contaminated soil. Models
for predicting this maximum removal rate have been presented by Marley and
Hoag* and Johnson et al.2 The former considered only compositions in a
residual free-phase, while the latter also considered the effects of sorption
and dissolution processes. A complete discussion of the development of these
models is not appropriate here, but we will discuss use of the predictions.
The change in composition, vapor concentration, removal rate, and
residual soil contamination level with time are functions of the initial
residual composition, vapor extraction well flowrate, and initial soil
contamination level. It is not necessary to generate predictions for every
combination of variables, however, because with appropriate scaling all
results will form a single curve for a given initial mixture composition.
Figure E-8a presents the results computed with the model presented by Johnson
et al.2 for the "weathered" gasoline mixture whose composition is given by
Table E-2. The important variable that determines residual soil levels, vapor
concentrations, and removal rates is the ratio Qt/M(t-0), which represents the
volume of air drawn through the contaminated zone per unit mass of
contaminant. In Figure E-8, the scaled removal rate (or equivalently the
E-19
-------
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Weatherea Gasoline
T = 20° C
10% moisture coniem
C(t=0) = 222 mg/1
¦80
% removed
QC/QC(t=0)
changed from 4-pnasc to
3-phue system
¦60
•01 T
"40
¦20
Full Composition
.0001
0
100
200
300
Qt/m(t=0) (I/g)
100
Weathered Gasoline
"80
10% moisture content
changed from 4-phasc to C(t=0) — 270 mg/1
3-phase system
% removed
QC/QC(t=0)
•60
¦40
.001
¦20
Approximate Composition
.0001
200
300
0
100
Qt/m(t=0) (1/g)
Figure E-8. Maximum Predicted Removal Rates for a Weathered Gasoline,
a) full composition, b) approximate composition.
E-22
-------
vapor concentration) decreases with time as the mixture becomes richer in the
less volatile compounds.
While a detailed compositional analysis was available for this gasoline
sample, an approximate composition based on a boiling point distribution curve
predicts similar results. Figure E-8b presents the results for the
approximate mixture composition also given in Table E-2.
Model predictions, such as those shown in Figure E-8 for the gasoline
sample defined by Table E-2, can be used to estimate removal rates (if the
vapor flowrate is specified), or alternatively the predictions can be used to
estimate vapor flowrate requirements (if the desired removal rate is
specified). For example, if we wanted to reduce the initial contamination
level by 90%, then Figure E-8 predicts that «100 1-air/g-gasoline will be
required. This is the minimum amount of vapor required, because it is based
on an equilibrium-based model. The necessary minimum average vapor flowrate
is then equal to the spill mass times the minimum required vapor flow/mass
gasoline divided by the desired duration of venting. Use of this approach is
illustrated in the service station site example provided at the end of this
paper.
Figure E-8 also illustrates that there is a practical limit to the
amount of residual contaminant that can be removed by venting alone. For
example, it will take a minimum of 100 1-vapor/g-gasoline to remove 90% of the
weathered gasoline defined in Table E-2, while it will take about 200
1-air/g-gasoline to remove the remaining 10%. In the case of gasoline, by the
time 90% of the initial residual has been removed the residual consists of
relatively insoluble and nonvolatile compounds. It is important to recognize
this limitation of venting, and when setting realistic clean-up target levels,
they should be based on the potential environmental impact of the residual
rather than any specific total residual hydrocarbon levels.
(6) - Are there likely to be any negative effects of soil venting?
It is possible that venting will induce the migration of off-site
contaminant vapors towards the extraction wells. This is likely to occur at a
service station, which is often in close proximity to other service stations.
If this occurs, one could spend a lot of time and money to unknowingly
clean-up someone else's problem. The solution is to establish a "vapor
barrier" at the perimeter of the contaminated zone. This can be accomplished
by allowing vapor flow into any perimeter groundwater monitoring wells, which
then act as passive air supply wells. In other cases it may be necessary to
install passive air injection wells, or trenches, as illustrated in Figure E-
9a.
As pointed out by Johnson et al.2 the application of a vacuum to
extraction wells can also cause a water table rise. In many cases
contaminated soils lie just above the water table and they become water
saturated, as illustrated in Figure E-9b. The maximum rise occurs at the
vapor extraction well, where the water table rise will be equal to the vacuum
E-23
-------
a)
Vapor Extraction
Well
Passive Air Injection Well
or
Perimeter Groundwater Monitoring Well
b)
Vapor Extraction
Well
Unsaturated
Soil Zone
Water Table Upweiling
Saturated
Soil Zone Caused by Vacuum
Figure E-9. a) Use of Passive Vapor Wells to Prevent Migration of Off-Site
Contaminant Vapors, b) Water Table Rise Caused by the Applied Vacuum.
E-24
-------
at the well expressed as an equivalent water column height (i.e., in or ft
H20). The solution to this problem is to install a dewatering system, with
groundwater pumping wells located as close to vapor extraction wells as
possible. The dewatering system must be designed to insure that contaminated
soils remain exposed to vapor flow. Other considerations not directly related
to venting system design, such as soluble plume migration control and
free-liquid product yield, will also be factors in the design of groundwater
pumping system.
Design Information
If venting is still a remediation option after answering the questions
above, then more accurate information must be collected. Specifically, the
soil permeability to vapor flow, vapor concentrations, and aquifer
characterics are required. These are obtained by two field experiments: air
permeability and groundwater pump tests. These are described briefly below.
Air Permeability Tests
Figure E-10 depicts the set-up of an air permeability test. The object
of this experiment is to remove vapors at a constant rate from an extraction
well, while monitoring with time the transient subsurface pressure
distribution at fixed points. Effluent vapor concentrations are also
monitored. It is important that the test be conducted properly to obtain
accurate design information. The extraction well should be screened through
the soil zone that will be vented during the actual operation. In many cases
existing groundwater monitoring wells are sufficient, if their screened
sections extend above the water table. Subsurface pressure monitoring probes
can be driven soil vapor sampling probes (for shallow <20 ft deep
contamination problems) or more permanent installations.
Flowrate and transient pressure distribution data are used to estimate
the soil permeability to vapor flow. The expected change in the subsurface
pressure distribution with time P'(r,t) is predicted2 by:
Q n e
P' 11 dx (E-13)
Unm(k/n) x
2
r tit
4kPAtat
For (r2 /4kPAtat)<0.1 Equation E-13 can be approximated by:
Q r2,M
P' [-0.5772 - ln( ) + ln(t)] (E-14)
47Tm(k/M) 4kPAta
E-25
-------
Pressure Vapor Flowmeter
Gauge
Vapor Treatment
Unit
Vacuum
Pump
Vapor Sampiin;
Port
•••
GH
GH
Vapor Extraction Well
Vapor
How
Vapor
Flow
Contaminated
Soil
Pressure Sampling Probes
Figure E-10. Air Permeability Test System.
E-26
-------
where:
P' - "gauge" pressure measured at distance r and time t
m - stratum thickness
r - radial distance from vapor extraction well
k - soil permeability to air flow
H - viscosity of air - 1.8 x 10"* g/cm-s
e - air-filled soil void fraction
t - time
Q - volumetric vapor flovrate from extraction well
PAtm - ambient atmospheric pressure -1.0 atm - 1.013 x 106
g/cm-s2
Equation E-14 predicts that a plot of P' -vs- ln(t) should be a straight line
with slope A and y-intercept B equal to:
Q Q r2efi
A B [-0.5772 - ln( )] (E-15)
4Wm(k/M) 4JTm(k/M) 4kPAtm
The permeability to vapor flow can then be calculated from the data by one of
two methods. The first is applicable when Q and m are known. The calculated
slope A is used:
QM
k (E-16)
4A)rm
The second approach must be used whenever Q or m is not known. In this case
the values A and B are both used:
r2€fi B
k exp(—+ 0.5772) (E-17)
A
Equation E-13 can also be used to choose the locations of subsurface
pressure monitoring points before conducting the air permeability test, given
an estimation of k and the flowrate to be used.
Vapor samples should be taken at the beginning and end of the air
permeability test, which should be conducted for a long enough time to extract
at least one "pore volume" Vp of vapor from the contaminated soil zone. This
insures that all vapors existing In the formation prior to venting are
removed. The vapor concentration at the start of the test is representative
of the equilibrium vapor concentration, while the concentration measured after
one pore volume has been extracted gives an indication of realistic removal
rates and the mixing or dlffusional limitations discussed in association with
Figure E-6. The time Tr for one pore volume to be removed Is:
Tp - Vp/Q - eAirR2H/Q (E-18)
E-27
-------
where R, H, CA> and Q are the radius of the zone of contamination, vertical
thickness of the zone of contamination, air-filled void fraction, and
volumetric vapor flowrate from the extraction well. For example, consider the
case where R-12 m, H-3 m, €A-0.35, and Q—0.57 m3/min (20 ft3/min) . Then rp-475
m3/0.57 m3/min-833 min-14 h.
Groundwater Pump Tests
To achieve efficient venting the hydrocarbon-contaminated soil has to be
exposed to air flow, which in turn requires that the water table be lowered to
counteract the water upwelling effect caused by the decreased vapor pressure
in the vicinity of a venting well (Johnson et al.2) and to possibly expose
contaminated soil below the water table. Thus the groundwater pumping system
has to have a sufficient pumping rate and be operated for a long enough time
period to obtain the required drawdowns. Since most venting systems are
installed above phreatic aquifers, two aquifer parameters are needed for the
design: average transmissivity T and effective porosity S. These parameters
can be estimated using the results of the standard transient groundwater pump
test with a constant pumping rate (Bear3). Using the estimated values the
required pumping rate may be calculated as follows:
Q - 4rrS(r,t)/V(u) (E-19)
where: W(u) is the well function3 of u - Sr2/^Tt, and s(r,t) is the required
drawdown at distance r and pumping time equal to t.
System Design
In this section we discuss the questions that must be answered in order
to design an in-situ soil venting system. It is not our intention to provide
a generic "recipe" for soil venting systems design; instead we suggest a
structured thought process to guide in choosing the number of extraction
wells, well spacing, construction, etc. Even in a structured thought process,
intuition and experience play important roles. There is no substitute for a
good fundamental understanding of vapor flow processes, transport phenomena,
and groundwater flow.
- Choosing the number of vapor extraction wells
Three methods for choosing the number of vapor extraction wells are
outlined belov. The greatest number of wells from these three methods is then
the value that should be used. The objective is to satisfy removal rate
requirements and achieve vapor removal from the entire zone of contamination.
For the first estimate we neglect residual contaminant composition and
vapor concentration changes with time. The acceptable removal rate Racc,ptabi«
is calculated from Equation E-4, while the estimated removal rate from a
single well R.lt is estimated from a choice of Equations E-2, E-6, E-7, or E-
E-28
-------
12 depending on whether the specific site conditions are most like Figure E-
6a, E-6b, or E-6c. The number of wells Nw,u required to achieve the
acceptable removal rate is:
(E-20)
^w«ll "
Equations E-2, E-6, and E-7 require vapor flow estimates, which can be
calculated from Equation E-5 using the measured soil permeability and chosen
extraction well vacuum Pw. At this point one must determine what blowers and
vacuum pumps are available because the characteristics of these units will
limit the range of feasible (PW,Q) values. For example, a blower that can
pump 100 scfm at 2 in H20 vacuum may only be able to pump 10 scfm at 100 in
H20 vacuum.
The second method, which accounts for composition changes with time,
utilizes model predictions, such as those illustrated in Figure E-8. Recall
that equilibrium-based models are used to calculate the minimum vapor flow to
achieve a given degree of remediation. For example, if we wish to obtain a
90% reduction in residual gasoline levels, Figure E-8 indicates that «100
1-vapor/g-gasoline must pass through the contaminated soil zone. If our spill
mass is 1500 kg (-500 gal), then a minimum of 1.5 x 10* 1-vapor must pass
through the contaminated soil zone. If our target clean-up period is six
months, this corresponds to a minimum average vapor flowrate of 0.57 m3/min
(-20 cfm). The minimum number of extraction wells is then equal to the
required minimum average flowrate/flowrate per well.
The third method for determining the number of wells insures that we
remove vapors and residual soil contamination from the entire zone of
contamination Naln. This is simply equal to the ratio of the area of
contamination AeontaalMtlon, to the area of influence of a single venting well
JTRj2:
A
^centaalnAt ion
Nala (E-21)
2
JTR
I
This requires an estimate of RIt which defines the zone in which vapor flow is
induced. In general, Rx depends on soil properties of the vented zone,
properties of surrounding soil layers, the depth at which the well is
screened, and the presence of any impermeable boundaries (water table, clay
layers, surface seal, building basement, etc.)- At this point it is useful to
have some understanding of vapor flow patterns because, except for certain
ideal cases', one cannot accurately predict vapor flowpaths without
numerically solving vapor flow equations. An estimate for Rx can be obtained
by fitting radial pressure distribution data from the air permeability test to
the steady-state radial pressure distribution equation2:
E-29
-------
PAta 2 lndr/RJ
P(r) - Pw[l+(l-( ) ) ]1'2 (E-22)
Pw lnd^/Rj)
where P(r). PAt-. Pv. and Ry are Che absolute pressure measured at a distance r
from the venting well, absolute ambient pressure, absolute pressure applied at
the vapor extraction well, and extraction well radius, respectively. Given
that these tests are usually conducted for less than a day, the results will
generally underestimate RT. If no site specific data is available, one can
conservatively estimate RT based on the published reports from in-situ soil
venting operations. Reported Rr values for permeable soils (sandy soils) at
depths greater than 20 ft below ground surface, or shallower soils beneath
good surface seals, are usually 10 m - 40 a.1 For less permeable soils
(silts, clays), or more shallow zones Rx is usually less.
- Choosing well location, spacing, passive wells, and surface seals
To be able to successfully locate extraction wells, passive wells, and
surface seals one must have a good understanding of vapor flow behavior. We
would like to place wells so that we insure adequate vapor flow through the
contaminated zone, while minimizing vapor flow through other zones.
If one well is sufficient, it will almost always be placed in the
geometric center of the contaminated soil zone, unless it is expected that
vapor flow channeling along a preferred direction will occur. In that case
the well will be placed so as to maximize air flow through the contaminated
zone.
When multiple wells are used it is important to consider the effect that
each well has on the vapor flow to all other wells. For example, if three
extraction wells are required at a given site, and they are installed in the
triplate design shown in Figure E-lla, there would be a "stagnant" region in
the middle of the wells where air flow would be very small in comparison to
the flow induced outside the triplate pattern boundaries. This problem can be
alleviated by the use of "passive wells" or "forced injection" wells as
illustrated in Figure E-llb (it can also be minimized by changing the vapor
flowrates from each well with time). A passive well is simply a well that is
open to the atmosphere; in many cases groundwater monitoring wells are
suitable. If a passive or forced injection well is to have any positive
effect, it muse be located within the extraction well's zone of influence.
Forced injection wells are simply vapor wells into which air is pumped rather
than removed. One oust be very careful in choosing the locations of forced
injection wells so that contaminant vapors are captured by the extraction
wells, rather than forced off-site. To date there have not been any detailed
reports of venting operations designed to study the advantages/disadvantages
of using forced injection wells. Figure E-llc presents another possible
extraction/injection well combination. As illustrated in Figure E-9, passive
wells can also be used as vapor barriers to prevent on-site migration of
off-site contamination problems.
E-30
-------
extraction
- wells
stagnant
air flow
region
b)
vapor flow
lines
injection
well
_ extraction
wells
C)
I
injection
wells
bT
extraction
wells
Figure E-ll. Venting Well Configuration.
E-31
-------
For shallow contamination problems (<4 m below ground surface) vapor
extraction trenches combined with surface seals may be more effective than
vertical wells. Trenches are usually limited to shallow soil zones because the
difficulty of installation increases with depth.
Surface seals, such as polymer-based liners and asphalt, concrete, or
clay caps, are sometimes used to control the vapor flow paths. Figure E-12
illustrates the effect that a surface seal will have on vapor flow patterns.
For shallow treatment zones (<5 m) the surface seal will have a significant
effect on the vapor flow paths, and seals can be added or removed to achieve
the desired vapor flowpath. For wells screened below 8 m the influence of
surface seals becomes less significant.
- Well screening and construction
Wells should be screened only through the zone of contamination, unless
the permeability to vapor flow is so low that removal rat«s would be greater
if flow were induced in an adjacent soil layer (see Figure E-6). Removal rate
estimates for various mass-transfer limited scenarios can be calculated from
Equations E-7 and E-12.
Based on Equation E-5, the flowrate is expected to increase by 15% when
the extraction well diameter is increased from 10 cm (4 in) to 20 cm (8 in).
This implies that well diameters should be as large as is practically
possible.
A typical well as shown in Figure E-13a is constructed from slotted pipe
(usually PVC). The slot size and number of slots per inch should be chosen to
maximize the open area of the pipe. A filter packing, such as sand or gravel,
is placed in the annulus between the borehole and pipe . Vapor extraction
wells are similar to groundwater monitoring wells in construction but there is
no need to filter vapors before they enter the well. The filter packing,
therefore, should be as coarse as possible. Any dust carried by the vapor
flow can be removed by an above-ground filter. Bentonite pellets and a
cement grout are loaded above the filter packing. It is important that these
be properly installed to prevent a vapor flow "short-sircuit". Any
groundwater monitoring wells installed near the extraction wells must also be
installed with good seals.
• Vapor treatment
Currently there are four main treatment processes available. Each is
discussed below.
- vapor combustion units: Vapors are incinerated and destruction
efficiencies are typically >95%. A supplemental fuel, such as propane, is
added before combustion unless extraction well vapor concentrations are on
the order of a few percent by volume. This process becomes less economical as
vapor concentrations decrease below «10,000 ppn^.
E-32
-------
"open" soil surface
b)
impermeable seal
Figure E-12. Effect of Surface Seal on Vapor Flowpath.
E-33
-------
cem;r.: cap
u
Sj
—
£;
-
Ul
>
ccment/bentoniie
eu
grout
'
*
slotted pipe T
1
f£
|
coarse packing
section *
|
Hi
b)
air-right monitoring well
cop/water sensor assembly
pressure gauge
connection
electronic water
sensor
wire ro sensor
_ double teflon
inner septa seal
monitoring
well cap
Figure E-13. a) Extraction Well Construction, and b) Air-Tight
Groundwater Level Measuring System.
E-34
-------
- catalytic oxidation units: Vapor streams are heated and then passed
over a catalyst bed. Destruction efficiencies are typically >95%. These
units are used for vapor concentrations <8000 ppn^. More concentrated vapors
can cause catalyst bed temperature excursions and melt-down.
- carbon beds: Carbon can be used to treat almost any vapor streams,
but is only economical for very low emission rates (<100 g/d)
- diffuser stacks: These do not treat vapors, but are the most
economical solution for areas in which they are permitted. They must be
carefully designed to minimize health risks and maximize safety.
• Groundwater pumping system
In cases where contaminated soils lie just above or below the water
table, groundwater pumping systems will be required to insure that
contaminated soils remain exposed. In designing a groundwater system it is
important to be aware that upwelling (draw-up) of the groundwater table will
occur when a vacuum is applied at the extraction well (see Figure E-9b).
Because the upwelling will be greatest at the extraction wells, groundwater
pumping wells should be located within or as close to the extraction wells as
possible. Their surface seals must be airtight to prevent unwanted
short-circuiting of airflow down the groundwater wells.
• System integration
System components (pumps, wells, vapor treating units, etc.) should be
combined to allow maximum flexibility of operation. The review by Hutzler et
al.1 provides descriptions of many reported systems. Specific requirements
are:
- separate valves, flowmeters, and pressure gauges for each extraction
and injection well.
• air filter to remove particulates from vapors upstream of pump and
flow meter.
• knock-out pot to remove any liquid from vapor stream upstream of pump
and flow meter.
The performance of a soil venting system must be monitored in order to
insure efficient operation, and to help determine when to shut-off the system.
At a minimum the following should be measured:
- date and eimm of measurement.
• vapor flow rates from extraction wells and into injection wells:
these can be measured by a variety of flowmeters including pitot tubes,
E-35
-------
orifice plates, and rotameters. It is important to have calibrated these
devices at the field operating pressures and temperatures.
- pressure readings at each extraction and injection well can be
measured with manometers or magnahelic gauges.
- vapor concent radons and compositions from extraction wells: total
hydrocarbon concentration can be measured by an on-line total hydrocarbon
analyzer calibrated to a specific hydrocarbon. This Information is combined
with vapor flowrate data to calculate removal rates and the cumulative amount
of contaminant removed. In addition, for mixtures the vapor composition
should be periodically checked. It is impossible to assess if vapor
concentration decreases with time are due to compositional changes or some
other phenomena (mass transfer resistance, water table upwelling, pore
blockage, etc.) without this information. Vapor samples can be collected in
evacuated gas sampling cylinders, stored, and later analyzed.
- temperature: ambient and soil.
- water table level (for contaminated soils located near the water
table): It is important to monitor the water table level to Insure that
contaminated soils remain exposed to vapor flow. Measuring the water table
level during venting is not a trivial task because the monitoring well must
remain sealed. Uncapping the well releases the vacuum and any effect that it
has on the water table level. Figure E-13b Illustrates a monitoring well cap
(constructed by Applied Geosclences Inc., Tustin, CA) that allows one to
measure simultaneously the water table level and vacuum in a monitoring well.
It is constructed from a commercially available monitoring well cap and
utilizes an electronic water level sensor.
Other valuable, but optional measurements are:
- soil gas vapor concentrations and compositions: these should be
measured periodically at different radial distances from the extraction well.
Figure E-14 shows the construction of a permanent monitoring installation
that can be used for vapor sampling and subsurface temperature measurements.
Another alternative for shallow contamination zones is the use of soil gas
survey probes.
This data is valuable for two reasons: a) by comparing extraction well
concentrations with soil gas concentrations it is possible to estimate the
fraction of vapor that is flowing through the contaminated zone f-C.«rMtion
*«ii/Cioii iu> b) it is possible to determine if the zone of contamination
is shrinking towards the extraction well, as it should with time. Three
measuring points are probably sufficient if one is located near the extraction
well, one is placed near the original edge of the zone of contamination, and
the third is placed somewhere in between.
These monitoring installations can also be useful for monitoring the
subsurface vapors after venting has ceased.
E-36
-------
Ground Surface
Box Containing Vapor Samplin:
Ports (^Thermocouples
1/8" OD Teflon Tubing
coarse packing
cement/bentonite
Figure E-14. Vadose Zone Monitoring Installation.
E-37
-------
When To Turn Off The System?
Target soil clean-up levels are ofcen sec on a sice-by-sice basis, and
are based on Che escimaced potential impacc that any residual may have on air
qualicy, groundwater qualicy, or ocher health standards. They may also be
related to safecy considerations (explosive limits). Generally, confirmation
soil borings, and somecimes soil vapor surveys, are required before closure is
granted. Because these analyses are expensive and ofcen disrupc Che normal
business of a site, it would be valuable to be able to determine when
confirmation borings should be taken. If the monicoring is done as suggesced
above, then the following criteria can be used:
- cumulative amount removed: determined by incegracing che measured
removal races (flowrace x concentration) with time. While chis value
indicaces how much concaminanc has been removed, ic is usually noc very useful
for determining when Co cake confirmacion borings unless che original spill
mass is known very accuracely. In mosc cases chac information is not
available and can not be calculated accurately from soil boring daca.
- extraction well vapor concentrations: the vapor concentrations are
good indications of how effectively the venting system is working, but
decreases in vapor excraccion well concencrations are noc strong evidence that
soil concentrations have decreased. Decreases may also be due to other
phenomena such as water table level increases, increased mass cransfer
resistance due to drying, or leaks in the excraccion system.
• extraction veil vapor composition: when combined with vapor
concencracions chis daca gives more insight inCo che effecciveness of che
system. If che total vapor concentration decreases without a change in
composicion, ic is probably due to one of che phenomena mentioned above, and
is noc an indicacion chat the residual concaminacion has been significancly
reduced. If a decrease in vapor concentration is accompanied by a shift in
composition Cowards less volatile compounds, on the other hand, ic is mosc
likely due Co a change in che residual contaminant concenCration. For
residual gasoline clean-up, for example, one might operace a venting system
until benzene, toluene, and xylenes were not detected in the vapors. The
remaining residual would then be composed of larger molecules, and it can be
argued that these do not pose a health threat through volatilization or
leaching pathways.
- soil gas contaminant concentration and composition: this data is the
most useful because it yields information about the residual composition and
extent of contamination. Vapor concentrations can not be used to determine
the residual level, except for very low residual levels (<500 mg/kg).
Other Factors
- increased blodegradation
It is often postulated that because the air supply to the vadose zone is
E-38
-------
increased, the natural aerobic microbiological activity is increased during
venting. While the argument is plausible and some laboratory data is
available7, conclusive evidence supporting this theory has yet to be
presented. This is due in part to the difficulty in making such a
measurement. A mass balance approach is not likely to be useful because the
initial spill mass is generally not known with sufficient accuracy. An
indirect method would be to measure C02 levels in the extraction well vapors,
but this in itself does not rule out the possibility that 02 is converted to
C02 before the vapors pass through the contaminated soil zone. The best
approach is to measure the 02/C02 concentrations in the vapors at the edge of
the contaminated zone, and in the vapor extraction wells. If the C02/02
concentration ratio increases as the vapors pass through the contaminated
soil, one can surmise that a transformation is occurring, although other
possible mechanisms (inorganic reactions) must be considered. An increase in
aerobic microbial populations would be additional supporting evidence.
- in-siCu heating/venting
The main property of a compound that determines whether or not it can be
removed by venting is its vapor pressure, which increases with increasing
temperature. Compounds that are considered nonvolatile, therefore, can be
removed by venting if the contaminated soil is heated to the proper
temperature. In-situ heating/venting systems utilizing radio-frequency
heating and conduction heating are currently under study*. An alternative is
to reinject heated vapors from catalytic oxidation or combustion units into
the contaminated soil zone.
- air sparging
Due to seasonal groundwater level fluctuations, contaminants sometimes
become trapped below the water table. In some cases groundwater pumping can
lower the water table enough to expose this zone, but in other cases this is
not practical. One possible solution is to install air sparging wells and
then inject air below the water table. Vapor extraction wells would then
capture the vapors that bubbled up through the groundwater. To date, success
of this approach has yet to be demonstrated. This could have a negative
effect if foaming, formation plugging, or downward migration of the residual
occurred.
Application of the Design Approach to a Service Station
Remediation
In the following we will demonstrate the use of the approach discussed
above and outlined in Figure E-2 for the design operation, and monitoring of
an in-situ venting operation at a service station.
E-39
-------
Preliminary Site Investigation
Prior to sampling it was estimated that 2000 gal of gasoline had leaked
from a product line at this site. Several soil borings were drilled and the
soil samples were analyzed for total petroleum hydrocarbons (TPH) and other
specific compounds (benzene, toluene, xylenes) by a heated-headspace method
utilizing a field GC-FID. Figure E-15 summarizes some of the results for one
transect at this site. The following relevant information was collected:
- based on boring logs there are four distinct soil layers at this site
between 0 - 18 m (0- 60 ft) below ground surface (BGS). Figure E-15 indicates
the soil type and location of each of these layers.
- depth to groundwater was 15 m, with fine to medium sand aquifer soils
- the largest concentrations of hydrocarbons were detected in the sandy
and silty clay layers adjacent to the water table. Some residual was detected
below the water table. Based on the data presented in Figure E-15 it is
estimated that - 4000 kg of hydrocarbons are present in the lower two soil
zones.
• initially there was some free-liquid gasoline floating on the water
table, and this was subsequently removed by pumping. A sample of this product
was analyzed and its approximate composition (-20% of the compounds could not
be identified) is listed in Table E-2 as the "weathered gasoline". The
corresponding boiling point distribution curve for this mixture has been
presented in Figure E-3.
- vadose zone monitoring installations similar to the one pictured in
Figure E-14 were installed during the preliminary site investigation.
Deciding if Venting is Appropriate
For the remainder of the analysis we will focus on the contaminated soils
located just above the water table.
- What contaminant vapor concentrations are likely to be obtained?
Based on the composition given in Table E-2, and using Equation E-l, the
predicted saturated TPH vapor concentration for this gasoline is:
C.ft - 220 mg/1
Using the "approximate" composition listed in Table E-2 yields a value
of 270 mg/1. The measured soil vapor concentration obtained from the vadose
zone monitoring well was 240 mg/1. Due to composition changes with time, this
will be the maximum concentration obtained during venting.
- Under ideal flow conditions is this concentration great enough to
yield acceptable removal rates?
E-40
-------
now Meter
Vapor
Incinerator
Sampling
Porr
10 —
20 —
30 _
c/5
"3
O
6
O 40
Well
Manifold
To Water Treating
Svstem
60—*
Static Ground
Water Table
Dilution
B owcr
V
Tank
Backfill
"0.02
Fine to
Coarse Sand
_ _o.o
Silty Clay
&
~ayey Silt
-- 971
_ _ 28679
23167
Fine to
Medium Sand
9 J
HB-17
HB-10
HB-21
[Ground Water
Recovery Well]
HB-5
\
HB-25
[Vapor
Recovery Well]
SCALE (ft)
i 1
10
20
Figure E-15. Initial Total Hydrocarbon Distribution [mg/kg-soil] and
Location of Lower Zone Vent Well.
E-41
-------
Equation E-4 was used to calculate Racc.pt4bL.• Assuming Msptu - 4000 kg
and t - 180 d, then:
K-ace«pt*bl« ~
22 kg/d
Using Equation E-2, C,lt - 240 mg/1, and Q - 2800 1/min (100 cfm):
R«»t ~ 970 kg/d
which is greater than R,ee.pt.bi..
- What range of vapor flowraces can realistically be achieved?
Based on boring logs the contaminated zone just above the water table is
composed of fine to medium sands, vhlch have an estimated permeability 1< k < 10
darcy. Using Figure E-5, or Equation E-5, the predicted flovrates for an
extraction well vacuum Pv - 0.90 atm are:
0.04 < Q < 0.4 m3/ni-min Rv - 5.1 cm, Rx - 12 m
0.43 < Q < 4.3 ft3/ft-min Rv - 2.0 in, Rt - 40 ft
The thickness of this zone and probable screen thickness of an extraction
well is about 2 m (6.6 ft). The total flovrate per well through this zone is
estimated to be 0.08
-------
contaminated zone to achieve this target. Based on our estimated initial
residual of 4000 kg TPH, 4 x 108 1-vapor are required. Over a six month
period this corresponds to an average flowrate Q-1.5 m3/min (54 cfm). Recall
that since this corresponds to the maximum removal rate, it is the minimum
required flowrate.
- Are there likely to be any negative effects of soil venting?
Given that the contaminated soils are located just above and below the
water table, water table upwelling during venting must be considered here.
Air Permeability Test
Figure E-16 presents data obtained from the air permeability test of
this soil zone. In addition to vapor extraction tests, air injection tests
were conducted. The data is analyzed in the same manner as discussed for
vapor extraction tests. Accurate flowrate (Q) values were not measured,
therefore, Equation E-17 was used to determine the permeability to vapor flow.
The k values ranged from 2 to 280 darcys, with the median being -8 darcys.
System Design
- Number of vapor extraction wells:
Based on the 8 darcys permeability, and assuming a 15 cm diameter (6 in)
venting well, a 2 m screened section, Pv - 0.90 atm (41 in H20 vacuum) and
Rj-12 m, then Equation E-5 predicts:
Q - 0.7 m3/min - 25 cfm
Based on the discussion above, a minimus average flowrate of 1.5 m3/m^n i-s
needed to reduce the residual to 1000 ppm in 6 months. The number of wells
required is then 1.5/0.7 - 2, assuming that 100% of the vapor flows through
contaminated soils. It is not likely that this will occur, and a more
conservative estimate of 50% vapor flowing through contaminated soils would
require that twice as many wells (4) be installed.
A single vapor extraction well (HB-25) was installed in this soil layer
with the knowledge that more wells were likely to be required. Its location and
screened interval are shown in Figure E-15. Other wells were installed in the
clay layer and upper sandy zone, but in this paper we will only discuss results
from treatment of the lower contaminated zone. A groundwater pumping well was
installed to maintain a 2 m drawdown below the static water level. Its location
is also shown in Figure E-15.
System Monitoring
Three vadose monitoring wells similar in construction to the one pictured
in Figure E-14 were installed so that the soil temperature, soil gas
E-43
-------
a)
0
Pressure -- -
Decrease
(in H,0) _4 __
-6-
-8-
-10
G HB-7D (i=3.4 m)
A HB-6D (r=l6. m)
- HB-14D (r=9.8 m)
a ~
~ a
"i
10 100
Time (min)
1000
b)
50
Pressure
Increase
(in H20)
40-
30-
20-
10-
~ HB-7D (r=3.4 ra)
± HB-6D (f=16. m)
0 HB-14D (r=9.8 m)
+ HB-10 (r»7.6m)
C?
,df
+*
+ ,
+ c
rf3 +
+ ->
+o
5 + ,+ "
k » i
A
T-
10 100
Time (min)
1000
Figure E-16. Air Permeability Test Results: a) vapor extraction test,
b) air injection test.
E-44
-------
concentrations, and subsurface pressure distribution could be monitored at three
depths. One sampling port is located in the zone adjacent to the aquifer. The
vapor flowrate from HB-25 and vapor concentrations were measured frequently, and
the vapor composition was determined by GC-FID analysis. In addition, the water
level in the groundwater monitoring wells was measured with the system pictured
in Figure E-13b. The results from the first four months of operation are
discussed below.
In Figure E-17a the extraction well vacuum and corresponding vapor flowrate
are presented. The vacuum was maintained at 0.95 atm (20 in H20 vacuum), and
the flowrate was initially 12 scfm. It gradually decreased to about 6 scfm over
80 d. For comparison, Equation (5) predicts that Q-12 cfm for k-8 darcys.
Increasing the applied vacuum to 0.70 atm (120 in H20 vacuum) had little effect
on the flowrate. This could be explained by increased water table upwelling,
which would act to decrease the vertical cross-section available for vapor flow.
The scatter in the flowrate measurements is probably due to inconsistent
operation of the groundwater pumping operation, which frequently failed to
perform properly.
Figure E-17b presents the change in vapor concentration with time. Fifteen
specific compounds were identified during the GC-FID vapor analyses; in this
figure we present the total concentration of known and unknown compounds detected
between five boiling point ranges:
methane - isopentane (<28°C)
isopentane - benzene (28 - 80°C)
benzene - toluene (80 - 111°C)
toluene - xylenes (111 - 144°C)
>xylenes (>144°C)
There was a shift in composition towards less volatile compounds in the
first 20 d, but after that period the composition remained relatively constant.
Note that there is still a significant fraction of volatile compounds present.
Within the first two days the vapor concentration decreased by 50%, which
corresponds to the time period for the removal of the first pore volume of air.
Comparing the subsequent vapor concentrations with the concentrations measured
in the vadose zone monitoring wells indicates that only (80 mg/l)/(240
mg/l)*100-33% of the vapors are flowing through contaminated soil.
Figure E-18a presents calculated removal rates (flowrate x concentration)
and cumulative amount (1 gal - 3 kg) removed during the first four months. The
decrease in removal rate with time is due to a combination of decreases in
flowrate and hydrocarbon vapor concentrations. After the first four months
approximately one-fourth of the estimated residual has been removed from this
lower zone.
On day 80 the vacuum was increased from 20 - 120 in H20 vacuum and the
subsequent increase in subsurface vacuum and water table upwelling was monitored.
Figure E-18b presents the results. Note that the water table rise paralleled the
vacuum increase, although the water table did not rise the same amount that the
E-45
-------
a;
HB-25
Vacuum
(in H 0)
2
Vacuum)
U " * * i
» / 1 ' ' i
V " ' R
f
40 60
Time (d)
[in H^O] denote vacuums expressed as equivalent water column heights
Figure E-17a. Soil Venting Results: Vacuum/Flowrate Data
E-46
-------
b)
100
80
Vapor
Cone. 60
(mg/1)
f~l Xylcnet
40 60
Time (d)
Figure E-17b. Soil Venting Results: Concentration/Composition Data
E-47
-------
a)
Removal 40 4
Rate
(kg/d) so
Cumulative
Recovered
(gal)
-i——i—1—i 1 i ¦ i
20 40 60 80 100 120
Time (d)
b)
0.5
0.4-
ft H O
2 OJ -j
0.2
0.1 -
OX)
0 - vacuum increase
* - water table upwelling
~ txP
1 10
Time (min)
100
[ft H^O] denote vacuums expressed as equivalent water column heights
Figure E-18. Soli Venting Results: a) Removal Rate/Cumulative
Recovered, b) Water Table Rise.
E-48
-------
vacuum did.
Figure E-19 compares Che reduced measured TPH vapor concentration
C(t)/C(t-0) with model predictions. C(t-O) was taken to be the vapor
concentration after one pore volume of air had passed through the contaminated
zone (-80 mg/1), m(t-0) is equal to the estimated spill mass (-4000 kg), and V(t)
is the total volume of air that has passed through the contaminated zone. This
quantity is obtained by integrating the total vapor flowrate with time, then
multiplying it by the fraction of vapors passing through the contaminated zone
f (-0.33). As discussed, the quantity f was estimated by comparing soil gas
concentrations from the vadose zone monitoring installations with vapor
concentrations in the extraction well vapors. As can be seen, there is good
quantitative agreement between the measured and predicted values.
Based on the data presented in Figures E-15 through E-19 and the model
predictions in Figure E-8, it appears that more extraction wells (-10 more) are
needed to remediate the site within a reasonable amount of time.
CONCLUSIONS
A structured, technically based approach has been presented for the design,
construction, and operation of venting systems. While we have attempted to
explain the process in detail for those not familiar with venting operations or
the underlying governing phenomena, the most effective and efficient systems can
only be designed and operated by personnel with a good understanding of the
fundamental processes involved. The service station spill example presented
supports the validity and usefulness of this approach.
There are still many technical issues that need to be resolved in the
future. In particular, we must be able to estimate removal rates for non-ideal
situations, demonstrate that biodegradation is enhanced by venting, and
investigate novel ideas for enhancing venting removal rates.
E-49
-------
C(t)/C(t=0) predicted
C(l)/C(l=0) measured
C(t)/C(t=0)
0.6-
weatfaered gasoline
m(t»0) - 4000 kg
0.4
0.2 ¦
0.0
0123456789 10
V(t)/m(t=0) (1/g)
Predictions and Measured Response.
Figure E-19. Comparison of Model Predict
E-50
-------
REFERENCES
Bear, J., Hydraulics of Groundwater, McGraw-Hill, 1979.
Dev, H., G. C. Sresty, J. E. Bridges and D. Downey, Field Test of the Radio
Frequency in-situ Soil Decontamination Process, in Superfund '88:
Proceedings of the 9th National Conference, HMCRI, November 1988.
Hutzler, N. J. , B. E. Murphy, and J. S. Gierke, State of Technology Review: Soil
Vapor Extraction Systems, U.S.E.P.A., CR-814319-01-1, 1988.
Johnson, P. C. , M. W. Kemblowski, and J. D. Colthart, Practical Screening Models
for Soil Venting Applications, NWWA/API Conference on Petroleum
Hydrocarbons and Organic Chemicals in Groundwater, Houston, TX, 1988.
Marley, M.C., and G. E. Hoag, Induced Soil Venting for the Recovery/Restoration
of Gasoline Hydrocarbons in the Vadose Zone, NWA/API Conference on
Petroleum Hydrocarbons and Organic Chemicals in Groundwater, Houston, TX,
1984.
Millington, R. J., and J. M. Quirk, Permeability of Porous Solids, Trans.
Faraday Soc., 57:1200-1207, 1961.
Salanitro, J. P., M. M. Western, and M. W. Kemblowski, Biodegradation of Aromatic
Hydrocarbons in Unsaturated Soil Microcosms. Poster paper presented at the
Fourth National Conference on Petroleum Contaminated Soils, University of
Massachusetts, Amherst, September 25-28, 1989.
Wilson, D. J., A. N. Clarke, and J. H. Clarke, Soil Clean-up by in-situ Aeration.
I. Mathematical Modelling, Sep. Science Tech., 23:991-1037, 1988.
E-51
-------
APPENDIX F
ENGINEERING BULLETINS FOR TREATMENT PROCESSES
CONTENTS
Page
EPA-540/2-91-023 Control of Air Emissions from Materials
Handling During Remediation F-2
EPA-540/2-91-008 Thermal Desorption Treatment F-9
EPA-540/2-91-006 In Situ Soil Vapor Extraction Treatment F-17
EPA-540/2-90-016 Slurry Biodegradation F-27
EPA-540/S-92-007 Rotating Biological Contactors F-35
EPA-540/R-93-519b Guide for Conducting Treatability Studies Under
CERCLA: Biodegradation Remedy Selection F-43
EPA-540/2-90-014 Mobile/Transportable Incineration Treatment F-52
EPA-540/2-90-017 Soil Washing Treatment F-59
EPA-540/S-94-503 Solvent Extraction F-69
EPA-540/2-91-021 In Situ Soil Flushing F-80
F-l
-------
*
3 EPA
United States
Environmental Protection
Agency
Superfund :
Office of Emergency and
Remedial Response
Washington, OC 20460
EPA/540/2-91/023
Office of
Research and Development
Cincinnati, OH 45268
October 1991
Engineering Bulletin
Control of Air Emissions From
Materials Handling During
Remediation
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation and Liability Act (CERCLA) mandates the
Environmental Protection Agency (EPA) to select remedies that
"utilize permanent solutions and alternative treatment technolo-
gies or resource recovery technologies to the maximum extent
practicable" and to prefer remedial actions in which treatment
"permanently and significantly reduces the volume, toxicity, or
mobility of hazardous substances, pollutants and contaminants
as a principal element." The Engineering Bulletins are a senes of
documents that summarize the latest information available on
selected treatment and site remediation technologies and re-
lated issues. They provide summaries of and references for the
latest information to help remedial project managers (RPMs), on-
scene coordinators (OSCs), contractors, and other site cleanup
managers understand the type of data and site characteristics
needed to evaluate a technology for potential applicability to
their Superfund or other hazardous waste site. Those documents
that describe individual treatment technologies focus on reme-
dial investigation scoping needs. Engineering Bulletins that are
specific to issues related to Superfund sites and cleanups provide
the reader with synopses of important considerations required
either in the planning of the field investigation or in the decisions
leading to the selection of remediation technologies applicable
to a specific site. Addenda will be issued periodically to update
the onginal bulletins.
Abstract
This bulletin presents an overview discussion on the impor-
tance of and methods for controlling emissions into the air 'rom
materials handling processes at Superfund or other hazardous
waste sites. It also describes several techniques used for dust
and vapor suppression that have Deen applied at Superfund
sites.
Air emission control techniques have been utilized for
Superfund cleanups at the McColl site (CA) and at the LaSalle
Electnc site (II). Foam suppression has been used at Rocky
Mountain Arsenal (CO), Texaco Fillmore (CA), and at a petro-'
* (reference lumber, page number)
leum refinery (CA) site. A number of temporary vapor suppres-
sion techniques have also been applied at other sites. Addition-
ally, the experience gained in the mining industry anc at haz-
ardous waste treatment, storage, and disposal sites will yield
applicable methods for Superfund sites.
This bulletin provides information on the apolicabilicy of air
emission controls for materials handling at Superfund sites,
limitations of the current systems, a descnption of the control
methods that have found application to date, site require-
ments, a summary of the performance experience, the status of
the existing techniques and identification of future develop-
ment expectations, and sources of additional information.
Applicability of Materials Handling Controls
Estimation of the potential releases to the air and an analy-
sis of the impacts to the air pathway are applicable to every
activity in the Superfund process. Since nearly every Superfund
site has a potential air emissions problem, the focus of this
bulletin is to assist RPMs and OSCs in considcing the appropri-
ate methods for material handling at Superfund sites. To do
that, the first step is to estimate the potential releases using the
air pathway analysis (APA) process.
The amended National Contingency Plan expands upon
the requirement to conduct and fully document a regimented
process called an air pathway analysis (APA). The process is
defined as a "systematic approach involving a combination of
modeling and monitoring methods to assess actual or potential
receptor exposure to air contaminants" [1 p. 1-1]*. When
considering removal or remedial responses (i.e., technologies),
an APA detailing emission estimates is useful for cetermining
the potential compliance with applicable or relevant and ap-
propriate requirements (ARARs) during remedial action, par-
ticularly at a State or local level. Compliance with Natior.ai j
Ambient Air Quality Standards during a remediation or the i
excavation and processing of the contaminated media must be
addressed. With the passage of the Clean Air Act Amendments
in November 1990 and the advent of numerous state air toxics
programs, remediation of Superfund sites must acdress the
F-2
-------
Figure 1
Procedures for Conducting APA for Superfund
Application—Overview [1, p. 1-4]
Volume I
Application ol Air Pathway
Analyses lor Superfund Activities
• Identity Superfund Remedial
Activity and Source-Specific Need
for an APA
• Recommend APA Procedures for
Superfund Applications
• Reference Volumes ll-IV for
Supplemental Technical
Procedures/Recommendations
" i
Volume II
Procedures for
Developing Baseline Air
Emission Estimates
• Procedures for Baseline
Emission Estimates
(undisturbed & disturbed
sites)
• Emission Estimation
Techniques for Landfill
and Lagoons
Volume III
Procedures for Estimating
Air Emission Impacts from
Remedial Activities
• Procedures for
Estimating Emissions
from Remedial Activities
• Emission Estimation
Techniques for Waste
Treatment
Volume IV
Procedures for Dispersion
Modeling and Air
Monitoring
• Procedures for
Dispersion Modeling
and Monitoring
• Technical
Recommendations for
Modeling and
Monitoring
media transfer that excavation and materials handling (before
and after treatment) will create, and the ARARs these regula-
tions represent. Figure 1 [1, p. 1 -4] indicates the applicability of
the guidance study series documents on the air pathway analy-
sis to remedial project managers/on-scene coordinators and to
contractors and other technical staff.
The potential for short-term risk (i.e.,. during the remedial
action) is a major criterion when selecting the best remedial
alternative. The general classes of contaminants of concern are
gaseous and particulate emissions. Particulate matter (PM)
becomes airborne via wind erosion, mechanical disturbances
(such as excavation and material processing), combustion, and
desorption. Caseous species are primarily volatilized contami-
nants (VCs), but natural processes such as biodegradation and
photo-decomposition can result in releases once the site has
been disturbed. Since volatilization is the primary mechanism
for gaseous emissions, any volatile contaminant in the soil, a
lagoon, a landfill, or even in open containers may be released to
the air. The carcinogenic and noncarcinogenic hazards that
gases and particulates present in the air pathway must be
assessed.
When initially considering remediation technologies appli-
cable to a site, the APA process can play an integral role in
estimating the risk that excavation and materials processing
pose to the receptors in the area. Any ex situ process that
requires such excavation and material sizing, screening, or other
pretreatment processing will result in losses of particulate and
volatile contaminants.
Similarly, emissions generated during the operation of the
technology (i.e., losses from air pollution control equipment or
fugitive losses from the treatment process itself) must be esti-
mated in order to complete the air emissions source assessment
prior to final selection of the remedial technology. The ambient
concentrations of air contaminants may have to be monitored
during the remediation process to ensure compliance with local
air toxics regulations. All of these considerations should be
assessed, a cost estimate prepared, and the results should be-
come an integral input to the selection of alternative technolo-
gies according to the National Contingency Plan process. Of
these criteria, overall protection of human health and the envi-
ronment, ARAR compliance, implementability, cost, short-term
effectiveness and State and community acceptance become
paramount concerns for the air pathway impact.
Results of a recently published study [16] indicate significant
VC losses during typical soil excavation, transport, and feed/
preparation operations. The contribution of each remedial step
to the VC emissions was examined. Table 1 presents the results
for each step. Although different chemical constituents and
concentrations were present in two different site zones, the
contribution of each remedial step to the VC emissions during
2 Engineering Bulletin: Control of Air Emissions From Materials Handling During Remediation
F-3
-------
Table 1
Remedial Step Fractional
Contribution to VCs [16, p. 39]
Remedial Activity
Overall Site
Excavation
0.0509
Bucket
0.0218
Truck Filling
0.0905
Transport
0.3051
Dumping
0.5016
Incinerator
0.0014
Exposed Soil
0.0287
Total
1.0000
the excavation process remained constant. This contribution
was dependent on the parameters cf the soil and the remedial
activity pattern. At this site, dumping and temporary storage at
the incinerator accounted for 50 percent of the VC emissions,
transport from the excavation ione was the second highest
contributor of emissions. All activities were assumed to be
uncontrolled. The use of tarps and/or foam suppressants could
suDstantiallv reduce these emissions from transport and storace.
Limitations
The control methods for dust and vapor suppression rarely
remove 100 percent of the contaminants fron the air. These
releases have to be estimated, along with the cost estimate for
application of the control method to properly assess trie feasi-
bility of implementating the remediation technology being
considered. Site conditions determine the effectiveress of spe-
cific control methods.
Table 2
Common Control Technologies Available For
Materials Handling [*]
Remedial
Operation
Control Technology
Excavation Water sprays of active areas
Oust suppressants
Surfactants
Foam coverings
Enclosures
Aerodynamic considerations
Transportation Watersprays of active areas
Dust suppressants
Surfactants
Road carpets
Road oiling
Speed reduction
Coverings for loads
Water sprays of active areas
Water spray curtains over bed during
dumping
Dust suppressants
Surfactants
Windscreens
Orientation of pile
Slope of pile
Poam covering and other coverings
Dust suppressants
Aerodynamic considerations
Cover by structure with air
displacement and control
Grading Light water sprays
Surfactants
Waste feed/ Cover by structure with air
preparation displacement and control
Dumping
Storage (waste/
residuals)
Some methods have very limited periods of effectiveness,
making multiple applications or specialized formulations neces-
sary. The scheduling of media excavation and processing may
be impacted, for example, in matching the length of effective-
ness of a foam or spray suppression technique being jsed.
If gaseous emissions are expected to be high, or local
fugitive limitations apply, costly areal containment methods
may be required. If a very large site is to be excavated and the
materials classified or preprocessed, portable versions will
have to be designed for local air emission control. The use of
such portable containment strategies will affect the overall
schedule of the remediation and will mandate unique worker
safety plans to ensure that the proper level of protective
apparel and monitoring devices are used during the excava-
tion process.
Control Methods
A list of the most commonly used cont'ol technologies
applicable to VCs and PMs released during soils handling is
presented in Table 2 (1, p. 5-31 j.
Volatilization of contaminants from a hazardous waste site
may be controlled by reducing soil vapor pore volume or using
physical/chemical barriers [2, p. 116], The rate of volatilization can
be reduced by adding water to reduce the air-filled pore spaces or
by reduction of the spaces themsetves through compaction tech-
niques. Compaction, however, wouid displace the volatiles occu-
pying the free spaces (soil venting); water suppression might result
in mobilizing the contaminant into a groundwater medium if not
property applied. Wastes amenable to this form of suppression
inc'uCe most volatile organic (e.g., benzene, gasoline, phenols) and
inorganic (e.g., hydrogen sulfide, ammonia, radon, methyl mer-
cury) compounds in soil. Contaminants with a high vapor phase
mobility and low water phase partition potential are particularly
amenable to this vapor control technique. However, the :mtita!
application of water wiil force VCs from the soil-free spaces.
•Adapted from [1],
Engineering Bulletin: Control of Air Emissions From Materials Handling During Remediation
F-4
3
-------
Physical/chemical barriers have found broad utility in tem-
porary vapor and particulate control from hazardous waste sites
[3, p. 4-1 to 4-10]. Evaporation retardants such as foams may
be applied, while simpler windscreens, synthetic covers, and
water/surfactant sprays have been used during excavation and
transportation operations. The most exotic system applied to a
Superfund site included a special domed structure erected over
the excavation area and equipped with carbon adsorption beds
through which the internal vapors were drawn [4], The domed
structure was designed to limit emissions through the structure
and was capable of being transported to the next excavation
site when required. A similar structure may be necessary at the
point of materials processing, prior to a proposed incinerator
for the site. This facility might be fixed, provided a centralized
location for the incinerator can be established.
Site Requirements
General site conditions that dictate the estimated mag-
nitude of air emissions are provided in Table 4 [7, p. 16].
The requirements for implementation of the dust/vapor con-
trol techniques are a function of the estimated emissions
once these site conditions have been assessed. Baseline
estimation techniques are available for both undisturbed
and disturbed sites, as well as mathematical modeling and
actual direct measurement methods to verify estimates. Con-
sideration of the particular weather conditions relative to the
proposed remediation schedule is critical to efficient control of
air emissions. Tables 3 and 4 should be considered concurrently
when structuring an air emissions control strategy for the site
and the remediation activities.
Sound engineering practices include a multitude of methods
for vapor and dust suppression; these techniques are shown
in Table 3 [5, p. vi]. More than a dozen different techniques
have been identified. Several of the methods in Table 3 can
be used collectively to achieve fugitive emissions control.
Application of foams during excavation operations and tarps
for overnight storage can achieve a greater overall control
efficiency at significantly lower cost than the use of an
enclosure with carbon adsorption control. Good engineer-
ing practices employing the use of windscreens or other
aerodynamic considerations may provide adequate control
at some sites; other sites may require application of nearly
every method in the list. Cost estimates of many control
techniques for VCs are presented in Reference 6 [6, p. 68],
The cost estimates in Reference 6 are not specific to any
particular Superfund site. Cost estimates vary significantly
according to the site conditions, contaminant type, and
ARARs to be met. Table 3 presents a relative cost index for
illustrative purposes.
Table 3
Realtive PM/VC Supression Technologies
Suppression technique
Low
Medium
High
Cost
Minimize waste surface area
X
X
X
1
Aerodynamic considerations
X
1
• Windscreens
X
1
• Wind blocks
X
1
• Orientation of activities
X
1
Covers, mats, membranes,
and fill materials
X
X
2-3
Water application
X
X
2-3
Water/additives
X
X
2-3
Inorganic control agents
X
X
2-3
Organic dust control
X
2"3 i
Foam suppressants
X
X
7-10 '
Enclosures
X
10 j
Table 4
Important Parameters Affecting
Baseline Air Emission Levels [7]
Qualitative Effect*
I Parameter
Volatlles
L
Particulate
Matter
Site Conditions
Size of landfill or lagoon
!
I Amount of exposed waste
| Depth of cover on landfills
: Presence of oil layer
' Compaction of cover on
[ landfills
I Aeration of lagoons
; Ground cover
I Weather Conditions
! Wind speed
| Temperature
. Relative humidity
I Barometric pressure
j Precipitation
Solar radiation
I
Affects overall Affects overall
magnitude of magnitude
emissions, but of emissions,
not per area, but not per
area.
High
Medium
High
Medium
High
Medium
Medium
Medium
Low
Medium
High
Low
High
Medium
High
High
Low
High
Soil/Waste Characteristics
i Physical properties of waste
Adsorption/absorption
1 properties of soil
! Soil moisture content
: Volatile fraction of waste
: Semivolatile/nonvolatile
fraction of waste
Organic content of soil
i and microbial activity
; 'High, medium, and low in this table refer to the qualitative effect
that the listed parameter typically has on baseline emissions. 1
High
High
High
Low
High
High
High
Low
Low
Low
High
Low
High
Low
High
Low
High
Low
4
Engineering Bulletin: Control of Air Emissions From Materials Handling During Remediation
-------
Table 5
Summary o( VOC Air Emissions Control Technologies For Landfills [•]
Disadvantages
Control
Foams
Complete Enclosure/
Treatment System
Fill Material
Synthetic Membrane
Aerodynamic Modification
Minimum Surface Area, Shape
Water
Inorganic/Organic Control Agents
Advantages
• Easy to Apply
• Effective
• Allow for Control of Working Faces
• Can Reduce Decontamination
• May Provide the Highest Degree
of Control For Some Applications
• Inexpensive
• Equipment Usually Available
• Simple Approach
• Simple
• Lower Cost
• Low Maintenance
• Inexpensive
• Can Be Included in Plan
• Easy to Apply
• Similar to Foams
• Moderately Exoensive
• Requires Trained Operators
• High Cost
• Air Scrubbing Required
• High Potential Risk
• Must Work Inside Enclosure
• Hard to Seai Air-Tight
• No Control for Working Face
• Creates More Contaminated Soil
• Worker Contact with Waste
on Application
• Hard to Seal Air-Tight
• Variable Control
• Requires Additional Controls
• Limited Operational Data Exist
• Effective Range Limited
• Maintenance Required
• Must Maintain
• Canr.ot Always Dictate Shape
• A Potential Exists fcr Leaching
to Croundwater
• Not as Effective as Foams For
Working Areas
Fugitive VC/PM Collection Systems • Can Be Used in Active Areas
• Adapted from [14]
Performance Experience
A study of fugitive dust control techniques conducted with
test plots at an active cleanup area documented decreasing
effectiveness of foam suppressants within 2 to 4 weeks of applica-
tion. The effectiveness of water sprays on dump trucks and at the
loading site was in the 40 to 60 percent range for the site and 60
to 70 percent range for the truck [8, p. 2]. Surfactants increased
the effectiveness of the water sprays.
Foam suppressants have been thoroughly studied by at
least two vendors: 3M and Rusmar Foam Technology [9][10].
Laboratory data for highly volatile organic*, such as benzene
and trichloroethylene contaminated sand, indicated more than
99 percent suppression effectiveness for several days. Comple-
mentary data indicated better barrier performance of foams-
over 10-mil polyethylene film in controlling volatilization [11, p.
7 & 8]. A burning landfill was coused and the vapors sup-
pressed by more than 90 percent using foam at a site in jersey
City [12, p. 3]. Similarly, vapors from a petroleum waste site
were compared jsing three different test agents: temporary
foam, rigid urea-formaldehyde foam, and a stabilized foam.
The temporary foam yielded an average 81 percent control for
20 minutes, rigid foam produced 73 percent control for about
2 hours, and the stabilized foam was 99 percent effective for 24
hours after application [13, p. 4-7].
The performance data reported are specific to the sites
and contaminants controlled. There is no direct applicability of
the performance data to general Superfurd sites or conditions.
Table 5 presents a summary of VC air emissions control
technologies for landfills (14, p. 38], Many of the techniques
used can control fugitive particulate emissions as well.
Engineering Bulletin: Control of Air Emissions From Materials Handling During Remediation 5
F-6
-------
Technology Status
Acknowledgments
The use of vapor and particulate control techniques has
been directly applied to at least three Superfund sites: McColl
(California), Purity Oil Site (California), and LaSalle Electric (Illi-
nois). The McColl work is available as a Superfund Innovative
Technology Evaluation demonstration of excavation techniques.
Although the domed structure used controlled sulfur dioxide
and VOC releases to the atmosphere, working conditions within
the dome were difficult. High concentrations of dust and
contaminants mandated use of a high level of personal protec-
tive apparel. Consequently, personnel were able to work within
the dome for only short periods of time [15].
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIC) under
contract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work
Assignment Manager and primary author. The author is espe-
cially grateful to Mr. Michael Borst of EPA-RREL, who contrib-
uted significantly by serving as a technical consultant during
the development of this document.
A variety of dust and vapor control techniques may be
applied at Superfund sites. A systematic approach to estimate
the quantities of air emissions to be controlled, the ambient
impact, and the selection of the most appropriate control
technique requires a thorough understanding of the site, wastes,
emissions potential, and the most relevant combinations of
control methods.
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meetings and/or peer reviewing the document:
Mr. Edward Bates
Mr. ]im Rawe
Dr. Chuck Schmidt
Mr. Joe Tessitore
EPA-RREL
SAIC
Environmental Consultant
Cross, Tessitore & Associates
EPA Contact
Technology-specific questions regarding air emissions may
be directed to:
Mr. Michael Borst
U.S. EPA, Releases Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Ave., Building 10 (MS-104)
Edison, N| 08837-3679
Telephone FTS 340-6631 or (908) 321-6631
Engineering Bulletin: Control of Air Emissions From Materials Handling During Remediation
F-7
-------
REFERENCES
1. Office of Air Quality Planning and Standards, Air Super-
fund National Technical Guidance Study Series, Volume
1: Application of Air Pathway Analysis for Suoerfund
Activities. Intenm Final EPA/450/1 -89/001, U.S. Environ-
mental Protection Agency, 1989.
2. Review of In-Place Treatment Techniques for Contami-
nated Surface Soils, Voiume 1: Technical Evaluation. EPA;'
540/2-84/00Ba, U.S. Environmental Protection Agency,
1984.
3. Handbook — Remedial Action at Waste Disposal Sites
(Revised). EPA/626/6-85/006, U.S. Environmental
Protection Agency, 1985.
4. U.S. Environmental Protection Agency, Superfund
Innovative Technology Evaluation (SITE) Program. EPA/
540/8-91/005, 1991.
5. U.S. Environmental Protection Agency, Dust and Vapor
Suppression Technologies for Excavating Contaminated
Soils, Sludges, and Sediments • Draft Report, Contract
No. 68-03-3450, 1987.
6. Shen, T., et. al. Assessment and Control of VOC Emissions
from Waste Disposal Facilities Critical Reviews in Environ-
mental Control, 20 (1), 1990.
7. Office of Air Quality Planning and Standards, Air Super-
fund National Technical Guidance Study Series, Volume
2: Estimation off Baseline Air Emissions at Superfund Sites.
Interim Final EPA/450/1 -89/002, U.S. Environmental
Protection Agency, 1989.
8. U.S. Environmental Protection Agency Project Summary.
Fugitive Dust Control Techniques at Hazardous Waste
Sites: Results of Three Sampling Studies to Determine
Control Effectiveness, EPA/S40/S2-85/003, U.S. Environ-
mental Protection Agency, 1988.
9. Marketing Brochure, Rusmar Foam Technology, January
1991.
10. Aim, R., et.al. The Use of Stabilized Acueous Foams to
Suppress Hazardous Vapors — Study of f-actors Influenc-
ing Performance. Presented at the HMCRI Symposium,
November 16-18, 1987.
11. Olson, K. Emission Control at Hazardous Waste Sites
Using Stable, Non-Drainmg Aqueous Foams. Presented at
the 80th Annual Meeting of the Air & Waste Manage-
ment Association, ;une 20-24, 1988.
12. Aim, R. Using Foam to Maintain Air Quality During
Remediation of Hazardous Waste Sites. Presented at the
Annual Meeting of the Air Pollution Control Association,
June 1987.
1 3. Radian Corporation 3M Foam Evaluation for Vapor
Mitigation — Technical Memorandum. August 1986.
14. Radian Corporation. Air Quality Engineenng Manual for
Hazardous Waste Site Mitigation Activities — Revision #2
November 1987.
15. Schmidt, C.E. for USEPA- AEERL. The Effectiveness of
Foam Products for Controlling the Contaminants
Emissions from the Waste at McColl Site in Fullerton,
California — Technical Paper Draft. November, 1989.
16. U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards. Development of
Examoie P'ocedures for Evaluating the Air Impacts of Soil
Excavation Associated with Superfund Remedial Actions.
Draft Report, July 1990.
Engineering Bulletin: Control of Air Emissions From Materials Handling During Remediation
F-8
7
-------
United States Offlc« of Emergency and Office of
Environmental Protection Remedial Response Research and Development
Agency Washington, DC 20460 Cincinnati, OH 45268
Superfund EPA/S40/2-91/008 May 1991
A CD* Engineering Bulletin
'ft'** Thermal Desorption Treatment
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants and contaminants as a principal element." The Engi-
neering Bulletins are a series of documents that summarize
the latest information available on selected treatment and site
remediation technologies and related issues. They provide
summaries of and references for the latest information to help
remedial project managers, on-scene coordinators, contrac-
tors, and other site cleanup managers understand the type of
data and site characteristics needed to evaluate a technology
for potential applicability to their Superfund or other hazard-
ous waste site. Those documents that describe individual
treatment technologies focus on remedial investigation scoping
needs. Addenda will be issued periodically to update the
original bulletins.
Abstract
Thermal desorption is an ex situ means to physically
separate volatile and some semivolatile contaminants from
soil, sediments, sludges, and filter cakes. For wastes contain-
ing up to 10% organics or less, thermal desorption can be
used alone for site remediation. It also may find applications
in conjunction with other technologies or be appropriate to
specific operable units at a site.
Site-specific treatability studies may be necessary to
document the applicability and performance of a thermal
desorption system. The EPA contact indicated at the end of
this bulletin can assist in the definition of other contacts and
sources of information necessary for such treatability studies.
Thermal desorption is applicable to organic wastes and
generally is not used for treating metals and other inorganics.
Depending on the specific thermal desorption vendor se-
lected, the technology heats contaminated media between
200-1000°F, driving off water and volatile contaminants.
Offgases may be burned in an afterburner, condensed to
reduce the volume to be disposed, or captured by carbon
adsorption beds.
Commercial-scale units exist and are in operation. Ther-
mal desorption has been selected at approximately fourteen
Superfund sites [1 ]* [2], Three Superfund Innovative Technol-
ogy Evaluation demonstrations are planned for the next year.
The final determination of the lowest cost alternative will
be more site-specific than process equipment dominated.
This bulletin provides information on the technology applica-
bility, limitations, the types of residuals produced, the latest
performance data, site requirements, the status of the tech-
nology, and sources for further information.
Technology Applicability
Thermal desorption has been proven effective in treating
contaminated soils, sludges, and various filter cakes. Chemi-
cal contaminants for which bench-scale through full-scale
treatment data exist include primarily volatile organic com-
pounds (VOCs), semivolatiles, and even higher boiling point
compounds, such as polychlorinated biphenyls (PCBs)
[3][4][5][6], The technology is not effective in separating
inorganics from the contaminated medium. Volatile metals,
however, may be removed by higher temperature thermal
desorption systems.
Some metals may be volatilized by the thermal desorp-
tion process as the contaminated medium is heated. The
presence of chlorine in the waste can also significantly affect
the volatilization of some metals, such as lead. Normally the
temperature of the medium achieved by the process does not
oxidize the metals present in the contaminated medium [7, p.
85].
The process is applicable for the separation of organics
from refinery wastes, coal tar wastes, wood-treating wastes,
creosote-contaminated soils, hydrocarbon-contaminated soils,
mixed (radioactive and hazardous) wastes, synthetic rubber
processing wastes, and paint wastes [8, p. 2][4][9],
Performance data presented in this bulletin should not be
considered directly applicable to other Superfund sites. A
number of variables, such as the specific mix and distribution .
* [reference number, page number]
F-9
-------
Table I
RCRA Codes (or Wastes Treated
by Thermal Desorptlon
Wood Treating Wastes
K001
Dissolved Air Flotation (DAF) Float
K048
Slop Oil Emulsion Solids
KQ49
Heat Exchanger 8undles Cleaning Sludge
K050
American Petroleum Institute (API)
Separator Sludge
K0S1
Tank Bottoms (leaded)
K052
Table 2
Effectiveness of Thermal Desorptlon on
General Contaminant Groups for Soil,
Sludge, Sediments, and Filter Cakes
tffectivenesi
i
Sedi-
Filter
Contaminant Croups
Soil
Sludge
ments
Cakes
Halogenated volatile*
m
~
~
¦
Haiogenated semivolatiles
¦
~
~
¦
Nonhalogenated volatilcs
¦
~
~
¦
V
£
Nonhalogenated semivolatiles
¦
~
~
¦
o
PCBs
¦
~
~
~
o
Pesticides
¦
~
~
T
Dioxins/Furans
¦
~
T
T
Organic cyanides
~
~
~
T
Organic corrosives
~
~
3
3
Volatile metals
¦
T
~
T
Nonvolatile metals
~
3
3
3
c
o
Asbestos
~
3
~
3
?
s
Radioactrve materials
3
~
~
3
Inorganic corrosives
Q
Q
3
3
Inorganic cyanides
~
~
3
~
b
Oxidizers
3
3
3
3
s
w
at
Reducers
3
3
3
3
¦
Demonstrated Effectiveness: Successfuf treatabrt'tv test at some scale
competed
~
Potential Effectiveness: Expert option that technology wll wor*
J
No Exoected Effectiveness: Expert option :hat technoloay
Mill 'tOt
work
of contaminants, affect system performance. A thorough
characterization of the site and a well-cesigned and con-
ducted treatability study are highly recommended.
Table 1 lists the codes for the specific Resource Conserva-
tion and Recovery Act (RCRA) wastes that have been treated
by th:s technology [8, p. 2][4][9]. The indicated codes were
derived from vendor data where the objective was to dete--
m:ne thermal desorption effectiveness for these specific in-
dustrial wastes. The effectiveness of thermal desorption on
general contaminant groups for various matrices is shown in
Table 2. Examples of constituents within contaminant groups
are provided in "Technology Screening Guide For Treatment
of CERCLA Soils and Sludges" [7, p. 10]. This table is based on
the current available information or professional judgment
where no information was available. The proven effectiveness
of the technology for a particular site or waste does not ensure
that it will be effective at all sites or that the treatment
efficiencies achieved will be acceptable at other sites. For the
ratings used for this table, demonstrated effectiveness means
that, at some scale, treatability was tested to show the tech-
nology was effective for that particular contaminant and me-
dium. The ratings of potential effectiveness or no expected
effectiveness are both based upon expert judgment. Where
potential effectiveness is indicated, the technology is beiieved
capable of successfully treating the contaminant group in a
particular medium. When the technology is not applicable or
will probably not work for a particular combination of con-
taminant group and medium, a no expected effectiveness
rating is given. Another source of general observations and
average removal efficiencies for different treatability groups is
contained in the Superfund Land Disposal Restrictions (LDR)
Guide #6A, "Obtaining a Soil and Debris Treatability Variance
for Remedial Actions," (OSWER Directive 9347.3-06FS, Sep-
tember 1990) [10] and Superfund LDR Guide #6B, "Obtain-
ing a Soil and Debris Treatability Variance for Removal Ac-
tions," (OSWER Directive 9347.3-06BFS, September 1990)
[11].
Limitations
The primary technical factor affecting thermal desorption
performance is the maximum bed temperature achieved. Since
the basis of the process is physical removal from the medium
by volatilization, bed temperature directly determines which
organics will be removed.
The contaminated medium must contain at least 20 per-
cent solids to facilitate placement of the waste material into
the desorption equipment (3, p. 9]. Some systems specify a
minimum of 30 percent solids [12, p. 6].
As the medium is heated and passes through the kiln or
desorber, energy is lost in heating moisture contained in the
contaminated soil. A very high moisture content can result in
low contaminant volatilization or a need to recycle the soil
through the desorber. High moisture content, therefore,
causes increased treatment costs.
Material handling of soils that are tightly aggregated or
largely day, or that contain rock fragments 0' panicles greater
than 1-1.5 inches can result in poor processing performance
due to caking. Also, if a high fraction of fine silt or clay exists
in the matrix, fugitive dusts will be generated [7, p. 831 and a
create' dust loading will be placed on the downstream air
pollution control equipment [12, p. 6).
The treated medium will typically contain less than 1
percent moisture. Dust can easily form in the transfer of the
treated medium from the desorption unit, but car. be mitigated
by water sprays. Normally, clean water from air pollution
control cevices can be used for this purpose.
Although volatile organics are the primary.target.of the-
thermal desorption technology, tr.e total organic loading is
limited by some systems to up ;o '-0 percent or less [1 3, p. II-
2
Engineering Bulletin: Thermal Desorption Treatment
F-10
-------
30], As in most systems that use a reactor or other equipment
to process wastes, a medium exhibiting a very high pH (greater
than 11) or very low pH (less than 5) may corrode the system
components [7, p. 85].
There is evidence with some system configurations that
polymers may foul and/or plug heat transfer surfaces [3, p. 9],
Laboratory/field tests of thermal desorption systems have
documented the deposition of insoluble brown tars (presum-
ably phenolic tars) on internal system components [14, p.
76],
High concentrations of inorganic constituents and/or
metals will likely not be effectively treated by thermal desorp-
tion. The maximum bed temperature and the presence of
chlorine can result in volatilization of some inorganic constitu-
ents in the waste, however.
Technology Description
Thermal desorption is any of a number of processes that
use either indirect or direct heat exchange to vaporize organic
contaminants from soil or sludge. Air, combustion gas, or
inert gas is used as the transfer medium for the vaporized
components. Thermal desorption systems are physical sepa-
ration processes and are not designed to provide high levels
of organic destruction, although the higher temperatures of
some systems will result in localized oxidation and/or pyroly-
sis. Thermal desorption is not incineration, since the destruc-
tion of organic contaminants is not the desired result. The
bed temperatures achieved and residence times designed
into thermal desorption systems will volatilize selected con-
taminants, but typically not oxidize or destroy them. System
performance is typically measured by comparison of untreated
soil/sludge contaminant levels with those of the processed
soil/sludge. Soil/sludge is typically heated to 200 - 1000° F,
based on the thermal desorption system selected.
Figure 1 is a general schematic of the thermal desorption
process.
Waste material handling (1) requires excavation of the
contaminated soil or sludge or delivery of filter cake to the
system. Typically, large objects greater than 1.5 inches are
screened from the medium and rejected. The medium is then
delivered by gravity to the desorber inlet or conveyed by
augers to a feed hopper [8, p. 1],
Significant system variation exists in the desorption step
(2). The dryer can be an indirectly fired rotary asphalt kiln, a
single (or set of) internally heated screw auger(s), or a series of
externally heated distillation chambers. The latter process
uses annular augers to move the medium from one volatiliza-
tion zone to the next. Additionally, testing and demonstration
data exist for a fluidized-bed desorption system [12].
The waste is intimately contacted with a heat transfer
surface, and highly volatile components (including water) are
driven off. An inert gas, such as nitrogen, may be injected in a
countercurrent sweep stream to prevent contaminant com-
bustion and to vaporize and remove the contaminants [8, p.
1][4], Other systems simply direct the hot gas stream from
the desorption unit [3, p. 5][5],
The actual bed temperature and residence time are the
primary factors affecting performance in thermal desorption.
These parameters are controlled in the desorption unit by
using a series of increasing temperature zones [8, p. 1 ], mul-
tiple passes of the medium through the desorber where the
operating temperature is sequentially increased, separate
compartments where the heat transfer fluid temperature is
higher, or sequential processing into higher temperature zones
[15][16], Heat transfer fluids used to date include hot com-
bustion gases, hot oil, steam, and molten salts.
Offgas from desorption is typically processed (3) to re-
move particulates. Volatiles in the offgas may be burned in an
afterburner, collected on activated carbon, or recovered in
condensation equipment. The selection of the gas treatment
system will depend on the concentrations of the contaminants,
cleanup standards, and the economics of the offgas treat-
ment system(s) employed.
Figure 1
Schematic Diagram of TTiermai Desorption
Clean Offgas
Concentrated Contaminants
Water
Oversized Refects
Excavate
Gas Treatment
System
Matena)
Handling
Engineering Bulletin: Thermal Desorption Treatment
F-ll
-------
Process Residuals
Operation of thermal desorption systems typically cre-
ates up to six process residuaf streams: treated medium,
oversized medium rejects, condensed contaminants and wa-
ter, particulate control system dust, clean offgas, and soent
caroon (if used). Treated medium, debris, and oversized
rejects may be suitable for return onsite.
Condensed water may be used as a dust suppressant for
the treated medium. Scrubber purge water can be purified
and returned to the site wastewater treatment facility (if
available), disposed to the sewer [3, p. 8] [8, p. 2} (4, p. 2], or
used for rehumidification and cooling of the hot, dusty me-
dia. Concentrated, condensed organic contaminants are
containerized for further treatment or recovery.
Dust collected from particulate control devices may be
combined with the treated medium or, depending on analy-
ses for carryover contamination, recycled through the des-
orption unit.
Clean offgas is released to the atmosphere. If used, spent
carbon may be recycled by tne original supplier or other such
processor.
Site Requirements
Thermal desorption systems are transported typically on
specifically adapted flatbed semitrailers. Since most systems
consist of three components (desorber, particulate control,
and gas treatment), space requirements on site are typically
less than 50 feet by 150 feet, exclusive of materials handling
and decontamination areas.
Standard 440V, three-phase electrical service is needed-
Water must be available at the site. Tne quantity of water
needed is vendor and site specific.
Treatment of contaminated soils or other waste materials
require that a site safety plan be developed to provide for
personnel protection anc special handling measures. Storage
should be provided to hold the process product streams until
they have been tested to determine their acceptability for
disposal or release. Depending upon the site, a method to
store waste that has been prepared for treatment may be
necessary. Storage caoacity will depend on waste volume.
Table 3
PCB Contaminated Soils
Pilot XTRAX™ [4]
feed
Product
Removal
Matrix
(ppm)
(ppm)
(%)
Clay
5,000
24
99.3
Silty Clay
2,800
19
99.5
Clay
1,600
4.8
99.7
Sandy
1,480
8.7
99.)
Cay
630
17
97.3
Onsite analytical equipment capable of determ.nirg site-
specific organic compounds for performance assessment make
the operation more efficient and provide better information
for process control.
Performance Data
Several thermal desorotion vendors report performance
data for their respective systems ranging from laboratory
treataoility studies to full-scale operation at designated
Superfund sites [17](9][18]. The cuality of this information
has net been determined. These data are included as a
general guideline to the performance of thermal desorption
eGuipment, and may not be directly transferable to a specific
Superfunc site. Good site characterization and treatability
studies are essential in further refining and screening the
thermal desorption technology.
Chem Waste Management's (OVM's) X'TRAX™ System
has been tested at laboratory and pilot scale. Pilot tests were
performed at CWM's Kettleman Hills facility in California.
Twenty tons of PC&- and organic-contaminated soils were
processed through tne 5 TPD pilot system. Tables 3 and 4
present the results of PCB separation from soil and total
hydrocarbon emissions from the system, respectively ;4J.
During a non-Superfund project for the Department of
Defense, thermal desorption was used in a full-scale demon-
stration at the Tinker Air Force 3ase in Oklahoma. The success
of this project led to the patenting of the process by Weston
Services, Inc. Since then, Weston has applied its low-tern-
perature thermal treatment (LT{) system to various contami-
nated soils at bench-scale through full-scale projects [19].
Table 5 presents a synopsis of system and performance data
for a full-scale treatment of soil contaminated with No. 2 fuel
oil and gasoline at a site in Illinois.
Cancnie Environmental has extens've performance data
for its Low Temperature Tr.ermai Aeration (LTTASM) system at
full-scale operation (15-20 cu. yds. per hour). The LTTasm has
been applied at the McKin (Maine), Ottati anc Goss (New
Hampshire) and Cannon Engineering Corp. (Massachusetts)
Superfund sites. Additionally, the LTTA4M has been used at
the privatety-funded site in South Kearney (New Jersey). Table
Table 4
Pilot X'TRAX^
TSCA Testing • Vent Emissions [4]
Total Hydro
-------
6 presents a summary of Canonie LTTASU data [5], The Can-
non Engineering (Mass) site, which was not included in Table
6, successfully treated a total of 1 1,330 tons of soil, containing
approximately 1803 lbs. of VOC [20].
T.D.I. Services, Inc. has demonstrated its HT-5 Thermal
Distillation Process at pilot- and full-scale for a variety of RCRA-
listed and other wastes that were prepared to simulate Ameri-
can Petroleum Institute (API) refinery sludge [8]. The com-
pany has conducted pilot- and full-scale testing with the API
sludge to demonstrate the system's ability to meet Land 8an
Disposal requirements for K048 through K052 wastes. Inde-
pendent evaluation by Law Environmental confirms that the
requirements were met, except for TCLP levels of nickel,
which were blamed on a need to "wear-in" the HT-5 system
[21, p. ii].
Remediation Technologies, Inc. (ReTec) has performed
numerous tests on RCRA-listed petroleum refinery wastes.
Table 7 presents results from treatment of refinery vacuum
Table 5
Full-Scale Performance Results
for the LT3 System [19]
Range of
Soil Range
Treated Range
Removal ¦
Contaminant
(ppb)
(PPt>)
Efficiency I
Benzene
1000
5.2
99.5
Toluene
24000
5.2
99.9
Xylene
110000
<1.0
>99.9 '
Ethyl benzene
20000
4.8
99.9
Napthalene
4900
<330
>99.3
Corcinogenic
j
j
Priority PNAs
<6000
<330-590
<90.2-94.5
Non-carcinogenic
]
Priority PNAs
890-6000
<330-450
<62.9-94.5
Table 6
Summary Results of the ITTASM
Full-Scale Cleanup Tests [S]
1
Contam-
Soil
Treoted
: Site
Processed
inant
(ppm)
(ppm)
'¦ S. Kearney
16000 tons
vOCs
PAHs
177.0(avg.)
35.31 (avg.)
0.87 (avQ.)
10.1 (avg.)
McKin
>9500 cu yds
2000 cu yds
VOCs
PAHs
ND-3310
NO-0.04
<10
; Ottdti {*
Goss
4500 cu yds
VOCs
1 500 (avg.)
<0.2 (avg )
Table 7
ReTec Treatment Results-Refinery
Vacuum Filter Cake (A) [3]
Table 8
ReTec Treatment Results-Creosote
Contaminated Clay [3]
Original
Treated
Removal
Original
Treated
Removal
Sample
Sample
Efficiency 1
Sample
Sample
Efficiency
Compound
(ppm)
(ppm)
w
Compound
(ppm)
(ppm)
(%)
Naphthalene
<0.1
<0.1
:
Naphthalene
1321
<0.1
>99 9
Acenaphthylene
<0.1
<0.1
-
Acenaphthylene
<0.1
<0.1
Acenaphthene
<0.1
<0.1
...
Acenaphthene
293
<0.1
>99.96
Fluorene
10.49
<0.1
>98.9
Fluorene
297
<0.1
>99.96
Phenanthrene
46.50
<0.1
>99.3
1 Phenanthrene
409
1.6
99.6
Anthracene
9.80
<0.1
>96.6 !
Anthracene
113
<0.1
>99.7
Fluoranthrene
73.94
<0.1
>99.8
Fluoranthrene
553
1.5
99.7
Pyrene
158.37
<0.1
>99.9 j
Pyrene
495
2.0
99.6
6cnzo(b)anthracene
56.33
1.43
97.5
Benzo(b)anthracene
59
<0.1
>99.99
Chrysene
64.71
<0.1
>99.9
Chrysene
46
<0.1
>99.8
Benzo(b)fluoranthene
105.06
2.17
97.9
Benzo(b)fluoranthene
14
2.5
82.3
Benzo(k)fluoranthene
225.37
3.64
98.4
Benzo(k)f!uoranthene
14
<0.1
>99.8
8enzo(a)pyrene
1 74.58
1.89
98.9
Benzo(a)pyrene
15
<0.1
>99 9
Oibenz(ab)antracene
477.44
10.25
97.8
Dibenzo(ab)anthracene
<0.1
<0.1
...
Benzo(ghi)perylene
163.53
5.09
96.6
Benzo(ghi)perylene
7
<0.1
>99 4
lndeno(12399.3
Treatment Temperature: 450°F
Treatment Temperature: 500°F
Engineering Bulletin: Thermal Desorption Treatment
F-13
-------
Table 9
ReTec Treatment Resufts-Coal Tar
Contaminated Soils [3]
Compound
Original
Sample
(ppm)
Treated
Sample
(ppm)
Removal
Efficiency
(%)
Benzene
1.7
<0.1
>94
Toluene
2.3
<0.1
>95
Ethyl benzene
1.6
<0.1
>93
Xylenes
6.3
<0.3
>95
Naphthalene
367
<1.7
>99
Pluorene
114
<0.2
>99
Phenanthrene
223
18
91.9
Anthracene
112
7.0
93.8
Fluoranthrene
214
15
93.0
Pyrene
110
11
90.0
Benzo(b)anthracer.e
56
<1.4
>97
Chrysene
58
3.7
93.6
Benzo(b)fluoranthene
45
<1.4
>97
Benzo(k)fluoranthene
35
<2.1
>94
Benzo(a)pyrene
47
<0.9
>98
Benzo(ghi)perylene
24
<1.1
>95
IndenoO 2 3-77
Treatment Temperature
i
i °
1
1
filter cake. Tests with creosote-contaminated clay and coal
tar-contaminated soils showed significant removal efficiencies
(Tables 8 and 9). All data were obtained through use of
ReTec's 100 Ib/h pilot scale unit processing actual Industrial
process wastes [3].
Recycling Sciences International, Inc. (formerfy American
Toxic Disposal, Inc.) has tested its Desorption and Vaporiza-
tion Extraction System (DAVES), formerfy called the Vaporiza-
tion Extraction System (VES), at Waukegan Harbor, Illinois.
The pilot-scale test demonstrated PC3 removal from material
containing uo to 2S0 parts per million (ppm) to levels less
tnan 2 ppm (12].
RCRA LDRs that require treatment of wastes to best dem-
onstrated available technology (BDAT) levels prior to iand
disposal may sometimes be determined :o be applicable or
relevant and appropriate requirements for CERCLA response
actions. Thermal desorption can produce a treated waste
that meets treatment levels set by BDAT but may not reach
t"ese treatment levels in all cases. The ability to meet re-
quired treatment levels is dependent upon the specific waste
constituents and the waste matrix. In cases where thermal
desorption does not meet these levels, it still may, in certain
situations, be selected for use at the site if a treatability
variance establishing alternative treatment levels is obtainea.
Treataoility variances are justified for handling complex soil
and debris matrices. The following guides describe when and
how to seek a treatability variance for soil and debris:
Superfund LDR Guide #6A, "Obtaining a Soii and Debris
Treataoility Variance for Remedial Actions" (OSWER Directive
9347.3-06FS, September 1990) (10], and Superfund LDR Cjide
#6B, "Obtaining a Soil and Debris Treatability Variance for
Removal Actions" (OSWER Directive 9347 3-06BFS, Septem-
ber 1990) [11]. Another approach could be to use other
treatment techniques in series with thermal desorption to
obtain desired treatment levels.
Technology Status
Significant theoretical research is ongoing [22]|23], as
well as direct demonstration of thermal desorption through
both treatability testing and full-scale cleanups.
A successful pilot-scale demonstration of |apanese soils
"roasting" was conducted in 1980 for trie recovery of mercury
from highly contaminated (up to 15.6 percent) soils at a plant
site in Tokyo. The high concentration of mercury made
recovery and refinement to commercial grade (less than 99.99
percent purity) economically feasible [24],
In this country, thermal desorption technologies are the
selected remedies for one or more operable units at fourteen
Superfund sites. Table 10 lists each site's location, pnmarv
contaminants, and present status [1][2].
Most of the hardware components of thermal desorption
are available off tr.e sheif anc represent no significant proolem
of availability. The engineenng and configuration of the
systems are similarly refined, such that once a system is de-
signed full-scale, little or no prototyping or redesign is required.
On-line availability of the full-scale systems described in
this bulletin is not documented. However, since the ex situ
system can be operated in batch mode, t is expected that
component failure can be identified and spare components
fitted quickly for minimal downtime.
Several vendors have documer-tec processing costs per
ton of feed processed. The overall range vares from $80 to
J350 per ton processed [6][4, p. 12][5][3, p. 9], Caution is
recommendec in using costs out of context because tne base
year of the estimates vary. Costs also are highly variable due
to the quantity of waste :o be processed, term of the reme-
diation contract, moisture content, organic constituency of
the contaminated medium, anc cleanup standards to be
achieved. Similarly, cost estimates should include such items
as preparation of Work Plans, permitting, excavation, pro-
cessing itself, QA/QC verification of treatment pe^ormance.
and reporting of data.
EPA Contact
Technology-specific questions regarding thermal cescrp-
tion may be directed to:
Michael Cruenfeld
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Releases Control 8ranch
2890 Woodbridge Ave. • _
Bldg. 10 (MS-104)
Edison, N] 08837
FTS 340-6625 or (908) 321-662S
6
F-14
Engineering Bulletin: Thermal Desorption Treatment
-------
Table 10
Superfund Sites Specifying Thermal Oesorption as the Remedial Action
Site
Location
Primary Contaminants
Status
Cannon Engineering
(Bridgewater Site)
Bridgewater, MA (1)
VOCs (Benzene, TCE &
Vinyl Chloride)
Proiect completed 10/90
McKin
Ottati & Goss
McKin, ME (1)
New Hampshire (1)
VOCs (TCE. BTX)
VOCs (TCE; PCE; 1, 2-DCA,
and Benzene)
Proiect completed 2/87
Project completed 9/89
Wide Beach
Brandt, NY (2)
PCBs
In design
• pilot study available 5/91
Metaltec/Aerosystems
Franklin Borough, N| (2)
TCE and VOCs
In design
• remedial design complete
• remediation starting Fall '91
Caldwell Trucking
Outboard Marine/
Waukegan Harbor
Reich Farms
Re-Solve
Fairfield, NJ (2)
Waukegan Harbor, 1L (5)
Dover Township, N| (02)
North Dartmouth, MA(1)
VOCs (TCE, PCE, and TCA)
PCBs
VOCs and Semivolatiles
PCBs
In design
In design
• treatability studies complete
Pre-design
In design
• pilot study June/|uly'91
Waldick Aerospace
Devices
New Jersey (2)
TCE and PCE
In design
Wamchem
Burton, SC (4)
BTX and SVOCs
(Naphthalene)
in design
• pilot study available 5/91
Fulton Terminals
Fulton, NY (2)
VOCs (Xylene, Styrene, TCE,
Ethylbenzene, Toluene) and
some PAHs
Pre-design
Stautfer Chemical
Stauffer Chemical
Cold Creek, AL (4)
Le Moyne. AL (4)
VOCs and pesticides
VOCs and pesticides
Pre-design
Pre-design
Acknowledgements
This bulletin was prepared for the U.S. Environmental
Protection Agency, Office of Research and Development
(ORD), Risk Reduction Engineering Laboratory (RREL), Cin-
cinnati, Ohio, by Science Applications International Corpora-
tion (SAIC) under contract no. 68-C8-0062. Mr. Eugene
Harris served as the EPA Technical Project Monitor. Mr. Gary
Baker (SAIC) was the Work Assignment Manager and author
of this bulletin. The author is especially grateful to Mr. Don
Oberacker, Ms. Pat Laforrrava, and Mr. Paul de Percin of EPA,
RREL, who have contributed significantly by serving as tech-
nical consultants during the development of this document.
The following other Agency and contractor personnel
have contributed their time and comments by participating in
the expert review meetings and/or peer reviewing the docu-
ment:
Dr. James Cudahy
Mr. James Cummings
Dr. Steve Lanier
Focus Environmental, Inc.
EPA-OERR
Energy and Environmental
Research Corp.
Ms. Evelyn Meagher-Hartzell SAIC
Mr. James Rawe SAIC
Ms. Tish Zimmerman EPA-OERR
Engineering Bulletin: Thermal Desorption Treatment
F-15
7
-------
REFERENCES
1. Innovative Treatment Technologies: Semi-Annual Status
Report, EPA/540/2-91/001, U.S. Environmental Protec-
tion Agency, Technology Innovation Office, Jan. 1991.
2. Personal communications with various EPA Regional
Project Managers, April, 1991.
3. Abnshamian, Ramin. Thermal Treatment of Refinery
Sludges and Contaminated Soils. Presented at Ameri-
can Petroleum Institute, Orlando, Florida, 1990.
4. Swanstrom, C., and C. Palme. X'TRAX™ Transportable
Thermal Separator for Organic Contaminated Solids.
Presented at Second Forum on Innovative Hazardous
Waste Treatment Technologies: Domestic and Interna-
tional, Philadelphia, Pennsylvania, 1990.
5. Canonie Environmental Services Corp, Low Temperature
Thermal Aeration (LTTASM) Marketing Brochures, circa
1990.
6. Nielson, R., and M. Cosmos. Low Temperature Thermal
Treatment (LT3) of Volatile Organic Compounds from
Soil: A Technology Demonstrated. Presented at the
American Institute of Chemical Engineers Meeting,
Denver, Colorado, 1988.
7. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
tal Protection Agency, 1988.
8. T.D.I. Services, Marketing Brochures, circa 1990.
9. Cudahy,)., and W. Troxler. 1990. Thermal Remedia-
tion Industry Update - II. Presented at Air and Waste
Management Association Symposium on Treatment of
Contaminated Soils, Cincinnati, Ohio, 1990.
10. Superfund LDR Guide #6A: (2nd Edition) Obtaining a
Soil and Debris Treatability Variance for Remedial
Actions. Superfund Publication 9347.3-06FS, U.S.
Environmental Protection Agency, 1990.
11. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. Superfund
Publication 9347.3-06BFS, U.S. Environmental Protec-
tion Agency, 1990.
12. Recycling Sciences International, Inc., DAVES Marketing
Brochures, circa 1990.
13. The Superfund Innovative Technology Evaluation
Program — Progress and Accomplishments Fiscal Year
1989, A Third Report to Congress, EPA/540/5-90/001,
U.S. Environmental Protection Agency, 1990.
14. Superfund Treatability Clearinghouse Abstracts. EPA/
540/2-89/001, U.S. Environmental Protection Agency,
1989.
15. Soil Tech, Inc., AOSTRA - Taciuk Processor Marketing
Brochure, circa 1990.
16. Ritcey, R., ar.d F. Schwartz. Anaerobic Pyrolysis of
Waste Solids and Sludges — The AOSTRA Taciuk Process
System. Presented at Environmental Hazards Confer-
ence and Exposition, Seattle, Washington, 1990.
17. The Superfund Innovative Technology Evaluation
Program: Technology Profiles. EPA/540/5-89/01 3,'U.S.
Environmental Protection Agency, 1989.
18. |ohnson, N., and M. Cosmos. Thermal Treatment
Technologies for Haz Waste Remediation. Pollution
Engineering, XXI(ll): 66-85, 1989.
19. Weston Services, Inc, Project Summaries (no date).
20. Canonie Environmental Services Corporation, Draft
Remedial Action Report - Cannons Bridgewater
Superfund Site, February 1991.
21. Onsite Engineering Report for Evaluation of the HT-5
High Temperature Distillation System for Treatment of
Contaminated Soils — Treatability Test Results for a
Simulated K051 API Separator Sludge, Vol 1: Executive
Summary, Law Environmental, 1990.
22. Lighty, J., et al. The Cleanup of Contaminated Soil by
Thermal Desorption. Presented at Second International
Conference on New Frontiers for Hazardous Waste
Management. EPA/600/9-87/018f, U.S. Environmental
Protection Agency, 1987. pp. 29-34.
23. Fox, R., et al. Soil Decontamination by Low-Tempera-
ture Thermal Separation. Presented at the DOE Model
Conference, Oak Ridge, Tennessee, 1989.
24. Ikeguchi, T., and S. Gotoh. Thermal Treatment of
Contaminated Soil with Mercury. Presented at Demon-
stration of Remedial Action Technologies for Contami-
nated Land and Groundwater, NATO/CCMS Second
International Conference, Bilthoven, the Netherlands,
1988. pp. 290-301.
8
Engineering Bulletin: Thermal Desorption Treatment
F-16
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United Slates Office of Emergency and Office of
Environmental Protection Remedial Response Research and Development
Agency Washington, DC 20460 Cincinnati, OH 45268
Superfund EPA/540/2-91/006 May 1991
Engineering Bulletin
&EPA In Situ Soil Vapor Extraction
Treatment
Purpose
Section 121 (b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element." The Engi-
neering Bulletins are a series of documents that summarize
the latest information available on selected treatment and site
remediation technologies and related issues. They provide
summaries of and references for the latest information to help
remedial project managers, on-scene coordinators, contrac-
tors, and other site cleanup managers understand the type of
data and site characteristics needed to evaluate a technology
for potential applicability to their Superfund or other hazard-
ous waste site. Those documents that describe individual
treatment technologies focus on remedial scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
Soil vapor extraction (SVE) is designed to physically re-
move volatile compounds, generally from the vadose or un-
saturated zone. It is an in situ process employing vapor
extraction wells alone or in combination with air injection
wells. Vacuum blowers supply the motive force, inducing air
flow through the soil matrix. The air strips the volatile com-
pounds from the soil and carries them to the screened ex-
traction well.
Air emissions from the systems are typically controlled by
adsorption of the volatiles onto activated carbon, thermal
destruction (incineration or catalytic oxidation), or condensa-
tion by refrigeration [1, p. 26].*
SVE is a developed technology that has been used in
commercial operations for several years. It was the selected
remedy for the first Record of Decision (ROD) to be signed
under the Superfund Amendments and Reauthorization Act
of 1986 (the Verona Well Field Superfund Site in Battle Creek,
* [reference number, page number]
Michigan). SVE has been chosen as a component of the ROD
at over 30 Superfund sites [2] [3] [4] [5] [6].
Site-specific treatability studies are the only means of
documenting the applicability and performance of an SVE
system. The EPA Contact indicated at the end of this bulletin
can assist in the location of other contacts and sources of
information necessary for such treatability studies.
The final determination of the lowest cost alternative will
be more site-specific than process equipment dominated.
This bulletin provides information on the technology applica-
bility, the limitations of the technology, the technology de-
scription, the types of residuals produced, site requirements,
the latest performance data, the status of the technology, and
sources for further information.
Technology Applicability
In situ SVE has been demonstrated effective for removing
volatile organic compounds (VOCs) from the vadose zone.
The effective removal of a chemical at a particular site does
not, however, guarantee an acceptable removal level at all
sites. The technology is very site-specific. It must be applied
only after the site has been characterized. In general, the
process works best in well drained soils with low organic
carbon content. However, the technology has been shown to
work in finer, wetter soils (e.g., clays), but at much slower
removal rates [7, p. 5],
The extent to which VOCs are dispersed in the soil—
vertically and horizontally—is an important consideration in
deciding whether SVE is preferable to other methods. Soil
excavation and treatment may be more cost effective when
only a few hundred cubic yards of near-surface soils have
been contaminated. If volume is in excess of 500 cubic yards,
if the spill has penetrated more than 20 or 30 feet, or the
contamination has spread through an area of several hundred
square feet at a particular depth, then excavation costs begin
to exceed those associated with an SVE system [8] [9]
[10, p. 6].
The depth to groundwater is also important. Groundwa-
ter level in some cases may be lowered to increase the volume
of the unsaturated zone. The water infiltration rate can be_
F-17
-------
Tabto 1
Eff*cttv*nMs of SVE on G*n«ral
Contaminant Groups For Soil
Contaminant Croups
Effectiveness
Soil
\
Halogenated volatiles
Halogenated semivolatiles
Nonhatogenated volatiles
Nonhalogenated semivolaties
PCBs
Pestiodes
Dtoxins/Purans
Organic cyanides
Organic corrosives
U
~
¦
¦
a
~
~
a
~
Volatile metals
Nonvolatile meuis
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
~
~
3
3
3
3
<
»
j
!
Oxidizers
Reducers
3
~
¦ Demonstrated Effectiveness: Successful treatability test at some
i scale completed
(~ Potential Effectiveness: Expert opinion that technology will wot*
~ No Expected Effectiveness: Expert opinion that technology will not
! wort:
controlled by placing an impermeable cap over the site. Soil
heterogeneities influence air movement as well as the loca-
tion of chemicals. The presence of heterogeneities may make
it more difficult to position extraction and inlet wells. There
generally will be significant differences in the air permeability
of the vanous soil strata which will affect the optimum design
of the SVE facility. The location of the contaminant on a
property and the type and extent of development in the
vicinity of the contamination may favor the installation of an
SVE system. For example, if the contamination exists beneath
a building or beneath an extensive utility trench network, SVE
should be considered.
SVE can be used alone or in combination with other
technologies to treat a site. SVE, in combination with
groundwater pumping and air stripping, is necessary when
contamination has reached an aquifer. When the contamina-
tion has not penetrated into the zone of saturation (i.e.,
below the water table), it is not necessary to install a ground-
water pumping system. A vacuum extraction well will cause
the water table to rise and will saturate the soil in the area of
the contamination. Pumping is then required to draw the wa-
ter table down and allow efficient vapor venting [11, p. 169].
SVE may be used at sites not requiring complete remedia-
tion. For example, a site may contain VOCs and nonvolatile
contaminants. A treatment requiring excavation might be
selected for the nonvolatile contaminants. If the site required
excavation in an enclosure to protect a nearby populace from
VCXI emissions, it would be cost effective to extract the volatiles
from the soil before excavation. This would obviate the need
for the enclosure. In this case it would be necessary to vent
the soil for only a fraction of the time required for complete
remediation.
Performance data presented in this bulletin should not be
considered directly applicable to other Superfund sites. A
number of variables such as the specific mix and distribution
of contaminants affect system performance. A thorough
characterization of the site and a well-designed and conducted
treatability study are highly recommended.
The effectiveness of SVE on general contaminant groups
for soils is shown in Table 1. Examples of constituents within
contaminant groups are provided in the "Technology Screen-
ing Guide For Treatment of CERCLA Soils and Sludges' [12].
This table is based on the current available information or
professional judgment where no information was available.
The proven effectiveness of the technology for a particular site
or waste does not ensure that it will be effective at aH sites or
that the treatment efficiencies achieved will be acceptable at
other sites. For the ratings used in this table, demonstrated
effectiveness means that, at some scale, treatability tests showed
that the technology was effective for that particular contami-
nant and matrix. The ratings of potential effectiveness, or no
expected effectiveness are both based upon expert judgment.
Where potential effectiveness is indicated, the technology is
believed capable of successfully treating the contaminant group
in a particular matrix. When the technology is not applicable
or will probably not wort; for a particular combination of
contaminant group and matrix, a no-expected-effectiveness
rating is given. Another source of general observations and
average removal efficiencies for different treatability groups is
contained in the Superfund Land Disposal Restrictions (LDR)
Guide #6A, 'Obtaining a Soil and Debris TreatabilityVariance
for Remedial Actions," (OSWER Directive 9347.3-06FS, July
1989) [1 3] and Superfund LDR Guide #68, "Obtaining a Soil
and Debris Treatability Variance for Removal Actions," (OSWER
Directive 9347.3-07FS, December 1989) [14],
Limitations
Soils exhibiting low air permeability are more difficult to
treat with In situ SVE. Soils with a high organic carbon
content have a high sorption capacity for VOCs and are more
difficult to remediate successfully with SVE. Low soil tem-
perature lowers a contaminant s vapor pressure, making vola-
tilization more difficult [11 ].
Sites that contain a high degree of soil heterogeneity will
likely offer variable flow and desorption performance, which
will make remediation difficult. However, proper design of
the vacuum extraction system may overcome the problems of
heterogeneity [7, p. 19] [15],
2
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-18
-------
It would be difficult to remove soil contaminants with
low vapor pressures and/or high water solubilities from a site.
The lower limit of vapor pressure for effective removal of a
compound is 1 mm Hg abs. Compounds with high water
solubilities, such as acetone, may be removed with relative
ease from arid soils. However, with normal soils (i.e., mois-
ture content ranging from 10 percent to 20 percent), the
likelihood of successful remediation drops significantly be-
cause the moisture in the soil acts as a sink for the soluble
acetone.
Technology Description
Figure 1 is a general schematic of the in situ SVE process.
After the contaminated area is defined, extraction wells (1)
are installed. Extraction well placement is critical. Locations
must be chosen to ensure adequate vapor flow through the
contaminated zone while minimizing vapor flow through
other zones [11, p. 170]. Wells are typically constructed of
PVC pipe that is screened through the zone of contamination
[11]. The screened pipe is placed in a permeable packing; the
unscreened portion is sealed in a cement/bentonite grout to
prevent a short-circuited air flow direct to the surface. Some
SVE systems are installed with air injection wells. These wells
may either passively take in atmospheric air or actively use
forced air injection [9]. The system must be designed so that
any air injected into the system does not result in the escape
of VOCs to the atmosphere. Proper design of the system can
also prevent offsite contamination from entering the area
being extracted.
The physical dimensions of a particular site may modify
SVE design. If the vadose zone depth is less than 10 feet and
the area of the site is quite large, a horizontal piping system or
trenches may be more economical than conventional wells.
An induced air flow draws contaminated vapors and
entrained water from the extraction wells through headers—
usually plastic piping—to a vapor-liquid separator (2). There,
entrained water is separated and contained for subsequent
treatment (4). The contaminant vapors are moved by a
vacuum blower (3) to vapor treatment (5).
Vapors produced by the process are typically treated by
carbon adsorption or thermal destruction. Other methods—
such as condensation, biological degradation, and ultraviolet
oxidation—have been applied, but only to a limited extent.
Process Residuals
The waste streams generated by in situ SVE are vapor and
liquid treatment residuals (e.g., spent granular activated car-
bon [GAC]), contaminated groundwater, and soil tailings from
drilling the wells. Contaminated groundwater may be treated
and discharged onsite [12, p. 86] or collected and treated off-
site. Highly contaminated soil tailings from drilling must be
collected and may be either cleaned onsite or sent to an
offsite, permitted facility for treatment by another technology
such as incineration.
Site Requirements
SVE systems vary in size and complexity depending on
the capacity of the system and the requirements for vapor
and liquid treatment They are typically transported by vehicles
ranging from trucks to specifically adapted flatbed semitrailers;
therefore, a proper staging area for these vehicles must be
incorporated in the plans.
Figure 1
Process Schematic of the In Situ Soil Vapor Extraction System
i
i
»»
1 »¦
¦ (5)
if
nent 1
Procaas Residual
vacuum
Blower
vapor
Liquid
Separator
Claan Water
Liquid
Treatment
Extraction
Procaaa Residual
Air Vent or
Air vant or
ln)action Wall
Injection Wall
Ground Surface
Contaminated
Vadoae
Zona
Monitoring
Wall
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-19
3
-------
Adequate access roads must be provided to bring mobile
drilling rigs onsite for construction of wells and to deliver
equipment required for the process (e.g., vacuum blowers,
vapor-liquid separator, emission control devices, GAC canisters).
A small commercial-size SVE system would require about
1,000 square feet of ground area for the equipment. This
area does not include space for the monitoring wells which
might cover 500 square feet. Space may be needed for a
fortdift truck to exchange skid-mounted GAC canisters when
regeneration is required. Large systems with integrated vapor
and liquid treatment systems will need additional area based
on vendor-specific requirements.
Standard 440V, three-phase electrical service is needed.
For many SVE applications, water may be required at the site.
The quantity of water needed is vendor- and site-specific.
Contaminated soils or other waste materials are hazard-
ous, and their handling requires that a site safety plan be
developed to provide for personnel protection and special
handling measures. Storage should be provided to hold the
process product streams until they have been tested to deter-
mine their acceptability for disposal or release. Depending
upon the site, a method to store soil tailings from drilling
operations may be necessary. Storage capacity will depend
on waste volume.
Onsite analytical equipment, including gas chromato-
graphy and organic vapor analyzers capable of determining
site-specific organic compounds for performance assessment,
make the operation more efficient and provide better infor-
mation for process control.
Performance Data
SVE, as an in situ process (no excavation is involved), may
require treatment of the soil to various cleanup levels man-
dated by federal and state site-specific criteria. The time
required to meet a target cleanup level (or performance ob-
jective) may be estimated by using data obtained from bench-
scale and pilot-scale tests in a time-predicting mathematical
model. Mathematical models can estimate cleanup t.rne co
reach a target level, residual contaminant levels after a given
period of operation and can predict location of hot spots
through diagrams of contaminant distribution [16].
Table 2 shows the performance of typical SVE applica-
tions. It lists the site location and size, the contaminants and
quantity of contaminants removed, the duration of operation,
and the maximum soil contaminant concentrations before
treatment and after treatment. The data presented for specific
contaminant removal effectiveness were obtained, for the
most part, from publications developed by the respective SVE
system vendors. The quality of this information has not been
determined.
Midwest Water Resources, Inc. (MWRI) installed its
VAPORTECH™ pumping unit at the Dayton, Ohio site of a
spill of uncombusted paint solvents caused by a fire in a paint
warehouse [19]. The major VOC compounds identified were
acetone, methyl isobutyl ketone (MIBK), methyl ethyl ketone
(MEK), benzene, ethylbenzene, toluene, naphtha, xylene, and
other volatile aliphatic and alkyt benzene compounds. The
site is underlain predominantly by valley-fill glacial outwash
within the Great Miami River Valley, reaching a thickness of
over 200 feet. The outwash is composed chiefly of coarse,
clean sand and gravel, with numerous cobbles and small
boulders. There are two outwash units at the site separated
by a discontinuous till at depths of 65 to 75 feet. The upper
outwash forms an unconfined aquifer with saturation at a
depth of 45 to 50 feet below grade. The till below serves as
an aquitard between the upper unconfined aquifer and the
lower confined to semiconfined aquifer. Vacuum withdrawal
extended to the depth of groundwater at about 40 to 45 feet.
During the first 73 days of operation, the system yielded
3,720 pounds of volatiles and after 56 weeks of operation,
had recovered over 8,000 pounds of VOCs from the site.
Closure levels for the site were developed for groundwater
VOC levels of ketones only. These soil action levels (acetone,
810 ng/l; MIBK, 260 ng/l, and MEK, 450 |jg/l) were set so that
waters recharging through contaminated soils would result in
Tabto 2.
Summary oi Performance Data for In Situ Soil Vapor Extraction
s/tf
Size
Contamlnonts
Quantity
removed
Duration of
operation
Soil concentrations (tng/kg)
max. before after
treatment treatment
Industrial • CA [1 7]
TCE
30 kg
440 days
0.53
0.06
Sheet Metal Plant - Ml [18]
5,000 cu yds
PCE*
59 kg
35 days
5600
0.70
Prison Const. Site - Ml [19]
165,000 cu yds
TCA
-
90 days
3.7
0.01
Sherwin-Williams Site - OH [19]
425,000 cu yds
Paint solvent*
4,100 kg
6 mo
38
0.04
Upjohn - PR [20]I21]
7,000,000 cu yds
CCI,
107,000 kg
3 yr
2200
<0.005
UST Beftview - FL [7]
-
BTtX
9,700 kg
7 mo
97
<0 006
Verona WritfieJd Ml [7][22]
35,000 cu yds
TCE, PCE, TCA
12,700 kg
Over 1 yr
1380
Ongoing
Petroleum Terminal.
Owensboro, KY [19]
12,000 cu yds
Gasoline, diesel
6 mo
>5000
1.0 (target)
Srrt Program - Croveiand MA [7]
6,000 cu yds
TCE
590 kg
56 days
96.1
4.19
•PCE = Ptfchloroctftyfent
4 Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-20
-------
groundwater VOC concentrations at or below regulatory
standards. The site met all the closure criteria by |une 1988.
A limited amount of performance data is available from
Superfund sites. The EPA Superfund Innovative Technology
Evaluation (SITE) Program's Croveland, Massachusetts, dem-
onstration of the Terra Vac Corporation SVE process produced
data that were subjected to quality assurance/quality control
tests. These data appear in Table 2 [7, p. 29] and Table 3 [7,
p. 31 ]. The site is contaminated by trichloroethylene (TCE), a
degreasing compound which was used by a machine shop
that is still in operation. The subsurface profile in the test area
consists of medium sand and gravel just below the surface,
underlain by finer and silty sands, a clay layer 3 to 7 feet in
depth, and—below the clay layer—coarser sands with gravel.
The clay layer or lens acts as a barrier against gross infiltration
of VOCs into subsequent subsoil strata. Most of the subsur-
face contamination lay above the clay lens, with the highest
concentrations adjacent to it. The SITE data represent the
highest percentage of contaminant reduction from one of the
four extraction wells installed for this demonstration test. The
TCE concentration levels are weighted average soil concen-
trations obtained by averaging split spoon sample concentra-
tions every 2 feet over the entire 24-foot extraction well
depth. Table 3 shows the reduction of TCE in the soil strata
near the same extraction well. The Croveland Superfund Site
is in the process of being remediated using this technology
[2].
The Upjohn facility in Barceloneta, Puerto Rico, is the first
and, thus far, the only Superfund site to be remediated with
SVE. The contaminant removed from this site was a mixture
containing 65 percent carbon tetrachloride (CCIJ and 35
percent acetonitrile [20], Nearly 18,000 gallons of CCI4 were
extracted during the remediation, including 8,000 gallons
that were extracted during a pilot operation conducted from
January 198 3 to April 1984. The volume of soil treated at the
Upjohn site amounted to 7,000,000 cubic yards. The respon-
sible party originally argued that the site should be considered
clean when soil samples taken from four boreholes drilled in
the area of high pretest contamination show nondetectable
levels of CCI4. EPA did not accept this criterion but instead
required a cleanup criteria of nondetectable levels of CC14 in all
the exhaust stacks for 3 consecutive months [21]. This re-
quirement was met by the technology and the site was con-
sidered remediated by EPA.
Approximately 92,000 pounds of contaminants have been
recovered from the Tyson's Dump site (Region 3) between
November 1988 and July 1990. The site consists of two
unlined lagoons and surrounding areas formerly used to store
chemical wastes. The initial Remedial Investigation identified
no soil heterogeneities and indicated that the water table was
20 feet below the surface. The maximum concentration in
the soil (total VOCs) was approximately 4 percent. The
occurence of dense nonaqueous-phase liquids (DNAPls) was
limited in areal extent. After over 18 months of operation, a
number of difficulties have been encountered. Heterogene-
ities in soil grain size, water content, permeability, physical
structure and compaction, and in contaminant concentrations
have been identified. Soil contaminant concentrations of up
to 20 percent and widespread distribution of DNAPls have
been found. A tar-like substance, which has caused plugging,
has been found in most of the extraction wells. After 18
months of operation, wellhead concentrations of total VOCs
have decreased by greater than 90 percent [23, p. 28].
As of December 31,1990, approximately 45,000 pounds
of VOCs had been removed from the Thomas Solvent Raymond
Road Operable Unit at the Verona Well Field site (Region 5). A
pilot-scale system was tested in the fall of 1987 and a full-scale
operation began in March, 1988. The soil at the site consists
of poorly-graded, fine-to-medium-grained loamy soils under-
lain by approximately 100 feet of sandstone. Groundwater is
located 16 to 25 feet below the surface. Total VOC concen-
trations in the combined extraction well header have de-
creased from a high of 19,000 ug/1 in 1987 to approximately
1,500 ug/1 in 1990 [22],
Tab* 3
Extraction Wall 4: TCE Reduction In Soil Strata—EPA Sit* Demonstration (Groveland, MA) [7, p. 31 ]
Depth (ft)
Description of strata
Hydraulic
Conductivity (cm/s)
Soil TCE concentration (mg/kg)
Pre-treatment Post-treatment
0-2
Med. sand w/gravel
10"
2.94
NO
2-4
LL brown fine sand
10"
29.90
ND
4-6
Med. stiff It brown fine sand
io-5
260.0
39.0
6-8
Soft dk. brown fine sand
1»»
303.0
9.0
8-10
Med. stiff brown sand
10"
351.0
ND
10-12
V. stff It. brown med. sand
10"
195.0
NO
12-14
V. Stiff brown fine sand w/silt
10"
3.14
2.3
14-16
M. stff gm-bm clay w/silt
104
ND
ND
16-18
Soft wet clay
IO4
ND
ND
18-20
Soft wet clay
IO4
NO
NO
20-22
V. stiff brn med-coarse sand
10-
NO
ND
22-24
V. stiff brn med-coarse w/gravel
io-1
6.17
ND
NO - Nondetectable level
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-21
-------
An SVE pilot study has been completed at the Colorado
Avenue Subsite of the Hastings (Nebraska) Groundwater Con-
tamination site (Region 7). Trichloroethylene (TCE), 1,1,1-
trichloroethane (TCA), and tetrachloroethylene (PCE) occur in
two distinct unsaturated soil zones. The shallow zone, from
the surface to a depth of 50 to 60 feet, consists of sandy and
clayey silt TCE concentrations as high as 3,600 ug/1 were
reported by EPA in this soil zone. The deeper zone consists of
interbedded sands, silty sands, and gravelly sands extending
from about SO feet to 120 feet. During the first 630 hours of
the pilot study (completed October 11, 1989), removal of
approximately 1,488 pounds of VOCs from a deep zone
extraction well and approximately 127 pounds of VOCs from
a shallow zone extraction well were reported. The data
suggest that SVE is a viable remedial technology for both soil
zones [24],
As of November, 1989, the SVE system at the Fairchild
Semi-conductor Corporation's former San Jose site (Region 9)
has reportedly removed over 14,000 pounds of volatile con-
taminants. Total contaminant mass removal rates for the SVE
system fell below 10 pounds per day on October 5, 1989 and
fell below 6 pounds per day in December, 1989. At that time,
a proposal to terminate operation of the SVE system was
submitted to the Regional Water Quality Control Board for
the San Francisco Bay Region [25, p.3].
Resource Conservation and Recovery Act (RCRA) LDRs
that require treatment of wastes to best demonstrated avail-
able technology (BOAT) levels prior to land disposal may
sometimes be determined to be applicable or relevant and
appropriate requirements for CERCLA response actions. SVE
can produce a treated waste that meets treatment levels set
by BOAT but may not reach these treatment levels in all cases.
The ability to meet required treatment levels is dependent
upon the specific waste constituents and the waste matrix. In
cases where SVE does not meet these levels, it still may, in
certain situations, be selected for use at the site if a treatability
variance establishing alternative treatment levels is obtained.
EPA has made the treatability variance process available in
order to ensure that LDRs do not unnecessarily restrict use of
alternative and innovative treatment technologies. Treatabil-
ity variances are justified for handling complex soil and debris
matrices. The following guides describe when and how to
seek a treatability vanance for soil and debris: Superfund LDR
Guide #6A, "Obtaining a Soil and Debris Treatability Variance
for Remedial Actions' (OSWER Directive 9347.3-06FS, July
1989) [13], and Superfund LDR Guide #6B, "Obtaining a Soil
and Debris Treatability Variance for Removal Actions" (OSWER
Directive 9347.3-07FS, December 1989) [14], Another ap-
proach could be to use other treatment techniques in series
with SVE to obtain desired treatment levels.
Technology Status
During 1989, at least 1 7 RODs specified SVE as part of
the remedial action [5]. Since 1982, SVE has been selected as
the remedial action, either alone or in conjunction with other
treatment technologies, in more than 30 RODs for Superfund
sites [2] [3] [4] [5] [6]. Table 4 presents the location, primary
contaminants, and status for these sites [3] [4] [5] The
technology also has been used to clean up numerous under-
ground gasoline storage tank spills.
A number of variations of the SVE system have been
investigated at Superfund sites. At the Tinkhams Garage Site
in New Hampshire (Region 1), a pilot study indicated that
SVE, when used in conjunction with ground water pumping
(dual extraction), was capable of treating soils to the 1 ppm
clean-up goal [26, 3-7] [27], Soil dewatering studies have
been conducted to determine the feasabiiity of lowering the
water table to permit the use of SVE at the Bendix, PA Site
(Region 3) [28]. Plans are underway to remediate a stockpile
of 700 cubic yards of excavated soil at the Sodeyco Site in Mt.
Holly, NC using SVE [29],
With the exception of the Barceloneta site, no Superfund
site has yet been cleaned up to the performance objective of
the technology. The performance objective is a site-specific
contaminant concentration, usually in soil. This objective may
be calculated with mathematical models with which EPA
evaluates delisting petitions for wastes contaminated with
VOCs [30]. It also may be possible to use a TCLP test on the
treated soil with a corresponding drinking water standard
contaminant level on the leachate.
Most of the hardware components of SVE are available
off the shelf and represent no significant problems of avail-
ability. The configuration, layout, operation, and design of
the extraction and monitoring wells and process components
are site specific. Modifications may also be required as dic-
tated by actual operating conditions.
On-line availability of the full-scale systems described in
this bulletin is not documented. System components are
highly reliable and are capable of continuous operation for
the duration of the cleanup. The system can be shut down, if
necessary, so that component failure can be identified and
replacemnts made quickly for minimal downtime.
Based on available data, SVE treatment estimates are
typically S50/ton for treatment of soil. Costs range from as
low as JlO/ton to as much as S150/ton [7], Capital costs for
SVE consist of extraction and monitoring well construction;
vacuum blowers (positive displacement or centrifugal); vapor
and liquid treatment systems piping, valves, and fittings (usu-
ally plastic); and instrumentation [31]. Operations and main-
tenance costs include labor, power, maintenance, and moni-
toring activities. Offgas and collected groundwater treatment
are the largest cost items in this list; the cost of a cleanup can
double if both are treated with activated carbon. Electric
power costs vary by location (i.e., local utility rates and site
conditions). They may be as low as 1 percent or as high as 2
percent of the total project cost.
Caution is recommended in using these costs out of
context, because the base year of the estimates vary. Costs
also are highly variable due to site variations as well as soil and
contaminant characteristics that impact the SVE process. As
contaminant concentrations are reduced, the cost effective-
ness of an SVE system may decrease with time.
6 Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-22
-------
Table 4
Superfund Sites Specifying SVE as a Remedial Action
Location (Region)
Primary Contaminants
Status
Croveland Wells 1 & 2
Groveland, MA (1)
TCE
SITE demonstration complete
Full-scale Remediation in design
Kellogg-Deering Well Field
Norwalk, CT (1)
PCE, TCE, and BTX
Pre-design
[3] [5] [6]
South Municipal Water
Peterborough, NH (1)
PCE, TCE, Toluene
Pre-design completion expected in the fall
Supply Well
of 1991
[3] [5][6]
Tinkham Garage
Londonderry, NH (1)
PCE, TCE
Pre-design pilot study completed
[26] [27]
Wells G fit H
Woburn, MA (1)
PCE, TCE
In design
[3] [5]
FAA Technical Center
Atlantic County, N| (2)
BTX, PAHs, Phenols
In design
[31 [5]
Upjohn Manufacturing Co.
Barceloneta, PR (2)
cci4
Project completed in 1988
[20] [21]
Allied Signal Aerospace-
South Montrose, PA (3)
TCE
Pre-design tests and dewatering
[28]
Bendix Flight System Div.
study completed
Henderson Road
Upper Merion Township,
PCE, TCE, Toluene, Benzene
Pre-design
[3] [<]
PA (3)
Tyson's Dump
Upper Merion Township,
PCE, TCE, Toluene, Benzene,
In operation (since 11/88)
[23]
PA (3)
Trichloropropane
Stauffer Chemical
Cold Creek, Al (4)
CCL4, pesticides
Pre-design
[5] [6]
Stauffer Chemical
Lemoyne, AL (4)
CCL4, pesticides
Pre-design
[5] [6]
Sodyeco
Mt Holly, NC (4)
TCE, PAHs
Design approved
[29]
Kysor Industrial
Cadillac, Ml (5)
PCE, TCE,Toluene, Xylene
In design; pilot studies in progress
[3] [5] [6]
Long Prairie
Long Prairie, MN (5)
PCE, TCE, DCE, Vinyl chloride
SVE construction expected in the Fall of 1991
[3] [6]
MIDCO 1
Gary, IN (5)
BTX, TCE, Phenol, Dichloro-
In Design
[3] [5] [6]
methane, 2-Butanone,
Chlorobenzene
Miami County Incinerator
Troy, OH (5)
PCE; TCE; Toluene
Pre-design
[3] [S] [6]
Pristine
Cincinnati, OH (5)
Benzene; Chloroform; TCE;
Pre-design
[3] [6]
1,2-DCA; 1,2-DCE
Seymour Recycling
Seymour, IN (5)
TCE; Toluene; Chloromethane;
Pre-design investigation completed
[32]
tis-1, 2-DCE; 1,1,1-OCA;
Chloroform
Verona Well Field
Battle Creek, Ml (5)
PCE, TCA
Operational since 3/81
[22]
Wausau Groundwater
Wausau, Wl (5)
PCE, TCE
Pre-design
[3] [5] [6]
Contamination
South Valley/
Albuquerque, NM (6)
Chlorinated solvents
Pilot studies scheduled for
[<] [61
General Electric
Summer of 1991
Hastings Groundwater
Hastings, NE (7)
CCL4 .Chloroform
Pilot studies completed for
[24]
Contamination
Colorado Ave. (t Far-Marco
subsites
Sand Creek Industrial
Commerce City, CO (B)
PCE, TCE, pesticides
Pilot study completed
[331
Fairchild Semiconductor
San )ose, CA (9)
PCE, TCA, DCE, DCA,
Operational since 1988,
[25]
Vinyl chlorides, Phenols,
Currently conducting
and Freon
resaturation studies
Fairchild Semiconductor/
Mountain View, CA (9)
PCE, TCA, DCE, DCA,
Pre-design
[3] [5]
MTV-1
Vinyl chlorides, Phenols,
and Freon
[3] [5]
Fairchild Semiconductor/
Mountain View, CA (9)
PCE, TCA, DCE, DCA,
Pre-design
MTV-2
Vinyl chlorides. Phenols,
and Freon
[31 [5]
Intel Corporation
Mountain View, CA (9)
PCE, TCA, DCE, DCA,
Pre-design
Vinyl chlorides. Phenols,
and Freon
[3][5]
Raytheon Corporation
Mountain View, CA (9)
PCE, TCA, DCE, DCA,
Pre-design
Vinyl chlorides, Phenols,
and Freon
[3] [4] [6]
Motorola 52nd Street
Phoenix, AZ (9)
TCA, TCE, CCL4, Ethyl benzene
Pre-design
Phoenix-Goodyear Airport
Goodyear, AZ (9)
TCE, DCE, MEK
North Unit - In design
[3*1
1 Area (also Litchfield
1 Airport Area)
South Unit - pilot study completed
engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-23
-------
EPA Contact
Technology-specific questions regarding SVE may be di-
rected to:
Michael Gruenfeld
U.S. Environmental Protection Agency
Releases Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Ave.
Building 10 (MS-104)
Edison, N] 08837
(FTS) 340-6924 or (908) 321-6924
Foster Wheeler Enviresponse inc. (FWEI) under contract No.
68-C8-0062 Mr. Eugene Harris served as the EPA Technical
Project Monitor. Gary Baker was SAJC's Work Assignment
Manage' This bulletin was authored by Mr. Pete Michaels of
FWEI. The author is especially grateful to Mr. Bob Hillger and
Mr. Chi-Yuan Fan of EPA, RREL, who have contributed signifi-
cantly by serving as technical consultants during the devel-
opment of this document.
The following other Agency and contractor personnel
have contributed their time and comments by participating in
the expert review meetings and/or peer reviewing the docu-
ment:
Acknowledgements
This bulletin was prepared for the U.S. Environmental
Protection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIQ, and
Dr. David Wilson
Dr. Neil Hutzler
Mr. Seymour Rosenthal
Mr. |im Rawe
Mr. Clyde Dial
Mr. )oe Tillman
Vanderbilt University
Michigan Technological University
FWEI
SAIC
SAIC
SAIC
8
F-24
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
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19. Midwest Water Resource, Inc.; Correspondence from
Dr. Frederick C. Payne.
20. Geotec Remedial Investigation Report and Feasibility
Study for Upjohn Manufacturing Co. Barceloneta,
Puerto Rico, 1984.
21. Geotec Evaluation of Closure Criteria for Vacuum
Extraction at Tank Farm. Upjohn Manufacturing
Company, Barceloneta, Puerto Rico, 1984.
22. CH2M Hill, Inc. Performance Evaluation Report Thomas
Solvent Raymond Road Operable Unit. Verona Well
Field Site, Battle Creek, Ml, April 1991.
23. Terra Vac Corporation. An Evaluation of the Tyson's Site
On-Site Vacuum Extraction Remedy Montgomery
County, Pennsylvania, August 1990.
24. IT Corporation. Final Report-Soil Vapor Extraction Pilot
Study, Colorado Avenue Subsite, Hastings Ground-
Water Contamination Site, Hastings, Nebraska, August,
1990.
25. Canonie Environmental. Supplement to Proposal to
Terminate In-Situ Soil Aeration System Operation at
Fairchild Semiconductor Corporation's Former San Jose
Site, December 1989.
26. Malcom Pirnie, Tinkhams Garage Site, Pre-Design Study,
Londonderry, New Hampshire - Final Report, July 1988.
27. Terra Vac Corp., Tinkhams Garage Site Vacuum Extrac-
tion Pilot Test, Londonderry, New Hampshire, July 20,
1988.
28. Environmental Resources Management, Inc. Dewater-
ing Study For The TCE Tank Area - Allied Signal Aero-
space, South Montrose, PA, December 1990.
29. Letter Correspondence from Sandoz Chemicals Corpo-
ration to the State of North Carolina Department of
Environmental Health, and Natural Resources, RE:
Remediation Activities in CERCLA C Area (Sodeyco)
Superfund Site, March 28, 1991.
30. Federal Register, Volume 50, No. 229, Wednesday,
November 27, 1985, pp. 48886-48910.
31. Assessing UST Corrective Action Technologies: Site
Assessment and Selection of Unsaturated Zone Treat-
ment Technologies. EPA/600/2-90/011, U.S. Environ-
mental Protection Agency, 1990.
32. Hydro Geo Chem, Inc. Completion Report, Pre-Design
Investigation for a Vapor Extraction at the Seymour Site,
Seymour, Indiana, February 1990. ......
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-25
-------
33. Groundwater Technology, Inc. Report of Findings •
Vacuum Extraction Pilot Treatability at the Sand Creek
Supertund Site (OU-1), Commerce City, Colorado,
March 1990.
34. Hydro Geo Chem, Inc. Results and Interpretation of the
Phoenix Goodyear Airport SVE Pilot Study, Goodyear,
Arizona, May 1989.
10 Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
F-26
-------
United States Office of Emergency and Office of
Environmental Protection Remedial Response Research and Development
Agency Washington, DC 20460 Cincinnati, OH 45268
Superfund EPA/540/2-90/016 September 1990
Engineering Bulletin
&EPA Slurry Biodegradation
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants and
contaminants as a principal element" The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
In a slurry biodegradation system, an aqueous slurry is
created by combining soil or sludge with water. This slurry is
then biodegraded aerobically using a self-contained reactor or
in a lined lagoon. Thus, slurry biodegradation can be compared
to an activated sludge process or an aerated lagoon, depending
on the case.
Slurry biodegradation is one of the biodegradation methods
for treating high concentrations (up to 250,00 mg/kg) of
soluble organic contaminants in soils and sludges. There are
two main objectives for using this technology: to destroy the
organic contaminant and, equally important, to reduce the
volume of contaminated material. Slurry biodegradation is not
effective in treating inorganics, including heavy metals. This
technology is in developmental stages but appears to be a
promising technology for cost-effective treatment of hazardous
waste.
Slurry biodegradation can be the sole treatment technology
in a complete cleanup system, or it can be used in conjunction
with other biological, chemical, and physical treatment. This
technology was selected as a component of the remedy for
polychlorinated biphenyl (PCB)-contaminated oilsat the General
Motors Superfund site at Massena, New York, [11, p. 2]*but has
not been a preferred alternative in any record of decision [6, p.
6], It may be demonstrated in the Superfund Innovative
Technology Evaluation (SITE) program. Commercial-scale
units are in operation. Vendors should becontacted to determine
the availability of a unit for a particular site. This bulletin
provides information on the technology applicability, the types
of residuals produced, the latest performance data, site
requirements, the status of the technology, and sources for
further information.
Technology Applicability
Biodegradation is a process that is considered to have
enormous potential to reduce hazardous contaminants in a
cost-effective manner. Biodegradation is not a feasible treatment
method for all sites. Each vendor's process may be capable of
treating only some contaminants. Treatability tests to determine
the biodegradability of the contaminants and the solids/liquid
separation that occurs at the end of the process are very
important.
Slurry biodegradation has been shown to be effective in
treating highly contaminated soils and sludges that have
contaminant concentrations ranging from 2,500 mg/kg to
250,000 mg/kg. It has the potential to treat a wide range of
organic contaminants such as pesticides, fuels, creosote, penta-
chlorophenol (PCP), PCBs, and some halogenated volatile
organics. It is expected to treat coal tars, refinery wastes,
hydrocarbons, wood-preserving wastes, and organic and
chlorinated organic sludges. The presence of heavy metals and
chlorides may inhibit the microbial metabolism and require
pretreatment. Listed Resource Conservation and Recovery Act
(RCRA) wastes it has treated are shown in Table 1 [10, p. 106].
•[Reference number, page number]
F-27
-------
. Table 1
RCRA-Usted Hazardous Wastes
Wood Treating Wastes
K001
Dissolved Air Floatation (DAf) float
K048
Slop Oil Emuision Solids
K049
American Petroleum institute (API) Separator
Sludge
K051
The effectiveness of this slurry biodegradation on general
contaminant groups for various matrices is shown in Table
2 [12, p. 1 3]. Examples of constituents within contaminant
groups are provided in Reference 12, "Technology Screening
Guide for Treatment of CERCLA Soils and Sludges." This table
is based on current available information or professional
judgment when no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiency achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated biodegradability
means that, at some scale, treatability was tested to show that,
for that particular contaminant and matrix, the technology was
effective. The ratings of potential biodegradability and' no
expected biodegradability are based upon expert judgment.
Where potential biodegradability is indicated, the technology
is believed capable of successfully treating the contaminant
group. When the technology is not applicable or will probably
not work for a particular contaminant group, a no-expected-
biodegradability rating is given. Another source of general
observations and average removal efficiencies for different
treatability groups is contained in the Superfund LDR Guide
#6A, "Obtaining a Soil and Debris Treatability Variance for
Remedial Actions," (OSWER Directive 9347.3-06FS [10], and
Superfund LDR Guide #6B, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions," (OSWER Directive
934 7.3-0 7FS [9].
Limitations
The various characteristics limiting the process feasibility,
the possible reasons for these, and actions to minimize impacts
of these limitations are listed in Table 3 (11, p. 2]. Some of these
actions could be a part of the pretreatment process. The
variation of these characteristics in a particular hardware design,
operation, and/or configuration for a specific site will largely
determine the viability of the technology and cost-effectiveness
of the process as a whole.
Tcble 2
DegraacbiSty Using Slurry Biodegradation
Treatment on General Contaminant Groups for
Soils, Sediments, and Sludges
| Contaminant Croups
Biodegradatvlity
All Matrices
Halogcnatcd volatile:
~
Haiogenated scmivolatiles
¦
Nonhalogcnated volatiles
~
Nonhalogenatec semivolatiles
c
Q
p
PCBs
o
Pesticides
Dioxins/Furans
G
Organic cyanides
T
Organic corrosives
G
Volatile metals
G
Nonvolatile metals
~
!
Asbestos
~
p
0
c
Radioactive materials
~
Inorganic corrosives
G
Inorganic cyanides
T
3!
Oxidizer*
G
Z
O
Reducer*
G
3
¦ Demonstrated Effectiveness: Successful treatability test at somescale completed
~ Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Lxpert opinion that technology wrl not worV
Technology Description
Figure 1 is a schematic of a slurry biodegradation process.
Waste preparation (1) includes excavation and/or moving
the waste material to the process where it is normally screened
to remove debris and large objects. Particle size reduction,
water addition, and pH and temperature adjustment are other
important waste preparation steps that may be required to
achieve the optimum inlet feed characteristics for maximum
contaminant reduction. The desired inlet feed characteristics
[6, p. 14] are:
Organics: .025-25%
Solids: 10-40%
Water 60-90%
Solids particle size:
by weight
by weight
by weight
Less than 1/4'
Temperature:15-35'C
pH: 4.5-8.8
2
Engineering Bulletin: Slurry Biodegradation Treatment
F-28
-------
After appropriate pretreatment, the wastes are suspended
in a slurry form and mixed in a tank (2) to maximize the mass
transfer rates and contact between contaminants and
microorganisms capatHe of degrading those contaminants.
Aerobic treatment in batch mode has been the most common
mode of operation. This process can be performed in contained
reactors (3) or in lined lagoons [7, p. 9]. In the latter case,
synthetic liners have to be placed in existing unlined lagoons,
complicating the operation and maintenance of the system. In
this case, excavation of a new lagoon or above-ground tank
reactors should be considered. Aeration is provided by floating
or submerged aerators or by compressors and spargers. Mixing
is provided by aeration alone or by aeration and mechanical
mixing. Nutrients and neutralizing agents are supplied to
relieve any chemical limitations to microbial activity. Other
materials, such as surfactants, dispersants, and compounds
supporting growth and inducing degradation of contaminant
compounds, can be used to improve the materials' handling
characteristics or increase substrate availability for
degradation [8, p. 5]. Microorganisms may be added initially to
seed the bioreactor or added continuously to maintain the
correct concentration of biomass. The residence time in the
bioreactor varies with the soil or sludge matrix; physical/
chemical nature of the contaminant, including concentration;
and the biodegradability of the contaminants. Once
biodegradation of the contaminants is completed, the treated
slurry is sent to a separation/dewatering system (4). A clarifier
for gravity separation, or any standard dewatering equipment,
can be used to separate the solid phase and the aqueous phase
of the slurry.
Site Requirements
Slurry biodegradation tank reactors are generally
transported by trailer. Therefore, adequate access roads are
required to get the unit to the site. Commercial units require a
setup area of 0.5-1 acre per million gallons of reactor volume.
Standard 440V three-phase electrical service is required.
Compressed air must be available. Water needs at the site can
be high if the waste matrix must be made into slurry form.
Contaminated soils or other waste materials are hazardous and
their handling requires that a site safety plan be developed to
provide for personnel protection and special handling measures.
Climate can influence site requirements by necessitating
covers over tanks to protect against heavy rainfall or cold for
long residence times.
Large quantities of wastewater that results from dewatering
the slurried soil or that is released from a sludge may need to be
stored prior to discharge to allow time for analytical tests to
verify that the standard for the site has been met. A place to
discharge this wastewater must be available.
Onsite analytical equipment for conducting dissolved
oxygen, ammonia, phosphorus, pH, and microbial activity are
needed for process control. High-performance liquid
chromatographic and/or gas chromatographic equipment is
desirable for monitoring organic biodegradation.
Process Residuals
There are three main waste streams generated in the slurry
biodegradation system: the treated solids (sludge or soil), the
process water, and possible air emissions. The solids are
dewatered and may be further treated if they still contain
organic contaminants. If the solids are contaminated with
inorganics and/or heavy metals, they can be stabilized before
disposal. The process water can be treated in an onsite
treatment system prior to discharge, or some of it (as high as 90
percent by weight of solids) is usually recycled to the front end
of the system for slurrying. Air emissions are possible during
operation of the system (e.g., benzene, toluene, xylene [BTX]
compounds); hence, depending on the waste characteristics,
air pollution control, such as activated carbon, may be necessary
K p. 29],
Performance Data
Performance results on slurry biodegradation systems are
provided based on the information supplied by various vendors.
The quality assurance for these results has not been evaluated.
In most of the performances, the cleanup criteria were based on
the requirements of the client; therefore, the data do not
necessarily reflect the maximum degree of treatment possible.
Remediation Technologies, Inc's (ReTeC) full-scale slurry
biodegradation system (using a lined lagoon) was used to treat
wood preserving sludges (K0001) at a site in Sweetwater,
Tennessee, and met the closure criteria for treatment of these
sludges. The system achieved greater than 99 percent removal
efficiency and over 99 percent reduction in volume attained for
PCP and polynuclear aromatic hydrocarbons (PAHs) (Table 4
and Table 5).
Engineering Bulletin: Slurry Biodegradation Treatment
F-29
3
-------
Figure 1
Slurry Biodegradation Process
Treated
Emissions
Water
~ Solids
^ Oversized
Rejects
Toble 3
Characteristics Limiting the Slurry Biodegradatfon Process
CHARACTERISTICS LIMITING
THE PROCESS FEASIBILITY
REASONS FOR POTENTIAL IMPACT
ACTIONS TO MINIMIZE IMPACTS
Variable waste composition
Inconsistent biodegradation caused by
variation in bioiogical activity
Dilution of waste stream. Increase mixing
Nonuniform particle size
Minimize the contact with microorganisms
Physical separation
Water solubility
Contaminants with low solubility are
harder to biodegrade
Addition of surfactants or other emulsifiers
Biodegradability
Low rate of destruction inhibits process
Addition of microbial culture capable of
degrading particularly difficult compounds or
longer residence time
Temperature outside 15-35°C
range
Less microbial activity outside this range
Temperature monitoring and adjustments
Nutrient deficiency
Lack of adequate nutrients for biological
activity
Nutrient monitoring; adjustment of the
carbon/nitrogen/phosphorus ratio
Oxygen deficiency
Lack of oxygen is rate limiting
Oxygen monitoring and adjustments
Insufficient Mixing
Inadequate microbes/solids/organics
contact
Optimize mixing charactenstics
pH outside 4.5 - 8.8 range
Inhibition of biological activity
Sludge pH monitoring. Addition of acidic or
alkaline compounds
Microbial population
Insufficient population results in low
biodegradation rates
Culture test, addition of culture strains
Water and air emissions
discharges
Potential environmental and/or health
impacts
Post-treatment processes (e.g., air scrubbing,
carbon filtration)
Presence of elevated, dissolved
levels of:
• Heavy metals
• Highly chlorinated organics
• Some pesticides, herbicides
• Inorganic salts
Can be highly toxk to microorganisms
Pretreatment processes to reduce the
concentration of toxic compounds in the
constituents in the reactor to nontoxic range
Emissions
Control
Waste
Preparation
0)
Mixing Tank
Bio Reactors
Dewatering
Slurrv
Water
Oxygen
Nutr-ents/
Additives
Engineering Bulletin: Slurry Blodegradation Treatment
F-30
-------
Table 4
Results Showing Reduction in Concentration for Wood Preserving Wastes
Initital Concentration
Final Concentration
Percent Removal
Compounds
Solids
Slurry
Solids
Slurry
Solids
Slurry
(mg/kg)
(mg/kg)
(mg/kg)
(mg/kg)
(mg/kg)
(mg/kg)
Phenol
14.6
1.4
0.7
<0.1
95.2*
92.8
Pentachlorophenol
687
64
12.3
0.8
98.2
92.8
Naphthalene
3,670
343
23
1.6
99.3*
99.5*
Phenanthrene & Anthracene
30,700
2,870
200
13.7
99.3
99.5
Fluoranthene
5,470
511
67
4.6
98.8
99.1
Carbazole
1,490
139
4.9
0.3
99.7
99.8
*May be due to combined effect of Volatilization and Biodegradation. [Source: ReTec, 50,000 gal. reactor]
Table 5
Results Showing Reduction In Volume For Wood Preserving Wastes
Compounds
Before Treatment
After Treatment
Percent Volume
(Total pounds)
(Total pounds)
Reduction
Phenol
368
41.4
88.8*
Pentachlorophenol
141,650
193.0
99.9
Naphthalene
179,830
36.6
99.9*
Phenanthrene & Anthracene
2,018,060
303.1
99.9
Fluoranthene
190,440
341.7
99.8
Carbazole
114,260
93.7
99.9
"May be due to combined effect of Volatilization and Biodegradation. [Source: ReTec, 50,000 gal. reactor]
Data for one of these pilot-scale field demonstrations,
which treated 72,000 gallons of oil refinery sludges, are shown
in Figure 2 [8, p. 24]. In this study, the degradation of PAHs was
relatively rapid and varied depending on the nature of the
waste and loading rate. The losses of carcinogenic PAHs
(principally the 5- and 6-ring PAHs) ranged from 30 to 80
percent over 2 months while virtually all of the noncarcinogenic
PAHs were degraded. The total PAH reduction ranged from 70
to 95 percent with a reactor residence time of 60 days.
ECOVA's full-scale, mobile slurry biodegradation unit was
used to treat more than 750 cubic yards of soil contaminated
with 2,4-Dichlorophenoxy acetic acid (2,4-D) and 4-chloro-2-
methyl-phenoxyacetic acid (MCPA) and other pesticides such
as alachlor, trifluralin, and carbofuran. To reduce 2,4-D and
MCPA levels from 800 ppm in soil and 400 ppm in slurry to less
than 20 ppm for both in 1 3 days, 26,000-gallon bioreactors
capable of handling approximately 60 cubic yards of soil were
used. The residuals of the process were further treated through
land application [3, p. 4J. Field application of the slurry bio-
degradation system designed by ECOVA to treat PCP-
contaminated wastes has resulted in a 99-percent decrease in
PCP concentrations (both in solid and aqueous phase) over a
period of 24 days [3, p. 5].
Performance data for Environmental Remediation, Inc.
(ERI) is available for the treatment of American Petroleum
Institute (API) separator sludge and wood-processing wastes.
Two lagoons containing an olefin sludge from an API separator
were treated. In one lagoon, containing, 4,000 cubic yards of
sludge, a degradation time of 21 days was required to achieve
68 percent volume reduction and 62 percent mass oil and
grease reduction at an operating temperature of 18*C. In the
second lagoon, containing 2,590 cubic yards of sludge, a
treatment time of 61 days was required to achieve 61 percent
sludge reduction and 87.3 percent mass oil and grease reduction
at an operating temperature of 14'C [1, p. 367].
At another site, the total wood-preserving "constituents 7
were reduced to less than 50 ppm. Each batch process was
Engineering Bulletin: Slurry Biodegradation Treatment
F-31
5
-------
Figure 2
Pilot Scale Results on Oil Refinery Sludges
Sample:
Lagoon Sludge
carried out with a residence time of 28 days in 24-foot-
diameter, 20-foot-height tank reactors handling 40 cubic yards
per batch [6]. The mean concentrations of K001 constituents
before treatment and the corresponding concentrations after
treatment, for both settled solids and supernatant, are provided
in Table 6 [2, o. 11 ]. The supernatant was discharged to a local,
publicly owned wastewater treatment works.
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to best demonstrated available technology
(BDAT) levels prior to land disposal may sometimes be
determined to be applicable or relevant and appropriate
requirements (ARARs) for CERCLA response actions. Slurry
biodegradation can produce a treated waste that meets
treatment levels set by BDAT, but may not reach these treatment
levels in all cases. The ability to meet required treatment levels
is dependent upon the specific waste constituents and the
waste matrix. In cases where' slurry biodegradaton does not
meet these levels, it still may, in certain situations, be selected
for use at the site if a treatability variance establishing alternative
treatment levels is obtained. EPA has made the treatability
variance process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions," (OSWER Directive 9347. J-06FS) [10) and Superfund
LDR Guide #68, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions" (OSWER Directive 9347.3-07FS)
[9]. Another approach could be to use other treatment
techniques in series with slurry biodegradation toobtain desired
treatment levels.
Technology Status
Biotrol, Inc. has a pilot-scale slurry bioreactor that consists
of a feed storage tank, a reactor tank, and a dewatering system
for the treated slurry. It was designed to treat the fine-particle
slurry from its soil-washing system. Biotrofs process was
included in the SITE program demonstration of its soil-washing
system at the MacGillis and Gibbs wood-preserving site in New
Brighton, Minnesota, during September and October of 1989.
Performance data from the SfTE demonstration are not currently
available; the Demonstration and Applications Analysis Report
is scheduled to be published in latel990.
6
F-32
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Table 6
Results of Wood Preserving Waste Treatment
Before treatment
After Treatment
Wood Preserving Waste
In Soil
In Settled Soil
In Supernatant
Constituents
(mg/kg)
(mg/kg)
(mg/L)
2-Chlorophenol
1.89
<0.01
<0.01
Phenol
3.91
<0.01
<0.01
2,4-Dimethylphenol
7.73
<0.01
<0.01
2,4,6-T richlorophenol
6.99
<0.01
<0.01
p-Chloro-m-cresol
118.62
<0.01
<0.01
Tetrachlorophenol
11.07
<0.02
<0.02
2,4-Dinitrophenol
4.77
<0.03
<0.03
Pentachlorophenol
420.59
3.1
<0.01
Naphthalene
1078.55
<0.01
0.04
Acenaphthylene
998.80
1.4
1.60
Phenanthrene + Anthracene
6832.07
3.8
3.00
Fluoranthene
1543.06
4.9
16.00
Chrysene + Benz(a)anthracene
519.32
1.4
8.20
Benzo(b)fluoranthene
519.32
<0.03
4.50
Benzo(a)pyrene
82.96
0.1
2.50
lndeno(l,2,3-cd)pyrene +
Dibenz(a,h)anthracene
84.88
0.5
1.70
Carbazole
135.40
<0.05
1.70
[Source: Environmental Solutions, Inc.]
ECOVA Corporation has a full-scale mobile slurry
biodegradation system. This system was demonstrated in the
field on soils contaminated with pesticides and PCP. ECOVA
has developed an innovative treatment approach that utilizes
contaminated ground water on site as the make up water to
prepare the slurry for the bioreactor.
ERI has developed a full-scale slurry biodegradation system.
ERI's slurry biodegradation system was used to reduce sludge
volumes and oil and grease content in two wastewatertreatment
lagoons at a major refinery outside of Houston, Texas, and to
treat 3,000 cubic yards of wood-preserving waste (creosote-
K001) over a total cleanup time of 18 months.
Environmental Solutions, Inc. reportedly has a full-scale
slurry biodegradation system, with a treatment capacity of up
to 100,000 cubic yards, that has been used to treat petroleum
and hydrocarbon sludges.
CroundwaterTechnology, Inc. reportedly has a full-scale
slurry biodegradation system, which employs flotation, reactor,
and darifier/sedimentation tanks in series, that has been used
to treat soils contaminated with heavy oils, PAHs, and light
organics.
ReTeC's full-scale slurry biodegradation system was used
in two maior projects: Valdosta, Georgia, and Sweetwater,
Tennessee. Both projects involved closure of RCRA-regulated
surface impoundments containing soils and sludges
contaminated with creosote constituents and PCP. Each project
used in-ground, lined slurry-phase bioreactor cells operating at
100 cubic yards per week. Residues were chemically stabilized
and further treated by tillage. For final closure, the impoundment
areas and slurry-phase cells were capped with clay and a heavy-
duty asphalt paving [5]. ReTeC has also performed several pilot-
scale field demonstrations with their system on oil refinery
sludges (RCRA K048-51).
One vendor estimates the cost of full-scale operation to be
J80 to J150 per cubic yard of soil or sludge, depending on the
initial concentration and treatment volume. The cost to use
slurry biodegradation will vary depending upon the need for
additional pre- and post-treatment and the addition of air
emission control equipment.
EPA Contact
Technology-specific questions regarding slurry bio-
degradation may be directed to:
Dr. Ronald Lewis
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Telephone: FTS 684-7856 or (51 3) 569-7856.
Engineering Bulletin: Slurry Biodegradation Treatment
F-33
7
-------
REFERENCES
1. Christiansen, |., T. Koenig, and C. Lucas. Topic 3:
Liquid/Solids Contact Case Study. In: Proceedings
from the Superfund Conference, Environmental
Remediation, Inc., Washington, D.C., 1989. pp. 365-
374.
2. Christiansen, J., B. Invin, E. Titcomb, and S. Morris.
Protocol Development For The Biological Remediation
of A Wood-Treating Site. In: Proceedings from the 1st
International Conference on Physicochemical and
Biological Detoxification and Biological Detoxification
of Hazardous Wastes, Atlantic City, New Jersey, 1989.
3. ECOVA Corporation. Company Project Description,
(no date).
4. Kabrick, R.( D. Sherman, VI. Coover, and R. Loehr.
September 1989, Biological Treatment of Petroleum
Refinery Sludges. Presented at the Third International
Conference on New Frontiers for Hazardous Waste
Management, Remediation Technologies, Inc.,
Pittsburgh, Pennsylvania, 1989.
5. ReTeC Corporation. Closure of Creosote and
Pentachlorophenol Impoundments. Company
Literature, (no date).
6. Richards, D. J. Remedy Selection at Superfund Sites on
Analysis of Bioremediation, 1989 AAAS/EPA
Environmental Science and Engineering Fellow, 1989.
7. Stroo, H. F., Remediation Technologies Inc. Biological
Treatment of Petroleum Sludges in Liquid/Solid
Contact Reactors. Environmental and Waste
Management World 3 (9): 9-12, 1989.
8. Stroo, H.F., ). Smith, M. Torpy, M. Coover, and R.
Kabrick. Bioremediation of Hydrocarbon-
Contaminated/Solids Using Liquid/Solids Contact
Reactors, Company Report, Remediation Technologies,
Inc., (no date), 27 pp.
9. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
10. Superfund LDR Guide #6A: Obtaining a Soil and
Debris Treatability Variance for Remedial Actions.
OSWER Directive 9347.3-06FS, U.S. Environmental
Protection Agency, 1989.
11. Innovative Technology: Slurry-Phase Biodegradation.
OSWER Directive 920G.5-252FS, U.S. Environmental
Protection Agency, 1989.
12. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA
PERMIT No. G-35
Official Business
Penalty for Private Use S300
F-34
-------
United States Office of Emergency and Office of
Environmental Protection Remedial Response Research and Development
Agency . Washington, DC 20460 Cincinnati, OH 45268
Superfund EPA/540/S-92/007 Octoberl 992
Engineering Bulletin
<&EPA Rotating Biological Contactors
Purpose
Section 121 (b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates the
Environmental Protection Agency (EPA) to select remedies that
"utilize permanent solutions and alternative treatment technolo-
gies or resource recovery technologies to the maximum extent
practicable" and to prefer remedial actions in which treatment
"permanently and significantly reduces the volume, toxicity, or
mobility of hazardous substances, pollutants, and contaminants
as a principal element." The Engineering Bulletins are a series of
documents that summarize the latest information available on
selected treatment and site remediation technologies and related
issues. They provide summaries of and references for the latest
information to help remedial project managers, on-scene coor-
dinators, contractors, and other site cleanup managers under-
stand the type of data and site characteristics needed to evalu-
ate a technology for potential applicability to their Superfund or
other hazardous waste site. Those documents that describe in-
dividual treatment technologies focus on remedial investigation
scoping needs. Addenda will be issued periodically to update
the original bulletins.
Abstract
Rotating biological contactors (RBCs) employ aerobic fixed-
film treatment to degrade either organic and/or nitro-
genous (ammonia-nitrogen) constituents present in aqueous
waste streams. Treatment is achieved as the waste passes by the
media, enabling fixed-film systems to acclimate bio mass capable
of degrading organic waste [1, p. 91 ]*. Fixed-film RBC reactors
provide a surface to which soil organisms can adhere; many in-
digenous soil organisms are effective degraders of hazardous
wastes.
An RBC consists of a series of corrugated plastic discs
mounted on a horizontal shaft As the discs rotate through the
aqueous waste stream, a microbial slime layer forms on the sur-
face of the discs. The microorganisms in this slime layer degrade
the waste's organic and nitrogenous constituents. Approximately
40 percent of the RBC's surface area is immersed in the waste
stream as the RBC rotates through the liquid. The remainder of
the surface area is exposed to the atmosphere, which provides
oxygen to the attached microorganisms and facilitates oxidation
of the organic and nitrogenous contaminants [2, p. 6], In gen-
Ireference number, page number]
eral, the large microbial population growing on the discs pro-
vides a high degree of waste treatment in a relatively short time.
Although RBC systems are capable of performing organic re-
moval and nitrification concurrently, they may be designed to
primarty provide either organic removal or nitrification singly [3,
p. 1-2].
RBCs were first developed in Europe in the 1950s [1, p. 6].
Commercial applications in the United States did not occur un-
til the late 1960s. Since then, RBCs have been used in the United
States to treat municipal and industrial wastewaters. Because bio-
logical treatment converts organics to innocuous products such
as COj, investigators have begun to evaluate whether biologi-
cal treatment systems like RBCs can effectively treat liquid waste
streams from Superfund sites. Treatability studies have been per-
formed at at least three Superfund sites to evaluate the effective-
ness of this technology at removing organic and nitrogenous
constituents from hazardous waste leachate. A full-scale RBC
treatment system is presently operating in at least one Super-
fund site in the United States.
Technology Applicability
Research demonstrates that RBCs can potentially treat aque-
ous organic waste streams from some Superfund sites. During
the treatability studies for the Stringfellow, New Lyme, and Moyer
Superfund sites, RBC systems efficiently removed the major or-
ganic and nitrogenous constituents in the leachates. Because
waste stream composition varies from site to site, treatability test-
ing to determine the degree of contaminant removal is an es-
sential element of the remedial action plan. Although recent
Superfund applications have been limited to the treatment of
landfill leachates, this technology may be applied to groundwa-
ter treatment [4],
In general, biological systems can degrade only the soluble
fraction of the organic contamination. Thus the applicability of
RBC treatment is ultimately dependent upon the solubility of the
contaminant RBCs are generally applicable to influents contain-
ing organic concentrations of up to 1 percent organics, or be-
tween 40 and 10,000 mg/l of SBOD. (Note: Soluble biochemi-
cal oxygen demand, or SBOD, measures the soluble fraction of
the biodegradable organic content in terms of oxygen demand.)
RBCs can be designed to reduce influent biochemical oxygen de-
mand (BOD) concentrations below 5 mg/l SBOD and ammo
F-35
-------
Table 1
Effectiveness of RBCs on General Contaminant
Group* for liquid Watte Streams
Contaminant Croups
tfiectlvtnai
Halogenated volatiles
¦
Halogenated semivolatiles
¦
Nonhalogenated volatiles
¦
£
Nonhalogenated semivolatiles
¦
c
Q
a
PCBs
~
Pesticides
~
Dloxins/Furans
Organic cyanides
~
Organic corrosives
~
Volatile metals
~
Nonvolatile metals
~
•5
0
Asbestos
O
e
Radioactive materials
~
~~
Inorganic corrosives
~
Inorganic cyanides
~
Sr
Oxidizers
n
%
«c
Reducers
~
¦
Demonstrated Effectiveness: Successful treataWity test it some scale com-
pleted.
T
Potential EHectiveness Expert opinion that technology *rfil wcrt.
3
No Expected Effectiveness: Expert ooon that technology will network.
nia-nitrogen (NH,-N) levels below 1.0 mg/l [5, p. 2] [6, p. 60].
RBCs are effective for treating solvents, halogenated organics,
acetone, alcohols, phenols, phthalates, cyanides, ammonia, and
petroleum products [7, p. 6] [8, p. 69]. RBCs have fully nitrified
leachates containing ammonia-nitrogen concentrations up to
700 mg/t [6, p. 61].
The effectiveness of RBC treatment systems on general con-
taminant groups is shown in Table 1. Examples of constituents
within contaminant groups are provided in Technology Screen-
ing Guide for Treatment of CERCLA Soils and Sludges" [9], Table
1 is based on the current available information or professional
judgment where no information was available. The proven ef-
fectiveness of the technology for a particular site or waste does
not ensure that it will be effective at all sites or that the treat-
ment efficiencies achieved will be acceptable at other sites. For
the ratings used for this table, demonstrated effectiveness means
that, at some scale, treatability was tested to show the technol-
ogy was effective for that particular contaminant group. The rat-
ings of potential effectiveness or no expected effectiveness are
based upon expert judgment. Where potential effectiveness is
indicated, the technology is believed capable of successfully treat-
ing the contaminant group in a particular medium. When the
technology is not applicable or wSI probably not work for a par-
ticular combination of contaminant group and medium, a no
expected effectiveness rating is given.
Limitations
Although RBCs have proven effective in treating waste
streams containing ammonia-nitrogen and organics, they are not
effective at removing most inorganics or non-biodegradable or-
ganics. Wastes containing high concentrations of heavy metals
and certain pesticides, herbicides, or highly chlorinated organ-
ics can resist RBC treatment by inhibiting microbial activity. Waste
streams containing toxic concentrations of these compounds
may require pretreatment to remove these materials prior to RBC
treatment [10, p. 3],
RBCs are susceptible to excessive biomass growth, particu-
larly when organic loadings are elevated. If the biomass fails to
slough off and a blanket of biomass forms which is thicker than
90 to 125 mils, the resulting weight may damage the shaft and
discs. When necessary, excess biofilm may be reduced by either
adjusting the operational characteristics of the RBC unit (e.g., the
rotational speed or direction) or by employing air or water to
shear off the excess biomass [11, p. 2].
In general, care must be taken to ensure that organic pr I-
lutants do not volatilize into the atmosphere. To control their
release, gaseous emissions may require offgas treatment [12, p.
31],
All biological systems, including RBCs, are sensitive to tem-
perature changes and experience drops in biological activity at
temperatures lower than 55°F. Covers should be employed to
protect the units from colder climates and extraordinary weather
conditions. Covers should also be used to protect the plastic discs
from degradation by ultraviolet light, to inhibit algal growth, and
to control the release of volatiles [13]. In general, organic deg-
radation is optimum at a pH between 6 and 8.5. Nitrification
requires the pH be greater than 6 [6, p. 61].
Additionally, nutrient and oxygen deficiencies can reduce
microbial activity, causing significant decreases in biodegrada-
tion rates [14, p. 39], Extremes in pH can limit the diversity of
the microbial population and may suppress specific microbes
capable of degrading the contaminants of interest. Fortunately,
these variables can be controlled by modifying the system de-
sign.
Technology Description
A typical RBC unit consists of 12-foot-diameter plastic discs
mounted along a 25-foot horizontal shaft. The total disc surface
area is normally 100,000 square feet for a standard unit and
150,000 square feet for a high density unit. Figure 1 is a dia-
gram of a typical RBC system.
As the RBC slowly rotates through the groundwater or
leachate at 1.5 rpm, a microbial slime forms on the discs. These
microorganisms degrade the organic and nitrogenous contami-
nants present in the waste stream. During rotation, approxi-
mately 40 percent of the discs' surface area is in contact with the
aqueous waste while the remaining surface area is exposed to
the atmosphere. The rotation of the media through the atmo-
sphere causes the oxygenation of the attached organisms. When
2
Engineering Bulletin: Rotating Biological Contactors
F-36
-------
Figure 1
Typical RBC Plant Schematic (12)
Offgas
Treatment
Offgas
Treatment
Offgas
Treatment
Primary
Treatment
Secondary
Clarifier
Effluent
Waste
RBC Units
Solids
Disposal
Disposal
operated properly, the shearing motion of the discs through the
aqueous waste causes excess biomass to shear off at a steady rate.
Suspended biological solids are carried through the successive
stages before entering the secondary clarifier [2, p. 13.101 ].
Primary treatment (e.g., darifiers or screens), to remove ma-
terials that could settle in the RBC tank or plug the discs, is often
essential for good operation. Influents containing high concen-
trations of fioatables (e.g., grease, etc.) will require treatment us-
ing either a primary clarifier or an alternate removal system [11,
P .2].
The RBC treatment process may involve a variety of steps,
as indicated by the block diagram in Figure 2. Typically, aque-
ous waste is transferred from a storage or equalization tank (1)
to a mixing tank (2) where chemicals may be added for metals
precipitation, nutrient adjustment, and pH control. The waste
stream then enters a clarifier (3) where the solids are separated
from the liquid. The effluent from the clarifier enters the RBC
(4) where the organics and/or ammonia are converted to innocu-
ous products. The treated waste is then pumped into a second
clarifier (5) for removal of the biological solids. After secondary
clarification the effluent enters a storage tank (6) where, depend-
ing upon the contamination remaining in the effluent, the waste
may be stored pending additional treatment or discharged to a
sewer system or surface stream. Throughout this treatment pro-
cess the offgases from the various stages should be collected for
treatment (7). The actual treatment train will, of course, depend
upon the nature of the waste and will be selected after the
treatability study is conducted.
Staging, which employs a number of RBCs in series, en-
hances the biochemical kinetics and establishes selective biologi-
cal cultures acclimated to successively decreasing organic load-
Figure 2
Block Diagram of the RBC Treatment Process
^ Offgases
Offgas
T reatment
Offgases
T reated
Effluents
Aqueous
Waste
Storage
Tank
Mixing
Tank
Storage
Tank
Clarifer
Clarifer
RBC Unit
Sludge Removal
Solids Removal
Engineering Bulletin: Rotatin^Blological Contactors
3
-------
ings. As the waste stream passes from stage to stage, progres-
sively increasing levels of treatment occur [2, p. 13.1 OS].
In addition to maximizing the system's efficiency, staging
can improve the system's ability to handle shock loads by ab-
sorbing the impact of a shock load in the initial stages, thereby
enabling subsequent stages to operate until the affected stages
recover [15, p. 10.200].
Factors effecting the removal efficiency of RBC systems in-
clude the type and concentration of organic* present, hydraulic
residence time, rotational speed, media surface area exposed and
submerged, and pre- and post-treatment activities. Design pa-
rameters for RBC treatment systems Include the organic and hy-
draulic load rates, design of the disc train(s), rotational velocity,
tank volume, media area submerged and exposed, retention
time, primary treatment and secondary darifier capacity, and
sludge production [8, p. 69],
Process Residuals
During primary clarification, debris, grit grease, metals, and
suspended solids (SS) are separated from the raw influent The
solids and sludges resulting from primary clarification may con-
tain metallic and organic contaminants and may require addi-
tional treatment Primary clarification residuals must be dUposed
of in an appropriate manner (e.g., land disposal, incineration,
soBdification. etc.).
Following RBC treatment the effluent undergoes second-
ary clarification to separate the suspended btomass solids from
the treated effluent. Refractory organics may contaminate both
the clarified effluent and residuals. Additional treatment of the
solids, sludges, and clarified effluent may be required. Clarified
secondary effluents which meet the treatment standards are gen-
erally discharged to a surface stream, while residual solids and
sludges must be disposed of in an appropriate manner, as out-
lined above for primary clarification residuals [2, p. 13.120).
Volatile organic compound (VOQ-bearing gases are often
liberated as a byproduct of RBC treatment. Care must be taken
to ensure that offgases do not contaminate the work space or
the atmosphere. Various techniques may be employed to con-
trol these emissions, including collecting the gases for treatment
[13].
Site Requirements
RBCs vary in size depending upon the surface area needed
to treat the hazardous waste stream. A single full size unit with
a walkway for access on either side of the unit takes up approxi-
mately 550 square feet [16]. The total area required for an RBC
system is site-specific and depends on the number, size, and con-
figuration of RBC units installed.
Contaminated groundwater, leachates, or waste materials
are often hazardous. Handling and treatment of these materials
requires that a site safety plan be developed to provide for per-
sonnel protection and special handling measures. Storage should
be provided to hold the process product streams until they have
been tested to determine their acceptability for disposal, reuse,
or release. Depending on the site, a method to store waste that
has been prepared for treatment may be necessary. Storage ca-
pacity will depend on waste volume.
Onsite analytical equipment capable of determining site-
specific organic compounds for performance assessment make
the operation more efficient and provide better information for
process control.
Performance Data
Limited information is available on the effectiveness of RBCs
in treating waste from Superfund sites. Most of the data came
from studies done on leachate from the New Lyme, Ohio;
Stringfelow, CaWomia; and Moyer, Pennsylvania Superfund sites.
The results of these studies are summarized below.
In order to compensate for the lack of Superfund perfor-
mance data, non-Superfund applications are also discussed. The
majority of the performance data for non-Superfund applications
were obtained from industrial RBC operations. Theoretically this
information has a high degree of application to Superfund
leachate and groundwater treatment.
The quality of the information present in this section has not
been determined. The data are included as a general guidance,
and may not be directly transferable to a specific Superfund site.
Good characterization and treatability studies are essential in
further refining and screening of RBC technology.
New Lyme Treatability Study
The EPA performed a remedy selection study on the leachate
from the New Lyme Superfund site located in New Lyme Town-
ship, Ashtabula County, Ohio, to help determine the applicabil-
ity of an RBC to treat hazardous waste from a Superfund site.
Samples of leachate collected from various seeps surrounding the
landfill showed that the leachate was highly concentrated. Re-
sults indicated that the leachate contained up to 2,000 mg/l dis-
solved organic carbon (DOC), 2,700 mg/l SBOD, and 5,200 mg/
I soluble chemical oxygen demand (SCOD) [17, p. 12]. (Note:
SCOD measures the soluble fraction of the organics amenable
to chemical oxidation, as well as certain inorganics such as sul-
fides, sulfites, ferrous iron, chlorides, and nitrites.)
Leachate from the New Lyme site was transported from New
Lyme to a demonstration-scale RBC located at the EPA's Testing
and Evaluation Facility in Cincinnati, Ohio. After an adequate
biomass was developed on the RBC discs using a primary efflu-
ent supplied by Mill Creek Treatment Facility (a local industrial
wastewater treatment facility), the units were gradually accli-
mated to an influent consisting of 100 percent leachate. Results
indicated that within 20 hours the RBC removed 97 percent of
the gross organics. as represented by DOC, from the leachate . -
(see Figure 3 and Table 2) [18, p. 7], Priority pollutants were .
either converted and/or stripped from the leachate during treat-
ment. After normal clarification, the effluent from the RBC was
Engineering Bulletin: Rotating Biological Contactors
F-38
-------
eligible for disposal into the sewer system leading to the Mill
Creek facility.
Stringfellow Treatability Study
A remedy selection study using an RBC was conducted on
leachate from the Stringfellow Superfund site located in Glen
Avon, California. After the leachate from this site received lime
treatment to remove metal contamination, the leachate was
transported to the EPA's Testing and Evaluation Facility in Cin-
cinnati for testing similar to the New Lyme study. The objective
of this study was to determine whether the leachate from
Stringfellow could be treated economically with an RBC system.
The leachate from this site was generated at a daily rate of
2,500 gallons. Compared to the New Lyme leachate, it con-
tained moderate concentrations of gross organics with DOC
values of 300 mg/l, SBOD values of 420 mg/l, and SCOD val-
ues of 800 mg/l [4, p. 44],
Results indicated that greater than 99 percent of SBOD was
removed, 65 percent of DOC was removed, and 54 percent
SCOD was removed within four days using the RBC laboratory-
scale treatment system [4, p. 44], Table 3 presents pertinent
information on the treatment of 100 percent leachate. Since
the DOC and SCOD conversion rates were low, a significant frac-
tion of the refractory organics remained following treatment Ac-
tivated carbon was used to reduce the DOC to limits acceptable
to the Mill Creek Treatment Facility.
BODT ¦ Total 8ioch«mical Oxygen Demand
NOj-N = Nitrogen as Nitrate
VSS = Volatile Suspended Soilds
Figure 3
Disappearance of DOC with Tim* (17, p. 14)
Experiments*
2.2
0 10 20 30 40
Time (hours)
• The Influent for Experiment 5 consisted 0/100 percent leachate and the
biomass on the R8Cs was acclimated. Nutrient addition was also employed
(at i ratio 0# 160/5/2 fc* C/N/P).
Moyer Treatability Study
During a recent remedy selection study, three treatability-
scale RBCs were used to degrade a low-BOD (26 mg/l), high
ammonia (154 mg/l) leachate from the Moyer Landfill Superfund
site in Lower Providence Township near Philadelphia, Pennsyl-
vania (19, p. 9 71 ]. The leachate has low organic strength (e.g.,
26 mg/l BOD, 358 mg/l COD, and 68 mg/l TOC) which is typi-
cal of an older landfill and it also contains mainly non-biodegrad-
able organic compounds [19, p. 972]. (Note: Total organic car-
bon, or TOC, is a measure of all organic carbon expressed as
carbon.) The abundance of ammonia found in the leachate
prompted investigators to attempt ammonia oxidation with an
RBC system. Relatively low substrate loading rates were em-
ployed during the study (0.2, 0.4, and 0.6 gpd/square foot of
disc surface area per stage). Ammonia oxidation was essentially
complete (98 percent) and a maximum of 80 percent of the BOD
and 38 percent of the COD in the leachate was oxidized [19, p.
980]. Runs performed using lower loading rates experienced the
largest removals. A limited denitrification study was also per-
formed using an anoxic RBC to treat an RBC effluent generated
during the aerobic segment of the treatability investigation. This
study demonstrated the feasibility of using denitrification to treat
Table 2
Removal of Pollutants from New Lyme Leachate (17, p. 17)
Experiments
Influent
Effluent
(mg/l)
(mg/l)
SBOD
2700
A
bod7
3000
6.6
DOC
2000
17
TOC
2100
19
SCOD
5200
33
N03"N
<1
60
ss
1400
6600
vss
240
2600
Volatile PP
Benzene
0.28
<0.002
Toluene
4.9
<0.002
Additional Volatiles
Cis 1,2-Dichloroethene
0.94
ND
Xylenes
2.8
ND
Acetone
140
ND
Methyl Ethyl Ketone
470
ND
Total Organic Halides
-
1.2
Total Toxic Organics
<0.250.
<0.010
Engineering Bulletin: Rotating Biological Contactors
F-39
5
-------
the nitrate produced by aerobic ammonia oxidation [19, p. 980].
Table 3
Treatment of 100% Strlngfeliow Leachate (4, p. 44)
Non-Superfund Applications
The Homestake Mine in Lead, South Dakota has operated
an RBC wastewater treatment plant since 1984. Forty-eight RBCs
treat up to 5.5 million gallons per day (MOD) (21,000 m') of
discharge water per day. The system was designed to degrade
thiocyanate, free cyanide, and metal-complexed cyanides, to re-
duce heavy metal concentrations, and to remove ammonia,
which is a byproduct of cyanide degradation [20, p. 2]. tight
parallel treatment trains, utilizing five RBCs in series, were em-
ployed to degrade and nitrify the metallurgical process waters
(see Table 4 for a characterization of the influent). The first two
REG in each train were used to degrade the cyanides and re-
move heavy toxic metals and particulate solids through biologi-
cal adsorption. The last three RBCs employed nitrification to
convert the ammonia to nitrate. Table 5 provides an average
performance breakdown for the system. During its operation,
overall performance improved significantly, as demonstrated by
an 86 percent increase in the systems ability to reduce total ef-
fluent cyanide concentrations (e.g., from 0.45 to 0.06
mg/1). Concurrently, the cost per kg to treat cyanide dropped
from $11.79 to J3.10, while the cost per mJ to treat effluent
decreased by 50 percent [21, p. 9]. In general, the system has
responded well to any upsets or disturbances. Diesel fuels, lu-
bricants, degreasers, biocides, dispersants, and flocculants have
been periodically found in the influent wastewater but normally
only create minor upsets in the performance of the plant Dur-
ing the life of the system, the number of upsets and the biomass's
ability to recuperate have both improved [21, p. 6].
A significant difference between the Homestake system and
the other RBC systems described within this report is that instead
of removing the metals contaminating the wastewater in the
pretreatment stage, metal reduction is accomplished through
bioadsorption during the treatment phase. Bioadsorption of
metals by biological cells is not unlike the use of activated car-
bon, however the number and complexity of binding sites on
the cell wall are enormous in comparison [20, p. 2].
In a study by Israel's Institute of Technology, a laboratory-
scale RBC was used to treat an oil refinery wastewater. The waste-
water had been pretreated using oil-water separation and dis-
solved air flotation. As summarized in Table 6, 91 percent of
the hydrocarbon and 97 percent of the phenol were removed,
as well as 96 percent of the ammonia-nitrogen [22, p. 4], By
gradually increasing the concentration of phenols present in the
influent (e.g., over a 5 day period) from 5 mg/l to 30 mg/l, the
system demonstrated that it was capable of quickly adapting to
influent changes and higher phenolic loads [22, p. 6]. During
this period, the RBC was able to maintain effluent COD concen-
trations at levels comparable to previous loadings. The system's
resilency was further demonstrated by its ability to recover from
a major disturbance (e.g., such that effluent COD removal was
interrupted) within 4 days [22, p. 7],
Technology Status
RBCs have been used commercially in the United States since
Leachate
(mg/l)
RBC
Effluent
(mg/l)
Use APC plus
Effluent
(mg/l)
SBOD
420
<3.0
0.9
BOD
440
22
DOC
300
110
20
TOC
310
22
SCOD
800
360
79
COD
840
95
ss
43
23
VS5
31
14
NHj-N
3.4
6.3
NO3-N
44
34
APC « Activated Powered Carbon
COD ¦ Chemical Oxygen Demand
Table 4
Homestake Mine Wastewater Matrix *
Decant
Water
(mg/l)
Mine
Water
(mg/l)
influent
Blend
(mg/l)
Thiocyanate
110-350
1-33
35-110
Total Cyanide
5.5-65.0
0.30-2.50
0.50-11.50
WAD Cyanide
3.10-38.75
0.50-1.10
0.50-7.15
Copper
0.5-3.1
0.10-2.65
0.15-2.95
Ammonia-N
5-10
5.00-19.00
6-12
Phosphorus-P
0.10-0.20
0.10-0.15
0.10-0.15
Alkalinity
50-200
150-250
125-225
pH
7-9
7-9
7.5-8.5
Hardness
400-500
650-1400
500-850
Temperature°C
1.0-27.2
24-33
5-25
WAD = Weak Acid Dissociable
'Adapted from reference (20, p 8]
Table 5
Influent, Effluent and Permit Concentrations at the
Homestake Mines (20. p. 8)
Influent Effluent Permit
(mg/l) (mg/l) (mg/l)
Thiocyanate
62.0
<0.5
-
Total Cyanides
4.1
0.06
1.00
WAD Cyanide
2.3
<0.02
0.10
Total Copper
0.56
0.07
0.13
Total Suspended Soilds
-
6.0 -
10.0
Ammonia-Nitrogen
5.60*
<0.50
1.0-3.9
•Ammonia peaks at 25 mg/l within the plant as a cyanide
degradation byproduct
6
Engineering Bulletin: Rotating Biological Contactors
-------
Table 6
Refinery Wastewater Quality Before and After
RBC Treatment (22, p. 4)
Constituent
Influent
(mg/l)
Effluent
(mg/l)
COD
Total
715
197
Soluble
685
186
BOD
Total
140
8
Soluble
128
6
Phenols
7.5
0.22
Suspended Solids
Total
32
7
Volatile
29
6
z
iT
z
12.8
0.48
the late 1960s to treat municipal and industrial wastes. In the
past decade, studies have been performed to evaluate the effec-
tiveness of RBO in treating leachate from hazardous waste sites.
Treatability studies have been performed on leachate from
the Stringfellow, New Lyme, and Moyer Superfund sites. Results
of these studies indicate that RBCs are effective in removing or-
ganic and nitrogenous constituents from hazardous waste
leachate. Additional research is needed to define the effective-
ness of an RBC in treating leachates and contaminated ground-
water and to determine the degree of organic stripping that
occurs during the treatment process. RBO are being used to
treat leachate from the New Lyme Superfund site.
RBCs require a minimal amount of equipment, manpower,
and space to operate. Staging of RBO will vary from site to site
depending on the waste stream. The cost to install a single RBC
unit with a protective cover and a surface area of 100,000 to
150,000 square feet ranges from S80,000 to S85,000 [16] [23].
During the Stringfellow treatability study researchers determined
that by augmenting the existing carbon treatment system with
RBCs, reductions in carbon costs would pay for the RBC plant
within 3.3 years [4, p. 44]. The RBC plant model used to for-
mulate this estimate was a scaled-up version of the pilot unit used
during the treatability study.
EPA Contact
Technology-specific questions regarding rotating biological
contactors may be directed to:
Edward |. Opatken
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Telephone: (513) 569-7855
Acknowledgments
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD), Risk
Reduction Engineering Laboratory (RREL), Cincinnati, Ohio, by
Science Applications International Corporation (SAIQ under
contract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work
Assignment Manager. This bulletin was written by Ms. Denise
Scott and Ms. Evelyn Meagher-Hartzell of SAIC.
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meetings and/or peer reviewing the document
Dr. Robert L. Irvine University of Notre Dame
Mr. Richard A. Sullivan Foth & Van Dyke
Ms. Mary Boyer SAIC
Mr. Cecil Cross SAIC
Engineering Bulletin: Rotating Biological Contactors u.s. pM^ one.: 199s - Ms-omeax* 7
-------
REFERENCES
1. Cheremisinoff, P.E. Biological Treatment of Hazardous
Wastes, Sludges, and Wastewater. Pollution Engineering,
Way 1990.
2. Envirex, Inc. Rex Biological Contactors: For Proven, Cost-
Effective Options in Secondary Treatment. Bulletin 315-
13A-5 1/90-3M.
3. Design Information on Rotating Biological Contactors,
EPA/600/2-84/106, U.S. Environmental Protection
Agency, |une 1984.
4. Opatken, E.J., H.K. Howard, and |.|. Bond. Stringfellow
Leachate Treatment with RBC. Environmental Progress,
Volume 7, No. 1, February 1988.
5. Walker Process Corporation. EnvlroDisc™ Rotating
Biological Contactor. Bulletin ll-S-88.
6. Opatken, E.J., and J.|. Bond. RBC Nitrification of High
Ammonia Leachates. Environmental Progress, Volume
10, No. 4, February 1991.
7. Guide to Treatment Technologies for Hazardous
Wastes at Superfund Sites. EPA/540/2-89/052, U.S.
Environmental Protection Agency, March 1989.
8. Data Requirements for Selecting Remedial Action
Technology. EPA/600/2-87/001, U.S. Environmental
Protection Agency, |anuary 1987.
9. Technology Screening Cuide forTreatment of
CERCLA Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
10. O'Shaughnessy et al. Treatment of Oil Shale Retort
Wastewater Using Rotating Biological Contactors.
Presented at the Water Pollution Control Federation,
55th Annual Conference, St. Louis, Missouri, October
1982.
11. Rotating Biological Contactors: U.S. Overview. EPA/
600/D-87/023, U.S. Environmental Protection
Agency, January 1987.
12. Nunno, T.J., and J.A. Hyman. Assessment of Interna-
tional Technologies for Superfund Applications. EPA/
540/2-88/003, U.S. Environmental Protection
Agency, September 1988.
13. Telephone conversation. Steve Oh, U.S. Army Corps
of Engineers, September 4, 1991.
14. Corrective Action: Technologies and Applications. EPA/
625/4-89/020, U.S. Environmental Protection Agency,
September 1984.
15. Lyco, Inc., Rotating Biological Surface (RBS) Waste-
water Equipment: RBS Design Manual. March 1986.
16. Telephone conversation. Cerald Ornstein, Lyco
Corporation, September 4, 1991.
17. Opatken, E.]., H.K. Howard, and J.|. Bond. Biologi-
cal Treatment of Leachate from a Superfund Site.
Environmental Progress, Volume B, No. 1, February
1989.
18. Opatken, E.|., H.K. Howard, and J.]. Bond. Biological
Treatment of Hazardous Aqueous Wastes. EPA/600/
D-87/1B4, |une 1987.
19. Spengel, O.B., and D.A. Dzombak. Treatment of Landfill
Leachate with Rotating Biological Contractors: Bench-
Scale Experiments. Research |oumal WPCF, Vol. 63, No.
7, November/December 1991.
20. Whit lock, |.L The Advantages of Biodegradation of
Cyanides, journal of the Minerals, Metals and Materials
Society, December 1989.
21. Whitlock, J.L. Biological Detoxification of Precious Metal
Processing Wastewaters. Homestake Mining Co., Lead,
SD.
22. Calil, N., and M. Rebhun. A Comparative Study of RBC
and Activated Sludge in Biotreatment of Wastewater from
an Integrated Oil Refinery. Israel Institute of Technology,
Haifa, Israel.
23. Telephone conversation. Jeff Kazmarek, Envirex Inc.,
September 4,1991.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Usa
$300
EPA/540/S-92/007
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
F-42
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United States Office of EPA/540/R-93/519b
Environmental Protection Solid Waste and August 1993
Agency Emergency Response
SEPA Guide for Conducting Treatability
Studies Under CERCLA:
Biodegradation Remedy Selection
Office of Emergency and Remedial Response
Hazardous Site Control Division OS-220 QUICK REFERENCE FACT SHEET
Section 121 (b) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 mandates
EPA to select remedies that "utilize permanent solutions and alternative treatment technologies or resource recovery technologies
to the maximum extent practicable" and to prefer remedial actions in which treatment that "permanently and significantly reduces
the volume, toxicity, or mobility of hazardous substances, pollutants, and contaminants is a principal element." Treatability studies
provide data to support remedy selection and implementation. They should be performed as soon as it becomes evident that the
available information is insufficient to ensure the quality of the decision. Conducting treatability studies early in the remedial
investigation/feasibility study (RI/FS) process should reduce uncertainties associated with selecting the remedy and should provide
a sound basis for the Record of Decision (ROD). Regional planning should factor in the time and resources required for these
studies.
This fact sheet provides a summary of information to facilitate the planning and execution of biodegradation remedy selection
treatability studies in support of the RI/FS and the remedial design/remedial action (RD/RA) processes. It is intended to provide
Remedial Project Managers (RPMs), On Scene Coordinators (OSCs), Potentially Responsible Parties (PRPs), and other interested
persons with enough information to determine whether biodegradation treatability studies may be considered in the remedy
selection phase of the RI/FS for the CERCLA site of interest. This fact sheet follows the organization of the "Guide for Conducting
Treatability Studies Under CERCLA: Biodegradation Remedy Selection,"EPA/540/R-93/514A", 1993. Detailed information on
designing and implementing remedy selection treatability studies for biodegradation is provided in the guidance document.
INTRODUCTION
There are three levels or tiers of treatability studies:
remedy screening, remedy selection, and RD/RA testing.
Treatability studies conducted during the RI/FS phase (rem-
edy screening and remedy selection) indicate whether the
technology can meet the cleanup goals for the site, whereas
treatability studies conducted during the RD/RA phase estab-
lish design and operating parameters for optimization of
technology performance. Although the purpose and scope of
these studies differ, they complement one another, since
information obtained in support of remedy selection may also
be used to support RD/RA.
Remedy screening studies are designed to provide a
quick and relatively inexpensive indication of whether biologi-
cal degradation is a potentially viable remedial technology.
The remedy screening evaluation should provide a prelimi-
nary indication that reductions in contaminant concentrations
are due to biodegradation and not abiotic processes such as
photodecomposition or volatilization.
Remedy selection studies should simulate conditions
during bioremediation, allowing researchers to determine the
technology's performance on a waste-specific basis. Bench-
scale testing is typically used for remedy selection testing;
however, it may fall short of providing enough information for
remedy selection. Pilot-scale testing also may be appropriate
for some sites. Bench-scale studies can, in some cases,
provide enough information for full-scale design.
F-43
RD/RA testing should provide accurate cost and perfor-
mance data, confirming that biodegradation rates and cleanup
levels determined during remedy selection can be achieved
for the site.
This fact sheet and its parent document, the "Guide for
Conducting Treatability Studies Under CERCLA: Biodegra-
dation Remedy Selection," EPA/540/R-93/514A primarily
focus on the remedy selection tier. These documents also
briefly discuss remedy screening and RD/RA testing.
TECHNOLOGY DESCRIPTION AND
PRELIMINARY SCREENING
Technology Description
Bioremediation generally refers to the breakdown of or-
ganic compounds (contaminants) by microorganisms. Biore-
mediation treatment technologies can be divided into two
categories, in situ and ex situ, based upon the location of the
contaminated medium during treatment.
• In Situ
In situ biological technologies treat contaminants inplace,.
eliminating the need for soil excavation and limiting volatile
releases into the atmosphere. As a result, many of the risks
and costs associated with materials handling are reduced or
eliminated.
- Printed on Recycled Paper
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Insitubioremertiation usually involves enhancing natural
biodegradation processes by adding nutrients, oxygen (if the
process Is aerobic), and in some cases, microorganisms to
stimulate the biodegradation ol contaminants. The technolo-
gy has primarily been used for the treatment of saturated
soils. In situ bioremediation is often used in conjunction with
a groundwater-pumping and soil-flushing system to circulate
nutrients and oxygen through a contaminated aquifer and
associated soils.
Bioventina is an in situ biological technology predomi-
nantly used to treat reasonably permeable, unsaturated soils.
Aeration systems, similarto those employed during soil vapor
extraction, are used during bioventing to supply oxygen to the
soil. An air pump, one or more air injection or vacuum
extraction probes, and emissions monitoring at the ground
surface are commonly used during bioventing. In order to
minimize contaminant volatilization, low air pressures and air
flow rates are typically utilized. Some systems, however,
utilize higher air flow rates, thereby combining bioventing with
soil vapor extraction.
• Ex Situ
Ex situ biological treatment technologies involve removal
of the contaminated media followed by onsite or offsite
treatment. Although media handling increases the costs of ex
situ treatment, ex situ approaches generally allow greater
control of process variables (e.g., pH, nutrient concentra-
tions, temperature, aeration).
Solid-phase bioremediatinn (sometimes referred to as
land treatment or land farming) is a process that treats soils
in above-ground treatment systems using conventional soil
management practices to enhance microbial degradation of
contaminants. Solid-phase bioremediation at CERCLA sites
usually involves placing excavated soil in an above-ground
soil treatment area. If required, nutrients and microorganisms
are added to the soil, which is tilled at regular intervals to
improve aeration and contact between the microorganisms
and the contaminants.
In slurrv-ohase bioremediation. excavated contaminated
soil is typically placed in an onsite, stirred-tank reactor where
the soil is combined with water to form a slurry. The solids
content of the slurry depends on the type of soil, the type of
mixing and aeration equipment available, and the rates of
contaminant removal that need to be achieved. The water
used in the process can be contaminated surfacewater or
groundwater, thus facilitating the simultaneous treatment of
contaminated soil and water. As with solid-phase bioreme-
diation. nutrients and microorganisms may be added to the
reactor to facilitate biodegradation.
Soil heap bioremediation involves piling contaminated
soil in heaps several meters high. Aeration is usually provided
by pulling a vacuum through the heap. Simple irrigation
techniques are generally used to maintain moisture content,
pH, and nutrient concentrations within ranges conducive to
the biodegradation of contaminants. The system can be
designed to control the release of VOCs by enclosing the soil
pile and passing the exhaust from the vacuum through acti-
vated carbon or biofilters.
Composting involves the storage of biodegradable waste
with a bulking agent (e.g., chopped hay or wood chips). The
structurally-firm bulking agent is usually biodegradable. Ad-
equate aeration; optimum temperature, moisture, and nutri-
ent concentrations; and the presence of an appropriate mi-
crobial population are necessary to enhance the decomposi-
tion of organic compounds The three basic types of compost-
ing systems are open windrow (where the piles are torn down
and rebuilt for aeration), static windrow (where air is forced
into the piles), and in-vessel (where tumbling, stirring, or
fbrced aeration are used).
Biofilters can be used to treat organic vapors in a manner
analogous to the biological treatment of wastewaters. By
providing bacteria with a surface on which to grow and optimal
oxygen, temperature, nutrients, moisture, and pH conditions,
biofilters can significantly reduce vapor phase organic con-
taminants. The primary components of biofilters are: an air
blower, an air distribution system, a moisturizing system, filter
media, and a drainage system. Removal efficiencies in the
range of 95 to 99 percent have been repo rted for light aliphatic
compounds, while lower removal efficiencies are common for
chlorinated aliphatic and aromatic compounds.
Technology Status
As of October 1992, approximately 149 CERCLA, Re-
source Conservation and Recovery Act (RCRA), and under-
ground storage tank (UST) sites, and other govenment regu-
lated sites have been identified by EPA Regions and States as
either considering (e.g., performing treatability studies), plan-
ning, operating full-scale, or having used biological treatment
systems. Approximately 62 percent of the sites are CERCLA
sites. 14 percent are RCRA sites, and 10 percent are UST
sites The remaining 14 percent represent Toxic Substance
Control Act (TSCA), and other Federal and State efforts.
Prescreening Characteristics
Before a treatability study is conducted, a literature search
should be performed to confirm whether the compounds of
interest are known to be amenable to biological treatment.
Evidence of biodegradation under dissimilar conditions, as
well as data relating to compounds of similar structure, should
be considered. If preliminary research indicates that bioreme-
diation is an unlikely candidate, further research may be
warranted. Before discarding biological remediation as an
option, expert recommendations regarding the technology's
potential should be obtained. The "Guide for Conducting
Treatability Studies Under CERCLA: Biodegradation Remedy
Selection", EPA/540/R-93/514A, lists references and elec-
tronic databases that can be useful when conducting the
literature search phase of a bioremediation project. Theguide
also provides contacts for technical assistance when deter-
mining the need or scope of a remedy selection treatability
study. One important resource for OSCs and RPMs is the
Technical Support Project (TSP) coordinated by EPA's Tech-
nology Innovation Office (703-308-8846). The TSP is oper-
ated by EPA laboratories and offers technical assistance
ranging from review of contractor work plans to assistance in
the performance of treatability studies.
The potential biodegradability of the contaminants of
concern is an important characteristic to be examined prior to
initiating treatability studies. Examples of classes of com-
pounds that are readily amenable to bioremediation are:
petroleum hydrocarbons such as gasoline and diesel; wood
treating wastes such as creosote and pentachlorophenol;
solvents such as acetone, ketones, and alcohols; and aro-
matic compounds such as benzene, toluene, xylenes, and
phenols. Several documents and review articles that present
detailed information on the biodegradabilityof compounds are
listed in the reference section of the complete guidance
document. However, discretion should be exercised when
using these reference materials, as microorganisms that can
F-44
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biodegrade compounds that have traditionally been consid-
ered nonbiodegradable are continually being isolated through
ongoing research and development efforts.
Site and soil characteristics that impact bioremediation
are listed in Table 1. The potential effects of these factors
upon candidate bioremediation technologies should also be
considered.
There is no steadfast rule that specifies when to proceed
with remedy screening, when to eliminate biodegradation as
a treatment technology, or when to proceed to remedy selec-
tion testing based on a preliminary screening analysis. An
analysis of the existing literature coupled with the site charac-
terization may provide the information required to make a
decision. However, wherr^n doubt, treatability studies are
recommended.
Technology Limitations
Many factors impact the feasibility of biodegradation.
These factors should be addressed prior to the selection of
Table 1. Site and Soil Characteristics Identified as
Important In Biological Treatment
In situ
Ex situ
Soil type
X
X
Extent of contamination
X
X
Soil profile properties
Boundary characteristics
X
Depth of contamination
X
Texture*
X
Structure
X
X
Bulk density*
X
Clay content
X
Type of clay
X
X
Cation exchange
X
X
Organic matter content*
X
X
pH*
X
X
Redox potential*
X
X
Hydraulic properties and conditions
Soil water characteristic curve
X
Field capacity/permanent wilting point
X
X
Water holding capacity*
X
X
Permeability* (under saturated and a range of
X
unsaturated conditions)
Infiltration rates*
X
Depth to impermeable layer or bedrock
X
Depth to groundwater, including seasonal
X
variations*
Flooding frequency
X
Runoff potential*
X
Geological and hydrogedogical factors
Subsurface geological features
X
Groundwater flow patterns and characteristics
X
Meterotogical and climatological data
Wind velocity and direction
X
Temperature
X
X
Precipitation -
X
X
Water budget
X
* Factors that may be managed to enhance soil treatment
biodegradation and prior to the investment of time and funds in
further testing. Some of these factors that may limit the use of
bioremedial technologies include the amount, location, extent,
and variability of the contamination. The physical form in which
the contaminants are distributed, as well as heterogeneities
within the media to be treated, may limit the applicability of
biodegradation.
Soil characteristics, such as nonuniform particle size
distribution, soil type, moisture content, hydraulic conductivity,
and permeability, can also significantly affect biodegradation.
Significant quantities of organic matter (humus, peat, non-
regulated anthropomorphic compounds, etc.) also may cause
high oxygen uptake rates, resulting in depleted oxygen sup-
plies during in situ application. Contaminant volatility is par-
ticularly important, especially in stirred or aerated reactors
where the contaminants can volatilize before being degraded.
The presence of either an indigenous or introduced micro-
bial population capable of degrading the contaminants of
concern is usually essential to the success of biological pro-
cesses. Each contaminant has a range of concentrations at
which the potential for biodegradation is maximized. Below
this range microbial activity may not occur without the addition
of a co-substrate. Above this range, microbial activity may be
inhibited and, once toxic concentrations are reached, eventu-
ally arrested. During inhibition, contaminant degradation gen-
erally occurs at a reduced rate. In contrast, at toxic concentra-
tions contaminant degradation does not occur. The concentra-
tions at which microbial growth is either supported, inhibited, or
arrested vary with the contaminant, media, and microbial
species.
Although preliminary data may be obtained that seem to
indicate that the technology is capable of reducing contamina-
tion levels to acceptable limits, the rate of contaminant removal
from soil during bioremediation exhibits asymptotic character-
istics. The initial rate of removal, after a potential lag period,
is rapid. With time, the rate decreases to a near-zero value,
and the contaminant concentration in the soil approaches a
fixed concentration that is typically nonzero (the asymptote).
Since the asymptote is difficult to predict and is sometimes
greater than the cleanup criteria, treatability testing must be
continued until either the removal goals are met or the asymp-
tote is reached.
THE USE OF TREATABILITY STUDIES IN
REMEDY EVALUATION
Treatability studies should be performed in a systematic
fashion to ensure that the data generated can support the
remedy evaluation and implementation process. A well-de-
signed treatability study can significantly reduce the overall
uncertainty associated with the decision, but cannot guarantee
that the chosen alternative will be completely successful. Care
must be exercised to ensure that the treatability study is
representative of the treatment (e.g., the sample is represen-
tative of waste to be treated) as it will be employed to minimize
uncertainty in the decision.
Treatability Testing Process
Treatability studies for a particular site will often entail
multiple tiers of testing. By balancing the time and cost
necessary to perform the testing with the risks inherent in the -
decision, the level of treatability testing required can be deter-
mined. Criteria for measuring the success of each level of
treatability study are listed in Table 2.
F-45
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Remedy screening is the first level of testing. It is used to
determine whether biodegradation is possible with the site-
specific waste material. These studies are generally low cost
(e.g., S10,000 to $50,000) and usually require 1 week to
several months to complete. Additional time must be allowed
for project planning, chemical analyses, interpretation of test
data, and report writing. Only limited quality control is re-
quired. These studies yield data indicating a technology's
potential to meet performance goals.
Remedy selection testing is the second level of testing.
To the maximum extent practical, remedy selection tests
should simulate site conditions during treatment, allowing
researchers to identity the technology's performance on a
waste-specific basis for an operable unit. These studies are
generally of moderate cost (e.g., $50,000 to $300,000) and
may require several weeks to two years to complete. They
yield data that verify that the technology is likely to meet
expected cleanup goals and can provide information in sup-
port of the detailed analysis of the alternative.
RD/RA testing is the third level of testing. By operating a
field unit under conditions similarto those expected during full-
scale remediation, the study can provide data required for final
full-scale design and accurate cost and time estimates. Unit
operating parameters can be optimized and the ability to
achieve cleanup levels can be confirmed. These studies are
of moderate to high cost (e.g., $ 100,000 to $500,000) and may
require several months or more to complete. They are per-
formed during the remedy implementation phase of a site
cleanup. Figure 1 shows the relationship of the three levels of
treatability study to each other and to the RI/FS process.
Applicability of Treatability Tests
Before conducting treatability studies, the objectives of
each tier of testing must be established. Biodegradation treat-
ability study objectives are based upon the specific needs of
the RI/FS. There are nine evaluation criteria specified in the
document, 'Guidance for Conducting Remedial Investigations
and Feasibility Studies Under CERCLA" (EPA/540/6-89/004).
A detailed analysis of different remedial alternatives using the
nine CERCLA criteria is essential. Treatability studies provide
data for up to seven of these criteria.
These seven criteria are:
• Overall protection of human health and the environment
• Compliance with applicable or relevant and appropriate
requirements (ARARs)
Table 2. Biodegradation Criteria for Each Treatability Study Tier
Criteria Remedy screening Remedy selection Remedy design
Biodegradation of most-
resistant contaminants of
concern
>20% net removal compared to
removal in inhibited control
Meets cleanup standards under test
conditions
Meets cleanup standards under
site conditions
Initial contaminant
concentration
Optimal for technology
Maximum concentration expected
during remediation
Actual range of concentrations
expected during remediation
Environmental condtions
Optimal for technology (include
site conditions if possible)
Simulate expected site treatment
conditions
Actual site treatment conditions
for the specific technology
Extent of biodegradation
Estimate*
Quantify
Quantify
Biodegradation rate
Crude estimate*
Defensible estimate
Quantify
Estimate time to reach
deanup standards
NA
Estimate
Refined estimate
Mass balance
Crude*
Closure or defensible explanation
Closure or defensible explanation
Tone byproducts
Detect*
Test for if appropriate*
Test for if appropriate
Process control and reBabJlity
NA
Assess potential
Demonstrate
Microbial activity
Crude measure*
Verify/quantity*
Quantify/monitor*
Process optimization
NA
Estimate'
Refined estimate
Cost estimate for full-scale
NA
Rough, -30%, +50%
Detailedfrefined
Bid specifications
Experimental scale
- NA
Usually bench-scale
NA
Either bench- or pilot-scale
Nearty complete ...
Usually pilot- or full-scale
Not required, although sometimes possible to address significantly.
4
F-46
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Remedial Investigation/
Feasibility Study (RI/FS)
Identification
of Alternatives
Record of
Decision -
(ROD)
Remedial Design/
- Remedial Action-
(RD/RA)
Remedy
Selection
Scoping
- the •
RI/FS
Literature
Screening
and
Treatability
Study Scoping
Site
Characterization
and Technology
Screening
Evaluation
"of Alternatives"
Implementation
of Remedy
REMEDY
SCREENING
to Determine
Technology Feasibility
REMEDY SELECTION
to Develop Performance
and Cost Data
RD/RA
to Develop Scale-Up,
Design, and Detailed
Cost Data
Figure 1. The Role of Treatability Studies In the RI/FS and RD/RA Process.
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, or volume through treat-
ment
• Short-term effectiveness
• Implementability
• Cost
The two remaining CERCLA criteria, State and commu-
nity acceptance, are based in part on the preferences and
concerns of the State and community regarding alternative
technologies. An available remediation technology may be
eliminated from consideration if the state or community ob-
jects to its use. Table 3 shows how the study goals of a remedy
selection treatability test address RI/FS criteria and the ex-
perimental parameters measured to assess the achievement
of those goals.
REMEDY SELECTION TREATABILITY
STUDY WORK PLAN
Carefully planned treatability studies are necessary to
ensure that the data generated are useful for evaluating the
validity or performance of a technology. The Work Plan,
prepared by the contractor when the Work Assignment is in
place, sets forth the contractor's proposed technical approach
for completing the tasks outlined in the Work Assignment. It
also assigns responsibilities and establishes the project sched-
ule and costs. The Work Plan must be approved by the RPM
before initiating subsequent tasks. A suggested organization
of the Work Plan is provided in the "Guide for Conducting
Treatability Studies Under CERCLA: Biodegradation Remedy
Selection", EPA7540/R-93/514a.
Test Goals
Remedy selection treatability goals must consider the
existing site contaminant levels and cleanup goals for soils,
sludges, and water at the site. The ideal technology perfor-
mance goals for remedy selection treatability tests are the
cleanup criteria for the site. Example remedy selection goals
are listed in Table 3. In previous years, cleanup goals often
reflected background site conditions. Attaining background
cleanup levels through treatment has proved impractical in
many situations. The present trend is toward the development
of site-specific cleanup target levels that are risk-based rather
than background-based.
Experimental Design
Careful planning during treatability study design is re-
quired to ensure adequate treatability study data are obtained.
Among other requirements, the experimental design must
identify the critical parameters and determine the required
number of replicate tests. Treatability studies can be designed
to simulate aerobic conditions, or may be planned to assess
biodegradation under anaerobic conditions. Ultimately, rem-
edy selection studies should strive to simulate the conditions
encountered during full-scale applications of the technology
under study.
F-47
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Table 3. Ability of Remedy Selection Treatability Studies to Address Rl/FS Criteria
Study goals
Experimental parameters
Rl/FS criteria*
Compare performance, cost, etc., of
different treatment systems at a
specific site
Dependent on type of treatment systems
compared
derail protection of human health and
the environment
Compliance with ARARs
Long-term effectiveness and permanence
Reduction of toxicity, mobility, and volume
through treatment
Short-term effectiveness
Implementability
Cost
Measure the initial and final
contaminant concentrations, and
calculate the percentage of
contaminant removal from tf>e soil,
sludge, or water through
biodegradation
Contaminant concentration
• Overall protection of human health and
fre environment
• Compliance with ARARs
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, and volume
through treatment
Estimate the type and concentration Contaminant/byproduct concentration
of residual contaminants and /or
byproducts left in the soil after
treatment
Develop estimates for reductions in
contaminant toxicity, volume, or
mobility
Identify contaminant fate and the
relative removals due to biological
and nonbiologicai removal
mechanisms
Produce design information required
for next level of testing
Develop preliminary cost and time
estimates for full-scale remediation
Evaluate need for pretreatment and
requirements tor long-term
operation, maintenance, and
monitoring
Evaluate need for additional steps
within treatment train
Assess ability of bioremediation to
meet site-specific cleanup levels
Determine optimal conditions for
biodegradation and evaluate steps
needed to stimulate biodegradation
Contaminant concentration, toxicity testing
Contaminant concentrations present in
solid, liquid, and gaseous phases taken
from test and control reactors, oxygen
uptake/C02 evolution
Temperature, pH, moisture, nutrient
concentrations and delivery, concentration
and delivery of electron donors and
acceptors, microbial composition, soil
characteristics, test duration, nonbiologicai
removal processes
Treatability study cost (i.e., material and
energy inputs, residuals quality and
production, O&M costs, where
appropriate), test duration, time required to
meet performance goals
Soil characteristics, contaminant
concentration/toxicity
Soil characteristics, contaminant
concentration, nonbiologicai removal
processes, residual quality (relative to
further treatment anchor disposal
requirements)
Contaminant concentration
Temperature, pH, nutrient concentrations
and delivery, concentration and delivery of
electron donors and acceptors, microbial
composition, soil characteristics, test
duration, contaminant concentration
• Overall protection of human health and
the environment
e Compliance with ARARs
e Long-term effectiveness and permanence
e Reduction of toxicity, mobility, and volume
through treatment
• Overall protection of human health and
the environment
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, and volume
througn treatment
• Short-term effectiveness
• Implementability
• Cost
Short-term effectiveness
Implementability
Cost
• Compliance with ARARs
• Long-term effectiveness and permanence
• Short-term effectiveness
• Implementability
• Cost
• Overall protection of human health and
the environment
• Long-term effectiveness and permanence
• Implementability
• Cost
• Overall protection of human health and
the environment
• Compliance with ARARs
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, and volume
through treatment
• Short-term effectiveness
• Implementability
• Cost
* Depending on specific components of the remedy selection treatability study, additional criteria may be applicable.
6
F-48
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A number of factors influence the basic design of biologi-
cal studies. These factors have a profound impact on both the
treatability study operation and utility. Important factors to be
considered when designing a biological treatability study
include the following:
Overall test objectives (as dictated by site remediation
objectives)
Specific removal goals or desired cleanup levels (as set
for a specific site)
Soil characteristics (soils with higher permeability are
more amenable to in situ biodegradation)
pH (most microbial degraders thrive when the pH is
between 6.5 and 8.5)
Temperature (optimum range is usually between 15°C
and 30°C for aerobic processes and 25°C to 35°C for
anaerobic processes)
Moisture (optimum range is usually between 40 and 80
percent of field capacity)
Nutrients (concentrations should be maintained at a rea-
sonably moderate but steady-state concentration deter-
mined experimentally)
Electron acceptors (usually oxygen derived from air, pure
oxygen, ozone, or hydrogen peroxide for aerobic studies
and nitrates for anaerobic tests)
Microorganisms (the use of introduced versus indigenous
populations)
Duration of test (sufficient to determine ability of treat-
ment to meet removal goals)
Inhibitory compounds and their control (dilution of media
may be required)
Impact of nonbiological removal processes (extent of
volatilization, sorption, photodecomposition, leaching, as
experienced by inhibited controls)
• Toxicity testing (to evaluate the risk reduction experi-
enced during treatment)
• Bioavailability (contaminants that biodegrade easily will
be utilized earliest)
In situ remedy selection treatability studies are either field
plot or soil column designs. Soil column studies may also be
performed ex situ, usually within a laboratory setting. Three
additional ex situ experimental designs are soil pans, soil
slurries, and contained soil treatment systems. Table 4 pre-
sents information on remedy selection treatability study ex-
perimental designs, including their applicability, scale, typical
size, and duration.
The test system used during remedy selection testing can
consist of a single large reactor or multiple small reactors.
Studies which employ large reactors include field studies,
large flask studies, and soil pan studies. Multiple reactors
consisting of serum bottles, small slurry reactors, and small
soil reactors may be set up in place of a single large system.
When a single reactor is used, small samples may be removed
at various times and compared to samples from control reac-
tors. When using large reactors, care should be taken to
ensure that the availability of supplements (i.e., oxygen and
moisture) are adequate, allowing for consistent degradation
rates within the reactor. Additionally, sampling must be sized
so that it does not affect the operation of the overall unit.
Remedy selection treatability tests should include controls to
measure the impact of nonbiological processes, such as vola-
tilization, sorption, chemical degradation, migration, and pho-
todecomposition. Inhibited controls can be established by
adding formaldehyde, mercuric chloride (during non-EPA stud-
ies), sulfuric acid (added to lower the pH to 2 or below), or
sodium azide to retard microbial activity. Contaminant con-
centrations are measured in both the test reactors and the
control reactors at the beginning of the study (T„), at interme-
diate times, and at the end of the study. The mean contaminant
concentrations in both the control and test reactors at the end
of the test can be compared to their initial concentrations to see
if a statistically significant change in concentration has oc-
curred. The decrease in the control reactors may be attributed
Table 4. Remedy Selection Treatability Study Characteristics
Type of study
Applicability
Scale
Size
Duration
Field plots
Soil columns
Soil pans
Slurry-phase
reactors
Contained soil
.systems
In situ bioremediation
In situ bioremediation
Solid-phase treatment
Slurry-phase and
solid-phase (occasionally)
treatment
Composting, soil heap
bioremediation, and
solid-phase treatment
Field-scale
Lab-and
field-scale
Lab-scale
Field-scale
Lab-scale
Lab- and
field-scale
1 to 1,111 yd plot of land* 2 months to 2 years
0.01 - 3,200 ft3 of soil,
sand, sediment, or stone
2 to 100 lbs of soil
Greater than 20 gallons of
slurried media
1 week to 6 months
1 to 6 months
2 to 3 months
1 fluid oz to 20 gallons 1 to 8 weeks
7 ft3 to S.god'yds of soil 10 days to 10 months
* Field plot sizes are given as areas rattier than volumes because treatment depths are frequently undefined.
7
F-49
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to abiotic mechanisms, while the decrease in the test reactors
would be a result of abiotic and biotic processes. The differ-
ence in mean contaminant concentrations between the test
reactors and the inhibited control reactors will show whether
there is a statistically significant reduction in contaminant
concentration due to microbial activity. Care should be taken
to assess the effects that the different sterilizing agents can
have on the chemical behavior of the soil-contaminant sys-
tem.
Complete sterilization of soils can be difficult to accom-
plish. Incomplete mixing of sterilization agents with soils can
result in pockets of surviving microbes in soil pores. In some
cases, microbial populations can transform and detoxify ster-
ilizing agents. Additional sterilizing agents can be provided
during the test to maintain reduced biological activity. The
effectiveness of sterilizing agents can be measured by tech-
niques such as microbial enumeration, respirometry, and
enzyme analysis. Unless these or similar techniques show
very low microbial activity, it may not be possible to distinguish
between removal of contaminants by abiotic and biological
processes in the control reactors. However, complete steril-
ization of the control is not necessary provided biological
activity is inhibited to the extent that a statistically significant
difference between the test and control means can be deter-
mined.
When designing a treatability study, the types of equip-
ment required for the test must be considered. Standard
laboratory equipment such as mixing flasks and sample col-
lection bottles should be available for all treatability studies. A
wide variety of equipment is employed during biodegradation
treatability testing to contain the media under study or isolate
it from the environment. During soil column studies, a metal,
plastic, or glass cylinder may be used onsite or offsite as part
of a laboratory study. Field plots, on the other hand, may
require that in-ground barriers, such as sheets of steel driven
into the ground, or above-ground barriers such as berms be
used to separate testing plots from one another or from soil
located outside of the testing area. Slurry reactors, which
range in size from 1 fluid ounce vials to 70,000-gallon lagoons,
typically utilize 0.1- to 130-gallon vessels. In contrast, con-
tained soil treatment systems will generally require a bermed,
watertight area in which the soil can be placed. The vessels
required for contained soil treatability studies also vary con-
siderably, since they may be designed to simulate compost-
ing, soil heaping, or other solid-phase biotreatment technolo-
gies. Depending on the type and scale of the system, a
leachate collection system and other accessories may also be
required.
SAMPLING AND ANALYSIS PLAN
The Sampling and Analysis Plan (SAP) consists of two
parts: the Field Sampling Plan (FSP) and the Quality Assur-
ance Project Plan (QAPP). A SAP is required for all field
activities conducted during the RI/FS. The purpose of the SAP
is to ensure that samples obtained for characterization and
testing are representative and that the quality of the analytical
data generated is satisfactory. The SAP addresses field
sampling, waste characterization, and sampling and analysis
of the treated wastes and residuals from the testing apparatus
or treatment unit. The SAP is usually prepared after Work Plan
approval.
TREATABILITY DATA INTERPRETATION
When conducting treatability studies, the test results and
goals for each tier must be properly evaluated to assess the
treatment potential of bioremediation. The remedy screening
tier establishes the general applicability of the technology. The
remedy selection testing tier demonstrates the applicability of
the technology to a specific site. The RD/RA tier provides
information in support of the evaluation criteria.
Interpretation of remedy selection test results should
allow the RPM or OSC to determine whether the bioremedia-
tion technology used Is capable of meeting cleanup standards
under simulated (or actual) site conditions. The experimental
design of the study should have been constructed to produce
quantitative and statistically defensible estimates of the extent
and rate of biodegradation. Ideally, a statistical evaluation of
the difference between biodegradation rates when parameters
such as nutrient addition, loading rate, and microbial compo-
sition are varied, should also be designed. Example 1 de-
scribes a remedy selection treatability test and the interpreta-
tion of the test results.
Estimation of Costs
Complete and accurate cost estimates are required in
order to fully recommend technologies for site remediation.
Consequently, when making preliminary cost estimates for
full-scale bioremediation, achievable cleanup levels, degrada-
tion rates, concentration and application frequencies of vari-
ous degradation enhancing supplements (e.g., nutrients, lime,
water, etc.), contaminant migration controls, and monitoring
requirements must be considered. The impact these param-
eters have on labor, analytical, material and energy costs, as
well as the unit's design and possible pre- and post-treatment
requirements, also must be considered.
Generally, large-scale field tests can be designed to
simulate full-scale performance and costs more accurately
than laboratory studies. However, estimating full-scale cost
from treatability study data can be difficult. Given the variability
and interaction of factors such as soil temperature, pH, mois-
ture, heterogenous contaminant concentrations, and optimal
nutrient concentrations, empirical results may not always de-
pict the range of reasonable bioremediation results. One
approach to examining the variability and interaction of these
factors is simulation modeling. Simulation models(e.g., Monte
Carlo models) attempt to quantify the probability that a certain
set of events or values will occur based upon available empiri-
cal data. Using probabilistic simulation methods can produce
time and cost estimates for a particular confidence level and a
specific level of certainty (e.g., the ability to state with 90
percent certainty that the cost of the project will be within ±40
percent of the estimate).
TECHNICAL ASSISTANCE
Information from existing literature and consultation with
experts are important factors in determining the need for and
ensuring the usefulness of treatability studies. A reference list
of sources on treatability studies is provided in the 'Guide for
Conducting Treatability Studies Under CERCLA" (EPA/540/R-
92/071 a).
It is recommended that a Technical Advisory Committee
(TAC) be used. This committee includes experts who provide
technical support from the scoping phase of the treatability
study through data evaluation. Members of the TAC may
include representatives from EPA (Regions or ORD), other •:
Federal agencies, States, and consulting firms.
The Office of Solid Waste and Emergency Response and
Office of Research and Development operate the TSP which
provides assistance in the planning, performance, and review
8
F-50
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Example 1
A remedy selection treatability study was performed to evaluate a slurry-phase technology's ability to remediate an
impoundment contaminated with petroleum refinery sludges. Surfactants and nutrients were added. Reactor performance
was monitored by measuring the oxygen uptake rate and oil and grease (O&G) removal. Based on extensive experience
with O&G biodegradation, toxicity testing was not performed.
The average initial O&G concentration in the sediment was 41,000ppm, the maximum concentration expected in the full-
scale (70,000 gallon), slurry bioreactor. A cleanup goal of 20,000 ppm O&G was targeted during the study. After 4 weeks,
the average O&G concentration in the inhibited control was reduced to 39,000 ppm, a reduction of nearly 5 percent. The
average O&G concentration in the biologically active system was reduced to 14,000 ppm, a 66 percent reduction in the
same time period. The leveling out of O&G concentrations at the end of the experiment indicates that the maximum extent
of biodegradation achievable under the test conditions had been reached.
O&G
Sample
T
0
T,
T3
\
Bioreactor
Replicate 1
39,000
32,000
21,000
13,000
14,000
Replicate 2
41,000
34,000
24,000
15,000
16,000
Replicate 3
43,000
39,000
24,000
17,000
12,000
Mean Value
41,000
35,000
23,000
15,000
14,000
Inhibited Control
Replicate 1
39,000
36,000
37,000
37,000
42,000
Replicate 2
41,000
39,000
40,000
41,000
36,000
Replicate 3
43,000
42,000
40,000
39,000
39,000
Mean Value
41,000
39,000
39,000
39,000
39,000
The average contaminant concentration in the slurry-phase bioreactor at each time-point is compared to the average
contaminant concentration in the inhibited control at the same time-point to measure the biodegradation at that time-point.
The inhibited control accounts for contaminant losses due to volatilization, adsorption to soil particles, and chemical
reactions. Some contaminant loss in the control due to biodegradation may occur since total sterilization is difficult to
accomplish. However, an O&G analysis of the extract generated from the slurry-phase reactor indicated that abiotic
losses were due mainly to adsorption. Since a statistically significant difference between the test and control means
exists, O&G reductions in the test bioreactor were attributed to biodegradation.
of treatability studies. For further information on treatability
study support or the TSP, please contact:
Groundwater Fate and Transport Technical
Support Center
Robert S. Kerr Environmental Research
Laboratory, (RSKERL)
Ada, OK 74820
Contact: Don Draper
(405) 332-8800
Engineering Technical Support Center (ETSC)
Risk Reduction Engineering Laboratory (RREL)
Cincinnati, OH 45268
Contact: Ben Blaney or Joan Colson
(513) 569-7406 or (513) 569-7501
FOR FURTHER INFORMATION
Sources of information on treatability studies and biore-
mediation are listed in the "Guide for Conducting Treatability
Studies Under CERCLA" (EPA/540/R-92/071 a) and the "Guide
for Conducting Treatability Studies Under CERCLA: Biodeg-
radation Remedy Selection" (EPA/540/R-93/541 A). Addition-
ally, the Office of Emergency and Remedial Response's Haz-
ardous Site Control Division (OERR/HSCD) Regional Coordi-
nator for each Region should be contacted for information and
assistance.
ACKNOWLEDGMENTS
This fact sheet and the corresponding guidance document
were prepared for the U.S. Environmental Protection Agency,
Office of Research and Development, Risk Reduction Engi-
neering Laboratory, Cincinnati, Ohio by Science Applications
International Corporation (SAIC) under Contract No. 68-C8-
0061 and Contract No. 68-C0-0048. Mr. Ed Opatken served as
the EPA Technical Project Monitor. Mr. Jim Rawe served as
SAIC's Work Assignment Manager. Mr. Rawe, Ms. Evelyn
Meagher-Hartzell, and Ms. Sharon Krietemeyer (SAIC) were
the primary technical authors. Mr. Derek Ross (ERM) and Mr,.
Kurt Whitford (SAIC) served as a technical experts.
Many Agency and independent reviewers have contribut-
ed their time and comments by participating in the expert
review meetings or peer reviewing the guidance document.
F-51
9
~ u.S. GOVERNMENT MINTING OFFICE: • 750-971/800*9
-------
Engineering^
SEPA Mobifeilfa
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
tec hnoiogies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants, and
contaminants as a principal element." The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment ana site remediation
technologies and related issues. They provide summaries of
and 'eferences for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
s.te charactenstics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Acdenda will be issued penodically to update the onginal
bulletins.
Abstract
Incineration treats organic contaminants in solids and
liquids by subjecting them to temperatures typically greater
than 1000'F in the presence of oxygen, which causes the
volatilization, combustion, and destruction of these compounds.
This oulletin describes mobile/transportable incineration systems
that can be moved to and subsequently removed from Superfund
and other hazardous waste sites. It does not address other
thermal processes that operate at lower temperatures or those
that operate at very high temperatures, such as a plasma arc.
It is applicable to a wide range of organic wastes and is generally
not used in treating inorganics and metals. Mobile/transportable
incinerators exhibit essentially the same environmental
performance as their stationary counterparts. To date, 49 of the
95 records of decision (RODs) designating thermal remedies at
Superfund sites have selected onsite incineration as an integral
part of a preferred treatment alternative. There are 22
* [refcrerce number. p*ge numb«r)
commercial-scale units in operation [5]*. This bulletin provides
information on the technology applicability, the types of residuals
resulting from the use of the technology, the latest performance
data, site requirements, the status of the technology, and
where to go for further information.
Technology Applicability
Mobile/transportable incineration has been shown to be
effective in treating soils, sediments, sludges, and liquids
containing pnmarily organic contaminants such as halogenated
and nonhalogenated volatiles and semivolatiles, polychlorinated
biphenyls (PCBs), pesticides, dioxins/furans, organic cyanides,
and organic con-osives. The process is applicable for the
thermal treatment of a wide range of specific Resource
Conservation and Recovery Art (RCRA) wastes and other
hazardous waste matrices that indude pesticides and herbicides,
spent halogenated and nonhalogenated solvents, chlorinated
phenol and chlorinated benzene manufacturing wastes, wood
preservation and wastewater sludge, organic chemicals
production residues, pesticides production residues, explosives
manufacturing wastes, petroleum refining wastes, coke industry
wastes, and organic chemicals residues (1 ] [2] [4] [6 through 11 ]
[131
Information on the physical and chemical characteristics of
the waste matrix is necessary to assess the matrix's impart on
waste preparation, handling, and feeding; incinerator type,
performance, size, and cost; air pollution control (APQ type
and size; and residue handling. Key physical parameters
include waste matrix physical characteristics (type of matrix,
physical form, handling properties, and particle size), moisture
content, and heating value. Key chemical parameters include
the type and concentration of organic compounds including
PCBs and dioxins, inorganics (metals), halogens, sulfur, and
phosphorous.
The effectiveness of mobile/transpoitable incineration on
general contaminant groups for various matrices is shown in
Table 1 [7, p. 9). Examples of constituents within contaminant
groups are provided in Reference 7, Technology Screening
Guide for Treatment of CERCLA Soils and Sludges." This table
F-52
-------
Table 1
Effectiveness of Inclnerafton on General Contaminant
Groups for Soil, Sediment, Sludge, and liquid
is based on current available information or professional
judgment when no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiency achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated effectiveness
means that, at some scale, treatability was tested to show that
the technology was effective for a particular contaminant and
matrix. The ratings of potential effectiveness or no expected
eff ectiveness are based upon expert judgment. Where potential
effectiveness is indicated, the technology is believed capable of
successfully treating the contaminant group in a particular
matrix. When the technology is not applicable or will probably
not work for a particular combination of contaminant group
and matrix, a no-expected-effectiveness rating is given. Other
sources o(general observations and average removal efficiencies
for different treatability groups are the Superfund LDR Guide
#6A, "Obtaining a Soil and Debris Treatability Variance for
Remedial Actions," (OSWER Directive 9347.3-06FS [1 3], and
Superfund LDR Guide #6B, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions," (OSWER Directive
9347.3-07FS [14],
Limitations
Toxic metals such as arsenic, lead, mercury, cadmium, and
chromium are not destroyed by combustion. As a result, some
will be present in the ash while others are volatilized and
released into the flue gas (1, pp. 3-6].
Alkali metals, such as sodium and potassium, can cause
severe refractory attack and form a sticky, low-melting-point
submicron particulate, which causes APC problems. A low feed
stream concentration of sodium and potassium may be achieved
through feed stock blending [1, pp. 3-11).
When PCBs and dioxins are present, higher temperatures
and longer residence times may be required to destroy them to
levels necessary to meet regulatory criteria (7, p. 34].
Moisture/water content of waste materials can create the
need to co-incinerate these materials with higher BTU streams,
or to use auxiliary fuels.
The heating value (BTU content) of the feed material
affects feed capacity and fuel usage of the incinerator. In
general, as the heating value of the feed increases, the feed
capacity and fuel usage of the incinerator will decrease. Solid
materials with high calorific values also may cause transient
behaviors that further limit feed capacity [9, p. 4],
The matrix characteristics of the waste affect the
pretreatment required and the capacity of the incinerator and
can cause APC problems. Organic liquid wastes can be pumped
to and then atomized in the incinerator combustion chamber.
Aqueous liquids may be suitable for incineration if they contain
a substantial amount of organic matter. However, because of
the large energy demand for evaporation when treating large
volumes of aqueous liquids, pretreatment to dewater the waste
may be cost effective [1, pp. 3-14], Also, if the organic content
is low, other methods of treatment may be more economical.
For the infrared incinerator, only solid and solid-like materials
within a specific size and moisture content range can be
processed because of the unique conveyor belt feed system
within the unit.
Sandy soil is relatively easy to feed and generally requires
no special handling procedures. Clay, which may be in large
clumps, may require size reduction. Rocky soils usually require
screening to remove oversize stones and boulders. The solids
can then be fed by gravity, screw feeder, or ram-type feeder into
the incinerator. Some types of solid waste may also require
crushing, grinding, and/or shredding prior to incineration [1,
pp. 3-17].
The form and structure of the waste feed can cause periodic
jams in the feed and ash handling systems. Wooden pallets,
metal drum closure rings, drum shards, plastics, trash, clothing,
and mud can cause blockages if pooriy prepared. Muddy soils
can stick to waste processing equipment and plug the feed
system [9, p. 8],
son/
Contaminant Croups
Sediment
Sludge
Liquid
Halogenated volatiles
¦
¦
¦
Halogenated semivolatiles
¦
¦
¦
Nonhalogenated volatiles
¦
¦
¦
Nonhalogenated semivolatiles
¦
¦
¦
C
o
PCBs
¦
¦
¦
?
O
Pesticides (halogenated)
T
¦
¦
Dioxins/Furans
¦
¦
¦
Organic cyanides
T
T
T
Organic corrosives
T
T
T
Volatile metals
~
~
~
Nonvolatile metals
~
~
~
c
Q
Asbestos
a
~
a
r
Radioactive materials
a
~
a
***
Inorganic corrosives
a
~
a
Inorganic cyanides
T
T
T
|
Oxidizers
T
T
T
o
to
«
Reducers
T
T
T
¦
Demonstrated Effectiveness: Successful treatability test at some scale
completed
~
Potential Effectiveness: Expert opinion that technology will wort
~
No Expected Effectiveness: Expert opinion that technology wi
not work
2
Engineering Bulletin: Mobile/Transportable Incineration Treatment
F-53
-------
The particle size distribution of the ash generated from the
waste can affect the amount of particulate carry-over from the
combustion chamber to the rest of the system (9, p. 16],
Incineration of halogens, such as fluorine and chlorine,
generates acid gases that can affect the capacity, the water
removal and replacement rates that control total dissolved
solids in the process water system, and the particulate emissions
[9, p. 12], The solutions used to neutralize these acid gases add
to the cost of operating this technology.
Organicphosphorouscompoundsform phosphorous pent-
oxide, which attacks refractory material, causes slagging prob-
lems and APC problems. Slagging can be controlled by feed
blending or operating at lower temperatures (1, pp. 3-10).
Technology Description
Figure 1 is a schematic of the mobile/transportable
incineration process.
Waste preparation (1) incfudes excavation and/or moving
the waste to the site. Depending on the requirements of the
incinerator type for soils and solids, various equipment is used
to obtain the necessary feed size. Blending is sometimes
required to achieve a uniform feed size and moisture content or
to dilute troublesome components (1, pp. 5-19].
The waste feed mechanism (2), which varies with the type
of the incinerator, introduces the waste into the combustion
system. The feed mechanism sets the requirements for waste
preparation and is a potential source of problems in the actual
operation of incinerators if not carefully designed [1, pp. 3-19].
Different incinerator designs (3) use different mechanisms
to obtain the temperature at which the furnace is operated, the
time during which the combustible material is subject to that
temperature, and the turbulence required to ensure that all the
combustible material is exposed to oxygen to ensure complete
combustion. Three common types of incineration systems for
treating contaminated soils are rotary kiln, circulating fluidized
bed, and infrared.
The rotary kiln is a slightly inclined cylinder that rotates on
its horizontal axis. Waste is fed into the high end of the rotary
kiln and passes through the combustion chamber by gravity. A
secondary combustion chamber (afterburner) further destroys
unburned organics in the flue gases [7, p. 40],
Figure 1
MobileAransportable Incineration Process
Treated
Emissions
Vapor
Control
1
Waste I Waste
Storage 1 ~
Waste | Wast0
Preparation m ~
0) 1 ^
Waste k
Feed 1
(2) 1
Emissions
Air Pollution
Control
(4)
Waste
Incinerator
(3)
Residue
Handling
Residue
Handling
Water
Solids
Treated
Solids
Engirt—ring Bulletin: Mobito/Transportabi• Incineration Tnatmont
F-54
3
-------
Circulating fluidized bed incinerators use high air velocity
to circulate and suspend the fuel/waste particles in a combustor
loop. Flue gas is separated from heavier particles in a solids
separation cyclone. Circulating fluidized beds do not require
an afterburner (7, p. 35].
Infrared processing systems use electrical Resistance heating
elements or indirect fuel-fired radiant U-tubes to generate
thermal radiation (1, pp. 4-5]. Waste is fed into the combustion
chamber by a conveyor belt and exposed to the radiant heat.
Exhaust gases pass through a secondary combustion chamber.
Offgases from the incinerator are treated by the APC
equipment to remove particulates and capture and neutralize
acids (4). Rotary kilns and infrared processing systems may
require both external particulate control and acid gas scrubbing
systems. Circulating fluidized beds do not require scrubbing
systems because limestone can be added directly into the
combustor loop but may require a system to remove particulates
[1, pp. 4.11 ] [2, p. 32]. APC equipment that can be used include
venturi scrubbers, wet electrostatic precipitators, baghouses,
and packed scrubbers.
Process Residuals
Three major waste streams are generated by this technology:
solids from the incinerator and APC system, water from the APC
system, and emissions from the incinerator.
Ash and treated soil/solids from the incinerator combustion
chamber may be contaminated with heavy metals. APC system
solids, such as fly ash, may contain high concentrations of
volatile metals. If these residues fail required leachate toxicity
tests, they can be treated by a process such as stabilization/
solidification and disposed of onsite or in an approved landfill
[7, p. 126],
Liquid waste from the APC system may contain caustic,
high chlorides, volatile metals, trace organic;, metal particulates,
and inorganic particulates. Treatment may require neutralization,
chemical precipitation, reverse osmosis, settling, evaporation,
filtration, or carbon adsorption before discharge [7, p. 127].
The flue gases from the incinerator are treated by APC
systems such as electrostatic precipitators or venturi scrubbers
before discharge through a stack.
Site Requirements
The site should be accessible by truck or rail and a graded/
gravel area is required for setup of the system. Concrete pads
may be required for some equipment (e.g., rotary kiln). For a
typical 5 tons per hour commercial-scale unit, 2 to 5 acres are
required for the overall system site including ancillary support
[10, p. 25].
Standard 440V three-phase electrical service is needed. A
continuous water supply must be available at the site. Auxiliary
fuel for feed BTU improvement may be required.
Contaminated soils or other waste materials are hazardous
and their handling requires that a site safety plan be developed
to provide for personnel protection and special handling
measures.
Various ancillary equipment may be required, such as
liquid/sludge transfer and feed pumps, ash collection and solids
handling equipment, personnel and maintenance facilities,
and process-generated waste treatment equipment. In addition,
a feed-materials staging area, a decontamination trailer, an ash
handling area, water treatment facilities, and a parking area
may be required [10, p. 24],
Proximity to a residential neighborhood will affect plant
noise requirements and may result in more stringent emissions
limitations on the incineration system.
Storage area and/or tanks for fuel, wastewater, and blending
of waste feed materials may be needed.
No specific onsite analytical capabilities are necessary on a
routine basis; however, depending on the site characteristics or
a specific Federal, State, or local requirement, some analytical
capability may be required.
Performance Data
More than any other technology, incineration is subject to
a series of technology-specific regulations, including the
following Federal requirements: the Clean Air Act 40 CFR 52.21
for air emissions; Toxic Substances Control Act (TSCA) 40 CFR
761,40for PCB treatment and disposal; National Environmental
Policy Act 40 CFR 6; RCRA 40 CFR 261/262/264/270 for
hazardous waste generation, treatment performance, storage,
and disposal standards; National Pollutant Discharge Elimination
System 33 U.S.C. 1251 for discharge to surface waters; and the
Noise Control Act P.L. 92-574. RCRA incineration standards
have been proposed that address metal emissions and products
of incomplete combustion. In addition, State requirements
must be met if they are more stringent than the Federal
requirements [1, p. 6-1],
All incineration operations conducted at CERCLA sites on
hazardous waste must comply with substantive and defined
Federal and State applicable or relevant and appropriate
requirements (ARARs) at the site. A substantial body of trial
burn results and other quality assured data exists to verify that
incinerator operations remove and destroy organic contaminants
from a variety of waste matrices to the parts per billion or even
the parts per trillion level, while meeting stringent stack emission
and water discharge requirements. The demonstrated treatment
systems that will be discussed in the technology status section,
therefore, can meet all the performance standards defined by
the applicable Federal and State regulations on waste treatment,
air emissions, discharge of process waters, and residue ash
disposal [1, p. A-l] [4, p. 4] [10, p. 9].
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be ARARs for CERCLA response actions. The solid
4
Engineering Bulletin: Mobile/Transportable Incineration Treatment
F-55
-------
residuals from the incinerator may not meet required treatment
levels in all cases. In cases where residues do not meet BOAT
levels, mobile incineration still may be selected, in certain
situations, for use at the site if a treatability variance establisning
alternative treatment levels is obtained. EPA has made the
treatability variance process available in order to ensure that
LDRs do not unnecessarily restrict the use of alternative and
innovative treatment technologies. Treatability variances may
be justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LOR Cuide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions," (OSWER Directive 9347.3-06FS) [13] and Superfund
LDR Cuide #6B, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions," (OSWER Directive 9347.3-
07FS) (It).
Technology Status
To date, 49 of the 95 RODs designating thermal remedies
at Superfund sites have selected onsite incineration as an
integral part of a preferred treatment alternative.
NA - Not available * Contracted, others completed 4 Superfund Site
Table 2 lists the site experience of the various mobile;
transportable incinerator systems. It includes information or,
the incinerator type/size, the site size, location, and contaminant
source or waste type treated f5J 13, p. 80] [8, p. 74],
The cost of incineration includes fixed and operational
costs. Fixed costs include site preparation, permitting, and
mobilization/demobilization. Operational costs such as labor,
utilities, and fuel are dependent on the type of waste treated
and the size of the site. Figure 2 gives an estimate of the total
cost for incinerator systems based on site size [12. pp. 1-3].
Superfund sites contaminated with only volatile organic
compounds can have even lower costs for thermal treatment
then the costs shown in Figure 2.
EPA Contact
Technology-specific questions regarding mobile/
transportable incineration may be directed to Donald A.
Oberacker, U.S. EPA Risk Reduction Engineering Laboratory, 26
West Martin Luther King Drive, Cincinnati, Ohio 45268,
telephone: FTS 684-7510 or (513) 569- 7510.
(Source: References 3, 5, 8]
Table 2.
Technology Status
Treatment
System/
Vendor
Thermal
Capacity
(MM BTU/Hr)
Experience
Site, Location
Waste Volume
(tons)
Contaminant Source or
Waste Type
Rotary Kiln
Ensco
35
Sydney Mines, Valrico, FL4
Lenz Oil NPL Site, Lemont, IL4
Naval Construction Battalion
Center (NCBC), Gulfport, MS
Union Carbide, Seadrift, TX*
Smithiville, Canada'
10,000
26,000
22,000
N/A
7,000
Waste oil
Hydrocarbon - sludge/solid/liquid
Dioxin/soil
Chemical manufacturing
PCB transformer leaks
100
Bridgeport Rental, Bridgeport, N|"
100,000
Used oil recycling
Rotary Kiln
IT
56
Comhusker Army Ammunition Plant
(CAAP), Grand Island, NE4
Louisiana Army Ammunition Plant
(LAAP), Shreveport, LA*1
Motco, Texas City, TX"
45,000
100,000
80,000
Munitions plant redwater pits
Munitions plant redwater lagoon
Styrene tar disposal pits
Rotary Kiln
8
Fairway Six Site, Aberdeen, NC
50
Pesticide dump
Vesta
12
Fort A.P. Hill, Bowling Green, VA
Nyanza/Nyacol Site, Ashland, MA4
Southern Crop Sen/ices Site
Delray Beach, FL
American Crossarm & Conduit Site
Chehalis, WA4
Rocky Boy, Havre, MT*
200
1,000
1,500
900
1,800
Army base
Dye manufacturing
Crop dusting operation
Wood treatment
Wood treatment
Engineering Bulletin: Mobile/Transportable Incineration Treatment
F-56
5
-------
Table 2
Technology Status (Continued)
Treatment
System/
Vendor
Thermal
Capacity
(MM BTU/Hr)
Experience
Site, Location
Waste Volume
(tons)
Contaminant Source or
Waste Type
Rotary Kiln
Weston
35
Lauder Salvage, Beardstown, It
Paxton Ave., Chicago, IL*
8,500
16,000
Metal scrap salvage
Waste lagoon
Rotary Kiln
AET
20
Valdez, AK
NA
Crude oil spill
Rotary Kiln
Boliden
40
Oak Creek, Wl
50,000
Dye manufacturing
Rotary Kiln
Harmon
82
Prentis Creosote & Forest Products
Prentis, MS
Bog Creek, Howell Township, N|4
9,200
22,500
Creosote/soil
Organic!
Rotary Kiln
Bell
30
Bell Lumber&Pole,
New Brighton, MN4
21,000
Wood treatment
Rotary Kiln
Kimmins
100
Lasalle, IL"
69,000
PCB capacitor manufacturing
Rotary Kiln
USEPA
10
Denney Farm, MO
6,250
Dioxin Soils
Rotary Kiln
Vertac
35
Vertac, Jacksonville, AR*4
6,500
Chemical manufacturing
Shirco Infrared
Haztech
30
Peak Oil, Tampa, FL4
Lasalle, IL*
7,000
30,000
Used oil recycling, PCBs/Lead
Transformer reconditioning
Shirco Infrared
CDC Engr.
NA
Rubicon, Ceismar, LA*
52,000
Chemical manufacturing
Shirco Infrared
OH Materials
30
Florida Steel, Indiantown, FL4
Twin City AAP, New Brighton, MN
Goosebay, Canada
18,000
2,000
4,000
Steel mill used oils
Munitions plant
PCBs
12
Gas Station Site, Cocoa, FL
1,000
Petroleum tank leak
Shirco Infrared
U.S. Woste
10
Private Site, San Bemadino, CA
5,400
Hydrocarbons
Circulating Bed
Combustor
Ogden
10
Arco Swanson River Field
Kenai, AK*
Stockton, CA*
80,000
16,000
Oil pipeline compressor oil
Underground tank oil leak
NA - Notavailable * Contracted, others completed 'Superfund She [Source: References 3, 5, 8]
6
Engineering Bulletin: Mobile/Transportable Incineration Treatment
F-57
-------
Figure 2
Effect oi Sit# Siz# on Indrwation Costs
o
~-
o
Q
o
c
E
30,000
Source: The Hazardous Waste Consultant [12, pp. 1 • 3)
Site Size-Tons
REFERENCES
1. High Temperature Thermal Treatment for CERCIA
Waste: Evaluation and Selection of On-site and Off-site
Systems. EPA/540/X-88/006, U.S. Environmental
Protection Agency Office of Solid Waste and
Emergency Response, December 1988.
2. Gupta, G., A. Sherman, and A. Gangadharan,
Hazardous Waste Incineration: The Process and the
Regulatory/Institutional Hurdles, Foster Wheeler
Enviresponse, Inc., Livingston, N|., (no date).
3. Cudahy,)., and A. Eicher. Thermal Remediation
Industry, Markets, Technology, Companies, Pollution
Engineering, 1989.
4. Stumbar, |., et al. EPA Mobile Incineration
Modifications, Testing and Operations, February 1986
to June 1989. EPA/600/2-90/042, U.S Environmental
Protection Agency, 1990.
5. Cudahy, J., and W. Troxler. Thermal Remediation
Industry Update II, Focus Environmental, Inc. Knoxville,
TN, 1990.
6. Experience in Incineration Applicable to Superfund Site
Remediation. EPA/625/9-88/008, U.S. Environmental
Protection Agency Risk Reduction Engineering
Laboratory and Center for Environmental Research
Information, 1988.
7. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
8. Johnson, N., and M. Cosmos. Thermal Treatment
Technologies for Haz Waste Remediation, Pollution
Engineering, 1989.
9. Stumbar, J., et al. Effect of Feed Characteristics on the
Performance of Environmental Protection Agency's
Mobile Incineration System. In Proceedings of the
Fifteenth Annual Research Symposium, Remedial
Action, Treatment and Disposal of Hazardous Wastes.
EPA/600/9-90/006, 1990.
10. Shirco Infrared Incineration System, Applications
Analysis Report EPA/540/A5-89/010, U.S.
Environmental Protection Agency, 1989.
11. Mobile Treatment Technologies for Superfund Wastes.
EPA 540/2-86/003(0, U.S. Environmental Protection
Agency Office of Solid Waste and Emergency Response,
1986.
12. McCoy and Associates, Inc., The Hazardous Waste
Consultant, Volume 7, Issue 3, 1989.
1 3. Superfund LDR Guide #6A: Obtaining a Soil and
Debris Treatability Variance for Remedial Actions.
OSWER Directive 9347.3-06FS, U.S. Environmental
Protection Agency, 1989.
14. Superfund LOR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
Engineering Bulletin: Mobile/Transportable Incineration Treatment
F-58
-------
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Devefopment
Cincinnati, OH 45268
Superfund EPA/540/2-90/017 September 1990
Engineering Bulletin
s>EPA Soil Washing Treatment
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants, and
contaminants as a principal element." The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
Soil washing is a water-based process for mechanically
scrubbing soils ex-situ to remove undesirable contaminants.
The process removes contaminants from soils in one of two
ways: by dissolving or suspending them in the wash solution
(which is later treated by conventional wastewater treatment
methods) or by concentrating them into a smaller volume of
soil through simple particle size separation techniques (similar
to those used in sand and gravel operations). Soil washing
systems incorporating both removal techniques offer the greatest
promise for application to soils contaminated with a wide
variety of heavy metal and organic contaminants.
The concept of reducing soil contamination through the
use of particle size separation is based on the finding that most
organic and inorganic contaminants tend to bind, either
chemically or physically, to clay and silt soil particles. The silt
and clay, in turn, are attached to sand and gravel particles by
physical processes, primarily compaction and adhesion.
Washing processes that separate the fine (small) clay and silt
particles from the coarser sand and gravel soil particles effectively
separate and concentrate the contaminants into a smaller
volume of soil that can be further treated or disposed. The
clean, larger fraction can be returned to the site for continued
use. This set of assumptions forms the basis for the volume-
reduction concept upon which most soil washing technology
applications are being developed.
At the present time, soil washing is used extensively in
Europe and has had limited use in the United States. During
1986-1989, the technology was one of the selected source
control remedies at eight Superfund sites.
The final determination of the lowest cost alternative will
be more site-specific than process equipment dominated.
Vendors should be contacted to determine the availability of a
unit for a particular site. This bulletin provides information on
the technology applicability, the types of residuals resulting
from the use of the technology, the latest performance data,
site requirements, the status of the technology, and where to
go for further information.
Technology Applicability
Soil washing can be used either as a stand-alone technology
or in combination with other treatment technologies. In some
cases, the process can deliver the performance needed to
reduce contaminant concentrations to acceptable levels and,
thus, serve as a stand-alone technology. In other cases, soil
washing is most successful when combined with other
technologies. It can be cost-effective as a pre-processing step
in reducing the quantity of material to be processed by another
technology such as incineration; it also can be used effectively
to transform the soil feedstock into a more homogeneous
condition to augment operations in the subsequent treatment
system. In general, soil washing is effective on coarse sand and
gravel contaminated with a wide range of organic, inorganic,
and reactive contaminants. Soils containing a large amount of
clay and silt typically do not respond well to soil washing,
especially if it is applied as a stand-alone technology.
A wide variety of chemical contaminants can be removed
from soils through soil washing applications. Removal efficiencies
depend on the type of contaminant as well as the type of soil.
Volatile organic contaminants often are easily removed from
soil by washing; experience shows that volatiles can be removed
with 90-99 percent efficiency or more. Semivofatile organics
F-59
-------
may be removed to a lesser extent (40-90 percent) by selection
of the proper surfactant. Metals and pesticides, which are more
insoluble in water, often require acids or chelating agents for
successful soil washing. The process can be applicable for the
treatment of soils contaminated with specific listed Resource
Conservation and Recovey Act (RCRA) wastes and other
hazardous wastes including wood-preserving chemicals
(pentachlorophenol, creosote), organic solvents, electroplating
residues (cyanides, heavy metals), paint sludges (heavy metals),
organic chemicals production residues, pesticidesand pesticides
production residues, and petroleum/oil residues (1, p. 659][2,
P- 1S][4](7 through 13]*.
The effectiveness of soil washing for general contaminant
groups and soil types is shown in Table 1 [1, p. 659][3, p.
13](15, p.1], Examples of constituents within contaminant
groups are provided in Reference 3, "Technology Screening
Guide For Treatment of CERCLA Soils and Sludges." This table
is based on currently available information or professional
judgment where definitive information is currently inadequate
or unavailable. The proven effectiveness of the technology for
a particular site or waste does not ensure that it wilt be effective
at all sites or that the treatment efficiency achieved will be
acceptable at other sites. For the ratings used in this table, good
to excellent applicability means the probability is high that soil
Table 1
Applicability o< Soil Washing on Gerwcd Contaminant
Groups for Various Soils
Contaminant Croups
Matrix
Sandy/ Sltty/Clay
Cravetty Soils Soils
[ Orgonk
Halogenated volatiles
Halogenated semivolatiles
Nonhatogenated volatJIes
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
U
~
¦
~
T
~
~
T
~
~
~
~
~
T
T
T
~
| Inorganic
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
¦
¦
T
T
~
~
T
~
~
~
St
s
j!
Oxidizers
Reducers
~
~
~
~
¦ Good to Excellent Applicability High probability 'Jut technology will be
successful
~ Moderate to Marginal Applicability: Exercise care in choosing technology
'J Noi Applicable. Expert opinion that technology will not work
washing will be effective for that particular contaminant and
matrix. Moderate to marginal applicability indicates situations
where care needs to be exercised in choosing the soil washing
technology. When not applicable is shown, the technology will
probably notworkfor that partkularcombmationofcontaminant
group and matrix. Other sources of general observations and
average removal efficiencies for different treatability groups are
the Superfund LDR Guide #6A, "Obtaining a Soil and Debris
Treatability Variance for Remedial Actions" (OSWER Directive
9347.3-06FS), [16] and Superfund LDR Guide #6B, "Obtaining
a Soil and Debris Treatability Variance for Removal Actions"
(OSWER Directive 9347.3-07FS) [17).
Information on cleanup objectives as well as the physical
and chemical characteristics of the site soil and its contaminants
is necessary to determine the potential performance of this
technology and the requirements for waste preparation and
pretreatment. Treatability tests are also required at the laboratory
screening, bench-scale and/or pilot-scale level(s) to determine
Table 2
Waste Soti Characterization Parameters
Parameter
Key Physical
Partide size (Attribution:
>2 mm
0.25-2 mm
0.063-0.25 mm
<0.063 mm
Other Physical
Purpose and Comment
Oversize pretreatment requirement*
Effective soil washing
Limited soil washing
Clay and silt fraction—difficult sofl
washing
Type, physical form,
handlfng properties
Moisture content
Key Chemical
Organic*
Concentration
Volatility
Partition
coefficient
Metals
' >eferecce number, page number)
Humk add
Other Chemical
pH, buffering
capacity
Affects pretreatment and transfer
requirements
Affects pretreatment and transfer
requirements
Determine contaminants and assess
separation and washing efficiency,
hydrophobic interaction, washing
fluid compatibility, changes in
washing fluid with changes in
contaminants. May require
preblending for consistent feed. Use
the jar test protocol to determine
contaminant partitioning.
Concentration and species of
constituents (specific jar test) will
determine washing fluid compatibility,
mobility of metals, posttreatment.
Organic content will affect adsorption
characteristics of contaminants on soil.
Important in manne/wetland sites. j
May affect pretreatment
requirements, compatibility with
eauipmem materials of construction,
wash fluid compatibility.
2
F-60
Engineering Bulletin: Soil Washing Treatment
-------
Figure 1
Soil WotMng Applicable Particle Size Sang*
Sand
Average ¦ Large
Gravel
Average ¦ Large
Stone
Average
Difficult
Soil Washing
(Regime III)
Soil Wash with
Specific Washing Fluid
(Regime II)
Economic Wash
with Simple Particle"
Size Separation
(Regime I)
0.001 0.002
0.006 0.01 0.02
0.063 0.1 0.2 0.6 1 2
Diameter of Particle In Millimeters
60 100
the feasibility of the specific soil washing process being
considered and to understand waste preparation and
pretreatment steps needed at a particular site. If bench-test
results are promising, pilot-scale demonstrations should normally
be conducted before final commitment to full-scale
implementation. Treatability study procedures are explained
in the EPA's forthcoming document entitled "Superfund
Treatability Study Protocol: Bench-Scale Level of Soils Washing
for Contaminated Soils" [14].
Table 2 contains physical and chemical soil characterization
parameters that must be established before a treatability test is
conducted on a specific soil washing process. The parameters
are defined as either "key" or "other" and should be evaluated
on a site-specific basis. Key parameters represent soil
characteristics that have a direct impact on the soil washing
process. Other parameters should also be determined, but they
can be adjusted prior to the soil washing step based on specific
process requirements. The table contains comments relating to
the purpose of the specific parameter to be characterized and
its impact on the process [6, p. 90][14, p. 35].
Particle size distribution is the key physical parameter for
determining the feasibility of using a soil washing process.
Although partide.size distribution should not become the sole
reason for choosing or eliminating soil washing as a candidate
technology for remediation, it can provide an initial means of
screening for the potential use of soil washing. Figure 1
presents a simplistic particle size distribution range of curves
that illustrate a general screening definition for soil washing
technology.
In its simplest application, soil washing is a particle size
separation process that can be used to segregate the fine
fractions from the coarse fractions. In Regime I of Figure 1,
where coarse soils are found, the matrix is very amenable to soil
washing using simple particle size separation.
Most contaminated soils will have a distribution that falls
within Regime II of Figure 1. The types of contaminants found
in the matrix will govern the composition of the washing fluid
and the overall efficiency of the soil washing process.
In Regime III of Figure 1, soils consisting largely of finer
sand, silt, and clay fractions, and those with high humic
content, tend to contain strongly adsorbed organics that
generally do not respond favorably to systems that work by only
dissolving or suspending contaminants in the wash solution.
However, they may respond to soil washing systems that also
incorporate a particle size separation step whereby contaminants
can be concentrated into a smaller volume.
Limitations
Contaminants in soils containing a high percentage of silt-
and clay-sized particles typically are strongly adsorbed and
difficult to remove. In such cases, soil washing generally should
not be considered as a stand-alone technology.
Hydrophobic contaminants generally require surfactants
or organic solvents for their removal from soil. Complex
mixtures of contaminants in the soil (such as a mixture of
metals, nonvolatile organics, and semivolatile organics) and
Engineering Bulletin: Soil Washing Treatment
F-61
3
-------
Hgui« 2
Aqueous Soli Washing Process
Volatiles
Contaminated
Soil
Makeup water
Extracting Agent(s)
(Surfactants, etc.)
Sofl
Preparation
(1)
Prepared
Soil
Treated
Emission
Air Emissions
Control
Recycled water
Chemicals
Soli Washing
Process
(2)_
-Washing
-Ainsing
-Sue Separation
Blowdown
Water
Wastewater
Treatment
(3)
Treated
Water
Sludges/
Contaminated Fines
Clean Soil
Oversized Rejects
frequent changes in the contaminant composition in the soil
matrix make it difficult to formulate a single suitable washing
fluid that will consistently and reliably remove all of the different
types of contaminants from the soil particles. Sequential
washing steps may be needed. Frequent changes In the wash
formulation and/or the soil/wash fluid ratio may be required [3,
p. 76][14, p. 7],
While wash water additives such as surfactants and chelants
may enhance some contaminant removal efficiencies in the soil
washing portion of the process, they also tend to interfere with
the downstream wastewater treatment segments of the process.
The presence of these additives in the washed soil and in the
wastewater treatment sludge may cause some difficulty in their
disposal [14, p. 7][15, p. 1 ]. Costs associated with handling the
additives and managing them as part of the residuals/wastewater
streams must be carefully weighed against the incremental
improvements in soil washing performance that they may
provide.
Technology Description
Figure 2 is a general schematic of the soil washing process
[1,p. 657][3, p. 72][15, p. 1].
Soil preparation (1) includes the excavation and/or moving
of contaminated soil to the process where it is normally
screened to remove debris and large objects. Depending upon
the technology and whether the process is semibatch or
continuous, the soil may be made pumpable by the addition of
water.
A number of unit processes occur in the soil washing
process (2). Soil is mixed with washwater and possibly extraction
agent(s) to remove contaminants from soil and transfer them
to the extraction fluid. The soil and washwater are then
separated, and the soil is rinsed with clean water. Clean soil is
then removed from the process as product. Suspended soil
particles are recovered directly from the spent washwater, as
sludge, by gravity means, or they may be removed by flocculation
with a selected potymer or chemical, and then separated by
gravity. These solids will most likely be a smaller quantity but
carry higher levels of contamination than the original soil and,
therefore, should be targeted for either further treatment or
secure disposal. Residual solidsfrom recycle water cleanup may
require post-treatment to ensure safe disposal or release. Water
used in the soil washing process is treated by conventional
wastewater treatment processes to enable it to be recycled for
further use.
Engineering Bulletin: Soil Washing Treatment
F-62
-------
Wastewater treatment (3) processes the blowdown or
discharge water to meet regulatory requirements for heavy
metal content, organics, total suspended solids, and other
parameters. Whenever possible, treated water should be
recycled to the soil washing process. Residual solids, such as
spent ion exchange resin and carbon, and sludges from biologi-
cal treatment may require post-treatment to ensure safe disposal
or release.
Vapor treatment may be needed to control air emissions
from excavation, feed preparation, and extraction; these
emissions are collected and treated, normally by carbon
adsorption or incineration, before being released to the
atmosphere.
Process Residuals
There are four main waste streams generated during soil
washing: contaminated solids from the soil washing unit,
wastewater, wastewater treatment sludges and residuals, and
air emissions.
Contaminated clay fines and sludges resulting from the
process may require further treatment using acceptable
treatment technologies (such as incineration, low temperature
desorption, solidification and stabilization, biological treatment,
and chemical treatment) in order to permit disposal in an
environmentally safe manner [16]. Blowdown water may need
treatment to meet appropriate discharge standards prior to
release to a local, publicly owned wastewater treatment works
or receiving stream. To the maximum extent practical, this
water should be recovered and reused in the washing process.
The wastewater treatment process sludges and residual solids,
such as spent carbon and spent ion exchange resin, must be
appropriately treated before disposal. Any air emissions from
the waste preparation area or the washing unit should be
collected and treated, as appropriate to meet applicable
regulatory standards.
Site Requirements
Access roads are required for transport of vehicles to and
from the site. Typically, mobile soil washing process systems
are located onsite and may occupy up to 4 acres for a 20 ton/
hour unit; the exact area will depend on the vendor system
selected, the amount of soil storage space, and/or the number
of tanks or ponds needed for washwater preparation and
wastewater treatment.
Typical utilities required are water, electricity, steam, and
compressed air. An estimate of the net (consumed) quantity of
total water required for soil washing, assuming water cleanup
and recirculation, is 130,000-800,000 gallons per 1,000 cubic
yards (2,500,000 lbs.) of soil (approximately 0.05-0.3 gallons
per pound).
Because contaminated soils are usually considered
their hanc"in9 requires that a site safety plan be
hinHi° t0 Prov'de 'or personnel protection and special
ing measures during soil washing operations.
Moisture content of soil must be controlled for consistent
handling and treatment; this can be accomplished, in part, by
covering excavation, storage, and treatment areas.
Fire hazard and explosion considerations should be minimal,
since the soil washing fluid is predominantly water. Generally,
soil washing does not require storing explosive, highly reactive
materials.
Climatic conditions such as annual or seasonal precipitation
cause surface runoff and water infiltration. Berms, dikes, or
other runoff control methods may be required. Cold weather
freezing must also be considered for aqueous systems and soil
excavation operations.
Proximity to a residential neighborhood will affect plant
noise requirements and emissions permitted in order to minimize
their impact on the population and meet existing rules and
regulations.
tf all or part of the processed soil is to be redeposited at the
site, storage areas must be provided until analytical data are
obtained that verifies that treatment standards have been
achieved. Onsite analytical capability could expedite the
storage/final disposition process. However, soil washing might
be applied to many different contaminant groups. Therefore,
the analytes that would have to be determined are site specific,
and the analytical equipment that must be available will vary
from site to site.
Performance Data
The performances of soil washing processes currently
shown to be effective in specific applications are listed in Table
3 [1 ][2][4][7 through 13], Also listed are the range of particle
size treated, contaminants successfully extracted, byproduct
wastes generated, extraction agents used, major extraction
equipment for each system, and general process comments.
The data presented for specific contaminant removal
effectiveness were obtained from publications developed by
the respective soil washing system vendors. The quality of this
information has not been determined.
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be applicable or relevant and appropriate
requirements (ARARs) for CERCLA response actions. The soil
washing technology can produce a treated waste that meets
treatment levels set by BOAT, but may not reach these treatment
levels in all cases. The ability to meet required treatment levels
is dependent upon the specific waste constituents and the
waste matrix. In cases where soil washing does not meet these
levels, it still may, in certain situations, be selected for use at the
site if a treatability variance establishing alternative treatment
levels is obtained. EPA has made the treatability variance
process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be justified
for handling complex soil and debris matrices. The following
guides describe when and how to seek a treatability variance for
soil and debris: Superfund LDR Guide #6A, "Obtaining a-Soil
^Vn««rfng Bulletin: Soil Washing Treatment
F-63
-------
and Debris Treatability Variance for Remedial Actions" (OSWER
Directive 9347.3-06FS) [16], and Superfund IDR Guide #6B,
"Obtaining a Soil and Debris Treatability Variance for Removal
Actions" (OSWER Directive 9347.3-07FS) [1 7). Another
approach could be to use other treatment techniques in series
with soil washing to obtain desired treatment levels.
Technology Status
During 1986-1989, soil washing technology was selected
as one of the source control remedies at eight Supeffund sites:
Vineland Chemical, New Jersey; Koppers Oroville Plant,
California; Cape Fear Wood Preserving, North Carolina; Ewan
Property, New jersey; Tinlcam Garage, New Hampshire; United
Scrap, Ohio; Koppers/Texarkana, Texas; and South Cavalcade,
Texas [18].
A large number of vendors provide a soil washing
technology. Table 3 shows the current status of the technology
for 14 vendors. The front portion of the table indicates the scale
of equipment available from the vendor and gives some
indication of the vendor's experience by showing the year it
began operation.
Processes evaluated or used for site cleanups by the EPA are
Identified separately by asterisks in the Proprietary Vendor
Process/EPA column in Table 3.
The following soil washing processes that are under
development have not been evaluated by the EPA or included
in Table 3. Environmental Group, Inc. of Webster, Texas, has
a process that reportedly removes metals and oil from soil.
Process efficiency is stated as greater than 99 percent for lead
removal from soils cleaned in Concord, California; greater than
99 percent for copper, lead, and zinc at a site in Racine,
Wisconsin; and 94 percent for PCB removal on a Morrisorv
Knudsen Company project. The process does not appear to
separate soil into different size fractions. Detailed information
on the process is not available. Consolidated Sludge Company
of Cleveland, Ohio, has a soil washing system planned that
incorporates their Mega-sludge Press at the end of the process
for dewatering solids. The system has not yet been built
Vendor-supplied treatment costs of the processes reviewed
ranged from $50 to $205 per ton of feed soil. The upper end
of the cost range includes costs for soil residue disposal.
EPA Contact
Technology-specific questions regarding soil washing may
be directed to:
Michael Gruenfeld
U.S. EPA, Releases Control Branch
Risk Reduction Engineering Laboratory
Woodbridge Avenue, Building 10
Edison, New jersey 08837
Telephone FTS 340-6625 or (201) 321-6625.
6
F-64
Engln^+rlng Bulletin: Soil Washing Treatment
-------
Table 3. Summary of Performance Data and Technology Status - Part I
Proprietary Vendor
Process/EPA
Highest Stale
of Operation
Year Operation
Began
tange of Particle
Size Treated
Contamlnana
extracted From Soil
extraction Agent(s)
U S Processes
(1) SOIL CLEANING COMPANY
OF AMERICA [5][1 5, p. 2]
Full scale
15 tons/hr
1988
8ulk soil
Oil and grease
Hot water with
surfactant
(2)- BIOTROL SOIL TREATMENT
SYSTEM (8STS)
[4, p. 6][12]
Pilot scale
500 Ibs/hr
Fall, 1987
Above clay size and
below 0.5 in. Some
cleaning of fine par-
ticles in bio-reactor
Organics - pentachloro-
phenol, creosote,
naphthalene, pyrene,
fluorene, etc.
Proprietary
conditioning
chemicals
(3) EPA'S MOBILE COUNTER-
CURRENT EXTRACTOR
[9][5. P- 5]
Pilot scale
4.1 tons/hr
Modified with
drum washer
and shakedown-
1982
Full Scale-1986
2-25 mm in drum
washer
<2 mm in four-stage
extractor
Soluble organics
(phenol, etc.)
Heavy metals
(Pb, etc.)
Various solvents,
additives, surfactants,
redox acids and bases
Chelating agent
(EDTA)
(4)' EPA'S FIRST GENERATION
PILOT DRUM SCREEN
WASHER [10, p. 8]
Pilot scale
1988
Oversize (>2 mm)
removed prior to
treatment
Petroleum
hydrocarbons
Biodegradable
surfactant
(aqueous slurry)
(5)* MTA REMEDIAL
RESOURCES
[11 HI 5, p. 2]
Bench scale
N/A
Oversize removed
prior to treatment
Organics (oil)
Heavy metals (inorganics)
removed using counter-
current decantation
with leaching
Surfactants and
alkaline chemicals
added upstream of
froth flotation cells.
Acid for leaching.
Non-U.S. Processes 1
(6) ECOTECHNIEK 8V
[2, p. 17]
Commercial
100 ton/hrmax
1982
Sandy soil
Crude oil
None. Water-sand
slurry heated to 90°C
max. with steam.
(7) BODEMSANERING
NEDERLAND
BV (BSN)
[2, p. 171
Commercial
20 ton/hr
1982
>100 mm removed
No more than 20%
<63 urn
Sludge <30 jim not
cleaned
Oil from sandy soil
None. Uses high
pressure water jet
for soils washing.
(8) HARBAUER
[2, p. 20][7, p. 5)
Commercial
15-20 tons/hr
Lab -1985
Commercial-1986
With fines
removal -1987
15 |im - 5mm Pre-
treatment coarse
screens, electromagnet
blade washer
Mostly organics
Limited heavy metals
removal experience
Hydraulkally
produced oscillation/
vibration
Surfactants
Acid/base
(9) HWZ
BODEMSANERING BV
[2. p. 171
Commercial
20-25 tons/hr
1984
<10 mm and >63 jim
Cyanide, Chlorinated
HC, some heavy
metals, PNA
Sodium Hydroxide
to adjust pH
Surfactants
(10) WE1IMAN
MIUEUTECHNIEK BV
[2,p.171[7, p. 6]
Pilot scale
10-15 tons/hr
1985
<10 mm and no more
than 30% <63 |im
Cyanide, heavy metals,
mineral oil (water
immiscible hydro-
carbons)
Proprietary extraction
agents. Hydrogen
Peroxide (H,0,)
added to react
with extracted CN
to form CO, and NH,
01) HE1DEMI| FROTH
flotation
[7, p. 8)
Full scale
N/A
<4 mm and no more
than 20% <50 Jim
Cyanide, heavy metals,
chlorinated HCs, oil,
toluene, benzene,
pesticides, etc
Proprietary Surfact-
ants and other pro-
prietary chemicals
",>T0CeU ev,lua,ed or used for Site cleanup by the EPA. N/A - Not available.
*n&n—ring Bulletin: Soil Washing Treatment
F-65
7
-------
Tabic 3. Summary of Performance Data and Technology Status • Part I (continued)
Proprietary Vendor 1 Highest Scab
Process/EPA of Operation
Year Operation
Began
Mange ofPartkie
She Treated
Contaminana
Extracted from Soft
Extrocthn Agent(t)
Non U S Processes (continued)
(12) EWH AL5EN -
BREITENBURG
Dekomat System [2, p. 20]
I
Pilot scale i
8-1 Ocu. m/hr |
N/A
<80 mm
Clays treated offsite
Oil from sandy soil
Proprietary
(13) TBSG
INOUSTRlEVtmniJNCEN
Oil Crep 1 System [7, p. 7]
Pilot scale
1986
Sand <50 mm
Particles <100 [im
treated offsite
Hydrocarbon and oil
i
Proprietary combina-
tion of surfactants,
solvents, and aromatic
hydrocarbons
(14) KLOCKNER
UMWELTECHNIK
fet-Modtfied BSN [2, p. 20]
, Pilot scale
N/A
No more than 20%
<63 pm
Aliphatic and aromatics
with densities < water,
volatile organic*, some
, other hydrocarbons
None. Soil blasted
with a water jet (at
5,075 psi)
Table 3. Summary of Performance Data and Technology Status - Part II
Proprietory Vendor
Byproduct Wastes
Extraction
Efficiency of
Additional
Process/EPA
Generated
Equipment I
Contaminant Removal
Process Comments
U.S. Processes
(1) SOIL CLEANING
OF AMERICA
Wet oil
Screw conveyors
Contort Removal Residual
inont Efficiency % ppm
Oil and 50-83 250-600
grease
Three screw conveyors operated
in series, hot water wtth surfactant
injected into each stage. Final soil
rinse on a fourth screw conveyor.
(2) * BIOTROL SOIL
treatment SYSTEM
(BSTS)
Oil and grease
Sludge from bio-
ogical treatment
Agitated
conditioning tank
Froth flotation
Slurry bioreactor
For the case presented:
90-95% for Pentachlorophenol;
to residuals <115 ppm.
85-95% for most other organic*;
to residuals <1 ppm.
Dewatered clays and organics to be
treated offsite by incineration,
solidification, etc. Washed soil was
approx. 78% of feed. Therefore,
significant volume reduction was
achieved.
(3) EPA'i MOBILE 1
COUNTER-CURRENT |
EXTRACTOR ,
1
Clay fraction
Recovered organic*
(extractor skimmings)
Spent |
carbon (oversize)
Drum screen
Water knife '
Soil scrubber
4- Stage
Counter-current
chemical extractor
Con torn- Removal Residual*
inant Efficiency % ppm
Phenol 90 from in. soil 1
80 from or. soil 96
AS20, 50-80 0.5-1.3.
Clay fraction treated elsewhere.
(4)- EPA's FIRST
GENERATION PILOT
DRUM SCREEN
WASHER (PDSW)
Sludge
Flocculated fines
1
Drum screen
washer
Sort Size Rest*
Contam- fraction Removal dual
I inant mm Effk.% ppm
Oil and 0.25-2 99 <5
grease <0.25 90 2400
Process removal efficiency
increases if extracting medium is
j heated. Install wet classifiers
beneath the PDSW to remove
waste water from treated sol.
Auger classifiers are required to
to discharge particles effectively.
(5)" MTA REMEDIAL
RESOURCES (MTARRt)
Froth Flotation
Fkxzculation froth
Reagent blend
tank
Flotation cells
Counter-current
decantation
Contam- Removal Residual
inant Efficiency % ppm
Volatile
organics 98-99+- < 50
Semi volatile
organics 98-994- < 250
Most fuel
products 98-99+- < 2200
Flotation cefls finked by underflow
weir gates. Induced air blown
down a center shaft in each mii
Continuous flcp operation, froth
contains 5-10 wt% of feed soil.
'Process evaluated or used for site cleanup by the EPA. N/A = Not available.
8
F-66
Engineering Bulletin: Soil Washing Treatment
-------
Tabic 3. Summary of Performance Data and Technology Status • Part II (continued)
[ Proprietary Vendor
Process/CPA
Noil U S Prixi-SM's
(6) ECOTECHNIEIC BV
Byproduct Wastes 1
Extraction
Efficiency of 1
Additional 1
Generated |
equipment
Contaminant Removal \
Process Comments |
Wet oil
Jacketed, agitated
tank
About 90%
20,000 ppfTi residual oil
Effectiveness of process depen-
dent on soil particle size and type
of oil to be separated.
(7)
BODEMSANERING
NEDERLAND BV (BSN)
Oil/organics
recovered from
wastewater fines
Water jet
Selected results:
Contam-
Removal
Residual
inant
Efficiency %
ppm
AromatlcJ
>81
>45
PNAs
95
15
Crude oil
97
2300
Contam-
Removal
Residual
inant
Efficiency %
ppm
Organk-CI
NO
Tot. organks 96
159-201
Tot phenol
86-94
7-22.5
PAH
86-90
91.4-97.5
PCB
84-88
0.5-1.3
Contam-
Removal
Residual
inant
Efficiency96
ppm
CN
95
5-15
PNAs
98
15-20
Chlorin-HC
98
<1
Heavy metals 75
75-125
No comments
(8) HARBAUER
OF AMERICA
Carbon which may
contain contami-
nants
Conditioning tank
Low frequency
vibration unit
Vibrating screw conveyor used.
Cleaned soil separated from
extractant liquor in stages; coarse
soil by sedimentation, medium
fraction in hydrodone, fines
(15-20 (im) by vacuum filter press.
(9) HWZ
BODEMSANERING BV
Fines
Sludge containing
iron cyanide
Large particles —
carbon, wood, grass
Scrubber
(for caustic
addition)
Upflow classifier
When the fines fraction (<63 |im) is
greater than 20%, the process is not
economical. HWZ has had some
problems in extracting PNAs and
oily material.
(10) HE1|MAN
MIUEUTECHNIEK BV
Flocculated fines
sludge
Oil (if any) and silt
Mix tank
followed by soils
fraction equip-
ment — hydro-
dories, sieves,
tilt plate separators
Contam- Removal
inant efficiency %
Cyanide 93-99
Heavy metal
cations approx. 70
Residual
ppm
<15
<200
Process works best on sandy softs
with a minimum of humus-like
compounds. Because no sand or
charcoal filters are employed by
Heijmans, the system does not
remove contaminants such as
chlorinated hydrocarbons.
(11) HEIDEMII FROTH
FLOTATION
Contaminated float
Conditioning tank
Froth flotation
tanks
Contam- Removal Residua!
inant Efficiency 96 ppm
Cyanide >95 5
Heavy metals >90 avg >150
Chlorln-HC >99 0.5
Oil >99 20
Process has broad application for
removing hazardous materials from
soil. Most experience has been on
a laboratory scale.
(12) EWH ALSEN -
BREITENBURG
Dekomat System
Recovered oil
Flocculated fines
(sludge)
High-shear
stirred tank
About 95% oil removed
Cleaned soil from high shear
stirred tank is separated into
fractions using vibrating screens,
screw classifies, hydrodones, and
sedimentation 'anks.
(13) TBSG
INDUSTRIEVEmET-
UNGEN
Oil Crep I System
Oil phase contain-
ing Oil Crep I
Screw mixer
followed by a
rotating separation
drum for oil
recovery
>95% Removal of hydrocarbons
has been achieved. Results are
influenced by other contaminants
present
Oil Crep system was used success-
fully in Flansburg, FRG (in 1986)
to remove PCBs, PAHs, and other
hydrocarbons.
(14) KLOCKNER
UMWELTECHNIK
High Pressure Water
let-Modified BSN
Oil/organics
recovered from
wastewater fines
Sludge
Water jet -
circular nozzle
arrangement
Selected results:
Contam-
Removal
Residual
inant
Efficiency It
ppm
HC
96.3
82.05
Chlorin-HC
>75.
<0.01
Aromatks
99.8
<0.02
PAHs
95.4
15.48
Phenol
>99.8
<0.01
No comments
Process evaluated or used for site cleanup by the EPA. N/A ¦ Not available.
£nQin—ring Bullmftt: Soil Washing Tnafmmnt
F-67
9
-------
REFERENCES
1. Assink, |.W. Extractive Methods for Soil
Decontamination; a General Survey and Review of
Operational Treatment Installations. In: Proceedings
from the first International TNO Conference on
Contaminated Soil, Ultrecht, Netherlands, 1985.
2. Raghavan, R., D.H. Diett, and E. Coles. Cleaning
Excavated Soil Using Extraction Agents: A State-of-the-
Art Review. EPA 600/2-89/034, U.S. Environmental
Protection Agency, 1988.
3. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA 540/2-88/004, U.S.
Environmental Protection Agency, 1988.
4. M.K. Stinson, et al. Workshop on the Extractive
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New jersey, 1988.
5. Smarkel, K.L Technology Demonstration Report - Soil
Washing of Low Volatility Petroleum Hydrocarbons.
California Department of Health Services, 1988.
6. Guide for Conducting Treatability Studies Under
CERCLA, Interim Final. EPA/S40/2-89/058, U.S.
Environmental Protection Agency, 1989.
7. Nunno, T.)„ |.A. Hyman, and T. Pheiffer. Development
of Site Remediation Technologies in European
Countries. Presented at Workshop on the Extractive
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New jersey, 1988.
8. Nunno, T.|., and )A Hyman. Assessment of
International Technologies for Superfund Applications.
EPA/540/2-88/003, U.S. Environmental Protection
Agency, 1988.
9. Scholz, R., and |. Milanowski. Mobile System for
Extracting Spilled Hazardous Materials from Excavated
Soils, Project Summary. EPA/600/S2-83/100, U.S.
Environmental Protection Agency, 1983.
10. Nash, |. Field Application of Pilot Scale Sorts Washing
System. Presented at Workshop on the Extracting
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New jersey, 1988.
11. Trost, P.B., and R.S. Rickard. On-site Soil Washing—A
Low Cost Alternative. Presented at AD PA. Los Angeles,
California, 1987.
12. Pflug, A.D. Abstract of Treatment Technologies, Biotrol,
Inc., Chaska, Minnesota, (no date).
13. Biotrol Technical Bulletin, No. 87-1 A, Presented at
Workshop on the Extraction Treatment of Excavated
Soil, U.S. Environmental Protection Agency, Edison,
New jersey, 1988.
14. Superfund Treatability Study Protocol: Bench-Scale
Level of Soils Washing for Contaminated Soils, Interim
Report U.S. Environmental Protection Agency, 1989.
15. Innovative Technology: Soil Washing. OSWER Directive
9200.5-250FS, U.S. Environmental Protection Agency,
1989.
16. Superfund LDR Guide #6A: Obtaining a Soil and Debris
Treatability Variance for Remedial Actions. OSWER
Directive 9347.3-06FS, U.S. Environmental Protection
Agency, 1989.
17. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
18. ROD Annual Report FY1989. EPA/540/8-90/006, U.S.
Environmental Protection Agency, 1990.
OTHER REFERENCES
Overview—Soils Washing Technologies For
Comprehensive Environmental Response,
Compensation, and Liability Act Resource Conservation
and Recovery Act Leaking Underground Storage Tanks,
Site Remediation, U.S. Environmental Protection
Agency, 1989.
10
F-68
Engineering Bulletin: Soil Washing Treatment
-------
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Table 1
RCRA Code* for Wattes Treated
by Solvent Extraction
Wood Treating Wastes
K001
Water Treatment Sludges
K044
Dissolved Air Flotation (DAf) Float
KQ48
Slop Oil Emulsion Solids
K049
Heat Exchanger Bundles Cleaning Sludge
K050
American Petroleum Institute (API)
Separator Sludge
K051
Tank Bottoms (leaded)
K052
Ammonia Still Sludge
K060
Pharmaceutical Sludge
K084
Decanter Tar Sludge
K069
Distillation Residues
K101
and matrix. The ratings of potential effectiveness or no
expected effectiveness are both based upon expert judg-
ment. Where potential effectiveness is indicated, the tech-
nology is believed capable of successfully treating the
contaminated group in a particular matrix. When the
technology is not applicable or will probably not work for a
particular combination of contaminant group and matrix, a
no expected effectiveness rating is given.
Limitations
Organically bound metals can co-extract with the tar-
get organic pollutants and become a constituent of the
concentrated organic waste stream. This is an unfavorable
occurrence because the presence of metals can restrict both
disposal and recycle options.
The presence of detergents and emulsifiers can unfa-
vorably influence extraction performance and material
throughput. Water soluble detergents found in some raw
wastes (particularly municipal) will dissolve and retain or-
ganic pollutants in competition with the extraction solvent.
This can impede a system's ability to achieve low concentra-
tion treatment levels. Detergents and emulsifiers can pro-
mote the evolution of foam, which hinders separation and
settling characteristics and generally decreases materials
throughput. Although methods exist to combat these
problems, they will add to the process cost.
When treated solids leave the extraction subsystem,
traces of extraction solvent are present [6, p. 125]. The
typical extraction solvents used in currently available sys-
tems either volatilize quickly from the treated solids or
biodegrade easily. Ambient air monitoring can be em-
ployed to determine if the volatilizing solvents present a
problem.
The types of organic pollutants that can be extracted
successfully depend, in part, on the nature of the extraction
solvent. Treatability tests should be. conducted to deter-
mine which solvent or combination of solvents is best suited
2
Table 2
Effectiveness of Solvent Extraction on
General Contaminant Groups for
Soil, Sludges, and Sediments
Efftcthrtncss
Contaminant Croups
Soil
Sludge Sediments
Halogenated volatiles
r
r
T
Halogenated semivolatiles
¦
¦
¦
Nonhalogenated volatiles
¦
¦
T
$
Nonhalogenated semivolatiles
¦
¦
¦
1
PCBs
¦
¦
¦
o
Pesticides
¦
T
T
Dioxins/Furans
~
T
T
Organic cyanides
~
T
T
Orqanic corrosives
~
T
T
Volatile metals
a
a
~
Nonvolatile metals
a
~
3
1!
Asbestos
a
~
3
&
$
Radioactive materials
a
~
3
Inorganic corrosives
~
~
0
inorganic cyanides
a
u
~
I
Oxidizers
~
a
~
8
V
Reducers
~
~
~
¦ Demonstrated Effectiveness: Successful treatability test at
some scale completed
~ Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Expert opinion that technology will not
work
to the site-specific matrix and contaminants. In general,
solvent extraction is least effective on very high molecular
weight organics and very hydrophilic (having an affinity for
water) substances.
Some commercially available extraction systems use
solvents that are flammable, toxic, or both [7, p.2].
However, there are standard procedures used by chemical
companies, service stations, etc. that can be used to greatly
reduce the potential for accidents. The National Fire
Protection Association (NFPA) Solvent Extraction Plants
Standard (No. 36) has specific guidelines for the use of
flammable solvents [8, p. 4-60].
Technology Description
Some type of pretreatment is necessary. This may
involve physical processing and, if needed, chemical condi-
tioning after the contaminated medium has been removed
from its original location. Soils and sediments can be
removed by excavation or dredging. Liquids and pumpable
sludges can be removed and transported using diaphragm
or positive displacement pumps.
Engineering Bulletin: Solvent Extraction
F-70
-------
Any combination of material classifiers, shredders, and
crushers can be used to reduce the size of particles being
fed into a solvent extraction process. Size reduction of
particles increases the exposed surface area, thereby in-
creasing extraction efficiency. Caution must be applied to
ensure that an overabundance of fines does not lead to
problems with phase separation between the solvent and
treated solids. The optimum particle size varies with the
type of extraction equipment used.
Moisture content may affect the performance of a
solvent extraction process depending on the specific sys-
tem design. If the system is designed to treat pumpabie
sludges or slurries, it may be necessary to add water to
solids or sediments to form a pumpabie slurry. Other
systems may require reduction of the moisture content in
order to treat contaminated media effectively.
Chemical conditioning may be necessary for some
wastes or solvent extraction systems. For example, pH
adjustment may be necessary for some systems to ensure
solvent stability or to protect process equipment from
corrosion.
Depending on the nature of the solvent used, solvent
extraction processes may be divided into three general
types. These include processes using the following types of
solvents: standard, liquefied gas (LG), and critical solution
temperature (CST) solvents. Standard solvent processes
use alkanes, alcohols, ketones, or similar liquid solvents at
or near ambient temperature and pressure. These types
solvents are used to treat contaminated solids in much ;
same way as they are commonly used by analytical labo
tories to extract organic contaminants from environmen
samples. LG processes use propane, butane, carbon die
ide, or other gases which have been pressurized at or n<
ambient temperature. Systems incorporating CST solver
utilize the unique solubility properties of those solven
Contaminants are extracted at one temperature where t
solvent and water are miscible and then the concentrat
contaminants are separated from the decanted liquid fr;
tion at another temperature where the solvent has minir
solubility in water. Triethylamine is an example of a C
solvent. Triethylamine is miscible in water at temperatu
less than 18°C and only slightly miscible above this te
perature.
A general schematic diagram of a standard solve
extraction process is given in Figure 1 [9, p.5]. The
systems are operated in either batch or continuous mc
and consist of four basic process steps: (1) extraction, (
separation, (3) desorption, and (4) solvent recovery.
In the first step, solids are loaded into an extracti
vessel and the vessel is purged with an inert gas. Solven
then added and mixed with the solids. Designs of vess
used for the extraction stage vary from countercurre;
continuous-flow systems to batch mixers. The ratio
solvent-to-solids also varies, but normally remains withir
range from 2:1 to 5:1. Solvent selection may also bi
Figure 1
General Schematic of a Standard Solvent Extraction Process
Solvent Make-up
Clean
Solvent
Solvent
with Organic
Contaminants
Contaminated Media
(pretreatment may"
be necessary)
.Concentrated
Contaminants
Clean
Solvent
Decontaminated
Solids plus
Residual Solvent
Decontaminated
Solvent
Recovery
(Distillation)
Extraction
Separation
(optional)
Desorption
(Raffinate
Stripping)
Engineering Bulletin: Solvent Extraction 3
F-71
-------
consideration. Ideally, a hydrophilic (having an affinity for
water) solvent or mixture of hydrophilic/hydrophobic (lack-
ing an affinity for water) solvents is mixed with the solids.
This hydrophilic solvent or solvent mixture will dewater the
solids and solubilize organic materials. Subsequent extrac-
tions may use only hydrophobic solvents. The contact time
and type of solvent used are contaminant-specific and are
usually selected during treatability studies.
Depending on the type of contaminated medium be-
ing treated, three phases may exist in the extractor: solid,
liquid, and vapor. Separation of solids from liquids can be
achieved by allowing solids to settle and pumping the
contaminant-containing solvent to the solvent recovery
system. If gravity separation is not sufficient, filtration or
centrifugation may be necessary. Residual solids will nor-
mally go through additional solvent washes within the
same vessel (for batch systems) or in duplicate reaction
vessels until cleanup goals are achieved. The settled solids
retain some solvent which must be removed. This is often
accomplished by thermal desorption.
Solvent recovery occurs in the final process step. Con-
taminant-laden solvent, along with the solvent vapors re-
moved during the desorption or raffinate stripping stage,
are transferred to a distillation system. To facilitate separa-
tion through volatilization and condensation, low boiling
point solvents are used for extraction. Condensed solvents
are normally recycled to the extractor; this conserves sol-
vent and reduces costs. Water may be evaporated or
discharged from the system, and still bottoms, which con-
tain high boiling point contaminants, are recovered for
future treatment.
In Figure 2, a general schematic diagram of an LC
extraction process is shown [9, p. 7], The same basic steps
associated with standard solvent processes are used with LC
systems; however, operating conditions are different, in-
creased pressure and temperature are required in order for
the solvent to take on LC characteristics.
Pumps or screw augers move the contaminated feed
through the process. In the extractor, the slurry is vigor-
ously mixed with the hydrophobic solvent. The extraction
step can involve multiple stages, with feed and solvent
moving in countercurrent directions.
The solvent/solids slurry is pumped to a decanting tank
where phase separation occurs. Solids settle to the bottom
of the decanter and are pumped to a desorber. Here, a
reduction in pressure vaporizes the solvent, which is re-
cycled, and the decontaminated slurry is discharged.
Contaminated solvent is removed from the top of the
decanter and is directed to a solvent recovery unit. A
reduction of pressure results in separating organic contami-
nants from the solvent. The organic contaminants remain
in the liquid phase and the solvent is vaporized and re-
moved. The solvent is then compressed and recycled to the
extractor. Concentrated contaminants are removed for
future treatment.
CST processes use extraction solvents for which solubil-
ity characteristics can be manipulated by changing the
temperature of the fluid. Such solvents include those
binary (liquid-liquid) systems that exhibit an upper CST
(sometimes referred to as upper consolute temperature), a
Figure 2
General Schematic of an LG Solvent Extraction Process
Clean Solvent
Contaminated Media
(pratreamnent may —|
be necessary)
Extraction
0)
Separation
(2)
Decontaminated
Media plus
Residual Solvent
Q-
Compressor/Pump
Contaminated
Solvent
Desorption
(3)
T
Decontaminated
Media
Solvent
Recovery
W
¦Q
Clean
Solvent
Concentrated
Contaminants
Clean Solvent
a
Solvent Make-up
J
Engineering Bulletin: Solvent Extraction
F-72
-------
Figure 3
General Schematic of a CST Solvent Extraction Process
Contaminated
Medta (pre- _
treatment may
be necessary)
Extraction
(1)
Solvent
Contaminated
Solvent
Separation
(2)
Contaminated
Solvent plus
Water
Decontaminated
Solids plus
Residual Solvent
Stripping
w
tr
Sofcent plus
Residual Water
Concentrated
Contaminants
Decanter
w
Desorption
(3)
Refrigeration
c
Solvent
Vapor
Stripping
(«>
Decontaminated
SoBds
Condenser
(4)
Water
Decanter
(<)
Solvent plus
Residual Water
TZ
Solvent
Solvent Make-up
Solvent plus
Residual Water
~
Treated
Water
lower CST (sometimes referred to as lower consolute tem-
perature), or both. For such systems, mutual solubilities of
the two liquids increase while approaching the CST. At or
beyond the CST, the two liquids are completely miscible in
each other. Figure 3 is a general schematic of a typical
lower CST solvent extraction process. Again, the same four
basic process steps are used; however, the solvent recovery
step consists of numerous unit operations [9, p.8].
Process Residuals
Three main product streams are produced from solvent
extraction processes. These include treated solids, concen-
trated contaminants (usually the oil fraction), and sepa-
rated water. Each of these streams should be analyzed to
determine its suitability for recycle, reuse, or further treat-
ment before disposal. Treatment options include: incin-
eration, dehalogenation, pyrolysis, etc.
Depending on the system used, the treated solids may
need to be dewatered, forming a dry solid and a separate
water stream. The volume of product water depends on the
inherent dewatering capability of the individual process, as
well as the process-specific requirements for feed slurrying.
Some residual solvent may remain in the soil matrix. This
can be mitigated by solvent selection, and if necessary, an
additional separation stage. Depending on the types and
concentrations of metal or other inorganic contaminants
present, post-treatment of the treated solids by some other
technique (e.g., solidification/stabilization) may be neces-
sary. Since the organic component has been separated,
additional solids treatment should be simplified.
The organic solvents used for extraction of contami-
nants normally will have a limited effect on mobilizing and
removing inorganic contaminants such as metals. In most
cases, inorganic constituents will be concentrated and
remain with the treated solids. If these remain below
cleanup levels, no further treatment may be required.
Alternatively, if high levels of leachable inorganic contami-
nants are present in the product solids, further treatment
such as solidification/stabilization, soil washing, or disposal
in a secured landfill may be required. The exception here
is organically bound metals. Such metals can be extracted
and recovered with the concentrated contaminant (oil)
fraction. High concentrations of specific metals, such as
lead, arsenic, and mercury, within the oil fraction can
restrict disposal and recycle options.
Concentrated contaminants normally include organic
contaminants, oils and grease (O&G), naturally occurring
organic substances found in the feed solids, and some
extraction fluid. Concentration factors may reduce the
Engineering Bulletin: Solvent Extraction
F-73
5
-------
overall volume of contaminated material to 1/10,000 of the
original waste volume depending on the volume of the total
extractable fraction. The highly-concentrated waste stream
which results is either destroyed or collected for reuse.
Incineration has been used for destruction of this fraction.
Dechlorination of contaminants such as PCBs remains un-
tried, but is a possible treatment. Resource recovery may
also be a possibility for waste streams which contain useful
organic compounds.
Use of hydrophilic solvents with moisture-containing
solids produces a solvent/water mixture and clean solids.
The solvent and water mixture are separated from the solids
by physical means such as decanting. Some fine solids may
be carried into the liquid stream. The solvent is normally
separated from the water by distillation [10], The water
produced via distillation will contain water-soluble con-
taminants from the feed solids, as well as trace amounts of
residual solvent and fines which passed through the sepa-
ration stage. If the feed solids were contaminated with
emulsifying agents, some organic contaminants may also
remain with the water fraction. Furthermore, the volume of
the water fraction can vary significantly from one site to
another, and with the use of dewatering as a pretreatment.
Hence, treatment of this fraction is dependent upon the
concentration of contaminants present in the water and the
flowrate and volume of residual water. In some cases, direct
discharge to a publicly owned treatment works (POTVV) or
stream may be acceptable; alternatively, onsite aqueous
treatment systems may be used to treat this fraction prior to
discharge.
Solvent extraction units are designed to operate with-
out air emissions. Nevertheless, during a recent SITE
Demonstration Test, solvent concentrations were detected
in 2 of 23 samples taken from the offgas vent system [11 ].
Corrective measures were taken to remedy this. In addi-
tion, emissions of dust and fugitive contaminants could
occur during excavation and materials handling opera-
tions.
Site Requirements
Solvent extraction units are transported by trailers.
Therefore, adequate access roads are required to get the
units to the site. Typical commercial-scale units of 25 to
125 tons per day (tpd) require a setup area of 1,500 to
10,000 square feet [12], NFPA recommends an exclusion
rone of 50 feet around solvent extraction systems operating
with flammable solvents [8, p. 4-61],
Standard 440V three-phase electrical service is needed.
Depending on the type of system used, between 50 and
10,000 gallons per day (gpd) of water must be available at
the site [12], The quantity of water needed is vendor and
site specific.
Contaminated soils or other waste materials are haz-
ardous and their handling requires that a site safety plan be
developed to provide for personnel protection and special
6
handling measures. Storage should be provided to hold the
process product streams until they have been tested to
determine their acceptability for disposal or release. De-
pending upon the site, a method to store waste that has
been prepared for treatment may be necessary. Storage
capacity requirements will depend on waste volume.
Onsite analytical equipment for conducting O&C
analyses and a gas chromatograph capable of determining
site-specific organic compounds for performance assess-
ment will shorten analytical turnaround time and provide
better information for process control.
Performance Data
Full-scale and pilot-scale performance data are cur-
rently available from only a few vendors: CF Systems,
Resources Conservation Company (RCC), Terra-Kleen Cor-
poration, and Dehydro-Tech Corporation. Lab-scale per-
formance data are also available from these and other
vendors. Data from Superfund Innovative Technology
Evaluation (SITE) demonstrations are peer-reviewed and
have been acquired in independently verified tests with
stringent quality standards. Likewise, performance data
Table 3
Contaminant Concentrations in Typical Solids
Treated by CF Systems' Process at Port Arthur,
Texas Refinery
Compound
mg/kg (ppm)
BOAT
Benzene
BDL
14
Ethylbenzene
BDL
14
Toluene
BDL
14
Xylenes
1.5
22
Naphthalene
2.2
42
Phenanthrene
3.4
34
2-Methylphenol
BDL
6.2
Anthracene
BDL
28
Benzo(a)anthracenc
BDL
28
Pyrene
1.6
36
Chrysene
BDL
15
Benzo(a)pyrene
BDL
12
Phenol
BDL
3.6
4-Methylphenol
BDL
6.2
Bis(2-E.H.)phthalate
BDL
7.3
Di-n-butyl phthalate
BDL
3.6
BDL below detection limits.
Engineering Bulletin: Solvent Extraction
F-74
-------
Table 5
Extraction of New Bedford Harbor Sediments
Using CF Systems' Process
Number of
Initial PCB
Final PCB
Passes
Concentration
Concentration
Reduction
Through
Test t (ppm)
(ppm)
(Percent)
extractor
1 350
8
98
9
2 288
47
84
1
3 2,575
200
92
6
from remedial actions at Superfund sites or EPA sponsored
treatability tests are assumed to be valid. The quality of
other data has not been determined.
The CF Systems' 25-tpd commercial unit treated refin-
ery sludge at Port Arthur, Texas, and operated with an on-
line availability of greater than 90 percent. Extraction
efficiencies for BTX and polynuclear aromatic hydrocarbon
(PAH) compounds were greater than 99 percent. As dem-
onstrated by Table 3, the typical level of organic; in the
treated solids met or exceeded the EPA Best Demonstrated
Available Technology (BDAT) standards required for these
listed refinery wastes [13].
Pilot-scale activities include the United Creosoting Su-
perfund Site treatability study and the SITE demonstration
at New Bedford Harbor, Massachusetts. During the spring
of 1989, CF Systems conducted a pilot-scale treatability
study for EPA Region VI and the Texas Water Commission at
the United Creosoting Superfund Site in Conroe, Texas. The
treatability study's objective was to evaluate the effective-
ness of the CF Systems process for treating soils contami-
nated with pentachlorophenol (PCP), dioxins, and creo-
sote-derived organic contaminants, such as PAHs. Treat-
ment data from the field demonstration (Table 4) show that
the total PAH concentration in the soil was reduced by more
than 95 percent Untreated soil had total PAH concentra-
tions ranging from 2,879 to 2,124 mg/kg [13].
The SITE demonstration was conducted during the fall
Table 4
CF Systems' Performance Data at United Creosote
Superfund Site
Notes: mg/kg on a dry weight basis. ND indicates not
detected. NA indicates not applicable.
Table 6
B.E.S.T * Process Data from the General Refining
Superfund Site
Initial
Product
TOP
Concentration
Solids Metal
Levels
Metals
(mg/kg)
(ppm)
(ppm)
, As
<0.6
<0.5
<0.0
Ba
239
410
<0.03
Cr
6.2
21
<0.05
Pb
3,200
23,000
5.2
Se
<4.0
<5.0
0.008
of 1988 to obtain specific operating and cost information
for making technology evaluations for use at other Super-
fund sites. Under the SITE Program, CF Systems demon-
strated an overall PCB reduction of more than 90 percent
(see Table 5) for harbor sediments with inlet concentrations
up to 2,575 ppm [14, p.6]. An extraction solvent blend of
propane and butane was used in this demonstration.
The ability of the RCC full-scale B.E.S.T.® process to
separate oil feedstock into product fractions was evaluated
by the EPA at the General Refining Superfund Site near
Savannah, Georgia, in February 1987. The test was con-
ducted with the assistance of EPA's Region X Environmental
Services Division in cooperation with EPA's Region IV Emer-
gency Response and Control Branch [15, p.1]. The site was
operated as a waste oil reclamation and re-refining facility
from the early 1950s until 1975. As a result of those
activities, four acidic oily sludge ponds with high levels of
heavy metals (Pb= 200 to 10,000 ppm, Cu= 83 to 190 ppm)
and detectable levels of PCBs (2.9 to 5 ppm) were pro-
duced. The average composition of the sludge from the
four lagoons was 10 percent oil, 20 percent solids, and 70
percent water by weight [15, p.1 3], The transportable 70-
tpd B.E.S.T.® unit processed approximately 3,700 tons of
sludge at the General Refining Site. The treated solids from
this unit were backfilled to the site, product oil was recycled
as a fuel oil blend, and the recovered water was pH adjusted
feed
Treated
Soil
Soil
Reduction
Compound
(mg/kg)
(mg/kg)
(percent)
PAHs
Acenaphthene
360
3.4
99
Acenaphthylene
1 5
3.0
B0
Anthracene
330
8.9
97
Benzo(a)anthracene
100
7.9
92
Benzo(a)pyrene
48
1 2
75
Benzo(b)fluoranthene
51
9.7
81
Benzo(g,h,i)perylene
20
1 2
40
Benzo(k)fluoranthene
50
1 7
66
Chrysene
1 1 0
9.1
92
Dibenzo(a,h)anthracene
ND
4.3
NA
Fluoranthene
360
11
97
Fluorene
380
3.8
99
lnd6no(1,2,3-cd)pyrene
19
11
58
Naphthalene
140
1.5
99
Phenanthrene
590
13
98
Pyrene
360
11
97
Total PAH concentration
2879
122.6
96
Engineering Bulletin: Solvent Extraction
F-75
7
-------
Table 7
Summary of Results from the SITE Demonstrator) of the RCC B.E.S.T.® Process
(Averages from Three Runs)
Transect 28 Sediment
Transect 6 Sediment
Parameter
PCBs
PAHs
Triethylamine
PCBs
PAHs
Triethylamine
Concentration in Untreated Sediment, mg/kg
12.1
550
NA
425
70,900
NA
Concentration in Treated Solids, mg/kg
0.04
22
45.1
1.8
510
103
Removal from Sediment, percent
99.7
96.0
NA
99.6
99.3
NA
Concentration in Oil Product, mg/kg
NA1
NA'
NA'
2,030
390,000
733'
Concentration in Water Product, mg/L
<0.003
<0.01
1.0
<0.001
<0.01
2.2
NA Not applicable.
1 The Transect 28 oil product was sampled at the end of the last run conducted on Transect 28 material. When the oil was sampled, there was
not sufficient oil present for oB polishing (using the solvent evaporator to remove virtual)/ all of the tn'ethylammr for the oil). Excess
triethylamine was therefore left in the oil.
^ This oil product was sampled following oH polishing.
and transported to a local industrial wastewater treatment
facility. Test results (Table 6) showed that the heavy metals
were mostly concentrated in the solids product fraction.
Toxicity Characteristic Leaching Procedure (TCLP) test re-
sults showed heavy metals to be in stable forms that resisted
leaching, illustrating a potential beneficial side effect when
metals are treated by the process [4, p.13].
During the summer of 1992 a SITE demonstration was
conducted to test the ability of the B.E.S.T.® system to
remove PAHs and PCBs from contaminated sediments ob-
tained from the Grand Calumet River. The pilot-scale
B.E.S.T.® system was primarily contained on two skids and
had an average daily capacity of 90 pounds of contami-
nated sediments. As Table 7 demonstrates, more than 96
percent of the PAHs and greater than 99 percent of the PCBs
initially present in the sediments collected from Transect 6
and Transect 28 of the Grand Calumet River were removed
[161.
Terra-Kleen Corporation has compiled remedial results
for its solvent extraction system at three sites; Treband
Superfund site, in Tulsa, Oklahoma; Sand Springs Substa-
tion site; Sand Springs, Oklahoma; and Pinette's Salvage
Yard Superfund site, Washburn, Maine. PCBs were the
primary contaminant at each of these sites. Table 8 summa-
rizes the performance at the Treband site. Preliminary
results from the Pinette's Salvage Yard site are given in
Table 9 [17],
The Carver-Greenfield (C-G) Process®, developed by
Dehydro-Tech Corporation, was evaluated during a SITE
demonstration at an EPA research facility in Edison, New
Jersey. During the August 1991 test, about 640 pounds of
drilling mud contaminated with indigenous oil and el-
evated levels of heavy metals were shipped to EPA in
Edison, New Jersey from the PAB Oil Site in Abbeville,
Louisiana. The pilot-scale unit was trailer-mounted and
capable of treating about 100 Ibs/hr of contaminated
drilling mud. The process removed about 90 percent of the
indigenous oil (as measured by solids/oil/water analysis).
The indigenous total petroleum hydrocarbon (TPH) remov-
als were essentially 100 percent for both runs [18, p. 1],
E. S. Fox Limited has determined performance data for
the Extraksol® Process developed by Sanivan Croup of
Montreal, Quebec, Canada. Performance data on contami-
nated soils and refinery wastes for the 1 ton per hour (tph)
mobile unit are shown in Table 10 [19]. The process uses
a proprietary solvent that reportedly achieved removal
efficiencies up to 99 percent (depending on the number of
extraction cycles and the type of soil) on solids with con-
taminants such as PCBs, O&G, PAHs, and PCP.
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to BOAT levels prior to land disposal
may sometimes be determined to be applicable or relevant
and appropriate requirements (ARARs) for CERCLA response
actions. The solvent extraction technology can produce a
treated waste that meets treatment levels set by BOAT, but
may not reach these treatment levels in all cases. The ability
to meet required treatment levels is dependent upon the
specific waste constituents and the waste matrix. In cases
where solvent extraction does not meet these levels, it still
may, in certain situations, be selected for use at the site if a
treatability variance establishing alternative treatment lev-
els is obtained. EPA has made the treatability variance
process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Reme-
dial Actions" (OSVVER Directive 9347.3-06FS, September -
1990) [20], and Superfund LDR Guide »6B, "Obtaining a .
8
F-76
Engineering Bulletin: Solvent Extraction
-------
Table 8
Terra-Kieen Soil Restoration Unit PC8 Removal at
Treband Superfund Site'
Initial
Final
Site
Level
Level
Coal
Reduction
(ppm)
(ppm)
(ppm)
(percent)
740
77
<100
89.6
810
3
<100
99.6
2,500
93
<100
96.3
1 Soil type: sand and concrete dust.
Table 9
Terra-Kleen Soil Restoration Unit PC8 Removal at
Pinette's Salvage Yard NPL Site1
Initial
final
Site
Level
Level
Coal
Reduction
(ppm)
(ppm)
(ppm)
(percent)
41.8
2.7
<5.0
93.5
76.9
4.31
<5.0
94.4
381
3.59
<5.0
99.1
1 Full scale data. Soil type: glacial till (gravel, sand, silt, and grey
marine clay).
Soil and Debris Treatability Variance for Removal Actions"
(OSWER Directive 9347.3-06BFS, September 1990) [21],
Another approach would be to use other treatment tech-
niques in series with solvent extraction to obtain desired
treatment levels.
Technology Status
As of October 1992, solvent extraction has been cho-
sen as the selected remedy at eight Superfund sites. Two of
these. General Refining,Georgia and Treband Warehouse,
Oklahoma were emergency responses that have been com-
pleted. The other sites include Norwood PCBs, Massachu-
setts; O'Conner, Maine; Pinette's Salvage Yard, Maine;
Ewan Property, New Jersey; Carolina Transformer, North
Carolina; United Creosoting, Texas (22, p. 51].
Solvent extraction systems are at various stages of
development. The following is a brief discussion of several
systems that have been identified.
CF Systems uses liquefied hydrocarbon gases such as
propane and butane as solvents for separating organic
contaminants from soils, sludges, and sediments. To date,
the CF Systems process has been used in the field at three
Superfund sites; nine petrochemical facilities and remedia-
tion sites; and a centralized treatment, storage, and dis-
Table 10
Summary of 1-tph Extrasol®
Process Performance Data
In
Out
Reduction
Contaminant Matrix
(ppm)
(ppm)
(percent)
O&G
Clayey Soil
1,800
182
89.9
OScG
Oily Sludge
72,000
2,000
97.2
O&G
Fuller's Earth
313,000
3,700
98.8
PAH
Clayey Soil
332
55
83.4
PAH
Oily Sludge
240
10
95.8
PCB
Clayey Soil
150
14
90.7
PCB
Clayey Soil
54
4.4
91.8
PCP
Porous Cravel
81.4
<0.21
99.7
PCP
Activated
Carbon
744
83
88.8
Note: Treated concentrations are based on criteria to be met
and not process efficiency
posal (TSD) facility. The CF Systems solvent extraction
technology is available in several commercial sizes and the
Mobile Demonstration Unit is available for onsite treatability
studies. CF Systems has supplied three commercial-scale
extraction units for the treatment of a variety of wastes [23,
p.3-12]. A 60-tpd treatment system was designed to
extract organic liquids from a broad range of hazardous
waste feeds at ENSCO's El Dorado, Arkansas, incinerator
facility. A commercial-scale extraction unit is installed at a
facility in Baltimore, Maryland, to remove organic contami-
nants from a 20 gallons- per-minute (gpm) wastewater
stream. A PCU-200 extraction unit was installed and
successfully operated at the Star Enterprise (Texaco) refin-
ery in Port Arthur, Texas. This unit was designed to treat
listed refinery wastes to meet or exceed the EPA's BDAT
standards. A 220 tpd extraction unit is currently being
designed for use at the United Creosoting Superfund site in
Conroe, Texas.
RCC's B.E.S.T.® system uses aliphatic amines (typically
triethylamine) as the solvent to separate and recover con-
taminants in either batch or continuous operation [4, p.2],
It can extract contaminants from soils, sludges, and sedi-
ments. In batch mode of operation, a pumpable waste is
not required. RCC has a transportable B.E.S.T.® pilot-scale
unit available to treat soils and sludges. This pilot-scale
equipment was used at a Gulf Coast refinery treating
various refinery waste streams and treated PCB-contami-
nated soils at an industrial site in Ohio during November of
1989. A full-scale unit with a nominal capacity of 70 tpd
was used to clean 3,700 tons of PCB-contaminated petro-
leum sludge at the General Refining Superfund Site in
Savannah, Georgia, in 1987 [16].
Terra-Kleen Corporation's Soil Restoration Unit was
developed for remedial actions involving Soil, debris, and
sediments contaminated with organic compounds. The :
Engineering Bulletin: Solvent Extraction
F-77
9
-------
Soil Restoration Unit ij a mobile system which uses various
combinations of up to 14 patented solvents, depending
upon target contaminants present. These solvents are non-
toxic and not listed hazardous wastes (1 7],
Dehydro-Tech Corporation's C-C Process is designed
for the cleanup of Superfund sites with sludges, soils, or
other water-bearing wastes containing hazardous com-
pounds, including PCBs, polycyclic aromatics, and dioxins.
A transportable pilot-scale system capable of treating 30 to
SO Ibs/hr of solids is available. Over 80 commercial C-C
Process facilities have been licensed in the past 30 years to
solve industrial waste disposal problems. More than half of
these plants were designed to dry and remove oil from
slaughterhouse waste (rendering plants) [12].
NuKEM Development Company/ENSR developed a
technique to remove PCBs from soils and mud several years
ago. Their solvent extraction method involves acidic con-
ditions, commercially available reagents to prepare the soil
matrix for exposure to the solvent, and ambient tempera-
tures and pressures [24], NuKEM Development Company/
ENSR is not currently marketing this technology for the
treatment of contaminated soils and sludges. Another
application being reviewed is the treatment of refinery
sludges (K wastes and F wastes). The Solvent Extraction
Process (SX.P) system developed for treating these wastes
has six steps; acidification, dispersion, extraction, raffinate
solvent recovery, stabilization/filtration, and distillation. A
pilot-scale SXP system has performed tests on over 20
different sludges. According to the vendor, preliminary
cost estimates for treating 5,000 tons per year of a feed with
10 percent solids and 10 percent oil appear to be less than
J 300 per ton [25].
The Extraksol® process was developed in 1984 by
Sanivan Croup, Montreal, Quebec, Canada [26, p-35]. It is
applicable to treatment of contaminated soils, sludges, and
sediments [26, p.45]. The 1-tph unit is suitable for small
projects with a maximum of 300 tons of material to be
treated. A transportable commercial scale unit, capable of
processing up to 8 tph, was constructed by E.S. Fox Ltd. At
present, the assembled unit is available for inspection at the
fabricator's facility in Welland, Ontario, Canada. [19].
The Low Energy Extraction Process (LEEP), developed
by ART International, Inc., is a patented solvent extraction
process that can be used on-site for decontaminating soils,
sludges and sediments. LEEP uses common organic sol-
vents to extract and concentrate organic pollutants such as
PCB, PAH, PCP, creosotes, and tar derived chemicals [27,
p.250]. Bench-scale studies were conducted on PCB con-
taminated soils and sediments, base neutral contaminated
soils and oil refinery sludges. ART has designed and con-
structed a LEEP Pilot Plant with a nominal solids throughput
of 200 Ibs/hr [12], The pilot plant has been operational
since March 1992. Recently, a 1 3 tph (dry basis) commer-
cial facility capable of treating soil contaminated with up to
S percent tar was completed for a former manufactured gas
plant site.
Phonix Milja, Denmark has developed the Soil Regen-
eration Plant, a 10 tph transportable solvent extraction
process. This process consists of a combined liquid extrac-
tion and steam stripping process operating in a closed loop.
A series of screw conveyors is used to transfer the contami-
nated soil through the process. Contaminants are removed
from soil in a countercurrent extraction process. A drainage
screw separates the soil from the extraction liquid. The
extraction liquid is distilled to remove contaminants and is
then recycled. The soil is steam heated to remove residual
contaminants before exiting the process [28].
Cost estimates for solvent extraction range from J 50 to
J900 per ton [12]. The most significant factors influencing
costs are the waste volume, the number of extraction
stages, and operating parameters such as labor, mainte-
nance, setup, decontamination, demobilization, and lost
time resulting from equipment operating delays. Extrac-
tion efficiency can be influenced by process parameters
such as solvent used, solvent/waste ratio, throughput rate,
extractor residence time, and number of extraction stages.
Thus, variation of these parameters, in particular hardware
design and/or configuration, will influence the treatment
unit cost component but should not be a significant con-
tributor to the overall site costs.
EPA Contact
Technology-specific questions regarding solvent ex-
traction may be directed to:
Mark Meckes
U.S. EPA, Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7348
Acknowledgments
This updated bulletin was prepared for the U.S. EPA,
Office of Research and Development (ORD), Risk Reduction
Engineering Laboratory (RREL), Cincinnati, Ohio, by Sci-
ence Applications International Corporation (SAIC) under
EPA Contract No. 68-CO-0048. Mr. Eugene Harris served as
the EPA Technical Project Monitor. Mr. |im Rawe (SAIC) was
the Work Assignment Manager. He and Mr. Ceorge Wahl
(SAIC) co-authored the revised bulletin. The authors are
especially grateful to Mr. Mark Meckes of EPA-RREL, who
contributed significantly by serving as a technical consult-
ant during the development of this document. The authors
also want to acknowledge the contributions of those who
participated in the develoment of the original bulletin.
The following other Agency and contractor personnel
have contributed their time and comments by peer review-
ing the document:
Dr. Ben Blaney EPA-RREL
Mr. |ohn Moses CF Technologies, Inc.
Dr. Ronald Dennis Lafayette College
10
F-78
Engineering Bulletin: Solvent Extraction
-------
REFERENCES
1. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environ-
mental Protection Agency, 1988.
2. Raghavan, R., D.H. Dietz, and E. Coles. Cleaning Exca-
vated Soil Using Extraction Agents: A State-of-the-Art
Review. EPA 600/2-89/034, U.S. Environmental Protec-
tion Agency, Releases Control Branch, Edison, N|, 1988.
3. CF Systems Corporation, Marketing Brochures (no
dates).
4. Austin, Douglas A. The B.E.S.T.® Process - An Innova-
tive and Demonstrated Process for Treating Hazardous
Sludges and Contaminated Soils. Presented at 81 st An-
nual Meeting of APCA, Preprint 88-6B.7, Dallas, Texas, .
1988.
5. Innovative Technology: B.E.S.T.® Solvent Extraction Pro-
cess. OSWER Directive 9200.5-253FS, U.S. Environmen-
tal Protection Agency, 1989.
6. Reilly, T.R., S. Sundaresan, and j.H. Highland. Cleanup
of PCB Contaminated Soils and Sludges By A Solvent
Extraction Process: A Case Study. Studies in Environ-
mental Science, 29: 125-139, 1986.
7. Weimer, l.D. The B.E.S.T.® Solvent Extraction Process
Applications with Hazardous Sludges, Soils and Sedi-
ments. Presented at the Third International Conference,
New Frontiers for Hazardous Waste Management, Pitts-
burgh, Pennsylvania, 1989.
8. Fire Protection Handbook. Fourteenth Ed. National Fire
Protection Association, 1976.
9. Guide for Conducting Treatability Studies under
CERCLA Solvent Extraction. EPA/540/R-92/016a, U.S.
Environmental Protection Agency, 1992.
10. Blank, Z. and W. Steiner. Low Energy Extraction Pro-
cess-LEEP: A New Technology to Decontaminate Soils,
Sediments, and Sludges. Presented at Haztech Interna-
tional 90, Houston Waste Conference, Houston, Texas,
May 1990.
11. Technology Evaluation Report - Resources Conservation
Company, Inc. B.E.S.T.® Solvent Extraction Technol-
ogy. EPA/540/R-92/079a U.S.Environmental Protection
Agency, 1993.
12. Vendor Information System for Innovative Treatment
Technologies (VISITT) Database, Version 1.0. U.S. Envi-
ronmental Protection Agency.
13. Site Remediation of Contaminated Soil and Sediments:
The CF Systems Solvent Extraction Technology. CF Sys-
tems, Marketing Brochure (no date).
14. Technology Evaluation Report - CF Systems Organics
Extraction System, New Bedford, MA, Volume I. EPA/
540/5-90/002, U.S. Environmental Protection Agency,
1990.
15. Evaluation of the B.E.S.T.® Solvent Extraction Sludge
Treatment Technology Twenty-Four Hour Test EPA/
600/2-88/051, U.S. Environmental Protection Agency,
1988.
16. Applications Analysis Report - Resources Conservation
Company, Inc. B.E.S.T.® Solvent Extraction Technology.
EPA/540/AR-92/079, U.S. Environmental Protection
Agency, 1993.
17. Cash, A.B. Full Scale Solvent Extraction Remedial Re-
sults. Presented at American Chemical Society, IfitEC
Division Special Symposium; Emerging Technologies for
Hazardous Waste Management, Atlanta, GA, September
21-23, 1992.
18. Applications Analysis Report - The Carver-Greenfield
Process®; Dehydro-Tech Corporation. EPA/540/AR-92/
002, U.S. Environmental Protection Agency, 1992.
19. Non-Thermal Extraction of Hazardous Wastes from Soil
Matrices. ES Fox Limited, Marketing Brochure (no
date).
20. Superfund LDR Guide #6A: (2nd Edition) Obtaining a
Soil and Debris Treatability Variance for Remedial Ac-
tions. Superfund Publication 9347.3-06FS, U.S. Environ-
mental Protection Agency, 1990.
21. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. Superfund
Publication 9347.3-06BFS, U.S. Environmental Protec-
tion Agency, 1990.
22. Innovative Treatment Technologies: Semi-Annual Status
Report (Fourth Edition). EPA542-R-92-011, U.S. Envi-
ronmental Protection Agency, 1992.
23. Applications Analysis Report - CF Systems Organics Ex-
traction System, New Bedford, MA. EPA/540/A5-90/
002, U.S. Environmental Protection Agency, 1990.
24. Massey, M.J., and S. Darian. ENSR Process for the Ex-
tractive Decontamination of Soils and Sludges. Present-
ed at the PCB Forum, International Conference for the
Remediation of PCB Contamination, Houston, Texas,
1989.
25. Chelemer, M.|. ENSR's SXP System for Treating Refinery
K-Wastes: An Update. ENSR Consulting and Engineer-
ing, Marketing Brochure (no date).
26. Paquin,)., and D. Mourato. Soil Decontamination with
Extraksol. Sanivan Group, Montreal, Canada (no date),
pp. 35-47.
27. The Superfund Innovative Technology Evaluation Pro-
gram: Technology Profiles Fifth Edition. EPA/540/R-92/
077, U.S. Environmental Protection Agency, 1992.
28. Phenix Milje Cleans Contaminated Soil On-Site: In Mo-
bile Extraction Plant. Phenix Milje Marketing Informa-
tion (no date).
Engineering Bulletin: Solvent Extraction
F-79
11
-------
United States Office of Emergency and Office of
Environmental Protection Remedial Response Research and Development
Agency Washington, DC 20440 Cincinnati, OH 45268
Superfund EPA/540/2-91/021 October 1991
Engineering Bulletin
v»EPA In Situ Soil Flushing
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element." The Engineer-
ing Bulletins are a seres of documents that summarize the latest
information available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial project
managers, on-scene coordinators, contractors, and other site
cleanup managers understand the type of data and site char-
acteristics needed to evaluate a technology for potential appli-
cability to their Superfund or other hazardous waste site. Those
documents that describe individual treatment technologies fo-
cus on remedial investigation scoping needs. Addenda will be
issued periodically to update the original bulletins.
Abstract
In situ soil flushing is the extraction of contaminants from
the soil with water or other suitable aqueous solutions. Soil
flushing is accomplished by passing the extraction fluid through
in-place soils using an injection or infiltration process. Extraction
fluids must be recovered and, when possible, are recycled. The
method is potentially applicable to all types at soil contami-
nants. Soil flushing enables removal of contaminants from the
soil and is most effective in permeable soils. An effective
collection system is required to prevent migration of contami-
nants and potentially toxic extraction fluids to uncontaminated
areas of the aquifer. Soil flushing, in conjunction with in situ
bioremediation, may be a cost-effective means of soil remedia-
tion at Certain sites [1, p. vi] [2, p. 11].* Typically, soil flushing
is used m conjunction with other treatments that destroy con-
taminants or remove them from the extraction fluid and
groundwater.
Soil flushing is a developing technology that has had lim-
ited use in the United States. Typically, laboratory and field
treatability studies must be performed under site-specific condi-
tions before soil flushing is selected as the remedy of choice. To
* 'reference number, page number)
date, the technology has been selected as part of the source
control remedy at 12 Superfund sites. This technology is
currently operational at only one Superfund site; a second is
scheduled to begin operation in 1991 [3][4], EPA completed
construction of a mobile soil-flushing system, the In Situ
Contaminant/Treatment Unit, in 1988. This mobile soil-flush-
ing system is designed for use at spills and uncontrolled hazard-
ous waste sites [5].
This bulletin provides information on the technology appli-
cability, the technology limitations, a description of the tech-
nology, the types of residuals resulting from the use of the
technology, site requirements, the latest performance data, the
status of the technology, and sources of further information.
Technology Applicability
In situ soil flushing is generally used in conjunction with
other treatment technologies such as activated carbon, biodeg-
radation, or chemical precipitation to treat contaminated
groundwater resulting from soil flushing. In some cases, the
process can reduce contaminant concentrations in the soil to
acceptable levels, and thus serve as the only soil treatment
technology. In other cases, in situ biodegradation or other in
situ technologies can be used in conjunction with soil flushing
to achieve acceptable contaminant removal efficiencies. In
general, soil flushing is effective on coarse sand and gravel
contaminated with a wide range of organic, inorganic, and
reactive contaminants. Soils containing a large amount of clay
and silt may not respond well to soil flushing, especially if it is
applied as a stand-atone technology.
A number of chemical contaminants can be removed from
soils using soil flushing. Removal efficiencies depend on the
type of contaminant as well as the type of soil. Soluble (hydro-
philic) organic contaminants often are easily removed from soil
by flushing with water alone. Typically, organics with octanol/
water partition coefficients (Kof less than 10 (log KW1< 1) are
highly soluble. Examples of such compounds induce lower
molecular weight alcohols, phenols, and carboxylic acids [6].
Low solubility (hydrophobic) organics may be removed by
selection of a compatible surfactant [7]. Examples of such
compounds include chlorinated pesticides, polychlorinated bi-
phenyls (PCBs), semivolatiles (chlorinated benzenes and poly- j
nuclear aromatic hydrocarbons), petroleum products (gasoline,
F-80
-------
jet fuel, kerosene, oils and greases), chlorinated solvents
(trichloroethene), and aromatic solvents (benzene, toluene, xy-
lenes and ethylbenzene) [8]. However, removal of some of
these chemical classes has not yet been demonstrated.
Metals may require acids, chelating agents, or reducing
agents for successful soil flushing. In some cases, all three types
of chemicals may be used in sequence to improve the removal
efficiency of metals [9J. Many inorganic metal salts, such as
carbonates of nickel, zinc, and copper, can be flushed from the
soil with dilute acid solutions [6], Some inorganic salts such as
sulfates and chlorides can be flushed with water alone.
In situ soil flushing has been considered for treating soils
contaminated with hazardous wastes, including pentachloro-
phenol and creosote from wood-preserving operations, organic
solvents, cyanides and heavy metals from electroplating resi-
dues, heavy metals from some paint sludges, organic chemical
production residues, pesticides and pesticide production resi-
dues, and petroleum/oil residues [10, p. 13][11, p. 8][7][12].
The effectiveness of soil flushing for general contaminant
groups [10, p. 13] is shown in Table 1. Examples of constitu-
ents within contaminant groups are provided in Reference 10,
"Technology Screening Guide For Treatment of CERCLA Soils
and Sludges." Table 1 is based on currently available informa-
tion or professional judgment where definitive information is
currently inadequate or unavailable. The demonstrated effec-
tiveness of the technology for a particular site or waste does not
ensure that it will be effective at all sites or that the treatment
efficiency achieved will be acceptable at other sites. For the
ratings used in this table, demonstrated effectiveness means
that, at some scale, treatability was tested to show that, for that
particular contaminant and matrix, the technology was effec-
tive. The ratings of potential effectiveness and no expected
effectiveness are based upon expert judgment. Where poten.
tial effectiveness is indicated, the technology is believed capable
of successfully treating the contaminant group in a particular
matrix. When the technology is not applicable or will probably
not work for a particular combination of contaminant group
and matrix, a no-expected-effectiveness rating is given. Other
sources of general observations and average removal efficien-
cies for different treatability groups are the Superfund LDR
Guide #6A, "Obtaining a Soil and Debris Treatability Vanance
for Remedial Actions" (OSWER Directive 9347.3-06FS) [13],
and Superfund LDR Guide #6B, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions" (OSWER Directive
9347.3-07FS) [14],
Information on deanup objectives, as well as the physical
and chemical characteristics of the site soil and its contami-
nants, is necessary to determine the potential performance of
this technology. Treatability tests are also required to determine
the feasibility of the specific soil-flushing process being consid-
ered. If bench-test results are promising, pilot-scale demonstra-
tions should be conducted before making a final commitment
to full-scale implementation. Table 2 contains physical and
chemical soil characterization parameters that should be estab-
lished before a treatability test is conducted at a specific site.
The table contains comments relating to the purpose of the
specific parameter to be characterized and its impact on the
process [15, p. 715] [16, p. 90] [1 7].
Soil permeability is a key physical parameter for determin-
ing the feasibility of using a soil-flushing process. Hydraulic
conductivity (K) is measured to assess the permeability of soils.
Soils with low permeability (K < 1.0 x 10"s cm/sec) will limit the
ability of flushing fluids to percolate through the soil in a
reasonable time frame. Soil flushing is most likely to be effective
in permeable soils (K > 1.0 x 103 cm/sec), but may have limited
application to less permeable soils (1.0 x 10 s cm/sec < K < 1.0 x
10"3 cm/sec). Since there can be significant lateral and vertical
variability in soil permeability, it is important that field measure-
ments be made using the appropriate methods.
Prior to field implementation of soil flushing, a thorough
groundwater hydrologic study should be carried out. This
should include information on seasonal fluctuations in water
level, direction of groundwater flow, porosity, vertical and hori-
zontal hydraulic conductivities, transmissivity and infiltration
(data on rainfall, evaporation, and percolation).
Moisture content can affect the amount of flushing fluids
required. Dry soils will require more flushing fluid initially to
mobilize contaminants. Moisture content is also used to calcu-
late pore volume to determine the rate of treatment [15].
The concentration and distribution of organic contami-
TatX* 1
Effectiveness of Soil Rushing on General
Contaminant Groups
Contaminant Croups
Effectiveneu
Halogenated volatile;
m
Halogenated semivolatiles
T
Nonhalogenated volatile*
T
Nonhalogenated semivolatiles
¦
c
0
0\
PCBs
T
V,
O
Pesticides (halogenated)
T
Dioxins/Furans
T
Organic cyanides
T
Organic corrosives
T
Volatile metals
T
Nonvolatile metals
¦
*5
o
Asbestos
~
Oi
O
c
Radioactive materials
~
Inorganic corrosives
T
Inorganic cyanides
~
1
Oxidizers
T
0
Reducers
T
¦
Demonstrated Effectiveness: Successful treatability test at some scale
completed.
~
Potential effectiveness: Expert op«n«on that technology will wort.
J No £*pected Effectiveness: tuperi opinion that tecnnotogy will not work.
2
Engineering Bulletin: In Situ Soil Flushing
F-81
-------
Tabt* 2
ChOfOCt«ft2atlon Poram«t«n
Poramtter
Soil oermeability
21 0 x TO-* cm/sec
<1.0 x 10*s cm/sec
Soil structure
Soil porosity
Moisture content
Groundwater hydroiogy
Organics
Concentration
Solubility
Partition
coefficient
Metals
Concentration
Solubility products
Reduction potential
Complex stability
constants
Total Organic Carbon
(TOO
Oay content
Cation Exchange
Capacity (CEO
pH, buffering
capacity
Purpose and Comment
Affects treatment time and
efficiency of contaminant removal
Effective soil flushing
Limited soil flushing
Influences low patterns
(channeling, Wockage)
Determines moisture capacity of soil:
at saturation (pore volume)
Affects flushing fluid transfer
requirements
Critical in controlling the recovery
of injected fluids and contaminants ;
Determine contaminants and j
assess flushing fluids required, !
flushing fluid compatibility. '
changes in flushing fluid with j
changes n contaminants. |
Concentration and species of cons- j
tituents will determine flushing fluid '
compatibility, mobility of metals, i
post treatment. j
I
Adsorption of contaminants on I
soil increases with increasing TOC. I
Imoortant in marine wetland sites, I
which typically have high TOC.
Adsorption of contaminants on soil
increases with increasing clay
content
May affect treatment of metallic
compounds.
May affect treatment additives
required, compatibility with
equipment materials of construe-
lion, wash fluid compatibility.
nants and metals are key chemical parameters. These param-
eters determine the type and quantity of flushing fluid required
as well as any pojt«treatment requirements. The solubility and
partition coefficients of organics in water or other solutions are
also important in the selection of the proper flushing fluids.
The species of metal compounds present will affect the solubil-
ity and leachability of heavy metals.
High humic content and high cation exchange capacity
tend co reduce the removal efficiency of soil flushing. Seme
organic contaminants may adsorb to humic matenals or c ays
in soils and, therefore, are difficult to remove during soil flusr-
>ng. Similarly, the binding of certain metals with days due :o
cationic exchange makes them difficult to remove with soil
'lushing. The buffenng capacity of the soil will affect the
amount required of some additives, especially acids. Precipita-
tion reactions (resulting in dogging of soil .cores) can occur due
to pH changes in the Hushing fluid caused oy che neutralizing
effect of soils with high buffenng capacity. Soil pH can affect
the speciation of metal compounds resulting m changes in the
solubility of metal compouncs in the flushing fluid.
Limitations
Cenerally, remediation times with this technology will be
lengthy (one to many years) due to the slowness of diffusion
processes in the liquid phase. This technology requires hydrau-
lic control to avoid movement of contaminants offsite. The
hydrogeology of some sites may make :nis difficult or impos-
sible to achieve.
Contaminants in soils containing a high percentage of silt-
and day-sized particles typically are strongly adsorbed and
difficult to remove. Also, soils with silt and day tend to be less
permeable. In such cases, soil flushing generally should not be
considered as a stand-alone technology.
Hydrophobic contaminants generally require surfactants
or organic solvents for their removal from soil. Complex mix-
tures of contaminants in the soil (such as a mixture of metals,
nonvolatile organics, and semivolatile organics) make it difficult
to formulate a single suitable flushing fluid that wiil consistently
and reliably remove all the different types of contaminants from
the soil. Frequent changes in contaminant concentration and
composition in the vertical and horizontal soil profiles will com-
plicate the formulation of the flushing fluid. Sequential steps
with frequent changes in the flushing formula may be required
at such complex sites [10, p. 77],
Bacterial fouling of infiltration and recovery systems and
treatment units may be a problem particularly if high iron
concentrations are present in the groundwater or if biodegrad-
able reagents are being used.
While "ushing additives such as surfactants and cl-elants
may enhance some contaminant removal efficiencies in the soil
Rushing process, they also tend to interfere with the down-
stream wastewater treatment processes. The presence of these
additives in the washed soil and in the wastewater treatment
sludge may cause some difficulty in their disposal. Costs associ-
ated with additives, and the management of these additives as
part of the residuals/wastewater streams, must be carefully
weighed against the incremental improvements in soil-flushing
performance that they may provide.
Engineering Bulletin: In Situ Soil Flushing
F-82
3
-------
Technology Description
Figure 1 is a general schematic of the soil flushing process (18, p.
7], The flushing fluid is applied (1) to the contaminated soil by
subsurface in|ectjon wells, shallow infiltration galleries, surface flood-
ing, or above-ground sprayers. The flushing fluid is typically water
and may contain additives to improve contaminant removal.
The flushing fluid percolates through the contaminated soil,
removing contaminants as it proceeds. Contaminants are mobi-
lized by solubilization into the flushing fluid, formation of emul-
sions, or through chemical reactions with the flushing fluid [19].
Contaminated flushing fluid or leachate mixes with ground-
water and is collected (2) for treatment. The flushing fluid
delivery and the groundwater extraction systems are designed
to ensure complete contaminant recovery [7], Ditches open to
the surface, subsurface collection drains, or groundwater recov-
ery wells may be used to collect flushing fluids and mobilized
contaminants. Proper design of a fluid recovery system is very
important to the effective application of soil flushing.
Contaminated groundwater and flushing fluids are cap-
tured and pumped to the surface in a standard groundwater
extraction well (3). The rate of groundwater withdrawal is
determined by the flushing fluid delivery rate, the natural infil-
tration rate, and the groundwater hydrology. These will deter-
mine the extent to which the groundwater removal rate must
exceed the flushing fluid delivery rate to ensure recovery of all
reagents and mobilized contaminants. The system must be
designed so that hydraulic control is maintained.
The groundwater and flushing fluid are treated (4) using
the appropriate wastewater treatment methods. Extracted
groundwater is treated to reduce the heavy metal content,
organics, total suspended solids, and other parameters until
they meet regulatory requirements. Metals may be removed
by lime precipitation or by other technologies compatible with
the flushing reagents used. Organics are removed with acti-
vated carbon, air stripping, or other appropriate technologies.
Whenever possible, treated water should be recycled as makeup
water at the front end of the soil-flushing process.
Flushing additives (5) are added, as required, to the
treated groundwater, which is recycled for use as flushing
fluid. Water alone is used to remove hydrophilic organics and
soluble heavy-metal salts [9]. Surfactants may be added to
remove hydrophobic and slightly hydrophilic organic con-
taminants [12], Chelating agents, such as ethylene-
diaminetetra-acetic acid (EDTA), can effectively remove cer-
tain metal compounds. Alkaline buffers such as tetrasodium
pyrophosphate can remove metals bound to the soil organic
fraction. Reducing agents such as hydroxylamine hydrochlo-
ride can reduce iron and manganese oxides that can bind
Figur* 1
Schematic o< Soil Flushing System
Spray Application
(V
Groundwater
Treatment
Pump Flushing
I 1 Additives
Groundwater
Extraction Well
Water Table
Contaminated Area
Leachate
Collection
Groundwater
Zone
Low Permeability
Zone '¦
4
F-83
Engineering Bulletin: In Siiu Soil Flushing
-------
metals m soil. Insoluble heavy-metal compounds also can be
reduced or oxidized to more soluble compounds. Weak acid
solutions can improve the solubility of certain heavy metals
[9]. Treatability studies should be conducted to determine
comparability of che flushing reagents with the contaminants
and with the site soils.
Process Residuals
The primary waste stream generated is contaminated flush-
ing fluid, which is recovered along with groundwater. Recov-
ered flushing fluids may need treatment to meet appropriate
discharge standards prior to release to a local, publidy-owned
wastewater treatment works or receiving streams. To the maxi-
mum extent practical, this water should be recovered and
reused in the flushing process. The separation of surfactants
from recovered flushing fluid, for reuse in the process, is a major
factor in the cost of soil flushing. Treatment of the flushing fluid
results in process sludges and residual solids, such as spent
carbon and spent ion exchange resin, which must be appropri-
ately treated before disposal. Air emissions of volatile contami-
nants from recovered flushing fluids should be collected and
treated, as appropriate, to meet applicable regulatory standards.
Residual flushing additives in the soil may be a concern and
should be evaluated on a site-specific basis.
Site Requirements
Access roads are required for transport of vehicles to and
from the site. Stationary or mobile soil-flushing process systems
are located on site. The exact area required will depend on the
vendor system selected and the number of tanks or ponds
needed for washwater preparation and wastewater treatment.
Because contaminated flushing fluids are usually consid-
ered hazardous, their handling requires that a site safety plan be
developed to provide for personnel protection and special han-
dling measures during wastewater treatment operations. Fire
hazard and explosion considerations should be minimal, since
the soil-flushing fluid is predominantly water.
An Underground Injection Control (UIC) Permit may be
necessary if subsurface infiltration galleries or injection welts are
used. When groundwater is not recycled, a National Pollution
Discharge Elimination System (NPDES) or State Pollution Dis-
charge Elimination System (SPDES) permit may be required.
Federal, State, and local regulatory agencies should be con-
tacted to determine permitting requirements before imple-
menting this technology.
Slurry wails or other containment structures may be needed
along with hydraulic controls to ensure capture of contaminants
and 'lushing additives. Climatic conditions such as precipitation
cause surface runoff and water infiltration. 8erms, dikes, or other
runoff control methods may be required. Impermeable mem-
branes may be necessary to limit infiltration of precipitation,
which could cause dilution of flushing solution and loss of hy-
draulic control. Cold weather freezing must also be considered
for shallow infiltration galleries and above-ground sprayers.
Engineering Bulletin: In Situ Soil Flushing
F-84
Performance Data
Some of the data presented for specific contamirart re-
moval effectiveness were obtained from publications devel-
oped ay the respective soil-flushing-system vendors. The qual-
ity of this information has not been determined; however >t
does give an indication of the effeciveness of in situ soil
flushing.
Tetrachloroethylene was discharged into the aquifer at the
site of a spill in Sindelfingen, Cermany. The contaminated
aquifer is a high-permeability (k=5.10 x 10"4 m/sec) layer over-
laying a clay barrier. Soil flushing was accomplished by infiltrat-
ing water into the ground through ditches. The leaching liquid
and polluted groundwater were pumped out of eight wetls and
treated with activated carbon. The treated water was recycled
through the infiltration ditches. Within 18 months, 17 metric
tons of chlorinated hydrocarbons were recovered [19, p. 565],
Two percolation basins were installed :o flush contami-
nated soil at the United Chrome Products site near Corvallis,
Oregon. Approximately 1,100 tons of soil containing the
highest chromium concentrations were excavated and dis-
posed of offsite. The resulting pits from the excavations were
used as infiltration basins to flush the remaining contaminated
soil. The soil-flushing operation for the removal of hexavalent
chromium from an estimated 2.4 million gallons of contami-
nated groundwater began in August 1988. No information on
the site soils was provided, but preliminary estimates were that
a groundwater equilibrium concentration of 100 mg/L chromium
would be reached in 1 to 2 years, but that final cleanup to 10
mg/L would take up to 25 years [20, p. H-l ]. Since that time
over 6-million gallons of groundwater, containing over 25,000
pounds of chromium, have been removed from the 23 extrac-
tion wells in the shallow aquifer. Average monthly chromium
concentrations in the groundwater decreased from 1,923 mg/
L in August 1988 to 96 mg/L in March 1991 [4],
Waste-Tech Services, Inc. performed two tests of soil-
flushing techniques to remove creosote contamination at the
Laramie Tie Plant sit* in Wyoming. The first test involved slowly
flooding the soil surface with water to perform primary oil
recovery (POR). Soil flushing reduced the average concentra-
tion of total extractable organics (TEO) from an estimated
initial concentration of 93,000 mg/kg to 24,500 mg/kg, a 74
percent reduction. The second test involved sequential treat-
ment with alkaline agents, polymers, and surfactants. During
the 8-month treatment period, average TEO concentrations
were reduced to 4,000 mg/kg. This represents an 84 percent
reduction from the post-POR concentration (24,500 mg/kg)
and a 96 percent reduction from the estimated initial concen-
tration (93,000 mg/kg). The tests were performed in alluvial
sands and gravels. The low permeability of adjacent silts and
days precluded soil flushing [22].
Laboratory tests were conducted on contaminated soils
from a fire-training area at Volk Air Force Base. Initial
concentrations of oil and grease in the soils were reported to be
10,000 and 6,000 mg/kg. A 1.5-percent surfacunt solution in
water was used to flush soil columns. The tests indicated that
75 to 94 percent of the initial hydrocarbon contamination
could be removed by flushing with 12-pore volumes of liquid.
5
-------
However, field tests were unsuccessful in removing the same
contaminants. Seven soil-flushing solutions, including the solu-
tion tested in the laboratory studies, were tested in field studies.
The flushing solutions were delivered to field test cells measur-
ing 1 foot deep and 1 to 2 feet square. Only three of the seven
tests achieved the target delivery of 14-pore volumes. Two of
the test cells plugged completely, permitting no further infiltra-
tion of flushing solutions. There was no statistically significant
removal of soil contaminants due to soil flushing. The plugging
of test cells may be related to the use of a surfactant solution.
By hydrolyzing in water, surfactants may block soil pores by
forming either floes or surfactant aggregates called micelles. In
addition, if the surfactant causes fine soil particles to become
suspended in the flushing fluid, narrow passages between soil
particles could be blocked, tf enough of these narrow passages
are blocked along a continuous front, a "mat" is said to have
formed, and fluid flow is halted in that area [23] [7],
Resource Conservation Recovery Act (RCRA) Land Dis-
posal Restrictions (IDRs) that require treatment of wastes to
best demonstrated available technology (BDAT) levels prior to
land disposal may sometimes be determined to be applicable
or relevant and appropriate requirements (ARARs) for CERCLA
response actions. The soil-flushing technology can produce a
treated waste that meets treatment levels set by BDAT, but
may not reach these treatment levels in all cases. The ability
of the technology to meet required treatment levels is depen-
dent upon the specific waste constituents and the waste
matrix. In cases where soil flushing does not meet these
levels, it still may, in certain situations, be selected for use at
the site if a treatability variance establishing alternative treat-
ment levels is obtained. EPA has made the treatability vari-
ance process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be justi-
fied for handling complex soil and debris matrices The
following guides describe when and how to seek a treatability
vanance for soil and debris: Superfund IDR Guide #6A
"Obtaining a Soil and Debris Treatability Variance for Rem*
dial Actions" (OSWER Directive 9347.3-06FS) [13], and Super-
fund IDR Guide #6B, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions" (OSWER Directive 9347.3-07FS)
[14]. Another approach could be to use other treatment
techniques in conjunction with soil flushing to obtain desired
treatment levels.
Technology Status
In situ soil flushing is a developing technology that has had
limited application in the United States. In situ soil flushing
technology has been selected as one of the source control
remedies at the 12 Superfund sites listed in Table 3 [3].
EPA Contact
Technology-specific questions regarding soil flushing may
be directed to:
Michael Gruenfeld
U.S. EPA, Releases Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Avenue, Building 10
Edison, New Jersey 08837
Telephone FTS 340-6625 or (908) 321-6625.
Table 3
Sup*rfund Sites Using In Situ Soil Flushing
Site
Location (Region)
Primary Contaminants
Status
Byron 8arrel & Drum
Genesee County, NY (2)
VOCs(BTX, PCE, and TCE)
Pre-design: finalizing workplan
Goose Farm
Plumsted Towmhip, NJ (2)
VOCs (Toluene. Ethylbenzene,
Oichloromethane, and TCE), SVOCs, and PAHs
In design: 30% design phase
Upari Landfill
Gloucester, N| (2)
VOCs (Benzene, Ethyl benzene, Dkhlormethane,
and TCE), SVOCs. PAHs and Chlonnated ethers
(bis-2-chloroethylether)
Operational, summer '91
Vineland Chemical
VineUnd. N| (2)
Arsenic and VOCs (Dichloromethane)
Pre*desiqn
Harvey-Knott Drum
DEf3)
Lead
In design: re-evaluating alternative
l.A. Clarke & Son
Spotsylvania, VA (3)
Creosote. PAHs, and 8enzene
In design
Ninth Avenue Dump
Garry, in (5)
VOCs (BTEX. TCE). PAHs, Phenols. Lead, PCBs.
and Tool Metals
In design: pilot failed
U.S. Aviex
Niles, Ml (5)
VOCs (Carbon Tetrachloride, DCA.
Ethylbenzene, PCE. TCE. Toluene. TCA. Preon,
Xylene, and Chloroform)
Pre-design: re-evaluating alternatives
South Calvacale Street
Houston, TX (6)
PAHs
In design
United Chrome Product*
Corvallis. OR (10)
Chromium
Operational since 8/88
Cross Brothers Pail
Pembroke, ll (5)
VOCs (Benzene. PCE. TCE. Toluene, and
Xylenes) and PCBs
In desgn: developing workpian .
Bog Creek.farm -
Howell Township. N) (2)
VOCs. Organics
In design: treatment plant completed.,
dump and treat not installed
6 Engineering Bulletin: In Situ Soil Flushing
F-85
-------
Acknowledgments
This bulletin was prepared for the U.S. Ervroimertal Protec-
tion Agency, Office of Researcn and Development (CRD), Risk
Redaction Engineering Laboratory (RREL), Cincinnati, Qhto. by
Science Aoplications International Corporation (SAIC) under con-
tract No. 63-C9-0C62. Mr. Eugene Harrs served as the EPA
Technical Project Monitor. Mr. Cary Baker was SAlC's Work As-
signment Marager. This bulletin was authored by Mr. jim Rawe cf
SAIC. The author s espec ally grateful to Ms. joyce Perdek of EPA,
RREL, who has contnbuted significantly by serving as a technical
reviewer during the develooment of this document
rh« following other Agency and contractor personnel he
expert review meeting anc/or peer reviewing the document;
Mr. Benjamin Blaney
Ms. Sally Clement
Mr. Clyde Dial
Ms. Linda Pied'er
Dr David Wiison
Ms. Tlsh Zimmerman
EPA-RREL
Baick, Hartman and Espcsito
SAIC
EPA-TIO
Vanderbilt University
EPA-OSWER
REFERENCES
1. Handbook: In Situ Treatment of Hazardous Waste-
Contaminated Soils. EPA/540/2-90/002, U.S. Environ-
mental Protection Agency, 1990.
2. A Compendium of Technologies Used in the Treatment
of Hazardous Wastes. EPA/625/8-87/014, U.S. Environ-
mental Protection Agency, 1987.
3. Innovative Treatment Technologies; Semi-Annual Status
Report. EPA/540/2-91/001, U.S. Environmental Protec-
tion Agency, 1991.
4. Personal communications of SAIC staff with RPMs, 1991.
5. In Situ Containment/Treatment System, Fact Sheet. U.S.
Environmental Protection Agency, 1988.
6. Sanning, D. E., et. al. Technologies for In Situ Treatment
of Hazardous Wastes. EPA/600/D-87/014, U.S. Environ-
mental Protection Agency, 1987.
7. Nash, J. and R.P. Traver. Field Evaluation of In Situ
Washing of Contaminated Soib With Water/Surfactants.
Overview-Soils Washing Technologies For Comprehen-
sive Environmental Response, Compensation, and Liability
Act. Resource Conservation and Recovery Act, Leaking
Underground Storage Tanks, Site Remediation, U.S.
Environmental Protection Agency, 1989. pp. 383-392.
8. Wilson, D. et. al.. Soil Washing and Flushing With
Surfactants. Tennessee Water Resources Research Center.
September, 1990.
9. Ellis, W.D., T.R. Fogg and A.N. Tafuri. Treatment of Soils
Contaminated With Heavy Metals. Overview-Soib
Washing Technologies For; Comprehensive Environmen-
tal Response, Compensation, and Liability Act, Resource
Conservation and Recovery Act, Leaking Underground
Storage Tanks, Site Remediation, U.S. Environmental
Protection Agency, 1989. pp. 127-134.
10. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U S. Ervironmen-
tal Protection Agency, 1988.
11. Nunno, T.|„ JA Hyman, and T. Pheitfer. Development of
Site Remediation Technologies in European Countries.
Presented at Workshop on the Extractive Treatment of
Excavated Soil. U.S. Environmental Protection Agency,
Edison, New lersey, 1988.
12. Ellis, W.D., |.R. Payne, and G.D. McNabb, Project
Summary: Treatment of Contaminated Soils with
Aqueous Surfactants. EPA/600/S2-85/129, U.S. Environ-
¦ mental Protection Agency, 1985.
13. Superfund LDR Guide #6A: Obtaining a Soil and Debris
Treatability Variance for Remedial Actions. OSWER
Directive 9347.3-06FS, U.S. Environmental Protection
Agency, 1989.
14. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
15. Sims, R.C Soil Remediation Techniques at Uncontrolled
Hazardous Waste Sites, A Critical Review. Air & Waste
Management Association, 1990.
16. Guide for Conducting Treatability Studies Under CERCL4,
Interim Final. EPA/540/2-89/058, U.S. Environmental
Protection Agency, 1989.
17. Connick, C.C. Mitigation of Heavy Metal Migration in
Soil. Overview-Soils Washing Technologies For: Compre-
hensive Environmental Response, Compensation, and
Liability Act, Resource Conservation and Recovery Act,
Leaking Underground Storage Tanks, Site Remediation,
U.S. Environmental Protection Agency, 1989 pp. 155-
165.
Engineering Bulletin: In Situ Soil Flushing
F-86
7
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APPENDIX G
ARTICLE ON INCINERATION
(Copyrighted 1993 by the Journal of the Air and Waste Management Association.
Reproduced with permission.)
G-l
-------
FEATURE
Incineration of Hazardous Waste:
A Critical Review Update
Clyde R. Dempsey and E. Timothy Oppelt
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio
Over the last 15 years, concern over improper disposal practices of the past has
manifested itself in the passage of a series of federal and state-level hazardous
waste cleanup and control statutes of unprecedented scope. As a result, there has
been a significant modification of waste management practices. The more traditional
and lowest-cost methods of direct landfilling, storage in surface impoundments and
deep-well injection are being replaced in large measure by waste minimization at
the source of generation, waste reuse, physical/chemical/biological treatment, in-
cineration and chemical stabilization/solidification methods. Of all of the "perma-
nent" treatment technologies, properly designed incineration systems are capable
i of the highest overall degree of destruction and control for the broadest range of
hazardous waste streams. Substantial design and operational experience exists in
this area and a wide variety of commercial systems are available. Consequently,
significant growth is anticipated in the use of incineration and other thermal destruc-
tion methods. The objective of this review is to examine the current state of knowl-
edge regarding hazardous waste incineration in an effort to put these technological
and environmental issues into perspective.
Hazardous waste management and
remediation of Superfund sites was the
environmental issue of the 1980s and
will likely continue to be so during the
1990s. Discovery of numerous envi-
ronmental catastrophes resulting from
improper disposal practices in the past
has elevated public awareness and
concern. Over the last 15 years, this
concern has manifested itself in the
passage of a series of federal and state-
! level hazardous waste management and
cleanup and control statutes of unprec-
edented scope and impact. At the fed-
eral level, these laws include the
Resource Conservation and Recovery
Act of 1976 (RCRA) and its subse-
quent amendments with its "cradle to
grave" provisions for controlling the
storage, transport, treatment and dis-
posal of hazardous waste. In 1979 the
polychlorinated biphenyl (PCB) regu-
lations, promulgated under Section 6(e)
of the Toxic Substances Control Act
(TSCA), prohibited the further manu-
facture of PCBs after July 2, 1979. This
established limits on PCB use in com-
merce and established regulations for
proper treatment and disposal. Cleanup
of uncontrolled waste sites created by
past poor disposal practices was pro-
vided for in the Comprehensive Envi-
ronmental Response, Compensation and
Liability Act (CERCLA) of 1980. This
act established a national fund (Super-
fund) to assist in remedial actions. The
1986 Superfund Amendments and
Reauthorization Act (SARA) not only
reauthorized the Superfund program but
greatly expanded the provisions and
funding of the initial act. In addition,
it established a clear preference for re-
mediation technologies that would
"permanently" and significantly re-
duce the volume, toxicity, or mobility
of hazardous substances, pollutants and
contaminants.
One of the more significant of these
statutes was the 1984 amendments and
reauthorization of RCRA. Termed the
Hazardous and Solid Waste Act
(HSWA) of 1984, these amendments
established a strict time line for re-
stricting untreated hazardous waste from
land disposal. The U.S. Environmen-
tal Protection Agency (EPA) promul-
gated the last of five Congressionally-
mandated prohibitions on land dis-
posal of hazardous wastes (the third
one-third of the schedule of restricted
hazardous wastes) on June 1, 1990.
When fully effective in May 1992, this
rule, combined with the previous rule-
makings, is expected to require the ad-
ditional treatment of 7 million tons per
year of hazardous waste to levels
achievable by the Best Demonstrated
Available Technology (BDAT) before
it can be land disposed.1
These various statutes will continue
to drive a significant modification of
waste management practices. The more
traditional and lowest-cost methods of
direct landfilling, storage in surface
impoundments and deep-well injection
are being replaced, in large measure,
by waste minimization at the source of
generation, waste reuse, physical/
chemical/biological treatment, incin-
eration and chemical stabilization/so-
lidification methods.
Of all of the "permanent" treat-
ment technologies, properly designed
incineration systems are capable of the
highest overall degree of destruction
and control for the broadest range of
hazardous waste streams. Substantial
design and operational experience ex-
ists in these areas and a wide variety
of commercial systems are available.
Consequently, significant growth is
anticipated in the use of incineration
and other thermal destruction meth-
ods.2
While thermal destruction offers
many advantages over alternative haz-
ardous waste treatment practices and
may help meet the anticipated need for
increased waste management capacity,
public opposition to the permitting and/
or use of thermal destruction opera-
tions has been strong in recent years.3'
7 The environmental awareness and ac-
tivism which spawned the major haz-
ardous waste laws of the 1980s have,
in many respects, switched to skepti-
cism over the safety and effectiveness
of the technological solutions which the
AIR & WASTE • Vol. 43 • January 1993 • 25
G-2
-------
laws were designed to regulate. Citi-
zen distrust of the waste management
facility owners and operators remains
strong. The ability of government
agencies to enforce compliance is also
questioned. Reports of trace quantities
of chlorinated dioxins, chlorinated fur-
ans and other combustion byproducts
in the stack emissions of municipal solid
waste and PCB incinerators have raised
questions in the minds of some con-
cerning whether the RCRA and other
incinerator standards are sufficient to
protect public health and the environ-
ment. Yet, faced with the specter of
complying with the HSWA land dis-
posal restrictions or the prospect of fu-
ture multimillion dollar environmental
damage settlements over contaminated
groundwater, waste generators are
looking to permanent destruction tech-
niques such as incineration as the pre-
ferred alternative.
The objective of this review is to
examine the current state of knowl-
edge regarding hazardous waste incin-
eration in an effort to put these
technological and environmental is-
sues into perspective. In doing so, it
will be important to review:
• Current and emerging regula-
tions and standards for incinera-
tors, industrial boilers and
furnaces burning hazardous waste
• Current incineration technology
and practice
• Capabilities and limitations of
methods for measuring process
performance
• Destruction efficiency and emis-
sions characterization of current
technology
• Methods for predicting and as-
suring incinerator performance
• Environmental and public health
implications of hazardous waste
incineration
• Remaining issues and research
needs
While the focus of this paper is on
hazardous waste incineration, it is im-
portant to understand that many of the
same issues relate to the use of haz-
ardous waste as a fuel in industrial
boilers and furnaces as well as munic-
ipal waste and medical waste inciner-
ation. Where possible and appropriate,
the performance and emissions of these
systems will be compared and con-
trasted with hazardous waste inciner-
ators.
Background
Historical Perspective
Purification by fire is an ancient
concept. Its applications are noted in
26 • January 1993 • Vol. 43 • AIR &
the earliest chapters of recorded his-
tory. The Hebrew word for hell, Geh-
enna, was actually derived from the
ancient phrase gc-bcn Hinnom or the
valley of the son of Hinnom, an area
outside of Jerusalem which housed the
smoldering town dump and was the site
of propitiatory sacrifices to Moloch ll.8
Today, waste fires on the ground or in
pits are still used throughout the world,
including the United States. This in-
cludes open burning of agricultural
waste as well as the burning of house-
hold refuse in some rural areas.
In the Middle Ages, an early waste
fire innovation was the "fire wagon,"
the first mobile incinerator.9 It was a
simple rectangular wooden wagon pro-
tected by a clay lining. The horse-drawn
wagon traveled the streets and resi-
dents threw their refuse into the mov-
ing bonfire.
Incineration as we know it today
began slightly over 100 years ago when
the first municipal waste "destructor"
was installed in Nottingham, En-
gland.9 Incineration use in the United
States grew rapidly, from the first in-
stallation on Governor's Island in New
York to more than 200 units in 1921.
Most of these were poorly operated
batch-fed units, some with steam re-
covery. Until the 1950s, incinerators
and their attendant smoke and odors
were accepted as a necessary evil and
their operations were generally under-
taken in the cheapest possible manner.
However, as billowing smoke stacks
became less of a symbol of prosperity
and air pollution regulations began to
emerge, incineration systems im-
proved dramatically.10 These improve-
ments included continuous feed,
improved combustion control, the use
of multiple combustion chambers, de-
signs for energy recovery, and the ap-
plication of air pollution control
systems."
Incineration has been employed for
the disposal of industrial chemical
wastes (hazardous waste) for over 50
years. Initial units borrowed from mu-
nicipal waste technology, but poor
performance and adaptability of these
early grate-type units led to the sub-
sequent use of rotary kilns. Many of
the earliest rotary kiln facilities were
in West Germany. llie first rotary kiln
unit for industrial wastes in the United
States was installed in 1948 at the Dow
Chemical Company facility in Mid-
land, Michigan.12
Regulations
The first U.S. federal standards for
the control of incineration emissions
were applied to municipal waste com-
bustors under the New Source Per-
formance Standards (NSPS) provisions
of the Clean Air Act (CAA) of 1970.
The NSPS established a time-averaged
(two hours) particulate emission limit
of 180 milligrams per dry standard cu-
bic meter (mg/dscm), corrected to 12
percent carbon dioxide (C02), for all
incineration units constructed after
August 1971 having charging rates
greater than 50 tons per day (tpd). On
February 11, 1991, the U.S. EPA pro-
mulgated more stringent rules for all
existing and new municipal waste
combustors (MWCs) with unit capac-
ities greater than 225 metric tons per
day (Mg/day).'1 This action required
the use of good combustion practice
(GCP) at all facilities, set lower par-
ticulate emissions limits to control
metals and established emission limits
on nitrogen oxides (NOx), organics,
hydrogen chloride (HC1), sulfur diox-
ide (S02) and opacity. The specific
limits are a function of the combustion
technology used and the facility's size
(capacity) and age (new or existing).
The February 1991 rules for GCPs and
emission limits are summarized in Ta-
ble I.
The February 1991 MWC rules arc
to be modified in the near future to
comply with the provisions of the No-
vember 1990 CAA Amendments. These
revisions will include: (1) rules for fa-
cilities with capacities less than 225
Mg/day, (2) emission limits for cad-
mium, lead and mercury, and (3) re-
quirements for the use of the maximum
achievable control technology
(MACT).14
Hazardous waste incineration per-
formance standards were not promul-
gated until after the passage of RCRA.
Technical standards for incinerators
were proposed in December 1978, un-
der Section 3004 of RCRA.15 Tliese
standards provided both performance
and operating requirements. The per-
formance standards included require-
ments for acceptable levels of
combustion efficiency, destruction ef-
ficiency for organic compounds, HG
removal efficiency and an emission limit
for particulate matter. Operational
standards required semicontinuous
monitoring of process variables, such
as carbon monoxide (CO), and spe-
cific minimum temperature and com-
bustion gas residence time levels.
During the allowable comment period
on the proposed rules, EPA received
extensive comments on the scope of
the standards and the adequacy of the
combined EPA and industrial data base
used to set the standards.
G-3
-------
Table I. Municipal waste combustor emission standards and guidelines.'3
EMISSION GUIDELINES-
DESCRIPTION
Capacity (Mg/day)
NSPS*'
>225
>225 to 1,000
>1,000
Opacity (%)
10
10
10
Metal Emissions
34
69
34
(As particulate matter,
mg/dscm)
Organic Emissions
30
125
60
(As total PCDD/PCDF,
or 250°
ng/dscm)
NOx (ppmv)
180
none
none
HC1 (% Reduction/ppmv)
95/25
50/25
90/25
S02 (% Reduction/ppmv)
80/30
50/30
70/30
CO (ppmv)d
50-150
50-250
50-250
¦ All emission limits are based on standard dry gas corrected to 7% 02.
b NSPS = New Source Performance Standard.
c Applies only to refuse-derived fuel (RDF) stokers and coal/RDF mixed fuel-fired com-
bustors.
d CO emission limits depend on the type of MWC technology. GCP requirements also
contain limitations on maximum steam load and temperature at the particulate control
device inlet.
Based upon the public comment,
EPA subsequently proceeded down a
three-phased regulatory path:
• Phase I (May 19, 1980). Interim
status standards were proposed
outlining operating procedures to
be followed by existing inciner-
ator facilities.'6
• Phase II (January 23, 1981). In-
terim final performance stan-
dards were promulgated requiring
specific levels of organic hazard-
ous constituent destruction and
removal, exhaust gas HC1 re-
moval and maximum particulate
emission concentration.17
• Phase III (June 24, 1982). The
interim final standards were
amended based on public com-
ment received on the standards
that were promulgated on Janu-
ary 23, 1981 and remain in force
at this time.18
The provisions of the final inciner-
ator standards, which are of greatest
importance to this paper, are the per-
formance standards which are now listed
in the Code of Federal Regulations
(CFR) under 40 CFR 264.343. These
standards require that in order to re-
ceive a RCRA permit, a facility must
attain the following performance lev-
els:
(1) A 99.99 percent destruction and
removal efficiency (DRE) for
each principal organic hazard-
ous constituent (POHC) in the
waste feed where:
DRE = [(Win - Wout)/Wjn] x 100
where: Win = mass feed rate of the
principal organic hazardous
constituent (POHC) in the
waste stream fed to the in-
cinerator, and
Woll, = mass emission rate
of the POHC in the stack
prior to release to the at-
mosphere.
(2) HC1 emissions no greater than
the larger of either 1.8 kilo-
grams per hour or 1 percent of
the HC1 in the stack gas prior
to entering any pollution con-
trol equipment (i.e., 99 percent
removal).
(3) Particulate matter emissions no
greater than 180 mg/dscm [0.08
grains per dry standard cubic
foot (dscf)] corrected to 7 per-
cent oxygen in the stack gas.
The measured particulate mat-
ter concentration is multiplied
by the following correction fac-
tor to obtain the corrected par-
ticulate matter emissions:
Correction Factor = 14/(21 - Y)
where: Y = measured oxygen con-
centration in the stack gas
on a dry basis (expressed as
a percentage).
The concept and selection of POHCs
is an important part of the incineration
regulations. POHCs, which are to be
sampled during "trial bums" to assess
attainment of the standards, are to be
selected from the organic group of the
RCRA Appendix VIII list of hazard-
ous constituents present in the wastes.17
Appendix VIII is a list of approxi-
mately 400 organic and inorganic haz-
ardous chemicals first published in Part
261 of the May 19, 1980 Federal Reg-
ister.16 This list is updated semian-
nually in 40 CFR 261.
POHC selection is covered by 40
CFR 264.342(b) which suggests that
Appendix VIII constituents, which are
in the highest concentration in the waste
feed and are the most difficult to in-
cinerate, are the most appropriate to be
selected as POHCs. Supplementary
guidance has also been issued.19-20 This
selection approach, particularly the
concept of hazardous compound inci-
nerability and selection of surrogate
POHCs, has been the subject of con-
siderable scientific debate. These is-
sues will be examined in greater detail
later.
On April 27, 1990, the EPA pro-
posed to amend the hazardous waste
incinerator regulations to control the
toxic metal and free chloride emissions
and improve HC1 emissions and resid-
ual organic emissions standards.21 In
addition, these amendments would have
allowed POHCs to be selected that were
not in the normal waste feed or on the
RCRA Appendix VIII list if they were
demonstrated to be suitable indicators
of DRE performance. These amend-
ments would have essentially applied
the same approach to hazardous waste
incinerators that has since been pro-
mulgated for the control of such emis-
sions from boilers and industrial
furnaces (BIFs) burning hazardous
waste (discussed later). In essence,
much of this has already been imple-
mented by EPA permit writers under
the "omnibus" authority of HSWA and
codified in 40 CFR 270.32 which states,
"Each permit issued under section 3005
of this act shall contain terms and con-
ditions as the Administrator or State
Director determines necessary to pro-
tect human health and the environ-
ment."
It is important to note that in 1980,
EPA chose not to apply the incinera-
tion standards to the burning of haz-
ardous waste as a fuel in industrial
boilers and furnaces.16 This exemption
was based upon a lack of sufficient in-
formation on the practice and the fact
that energy recovery constituted a ben-
eficial use of wastes. Considerable data
have been assembled since the exemp-
tion was granted in 1980.
To ensure that low-heating-value
hazardous waste was not burned in a
boiler or industrial furnace, ostensibly
for energy recovery but actually to avoid
the cost or regulation of incineration,
AIR & WASTE • Vol. 43 • January 1993 • 27
G-4
-------
the EPA developed a "sham recy-
cling" policy in 1983.22 That policy
held that if a hazardous waste having
less than 5,000 to 8,000 Btu/lb heating
value were burned in a boiler or in-
dustrial furnace, it was not burned for
its fuel value but rather to avoid the
cost (or regulation) of incineration. With
the promulgation of the BIF nilc, all
BIFs burning hazardous wastes must
now meet the new treatment standards
(discussed later). Because of this the
"sham recycling" policy is being
phased out.
On January 4, 1985, EPA revised
its rules to state that listed hazardous
wastes and sludges arc subject to trans-
portation and storage controls prior to
their being burned as fuels in boilers
and industrial furnaces and prior to their
processing or blending to produce a
waste-derived fuel.23 On November 29,
1985, EPA promulgated administra-
tive controls for marketers and burners
of hazardous waste fuels that regulated
the transportation and storage of any
hazardous waste used as a fuel or used
to produce a fuel.24 It also prohibited
the burning of hazardous waste fuel in
nonindustrial boilers, unless the boiler
complied with the standards for haz-
ardous waste incinerators.
On May 6,1987, the EPA proposed
regulations to control the emissions
from boilers and industrial furnaces
burning hazardous waste.21 The Agency
published a supplement to this pro-
posed rule on October 26, 1989, which
requested comment on alternate ap-
proaches to addressing issues concern-
ing the control of CO, metals, HQ,
particulates and other related issues.26
The Final rule was promulgated on
February 21, 1991 and became effec-
tive August 21, 1991,27 and technical
amendments to the final rule were pub-
lished on August 27, 1991.28 These
regulations control emissions of toxic
organic compounds, toxic metals, hy-
drogen chloride, chlorine gas and par-
ticulate matter from boilers and
industrial furnaces burning hazardous
waste. In addition, this rule subjects
owners and operators of these devices
to the general facility standards appli-
cable to hazardous waste treatment,
storage and disposal facilities. An in-
novative feature of this BIF rule is that
it includes substantive interim status
standards which are self-implemented
by industry. By August 21, 1992, the
facilities were required to conduct a
compliance test and provide certifica-
tion that they were meeting the BIF
performance standards. Thus, existing
BIF facilities will be operating under
emissions standards and other controls
even before they are permitted. How-
ever, there are differences between the
interim standards and controls and the
requirements for permitted facilities.
EPA will require the permittee to con-
duct the RCRA trial bum in due course
to ensure compliance with standards
given below.
Toxic organic compound emissions
are controlled by requiring boilers and
industrial furnaces to comply with the
same DRE standard currently appli-
cable to hazardous waste incinerators:
99.9999 percent DRE for dioxin-listed
waste (EPA Hazardous Waste Nos.
F020, F021, F022, F023, F026 or F027)
and 99.99 percent DRE for all other
hazardous wastes. Compliance with the
DRE standard must be demonstrated
during a trial burn for each selected
POHC. However, facilities may be ex-
empt from the trial burn requirements
depending upon the type and quantity
of waste burned, the type of facility,
and operating conditions. As with haz-
ardous waste incinerators, POHCs are
to be selected based on the degree of
difficulty of destruction of the organic
constituents in the waste and on their
concentrations or mass in the waste
feed. In most cases, it is believed that
these POHCs will be selected from or-
ganic compounds contained on the
RCRA Appendix VIII list of hazard-
ous constituents. The applicants have
the option, however, of proposing
compounds that are not in the normal
waste feed or not on the RCRA Ap-
pendix VIII list if they can demon-
strate that those compounds are suitable
indicators of DRE performance. Such
POHCs need not be toxic or organic
compounds. POHC selection will be
discussed further under the section la-
beled "Surrogates."
Products of incomplete combustion
(PICs) are controlled by setting limits
on parameters that will assure that the
device is operated under good com-
bustion conditions. This is accom-
plished by either limiting the hourly
rolling average concentration of the flue
gas concentration of CO to 100 parts
per million by volume (ppmv), based
on standard dry gas corrected to 7 per-
cent oxygen (Tier 1), or limiting hy-
drocarbon (HC) emissions to a
maximum of 20 ppmv (Tier II). Fur-
naces that cannot meet the HC limit
because of organic matter in the raw
material may establish a higher HC limit
by conducting site-specific sampling
and analysis and dispersion modeling
to demonstrate that annual average
ground level concentrations of specific
organic compounds do not exceed
specified levels for noncarcinogens and
do not pose high risks to the maximum
exposed individual (ME1) for carcin-
ogenic compounds. As a part of this
analysis, they must also determine the
baseline HC contents in the raw ma-
terial.
Owners and operators of hazardous
waste-burning boilers and industrial
furnaces equipped with a dry particu-
late matter control device that operates
within the range of 450 to 750°F and
furnaces operating under an alternate
HC limit must conduct site-specific risk
assessments. The assessments are re-
quired to demonstrate that emissions
of chlorinated dibenzo-p-dioxins and
dibenzofurans do not result in an in-
creased lifetime cancer risk to the MF,I
greater than one in 100,000.
Emission limits based on projected
inhalation health risks to a hypotheti-
cal MEI have been established for 10
toxic metals which are listed in Table
II along with their corresponding unit
risk (for carcinogens) or reference air
concentration (RAC) (for noncarcino-
gens) values. RACs for nickel and se-
lenium have been included as well since
it is anticipated that these metals will
also be regulated in the near future.
Limits for the carcinogenic metals arc
established so that the incremental
cancer risk to the MEI is not greater
than one in 100,000. These risk as-
sessments are calculated by utilizing
dispersion modeling and the unit risk
estimates prepared by EPA's Carcin-
ogen Assessment Group (CAG). Unit
risk is defined as the incremental can-
cer risk to an individual exposed for a
lifetime (70 years) to ambient air con-
taining one microgram of the com-
pound per cubic meter (fig/m3) of air.29
The limits for the noncarcinogenic
metals are based on Reference Doses
(RfDs) below which adverse health ef-
fects have not been observed. Based
on assumptions concerning body
weight, volume of air breathed, back-
ground levels of the metals from other
sources, and the relationship between
the oral and inhalation routes of ex-
posure, the RfDs have been used to
calculate maximum RACs attributable
to noncarcinogenic metal emissions
from BIFs. EPA has apportioned 75
percent of the RfD to other nonspeci-
fied sources, so the calculated RAC is
based on only 25 percent of the RfD.
The RAC for lead is set at 10 percent
of the national ambient air quality
standard. This data and dispersion
modeling are then used to back-cal-
culate acceptable emissions.
The metals standards are imple-
mented through a three-tiered ap-
proach and compliance with any tier is
28 • January 1993 • Vol. 43 • AIR & WASTE
I
G-5
-------
acceptable. The tiers are structured to
allow higher emission rates (and feed
rates) as the owner or operator elects
to conduct more site-specific testing and
analysis. Under Tier 1, it is assumed
that all metals fed to the device are
emitted. The EPA has developed ta-
bles specifying waste feed rate limits
for each metal as a function of effec-
tive stack height, terrain and land use
in the vicinity of the stack assuming
reasonable, worst-case dispersion
scenarios.
Under Tier II, the owner or operator
conducts emission testing to determine
the percentage of metals fed that are
actually emitted due to partitioning to
the bottom ash or to kiln "product"
(in the case of cement kilns, for ex-
ample) and the amount removed by the
air pollution control device (APCD).
The same tables that were developed
for Tier I are used but they now rep-
resent metal emission rates instead of
metal feed rates.
Under Tier III, the owner or oper-
ator conducts metal emissions testing
to determine the emission rate for each
metal and air dispersion modeling to
predict the maximum annual average
off-site ground level concentration for
each metal to demonstrate that accept-
able ambient levels are not exceeded.
The emission of HC1 and free chlor-
ine (Cl2) are controlled under a three-
tiered approach similar to that used for
metals and their RACs are given in Ta-
ble 11. The limit for particulate matter
is 180 mg/dscm corrected to 7 percent
oxygen, the same as the hazardous
waste incinerator standard.
EPA has also promulgated regula-
tions for the incineration of specific
wastes. Incineration of PCBs at con-
centrations of 50 parts per million (ppm)
and greater is controlled under TSCA
rules, which were initially promul-
gated in May 1979, and are codified
in 40 CFR 761.30 These rules stipulate
that incineration is an acceptable treat-
ment technology. Other disposal alter-
natives are permitted depending upon
the PCB concentrations and waste
characteristics. The principal perform-
ance standards and operating condi-
tions that incinerators burning PCBs
must meet depends upon whether the
waste is a liquid or nonliquid. For liq-
uid waste, the following applies:
(1) The combustion chamber gas
residence time must be at least
2 seconds at l,200oC ( + /-
100°C) with a minimum of 3
percent excess oxygen in the
stack gas; or
The combustion chamber gas
residence time must be at least
1.5 seconds at l,600oC ( + /-
100°C) with a minimum of 2
percent excess oxygen in the
stack gas.
(2) Combustion efficiency (CE)
shall be at least 99.9 percent
computed as follows:
^ _ Percent C02
Percent C02 + Percent CO
x 100
Incinerators burning nonliquid PCB
wastes must comply with the follow-
ing:
(1) The mass emissions from the
incinerator shall be no greater
than 0.001 gram (g) PCB per
kilogram (kg) of the PCB intro-
duced into the incinerator (which
is the same as a DRE of at least
99.9999 percent for the PCBs).
(2) The CE shall be at least 99.9
percent.
The incineration of wastes contain-
ing certain chlorinated dibenzo-p-
dioxins, chlorinated dibenzofurans and
chlorinated phenols is regulated under
RCRA rules promulgated January 14,
1985.31 This so-called "dioxin rule"
limits the incineration of these specific
wastes (EPA waste codes F020, F021,
F022, F023, F026 or F027), summa-
rized in Table III, to incinerators which
have demonstrated the ability to achieve
at least 99.9999 percent DRE for
chlorinated dioxins or similar com-
pounds during the trial burn.
Current Incineration Practice
Incineration Practice
Incineration is an engineered process
that employs thermal decomposition via
thermal oxidation at high temperature
(usually 900oC or greater) to destroy
the organic fraction of the waste and
reduce volume. Generally, combusti-
ble wastes or wastes with significant
organic content are considered most
appropriate for incineration. Techni-
cally, however, any waste with a haz-
ardous organic fraction, no matter how
small, is at least a functional candidate
for incineration. For instance, signifi-
cant amounts of contaminated water
were being incinerated in the United
States during the early 1980s.32 Con-
taminated soils are also being incin-
erated with increasing frequency. EPA,
for example, has employed a mobile
incinerator to decontaminate 40 tons of
Missouri soil which had been contam-
inated with four pounds of chlorinated
dioxin compounds.33"36
Following this successful demon-
stration of mobile incineration, many
Table II. Summary of toxic metals, HC1 and CL, regulated for boilers and industrial
furnaces burning hazardous wastes.27
CARCINOGENIC NON-CARCINOGENIC
Maximum
Unit Risk Permissible Air
[Cancers/
Concentrations
RAC"
Metal
(M-g/m3)]
(M-g/m3)*
Metal
(ng/m3)
Cadmium
0.0018
0.0056
Barium
50.00
Beryllium
0.0024
0.0042
Nickel'
20.00
Arsenic
0.0043
0.0023
HC1
7.00
Chromium'1
0.0120
0.00083
Selenium'
4.00
Silver
3.00
Thallium
0.50
Cl2
0.40
Antimony
0.30
Lead
0.09
Mercury
.08*
' These air concentrations apply only if emitted alone and no other carcinogenic metal is
emitted. As a practical matter, allowable limits will be even lower, due to the presence
of other carcinogens.
b RAC = reference air concentration.
c Values for nickel and selenium have been included as it is anticipated these metals will
be regulated in the future.
11 Chromium Unit Risk is for Chromium VI (i.e., Cr*').
' The RAC for mercury has recently been reduced from 0.30 to 0.08 |ig/m5. The Agency
will use the "omnibus" authority of 40 CFR 270.32 to use revised RACs where the
facts warrant.
AIR & WASTE • Vol. 43 • January 1993 • 29
-------
Table III. Summary of specific dioxin-containing wastes thai, if incinerated, mus! be treated in an incinerator certified capable of
achieving a DRE of at least 99.9999%."
EPA Hazardous
Waste Number Description
F020 Wastes (except wastewater and spent carbon from hydrogen chloride purification) from the production or
manufacturing use (as a reactant, chemical intermediate, or component in a formulating process) of tri- or
tetrachlorophenol, or of intermediates used to produce their pesticide derivatives. (This listing does not include
wastes from the production of Hexachlorophene from highly purified 2,4,5-trichlorophenol.)
F021 Wastes (except wastewater and spent carbon from hydrogen chloride purification) from the production or
manufacturing use (as a reactant, chemical intermediate, or component in a formulating process) of pentach-
lorophenol, or of intermediates used to produce its derivatives.
F022 Wastes (except wastewater and spent carbon from hydrogen chloride purification) from the manufacturing use
(as a reactant, chemical intermediate, or component in a formulating process) of tetra-, penta-, or hexachlo-
robenzenes under alkaline conditions.
F023 Wastes (except wastewater and spent carbon from hydrogen chloride purification) from the production of
materials on equipment previously used for the production or manufacturing use (as a reactant, chemical
intermediate, or component in a formulating process) of tri- and tetrachlorophenols. (This listing does not
include wastes from equipment used only for the production or use of Hexachlorophene from highly purified
2,4,5-trichlorophcnol.)
F026 Wastes (except wastewater and spent carbon from hydrogen chloride purification) from the production of
materials on equipment previously used for the manufacturing use (as a reactant, chemical intermediate, or
component in a formulating process) of tetra-, penta-, or hexachlorobenzcne under alkaline conditions.
F027 Discarded unused formulations containing tri-, tetra-, or pentachlorophenol or discarded unused formulations
containing compounds derived from these chlorophenols. (This listing does not include formulations containing
Hexachlorophene synthesized from prepurified 2,4,5-trichlorophenol as the sole component.)
companies have built mobile or trans-
portable incinerators that are actively
employed in the remediation of Super-
fund sites. Some of these arc scaled-
down, trailer-mounted versions of
conventional rotary kiln or fluidized bed
incinerators with thermal capacities of
10 to 20 million British thermal units
per hour (Btu/h). However, transport-
able units as large as 120 million Btu/
h are also available. Overall, the per-
formance of these mobile systems has
been shown to be comparable to equiv-
alent stationary facilities.34-35 One ad-
vantage of mobile systems is that they
may be more generally socio-politi-
cally acceptable than removal and
transportation of cleanup residues to
commercial facilities. This may not be
true, however, for people living near
the site. In the instance of soil decon-
tamination, on-site incineration is
commonly more cost-effective than
transportation of large amounts of con-
taminated material to central inciner-
ation facilities.
While the exact number of available
mobile and transportable units is
somewhat dynamic, a 1990 analysis37
provides a good characterization of this
sector of incinerators. At that time, it
was reported that 15 companies were
operating 30 units which were com-
prised of 22 rotary kilns, four infrared
conveyors and four circulating beds. A
more recent survey38 showed that as of
March 1992, mobile and transportable
incinerators were in various stages of
remediating 2,139,700 tons of con-
taminated soil at 56 sites which are
summarized in Table IV. It should be
noted that the sites summarized in Ta-
ble IV include CERCLA-Superfund,
RCRA corrective action, RCRA clo-
sure, real estate transfer and spill
cleanup sites. It does not include un-
derground storage tank (UST) sites. As
we continue to remediate the balance
of the nation's Superfund sites, the use
of mobile/transportable incinerators will
likely continue to increase as Records
of Decision (RODs) arc frequently
based on thermal treatment technolo-
gies.
Since the promulgation of the RCRA
interim status incinerator standards in
1980, a number of surveys and studies
have been conducted to assess the
quantity and types of hazardous waste
generated in the United States, as well
as the quantities and types of wastes
being managed by various treatment,
storage and disposal facilities. Many
of these were conducted during the
early- to mid-1980s3'"46 and efforts have
continued47 to refine and update this
information.
Perhaps the most up-to-date and
comprehensive data available on the
generation and management of hazard-
ous waste are contained in the State
Capacity Assurance Plans (CAPs).
SARA required each state to submit a
CAP by October 17, 1989 to EPA
demonstrating that it had sufficient in-
state capacity or had secured sufficient
capacity in other states for managing
its hazardous waste. As a part of this
plan, each state was required to pro-
vide information on hazardous waste
generation and management within the
state for 1987, 1989, 1995 and 2009.
The only year for which amounts arc
based on actual waste management in
these plans is 1987. All other years are
projections.
Table IV. Summaiy of mobile/transportable indneratou; remediating Superfund and other
contaminated soils as of March 1992."
DESCRIPTION
SITES
QUANTITY OF CONTAMINATED
SOIL ( l'ONS)
Finished
32
452,200
On-Going
12
845,500
Contracted
12
842,000
Totals
56
2,139,700
Note: Underground storage tank (UST) cleanups are not included.
30 • January 1993 • Vol. 43 • AIR & WASTE
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A review of these various studies
has sometimes revealed significant dif-
ferences in what would seem to be rel-
atively straightforward statistics. While
frustrating to those in government and
industry who evaluate waste manage-
ment alternatives and economic im-
pacts, these deficiencies in the data base
are not surprising. They have resulted
from many factors, such as changes
and uncertainties in regulatory defini-
tions of hazardous waste terms, differ-
ences in methods and assumptions
employed in the various surveys, and
incomplete or inaccurate responses by
facility owners and operators. Contin-
uing changes in waste generation rates,
the number and permit status of facil-
ities which have occurred in response
to regulatory changes, and economic
factors have also made it difficult to
accurately project trends in waste man-
agement practice from one point in time
to another.
One of the most important factors,
however, that has contributed to dif-
ferences among these estimates is the
varying manner in which "exempt
waste" has been treated. Waste that
otherwise would be defined as hazard-
ous is exempt from RCRA hazardous
waste regulations when treated in
wastewater treatment plants regulated
under the Clean Water Act. Approxi-
mately 97 percent (when exempt waste
is included) of the hazardous generated
in the United States is wastewater48 and
much of this is treated in exempt fa-
cilities. One analysis of the CAPs49 il-
lustrates the impact this can have.
Eighteen states included some exempt
waste in their estimates of hazardous
waste generated in 1987. If this ex-
empt waste had not been included, the
total reported for the United States
would have been over 40 percent less.
In spite of these deficiencies and
limitations, it is possible to construct
a reasonable picture of hazardous waste
generation and incineration practice
from the aggregate of the studies. To-
tal annual hazardous waste generation
in the United States was first projected
by EPA to be approximately 265 mil-
lion metric tons (MMT) for 1981 in the
so-called Westat mail survey.43 This
was later corroborated in separate
studies by the Congressional Budget
Office (CBO)44 and the Congressional
Office of Technology Assessment
(OTA).45 EPA estimated 216 MMT
were generated in 198747 and the CAPs
reported that 249.3 MMT were gen-
erated for this same period.49 How-
ever, 101.4 MMT of this was exempt
waste leaving a balance of 147.9 MMT
of non-exempt hazardous waste.
Only a small fraction of this waste
(< 1 percent) was believed to have been
incinerated. EPA estimated that 1.7
MMT was treated in incinerators dur-
ing 1981.43 The CBO projected this
amount at 2.7 MMT for 1983.44 EPA
estimated that 1.0 MMT were treated
at 227 incinerator sites (310 estimated
units) during 1987.21 EPA has also es-
timated that approximately 1.0 MMT
were burned in industrial furnaces27
while Holloway50 estimated that 1.0
MMT were burned in industrial boilers
per year during the late 1980s. These
quantities are in reasonable agreement
with the estimates in the CAPs which
are summarized in Table V by SARA
management category for non-exempt
hazardous waste for 1987. The CAPs
estimated that 1.3 MMT of hazardous
waste were incinerated and 1.2 MMT
were burned in BIFs during 1987.
The principal attractions to burning
hazardous waste in industrial boilers
and furnaces include previous exemp-
tion from RCRA incineration stan-
dards, projected fuel and waste
transportation cost savings, and ex-
pected waste disposal cost savings since
hazardous waste used as a fuel could
be sold (i.e., it had an economic fuel
value).
SARA
Management
Category
Recovery:
Metals
Solvents
Other
Total Recovery
Thermal Processes:
Incineration/Liquids
Incineration/Solids
Energy Recovery
Total Thermal
Treatment:
Aqueous Inorganic
Aqueous Organic
Other Treatment
Sludge Treatment
Stabilization
Total Treatment
Disposal:
Land Treatment
Landfill
Deep Well Injection
Other Disposal
Total Disposal
Total Non-Exempt
Hazardous Waste
* MMT = millions of metric tons
One source of information on waste
fuel use in industrial processes was
compiled for EPA in 1984.51 The study
synopsized results of a national ques-
tionnaire of waste fuel and waste oil
use in 1983. The study revealed that
there were over 1,300 facilities using
hazardous waste-derived fuels (HWDF),
accounting for a total of 230 million
gallons (0.9 MMT) per year. The
chemical industry Standard Industrial
Classification (SIC) 28 accounted for
67 percent of this while operating only
12.4 percent of the facilities using
HWDF. Other industries employing
significant quantities of hazardous waste
as fuel included SICs 26 (paper), 29
(petroleum), 32 (stone, clay, glass,
concrete), and 33 (primary metals). The
majority (69 percent) of the waste was
burned in large quantities by a few fa-
cilities representing only a small frac-
tion (1.6 percent) of the 1,300 facilities.
These included medium- to large-sized
industrial boilers, cement and aggre-
gate kilns, and iron-making furnaces.
While waste-code-specific data on
HWDF are not readily available, 1983
data indicate that of the HWDF burned,
30 percent was organic solvents and 45
percent was other hazardous organ-
ics.51 Most of this waste was generated
Percent
Quantity of
(MMT)" Total
0.4 0.2
0.9 0.6
0.1 0.1
1.4 0.9
1.1 0.8
0.2 0.1
1.2 0.8
2.5 1.7
16.8 11.4
36.7 24.8
58.8 39.7
0.4 0.3
0.6 0.4
113.3 76.6
0.4 0.3
3.3 2.3
26.8 18.1
0.2 0.1
30.7 20.8
147.9 100
Table V. Quantities of non-exempt hazardous wastes generated in the United States,
1987.49
AIR & WASTE • Vol. 43 • January 1993 • 31
G-8
-------
This public opposition has created
considerable uncertainty for waste
generators, equipment manufacturers
and commercial waste disposers. This
uncertainty plus more stringent regu-
lations are partially responsible for the
changes in the numbers of facilities and
companies that have remained in the
hazardous waste incineration business.
Between 1981 and 1987 for instance,
almost 100 incinerators withdrew from
the RCRA system; they either ceased
operation or decided to no longer han-
dle hazardous wastes.41 Of the 57
companies identified as marketing
hazardous waste incinerators in 1981,
23 had either gone out of business, left
the hazardous waste incinerator busi-
ness or put considerably less emphasis
on this activity by 1984.41 By Novem-
ber 8, 1989, (the Congressionally-
mandated statutory deadline for per-
mitting all hazardous waste incinera-
tors) an additional 55 incinerator sites
had announced that they would close,
120 incinerator sites had been permit-
ted and fifty-five incinerator sites were
allowed to continue operation (pend-
ing receipt of a permit) while they ad-
dressed deficiencies.5 By December
1991, there were approximately 150
permitted and operating incinerator fa-
cilities.60 In addition, an estimated 925
boilers were burning hazardous wastes
as fuel during 1991. Following the
promulgation of the "Burning of Haz-
ardous Waste in Boilers and Industrial
Furnaces; Final Rule"27 on February
21, 1991, it was expected that 200 of
these would stop burning hazardous
waste, 600 would continue to operate
under the small-quantity on-site burner
exemption (does not require permit) and
125 would continue to operate subject
to the interim status and permit stan-
dards of the rule. It was also estimated
that approximately 75 industrial fur-
naces would continue to burn hazard-
ous wastes. The regulated universe of
these furnaces were estimated to be
comprised of 40 cement kilns, 18 light-
weight aggregate kilns and 15 halogen
acid furnaces.27 It now appears, how-
ever, that a somewhat larger number
of cement kilns may wish to bum haz-
ardous waste. As of February 1992, 53
cement facilities had applied for in-
terim status under the B1F rule.61
The amount of public opposition to
proposed permits for incinerator facil-
ities varies by location and type of
waste. On-site facilities that directly
serve a single waste generator have
greater public acceptance than off-site,
commercial incinerators that serve
multiple generators in a large market
area. Off-site facilities are often not
discerned as providing sufficient eco-
nomic benefits to the local community
to offset the perceived risks associated
with the importation of wastes from
other areas. On-site facilities are more
clearly distinguished as being linked to
businesses that are important to the lo-
cal economy, and are generally not
perceived as being importers of haz-
ardous waste. Opposition has tended
to focus primarily on new off-site
commercial facilities and on new ap-
plications to bum PCBs, which critics
view as particularly hazardous.
In an effort to assess the dilemma
of perceived benefits versus public
concerns, EPA conducted an assess-
ment in 1985 to determine if there was
a need for a change in the approach
toward regulating thermal destruc-
tion.3 The major issues reported by cit-
izens included concern for;
• Hazardous material spills in stor-
age, treatment and handling
• Environmental and health im-
pacts
• Poor site selection processes
• Distrust of incinerator owners and
operators
• Inability of government agencies
to enforce compliance
The study concluded that public op-
position to incineration may decline
somewhat if regulators address more
fully some citizen concerns regarding
national regulatory strategy, local
community impact, equity of facility
siting, public decision-making
processes, and especially enforcement
plans and capacity. It was also con-
cluded that there is a need to better
communicate how health and environ-
mental concerns and priorities are re-
flected in regulations and standards.
Better communication of regulatory
Waate Preparation
Blinding
Screening
Shreddkig
Alomzafon
Ram
Gravty
Combustion
I
I I
Liquid mjeclton
Rotary K3n
ftred II—m
Air Pollution Control
Quench
Heat
Recovery
Venturi
w« es?*
IWS*
P*cfced Taw
Spray Tow
Trey To*
Preparation
'IWS * .or.krrg Wei Scftjbbftf
Oewaiertng
Chemical
St4bill«ttan
Secure Landfill
Neutralzation
Chemical Treatment
Rgure General orientation of incineration subsystems and typical process component options.
G-9
AIR & WASTE • Vol. 43 * January 1993-33
-------
on-site and 74 percent of the balance
arrived directly from an off-site gen-
erator rather than through an interme-
diary.
Precise information on the exact
types of wastes actually going to in-
cineration facilities is not readily avail-
able. Many facilities operate on an
intermittent basis and handle mixtures
of wastes which are difficult to de-
scribe in terms of EPA standard waste
codes. A 1983 EPA study examined
data on 413 waste streams going to 204
incineration facilities in the United
States.32 The major waste streams in-
cinerated were spent nonhalogenated
solvents (EPA waste code F003) and
corrosive and reactive wastes contam-
inated with organics (EPA waste codes
D002 and D003). Together, these ac-
counted for 44 percent of the waste
incinerated. Other prominent wastes
included hydrocyanic acid (P063),
acrylonitrile bottoms (KO11) and nonl-
isted ignitable wastes (D001). In a sep-
arate EPA analysis, 1981
information43 was utilized to charac-
terize the waste that was treated in in-
cinerators. It was found that the waste
was composed of almost 60 different
waste codes. Two waste codes - D001,
ignitable wastes; and X182, a mixture
of U008-acrylic acid, U112-ethyl ace-
tate, U113-ethyl acrylate and P003-ac-
rolein - accounted for 71 percent of the
waste. It was also estimated that ap-
proximately 44 percent of this waste
contained toxic metals and approxi-
mately 37 percent contained chlorine.
Behmanesh et al.i2 examined the
quantity and composition of RCRA
hazardous wastes incinerated during
1986 and determined the metal-to-hal-
ogen ratio of incinerated waste by SIC.
He found that the source of the waste
streams containing metals was very
much different from the bulk of incin-
erated wastes. In some cases only two
or three waste streams contained a sig-
nificant portion of the total metal load-
ing fed to the incinerator.
While only a small fraction of the
generated hazardous waste is currently
managed by incineration, several forces
will likely result in the increased use
of incineration. Implementation of the
HSWA land disposal restriction regu-
lations is expected to increase the
quantity of hazardous waste inciner-
ated. This will require an additional 7
million tons per year of hazardous waste
that was previously land disposed to
now be treated to levels achievable by
the BDAT before it can be land dis-
posed.1 The BDAT treatment levels for
many of the scheduled restricted haz-
ardous wastes were based on inciner-
ation. In addition, as generator concern
for long-term liability increases, incin-
eration will likely continue to become
more attractive. EPA has estimated that
nearly 8.5 MMT more hazardous wastes
could have been thermally destroyed
in incinerators and industrial furnaces
in 1981 than actually was.43 Numerous
other studies have indicated that the
actual use and demand for incineration
technologies to manage hazardous waste
will increase significantly.2-44-53"55 Also,
there has been a trend toward consid-
ering a broader spectrum of waste types
that are appropriate for incineration. As
the remediation of Superfund sites has
demonstrated, wastes contaminated with
only relatively low concentrations
(hundreds of ppm and lower for some
dioxin contaminated sites) of organics
and some levels of metals are being
treated by incineration. Therefore, a
much greater percentage of generated
hazardous waste may be managed by
incineration in the future.
It is clear that considerable potential
exists for expansion of incineration
practice. This assumes, however, that
sufficient RCRA- and/or TSCA-per-
mitted and mobile/transportable capac-
ity can be made available. This is, of
course, a significant issue and one
which has been given attention in a
number of studies.1-39^2 Gruber36 and
Highum57 have examined the existing
incineration capacity and found that
during 1987 there were 17 operating
commercial hazardous waste inciner-
ation facilities and 154 operating on-
site hazardous waste incineration fa-
cilities with a combined capacity of 4.3
MMT. This information is summa-
rized in Table VI. In addition, it has
been reported56'58 that a number of ef-
forts are under way to bring nonoper-
ating units on line, expand existing
capacity and build new facilities which
could significantly increase available
incineration capacity.
When compared with the quantities
of hazardous wastes currently being
inciner.ated, it would appear that the
necessary future capacity should be
available. This is somewhat mislead-
ing, however. First the capacity fig-
ures are, for the most part, maximum
capacity estimates and it is unlikely that
they could be realistically attained.
Highum57 estimated that actual capac-
ity would 30 to 50 percent less (2.2 to
3.0 MMT) than that showed in Table
VI. As mentioned earlier, it may be
desired to incinerate much greater
quantities of waste in the future. It is
highly unlikely that all of the nono-
perating and planned units will ac-
tually be brought on line. While national
waste capacity on a tonnage basis may
appear to be available, this does not
recognize the need for capacity by waste
type or location. For example, if much
of the available capacity is for liquid
waste, there may not be sufficient ca-
pacity for sludges and solids. Also, in-
cineration capacity for special wastes
such as explosives and mixed wastes,
may not be sufficient. Only 13 states
had operating commercial incinerators
in 1987.57
One of the major barriers to in-
creased incineration capacity is public
opposition to the permitting and siting
of new facilities, especially the off-site
commercial facilities which would be
necessary to handle much of the solids
and sludges which will increasingly re-
quire suitable disposal. Public oppo-
sition to the permitting of new
commercial thermal destruction oper-
ations has been very strong in recent
years. For example, Greenpeace claims
to have been instrumental in prevent-
ing the construction or permitting of
44 incinerators.4 The normal time re-
quired for permitting new commercial
incineration facilities is at least three
years and often much longer. This time
factor, and the expense of obtaining a
permit, may be greatly increased where
public opposition exists. The typical
length of time required to obtain a per-
mit for a new industrial incinerator to
be located at an existing industrial fa-
cility is one to two years.
Table VI. Summary of U.S. operating hazardous waste incinerator capacity, 1987.57
Description
Number
Capacity'
(MMT)
Commercial HWI Facilities
17"
0.9
On-site Incinerator
154
3.4
Facilities
Total
171
4.3
' Capacities as shown are likely maximum capacities. Actual capacities are estimated to
be 30% to 50% less.
b Includes four industrial furnace facilities that have been permitted as hazardous waste
incinerators.
32 • January 1993 • Vol. 43 • AIR & WASTE
G-10
-------
policy, strategy and other activities re-
lated to decisions on proposed permits
for individual incinerator facilities or
units is certainly desirable since im-
proved communication with the public
can enhance the credibility of regula-
tory and enforcement agencies.
Incineration Technology
I Different incineration technologies
: have been developed for handling the
various types and physical forms of
hazardous waste. The four most com-
mon incinerator designs are liquid in-
jection (sometimes combined with fume
incineration), rotary kiln, fixed hearth
and fluidized bed incinerators.
The process of selecting and de-
signing hazardous waste incineration
systems can be very complex. Fortu-
nately, considerable industrial manu-
facturing experience exists and many
useful design guides have been pub-
lished.11-62"65 Thus, while a detailed
examination of design principles is be-
yond the scope of this paper, a gen-
eralized review of the most prominent
features of incineration systems and
important design factors will be help-
ful in understanding a thermal destruc-
| tor's operation and emissions
! performance.
The four major subsystems which
may be incorporated into a hazardous
waste incineration system arc: (1) waste
preparation and feeding, (2) combus-
tion chamber(s), (3) air pollution con-
trol and (4) residue/ash handling. The
normal orientation of these subsystems
is shown in Figure 1, along with typ-
ical process component options. The
selection of the appropriate combina-
tion of these components is primarily
a function of the physical and chemical
properties of the waste stream or streams
to be incinerated.
(1) Waste Preparation and Feed-
ing. The physical form of the waste
determines the appropriate feed
: method." Liquids are blended, then
I pumped into the combustion chambers
through nozzles or via specially de-
signed atomizing burners. Wastes con-
taining suspended particles may need
to be screened to avoid clogging of
small nozzle or atomizer openings.
While sustained combustion is possi-
ble with waste heat content as low as
4,000 Btu/lb, liquid wastes arc typi-
cally blended to a net heat content of
8,000 Btu/lb or greater, if possible. To
incinerate lower heating value wastes,
supplementary fuel will normally be
required. Blending may be achieved by
either mixing the wastes before they
are fed to the combustion chamber or
by using separate nozzles for different
types of waste, wherein the mixing oc-
curs in the combustion chamber.
Blending is also used to control the
chlorine content of the waste fed to the
incinerator. Wastes with a chlorine
content of 70 percent and higher can
be incinerated in specially designed in-
cinerators.66 Blending provides better
combustion control and limits the po-
tential for periodic formation of high
concentrations of free-chlorine gas in
the combustion gases.
Sludges are typically fed using pro-
gressive cavity pumps and water cooled
lances. Bulk solid wastes may require
shredding for control of particle size.
They may be fed to the combustion
chamber via rams, gravity feed, air-
lock feeders, vibratory or screw feed-
ers, or belt feeders. Containerized waste
is typically gravity or ram fed.
(2) Combustion Chambers. The
physical form of the waste and its ash
content determine the type of combus-
tion chamber selected. Table Vll pro-
vides general selection considerations
for the four major combustion cham-
ber (incinerator) designs as a function
of wastes of different forms.62 Most
incineration systems derive their names
from the type of combustion chamber
employed.
Liquid injection incinerators or
combustion chambers are applicable
almost exclusively for pumpable liquid
waste. These units (Figure 2) are usu-
ally simple, refractory-lined cylinders
(either horizontally or vertically aligned)
equipped with one or more waste burn-
ers. Liquid wastes are injected through
the burner(s), atomized to fine droplets
and burned in suspension. Burners, as
well as separate waste injection noz- j
zlcs, may be oriented for axial, radial
or tangential Firing. Improved utiliza- I
tion of combustion space and higher I
heat release rates, however, can be
achieved with the utilization of swirl
or vortex burners or designs involving
tangential entry.67
Good atomization is critical to
achieving high destruction efficiency '
in liquid combustors. Nozzles have been j
developed to produce mists with mean 1
particle diameters as low as 1 micron
(p-m),68 compared to typical oil burn-
ers which yield droplets in the 10 to
50 p.m range.69 Atomization may be
attained by low pressure air or steam
[1 to 10 pounds per square inch gauge
(psig)], high pressure air or steam (25
to 100 psig), or mechanical (hydraulic)
means using specially designed ori-
fices (25 to 450 psig).
Vertically downward oriented liq-
uid injection incinerators are preferred
when wastes are high in inorganic salts
and fusible ash content, while horizon-
tal units may be used with low ash
waste. In the past, the typical capacity
of liquid injection incinerators was
roughly 30 X 106 Btu/h heat release.
However, units as high as 210 X 106
Btu/h are now in operation.
Rotary kiln incinerators (Figure 3)
are more versatile in the sense that they
are applicable to the destruction of solid
wastes, slurries and containerized waste
as well as liquids. Because of this, these
units are most frequently incorporated
into commercial off-site incineration
facility designs and utilized for Super-
fund remediation. The rotary kiln is a
horizontal cylindrical refractory-lined
shell that is mounted on a slight slope.
Rotation of the shell provides for
transportation of waste through the kiln
as well as enhanced mixing of the i
burning solid waste. The waste may
move either concurrent or countercur-
rent to the gas flow. The residence time
of waste solids in the kiln is generally
Table VII. Applicability of major incinerator types to wastes of various physical form."
Liquid Rotary Fixed Fluidized
Injection Kiln Hearth Bed
Solids:
Granular, homogeneous
X
X
X
Irregular, bulky (pallets, etc.)
X
X
Low melting point (tars, etc.)
X
X
X
X
Organic compounds with fusible ash constituents
X
X
X
Unprepared, large, bulky material
X
X
Gases:
Organic vapor laden
X
X
X
X
Liquids:
High organic strength aqueous wastes
X
X
X
X
Organic liquids
X
X
X
X
Solids-liquids:
Was:e contains halogenated aromatic compounds
X
X
X
(2,200°F minimum)
Aqueous organic sludge
X
X
34 • January 1993 • Vol. 43 • AIR 4 WASTE
i
G-ll
-------
Oischarge
to Quench or
Waste Heat Recovery
Aqueous
Waste
Steam
Auxiliary
Fuel
Liquid
Waste
Primary
Combustion
Air
Excess Air
Refractory Wall
Atomizing
Steam or
2600»F-3000«F
0.3-2.0 Seconds
Mean Combustion
Gas Residence Time
1500*F.2200*F
Cross Section
Combustion
Air
Waste Liquids.
Auxiliary Fuel
Waste Solids,
Containers or'
Sludges
Discharge
to Quench or
Heat Recovery
Auxiliary
Fuel
Liquid Waste
120%-200%
Excess Air
Rotary Seals
Refracto
1200-F-2300-F
2000-F
Incline 50-250%
Excess Air
Shroud
Auxiliary Ash
Fuel
1.0-3.0 Seconds
Mean Gas
Residence Time
Refractory
Ash
Rotary Kiln
Afterburner
Figure 3. Typical rotary kjln/attertxjmer combustion chamber.
Figure 2. Typical liquid injection combustion chamber.
0.5 to 1.5 hours. This is controlled by
the kiln rotation speed (typically 0.5 to
1.0 revolutions per minute), the waste
feed rate, and in some instances, the
inclusion of internal dams to retard the
rate of waste movement through the
kiln. The feed rate is also generally
adjusted to limit the amount of waste
being processed in the kiln to at most
20 percent of the kiln volume.
The primary function of the kiln is
to convert solid wastes to gases, which
occurs through a series of volatiliza-
tion, destructive distillation and partial
combustion reactions. An afterburner
G-12
AIR & WASTE. Vol. 43 • January 1993 • 35
-------
i? necessary, however, to complete the
gas-phase combustion reactions. The
afterburner is connected directly to the
discharge end of the kiln where the
gases exiting the Idin are directed ;o
the afterburner chamber. Some more
recent systems have installed a "hot
cyclone" between the kiln and after-
burner to remove solid particles that
might otherwise create slagging prob-
lems in the afterburner. The afterbur-
ner itself may be horizontally or
vertically aligned, and essentially
functions much on the same principles
as a liquid injection incinerator. In fact,
many facilities aiso fire liquid hazard-
ous waste through separate waste
burners in the afterburner. Both the af-
terburner and kiln are usually equipped
with an auxiliary fuel firing system to
bring the units up to temperature and
to maintain :he desired operating tem-
peratures. Or. the other hand, some op-
erators make it a practice of firing their
aqueous waste streams into the after-
burner as a temperature control mea-
sure. Rotary loins have been designed
with a heal release capacity as high as
150 X 106 Btu/h in the United States.
On average, however, units are typi-
cally around 60 X 106 Btu/h.
Fixed hearth incinerators, also called
controlled air, starved air or pyrolytic
incinerators, are the third technology
in use for hazardous waste incineration
today. These units employ a two-stage
combustion process, much like rotary
kilns (Figure 4). Waste is ram fed or
pumped into the first stage or primary
chamber, and burned at roughly 50 to
80 percent of stoichiometric air re-
quirements. This starved air condition
causes most of the volatile fraction of
the waste to be vaporized by the en-
do;hermic heat provided by the oxi-
dation of the fixed carbon fraction. The
resultant smoke and pyrolytic products
consisting primarily of methane, ethane
and other hydrocarbons; carbon mon-
oxide and products of combustion pass
to the second stage, or secondary
chamber. Here, additional air is in-
jected to complete the combustion
which can occur either spontaneously
or through the addition of supplemen-
tary fuels. The primary chamber com-
bustion reactions and turbulent
velocities are maintained at low levels
by the starved-air conditions to mini-
mize paniculate entrapment and car-
Dlscnarge
to Quench or
Heat Recovery
0.25-2.5 Seconds
Mean Residence Time
100-200%
Excess Air
i I
r««d
Rem-
Secondary
Chamber
1400-F . 2000
Primary
Chamber
1200«F • iaoo*F
2Z2ZZZZZZZZ
Combustion
Air
Transfer
Auxiliary Fuel or
Liquid Waate
Auxiliary Fuel
50 • 60%
Stoichiometric air
Refractory
Ash Discharge-
Ram
Aati Discharge
Figurt 4. Typical taM beam co^ci'Stion tfamwr.
36 • January 1S93 • Vol. 43 • AIR & WASTE
G-13
-------
ryover. With the addition of secondary
air, total excess air for fixed hearth in-
cinerators is in the 100 to 200 percent
range.
Fixed hearth units tend to be of
smaller capacity than liquid injection
or rotary kiln incinerators because of
physical limitations in ram-feeding and
transporting large amounts of waste
material through the combustion
chamber. These lower relative capital
costs and potentially reduced particu-
late control requirements make them
more attractive than rotary kilns for
smaller on-site installations.
Fluidized beds have long served the
chemical processing industry as a unit
operation and have been used to bum
sludge generated by municipal waste-
water treatment plants. This type of
combustion system has only recently
begun to see application in hazardous
waste incineration. Fluidized bed in-
cinerators may be either circulating or
bubbling bed designs.70 Both types
consist of a single refractory-lined
combustion vessel partially filled with
particles of sand, alumina, calcium
carbonate or other such materials.
Combustion air is supplied through a
distributor plate at the base of the com-
bustor (Figure 5) at a rate sufficient to
fluidize (bubbling bed) or entrain part
of the bed material (circulating bed).
In the circulating bed design, air ve-
locities are higher and the solids are
blown overhead, separated in a cy-
clone and then returned to the com-
bustion chamber. Operating
temperatures are normally maintained
in the 1,400 to 1,600°F range and ex-
cess air requirements range from 25 to
150 percent.
Fluidized bed incinerators are pri-
marily used for liquids, sludges or
shredded solid materials including soil.
To allow for good distribution of waste
materials within the bed and removal
of solid residues from the bed, all sol-
ids generally require prescreening or
crushing to a size less than 2 inches in
diameter. Fluidized bed incinerators
offer: high gas-to-solids ratios, high heat
transfer efficiencies, high turbulence
in both gas and solid phases, uniform
temperatures throughout the bed, and
the potential for in-situ acid gas neu-
tralization by lime, limestone or car-
bonate addition. Fluidized beds also
have the potential for solids agglom-
eration in the bed, especially if salts
are present in waste feeds.
Regardless of the incinerator type
selected, the chemical and thermody-
namic properties of the wastes deter-
mine the sizing of the combustion
chamber and its operating conditions |
(temperature, excess air, flow rates) and
determine the nature of air pollution
control and ash/residue handling sys-
tems. Elemental composition and
moisture content data are necessary to
determine stoichiometric combustion
air requirements and to predict com-
bustion gas flow and composition.
These parameters are important in de-
termining combustion temperature and
residence time, the efficiency of waste/
fuel/air mixing, and the type and size
of air pollution control equipment.
Typical operating temperatures, gas
(and solid) residence times, and excess
air rates for each of the four major in-
cinerator types are indicated in Figures
2-5. It is important to understand,
however, that significant deviation from
these values has been observed in ac-
tual field practice without detrimental
effect on waste destruction and re-
moval efficiency.71
(3) Air Pollution Control. Follow-
ing the incineration of hazardous
wastes, combustion gases typically need
to be further treated in an air pollution
control system. The presence of chlor-
ine or other halogens in the waste will
generally signal a need for a scrubbing
or absorption step for combustion gases
to remove HQ and other haloacids. Ash
in the waste is not destroyed in the
combustion process. Depending on its
composition, ash will either exit as
bottom ash, at the discharge end of a
kiln or hearth for example, and/or as
particulate matter suspended in the
combustion gas stream (fly ash). Par-
ticulate emissions from most hazard-
ous waste combustion systems generally
have particle diameters down to less
than one micron and require high ef-
ficiency collection devices to meet the
RCRA or state emission standards.
One of the most commonly em-
ployed air pollution control systems for
hazardous waste facilities is a quench
(gas cooling and conditioning) fol-
lowed by high-energy venturi scrubber
(particulate removal), a packed tower
absorber (acid gas removal) and a de-
mister (visible vapor plume reduc-
tion). Facilities handling low ash, low
halogen content liquid waste streams
have been able to operate without any
control, however.
Venturi scrubbers involve the injec-
tion of a scrubbing liquid (usually water
or a water/caustic solution) into the ex-
haust gas stream as it passes through a
high velocity constriction, or throat. The
liquid is atomized into fine droplets
wfu'ch entrain fine particles and a por-
tion of the absorbable gases in the gas
stream. The major advantage of ven-
turi scrubbers is their reliability and
relative simplicity of operation. On the
other hand, maintaining the significant
pressure drop across the venturi throat
(60 to 120 inches of water column) re-
quired for efficient hazardous waste
combustion particulate matter control
represents a significant percentage of
1.09.0 Seconds
M*tn Combustion
Gu Residence
Time
Preheet
Burner
Olaehargc
to Cyclone
25- 190%
Fluidized ;
Liquid
Send or Alumina-
Sludge
~.~'~D ntTD
Fluidlxing
Combustion
Solids Feed and
Cyclone Ash Recycle
1400* • 1600-F
Auxiliary Fuel
Air Distribution
Manifold
Ash/Bed
Removal
Figure S. Typical fluidized bed combustion chamber.
G-14
AIR & WASTE • Vol. 43 • January 1993 • 37
-------
the total cost of operation of inciner-
ation facilities employing venturi
scrubbing. Also, venturi scrubbers may
not be very effective in controlling the
emission of fine particulates such as
metal aerosols.
Acid gas removal is generally ac-
complished in packed bed or plate tower
scrubbers. Packed bed scrubbers are
generally vessels filled with randomly-
oriented packing material such as
polyethylene saddles or rings. The
scrubbing liquid is fed to the top of the
vessel, with the gas flowing in either
concurrent, countercurrent or cross-
Dow modes. As the liquid flows through
the bed, it wets the packing material
and thus provides the interfacia! sur-
face area for mass transfer with the gas
phase which is required for effective
acid gas absorption.
Like packed bed scrubbers, plate
scrubbers also rely on absorption for
the removal of contaminants. The basic
design is a vertical cylindrical column
with a number of plates or trays inside.
The scrubbing liquid is introduced at
the top plate and flows successively
across each plate as it moves down-
ward to the liquid outlet at the tower
i bottom. Gas comes in at the bottom of
I the tower and passes through openings
: in each plate before leaving through
the top. Gas absorption is promoted by
the breaking up of the gas phase into
small bubbles which pass through the
volume of liquid on each plate.
Packed bed or plate tower scrubbers
are commonly used at liquid injection
incinerator facilities, where absorption
j of soluble gaseous pollutants [HC1 &
sulfur oxides (SO„)] is often most im-
portant and particulate control is less
critical. At rotary kiln or fixed hearth
facilities, or liquid injection facilities
where high ash content wastes are in-
cinerated, however, venturi scrubbers
are often used in series with packed
bed or plate tower scrubbers.
Many designs have begun to incor-
porate waste heat boilers as a substi-
tute for gas quenching and as a means
of energy recovery. •73 Wet electro-
static precipitators (ESP), ionizing wet
scrubbers (IWS), collision scrubbers,
spray dryer absorbers (SDA), and fab-
ric filters (FF) are also being incor-
porated into newer systems.74 This is
iargely due to their high removal ef-
ficiencies for small particles and lower
pressure drop.
(4) Residue and Ash Handling. The
inorganic components of hazardous
wastes are not destroyed by incinera-
tion. These materials exit the inciner-
ation system either as bottom ash from
the combustion chamber, as contami-
nants in scrubber waters and other air
pollution control residues, and in small
amounts in air emissions from the stack.
Residues generated from the incinera-
tion of hazardous waste must be man-
aged carefully.
Ash is commonly either air-cooled
or quenched with water after discharge
from the combustion chamber. From
this point, ash is frequently accumu-
lated on-site in storage lagoons or in
containers prior to disposal in a per-
mitted hazardous waste land disposal
facility. Dewatering or chemical fixa-
tion/ stabilization may also be applied
to meet the Land Disposal Restriction
(LDR) regulations prior to disposal.
Air pollution control residues are
generated from the combustion gas
quenching, particulate removal, and
acid gas absorption steps in an incin-
eration system. These residues are typ-
ically aqueous streams containing
entrained particulate matter, absorbed
acid gases (usually as HQ), salts, and
trace amounts of organic contami-
nants. These streams are often col-
lected in sumps or recirculation tanks
where the acids are neutralized with
caustic and returned to the process.
Eventually, a portion or all of these
waters must be discharged for treat-
ment and disposal. Many facilities dis-
charge neutralized waters to settling
lagoons or to a chemical precipitation
step to allow for suspended contami-
nants to be concentrated and ultimately
sent to land disposal. Depending upon
the nature of the dissolved contami-
nants and their concentration after
treatment, waters may either be re-
turned to the process or discharged to
sewers. One alternative to the man-
agement of aqueous residue streams is
to use dry scrubber systems which do
not generate any wastewater.
Measuring Process Performance
Proper and accurate measurement
of the emissions from incineration sys-
tems is a critical issue. Great demands
have been placed upon sampling and
analysis technology by the RCRA in-
cinerator regulations. Fortunately, sig-
nificant progress has been made in
adapting measurement methods to the
rigors of specific compound identifi-
cation and the level of detection and
accuracy which are necessary to assess
compliance with the RCRA incinera-
tion standards. These methods will
rarely-be a limitation in assessing in-
cinerator performance if proper atten-
tion^ given to quality assurance and
quality control, if adequate advanced
planning is conducted, and if experi-
enced personnel arc involved in the
sampling and analysis activities.
Performance measurement may have
any of the following three purposes:
(1) to establish initial or periodic com-
pliance with performance standards
(e.g., trial burns), (2) to routinely
monitor process performance and di-
rect process control (e.g., continuous
monitoring), and (3) to conduct per-
formance measurements for research
and equipment development purposes.
Nearly all the methods employed in
assessing regulatory compliance are
official methods which have been stan-
dardized and published in the Federal
Register or EPA guidance documents.
Routine performance monitoring for
process control often involves the use
of continuous monitors for emissions
and facility-specific engineering pa-
rameters (e.g., temperature, pH, kiln
rotation). Research and equipment as-
sessment investigations may involve any
of the aforementioned techniques in
combination with standard and occa-
sional nonstandard sampling and
analysis techniques designed for rapid
screening of performance or for ultra-
sensitive detection of specific mate-
rials.
Performance Measurement
Figure 6 illustrates sampling points
which may be involved in assessing
incinerator performance. In the case of
trial bum activities, the main focus of
sampling activities is on the collection
of waste feed and stack emission sam-
ples. Ash and air pollution control sys-
tem residues are also sampled and
analyzed. Sampling of input/output
streams around individual system
components (e.g., scrubbers) may also
be conducted in research testing or
equipment evaluation studies.
The main focus of analytical activ-
ities is on POHCs, particulates, metals
and HC1. Stack gas analysis may be
extended to a determination of other
organic compound emissions. In the
case of particulate emissions, the size
distribution of stack particles may also
be of interest. The size of emitted par-
ticulate affects its transportation and fate
in the atmosphere and can influence
the fate of panicles relative to inhala-
tion, an important factor in health ef-
fects assessment. Few hazardous waste
incinerator tests have actually col-
lected panicle size data, primarily due
to time and funding limitations.
EPA has provided guidance on the
types and methods of sampling and
analysis to be used in trial burns de-
signed to measure facility compliance
38 • January 1993 • Vol. 43 • AIR & WASTE
,.:S~G-15
f
-------
Legend
(p) Pressure
(t) Temperature
(?) Flow Rate
Differential Pressure
AP
Solid
POHC
Wtlght
Rotary
Klin
POHC
POHC
Metals
TCLP
Aauaoua
aata
POHC
| PQHC|—
Fual
POHC
Uqula
Infection
Gaaaout
Watt*
POHC
[POHC)—
Fual
(T) ^
HMt
Recovery
&)
i—»
POHC
Particulate
POHC
©©
Abeorber
V#nturl
0-
POHC
PH
Metals
TCLP
r
Rgun 6. Potential sampling points tor assessing incinerator performance.
with the RCRA incinerator stan-
dards.19'20-29-75-79 Johnson80-81 has pro-
vided additional information on this
subject. The first guidance manual for
hazardous waste incinerator permit-
ting,19 issued in 1983, is being updated
and should be available in the near fu-
ture. Similar guidance has been pro-
vided for PCB incinerators.82 Table VIII
outlines sampling methods typically
involved in RCRA trial burns. For any
trial burn, at any one set of operating
conditions and waste feed conditions,
three replicate runs (i.e., identical as
possible) are usually recommended to
obtain a representative assessment of
incinerator performance.75
The sampling method numbers in
Table VIII refer to methods identified
in EPA guidance documents and re-
ports.76-7®-83-84 These materials expand
upon and augment the information in
EPA SW-846, "Test Methods for
Evaluating Solid Waste: Physical/
Chemical Methods"85-86 and "Sam-
plers and Sampling Procedures for
Hazardous Waste Streams."87 EPA has
also developed a computerized data base
which provides a reference directory
pertaining to the availability and reli-
ability of sampling and analysis meth-
ods for potentially designated POHCs.88
An expanded version of this reference
directory is under development.89 Along
with 40 CFR, Part 60, Appendix A,
these references are the best sources
from which to identify sampling meth-
ods to be used in incinerator perform-
ance evaluations.
Analytical methods for specific
hazardous compounds are often of
greatest interest. Analytical methods
for Appendix VIII compounds15 in these
references are generally based upon
high-resolution fused-silica-capillary
column gas chromatography (GC) in
combination with mass spectrometry
(MS) for specific compound detection.
High-performance liquid chromatog-
raphy (HPLC) is recommended for de-
termination of compounds that are
inappropriate for detection by GC/MS.
Application of analytical methods has
been evaluated for 240 of the approx-
imately 400 Appendix VIII Com-
pounds.90-91 These methods have shown
acceptable precision in determining
most of the compounds. Detection limits
in synthetic samples were on the order
of 1 to 10 nanograms per injection, but
detection in actual waste samples will
be dependent upon the nature of inter-
ferences in the waste matrix.
While all emissions from hazardous
waste incinerators are important, the
greatest interest is most often placed
on stack emissions. The accuracy and
reliability of stack sampling results are
central to the entire issue of incinerator
performance and environmental safety.
Existing methods have been the sub-
ject of substantial research, validation
and debate. Procedures are now in place
that provide assurance that measure-
ment of these emissions are valid.84
Stack emissions are sampled to de-
termine stack gas flow rate, HQ, par-
ticulate concentration, metals and the
concentration of organic compounds of
interest. Determination of stack gas flow
rate and particulate emissions is per-
formed using the conventional stack
sampling method commonly referred
to as Method 5. This method encom-
passes EPA Methods 1 through 5 and
is defined in detail in 40 CFR Part 60,
Appendix A. HQ emissions are sam-
pled by modifying the Method 5 train
to include a caustic impinger. A spe-
cialized sampling and analytical method
has also been developed to further spe-
ciate and quantify hydrogen halide and
halogen emissions92 and is specified in
the EPA "Methods Manual for Com-
pliance with BIF Regulation"84
Method 0050.
as
G-16
AIR & WASTE • Vol. 43 • January 1993 • 39
-------
Table VIP. Sampling methods and analysis parameters.
Sample
Sampling frequency
for each run
Sampling
method'
Analysis parameter"
1. Liquid waste feed
Grab sample every 15 min
S004
V&SV-POHCs, CI, ash,
ult. anal., viscosity,
HHV, metals
2. Solid waste feed
Grab sample from each drum
S006, S007
VS& V-POHCs, CI, ash,
HHV, metals
3. Chamber ash
Grab one sample after all
runs are completed
S006
V&SV-POHCs, TCLP",
HHV, TOC, metals
4. Stack gas
Composite
Method 0010 (3h) (MM5)
SV-POHCs
Composite
Composite
Method 5'
Method 0011
Particulate, H;0
Formaldehyde
Composite
Method 0050
HC1, CI,
Composite
Three pairs of traps
Method 0030 (2h)
(VOST)
V-POHCs
Composite in Tedlar gas bag
Composite
Continuous
Composite
Method 0040
Method 3 (1-2 h)
CEM
Method 0012
V-POHCs'
C02 and O, by Orsat
CO, C03, 03, SO,
Trace metals'
5. APCD Effluent
(liquid)
Grab sample every 1/2 h
S004
V&SV-POHCs, CI, pH,
metals
6. APCD Residue
Grab sample every 1/2 h
S006
V&SV-POHCs, metals
(solid)
¦ VOST denotes volatile organic sampling train; MM5 denotes EPA Modified Method 5; SXXX denotes sampling methods found in
"Sampling and Analysis Methods for Hazardous Waste Combustion"'3; CEM denotes Continuous Emission Monitor (usually nondis-
pcrsive infrared).
' V-POHCs denotes volatile principal organic hazardous constituents (POHCs); SV-POHCs denotes semivolatile POHCs; HHV denotes
higher heating value; TOC denotes Total Organic Carbon.
e Gas bag samples may be analyzed for V-POHCs only if VOST samoles are saturated and nol quantifiable or if the tarcet POHC is too
volatile for VOST.
" TCLP - toxicity characteristic leaching procedure"3.
• Metals captured by the Multiple Metals Sampling Train84.
' Method 5 can be combined with Method 0050 or Method 0012.
The technology of incinerator stack
sampling for trace organic compounds
is sophisticated. While the basic tech-
nology is well developed, many pit-
falls await those who attempt the job
without sufficient knowledge or ex-
perience. Sampling a stack effluent for
organics to determine DRE may re-
quire one to four (or more) separate
methods. This depends on the number
and characteristics of compounds to be
quantified and the detection limits re-
quired to prove a DRE of 99.99 to
99.9999 percent or establish levels of
incomplete combustion byproducts.
Special attention must be given to
sampling rate and duration in planning
for emission tests. This will ensure that
a sufficient amount of sample is col-
lected to meet detection limit objec-
tives and allow for all necessary
analyses to be completed.75
The seven methods most often used
for hazardous waste incinerator sam-
pling are: (1) Modified Method 5
(MM5). (Method 0010), (2) Method 5
(M5), (3) Volatile Organic Sampling
Train (VOST). (Method 0030), (4) Gas
bags. (Method 0040), (5) Method 0050,
(6) Multiple Metals Sampling Train.
(Method 0012), and (7) Method 0011.
The MM5 train is used to capture
semivolatile (boiling point 100°C to
300°C) and nonvolatile (boiling point
>300°C) organic compounds. The
MM5 is merely a simple modification
of the M5 train involving insertion of
a sorbent module (XAD-2 resin) be-
tween the filter and the first im-
pinger.93 It is recommended that a
separate M5 train for particulate deter-
mination be used in tandem with the
MM5 train since drying of the filter for
particulate determination may invali-
date analysis of organic compounds on
the filter.75 Like the M5, the MM5 in-
volves isokinetic traversing of the stack
with a sampling probe. Water-cooled
sample probes are necessary for sam-
pling hot combustion gases in regions
ahead of quenching. Where it is desir-
able to collect larger amounts of sam-
ple for more extensive analysis or lower
detection limits, the much larger Source
40 • January 1993 • Vol. 43 • AIR & WASTE
Assessment Sampling System (SASS)
may be used instead of the MM5.75
SASS involves single point (pseudo-
isokinetic) sampling at a rate of 110 to
140 L/min (4 to 5 cfm) compared to
the 14 to 28 LVmin (0.5 to 1 cfm) rate
of the MM5. The same sorbent resin
(XAD-2) is also used. Because of its
more convenient sample size, porta-
bility and multi-point isokinetic sam-
pling, the MM5 train is generally
preferred over the SASS train.
The VOST is used for volatile or-
ganic compounds (boiling point 30°C
to 132°C). This method was developed ;
by EPA in 1981 to enable detection of
stack concentrations of volatile or-
ganic compounds as low as 0.1 ng^L.94
This detection limit was deemed nec-
essary to demonstrate greater than 99.99 j
percent DRE for volatile organic com-
pounds at concentrations as low as 100
ppm in the waste feed. The VOST sys-
tem involves drawing a stack gas sam-
ple through two sorbent tubes in series.
The first tube contains Tenax resin and
the second contains Tcnax and acti-
G-17
-------
vated charcoal. Up to six pairs of sor-
bent tubes operating at one LVmin for
20 minutes each may be needed to
achieve DRE confirmation.95 For higher
stack gas concentrations, however, the
VOST may be operated at lower flow
rates with fewer pairs of tubes.
Various types of gas sampling bags
may also be used to sample for volatile
organic compounds. These are gener-
ally appropriate only for higher or-
ganic concentrations. The accuracy of
sampling with this method is a func-
tion of the sampling and storage char-
acteristics of the bags.96 The use of
extensive quality assurance and quality
control procedures is required with both
plastic bags and the VOST to avoid
sample contamination in the field and
in transit.97 This problem was not fully
appreciated in some of the early field
tests employing the VOST.
Both the MM5 and VOST sampling
methods have been subjected to labo-
ratory and field validation studies for
selected compounds.98'100 These stud-
ies have demonstrated that excellent
results are possible with these meth-
ods. It is important to note, however,
that modifications of these methods may
be required for certain POHC com-
pounds which become chemically or
physically altered in the sampling sys-
tems. Highly water-soluble com-
pounds (e.g., acetonitrile) and water-
reactive compounds (e.g., phthalic an-
hydride), for instance, present special
challenges to current sampling meth-
ods.
Method 0050 is used to collect HQ
and CI, in stack gases. It collects the
emission samples isokinetically and can
be combined with Method 5 for par-
ticulate determination. The Multiple
Metals Sampling Train is used to de-
termine the total chromium, cadmium,
arsenic, nickel, manganese, beryl-
lium, copper, zinc, lead, selenium,
phosphorus, thallium, silver, anti-
mony, barium and mercury in incin-
erator stack emissions. The stack sample
is withdrawn isokinetically from the
source with particulate emissions col-
lected in the probe and on a heated
filter and gaseous emissions collected
in a series of chilled impingers con-
taining an aqueous solution of dilute
nitric acid combined with dilute hy-
drogen peroxide in each of two im-
pingers, and acidic potassium
permanganate solution in each of two
impingers. Method 0011 is used to
collect formaldehyde in stack emis-
sions.
Process Monitoring
Measurement of a wide variety of
incinerator operating parameters may
be necessary to maintain thermal de-
struction conditions which are equiv-
alent to those observed during a
successful trial bum. These measures
are used as indicators of the perform-
ance of the incineration system and
serve as input to automatic and manual
process control strategies. There are
many potential measurements, includ-
ing such parameters as combustion
temperature, waste feed rate, oxygen
and CO concentration in the stack, gas
flow rate at strategic points and scrub-
ber solution pH. These parameters and
their use are described in detail in a
number of resource docu-
ments.19,2a62-75
Continuous emission monitors
(CEMs) are required or often used in
measuring combustion gas compo-
nents such as CO, C02, oxygen (02),
NOx and HC. More recently, some
consideration has been given to the uti-
lization of HC1 and opacity CEMs as
well. If properly interpreted, combus-
tion gas components may indicate the
completeness of the thermal destruc-
tion reaction. These methods typically
require extraction of gas samples from
the gas stream of interest and mea-
surement with a remote instrument.
Some parameters, such as CO and 02,
may be measured in-situ (in the stack).
Table IX summarizes monitor type and
available concentration measurement
ranges for a number of CEMs,101 some
of which are required by the RCRA
regulations. These CEMs are, how-
ever, commercially available at vary-
ing stages of development.
EPA has promulgated performance
specifications for continuous emission
monitoring of carbon monoxide, oxy-
gen and hydrocarbons for incinerators,
boilers and industrial furnaces burning
hazardous waste.84 Performance spec-
ifications for CO and 02 are given in
Table X. Monitoring HC is based on
extracting a sample through a heated
sample line to a flame ionization de-
tector (FID). Unheated systems may
also be used on an interim basis if a
gas conditioning system is provided that
reduces the moisture content of the
sample gas entering the FID to less than
2 percent.
Emissions from Hazardous Waste
Incineration
Ideally, the primary products from
combustion are carbon dioxide, water
vapor and inert ash. In reality, what
appears outwardly to be a straight-for-
ward, simple process is actually an ex-
tremely complex one involving
thousands of physical interactions and
chemical reactions, reaction kinetics,
catalysis, combustion aerodynamics and
Table IX.
Summary of continuous emission monitors.101
Expected
concentration
Available
Pollutant
Monitor type
range
range*
o2
Paramagnetic
Electrocaialytic (e.g.,
zirconium oxide)
5-14%
0-25%
C02
NDIR"
2-12%
0-21%
CO
NDIR
0-100 ppmv
0-5000 ppmv
HQ
NDIR
0-50 ppmv
0-10000 ppmv
Opacity
Transmissometer
0-10%
0-100%
NO,
Chemiluminescence
0-4000 ppmv
0-10000 ppmv
S02
Flame photometry
Pulsed fluorescence
NDUVC
0-4000 ppmv
0-5000 ppmv
SO,
Organic
Colorimetric
0-100 ppmv
0-50 ppmv
Gas chromatography
0-50 ppmv
0-100 ppmv
compounds
(FID)"
Gas chromatography
(ECD)<
Gas chromatography
(P1D)<
IR absorption
UV absorption
HC
FID
0-50 ppmv
0-100 ppmv
' For available instruments only. Higher ranges are possible through dilution.
6 Nondispersion infrared.
c Nondispersion ultraviolet.
d Flame ionization detector.
' Electron capture detector.
' Photo-ionization detector.
G-18
AIR & WASTE • Vol. 43 • January 1993 • 41
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Table X. Performance specifications for CO and 0, monitors.84
CO monitors
Parameter
Low range
High range
0,
monitors
Calibration
drift
(CD) 24 hours
Calibration
error
(CE)
Response time
Relative
accuracv"
(RA)'
< 6 ppm"
< 10 ppm*
< 2 min
£ 90 ppm
< 150 ppm
£ 2 min
(<)
S 0.5% 0;
s: 0.5% O,
£ 2 min
(incorporated
in CO and RA
calculation)
¦ For Tier II, CD and CE arc <3% and <5% of twice the permit limit, respectively.
' Expressed as the sum of the mean absolute value plus the 95% confidence interval of a
series of measurements.
' The greater of 10% of the Performance Test Method (PTM) or 10 ppm.
heat transfer. This is further compli-
cated by the complex and fluctuating
nature of the waste feed to the process.
While combustion and incineration de-
vices are designed to optimize the
chances for completion of these reac-
tions, they never completely attain the
ideal. Rather, small quantities of a
multitude of other products may be
formed, depending on the chemical
composition of the waste and the com-
bustion conditions encountered. These
products, along with potentially un-
reacted components of the waste, com-
prise the emissions from the incinerator.
Hydrogen chloride and small
amounts of chlorine, for example, are
formed from the incineration of chlor-
inated hydrocarbons. Hydrogen fluo-
ride (HF) is formed from the
incineration of organic fluorides, and
both hydrogen bromide (HBr) and bro-
mine (Br2) arc formed from the incin-
eration of organic bromides.102 Sulfur
oxides, mostly as S02, but also in-
cluding 1 to 5 percent sulfur trioxidc
(S03), are formed from the sulfur pres-
ent in the waste material and auxiliary
fuel. Highly corrosive phosphorus
pentoxide (P,0<) is formed from the
incineration of organo-phosphorus
compounds. In addition, oxides of ni-
trogen may be formed by fixation of
nitrogen from nitrogen compounds
present in the waste material or in the
combustion air. Suspended particulate
emissions are also produced and in-
clude particles of mineral oxides and
salts from the mineral constituents in
the waste material. A wide range of
organic compounds may also be formed
in trace amounts from the incomplete
thermal destruction of organic com-
j pounds in the waste and auxiliary fuel.
Prior to the 1980s, there were only
limited data available on waste de-
struction performance and pollutant
emissions from hazardous waste ther-
mal destruction devices. Studies by EPA
and others in the 1970s employed a
variety of evolving trace organic pol-
lutant sampling and analysis tech-
niques and were often targeted only
toward measuring macro-destruction
and combustion efficiencies'03"105 rather
than the destruction and removal of
specific organics and characterization
of the emissions. During the early
1980s, however, EPA conducted a
substantial program of performance
testing at thermal destruction facilities.
The testing was designed to estimate
the environmental impact of these op- ¦
erations and to provide information on '
the ability of these facilities to destroy
organics and control emissions. The test
facilities, test procedures, and per-
formance results have been
summarized106 for the facilities tested
(incinerators, industrial boilers, and
industrial process kilns). Complete test
reports have been published for the in-
cinerators,107 industrial boilers,108-10'
and cement/aggregate kilns110-111 tested.
These data as well as trial bum results
from fourteen additional RCRA incin-
erators, have been summarized in an
EPA report, "Permit Writer's Guide
to Test Burn Data-Hazardous Waste
Incineration."112 EPA has conducted
additional testing to further investigate
the characterization and control of par-
ticulate matter, metals, HO, total mass
emissions, and PICs from hazardous
waste incinerators113115 and cement
kilns.11®117 In addition, numerous trial
burns have since been conducted for
hazardous waste incinerators in com-
pliance with the RCRA permitting re-
quirements.
The following sections discuss this
information in five areas:
(1) DRE, paniculate emissions and
HC1 control
(2) Metal emissions
(3) Combustion byproduct emis-
sions
(4) Dioxin and furan emissions
(5) Ash and air pollution control
residue quality
DRE, Particulate Emissions and HCI
Control
Tables XI, XII and XIII summarize
waste destruction efficiency, HCI and
particulate emissions results for incin-
erators, industrial boilers, and cement
kilns tested by EPA in the early 1980s.
Information from 14 trial bums are also
included in Table XI. The tables also
summarize certain process operating
parameters, as well as emissions of CO,
and 02 and, in some instances, NOx
and SOx.
These data reveal that well operated
incinerators, industrial boilers and
process kilns are capable of achieving |
99.99 (the RCRA performance stan- :
dard) to >99.999 percent DREs. In
many cases the target POHC was be-
low the detection limit and the calcu-
lated DRE was a maximum value
assuming the stack gas concentration
of the POHC equalled the detection
limit. All of the incinerators tested by
EPA achieved this level of perform-
ance for candidate POHC compounds
in concentrations greater than 1,200
parts per million (ppm) in the waste
feed.1'8 Candidate POHC compounds
between 200 and 1,200 ppm fre-
quently were not destroyed to a 99.99
percent DRE and no compounds below
200 ppm in the waste feed met the
RCRA DRE limit. In fact, regression
analysis of the pooled data suggested
that statistically significant correla-
tions (correlation coefficients were 0.76
and 0.84) existed between compound
penetration (1-DRE) and compound
feed concentration, showing that DRE
increased with waste feed concentra-
tion.116
This phenomenon, which has been
observed in tests of other thermal de-
struction devices, was not anticipated.
A number of possible explanations have j
been advanced.2-107 The most fre-
quently stated theory postulates that at
the very low stack emission concentra-
tions (< 1 ng/L) necessary to demon-
strate greater than 99.99 percent DRE
for a sub-1,200 ppm compound, suf-
ficient amounts of that compound may
42 • January 1993 • Vol. 43 • AIR & WASTE
G-19
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Table XI. Incinerator performance and slack emissions data (data reported as averages for each facility).I0,"z
Facility Type
o2
(%)
CO
(ppm)
HC
(ppm)
DRE
(%)
Particulate
(mg/m3)
HCI
control
(%)
Commercial rotary kiln/liquid incinerator
10.5
6.2
1.0
99.999
152
99.4
Commercial fixed hearth, two-stage incinerator
11.4
6.9
1.0
99.994
400
98.3
On-site two-stage liquid incinerator
8.1
9.4
6.0
99.994
143
99.7
Commercial fixed hearth, two-stage incinerator
11.0
327.7
18.7
99.997
60
b
On-site liquid injection incinerator
13.2
11.9
1.0
99.999
186
b
Commercial two-stage incinerator
10.2
1.1
1.3
99.998
902
b
On-site rotary kiln incinerator
9.7
554.0
61.7
99.999
23
99.9
Commercial two-stage fixed hearth incinerator
13.4
26.8
1.8
99.996
168
98.3
On-site rotary kiln
c
794.5
NA'
99.998
184
99.7
On-site liquid injection incinerator
9.7
66.3
7.8
99.994
95
b
On-site rotary kiln incinerator
10.7
5.8
NA
99.996
404
99.9
On-site rotary kiln incinerator
14.1
323.0
NA
99.996
NA
99.8
On-site liquid injection incinerator
12.4
31.9
1.9
99.999
163
98.6
On-site liquid injection incinerator
9.3
1.0
NA
99.996
40
b
On-site fluidized bed incinerator
3.6
67.4
NA
99.996
259
b
On-site fixed hearth incinerator
12.9
NDd
NA
99.999
93
b
On-site liquid injection incinerator
4.5
358.0
NA
99.995
99
b
On-site liquid injection incinerator
3.6
28.4
NA
99.998
12
99.3
Commercial rotary kiln incinerator
9.4
8.0
0.5
99.999
172
99.9
On-site liquid injection incinerator
3.1
779.3
NA
99.999
88
99.6
On-site liquid furnace incinerator
6.4
56.3
NA
99.999
4
99.9
On-site fixed hearth incinerator
13.5
5.0
NA
99.999
150
98.4
i na = not available.
» HCI emissions <4 lb/h.
c Reported only as a range (3.1-16.7%)
4 ND = Not detected.
Table XII. Summary of boiler performance (data reported as averages for each facility).106
Facility Type
Load
(%)
o2
(%)
Residence
time
(s)
Average
volumetric heat
release rate
(kW/m3)
DRE"
W/F1 (%)
NO, (ppm)6
CO
(ppm)"
Watertube stoker
100
6-16
1.2
509
99.98
40
163-210
900-1200
Packaged firetube
25
4-6
0.8
739
99.991
0.1-0.5
40-65
47-88
Field erected watertube
26
10
2
78
99.999
37
61-96
18-21
Converted stoker
78
4-6
1.1
339
99.998
18-48
193-250
75-127
Packaged watertube
36-73
6-7
1.1-0.5
960
99.995
19-56
164-492
83-138
Convened watertube
53
7-11
2
107
99.98
8.7-10.1
243-328
109-139
Modified firetube
44
8
0.4
807
99.998
100
67-74
146-170
Tangentially fired watertube
100
6
2
180
99.991
2.4-4.3
393-466
142-201
Packaged watertube
65
2
1.8
343
99.998
8.2
64-78
46-750
410-1125'
Packaged firetube
50-100
3-8
0.7-0.3
1240
99.999
100
85-203
20-135
Packaged watertube
82
4
1.8
269
99.999
49
154-278
102-119
' W/F = waste heat input as a percent of total heat input.
* Range of average values across individual sites and runs including baseline.
' Higher values are for high nitrogen content waste firing.
' Mass weighted average for all POHCs in the waste > 100 ppm.
actually be formed as an incomplete
combustion or recombination byprod-
uct from other compounds in the wastes
'"f601 a reduction of the calculated
DRE below 99.99 percent. Others ar-
^ue '*?at limitations of current stack
sampling and analysis techniques for
such low levels of trace organic com-
pounds are responsible.
a.reSu'at0fy standpoint, how-
c', ""s is not currently perceived as
an issue. Few, if any, of the low con-
centration compounds in the wastes
identified in the EPA test program
would have actually been selected as
POHCs in trial burns if existing EPA
guidance on POHC selection was em-
ployed. It is also important to note that
even though DRE declines with lower
initial compound concentrations in the
waste, the absolute amount of com-
pound emitted also declines. In fact,
the DRE versus concentration corre-
lation noted previously actually pre-
dicts that the net emissions resulting
from a reduced DRE for a 100 ppm
compound will actually be slightly less
than those for a 99.99 percent DRE for
the compound at 1000 ppm in the waste.
Table Xll indicates that industrial
boilers, particularly the larger water-
tube units, typically attain 99.99 per-
cent DRE. Cement kilns, lime kilns
G-20
AIR & WASTE • Vol. 43 • January 1993 • 43
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FEATURE
Table XIII. Summary of industrial bin performance and stack emissions data (dam reported as averages for each facility).
Particulate
HC1
NOx
SO-
W/F
Facility Type
Test*
DRE (%)
(kg/Mg)<
(kg/h)
(ppm)
(ppm)
Wet process cement kiln
W
99.200
0.27
0.36
68
450
25
(non-atomized waste)
B
-
0.26
0.09
136
279
-
Wet process cement kiln
W
99.996
0.27
2.1
478
265
15
(atomized waste)
B
—
0.26
0.6
371
636
-
Dry process cement kiln
W
99.998
—
11.5
814
19
45
(non-atomized waste)
B
—
-
1.3
620
7
-
Dry process cement kiln
w
99.992
—
0.47
486
27
15
(atomized waste)
B
—
—
0.25
680
27
—
Lime kiln
W
99.997
0.11
0.20
446
596
30
(atomized waste)
B
-
0.10
0.09
386
553
-
Shale aggregate kiln
W
>99.99
0.33
2.1
—
—
100
(atomized waste)
Gay aggregate kiln
W
99.998
0.58
0.023
162
1130
59
(atomized waste)
Gay products kiln
W
>99.99
0.002
0.84
—
—
100
(atomized waste)
' W = waste testing, B = baseline (fossil fuel only).
0 W/F = waste fuel heat input expressed as a percent of total heat input.
c Paniculate emissions are expressed as kg paniculate per metric ton (Mg) of product produced (e.g., cement, lime).
and light-weight aggregate kilns with
good combustion control and waste
i atomization all met or exceeded the
99.99 percent DRE (Table Xlll).
All incinerators and industrial
process kilns tested met or approached
the RCRA HC1 removal standard of 99
percent. The industrial boilers tested
typically had no controls for HQ, but
none exceeded the 1.8 kg/h emission
standard because wastes with low net
chlorine content were employed.
Achieving the RCRA paniculate
emission standard of 180 mg/dscm was
a problem for a number of the incin-
erators tested by EPA. Four of the eight
I units tested failed to meet the RCRA
standard. Two of those facilities were
marginally above the emission limit and
could likely meet the standard with mi-
nor operating adjustments. The re-
maining two facilities appeared to need
significant design and/or operational
changes."9 In some cases, failure of
the paniculate emission standard may
be attributed to dissolved neutraliza-
tion salts in mist carryover from al-
kaline acid gas scrubbers. It is clear,
however, that the paniculate emission
standard of 180 mg/dscm is achievable
if proper air pollution control is pro-
vided since at least 150 hazardous waste
incinerators have now demonstrated this
during their trial burns.
In fact, it appears that the technol-
ogy exists to reduce paniculate emis-
sions to substantially lower levels. In
a test of a full-scale PCB incinerator
equipped with a spray dryer/baghouse
followed by an ionizing wet scrub-
ber,"4 particulate emissions averaged
20 mg/dscm for one test condition and
109 mg/dscm for a second test condi-
tion. In another test of a full-scale haz-
ardous waste incinerator115 equipped
with a vcnturi/packed-bed wet scrub-
ber system, the paniculate emissions
averaged 48 mg/dscm. The particulate
emissions from a pilot-scale hazardous
waste incinerator113 ranged from 17 to
64 mg/dscm when it was equipped with
an ESP. When this system was equipped
with a Hydro-Sonic* wet scrubber, the
paniculate emissions averaged 10 mg/
dscm.
No significant changes in panicu-
late emissions were observed for in-
dustrial boilers and certain of the
industrial process kilns when they fired
waste fuels compared to emissions for
fossil fuels only.;20-121 Some increased
emissions were observed in kilns em-
ploying electrostatic precipitators for
particulate control. These increases were
attributed to changes in the electrical
resistivity of the panicles due to the
presence of increased chloride levels.
Adjustments in ESP operation should
correct this in most cases.
Metal Emissions
Metals are of possible concern in
waste incineration because of their
presence in many hazardous wastes and
because of possible adverse health ef-
fects from human exposure to emis-
sions. Those metals posing carcinogenic
risk include arsenic, cadmium, chro-
mium and beryllium. Among the non-
carcinogenic toxic metals are antimony,
barium, lead, mercury, silver and thal-
lium. It is anticipated that the noncar-
cinogenic toxic metals, nickel and
selenium, will also be regulated in the
near future.
Incineration may change the form
of metal fractions in waste streams, but
it will not destroy the elemental met-
als. As a result, metals are expected to
emerge from the combustion zone es-
sentially in the same total quantity as
the input. The principal environmental
concern therefore centers around where
and in what physical or chemical form
the metals exit the combustion system,
i.e., bottom ash, APCD residues or
stack emissions.
Most interest has traditionally fo-
cused on stack emissions of metals. In-
creasing attention, however, is now
being given to the quality of residuals
from incineration of metal-bearing
hazardous wastes since disposal of these
materials has become subject to LDR
Rules under HSWA.
Metals present in the feed to com-
bustion devices exit via several path-
ways. The mechanisms which control
the behavior of metals during inciner-
ation arc similar to those of other types
of combustion systems. Much of the
early knowledge on metal behavior in
combustion systems was based on coal
combustion research.122126
The inorganic portion of wastes
contains most of the metals and metal
44 • January 1993 • Vol. 43 • AIR & WASTE
G-21
-------
•es 127 |^uch ot Uie inorganic ma-
S^I remains inert during incineration
SmX »' particte,°*.P>m<»lal<
from hazardous waste incinerators is
SSposed mostly of oxides of silicon,
"on calcic and aluminum Typi-
"X from 1 to 10 percent of the par-
S LetRCRA regulated metals.-
A small fraction of this ash is entrained
hv the combustion gases, while the re-
mainder travels through the primary
combustion chamber and exits as bot-
tom ash. Some metals and metal spe-
cies are volatile and will vaporize at
the conditions found in incinerators.129
Vaporized metals can condense ho-
mogeneously into condensation nuclei
that grow into a very fine fume, or
they can condense heterogeneously onto
existing flue gas particulate.130 In both
mechanisms, the tendency is to enrich
(be found at higher "per mass" con-
centration) in fine paniculate.131 Un-
der another mechanism, metal species
may teact to form new compounds such
as metal chlorides, fluorides, oxides and
reduced species. These new com-
pounds are sometimes more volatile
than the original species and therefore
vaporize, after which they typically
undergo homogeneous condensa-
tion.12?-132-133
EPA has been developing a model
to aid in predicting the relative distri-
butions of trace metals in emissions and
discharges from incinerators.132-134 The
volatility temperature of the metal is
one of the principal input parameters
for this model. Volatility temperature
is the temperature at which the effec-
tive vapor pressure of the metal is 10-6
atmospheres. The effective vapor pres-
sure is the sum of the equilibrium va-
por pressure of all species containing
the metal.
The presence of chlorine can affect
the metal species and volatility tem-
perature. This is particularly true for
lead and nickel because the chlorides
of these metals are more volatile than
the species that would exist without
chlorine. The volatility temperatures
with 10 percent chlorine and without
chlorine for the 10 RCRA-regulated
metals, plus nickel and selenium, are
given in Table XIV.133 This reflects
the quantity of a metal that would va-
porize under a given set of conditions.
The lower the volatility temperature of
the metal, the more volatile it is ex-
pected to be.
Until recently, data on metal behav-
ior in hazardous waste incinerators were
quite limited. The focus of most emis-
sion assessments had historically been
on organic compounds. Over the past
several years, however, the body of
knowledge on incineration of metal-
bearing waste has been expanded sig-
nificantly. A number of EPA-spon-
sored studies have examined metals
partitioning (distribution among dis-
charge streams) and APCD collection
efficiencies.113"115-132-133-136-140
As part of its strategy to control metal
emissions, EPA has developed con-
servative estimates for partitioning of
metals within combustion processes
prior to the APCD.29 Table XV lists
these estimates for two temperatures
(1600°F and 2000°F) and two levels of
chlorine in the waste feed (0 and 1 per-
cent). Similarly, conservative metal
collection efficiencies have been esti-
mated for a number of different APCD
types and are listed in Table XVI.29
Actual stack data indicate that fabric
filter removal efficiencies are far higher
than 95% on most metals except mer-
cury. Effective mercury removal re-
quires gas cooling and high efficiency
wet scrubbers or carbon and a fabric
filter.
As noted in the EPA guidance doc-
ument on control of metal emissions,29
the conservative nature of the Tables
XV and XVI should be stressed. A
multitude of waste feed compositions
(for example, metal species concentra-
tions, chlorine concentrations, matri-
ces), incinerator designs (such as
combustion chamber and APCD) and
operating conditions (like temperature
profiles, oxygen concentrations, gas
velocities) will be encountered. This
Table XIV. Metal volatility temperatures.'"
Without Chlorine With 10% Chlorine
Volatility
Volatility
Temperature
Principal
Temperature
Principal
Metal
(°C)
Species
(°C)
Species
Chromium
1613
CrCyCrO,
1611
CrOj/CrOj
Nickel
1210
Ni (OH)j
693
NiClz
Beryllium
1054
Be (OH)2
1054
Be (OH)2
Silver
904
Ag
627
AgCI
Barium
849
Ba (OH)j
904
BaClj
Thallium
721
T1A
138
tioh
Antimony
660
SbjO,
660
SbjOj
Lead
627
Pb
-15
PbCl4
Selenium
318
Se02
318
Se02
Cadmium
214
Cd
214
Cd
Arsenic
32
As,0,
32
ASzOj
Mercury
14
Hg
14
Hg
Table XV. Conservative estimates of metals partitioning to APCD* as a function of
solids" temperature' (%).w
1600°F 2000°F
Metal"
Q
II
o
a = i%
Q
II
o
$
a = 1%
Antimony
100
100
100
100.
Arsenic
100
100
100
100
Barium
50
30
100
100
Beryllium
5
5
5
5
Cadmium
100
100
100
100
Chromium
5
5
5
5
Lead
100
100
100
100
Mercury
100
100
100
100
Silver
8
100
100
100
Thallium
100
100
100
100
* The remaining percentage is contained in the bottom ash of the incineraior.
6 Partitioning for liquids is estimated at 100% for all metals.
c The combustion gas temperature is estimated to be 100-400°F higher than the solids
temperature.
" Assumptions: Excess air = 50%; Entrainment = 5%; Waste Metals Content = 100
ppm for each metal. For a given set of combustion chamber conditions, the maximum
amount of metal which will be vaporized will become constant as the metal concentration
in the solids increase. As a result, higher concentrations of metals are expected to have
lower partitioning factors.
G-22
AIR & WASTE • Vol. 43 • January 1993 • 45
-------
FEATURE
Table XVI. Air pollution control devices and :heir conservatively estimated efficiencies
for controlling toxic metals.29
POLLUTANT
.APCD
Ba, Be
Ag
Cr
As, Sb, Cd,
Pb, T1
Hg
*WS
50
50
50
40
30
•VS-20
90
90
90
20
20
¦VS-60
98
98
98
40
40
ESP-1
95
95
95
SO
0
ESP-2
97
97
97
85
0
ESP-4
99
99
99
90
0
•WESP
97
97
96
95
60
•FF
95
95
95
90
50
*PS
95
95
95
95
80
SD/FF;SD/C/FF
99
99
99
95
90
DS/FF
98
98
98
98
50
•FF/WS
95
95
95
90
50
ESP-1/WS;ESP-1/PS
96
96
96
90
80
ES P-4/WS; ES P-4/PS
99
99
99
95
85
•VS-20/WS
97
97
97
96
80
•"WS/TWS
95
95
95
95
85
•WESP/VS-20/TWS
99
99
98
97
90
C/DS/ES P/FF; C/DS/C/ES P/FF
99
99
99
99
98
SD/C/ESP-1
99
99
98
95
85
It is assumed that flue gases have been precooled in a quench. If gases are not cooled
adequately, mercury recoveries will diminish, as will cadmium and arsenic to a lesser
extent.
An fWS is nearly always used with an upstream quench and packed horizontal scrubber.
C
WS
PS
VS-20
VS-60
ESP-1
ESP-2
ESP-4
WESP
IWS
DS
FF
SD
Cyclone
Wet Scrubber including: Sieve Tray Tower; Packed Tower; Bubble Cap
Tower
Proprietary Wet Scnibbcr Design (A number of proprietary wet scrubbers
have come on the market in recent years that are highly efficient on both
particulates and corrosive gases. Two such units are offered by Calvert
Environmental Equipment Co. and by Hydro-Sonic Systems, Inc.).
Venturi Scrubber, ca. 20-30 in W. G. AP
Venturi Scrubber, ca. > 60 in W. G. A?
Electrostatic Precipitator; 1 stage
Electrostatic Precipitator; 2 stages
Electrostatic Precipitator; 4 stages
Wet ESP
Ionizing Wet Scrubber
Dry Scrubber
Fabric Filter (Baghouse)
Spray Dryer (Wet/Dry Scrubber)
can result in significantly differing
partitioning and metals collection ef-
ficiency factors. Furthermore, it should
be noted that similar emission rates for
two different facilities may result in
two very different rates of human ex-
posure as a result of sitc-spccific dis-
persion factors. Emission rates must be
translated into exposure rates in order
to fully evaluate health impacts.
Since 1988, a number of parametric
metals partitioning studies have been
! carried out at EPA's Incineration Re-
search Facility (1RF) in Jefferson, Ar-
kansas. These studies examined the
effects of operating conditions and
j waste feed characteristics on the be-
! havior of a mixture of metals fed into
' a pilot-scale rotary kiln incinerator.
While the majority of the metals fol-
lowed their predicted behavior, some
did not.
Axsenic, for example, behaved quite
differently from what was expected. The
guidance document29 suggests a con-
servative assumption of 100 percent
arsenic partitioning to flue gas, yet as
much as 95 percent of the discharged
arsenic in the 1RF studies was ac-
counted for by the kiln ash fraction.137
Lead behavior also differed from ex-
pectations; its observed volatility
changed significantly between two test
series conducted under similar oper-
ating conditions. In the first test series,
an average of 20 percent of the re-
covered lead was accounted for by kiln
ash. But in the second test scries, much
more lead stayed in the kiln ash and
that fraction rose to greater than 80
percent.133 Research is continuing to
investigate this occurrence.
Consideration of specific waste feed
composition, incinerator operating
conditions, APCD type and site-spe-
cific dispersion modeling will assist in
the prediction of a waste feedrate that
will result in acceptable emissions un-
der EPA's current guidance. Unless
emission testing is conducted, it is
conservatively assumed that 100% of
the metals in the feed are emitted to
the air. Whether or not this fccdratc is
economically or practically feasible
must be determined on an individual
basis. Treatability tests of the waste
may be warranted.
Combustion Byproduct Emissions 1
The current RCRA incineration
standards regulate destruction and re-
moval only for the major hazardous
compounds in the waste. One of the
concerns expressed by some scientists
and environmentalists regarding haz-
ardous waste thermal destruction is the
possible impact on human health and
the environment of potentially hazard- 1
ous PIC emissions. While many of the
incinerator field tests conducted to date
have attempted to quantify byproduct .
emissions, these data have been criti- i
cized as being incomplete and insuf-
ficient for the purposes of a full risk
assessment.141'142 Testing has focused ]
largely on identifying Appendix VIII
organic compounds only. Comparison
of total hydrocarbon emissions with the
total quantity of specific organic com-
pounds identified in the emissions has
usually revealed that only a relatively
small percentage of the total hydrocar-
bon emissions may have been identi-
fied.143-144 However, major efforts have
been conducted to better understand the
composition of the total mass emis-
sions.113'41
Incomplete combustion byproducts
from hazardous waste incineration have
been recognized for some time. Early
pilot-scale studies of the thermal de-
struction of the pesticide, Kepone,
found emissions of hexachlorobenzcne
and several other "daughter products"
which had been predicted from pre-
vious laboratory-scale studies.146 Sim-
ilar thermal decomposition studies
followed for PCBs1 and dozens of
other compounds.148'151
Dellinger152 has conducted a com-
prehensive review of the status of re-
search concerning the emission of
organic PICs from hazardous waste in-
cinerators (HWls) and concluded that
these emissions were primarily caused
G-23
-------
by temporal or spatial excursions from
nominal incineration conditions. He
further concluded that low temperature
due to quenching, residence time short
circuits due to non-plug flow and/or
unswept recesses, and locally high
waste/oxygen concentrations ratios due
to poor microscale mixing or over-
loading were the most likely causes for
PIC emissions.
While the RCRA incinerator stan-
dards do not specifically regulate in-
complete combustion byproducts, this
issue has been considered during the
regulatory process. The January 1981
Phase I rule proposed that emissions
of incomplete combustion byproducts
be limited to 0.01 percent of the POHC
input to hazardous waste incinera-
tors.17 Although this proposal was never
adopted, the recently proposed amend-
ments to the hazardous waste inciner-
ation regulations include a provision to
control PICs by setting limits on pa-
rameters (CO or HC emissions) which
would assure that the device is oper-
ated under good combustion condi-
tions.21 While these amendments have
not been promulgated, this approach is
being implemented on a national basis
by permit writers using the "omni-
bus" authority (40 CFR 270.32). Re-
searchers, regulators and
environmentalists have pursued the
question of PICs, including various at-
tempts to analyze actual field perform-
ance.115''44'14^153'155 One of the basic
problems in assessing the results of
laboratory and, particularly, field stud-
ies of PIC emissions is the fact that
there is no standardized definition of
what a PIC is. While a POHC is de-
fined in the RCRA regulations, a PIC
is not. Thus, there is often confusion
even among scientists working in the
area. Strictly speaking, PICs are or-
ganic compounds which are present in
the emissions from the incineration
process, but which were not present or
detectable in the fuel or air fed to the
incinerator. In EPA's test program,
compounds were considered to be PICs
if they were regulated organic com-
pounds (that is listed in Appendix VIII
of CFR 40 Part 261) which were de-
tected in stack emissions, but not pres-
ent in the waste feed at concentrations
greater than 100 ppm.153
Compounds in the emission stream
which are identified as PICs may ac-
tually result from any one of the fol-
lowing four phenomena:
(1) Compounds resulting from the
incomplete destruction of the
POHCs, such as fragments of
the original POHCs.
(2) New compounds "created" in
the combustion zone and down-
stream as the result of partial
destruction followed by radical-
molecule reactions with other
compounds or compound frag-
ments present. These com-
pounds may also result from the
incomplete combustion of non-
Appendix VIII compounds in the
waste. This aspect may be es-
pecially significant where fossil
fuel is used in incineration and
where waste is fired into con-
ventional industrial furnaces as
only a percentage of the heat
input.
(3) An Appendix VIII compound
originally present in the feed
stream before incineration but
not specifically identified as a
POHC.
(4) Compounds from other sources,
such as ambient air pollutants in
combustion air. In some field
tests, compounds identified in
the stack emissions as PICs were
actually found to have come
from contaminants (trihalome-
thanes) in the potable water used
for scrubber water make-up.133
Given the complexity of sources of
potential PIC compounds, it is not sur-
prising that a consensus PIC definition
has been difficult to achieve. Conse-
quently, for the purpose of this review,
it seems more productive to examine
the issue of combustion byproducts
separately from any type of specific
definition by ignoring the source or
cause of the emission of particular
compounds and considering all or-
ganic compound emissions (including
POHCs) as combustion byproducts
(CBPs). An earlier EPA study exam-
ined CBPs in this fashion.144 TTie study
examined field test data from 23 EPA-
sponsored emissions tests at thermal
destruction facilities. Included were
eight incinerators, nine industrial boil-
ers and six industrial kilns. Organic
emissions from hazardous waste facil-
ities were compared to emissions when
these facilities were burning fossil fuel
only. The organic emissions were also
compared to organic emissions from
municipal solid waste incinerators and
coal-fired utility boilers.
This EPA study of thermal destruc-
tion systems identified 55 Appendix
VIII compounds (28 volatile and 27
semivolatile) in stack emissions. This
and other emission data have been used
to generate a list (Table XVII)27 of or-
ganics that could potentially be emit-
ted from devices burning hazardous
waste. These compounds were emitted
at normalized rates that span over five
orders of magnitude, 0.09 to 13,000
nanograms of emissions per kilojoule
(ng/kJ) of combustor heat input (one
ng/kJ = 2.34 X 10"6lb/million Btu).
The greatest number of compounds
were emitted in the 10 to 100 ng/kJ
range. Only nine of the 23 facilities
emitted identified hazardous com-
pounds at rates exceeding 100 ng/kJ.
The volatile compounds tended to
be detected more often, and in signif-
icantly higher concentrations, than the
semivolatile compounds. The com-
pounds that occurred most frequently
and in the highest concentrations, nine
volatile and six semivolatile, are in-
dicated in Table XVII. Emission rates
for incinerators, boilers and kilns are
shown in Table XVIII for 12 of these
compounds for which sufficient data
were available for comparison. The data
show that values from test run to test
run varied considerably. Thus, these
data do not allow prediction of levels
for all three combustion devices. Many
of the volatile compounds showed
higher levels for boilers, and semivo-
latile compounds tended to be higher
for incinerators than boilers. However,
most of the organic compound mass
emitted from hazardous waste incin-
erators are volatile compounds.155
Data were also available from sev-
eral baseline (no waste firing) tests on
boilers and kilns which allowed com-
parison of emissions from hazardous
waste combustion with combustion of
other fuels. While there was a wide
range in values from test to test, the
data suggested that there is little in-
herent difference between waste and
fuel combustion emissions.144
Sufficient data for five semivolatile
compounds were available to compare
their emissions when burning hazard-
ous waste versus their emissions from
municipal incinerators and coal-fired
power plants. Similar data were not
available for volatile compounds. Ta-
ble XIX presents this comparison. The
four phthalate compounds in the table
show very similar emission rates from
all three sources. The phthalate rates,
however, should be viewed with cau-
tion since they can be artifacts of lab-
oratory contamination. Naphthalene
emissions were lower for power plants
than the other two sources. Again, the
data suggest that for these compounds
there is little inherent difference among
the emissions from these different
combustion sources.
In most of these studies, however,
only a portion of the organic mass
emissions has been identified. Many
G-24
AIR 4 WASTE • Vol. 43 • January 1993 • 47
-------
FEATURE
believe that most of this unidentified
mass is non-chlorinated C,-C5 hydro-
carbons, many of which tend to be of
lesser concern from a risk standpoint.
In an EPA test of a full-scale hazard-
ous waste incinerator it was found that
most of the organic mass in the stack
gas (80.7% average) was C.-C, vola-
| tile compounds. In a test of a full-
scale rotary kiln hazardous waste in-
cinerator, EPA attempted to identify
the total mass emissions of all organics
under both steady and nonsteady state
conditions.143 Between 53 to 91 per-
cent of the organic emissions were
identified. Methane and ethylene ac-
counted for 33 to 97 percent of the
identified organic emissions. While it
is recognized that these results are only
Volatile Compounds
Benzene'
Toluene'
Carbon tetrachloride*
Chloroform'
Methylene chloride*
Trichloroethylene*
Tctrachlorocthylcne'
1,1,1 -Trichloroethane*
Chlorobenzene*
cis-1,4-Dichloro-2-butene
Bromochloromethane
Bromodicnloromethane
Bromoform
Bromomethane
Methylene bromide
Meihyl ethyl ketone
¦ Most frequently detected organics.
representative of emissions from the
particular facility tested, they do sup-
port the belief that a large percentage
of the organic emissions are the non-
chlorinated, low molecular weight hy-
drocarbons. Additional testing is needed
to more completely characterize emis-
sions. However, such testing is very
expensive. The described test cost ap-
proximately 5700,000.
EPA has analyzed its historical data
base on emissions of individual or-
ganic compounds from hazardous waste
incinerators, boilers and industrial fur-
i naces.77 This information was used to
| develop a "reasonable worst-case"
' emission concentration for specific or-
ganic compounds from these devices.
I For each Appendix VIII compound
Semivolatile Compounds
Bis(2-cthylhexyl)phthalate*
Naphthalene'
Phenol*
Diethylphthalate*
Butylbenzylphthalate*
Dibutyl phthalate*
2-4-Dimethylphenol
o-Dichlorobenzene
m-Dichlorobenzene
p-Dichlorobenzene
Hcxachlorobenzcne
2,4,6-Trichlorophenol
Fluoranthene
o-Nitrophenol
1,2,4-Trichlorobenzene
o-Chlorophenol
Pentachlorophenol
Pyrene
Dimethyl phthalate
Mononitrobenzene
2,6-Toluene diisocyanate
identified in the emissions data base,
it was assumed that that compound was !
emitted at its 95th percentile concen-
tration level. This was further ex-
panded by including methane and
ethane emissions from fossil fuel com-
bustion and formaldehyde concentra-
tion from municipal waste incinerators,
also at their 95th percentile concentra-
tion. In addition, compounds which had
not been detected from hazardous waste
combustion but for which health ef-
fects data are available were assigned
a value of 0.1 ng/L. Table XX pro-
vides the 95th percentile concentration
level for the major organics that were
determined by this approach. It is in-
teresting to note that C, and C, hydro-
carbons account for almost 68 percent
of the total organic emissions. Ben-
zene, methylene chloride, chloroform,
formaldehyde, chloromethanc, 1,2-
I dichloroethane and toluene accounted
for most (over 28 percent) of the bal-
ance of the emissions. Again, it should
be stressed that these values are rea-
j sonable worst-case estimates and ac-
tual emissions would likely be lower
for most facilities.
Oloxln and Furan Emissfonsm
Without doubt, the greatest amount
of scientific and public attention has
been given to one class of incinerator
combustion byproducts, the dioxins and
furans. Dioxins are members of a fam-
ily of organic compounds known
chemically as dibenzo-p-dioxins. This
family is characterized by a three-ring
nucleus consisting of two benzene rings
interconnected by a pair of oxygen at-
oms. The structural formula of the
dioxin nucleus and the convention used
in numbering its substituent positions
are shown in Figure 7.156 Usually, the
Table XVII. Organics that could potentially be emitted from devices burning hazardous
waste.1'
Table XVIII. Emission rates of specific compounds from incinerators, boilers, and kilns, ng/kJ.'1'"
Incinerators Boilers Industrial Furnace Kilns
Mean
Range
Mean
Range
Mean
Range
Benzene
87
2-980
30
0-300
580
290-1,000
Toluene
1.6
.1.5-4.1
280
0-1,200
b
b
Carbon tetrachloride
0.8
0.3-1.5
1.8
0-7.2
b
b
Chloroform
3.8
0.5-8.4
120
0-1,700
b
b
Methylene chloride
2.2
0-9.6
180
0-5,800
b
b
Trichloroethvlene
5.2
2.3-9.1•
1.2
0-13
1.3
0.7-2.8
Tetrachloroethylene
0.3
0-1.3
63
0-780
b
b
1,1,1 -T richloroethane
0.3
0-1.3
7.5
0-66
2.4
(One value)
Chlorobenzene
1.2
0-6.0
63
0-1,000
152
33-270
Naphthalene
44
0.7-150
0.6
0.3-2.1
b
b
Phenol
7.8
0-16
0.3
0-0.8
0.02
0-0.05
Diethylphthalate
3.7
2.8-4.8
0.4
0.04-1.6
b
b
" Expressed as ng of emission per kJ of combustor heat Input (1 ng/kj = 2.34 x lO-'Ib/MM Btu).
" No data.
48 • January 1993 • Vol. 43 • AIR & WASTE
G-25
-------
Table XIX. Semivolatile compound emission rates from hazardous waste combustion,
municipal incinerators, and coal power plants, ng/kj.* '"
Hazardous Waste Municipal Waste Coal Power Plant
Mean Range Mean Range Mean Range
Naphthalene
17
0.3-150
71
0.4-400
0.5
0.06-1.8
Bis(2-ethylhexyl)phthalate
4.6
0-21
4.6
0.4-12
7.6
0.2-24
Diethylphthalate
1.2
0.04-4.8
0.5
0-0.9
2.8
0.4-5.7
Butylbenzphthalate
3.7
0.7-23
b
b
0.5
0.3-1.0
Dibutylphthalate
0.3
0-1.1
3.9
1.5-7.6
3.0
0.09-8.7
¦ Expressed as ng of emission per kJ of combustor heat input (1 ng/kj = 2.34 x 10-6lb/
MM Btu).
6 No data.
Table XX. Reasonable worst case emissions of specific organics from incinerators, boil-
ers and industrial furnaces burning hazardous wastes.77
Carcinogenic Emission' Percent of Total
(Y/N) (ng/L) (%)
C2 Hydrocarbons
N
17000
43.3
CI Hydrocarbons
N
9600
24.5
Benzene
Y
4928
12.6
Methylene Chloride*
Y
1755
4.5
Chloroform
Y
1407
3.6
Formaldehyde
Y
892
2.3
Chloromethane
Y
807
2.1
1,2-Dichloroethane
Y
714
1.8
Toluene
N
551
1.4
Tetrachloroethylene
Y
297
0.76
Chlorobenzene"
N
195
0.50
2,4,5-Trichlorophenol
N
144
0.37
Naphthalene6
N
130
0.33
Carbon Tetrachloride
Y
99.5
0.25
o-Dichlorobenzene
N
95
0.24
p-Dichlorobenzene
N
86
0.22
Trichloroethylene
Y
81.8
0.21
bis(2-Ethylhexyl) Phthalate
Y
77.7
0.20
1,2,4-Trichlorobe nze ne
N
77
0.20
1,1,1 -Trichloroethane"
N
64
0.16
1,1,2-Trichloroethane
Y
36.7
0.094
Methyl Ethyl Ketone
N
33.2
0.085
Phenol
N
33.1
0.084
1,1-Dichloroethylene
Y
31.6
0.081
Diethyl Phthalate
N
31
0.079
1,1,2,2-Tetrachloroethane
Y
17
0.043
Vinyl Chloride
Y
14
0.036
Pentachlorophenol
N
9.3
0.024
Hexachlorobenzene
Y
8.95
0.023
Dibutyl Phthalate"
N
3.6
0.0092
1,1-Dichloroethane
Y
3.37
0.0086
Butylbenzyl Phthalate"
N
3
0.0076
Bromomethane
N
2.13
0.0054
Dichlorodifluoromethane
N
1.22
0.0031
Benzo(a)Anthracene
Y
1.10
0.0028
2,4-Dichlorophenol
N
0.50
0.0013
Acetonitrile
N
0.26
0.00066
TCDF
Y
0.00141
0.0000036
PCDD
Y
0.10246
0.00026
Other Carcinogens
Y
4.6
0.0117
Other Noncarcinogens
N
2.8
0.007
Totals
39240
• May be due to laboratory contamination.
^ Values estimated from Reference 126.
95th percentile concentration levels.
term "dioxin" refers to the chlori-
nated congeners of dibenzo-p-dioxin.
Theoretically, one to eight chlorine at-
oms can occur at dioxin substituent po-
sitions such that 75 chlorinated dioxin
congeners are possible.
Furans are members of a family of
organic compounds known chemically
as dibenzofurans. They have a similar
structure to the dibenzo-p-dioxins ex-
cept that the two benzene rings in the
nucleus are interconnected with a five-
member ring containing only one oxy-
gen atom. The structural formula of
the furan nucleus and the convention
used in numbering its substituent po-
sitions are shown in Figure 8.156 As
with dioxins, the term "furan" nor-
mally refers to the chlorinated conge-
ners of dibenzofurans. Theoretically,
135 chlorinated furan congeners are
possible. From a human health hazard
viewpoint, the polychlorinated di-
benzo-p-dioxin (PCDD) and the poly-
chlorinated dibenzofuran (PCDF)
compounds (specifically, their "tetra"
and "penta" forms) are the most sig-
nificant. Polychlorinated, as used here,
means the compound contains four or
more chlorine atoms.
Initially, most concern was focused
on 2,3,7,8-tetrachlorodibenzo-p-dioxin
(2,3,7,8-TCDD). Over the last 20 years,
many studies have been conducted to
elucidate the toxic effects of 2,3,7,8-
TCDD. The data from these studies are
summarized in a number of re-
views.157"161 While these data have not
answered all of the questions, the data
do show that 2,3,7,8-TCDD can pro-
duce a variety of toxic effects, includ-
ing cancer and reproductive effects, in
laboratory animals at very low doses.
While some reports in the literature
suggest that the chemical can produce
similar effects in humans, more defin-
itive information is needed.162 Finger-
hut et al.163 recently conducted a study
of mortality among 5,172 workers at
12 plants in the United States that pro-
duced chemicals contaminated with
TCDD and did not find a significant
increase in cancers for this group.
For risk assessment purposes, EPA
currently classifies 2,3,7,8-TCDD as a
"B2" carcinogen with a potency of
1.6 x 105 (mg/kg-d)-1, by far the most
potent carcinogen yet evaluated by the
Agency.159 The B2 category is one of
five categories that EPA uses to group
the weight of evidence of the carcin-
ogenicity of a chemical for humans.
These are further defined below:164
G-26
AIR & WASTE • Vol. 43 • January 1993 • 49
-------
FEATURE
Group A: There is sufficient evi-
dence from epidemio-
logic studies to support
a causal association be-
tween exposure to the
' chemical agent and can-
cer.
Group Bl: The weight of evidence
of carcinogenicity based
on animal studies is
"sufficient" but there
is limited evidence of
carcinogenicity from
epidemiologic studies.
Group B2: The weight of evidence
of carcinogenicity based
on animal studies is
"sufficient" but there
is "inadequate evi-
dence" or "no data"
from epidemiologic
studies.
Group C: There is limited evidence
of carcinogenicity in an-
imal studies but no hu-
man data.
> Dioxln Configuration
1
2
D benzo
Hgura 7. Structfal formula of Die dioxln nucleus.
Group D: Not classified as to hu-
man carcinogenicity be-
cause there is inadequate
human and animal evi-
dence of carcinogenicity
or no data available.
Group E: Not a human carcinogen.
The compound 2,3,7,8-TCDD is
also the most potent reproductive toxin
yet evaluated by the Agency, with a
RfD of 1 pg/kg-d.15' More recently, it
has been suggested by some scientists
that the Agency's health standards for
this chemical are not supported by the
latest scientific evidence. The U.S. EPA
has undertaken a review to reassess the
toxicity of 2,3,7,8-TCDD which might
result in a revision of risks assigned to
it.165
In order to address the risks posed
by other chlorinated dibenzo-p-dioxins
and chlorinated dibenzofurans (CDDs
and CDFs), in the spring of 1987 the
EPA first adopted an interim proce-
dure for estimating the hazard ana dose-
response of complex mixtures contain-
ing CDDs and CDFs in addition to
Dibenzofuran Configuration
Rgore a. Structural formula cf Die furan nucleus.
Table XXI. International toxicity equivalency factors/89 (I-TEFs/89).'
Compound
I-TEFs/89
Mono-, Di-, and TriCDDs
()
2,3,7,8-TCDD
1
Other TCDDs
0
2,3,7,8-PeCDD
0.5
Other PeCDDs
0
2,3,7,8-HxCDDs
0.1
Other HxCDDs
0
2,3,7,8-HpCDD
0.01
Other HpCDDs
0
OCDD
0.001
Mono-, Di-, and TriCDFs
0
2,3,7,8-TCDF
0.1
Other TCDFs
0
1,2,3,7,8-PeCDF
0.05
2,3,4,7,8-PeCDF
0.5
Other PeCDFs
0
2,3,7,8-HxCDFs
0.1
Other HxCDFs
0
2,3,7,8-HpCDFs
0.01
Other HpCDFs
0
OCDF
0.001
2,3,7,8-TCDD.166 This procedure was j
based upon a set of derived toxicity
equivalency factors (TEFs) which per-
mit the conversion of any CDD/CDF
congener into an equivalent concentra-
tion of 2,3,7,8-TCDD or Toxicity
Equivalents (TEQs). In 1989, the EPA
updated this procedure by adopting the
International TEFs (I-TEFs/89) which
are given in Table XX].162 As can be
seen in the table, the relative toxicities
of the other 209 congeners of dioxins
and furans range from 0 to 50 percent
of the toxicity of 2,3,7,8-TCDD.
Therefore, the combined toxicity of a
mixture of PCDD/PCDFs is highly de-
pendent on the specific isomers that
constitute that mixture.
With the exception of analytical
standards, dioxins and furans are not
intentionally made for any purpose.
They can, however, be created as by-
products in the manufacture of other
chemicals (such as some pesticides) or
as a result of incomplete combustion
or the recombination of exhaust prod-
ucts from the burning of mixtures con-
taining certain chlorinated organic
compounds. Since the first published
report of PCDD and PCDF emissions
from a municipal solid waste inciner-
ator by Olie et al.167 a large number
of studies have been carried out to ex-
amine this phenomenon. Some of this
initial work was reported by Buser a
at.,"* Eiceman et al.,169 Karasek,™
Bumb et al.,171 Cavallaro et al.,172 and
Lustenhouwer et al.173 Over the past
10 years, numerous studies have con-
tinued to investigate this issue and
PCDD/PCDFs have been the focus of
many national and international sym-
posia and conferences.174
A large part of the interest has been
placed on municipal solid waste incin-
eration. A number of excellent sum-
maries of municipal solid waste
incinerator emission data have been
prepared.175 178 EPA has reviewed
PCDD/PCDF emissions data for a broad
range of combustion sources, includ-
ing fossil fuel and wood combustion
and a wide range of industrial fur-
naces,'55 and has reported the results
of emissions testing at 13 additional
facilities.179
EPA full-scale hazardous waste tests
have examined dioxin/furan emissions
at six incinerators,107 five industrial
boilers,180 two cement kilns181-182 and
a lime kiln1"3 employing hazardous
waste as a fuel. Data are also available
from test burns at one incinerator burn-
ing pentachlorophenol (PCP) waste184
and three PCB incinerators.133-186
Dioxin/furan emission data are also
available from a pilot-scale treatability
50 • January 1993 • Vol. 43 • AIR & WASTE
G-27
-------
test of PCB-contaminated soil from a
Superfund site.187 More recent dioxin/
furan emission data are available for
municipal waste combustors (MWCs)
and medical waste incinerators (MWIs)
as a result of EPA testing to support
the development of regulations for these
sources.18®"190 Dioxin/furan emissions
from all of these sources are summa-
rized in Table XXII. In addition, these
emissions are expressed in I-TEQs/89
in both concentration and mass per year.
No 2,3,7,8-TCDD was detected in
any of the 10 full-scale hazardous waste
incinerators or three industrial fur-
naces burning hazardous or PCB waste.
The compound 2,3,7,8-TCDD was de-
tected at the detection level of 0.002
ng/dscm in one series of tests at In-
dustrial Boiler D and at .003 ng/dscm
for the pilot-scale treatability tests.
Detectable levels of PCDD or PCDF
were found at five of the hazardous
waste incinerators and all five of the
industrial boilers. No PCDD or PCDF
was found at any of the three industrial
furnaces. By comparison, 2,3,7,8-
TCDD, PCDDs and PCDFs have been
detected frequently in MWI and MWC
emissions at levels that are three to four
orders of magnitude higher than emis-
sions reported from HWIs, industrial
boilers and industrial furnaces burning
hazardous wastes.
Recent testing188-190 has demon-
strated, however, that through the
combination of good combustion prac-
tices and flue gas cleaning, dioxin/furan
emissions from MWCs can be dra-
matically reduced to levels that are
about the same as to somewhat higher
than those reported for hazardous waste
Table XXII. Dioxin/furan emissions from thermal destruction facilities (ng/dscm @ 1% O,).
Sample
I-TEQs/89<
Facility Type'
(Waste)6
2378-TCDD
PCDD
PCDF
ng/dscm
g/yr"
Ref.
HWI (Commercial, Rotary Kiln, Liquid Injection)
FG' (HW)
ND'
ND
ND
ND
ND
107
HWI (Confidential)
FG/FA (HW)
ND
22
70
17.7
1.95
107
HWI (On-site Liquid Injection)
FG (HW)
ND
ND
7.3
0.93
0.02
107
HWI (On-site Liquid Injection)
FG (HW)
ND
ND
ND
ND
ND
107
HWI (Commercial, Two Chamber, Liquid
FG/FA (HW)
ND
ND
1.7
0.57
0.02
107
Injection and Hearth)
HWI (On-site Kiln and Liquid Injection in
FG (HW)
ND
ND
ND -
ND
ND
107
Parallel)
HWI (Liquid Injection, Incinerator Ship)
FG/FA (PCB)
ND
ND
ND
0.3
0.16
185
HWI (Fixed Hearth)
FG/FA (PCP)
ND
ND
ND
ND
ND
184
HWI (Liquid Injection)
FG/FA (PCB)
ND
0.64
9.9
1.63
0.81
186
HWI (Rotary Kiln/Liquid Injection)
FG/FA (PCB)
ND
0.18
2.1
0.39
0.12
186
HWI (Pilot-scale Rotary Kiln)
FG/FA (PCB)
.003
.108
3.18
.073
.001
187
Cement Kiln
FG (HW)
ND
ND
ND
ND
ND
181
Cement Kiln
FG (HW)
ND
ND
ND
ND
ND
182
Lime Kiln
FG/FA (HW)
ND
ND
ND
ND
ND
183
Industrial Boiler/A (Watertube Stoker)
FG/FA (PCP)
ND
75.5
NR8
10.5
0.84
180
Industrial Boiler/D (Converted Stoker)
FG/FA (HW)
ND-.002
0.64-0.8
0.24-5.5
0.45
0.12
180
Industrial Boiler/E (Packaged Watertube)
FG/FA (HW)
ND
ND
0.14
0.01
0.0026
180
Industrial Boiler/M (Tangentially Fired
FG/FA (HW)
ND
ND
0.81
0.11
NA"
180
Watertube)
Industrial Boiler/L (Packaged Watertube)
FG/FA (HW)
ND
1.1
2.5
0.336
NA
180
MWC/A
FG/FA (MW)
0.5
41.2
202
22.22
24.70
179
MWC/B
FG/FA (MW)
20.2
4980
9022
2628.9
729.79
179
MWC/C
FG/FA (MW)
NR
35.8
93.3
9.07
NA
179
MWC/D
FG/FA (MW)
0.6
552
117
140.2
74.00
179
'MWC/E
FG/FA (MW)
12.4
3344
4122
1704
142.66
179
MWC/F
FA/FA (MW)
NR
163
194
34.8
NA
179
MWC/Mass Bum (SDA/FF)'
FG/FA (MW)
NA
1.01
1.19
0.079
NA
188
MWC/Mass Bum (SDA/ESP)'
FG/FA (MW)
NA
15.6
60.4
1.159
NA
188
MWC/Refuse Derived Fuel (SDA/FF)
FG/FA (MW)
NA
0.271
0.375
0.005
NA
188
MWI/A (Lime Injection/FF)
FG/FA (MdW)
0.11
92.78
1655
10.81
0.14
189
MWI/B (Venturi/Packed Beed)
FG/FA (MdW)
0.07
62.88
342
7.59
0.30
189
MWI/K (No APCD)
FG/FA (MdW)
12.3
3000
14300
435.18
3.84
189
MWI/W (No APCD)
FG/FA (MdW)
3.79
714
3740
123.16
1.44
189
* HWI = Hazardous Waste Incinerator; MWI = Medical Waste Incinerator; MWC
' = Municipal Waste Combustor.
' Information in parentheses describes waste feed; HW = hazardous waste; PCB = polychlorinated biphenyls; PCP = pentachlorophenol
waste; MdW = medical waste; MW = municipal waste.
: Calculated by the International Toxicity Equivalency Factor/89 (I-TEF/89) method. If isomer specific data was not available, homologue
data were considered to be composed of the most toxic isomers.
' Assumes 8160 operating hours per year.
' FG = flue gases analyzed; FA = flue gas particulate analyzed.
1 ND = not detected.
¦ NR = not reported.
" NA = Not available. .
1 SDA/FF = spray dryer absorber/fabric filter.
1 ESP = electrostatic precipitator.
G-28
AIR & WASTE • Vol. 43 • January 1993 • 51
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FEATURE
incinerators. On February 11, 1991, the
emission standards for new MWCs and
guidelines for existing facilities were
promulgated and became effective on
August 12, 1991.13 The specific dioxin/
furan stack emission limits arc a func-
tion of the facility's size and age and
range from 30 to 250 ng/dscm of total
PCDDs and PCDFs (see Table I). It is
expected that current efforts to develop
emission standards for MWls191 may
also result in design and operational
improvements which will effect a re-
duction of dioxin/furan emissions from
these facilities as well.
From a human health risk view-
point, the mass of toxicity equivalents
emitted is the best indication of the
threat posed by these emissions. How-
ever, calculation requires identifica-
tion of all of the specific isomers given
in Table XXI. If isomer-specific data
are not available, homologue data are
considered to be comprised of the most
toxic isomers. With the exception of
the MWls and three of the MWCs188
in Table XXII, isomer-specific data
were not available and the I-TEQs/89
are, therefore, conservative.
Using an even more conservative
approach, risk assessment calculations
for dioxin/furan emissions from two
HWls burning PCBs concluded that
these emissions did not pose a signif-
icant risk based on excess lifetime can-
cer risk to the MEI of 1.8 x 10~5 and
3.9 x 10"7.18* Dioxin/furan emissions
levels from these two facilities are at
the high end of the range of emissions
measured from hazardous waste incin-
erators. The lower levels of emissions
found at other facilities burning haz-
ardous waste are not believed to create
a significant risk to human health.
Ash and Air Pollution Control Residue
Quality
Facilities which incinerate hazard-
ous waste containing significant ash or
halogen contents will generate com-
bustion chamber bottom ash and var-
ious types of residues collected by
subsequent APCDs. Operators must
assess these materials to determine
proper methods of disposal.
Since APCDs using wet collection
methods predominates incinerator
practice, fly ash and haloacids (like
HC1) are often collected in aqueous ef-
fluents from a scrubber, absorber or
wet ESP. The principal contaminants
of interest in these APCD residues and
incinerator bottom ash are heavy met-
als and trace levels of undestroyed or-
ganic material.
Currently under RCRA, the incin-
eration of a listed hazardous waste re-
sults in the generation of ashes and
residues which bear the same listed-
wastc code as the parent waste. This
"derived from" rule has been chal-
lenged in court, however, and is under
review. Currently, these "derived
from" listed-waste ashes and residues
are subject to LDR regulations, which
specify a concentration level that must
be met or a treatment technology that
must be applied prior to placement of
the materials in landfills. Further, fa-
cilities incinerating any hazardous waste
musi determine if the materials gen-
erated during such incineration exhibit
any of the four hazardous characteris-
tics defined in the regulations (i.e., ig-
nitability, corrosivity, reactivity and
toxicity). Among the more compre-
hensive of the tests for hazardous char-
acteristics is the Toxicity Characteristic
Leaching Procedure (TCLP),1'2 de-
signed to measure the concentration of i
a number of contaminants in a waste |
extract. !
Some characterization data are
available for combustion chamber ash
and air pollution control residues which
were generated by the incineration of
a wide variety of wastes under a wide
variety of conditions. Combustion
chamber ash and scrubber water were
analyzed for several of the incinerators
tested by EPA as part of the incinera-
tion Regulatory Impact Analysis (RLA)
program.107 In additional testing, 10
incinerators were sampled to charac-
terize ash and residues.1'3 Incinerator
ash and residues were also character-
ized as part of BDAT incineration tests
under both RCRA and CERCLA,194-
201 as well as during demonstration
testing under the Superfund Innovative
Technology Evaluation (SITE) pro-
nn
gram.
In the RLA study,107 incinerator ash
and scrubber waters were analyzed for
organic constituents. Only two facili-
ties had ash concentrations of organic
compounds at levels greater than 35
p.g/g. When organic compounds were
detected, they tended to be toluene,
phenol or naphthalene at concentra-
tions less than 10 H-g/g. The same
compounds were also detected in
scrubber waters, usually at concentra-
tions below 20 M-g/L. :
The results of the 10-incinerator test |
program generally confirmed the RIA '
results.1" While more organic com-
pounds were detected across all of the
facilities (19 volatile and 24 semivo-
latile organic compounds), levels in ash
were typically at or well below 30 p.g/
g. More compounds were detected in
scrubber waters across the 10 facilities
than in the RIA study (nine volatiles
and five semivolatiles) and in higher
concentrations. Semivolatiles ranged
from 0 to 100 (igT-, while volatile
compounds were much higher (0 to 32
mg/L).
Combustion chamber ash and
scrubber waters were also analyzed for
metals in these studies. Detected con-
centrations varied widely and were a
function of facility operating condi-
tions, residue processing and the amount
of metal in the input waste stream,
among other variables. Metals most
frequently detected in the ash were
chromium, zinc, copper, nickel, lead,
arsenic and silver.203
While the majority of the metals in
the TCLP extracts of the residues were
at concentrations below lhe standards
which define a waste as characteristi-
cally hazardous, disposal of the ma-
terial is often subject to more restrictive
LDR standards which are not always
met. When compared to the most strin-
gent of the "land ban" treatment stan-
dards, ash and scrubber wastewater
from conventional incinerators yielded
TCLP extracts which often exceeded
the limits, particularly those for met-
als. Among metals which most fre-
quently exceeded these limits were
arsenic, nickel and lead. This suggests
that wastes subject to land disposal
standards may require further treat-
ment (such as stabilization or precipi-
tation) prior to disposal.201 High-
temperature "slagging" incinerators
have shown some promise in produc-
ing ash with reduced metal leachabil-
jjy_ 204.205
Overall, the data indicate that very
small amounts of residual organic
compounds remain in incinerator ash
and APCD residues. Thus, destruction
and removal efficiencies reported for
incinerators are almost entirely the re-
sult of destruction, rather than re-
moval, of organic compounds. Levels
of metals in ashes and APCD residues,
and in their TCLP extracts, varied
widely but generally do not appear to
exhibit RCRA toxicity characteristics.
In contrast, some TCLP extracts are
likely to exceed the more restrictive
standards associated with the LDR
rules. It should be recognized that the
available data represent short-term
samples from less than 10 percent of
the total hazardous waste incinerator
population in the United States. Use of
these data to project residue and ash
quality for specific waste/incinerator
combinations is not possible. Metals
and organic concentrations are highly
waste- and facility-specific and will
52 • January 1993 • Vol. 43 • AIR & WASTE
G-29
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FEATURE
parameters are based on equipment
manufacturers' design and operating
specifications. They are set indepen-
dently of trial burn results and are not
linked with the automatic waste feed
cutoff.
Operating conditions (such as com-
bustion temperature and 02 and CO in
stack emissions) must be used as sur-
rogates for continued high destruction
performance after the trial bum since
there is currently no real-time method
to determine DRJE for specific POHCs.
DRE can only be determined with cer-
tainty via expensive, multi-day testing
procedures. Similarly, parameters re-
lated to the specific APCD are used as
surrogates to assure HQ removal and
particulate control. Although, CEMs
are available for HC1 monitoring. An-
alytical results often take weeks or
months to generate. EPA believes the
current permitting approach is reason-
able and protective of human health
and the environment. But many argue
that the availability of additional real-
time monitoring techniques to detect
process upsets and alert operators to
automatically take corrective action
would significantly increase public ac-
ceptance of thermal destruction tech-
nology.
Two general classes of performance
estimation techniques exist. The first
of these involves the use of com-
pounds which are either identified in
the waste or added to it to serve as
"surrogates" for the destruction of other
important compounds in the waste. The
second approach involves the use of
indicator emissions such as CO or un-
bumed hydrocarbons to minor waste
destruction efficiency. A combination
of both concepts are currently used to
some extent in incinerator permitting.
Surrogates
The surrogates concept involves
identifying an easily detected organic
compound or compounds which are
more difficult to thermally destroy than
any of the other hazardous compounds
in the waste feed mixture. It is then
assumed that if destruction efficiency
for this compound is known for a given
facility then all other compounds in the
waste will be destroyed to at least that
degree. Therefore, this concept in-
volves developing an incinerability
ranking of compounds.
The RCRA permit guidance for se-
lecting POHCs in wastes actually em-
ploys this approach along with other
considerations. It is recommended that
a group of POHCs be chosen based on
a variety of considerations including
incinerability, concentration in the feed
and compound structure. Identifying
compound incinerability has proven
difficult, however, and sometimes un-
reliable. EPA originally suggested the
use of compound heat of combustion
(AHC) as a ranking of compound in-
cinerability. 19 This ranking method has
received considerable criticism206 and
alternative methods, some of which
have also been criticized, have been
proposed. These ranking approaches
have been reviewed and compared by
Dellinger.207 They include autoigni-
tion temperature,208 theoretical flame
mode kinetics,209 experimental flame
failure modes,210 ignition delay time,211
and gas-phase (nonflame) thermal sta-
bility.206-212,213 The rankings of com-
pounds by each of these indices were
compared to their observed incinera-
bility in actual waste incineration tests
in 10 pilot- and field-scale units.207 Each
index failed to adequately predict field
results except for the nonflame thermal
stability method. This method, based
on experimentally determined thermal
stability for mixtures of compounds
under low oxygen concentration con-
ditions, showed a statistically signifi-
cant correlation for the compounds
evaluated.
While the low oxygen thermal sta-
bility (TSLo02) concept appears
promising, bench-scale data are only
available for approximately half of the
Appendix VIII organic compounds.
Correlation for other important Appen-
dix VIII compounds over a range of
compound concentrations is needed to
fully understand the potential utiliza-
tion of this incinerability ranking ap-
proach. In recent tests carried out at
both pilot- and full-scale levels, the
TSLo02 (or "pyrolytic") Incinerabil-
ity Ranking Index was investi-
gated.214-213 Only a limited amount of
data could be obtained (given EPA's
funding limitations). Consequently,
making definitive statistical compari-
sons was difficult. Nevertheless, an
analysis of that data (as contrasted to
the data gathered at bench-scale on the
roughly 160 compounds aforemen-
tioned) led to the following three gen-
eral conclusions:216
(1) The pyrolytic-based thermal
stability ranking of POHC in-
cinerability yielded statistically
significant correlations at the
97.5 percent confidence level
for each test series at the pilot
facility and 90 percent for the
full-scale facility. In contrast,
the AHC Index achieved sta-
tistically significant correla-
tions at the 90 percent
confidence level in only two of
six test series.
(2) Some differences between pre-
dicted and observed results using
the TSLo02 ranking were likely
due to PIC formation. Other
discrepancies were particularly-
notable for benzene in the pilot-
scale tests and for toluene in the
full-scale tests, both of which
were considerably more des-
tructible (or "fragile") than
predicted. These results dis-
agree with typical observations
for other field studies.
(3) The full-scale tests consistently
showed sulfur hexafluoride (SF6)
to be significantly more "sta-
ble" (resistant to destruction)
than the other POHCs, sup-
porting its potential as an inci-
nerability surrogate.
As a result of uncertainty over in-
cinerability rankings, the use of "ad-
ditives" is being considered for
overcoming the limitations of the POHC
compound approach. This concept in-
volves the addition of a single, well-
characterized compound or small group
(or "soup") of compounds to a waste
stream, with subsequent continuous
monitoring of the emissions of the
compound(s) to serve as a measure of
destruction performance. Compounds
such as various freons217-218 and SF6
have been proposed.219*221 In a recent
EPA study,222 a mixture of four stable
POHCs (as predicted by the TSLoO;
Ranking) and SF6 were fed to a pilot-
scale rotary kiln system which was op-
erated at different temperatures and
oxygen concentrations. In all cases
where the SF4 DRE was 99.99 percent
or greater, the individual POHC DREs
exceeded 99.99 percent. However, there
is also some evidence that SF6 may not
always be a conservative indicator of
organic destruction for all cases such
as the low oxygen failure mode. Con-
ceptually, these types of materials
would appear to be good additives since
they rarely occur in hazardous wastes,
can be detected in emissions using on-
line instruments and are not likely to
be formed as PICs.
Combustion byproducts formation
has caused difficulty in interpreting in-
cinerability data for mixtures of con-
ventional POHC candidate
compounds.219,223,224 While labora-
tory-scale studies have shown some
promise, earlier attempts in correlating
field incinerator performance with ad-
ditives behavior have generally been
inconclusive. Additional testing is
54 • January 1993 • Vol. 43 • AIR & WASTE
- G-30
-------
needed, beyond the recent pilot- and
full-scale tests highlighted previously.
Performance Indicators
Carbon monoxide and total un-
hurried hydrocarbons are emitted from
all combustion systems in varying
amounts. Because CO is the final com-
bustion intermediate prior to the for-
mation of CO? in an ideal combustion
process, it has been used in the deter-
mination of combustion efficiency.
Measured unburned hydrocarbon
emission values do not include all in-
completely combusted hydrocarbons.
Rather, this is an instrumentation-de-
rived value resulting from the passage
of gaseous emissions through a hydro-
gen Flame Ionization Detector (FID),
which is commonly used with gas
chromatographs. The FID responds to
the number of carbon-hydrogen and
carbon-carbon bonds in residuals in the
combustion gas but not to carbon-hal-
ogen bonds. Nonetheless, because it
does not respond to oxidized products
such as 02, CO, C02 and H,0, it has
traditionally been used as an indicator
of residual fuel emissions.
The use of CO and HC as indicators
of the degree of combustion comple-
tion in hazardous waste incineration has
been studied by several
groups210-219,225-226 and crificized by
others.224-227 Waterland obtained pilot-
scale data which indicated correlations
of the fractional penetration of POHCs
(1-DRE/T00) with CO and HC.225
Kramlich et al.210 and LaFond et al.223
found that increases in CO preceded
increases in the penetration of POHCs
in a laboratory-scale turbulent flame
reactor as parameters such as air/fuel
ratio, atomization and degree of ther-
mal quenching were varied. At the same
time, HC tended to increase as POHC
! penetration increased. In a test of a pilot-
scale circulating fluidized bed com-
j bustor, Chang et al.219 indicated that
penetration of combustion byproducts
appeared to be correlated with HC and
that there were no instances of high
combustion byproducts penetration
without a corresponding increase in CO.
The converse was not true; increases
in CO were observed on some occa-
sions without a corresponding increase
in combustion byproduct penetration.
POHC destruction efficiency was high
throughout this series of tests and did
not appear to correlate well with either
HC or CO. Although critical of the use
of CO as a surrogate for POHC DRE
or as an indicator of incinerator per-
formance, Daniels et al.227 presented
data obtained from a full-scale rotary
kiln. In five out of six cases the data
indicated increased POHC penetration
with increased CO concentration.
Analysis of the pooled data from the
early 1980s EPA incinerator test pro-
gram revealed that there was no ab-
solute level of mean combustion
temperature, mean gas-phase resi-
dence time or carbon monoxide emis-
sion concentration which correlated with
achieving a 99.99 percent DRE.'07
Residence times ranged from 0.1 to 6.5
seconds in the facilities tested, and
temperatures ranged from 648 to
1,450°C. Carbon monoxide levels were
as high as 600 ppmv, but at most plants
ranged from 5 to 15 ppmv. It was con-
cluded that the relationships between
DRE and these parameters arc, in all
likelihood, facility-specific and that
waste characteristics, waste atomiza-
tion and combustion chamber mixing
likely play equally important roles in
achieving high DREs. Timing, fund-
ing and facility constraints, however,
did not allow for collection of suffi-
cient performance data under varying
conditions at each site tested to allow
quantification of such relationships. In
particular, few of the test conditions
produced DREs significantly below
99.99 percent.
Dellinger224 has suggested that one
reason for difficulties in correlating CO
with DRE is that the assumed rapid
oxidation of hydrocarbons to CO may
not be correct for complex hazardous
wastes containing large halogenated and
heteroatom molecules. For these wastes,
formation of stable and/or refractory
intermediate organic reaction products
may delay the production of CO. This
delay would tend to distribute or move
the CO production maximum relative
to fuel (waste) destruction efficiency
and would tend to negate the useful-
ness of CO measurement in the region
of 99.99 percent DRE. Hall et at.22''
have conducted laboratory studies of
CO formation versus compound de-
struction for several complex mixtures
and found no correlation.
The Clean Air Act regulations cur-
rently requires the continuous moni-
toring of opacity using transmissometers
for many types of facilities (such as
cement kilns) and the continuous emis-
sion monitoring of MWCs is also re-
quired. Furthermore, it appears that
opacity can be correlated to mass par-
ticulate emissions on a site specific ba-
sis. Thus, the possibility exists for using
continuous opacity monitoring (COM)
to monitor mass particulate emissions.
Predicting Performance
Based on current knowledge, it
would appear that no single perform-
ance indicator or surrogate is sufficient
as a predictor of organic compound de-
struction in incinerators. While low
oxygen thermal stability data show
promise as a predictor of relative com-
pound incinerability, the data base is
still not sufficient to extend this con-
cept to universal POHC selections or
to the development of standard POHC
soups for trial burns or compliance
monitoring. Data on additives are also
insufficient to project a DRE correla-
tion. EPA's Science Advisory Board
(SAB) did conclude that the concept
of using CO and/or HC concentrations
to ensure that PIC emissions from
combustion devices burning hazardous
waste are below levels of public health
concern was reasonable.142 Even though
it was observed that there was not a
universal correlation between CO and
PIC emissions, it was found that when
CO was low, PICs were also low. On
the other hand, when CO was high,
PICs may or may not be high. Con-
sequently, CO should be a good con-
servative indicator of combustion
performance.21 While attempts to cor-
relate performance with single indica-
tors and surrogates have not been
entirely successful, taken in appropri-
ate combination with other indicators
they arc useful as real-time indicators
of the onset of process failure.
One of the additional limitations
placed upon attempts to correlate sur-
rogates and indicators with DRE and
emissions of PICs is the lack of a sig-
nificant data base on incinerator op-
eration under failure or upset conditions.
A failure condition can be defined as
a normal or accidental operational de-
viation which results in failure of the '
facility to achieve the RCRA perform-
ance standards such as a 99.99 percent
DRE. Most of the field incinerator data
used to make HC and CO correlations
has been taken under steady-state op-
erating conditions, although there are
some full-scale emissions data avail-
able for non-steady state opera-
tion. I1!-l4S The impact of events that
could be indicative of failure (such as
nozzle clogging, kiln overcharging, and
CO and HC emissions spikes) has not
been adequately quantified. This is
largely because of limitations on test
time and funding and, in particular,
permit constraints which prohibit off-
design operation of facilities. EPA has,
however, conducted some failure-mode
testing at its bench- and pilot-scale re-
search facilities in Cincinnati, Ohio,
Research Triangle Park, North Caro-
lina and Jefferson, Arkansas. And some
testing has shown that there is little j
change in POHC DRE over significant |
G-31
AIR & WASTE • Vol. 43 • January 1993-55
-------
FEATURE
operating ranges or under "apparent"
failure conditions.214-222-229'232
In July 1990, EPA and the Occu-
pational Safety and Health Adminis-
tration established a joint task force to
review safety and health issues at haz-
ardous waste incineration facilities na-
tionwide. The task force inspected 29
facilities. While the focus of this in-
spection was to evaluate compliance
with safety and RCRA standards, a
significant number of waste feed cu-
toffs and emergency safety vent open-
ings were also noted at some
facilities.233 EPA is, therefore, con-
ducting additional failure-mode testing
at its bench- and pilot-scale research
facilities in Research Triangle Park,
North Carolina and Jefferson, Arkan-
sas to assess the impact of these events.
A series of pilot-scale incineration
tests were recently conducted at the IRF
to assess the impact on emissions in
situations that would trigger a waste
feed cutoff.234 Seven tests were per-
formed corresponding to high CO
spikes, reduced pressure drop across
the venturi scrubber and decreased
scrubber liquor flow to the packed-col-
umn scrubber. None of the modes tested
caused significant increases in POHC,
trace metal, or HC1 emissions.
EPA has also conducted nonsteady-
state operational assessments at three
boilers employing hazardous waste as
a fuel.235 The impact of typical non-
steady-state operating conditions (such
as start-up, soot blowing and load
change) upon DRE and emission of
combustion byproducts, CO and HC
was studied. While elevated CO emis-
sions were observed at two of the sites
under off-design operation, attempts to
correlate DRE with CO, NOx and 02
emissions were unsuccessful. This was
largely because 99.99 percent DRE was
achieved under both good and off-de-
sign operation. The testing, however,
acknowledged some of the difficulties
in conducting off-design studies. In
some cases, the duration of the process
transient to be studied may be shorter
than the sampling time required to col-
lect a sufficient sample to assess DRE.
The large volume and high surface area
(boiler tubes) in boilers tended to delay
emissions of organics from one off-de-
sign test to the next, making it difficult
to separate cause and effect.
This so-called "hysteresis effect"
has been tested more thoroughly and
found to be much less of a problem in
determining true DREs than originally
thought.234 In this test of a full-scale
boiler, the operating parameters were
set in an attempt to maximize the hys-
teresis effect by operating the boiler in
a "sooting" mode. It was found that
while hysteresis did occur, the mag-
nitude was compound-specific and small
so that it would have little effect in
determining the DRE. The mass of
pollutants emitted during hysteresis
ranged from 5.5 percent for monoch-
lorobenzene to 10.5 percent for trich-
loroethylene of the mass of these same
pollutants that were emitted during
normal sampling operation.237 This
would have the net effect of changing
a 99.99% DRE calculated under nor-
mal sampling procedures to 99.9895%
for monochlorobenzene and to 99.9890
for trichloroethylene.
Environmental and Public Health
Implications
Regardless of the apparent capabil-
ities of hazardous waste incinerators to
meet or exceed the RCRA perform-
ance standards, the ultimate public test
involves demonstration that there is no
unacceptable increase in public health
risk from the emissions to the environ-
ment. While any of the emissions from
an incinerator may potentially be of
environmental interest, most attention
has been directed toward air pollution
emissions. This is because they appear
to represent the most important source
of off-site human exposure and there
is no opportunity for secondary con-
tainment or treatment of emissions once
they leave the stack. Ash and scrubber
residues, however, are lower in vol-
ume and can be contained, examined
and if necessary, treated prior to dis-
charge or disposal. In addition to
chronic exposure to recurring emis-
sions, there are also environmental and
public health impacts which could re-
sult from potential single-event or cat-
astrophic emissions at incineration
facilities.
Risks from Single-Event Emissions
As with any industrial facility, there
are risks from potential accidents at in-
cineration facilities such as fires, ex-
plosions, spills of raw waste, physical
injuries, acute exposure to waste, or
accidental releases to the environment.
These events are probabilistic in nature
and their evaluation in a risk assess-
ment is handled differently from con-
tinuous pollutant emissions from stacks.
For instance, the U.S. Department of
Transportation maintains statistics on
the frequency of releases of cargo from
vehicular accidents involving trucks.
For tank trucks of all types, for in-
stance, this is estimated to be 0.35 re-
leases per million miles traveled.238
Similar values may be identified for
accidents involving storage facilities and
transfer operations.
Little specific information on these
types of accidents is available for haz-
ardous waste incineration facilities.
Often such detail which is not readily
available is a matter of legal and court
actions and other kinds of settlements
protected by privacy. Ingiwersen et
al.239 evaluated the potential off-site
impacts of five hypothetical accidents
at a planned hazardous waste inciner-
ation facility. It was estimated that no
long-term adverse effects could be ex-
pected from chronic exposure for the
nearest residents (0.5 miles) and that
any effects due to acute exposures to
the HC1 emissions from the accidents
were expected to be short-term and re-
versible. Actual accidents at an oper-
ating European facility have been
documented;240 seven accidents oc-
curred over an 11-year period. One
employee was injured and no off-site
effects were reported for any of the
incidents, which generally involved
storage and handling operations. In the
absence of accident data specific for
incineration facilities, statistics from
related industrial practices are proba-
bly adequate in assessing these risks.
Methods for Assessing Risks from
Recurring Emissions
The major concern of this discus-
sion is the risk associated with recur-
ring air pollution emissions from
incinerators. The assessment of risk to
human health rather than environmen-
tal damage is generally believed to be
of greatest interest. Four general steps
are involved in assessing the impact on
public health from stack emissions from
an incinerator:241
(1) Identify the health effects of
constituents of concern as a
function of concentration level.
(2) Predict the concentrations of
these constituents to which the
public may be exposed.
(3) Estimate the health impact of
these concentration exposures.
(4) Conduct an uncertainty analy-
sis.
Identification of the constituents of
concern in stack emissions and the
health effects of these constituents is,
of course, a function of the waste
streams and incineration facility of in-
rerest. In general, any of the constit- ¦
uenis in Appendix VIII of the RCRA j
standards are of possible interest. Other j
compounds which may be found in ;
combustion emissions (certain polyn- '
uclear aromatics, polycyclic aromatic
56 • January 1993 • Vol. 43 • AIR & WASTE
G-32
-------
compounds and heavy meals) may also
be of concern. The major health ef-
fects of concern are for low-level
chronic exposure to these materials.
These effects are generally carcino-
genicity, mutagenicity, teratogenic or
target organ toxicity such as nephro-
toxicity, immunotoxicity and behav-
ioral effects.
Predicting the potential levels of
human exposure to pollutants requires
information on the frequency, inten-
sity, duration and continuity of expo-
sure.241 Exposure assessment generally
requires the use of mathematical models
which simulate the transport and dis-
persion of emissions from the stack to
the exposed population. EPA has de-
veloped approximately 10 models suit-
able for regulatory application and more
than 20 additional models have been
submitted to EPA by private devel-
opers for possible use. EPA has issued
guidelines which recommend the air
quality modeling techniques that should
be used. Table XXIV lists specific
models that are recommended for se-
lected applications in simple ter-
rain.^242'2" Simple terrain, as used here,
is considered to be an area where ter-
rain features are all lower in elevation
than the top of the stack of the source(s)
in question.
I Of the air dispersion models avail-
able, EPA has most often used the In-
dustrial Source Complex Long-Term
(1SCLT) Model for predicting annual
average concentration for hazardous
waste incinerator facility studies.24*-247
The Oak Ridge National Laboratory has
linked the ISCLT model with comput-
erized meteorology and population data
bases and programs to form the Inha-
lation Exposure Methodology
(IEM).248-24' The IEM employs U.S.
population data and local meteorolog-
ical data along with ISCLT to estimate
air pollutant concentrations and human
inhalation exposures in the vicinity of
hazardous waste incinerators located
anywhere in the United States. The IEM
has been used extensively by EPA in
assessing regulatory alternatives for
hazardous waste incinerators.:50-251
The exposure information gener-
ated by models such as the IEM may
then be employed to estimate human
health risk. The individuals at highest
risk of developing adverse health ef-
fects are of most interest. The risk to
this "maximally exposed population"
is estimated from the modeled expo-
sure at the point of highest annual av-
erage pollutant ground-level
concentration outside the facility. For
each exposed individual, cancer risk is
Tahle XXIV. Preferred air quality models for selected applications in simple terrain.2'
Short Term (1-24 hours) Land Use Model"-"
Single Source
Multiple Source
Complicated Sources*
Buoyant Industrial Line Source
Rural
Urban
Rural
Urban
Rural/Urban
Rural
CRSTER
RAM
MPTER
RAM
ISCST
BLP
Long Term (monthly, seasonal or annual)
Single Source
Multiple Source
Complicated Sources'
Buoyant Industrial Line Source
Rural
Urban
Rural
Urban
Rural/Urban
Rural
CRSTER
RAM
MPTER
CDM 2.0 or RAM"
ISCLT
BLP
' CRSTER denotes single source model; RAM denotes Gaussian-plume multiple source
air quality algorithm; MPTER denotes multiple point Gaussian dispersion algorithm with
terrain adjustment; ISCST/ISCLT denotes industrial source complex short-term and long-
term models; BLP denotes buoyant line and point source dispersion model; CDM denotes
climatologica! dispersion model.
" Several of these models contain options which allow them to be interchanged. For ex-
ample, ISCST can be substituted for CRSTER and equivalent, if not identical, concen-
tration estimates obtained. Similarly, for a point source application, MPTER with urban
option can be substituted for RAM. Where a substitution is convenient to the user and
equivalent estimates are assured, it may be made. The models as listed here reflect the
applications for which they were originally intended.
' Complicated sources are sources with special problems such as aerodynamic downwash,
panicle deposition, volume and area sources, etc.
J If only a few sources in an urban area arc to be modeled, RAM should be used.
expressed as the cumulative risk over
a 70-year (lifetime) period of contin-
uous exposure.
A variety of models are available to
quantify the health risks of chemical
pollutants. Carcinogen potency factors
have been developed by EPA based on
the linearized multistage model.'3* This
model is consistent with current un-
derstanding of the mechanism of car-
cinogenesis. For noncarcinogcntc
effects, no observable adverse effect
levels (NOAELs) have been used to
derive RfD levels.252
There is considerable uncertainty
involved in conducting risk assess-
ments. Numerous assumptions must be
made regarding pollutant emission lev-
els, pollutant effects, dispersion fac-
tors and so on. Only a fraction-of the
needed tests of the effects of chronic,
low-level exposures to environmental
pollutants have been done. There is also
considerable uncertainty in extrapolat-
ing effects from high doses, which cause
effects in animals, to low doses in hu-
mans. Linearity assumptions are typi-
cally used in making such
extrapolations. Some investigators have
questioned the wisdom of such as-
sumptions, however.253
Beyond this, very little is known
about how, or even if, this information
can be used to estimate the effects of
complex mixtures of the substances
usually present in incinerator stack
emissions. For these reasons and other
limitations, most assessments adopt
assumptions and risk estimate values
which produce an estimate of a worst-
case effect. In order to promote con-
sistency in risk assessments, EPA has
published in the Federal Register a six-
part guidance on risk and exposure as-
sessment methodologies.254 This guid-
ance is an excellent resource to those
conducting or evaluating risk assess-
ment studies. In addition, EPA has is-
sued risk assessment guidance manuals
to be used in the remedial investiga-
tion/feasibility study (RI/FS) process
at Superfund sites.255-256
Overall Risks from Long-Term Air
Pollution Emissions from Hazardous
Waste Incinerators
Risk assessment and risk manage-
ment have been used increasingly by
industry and government over the past
fifteen years in evaluating control
technology and regulatory options for
managing hazardous waste.257 The in-
itial 1978 RCRA incineration stan-
dards, for instance, were almost entirely
design and performance oriented. In the
1981 proposal, however, EPA incor-
porated risk assessment into what was
G-33
AIR & WASTE • Vol. 43 • January 1993-57
-------
called the "best engineering judge-
ment" (BEJ) approach to regulating and
permitting incinerators.17 The operat-
ing and performance standards for in-
cinerators were to apply to facilities
unless a site-specific risk assessment
indicated that a higher degree of con-
trol was necessary. The risk assess-
ment proposal, however, was not
included in the final rule in 1982,
largely because of concern from the
regulated community over the uncer-
tainty of risk assessment approaches.
Rather, risk assessment and cost-ben-
efit analysis became a more integral
part of the development of hazardous
waste control technology standards
through the conduct of Regulatory Im-
pact Analyses of all proposed stan-
dards as required by Executive Order
12291.
Rules promulgated for burning haz-
ardous waste in boilers and industrial
furnaces27 require that emissions test-
ing and health-risk assessments for
chlorinated dioxins and furans for cer-
tain facilities be done. Emission limits
for metals, HC1 and Cl2 are based on
projected inhalation health risks to the
hypothetical maximum exposed indi-
vidual. Similar approaches were used
in developing the proposed amend-
ments to the hazardous waste inciner-
ator regulations.21
A number of risk assessments have
been conducted for specific hazardous
waste incinerators and for incineration
on a national basis. Using the emis-
sions data from eight full-scale incin-
erator tests,107 EPA conducted a risk
assessment as pan of its Incinerator RIA
in 1982. The objective was to examine
the economic impact of the regulations
on the regulated community and to es-
timate the health and environmental
effects of the regulations.258 The risks
due to POHCs, PICs and metal emis-
sions were developed (Table XXV).
Since then, numerous other risk as-
sessments have been conducted for fa-
cilities burning hazardous waste.
While these results show that the
human health risks from emission of
organics from most hazardous waste
incinerators are low, risks from metal
emissions show the greatest potential
for cancer risk. The risks from metals
Table XXV. Total excess lifetime cancer
risk to (he maximum exposed individual
from incinerator emissions.a"
POHCs 10-10 to 10-7
PICs 10-" to 10-7
Metals 10-" to 10"s
Total 10-" to 10"5
emissions ranged from two to six or-
ders of magnitude higher than values
for POHCs and PICs, and dominated
the total risk values. Risks from resid-
ual POHC and PIC emissions from the
incinerators tested were both low. Much
more importance has now been given
to the control of metal emissions, how-
ever, and the risks from these emis-
sions will not exceed acceptable levels
if appropriate APCDs and the metal
controls promulgated for BIFs27 are
employed.
Taylor et al.259 reported the results
of a risk assessment for metal emis-
sions using the same test data but em-
ploying somewhat different
assumptions. Using the IEM method-
ology, carcinogenic and noncarcino-
genic risks were examined.
Interestingly, these results showed even
lower cancer risks than the EPA study.
Individual lifetime cancer risks for the
maximum exposed population ranged
from a low of 4.48 x 10"11 for beryl-
lium to a high of 3.47 X 10~6 for chro-
mium. Noncarcinogenic risks were also
small. All values were well below the
respective acceptable daily intake (ADI)
values. Lead intake was highest, esti-
mated at 2 percent of the ADI.
Kelly reported similar conclusions
for a risk assessment of stack emis-
sions from a hazardous waste inciner-
ator in Biebesheim, West Germany.260
Maximum ground level air concentra-
tions for 24 metals (and for PCB) were
estimated using the IEM. All levels
(including PCB) were less than 2 per-
cent of the corresponding continuous
exposure limit (CEL) value.
Following the promulgation of the
BIF regulations,28 some communities
have become increasing concerned re-
garding the burning of hazardous waste
in cement kilns. Studies have been
conducted to address the risk posed by
this practice. Mantus261 reported that
the organic and metal emissions of a
well-designed and properly operated
cement kiln burning hazardous waste
are not substantially different from the
emissions of a cement kiln burning only
conventional fuel. Mantus also re-
ported that no increases in adverse
health effects were expected due to the
use of hazardous waste fuels. The Texas
Air Control Board conducted an exten-
sive environmental monitoring study
in Midlothian, Texas where two ce-
ment plants were burning hazardous
waste and reported that no adverse
health effects were expected due to
emissions from these facilities.262
Holton et al.263'265 examined the
significance of various exposure path-
ways for air pollution emissions from
three sizes of land-based incinerators
located at three hypothetical sites in
the United States. For certain organic
chemicals, the food chain pathway may
be an important contributor to total hu-
man exposure. The study concluded,
however, that the human health risk
from emissions was small for all of the
chemicals studied irrespective of the
exposure pathway. EPA has recently
issued guidance necessary to estimate
the health risks that result from expo-
sure to toxic pollutants in combustor
emissions by pathways other than in-
halation.266
Fugitive emissions from peripheral
facilities at incinerators (such as stor-
age tanks) were also estimated to be
an important contributor to total pol-
lutant emissions.264,265 Few studies have
quantified fugitive emission levels at
incinerators, but the ones that did have
shown that ambient levels are not a
cause for concern.107-267-268
The risks associated with incinera-
tion of hazardous wastes at sea have
been compared to risks from land-based
incineration.238 While risks of marine
and terrestrial ecological damage were
estimated, the direct human health risks
from stack emissions are of greatest
interest in this discussion (Table XXVI).
The incremental cancer risk to the most
Table XXVI. Incremental cancer risk to the most exposed individual by type of stack
release."8
Systems PCB Waste EDC Waste
Ocean-based
POHCs 1.45 x 10-'° 5.51 x 10"10
PICs 1.68 x 10-|J 3.36 x 10-'
Metals 6.37 x 10-7 1.06 x 10-6
Total stack 6.37 x 10-7 1.06 x 10"6
Land-based (two sites)
POHCs 5.13 x 10-8 1.43 x 10-7
PICs 1.79 x 10-4 2.59 x 10"8
Metals 2.65 x 10"s 3.12 x 10-5
Total stack 2.74 x 10"5 3.14 x 10"5
58 • January 1993 • Vol. 43 • AIR & WASTE
G-34
-------
exposed individual was determined for
POHCs, PICs and metals for two scen-
arios: a PCB waste and an ethylene
dichloride (EDC) waste. Not surpris-
ingly, the human health risk of stack
emissions from ocean incineration were
less than those of land-based systems,
largely due to distance from popula-
tion. The land-based incinerator risk
values were similar to those estimated
in the EPA incinerator RIA. POHC and
PIC releases showed low risk, gener-
ally one to five orders of magnitude
less than those for metals. Risks from
metals accounted for from 90 percent
to almost all of the identified risk from
either system, and they exceeded the
10-6 risk level for only the land-based
scenario. The study notes, however,
that the assumptions used in the as-
sessment overstate the likely levels of
carcinogenic metals in the hypothetical
wastes used in the assessment and,
therefore, likely overestimate emis-
sions and risk levels.
All of these risk assessment studies
suggest that stack emissions from in-
cineration of hazardous waste pose lit-
tle risk to human health. However, as
previously stated, the emissions data
base upon which many of the assess-
ments were based has been criticized
by EPA's Science Advisory Board
(SAB) as being insufficient.141,142 The
SAB has recommended that "EPA
should conduct more studies to better
define whether or not a problem exists
with the emission of PICs, the source(s)
of the problem if it exists, and how to
minimize the problem."142
It is not clear, however,, that even
this level of emissions information will
really answer the question of how much
absolute risk is associated with incin-
erator emissions. From the standpoint
of the lay public, it may be more use-
ful and productive to compare these
emissions with other types of combus-
tion emissions whose risks we have ac-
cepted in daily life. Lewtas269 and others
have done interesting work on the
comparative cancer potency of com-
plex mixtures of pollutants (for ex-
ample, power plant emissions,
automobile exhaust and cigarette
smoke). Using short-term bioassavs of
organics extracted from actual emis-
sions, the relative cancer potency of
emissions has been estimated.
Comparative mutagenic emissions
rates, expressed as revertants per mile
or joule, have been determined from
testing mobile sources and stationary
sources, respectively. Experimental
work to date suggests that the muta-
genic emission rates of wood stoves,
for instance, are as much as four or-
ders of magnitude greater than those
for conventional coal-fired utility power
plants.26' Similar sampling and testing
are needed for incineration emissions
so that their potency can be compared
to everyday sources such as wood
stoves, oil furnaces and utility power
plants. It should be noted, however,
that use of comparative mutagenic
emissions rates alone docs not account
for variations in potential human health
impact that occur due to differences in
exposure level to emissions from
sources of different types or as a result
of different routes of exposure.
The mass of specific organic emis-
sions from HWls have been
compared270 to the 1990 Toxics Re-
lease Inventory (TRI).271 The HWI
emissions were estimated using "rea-
sonable worst case" assumptions.
Comparisons were made for 15 carcin-
ogenic organic and 17 non-carcino-
genic compounds. Ratios for all but
one of these compound-specific HWI
emissions to their corresponding TRI
air releases ranged from 0.0003 to 0.746
percent. The total mass emissions
(121.7 tons) of all 32 specific organics
from HWls was less than 0.03 percent
of the corresponding 1990 TRI air re-
leases (431,600 tons).
In an EPA analysis, the cancer risks
from exposures to airborne toxic pol-
lutants were estimated for the total U.S.
population.272 The purpose of this was
to provide information to suggest
priorities for air toxics control. It is
emphasized that the estimated annual
cancer cases are not absolute predic-
tions of cancer occurrence and are in-
tended to be used in a relative sense
only. About 90 toxic air pollutants and
60 source categories were addressed.
Hazardous waste incinerators and in-
dustrial boilers and furnaces burning
hazardous waste comprised one of the
source categories. Estimated incre-
mental annual cancer cases are sum-
marized in Table XXVII. It is
interesting to note that emissions from
burning hazardous waste accounted for
only an incremental 0.3 cancer cases
per year or 0.015 percent of the esti-
mated 1,986 incremental annual can-
cer cases from all 60 sources. Over 56
percent of the cancer cases was due to
emissions from motor vehicles. Can-
cer cases due to source categories such
as woodsmoke and gasoline marketing
were two to three orders of magnitude
higher than those due to burning haz-
ardous waste. In comparison, it is es-
timated that_H0,000 cancer cases were
due to tobaamise and 385,000 cancer
AIR
G-35
cases were due to diet in the U.S. in
1991.273
Conclusions
The body of knowledge concerning
hazardous waste incineration has been
expanding rapidly since 1980. This re-
view update has examined some of the
most significant aspects of this infor-
mation. A number of conclusions may
be drawn on the status of incineration
technology, current practice, monitor- j
ing methods, emissions and perform- ;
ance, and public health risks. Beyond !
these, a number of remaining issues j
and research needs can also be iden- |
tified. j
Based on this review, the following
conclusions may be drawn:
(1) Incineration is a demonstrated,
commercially available tech-
nology for hazardous waste
treatment. Considerable design
experience exists, and design
and operating guidelines are
available covering the engi-
neering aspects of these sys-
tems.
(2) A variety of process technolo-
gies exist for the range of haz-
ardous wastes appropriate for
thermal destruction. The most
common incinerator designs in-
corporate one of four major
combustion chamber designs:
liquid injection, rotary kiln,
fixed hearth or fluidized bed. \
The most common air pollution j
control system involves com- !
bustion gas quenching followed
by a venturi scrubber (for par-
ticulate removal), a packed
tower absorber (for acid gas re-
moval) and a mist eliminator.
Newer systems have incorpo-
rated more efficient air pollu-
tion control devices, however,
such as wet electrostatic precip-
itators, ionizing wet scrubbers,
spray dryer absorbers, fabric
filters and proprietary systems.
(3) Some of the most recent infor-
mation for the burning of haz-
ardous waste is provided by the
state Capacity Analysis Plans
which show that for 1987 about
1.3 MMT of hazardous waste
were incinerated in 171 incin-
erator facilities across the United
States. In addition, about 1.2
MMT of hazardous waste were
burned in BIFs during this same
period.
& WASTE • Vol. 43 • January 1993 • 59
-------
FEATURE
Ranking Index. Bench-scale
data are only available, how-
ever, for approximately half of
the Appendix VIII organic
compounds.
(18) There appears to be little in-
creased human health risk from
hazardous waste incinerator
emissions, based on assess-
ments done to date. Metal
emissions appear to be most
significant in the risk values
which have been derived.
(19) An EPA analysis of 90 toxic
air pollutants from 60 indus-
trial categories estimated that
the incremental cancer risk
from all hazardous waste in-
cinerators, industrial boilers
and industrial furnaces burn-
ing hazardous waste in the
United States at approxi-
mately 0.3 cancers per year.
This compared to 1,986 addi-
tional cancers per year from all
60 categories.
(20) In spite of the demonstrated
destruction capabilities of haz-
ardous waste incinerators and
the apparent low incremental
risk of emissions, there is con-
siderable public opposition to
siting and permitting these fa-
cilities. Permits for commer-
cial HWIs require an average
of three years, and often much
longer, to be finalized. Uncer-
tainty over permitting and
public acceptance will likely
result in a near-term shortfall
in needed capacity for certain
geographic areas and for spe-
cific waste types such as ex-
plosives, mixed waste, and
possibly solids and sludges.
Remaining Issues and Research
Needs
While thermal destruction rep-
resents the most effective and widely
applicable control technology avail-
able today for the disposal of organic
hazardous waste, a number of issues
remain concerning its use in the long
term. These include: destruction effec-
tiveness on untested/unique wastes,
control of heavy metal emissions,
emissions of combustion byproducts,
detection of process failure, real-time
performance assurance and the role of
innovative technology.
Destruction Effectiveness on
Untested/Unique Wastes
Most of the performance data which
have been used in the development and
assessment of thermal destruction reg-
ulations and standards to date have been
collected for waste/thermal technology
combinations typical of current prac-
tice. The character of wastes which are
being treated by incineration, how-
ever, has begun to change dramatically
during recent years. These changes have
been strongly influenced by the Land
Disposal Restrictions Program re-
quired by the Hazardous and Solid
Waste Act Amendments of 1984 and
influenced by increased emphasis upon
remedial action at Superfund sites. This
is due to the fact that the BDAT treat-
ment standards for many of the re-
stricted wastes are based on
incineration, which is also frequently
selected as the remediation technology
for Superfund sites. These wastes often:
have higher solids and water content,
are more complex in their physical and
chemical composition, may contain in-
organic salts, have lower heating value
and/or potentially contain higher levels
of hazardous metals and high-hazard
organics compared to wastes which
were typically incinerated in the past.
To further clarify this issue, the term
"untested/unique wastes" emphasizes
the wide spectrum of mixed waste or-
ganics, plastics, inorganics, and con-
taminated soil and other debris being
found at numerous Superfund sites
where industrial wastes from multiple
sources had been buried. The term also
applies to other, more homogeneous
RCRA waste streams such as waste
pesticides or industrial chemicals which
previously had never been treated by
incineration. In either case, not thor-
oughly understood are the incineration
of wastes containing the following:
toxic metals in significant concentra-
tions, various organics for which there
is a lack of documented incineration
experience, and organics absorbed
within inorganic matrices where the
organic desorption properties have not
been fully investigated. Waste con-
taining inorganic salts and other situ-
ations, such as where plastics or sludges
or light and fluffy materials are in-
volved, potentially present materials-
handling problems in an incinerator.
Consequently, while incineration is
believed capable of achieving high
levels of destruction for hazardous
wastes and there is a wealth of suc-
cessful experience and destruction data
for wastes historically incinerated in
stationary facilities, situations may still
arise where an unfamiliar combination
of organics, inorganics, and waste me-
dia or soil are considered for inciner-
ation. Treatability/performance testing
in such situations may be necessary to:
assure the destruction and removal ef-
fectiveness for untested wastes, assess
process limitations and waste pretreat-
ment requirements, determine the safety
or treatment requirements for process
residues and improve the ability to pre-
dict incinerator performance when fed
new waste materials.
Control of Heavy Metai Emissions
While the human health risk asso-
ciated with incinerator emissions ap-
pears to be small, metal emissions have
been the dominant component of the
risk levels identified thus far. Signifi-
cant progress has been made in better
understanding the fate or "partition-
ing" of metals in the combustion
process and the effectiveness of certain
APCDs to control metal emissions, but
much remains to be done.
Research to understand the incin-
eration behavior of organic/metal mix-
tures began in earnest only a few years
ago. As a result, understanding of met-
als partitioning is not yet complete.
Likewise, at a very early stage of de-
velopment are the understanding of the
importance of the chemical form of the
particular metal species (whether pure,
oxides, chlorides, alloys or organo-
metallics and their respective valence
states) as well as the knowledge con-
cerning the possible influences of the
soil matrix and/or inorganic materials
(such as lime, portland cement dust and
fly ash) that could be added to the in-
cineration process to tie up the metals.
In addition, modified operation of con-
ventional rotary kilns such as running
at lower temperatures in the primary
chamber to "remove" the organics for
subsequent destruction in the afterbur-
ner may become increasingly attrac-
tive. This may be particularly true for
treating wastes such as Superfund soils
which are contaminated by both or-
ganics and metals since more of the
metal might remain with the treated/
decontaminated soil and not pose an
air pollution problem. More testing is
required, however, to determine that
these modified operating approaches
will effectively destroy the organics and
decontaminate the soil.
Emissions of Combustion Byproducts
Current information suggests that
organic combustion byproduct emis-
sions resulting from the incineration of
hazardous waste do not represent a sig-
nificant risk to public health. Some,
however, have questioned the com-
pleteness or thoroughness of emissions
data and, therefore, the adequacy of
risk assessments performed using these
62 • January 1993 • Vol. 43 • AIR & WASTE G_3g
-------
data. This issue has emerged as a con-
cern in numerous public meetings on
incinerator permits and facility sitings.
There is little doubt that none of the
emissions testing efforts conducted to
date has identified all compounds con-
tained in incinerator stack emissions.
It should be noted, however, that the
same is true for virtually any other
source of air (including vehicle emis-
sions) or water pollution; that is the
complete character of these other
emissions or effluents is also not com-
pletely known. While many believe that
most of the unidentified organic mass
is nonchlorinated, low molecular weight
hydrocarbons which are of little con-
cern from a health risk viewpoint, this
is not vet sufficiently supported by
currently available data. In one full-
scale test, however, between 53 to 91
percent of all organics were identified.
Methane and ethylene accounted for 33
to 97 percent of the identified emis-
sions.
Because hazardous waste facilities
are perceived by some as posing higher
risk than many other types of pollution
control or industrial facilities, more at-
tention is given to their emissions. Thus, j
while it is unlikely that any major, j
highly hazardous components of emis- |
sions have been overlooked, the data i
are not available to satisfactorily prove :
this to all who may be concerned. The
EPA's Science Advisory Board has
recommended that EPA should inves-
tigate this issue more thoroughly to
better define whether or not a problem
exists due to the emission of organics,
the sources(s) of the problem if it ex-
ists and how to minimize the problem.
On the other hand, the task of finding
all potentially hazardous compounds is
an open-ended one, ultimately limited
by expense.
Most risk assessments conducted to
date have been based on inhalation of
HWI emissions. For certain situations,
the food chain pathway may be an im-
portant contributor to total human ex-
posure. Additional effort is needed to
investigate this issue both in the form
of validating methodologies and ap-
plying these methodologies to specific
cases.
Detection of Process Failure
Another issue related to combustion
byproduct emissions is that only a few
tests"5 ' 45-23'1 have examined the level
and chemical character of emissions for
those occasional periods of time when
facilities may be operating under upset
conditions (transients or failure modes).
More experimental work is clearly
needed here. Some testing has shown
that there is little change in principal
organic hazardous constituent DRE over
significant operating ranges or under
"apparent" failure conditions. But at
the same time, measured or visible
emissions of unbumed hydrocarbons
have typically increased. Research is
necessary to determine if these "fail-
ure-mode" emissions pose a hazard.
One approach to resolving both the
question of data completeness and fail-
ure mode impacts is to examine the
relative potency of emissions using
short-term bioassays and bioassay-di-
rected chemical analysis as a means of
more cost-effectively identifying the
chemical compounds (perhaps includ-
ing some previously unidentified) which
are primarily causing the potency.
While short-term bioassays have their
own set of constraints and limitations,
they have proven useful in comparing
the cancer potency of mixtures of com-
pounds among different combustion
sources. Testing a reasonable range of
hazardous waste types under "good"
and off-design conditions would give
an indication of the range of potency
of emissions as a function of opera-
tional conditions. This would also per-
mit additional comparison with
conventional combustion sources such
as automobiles, which are more fa-
miliar to the general public.
Real-Time Performance Assurance
Once the public health significance
of incinerator emissions is verified,
methods must be available to assure
that effective operation is maintained.
A variety of surrogates and indicators
of incinerator performance have been
evaluated and are already being used.
None, however, are capable of directly
identifying and measuring the emis-
sion of specific organics or metals on
a "real-time basis" and little evalua-
tion has been done under true failure
conditions.
While the TSLo02 Incinerability
Ranking Index appears promising, ad-
ditional laboratory evaluations need to
be conducted for many of the remain-
ing hazardous constituent organic
compounds. Additional validation
studies are needed before this method
can be used reliably for POHC desig-
nation or as a basis for establishing op-
timal continuous monitoring systems
for specific surrogate compounds. Re-
search has indicated that the additive
SF6 may be a useful way of continu-
ously assuring DRE, but this would
probably have to be used in combina-
tion with other parameters since there
may be cases where SF6 is not always
a conservative indicator of organic de-
struction. Additional investigation is
needed to fully understand the poten-
tial of SF6 and similar compounds for
assuring DRE.
j While it may not be possible to find
j an easily monitored parameter which
i "correlates" with incinerator perform-
i ance, it may be possible to identify other
: parameters and combinations of pa-
I rameters which might improve the
' ability to identify the onset of process
: failure. Research is necessary to ex-
. amine the suitability of additional real-
time monitoring systems and ap-
proaches to more reliably predict
process failure. Some promising work
is under way to develop "real-time"
detection monitors for specific organ-
ics and metals utilizing Fourier trans-
form infrared (FT1R) spectroscopy274
and laser technology. Availability and
use of such techniques might have a
significant and beneficial impact upon
public acceptance of these facilities and
form a technical basis for more effec-
tive compliance monitoring by regu-
latory agencies. CEMs are alio available
for HCl and opacity, and utilization of
these monitors could possibly help as-
sure the control of HCl and particu-
lates from HWls on a continuous basis.
Role of Innovative Technology
A wide range of innovative hazard-
ous waste technology has emerged since
the passage of RCRA."5-2"1 A number
of these technologies are thermal de-
struction processes. The potential de-
struction capabilities and cost-
effectiveness of these processes have
been steadily publicized, although many
of the techniques must be considered
to be only in the developmental stage.
Among technologies considered to be
new or innovative are pyrolysis, high-
and low-temperature plasmas, molten
1 salt, molten giass and molten metal
baths. One innovative concept which
has been tested and applied to Super-
fund soils in the past three to five years
i by Rollins Environmental Services is
a patented "rotary reactor."277 This
system utilizes a basic rotary kiln con-
cept, modified by the addition of a me-
chanically agitated and recycled internal
bed of sand or aggregate.
Many argue, particularly in public
hearings, that decisions on permitting
conventional incineration facilities
should be postponed in favor of adopt-
ing more innovative approaches, whose
inventors or developers often claim
higher destruction efficiency at lower
cost than conventional systems. For
G-37
AIR & WASTE • Vol. 43 • January 1993 • 63
-------
specific waste streams (such as con-
taminated soils and PCBs), a number
of innovative systems have demon-
strated equivalent performance to those
of conventional systems. Some sys-
tems appear to offer advantages for
handling specific, although sometimes
limited, waste streams. Considerable
uncertainty exists as to the true cost-
effectiveness of some systems, since
practical field experience and system
longevity data are often not yet avail-
able to aid in identifying operating
limitations.
In order to accelerate the develop-
ment and use of innovative cleanup
technologies at Superfund sites across
the country, EPA has established the
Superfund Innovative Technology
Evaluation (SITE) Program. In a re-
cent report278 that briefly described 72
demonstration and emerging technol-
ogies that were being evaluated under
the SITE Program, it was reported that
13 percent of the emerging technolo-
gies and 20 percent of the demonstra-
tion program technologies were thermal.
Many of these emerging systems will
find a role in future hazardous waste
management strategies. Policymakers,
public officials and industrial decision
officials should be careful, however,
in delaying action on currently avail-
able, demonstrated, thermal destruc-
tion systems until the need, benefit and
operability of such innovative systems
are clearly established.
Acknowledgments
This is an update of an earlier pub-
lication, "Incineration of Hazardous
Waste, A Critical Review," authored
by E. Timothy Oppelt in 1987279 and
has been prepared to reflect changes
that have occurred in the hazardous
waste incineration area over the past
five years. The authors wish to rec-
ognize and express their thanks to the
following individuals who provided
significant input and review for certain
sections: Jim Kilgroe, Air and Energy
Engineering Research Laboratory
(municipal waste combustor regula-
tions); Shiva Garg and Robert Hollo-
way, Office of Solid Waste (OSW)
(Regulations); Sonya Sasseville, OSW
(permitting); Donald Oberacker, Risk
Reduction Engineering Laboratory
(RREL) (Current Incineration Prac-
tice); Dr. Larry Johnson, Atmospheric
Research and Exposure Assessment
Laboratory and Robert Thumau, RREL
(Measuring Process Performance);
Gregory Carroll, RREL (Metal Emis-
sions and Ash and Air Pollution Con-
trol Residue Quality); George Huffman,
64 • January 1993 • Vol. 43 • AIR &
RREL (Combustion Byproducts Emis-
sions and Predicting and Assuring In-
cinerator Performance); Dr. Debdas
Mukeijee, Environmental Criteria and
Assessment Office (Environmental and
Public Health Implications) and Jim
Cudahy, Focus Environmental, Inc. for
his comprehensive technical review.
Finally, a report such as this would
never have been possible without the
stellar secretarial support provided by
Susan Grause and Patricia William-
son, RREL.
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233. U.S. EPA - OSHA Joint Task
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234. W.E. Whitworth, et al., "Eval-
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264, Subpart O-Incinerators,"
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252. U.S. EPA, "Integrated Risk In-
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Description and Use in Health
Risk Assessments," On-Line,
1992.
253. B.D. Goldstein, "Toxic sub-
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255. U.S. EPA, "Risk Assessment
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256. U.S. EPA, "Risk Assessment
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257. W.D. Ruckelshaus, "Science,
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258. Weinberger, L., et al., "Sup-
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259. C.C. Taylor, et aL, "Health Risk
Assessment for Metals Emis-
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APCA Annual Meeting, Minne-
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260. K.E. Kelly, "Comparison of
Metal Emissions Data from
Hazardous Waste Incineration
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262. Texas Air Control Board, "Con-
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1992.
263. G.A. Holton, et al., "Inhalation
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264. G.A. Holton, C.C. Travis, E.L.
Etnier, F.R. O'Donnell, D.M.
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265. C.C. Travis, E.L. Etnier, G.A.
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266. U.S. EPA, "Methodology for
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267. M.Y. Anastas, "Control Tech-
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268. M. Anastas, "Control Technol-
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Waste Disposal Operations in
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269. J. Lewtas, "Comparative Po-
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270. Dempsey, C.R., " A Compari-
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City, Missouri, June 21-26,1992.
271. U.S. EPA, "Toxics Release In-
ventory," On-Line, 1992.
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273. American Cancer Society,
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274. J.D. Demirgian, C.L. Hammer,
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72 • January 1993 • Vol. 43 • AIR & WASTE
G-46
-------
Acronyms/Abbreviations
ADI: acceptable daily intake
APCD: air pollution control device
BDAT: best demonstrated available
technology
BEJ: best engineering judgment
BIFs: boilers and industrial furnaces
Btu: British thermal unit
Br;: bromine
CD: calibration drift
CAP: Capacity Assurance Plan
CO,: carbon dioxide
CO: carbon monoxide
CAG: carcinogen assessment group
CDF: chlorinated dibenzofuran
CDD: chlorinated dibenzo-p-dioxin
CU: free chlorine
CAA: Clean Air Act
CFR: Code of Federal Regulations
CBP: combustion byproducts
CE: combustion efficiency or calibra-
tion error
AHc: compound heat of combustion
CERCLA: Comprehensive Environ-
mental Response, Compensation, and
Liability Act of 1980
CBO: Congressional Budget Office
CEM: continuous emission monitors
COM: continuous opacity monitoring
CEL: continuous exposure limit
cfm: cubic feet per minute
DRE: destruction and removal effi-
ciency
dscf: dry standard cubic foot
ECD: elecrron capture detector
ESP: electrostatic precipitator
EPA: U.S. Environmental Protection
Agency
EDC: ethylene dichloride
FF: fabric filter
FID: flame ionization detector
FTIR: Fourier transform infrared
GC: gas chromatography
GCP: good combustion practice
g: gram
HSWA: Hazardous and Solid Waste
Act of 1984
HWDF: hazardous waste derived fuel
HWI: hazardous waste incinerator
HPLC: high-performance liquid chro-
matography
HC: hydrocarbon
HBr: hydrogen bromide
HC1: hydrogen chloride
: HF: hydrogen fluoride
1 HHV: higher heating value
IRF: Incineration Research Facility
1SCLT: Industrial Source Complex
Long-Term
1EM: Inhalation Exposure Methodol-
ogy
I-TEFs/89: International Toxicity
Equivalency Factors, 1989
i IWS: ionizing wet scrubber
! LDR: Land Disposal Restriction
TSLo02: low oxygen thermal stability
MS: mass spectrometry
MACT: maximum achievable control
technology
MEI: maximum exposed individual
MV/I: medical waste incinerator
M5: Method 5
Mg: metric ton (106 grams)
(ig/m3: micrograms (10~6 grams) per
cubic meter
ixm: micrpn (10-4 meters)
mg/dscm: milligrams per dry standard
cubic meter
mg/kg-d: milligrams per kilogram per
day
MMT: million metric tons
MM5: modified Method 5
MWC: municipal waste combustor
ng/dscm: nanograms (10"' grams) per
dry standard cubic meter
ng/kJ: nanograms per kilojoule
ng/L: nanograms per liter
NSPS: New Source Performance Stan-
dards
NO,: nitrogen oxides
ND1R: nondispersion infrared
NDUV: nondispersion ultraviolet
NOAEL: no observable adverse effect
level
OTA: Office of Technology Assess-
ment
02: oxygen
ppm: parts per million
ppmv: parts per million by volume
PTM: performance test method
P,05: phosphorus pentoxide
PID: photo-ionization detector
pg/kg-d: picograms (10"12 grams) per
kilogram per day
PCB: polychlorinatcd biphcnyls
PCDF: polychlorinated dibenzofuran
PCDD: polychlorinated dibenzo-p-
dioxin
PCP: pentachlorophenol
psig: pounds per square inch gauge
AP: pressure drop
POHC: principal organic hazardous
constituent
PICs: products of incomplete combus-
tion
RODs: Records of Decision
RAC: reference air concentration
RfD: reference dose
RDF: refuse-derived fuel
RLA: Regulatory Impact Analysis
RA: relative accuracy
RI/FS: remedial investigation/feasibil-
ity study
RCRA: Resource Conservation and
Recovery Act of 1976
RREL: Risk Reduction Engineering
Laboratory
SAB: Science Advisory Board
SIC: Standard Industrial Classification
SASS: Source Assessment Sampling
System
SD: spray dryer
SDA: spray dryer absorber
S02: sulfur dioxide
SF6: sulfur hexafluoride
SO,: sulfur oxides
SOv sulfur trioxide
SARA: 1986 Superfund Amendments
and Reauthorization Act
SITE: Superfund Innovative Technol-
ogy Evaluation
TCDD: tetrachlorodibenzo-p-dioxin
TOC: total organic carbon
tpd: tons per day
TRI: Toxics Release Inventory
TCLP: Toxicity Characteristic Leach-
ing Procedure
TEF: toxicity equivalency factor
TEQ: Toxicity Equivalents
TSCA: Toxic Substances Control Act
UV: ultraviolet
L'ST: underground storage tank
VOST: volatile organic sampling train
G-47
AIR & WASTE • Vol. 43 • January 1993 • 73
-------
APPENDIX H
Uncertainty/Sensitivity Analysis
Uncertainty Analysis for EEM 1: Excavation/Removal
Emission Rate for Benzene from Gasoline-Contaminated Soil
Variable parameters are in bold:
Assumptions:
c =
10
ppm
soil concentration of benzene
beta =
1.5
CO
<
E
bulk density of the soil
A=
2500
mA2
emitting surface area
Q=
0.042
mA3/sec
excavation rate
Mfrac=
0.15
%/100
moisture by weight
Equations used:
ER = ERps + ERdiff
ERps = [(Pa)(Mw)(10A6)(Ea)(Q)(ExC)]/[(R)(T)]
ERdiff = [Cs)(10,000)(A)]/{[(Ea)/(Keq)(Kg)] + [(pi)(t)/(De)(Keq)]A0.5}
Cs = (C)(beta)(10A-6)
Et = 1 - (beta/p)
Ea = 1- (beta +
(beta*Mfrac)/p)
Additional Parameters:
Pa=
95.2 mm Hg
vapor pressure of benzene at ambient temp. (298K)
Mw=
78 g/g-mol
molecular weight
Ea=
0.349057 vol/vol
air-filled porosity
Et=
0.433962 vol/vol
total porosity
ExC=
0.10 %/100
soil-gas to atmosphere exchange constant
Ta=
298 degrees K
ambient temperature
Cs=
1.50E-05 g/cmA3
mass loading in bulk soil
Keq=
1 g/g
equilibrium coefficient
Kg=
0.15 cm/sec
gas phase mass transfer coefficient
t=
60 sec
time to achieve best curve fit
De=
0.014872 cmA2/sec
effective diffusivity in air
P=
2.65 g/cmA3
particle density
Point Estimates Using the Above Parameters/Equations:
ERps=
0.585797 g/sec
emission rate from pore space
ERdif=
3.263417 g/sec
emission rate from diffusion
ER =
3.849215 g/sec
total emission rate
H-1
-------
EEM 1 Uncertainty/Sensitivity Analysis
Simulation started on 9/27/96 at 12:06:54
Simulation stopped on 9/27/96 at 12:09:04
Sensitivity Chart
Target Forecast: EEM 1. ER (Pore Space)
Excavation Rate (Q)
49.7%
Sol Bufc Density (beta)
31.7%
Exchange Constant (ExC)
17.3%
:
Particle Density (p)
0.9%
i \ i
Soil Moisture Fraction (Mfrac)
0.3%
i i i
Soil Benzoro Cone. (C)
0.1%
i i i
Benzene Bulk Loading (Cs)
0.0%
i i i
¦ i i
: i i
0% 25% 50% 75% 100%
Measured by Contribution to Variance
Sensitivity Chart
Target Forecast EEM 1. ER (Diffusion)
So:l Bu:k Density (beta)
• Benzene Bu k Leading (Cs)
6 3% :
Particle Densty (p)
1.9% III!
• Soil Moisture Fracton (M'rac)
1-5* i ; : :
i Soil Beraene Cone. (C)
\ ; : ;
1 Excavat'on Rate (O)
0.0% i | 1 i
Exchange Constant (ExC)
0.0% I ' 1 '
i 1 1 1
0% 25% 50% 75% 100%
Measured by Contribution to Variance
Sensitivity Chart
Target Forecast: EEM 1. ER (Total)
Soli Bulk Density (beta)
84 9%
Excavation Rate (Q)
6.3%
¦
Benzene Bulk Loadrrg (Cs)
3.1%
I
Exchange Constant (ExC)
2.6%
1
Particle Density (p)
1.8%
i : i :
Soli Md9ture Fraction (Mfrac)
1.2%
i
Soil Benzene Cone. (C)
0.1%
i : : :
i i i
i i i
i i i
i i i
i i i
0% 25% 50% 75% 100%
Measured by Contribution to Variance
H-2
-------
Forecast: EEM 1. ER (Pore Space)
Cell: B35
Summary:
Certainty Level is 94.99%
Certainty Range is from 0.16 to 2.71 (g/sec)
Display Range is from 0.00 to 3.00 (g/sec)
Entire Range is from 0.07 to 4.48 (g/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.01
Statistics: Value
Trials 10000
Mean 0.98
Median 0.82
Mode
Standard Deviation 0.68
Variance 0.46
Skewness 1.35
Kurtosis 5.17
Coeff. of Variability 0.69
Range Minimum 0.07
Range Maximum 4.48
Range Width 4.41
Mean Std. Error 0.01
Forecast: EEM 1. ER (Pore Space)
e
Q_
66.7
.007
Mean * 0.98
iiiiiiLiiiiniriii
.000
0.75
2.25
3.00
0.00
1.60
Certainty Is 94.99% from 0.16 to 2.71 {9/sec)
Percentiles:
Percentile
(a/sec)
0%
0.07
10%
0.29
20%
0.42
30%
0.54
40%
0.67
50%
0.82
H-3
-------
Forecast: EEM 1. ER (Pore Space) (cont'd)
Cell: B35
Percentile
(a/sec)
60%
0.99
70%
1.20
80%
1.46
90%
1.90
100%
4.48
End of Forecast
H-4
-------
Forecast: EEM 1. ER (Total)
Cell: B37
Summary:
Certainty Level is 95.01 %
Certainty Range is from 1.41 to 7.38 (g/sec)
Display Range is from 0.00 to 9.00 (g/sec)
Entire Range is from 0.59 to 10.30 (g/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.02
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Value
10000
4.17
4.13
1.62
2.62
0.21
2.46
0.39
0.59
10.30
9.71
0.02
10,000 Trials
.021
.015
.010
0.00
Forecast: EEM 1. ER (Total)
Frequency Chart
11 Outliers
- 102
Mean = 4.17
~ <
2.25 4.50 6.75
CertaJnty is 95.01% from 1.41 to 7.38 (g/sec)
Percentiles:
Percentile
(a/sec)
0%
0.59
10%
2.03
20%
2.62
30%
3.15
40%
3.65
50%
4.13
H-5
-------
Forecast: EEM 1. ER (Total) (cont'd) Cell: B37
Percentile
(a/sec)
60%
4.62
70%
5.11
80%
5.61
90%
6.31
100%
10.30
End of Forecast
H-6
-------
Forecast: Effective Diffusivity (De) Cell: B31
Summary:
Display Range is from 0.00 to 0.04 (cmA2/sec)
Entire Range is from 0.00 to 0.04 (cmA2/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.00
Statistics: Value
Trials 10000
Mean 0.02
Median 0.01
Mode
Standard Deviation 0.01
Variance 0.00
Skewness 0.32
Kurtosis 1.92
Coeff. of Variability 0.63
Range Minimum 0.00
Range Maximum 0.04
Range Width 0.04
Mean Std. Error 0.00
10,000 Trials
.019 ¦,
<0
-Q
O
L.
CL
Forecast: Effective Diffusivity (De)
Frequency Chart
0.01
Mean = 0.02
UiUlUIllllIlllIUllIi
0.02
(cnY^sec)
Ilk,,
0 Outliers
190
Percentiles:
Percentile
0%
10%
20%
30%
40%
50%
60%
70%
(cmA2/sec)
0.00
0.00
0.01
0.01
0.01
0.01
0.02
0.02
H-7
-------
Forecast: Effective Diffusivity (De)
(cont'd)
Cell:
B31
End of Forecast
Percentile
80%
90%
100%
(cmA2/sec)
0.03
0.03
0.04
H-8
-------
Forecast: Air-Filled Porosity (Ea)
Cell: B23
Summary:
Display Range is from 0.05 to 0.60 (vol/vol)
Entire Range is from 0.07 to 0.59 (vol/vol)
After 10,000 Trials, the Std. Error of the Mean is 0.00
Statistics: Value
Trials 10000
Mean 0.35
Median 0.35
Mode
Standard Deviation 0.13
Variance 0.02
Skewness -0.03
Kurtosis 1.88
Coeff. of Variability 0.37
Range Minimum 0.07
Range Maximum 0.59
Range Width 0.52
Mean Std. Error 0.00
Forecast: Air-Filled Porosity (Ea)
0 Outliers
166
124
3 i
.008
¦O
to
¦O
o
k_
Mean = 0.35
.000
0.46
0.60
0.33
0.05
0.19
(vol/vol)
Percentiles:
Percentile
(vol/vol)
0%
0.07
10%
0.17
20%
0.22
30%
0.26
40%
0.31
50%
0.35
60%
0.39
70%
0.44
H-9
-------
Forecast: Air-Filled Porosity (Ea) (cont'd)
Cell: B23
End of Forecast
Percentile
80%
90%
100%
(vol/vol)
0.48
0.52
0.59
H-10
-------
Forecast: Total Porosity (Et)
Cell: B24
Summary:
Display Range is from 0.20 to 0.65 (vol/vol)
Entire Range is from 0.21 to 0.64 (vol/vol)
After 10,000 Trials, the Std. Error of the Mean is 0.00
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Value
10000
0.43
0.43
0.11
0.01
-0.02
1.86
0.25
0.21
0.64
0.43
0.00
10,000 Trials
.015
| .011
I ^
i 2
.004
Forecast: Total Porosity (Et)
Frequency Chart
0.43
(vol/vol)
0 Outliers
- 148
4
0.65
ro
3
3
Percentiles:
Percentile
(vol/vol)
0%
0.21
10%
0.28
20%
0.32
30%
0.36
40%
0.40
50%
0.43
60%
0.47
70%
0.51
H-11
-------
Forecast: Total Porosity (Et) (cont'd)
Cell: B24
End of Forecast
Percentile
80%
90%
100%
(vol/vol)
0.55
0.58
0.64
H-12
-------
Forecast: EEM 1. ER (Diffusion)
Cell: B36
Summary:
Certainty Level is 95.04%
Certainty Range is from 1.10 to 5.23 (g/sec)
Display Range is from 0.00 to 7.00 (g/sec)
Entire Range is from 0.47 to 6.64 (g/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.01
Statistics: Value
Trials 10000
Mean 3.19
Median 3.22
Mode
Standard Deviation 1.16
Variance 1.35
Skewness -0.04
Kurtosis 2.13
Coeff. of Variability 0.36
Range Minimum 0.47
Range Maximum 6.64
Range Width 6.17
Mean Std. Error 0.01
Forecast: EEM 1. ER (Diffusion)
; 10,000 Trials
I 023 "I
Frequency Chart
0 Outliers
226
.017
- 169
.011
.006
56.5
Mean = 3.19
.000
5.25
7.00
0.00
1.75
3.50
Certainty is 95.04% from 1.10 to 5.23 (gteec)
Percentiles:
Percentile
(a/sec)
0%
0.47
10%
1.59
20%
2.05
30%
2.46
40%
2.85
50%
3.22
H-13
-------
Forecast: EEM 1. ER (Diffusion) (cont'd) Cell: B36
End of Forecast
Percentile
60%
70%
80%
90%
100%
(q/sec)
3.57
3.94
4.28
4.72
6.64
H-14
-------
Assumptions
Assumption: Soil Benzene Cone. (C)
Cell: C5
Normal distribution with parameters:
Mean 10.00
Standard Dev. 1.00
Selected range is from -Infinity to + Infinity
Mean value in simulation was 10.00
Soil 8*ni*
-------
Assumption: Exchange Constant (ExC)
Cell: B25
Triangular distribution with parameters:
Minimum
Likeliest
Maximum
Selected range is from 0.10 to 0.33
Mean value in simulation was 0.18
Eietiang* ContUnt (ExC)
0.10
0.10
0.33
Assumption: Benzene Bulk Loading (Cs)
Normal distribution with parameters:
Mean
Standard Dev.
1.50E-05
1.50E-06
Selected range is from -Infinity to + Infinity
Mean value in simulation was 1.50E-5
Cell: B27
Bulk Loading (Cs)
i otc s i ?rt » i vxi i nt t i est.s
Assumption: Particle Density (p)
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 2.65
Cell: B32
2.52
2.78
Puttclt D«nttty (p)
End of Assumptions
H-16
-------
Uncertainty Analysis for EEM 2: Thermal Desorption
Emission Rate for Benzene from Gasoline-Contaminated Soil
Variable parameters are in bold:
Assumptions: C= 10.00 ppm
F= 27200 kg/hr
V= 99.50 %
CE= 99.50 %
soil concentration of benzene
mass rate of soil treated
percentage of benzene volatilized
percent efficiency of control devices
Equations used:
ER (g/hr) = (C/1000)(F)(V/100)(1-(CE/100))
Point Estimate Using the Above Parameters/Equation:
ER= 1.353 g/sec total emission rate
H-17
-------
EEM 2 Uncertainty/Sensitivity Analysis
Simulation started on 9/27/96 at 12:34:02
Simulation stopped on 9/27/96 at 12:35:30
1 Control Efficiency (CE)
Soil Cone, of Benzene (C)
Soil Feed Rate (F)
Volatilized Fraction (V)
Sensitivity Chart
Target Forecast: EEM 2. ER (Total)
93.3°/
25% 50% 75%
Measured by Contribution to Variance
H-18
-------
Forecast: EEM 2. ER (Total)
Cell: B14
Summary:
Certainty Level is 95.05%
Certainty Range is from 0.320 to 2.540 (g/sec)
Display Range is from 0.000 to 3.000 (g/sec)
Entire Range is from 0.030 to 3.552 (g/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.006
Statistics: Value
Trials 10000
Mean 1.362
Median 1.338
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
0.576
0.331
0.21
2.63
0.42
0.030
3.552
3.522
0.006
10,000 Trials
023 -)
Forecast: EEM 2. ER (Total)
Frequency Chart
18 Outliers
—I- 233
017
174
A 012
CO
116
""Jill
O
I. 58.2 ^
Certainty is 95.05% from 0 320 to 2.540 (gfeec)
Percentiles:
Percentile
0%
10%
20%
30%
40%
50%
(a/sec)
0.030
0.611
0.849
1.030
1.192
1.338
H-19
-------
Forecast: EEM 2. ER (Total) (cont'd)
Cell: B14
End of Forecast
Percentile
60%
70%
80%
90%
100%
(a/sec)
1.495
1.665
1.860
2.129
3.552
H-20
-------
Assumptions
Assumption: Control Efficiency (CE)
Triangular distribution with parameters:
Minimum
Likeliest
Maximum
Selected range is from 99.00 to 99.99
Mean value in simulation was 99.50
Cell: C8
99.00
99.50
99.99
Control Efficiency (CE)
K00 W 3i WW W74
Assumption: Volatilized Fraction (V)
Triangular distribution with parameters:
Minimum
Likeliest
Maximum
Selected range is from 99.00 to 99.99
Mean value in simulation was 99.50
Cell: C7
99.00
99.50
99.99
Volitlllz«d Fraction (V)
M }i 90 60 99 74
Assumption: Soil Feed Rate (F)
Uniform distribution with parameters:
Minimum
Maximum
24,480.00
29,920.00
Mean value in simulation was 27,200.00
Soil Fm4 Rat* (F)
24 410 00 tt*40 00 27JOOOO »M000 »»W00
Cell: C6
Assumption: Soil Cone, of Benzene (C)
Normal distribution with parameters:
Mean
Standard Dev.
10.00
1.00
Selected range is from -Infinity to + Infinity
Mean value in simulation was 10.00
Soli Cone, of B*nx*n* (C)
Cell: C5
End of Assumptions
H-21
-------
Uncertainty Analysis for EEM 3: Soil Vapor Extraction
Emission Rate for Benzene from Gasoline-Contaminated Soil
Variable parameters are in bold:
Assumptions:
Q = 85 mA3/min vapor extraction rate
Equations used:
ER (g/sec) = (Cg)(Q/60)(10A-6)
Cg (ug/mA3) = [(Ps)(Mw)(10A9)]/[(R)(Ts)]
Additional Parameters:
Pa= 95.2 mm Hg vapor pressure of benzene at ambient temp. (298K)
Ps= 77.1 mmHg vapor pressure of benzene at soil temp. (293K)
Mw= 78 g/g-mol molecular weight
Ta= 298 degrees K ambient temperature
Ts= 293 degrees K soil temperature
Point Estimates Using the Above Parameters/Equations:
ER= 0.466 g/sec total emission rate
H-22
-------
EEM 3 Uncertainty/Sensitivity Analysis
Simulation started on 9/27/96 at 12:55:39
Simulation stopped on 9/27/96 at 12:56:34
Vapor Extract. Rate (Q)
Soil Cone, of Benzene (C)
i
Sensitivity Chart
Target Forecast: EEM 3. ER (Total)
I 100.0%
0.0% I
25% 50% 75%
Measured by Contribution to Variance
H-23
-------
Forecast: EEM 3. ER (Total)
Cell: B20
Summary:
Certainty Level is 95.08%
Certainty Range is from 0.333 to 0.599 (g/sec)
Display Range is from 0.325 to 0.625 (g/sec)
Entire Range is from 0.326 to 0.606 (g/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.001
Statistics: Value
Trials 10000
Mean 0.466
Median 0.466
Mode
Standard Deviation 0.081
Variance 0.007
Skewness 0.00
Kurtosis 1.80
Coeff. of Variability 0.17
Range Minimum 0.326
Range Maximum 0.606
Range Width 0.280
Mean Std. Error 0.001
| Forecast: EEM 3. ER (Total)
! 10,000 Trials Frequency Chart 0 Outliers
011 1 iTTTi—i I~M i ' 110
.008 J 82 5
* i ?
I S ! n
¦ .o .006 -u- -* 55 A
« i =
*° I 3
> .003 L. 27.5 5
! <
i Mean ¦ 0.466 j
000 ~ < 0
0.325 0 400 0 475 0.550 0 625
! Certainty » 95 08% trom 0 333 to 0,599 Iglsnc)
Percentiles:
Percentile (a/sec)
0% 0.326
10% 0.354
20% 0.382
30% 0.410
40% 0.438
50% 0.466
H-24
-------
Forecast: EEM 3. ER (Total) (cont'd) Cell: B20
Percentile
(a/sec)
60%
0.494
70%
0.522
80%
0.550
90%
0.578
100%
0.606
End of Forecast
H-25
-------
Assumptions
Assumption: Soil Cone, of Benzene (C)
Cell: C5
Normal distribution with parameters:
Mean 10.00
Standard Dev. 1.00
Selected range is from -Infinity to + Infinity
Mean value in simulation was 10.00
Soil Cone, of Banyan* (C)
Assumption: Vapor Extract. Rate (Q)
Cell: C6
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 85.00
Vapor Extract. Rat* (Q)
59.50
110.50
End of Assumptions
H-26
-------
Uncertainty Analysis for EEM 4: In-Situ Biodegradation
Emission Rate for Benzene from Gasoline-Contaminated Soil
Variable parameters are in bold:
Assumptions: C= 10
A = 2500
D = 5
beta = 1.5
Mfrac= 0.15
ppm soil concentration of benzene
mA2 surface area
m excavation depth
g/cmA3 bulk density of the soil
%/100 moisture by weight
Equations used:
ER (g/sec) = (Cg)(Q/60)(10A-6)
Cg (ug/mA3) = [(Ps)(Mw)(10A9)]/[(R)(Ts)]
Q (mA3/min) = (1.0/1440)(Sv)(Ea)
Additional Parameters:
Pa=
95.2 mm Hg
vapor pressure of benzene at ambient temp. (298K)
Ps=
77.1 mmHg
vapor pressure of benzene at soil temp. (293K)
MW=
78 g/g-mol
molecular weight
Ta=
298 degrees K
ambient temperature
Ts=
293 degrees K
soil temperature
Ea=
0.349057 vol/vol
air-filled porosity
P=
2.65 g/cmA3
particle density
pv=
1.0 vol/vol
number of pore volumes vented per day
Point Estimates Using the Above Parameters/Equations:
Cg= 329131 ug/mA3 saturated vapor concentration
Q= 3 mA3/min exhaust flow rate
ER= 0.017 g/sec total emission rate
H-27
-------
EEM 4 Uncertainty/Sensitivity Analysis
Simulation started on 9/27/96 at 13:13:29
Simulation stopped on 9/27/96 at 13:15:09
Sensitivity Chart
Target Forecast: EEM 4: ER (Total)
Bulk Soil Density (beta)
HUH
Pore Volumes/Day (pv)
i i
i i
Particle density (p)
1-5% | ;
i i
i i
Moisture Fraction (Mfrac)
04% | ;
i i
i i
Soil Cone, of Benzene (C)
oo% j ;
!
i
i i
i i
i i
i i
i i
i i
i <
i i
i i
i i
0% 25% 50% 75% 100
Measured by Contribution to Variance
H-28
-------
Forecast: Air-Filled Porosity
Cell: B22
Summary:
Certainty Level is 95.11 %
Certainty Range is from 0.13 to 0.56 (vol/vol)
Display Range is from 0.05 to 0.60 (vol/vol)
Entire Range is from 0.08 to 0.59 (vol/vol)
After 10,000 Trials, the Std. Error of the Mean is 0.00
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Value
10000
0.35
0.35
0.13
0.02
-0.03
1.88
0.36
0.08
0.59
0.52
0.00
10,000 Trials
016 n
Forecast: Air-Filled Porosity
Frequency Chart
0 Outliers
157
0.19 0.33 0.46
Certainty is 95.11 % from 0.13 to 0.S6 (voKVot)
Percentiles:
Percentile
0%
10%
20%
30%
40%
50%
(vol/vol)
0.08
0.18
0.22
0.26
0.31
0.35
H-29
-------
Forecast: Air-Filled Porosity (cont'd)
Cell: B22
End of Forecast
Percentile
60%
70%
80%
90%
100%
(vol/vol)
0.39
0.43
0.48
0.52
0.59
H-30
-------
Forecast: Saturated Vapor Cone. (Cg) Cell: B27
Summary:
Display Range is from 329131 to 329131 (ug/mA3)
Entire Range is from 329131 to 329131 (ug/mA3)
After 10,000 Trials, the Std. Error of the Mean is 0
Statistics: Value
Trials 10000
Mean 329131
Median 329131
Mode 329131
Standard Deviation 0
Variance 0
Skewness 0.00
Kurtosis + Infinity
Coeff. of Variability 0.00
Range Minimum 329131
Range Maximum 329131
Range Width 0
Mean Std. Error 0.00
10,000 Trials
1 000
750 — .
.500 _ .
i
.250 J_ .
.000
~
329131
Forecast: Saturated Vapor Cone. (Cg)
Frequency Chart
0 Outliers
10000
n
.o
e
n
329131
i
329131
Percentiles:
Percentile
(ua/mA3)
0%
329131
10%
329131
20%
329131
30%
329131
40%
329131
50%
329131
60%
329131
70%
329131
H-31
-------
Forecast: Saturated Vapor Cone. (Cg) (cont'd)
Cell: B27
Percentile
80%
90%
100%
End of Forecast
(uq/mA3)
329131
329131
329131
H-32
-------
Forecast: Exhaust Flow Rate (Q)
Cell: B28
Summary:
Certainty Level is 95.02%
Certainty Range is from 1 to 7 (mA3/min)
Display Range is from 0 to 8 (mA3/min)
Entire Range is from 0 to 10 (mA3/min)
After 10,000 Trials, the Std. Error of the Mean is 0
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Forecast: Exhaust Flow Rate (Q)
10,000 Trials
.023
Frequency Chart
80 Outliers
—i- 220
.017
011
006
Mean = 3
.000
2
0
4
6
8
Certainty is 95.02% from 1 to 7 (fTv*3/m«ri)
Percentiles:
Percentile
(mA3/min)
0%
0
10%
1
20%
2
30%
2
40%
3
50%
3
Value
10000
3
3
2
3
0.71
3.05
0.50
0
10
9
0.02
H-33
-------
Forecast: Exhaust Flow Rate (Q) (cont'd)
Cell: B28
Percentile
60%
70%
80%
90%
100%
End of Forecast
(m^3/min)
3
4
5
6
10
H-34
-------
Forecast: EEM 4: ER (Total)
Cell: B29
Summary:
Certainty Level is 95.01 %
Certainty Range is from 0.005 to 0.039 (g/sec)
Display Range is from 0.000 to 0.045 (g/sec)
Entire Range is from 0.002 to 0.052 (g/sec)
After 10,000 Trials, the Std. Error of the Mean is 0.000
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Value
10000
0.018
0.017
0.009
0.000
0.71
3.05
0.50
0.002
0.052
0.051
0.000
Forecast: EEM 4: ER (Total)
Outliers
10,000 Trials
Mean ¦ 0 018
miimuirann
o.ooo
0.011 0.023 0.034
CertaknTy b 95 01% from 0.005 to 0.039 (gfcec)
Percentiles:
Percentile
0%
10%
20%
30%
40%
50%
(g/sec)
0.002
0.008
0.010
0.012
0.014
0.017
H-35
-------
Forecast: EEM 4: ER (Total) (cont'd) Cell: B29
End of Forecast
Percentile
60%
70%
80%
90%
100%
(q/sec)
0.019
0.022
0.026
0.031
0.052
H-36
-------
Assumptions
Assumption: Soil Cone, of Benzene (C)
Cell: C5
Normal distribution with parameters:
Mean 10.00
Standard Dev. 1.00
Selected range is from -Infinity to + Infinity
Mean value in simulation was 10.00
Soli Cone, of (C)
700 »»
SO 13 90
Assumption: Bulk Soil Density (beta)
Cell: C8
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 1.50
Bulk Soil OtntKy (b«ta)
1.00
2.00
Assumption: Moisture Fraction (Mfrac)
Cell: C9
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 0.15
Molftur* Friction (Mfr*e)
0.12
0.18
Assumption: Particle density (p)
Cell: B23
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 2.65
Parttcl* density (p)
2.52
2.78
H-37
-------
Assumption: Pore Volumes/Day (pv)
Cell: B24
Triangular distribution with parameters:
Minimum
Likeliest
Maximum
Selected range is from 0.3 to 2.0
Mean value in simulation was 1.1
Por* VotumM/Day (pv)
0.3
1.0
2.0
End of Assumptions
H-38
-------
Uncertainty Analysis for EEM 5: Ex-Situ Biodegradation
Emission Rate for Benzene from Gasoline-Contaminated Soil
Variable parameters are in bold:
Assumptions: continuous slurry process is used.
C= 10 ppm soil concentration of benzene
Mr= 600 kg/hr mass feed rate for soil treatment
V= 0.62 %/100 percentage of contaminant volatilized
Equations used:
ER (g/hr) = (C/1000)(Mr)(V)
Point Estimate Using the Above Parameters/Equation:
ER= 3.720 g/hr total emission rate
H-39
-------
EEM 5 Uncertainty/Sensitivity Analysis
Simulation started on 9/27/96 at 13:26:12
Simulation stopped on 9/27/96 at 13:27:30
Fraction Volatilized (V)
Soil Cone, of Benzene (C)
Mass Feed Rate (Mr)
Sensitivity Chart
Target Forecast: EEM 5: ER (Total)
25% 50% 75%
Measured by Contribution to Variance
H-40
-------
Forecast: EEM 5: ER (Total)
Cell: B14
Summary:
Certainty Level is 95.01 %
Certainty Range is from 1.800 to 5.820 (g/hr)
Display Range is from 1.000 to 7.000 (g/hr)
Entire Range is from 1.312 to 6.999 (g/hr)
After 10,000 Trials, the Std. Error of the Mean is 0.011
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Value
10000
3.599
3.555
1.124
1.263
0.24
2.22
0.31
1.312
6.999
5.687
0.011
10,000 Trials
020 -j
Forecast EEM 5: ER (Total)
Frequency Chart
0
.o
e
L.
Q.
0 Outliers
- 196
IIIIII1IIIIIIILIIIIILIII]
2.500 4.000 5.500
Certainty Is 95.01% from 1.800 to 5.820 (#ir)
Percentiles:
Percentile
0%
10%
20%
30%
40%
50%
(g/hr)
1.312
2.130
2.487
2.834
3.193
3.555
H-41
-------
Forecast: EEM 5: ER (Total) (cont'd)
Cell: B14
Percentile
60%
70%
80%
90%
100%
(g/hr)
3.902
4.251
4.652
5.157
6.999
End of Forecast
H-42
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Assumptions
Assumption: Soil Cone, of Benzene (C)
Cell: C6
Normal distribution with parameters:
Mean 10.00
Standard Dev. 1.00
Selected range is from -Infinity to + Infinity
Mean value in simulation was 10.00
Soli Cone, of (C)
SO <300
Assumption: Mass Feed Rate (Mr)
Cell: C7
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 600.00
Mm* Fwd R«t« (Mr)
540.00
660.00
MOO 570 00 <00 00 <30 30 M000
Assumption: Fraction Volatilized (V)
Cell: C8
Uniform distribution with parameters:
Minimum
Maximum
Mean value in simulation was 0.60
Friction Volatilli*d (V)
0.30
0.90
End of Assumptions
H-43
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Uncertainty Analysis for EEM 6: Incineration
Emission Rate for Benzene from Gasoline-Contaminated Soil
Variable parameters are in bold:
Assumptions: continuous slurry process is used
C= 10.00 mg/kg
CE= 99.5 %
Mw= 4500 kg/hr
Equations used:
ER (g/hr) = (1-(DRE/100))(C/1000)(mw)
Point Estimate Using the Above Parameters/Equation:
ER= 0.225 g/hr total emission rate
soil concentration of benzene
control (destruction & removal) efficiency
mass feed rate for soil treatment
H-44
-------
EEM 6 Uncertainty/Summary
Simulation started on 9/27/96 at 13:44:08
Simulation stopped on 9/27/96 at 13:45:29
Sensitivity Chart
Target Forecast: EEM 6: ER (Total)
Control Efficiency (CE)
93.3%
Soil Cone, of Benzene (C)
5.0%
¦
Mass Feed Rate (Mw)
1.7%
i : : :
1 ! !
i i
i i
i i
i
L : : I | I :
0% 25% 50% 75% 100%
I
I Measured by Contribution to Variance
H-45
-------
Forecast: EEM 6: ER (Total) Cell: B14
Summary:
Certainty Level is 95.04%
Certainty Range is from 0.052 to 0.418 (g/hr)
Display Range is from 0.000 to 0.500 (g/hr)
Entire Range is from 0.008 to 0.554 (g/hr)
After 10,000 Trials, the Std. Error of the Mean is 0.001
Statistics:
Trials
Mean
Median
Mode
Standard Deviation
Variance
Skewness
Kurtosis
Coeff. of Variability
Range Minimum
Range Maximum
Range Width
Mean Std. Error
Value
10000
0.227
0.224
0.095
0.009
0.19
2.65
0.42
0.008
0.554
0.546
0.001
Forecast EEM 6: ER (Total)
10,000 Trials Frequency Chart 19 Outliers
111
I
J
Illllliliii«it.i
0.000 0.125 0,250 0.375 0,500
Certainty b 95.04% from 0 052 to 0.418 (g4u)
Percentiles:
Percentile fg/hr)
0% 0.008
10% 0.101
20% 0.141
30% 0.172
40% 0.199
50% 0.224
H-46
-------
Forecast: EEM 6: ER (Total) (cont'd) Cell: B14
Percentile
(a/hr)
60%
0.249
70%
0.276
80%
0.309
90%
0.354
100%
0.554
End of Forecast
H-47
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Assumptions
Assumption: Soil Cone, of Benzene (C)
Cell: C6
Normal distribution with parameters:
Mean 10.00
Standard Dev. 1.00
Selected range is from -Infinity to + Infinity
Mean value in simulation was 10.00
Soil Cone, of B*nz«n« (C)
Assumption: Control Efficiency (CE)
Triangular distribution with parameters:
Minimum
Likeliest
Maximum
Selected range is from 99.00 to 99.99
Mean value in simulation was 99.50
Cell: C7
99.00
99.50
99.99
Control Efficiency (CE)
» MM M 74 99 99
Assumption: Mass Feed Rate (Mw)
Uniform distribution with parameters:
Minimum 4,050.00
Maximum 4,950.00
Mean value in simulation was 4,500.00
Cell: C8
Mau FMd Rat* (Mw)
End of Assumptions
H-48
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completin.
REPORT NO.
PA-600/R-97-116
3. Rl
TITLE AND SUBTITLE
Air Emissions from the Treatment of Soils Conta-
minated with Petroleum Fuels and Other Substances
6. PERFORMING ORGANIZATION CODE
. REPORT DATE
October 1997
authoris) Eklund, P. Thompson, A. Inglis, W. Whee-
ess, and W.Horton (Radian); and S.Roe (Pechan)
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING OROANIZATION NAME AND ADDRESS
rtadian Corp.
0. Box 201088
Austin, TX 78720
E. H. Pechan and Assoc.
2880 Sunrise Blvd, No. 220
Rancho Cordova, CA 95742
10. PROGRAM ELEMENT NO.
1. CONTRACT/GRANT NO. CO_ nO-OlfiO
Task 262 (Radian) and 68- .
D3-0035 Task 11-92 (Pechan)
12. SPONSORING AGENCY NAME AND ADDRESS
PA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 10/94 - 10/96
14. SPONSORING AGENCY CODE
EPA/600/13
Thorneloe, Mail Drop 63,
dtd July 1992.
is.supplementary notes ^pp(3D proiect officer is Susan A.
919/541-2709. The report updates EPA-600/R-92-124,
i6. abstract rep0rt updates a 1992 report that summarizes available information on
air emissions from the treatment of soils contaminated with fuels. Soils contamina-
ted by leaks or spills of fuel products, such as gasoline and jet fuel, are a nation-
wide concern. Air emissions during remediation are a potential problem because of
the volatile nature of many of the fuel components and the remediation processes
themselves, which may promote or result in contaminant transfer to the vapor
phase. Limited information also is included on air emissions from the treatment of
soils contaminated with hazardous wastes. The report will allow staff from state anc
local regulatory agencies, as well as staff from EPA regional offices, to assess the
different options for cleaning up soil contaminated with fuels. Seven general reme-
diation approaches are addressed in this report. For each approach, information is
presented about the remediation process, the typical air emission species of con-
cern and their release points, and the available air emissions data. Control technol-j
ogies for each remediation approach are identified, and their reported efficiencies
are summarized. Cost data are given for each remediation approach and for its
associated control technologies. Emission estimation methods (EEMs) for each re-
mediation approach are presented along with a brief case study.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group 1
Air Pollution Volatility
Petroleum Products Organic Compounds
Fuels Estimating
Soils Cost Effectiveness
Contamination
Emission
Air Pollution Control
Stationary Sources
Volatile Organic Com-
pounds (VOCs)
13B 20 M
11G 07 C
21D, 211
08G.08M 14 A
14G
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES 1
- 482 I
20. SECURITY CLASS (This page)
Unclassified
22. PRICE I
EPA Form 2220-1 (9-73)
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